SUMMARY Immunoglobulin G4-related sialadenitis (IgG4-RS) is a newly recognized immune-mediated disease and one of immunoglobulin G4-related diseases (IgG4-RD). Our multidisciplinary research group investigated the clinicopathological characteristics and diagnosis of IgG4-RS during the past 10 years. Clinically, it showed multiple bilateral enlargement of major salivary glands (including sublingual and accessory parotid glands) and lacrimal glands. The comorbid diseases of head and neck region including rhinosinusitis, allergic rhinitis, and lymphadenopathy were commonly seen, which could occur more early than enlargement of major salivary glands. Internal organ involvements, such as autoimmune pancreatitis, sclerosing cholangitis, and interstitial pneumonia could also be seen. Thirty-five (38.5%)patients had the symptom of xerostomia. Saliva flow at rest was lower than normal. Secretory function was reduced more severely in the submandibular glands than in the parotid glands. Serum levels of IgG4 were elevated in almost all the cases and the majority of the patients had increased IgE levels. CT, ultrasonography, and sialography showed their imaging characteristics. Histologically it showed marked lymphoplasmacytic inflammation, large irregular lymphoid follicles with expanded germinal centers, prominent cellular interlobular fibrosis, eosinophil infiltration, and obliterative phlebitis. Their immunohistological examination showed marked IgG-positive and IgG4-positive plasma cell infiltration and high IgG4/IgG ratio. The disease could be divided into three stages according to severity of glandular fibrosis. The serum IgG4 level was higher and the saliva secretion lower as glandular fibrosis increased. IgG4-RS should be differentiated from other diseases with enlargement of major salivary gland and lacrimal gland, such as primary Sjögren syndrome, chronic obstructive submandibular sialadenitis, and eosinophilic hyperplastic lymphogranuloma.

Objective: To investigate the BRAF gene mutations in ameloblastic fibroma (AF), and to further analyze the relationship between the BRAF mutation and clinical characteristics so as to provide new reference to the study of AF’s molecular pathology. Methods: Sixteen cases diagnosed as AF at the Department of Oral Pathology, Peking University School of Stomatology between January 1990 and December 2017 were collected. Genomic DNA was extracted from formalin-fixed, paraffin embedded tissues using the QIAamp DNA Mini Kit (Qiagen, Germany) according to the manufacturer’s instructions. Polymerase chain reaction (PCR) and direct sequencings were used to detect the BRAF gene mutations. The clinicopathological data, such as the age, location of the lesion, symptoms and treatments were retrospectively analyzed. Results: The sixteen cases of AF involved nine women and seven men aged 2-67 years. Three lesions occurred in the maxilla and thirteen in the mandible. The most common presenting symptom of AF was a painless slowly enlarging mass with swelling. Ten patients received conservative treatment and the other six patients received radical surgery. Three cases relapsed during the study period. BRAF gene mutation was found in sixteen of all the sixteen samples analyzed (100%). The BRAF mutation was a point mutation with a thymine-adenine transversion at nucleotide 1 799 of 15 exons, resulting in a change at residue 600 that substituted glutamine for valine. This mutation was the strongest activator of the downstream RAS/RAF/MEK/ERK-MAPK signaling pathway. This helped to bring about a gain-of-function mutation due to a V600E substitution. Many studies identified that BRAF regulated survival, apoptosis, and proliferation of cells by inducing MAPK pathways activation. For the existing cases, none of the age, sex, location, recurrence and treatments had a statistically significant correlation with BRAF mutation. Conclusion: Our findings demonstrated high prevalence of BRAF V600E mutation in AF. The pathogenic role remains to be clarified.

Objective:To screen for BMP2 mutation with functional impact in patients with congenital tooth agenesis and to make oral and skeletal phenotype record and functional analysis with in vitro experiments. Methods: We enrolled eighteen patients with congenital tooth agenesis. The medical and dental history was collected,and clinical and dental examinations including the X-ray examination of oral-facial and skeletal bone were performed for the phenotypic analysis. Blood samples were collected to extract DNA and whole exome sequencing was conducted. The genes involved in oral-facial development and congenital skeletal diseases were investigated for mutation screening. The mutations with functional impact were then investigated. In one patient, the BMP2 mutation with putative functional impact was selected for functional analysis. Wild type and mutant BMP2 plasmids with green fluorescent protein (GFP) tag were constructed and transfected into HEK293T cells. Subcellular protein distribution was observed under laser scanning confocal microscope. The activation of downstream SMAD1/5/9 phosphorylation by BMP2 was detected by Western blotting to investigate the functional impact and genetic pathogenicity. Results: BMP2 mutation NM_001200.3:c.393A>T(p.Arg131Ser), rs140417301 was detected in one patient with congenital tooth agenesis, while for other genes involved in oral-facial development and congenital skeletal diseases, no functionally significant mutation was found. The proband’s parents didn’t carry this mutation. The father had normal dentition, while the mother lacked one premolar, and both the parents showed normal palate and maxilla. The patient also had maxillary hypoplasia in both sagittal and coronal planes, palatal dysmorphology, and malocclusion, and was diagonsed with osteopenia after the X-ray examnination of his skeletal bone. Functional analysis showed this mutation had normal subcelluar localization but reduced phosphorylation of SMAD1/5/9 (reduction by 32%, 22%, and 27% in three independent replicates). Taken together with family co-segregation, this mutaion was considered as “likely pathogenic”. Conclusion: BMP2 mutation c.393A>T (p. Arg131Ser) affects bone morphogenetic protein signaling activity, and may affect the number of teeth, growth of maxilla and palate, and bone mineral density.

Objective: To evaluate the diagnostic efficiency of oral mucosa disease, especially oral squamous cell carcinoma (OSCC) and oral potential malignant disorders (OPMDs) by DNA cytometry compared with histopathological diagnosis, so as to find a convenient, simple and low-invasive method for screening and follow-up. Methods: 203 subjects with OSCC, OPMDs and other oral mucosa disease without dysplasia according to the inclusion criteria and exclusion criteria were recruited from Peking University School and Hospital of Stomatology. The mean age was (52.44±13.55) years, 98 males and 105 females. Brush biopsy was taken before scalpel biopsy at the same site. The brush biopsy sample was screened by moticytometer system for DNA cytometry after Feulgen stain, and histopathological examination were taken for the scalpel tissue. Data from DNA cytometry were used to calculate the parameters, such as sensitivity, specificity, positive and negative predictive values, odds ratios, Youden index (YI), positive and negative likelihood ratios, compared with the golden standard, histopathological diagnosis. DNA cytometry and histopathological diagnosis were performed back to back. Results: Totally, 42 OSCC and 4 tumor in situ (TIS), 39 oral leukoplakia (OLK) with dysplasia (17 mild dysplasia, 13 medium dysplasia and 9 severe dysplasia), 29 OLK with hyperplasia, 1 verrucous OLK, 83 oral lichen planus (OLP) and 5 inflammation were included in our research. We grouped the OSCC, TIS and dysplasia as the positive group and others without dysplasia as the negative group, the sensitivity of DNA cytometry was 79.07%, the specificity was 81.20%, and the diagnostic accuracy was 80.30%,We grouped the OSCC and TIS as the tumor group, OLP, OLK with hyperplasia and inflammation as the non-tumor group, The sensitivity of DNA cytometry in diagnosing OSCC and TIS was 95.65%, and the specificity was 81.2%, The diagnostic accuracy was 85.28%. positive predictive values 66.67%, negative predictive values 97.94%, ratio odds 95, positive likelihood ratio 5.09, negative likelihood ratio 0.05, and Youden index 0.77. For the dysplasia, we grouped the different dysplasia together as the dyaplasia group, OLP, OLK with hyperplasia and inflammation as the non-tumor group, the sensitivity of DNA cytometry in diagnosing dyaplasia is 60%, the specificity is 81.2%. The diagnostic accuracy is 75.8%, positive predictive values 52.17%, negative predictive values 85.59%, ratio odds 6.48,positive likelihood ratio 3.19, negative likelihood ratio 0.49, and Youden index 0.41. Conclusion: DNA cytometry is convenient and low-invasive, which can be used as an adjuvant method for screening the early OSCC and OPMDs, monitoring the prognosis of OSCC after surgery. Further large-scale and long period prospective studies are necessary to validate the better value of DNA cytometry.

Objective: To investigate the effect of long-term resistance exercise of hindlimb on mechan-ical hyperalgesia of bilateral masseter muscle in rats with or without occlusal interference. Methods: Six-teen male Sprague-Dawley rats (220-250 g) were randomly divided into four groups: the naive control group, na?ve exercise group, occlusal interference control group, and occlusal interference exercise group. The rats in occlusal interference groups (occlusal interference control group and occlusal interference exercise group) obtained occlusal interference with 0.4 mm-thick crowns bonded to the right maxillary first molars. The rats in exercise groups (na?ve exercise group and occlusal interference exercise group) performed squat-type resistance exercises for 30 minutes, once a day, 5 days/week, lasting for 14 weeks. Resistance exercise was recorded every day. Mechanical withdrawal thresholds of bilateral masseter muscle were tested per week by use of modified electronic von-frey anesthesiometer. The rats were weighed per week. After the 14-week exercise, the muscle strength of the hindlimb was tested with a grip strength meter. Muscle (gastrocnemius and soleus) weight of bilateral hindlimb and length of bilateral fibula of the rats were obtained. The muscle-mass/body-mass ratios and muscle-mass/fibula-length ratios were calculated. Results: Between the na?ve control group and na?ve exercise group, there was no sig-nificant difference in the mechanical withdrawal thresholds of bilateral masseter muscle for the 0-4 weeks (P>0.05). During the 5-14 weeks, the mechanical withdrawal thresholds of the rats in the na?ve exercise group were higher than those in the na?ve control group (P<0.05). Between the occlusal interference control group and occlusal interference exercise group, there was no significant difference in the mechanical withdrawal thresholds of bilateral masseter muscle for the 0-6 weeks (P>0.05). During the 7-14 weeks, the mechanical withdrawal thresholds of rats in the na?ve exercise group were higher than those in the occlusal interference control group (P<0.05). After the 14-week exercise, the body mass of the rats in non-exercise group (the na?ve control group and occlusal interference control group) were larger than those in exercise group [(462±6) g vs. (418±14) g, P<0.05]. And the muscle strength of hindlimb of the rats in exercise group were bigger than those in non-exercise group [(6.75±0.13) N vs. (5.41±0.15) N, P<0.01]. Conclusion: Long-term resistance exercise can increase mechanical withdrawal thresholds of the bilateral masseter muscle in rats with or without masseter muscle mechanical hyperalgesia.

Objective: To compare cell adhesion, proliferation and odontoblastic differentiation of human dental pulp cells (hDPCs) on electrospun collagen nanofibrous matrix (Col_NFM) with that on collagen flat film (Col-FF), to investigate the biological effect of collagen nanofibrous matrix on hDPCs. Methods: The surface morphology of the two different collagen scaffold was analyzed by scanning electron microscopy (SEM), and the contact angle and the swelling ratio were also measured. Then hDPCs were implanted on the two different collagen scaffolds, the cell morphology was observed using SEM and laser scanning microscope (LSM), and cell proliferation was evaluated by the CCK-8 assay. After hDPCs cultured on the two different collagen scaffold with odontoblastic medium for 14 days, the expression of odontoblastic differentiation related genes was detected by real-time PCR, and alizarin red staining was used to test the formation of mineralized nodules. Results: From the SEM figures, the fibers’ diameter of Col_NFM was (884±159) nm, and there were abundant three dimensional connected pore structures between the fibers of Col_NFM, while the surface of Col_FF was completely flat without pore structure. The contact angle at 0 s of Col_NFM was 85.03°±4.45°, and that of Col_FF was 98.98°±5.81°. The swelling ratio of Col_NFM was approximately 3 folds compared with dry weight sample, while that of Col_FF was just 1 fold. Thus Col_NFM indicated better hydrophilicity and swelling property. SEM and LSM showed that hDPCs on Col_NFM presented an irregular and highly branched phenotype, and could penetrate into the nanofibrous scaffold. In contrast, the cells were spread only on the surface of Col_FF with a spindle-shaped morphology. CCK-8 assays showed that hDPCs on Col_NFM showed higher proliferation rate than on Col_FF. After hDPCs were cultured on the two different collagen scaffolds with odontoblastic medium for 14 days, more expressions of odontoblastic differentiation related genes, such as dentin sialophosphoprotein (DSPP) and dentin matrix proten-1 (DMP1) were determined in Col_NFM group (P<0.05), and more mineralization depositions were also observed in Col_NFM group according to the results of alizarin red staining. Conclusion: Col_NFM with nanoscale microstructure achieves better hydrophilic and swelling properties than Col_FF, and hDPCs cultured with Col_NFM present higher activity on cell adhesion, proliferation and odontoblastic differentiation.

Objective: To investigate the clinicopathological features and prognostic factors in lymphoma of parotid origin. Methods: Clinicopathological data of the patients with parotid lymphoma who were initially diagnosed in Peking University Hospital of Stomatology from 2006 to 2016 were collected and analyzed retrospectively. The patients were followed-up for 5 to 149 months with a median period of 45 months, and the factors influencing the prognosis were evaluated. Results: A total of 41 patients with primary parotid lymphoma were included in this retrospective study. The rate of male to female was 1 ∶2.15. The median age was 57 years (ranging from 8 months to 91 years). According to WHO classification, 40 cases (97.1%) were diagnosed as non-Hodgkin lymphoma (NHL), including 15 cases of extranodal marginal zone B-cell lymphoma of mucosa-associated lymphoid tissue (MALT), 14 cases of diffuse large B cell lymphoma (DLBCL) as well as 4 cases of follicular lymphoma, while other subtypes of NHL were rare. Only one case was diagnosed as Hodgkin lymphoma. Regarding the clinical staging at the initial diagnosis, 37 patients (90.2%) were diagnosed as stage ⅠE or ⅡE of the disease, while 4 patients (9.8%) as stage ⅢE or stage ⅣE. Seven patients (17.1%) had a history of Sjögren syndrome (SS), all of whom were MALT lymphoma. The mean ill duration of the 41 patients were 20.7 months. Thirty-two patients (78%) presented a slowly growing painless mass in the parotid gland. Treatment options included localized therapy and systemic therapy, all of whom had good curative effect. Nine patients (21.9%) died during the follow-up period. The overall survival rates of 2-year and 5-year were 84.5% and 81.3% respectively. The univariate analysis demonstrated statistically significant differences for accelerated growth of tumor (P=0.005), and presence of tumor capsule (P=0.011). The multi-univariate analysis demonstrated statistically significant differences for presence of tumor capsule (P=0.041). Conclusion: A large majority of primary parotid lymphoma were NHL, among which MALT lymphoma and DLBCL were common subtypes. Most patients presented an indolent mass in parotid gland, which should be distinguished from the parotid benign tumors. SS is closely related to the pathogenesis of MALT lymphoma. The prognosis is better than that of other malignant parotid tumors. Absence of tumor capsule may predict a poor prognosis in patients with parotid lymphoma.

Objective: To investigate the effect of different treatment temperatures of a novel cold atmospheric plasma jet treatment on the resin-dentin bonding. Methods:(1) Fifty-two freshly extracted, non-carious and intact third molars were collected. The occlusal one-third of the crown was removed by means of a water-cooled low-speed Isomet saw. One dentin disc [(900 ±100) μm] was prepared for each tooth. The fifty-two dentin discs were randomly divided into control group and experimental groups, of which four were in control group, and forty-eight were divided into four experimental groups according to the different treatment temperatures (4 ℃, 10 ℃, 20 ℃ and 30 ℃) of the novel radio-frequency atmospheric-pressure glow discharge (RF-APGD) plasma jet, twelve in each group. Each experimental group was divided into three subgroups according to different treatment time (10 s, 20 s and 30 s), with four in each subgroup. The occlusal one-third of the crown was removed by means of a water-cooled low-speed Isomet saw. The morphology of demineralized dentin surfaces was analyzed using field emission scanning electron microscopy. (2) Twenty unerupted, non-carious and intact third molars were randomly divided into five groups, four in each group: control group, untreated; 4 ℃, 10 ℃, 20 ℃ and 30 ℃ experimental groups, each group was treated with the RF-APGD plasma jet for 20 s. The micro-tensile resin dentin bond strength was tested after 20 s RF-APGD plasma jet treatment with different temperatures, using a universal mechanical machine. Results:(1)The field emission scanning electron micro-scopy results indicated that when compared with the control group, a 10 s RF-APGD plasma jet treatment with 30 ℃ and 20 ℃ collapsed the collagen scaffold. Collagen fibrils maintained an uncollapsed three-dimensional structure after the 4 ℃ RF-APGD plasma jet treatment for even 30 s treatment. (2) The microtensile resin dentin bond strength results of the 4 ℃ RF-APGD plasma jet treatment group (57.8±0.7) MPa were significantly higher than that of the control group [(47.4±0.5) MPa] and 10 s, 20 s and 30 s RF-APGD plasma treatment group [(51.9±0.7) MPa,(29.7±1.0) MPa and (22.2±1.5) MPa] with statistically significant difference (P<0.05). Compared with the control group, the micro-tensile bond strength increased about 21.9% and 9.5% after 4 ℃ and 10 ℃ RF-APGD plasma jet treatment, respectively. Conclusion:Compared with other treatment temperatures, this novel RF-APGD plasma jet treatment with the temperature of 4 ℃ can preserve the three-dimensional morphology of demineralized dentin better, and can improve the resin-dentin bonding.

Objective: To retrospectively analyze the results of treatment outcome by surgery combined with ¹²⁵I brachytherapy and correlative factors of adenoid cystic carcinoma (ACC). Methods: In the study, 75 patients with primary ACC of oral and maxillofacial region were treated by surgery combined with ¹²⁵I seeds brachytherapy. Radical resection or subtotal resection was applied for the tumor. The brachytherapy treatment planning system was used to create implant plans with the prescribed dose of 60 Gy to 120 Gy. The ¹²⁵I seeds were implanted intraoperatively or postoperatively. The regular follow-up was required. The Kaplan-Meier method was used to assess the tumor control rate and the patients’ survival rates. Meanwhile, the Cox regression analysis was used to find out the prognostic factors. Results: Local control rates at the end of 3 and 5 years were as follows: T₁-T₂, 92.2% and 82.0%; T₃-T₄, 82.6% and 82.6%; and overall, 90.0% and 78.8%. The disease-free survival rates were 74.9% and 54.3%, respectively. The overall survival rates for all the patients were 86.0% and 79.6%, respectively at the end of 3 and 5 years and were 91.3% and 91.3% for T₁-T₂ patients vs. 73.9% and 59.7% for T₃-T₄ patients. Distant metastasis-free survival rates at the end of 3 and 5 years were 84.4% and 76.7%, respectively. The distant metastasis-free survival rates at the end of 3 and 5 years were 83.4% and 79.6% with T₁-T₂ lesion compared with 86.0% and 67.8% with T₃-T₄ lesion. According to the COX univariate analysis and multivariate analysis, the risk of local recurrence would be raised by the age. Tumor stage and tumor site were the prognostic factors of the overall survival rates. Conclusion: ¹²⁵I brachytherapy conducted as an adjuvant therapy postoperatively of ACC of oral and maxillofacial region can acquire satisfactory local-regional control, distant metastasis-free survival, disease-free survival and overall survival. Tumors are prone to recur on the older patients. Patients having advanced tumor stage or tumor located in the nasal cavity or sinuses will suffer lower survival rates.

Objective: To explore the value of incorporated multimodal image fusion technology with computer-aided design of the skull base-infratemporal tumor treatment. Methods: A retrospective study was carried out to enroll seventeen patients with skull base-infratemporal tumors treated at Peking University Hospital of Stomatology from February 2011 to September 2018. Plain CT, enhanced CT and MRI data were imported into the iPlan 3.0 software (BrainLab navigation system), and the image fusion was performed for each patient preoperatively. Then the three-dimensional images of the tumor, vital vessels and craniofacial bones were reconstructed to prepare virtual operation design. We evaluated the application of multimodal image fusion technology that had been incorporated with computer-aided planning during the navigation-guided biopsy or surgery, through the analysis of the biopsy and operation data and re-gular follow-up postoperatively. Results: The mean age of 17 patients (7 males and 10 females) was 46 years. Primary tumors occurred in 11 cases, and recurrent tumors in 6 cases. The size of the 17 tumors ranged from 2.9 cm to 9 cm, and the mean size was 4.35 cm. There were 7 cases with skull base bone destruction and/or intracranial extension, and 10 cases with tumors adjacent to the skull base. High-quality multimodal fused images were obtained in all the 17 cases. The spatial-position relationships of the tumors, adjacent craniomaxillofacial bones and vital vessels labeled with different colors were displayed well on the generated fusion images. The multimodal image fusion technology that incorporated with computer-aided three-dimensional reconstruction and then applied in navigation-guided biopsy or surgery showed that, preoperative analysis and virtual operation design functioned with good results, especially in cases with small tumor size, recurrence or ill-defined borders in the skull base-infratemporal region. Operation was carried out in 16 cases after preoperative diagnosis and assessment, and 1 case was performed by navigation-guided biopsy only. The proportions of navigation-guided surgery and biopsy were 70.6% (12/17) and 17.6% (3/17) individually. The positive rate of pathologic diagnosis using navigation-guided biopsy was 100% (3/3). All the navigation-guided biopsies or operations were carried out successfully. Complications included 1 case of cerebrospinal fluid leak from a recurred meningioma patient postoperatively, and 1 case of facial paralysis resulting from parotid-gland deep lobe tumor. Most (14/15) tumors got complete removal with safe boundary through intra-operative navigation verification and post-operative imaging confirmation, except for one case of subtotal resection to avoid the injury of cavernous sinus. The pathological results of the tumors could be classified to mesenchymal (10), adenogenous (3), neurogenic (3) or epithelial (1) resources. The follow-up time ranged from 3 to 94 months, with the median follow-up time of 9 months. Conclusion:Taking full advantages of individualized multimodal images, could help analyze the three-dimensional spatial position relationship of tumors, vital vessels and craniofacial bones properly, and then complete the virtual operation design well. The incorporated multimodal image fusion technology with navigation technology may improve the accuracy and safety of core needle biopsy and surgical treatment of skull base-infratemporal tumors.

Objective: To evaluate the practical value of near-infrared light transillumination (NILT, DIAGNOcam) on detection of incipient proximal caries in primary molars. Methods: In this study, 4-9-year-old children with suspicious proximal lesions in primary molars were recruited. The target teeth were examined with clinical examination, bitewing radiograph and DIAGNOcam. And the caries indexes were rated as 0 (no caries), 1 (caries reaching outer 1/2 enamel), 2 (caries reaching inner 1/2 ena-mel), and 3 (dentine caries). Those primary molars with at least one of the adjacent molars according with the criteria of invasive treatment, i.e. the teeth were diagnosed as caries reaching inner 1/2 enamel or dentine with at least two detection methods, were included. The target teeth with caries index ≥2 accepted the invasive treatment. And the caries status of the adjacent teeth was observed under direct vision and those teeth of caries index ≥2 would also accept the invasive treatment. The relationship of lesions to enamel-dentine junction (EDJ) were recorded and used as reference standard to compare the sensitivity, specificity and accuracy of those three methods in detecting the incipient proximal caries in primary molars. Results: In this study, 36 children with 104 suspicious proximal lesions in primary molars were recruited, of which 5 were diagnosed as no caries, 20 were diagnosed as superficial enamel caries, and 79 accepted invasive treatment, of which 22 were diagnosed as EDJ caries, and 57 as dentine caries. The sensitivity of clinical examination, bitewing radiograph, and DIAGNOcam were 68.69%, 81.82%, 78.79%, respectively. The specificity were 100.00%, 100.00%, 80.00%, and the accuracy were 75.96%, 85.65%, 78.85%, respectively. As for superficial enamel caries, the sensitivity of cli-nical examination was lowest, only 10%, while DIAGNOcam was 60%, higher than 40% of bitewing radiograph. As for EDJ caries, the sensitivity of bitewing radiograph was highest as 86.36%, followed by DIAGNOcam 72.73% and clinical examination 68.18%. As for dentine caries, the sensitivity of the three detection methods were higher than 85%, of which bitewing radiograph was the highest as 94.74%. Conclusion: The accuracy of DIAGNOcam in detecting incipient proximal caries in primary molars was comparable to that of bitewing radiograph. It was safe, and convenient with no exposure to radiation, which was applicable to be used in pediatric dentistry.

Objective: To evaluate the outcomes and to find out the influence factors of indirect pulp treatment in primary teeth. Methods: Children who received indirect pulp treatment in primary teeth in the Department of Pediatric Dentistry in Peking University School and Hospital of Stomatology from August, 2014 to September, 2016 were collected in the Electronic Medical Record Database of Peking University School and Hospital of Stomatology, via the database for scientific research provided by the corporation of Kaientai. The children selected as the subjects of this study were followed up over 1.5 years, and they were under 9 years old if in the group of primary molars while the children in the group of primary anterior teeth were under 4 and a half years old. Those children who were not reviewed regularly or didn’t have complete medical records were removed. Basic information, the relevant medical records and radiographic records of those children were collected. All teeth were examined clinically and classified into 2 outcomes, teeth in group H were regarded as succeeded, and teeth in group P were regarded as failed. Survival analysis was applied. The survival rate and survival time of the deciduous teeth calcu-lated. Multivariate analysis was performed by using Cox proportional hazard model. Results: One hundred and six children were finally included, aged from 1.6 to 8.8 years, with the mean age of (5.0±1.7) years. 168 primary teeth (122 primary molars, 46 primary anterior teeth) were included, and the average follow up time was (729±244) days. Thirty-five primary teeth (23 primary molars, 12 primary anterior teeth) failed upon clinical or radiographic examinations by September, 2018. The cumulative survival probability of half a year, one year, one year and a half, two years, two and a half years for the indirect pulp treatment was 93.5%, 92.9%, 87.5%, 82.7%, and 75.5% through the Kaplan-Meier method, respectively. Through the analysis of Cox proportional hazard model, in primary molars, the survival probability tended to be lower when the number of tooth surface affected by caries was greater (OR=1.709, P<0.05). Compared with primary molars, the survival probability of primary anterior teeth was lower, but the difference was not significant. Conclusion: Complying the current instructions in our department, the cumulative survival probability of two and a half years after the indirect pulp treatment in primary teeth was 75.5%. In primary molars, the survival probability tended to be lower when the number of tooth surfaces affected by caries increased.

Objective: To evaluate the clinical characteristics and effectiveness of bioceramic putty repairment (iroot BP Plus) used as pulp capping agents on pulpotomy in primary molars. Methods: Forty primary molars were treated by pulpotomy with bioceramic putty repairmen as the pulp capping agents at the Third Clinical Division of Peking University School and Hospital of Stomatology, from September 2016 to September 2017. The children who were followed up over one year were selected as the subjects of this study. The teeth were checked clinically and radiographically during fixed intervals, and classified into one of five outcomes: N,H,P₀,P_X,P_Y. N, absence of clinical symptoms, and absence of apical radiolucency; H, absence of clinical symptoms, and nonpathologic radiographic change present; P₀, absence of clinical symptoms, and pathologic change present, no need for treatment; P_X, present or absence of clinical symptoms, pathologic change present treatment or extract immediately; P_Y, premature loss of deciduous tooth. Molars classified into N and H were regarded as successful, classified into P₀,P_X and P_Y were regarded as failed. Results:Followed up for 12-24 months (the average follow up time was 16months),thirty four children were finally included, aged from 3.1 years to 8.5 yaers (the average age was 4.3 years), forty primary molars were included. Thirty four primary molars were included into N group, with absence of clinical symptoms, absence of apical radiolucency. Two molars were included into H group with physiological root absorption. One molar was included into P₀ group with absence of clinical symptoms butinternal absorption of the root. Three molars were included into P_X group, with gingival fistula and apical radiolucency. None was included into P_Y group. Thirty six teeth got successful treatment, four molars failed. One year success rate of pulpotomy of primary molars using bioceramic putty repairment was 95%. Conclusion: Current evidence suggests that bioceramic putty repairment as a pulpotomy medicament showed satisfied clinical and radiographic result in pulpotomy of primary molars. Bioceramic putty repairment is an acceptable material when used in pulpotomy of primary molars.

Objective: To evaluate the diagnostic accuracy of cone beam computed tomography (CBCT) with different resolution settings in detecting the simulated external root resorption defects. Methods: External root resorption defects were simulated in 51 human single rooted premolar teeth. Ca-vities simulating root resorption defects of 1 mm in diameter and 0.1 mm, 0.2 mm, and 0.3 mm in depth were drilled in the cervical, middle and apical thirds of lingual surfaces of the teeth. In addition to the 51 locations as controls, a total of 102 cavities were obtained in the present study. Specimens were placed in a human dry mandible and scanned by ProMax 3D and DCT PRO CBCT with different resolution settings, respectively. The three-dimensional CBCT images were evaluated by two experienced observers. The data were analyzed with receiver operating characteristics (ROC) analysis. ROC curves were generated and the area under ROC curve (Az) was employed to express the diagnostic accuracy. Results: The diagnostic accuracy (Az value) of ProMax 3D CBCT with high, normal and low resolution settings were 0.867, 0.703 and 0.665 (P < 0.05), respectively. Defects with depths of 0.2 mm and 0.3 mm were easier to be detected than those with depths of 0.1 mm (P < 0.05). The images obtained by high resolution mode scanning had obvious advantages in detecting smaller defects (depth 0.1 mm and 0.2 mm). The DCT PRO CBCT provided 4 resolution settings including normal quality + normal resolution, normal quality + high resolution, high quality + normal resolution and high quality + high resolution. The Az values for those 4 resolution settings were 0.527, 0.725, 0.743, and 0.794 (P < 0.05), respectively. Similar to ProMax 3D CBCT, the scanning mode with high resolution played a better role in detecting the defects with depth of 0.1 mm. Except for the scanning setting mode with normal quality + normal resolution, the other three modes could well be evaluated for the defects with depth of 0.2 mm and 0.3 mm. Conclusion: It is concluded that the diagnostic ability for external root resorption of CBCT could be affected by resolution settings. Computer-aid imaging method can improve the CBCT diagnostic accuracy for external root resorption without increasing the radiation dose level during CBCT scanning.

Objective: To evaluate the clinical outcomes of vestibular incision subperiosteal tunnel access (VISTA) with connective tissue graft (CTG) in the treatment of Miller classes Ⅰ and Ⅱ localized gingival recession. Methods: Ten patients with 10 Miller classes Ⅰ and Ⅱ localized gingival recessions were enrolled in the study. All defects were equal to or above 2 mm in recession depth. All the patients received treatment with VISTA+CTG. Their clinical parameters, including recession depth (Rec), recession width (RW), keratinized tissue width (KT), clinical attachment loss (CAL), probing depth (PD) were recorded and compared before surgery and 6 months later. The mean root coverage (MRC) and complete root coverage (CRC) were calculated at the end of 6 months. A visual analogue scale (VAS) was used to estimate the patients’ discomfort during the operation and during the 2 weeks post-operation. Patient-based aesthetic satisfaction 6 months after surgery was evaluated by a VAS. Results: The mean Rec was (2.65±0.82) mm at baseline, and (0.35±0.58) mm after 6 months. The VISTA+CTG treatment resulted in an improvement of (2.30±0.98) mm in recession depth (P<0.001). MRC was 86.67%±21.94% and CRC reached 70% at the end of 6 months. KT increased (0.90±1.22) mm (P<0.05) . Aesthetic satisfaction on the patients’ level was 8.30 based on VAS (0=unsatisfied, 10=extremely satisfied). The patients’ discomfort during the operation and 2 weeks post operation were 2.40 and 4.30 (0=no pain, 10=extreme pain). Furthermore, clinical outcomes showed no statistically significant difference between the gingival biotypes, and between the teeth positioned in maxillary and in mandibular. Conclusion: VISTA+CTG could be an effective treatment for Miller classes Ⅰ and Ⅱ localized gingival recession. Clinical outcomes indicated decrease in recession depth and width, and increase in width of keratinized tissue. Patients suffered little pain during the operation and 2 weeks post-operation of healing and accessed good aesthetic satisfaction. VISTA+CTG could be an option for the treatment of Miller classes Ⅰ and Ⅱ localized gingival recession.

Objective:To investigate stability of skeletal hard tissues, dental hard tissues and soft tissues after orthodontic-orthognathic treatment in a long term. This study reviewed longitudinal changes in orthodontic-orthognathic patients of skeletal class Ⅲ malocculsion, using lateral cephalometric radiographs in 3-12 years after treatment in comparison to treatment finishing. Methods: Twenty-two patients with skeletal Class Ⅲ malocclusion following orthodontic-orthognathic surgery in Peking University School and Hospital of Stomatology from January 1, 2000 to January 1, 2009 were observed. The lateral cephalometric radiographs of the following stages were collected: treatment finishing (T1), 3 to 12 years after treatment (T2). Statistical analyses of cephalometrics were evaluated. Paired student t test was performed by SPSS 17.0. Results: Data of all the 22 patients were studied in longitudinal timeline after treatment and 3-12 years after treatment. From T1 to T2, we evaluated 11-SN (angle between the upper incisors axis and SN plane), 11-NA angle (angle between the upper incisors axis and NA plane), 11-NA mm (perpendicular distance from upper incisors to NA plane), 11-41(angle between the upper incisors axis and lower incisors axis), 41-NB angle (angle between lower incisors and NB plane), 41-NB(perpendicular distance from lower incisors to NB plane), 41-MP angle (angle between lower incisors and GoGn plane), and IMPA [angle between lower incisor and mandibular plane (tangent line to submandibular border)]. Most hard tissues of the teeth remained stable but upper anterior teeth angulations decreased, indicating by significantly reducing 11-SN (T1:110.98°±6.77°; T2: 109.21°±5.80°; P=0.005); reducing 11-NA(T1: 28.31°±6.80°;T2: 26.49°±6.18°; P=0.002); increasing 11-41 (T1:123.51°±8.14°;T2:125.7°±10.01°;P=0.035). From T1 to T2, we also evaluated SNA (angle of sella-nasion-A-point ), SNB (angle of sella-nasion-B-point), ANB (angle of A-point-nasion-B-point), GoGn-SN(angle between GoGn and SN plane), GoGn-FH (angle between GoGn and Frankfort plane), Y axis(angel between Sella-Gn and Frankfort plane), N-ANS (distance from nasion point to ANS point), ANS-Me (distance from ANS point to Menton point), N-Me (distance from nasion point to Menton point), ANS-Me/N-Me% (proportion of ANS-Me to N-Me), and FMA (angle between Frankfort and mandibular plane), Wits appraisal (horizontal distance between points A and B on functional occlusal plane). Skeletal hard tissues also remained relatively stable, only N-Me value changed significantly with a decreasing facial height (T1:124.98°±11.98°; T2:122.4°±11.05°; P=0.024). From T1 to T2, we finally evaluated FH-NsPg angle (angle between NsPg and Frankfort plane), H angle (angel between H line and NB), FH-A’UL angle (angle between A’UL and Frankfort plane), FH-B’LL angle (angle between B’LL and Frankfort plane), UL-LL (angle between UL and LL), UL-EP (distance between UL and E line), LL-EP (distance between LL and E line), Sn-H(perpendicular distance between Sn point and H line), Nls-H (distance of nose-lip-sulcus to H line), Li-H (lower lip to H line), Si-H (lower lip sulcus to H line), and NLA (nasolabial angle, angle of Cm-Sn-UL-point).Soft tissues changes were observed in decreasing UL-EP [T1: (-2.78±2.20) mm; (-3.29±2.44) mm; P=0.02] and H angle(T1: 8.27°±3.71°; 7.32°±3.83°; P=0.006).Other soft tissues remained relatively stable by retruding upper lip position and chin changes with no statistical significance. Conclusion: Orthodontic-orthognathic treatment can improve esthetics and occlusal function in patients of skeletal class Ⅲ malocclusion with a stable long-term outcome.

Objective: To compare the edge morphology of partial veneers made of different materials by slurry molding, heat-pressed and computer aided design/computer aided manufacturing (CAD/CAM) techniques. Methods: Thirty premolars with smooth surface and intact enamel were selected and randomly divided into five groups, 6 specimens for each group. Group A were made from feldspathic porcelain (Noritake ^?) by slurry molding, while Group B were made from lithium disilicate glass ceramic (IPS E.max ^? Press) by heat-pressed. Group C/D/E were respectively made from feldspar porcelain block (VITA Mark Ⅱ ^?), zirconia-reinforced glass ceramic (VITA Suprinity ^?) and hybrid ceramic with a ceramic-polymer network (VITA Enamic ^?) by CAD/CAM techniques. All the partial veneers luted with light-cured composite resin. Then the partial veneers were trimmed and polished to achieve the smooth finishing margin, clinical polishing sets were used according to the product descriptions. Scanning electron microscope (SEM) was used to observe the edge morphology of prostheses and the exposure of resin cements. Results: The smooth surface and knife-like edge of the partial veneers could be obtained after bonding, trimming and polishing. The edges of Group A were slightly rough and the width of the exposed adhesive was (106.00±9.17) μm. In Group B, the edges were smoother than Group A, and the exposed wide adhesive strip was visible, which was (138.33±20.59) μm. In Group E, the edges were smooth too, and the width of exposed adhesive strip was (186.00±5.66) μm. The edges of Group C and Group D were rough and uneven, and the adhesive was rarely exposed, they were (50.67±7.51) μm and (65.67±17.90) μm. There were all significant differences between two groups, except Group C and Group D. Conclusion: After trimming and polishing in accordance with clinical procedures, the expected knife-like edge can be obtained in all groups. The width of the exposed resin adhesive of each group is different, the order: Mark Ⅱ/Suprinity

Objective: To assess and compare the effects of loupes and microscope on laminate veneer preparation of the first practitioner from the aspects of efficiency, quality and accuracy of preparation, and preference. Methods: Twenty young prosthodontists from the Department of Prosthodontics, Peking University School and Hospital of Stomatology were recruited into this study, which was prospective, single blind, self-control trials. The participants had no experience of using dental magnification devices. They prepared laminate veneers in the artificial dental model, under routine visual field (control group), 2.5× headwear loupes (loupes group), and 8× operating microscope (microscopic group) by turning. The time for tooth preparation was recorded. Thereafter, subjective assessments of efficiency, quality of preparation and preference were performed by themselves using visual analogue score (VAS). Expert assessments of quality and accuracy of preparation were performed by two professors using stereomicroscope and digital technique respectively. Results: In terms of efficiency, the subjective scores for the control group, loupes group and microscopic group were 7.15±1.73, 8.10±0.91 and 5.40±2.04, respectively. There was significant difference between the loupes group and microscopic group (P<0.05). The time of tooth preparation for the control group, loupes group and microscopic group was (430.10±163.04) s, (393.90±157.27) s and (441.95±164.18) s, respectively. There was significant diffe-rence between the loupes group and microscopic group (P<0.05). The loupes group was more efficient than the microscopic group. In terms of the quality of preparations, the subjective scores for the control group, loupes group and microscopic group were 6.55±2.09, 7.85±0.99 and 6.25±1.77, respectively. There was significant difference between the loupes group and microscopic group (P<0.05). The expert evaluations for the control group, loupes group and microscopic group were 12.20±1.67, 12.50±1.70 and 11.35±2.60, respectively. There was significant difference between the loupes group and microscopic group (P<0.05). The loupes group had higher quality than the microscopic group. In terms of the accuracy of preparations, the control group, loupes group and microscopic group of incisal 1/3 were (0.107±0.097) mm, (0.142±0.118) mm and (0.123±0.087) mm, respectively, of middle 1/3 were (0.128±0.073) mm, (0.113±0.105) mm and (0.125±0.077) mm, respectively, and of cervical 1/3 were (0.075±0.054) mm, (0.068±0.044) mm and (0.058±0.047) mm, respectively. There was no significant difference among the three groups (P>0.05). In terms of the preference, the subjective scores for the control group, loupes group and microscopic group were 6.55±2.31, 8.60±1.10 and 5.80±2.07, respectively. There was significant difference between the loupes group and microscopic group (P<0.05). The participants had the highest preference for loupes. Conclusion: For the first practitioners, loupes is better than microscope for laminate veneer preparation.

Objective: To establish a complete workflow of digital design and manufacturing occlusal splint for sleep bruxism, which can be preliminarily applied in clinical use, thus observe the clinical efficacy. Methods: Twenty-four patients with sleep bruxism were recruited in the study and randomly divi-ded into two groups by using random number tables. Digital-occlusal-splint (experimental group) treatment plan and traditional-occlusal-splint (control group) treatment plan were carried out for each group, respectively. For experimental group, digital models of patients’ both dental arches and the occlusion relationship after elevation were captured using an intraoral scanner. The occlusal splint was carried out by computer aided design/computer aided manufacturing (CAD/CAM), including splint designing and milling. For control group, the traditional soft occlusal splint was fabricated by vacuum laminator. The two kinds of occlusal splints were tried in the patients from each group, and the occlusal contacts were tested respectively by T-scan analysis system, which recorded the changes of occlusal indicators in the two groups. The retention, appearance and occlusal comfort degree were evaluated by the two groups of patients. Mann-Whitney test was performed with IBM SPSS 20.0 software, and bilateral test was performed. P<0.05 was considered to be statistically significant. Results: The complete workflow of digital design and manufacturing occlusal splint was successfully established. During the clinical use, there was no statistical difference in the retention evaluation of two kinds of occlusal splints between the two groups of patients (Z=-0.538, P=0.590). The appearance score (Z=2.038, P=0.042) and the occlusal comfort score (Z=-2.579, P=0.010) of the experimental group were higher than those of the control group, with statistically significant differences. The T-scan analysis results showed that only the second molar on both sides of the traditional occlusal splint had occlusal contact in intercupsal position, while the digital occlusal splint had stable and bilaterally balanced contact between the maxillary and mandibular teeth. Furthermore, the occlusal force was uniformly distributed in the experimental group. Conclusion: The complete workflow of digital occlusal splint improves the occlusal design, greatly simplifies and optimizes the traditional process of making occlusal splint. This new method is resource-saving and environmental-friendly, and it is able to serve patients more conveniently and efficiently.

Objective: To assess the effects of two surface treatments (sandblasting, SB; microarc-oxidation, MAO) and resin luting on shear bond strength and durability of titanium alloy and composite-resin. Methods: Eighty cylindrical titanium alloy specimens with a diameter of 10 mm and a height of 8 mm were fabricated by CAD/CAM technique. It was divided into two groups according to the surface treatment methods: sandblasting with Al₂O₃ particles on the surface of SB specimens; porous ceramic film structure could be formed on the surface of MAO specimens after surface treatment. Each group was classified into SB-resin luting-N group (not used), SB-resin luting-Y group (used), MAO-resin luting-N group (not used), MAO-resin luting-Y group (used) depending on whether or not resin luting was applied. Each specimen was bonded and cured with the Cemerage resin, and the shear bond strength after 0 and 5 000 thermocycling was tested. The results were statistically analyzed. The surface morphology of titanium alloy specimens before and after the shear bond strength test was observed by scanning electron microscopy (SEM). Results:The shear bond strength between titanium alloy and composite-resin was the highest in the SB combined with resin luting group after 0 thermocycling (16.2±1.8) MPa; was the lowest in MAO group after 5 000 thermocycling (8.9±1.5) MPa. The shear bond strength of SB and MAO surface treatment methods combined without resin luting group after 5 000 thermocycling were (10.7±2.2) MPa and (8.9±1.5) MPa, which were statistically lower than those in the thermocycling 0 (P=0.000 and P=0.001). The shear bond strength of SB and MAO surface treatment methods combined with resin luting group after 5 000 thermocycling were (15.5±2.1) MPa and (11.7±1.3) MPa, respectively, which were lower than those in the thermocycling 0 group, but there was no statistical significance (P=0.087 and P=0.234). Conclusion: Both the surface treatment methods of SB and MAO combined with resin luting can improve the shear bond strength and durability of titanium alloy and composite-resin. The SB combined with resin luting is more significant. At present, the effect of SB is better than that of MAO due to the limitation of technical parameters of micro-arc oxidation.

Objective: To establish a 3D printing system for bone tissue engineering scaffold fabrication based on the principle of fused deposition modeling, and to evaluate the controllability over macro and micro structure precision of polylactide (PLA) and polycaprolactone (PCL)scaffolds. Methods: The system was composed of the elements mixture-Ⅰ bioprinter and its supporting slicing software which generated printing control code in the G code file format. With a diameter of 0.3 mm, the nozzle of the bioprinter was controlled by a triaxial stepper motor and extruded melting material. In this study, a 10 mm×10 mm×2 mm cuboid CAD model was designed in the image ware software and saved as STL file. The file was imported into the slicing software and the internal structure was designed in a pattern of cuboid pore uniform distribution, with a layer thickness of 0.2 mm. Then the data were exported as Gcode file and ready for printing. Both polylactic acid (PLA) and polycaprolactone (PCL) filaments were used to print the cuboid parts and each material was printed 10 times repeatedly. After natural cooling, the PLA and PCL scaffolds were removed fromthe platform and the macro dimensions of each one were measured using a vernier caliper. Three scaffolds of each material were randomly selected and scanned by a 3D measurement laser microscope. Measurements of thediameter of struts and the size of pores both in the interlayer overlapping area and non-interlayer overlapping area were taken. Results: The pores in the printed PLA and PCL scaffolds were regular and interconnected. The printed PLA scaffolds were 9.950 (0.020) mm long, 9.950 (0.003) mm wide and 1.970 (0.023) mm high, while the PCL scaffolds were 9.845 (0.025) mm long, 9.845 (0.045) mm wide and 1.950 (0.043) mm high. The struts of both the PLA and PCL parts became wider inthe interlayer overlapping area, and the former was more obvious. The difference between the designed size and the printed size was greatest in the pore size of the PLA scaffolds in interlayer overlapping area [(274.09 ± 8.35) μm)], which was 26.91 μm. However, it satisfied the requirements for research application. Conclusion: The self-established 3D printing system for bone tissue engineering scaffold can be used to print PLA and PCL porous scaffolds. The controllability of this system over macro and micro structure can meet the precision requirements for research application.

Objective: To establish a reference dental model used for trueness evaluation of photo-curing 3D printing technologies, and to establish a multidimensional trueness evaluation method based on the reference dental model, which can yield a comprehensive objective evaluating result. Methods: A reference dental model was designed in 3ds Max 2018 software based on the statistical analysis results of dental crown and dental arch of Chinese population in previous studies in order to simulate a real dental model. This model was made up of several simple geometrical configurations, which could minimize the manual measurement error. Physical models were fabricated using three types of photo-curing three-dimensional printers using different techniques: Objet30 Pro (PJ), Projet 3510 HD Plus (MJP), and Perfactory DDP (DLP). The models were scanned by a laser-scanning device and the files were exported in a stereolithography file format. In Geomagic Studio 2012, 3D shape deviations (including overall 3D deviation, flatness error, parallelism error and perpendicularity error) were measured by several commands using the data obtained from the scanning. With regard to the feature size of the simulated dental crown and dental arch, linear measurements (including mesiodistal diameter, buccolingual diameter, crown height of each simulated dental crown and feature size of dental arch) were recorded for selected landmarks using a digital caliper. The measurement results of feature sizes were used to analyze the occlusal plane percentage error and the occlusogingival direction percentage error. Results: For the 3D shape deviation, the results showed that the printed model made by the Objet30 Pro had the lowest overall 3D deviation, the model made by Projet 3510 HD Plus had the best perpendicularity accuracy and the model made by Perfactory DDP had the best flatness accuracy. In terms of the accuracy of the feature size, the model made by the Objet30 Pro was the most accurate in consideration of the results of the occlusal plane percentage error and the occlusogingival direction percentage error. Conclusion: The reference dental model and the trueness evaluation method using this model is universally applicable in evaluating the trueness of photo-curing three-dimensional printed dental model and can provide a comprehensive objective evaluating result, which can serve as a reference for the clinical use of photo-curing 3D printing technology.

Objective: To construct a model for a controlled memory (CM) nickel-titanium (NiTi) file and another M-wire NiTi file with the same geometry by using finite element analysis. To evaluate the flexibility of a CM NiTi file by using three dimensional finite element method and to compare its mechanical responses with that M-wire NiTi. Methods: Based on the reverse engineering, the 21 mm long, 25#/08 taper Hyflex NT NiTi file and Hyflex CM NiTi file were fixed by the cantilever bending model at a distance of 9.5 mm from the tip of the file. The mechanical tester’s indenter was loaded/unloaded at a distance of 3 mm from the tip of the file. The maximum displacement was 3 mm, the load displacement curve was obtained. Subsequently, by using a micro-CT to scan (layer spacing of 8 μm) NiTi files, and ABAQUS (6.10) was introduced to construct a geometric model. Hyflex NT was considered as a shape-memory alloy constitutive model, Hyflex CM was considered as a power-hardening plastic constitutive model, respectively. Comparing the load-displacement curve of cantilever bending in the three-dimensional finite element model with the load-displacement curve in the experiment. Results: Two tetrahedral element models were constructed, the total number of nodes was 99 353 and the total number of cells was 63 744. When the loading displacement was 1 mm, the stress distribution of the cross section at 6.1 mm from the tip of the file was observed. The upper and lower surfaces were subjected to the maximum bending stress and entered the phase transformation yield stage. The finite element simulation could clearly show the deformation of the file. Various information such as deformation characteristics and stress distribution in the process were well fitted to the actual experimental curve. Conclusion: The constitutive behavior of the material has a significant effect on the mechanical behavior of NiTi file. The finite element model established for the NiTi file of the CM wire can accurately capture the characteristics of various deformation processes of the NiTi root canal file, and it has a good fit with the actual experimental curve. The finite element model can be used for study on bending properties of CM wire.

Objective: To investigate the oral hygiene status of edentulous patients with locator attachments implant overdentures (IOD) and to analyze the relationship among daily hygiene behavior, oral hygiene status and peri-implant diseases. Methods: Edentulous patients who received IOD treatment with locator attachments from January 2012 to May 2016 were recruited. Clinical and radiographic examinations were conducted to assess the peri-implant tissue status. Modified plaque index (mPLI), sulcus bleeding index (SBI), gingival index (GI), and probing depth (PD) were recorded and peri-implant marginal bone loss (MBL) was measured using paralleling projection technique. Patients’ peri-implant oral hygiene maintainence habits were investigated. The correlation between peri-implant diseases and oral hygiene status and behaviors was analyzed. Results: Fifty patients (125 implants) with an average follow-up time of 22 months (6-54 months) were enrolled. The mean values of mPLI, SBI, and GI were 1.4±1.2, 0.8±0.7, and 0.7±0.6, respectively. Average PD was (2.2±0.7) mm. Mesial and distal maginal bone resorptions were (1.1±1.1) mm and (0.9±0.9) mm, respectively. The prevalance of mucositis and peri-implantitis of the implants were 49.6% and 0. The prevelance of mucositis in the patients with poor oral hygiene (mPLI≥2) was 11.9 times as much as that of those with adequate oral hygiene (mPLI<1). The patients who performed oral hygiene procedure on attachments at least twice a day achieved much lower mPLI scores than those who cleaned less than twice a day. Conclusion: Oral hygiene condition in the group of patients with implant overdentures was poor, and it contributed to increased risk of peri-implant mucositis. The prevelance of musositis of the paitients with poor oral hygiene was 11.9 times as much as that of those with proper oral hygiene. Patients wearing IOD should pay more attention to the hygiene of the attachments.

Objective: Human U three protein 14a (hUTP14a) facilitates tumorigenesis through promoting p53 and Rb degradation as well as enhancing c-Myc oncogenic activity. Moreover, hUTP14a expression is up-regulated in human hepatocellular cancer and colorectal cancer tissues. In this study, the expression of hUTP14a in non-small cell lung cancer (NSCLC) tissues was evaluated by immunohistochemistry staining (IHC). The relationship between hUTP14a expression levels and the clinical characteristics of the NSCLC patients were analyzed. Methods: Lung cancer tissues and the adjacent non-cancerous tissues were collected from 123 cases of NSCLC patients including 53 cases of squamous cell carcinoma (SCC) and 70 cases of adenocarcinoma (ADC), who had accepted surgical resection at Peking University Third Hospital from May 2003 to April 2006. The expression level of hUTP14a was determined by IHC in human NSCLC tissues and the adjacent non-cancerous tissues. The associations between hUTP14a expression and the clinical pathological variables including gender, age, tumor size, histological type, differentiation degree and clinical pathological stage were analyzed using the Pearson’s χ ² test. Results: The expression rate of hUTP14a in NSCLC tissues was significantly higher than that in the non-cancerous tissues (37.4% vs. 0, P<0.001). The expressions of hUTP14a in lung ADC and SCC were 48.6% and 20.6%, respectively. The expression rate of hUTP14a in both lung ADC and SCC was significantly higher than that in the adjacent non-cancerous tissues (P<0.001). In addition, the expression rate of hUTP14a in lung ADC was significantly higher than that in SCC (χ ²=8.66, P=0.003). Furthermore, the expression rate of hUTP14a in the late pTNM stage of SCC was significantly higher than that in the early pTNM stage of SCC while hUTP14a expression level was not associated with pTNM stage of ADC. No correlation was found between hUTP14a expression and the other clinical pathologic features of the patients. Conclusion: Expression of hUTP14a was up-regulated in NSCLC tissues and was correlated with pTNM stage of SCC, suggesting that hUTP14a might possess a potential as a candidate marker for the early diagnosis screening of NSCLC.

Objective: To study the effects of in vitro fertilization-embryo transfer (IVF-ET) technique on gene expression of focal adhension kinase (FAK) signaling pathway in early placental trophoblast cells, and to explore the effects of IVF-ET technology on the development and function of early placenta. Methods: We collected 7-8 weeks of gestation placenta tissue as a study group by ultrasound guided reduction of fetal from double embryo transfer under IVF-ET technology. In the control group, placenta tissues were obtained from the spontaneous abortion of natural pregnancy twin 7-8 weeks. Microarray hybridization analysis was performed on the placenta tissue of the two groups using the Affymetrix HG-U133 Plus 2.0 gene chip. Eight differentially expressed genes were identified by real-time quantitative polyme-rase chain reaction (qRT-PCR), and unsupervised clustering analysis and functional bioinformatics analy-sis were performed for the differentially expressed genes. Results: Twenty-eight cases of IVF-ET reduced fetal villi and 8 cases of spontaneous abortion villi were collected. A total of 8 placental villi were detected by the gene chip. Compared with the natural pregnancy control group, 32 differentially expressed genes in the placental FAK signaling pathway were expressed in IVF-ET. The differential expression was greater than or equal to 2 times, of which 12 genes were up-regulated and 20 were down-regulated. The qRT-PCR showed that the expression of the 8 genes in FAK signaling pathways of IVF-ET was significantly different from that in the placenta of natural pregnancy, which was consistent with the result of the gene chip detection. The FAK signal pathway gene localization showed that the FAK gene was mainly located in the upstream of the signal pathway in the placenta of IVF-ET. The placental trophoblast cells maintained the FAK signaling pathway function through gene expression compensation. Conclusion: There are gene expression differences in the FAK signaling pathway between the IVF-ET derived early placenta and the natural pregnancy placenta. The differentially expressed genes are involved in many key functions of the FAK signaling pathway and affect the early development and function of the IVF-ET placenta, while the placental trophoblast cells change gene expression for interference to compensate for IVF-ET technology itself, maintain normal function of the FAK signaling pathway, and satisfy the need for placental and fetal development.

Objective: To analyze the predictive value of umbilical arterial cord pH on complications of hospitalized neonates after cesarean section. Methods: This was a retrospective cohort study and carried out in Peking University First Hospital from January 1,2017 to June 30,2017. Neonates who were deli-vered by cesarean section were enrolled. The primary endpoint was the incidence of complications during in-hospital stay (including infection,aspiration pneumonia,myocardial damage,etc.). The subjects were divided into two groups:with or without complication. The umbilical arterial cord pH values were compared between the two groups. Perinatal baseline characteristics of maternal and neonatal data were recorded. The ROC curve was used to analyze the value of umbilical arterial cord pH in predicting neonatal complications during hospitalization. Multivariate Logistic regression was employed to analyze the potential risk factors of neonatal complications. Results: In the study,872 neonates were included in the final analysis (541 in elective surgery and 331 in emergency surgery). The overall incidence of neonatal complications during hospitalization was 14.1%. The first three higher incidences were infection,aspiration pneumonia and myocardial damage. The average pH value in neonates without complication was 7.31 while 7.29 in neonates with complication. There was statistical significance between the two groups (P<0.001). The overall incidence of pH≤7.20 was 3.1% (27/872). The patients in neonates without complication had higher incidence of pH≤7.20 than those in neonates with complication (1.6% vs. 12.2%, P<0.001). Multivariate Logistic regression showed 6 risk factors of neonatal hospitalized complications including preterm delivery (OR=8.224,95%CI:4.910-13.777, P<0.001),pregnancy-induced hypertension (OR=1.886,95%CI:1.004-3.546,P=0.049), intrauterine growth restriction (OR=4.429,95%CI:1.280-15.330,P=0.019), emergency cesarean section (OR=2.711,95%CI:1.682-4.369,P<0.001),umbilical arterial blood gas pH≤7.20 (OR=7.420,95%CI:2.951-18.655,P<0.001) and 5-minute Apgar score <10 scores (OR=11.849,95%CI:3.977-35.128,P<0.001). The areas under the ROC curve of umbilical arterial blood gas pH in all neonatal,elective and emergency cesarean section were 0.570 (95%CI:0.508-0.633,P=0.012),0.559 (95%CI:0.465-0.652,P=0.189) and 0.617 (95%CI:0.538-0.697,P=0.002),respectively. Conclusion: Umbilical arterial cord pH≤7.20 was related with increased incidence of neonatal complications after cesarean section,but ROC curve analysis showed a lower predictive value.

Objective: To discuss the clinical characteristics and diagnostic and therapeutic considerations of primary thyroid lymphoma (PTL) by reviewing PTL cases. Methods: In the study, 12 cases of PTL diagnosed and treated in Peking University First Hospital between January 1995 and September 2015 were identified. The clinical characteristics, management experiences and prognosis of these cases were reviewed retrospectively. Results: A total of 12 PTL patients (four males and eight females) were collected, with an average age of 63 years (42 to 81 years) at the time of diagnosis. The average time to clarify diagnosis was 5 months (0.5 to 24 months). Eleven patients presented with a rapidly growing neck mass and visited surgical department, except one complained of coughing and suffocated. Seven patients were hypothyroid, and four were euthyroid at the time of diagnosis. In sonography of 11 cases, nine showed bilateral nodules, with an average diameter of 3.87 cm. Pathologic diagnosis of non-Hodgkin’s lymphoma was confirmed in all the 12 cases by means of partial thyroidectomy (four) or core needle biopsy (eight). The pathological subtypes were diffuse large B cell lymphoma in nine patients, mucosa-associated lymphoid tissue lymphoma (MALToma) in two, and small B cell lymphoma in the other one patient. Five patients were concomitant with Hashimoto’s thyroiditis. Eleven patients received chemotherapy. Only one patient did not have any further treatment after operation due to an inertia type of tumor. The median overall survival time was 24 months (1-117 months), three patients died. Among the patients who survived, seven completed chemotherapy without disease progression, one MALToma case did not receive chemotherapy after thyroidectomy but was still alive with PTL, and one patient just finished his second course of chemotherapy. Conclusion: The diagnosis of PTL should be considered when dealing with rapidly growing goiters in elder female Hashimoto’s thyroiditis patients whose B ultrasound indicates hypoechogenicity in thyroid nodules or parenchyma, especially with lymphadenopathy and tracheal compressions. Timely use of coreneedle biopsy on suspicious cases can avoid unnecessary surgical trauma, and chemotherapy is the main treatment.

Objective:To evaluate the efficacy and safety of submucosal tunneling endoscopic resection (STER) and endoscopic submucosal excavation (ESE) for upper gastroenterology submucosal tumors (SMT) originating from the muscularis propria (MP) layer. Methods: Clinicopathological and endoscopic data of 42 cases with upper gastroenterology tumors originating from the MP layer who were treated with STER (n=28) or ESE (n=14) between April 2013 and December 2016 in Peking University Third Hospital were retrospectively analyzed. The treatment and complications of the two groups were compared. Results: In the study, 42 cases were all resected by therapeutic endoscopy successfully.There was no significant difference (STER vs. ESE) in gender, age, mean tumor size [1.5 (1.0-6.0) cm vs. 1.3 (0.5-2.0) cm,P=0.056]. STER was superior to ESE with reduced sutured time [3.5 (1.0-11.0) min vs. 8.0 (2.0-33.0) min, P=0.006], but more resection time [46.5 (11.0-163.0) min vs.19.5 (6.0-56.0) min, P=0.007]. There was statistical difference between the two groups in resection time or sutured time, but no significant difference (STER vs. ESE) in total operative time [52.0 (14.0-167.0) min vs. 31.5 (10.0-88.0) min, P=0.080]. En bloc resection rates (92.9% vs. 85.7%), hospital stay duration and complications (10.7 vs. 0.0) were similar in the STER and ESE groups. One case developed mediastinal emphysema and 2 pneumonia after operation in STER group, and all of them recovered uneventfully after conservative treatments; There were no complications in the ESE group. After operation, 28 cases of leiomyoma and 14 cases of stromal tumor were diagnosed by routine pathological and immunohistochemical staining. Among them, 6 cases of stromal tumors in group STER were all extremely low risk, 4 cases of stromal tumors in group ESE were extremely low risk, 4 cases of stromal tumors in group ESE were medium risk (the size of the lesion was about 1.0-2.0 cm, and mitotic figures counted (6-8)/50 high power field). The median follow-up time of all the patients was 46.5 (24-60) months, and the shortest follow-up time for medium risk stromal tumors was 32 months. No residual tumor, recurrence and implantation in the tunnel were observed. Conclusion: STER or ESE can be used as an effective and safe option for treatment of submucosal tumors originating from the muscularis propria of the upper digestive tract. Compared with STER, ESE had shorter resection time but longer wound closure time. There was no significant difference in total operation time.

Objective:To compare the effects of ultrasound-guided interscalene brachial plexus block and C5-6 nerve root block for analgesia after shoulder arthroscopy. Methods: In the study, 40 patients of ASA Ⅰ-Ⅱ were selected for elective general anesthesia to repair the shoulder ligament rupture in Peking University Third Hospital, who were randomly divided into two groups, respectively for the intermuscular brachial plexus block group (group I) and C5-6 nerve root block group (group C), n=20. The forty patients underwent ultrasound-guided brachial plexus block or C5-6 nerve root block before general anesthesia. Group I: 0.2% ropivacaine 10 mL was injected into brachial plexus intermuscular approach; Group C: 0.2% ropivacaine 10 mL was injected around the nerve roots of C5 and C6, and the ultrasound images showed that the liquid wrapped nerve roots. The time of sensory and motor block after puncture, operation time, the time of postoperative analgesia, numerical rating scale (NRS) scores at 1, 6, 12, and 24 h postoperatively and the finger movements were recorded. The adverse drug reactions and the patient satisfaction were recorded. The primary end point was the study of shoulder rest and movement pain in the patients with postoperative nerve blockage; the secondary end point was the patient’s limb movements and thepatient satisfaction. Results: The duration of analgesia was (571.50±70.11) min in group I and (615.60±112.15) min in group C, and there was no difference between the two groups (P>0.05). The static and dynamic NRS scores at 1, 6, and 12 h in group C were lower than those in group I (P<0.05). There was no difference in static and dynamic NRS scores between the two groups during 24 hours (P>0.05). There was a significant difference in grade of muscle strength between group C [5(4,5)] and group I [4(2,4)] in the patients with nerve block hind limb (P<0.01), and there were significant differences between the two groups’ sensation in the radial nerve group C [1(0,2)] and group I [2(1,2)], the median nerve group C [0(0,2)] and group I [2(1,2)], and the ulnar nerves group C [0(0,1)] and group I [1(1,2)] (P<0.01). There was no statistical difference between the two groups in the sencation of the shoulder, group C 2(1,2) and group I 2(1,2) , P>0.05. Compared with group I 8(6,9), group C 9(8,10) was a significant difference in satisfaction (P<0.01). Conclusion: Interscalene brachial plexus block and C5-6 nerve root block could satisfy the needs of analgesia after shoulder arthroscopy, but C5-6 nerve root blockage does not limit the limb activity, the numbness is less, and the patient’s satisfaction is higher.

Objective: To explore the application accuracy of virtual preoperative plan after the condylectomy via intraoral approach under computer assisted surgical navigation, and to analyze the location and cause of the surgical deviation to provide reference for the surgical procedure improvement in the future. Methods: In the study, 23 cases with condylar hypertrophy (11 with condylar osteochondroma and 12 with condylar benign hypertrophy) in Department of Oral and Maxilloficial Surgery, Peking University School and Hospital of Atomatology from December 2012 to December 2016 were treated by condylectomy via intraoral approach under computer assisted surgical navigation. The patient’s spiral CT data were imported into ProPlan software before operation, and the affected mandibular ramus was reconstructed three-dimensionally. The condylar osteotomy line was designed according to the lesion range, and the preoperative design model was generated and introduced into the BrainLab navigation system. Under the guidance of computer navigation, the intraoral approach was used to complete the condylar resection according to the preoperative design of the osteotomy line. Cranial spiral CT of the craniofacial region was taken within one week after operation. Three-dimensional reconstruction of the mandibular ramus at the condylectomy side was performed, and the condylar section was divided into six segments (anterolateral, anterior, anteromedial, posteromedial, posterior, and posterolateral) and the corresponding regional measurement points P1 to P6 were defined. Then the preoperative virtual model and the postoperative actual model were matched by Geomagic studio 12.0 to compare the differences and to analyze the accuracy of the operation. Results: All the patients had successfully accomplished the operation and obtained satisfactory results. Postoperative CT showed that the condyle lesion was completely resected, and the condylar osteotomy line was basically consistent with the surgical design. No tumor recurrence or temporomandibular joint ankylosis during the follow-up period. The postoperative accuracy analysis of the condylar resection showed that the confidence intervals measured by the six groups of P1 to P6 were(-2.26 mm, -1.89 mm), (-2.30 mm, -1.45 mm),(-3.37 mm, -2.91 mm),(-2.83 mm, -1.75 mm),(-1.13 mm, 0.99 mm), and(-1.17 mm, 0.17 mm), where P3 group was different from the other 5 groups. There was no significant difference between the P5 and P6 groups and the difference between the other four groups was statistically significant. Conclusion: Under the guidance of computer navigation, the intraoral approach can be performed more accurately. The surgical deviation of each part of the osteo-tomy surface is mainly due to excessive resection. The anterior medial area of the anterior medial condyle represents the most excessive resection. The posterior and posterior lateral measurement points represent the posterior condylar area. The average deviation is not large, but the fluctuation of the deviation value is larger than that of the other four groups. The accuracy of computer-assisted subtotal resection has yet to be improved.

Objective: To retrospectively compare the effect of alternate levels miniplate and anchor fixation with the effect of all levels miniplate fixation in expansive open-door cervical laminoplasty (EOLP). Methods: Patients with cervical spondylosis underwent EOLP between July 2015 and June 2016 were included in the study. There were 33 patients in the alternate group (alternate levels miniplate and anchor fixation group) and 34 patients in the miniplate group (all levels miniplate fixation group). Neurological function was evaluated with the Japanese Orthopedic Association (JOA) score and degree of pain was assessed with the visual analogue scale (VAS) score. Basic clinical and surgical data, complication rates and medical costs of the two groups were compared. In addition, radiological examinations were performed pre- and post-operatively and at the final follow-up. Relative imaging data such as anteroposterior diameter (APD), cervical curvature index (CCI) and open angle were collected and compared. Results: (1) The mean follow-up time was 18.6 months in the alternate group and 18.9 months in the miniplate group. There were no significant differences in operation time, intraoperative blood loss, perioperative complication rates, post-operative hospital stays, VAS scores and neurological recovery rates preoperatively and at the final follow-up between the two groups. (2) Additionally, no obvious differences were observed about CCIs and APDs at the three follow-up time points between the two groups. Post-operative open angles at C4 and C6 in the alternate group were significantly smaller than those in the miniplate group. However, there were no significant differences in C3, C5 and C7 open angles between the two groups post-operatively. Notably, no significant differences were detected about the open angles at all levels between the two groups at the final follow-up. (3) When comparing radiologic data at different time points in each group, CCIs and open angles at each level had no significant differences, but APDs after surgery and at the final follow-up were significantly larger than pre-operative APDs. (4) Total costs in the alternate group were significantly lower than those in the miniplate group. Conclusion: The two surgical methods showed almost the same neurological recovery rates and complication rates. However, use of alternate levels miniplate and anchor fixation in EOLP can reduce medical expenses.