To perform disease management based on caries risk assessment of children aged 6 in Shanghai and to explore the clinical effect.

In 2018, 2127 6-year-old children from 19 primary schools in four districts were sampled by random cluster sampling in Shanghai, which were divided into the control group and the experimental group. Referring to the Caries-risk Assessment Tool proposed by the American Academy of Pediatric Dentistry, all children included were evaluated to obtain the baseline. The children in the experimental group were managed by the intervention measures in CAT according to the high, medium and low caries risk levels. The children in the control group were managed according to Shanghai Basic Oral Public Health Service Project. EpiData3.1 was used to establish the database, and SPSS 21.0 was used for statistical analysis. Dental caries prevalence and the incidence of new cavitation of the two groups were analyzed by Chi-square test. Multiple logistic regression analysis was used to analyze and compare the factors related to dental caries in children in the two groups.

A total of 1691 children were included in the study in 2019, and the lost rate of follow-up was 20.50%. 1655 children finally completed the whole survey after removing some invalid questionnaires, including 826 children in the experimental group and 829 in the control group. In 2018, dental caries prevalence of all children included was 62.25% which increased to 68.22% after one year of intervention, but the increase rate of the experimental group was lower than that in the control group. Children in the experimental group had a lower risk of caries than those in the control group in 2019. The incidence of new cavitation of the experimental and control group was 37.6% and 47.6% (χ² = 16.954, P = 0.000) , respectively. The factors related to dental caries in the two groups included the frequency of taking sugar snacks or drinks between meals a day (P_{control group} = 0.031, OR_{control group} = 0.573; P_{experimental group} = 0.002, OR_{experimental group} = 0.471) , the frequency of taking desserts or sweet drinks before bed at night (P_{control group} = 0.043, OR_{control group} = 0.708; P_{experimental group} = 0.026, OR_{experimental group} = 0.706) , and the frequency of brushing teeth per day (P_{control group} = 0.000, OR_{control group} = 0.456; P_{experimental group} = 0.000, OR_{experimental group} = 0.178) . The risk factor of the control group also included the age to start brushing teeth (P = 0.037, OR = 0.380) , while among the experimental group, local fluoride application (P = 0.000, OR = 0.554) was a protective factor for caries.

It is worth popularizing disease management based on caries risk assessment, which is effective in reducing the caries status of children aged 6 in Shanghai.

To develop and evaluate a file collecting system for formative assessment used by orthodontic teachers.

Data conversion tool was developed with Python which optimized file collecting process with on-line questionnaire. Teachers from the orthodontic department, Foshan Stomatological Hospital were recruited in our study, demonstrated how to use the file collecting system and then asked to collect 10 assignment files with e-mail, online questionnaire and our system, respectively. Time used and amount of mouse clicks for each methods were recorded and compared with analysis of variance. Then surveys were carried out to investigate the use of online questionnaire and predictors for time consumption in each method were investigated with simple linear regression and multivariable linear regression.

During the period of May, 2019 to July, 2019, 20 teachers[11 male, 9 female, age (37.8 ± 7.3) years, all of them are dentist by profession] were recruited in our study. File collecting with e-mail took (10.40 ± 2.43) min, and (151.0 ± 70.6) clicks. With on-line questionnaire, it took (5.91 ± 0.13) min and (37.7 ± 10.5) clicks, while with our system, it only took (3.99 ± 0.34) min and (11.0 ± 1.7) clicks to finish. Differences in time consumption (F = 106.7, P<0.001) and clicks (F = 64.9, P<0.001) were statistically significant. Multi-variable regression showed that recent file collecting related experience was an independent predictor (β₁ = -0.34, P = 0.04) for time consumption with our system.

Our system is superior in time consumption and simplicity when compared with traditional file collecting method, such as e-mail, and on-line questionnaire. This trend is especially prominent for teachers who recently carried out file collecting tasks. In general, our research provided a useful tool for assignment file collection in formative assessment.

To explore the effectiveness of clinic and research ability evaluation method in practice assessment of undergraduates majoring in stomatology.

Undergraduates of Grade 2008 and Grade 2013 from Guanghua School of Stomatology, Sun Yat-sen University were enrolled in this study. The traditional clinical practice assessment was implemented among Grade 2008 students, while comprehensive evaluation method was implemented among Grade 2013 students. After clinical practice, both students and clinical teachers were asked to filling out a questionnaire, which would be used to evaluate and analyse effect of the two different assessment systems. Data were statistically analyzed with t-test of two independent samples using SPSS 20.0. The difference was considered statistically significant by P<0.05.

The satisfaction scores to their assessment systems of students in Grade 2008 and Grade 2013 were (7.52 ± 1.41) and (6.91 ± 2.04) , respectively, with no statistically significant difference (t = 1.974, P = 0.051) . Although there was no statistical difference in clinical ability associated self-score between the two groups (P>0.05) , the research ability associated self-score of Grade 2013 students were better than that of Grade 2008 (P<0.05) . Besides, more than 85% clinical teachers were satisfied with the new assessment program and thought it was more favorable to clinical and academic competence cultivation.

Comprehensive evaluation method maintained clinical level among undergraduates and improved their ability in research.

To make a preliminary evaluation of the application of digital virtual teaching system in tooth preparation for an all-ceramic crown of an anterior tooth.

Forty-five students, who participated in 2018 and 2019 Clinical Skills Exhibition Activities for Stomatology Students (21 in 2018 exhibition activities named 2nd "South China Cup" and 24 in 2019 named 3rd "Guanghua Cup" ) , performed tooth preparation for an all-ceramic crown on a plastic tooth of left upper central incisor (#21) by using the test mode of the digital virtual teaching system. The scores of tooth preparation were assessed by two professional judges and the system, respectively, which was then analyzed by the Pearson Correlation (SPSS 26.0) . Moreover, the assessment time required by the judges was also recorded.

The correlation coefficients of the scores by the two assessment methods in 2018 and 2019 were 0.567 (P = 0.007) and 0.544 (P = 0.006) , respectively. The scores assessed by the digital virtual teaching system were obtained at the end of tooth preparation, while the professional judges required a mean of 2.31 minutes in 2018 and 1.88 minutes in 2019 for evaluation.

The digital virtual teaching system can be applied in the tooth-preparation training for undergraduates, and give a real-time assessment. The scores were positively correlated with the judges′. Both of the two assessment methods have their own advantages and disadvantages, so that a combination of the two might be more effective in teaching.

To evaluate the treatment effect of immediate implantation with the elevation of maxillary sinus floor through the lateral wall, accompanied with maxillary cyst or chronic maxillary sinusitis.

From March 2014 to March 2018, a total of 53 immediate implantations with the elevation of maxillary sinus floor through the lateral wall were selected from dental implant department and surgery department in stomatology hospital of Haizhu District. According to the inclusion criteria of literature reports, all the cases were divided into three groups, including 17 cases with maxillary cyst, 15 cases with chronic maxillary sinusitis and 21 cases without cyst or sinusitis for control. Mucosal thickness and residual bone height of maxillary sinus were recorded preoperatively. Mucosal ruptures of maxillary sinus were recorded during the operation. Postoperative complications were recorded 7 days after the operation. Sinus bone gain (SBG) , apical bone height (ABH) , marginal bone loss (MBL) , cyst change and mucosal thickening were also recorded 12 months after restorations. Statistical data analysis was taken by SPSS 20.0. Acute postoperative infections among the three groups were compared with Fisher exact test. Mucosal thickness of maxillary sinus, sinus bone gain and marginal bone absorption among the three groups were compared with single factor variance analysis. Preoperative and postoperative diameter of the cyst and mucosal thickness of maxillary sinus were compared with paired t test.

All patients finished treatments without mucosal rupture. Acute inflammations were found, including two cases in the maxillary cyst group, three cases in the chronic maxillary sinusitis group and one case in the control group. No significant difference was found among the three groups for acute inflammations (Fisher exact test χ² = 2.049, P = 0.352) . Postoperative hematocele and hydrops in sinus was not found in all cases. SBG at 12 months after restoration in the cyst group, the sinusitis group, and the control group was found to be (8.09 ± 1.20) , (7.17 ± 1.18) and (7.36 ± 1.41) mm, respectively. There was no significant difference in SBG among the three groups (F = 2.409, P = 0.100) . ABH in the cyst group, the sinusitis group and the control group was (1.94 ± 1.34) , (1.40 ± 1.12) and (2.10 ± 1.30) mm, respectively. There was no significant difference in ABH (F = 1.382, P = 0.261) , either. MBL in the cyst group, the sinusitis group and the control group was (0.53 ± 0.70) , (0.47 ± 0.92) and (0.48 ± 0.67) mm, respectively. There was no significant difference in bone absorptions (F = 0.118, P = 0.889) . In the cyst group, the mean postoperative diameter of cysts (2.35 ± 3.51) mm was smaller than that of the pre-operative ones (8.41 ± 3.04) mm, which was significantly different (t = 5.216, P<0.001) . In sinusitis group, the thickness of mucosa (6.27±2.15) mm was increased than that of pre-operation (5.27±1.58) mm, which was of significant difference (t = -2.562, P = 0.023) .

It may be feasible to apply immediate implantation with the elevation of maxillary sinus floor through the lateral wall, in case of maxillary cyst or chronic maxillary sinusitis.

To evaluate the effect of applying virtual simulation system to local anesthesia teaching in oral surgery.

Sixty undergraduates from grade 2017 five-year program of school of stomatology, Lanzhou University were selected as research subjects in July 2019. The students were divided into three groups by using the random number table, named control group (group C) , head-simulator group (group F) and virtual simulation system group (group V) , with 20 students in each group. Three groups received theoretical knowledge training and watched the operation demonstration. After the training and demonstration, they took the theoretical examination. Then group C students were divided into ten groups in pairs for inferior alveolar nerve block anesthesia, with professional teachers scoring the scores. The students in group F were trained on the head simulator and the students in group V were trained on the virtual simulation system. After the training, the inferior alveolar nerve block anesthesia injection operation examination and the second theoretical examination for three groups were conducted. Questionnaire surveys were conducted for group F and group V. SPSS 22.0 statistical software was used for statistical analysis of the data. The comparison of two theoretical scores of each group was analyzed by paired sample t-test. The comparisons of the operation scores and anesthesia effect scores of different groups were analyzed by one-way ANOVA. The comparisons of the operation scores and anesthesia effect scores between two groups were analyzed by independent-sample t test.

After the practice, the theoretical scores of the students in group V had been improved greatly (t_V = 3.768, P_V = 0.001) . However, the difference between the second theoretical scores and the first theoretical scores of students in group F and group C was not statistically significant (t_F = 2.079, P_F = 0.051; t_C = 0.538, P_C = 0.597) . The operation assessment scores were 82.1 ± 2.6 for group C, 83.9 ± 1.5 for group F and 85.7 ± 2.5 for group V, and the difference was statistically significant (F = 12.629, P<0.001) . Meanwhile, in the anesthesia effect assessment, the scores of three groups were 63.5 ± 6.7 for group C, 68.5 ± 5.9 for group F, and 74.0 ± 6.8 for group V, and the difference was statistically significant (F = 13.157, P<0.001) . The results of the questionnaire showed that most students thought that the virtual simulation system can improve the operation skills, theoretical knowledge level and learning interest.

In the preclinical teaching process of anesthesia injection, the virtual simulation system is more conductive for dental students to improve the operation skills and theoretical knowledge, which is worth promotion in the preclinical teaching of local anesthesia.

To assess postoperative pain after endodontic therapy and its association with clinical factors such as gender, age, tooth type, pulpal diagnosis, and preoperative pain, length of obturation and sealer extrusion.

The patients, who came to the Clinic of Stomatology, SUMC and received the root canal therapy for molars and premolars from July, 2018 to April, 2019, were randomly selected by simple random sampling (the order of subjects′ recruitment) . There were 140 cases, including 63 males and 77 females. Local Anesthesia (2% Lidocain with 1∶80 000 Epinephrine) was administered. Access cavity was prepared with the help of bur. Canal preparation was completed using standard technique. Access was sealed with sterile dry cotton pellet and restored temporarily with double layer of glass ionomer cement. After one week patients were recalled and access was re-opened, obturation was done using continuous-wave of gutta-percha vertical condensation technique. AH-plus sealer was used. Postoperative radiographs were taken. Patients were recalled after 24 hours and postobturation pain was recorded using visual analogue scale (VAS) . Data was recorded and χ² test and Logistic regression was used for statistical analysis.

A total of 140 cases were included and 84 patients (60%) developed postoperative discomfort. 61 patients (43.6%) reported mild. 9 (6.4%) and 14 (10%) presented moderate and severe pain, respectively. No patients had extremely severe pain. The χ² test showed that postoperative pain was independent of gender and tooth type but correlated with the diagnosis of preoperative pulp infection (χ² = 76.11, P<0.001) and obturation (χ² = 16.3, P<0.001) , as well as the presence of sealer extrusion apical orifice. Multivariate Logistic regression analysis showed that no symptoms before operation and postoperative pain was correspondingly reduced (OR = 0.179, P = 0.048) . If the paste was not exceeded, the incidence of postoperative pain was reduced (OR = 0.039, P = 0.005) . Chronic pulpitis had less postoperative pain than periapical inflammation (OR = 0.034, P<0.001) , while pulp necrosis had more postoperative pain than periapical inflammation (OR = 4.080, P = 0.038) . Compared with overfilling, both adequate filling (OR<0.001, P<0.001) and underfilling<2 mm from the root tip (OR<0.001, P<0.001) reduced postoperative pain.

A significant association of obturation with postoperative pain was observed in this study. Therefore, clinician should avoid the sealer extrusion when doing the obturation. For the patients with pulp neurosis and periapical lesions, communication after root canal treatment should be pay more attention to.

The present study used oro-maxillaofacial cone-beam computed tomography (CBCT) to analyze the effect of nonoperative periodontal treatment on morphological changes of the schneiderian membrane of maxillary sinus, in the chronic periodontitis patients.

The clinical data of 30 cases of chronic periodontitis, with mucosal thickening maxillary sinusitis suspected in the department of stomatology of the central hospital of Baoan district in Shenzhen from January 2018 to October 2018, were retrospectively analyzed. All patients underwent oro-maxillaofacial CBCT scanning at 6 months after the first periodontal non-surgical treatment. The changes of the maxillary sinus mucosa were measured by CBCT software, and the clinical indexes [probing depth (PD) , clinical attachment loss (CAL) , plaque index (PLI) , sulcus bleeding index (SBI) ] thickness and length of maxillary sinus mucosa before and after treatment were also analyzed. Pearson correlation coefficient was used to analyze the correlation between clinical indicators and mucosal thickness. The paired t test was used to compare the thickness and length of the left and right mucous membrane as well as the examination indexes before and after treatment.

Among 30 patients, the dimension of the mucosal thickening was positively correlated with PD and CAL values, and the correlation was statistically significant (P<0.05) . Totally 58 maxillary sinus showed mucosal thickening. There were 20 mild thickening cases, and the dimension of mucosal thickening 6 months after treatment [ (1.1±0.6) mm] was significantly lower than that before treatment [ (2.5±0.7) mm] (t = 2.983, P = 0.015) . There were 30 moderate thickening cases and the dimension of mucosal thickening 6 months after treatment [ (2.3±0.6) mm] was significantly lower than that before treatment [ (5.8±0.5) mm] (t = 3.987, P<0.001) . There were 8 severe thickening cases and the dimension of mucosal thickening 6 months after treatment [ (4.2 ± 0.4) mm] was also significantly lower than that before treatment [ (11.2±1.8) mm] (t = 3.951, P<0.001) . The periodontal indexes of patients with mild, moderate and severe mucosal thickening in maxillary sinus showed statistically significant difference after treatment compared with those before treatment (P<0.05) .

Nonoperative periodontal treatment has a positive therapeutic significance for improving the schneiderian membrane thickening of maxillary sinus. Oro-maxillaofacial CBCT is a non-invasive and quantitative imaging method for the evaluation of periodontal tissue and maxillary sinus tissues.

Dental erosion is defined as a loss of hard tissue due to chemical attack without the involvement of micro-organisms. Recently, it is considered as an increasing oral health problem because of its increasing prevalence, especially in young people. A wide variety of less- and non-invasive methods have been developed to evaluate dental erosion, including the laboratory and clinical methods. This review focused on the indication, application and research progress of such evaluation methods.

Practical skill evaluation and examination is a critical part of health care professional education. The present article analyzed the existing problems in the current practical skill examination in China. The grading system, which was based on the student rank by examiners′ panel discussion, has therefore been proposed by the authors. The advantage and matters need attention of this grading system were discussed in this article.

To explore the reproducibility of tooth width measurements in digital models from different stages of Invisalign^? treatment, and provide evidence for evaluation of the achieved amount of interproximal reduction (IPR) .

Fifty nonextraction patients were treated with Invisalign^? without interproximal reduction. Digital models of each patient were acquired using the iTero intraoral scanner and examined using ClinCheck software twice: at the start of the case (T1) and during the first midcourse correction or refinement (T2) . The individual tooth width and the anterior and overall Bolton ratios were recorded from ClinCheck. The upper and lower combined anterior and overall teeth widths (UATW, UOTW, LATW and LOTW respectively) were calculated. The reproducibility was determined using intraclass correlation coefficients (ICCs) . The differences between T1 and T2 were used to assess the precision of tooth width. The cases were further divided into groups according to tooth arrangement, age and sex, and the precision of combined teeth width measurements among groups were compared.

The individual tooth width, combined teeth widths and Bolton ratios had ICCs≥0.917. For individual tooth width, the mean differences between T1 and T2 were-0.09-0.03 mm, and the standard deviations were 0.06-0.17 mm. For combined teeth widths, the mean differences were-0.14-0.10 mm, and the standard deviations were 0.21-0.53 mm. The difference in anterior ratio was (0.02 ± 0.71) % and in overall ratio was (0.25 ± 0.61) %. The precision of LOTW showed significant difference among the Spacing, Non-crowding and crowding groups (P<0.05) , while the precision of UATW, UOTW and LATW showed no significant difference (P>0.05) . The precision of all four combined teeth widths measurements showed no significant difference between female and male groups (P>0.05) or between adolescent and adult groups (P>0.05) .

The individual tooth width and combined teeth widths measurements of the digital models from different stages of Invisalign^? treatment showed high reproducibility and clinically acceptable precision in ClinCheck. However, the precision had a relatively large individual variability. The precision of combined teeth widths were not influenced by age and sex but by tooth arrangement to some extent. The tooth width measurements could be generally used as reference for treatment plan and evaluation of the achieved IPR amount.

To analyze the MRI features of temporomandibular disorders (TMD) patients and the value of MRI in evaluating the treatment effect of RW-splint.

Thirty-two patients diagnosed with TMD underwent MRI examination, and the MRI features of sixty-four sides of temporomandibular joint were analyzed retrospectively. Twenty-one patients received RW-splint treatment and underwent MRI examination after treatment, the change of angle of disc-condyle and disc length were analyzed after RW-splint treatment.

In sixty-four sides joints, forty-six discs were found morphogenetic changes, twenty-one joints showed anterior disk with reduction and twenty-five joints showed anterior disk without reduction. Forty-six mandibular condyles showed osteoproliferaion and cortical bone deficiency in varying degrees, thirteen mandibular condyles showed hyperkinesia and five mandibular condyles showed movement restriction. Ten sides showed arthoedema. After the treatment, the angle of disc-condyle in patients with reversible anterior disc displacement decreased from (25.7 ± 2.6) ° to (19.1 ± 1.6) °, the disc length decreased from (11.1 ± 1.3) mm to (9.1 ± 0.7) mm, the change of angle of disc-condyle and disc length were statistically significant (t_angle= 2.889, P_angle= 0.014; t_length= 2.354, P_length= 0.023) . After the treatment, the angle of disc-condyle in patients with irreversible anterior disc displacement changed from (26.4 ± 2.3) ° to (24.1 ± 2.1) °, the disc length decreased from (12.0 ± 1.3) mm to (11.9 ± 1.2) mm, and the change of angle of disc-condyle and disc length were not statistically significant (t_angle= 1.897, P_angle= 0.082; t_length= 1.076, P_length= 0.124) .

MRI can not only be used to diagnose TMD, but also can evaluate the treatment effect of RW-splint objectively.

To explore a proper manner for the prevention and evaluation of vascular crisis, and to improve the success rate of flaps for full thickness defects in patients suffering from oral cancer.

Patients suffering from oral cancer (37 cases) during August 2013 and August 2015 underwent one stage radical surgery and reconstruction of full thickness defects with free folded flap. Flaps were observed and evaluated according to the criteria of vascular crisis prevention, including the color, density, temperature of both sides (intra/extra-oral) . Once such parameters were 20% lower than the standard, it was reported to surgeons at once and proper measures were taken.

Six cases of vascular crisis were found in no more than three days post-operation, including four cases of venous thrombosis and two cases of arterial thrombosis. All these cases recovered after proper treatment.

It is important to observe and evaluate the flap according to the criteria of vascular crisis prevention, which is of help in improving the success rate of surgery.

Patient-based compliance, which is one of the key factors to ensure the quality of orthodontic treatments, can be evaluated in three aspects, including patient-related, environmental and medical factors. A comprehensive evaluation of patients′ appliance may be of help in making individualized therapeutic plans, increasing their acceptance of the treatment plan and ensuring the completion of the whole treatment procedure. Hence, how to evaluate the compliance of first visit orthodontic patients was discussed in detail in this review.

To investigate the differences between Simodent virtual simulation system and traditional head-simulation model in the evaluation of students′ training score with cariology laboratory course.

Both of Simodent virtual simulation system and traditional head-simulator were simultaneously applied among 2012 grade five-year BDS students of Guanghua School of Stomatology, Sun Yat-sen University. During cavity preparation, each students′ operating time, deviation of floor of cavity and cavity rim with Simodent virtual simulation system, as well as subjective scores with traditional method (plaster and resin teeth) were recorded. Teaching questionnaire was applied to investigate the teaching effects of Simodent virtual simulation system. Using SPSS 20.0 statistical software, all of the students′ scores and the questionnaire data were recorded and analyzed by the statistical method of One-Way ANOVA.

The teaching scores of traditional head-simulation model were relatively subjective, and there were no significant differences of students′ scores (t_plaster= 0.33, P_plaster= 0.72; t_resin= 0.50, P_resin= 0.61) . Simodent virtual simulation system was able to evaluate the operating level of each student more accurately, and there were significant differences between different groups of students (t_time= 1.04, P_time= 0.04; t_deviation= 1.70, P_deviation= 0.02) . Results of questionnaire revealed that most students could accept Simodent virtual simulation system, and the system was much easier to master after the training of traditional cavity preparation. Virtual simulation system required further improvement in aspects of data module and operating.

Traditional head-simulation model should be applied in combination with Simodent virtual simulation system. Simodent virtual system has obvious advantages in the assessment of operation accuracy, and it will be more responsive to the needs of future simulation teaching with further improvement.

To analyze and evaluate the effect of Virtual Laboratory Simodont applied in the preclinic teaching of dental cavity preparation.

Thirty dental undergraduates from China Medical University were selected and randomly divided into three groups after being unified with theory training, 10 students for each group with gender parity. Group C was a control, whereas group F and M were trained in the traditional phantom lab (with conventional plastic prefab tooth) and in the Simodont lab, respectively. Tests for the preparation skill were performed before, during and after training. Scores were recorded upon both the visual assessment of teachers and a digital evaluation system according to the preparation requirements of permanent molars ClassⅡ cavity. Evaluation results were analyzed with Kruskal Wallis test and multiple comparisons, with significance level α= 0.05.

The preparation skill of the experimental groups was improved through the training, especially for the students trained in the Simodont lab (TEST3_C= 3.8 ± 2.2, TEST3_F= 5.2 ± 1.9, TEST3_M= 7.4 ± 1.4; t_CF= 2.79, P_CF= 0.021; t_CM= 4.65, P_CM= 0.001; t_FM= 3.01, P_FM= 0.013) . The result of digital evaluation was consistent with that of visual assessment by teachers. Both group F and M were improved after two stages of practice (χ²_F=39.56, P_F< 0.001; χ^2M= 41.73, P_M<0.001) . The result of group M was significantly better than that of group C and F (χ^2CM= 31.16, P_CM= 0.001; χ^2FM= 24.89, P_FM= 0.006) .

Simodont can help dental students improve their practice skills, and strengthen the teaching effect of cavity preparation, so that it is of high recommendation in the dental preclinical teaching.

To evaluate the effectiveness of a digital guide and assessment system in the teaching of tooth preparation.

Thirty senior students of stomatology were divided into two groups randomly, with fifteen in each group. A preparation of an upper right central incisor fixed in a dental simulation model was carried out for both groups. During the preparation, students in group A were under the guidance of Dental Clinical Guidance and Assessment system, while group B were not. The amount and time of preparation, and the frequency of help-seeking of each group were recorded and the data were analyzed with rank sum test, student′s t-test and chi-square test, respectively.

A significantly better tooth preparation (incisor edge preparation/labial preparation/lingual preparation/smoothness) was observed in group A compared with group B. Tooth preparation time of group A and B was (34.87 ± 3.04) and (43.67 ± 2.99) min respectively, indicating a higher efficiency of the former (t=-7.985, P<0.001) . The frequency of help-seeking of group A and B was 26.67 and 93.33% respectively, demonstrating less questions were encountered in group A than group B (χ²= 13.889, P= 0.002) .

Dental Clinical Guidance and Assessment system can help teachers improve the teaching quality of tooth preparation and accelerate students′ mastery of this clinical technique.

To evaluate the clinical effects of the transparotid approach for open treatment of condylar fractures.

In this study, 31 patients with mandibular condylar fractures (36 sides) , were treated using a transparotid approach for open treatment of condylar fractures. Follow-up examinations and postoperative CT scan were performed. The degree of mouth opening, occlusal relationship, facial nerve function, and other complications in the patients were assessed and evaluated.

24 patients with mandibular condylar fractures (29 sides) were treated through the transparotid approach with rigid internal fixation using miniplates; 7 patients whose condyle fracture′ fragments were removed and had arthroplasty of temporomandibular joints. Follow-up examinations were performed for a minimum of 6 months and a maximum of 18 months (average 11.3 months) after surgical treatment. Postoperative CT scan showed that all the condyles had been repositioned and fixed in the normal position; Occlusal function recovered well and facial symmetry was achieved in all of the patients; 4 patients developed Ⅰor Ⅱgrade of limited mouth opening in the early period, and returned to normal after serial trainings; 5 patients developed palsy of the facial nerve that was completely recovered after 8 weeks; 1 patient developed a fistula of the parotid gland who had a second wound healing after bandage treatment for 2 weeks; 4 cases developed traumatic articular diseases that the relevant symptoms such as joint snapping and ache.

The transparotid approach for the open treatment of condylar fractures is feasible and safe, also worthy of clinical application and popularization.

To determine the change of labial bone mass 1 year after immediate implant placement and delayed implant placement by cone beam computed tomography(CBCT), and to evaluate the diagnostic value of CBCT for post-implant labial bone mass during esthetic zone.

A total of 22 implants from 22 patients in maxillary anterior region were followed up with 11 immediate implant placements and 11 delayed implant placements. CBCT images were obtained at three different time point: one week before surgery, immediately after surgery, and one year after implant placement. Labial bone thickness and height were recorded with four sites identification designed by ourselves in this study. The software of SPSS 13.0 was used for statistical analysis.

Significant vertical reduction of labial bone was found in immediate implant placements after 1-year(t=3.316, P=0.009), while no significant difference in delayed implant placement(t=2.073, P=0.068). The 1-year horizontal bone alteration was significantly different at 1 mm apical to the implant/abutment interface(t=2.369, P=0.042)and midimplant(t=3.474, P=0.007); while no significant difference was found at 1 mm coronal to implant bottom both in immediate implant and delayed implant(t=1.596, P=0.145).

CBCT can be used to evaluate the post-implant labial bone mass in esthetic zone. Labial bone and alteration one year after implant placement can be qualitatively assessed by CBCT.