Three-dimensional inlay-guided endodontics applied in variant root canals: A case report and review of literature.

BACKGROUND: Root canal retreatment is common after root canal therapy in clinical situations. Especially, completing the retreatment of variant root canals can be challenging. This is particularly true for the molars located at the end of the dental arch. However, advancements in digital dental diagnosis and treatment techniques can solve these problems. Here, we describe a case of a maxillary second molar with a variant distobuccal root canal treated via a novel "inlay-guided endodontics" technique based on improved computer-generated programs. CASE SUMMARY: A 63-year-old man complained of a defect in the maxillary left second molar. The tooth, diagnosed with post-treatment endodontic disease, was initially treated by conventional methods, which were ineffective. Our "inlay-guided endodontics" technique was subsequently adopted, with the establishment of a precise integrated three-dimensional (3D) plate model of cone-beam computed tomography data and a digital impression of the dentition. An optimal root canal approach was generated for the "virtual file" in the 3D model. The plate data were imported into a 3D printer and printed. With the help of the guide plate, the file was accurately placed into the cervical third of the distal root canal. The root canal and prosthodontic treatments successfully proceeded subsequently. CONCLUSION: Our newly developed inlay guide plates may facilitate individualized and minimally invasive root canal treatment.

Esthetic evaluation of facial cheek volume: A study using 3D stereophotogrammetry.

OBJECTIVES: To investigate the influence of cheek volume on facial esthetics judged by orthodontists and non-specialists. MATERIALS AND METHODS: A 25-year-old female's natural and smiling face was captured by 3D stereophotogrammetry. Cheek volume of the 3D image was altered to different degrees three-dimensionally. For the natural and smiling face, seven groups of facial images were created: decreased grade I/II/III, increased grade I/II/III, and the original one. Thirty orthodontists and 30 nonspecialists were invited to perform esthetic evaluation of the original and transformed images using a questionnaire. Data were calculated with one-way analysis of variance (least significant difference test) and independent samples t test. RESULTS: Compared to nonspecialists, orthodontists gave lower esthetic scores to the decreased grade III facial images (maximum deformation degree: 7.500 mm and 7.327 mm in natural and smiling face-oriented image groups, respectively). The decreased grade III facial images also received the highest age ranks. However, the increased grade III facial images received the lowest scores and highest age ranks from nonspecialists (maximum deformation degree: 6.994 mm and 5.300 mm in natural and smiling face-oriented image groups, respectively) ( P < .01). CONCLUSIONS: Orthodontists and nonspecialists showed different esthetic evaluation of varied cheek volume. The influence of cheek volume in orthodontic diagnostic analysis needs further consideration.

Obeservations on association between third molar agenesis and craniofacial morphology.

OBJECTIVE: This study was designed to examine the relationship between third molar agenesis and skeletal morphology in the Chinese population. MATERIALS AND METHODS: A total of 1043 patients' records were analyzed with panoramic radiographs and cephalograms. Congenitally missing third molars were assessed with respect to gender, jaw, and side, and assessed in various types of facial morphology. Linear, angular, and proportional cephalometric measurements were analyzed and compared among the samples. For the evaluation of results, the following statistics were used: the Pearson χ 2 test, one-way ANOVA, and the Student-Newman-Keuls method. RESULTS: The overall prevalence of third molar agenesis was 28.7%. Missing third molars were more common in the maxilla and on the right side, while the difference was not statistically significant (P > 0.05) between genders. Every hypodontia group had a smaller SN-GoGn angle, Y-axis-FH angle, and a larger S-Go/N-Me ratio. The group with third molar agenesis in both jaws had smaller SNA and Wits values. The frequency of third molar agenesis in subjects with a Class II malocclusion was significantly lower than in other types of malocclusion (P < 0.05), and the incidence of third molar agenesis in hypodivergent growth pattern was higher than in other patterns (P < 0.05). CONCLUSION: The results demonstrate a possible association between third molar agenesis and both sagittal and vertical craniofacial morphology.

Differences between active and passive self-ligating brackets for orthodontic treatment : Systematic review and meta-analysis based on randomized clinical trials.

PURPOSE: In orthodontic treatment, the effects of differences in the design between active and passive self-ligating bracket (ASLB and PSLB, respectively) are usually neglected. This study investigated differences in effectiveness and efficiency between ASLBs and PSLBs. METHODS: To identify randomized, controlled clinical trials (RCTs) comparing ASLB with PSLB, the electronic databases Medline, Embase, Cochrane Central Register of Controlled Trials, Chinese Biomedical Literature Database, China National Knowledge Infrastructure, and Chinese Medical Journal Database were searched without language or time limits. Relevant available dental journals and reference lists from included studies were manually searched for applicable reports. Meta-analyses were conducted with the Review Manager program. Two independent reviewers performed all search processes; disagreements were discussed with a third reviewer. RESULTS: Eight studies were included in the systematic review, of which six were included in the meta-analysis due to the data consistency. Three had a low risk of bias, four had an unclear risk of bias, and one had a high risk of bias. With regard to alignment efficiency, meta-analysis favors ASLB [mean difference (MD) -10.24 days, 95% confidence interval (CI) -17.68 to -2.80]. However, the same analysis does not favor either design in terms of width change due to treatment for intercanine (MD -0.49 mm, 95% CI -1.10 to 0.13 mm) interfirst premolar (MD -0.07 mm, 95% CI -0.69, 0.56 mm) intersecond premolar (MD -0.58 mm, 95% CI -1.25 to 0.08 mm) and intermolar (MD 0.10 mm, 95% CI -0.82 to 1.02 mm) width. CONCLUSIONS: Based on current clinical evidence from RCTs, ASLB appears to be more efficient for alignment, while neither design shows an advantage for width change. Further research is needed to confirm present results.