Evaluation of enamel surface integrity after orthodontic bracket debonding: comparison of three different system.

OBJECTIVE: This study aimed to evaluate enamel surface integrity and time consumed during residual cement removal after bracket debonding using different adhesive removal burs with and without a dental loupe. MATERIAL AND METHODS: Sixty human-extracted premolars were collected, cleaned, mounted, and prepared for orthodontic bracket bonding. Teeth were randomly divided into three main groups (n = 20) based on the adhesive removal method: tungsten carbide system (TC), sof-lex discs system (SD), and diamond system (DB) groups. Then, each group was subdivided into two subgroups (naked eye and magnifying loupe subgroups). The brackets were bonded and then debonded after 24 h, and the Adhesive Remnant Index (ARI) was assessed. The adhesive remnants were removed by different systems, and the final polishing was performed by Silicone OneGloss. The enamel surface roughness was evaluated before bracketing (T0), after residual cement removal (T1), and finally after polishing (T2) using surface Mitutoyo SJ-210 profilometry and Scanning Electron Microscopy (SEM) to determine the Enamel Damage Index (EDI) score. The time consumed for adhesive removal was recorded in seconds. RESULTS: The Kruskal Wallis test showed a statistically significant difference in roughness values at T1 compared to T2 between subgroups (p < 0.001). When comparing EDI at T1 and T2, the Kruskal-Wallis H-test showed statistically significant differences in all subgroups. The pairwise comparisons revealed that EDI scores showed a statistically significant difference at T1 and T2 between DB vs. TC and SD (p = 0.015) but not between TC vs. SD (p = 1.000), indicating the highest roughness value observed in the DB group. The time for cement removal was significantly shorter in the magnifying loupe group than in the naked eye group and was shortest with the TC group, whereas the time was the longest with the DB group (p < 0.05). CONCLUSION: All three systems were clinically satisfactory for residual orthodontic adhesive removal. However, TC system produced the lowest enamel roughness, while the DB system created the greatest. The polishing step created smoother surfaces regardless of the systems used for resin removal.

Orthognathic surgical treatment of secondary maxillary deformities following the cleft lip and palate repair / 中华整形外科杂志

Objective@#The aim of this study is to summarize the experience of the orthognathic surgical treatment forsecondary maxillary deformities following the cleft lip and palate repair.@*Methods@#Twenty-two patients with secondary maxillary deformities following the cleft lip and palate repairment(orthognathic approach), were retrospectively analyzed.All the cases were treated in the Hospital of Stomatology, China Medical University from January 2007 to December 2016. There were 9 males and 13 females, ranging from 18 to 24 years in age. Only 3 of those cases were not undergone preoperative and postoperative orthodontic treatments. The anteroposterior maxilla and mandible discrepancy was 6-11 mm preoperatively. The modified surgical procedures are as follows: One-stage alveolar bone graftand maxillary osteotomy were performed for unilateral cleft patients; Internal fixation with micro-plate at the alveolar cleft region was performed to stabilize the maxillary dental arch intraoperatively; Intermolar wire ligation and palatal arch were used to control the width of maxilla intraoperatively and 1 month after operation; 2-3 mm overcorrection for the Le Fort Ⅰ advancement was produced to reduce relapse in sagittal direction. Mandibular set back was performed using bilateral sagittal split osteotomy at the same time. Rigid internal fixation with titanium palates and screws was applied for all the cases. All patients had been followed up for 1 to 2 years postoperatively.@*Results@#Most of the patients had satisfactory facial proportion, and good and stable occlusion relationship, with only one patient developed severely uncontrollable relapse to class Ⅲ malocclusion, and 3 patients experienced relapse resulted in edge to edge incisor relationship.@*Conclusions@#Le Fort Ⅰ osteotomy combined with bilateral sagittal split osteotomy was effective to correct the secondary maxillary deformities following the cleft lip and palate repair. The treatment plan should be individualized, depending on the patients′ occlusion relationship, skeletal deformity, and facial appearance as well. It is necessary to modify the surgical techniques of Le Fort Ⅰ osteotomy for the cleft patients.

Evaluation of application effect of micro-class in orthodontic removable appliance practicum / 中华医学教育探索杂志

Objective To investigate the effect of Micro-class in orthodontic practicum for five-year undergraduate students in stomotology. Methods Experimental comparative method was used on two groups of undergraduate students. A total of 70 students in Grade 2011 were taught with traditional teaching mode as the control group, while 50 students in Grade 2012 were taught with Micro-class lecture as the observation group. The satisfaction questionnaires were distributed to both groups after the course to facilitate the eval-uation of teaching methods, which specifically was done by SPSS 21.0 for t test and Chi-square test. Results The results of survey showed that the satisfaction of the observation group was significantly higher than that of the control group, which exemplified in the studying interest inspiration, studying efficiency improvement, further development, and overall satisfaction [(4.00±0.73) vs. (3.05±0.77); (4.06±0.65) vs. (3.06±1.01);(4.86±0.35) vs. (2.64±0.80); (4.32±0.47) vs. (2.62±1.08)], (P<0.01). Conclusion Micro-class can improve the teaching quality, and it is meaningful to apply the micro-class in orthodontic practicum.

The activity of M-phase promoting factor in oral normal tissue and tumor / 中华口腔医学杂志

<p><b>OBJECTIVE</b>To investigate the content and activity of M-phase promoting factor (MPF) in pleomorphic adenoma, mucoepidermoid carcinoma, buccal carcinoma and normal tissue, in order to evaluate the role of MPF in the development of tumor and the relationship between MPF and malignant degree.</p><p><b>METHODS</b>The content and activity of MPF were assessed by immunobloting and Gollicano method.</p><p><b>RESULTS</b>The cdc2 and cyclinB (two subunits of MPF) were found both in normal and tumor tissues, and their content in tumor was higher than normal tissues. Buccal carcinoma was 64% higher than normal tissues. The activity of MPF in carcinoma was higher than normal tissue and had positive relation with the malignant extent.</p><p><b>CONCLUSIONS</b>The content and activity of MPF in tumor are higher than normal tissue. PKC can activate MPF. These results show PKC may promote tumor proliferation by activating MPF and also, the activity of MPF has some relation with malignant extent.</p>