ObjectiveThe coefficients of friction (COFs) of aesthetic ceramic and stainless steel brackets used in conjunction with stainless steel archwires were investigated using a modified linear tribometer and special computer software, and the effects of the bracket slot size (0.018 inches [in] or 0.022 in) and materials (ceramic or metal) on the COF were determined.MethodsFour types of ceramic (one with a stainless steel slot) and one conventional stainless steel bracket were tested with two types of archwire sizes: a 0.017 × 0.025-in wire in the 0.018-in slots and a 0.019 × 0.025-in wire in the 0.022-in slot brackets. For pairwise comparisons between the 0.018-in and 0.022-in slot sizes in the same bracket, an independent sample t-test was used. One-way and two-way analysis of variance (ANOVA) and Tukey's post-hoc test at the 95% confidence level (α = 0.05) were also used for statistical analyses.ResultsThere were significant differences between the 0.022-in and 0.018-in slot sizes for the same brand of bracket. ANOVA also showed that both slot size and bracket slot material had significant effects on COF values (p < 0.001). The ceramic bracket with a 0.022-in stainless steel slot showed the lowest mean COF (µ = 0.18), followed by the conventional stainless steel bracket with a 0.022-in slot (µ = 0.21). The monocrystalline alumina ceramic bracket with a 0.018-in slot had the highest COF (µ = 0.85).ConclusionsBrackets with stainless steel slots exhibit lower COFs than ceramic slot brackets. All brackets show lower COFs as the slot size increases.

Objective The aim of this in vitro study was to evaluate the changes in friction between orthodontic brackets and archwires coated with aluminum oxide (Al 2 O 3 ), titanium nitride (TiN), or chromium nitride (CrN). In addition, the resistance of the coatings to intraoral conditions was evaluated. Methods Stainless steel canine brackets, 0.016-inch round nickel–titanium archwires, and 0.019 × 0.025-inch stainless steel archwires were coated with Al 2 O 3 , TiN, and CrN using radio frequency magnetron sputtering. The coated materials were examined using scanning electron microscopy, an X-ray diffractometer, atomic force microscopy, and surface profilometry. In addition, the samples were subjected to thermal cycling and in vitro brushing tests, and the effects of the simulated intraoral conditions on the coating structure were evaluated. Results Coating of the metal bracket as well as nickel–titanium archwire with Al 2 O 3 reduced the coefficients of friction (CoFs) for the bracket–archwire combination ( p < 0.01). When the bracket and stainless steel archwire were coated with Al 2 O 3 and TiN, the CoFs were significantly lower (0.207 and 0.372, respectively) than that recorded when this bracket–archwire combination was left uncoated (0.552; p < 0.01). The friction, thermal, and brushing tests did not deteriorate the overall quality of the Al 2 O 3 coatings; however, some small areas of peeling were evident for the TiN coatings, whereas comparatively larger areas of peeling were observed for the CrN coatings. Conclusions Our findings suggest that the CoFs for metal bracket–archwire combinations used in orthodontic treatment can be decreased by coating with Al 2 O 3 and TiN thin films.

Orthodontic closure of old, edentulous spaces in the mandibular posterior region is a major challenge. In this report, we describe a method of orthodontic closure of edentulous spaces in the mandibular posterior region accelerated by piezoelectric decortication and alveolar ridge expansion. Combined piezosurgical and orthodontic treatments were used to close 14- and 15-mm-wide spaces in the mandibular left and right posterior areas, respectively, of a female patient, aged 18 years and 9 months, diagnosed with skeletal Class III malocclusion, hypodontia, and polydiastemas. After the piezoelectric decortication, segmental and full-arch mechanics were applied in the orthodontic phase. Despite some extent of root resorption and anchorage loss, the edentulous spaces were closed, and adequate function and esthetics were regained without further restorative treatment. Alveolar ridge expansion-assisted orthodontic space closure seems to be an effective and relatively less-invasive treatment alternative for edentulous spaces in the mandibular posterior region.

The amount of gingival display, the buccal corridor width, and the knowledge in the field affects the perceptions of smile attractiveness. Thus, 3 mm of gingival display and buccal corridor width larger than 16% should be avoided for esthetic reasons during dental treatment.

The purpose of this in vitro study was to investigate the reliability of the adhesive remnant index (ARI) score system with different assessment methods and to test the compatibility of the estimators. Materials and Methods: Sixty-eight human premolars were used in this study. The premolar brackets (SmartClip, 3M Unitek, Monrovia, CA, USA) were bonded with a light cure adhesive (Transbond XT, 3M Unitek). Brackets were debonded using a Lloyd LRX testing machine (Lloyd Instruments Plc., Fareham, Hampshire, UK). Special image analysis software with 320 magnification and naked-eye assessment methods were used to evaluate the adhesive remnant. Four different investigators scored the same samples according to a 4-point scale. The Kendall rank correlation coefficient was used to test the reliability of the estimator's scores. The Friedman test, followed by the Wilcoxon signed-ranks test, was used to investigate significant differences in the ARI scores between the different assessment methods Results: The Kendall rank correlation coefficients revealed no significant difference between the scores assigned by the investigators in this study. However, the ARI scores were significantly different when the special image analysis program was used (p , 0.05). Conclusion: The reliability of the ARI scores increased when quantitative measurement methods were used.