Evaluation of enamel roughness after orthodontic debonding and clean-up procedures using zirconia, tungsten carbide, and white stone burs: an in vitro study.

BACKGROUND: The main goal of orthodontic debonding is to restore the enamel surface as closely as possible to its pretreatment condition without iatrogenic damage. This study aimed to compare the effects of different adhesive removal burs; zirconia burs, tungsten carbide burs, and white stone burs on enamel surface roughness. MATERIALS AND METHODS: Total sample of 72 extracted premolars was randomly divided into three equal groups (n = 24) depending on the method of adhesive removal: zirconia burs (ZB); tungsten carbide burs (TC); and white stones (WS). The metal brackets were bonded using Transbond XT orthodontic adhesive (3 M Unitek, Monrovia, CA, USA) and debonded after 24 h using a debonding plier, then the ARI was assessed. The adhesive remnants were removed using the different burs and Final polishing was performed using Sof-lex discs and spirals. Thirteen samples from each group were evaluated using a Mitutoyo SJ-210 profilometer to determine average surface roughness (Ra) and three samples from each group were examined under Scanning Electron Microscopy (SEM) to determine EDI score. The evaluations were performed at three time points; before bonding (T0), after adhesive removal (T1) and after polishing (T2) and the time consumed for adhesive removal by burs was recorded in seconds. The data were analyzed statistically by ANOVA, Tukey's test and Kruskal-Wallis H-test. RESULTS: Kruskal-Wallis H-test showed no statistically significant difference of ARI in all studied groups (p = 0.845) and two-way mixed ANOVA revealed that all burs significantly increased surface roughness at T1 compared to T0 (p < 0.001) in all groups with the lowest Ra values were observed in the ZB group, followed by the TC group, and WS group. The fastest procedure was performed with WS, followed by ZB, then TC bur (p < 0.001). After polishing (T2), Ra values showed no significant difference in ZB group (P = 0.428) and TC group (P = 1.000) as compared to T0, while it was significant in WS group (p < 0.001). CONCLUSION: zirconia bur was comparable to tungsten carbide bur and can be considered as alternative to white stone which caused severe enamel damage. The polishing step created smoother surface regardless of the bur used for resin removal.

Comparison of Enamel Surface Roughness after Bracket Debonding and Adhesive Resin Removal Using Different Burs with and without the Aid of a Magnifying Loupe.

AIM: This study aimed to evaluate the impact of using a magnifying dental loupe on enamel surface roughness during adhesive resin removal by different burs. MATERIALS AND METHODS: Ninety-six extracted premolar teeth were randomly divided according to the bur used with or without the aid of a magnifying loupe into four equal groups (N = 24): group I: naked eye tungsten carbide burs (NTC); group II: magnifying loupe tungsten carbide burs (MTC); group III: naked eye white stones (NWS); and group IV: magnifying loupe white stones (MWS). The initial surface roughness (Ra) T0 was evaluated using a profilometer, and the scanning electronic microscopy (SEM) technique. The metal brackets were bonded and debonded after 24 hours with debonding plier. After adhesive removal, Ra was evaluated again (T1) also the time spent on adhesive removal was recorded in seconds. The samples were finally polished by Sof-Lex discs and Sof-Lex spirals, and the third Ra evaluation was performed (T2). RESULTS: The results of two-way mixed analysis of variance (ANOVA) showed that all burs increased surface roughness at T1 as compared to T0 (p < 0.001) with the highest Ra values shown in group III followed by group IV, group I, and group II. After polishing, no significant difference was noted in Ra values in group I and group II at T0 vs T2 (p = 1.000), while it was significant in group III and group IV (p < 0.001). Regarding the time required for adhesive removal, the shortest time was in group IV followed by groups III, II, and I, respectively. CONCLUSION: The use of a magnifying loupe affects the quality of the clean-up procedure by reducing the enamel surface roughness and the time spent on adhesive removal. CLINICAL SIGNIFICANCE: Using a magnifying loupe was helpful during orthodontic debonding and adhesive removal.

Impact of retraction force magnitudes on mobility of maxillary canines: a split-mouth design.

OBJECTIVE: Prospective evaluation of the maxillary canine mobility during retraction using two different force levels over 5 months of retraction. MATERIALS AND METHODS: Thirty patients indicated for maximum retraction of maxillary canines with age range of 14.7-18.9 years were included in the study. After complete leveling and alignment and immediately before canine retraction, the mobility of the maxillary canines was measured using the Periotest device and repeated monthly. A split-mouth design was applied where on the one side, the retraction force was 100 g, while on the other side 200 g of force. Four subgroups were investigated: A1 (R3 100 g), A2 (L3 200 g), B1 (R3 200 g) and B2 (L3 100 g). The total amount of canine retraction was measured for each side using the pre- and post-retraction dental casts. RESULTS: The collected data were normally distributed. ANOVA test showed insignificant statistical difference in Periotest values (PTVs) among the four subgroups pre-retraction and monthly p > 0.05. However, each group showed a statistically significant difference in PTVs over the 5 months. The independent sample t test showed a statistical insignificant difference in PTVs between the 100 g and 200 g retraction force. Pearson correlation of the PTVs to the period of retraction was statistically significant p < 0.05 while being in significant to the retraction force p > 0.05. CONCLUSION: Increasing the retraction force of maxillary canines up to 200 g of force does not significantly increase the teeth mobility during orthodontic treatment. There is a positive correlation between the PTVs and the duration of tooth movement regardless the magnitude of force.

Effects on root axes and resorption of simultaneous intrusion and retraction of maxillary central and lateral incisors using mini-implant supported three-piece burstone base arch: A prospective observational study.

OBJECTIVE: Prospective morphometric evaluation of the positional changes and root resorption of maxillary central and lateral incisors undergoing simultaneous intrusion and retraction (SIR) using mini-implant supported 3-piece Burstone base arch. MATERIALS AND METHODS: Bracket head type mini-implants were inserted between the maxillary second premolar and first permanent molar. After maxillary canine retraction, SIR of maxillary incisors was begun using mini-implant supported 3-piece Burstone arch. A segmental CBCT was taken before and after SIR of the maxillary four incisors. Data collected were analysed using Paired t test, ANOVA test, independent sample t test and Pearson's correlation test. RESULTS: Sixteen patients of 17.9±1.94 years mean age with class II division 1 malocclusion, deep bite≥4mm and overjet 5-8mm were selected. All mini-implants showed good stability during treatment with no looseness. Increasing the vertical end of the anterior segment up to 10mm led to controlled tipping and partial bodily retraction of the maxillary central and lateral incisors. The centre of resistance (CRe) of the four maxillary incisors was retracted 2.38±0.77mm and intruded 2.76±1.0mm with a mean change in axial inclination of 9.76±3.45°. The mean amount of root resorption of the four incisors was 1.29±0.59mm over a mean period of 6.2 months. CONCLUSIONS: The mini-implant supported 3-piece Burstone base arch had a pronounced effect on SIR of flared maxillary incisors with clinically insignificant amount of root resorption.