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.

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.

Background: This study aimed to assess the impact of silver and titanium dioxide nano-coatings on stainless steel and nickel titanium arch wires concerning friction, surface roughness and the release of nickel, silver, and titanium ions. Methods: A total of 168 arch wires measuring 17.8 cm in length were divided into two groups based on the type of the orthodontic arch wire material: 84 stainless steel (SS) wires and 84 nickel titanium (NiTi) wires. Each group of these wire materials was evenly divided into three subgroups according to the nano coating material: non-coated group (control), titanium dioxide nanoparticles (TiO ₂ NPs) and silver nanoparticles (Ag-NPs). Static friction on a specially designed acrylic plate was measured using a universal testing machine. Surface roughness data was then gathered using a profilometer machine, and inductively coupled plasma-optical emission spectroscopy (ICP-OES) was used to determine the ion release of Ni, Ag and Ti ions. The collected data were compared using a two-way ANOVA and the Bonferroni test for repeated pairwise comparisons. In the ion release test all samples had been incubated in 10 milliliters of artificial saliva and the data was collected at intervals of after 48 h, one week and two weeks, respectively. Then compared using a three-way mixed ANOVA. Results: The nano-coating effect on arch wires static frictional resistance was statistically significantly higher in the nanocoated wires especially in nanocoated SS arch wires ( p < .001). The surface roughness of both arch wires is significantly impacted by the nanocoating as it became lower in nanocoated arch wires especially Ag-NPs coated SS arch wires ( p < .001). Ni ion release significantly decreased in SS arch wires coated with TiO ₂ NPs in comparison to SS wires coated with Ag-NPs and to NiTi arch wires coated with Ag-NPs and TiO ₂ NPs ( p < .001). Conclusions: Ag-NPs and TiO ₂ NPs coatings are suitable for decreasing static friction in arch wires and improving surface roughness. Nano coating can improve surface roughness, static friction resistance especially for SS arch wires. Ion release of Ag and Ti ions in NiTi and SS coated arch wires is in safety concerns associated with nanoparticle dimensions. Ni ion release decreased in nano-coatings so, nano-coatings slightly improved the corrosion resistance especially in SS arch wires coated with TiO ₂ NPs.