BackgroundThe aim of this prospective clinical study was to compare the mean durability and the failure rates of two types of orthodontic retainers.MethodsOrthodontic patients (142) aged between 14 and 28 years were recruited in this study. The polyethylene woven ribbon (Ribbond, Seattle, WA, USA) retainer was compared with a 0.0175-in flexible spiral wire (Respond, Ormco, Glendora, CA, USA) retainer. When treatment was completed, the retainers were bonded from canine to canine in the maxillary and the mandibular arches of the participants. In the follow-up visits, the patients were re-evaluated every 3 months over a period of 18 months. The time taken for the retainers to remain without any fracture was appraised. Kaplan-Meier analysis and the logrank test were employed to identify significant differences in the survival functions between the groups. The rates of the retainers' failure between the groups were analyzed using Chi-square test.ResultsIt was revealed that the mean survival of the flexible spiral wire retainer was 15.34 ± 0.47 and 15.60 ± 0.42 months in the maxillary and mandibular arches, respectively. The mean survival of the ribbon retainer was 13.95 ± 0.55 and 14.26 ± 0.57 months in the maxillary and mandibular arches, respectively. Ribbon retainers showed a failure rate of 50% in the maxillary and 42.6% in the mandibular arches. Flexible spiral retainers showed a failure rate of 36.5% in the maxillary and 37.8% in the mandibular arches. The differences were not statistically significant. Regarding the evaluation period, the differences had limited clinical significance.ConclusionThe mean survival time and the failure rates of the polyethylene woven ribbon retainer were comparable to the flexible spiral wire retainer during the 18 months after orthodontic treatment.

Bond failure after rebonding for newly placed brackets can be reduced by appropriate enamel surface treatment. This in vitro study investigated the effect of two enamel surface treatments on the bond strength of metallic brackets in the rebonding process. After debonding the brackets and removing the residual adhesive on the enamel surface of 50 upper premolar teeth, the teeth were divided into two equal groups. In the first group, the enamel surface was etched with phosphoric acid 37 per cent, and in the second group, the teeth were sandblasted prior to acid etching. After bonding of the new brackets, the shear bond strength (SBS), probability of bond failures, and adhesive remnant index (ARI) were determined and compared with the t-test, Weibull analysis, and chi-square test. Mean SBS in both groups did not differ significantly (P = 0.081). Most bond failures occurred with ARI scores of 2 and 3, and the difference between the two groups was statistically significant (P < 0.001). Weibull analysis showed that for a given stress, the probability of failure differed between groups. Enamel surface preparation with sandblasting prior to acid etching did not significantly improve SBS in bracket rebonding and left more residual adhesive remnants on the enamel surface.

Objective: This study evaluated the effect of superpulse CO 2 laser irradiation and deglazing of porcelain surfaces on the shear bond strength (SBS) of metal orthodontic brackets, and compared it with two conventional etching techniques. Methods: Forty-eight Feldspathic porcelain fused to metal specimens embedded in cylindrical acrylic resin tubes were fabricated, and all the specimens were divided into four groups. In Group 1, the specimens were roughened with a diamond bur and etched with hydrofluoric acid (HFA) gel for 4 min. In Group 2, the specimens were roughened with a bur and irradiated by a CO 2 laser with a 2 W power setting for 20 sec. In Group 3, the specimens were only irradiated by a CO 2 laser. In Group 4, the porcelain surface was sandblasted with 50 lm aluminum oxide. Before bonding, the bracket silane was applied on the porcelain surfaces. SBS was evaluated by a Universal testing machine (Zwickroll, Germany). The remaining adhesive after the bond failure was evaluated using an adhesive remnant index (ARI). Statistical analysis was conducted by analysis of variance (ANOVA), Tukey, and Kruskal-Wallis tests. Results: ANOVA revealed significant differences in SBS among the four groups ( p < 0.001). Group 1 demonstrated significantly higher bond strength (13.13 -2.47) when compared with the other groups. Group 2 showed higher bond strength (9.60 -1.91) when compared with group 4 (6.40 -1.67) ( p = 0.016). Group 1 displayed the highest ARI scores among the groups. Conclusions: Deglazing combined with HFA etching produced the highest bond strength, but CO 2 laser irradiation provided adequate bond strength and allowed for elimination of the HFA step. Deglazing is not recommended as a preliminary step before CO 2 laser conditioning.

BackgroundThis study aims to evaluate and compare the effect of pre-procedural administration of acetaminophen, ibuprofen, and meloxicam in reducing pain after separator placement.MethodsThree hundred twenty-one patients who needed orthodontic treatment and aged above 15 were randomly assigned to one of the three study groups: group A: 650 mg acetaminophen, group B: 400 mg ibuprofen, and group C: 7.5 mg meloxicam. All subjects received a single dose of medication 1 h prior to separator placement. Using visual analog scale, patients recorded their pain perception during rest, fitting posterior teeth together, and chewing at time intervals of immediately, 2, 6, 24, and 48 h after separator placement.ResultsThere was no significant difference between acetaminophen, ibuprofen, and meloxicam in post-separator placement pain control when administered 1 h before the procedure. In all the groups, at rest, pain level elevated after separator placement and reached its peak at 24 h and then subsided until 48 h. But during chewing and fitting of the posterior teeth, some of the groups reached a peak in pain at 48 h. No significant difference was found in pain experience between males and females.ConclusionsMeloxicam can be used as an effective analgesic in orthodontic pain control considering it has less gastric side effects compared to the conventional nonsteroidal anti-inflammatory drugs.Trial registrationIranian Registry of Clinical Trials, IRCT2015041821828N1

No abstract