Comparative Evaluation of Two Bis-GMA Based Orthodontic Bonding Adhesives - A Randomized Clinical Trial

Comparative evaluation of bracket bond failure rates of a novel non-primer adhesive with a conventional primer-based orthodontic adhesive - a pilot study

Background

Bonding is an important step in fixed orthodontic therapy and evaluation of bracket bond failures while using different bonding systems is required. The aim of the present study was to evaluate and compare bracket failure rates of a novel no primer adhesive with conventional primer-based orthodontic adhesives.

Methods

This split mouth study was conducted among fifteen patients who underwent therapy with fixed orthodontic appliances using metal brackets. Total of 300 brackets were bonded and the bracket bond failure rates were assessed at the end of 3 months. The difference in bond failure rates between the two groups were assessed in different teeth. Descriptive statistics and chi-square test was performed.

Results

Evaluation of bracket bond failure rates showed a higher incidence of bond failures in the group bonded with the primerless adhesive (6.3%) compared to conventional adhesive (2.3%) but there was no statistically significant difference (P>0.05). No intergroup difference was found in the bracket failure rates of individual teeth (P>0.05).

Conclusion

Higher incidence of bond failures were noted with brackets bonded with primerless adhesive when compared to primer-based adhesive but no significant difference was noted over a period of 3 months. Mandibular canine and premolars had a higher bracket failure rate with no significant difference between the adhesives.

Variation in condylar morphology in different malocclusion among Indians

Temporo-mandibular joint (TMJ) joint and the condyle of mandible are observed in the radiographs of the skull and the jaw. Therefore, it is of interest to assess the predictability of four different shapes of condyle in skeletal class I, II and III malocclusion. The four commonly visualized shapes are oval, bird beak, diamond and crooked were assessed using an ortho pantomogram (OPG). Each of the malocclusion was visualized for different shapes of the condyle. 987 OPGs were radiographically evaluated and the morphology of 1974 condylar heads was visualized. The shapes of the condyles were grouped under four different types. Data shows that oval shaped condyle was most common followed by bird beak. There was variability in the diamond and crooked shape and was lesser than the other types. Thus, the shapes of the condyle are useful predictable guide in deciding the nature of the occlusion.

Palatal plane inclination on vertical growth pattern among Indians

The skeletal discrepancies in the vertical dimensions can either lead to a long face or a short face. The palatal plane inclination is one such contributing factor. The study sample comprised of 15 lateral cephalograms collected between the time period of June 2019 - March 2020 with 5 cephalograms belonging to skeletal Class I, II and III respectively. The inclination angle and mandibular plane angle were measured using the FACAD software. The obtained results were tabulated and statistically analysed using Pearson's correlation test to determine the correlation between the two variables. There was a statistically significant negative correlation between the skeletal malocclusions with a p value of 0.011. Thus, palatal plane inclination is not a major contributing factor for vertical growth pattern and it is suggestive of a multifactorial influence.

Physical and chemical mechanisms involved in adhesion of orthodontic bonding composites: in vitro evaluations

Background

Bond strength of orthodontic composite is strongly influenced by molecular and structural mechanisms. Aim of this in vitro study was to compare bond strength of light-cure orthodontic composites by measuring debonding forces and evaluating locations of bond failure. Investigations on chemical compositions clarified adhesive behaviors and abilities, exploring effects of ageing processes in this junction materials.

Methods

Twelve enamel discs, from human premolars, were randomly coupled to one orthodontic adhesive system (Transbond XT™ 3 M UNITEK, USA, Light-Cure Orthodontic Paste, LEONE, Italy and Bisco Ortho Bracket Paste LC, BISCO, Illinois) and underwent to Shear Bond Strength test. Metallic brackets were bonded to twenty-seven human premolar, with one of the adhesive systems, to quantify, at FE-SEM magnifications, after debonding, the residual material on enamel and bracket base surfaces. Raman Spectroscopy analysis was performed on eight discs of each composites to investigate on chemical compositions, before and after accelerated aging procedures in human saliva and sugary drink.

Results

Orthodontic adhesive systems showed similar strength of adhesion to enamel. The breakage of adhesive-adherent bond occurs in TXT at enamel-adhesive interface while in Bisco and Leone at adhesive-bracket interface. Accelerated in vitro aging demonstrated good physical–chemical stability for all composites, Bisco only, was weakly contaminated with respect to the other materials.

Conclusion

A similar, clinically adequate and acceptable bond strength to enamel for debonding maneuvers was recorded in all orthodontic adhesive systems under examination. No significant chemical alterations are recorded, even in highly critical situations, not altering the initial mechanical properties of materials.

Frequency of premolar teeth extractions for orthodontic treatment

It is of interest to evaluate the frequency of premolar extractions during orthodontic treatment in patients reporting to the Saveetha dental hospital in Chennai from 2019-2020. We used the records from 987 patients who underwent orthodontic treatment from June 2019 to March 2020 in a dental hospital for this analysis. Digital case records of patients who underwent therapeutic extractions of premolars were isolated. A sample dataset of 340 case records were selected for this study. Data shows that 34.4% of subjects underwent premolar extractions amongst a total of 987 subjects who underwent orthodontic treatment. 89.4% of patients were Angle's Class I malocclusion patients, and the rest were Class II patients. However, no premolar extractions were done in Class III patients. Data also shows that 67.1% of subjects underwent all 4 first premolar extractions and 13.2% underwent only upper first premolar extractions. Thus, a significant association was found between Type of Malocclusion and the Type of premolar extractions with p < 0.05. Moreover, only 34.4% of patients underwent premolar extractions and the majority of them underwent all 4 first premolar extractions.

Bond Strength of an Orthodontic Adhesive Containing an Antibiofilm Agent (Octafluoropentyl Methacrylate)

Objective

The objective of this study was to determine whether an adhesive containing antibiofilm agent octafluoropentyl methacrylate (OFPA) has an acceptable bond strength as an orthodontic adhesive.

Methods

Sixty human premolars were divided into four groups. In Groups 1 and 2, brackets were bonded to the teeth using experimental nanohybrid adhesive containing OFPA (ENH-OFPA) and Transbond XT (TXT) was used in Groups 3 and 4. In Groups 1 and 3, the samples were stored in water at 37°C for 24 h and in Groups 2 and 4 thermocycled between 5°C and 55°C. The entire samples were debonded utilizing a universal testing machine. Two-way ANOVA test employed to compare the shear bond strength (SBS) between two adhesives. Independent Student's t-test was utilized to compare the SBS at 24 h and followed thermocycling in each adhesive group. Adhesive remnant index (ARI) evaluated in different groups using Chi-square test.

Results

The mean value for SBS in ENH and TXT groups were 8.13 MPa and 8.10 MPa, respectively. The inference of P = 0.260 was observed and concluded to be nonsignificant for adhesives in terms of SBS. Statistically, differences that observed in SBS at 24 h and following thermocycling in TXT (P = 0.288) and ENH-OFPA (P = 0.145) groups did not consider to be significant. Comparing ARI scores with bracket failure mode resulted in no significant difference (P = 1) between two adhesives in both 24 h and following thermocycling.

Conclusion

Adding OFPA does not compromise SBS of the experimented orthodontic adhesive.