Shear bond strength of metallic and ceramic brackets using color change adhesives

Safe Debonding of Fixed Appliances: A Comparison of Traditional Techniques and LODI Devices on Different Bracket Types in Terms of Enamel Cracks, Site of Bond Failure, and Bracket Reusability

The objective of this study was to compare the effects of the debonding of three different bracket types by means of three popular debonding methods. A total of 180 human third molars was divided into six groups, consisting of 20 teeth each. Three bracket types were bonded to the enamel (metal brackets with an integral base and a foil mesh base, and ceramic brackets) and three methods of bracket debonding were employed (bracket removal pliers, Weingart pliers, and Lift-Off Debonding Instrument). The samples were examined with scanning electron microscopy to assess the number of enamel cracks, measure the area of adhesive remaining on the enamel, and calculate the adhesive remnant index (ARI). There were no statistically significant differences between the groups in terms of the number of enamel cracks after bracket debonding. The amount of adhesive remaining on the teeth after the brackets were removed was significantly different between the groups. LODI and Weingart pliers are considered to be the safest methods of debonding brackets with an integral base, while LODI is the best tool for brackets with foil mesh. Bracket removal pliers are considered to be the preferred method for ceramic bracket debonding.

Bond assessment of enamel conditioned with Er, Cr: YSGG laser and methylene blue photosensitizer activated by photodynamic therapy to orthodontic metallic brackets

AIM

To assess bond integrity and failure mode after enamel pretreated with conventional and contemporary conditioning methods were bonded to metallic brackets (MB).

MATERIAL AND METHODS

Forty maxillary central incisors were selected and disinfected. All specimens were mounted up to the cement-o-enamel junction and divided into four experimental groups randomly based on the enamel conditioning technique. Photodynamic therapy (PDT) was used to condition enamel in group 1, Total-etch and rinse (TER) was used to treat samples in group 2, Specimens in group 3 were conditioned with ECL, and samples in group 4 surface pretreated with SEP. Bonding of MB was performed on the surfaces of all the specimens with a Transbond XT. Specimens from all investigated groups were positioned on a universal testing machine maintaining buccal surfaces similar to the direction of the force. After bracket debonding bond failure was assessed using ARI. The bond integrity of all four groups was compared using analysis of variance (ANOVA). Post hoc Tukey test was used for pairwise comparison among different groups.

RESULTS

Group 2, TER+MB (15.38±0.14 MPa) displayed the highest bond value whereas the lowest values of SBS were exhibited by group 1, PDT+MB (10.11±0.17 MPa). The inter-group comparison revealed that specimens of group 2 and group 3, ECL+MB (14.61±0.55 MPa) demonstrated comparable bond strength (p>0.05).

CONCLUSION

Enamel conditioned with TER and ECL demonstrated comparable SBS. However, bond integrity after PDT and SEP (self-etch primer) surface treatment of enamel bonded with MB significantly lowered bond values.

Influence of photodynamic therapy and different conventional methods on conditioning of lithium di silicate ceramics bonded to metallic brackets: An assessment of bond strength

AIM

The aim of the current study was to assess the effect of different conditioning methods on Lithium di silicate (LDC) employing conventional and contemporary regimes bonded to metallic brackets.

MATERIAL AND METHODS

70 discs of LDC were prepared and polished to attain smooth surface. Samples were allocated into seven groups according to ceramic surface conditioning. Group 1 surface treated with Er-YAG laser and saline (S), Group 2 PDT using MBP + S, Group 3 H F + S (control), Group 3 HF (Hydrofluoric acid) + saline, Group 4 HF (Hydrofluoric acid) + ultrasonic bath (UB) + S, Group 5 sand blasting the glass ceramic surface with 120 um Al₂O₃, Group 6 LDC surface conditioned with SECP(Etch and Prime) and Group 7 ECL(Laser) + S on was irradiated on LDC. Both chemical and mechanical surface treatments of LDC were followed by placement of metallic brackets. Samples were arranged in universal testing machine for shear bond strength (SBS) testing. Bond failure of brackets were assessed using ARI. To assess and compare the mean and standard deviations (SD) among experimental groups analysis of variance (ANOVA) was employed. All treatment combination means were compared using the post hoc Tukey's multiple comparison test at a significance level of (p ≤ 0.05).

RESULTS

SBS values of Group 2 H F acid + S displayed highest bond durability (22.28 ± 1.09 MPa). Whereas, specimens in Group 4 surface treated with 120 μm Al₂O₃ displayed lowest SBS scores (11.81 ± 0.55 MPa) and these bond scores were comparable to PDT using MBP + S (12.54 ± 1.09 MPa) (p > 0.05). LDC surface treated by ECL + S (21.11 ± 3.85 MPa), HF + UB + S (19.28 ± 0.52 MPa) exhibited results comparable to HF acid + S (p > 0.05).

CONCLUSION

LDC conditioned with HFS still remains as gold standard. Use of PDT for surface treatment of LDC and bonded to metallic bracket is not recommended as it results in decreased bond durability. Use of ECL-S and HF + UB + S has a potential to be used alternatively to HFS for LDC conditioning.

Influence of phototherapy on bond strength and failure modes of enamel bonded to ceramic and metallic brackets with different surface treatment regimes

AIM

The aim of the current study was to assess efficacy of phototherapy on mode of failure and shear bond strength among different brackets in combination with dissimilar conditioning regimens on enamel surface.

MATERIAL AND METHODS

Ninety maxillary premolars were arbitrarily assigned into six groups (n = 15 each) based on surface conditioning of enamel. Group 1 and group 2 surface treated with total etch + rinse. Group 3 and group 4 surface conditioned with Er,Cr:YSGG. Group 5 and group 6 surface treated with self-etching primer (SEP). Now based on the type of bracket bonded to enamel surface. Group 1, 3 and 5 were bonded to metallic brackets (MB). Similarly, group 2,4,6 were bonded to ceramic bracket (CB). All samples from each group were positioned in a in a universal testing machine for shear bond strength testing. Ten samples from each group were used to discover the sites of bond failure using ARI with stereomicroscope. The mean shear bond strength of six groups were compared by analysis of variance (ANOVA) and pairwise comparison between groups were analysed with the Post hoc Tukey test at a significance level of (p < 0.05).

RESULTS

The maximum SBS values were displayed by group 1 total etch + rinse MB (14.84 ± 1.78) whereas the minimum shear bond strength values were exhibited by group 6 SEP CB (9.99 ± 0.91). Samples treated with total etch + rinse MB (14.84 ± 1.78) and group 3 Er,Cr:YSGG MB unveiled comparable bond strength (p > 0.05). Similarly, experimental group 2 total etch + rinse CB (12.52 ± 1.28) was found to be comparable to group 4 Er,Cr:YSGG CB (12.14 ± 4.12) (p > 0.05).

CONCLUSION

Enamel etched for bonding bracket with Er,Cr:YSGG phototherapy at (4.5 W and 30 Hz) displayed comparable bond strength to conventional Transbond XT independent on the type of brackets used.

Variations in enamel damage after debonding of two different bracket base designs: An in vitro study

Background. Bracket base design is a factor influencing shear bond strength. High shear bond strength leads to enamel crack formation during debonding. The aim of this study was to compare enamel damage variations, including the number and length of enamel cracks after debonding of two different base designs. Methods. Eighty-eight extracted human premolars were randomly divided into2 groups (n=44). The teeth in each group were bonded by two types of brackets with different base designs: 80-gauge mesh design versus anchor pylon design with pylons for adhesive retention. The number and length of enamel cracks before bonding and after debonding were evaluated under an optical stereomicroscope ×40 in both groups. Mann-Whitney U test was used to compare the number of cracks between the two groups. ANCOVA was used for comparison of crack lengths after and before debonding in each group and between the two groups. Results. There was a significant increase in enamel crack length and numbers in each group after debonding. There was no significant difference in enamel crack numbers after debonding between the two groups, whereas the length of enamel cracks was significantly greater in anchor pylon base design after debonding. Conclusion. Bracket bases with pylon design for adhesive retention caused more iatrogenic debonding damage to enamel surface.

Effect of bracket base design on shear bond strength to feldspathic porcelain

Objectives:

This study sought to assess the effect of bracket base design on the shear bond strength (SBS) of the bracket to feldspathic porcelain.

Materials and Methods:

This in vitro, experimental study was conducted on 40 porcelain-fused-to-metal restorations and four different bracket base designs were bonded to these specimens. The porcelain surfaces were etched, silanized, and bonded to brackets. Specimens were thermocycler, incubated for 24 h and were subjected to SBS. Data were analyzed using Shapiro–Wilk test, Levene's test, one-way ANOVA, and Tukey's honest significant difference test. Adhesive remnant index was calculated and compared using Fisher's exact test.

Results:

One-way ANOVA showed that the SBS values were significantly different among the four groups (P < 0.001). Groups 1, 2, and 4 were not significantly different, but group 3 had significantly lower SBS (P < 0.001). Fractures mostly occurred at the porcelain-adhesive interface in Groups 1 and 2 while in Groups 3 and 4, bracket-adhesive and mixed failures were more common.

Conclusion:

The bracket base design significantly affects the SBS to feldspathic porcelain.

Shear Bond Strength of Orthodontic Brackets Fixed with Remineralizing Adhesive Systems after Simulating One Year of Orthodontic Treatment

The objective of this study is to assess, in vitro, the shear bond strength of orthodontic brackets fixed with remineralizing adhesive systems submitted to thermomechanical cycling, simulating one year of orthodontic treatment. Sixty-four bovine incisor teeth were randomly divided into 4 experimental groups (n = 16): XT: Transbond XT, QC: Quick Cure, OL: Ortholite Color, and SEP: Transbond Plus Self-Etching Primer. The samples were submitted to thermomechanical cycling simulating one year of orthodontic treatment. Shear bond strength tests were carried out using a universal testing machine with a load cell of 50 KgF at 0.5 mm/minute. The samples were examined with a stereomicroscope and a scanning electron microscope (SEM) in order to analyze enamel surface and Adhesive Remnant Index (ARI). Kruskal-Wallis and Mann-Whitney (with Bonferroni correction) tests showed a significant difference between the studied groups (p < 0.05). Groups XT, QC, and SEP presented the highest values of adhesive resistance and no statistical differences were found between them. The highest frequency of failures between enamel and adhesive was observed in groups XT, QC, and OL. Quick Cure (QC) remineralizing adhesive system presented average adhesive resistance values similar to conventional (XT) and self-etching (SEP) adhesives, while remineralizing system (OL) provided the lowest values of adhesive resistance.