Bond Strength of Abraded and Non-Abraded Bleached Enamel to Resin After Er,Cr:YSGG Laser Irradiation

Vital Bleaching Influences the Bond Strength of Adhesive Systems to Enamel and Dentin: A Systematic Review and Meta-Analysis of In Vitro Studies

CLINICAL RELEVANCE

Vital bleaching impairs the bonding of adhesive systems to enamel and dentin. Thus, restoration placement should be delayed for at least two weeks after completion of bleaching procedures.

SUMMARY

Objective: This systematic review evaluates the influence of vital bleaching on the bond strength of adhesive systems to enamel and dentin.Methods: This review was conducted according to Preferred Reporting Items for Systematic Reviews and Meta-analyses (PRISMA). In vitro studies comparing the bond strength of bleached and unbleached enamel and dentin were searched at the electronic databases-PubMed/MEDLINE, Scopus, and Web of Science-with no limit on year or language. The studies were screened and had data extracted by two reviewers independently. Bond strength data were meta-analyzed using the inverse variance method and the random effect model (p≤0.05).Results: The electronic search provided 4941 eligible studies, and 52 were included in the systematic review and the meta-analysis. The global meta-analysis showed that bleaching impairs the bond strength of adhesive systems to enamel and dentin (p<0.001; mean difference [MD]: -0.96; confidence interval [CI]: -1.18 to -0.73), regardless of the bleaching agent (p<0.001; MD: -9.98; CI: -1.37 to -0.58) or substrate (p<0.001; MD: -0.89; CI: -1.12 to -0.66). The detrimental effect of bleaching on bond strength was not observed after two and three weeks after bleaching (p=0.1; MD: -0.39; CI: -0.84 to 0.65; and p=0.18; MD: -0.99; CI: -2.45 to 0.47, respectively).Conclusion: This systematic review and meta-analysis demonstrated that vital bleaching impairs the bonding of adhesive systems to enamel and dentin, and this adverse effect persists for two weeks.

Efficacy of root canal treatment in c-shaped canals with adjunctive photodynamic therapy using micro-CT

AIM

To investigate the efficacy of conventional root canal treatment (cRCT) with adjunctive photodynamic therapy (aPDT) against microbial biofilms within infected c-shaped root canals.

METHODS

In this in vitro report, the inoculation of 20 freshly extracted human mandibular molar teeth having c-shaped root canal configuration was performed with E. faecalis and P. aeruginosa to produce three-day biofilms in prepared canal system. PDT used a combination of chlorin (ce6) and polyethylenimine (PEI) as the photosensitizer (PS). A 200 μ-fiber was employed to deliver a 660 nm diode laser light into the root canal, and this was compared and conjugated with conventional endodontic treatment utilizing antiseptic irrigation and mechanical debridement.

RESULTS

The utilization of aPDT (group-2) resulted in a considerable decrease in the count of E. faecalis and P. aeruginosa from 12.84 ± 2.18 CFU/mL to 5.13 ± 0.67 CFU/mL, and from 14.06 ± 3.98 CFU/mL to 4.82 ± 1.05 CFU/mL pre-and post-treatment, respectively. A statistically significant reduction in the bacterial counts of both microbes was observed after treatment among the samples of the both study groups (p < 0.05). Specimens in group-2 (8.42 ± 1.14 MPa) demonstrated the highest mean push-out bond strength, whereas the lowest was shown by samples in group-1 (7.08 ± 1.09 MPa). ANOVA showed no statistical difference between the research groups (p = 0.676). The independent t-test revealed that the mean push-out bond strength scores of the cervical segments were higher than the apical and middle segments of roots in research groups (p < 0.05).

CONCLUSION

In c-shaped root canals, the application of photodynamic therapy as an adjuvant to conventional root canal treatment contributes to a statistically significant decrease in the microbial count of E. faecalis and P. aeruginosa along with an improved push-out bond strength of the root canal filling material with root.

Effect of Er,Cr:YSGG on bond strength and microleakage of dentin bonded to resin composite with different distance and irradiation time

BACKGROUND

To explore the surface modification of dentin using Er,Cr:YSGG phototherapy and bonding system on the shear bond strength and microleakage scores at two different distances and times of laser irradiation.

MATERIALS AND METHODS

Ninety disease-free third molars were collected for the experiment. The four laser groups were divided on the basis of non-contact mode distance and time of irradiation: Group-I: Distance of 1 mm with duration of 60 s; Group-II: Distance of 1 mm with duration of 120 s; Group-III: Distance of 2 mm with duration of 60 s and; Group-IV: Distance of 2 mm with duration of 120 s. The surface for control group (Group-EB: Etch & bond group) was treated with etch and rinse bonding regime. Specimens from all the groups were assessed for shear bond strength and microleakage scores. Samples from all groups were immersed in 2% methylene blue for 24 h and assessed under a digital microscope for microleakage.

RESULTS

The lowest bond strength and microleakage was observed in the control group EB. The maximum bond strength score was observed in Group-IV with mean scores 23.41 ± 1.83, while the maximum microleakage scores were observed in Group-II and Group-IV with mean scores 1.0 ± 0.36 and 1.0 ± 0.11, respectively. The lowest bond strength and microleakage among laser groups was observed in Group-II and Group-III, respectively. However, specimens in laser groups showed comparable bond strength and microleakge scores (p > 0.05). For bond strength and microleakage values, analysis of variance showed significant difference among the study groups (p < 0.001). Using Tukey post hoc test, bond strength and microleakage of laser groups showed statistically significant values than EB group.

CONCLUSION

Use of phototherapy using Er,Cr:YSGG for dentin surface treatment has the potential for clinical application in comparison to conventional conditioning technique. Increasing the distance of laser application and time of irradiation has significant effect on the shear bond strength and microleakage scores of dentin bonded to resin composite. However, further in-vitro analysis should be undertaken in order to prove such findings.

Efficacy of Er Cr: YSGG laser therapy at different frequency and power levels on bond integrity of composite to bleached enamel

The aim was to evaluate the influence of Er, Cr: YSGG laser therapy at different pulse frequency and power levels on the bond strength and microleakage of bleached enamel. One hundred samples were bleached using in-office whitening agent. Bleached samples were divided into six subgroups, four subgroups was based on laser application parameters (pulse frequency 50 and 30 Hz; Power 4.5 & 6 W) one subgroup was treated with bleach (B) and the other was control (no bleaching, no laser application). All specimens including control were etched with 37% phosphoric acid and composite build-ups were performed. Ten specimens from all the groups (B: Bleach only, L1: 50 Hz-4.5 W, L2: 50 Hz-6 W, L3: 30 Hz-4.5 W, L4:50 Hz-6W & C: Control) were assessed for shear bond strength and microleakage scores. Ten samples from all groups were immersed in 2% methylene blue for 24 h and assessed under a digital microscope for microleakage. The lowest mean bond strength was achieved in bleached group (9.49 ± 0.95) and maximum bond strength was observed in control group (33.97 ± 0.86). The highest mean microleakage score was found in bleached specimens (group B) (630.32 ± 156.58) and the lowest in controls (group C) (36.66 ± 27.33). Among assessed laser frequency and power combinations, 4.5 W and 30 Hz frequency showed maximum adhesive bond integrity (high bond strength and low microleakage) for bleached enamel samples.