Investigation of the Er: YAG laser and diamond bur cavity preparation on the marginal microleakage of Class V cavities restored with different flowable composites

Effect of chitosan and CMCS on dentin after Er:YAG laser irradiation: shear bond strength and surface morphology analysis

OBJECTIVES

The aim of the present study was to evaluate the effect of chitosan and carboxymethyl chitosan (CMCS) on dentin surface morphology and bonding strength after irradiation of Er:YAG laser.

METHODS

Eighty-four laser-irradiated dentin samples were randomly distributed into three groups (n = 28/group) according to different surface conditioning process: deionized water for 60s; 1wt% chitosan for 60s; or 1wt% CMCS for 60s. Two specimens from each group were subjected to TEM analysis to confirm the presence of extrafibrillar demineralization on dentin fibrils. Two specimens from each group were subjected to morphological analysis by SEM. Seventy-two specimens (n = 24/group) were prepared, with a composite resin cone adhered to the dentin surface, and were then randomly assigned to one of two aging processes: storage in deionized water for 24 h or a thermocycling stimulation. The shear bond strength of laser-irradiated dentin to the resin composite was determined by a universal testing machine. Data acquired in the shear bond strength test was analyzed by one-way ANOVA with the Tukey honestly significant difference post hoc test and Independent Samples t-test (α = 0.05).

RESULTS

CMCS group presented demineralized zone and a relatively smooth dentin surface morphology. CMCS group had significantly higher SBS value (6.08 ± 2.12) without aging (p < 0.05). After thermal cycling, both chitosan (5.26 ± 2.30) and CMCS group (5.82 ± 1.90) presented higher bonding strength compared to control group (3.19 ± 1.32) (p < 0.05). Chitosan and CMCS group preserved the bonding strength after aging process (p > 0.05).

CONCLUSIONS

CMCS has the potential to be applied in conjunction with Er:YAG laser in cavity preparation and resin restoration.

Effects of Er:YAG and Er,Cr:YSGG laser irradiation and adhesive systems on microtensile bond strength of a self-adhering composite

This study was aimed to evaluate the effects of Er:YAG and Er,Cr:YSGG laser irradiation and adhesive systems on the microtensile bond strength of Fusio Liquid Dentin (FLD) which is a self-adhering composite (SAC). Twenty-four freshly extracted human molar teeth were collected, and the enamel was removed from the occlusal surface to obtain a flat dentin surface. Twenty-four teeth were randomly divided into eight groups: Group 1: only Fusio Liquid Dentin (FLD) (Petron Clinical, Orange, California, USA) was applied to the dentin surface; Group 2: 37% Phosphoricacid (i-GEL, Medicinos Linija UAB, Lithuania) + FLD; Group 3: Single Bond Universal (SBU) (3 M ESPE, Germany) + FLD; Group 4: Adper Easy One (AEO) (3 M ESPE, Germany) + FLD; Group 5: Er:YAG laser + AEO + FLD; Group 6: Er:YAG laser + SBU + FLD; Group 7: Er,Cr:YSGG laser + AEO + FLD; and Group 8: Er,Cr:YSGG laser + SBU + FLD. After thermocycling, 1 × 1 mm2 sticks were used for the µTBS test (n = 10). Two sticks per group were used for SEM analysis. Fractured sample surfaces were evaluated using a stereomicroscope. Group 8 showed the highest µTBS value (13.70 MPa), whereas Group 1 showed the lowest μTBS value (5.60 MPa). There were no significant differences between Groups 2, 3, and 4 (P = 0.324), but Groups 5-8 showed statistically significant results that were higher than Groups 1-4 (P = 0.012). Adhesive failure mode was predominant followed by mixed failure. The evaluation of bonding of the FLD to dentin showed that the combined use of Er:YAG and Er,Cr:YSGG lasers with SBU and AEO on dentin surfaces improved the dentinal bond strength of the FLD.

Er:YAG laser application in caries removal and cavity preparation in children: a meta-analysis

The aim of this meta-analysis was to systematically evaluate the applications of Er:YAG lasers for the removal of caries and cavity preparation in children. The meta-analysis was performed according to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) and was conducted with data extracted from seven relevant randomized controlled trials (RCTs) published from 1997 to July 2017. The data heterogeneity of each study was assessed by a Q test. We used the heterogeneity results to calculate the standard mean difference (SMD) or relative risk (RR) and 95% confidence interval (95%CI) using STATA version 10.0. The publication bias was evaluated using Begger's test. There were seven randomized controlled trials included in this study. The analysis results indicate that compared to the conventional mechanical method, more time was needed for Er:YAG laser treatment (SMD 1.945, 95%CI 0.942 to 2.948). However, the pain reported by patients was reduced with Er:YAG laser treatment (SMD - 1.013, 95%CI - 1.892 to - 0.196). There were no significant differences between the groups in the complete retention rate (RR 1.021, 95%CI 0.963 to 1.114), the marginal discoloration (RR 1.638, 95% CI 0.240 to 11.986) and the marginal adaptation (RR 1.480, 95%CI 0.257 to 8.515). In conclusion, our data indicate that the time required for Er:YAG laser treatment was longer than that for the conventional mechanical method, but there was less pain associated with the Er:YAG laser treatment. There were no significant differences in the complete retention rate, marginal discoloration, and marginal adaptation between the two groups.