Photodynamic activation of irrigation (using different laser prototypes) on push out bond strength of fiber posts

Influence of resin cements and root canal disinfection techniques on the adhesive bond strength of fibre reinforced composite post to radicular dentin

AIM

To determine the push out bond strength (PBS) of fibre reinforced composite post (FRCP) bonded to radicular dentin using different cement types total etch resin cement (TERC) and Self-adhesive resin cement (SARC) conditioned with (PDT, 5.25 % NaOCl with EDTA and 1% NaOCl) MATERIALS AND METHODS: Sixty freshly extracted (orthodontic purpose) human single rooted mandibular premolars were collected. Teeth were disinfected and coronal part of all samples were removed. Cleaning shaping and finishing of canal space was performed and filled with gutta percha via lateral condensation. Post space was prepared and disinfected with three irrigating solutions. Samples in group 1 and 2 disinfected 5.25 % NaOCl with EDTA, group 3 and 4 steriled with 1% NaOCl and group 5 and 6 disinfected with Methylene Blue photodynamic therapy (PDT). Based on the resin cement, FRCP was luted with TERC in group 2, 4 and 5; and with SARC in group 1,3 and 6 respectively. All specimens were subjected to aging and push-out bond strength (PBS) on universal testing machine after sectioning of each sample in three segments (coronal, middle and apical). Following push out bond strength (PBS), debonded surface were observed under stereomicroscope at 40x magnification. PBS were equated by means of analysis of variance (ANOVA) and Tukey's post hoc test maintaining level of significance (p < 0.05) RESULTS: Group 1 (SARC) and 2 (TERC) disinfected with 5.25 % NaOCl with 17 % EDTA, TERC (group 2) showed higher extrusion bond strength at all three levels coronal (9.25 ± 0.21 MPa) middle (8.81 ± 0.94 MPa) and apical (8.21 ± 0.93 MPa). Whereas, canal space sterilized with 1% NaOCl [group 3 (SARC) and group 4 (TERC)], posts cemented with TERC exhibited the higher PBS at all three levels of root canal (10.22 ± 0.36 MPa), (9.68 ± 0.51 MPa), (6.33 ± 0.08 MPa). Similarly, among PDT disinfected fiber post [group 5 (TERC) and group 6 (SARC)], TERC exhibited the greater PBS values at coronal, middle and apical levels (6.25 ± 0.39 MPa) (5.17 ± 0.22 MPa) (4.32 ± 0.69 MPa) compared to SARC specimens CONCLUSION: Irrespective of canal irrigant, fiber post bonded with TERC showed higher PBS at coronal and middle third. Fiber post bonded with SARC when irrigated with 5.25 % NaOCl with EDTA, 1% NaOCl displayed higher PBS at apical third. Canal disinfected using PDT showed lower PBS for FRCP compared to 5.25 % NaOCl with EDTA and 1% NaOCl.

Impact of photodynamic therapy on the push-out bond strength of fiber posts to root dentin: A systematic review and meta-analysis

BACKGROUND AND PURPOSE

This systematic review documents the up-to-date evidence on the efficacy of photodynamic therapy (PDT) on the push-out bond strength of fiber posts cemented to root dentin.

MATERIALS AND METHODS

The focused PICO question was: "What impact does PDT have on the push-out bond strength of fiber posts cemented to root dentin?" This systematic review followed the guidelines and recommendations reported in the Preferred Reporting Items for Systematic Review and Meta-Analysis (PRISMA) guidelines chart. An electronic search was performed in MEDLINE/PubMed, SCOPUS, Web of Science, and Embase from January 1980 up to and including January 2020. Heterogeneity was calculated for push-out bond strength by means of the Chi-square test and I² statistics. For meta-analyses, if the I² was higher than 50 %, a random effects model was used, otherwise a fixed effects model for I² ≤50 % was applied. A p-value <0.05 was set for significant heterogeneity. Forest plots were computed reporting standard mean differences (SMD) of outcomes and 95 % confidence intervals (CI).

RESULTS

In total, ten studies were included, all of wich demonstrated medium risk of bias. All studies tested the push-out bond strength by means of a universal testing machine with applying a load ranging between 0.5 and 1 mm/min speed. Of the 10 studies, nine (90 %) indicated that PDT had no effect on push-out bond strength of fiber posts to root dentin. Only one study indicated that PDT significantly improved the bond strength when compared with other control groups. The overall mean difference for push out bond strength showed no statistically significant difference between PDT and the control group (SMD = -1.11 [-3.25, 1.02], Z=-1.02, p = 0.305).

CONCLUSION

This systematic review concludes that PDT has no effect on improving the push-out bond strength of fiber posts to root dentin.

Efficacy of chlorhexidine, Er Cr YSGG laser and photodynamic therapy on the adhesive bond integrity of caries affected dentin. An in-vitro study

AIM

To evaluate the adhesive bond integrity (shear bond strength-SBS) of composite resin bonded to carious dentin using chlorhexidine gluconate (CHX), Er,Cr:YSGG laser (ECYL) and photodynamic therapy (PDT).

MATERIAL AND METHODS

Thirty carious and ten non-carious mandibular teeth were collected through non-traumatic extraction. All samples were embedded in polyvinyl cross-sections to the cemento-enamel junction. The preparation of caries-affected dentin was performed by grinding the specimens using silicon carbide discs. All specimens were randomly allocated in to four groups (n = 10). Group 1, non-affected dentin with no disinfection; Group 2, caries affected dentin treated with 2% CHX; Group 3, affected dentin disinfected with PDT [100 mg/L methylene blue solution (MBS) and Diode laser]; Group 4, affected dentin treated with ECYL. Self-etch adhesive was smeared on all specimens for 10 s and photopolymerized for 10 s. All specimens were placed in an incubator with humid environment for 24 h at 37 °C followed by positioning in universal testing machine for SBS testing. Failure mode examination of debonded samples was performed by a stereomicroscope. Analysis of variance (ANOVA) was used for inter group comparison through mean and standard deviation of each group. For multiple group comparison Tukey HSD was employed. Level of significance was established at p < 0.05.

RESULTS

The highest SBS value was observed in group 1 (24.98 ± 1.59 MPa). Whereas, the lowest bond strength was displayed by group 3 (14.22 ± 1.40 MPa) specimens. Lased dentin in group 4 (15.89 ± 3.22 MPa) exhibited SBS values comparable to group 3 (14.22 ± 1.40 MPa). Group 2 (CHX-18.25 ± 1.29 MPa) exhibited statistically significant difference compared to all experimental groups (p < 0.05).

CONCLUSIONS

Adhesive bond strength of disinfected carious dentin was higher with CHX treatment as compared to Photodynamic therapy and Er,Cr: YSGG laser treatment. Carious dentin showed lower bond strength to composite resin as compared to non-carious dentin.