Photodynamic Therapy (PDT) in Prosthodontics: Disinfection of Human Teeth Exposed to Streptococcus mutans and the Effect on the Adhesion of Full Ceramic Veneers, Crowns, and Inlays: An In Vitro Study

Primary Dentin Conditioning with Methylene Blue Activated Photodynamic Therapy, Phytic Acid, and Er,Cr:YSGG to Resin-Modified Glass Ionomer Cement in Comparison to Conventional Polyacrylic Acid

Aim: Impact of surface conditioner phytic acid (IP6) Er,Cr:YSGG laser (ECYL) methylene blue photodynamic therapy (MB-PDT) on the microleakage and shear bond strength (SBS) of resin-modified glass ionomer cement (RMGIC) to primary sound dentin. Material and method: Overall, 80 extracted sound primary molars were collected followed by their submergence in self-cure acrylic resin. The dentin surface was exposed and made flat and was assigned into four groups based on the surface conditioning. Group 1: polyacrylic acid (PAA), Group 2: 1% IP6, Group 3: ECYL, and Group 4: MB-PDT. RMGIC restorative material was bonded to primary dentin. Marginal leakage assessment was performed using silver nitrate. SBS and failure mode assessment were performed using a universal testing machine and stereomicroscope. Mean and standard deviations of SBS and marginal leakage were compared using analysis of variance and multiple comparisons of Tukey's post-hoc test (p < 0.05). Results: MB-PDT treated specimens displayed the highest values of marginal leakage (37.56 ± 1.25 nm) and lowest SBS (7.93 ± 1.03 MPa). However, samples in Group 2 conditioned with IP6 presented the lowest dye penetration score (11.23 ± 1.22 nm) and highest bond strength scores (11.12 ± 0.82 MPa). Conclusions: IP6 and ECYL have proved to be better alternatives in terms of low microleakage and improved SBS scores to PAA as a primary dentin surface conditioner for bonding RMGIC restoration. Conversely, MB-PDT, when employed as a dentin surface conditioner for RMGIC restorations, exhibited suboptimal results, characterized by elevated microleakage and compromised bond strength.

Hybrid ceramic repair strength, surface roughness, and bond failure, using methylene blue-activated low-level laser therapy, Carbon dioxide, and Ti: Al2O3 laser

AIMS

To evaluate the impact of various pretreatment regimes (LLLT, Ti-sapphire laser, CO2, and HFA-S) on hybrid ceramics, specifically focusing on their ability to enhance repair strength and minimize surface roughness (Ra).

MATERIAL AND METHODS

Discs were made from hybrid ceramics and after disinfection were randomly divided into four groups based on different surface conditioning techniques. Each group consisted of 15 discs, resulting in a total sample size of 60. dics in group 1 was surface treated with Low-level laser therapy (LLLT) using methylene blue (MB), Discs in group 2 with Ti-sapphire laser, Discs in group 3 with CO2 laser, and discs in group 4 with HFA-S. Five samples from each group were assessed for Ra. The remaining 10 samples from each group underwent repair using a porcelain repair kit in adherence to the planned instructions. The bond strength of each sample in all groups was measured using a universal testing machine. Following the bond strength testing, the specimens from all study groups were analyzed to determine the mode of failure. To evaluate the data, a two-way analysis of variance (ANOVA) was used, followed by post hoc multiple comparisons.

RESULTS

The highest repair bond strength was observed in group 4 hybrid ceramics pretreated with HFA-S (19.05±0.79 MPa). The lowest repair bond scores were observed in group 1 hybrid ceramics preconditioned with LLLT in the presence of Photosensitizer (13.41±0.36 MPa). The highest Ra scores were exhibited in group 2 surface treated with Ti-sapphire laser (0.0515±0.16 µm) and the lowest Ra scores were observed in Group 4 HFA-S (0.0311±0.79 µm). Predominant bond failure among different investigated groups was cohesive.

CONCLUSION

The current gold standard for hybrid ceramic conditioning is the use of hydrofluoric acid (HFA) combined with a silane coupling agent. Low-level laser therapy with methylene blue photosensitizer is not recommended for the treatment of hybrid ceramics.

Photodynamic Therapy

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