Effect of Cavity Disinfection Protocols on Microtensile Bond Strength of Universal Adhesive to Dentin
At a Glance
Section titled “At a Glance”| Metadata | Details |
|---|---|
| Publication Date | 2022-05-10 |
| Journal | Odovtos - International Journal of Dental Sciences |
| Authors | Dilber Bilgili Can, Ayşe Dündar, Çağatay Barutçugil |
| Institutions | Akdeniz University, Van Yüzüncü Yıl Üniversitesi |
| Citations | 4 |
| Analysis | Full AI Review Included |
Executive Summary
Section titled “Executive Summary”This study investigates the impact of various cavity disinfection protocols on the microtensile bond strength (µTBS) of a 10-MDP containing universal adhesive (G-Premio Bond) applied to dentin.
- Core Finding: All tested cavity disinfection procedures (Chlorhexidine, Ozone, Er,Cr:YSGG Laser) significantly decreased the µTBS of the resin-dentin interface compared to the untreated control group (35.13 ± 6.20 MPa).
- Lowest Performance: The lowest bond strengths were recorded for the Laser (19.25 ± 4.66 MPa) and Chlorhexidine (CHX) (23.07 ± 7.01 MPa) groups.
- Failure Mode Correlation: Groups with low µTBS (CHX and Laser) exhibited a high tendency toward adhesive failure (95%), indicating weak bonding at the resin-dentin interface.
- CHX Mechanism: The reduction in bond strength is hypothesized to be due to competitive chemical interaction between CHX and the 10-MDP monomer, potentially inhibiting the chemical bonding of MDP to dentin calcium ions.
- Laser Mechanism: Laser irradiation likely caused thermal damage, leading to melting and evaporation of collagen fibrils, which subsequently hindered the diffusion and penetration of the adhesive resin.
- Microstructural Evidence (CLSM): Confocal Laser Scanning Microscopy confirmed that the control group achieved the most prominent nano-layering and distinct resin tags, correlating directly with the highest mechanical strength.
Technical Specifications
Section titled “Technical Specifications”| Parameter | Value | Unit | Context |
|---|---|---|---|
| Control Group µTBS (Mean ± SD) | 35.13 ± 6.20 | MPa | Highest bond strength (No treatment) |
| Laser Group µTBS (Mean ± SD) | 19.25 ± 4.66 | MPa | Lowest bond strength (Er,Cr:YSGG) |
| CHX Group µTBS (Mean ± SD) | 23.07 ± 7.01 | MPa | Low bond strength (2% Chlorhexidine) |
| Ozone Group µTBS (Mean ± SD) | 27.53 ± 5.83 | MPa | Intermediate bond strength |
| Laser Wavelength | 2780 | nm | Er, Cr: YSGG laser source |
| Laser Power Output | 0.75 | Watts | Low power setting for disinfection |
| Laser Pulse Duration | 140 | microseconds | Applied to dentin surface |
| Adhesive Functional Monomers | 10-MDP, 4-MET | N/A | G-Premio Bond composition |
| Specimen Cross-Sectional Area | 1 x 1 | mm2 | Microtensile bond strength beam size |
| Curing Irradiance (Standard Mode) | 1000 | mW/cm2 | LED curing unit setting |
| Storage Temperature | 37 | °C | Distilled water immersion for 24h |
Key Methodologies
Section titled “Key Methodologies”The study employed standardized substrate preparation, specific disinfection protocols, and mechanical/microscopic analysis techniques.
- Substrate Preparation: Extracted human third molars were sectioned mid-coronally to expose flat dentin. Surfaces were wet-polished using 600-grit silicon carbide paper for 60s to establish a uniform smear layer.
- Disinfection Protocols (Pre-treatment):
- CHX: 2% Chlorhexidine gluconate applied via cotton pellet for 20s, followed by 10s air-drying.
- Ozone: Dental ozone generator applied to the dentin surface for 30s.
- LASER (Er,Cr:YSGG): 0.75W power, 15% water/15% air pressure, 140 microseconds pulse duration. Irradiation applied five times for 10s intervals (5s rest).
- Adhesive Application: G-Premio Bond (universal adhesive) was applied immediately after disinfection in self-etch mode, following manufacturer instructions.
- Curing and Restoration: The adhesive was light-cured for 10s. Composite resin (Charisma Smart) was built up incrementally (2mm increments) to 5mm height, with each increment cured for 20s.
- Microtensile Bond Strength (µTBS) Testing: Samples were sectioned into 1 mm2 beams (n=20 per group). Beams were secured and stressed at a crosshead speed of 1 mm/min until fracture.
- Microscopic Analysis (CLSM): For visualization of resin penetration, Rhodamine B fluorescent dye (0.008%) was incorporated into the adhesive. Samples were examined using a Zeiss Lsm 510 Meta CLSM at 40x magnification, utilizing 543nm and 489nm lasers.
Commercial Applications
Section titled “Commercial Applications”The findings are critical for optimizing clinical protocols and material selection in restorative dentistry, focusing on interface integrity and long-term restoration success.
- Adhesive System Formulation: Provides data on the chemical compatibility of functional monomers (like 10-MDP) with common antimicrobial agents (CHX). This informs the development of next-generation universal adhesives designed for robustness against pre-treatment residues.
- Laser Dentistry Protocol Development: Establishes specific Er,Cr:YSGG laser parameters (0.75W, 2780nm) that, while effective for disinfection, negatively impact dentin bonding. Engineers must optimize laser settings to achieve sterilization without causing thermal damage that compromises the collagen matrix and subsequent resin infiltration.
- Surface Pre-treatment Standardization: Demonstrates that ozone application, while reducing bond strength, performs significantly better than CHX or Laser treatment. This supports the use of ozone as a less detrimental disinfection option when using MDP-based self-etch adhesives.
- Biomaterial Failure Analysis: The high incidence of adhesive failure (95%) in the CHX and Laser groups serves as a benchmark for unacceptable interface integrity, guiding quality control standards for dental materials and procedures.
- Hybrid Layer Engineering: CLSM results link the quality of the hybrid layer (nano-layering and resin tag formation) directly to mechanical performance, emphasizing the importance of maximizing monomer diffusion into the dentin substrate.
View Original Abstract
The purpose of this study was to compare the effect of different disinfection protocols of dentin on bond strength of an MDP-containing universal adhesive. Twelve extracted mandibular third molars were separated horizontally at the mid-coronal of crown to get smooth and sound dentin surfaces using low-speed diamond saw. The teeth were randomly fallen into four groups: chlorhexidine (CHX), ozone, Er,Cr:YSGG laser irradiation (LASER) and no treatment (control). After cavity disinfection application, a universal adhesive (G-Premio Bond) was applied to the surface of dentin according to self-etch mode as instructed by the manufacturer. After incremental built-up of composite resin (Charisma Smart), the specimens were immersed in distilled water at 37°C for 24h. Dentin/composite beams with 1 mm² cross sectional area were produced and micro-tensile bond strength (µTBS) was applied on these beams (n=20). Failure mods were determined under a stereomicroscope at ×40. The resin penetration of samples stained with Rhodamine B fluorochrome dye was examined with a confocal laser scanning microscope. Statistical analysis was performed with SPSS-22. Test results were analyzed using One-way Anova and Tukey HSD Post-Hoc tests (p<0.05). The µTBS value of control (35.13±6.20) was the highest statistically among the groups (p<0.05). The lowest µTBS were obtained by LASER (19.25±4.66) and CHX (23.07±7.01). There was no significant difference between CHX and LASER, and between CHX and ozone (p>0.5). All applications of cavity disinfection procedures decreased the µTBS of the resin-dentin interface.