Evaluation of the Effect of Atmospheric Pressure Variations on the Marginal Seal of Class I Composite Resin Restorations Bonded with a Three-Step Etch-and-Rinse Adhesive: An In Vitro Study

Abstract

Background: The durability of composite resin restorations under pressure variations (e.g., diving, air travel, hyperbaric oxygen therapy) remains a concern due to potential microleakage at the tooth–composite interface.

Objective: To assess whether a single exposure to hyperbaric or hypobaric pressure affects the marginal sealing of Class I cavities restored using a three-step etch-and-rinse adhesive system (Optibond FL).

Methods: Forty extracted human molars were randomly assigned to eight groups (n = 5) and restored with Ceram.x Spectra ST HV composite resin following standard adhesive protocols. The groups were exposed to simulated hyperbaric (up to 3.5 × 10³ hPa) or hypobaric (down to 0.75 × 10³ hPa) conditions for varying durations. One group served as a control (no pressure change). Specimens were immersed in 1% methylene blue dye for 24 hours, sectioned, and analyzed using a VR-H4J profilometer to measure dye penetration at the tooth–composite interface. Data were analyzed using the Shapiro–Wilk test and Kruskal–Wallis test (? = 0.05).

Results: No statistically significant differences in microleakage were observed between the control group and pressure-exposed groups (p > 0.05). In total, 87.5% of the samples showed no detectable microleakage. Only 5 out of 40 teeth showed minimal dye penetration.

Conclusion: Within the limits of this in vitro study, a single exposure to hyperbaric or hypobaric conditions did not affect the marginal integrity of Class I restorations bonded with the ER3 adhesive system. Pressure variations of the magnitude and duration tested appear unlikely to compromise the seal when proper adhesive protocols are followed.