Dentin Pre-Treatment to Suppress Microleakage of Amalgam Restorations

Diminished microleakage of amalgam-to-dentin preparations would benefit large populations in public health facilities. Prior studies demonstrated less microleakage for bonded amalgams than similarly bonded advanced composites among 30 different composite/bonding agent/storage conditions, Haller et al. showed that a combination of formaldehyde pre-treatment and glutaraldehyde-containing Syntac adhesive minimized microleakage. In the current study, CLass V restorations (groups of 10 formaldehyde-treated non carious human molars) were filled with Valiant (Ivoclar NA) amalgam after application of one of three liners: Copalite varnish; Amalagambond Plus with microfiber; and Syntac/Variolink. The control group used no liner material. After 24 hours at 37°C/100% RH, samples were thermocycled (1000 eyeles) in water at 5°C and 60°C (15 second dwell time in each). Samples were immersed in 5% methylene blue solution (4 hrs) and observed under a stereomicroscope; interfaces also were examined by SEM. Krsukal Wallis ANOVA by ranks (P<0.01) and Mann Whitney U Tests (P<0.05) of the data indicate improvements (equivalent among the 3 different liners tested here) over unlined amalgam preparations. Liner/aldehyde-crosslinked dentin interphases, without technique-sensitive composites, may minimize microleakage by improving amalgam contact (physical) bonding