Clinical evaluation of etched porcelain onlays: a 4-year report.

Etched porcelain-bonded-to-enamel restorations (porcelain veneers) have demonstrated a low incidence of debonding, fracture, microleakage, and discoloration. In addition, laboratory and short-term clinical studies have shown satisfactory results with posterior etched porcelain-bonded restorations. This study evaluated the 4-year clinical performance of posterior all-ceramic onlays and overlays bonded with a dual-cure luting resin and a self-cure acetone-based dentinal adhesive. Twenty-one posterior porcelain overlay restorations were fabricated from a high-leucite-content porcelain and bonded to the teeth of 12 adults using a dual-cure luting resin and an acetone-based self-cure N(P-tolyl) glycine-glycdyl methacrylate (NTG-GMA), pyromellitic acid dianhydride and 2-hydroxyethyl methacrylate (PMDM) dentinal adhesive. Restorations were examined for retention, marginal caries, marginal microleakage, sensitivity, discoloration, restorative fracture, and patient satisfaction. Data collected at 4 years revealed 100% retention of the restorations with no marginal discoloration, marginal ditching, caries, or sensitivity. A small gap (Ryge UPHS rating of Bravo) was detected at the facial margin of one restoration but was not sufficient enough to require repair or replacement. Each patient reported a very high level of satisfaction with the restorations. This study demonstrates that porcelain overlays with supragingival margins entirely on enamel that rely primarily or entirely on bonding for their retention can provide excellent esthetics, good function, and perhaps long-term durability if properly designed, fabricated, and bonded. Porcelain overlays fabricated from high-leucite-content porcelain bonded to sound enamel and dentin with a dual-cure luting resin and a fourth generation dentinal adhesive provide satisfactory clinical results and high patient satisfaction.