Clinical longevity of extensive direct composite restorations in amalgam replacement

Method: Between January 2007 and June 2012, a total of 88 patients (57 women, 31 men; mean age: 51 years old) received extensive cusp replacing DRCs (N=118) in the posterior teeth. DRCs were indicated for replacement of existing amalgam restorations where dentin substrates were stained by amalgam. After employing 3-step total-etch adhesive technique (Quadrant Unibond Primer, Quadrant Unibond Sealer, Cavex), cavities were restored using a hybrid composite (Clearfil Photobright, Kuraray). At baseline and thereafter every 6 months, restorations were checked upon marginal integrity, anatomical contour, food impaction, secondary caries, fractures and endodontic problems. Restorations were scored as failed if any operative intervention was indicated for repair, partial or total replacement.

Result: Restorations were observed for a minimum of 7, and maximum 70 months (mean: 30 months). In total, 4 failures were observed due to fracture (n=1), endodontic complication (n=2) and inadequate proximal contact (n=1). Failures were neither related to inadequate adhesion, nor to secondary caries. Cumulative survival rate was 96% up to 70 months (Kaplan-Meier) with an annual failure rate of 0.6%.

Conclusion: The null hypothesis was rejected. In case of amalgam replacement, stained dentin by amalgam constituents does not impair clinical longevity of extended cusp replacing direct resin composite restorations.