Direct composite inlays versus conventional composite restorations: 5-year follow-up

To determine at 5 year follow-up the failure rate, wear rates and other aspects of clinical performance of direct composite inlays compared with conventional composite restorations placed incrementally.

100 matched pairs of restorations were originally entered into the trial. Each pair consisted of a direct composite inlay and a conventional composite restoration made from the same material. At 5 years it was possible to recall 65 pairs, of which 54 were complete. Clinical assessments were made using USPHS criteria (indirect measurements of occlusal wear were made using Ivoclar standard dies) and annual bite wing radiographs.

There was a trend to more failure of inlays than conventional composites (17.4 c.f. 7.5%) but this was not significant. The clinical performance of both types of restoration was similar and compared favourably with the results of studies of other materials. Secondary decay was diagnosed in only one restoration. Between 3 and 5 years there was some deterioration in cavo-marginal discoloration, marginal adaptation (occlusally) and surface roughness (occlusally). There was no apparent deterioration in colour match, proximal contact, shim stock contacts and Gingival Index. Wear rates of both types of restoration showed no significant difference and were essentially linear with a mean of 33-34 microm per year.

Both inlays and conventional composite restorations complied with ADA specification minimum requirements for posterior composite restorations. In this study the direct inlay technique gave no clinical advantage over conventional, incremental placement.