A clinical evaluation of Class II composites placed using a decoupling technique

This study was undertaken to evaluate the three-year clinical performance of Class II restorations of a fine particle hybrid composite placed using a decoupling placement technique, whereby polymerization shrinkage stresses at the cervical tooth-restoration interface were minimized by separating the initial gingival increment of composite from the body of the restoration using a polyurethane varnish.

The study was a practice-based explanatory, single-center clinical trial. A minimum of 40 Class II restorations of the material under investigation (Tetric) was required to be placed in predominantly molar teeth in selected patients. The restorations were placed using a decoupling incremental technique, bonding being accomplished using Syntac and Heliobond. The restorations were reviewed within 1 month of placement, thereafter at 18 months, then at 2 and 3 to 4 years using predetermined codes and criteria. Impressions and photographic records were used to obtain retrospective, third-party assessments of the restorations.

Of 43 restorations originally placed and found to have ideal characteristics at baseline review, 41 (95%) were reviewed at 18 months, 36 (84%) at two years, and 31 (74%) at 3 to 4 years. None of the restorations were found to have suffered significant deterioration, notwithstanding three restorations having been lost to the study because of the replacement of part of the restored tooth for causes other than the catastrophic failure of the material. No secondary caries or postoperative sensitivity was recorded.

It was concluded that the findings support the use of the material under investigation in the restoration of moderate- to large-sized Class II preparations in selected patients. The decoupling placement technique employed may be found to be an effective means to limit postoperative sensitivity and to contribute to the favorable in-service performance of restorations of the type investigated. Good practice would now require a multicentered, randomized controlled trial to investigate the effectiveness of the material and, in particular, the decoupling technique under the conditions of everyday practice.