PBE를 이용한 구치부 간접 레진 복합 수복물의 임상적 평가

The rehabilitation of decayed or fractured posterior teeth using an indirect technique was introduced for large cavities with coverage of one or more cusps. Problems of biological nature and technical operative may be encountered when restoring large cavities extending below the cement-enamel junction(CEJ).

Biological problems refers to the possible violation of the 'biological width', a recommended distance of 3 mm or more between the restorative margins and the alveolar crest. The technical operative problems include difficulties in tooth preparation, impression making, adhesive cementation of the restoration, finishing and polishing in subgingival areas. In order to eliminate these difficulties Proximal Box Elevation' (PBE) was introduced that proposes application of composite resin in the deepest parts of the proximal areas in order to reposition the cervical margin supragingivally. Whether the PBE technique is the most optimal treatment option for the restoration of cavities extending below CEJ and how the proposed advantages and possible disadvantages could affect the clinical performance of the indirect restorations are the topics extensively discussed among clinicians.

According to results of in vitro studies, PBE was found to be effective in indirect resin composite bonding to deep proximal boxes in terms of marginal quality and adaptation (1).

In a retrospective clinical study, 79 indirect composite restorations were clinically examined following modified United States Public Health Service criteria. Survival rate was 91.1% and success rate was 84.8% after 5 years (2). Similarly, in another clinical study success rate of 71 indirect composite restorations was reported as 100% after 36 months (3). Nevertheless, not much scientific evidence on the influence of PBE technique on the longevity of the restorations and the periodontal health could be found in the currently available literature. Randomized controlled clinical trials with classification of baseline clinical situation and standardization of cavity preparations are necessary to evaluate the clinical performance of this technique.

This study will be carried out as a prospective study, with assessment of the restorations after three years. 80 indirect composite restorations in at least 60 patients will be included. Potential patients attending to Istanbul Medipol University Dental Clinics in Istanbul will be invited to the study. The patients meeting the inclusion criteria will be recruited. After giving their consent to take part in the study, baseline clinical situation will be classified based on technical operative and biological parameters (4).

The treatment procedure is:

Restorative process in all cases, will start with coronal relocation of the margins using flowable composite with maximum thickness 1 to 1.5 mm and followed by resin composite build-up. Defined principles of morphology driven preparation technique will be followed for standardization of cavity preparations. Impression making, fabrication of indirect restoration with SR Nexco and adhesive cementation will be completed according to manufacturer's instructions.

The control procedure is:

The restorations will be evaluated according to marginal adaptation, cavo surface marginal discoloration, approximal contact, fractures and caries associated with restorations. The periodontal status will be assessed with defined periodontal parameters. The controls will be conducted after two weeks, six months, 1year, 2 and 3 years.