This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. The subproject and investigator (PI) may have received primary funding from another NIH source, and thus could be represented in other CRISP entries. The institution listed is for the Center, which is not necessarily the institution for the investigator. Posterior resin composites are used by 80% of the dentists practicing in the United States. The results of the first clinical trial of posterior composites were published in 1971. Subsequent recalls of the same restorations revealed that the resin composite restorations had poor wear resistance. Early reviews recommended that composite be limited to conservative bicuspid and first molar restorations where esthetics was critical. In spite of improvements in resin composites, material limitations exist which restrict the use of resin composite as a posterior restorative material. Clinically, resin restorations are difficult and require more placement time tkhan a similar sized amalgam restoration. Interproximal contacts are difficult to obtain since composite is a paste material that shrinks during polymerization; two clinical investigations reported weak or defective contacts in 20% of the posterior composite restorations. The development of recurrent caries is a clinical problem with composite resin restorations primarily due to polymerization shrinkage and opening of the restoration gingival cavosurface margins. At present, the best means of diagnosing interproximal recurrent caries is with bitewing radiographs, which records demineralization (the loss of mineral content of the enamel and dentin) as a corresponding decrease in rediographic density. Further developments of composite resin with more wear resistance, reduced polymerization shrinkage and improved adhesive systems with stronger bonds to tooth structure are needed. This study will evaluate the clinical success of a composite with reduced polymerization shrinkage placed in class 1 and class 2 preparations to evaluate whether the composite will pass the certification program established by the American Dental Association.
Specific Aims : 1. To place a composite resin in Class I and Class II cavity preparations, evaluate the resin composite restorations at baseline, 6 months, 1 year, and 18 months for specific criteria (direct and indirect). 2. To evaluate the resin composite restorations for staining, marginal integrity, response to cold, placement time, and proximal contact for 18 months.
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