In vitro evaluation of marginal degradation of composite restorations

Shiro Suzuki, DDS, PhD,(a) Hisanori Kurashige, DDS,(b) and Takuo Tanaka, DDS, PhD(b)

(a)Department of Prosthodontics and Biomaterials, University of Alabama at Birmingham School of Dentistry, Birmingham, AL, USA, and (b)Department of Fixed Prosthodontics, Kagoshima University Dental School, Kagoshima, Japan

Purpose: The purpose of this study was to evaluate the effect of occlusal stressing on marginal integrity of multiple composite restorations in the same tooth.
Materials and Methods: Class V cavities were prepared on buccal and lingual surfaces of 42 extracted human maxillary premolars. Cavo-surface margins were placed in enamel on the incisal wall and in cementum on the gingival wall. Class II (MOD) cavities were also prepared on the same tooth. Class V cavities were restored with a direct composite. For Class II cavities, one-half numbers of the specimens were restored with the direct composite, and the remainders were restored with an indirect composite. The specimens were mounted on two different loading devices (vertical and sliding types) and repetitively loaded with 75 N at 1.2 Hz for 100,000 cycles. Seven specimens were used for each simulation. The tested specimens were immersed into 5% methylene blue solution for two hours, and the lengths of marginal staining and depth of dye penetration were evaluated. The values at each area were averaged, and the data were statistically analyzed by analysis of variance (ANOVA). The differences between gingival and occlusal microleakage; vertical loading and vertical with sliding; and direct and indirect restorations were determined with Fisher’s PLSD test (p<0.05).
Results: The results indicated that all of the gingival margins on Class V restorations exhibited greater deterioration compared to occlusal margins.
Conclusion: It is suggested that the cementum/restoration interface had less durability compared to enamel/restoration interface.
(Int Chin J Dent 2002; 2: 143-150.)

Clinical Significance: Clinicians need to realize that cementum margin of Class V composite restoration will be affected by occlusal stress when Class II restoration is placed on the same tooth.
Key Words: class V restoration, composite, in vitro test, marginal degradation, occlusal stress.