EFFECT OF THERMAL CYCLING ON MARGINAL SEAL OF DIFFERENT DENTIN SUBSTITUTES

Document Type : Original Article

Authors

1 Fixed Prosthodontics Department, October University of Modern Sciences and Arts, Faculty of Dentistry, Cairo, Egypt.

2 Doctorate of Operative Dentistry, Faculty of Dentistry, Cairo University, Cairo, Egypt.

3 Operative Dentistry Department, October University of Modern Sciences and Arts, Faculty of Dentistry, Cairo, Egypt.

Abstract

Objectives: To investigate the marginal seal of new dentin substitutes using environmental SEM and evaluate the longevity of the seal after being subjected to thermal stresses.
Methods: Four different dentin substitute materials (SDR, DENTSPLY; Sonic Fill, Kerr; Filtek Bulk Fill, 3M ESPE; and Fuji II LC, GC Corporation) were tested in this study. MOD cavities (4mm depth and half of the intercuspal distance width) were prepared on eighty human sound extracted premolars. Teeth were divided randomly into four groups according to the tested material. Each group was further divided into two subgroups (n=10): subgroup A; No thermal cycling was applied, and subgroup B; was subjected to thermal cycling (5±2 ºC - 55±2 ºC for 1000 cycles). The teeth were sectioned vertically through the resin composite parallel to their long axis in mesiodistal direction. Specimens were then tested for gap formations along pulpal dentin interface using Environmental SEM. Data were tabulated and statistically analyzed.
Results: Regardless of thermal cycling; Fuji II showed the statistically significantly highest mean gap distance (26.6 ± 12.6). Sonic Fill showed statistically significantly lower mean value (23.4 ± 4.3). There was no statistically significant difference between Bulk Fill (17.5 ± 1.7) and SDR (16.3 ± 1.5); both showed the statistically significantly lowest mean gap distance. Without thermal cycling, Sonic Fill showed the statistically significantly highest mean gap distance (19.4 ± 1.2). No statistically significant difference was found between Filtek Bulk Fill (16.1 ± 1.0), SDR (15.3 ± 0.9) and Fuji II (14.6 ± 0.7); all showed the statistically significantly lowest mean gap distances. While with thermal cycling, Fuji II (38.5 ± 0.9) showed the statistically significantly highest mean gap distance. Sonic Fill showed statistically significantly lower mean value (27.3 ± 0.9). There was no statistically significant difference between Filtek Bulk Fill (18.9 ± 0.7) and SDR (17.4 ± 1.2); both showed the statistically significantly lowest mean gap distance.
Conclusions: Under the test conditions, Bulk Fill and SDR provided an adequate marginal seal, regarding gap distance, when compared to Sonic Fill and Fuji II. Meanwhile, thermal cycling significantly increases gap distance in all tested dentin substitutes, thus affecting longevity.

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