Der Einfluss unterschiedlicher Provisorien auf den Komposit-Dentin-Verbund bei Komposit-Inlays

Introduction: In the present study it should be investigated to what extend the composite-dentin bond strength of resin composite inlays is influenced by temporary cements (UltraTemp®, Ultradent Products Inc., Utah, USA; Temp Bond™ and Temp Bond NE™, Kerr Hawe S.A., Bioggio, Schweiz) having been applied in dental cavities prior to the actual luting prcess. In addition, methods for removal of temporary cements should be considered, too. Methods: In this experimental in vitro study, 48 caries and filling-free human third molars were used (with or without completed root development). These teeth were randomly assigned to twelve groups (n=4). Each specimen received a conical occlusal Class-I preparation. Resin composite inlays were manufactured (Venus® Diamond PLT Refill) directly in the cavities. After the inlay´s removal, cavities were filled with several temporary cements, i.e. UltraTemp® (group 4 to 6), Temp Bond™ (group 7-9) and Temp Bond NE™ (group 10-12). These were removed from the cavity by either a scaler only (H6/H7, Hu-Friedy, Leimen, Germany; Gr. 4, 7, 10), a scaler plus pumice slurry (Gr. 5, 8,1 1) or an air abrasion device (KaVo Rondoflex plus 360 with Al2O3 27µm, KaVo Dental GmbH, Biberach, Germany; Gr. 6, 9, 12). Groups 1 to 3 were control groups without any provisorial pretreatment. In the next step, all cavities were conditioned by the multi-bottle adhesive system Syntac® (Ivoclar Vivadent, Schaan, principality of Liechtenstein). Thereafter the inlays were cemented using the flowable resin composite Tetric EvoFlow (Ivoclar Vivadent). In the following step the specimens were cut using a slow-speed diamond saw resulting in slices and sticks (Isomet 1000, Buehler, Lake Bluff, IL, USA). Sticks were loaded in tension until failure occurred using a universal testing machine (Microtensile MTD-500 Plus, Universal-Prüfmaschine, SD-Mechatronik GmbH, Feldkirchen, Germany) at a crosshead speed of 0.5 mm/min. The composite-dentine-interface was qualitatively analysed using a scanning eletron microscope (REM Phenom, Phenom World BV, Eindhoven, Netherlands). The results of the microtensile bond strength test were statistically analysed by the SPSS 14.0 software (SPSS Inc., Chicago, IL, USA). Results: It could be shown that more the choice of removing method than the temporary cement´s material negatively influenced the composite-dentin bond strength. In comparison with the control groups without provisorial pretreatment, only the experimental groups treated with a sandblaster showed comparable results (p>0.05). Cement emoval by scaler was shown to be an inadequate method pertaining to dentin bond strength. According to the statistical analysis there were no essential differences between the temporary cements (p>0.05). Only experimental group 5 (UltraTemp® with scaler / pumice slurry) showed a significant increase of dentin bond strength compared to other groups pretreated with other temporary cements using the same method of removal. Finally it should be stated, that the provisorial pretreatment with temporary cements negatively influenced bond strength compared with the result of control groups regardless which kind of type was used.