Evaluation of the adaptation and resistance properties of provisional restorations fabricated via conventional and digital methods for teeth prepared with differentfinish line geometry

Provisional restorations are prostethic restorations manufactured for preserving the pulp of the prepared tooth, providing stability, maintaining the health of the surrounding periodantal tissues and providing an occlusal function for period of time between tooth preperation to cementation of the permanent restoration. Nowadays provisional restorations can be manufactured by using variety of different materials and techniques. These manufacturing techniques can be divided in to two catalogues as conventional and digital. Conventional fabrication methods have been used for a long time from past to present and ensures the production of a restoration with a high success rate. Restorations can be manufactured with digital fabrication techniques using CAD-CAM milling devices and 3D printers. The development of digital technology has accelerated the process of design and producing of restorations and ensured more precise production. To sustain the function of the temporary restoration in an oral environment for long term, the provisional restoration has to have a good marginal adaptation and a high resistance to the occlusal forces. The restorations that don't have good marginal fit will have poor sealing. The restorations with poor sealing features will allow the oral fluids reach to the prepared tooth that is under the restoration and cause problems like sensitivity and decementation by allowing dissolution of the temporary cement. On the other hand, the restorations with low resistance is prone to having cracks and breaks under the occlusal stresses. As a result of these problems, tooth sensitivity, periodontal tissue and aesthatic problems will arise The constant development of digital technology necessitates knowing the weaknesses and strengths of digital methods in comparison to conventional methods. Therefore, this thesis study, compares the harmony and resistance of the provisional restorations fabricated with different methods. For this thesis study, extracted upper premolar teeth were prepared using three different finish lines (chamfer, feather, shoulder) and for these teeth, provisional restorations were fabricated using four different methods: CAD-CAM milling (inLab MCX5, Sirona Dental Systems, USA), 3D Printing (Formlabs, USA), by a dental technician (Imicryl, IMIDENT, Turkey), direct production (Hexa-temp, Spident, Korea). Each and every groups sample size has been determined as n=10. The models of each teeth, have been obtained by using 3D printer (Nexdent 5100, Nextdent, Netherlands) before and after the preparation. After the production of restorations, marginal, axial and occlusal cement space have been mesured with silicone replica technique. Afterwards marginal adaptation of the restoration have been examined with micro-CT display methods. Afterwards a light body impression material (Elite HD+, Zhermack, Italy) was placed inside the temporary restorations and the impression materials that mimics the cement space were compared with each other by measuring their weights on a digital scale (RADWAG Wagi Elektroniczne, Poland). At last with the purpose of surveying the resistance of the restorations, the provisional restorations had been fractured using compressive forces under the universal testing device and values of failure have been registered.The obtained data have been analized by the two factor (finish line and production technique) factorial analysis of variance (Factorial ANOVA). Duncan Multi Comparision Tests have been used for determining the different groups. The restorations that have been produced showed clinically acceptable results in terms of marginal adaptation. While the finish line that have been used did not influenced the marginal adaptation, it has influenced the internal adaptation of the restorations. The resistance of the restorations differed according to production method and finish line.