Author(s):
1. Valentina Veselinović, Republic of Srpska, Bosnia and Herzegovina
2. Rebeka Rudolf, University of Maribor, Faculty of Mechanical Engineering, Slovenia
3. Aleksandra Grebenar, Medicinski fakultet Banja Luka , Republic of Srpska, Bosnia and Herzegovina
4. Sanja Gnjato, University of Banja Luka, Medical Faculty, Republic of Srpska, Bosnia and Herzegovina
5. Nataša Trtić, Republic of Srpska, Bosnia and Herzegovina
6. Verica Pavlić, PHI Institute of Dentistry, Banja Luka, Republic of Srpska, Bosnia and Herzegovina

Abstract:
Cements in the oral cavity are subjected to many factors affecting cement retention, the major ones being masticatory loads and thermal stress. The gold standard in cementing restorations in the contemporary implant prosthodontics are resin cements while their predisposition to the effects of oral cavity environment presents a major factor for the efficiency of dental implant treatment. MATERIAL AND METHOD In the study, we used 40 test models made up of a combination of original components of the Nobel Biocare system (implant replica NobRplN and titanium suprastructure Easy abatement NP 0.75) and the restoration cast in CoCrMo alloy. The specimens were divided in 4 test groups with 10 specimens each. The specimens in each group were cemented with resin composit cement with or without using the metal primer. Group I – Multilink Implant, IvoclarVivadent, Liechtenstein, Group II – Multilink Implant, IvoclarVivadent, Liechtenstein + Monobond Plus, Group III G-CEM LinkAce®, Group IV - G-CEM LinkAce® + GC Metalprimer II. The specimens were stored in 100% relative humidity for 24 hours whereupon each group underwent 5 rounds of testing. The specimens were subjected to thermal and mechanical load cycling tests whose number reflected the period of simulation of the function in the oral cavity (unloaded specimens, 7 days of function, 3 months, 6 months and 12 months). The retention force was measured by the Universal testing machine. RESULTS The highest retention values of the resin composite cement were recorded during the initial tests, which then declined in the subsequent rounds of testing. The biggest fall was measured in the first week after the cementation, while the cross-comparison of the later rounds of testing did not show any statistically significant differences. The values of the retention force of resin composite cements 12 months after the cementation dropped by one third of the initial values. All recorded values were higher in the specimens with primer coating. CONCLUSION Masticatory forces and temperature changes in the oral cavity reduced the retention values of resin cement but its values after 12 months of function were still high and provided stability and retention of the restoration in function. The usage of metal primer had a significant effect on retention force values at all levels of testing.

Key words:
implantoprosthetics,composite cements,retention,mechanical cycling loading,temperature fluctuations,metal primers

Thematic field:
SYMPOSIUM B - Biomaterials and nanomedicine

Date of abstract submission:
12.07.2016.

Conference:
Contemporary Materials 2016 - Savremeni Materijali