Effect of implant angulations on the accuracy of multi-implants implant level impression using different materials and techniques

Algellay A. M. (2018). Effect of implant angulations on the accuracy of multi-implants implant levelusing different Materials and techniques. Yeditepe University, Institute of Health Science, Department of prosthodontics, MSc thesis, İstanbul. This study aimed to evaluate the effect of implant angulation on the accuracy of multi implant impression using different material and techniques. A master model with four internal connection implants was prepared. With two implants placed anteriorly in canine region with 0°, and two implants placed posteriorly in the first molar region with 30°, which simulating the protocol of all on four. 40 impression were performed on the master model using two different techniques (direct splinted and indirect snap-on) and two different material (polyvinyl siloxane and polyether). Models where divided into four groups (n=10). Models where scanned with 3D shap scanner. STL file where anaylzed and measurements where performed using 3D design program (Rhinoceros 0.5), to measure the discrepancies between the master model and the produced model. analysis of variance (ANOVA) according to Kruskal–Wallis was used. The Mann–Whitney U-test was applied for paired group comparisons (P=0.05). The results revealed that a significant difference between the groups related to three-dimensional discrepancies (P=0.003), with higher discrepancy related to indirect snap-on technique with polyether (0.072 ±0.062) mm. The best results was with direct splinted technique with polyvinyl siloxane (0.032 ±0.020) mm and the indirect snap-on technique with polyvinyl siloxane showed a mean of 0.031(±0.042) mm. polyvinyl siloxane showed better accuracy than polyether where a significant differences in 3D and Z axis were found (P=0.002, P=0.000). we concluded that Implant angulation affected the impression accuracy, and a better result could be reached with polyvinyl siloxane material regardless of the technique. Key words: angulated implant, impression accuracy, polyvinyl siloxane, polyether, indirect snap-on technique