EVALUATION OF THE ACCURACY OF ABUTMENT LEVEL IMPRESSION IN “ALL ON FOUR” IMPLANT CASES

Objectives: A lack of parallelism among the implants, and that between the implants and the teeth is a common finding in clinical situations. The aim of the following study was to evaluate the accuracy of abutment level impression in “All On Four” cases.
Materials and methods: Five completely edentulous patients restored with “All On Four” distribution of implants in the lower arch were recruited in this study. Prior to restoration two impressions were made for each case. The first impression utilized a specific abutment level impression (recommended by the manufacturer) and poured into a stone cast; trans-mucosal abutments were then screwed onto the implant analogues. The second impression was in a form of a simple impression of the trans-mucosal abutments, and poured into a stone cast. This group was considered as the control group. Both casts were photographed and using the Digimizer^® Software V. 4.3.1 linear measurements and surface areas were measured on the casts and compared.
Results: Using independent t-test, there was a significant difference between the linear measurements and surface areas measured on the casts produced by both impression techniques, where (P-value < 0.05).
Conclusion: In angulated implant cases (All On Four), the position of abutments on a cast produced by the abutment level impressions used showed statistically significant difference from the original abutments’ position in the patients’ mouth.