Assessment of Effect of Implant Angulation and Implant Number on the Dimensional Accuracy of Definitive Casts.

AIM: To analyze the impact of implant angulation and implant number on the dimensional accuracy of definitive casts. MATERIALS AND METHODS: Seven definitive casts with implant analogs placed in a triangular pattern were made from dental stone. The groups were as follows: group 1 (control group) all implant analogs perpendicular to the plane of the cast; the center implant analog (implant 2) being at 90 degrees to the plane of the cast in all groups and implant analogs number 1 and 3 arranged in 5 degrees , 10 degrees , or 15 degrees divergence from or convergence to the center implant (implant number 2). Three open-tray impressions of definitive casts were made in each group. Impressions were poured in type IV dental stone. Coordinates in the three planes were measured at the implant analog top surface and the base of the cast using a fine tip measuring stylus. The data were aligned and the angular differences between implant analog vectors from definitive and duplicate casts were calculated in degrees. RESULTS: The impact of implant number on the dimensional accuracy of definitive casts was significant whereas for implant angulation it was nonsignificant. The correlation of angulation and the number of the implant did not show an interpretable pattern. The precision of duplicate casts (compared to definitive casts) is not affected by the combined interaction of implant number and implant angulation. CONCLUSION: The close proximity of implant angulation toward a right-angled direction results in higher precision of implant. In the impression, there is direct picking from the impression copings which decreases the discrepancies in implant angulation on impression and master cast. The interaction of implant angulation and the number shows a noninterpretable pattern. CLINICAL SIGNIFICANCE: Dimensionally accurate implant impressions can be made by using an open tray technique for three implants angled up to 15 degrees .