Aim: Transferring an accurate copy of the patient's soft and hard tissue to the dental laboratory is of essential importance. Various methods of implant impression have different outcomes on dimensions of final cast. This study aimed to compare two methods of implant impression on abutment level with and without impression coping on two parallel implants.
Materials and methods: In this experimental study, a resin model with two holes for fixing the implant was made. The first and second implants had a 4 and 11 mm distance to canine respectively. In this study two methods were used for impression: first was direct (without impression coping) and second was indirect (with the impression coping). Ten impressions were prepared for a total of 10 stone casts. For analyzing the abutment analogs positions, each cast was analyzed using a cruicial malformation and malarticulatoin (CMM) in three dimensions (X, Y, and Z). The difference in dimensions of final casts and laboratory models were analyzed using Independent t-test.
Results: The results did not show a significant difference between direct and indirect methods in Z and Y axis in absolute transmission (Δr). The dimensional changes in the X-axis in the direct method was 0.647 ± 0.155 which is 0.067 ± 0.146 more than the indirect method. A significant difference (p = 0.044) was observed between the two methods in X-axis.
Conclusion: Based on the results, this research found the indirect impression on abutment surface to be more accurate than the direct one. In general, two methods were not significantly different, and dentists can use the simple method of the direct impression for making implant prosthetics.
Clinical significance: Reconstruction of implant's accurate position in the process of impression, along with a tension-free insertion, is the first step in having an accurate prosthesis. Abutment level impression with the impression coping is slightly more accurate than the one without impression coping.
Keywords: Dental abutments; Dental implants; Dental impression techniques Prosthodontics..