Analysing the precision of dental impression on angulated implants using full arch and sectional approaches in the abutment and fixture levels

Abstract

Aim and background: The goal of this research is, to study the effect of different dental impression methods in the abutment and fixture levels using the Sectional (SE) and Full Arch (FA) approaches in some implants with internal connectionsas well as different angles of each implant placements on the accuracy of the final casts. Methods and Materials: 4 analogues(implant replicas) were placed on both sides of the imaginary arch (the premolar and the first molar area)in a way that, the opposite side analogues would buccolingually make an angle of 40-60 degreeswhile, each of the analogueswere tilted 10 degreesmesially in their longitudinal axis. The dental impression procedure in both fixture and abutment levels was conducted by the same person using Poly Vinyl Siloxane (PVS). 10 FA and 10 SE dental impressions were taken from each fixture and abutmentlevels. The impressions were castedusingDental Stone Type IV. The center to center distance between the implants (a, b and etc.) along with their angles (θ1, θ2 and etc.) on the initial cast and the duplicated cast were all measured using the Coordinate Measuring Machine (CMM) device in the X-Y-Z axis. The results were analyzed using a statistic software called Statistical Package for the Social Sciences (SPSS 20) based on theT-Test, One-Way ANOVA and Two-Way ANOVA statistical methods. (p<0.05) Results: The results of the Two-Way ANOVA showed a significant difference between the studied groups. (P<0.001) The results of the One-Way ANOVA illustratedchanges of line and angle movements in all positions as (Δa, Δb, Δc, etc.) and (Δθ1, Δθ2, etc.) while, using FA impression in the fixture and the abutment levels showed a significant statistical difference. (P<0.001) The results of the T-Test in the SE approach in two levels of fixture and abutment demonstratedthat, only changes in θ2angle wassignificant, as other changes of (Δf and Δθ1)also showed a significant difference. (P>0.05) Moreover, the SE approach in abutment's level was significantly more precise in accordanceto the fixture level. Conclusion: In angulated implants, it is recommended to make the dental impressionin the abutment level using a sectional approach which, has higher precision.