To evaluate and compare the accuracy of definitive casts using various splinting methods on implant level impressions in All-on-Four treatment: An in vitro study

Aim: The aim of this study is to evaluate and compare the accuracy of master casts obtained by different splinting techniques for implant level impressions in All-on-Four implant treatment protocol using a coordinate measuring machine. Settings and Design: The study design involves an in vitro study. Materials and Methods: In this in vitro study, a reference clear acrylic resin (AR) model comprising four regular platform implant 3.6 mm x 10.0 mm (Dentium Implant India Pvt. Ltd, Bengaluru, India) which was placed following the All-on-Four implant protocol is prepared. Impressions were categorized into three different groups: Group 1 - impression copings were nonsplinted; Group 2 - impression copings were splinted using AR sectioned 17 min after setting and rewelded with the same resin; and Group 3 - impression copings were splinted by titanium bar using an intraoral welder. A total of 33 (n = 11 in each group) impressions were made to evaluate three different splinting techniques. Impressions were poured with Type 4 dental stone. A coordinate measuring machine was used to record the x, y, and z co-ordinates and angular displacement. The measurements were compared with those obtained from the reference model. Statistical Analysis Used: One-way ANOVA test was used as a test of significance. Results: There was less linear and rotational displacement for the metal-splinted group (P < 0.001) In the x-axis, nonsplinted group showed a statistically significant difference in straight implants (2 and 3 implants) (P = 0.001) of All-on-Four treatment protocol. Conclusion: The splinting methods have a direct effect on the accuracy of definitive casts. The metal-splinted direct technique produced the most accurate casts followed by AR-splinted direct technique and nonsplinted direct technique.