Effect of Scanbody Material and Mucosa Modification Technique on The Accuracy of Digital Impressions of Edentulous Arches with Multiple Implants

Aim: The aim of current research is to evaluate the effect of scanbody material and additional reference markers in the form of artificial landmarks on the accuracy of digital impressions of edentulous arches with multiple implants. Material and Methods: A model of an edentulous maxilla with six implants (BLT, RC, Institut Straumann, AG) was used as master model. PEEK and PMMA scanbodies were screwed on the implants and digital impressions were obtained with an intraoral scanner (TRIOS4, 3Shape). Reference markers made of flowable composite (C), gingival barrier material (GB), scannable silicone (S) were placed on the edentulous spaces and impressions were obtained. The master model was digitalized with an extraoral high-resolution reference scanner. Deviations of the predetermined points and inter-implant distances were calculated by using superimpositining technique. Results: Inter-implant distance measurements showed that PEEK scanbodies demonstrated better precision than PMMA scanbodies, (p<.001). In the subgroups, also PEEK groups were more accurate than PMMA groups (p<.001). Kruskal-Wallis test also showed statistical difference in deviations of the predetermined points among the groups in precision (p<.001). Addition of markers did not influence the precision and trueness in PEEK groups but in PMMA groups both in distance measurements and predetermined point deviations. Conclusion: Addition of reference markers does not make any significance in the accuracy of digital impressions when PEEK scanbodies are used. PMMA seems not to be an alternative material as scanbody material, addition of markers is needed.