Accuracy of intraoral scanning technique for implant supported full-arch screw retained prosthesis

M2RWU ePOSTER BASIC RESEARCH

Background: In recent years, digital workflow in implant dentistry evolved with the advances in CAD data exchange to position implants three dimensionally into STL files. Accordingly, direct digital impression (direct-dI) using an intraoral scanner has become a daily clinical practice for implant supported single crowns and fixed partial dentures. However, knowledge with regards to use of the same technology for edentulous arches is insufficient.

Aim/Hypothesis: To compare positional accuracy of implants recorded with conventional impression (cI) and direct-dI technique in maxilla. It was hypothesized that different CAD data exchange mediums used in direct-dI do not differ from various approaches in cI.

Materials and Methods: Four implants, two straight anterior and two angulated posterior, supporting fixed full-arch screw retained prosthesis in rehabilitation of maxillary edentulism was studied. A solid master model was used in impression making of dental implants with conventional and digital impressions. For cI group, implants were recorded with open- and closed-tray approach using elastomeric impression material, and followed by cast model production with dental stone. For direct-dI group, different scan-posts were digitalized using an intraoral scanner. Digital CAD models with implants were designed using associated CAD data exchange mediums, and 3D printed with additive manufacturing. Implant positions in all study cast- and digital- models were recorded manually and visually in three dimension using co-coordinate measuring maCHINA (CMM) and laser scanning maCHINA (LSM) respectively. Implant positions were compared between impression techniques and within each impression approach as well.

Results: Except for posterior angulated implants recorded with cI and direct-DI, differences for all implant positions in angular measurements with CMM between impression techniques and within impression approach were statistically insignificant. All implant positions in linear measurements displayed statistically insignificant difference. LSM implant angulation data were statistically different for anterior straight implants between cI and direct-dI techniques, and within direct-dI technique for different CAD data exchange mediums. All other measurements presented statistically insignificant differences both between impression techniques and within impression approaches.

Conclusions and Clinical Implications: direct-dI technique using an intraoral scanner in fabrication of full-arch implant supported fixed restoration in maxilla is promising due to similar implant position recordings compared to cI techniques. Furthermore, use of different CAD data exchange mediums may be considered to facilitate digital workflow in implant dentistry. direct-dI technique can be used clinically in recording of implant positions to support full arch one-piece screw retained implant superstructures.

Keywords: intraoral scanner, digitalization, dental implant, impression, edentulism