[EP-9] Usefulness of intraoral scanners for abutment cavities- Effect of depth of field and post geometry -
[Abstract]
[Objective]
Recent technological improvements in intraoral scanners (hereafter referred to as IOS) have led to the development of IOS with improved depth-of-field performance. As a result, they are expected to be clinically applicable to post areas and deep medial cavities, which were previously considered difficult to scan in prosthodontics. However, the factors influencing the accuracy of optical impression taking are still unclear. Therefore, the aim of this study was to verify the feasibility of the clinical application of intraoral scanners to abutment cavities.
[Method]
First, abutment cavities scanned with two different IOSs with different scan measurement depths were compared. A maxillary model first molar was used as the reference model. A 6 mm deep post section was formed in the palatal root using a root canal formation bar. The height diameter of the remaining wall of the crown was determined under three conditions. All measurement data were converted to STL data and imported onto 3D measurement software. The perpendicular line from the reference plane connecting the reference spheres to the post tip was measured as the scan measurement depth. The results suggest that scanning to the post tip is possible with Primescan, which has a deep scanning depth, regardless of the diameter of the residual wall height, and can be applied clinically. Next, the effect of different post geometries on the accuracy of optical impressions in abutment cavities was investigated using the Primescan. Six conditions of abutment teeth with post sections of different long and wide diameters were fabricated in the palatal root. All measurement data were converted to STL data and the deviation between the master data and the IOS scan data was measured at five measurement points set on the post.
[Results and Discussion]
When the post length diameter was 6 mm, no significant difference in scan deviation was observed between different post width diameters, but when the post length diameter was 8 mm, the scan deviation decreased as the post width diameter increased. This suggests that the shape of the post of the abutment cavity influences the accuracy of optical impression taking.
[Objective]
Recent technological improvements in intraoral scanners (hereafter referred to as IOS) have led to the development of IOS with improved depth-of-field performance. As a result, they are expected to be clinically applicable to post areas and deep medial cavities, which were previously considered difficult to scan in prosthodontics. However, the factors influencing the accuracy of optical impression taking are still unclear. Therefore, the aim of this study was to verify the feasibility of the clinical application of intraoral scanners to abutment cavities.
[Method]
First, abutment cavities scanned with two different IOSs with different scan measurement depths were compared. A maxillary model first molar was used as the reference model. A 6 mm deep post section was formed in the palatal root using a root canal formation bar. The height diameter of the remaining wall of the crown was determined under three conditions. All measurement data were converted to STL data and imported onto 3D measurement software. The perpendicular line from the reference plane connecting the reference spheres to the post tip was measured as the scan measurement depth. The results suggest that scanning to the post tip is possible with Primescan, which has a deep scanning depth, regardless of the diameter of the residual wall height, and can be applied clinically. Next, the effect of different post geometries on the accuracy of optical impressions in abutment cavities was investigated using the Primescan. Six conditions of abutment teeth with post sections of different long and wide diameters were fabricated in the palatal root. All measurement data were converted to STL data and the deviation between the master data and the IOS scan data was measured at five measurement points set on the post.
[Results and Discussion]
When the post length diameter was 6 mm, no significant difference in scan deviation was observed between different post width diameters, but when the post length diameter was 8 mm, the scan deviation decreased as the post width diameter increased. This suggests that the shape of the post of the abutment cavity influences the accuracy of optical impression taking.