Comparative Accuracy of Facial Models Fabricated Using Traditional and 3D Imaging Techniques.

PURPOSE: The purpose of this investigation was to compare the accuracy of facial models fabricated using facial moulage impression methods to the three-dimensional printed (3DP) fabrication methods using soft tissue images obtained from cone beam computed tomography (CBCT) and 3D stereophotogrammetry (3D-SPG) scans. MATERIALS AND METHODS: A reference phantom model was fabricated using a 3D-SPG image of a human control form with ten fiducial markers placed on common anthropometric landmarks. This image was converted into the investigation control phantom model (CPM) using 3DP methods. The CPM was attached to a camera tripod for ease of image capture. Three CBCT and three 3D-SPG images of the CPM were captured. The DICOM and STL files from the three 3dMD and three CBCT were imported to the 3DP, and six testing models were made. Reversible hydrocolloid and dental stone were used to make three facial moulages of the CPM, and the impressions/casts were poured in type IV gypsum dental stone. A coordinate measuring machine (CMM) was used to measure the distances between each of the ten fiducial markers. Each measurement was made using one point as a static reference to the other nine points. The same measuring procedures were accomplished on all specimens. All measurements were compared between specimens and the control. The data were analyzed using ANOVA and Tukey pairwise comparison of the raters, methods, and fiducial markers. RESULTS: The ANOVA multiple comparisons showed significant difference among the three methods (p < 0.05). Further, the interaction of methods versus fiducial markers also showed significant difference (p < 0.05). The CBCT and facial moulage method showed the greatest accuracy. CONCLUSIONS: 3DP models fabricated using 3D-SPG showed statistical difference in comparison to the models fabricated using the traditional method of facial moulage and 3DP models fabricated from CBCT imaging. 3DP models fabricated using 3D-SPG were less accurate than the CPM and models fabricated using facial moulage and CBCT imaging techniques.

Implant placement accuracy when using stereolithographic template as a surgical guide: preliminary results.

PURPOSE: The aim of this study is to evaluate implant placement accuracy using the coordinate measure machine (CMM) and to assess how accurate implant angulations and point of entrance can be transferred when using a stereolithographic surgical template as a guide during implant placement. MATERIAL AND METHODS: Angulations, entrance points of 40 implants placed in 6 edentulous jaws using stereolithographic surgical template were evaluated. The angulations were noted in both mesio-distal and bucco-lingual planes. The central axis of each treatment-planned implant was determined using the CMM by locating 3 points along the hollow channel of the drill guide stainless steel sleeve of the stereolithographic surgical template and the central axis of the actual implant, evaluated postsurgically, were determined. Three points along the guide pins were noted after mounted to the implant fixture analogs on the working cast. The differences between the proposed and actual implant point of entrance and angulations were calculated and the data were analyzed using the paired t test. RESULTS: The mean mesio-distal angle deviation of the actual implant from the planned position was 0.7 +/- 5.02 degrees, and the mean bucco-lingual angle deviation was 0.46 +/- 4.43 degrees. Thirty implants (88%) and 31 implants (91%) recorded a <7 degrees angle deviation for the mesio-distal and bucco-lingual plane angle, respectively. No statistical significant difference was found for the angle deviation. The mean difference of the entrance point was within 0.2 +/- 0.72 mm, 29 implants (85%) were within <1 mm from the intended position. Statistically significant difference was shown for the entrance point deviation. CONCLUSION: When measured using the CMM, the stereolithographic surgical template was sufficiently accurate in transferring the planned implant position to the surgical field relative to the implant angulations and point of entrance. Further clinical studies using a greater number of patients are needed to confirm the results of this study.