Reliability of digital repeated-scan superimposition and single-scan techniques for wear volume loss assessment on flat surfaces.

OBJECTIVES: Evidence on the reliability of digital techniques for wear volume assessment using three-dimensional (3D) scan datasets is scarce. This study evaluated the reliability of a repeated-scan superimposition technique and two single-scan techniques in assessing wear volume loss on flat surfaces of 3D-printed resin specimens. METHODS: Cuboid-shaped (15×10×10 mm) resin specimens were 3D-printed (n = 14) and scanned before and after 200,000 cycles of masticatory simulation. For the repeated-scan superimposition technique, digital 3D models of specimens before and after masticatory simulation were superimposed, and the volume loss was determined. The first single-scan technique utilized a computer-aided design freeware program, while the second one employed a 3D-metrology software program. In the freeware program, the worn area of 3D objects was edited directly to obtain a flat surface. In the 3D-metrology software program, the worn area was deleted first and then filled to the flat surface. The volume differences before and after editing were calculated in each software program. Agreement between the three measurement techniques was determined through intraclass correlation coefficients (ICCs). One-way analysis of variance was performed to compare the wear volume loss assessed by the three techniques (α = 0.05). RESULTS: High inter-technique reliability was observed between the three assessment techniques (ICC = 0.998, p < .001). On pair-wise comparisons of two of the three techniques, all pairs showed high consistency (ICC ≥ 0.999, p < .001). No significant difference was found in the wear volume loss assessed using the three techniques (p = .996). CONCLUSIONS: Digital repeated-scan superimposition and two single-scan techniques demonstrated high reliability in assessing wear volume loss on flat surfaces. CLINICAL SIGNIFICANCE: The repeated-scan superimposition technique can be effectively utilized to assess wear volume loss of anatomically shaped specimens and flat surfaces. This study indicates that the single-scan techniques may serve as a suitable alternative to the repeated-scan superimposition technique when evaluating wear volume loss of flat surfaces.

Comparison of digital and conventional assessment methods for a single tooth preparation and educational satisfaction.

INTRODUCTION: Digital feedback for tooth preparation can provide dental practitioners with more objective and accurate evaluations compared to conventional methods. This study aimed to evaluate the educational effect and satisfaction of digital feedback compared with those of the conventional putty index method for tooth preparation. MATERIAL AND METHODS: Forty-eight third-grade dental students were selected. All students performed a full-coverage preparation on a right mandibular first molar resin tooth. They were randomly divided into four groups (n = 12)-no guide (control), putty index, digital feedback, and digital and putty index assessment. Three-dimensional analysis was performed using an analysis software (GomInspect 2018, Gom) to evaluate the amount of tooth structure removed. At the end of the practice, the students completed a questionnaire to evaluate the educational satisfaction of the respective methods. RESULTS: There was no statistical significance of the amount of preparation amongst groups in most of the measured areas only except for several specific points. Overall occlusal surface showed 0.99 ± 0.27 mm in the N group (no guide) and 1.15 ± 0.31 mm in the D group (digital feedback), and overall axial surface showed no statistical differences (p > .05). The groups that used digital assessment showed a high level of satisfaction compared with conventional assessment. CONCLUSIONS: It was difficult to confirm that the digital-based feedback promotes accurate tooth preparation compared to conventional feedback within the limitation of this study. However, it improved educational satisfaction and permitted objective evaluation.