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Computer-aided design and computer-aided manufacturing (CAD-CAM) technology has revolutionized workflow in dentistry because of its speed, convenience, and accuracy. [1][2][3][4] Accuracy of definitive restoration fabricated in a fully digital workflow is a crucial factor determining clinical success. 5 When the restoration fails to seat properly in the cavity, more time needs to be spent for the necessary adjustments. If the spacer parameters are set at a high value during the CAD procedure to allow ease of seating, large internal and marginal gaps occur between the tooth and restoration. Poor adaptation jeopardizes longevity in indirect restorations, [6][7][8][9][10][11] as large discrepancies may lead to clinical complications such as secondary caries or periodontal inflammation due to plaque accumulation. 12,13 The accuracy of intraoral scanners (IOSs) has been described, according to the definition 5725-1 of the International Organization for Standardization 14 by using the following terms: trueness, referring to the closeness of agreement between the arithmetic mean of a large number of test results and the true or accepted reference value and precision, referringThis study was supported by the Yonsei University College of Dentistry (6-2017-0015).

PURPOSEArticulation paper mark size is widely accepted as an indicator of forceful tooth contacts. However, mark size is indicative of contact location and surface area only, and does not quantify occlusal force. The purpose of this study is to determine if a relationship exists between the size of paper marks and the percentage of force applied to the same tooth.MATERIALS AND METHODSThirty dentate female subjects intercuspated into articulation paper strips to mark occlusal contacts on their maxillary posterior teeth, followed by taking photographs. Then each subject made a multi-bite digital occlusal force percentage recording. The surface area of the largest and darkest articulation paper mark (n = 240 marks) in each quadrant (n = 60 quadrants) was calculated in photographic pixels, and compared with the force percentage present on the same tooth.RESULTSRegression analysis shows a bi-variant fit of force % on tooth (P<.05). The correlation coefficient between the mark area and the percentage of force indicated a low positive correlation. The coefficient of determination showed a low causative relationship between mark area and force (r2 = 0.067). The largest paper mark in each quadrant was matched with the most forceful tooth in that same quadrant only 38.3% of time. Only 6 2/3% of mark surface area could be explained by applied occlusal force, while most of the mark area results from other factors unrelated to the applied occlusal force.CONCLUSIONThe findings of this study indicate that size of articulation paper mark is an unreliable indicator of applied occlusal force, to guide treatment occlusal adjustments.

Purpose: This study aimed to evaluate the influence of tooth location and inlay cavity type on the accuracy of intraoral digital impressions. Methods: Class II inlay preparation was performed on anatomical models of the maxillary first molar (16) and mandibular first molar (46). Mesioocclusal and disto-occlusal cavities were prepared, such that the axial wall of the proximal box measured 1 mm or 2 mm in height. Thus, four types of inlay cavities were prepared in 16 and 46, respectively. Ten digital impressions of each cavity were obtained using Cerec Primescan (Sirona). Reference scans were obtained with a laboratory scanner (E3, 3Shape). All scan data were exported for comparative analysis of the three-dimensional models. Mean absolute deviation values were calculated to evaluate the trueness and precision of the digital models. Color-coded maps were used for the qualitative analysis of deviations. Results: The overall results showed that the trueness for 16 (10.43 ± 0.39 μm) was higher than that for 46 (12.42 ± 0.59 μm) (p < 0.05), while the precision was similar between 16 (3.08 ± 0.92 μm) and 46 (3.08 ± 0.76 μm). The cavity type affected the accuracy of the digital impressions. The highest deviation was observed in positive directions at the margins of the proximal boxes regardless of the cavity type. Conclusions: Tooth location and cavity type affected the accuracy of intraoral digital impressions. Positive deviations were observed at the margins of the proximal boxes.