Purpose: Tooth wear is related to occlusal contact area. The aim of this study was to investigate which behavioural factors associated with tooth wear influenced occlusal contacts.

Methods: Forty-six volunteers (35 men, 11 women, 23 ± 2 years old) participated in this cross-sectional study. Participants answered a questionnaire about daytime and night-time habits (sleep bruxism, sleeping in prone position, habitual continuous tooth contact, resting the chin on the hand, poor daytime body posture, habitually drinking soft drink or isotonic drink, habitually drinking alcohol, and habitually eating hard food). Occlusal contact area (OCA) and occlusal contact points (OCPs) were computed from silicone occlusal registration records at the intercuspal position using an occlusal contact visualizing and analysing device. Occlusal contact was defined as any area with a thickness of ≤ 50 μm on the occlusal registration record.

Results: Smaller OCA and fewer OCPs were found in participants with self-reported sleep bruxism (SB) than in those without SB (27.3 ± 13.8 mm² vs 36.2 ± 13.1 mm², 38.1 ± 9.2 points vs 48.1 ± 12.2 points). Participants who habitually rested their chin on their hand had a smaller OCA than those without this habit (25.7 ± 11.5 mm² vs 37.0 ± 13.9 mm²). Participants with an alcohol drinking habit had a greater OCA than non-drinkers (40.6 ± 15.1 mm² vs 29.1 ± 12.5 mm²). Awareness of prone sleeping, habitual continuous tooth contact (including daytime clenching), poor daytime body posture, habitually drinking soft drinks or isotonic drinks and habitually eating hard food did not influence either OCA or OCP. Binomial logistic regression analysis revealed that for OCA, self-reported SB and resting the chin on the hand were significant negative predictors (β = −0.282, −0.351, respectively), while drinking alcohol was a positive predictor (β = 0.370).

Conclusions: Self-reported SB, resting the chin on the hand, and habitually drinking alcohol influenced OCA. Dental clinicians should inform patients with tooth wear about habits likely to influence OCA.

The aim of this present study was to investigate the reproducibility of surface profile and step height in the dental scanners.

A step height specimen (Step Master SERIES516-499), which has 300, 100, 50, and 20 μm height of 4 steps, constructed with 5 ceramic gauge-blocks (G1-G5). The specimen was scanned with 2 laboratory (D900 and Ceramill map400) and 2 intra-oral scanners (Trios3 and CS3600), each 10 times. To evaluate the reproducibility of surface profile, the scanned data within the region of interest (ROI) on G1 was used, and the parallelism tolerance of the target surface was investigated. To evaluate the reproducibility of step height difference, the cumulative step values with respect to a reference plane that best fitting to the mesh data on G1 were calculated.

The parallelism tolerances of target surface in the laboratory and intra-oral scanners were approximately 10 and 20 μm, respectively. It of the CS3600 was significantly lower than those of other 3 scanners. In the laboratory scanners, all step height could be measured. On the other hand, it was difficult to detect under the step height of 50 μm with the Torios3, and under 100 μm with the CS3600.

Within the limitations of this study, in the scanning processes and 3D-construction, the error in the laboratory scanners was significantly less than intra-oral scanners. The results of this study could provide an insight into the appropriate clinical requirement for each CAD/CAM system.