Survey on the prevalence of occupational injuries to the head and teeth in automotive repair and maintenance in Switzerland.

Automotive mechanics are exposed to an increased risk for occupational injuries (OI) to the hands, arms, head and teeth. The aim of this study was to assess the self-reported prevalence of OIs to the head, including traumatic dental injuries (TDIs), among automotive repair and maintenance workers dealing with motorcycles, cars and vehicles over 3.5 tons. We surveyed healthy mechanics in Swiss automotive repair workshops from 2019 to 2021. Overall, 121 automotive repair and maintenance workers responded to our 12-item questionnaire concerning their professional experience, protective measures and occupational injuries to the head and teeth (response rate: 12%). 119 were considered eligible for inclusion and two were excluded. Most persons surveyed (94%) were males with more than 10 years of professional experience. Eighty-five (72%) reported occupational injuries in general, 37 (43.5%) specified OIs to the head or tooth area, and 16 stipulated that these cases teeth were affected. The most common self-reported diagnosis was tooth fracture (p=0.191). Traumatic dental injury in childhood increased the odds ratio (OR) for occupational injury to the head or teeth by a factor of 2.4 (95% CI: 1.1, 5.5, p=0.036). Age, gender and dental trauma in childhood may also influence the prevalence of occupational injuries in general in this cohort. We conclude that occupational dental accidents in automotive repair workshops can be reduced by raising awareness of this issue and by taking effective preventive measures.

Photographic assessment of simulated dental luxation injuries.

BACKGROUND/AIM: Dental photographs are a valid means for documentation of dental luxation injuries. The aim of the study was to evaluate the utility of two photographs from different perspectives in the assessment of dental luxation injuries compared to one perspective only. MATERIALS AND METHODS: Photographs of simulated dental luxation injuries were shown to experts in dental traumatology and other dentists who had to estimate the displacement in the vertical and horizontal dimensions. The overall error of estimation as a result of both vertical displacement and horizontal displacement was calculated and statistically analyzed. RESULTS: The mean overall error of estimation was 0.43 mm and 0.75 mm for experts and dentists, respectively. If two (frontal and occlusal) perspectives were available, the overall error was lower than when only one perspective was available (p < .001). Experts had a lower overall error compared to dentists (p < .015). CONCLUSION: Two photographs from two perspectives allowed better interpretation of dental luxation injuries.

Comparing the mechanical properties of pressed, milled, and 3D-printed resins for occlusal devices.

STATEMENT OF PROBLEM: Comparisons of the material qualities of pressed, milled, and 3D-printed occlusal devices are sparse, complicating informed decisions on material choice. PURPOSE: The purpose of this in vitro study was to compare the material properties of pressed, milled, and 3D-printed resins, as well as how these are affected by thermal aging. These data were then used to estimate the likely clinical performance of the tested materials. MATERIAL AND METHODS: Three pressed (ProBase Cold; Ivoclar Vivadent AG, Palapress clear; Kulzer GmbH, Aesthetic Blue clear; Candulor), 3 milled (Temp Premium Flexible Transpa; Zirkonzahn, idodentine PMMA transparent; Unión Dental S.A., Yamahachi PMMA clear; Yamahachi Dental MFG), and three 3D-printed (Freeprint splint; DETAX GmbH, LuxaPrint Ortho Plus; DMG GmbH, Nextdent Ortho Clear; Vertex-Dental B.V.) resin materials were evaluated. Flexural strength, Martens hardness (HM), Vickers hardness (HV), water sorption, water solubility, and surface topography were analyzed. The tests were carried out after 50 hours of water storage at 37 °C (baseline) and after simulated aging (50 hours of water storage at 37 °C, followed by 20 000 thermocycles [TC] at 5 °C and 55 °C). RESULTS: At baseline, the mean flexural strength values were 92.8 to 99.5 MPa for pressed, 95.1 to 122.0 MPa for milled, and 19.5 to 91.3 MPa for 3D-printed materials. After aging, these values were 87.6 to 93.5 MPa for pressed, 93.1 to 116.0 MPa for milled, and 13.0 to 63.3 MPa for 3D-printed resins. The mean HM values were 130.1 to 134.1 N/mm for pressed and 130.3 to 158.5 N/mm for milled resins. After aging, the mean HM ranged from 121.6 to 124.2 N/mm for pressed and 116.2 to 149.7 N/mm for milled resins. The mean HV values were 18.2 to 19.9 for pressed and 18.4 to 23.0 for milled resins before aging and 16.9 to 18.7 for pressed and 17.3 to 22.3 N/mm for milled resins after aging. Printed resins could not be measured. At baseline, the mean modulus of elasticity ranged from 4.6 to 4.8 GPa for pressed and from 4.7 to 5.3 GPa for milled resins. For 3D-printed resins, only 1 material could be measured (3.7 GPa). The mean sorption values were 8.6 to 9.2 µg/mm3 for pressed, 7.9 to 10.5 µg/mm3 for milled, and 9.2 to 21.2 µg/mm3 for additive resins. After aging, these values were 21.1 to 22.6 µg/mm3 for pressed, 20.5 to 23.7 µg/mm3 for milled, and 19.4 to 45.5 µg/mm3 for 3D-printed resins. The mean solubility values ranged from 0.3 to 1.4 µg/mm3 for pressed, 0.4 to 1.7 µg/mm3 for milled, and -3.5 to 11 µg/mm3 for 3D-printed materials. CONCLUSIONS: Pressed and milled resins can be considered equivalent in terms of their material properties. Relative to the pressed and milled resins, the 3D-printed resins had lower flexural strength and hardness values and higher water sorption and solubility.