Vibration Exposure and Transmissibility on Dentist's Anatomy: A Study of Micro Motors and Air-Turbines

Musculoskeletal disorders among dental students: a survey from Saudi Arabia

BACKGROUND

Work-related musculoskeletal disorders (WMSD) are injuries affecting bones, joints, muscles, and tendons due to improper working conditions with serious consequences on health and career. Dentists were found to be at greater risk of developing WMSD compared to other healthcare providers. This study aimed to investigate the prevalence and risk factors of WMSD among dental students in Saudi Arabia.

METHODS

This cross-sectional survey-based study recruited dental students across the kingdom using respondent-driven sampling technique. Data was collected using the Nordic Musculoskeletal scale and a validated, self- administered, close-ended questionnaire which assessed WMSDs predisposing factors, enabling factors and musculoskeletal disorders consequences and management. The questionnaire was administered in both Arabic and English languages and was distributed online using google forms. Data analysis was performed using SPSS, Chi-square test or Fisher Exact test was used where appropriate and Multivariate Logistic regression analysis was performed to identify predictors of developing WMSDs.

RESULTS

The prevalence of WMSD was 87% (95% CL; 83.9% to 90.3%) among the 462 respondents. Gender, study year, type of practice, having clinics for left-handed, hours of clinical practice, sitting in the proper position while working, use of coping strategies were significantly associated with WMSD prevalence (P < 0.05). Males were OR = 10 times at higher risk of WMSD compared to females (P = 0.0001). Those with daily clinical practice were OR = 5 times at higher risk of WMSD than those who have weekly practice. Those practicing walking, workout, and yoga showed lower prevalence of WMSD (OR = 0.377 & 0.323, p = 0.015, 0.010 respectively).

CONCLUSIONS

The prevalence of WMSD among dental students in KSA was high. Males and those with prolonged clinical sessions were at greater risk of WMSD. There is a need for awareness campaigns to educate dental students about risk factors of WMSD. Collegesy, dental colleges should adopt policies in reducing WMSD among their students.

Evaluation of Vision-Based Hand Tool Tracking Methods for Quality Assessment and Training in Human-Centered Industry 4.0

Smart industrial workstations for the training and evaluation of workers are an innovative approach to face the problems of manufacturing quality assessment and fast training. However, such products do not implement algorithms that are able to accurately track the pose of a hand tool that might also be partially occluded by the operator’s hands. In the best case, the already proposed systems roughly track the position of the operator’s hand center assuming that a certain task has been performed if the hand center position is close enough to a specified area. The problem of the pose estimation of 3D objects, including the hand tool, is an open and debated problem. The methods that lead to high accuracies are time consuming and require a 3D model of the object to detect, which is why they cannot be adopted for a real-time training system. The rise in deep learning has stimulated the search for better-performing vision-based solutions. Nevertheless, the problem of hand tool pose estimation for assembly and training procedures appears to not have been extensively investigated. In this study, four different vision-based methods based, respectively, on ArUco markers, OpenPose, Azure Kinect Body Tracking and the YOLO network have been proposed in order to estimate the position of a specific point of interest of the tool that has to be tracked in real-time during an assembly or maintenance procedure. The proposed approaches have been tested on a real scenario with four users handling a power drill simulating three different conditions during an assembly procedure. The performance of the methods has been evaluated and compared with the HTC Vive tracking system as a benchmark. Then, the advantages and drawbacks in terms of the accuracy and invasiveness of the method have been discussed. The authors can state that OpenPose is the most robust proposal arising from the study. The authors will investigate the OpenPose performance in more depth in further studies. The framework appears to be very interesting regarding its integration into a smart workstation for quality assessment and training.

Effect of mass variation on vibration properties of the tooth in drilling operation

Dental cavity represent one of the widespread illness of the tooth. Method for treating of the tooth is to drill the cavity and to fill the hole with suitable material. Measurements show that during drilling the tooth vibrates with increasing mass that causes unpleasant feeling for patient. The aim of the paper is to give the theoretical explanation for this phenomena and to give suggestion for vibration elimination. During drilling, mass of the tooth is decreasing and the so called ‘reactive force’ occurs. Drilling and reactive force cause tooth vibration. The system is modeled as a nonlinear time variable system. An analytical procedure for solving of the equation of vibration is developed. The solution is assumed in the form of the generalized trigonometric function with time variable amplitude and phase. It is obtained that not only the amplitude but also the frequency of tooth vibration in drilling are increased. In addition to reactive force the drilling velocity, diameter of the drill tool and spindle speed affect the vibration level. The appropriate values of these parameters would eliminate or decrease the patient bad feeling.

A Novel Method for Adjusting the Taper and Adaption of Automatic Tooth Preparations with a High-Power Femtosecond Laser

This study explored the effect of the light-off delay setting in a robotically controlled femtosecond laser on the taper and adaption of resin tooth preparations. Thirty resin teeth (divided into six equal groups) were studied under different light-off delay conditions. Tapers from six vertical sections of the teeth were measured and compared among the light-off delay groups. The mean taper decreased from 39.268° ± 4.530° to 25.393° ± 5.496° as the light-off delay increased (p < 0.05). The average distance between the occlusal surfaces of the scanned data and the predesigned preparation data decreased from 0.089 ± 0.005 to 0.013 ± 0.030 μm as the light-off delay increased (p < 0.05). The light-off delay of the femtosecond laser is correlated with the taper and adaption of automatic tooth preparations; this setting needs to be considered during automatic tooth preparation.