Effect of magnification factor by Galilean loupes on working posture of dental students in simulated clinical procedures: associations between direct and observational measurements

Effect of loupe and microscope on dentists' neck and shoulder muscle workload during crown preparation

Although there is consensus among dentists that visual aids not only improve vision but also help improve posture, evidence is scarce. This study aimed to evaluate the effect of visual aids (loupe and microscope) on the muscle workload of dentists during crown preparation on dentiform first molars in each quadrant of a phantom head, considering dentists' muscles, patients' tooth positions and surfaces. Six right-handed dentists from a single tertiary hospital participated. Surface electromyography device recorded the muscle workload of the bilateral upper trapezius, sternocleidomastoid, cervical erector spinae, and anterior deltoid during crown preparation. The results showed significantly lower workload in all examined muscles when using a microscope compared to the naked eye (p < 0.05), whereas the loupe showed reduced workload in some specific muscles. The muscle with the highest workload for all visual aids was the cervical erector spinae, followed by the upper trapezius. When analyzed by tooth surface, while the loupe did not significantly reduce overall workload compared to the naked eye for each surface, the microscope significantly reduced workload for most surfaces (p < 0.05). Therefore, during crown preparation, the workload of the studied muscles can successfully be reduced with the use of a loupe or microscope.

Magnification in preclinical procedures: effect on muscle activity and angular deviations of the neck and trunk

Objectives

This study aimed to assess the effects of different magnification systems on the angular deviations of the neck and trunk and the muscle activities of the upper back and neck during preclinical cavity preparation.

Methods

This was an experimental laboratory study, with the angular deviations from the neutral positions of the neck and trunk and the activities of the bilateral upper back (the descending and ascending trapezius) and neck (sternocleidomastoid) muscles as the dependent variables. The independent variables were the different magnification systems used (Simple, Galilean, and Keplerian loupes, with direct vision as the control) and prepared teeth (teeth 16, 26, 36, and 46). A dental mannequin phantom head with artificial resin teeth was used, and Class I cavity preparations for composite resin were performed on teeth 16, 26, 36, and 46 using a 1012 round diamond bur at low speed. To analyze the angular deviations, the postures adopted during the procedure were recorded using a tripod-mounted camera positioned to provide a lateral view of the operator. A trained researcher measured the angular deviations using the software entitled "Software for Postural Assessment"-SAPO (version 0.69). Bilateral muscle activity was assessed using surface electromyography. Descriptive statistical analysis was performed, and after verifying the assumptions of normality and homoscedasticity, two-way analysis of variance and the Tukey and Games-Howell post-hoc tests were used to compare the data (α=0.05).

Results

The angular deviation from the neutral position of the neck was found to be significantly higher during cavity preparations performed with the naked eye and the Simple loupe, irrespective of the prepared tooth. With regard to tooth location, the angular deviation of the neck was significantly greater during cavity preparation on teeth 16 and 26, and the angular deviation of the trunk was significantly greater during cavity preparation on tooth 26, regardless of the magnification system used. There were significant differences in right sternocleidomastoid muscle activity between the Simple, Galilean, and Keplerian loupes, with activity being the lowest for the Galilean loupe (p = 0.008). There were no significant differences in left sternocleidomastoid muscle activity between the loupes, regardless of the prepared tooth (p = 0.077). The activities of the bilateral descending trapezius and the right ascending trapezius muscles were significantly lower when the Galilean loupe was used (p < 0.010).

Conclusion

These results suggest that the Galilean loupe resulted in lower muscle activity in the neck and back regions and that the Galilean and Keplerian loupes resulted in less angular deviations of the neck and trunk during cavity preparation.

The effect of Galilean magnification loupes on the visual acuity and working distance of dental students

OBJECTIVE

This study aimed to evaluate the visual acuity and working distance of dental students using Galilean loupes at different magnification levels.

METHODS

The participants included 50 undergraduate dentistry students selected from each class in the second to fifth years (N = 200) of São Paulo State University, School of Dentistry, Araraquara. The response variables were (i) the working distance between the operator's eyes and the mouth of the dental phantom head, and (ii) visual acuity. The independent variables were the five levels of the Galilean magnification system (naked eye, Galilean loupe simulator without magnification, and Galilean loupes with 2.5×, 3.0×, or 3.5× magnification) and academic year. Visual acuity was measured using a miniature Snellen eye chart inserted into the Class I cavities of the maxillary molars. After verifying the assumptions of normality and sphericity, a mixed repeated measures analysis was performed (α = 0.05).

RESULTS

Statistical significance was found between the "magnification system" and "academic year" for visual acuity (p < 0.001). For the second-, fourth-, and fifth-year participants, there were no significant differences in visual acuity between the naked eye and different magnifications of the Galilean loupes, which were superior to and significantly different from that of the loupe simulator. For the working distance, statistical significance was observed in the interaction between "magnification system" and "academic year" (p = 0.008). For the third-, fourth-, and fifth-year participants, there was no significant difference in the working distance between the naked eye and different magnifications of the Galilean loupes, which were superior to and significantly different from that of the simulator.

CONCLUSION

It was concluded that the different magnification levels of the Galilean loupes did not influence the visual acuity or distance between the eyes of the operator and the mouth of the dental phantom head in the evaluated students.

Impact of using magnifying dental loupes on clinical performance during tooth preparation: A systematic review

Background

To assess whether using magnification loupes affects tooth preparation working posture performed by undergraduate students and dentistry professionals and whether it influences the quality of the preparation, operator satisfaction and procedure time.

Material and Methods

This review was performed according to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) statement and registered in the International Prospective Register of Systematic Review (CRD42023482377). Electronic searches were conducted in PubMed/Medline, Cochrane Library, Web of Science, and Scopus databases for relevant articles published up to August 2023. Clinical or laboratory studies evaluating cavities or dental preparations performed with and without magnification loupes were considered eligible. The outcomes were operator working posture, dental preparation quality, operator satisfaction, and procedure time. The quality of the studies was evaluated using the JBI Critical Appraisal tools for Quasi-Experimental Studies.

Results

The searches retrieved 1493 articles. Based on the eligibility criteria, 11 laboratory studies were included, where 410 undergraduate and graduate dental students conducted dental preparations in 1851 dental specimens. Of the 11 selected studies, 6 evaluated the working posture, 6 assessed the quality of the dental preparations, 5 reported operator satisfaction, and 2 assessed procedure time. The results showed that magnifying loupes significantly improved operator working posture, but did not influence the quality of tooth preparations. Although satisfaction reports about experiences with magnifying loupes were favorable, no significant difference was found.

Conclusions

Magnification loupes improved operator working posture. However, clinical studies with more scientific evidence are needed for steady conclusions regarding operator satisfaction and procedural time. Key words:Magnification, dental loupes, tooth preparation, cavity preparation, dental education.

Musculoskeletal disorders and work ability among dentists and dental students in Finland

BACKGROUND

Musculoskeletal disorders are leading causes for long sickness absences and early retirement. Dental work is physically strenuous, and many studies have shown a relation between work-related MSDs and dentistry. However, fewer studies have focused on how these conditions affect the work ability of dentists.

OBJECTIVE

This study aimed to reveal the relationship between MSD, work ability and sickness absences in Finnish dentists and dental students.

METHODS

A questionnaire was sent to 1200 dental workers and students. It inquired of age, gender, use of dental loupes, physical exercise, use of health care, and site, length and frequency of musculoskeletal complaints. Work ability was assessed with four parameters: work ability score (WAS), future work ability (FWA), self-estimation of MSD-related work disability, and sickness absence days.

RESULTS

The questionnaire gained 255 responses (response rate 21%). The majority (90%) of the respondents had experienced MSD during the past year but only eleven percent of them had been on sick leave. MSDs correlated significantly with WAS, FWA and MSD-related work disability. Results remained significant even age adjusted. Age was a strong predictor of declined work ability, but gender, physical exercise or dental loupe use did not have a significant impact.

CONCLUSIONS

Despite all the ergonomic advances in modern dentistry, the occurrence of MSD symptoms is still high. MSDs seem to affect dentists' work ability significantly, but amount of sickness absence is relatively low, which may indicate a high level of presenteeism.

Value of including loupes in prosthodontic and endodontic components of dental degrees: a systematic review

Background It is crucial dental students graduate with sound knowledge of endodontics and prosthodontics. The use of loupes is important for these due to their intricate nature, but there is currently no standardisation of curricula.Objective This systematic review investigates the value of including loupes in completing dental degrees and their benefits to dental students.Methods Literature was searched from inception to February 2022 in PubMed, Embase and Scopus. Articles included were primary studies of dental students studying endodontics or prosthodontics, which had outcomes related to the value of utilising loupes in learning, clinical application and ergonomics.Results A total of 1,489 articles were retrieved, of which 14 relevant articles were identified. These articles discussed student perceptions and the impact on visual acuity, ergonomic practices and dental procedures. Overall, students perceived that loupes increased self-confidence and allowed a greater operative view but were initially difficult to use. Using loupes resulted in greater visual acuity than no magnification and improved ergonomic practices by reducing neck angulation and improving posture. Students also received better grades when using loupes during cavity access preparation or root canal therapy.Conclusion The use of loupes by dental students can be beneficial if there is initial teaching on their use.

Effect of finger rest positions on upper limb muscle activity during pre-clinical procedures

Objectives

This study aimed to observe the effect of different finger rest positions on the muscular activity of the hand, forearm, arm, shoulder, thorax, and neck, as well as on the angular deviation from the neutral position of the neck, trunk, upper arm, and forearm on the working side during pre-clinical procedures.

Methods

An experimental laboratory study was performed. Response variables were muscle activation of the abductor pollicis, brachioradialis, biceps brachii, deltoid, pectoralis major, and right sternocleidomastoid muscles and angular deviation from the neutral position of the neck, trunk, arm, and forearm during simulated clinical procedures. Independent variable was finger-rest position during cavity preparation (no finger rest, usual rest, and ergonomic rest). Class I cavity preparations (N = 120) were performed on artificial first molars (16, 26, 36, and 46) (N = 120). Muscular activation was assessed by surface electromyography and angular deviations using Software for Postural Assessment (SAPO) version 0.69. One-way analysis of variance and Tukey's or Games-Howell's post-hoc tests were performed (α = 0.05).

Results

For the sternocleidomastoid muscle, there was no statistically significant difference between the different rest positions. For the deltoid muscle, work with no finger rest resulted in greater muscle activation (p < 0.001) during work on tooth 36. Regarding the pectoralis major and right brachioradialis muscles, we observed that for both teeth 16 and 26, working with ergonomic rest showed less muscle activation. Muscle activation of the right biceps brachii was higher for work with no rest in both the upper and lower arches, differing significantly only from the usual rest in tooth 16 (p < 0.001), usual rest and ergonomic rest in teeth 26 and 46 (p < 0.001), and only ergonomic rest in tooth 36 (p = 0.044). In the right abductor pollicis muscle, work with ergonomic rest resulted in less muscle activation for cavity preparation in teeth 16, 26, and 36, which was significantly different from work with no rest (p = 0.029, p < 0.001, and p = 0.013, respectively). Regarding angular deviation, it was observed that for tooth 16, there was a greater angular deviation of the arm when performing cavity preparations with no finger rest. For teeth 26 and 46, the ergonomic finger rest provided lower angular deviation from the neutral position of the right arm. For tooth 36, ergonomic rest provided less angular deviation from the neutral neck position.

Conclusion

In general, the use of non-active finger rest during simulated cavity preparations, regardless of the type of rest, provided less muscle activation and angular deviation from the neutral position of the body's upper extremity when performing pre-clinical procedures.

Transition between preclinical and clinical training: Perception of dental students regarding the adoption of ergonomic principles

OBJECTIVE

This study aimed to evaluate the perceptions of third-year dental students regarding the application of ergonomic principles in the transition between preclinical and clinical training in Restorative Dentistry.

METHODS

We conducted a qualitative observational cross-sectional study. The sample consisted of forty-six third-year dental students at São Paulo State University (Unesp), School of Dentistry, Araraquara. Data was collected using an individual interview recorded on a digital voice recorder. A script containing questions related to the process of adaptation of students to clinical care with a view to ergonomic work posture was used. Data analysis was based on the quali-quantitative technique of Discourse of the Collective Subject (DCS), using Qualiquantisoft®.

RESULTS

Most students (97.80%) perceived the need for an adaptation period in the transition from the preclinic to the clinic regarding ergonomic posture requirements; a part of them (45.65%) claimed that they still could not adapt, primarily due to the difference between the laboratory and clinic in the workstation (50.00%). Some students suggested longer preclinical training in a clinical environment to facilitate this transition (21.74%). The dental stool (32.60%) and the dental chair (21.74%) were the external factors that contributed most to making this transition difficult. The difficulty of the restorative dentistry procedure (10.87%) also interfered with posture. Additionally, the most challenging ergonomic posture requirements in the transition period were maintaining 30 to 40 cm between the patient's mouth and operator's eyes (45.65%), positioning the patient in the dental chair correctly (15.22%), and working with the elbows close to the body (15.22%).

CONCLUSION

Most students perceived the need for an adaptation period in the preclinical transition to the clinic, attributing difficulties to adopt the ergonomic posture requirements, to use the workstation and to perform the procedures on real patients.