Photoelasticity for Stress Concentration Analysis in Dentistry and Medicine.

Complex stresses are created or applied as part of medical and dental treatments, which are linked to the achievement of treatment goals and favorable prognosis. Photoelasticity is an optical technique that can help observe and understand biomechanics, which is essential for planning, evaluation and treatment in health professions. The objective of this project was to review the existing information on the use of photoelasticity in medicine and dentistry and determine their purpose, the areas or treatments for which it was used, models used as well as to identify areas of opportunity for the application of the technique and the generation of new models. A literature review was carried out to identify publications in dentistry and medicine in which photoelasticity was used as an experimental method. The databases used were: Sciencedirect, PubMed, Scopus, Ovid, Springer, EBSCO, Wiley, Lilacs, Medigraphic Artemisa and SciELO. Duplicate and incomplete articles were eliminated, obtaining 84 articles published between 2000 and 2019 for analysis. In dentistry, ten subdisciplines were found in which photoelasticity was used; those related to implants for fixed prostheses were the most abundant. In medicine, orthopedic research predominates; and its application is not limited to hard tissues. No reports were found on the use of photoelastic models as a teaching aid in either medicine or dentistry. Photoelasticity has been widely used in the context of research where it has limitations due to the characteristics of the results provided by the technique, there is no evidence of use in the health area to exploit its application in learning biomechanics; on the other hand there is little development in models that faithfully represent the anatomy and characteristics of the different tissues of the human body, which opens the opportunity to take up the qualitative results offered by the technique to transpolate it to an application and clinical learning.

Association of Age and Temperamental Traits with Children's Behaviour during Dental Treatment.

During paediatric dental treatment, cooperation by children is essential, and temperament can determine their behaviour style. This study aimed to associate temperamental traits and age with behaviour during paediatric dental treatment. This was an observational and cross-sectional study of patients aged 3-10 years. To determine the temperamental traits, an Emotionality Activity and Sociability Temperament Survey (EAS) was performed with the children's parents. The type of behaviour was determined with Frankl's criteria. The total scores for temperamental traits, means, and standard deviations were obtained. The chi-squared test, one-way ANOVA and Student's t-test were applied. A total of 140 patients, who were 5 ± 2.1 years old, participated in the study. Age was determinant for negative behaviour, with a greater frequency in children ≤5 years old (p < 0.05), and a significant negative correlation between age and behaviour (rho = -0.245, p = 0.001). Patients with higher emotionality and activity presented negative and definitely negative behaviours more frequently (p < 0.01). The values for sociability and shyness were similar for positive or negative behaviours. In conclusion, the temperamental traits of emotionality and activity were more frequent in children with disruptive behaviours; therefore, conducting a survey on temperamental traits can be useful for planning behavioural approaches in paediatric dentistry.

[Photoelastic models applied to dental restorations]. / Modelos fotoelásticos aplicados a la restauración dental.

Objective: To improve the understanding of the changes generated by restorative procedures through photoelastic models. Dental reconstruction should be based on principles of occlusion in order not to cause premature contact points during preparation and restoration procedures that can lead to disorders such as occlusal trauma, temporo-mandibullary joint dysfunction, or fractures. This paper presents a didactic method to objectively visualize occlusal loads and their distribution. Materials and methods: Photoelastic models of teeth and maxillary segments were made to visualize the effects of dental preparations and restorations, as well as the wear of premature contact points. Results: The direction, intensity and distribution of stresses in the crown and bone support were analyzed by photoelasticity. Conclusions: The technique allows visualization of how the structures are affected from the cavity preparation, the different stresses with diamond or carbide burs, in addition to observing how a premature contact point not only affects the organ that contains it but also the surrounding structures.