Investigation of factors that influence the relationship between mental rotation ability and anatomy learning.

BACKGROUND: Mental rotation is a cognitive process that involves the rotation of a mental representation of an object. This ability is important for medical students in studying anatomy as this subject requires the understanding of positional relations between organs. OBJECTIVES: To find the effect of video learning of anatomy, training, gender, and type of practical exam on mental rotation ability. Also, to find correlation between mental rotation and anatomy scores. METHODS: Two groups were recruited: group A studied practical anatomy online using videos due to the COVID-19 pandemic lockdown; group B studied anatomy labs on-campus on plastic models. Both groups underwent a mental rotation test. Group A took labs on-campus during their second year and this was considered a training course for their mental rotation ability. Both groups, then, took a second mental rotation test. Group A was finally given a practical anatomy exam using plastic models. RESULTS: Males scored higher than females, though not significantly. The intervention course produced no significant change in mental rotation score of group A. Mental rotation score was correlated more with the theoretical anatomy exams than the MCQ-based practical exam, for both groups. For group A, mental rotation was better correlated with the model-based than the MCQ-based practical exam, especially the post-training score. CONCLUSION: For students to take full advantage of their mental rotation ability, not only their practical anatomy sessions but their practical anatomy exams should be on anatomical specimens and not just videos or images.

Is Continuous Eruption Related to Periodontal Changes? A 16-Year Follow-up.

The aims of this study were to 1) determine if continuous eruption occurs in the maxillary teeth, 2) assess the magnitude of the continuous eruption, and 3) evaluate the effects of continuous eruption on the different periodontal parameters by using data from the population-based cohort of the Study of Health in Pomerania (SHIP). The jaw casts of 140 participants from the baseline (SHIP-0) and 16-y follow-up (SHIP-3) were digitized as 3-dimensional models. Robust reference points were set to match the tooth eruption stage at SHIP-0 and SHIP-3. Reference points were set on the occlusal surface of the contralateral premolar and molar teeth, the palatal fossa of an incisor, and the rugae of the hard palate. Reference points were combined to represent 3 virtual occlusal planes. Continuous eruption was measured as the mean height difference between the 3 planes and rugae fix points at SHIP-0 and SHIP-3. Probing depth, clinical attachment levels, gingiva above the cementoenamel junction (gingival height), and number of missing teeth were clinically assessed in the maxilla. Changes in periodontal variables were regressed onto changes in continuous eruption after adjustment for age, sex, number of filled teeth, and education or tooth wear. Continuous tooth eruption >1 mm over the 16 y was found in 4 of 140 adults and averaged to 0.33 mm, equaling 0.021 mm/y. In the total sample, an increase in continuous eruption was significantly associated with decreases in mean gingival height (B = -0.34; 95% CI, -0.65 to -0.03). In a subsample of participants without tooth loss, continuous eruption was negatively associated with PD. This study confirmed that continuous eruption is clearly detectable and may contribute to lower gingival heights in the maxilla.

Influence of Age and Tooth Loss on Masticatory Muscles Characteristics: A Population Based MR Imaging Study.

BACKGROUND: Aging is associated with a decline in masticatory muscles mass and performance. The present study aims to examine the differences in the cross-sectional areas of the masseter, medial and lateral pterygoid muscles in relation to age and the present dental status in a population-based magnetic resonance imaging study. METHODS: This cross sectional study involved 747 subjects aged between 30-89 years (344 male, 403 female) who underwent both a whole body MRI and a full oral examination. The cross-sectional areas of the masseter, medial and lateral pterygoid muscles were measured from MRI images using the software Osirix. Dental and prosthetic status data from the oral examination were classified according to Eichner index. The method of generalized least squares, also called growth curve model, was used to examine the associations between the cross-sectional areas, age and tooth status. RESULTS: The cross-sectional area of the lateral pterygoid muscle decreased substantially with age in women but did not depend on age in men. The medial pterygoid muscle depended on age but an effect modification by gender was uncertain. Masseter muscle was weakly associated with age but strongly associated with the number of teeth in both genders. CONCLUSIONS: Our findings suggest that age has a heterogeneous effect on masticatory muscles. This indicates that age related changes to the masticatory muscles are muscle specific and are not consistent between the different muscles.