Facial skeleton asymmetry and its relationship to mastication in the Early Medieval period (Great Moravian Empire, Mikulčice, 9th–10th century)

Association between chewing side preference and MRI characteristics in patients with anterior disc displacement of the temporomandibular joint

OBJECTIVE

To compare the magnetic resonance imaging (MRI) characteristics in the anterior disc displacement (ADD) patients with and without chewing side preference (CSP).

METHODS

The MRI characteristics of the bilateral temporomandibular joint (TMJ) in 111 patients with ADD were retrospectively analysed. Based on the presence of CSP, all subjects were divided into the non-CSP group (NC group, N = 40) and CSP group (C group, N = 71). Based on the preferred chewing side in the C group, the patients were divided into ipsilateral and contralateral sides. The morphology, length, disc-condyle angle, and coordinate position of the disc and condyle of the bilateral TMJ were compared.

RESULTS

MRI examination showed a significant difference between ipsilateral and contralateral joint displacement in patients with CSP (P<0.05). In CSP patients, the disc length of the same side in the ipsilateral side was significantly shorter than the contralateral side (P<0.05). A significant difference in the Y-axis coordinates of the ipsilateral and contralateral discs was also found in patients with CSP (P<0.05). The disc displacement grade, morphology of the articular disc, ipsilateral disc length, and ipsilateral disc-condyle Y-axis distance were positively correlated with CSP (P<0.05).

CONCLUSION

CSP is related to the shape of the articular disc and disc-condyle position in patients with ADD. CSP may aggravate the development of ADD.

The effect of sex and age on facial shape directional asymmetry in adults: A 3D landmarks-based method study

OBJECTIVES

Facial directional asymmetry research, including age-related changes, is crucial for the evaluation of treatment of craniofacial malformations/trauma in orthodontics, facial surgery and forensic sciences. The aim was to describe facial directional asymmetry (DA) in different age categories of adults using 3D methods. According to our hypothesis, facial shape DA (1) depends on sex; (2) differs among age groups; and (3) has wider variability in older age.

MATERIAL AND METHODS

A cross-sectional sample of healthy Czech adults without craniofacial trauma or anomalies consisted of 300 3D facial models (151 females). The age-range in the study was between 20-80 years. The shape asymmetry of 28 3D landmarks was evaluated using geometric morphometrics and multivariate statistics.

RESULTS

The manifestation of DA was similar in both sexes and in each age category; however, there were some statistical differences. In contrast to the ideal symmetrical face, the mean asymmetrical faces tended to create a slightly bent "C" shape of the midline. Therefore, the upper face was rotated slightly clockwise and the lower face counter-clockwise. The right eye was located slightly higher, with the nasal tip and mandibular region tilting to the left. Sex differences in facial DA were significant before the age of 40. DA was more significant in the youngest males than in the oldest, while the women's DA did not change.

CONCLUSIONS

The DA patterns were similar in both sexes and in all age categories (a slightly bent C shape of the midline); however, some significant local differences between male age groups were found. A significantly more pronounced asymmetry compared to other age groups was found only in the youngest males from 20 to 40 years. Moreover, significant sexual dimorphism of DA rapidly decreased after middle age, likely caused by the same age-related changes of the face during aging.

Breaking Symmetry: A Quantitative Analysis of Facial Skeleton Disharmony in Children Born with Bilateral Cleft Lip and Palate

Bilateral cleft lip and palate (BCLP) occurs when craniofacial precursors fail to form or fuse properly during development. The aim of this retrospective, cross-sectional investigation was to quantify directional asymmetry (DA) of the facial skeleton of children born with Veau Class IV nonsyndromic BCLP. To accomplish this goal, coordinate values of anatomical landmarks were acquired from three-dimensional cone beam computed tomographic images of the craniofacial skeleton of middle- to late-aged children born with BCLP and age- and sex-matched controls and used to compare patterns of asymmetry variation. Multivariate analyses revealed different patterns of DA variation across samples and identified approximately 30% of DA measures as significantly different. Magnitudes of statistically significant linear distances differ in the craniofacial region, with most smaller DA differences located near the orbits and frontal bone, while larger differences were localized mostly to the midface, alveolar ridge, and nasal borders. Generally, areas of the craniofacial skeleton derived from the maxillary and nasal prominences demonstrated the highest magnitudes of DA. The methods and results presented will be useful to biomedical researchers when identifying the extent to which patients with BCLP diverge from typical developmental expectations. Quantifying DA and assessing local differences across the craniofacial complex can aid medical practitioners when developing treatments to improve BCLP surgical algorithms and outcomes. Anat Rec, 302:1726-1732, 2019. © 2019 American Association for Anatomy.

Three-dimensional geometry of human tibial anterior curvature in chronologically distinct population samples of Central Europeans (2900 BC - 21st century AD)

Several lines of bioarchaeological research have confirmed the gradual decline in lower limb loading among past human populations, beginning with the transition to agriculture. The goal of this study was to assess whether human tibial curvature reflects this decline, with a special emphasis on the time-span during which the pace of technological change has been the most rapid. Our study is the first (1) to apply longitudinal curvature analysis in the antero-posterior (A–P) and medio-lateral (M–L) planes to the human tibia, and (2) that incorporates a broad temporal population sample including the periods of intensification of agriculture, urbanization and industrialization (from 2900 BC to the 21^st century AD; N = 435) within Czech territories. Using three-dimensional geometric morphometrics, we investigated whether anterior tibial curvature mirrors assumed diminishing lower limb loading between prehistoric and industrialized societies and explored its shape in all three dimensions. Results showed the continuous trend of A–P straightening of the shaft. This straightening was associated with a relative sigmoidal curve accentuation in the M-L plane. Given the timescale involved and the known phenomenon of declining mobility, such adaptive changes in bone geometry can be interpreted in terms of the diminishing biomechanical demands on the tibia under different living conditions.

Three-dimensional geometry of human tibial anterior curvature in chronologically distinct population samples of Central Europeans (2900 BC - 21st century AD)

Several lines of bioarchaeological research have confirmed the gradual decline in lower limb loading among past human populations, beginning with the transition to agriculture. The goal of this study was to assess whether human tibial curvature reflects this decline, with a special emphasis on the time-span during which the pace of technological change has been the most rapid. Our study is the first (1) to apply longitudinal curvature analysis in the antero-posterior (A-P) and medio-lateral (M-L) planes to the human tibia, and (2) that incorporates a broad temporal population sample including the periods of intensification of agriculture, urbanization and industrialization (from 2900 BC to the 21^st century AD; N = 435) within Czech territories. Using three-dimensional geometric morphometrics, we investigated whether anterior tibial curvature mirrors assumed diminishing lower limb loading between prehistoric and industrialized societies and explored its shape in all three dimensions. Results showed the continuous trend of A-P straightening of the shaft. This straightening was associated with a relative sigmoidal curve accentuation in the M-L plane. Given the timescale involved and the known phenomenon of declining mobility, such adaptive changes in bone geometry can be interpreted in terms of the diminishing biomechanical demands on the tibia under different living conditions.