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Three Dimensional Osteometric Analysis of Mandibular Symmetry and Morphological Consistency in Cats.

ABSTRACT: Objectives: The aim of this study was to describe a number of anatomical reference points which can be used to measure mandibular morphology and assess the degree of mandibular symmetry in a group of normal cats. Comparisons were then made between cats to evaluate correlations between morphological measurements and degree of inter-cat variation. This will provide data valuable evaluating and developing techniques for caudal mandibular fracture repair. Methods: Twenty-seven mixed breed cats (26 Domestic Shorthaired and 1 Domestic Longhaired) with no history of head trauma, intact undamaged mandibles, both mandibular fourth premolars and first molars present which had a full skull CT scan were included in this study. Anatomical reference points were defined on maximum intensity projections of multiplanar reconstruction of the mandibles and measurements taken. The ratios between paired right and left measurements, and the ratio of jaw widths at the coronoid process and mandibular foramen were calculated. All analyses were performed using R version 3.3.3 and the multcomp library. Results: None of the right:left ratios were detected as being significantly different from 1 and the coefficient of variation values were all very small showing that when cats deviate from the mean ratio they do so by only a small amount. Measurements analyzed to determine how consistent individual measurements were between cats showed that the most consistent measurement was the lateral ramus inclination angle. The least consistent measurements were ramus height and jaw width at the mental foramen. The correlation between pairs of measurements of the right and left ramus was analyzed and demonstrated a strong correlation between the height, width and length of the ramus. Conclusions: This study has demonstrated a low level of asymmetry between contralateral mandibles in cats, a high level of consistency in the dimensions of mandibles between cats and a strong correlation between the height, width and length of the ramus.

SUBMITTER: Southerden P

PROVIDER: S-EPMC6052099 | biostudies-literature |

REPOSITORIES: biostudies-literature

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Project description:ObjectiveThis study aimed to evaluate the condylar positional changes following mandibular reconstruction with preservation of the condylar head using Cone-Beam Computed Tomography (CBCT). Also, to assess joint space changes and the overall volumetric space compared to the preoperative status.MethodologyThis prospective study included 30 patients (60 joints) subjected to unilateral mandibular resection and reconstruction with preservation of the condylar head. The Helkimo index and preoperative (T1), two weeks postoperative (T2), and follow-up CBCTs (T3) after at least six months were gathered and processed to evaluate the condylar position and TMJ joint space using Anatomage Invivo 6. A student's t-test and repeated-measures ANOVA statistics were used. A P value of less than 0.05 was considered statistically significant.ResultsThirty patients (14 males, 16 females) with a mean age of 40.01 ± 12.7 years (a range of 18.1-62.9 years) were included. On the tumor side, there were significant variances in the vertical and mediolateral condylar positions between the three-time points (T1, T2, T3). Immediately after the operation, the condyles were significantly displaced in a downward direction at T2, which became larger after the last follow-up period (T3) (p = 0.007). The condylar positions at the anteroposterior direction were relatively stable without significant differences between the three times points (p = 0.915). On the non-tumor side, the condylar positions were relatively stable in the mediolateral and anteroposterior positions. In the tumor side, all of the TMJ spaces were significantly increased in size following the mandibular reconstructions (T2 and T3). However, on the non-tumor side, the anterior, posterior, and medial joint spaces were significantly changed postoperatively.ConclusionAfter mandibular reconstruction with condylar preservation, the condylar position and volumetric measurement immediately changed noticeably and continued to be a permanent change over time compared to relatively stable condyles on the non-tumor side. According to Helkimo index, patients become adapted to the postoperative changes without significant differences between the two sides.

Project description:IntroductionThe shape and volume of the condyle is considered to play an important role in the pathogenesis of the mandibular deviation. Curvature analysis is informative for objectively assess whether the shape of the condyles matches that of the glenoid fossa. In this study, a three-dimensional (3-D) quantification of bilateral asymmetrical condyles was firstly conducted to identify the specific role of 3-D condylar configuration for mandibular asymmetry.Methods55 adult patients, 26 males (26 ± 5 yrs) and 29 females (26 ± 5 yrs), diagnosed with mandibular asymmetry were included. The examination of deviation of chin point, deviation of dental midlines, inclination of occlusal plane, and depth of the mandibular occlusal plane were conducted. After the clinical investigation, computed tomography images from the patients were used to reconstruct the 3-D mandibular models. Then the condylar volume, surface size, surface curvature and bone mineral density were evaluated independently for each patient on non-deviated and deviated sides of temporomandibular joint.ResultsBoth the condylar surface size and volume were significantly larger on deviated side (surface size: 1666.14 ± 318.3 mm2, volume: 1981.5 ± 418.3 mm3). The anterior slope of the condyle was flatter (0.12 ± 0.06) and the posterior slope (0.39 ± 0.08) was prominently convex on the deviated side. The corresponding bone mineral density values were 523.01 ±118.1 HU and 549.07 ±120. 6 HU on anterior and posterior slopes.ConclusionsThe incongruence presented on the deviated side resulted in a reduction in contact areas and, thus, an increase in contact stresses and changes of bone density. All aforementioned results suggest that the difference existing between deviated and non-deviated condyles correlates with facial asymmetrical development. In mandibular asymmetry patients, the 3-D morphology of condyle on deviated side differ from the non-deviated side, which indicates the association between asymmetrical jaw function and joint remodeling.

Project description:The bones forming the talocrural joint (TCJ) and subtalar joint (STJ) are often assumed to be bilaterally symmetric. Therefore, the contralateral limb (i.e. the fibula, tibia, calcaneus and talus) is used as a template or an intra-subject control in clinical and research practice. However, the validity of the symmetry assumption is controversial, because insufficient information is available on the shape variations and bilateral (a)symmetry of the fibula, tibia, calcaneus and talus. Using three-dimensional spatially dense sampled representations of bone shapes extracted from bilateral computed tomography scans of 66 individuals (55 male, mean age: 61?±?10?years; 11 female, mean age: 53?±?15?years), we analyzed whether: (i) similar shape patterns exist in the left and right bones of the same type; (ii) gender has an effect on bone shape variations; (iii) intra-subject shape variation is smaller than that of inter-subject for a given shape variance direction. For the first set of analyses, all left and right instances of the same type of bone were considered as two separate groups, and statistically compared with each other on multiple aspects including group location (central tendency), variance-covariance scale (dispersion) and orientation (covariance structure) using distance-based permutational tests. For the second and third sets of analyses, all left and right bones of the same type were pooled into one group, and shape variations in the TCJ and STJ bones were extracted using principal component analysis. The effects of gender on age-adjusted bone shape differences were assessed using an analysis of covariance. Moreover, intra-class correlation was employed to evaluate intra- and inter-subject bone shape variations. For each bone type, both sides had similar shape patterns (Ppermutational -values?>?0.05). After Bonferroni adjustment, gender led to shape differences, which were mainly in the lateral and medial condyles of the tibia (P?=?0.003), the length and height of the calcaneus (P?<?0.001), the posterior and anterior talar articular surfaces of the calcaneus (P?=?0.001), and in the posterior aspect of the talus (P?=?0.001). Intra-subject shape variations in the tibial tuberosity together with the diameter of the tibia, and the curvature of the fibula shaft and the diameter of the fibula were as high as those of inter-subject. This result suggests that the shape symmetry assumption could be violated for some specific shape variations in the fibula and tibia.

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Three Dimensional Osteometric Analysis of Mandibular Symmetry and Morphological Consistency in Cats.

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