Posterior Mandibular Displacement. A Systematic Review Based on Animal Studies

Treating extreme mandibular growth is challenging. The mandible is pushed backwards to address itsprotrusion. Nevertheless, conclusions after such displacement in animals have been contradictory. The aim of the present review is to present measurable alterations of the mandible and the condyle following retractionin healthy rats or rabbits. PubMed, Scopus and Web of Science were accessed for relevant studies up to October 2020. Eligibility was determined by the PICOS process, while the risk of bias was estimated with SYRCLE’s risk of bias tool. Retraction resulted in a more distal molar occlusion and the condyle rested more posteriorly. Mandibular anteroposterior bilateral growth restriction was achieved, the condylar process measured smaller and its angulation increased. The condylar neck thickened, its posterior surface flattened, the coronoid process was measured longer, and enlarged retromolar density was registered. Differences in the ramus height and the intercondylar distance were insignificant. Changes persisted for the period of study and subsequently the mandible resumed its inherited growth pattern. The timing of mandibular shaping and TMJ outcomes might depend on the properties of the applied force. Stability is of concern and well-structured, long-term studies are expected to resolve the issue and further clarify the results of posterior mandibular displacement.

Morphology and morphometric study of occipital condyles

Introduction: The occipital condyles are undersurface protruberances of the occipital bone in vertebrates, which articulate with the superior facets of the atlas vertebra. The condyles are oval or reniform in shape, and their anterior extremities directed forward and medially and are closer together than the posterior end. Aim: The aim of the study is to provide important anatomical parameters for lateral transcondylar approach. Materials and Methods: 200 occipital condyles in 100 dry human skulls ( 73 males and 27 females) were studied. The measured parameters included length, width, height, shape, anterior and posterior intercondylar distance, distance between basion and opesthion, distance from anterior tip of the condyle to the basion and opestion and distance from posterior tip to the basion and opesthion. Measurements were made using Vernier Callipers. Results: The mean length, width and height of the occipital condyles in males is greater than females. The anterior intercondylar distance is more in females whereas posterior intercondylar distance is more in males. The mean distance from basion to opesthion / anteroposteriordiamerer of foramen magnum is more in males than in females. The mean distance between the anterior tip of occipital condyles to basion is more in females than in males on both the sides. Conclusion: The knowledge of condylar anatomy helps the surgeon in making important decisions regarding extent and direction of condylar drilling and minimizing injury and retraction of neural structures. KEY WORDS: Occipital Condyles, Foramen Magnum, Intercondylar distance, Basion, Opesthion.

Morphometric evaluations of intercondylar distances using computed tomographic scan images in Maiduguri, northeastern Nigeria

Knowledge of the anatomy of the occipital condyle (OC) and the structures around it is significant in sex determination and in surgical operations involving the basicranium. The present study attempts to evaluate the anterior occipital intercondylar distance (AOID) and posterior occipital intercondylar distance (POID) in the sample population as well as its variability in different populations. The sample population for the present study comprised of computed tomographic (CT) images of 110 patients (60 males and 50 females) aged 18–65 years obtained from the Federal Neuropsychiatric Hospital, Maiduguri, Borno State-Nigeria. Males presented significantly higher mean values for both the parameters measured (p<0.001). Mean values of AOID in males and females are respectively 24.15 mm and 22.31 mm, while the POID mean values are 26.83 mm and 23.79 mm. The ratio of POID to AOID is 1.1:1.0 in both males and females in the sample. This ratio varies from population to population.

The Relationship Between Football Participation Level and Lower Leg Alignment in Youth Males: Genu Varum

The aim of this study was to determine the effects of football participation levels on genu varum ratings by using Q angle and intercondylar distance. Twenty male football players for each elite and amateur football teams and 20 sedentary young male volunteers participated in this study. The anthropometric variables (body height, body weight, body fat percentage, body mass index) and genu varum levels by evaluating the lower extremity alignment using intercondylar distance, and Q angles for both legs were measured. The intercondylar distance measurements were done by using caliper with the sensitivity of 0.01 mm and Q angle measurements were carried out by the examination of the photographs of participants. One Way ANOVA and post-hoc Tukey test were used to assess statistically intra-group differences. Cohen's Kappa coefficient were used to determine agreement among observers. SPSS v.25 program was used to analyse the data. Intercondylar distance values were found significantly higher in elite group than in amateur and sedentary groups (45.65 ± 13.54; 28.84 ± 14.61; 3.70 ± 5.19 mm, respectively, p<0.001). As a result of this study, it was determined that the participation level of football trainings lead an increase in intercondylar distance significantly. The highest Q-angle values were observed in amateur football players.

Altered mandibular growth under functional posterior displacement in rats

Objective: To test the null hypothesis that there is no difference in mandibular growth between growing rats with posterior functional mandibular displacement and growing rats without functional mandibular displacement. Materials and Methods: Twenty female Wistar rats (5 weeks old) were randomized into two groups: (1) control and (2) mandible posterior displacement in the occluded condition induced by an occlusal guiding appliance. After 8 weeks all animals were sacrificed, cone beam computed tomography scan images of the heads were taken using the classic I-CAT, and acrylic rapid-prototyped templates of the mandibles were constructed. Mandibular length, ramus height, and intercondylar distance were measured. Mandibular length and ramus height were submitted to the two-way analysis of variance, while intercondylar distance was analyzed by nonpaired Student's t-test. Results: Mandibular length was bigger (P &lt; .0001) in the control than in the experimental group, but no significant difference was found between the left and right sides (P = .9380). No significant differences were observed for ramus height and intercondylar distance. Conclusions: The results of this study demonstrated that functional posterior displacement of the mandible in growing rats resulted in shorter mandibular length.