Condylar and ramus volume in asymmetric and symmetric skeletal class III malocclusion: A cone-beam computed tomography study.

Background/purpose: Among the craniofacial structures, the mandible is the only bony structure with movable joints. Each part (including condyle process, coronoid process, and ramus) of mandible would interaction with the muscles and proceed different osteogenesis progress. The objective of this study was to evaluate the mandibles with symmetric and asymmetric skeletal Class III jaw relations by quantifying differences in the condyle process, coronoid process and ramus on CBCT (Cone-beam computer tomography) images. Our hypothesis was that CBCT would reveal no voluminal differences between deviated and non-deviated mandibular segments in asymmetric skeletal Class III. Materials and methods: CBCT imagines were collected from dental department, KMUH and then divided into symmetric Class III group (Menton deviation < 4mm) and asymmetric Class III group (Menton deviation≧4mm). The mandibular structure would be segmented to ramus, condylar and coronoid process. Each volume was measured. Independent t test was used for comparison between groups, and paired t test was applied for comparison between both segmented parts within each group. Results: Significant differences between deviation and non-deviation sides in the asymmetric group were found in condylar and ramus segments for volumetric quantitative measurements. There has no significant difference in ramus parts between groups. Significant greater condylar volume was found in non-deviation side of asymmetric group. Conclusion: The results demonstrated that in the side with greater mandible growth potential, the condylar and the ramus volume would be greater as well. CBCT is a useful and accurate modality for quantification and evaluation of mandibular asymmetry.

Three-dimensional evaluation of mandibular volume in patients with cleft lip and palate during the deciduous dentition period.

OBJECTIVES: To examine the relationship between mandibular volume and craniofacial morphology in patients with cleft lip and palate using cone beam computed tomography (CBCT) and to compare these findings with control (noncleft) patients undergoing CBCT for other purposes during the deciduous dentition period. MATERIALS AND METHODS: Eighty-four patients were categorized into the unilateral cleft lip and alveolus (UCLA) group (n = 25; mean age, 4.60 ± 0.40 years), unilateral cleft lip and palate (UCLP) group (n = 23; mean age, 4.52 ± 0.39 years), bilateral cleft lip and palate (BCLP) group (n = 22; mean age, 4.54 ± 0.37 years), and control group without cleft (n = 14; mean age, 5.19 ± 0.52 years). Mandibular volume and craniofacial cephalometric measurements were obtained using CBCT. All measurements were assessed by analysis of covariance (ANCOVA) using Bonferroni post hoc pairwise comparison tests. RESULTS: ANCOVA revealed no statistically significant differences in mandibular volume among the groups. SNA° and ANB° were significantly larger in the UCLA and BCLP groups than in the control group. SN-MP° was smallest in the UCLA group. Co-A in the UCLP group was shorter than in the UCLA and BCLP groups. Go-Gn was shortest in the UCLP and BCLP groups compared with the control group. CONCLUSIONS: Three-dimensional evaluation of craniofacial morphology using CBCT can provide valuable information on malocclusion and other dentoskeletal problems among patients with CLP.

3-Dimensional CBCT analysis of mandibular asymmetry in unilateral condylar hyperplasia.

PURPOSE: Three-dimensional quantification of asymmetry in UCH has not been reported yet, but would be useful for diagnosing and evaluating the degree of deformity in this disease. It enables profound decision-making and timing of surgery. Unilateral condylar hyperplasia (UCH) can subjectively be classified in hemimandibular elongation (HE), hemimandibular hyperplasia (HH) and a combination of these two (hybrid form). The main purpose of this study was to quantify mandibular asymmetry in UCH patients with a reliable and reproducible method. Secondly, it was evaluated whether the existing classification can be confirmed. MATERIALS AND METHODS: 37 UCH-patients with progressive mandibular asymmetry, supported by a positive bone scan and/or such clinical progression that condylectomy was performed, were included in this retrospective study. A group of healthy subjects, matched for age and gender, was used as the control group. Cone-beam computed tomography (CBCT) scans were imported in Maxilim® software. Each mandibular half was divided into three skeletal segments (condyle, ramus, and body). Linear and volumetric measurements were calculated for these skeletal units on the affected and unaffected side, for both patients and controls. RESULTS: Significant differences between affected and unaffected sides in the patient group were found in condylar, ramus, and body segments for linear (p < 0.01) as well as for volumetric quantitative measurements (p < 0.0040). A mean linear difference between affected and unaffected sides in the condylar region of the UCH patient group was found of 3.6 mm (sd 2.9) versus 0.2 mm (sd 1.5) in controls. For volumetric measurements there was a mean difference between the left and right condyle of 718 mm3 (sd 638) in the patient group versus 8 mm3 (sd 225) difference in the control group. The condyle was the most affected segment. Differences between sides were significantly larger in the patient group than in the control group (p < 0.001). It was not possible to objectify differences between HE and HH. CONCLUSION: CBCT is a useful and accurate modality for quantification and evaluation of mandibular asymmetry in UCH. It enables objective monitoring. The existing classification in HE and HH could not be confirmed.

Evaluation of mandibular volume classified by vertical skeletal dimensions with cone-beam computed tomography.

OBJECTIVE: To investigate the relationship between anteroposterior and vertical differences in maxillofacial morphology and mandibular volume. MATERIALS AND METHODS: Subjects comprised 213 Japanese adults (84 males and 129 females) who were divided into three groups based on mandibular basal arch (ANB) and Wits, measured in a cephalometric analysis: Class I (-1° ≤ ANB < 4°,-1 mm ≤ Wits < 0 mm), Class II (ANB ≥ 4°, Wits ≥ 0), and Class III (ANB <-1°, Wits <-1 mm). Subjects were also divided into three groups based on the mandibular plane angle (Mp), as follows: hypodivergent (Mp < 23°), normodivergent (Mp  =  23-30°), and hyperdivergent (Mp > 30°) groups. Mandibular volume was measured from cone-beam computed tomographic images that were analyzed using Analyze™ image processing software and compared among the three groups in each classification. RESULTS: No significant differences were noted in mandibular volume among Classes I, II, and III. An inverse relationship was found between mandibular volume and Mp, and a significant difference was noted in mandibular volume between the hypodivergent and hyperdivergent groups. CONCLUSIONS: In addition to two-dimensional analysis, such as lateral cephalometry, three-dimensional information such as volume, provided by cone-beam computed tomography, contributes to a more detailed assessment of maxillofacial morphology.

Evaluation of the mandibular volume and correlating variables in patients affected by unilateral and bilateral cleft lip and palate: a cone-beam computed tomography study.

OBJECTIVES: The aims of the present study were to evaluate the mandibular volume in patients affected by unilateral (UCLP) and bilateral cleft lip and palate (BCLP) and to compare the findings with a well-matched normal occlusion sample without cleft. MATERIALS AND METHODS: The study sample consisted of 66 patients divided into UCLP (24 patients; mean age, 14.46 ± 3.24 years), BCLP (17 patients; mean age, 14.28 ± 2.85 years), and control (25 patients; mean age, 14.40 ± 2.81 years) groups. The volume of the mandible including the condyle and the roots of the teeth and craniofacial measurements were performed using cone-beam computed tomography and analyzed using the one-way variance analysis and post hoc Tukey's tests. Regression analyses were used to evaluate the relationships of the measurements and the mandibular volume. RESULTS: Patients affected by UCLP and BCLP had similar craniofacial features (p > 0.05), including decreased SNB, Co-A, Co-Gn, Co-Go, and Go-Gn and increased ANB and SN-MP measurements compared to the control group. Both UCLP and BCLP groups had decreased values of mandibular volume compared to the normal occlusion group, while these differences were found to be statistically insignificant (p > 0.05). Co-Go (Beta = 0.420; p = 0.014) and Co-Gn variables (Beta = 0.708; p = 0.045) were positively correlated with mandibular volume, while SNB (Beta = -0.669; p = 0.044) and SN-MP (Beta = -0.358; p = 0.049) variables were negatively correlated (R (2) = 60.3 and p = 0.000). CONCLUSION: Mandibular volume insignificantly differs in cleft patients (p > 0.05), and the variables of Co-Go, Co-Gn, SNB, and SN-MP significantly correlate with the volume. CLINICAL RELEVANCE: This article investigates mandibular volume in patients affected by UCLP and BCLP that has never been investigated in the literature. The present study showed that both UCLP and BCLP groups had insignificantly decreased values of mandibular volume compared to the normal occlusion group.