Mandibular asymmetry types and differences in dental compensations of Class III patients analyzed with cone-beam computed tomography.

OBJECTIVES: To assess differences in dental compensation of the incisors and first molars in skeletal Class III patients with roll-, yaw-, and translation-dominant mandibular asymmetries. MATERIALS AND METHODS: A total of 90 skeletal Class III adult patients (mean age, 22.00 ± 3.31 years; range, 18-37.9 years) with facial asymmetry were enrolled and divided into the roll-, yaw-, and translation-dominant type groups (n = 30 per group). The vertical, transverse, and anteroposterior distances and axial angles of the teeth were measured using cone-beam computed tomography images. The measurements were compared between the deviated and nondeviated sides using a paired t-test and among the three groups using one-way analysis of variance with a Tukey post hoc test. RESULTS: The roll-dominant groups showed the greatest values for the bilateral difference in the vertical position of the maxillary (2.42 ± 1.24 mm) and mandibular molars (2.23 ± 1.28 mm; P < .001). The transverse deviations of the maxillary (2.19 ± 1.51 mm) and mandibular incisors (-2.11 ± 1.39 mm) were greater in the yaw-dominant groups than those of other groups. Regarding tooth axial angle, the yaw-dominant group showed the greatest tipping of the mandibular incisor (-4.13 ± 3.30°; P < .001). CONCLUSIONS: Dental compensation differed depending on the type of facial asymmetry. The roll-dominant type showed more vertical compensation of the posterior teeth, whereas the yaw-dominant type exhibited more tipping of the molars and incisors. By precisely assessing dental compensation in each asymmetry type, sufficient dental decompensation could be achieved.

A cross-sectional study on three-dimensional compensatory characteristics of maxillary teeth in patients with different types of skeletal Class III malocclusion with mandibular asymmetry.

OBJECTIVE: The purpose of this study was to analyze three-dimensional dental compensation in patients with different types of skeletal Class III malocclusion with mandibular asymmetry, using cone-beam computed tomography (CBCT) and three-dimensional reconstruction measurement technology, thereby providing clinical guidance and reference for combined orthodontic and orthognathic treatment. METHODS: 81 patients with skeletal Class III malocclusion with mandibular asymmetry were selected in accordance with the inclusion criteria. According to a new classification method based on the direction and amount of menton deviation relative to ramus deviation, patients were divided into three groups called Type 1, Type 2, and Type 3. In Type 1, the direction of menton deviation was consistent with that of ramus deviation and the amount of menton deviation was greater than that of ramus deviation. In Type 2, the direction of menton deviation was consistent with that of ramus deviation and the amount of menton deviation was smaller than that of ramus deviation. In Type 3, the direction of menton deviation was inconsistent with that of ramus deviation. The maxillary occlusal plane (OP), anterior occlusal plane (AOP), and posterior occlusal plane (POP) were measured on reconstructed CBCT images. The vertical, transverse, and anteroposterior distances from maxillary teeth to reference planes and the 3D angles between the long axis of these teeth and reference planes were measured. These dental variables measured from the deviated and non-deviated sides were compared within each group, as well as among each other. RESULTS: Of the 81 patients with asymmetrical Class III malocclusion, 52 patients were categorized in Type 1, 12 patients in Type 2, and 17 patients in Type 3. There were significant differences between deviated and non-deviated sides in Type 1 and Type 3 (p < 0.05). In Type 1, the vertical distances of maxillary teeth on the deviated side were lower than those on the non-deviated side, and AOP, OP, and POP on the deviated side were larger than those on the non-deviated side (p < 0.05). In Type 3, the vertical distances of the maxillary teeth on the deviated side were lower (p < 0.05), and the AOP and OP on the deviated side were larger than those on the non-deviated side. In all three groups, the transverse distances of the maxillary teeth from the mid-sagittal plane on the deviated side were larger than those on the non-deviated side (p < 0.05), and the angles between the long axis of maxillary teeth and the mid-sagittal plane on the deviated side were larger, respectively (p < 0.05). CONCLUSIONS: The maxillary teeth on the deviated side were observed to have smaller eruption heights in Type 1 and Type 3. In Type 1, AOP, POP, and OP were greater on the deviated side, while in Type 3, only AOP and OP were greater on the deviated side. The maxillary teeth of patients in all three groups on the deviated side were buccal and buccally inclined. Larger sample observations are still needed to further verify these findings.

Orthodontic camouflage as a treatment alternative for skeletal Class III

ABSTRACT Introduction: Skeletal Class III malocclusion is a deformity of complex treatment, with few intervention alternatives, which are further limited in nongrowing patients. In most cases, orthognathic surgery is the ideal treatment for adults, an option often refused by patients. Mild to moderate skeletal Class III malocclusions and acceptable facial esthetics can benefit from a course of treatment in which dental movements are used to compensate for the skeletal discrepancy. Objective: This study aimed to discuss orthodontic camouflage as an option for adult patients with Class III malocclusion, emphasizing its indications, implications and expected results.

RESUMO Introdução: A má oclusão esquelética de Classe III é uma deformidade de difícil tratamento e com poucas alternativas de intervenção, que ficam ainda mais limitadas em pacientes sem crescimento. Na maior parte dos casos, o tratamento ideal para adultos é a cirurgia ortognática, opção muitas vezes recusada pelo paciente. As más oclusões esqueléticas de Classe III leve a moderada e com estética facial aceitável podem se beneficiar de um plano de tratamento no qual movimentações dentárias são realizadas para compensar a discrepância esquelética. Objetivo: O objetivo do presente estudo foi discutir a camuflagem ortodôntica como opção para pacientes adultos com má oclusão de Classe III, ressaltando suas indicações, implicações e resultados esperados.

Multiloop edgewise archwire technique and denture frame analysis: a systematic review.

BACKGROUND: The Multiloop Edgewise Archwire (MEAW) appliance is an orthodontic treatment method suitable for the therapy of severe types of malocclusions such as open bites or anterior crossbites. The cephalometric Denture Frame Analysis (DFA) provides a supportive diagnostic tool for patient-specific treatment planning concerning the rearrangement of occlusion within the "denture frame". The objective of this study is to give a comprehensive overview of the national and international scientific literature about MEAW and DFA regarding the general therapeutic effects, advantages and limitations. METHODS AND MATERIALS: A computerized literature search was performed using four principal medical databases (PubMed/Medline, Google Scholar, Web of Science and Cochrane Central Register of Controlled Trials) and supplemented by manual searching of the references listed in the retrieved articles. The results were screened and assessed following the PRISMA guidelines. RESULTS: Six hundred seventy-seven full articles were assessed for eligibility. A number of 134 articles went through qualitative analysis and 3 studies were finally involved in comparative synopsis. The findings reveal advantageous characteristics of the MEAW technique such as a high degree of three-dimensional individual tooth control and a comparatively low load deflection rate, causing mostly dentoalveolar changes without significantly influencing the skeletal structures. CONCLUSION: Based on current literature, the MEAW technique appears to have several therapeutic benefits and serves as a sufficient alternative treatment method for dentoalveolar compensation, when measures of orthognathic surgery are rejected. Concerning the deficient data basis of available literature and the low level of scientific evidence, further studies are required in order to expand on the knowledge in this subject area. Several aspects like the effectiveness or the long-term stability have to be evaluated more extensively. Moreover, the transferability of the DFA to ethnic groups other than the Asian ethnicity should be examined further.

Cone-beam computed tomography analysis of transverse dental compensation in patients with skeletal Class III malocclusion and facial asymmetry.

OBJECTIVE: The purpose of this study was to analyze the transverse dental compensation in reference to the maxillary and mandibular basal bones using cone-beam computed tomography (CBCT) and evaluate the correlations between transverse dental compensation and skeletal asymmetry variables in patients with skeletal Class III malocclusion and facial asymmetry. METHODS: Thirty patients with skeletal Class I (control group; 15 men, 15 women) and 30 patients with skeletal Class III with menton deviation (asymmetry group; 16 men, 14 women) were included. Skeletal and dental measurements were acquired from reconstructed CBCT images using OnDemand3D 1.0 software. All measurements were compared between groups and between the deviated and nondeviated sides of the asymmetry group. Correlation coefficients for the association between skeletal and dental measurements were calculated. RESULTS: Differences in the ramus inclination (p < 0.001), maxillary canine and first molar inclinations (p < 0.001), and distances from the canine and first molar cusp tips to the midmaxillary or midmandibular planes (p < 0.01) between the right and left sides were significantly greater in the asymmetry group than in the control group. In the asymmetry group, the ramus inclination difference (p < 0.05) and mandibular canting (p < 0.05) were correlated with the amount of menton deviation. In addition, dental measurements were positively correlated with the amount of menton deviation (p < 0.05). CONCLUSIONS: Transverse dental compensation was correlated with the maxillary and mandibular asymmetry patterns. These results would be helpful in understanding the pattern of transverse dental compensation and planning surgical procedure for patients with skeletal Class III malocclusion and facial asymmetry.

Cone-beam computed tomography analysis of transverse dental compensation in patients with skeletal Class III malocclusion and facial asymmetry / 대한치과교정학회지

OBJECTIVE: The purpose of this study was to analyze the transverse dental compensation in reference to the maxillary and mandibular basal bones using cone-beam computed tomography (CBCT) and evaluate the correlations between transverse dental compensation and skeletal asymmetry variables in patients with skeletal Class III malocclusion and facial asymmetry. METHODS: Thirty patients with skeletal Class I (control group; 15 men, 15 women) and 30 patients with skeletal Class III with menton deviation (asymmetry group; 16 men, 14 women) were included. Skeletal and dental measurements were acquired from reconstructed CBCT images using OnDemand3D 1.0 software. All measurements were compared between groups and between the deviated and nondeviated sides of the asymmetry group. Correlation coefficients for the association between skeletal and dental measurements were calculated. RESULTS: Differences in the ramus inclination (p < 0.001), maxillary canine and first molar inclinations (p < 0.001), and distances from the canine and first molar cusp tips to the midmaxillary or midmandibular planes (p < 0.01) between the right and left sides were significantly greater in the asymmetry group than in the control group. In the asymmetry group, the ramus inclination difference (p < 0.05) and mandibular canting (p < 0.05) were correlated with the amount of menton deviation. In addition, dental measurements were positively correlated with the amount of menton deviation (p < 0.05). CONCLUSIONS: Transverse dental compensation was correlated with the maxillary and mandibular asymmetry patterns. These results would be helpful in understanding the pattern of transverse dental compensation and planning surgical procedure for patients with skeletal Class III malocclusion and facial asymmetry.

Mixed-reality simulation for orthognathic surgery.

BACKGROUND: Mandibular motion tracking system (ManMoS) has been developed for orthognathic surgery. This article aimed to introduce the ManMoS and to examine the accuracy of this system. METHODS: Skeletal and dental models are reconstructed in a virtual space from the DICOM data of three-dimensional computed tomography (3D-CT) recording and the STL data of 3D scanning, respectively. The ManMoS uniquely integrates the virtual dento-skeletal model with the real motion of the dental cast mounted on the simulator, using the reference splint. Positional change of the dental cast is tracked by using the 3D motion tracking equipment and reflects on the jaw position of the virtual model in real time, generating the mixed-reality surgical simulation. ManMoS was applied for two clinical cases having a facial asymmetry. In order to assess the accuracy of the ManMoS, the positional change of the lower dental arch was compared between the virtual and real models. RESULTS: With the measurement data of the real lower dental cast as a reference, measurement error for the whole simulation system was less than 0.32 mm. In ManMoS, the skeletal and dental asymmetries were adequately diagnosed in three dimensions. Jaw repositioning was simulated with priority given to the skeletal correction rather than the occlusal correction. In two cases, facial asymmetry was successfully improved while a normal occlusal relationship was reconstructed. Positional change measured in the virtual model did not differ significantly from that in the real model. CONCLUSIONS: It was suggested that the accuracy of the ManMoS was good enough for a clinical use. This surgical simulation system appears to meet clinical demands well and is an important facilitator of communication between orthodontists and surgeons.

Mixed-reality simulation for orthognathic surgery / 대한악안면성형재건외과학회지

BACKGROUND: Mandibular motion tracking system (ManMoS) has been developed for orthognathic surgery. This article aimed to introduce the ManMoS and to examine the accuracy of this system. METHODS: Skeletal and dental models are reconstructed in a virtual space from the DICOM data of three-dimensional computed tomography (3D-CT) recording and the STL data of 3D scanning, respectively. The ManMoS uniquely integrates the virtual dento-skeletal model with the real motion of the dental cast mounted on the simulator, using the reference splint. Positional change of the dental cast is tracked by using the 3D motion tracking equipment and reflects on the jaw position of the virtual model in real time, generating the mixed-reality surgical simulation. ManMoS was applied for two clinical cases having a facial asymmetry. In order to assess the accuracy of the ManMoS, the positional change of the lower dental arch was compared between the virtual and real models. RESULTS: With the measurement data of the real lower dental cast as a reference, measurement error for the whole simulation system was less than 0.32 mm. In ManMoS, the skeletal and dental asymmetries were adequately diagnosed in three dimensions. Jaw repositioning was simulated with priority given to the skeletal correction rather than the occlusal correction. In two cases, facial asymmetry was successfully improved while a normal occlusal relationship was reconstructed. Positional change measured in the virtual model did not differ significantly from that in the real model. CONCLUSIONS: It was suggested that the accuracy of the ManMoS was good enough for a clinical use. This surgical simulation system appears to meet clinical demands well and is an important facilitator of communication between orthodontists and surgeons.

The assessment of dentoalveolar compensation in facial asymmetry individuals: integration of cone beam CT and laser scanned dental cast images / 대한치과교정학회지

OBJECTIVE: The purpose of this study was to assess the dentoalveolar compensation in facial asymmetry individuals using an integration of a CBCT image and a laser scanned dental cast image. METHODS: The subjects consisted of 30 adults with asymmetric mandibles and 20 adults with symmetric mandibles. The CBCT and laser scanned dental cast images were integrated with a registration technique. Canine and first molar position and angulation were assessed from reference coordinates. The differences between deviated and non-deviated sides were analyzed with the paired t-test. The differences shown according to menton deviation were also statistically analyzed using Pearson correlation analysis. RESULTS: The experimental group showed deviated and non-deviated side differences (dev.-ndev.) in the position and angle of the canine and first molars. Menton deviation showed positive correlation with the deviation side (dev.-ndev.) for the maxillary and mandibular 1st molar angles, negative correlation with the deviation side for the vertical position of the maxillary 1st molars, transverse position of the mandibular canine, transverse position and vertical position of the mesio-lingual cusp of the mandibular 1st molars. CONCLUSIONS: The upper and lower canine and first molars of facial asymmetry individuals were compensated, so the transverse position, vertical position, and angle showed differences between the deviated/non-deviated sides.

The relationship between posterior dental compensation and skeletal discrepancy in class III malocclusion / 대한치과교정학회지

This study examined the relations between degree of posterior dental compensation and skeletal discrepancy in Class III malocclusion. The pretreatment lateral cephalograms and dental casts of 87 skeletal Class III adults were selected to provide a random sampling of skeletal Class III malocclusion. Skeletal discrepancy was described with ANB angle, Wits appraisal, SN-Mn plane angle, FMA and ratios of basal arch width. Degree of posterior dental compensation was described with maxillary intermolar angle, mandibular intermolar angle and sum of intermoloar angle. The relationships between skeletal discrepancy and degree of posterior dental compensation were analyzed with simple correlation analysis, stepwise multiple regression analysis. The results were as follows : 1. A strong association was found between the variation in the anteroposterior measure, ANB angle and the variation of posterior dental compensation measures, sum of intermolar angle and mandibular intermolar angle in skeletal Class III malocclusion. 2. There was no statistically significant relationship between the variation in the vertical measures and the variation of posterior dental compensation measures in skeletal Class III malocclusion. 3. There was no statistically significant relationship between the variation in the anteroposterior and vertical measures and degree of basal arch width discrepancy.

The correlation between dental compensation and craniofacial morphology in skeletal Class III malocclusion / 대한치과교정학회지

This investigation was designed to analyze the degree of dental compensation according to horizontal components of craniofacial skeleton and to investigate correlation between dental compensation and craniofacial pattern in skeletal class III malocclusion. The material selected for this study consisted of standard lateral cephalogram of 59 subjects in normal occlusion group, 91 subjects in mild skeletal class III malocclusion group and 58 subjects in severe skeletal class III malocclusion group. The mild skeletal class III malocclusion group was divided into two groups, one was class III malocclusion without anterior crossbite group and the other was class III malocclusion with anterior crossbite group. The data were analyzed by Quick-ceph image program. The results were as follows. 1. Mild skeletal class III malocclusion without anterior crossbite group showed the most labial inclination of upper incisors, followed by severe skeletal class III malocclusion group and mild skeletal class III malocclusion with anterior crossbite group, the Latter showing the least. The amount of lingual inclination of lower incisors was the largest in severe skeletal class III malocclusion group, and there was no statistically significant difference between mild skeletal claw III malocclusion without anterior crossbite group and mild skeletal class III malocclusion with anterior crossbite group. 2. There were little differences in vertical skeletal structure between mild skeletal class III malocclusion without anterior crossbite group and mild skeletal class III malocclusion with anterior cwssbite group, they showed statistically significant differences in the upper incisors measurements. 3. The measurements of lower incisors in mild skeletal class III malocclusion without anterior crossbite group and upper incisors in mild skeletal class III malocclusion with anterior crossbite group represented a high correlation with skeletal structure. Especially, deltaIMPA and deltaFMIA of lower incisor measurements, and deltaU1-FR deltaUi-SN of upper incisor measurements showed high correlation with skeletal structure in each group. 4. deltaIMPA and deltaFMIA of lower incisor measurements showed high correlation with skeletal structure in all groups. deltaUI-FH, deltaU1-SN and Ui-facial plane(mm) of upper incisor measurements represented higher correlation with skeletal structure than any other upper incisor measurements.