Effects of early unilateral mandibular first molar extraction on condylar and ramal asymmetry / Efectos de la extracción temprana del primer molar mandibular unilateral sobre la asimetría condilar y ramal

SUMMARY: Craniofacial symmetry is an important factor in creating a harmonious facial appearance. Genetic and external factors may cause the formation of mandibular asymmetry. The aim of this study was to evaluate vertical mandibular asymmetries in adolescents who had unilateral mandibular first permanent molar (FPM) teeth extracted at an early age. The study group consisted of 60 subjects (30 females, 30 males with a mean age of 16.18±1.04 years) who had their mandibular permanent first molar tooth extracted before the age of 12, and the control group consisted of 60 healthy subjects (30 females, 30 males with a mean age of 16.23±0.92 years). Condylar asymmetry index (CAI), ramal asymmetry index (RAI), and condylar-ramal asymmetry index (CRAI) were calculated using panoramic radiographs of the subjects. Independent samples t-test was used to evaluate the differences between groups. CAI, RAI, and CRAI values were similar between male and female subjects in both control and study groups, and no statistically significant difference was found (p>0.05). No statistically significant difference was observed between the group who had their mandibular first permanent molar teeth extracted at an early age and the control group (p>0.05). CAI values were relatively higher in both groups, but there was no significant difference between the CAI, RAI, and CRAI values between the groups.

La simetría craneofacial es un factor importante para crear una apariencia facial armoniosa. Factores genéticos y externos pueden causar la formación de asimetría mandibular. El objetivo de este estudio fue evaluar las asimetrías mandibulares verticales en adolescentes a quienes se les extrajo el primer molar permanente (FPM) mandibular unilateral a una edad temprana. El grupo de estudio consistió en 60 sujetos (30 mujeres, 30 hombres con una edad media de 16,18±1,04 años) a quienes se les extrajo el primer molar mandibular permanente antes de los 12 años, y el grupo control consistió en 60 sujetos sanos (30 mujeres, 30 hombres con una edad media de 16,23±0,92 años). El índice de asimetría condilar (CAI), el índice de asimetría ramal (RAI) y el índice de asimetría condilar-ramal (CRAI) se calcularon utilizando radiografías panorámicas de los sujetos. Se utilizó la prueba t de muestras independientes para evaluar las diferencias entre los grupos. Los valores de CAI, RAI y CRAI fueron similares entre los hombres y las mujeres tanto en el grupo control como en el de estudio, y no se encontraron diferencias estadísticamente significativas (p>0.05). No se observaron diferencias estadísticamente significativas entre el grupo al que se le extrajo el primer molar permanente mandibular a una edad temprana y el grupo control (p>0,05). Los valores de CAI fueron relativamente más altos en ambos grupos, pero no hubo diferencias significativas entre los valores de CAI, RAI y CRAI entre los grupos.

CBCT analysis of condylar and occlusal plane features in skeletal Class Ⅲ malocclusion patients with mandibular asymmetry / 口腔医学

Objective@#To analyze the condylar and inclination of the occlusal plane features in skeletal Class Ⅲ malocclusion patients with mandibular asymmetry by using cone beam computed tomography(CBCT).@* Methods@#Forty eligible patients with Angle Class Ⅲ malocclusion were enrolled. All individuals were classified based on the distance from Me point to median sagittal plane. The left and right angles between OP and FH plane, the position and morphology of the condyle were measured in both groups.Then the data collected were statistically analyzed. @* Results@#Compared to the opposite side, there was a statistically significant difference(P<0.05) in angle between OP and FH plane, the anterior joint space, superior joint space, lateral joint space and condylar mediolateral diameter, with a higher proportion of joint posteriority in deviated side. Mandibular deviations were positively correlated with both the anterior joint space of the deviated side and the angle between OP and FH plane of the opposite side(P<0.01). There was no statistical difference between the left and right side of angles between OP and FH plane, the position and morphology of the condyle in skeletal Class Ⅲ patients without mandibular deviation(P>0.05); the joint was predominantly in anterior and middle position. @*Conclusion@#There is asymmetry on the left and right sides of the inclination ofocclusal plane, the position and morphology of the condyle of skeletal Class Ⅲ malocclusion patients with mandibular asymmetry. Compared with the opposite side, the deviated side has smaller angle between OP and FH plane and smaller condylar mediolateral diameter, and the condyle shows generally more posterior, inferior and inward movement in glenoid fossa. The inclination of the occlusal plane and the position of condyle are significantly and positively correlated with the distance from Me point to median sagittal plane.

Prevalencia de asimetrías mandibulares en pacientes de Quito Ecuador medidas mediante radiografías panorámicas / Prevalence of Mandibular Asymmetries in Patients from Quito Ecuador Measured through Panoramic Radiographies

Antecedentes: Las asimetrías mandibulares se consideran variaciones morfológicas que pueden ser imperceptibles o asociarse a maloclusiones, trastornos temporomandibulares y asimetrías faciales. Objetivo: Determinar la prevalencia de asimetría vertical mandibular en radiografías panorámicas de pacientes atendidos en el centro quirúrgico de la Facultad de Odontología de la Universidad Central del Ecuador, mediante el análisis de Habets. Métodos: Se llevó a cabo un estudio descriptivo retrospectivo para analizar radiografías panorámicas de pacientes mayores de 15 años que presentaron dentición definitiva completa y asistieron a consulta durante los 3 últimos años. La muestra estuvo compuesta por 680 radiografías que correspondían 309 a pacientes hombres y 371 mujeres, con una edad promedio de 22,02 años. Se utilizaron la prueba de Chi cuadrado para evaluar la asociación de las asimetrías encontradas en cada una de las variables dependientes con la edad y sexo del paciente, y las de Mann-Whitney y Kruskal Wallis para la distribución de las variables (intervalo de confianza del 95 %, p<0,05). Resultados: La prevalencia de asimetrías verticales condilares fue del 70,3 %, las de rama 38,7 % y la de cóndilo-rama 30,7 %. Estos valores presentaron mayor tendencia hacia el lado izquierdo. Conclusión: El índice de asimetría de Habets con un corte del 3 % mostró una prevalencia de asimetría condilar en mayor grado, seguida por la asimetría de rama y, menos prevalente, la cóndilo-rama. Estos valores no representaron significancia estadística en relación con la edad y el sexo del paciente.

Background: Mandibular asymmetries are considered morphological variations, which may be imperceptible or linked to malocclusions, temporomandibular disorders, and facial asymmetries. Purpose: To determine the prevalence of mandibular vertical asymmetries through panoramic radiographs of patients treated at the surgical center of the Universidad Central del Ecuador using Habets analysis. Methods: A descriptive and retrospective was conducted to analyze panoramic radiographies of older-than-15-year-old patients who presented complete permanent dentition and were seen within the last 3 years. The sample consisted of 680 radiographs of 309 men and 371 women, with an average age of 22.02 years. Chi-square test was used to analyze the association between asymmetries found for each dependent variable and patients' age and sex. Mann-Whitney and Kruskal Wallis tests were performed to analyze variable distribution (confidence interval of 95 %. p<0.05). Results: The prevalence of vertical condylar asymmetry was 70.3 %, followed by ramus (38.7 %), and condyle- ramus (30.7 %). There was a larger tendency towards the left side. Conclusion: The Habets asymmetry index with a 3 % cut showed a prevalence of condylar asymmetry to a greater degree, followed by ramus asymmetry and condylar-ramus asymmetry. These values did not show statistical significance regarding age and sex.

Mandibular morphology of adults with skeletal classⅢmalocclusion and mandibular deviation analysed by CBCT / 实用口腔医学杂志

Objective:To analyse the asymmetry of mandibular of adults with skeletal classⅢmalocclusion and mandibular deviation using cone-beam computerized tomography(CBCT).Methods:20 adults with skeletal classⅢmalocclusion and mandibular deviation (deviation group)and 20 adults with individual normal occlusion(normal group)were included.CBCT slices were taken for each sub-ject.INVIVO 5 software was used to make 3D reconstruction and location marks for line distance and volume measurements of mandi-ble and condyle.Results:The measurements of the mandibular ramus length,mandibular total length,hemi-mandibular volume, mandibular ramus volume,posterior part of mandibular body length,condylar unit length,angular unit length,body unit length and an-gular angle in deviation group were significantly different between 2 sides(P<0.05).Compared with the normal group,differences of the asymmetry of mandibular ramus length,mandibular total length,hemi-mandibular volume,mandibular ramus volume,posterior part of mandibular body length,angular angle,condylar unit length and body unit length between 2 sides in deviation group were sig-nificantly different(P<0.05).Conclusion:In adults with skeletal classⅢmalocclusion and mandibular deviation deviated condylar and mandibular ramus are smaller than those of the nondeviated;the posterior part of mandibular body is slightly asymmetric while the anterior part of mandibular body is almost symmetric.

Evaluación de la asimetría vertical mandibular, en pacientes con mordida cruzada posterior uni y bilateral / Evaluation of mandibular asymmetry in unilateral and bilateral posterior crossbite patients

El objetivo fue determinar la existencia de asimetría vertical mandibular, en pacientes con mordida cruzada posterior uni y bilateral, tanto en dentición mixta primera fase como en permanente completa. Se recolectaron radiografías panorámicas correspondientes a 121 pacientes con dentición mixta primera fase y permanente completa, 57 de los cuales, presentaba mordida cruzada unilateral, 21 mordida cruzada bilateral y 43 individuos con oclusión normal, que sirvieron como grupo control. En las radiografías, se cuantificaron medidas lineales de altura condilar, coronoidea, de rama, cóndilo-más-rama y la diferencia entre las alturas de cóndilo y coronoides. Además, se calcularon los índices de asimetría para cada una de dichas estructuras. Se determinó la existencia de diferencias significativas entre los grupos, mediante el cálculo de los test Mann-Whitney y Kruskal-Wallis, dada la distribución de las variables y un test de chi cuadrado para evaluar asociación entre las mismas, con un intervalo de confianza de 95 por ciento (p<,05). Existen diferencias significativas entre los índices de rama y de cóndilo-más-rama, entre el grupo control y el grupo con mordida cruzada unilateral (MCU), al igual que en el índice coronoideo, entre el grupo control y el grupo con mordida cruzada bilateral. El grupo con MCU, presentó un mayor porcentaje de pacientes con asimetría de cóndilo y rama, encontrándose una leve asociación entre la condición de mordida cruzada unilateral y la asimetría de dichas estructuras. Dados los resultados, se puede concluir que existe asimetría en el cóndilo, coronoides y en cóndilo-menos-coronoides y coronoides, tanto en pacientes con mordida cruzada uni como bilateral. Sin embargo, el grupo con MCU presenta un mayor porcentaje de pacientes con asimetría de cóndilo y rama, existiendo una leve asociación entre MCU y asimetría de dichas estructuras...

The aim was to evaluate the mandibular vertical asymmetry, in unilateral and bilateral posterior crossbite patients both in permanent and mixed dentition. One hundred twenty one panoramic radiographs were collected, 57 from patients with unilateral posterior crossbite, 21 patients with bilateral posterior crossbite and 43 with normal occlusion that were used as a control group. Subsequently, reference points and cephalometric traces were drawn manually by a calibrated examiner in order to register the condylar, coronoideal, and ramal heigths. This data was used to calculate an asymmetry index for each structure. According to the distribution of the variables, Mann-Whitney and Kruskal-Wallis test was used to compare the data between groups of patients and chi square was used to evaluate association between them, at the 95 percent confidence interval (p<.05). Statistically significant differences were found in the ramal and condylar-plus-ramal asymmetry index values, between the control and the unilateral posterior crossbite group, also statistical differences were found in the coronoideal index values, between the control and the bilateral posterior crossbite groups. On the other hand, the bilateral crossbite group, presented a higher percentage of patients with condylar and ramal asymmetry, finding a mild statistically significant association between this condition and those with asymmetry. Condylar and coronoideal asymmetry was found both in the unilateral as in the unilateral posterior crossbite patients. The bilateral crossbite group, presented a major percentage of patients with asymmetry, with a mild association between those conditions...

Facial asymmetry with mandibular prognathism: A new trial of classification and interpretation

OBJECT: Patients with facial asymmetry accompanying mandibular prognathism have various causes and clinical features. So, it is difficult to find a satisfactory treatment method functionally and esthetically. Every traditional classification and interpretation to find etiopathogenesis and/or to establish ideal surgical modality has many limitations because it can't be applied simply to various conditions of patients with facial asymmetry accompanying mandibular prognathism. Therefore, we employ a new classification to interpret more details of the morphologic change of mandible and the spatial change of mandible and maxilla. MATERIALS AND METHODS: Using panoramic X-ray films, PA cephalograms and submentovertex films of 126 patients diagnosed with facial asymmetry accompanying mandibular prognathism as resources, the following results were gathered after analyzing each characteristics through distributing the patterns according to the morphological mandibular asymmetry and mandibular and maxillary spatial asymmetry. RESULTS: Almost frequency of morphological mandibular asymmetry was shown. In case of condyle-ramus elongation and body elongation group, it's frequency was the highest. Higher frequency of compensating vertical growth was shown on the side of over growing maxilla in case of vertical length difference between left and right condyle-ramus. On the other hand, higher frequency of no compensating vertical growth difference between left and right side was shown in case of no vertical length difference in condyleramus. Spatial mandibular asymmetry generally occurred when there was no morphological mandibular asymmetry. Correlation between condyle length difference and condyle-ramus length difference between left and right side was very high, but correlation between condyle length difference and body length difference, and correlation between condyle length difference and body vertical length difference was low. CONCLUSION: In case of patients with facial asymmetry accompanying mandibular prognathism, it is suggested that various pattern of facial asymmetry is occurred by the independent growth of each unit rather than dependent growth of other unit by major growth unit abnormality. Due to the untypical pattern and the various asymmetry occurring according to the changes of each mandibular growth unit, it is considered that an appropriate surgical method should be searched based on the accurate recognition of the each pattern for patients with facial asymmetry accompanying mandibular prognathism.

Comparative study on the osseous changes of the TMJ and mandibular asymmetry after conservative or operative treatment in condylar fracture patients / 대한구강악안면방사선학회지

PURPOSE: To compare the effects of the conservative treatment and operative treatment by observation of osseous changes of the TMJ and mandibular asymmetry in condylar fracture patients. MATERIALS AND METHODS: 33 condylar fracture patients (17 with conservative and 16 with operative treatment) were included in this study. After a minimum of 6 months after the surgical procedure, patients were given a follow up examination of the osseous changes using a transcranial view. Differences in the osseous changes of both groups were compared and the asymmetry indices were calculated on a postero-anterior skull view. RESULTS: The TMJ of the operative treatment group showed more significant osseous changes than the conservative treatment group. The affected TMJ showed more significant osseous changes than the unaffected TMJ in the both groups. The unaffected TMJ of the conservative group and the affected TMJ of the operative group showed significant osseous changes. The mandibular asymmetry indices in the conservative and operative group were 5.12 and 7.30 respectively at the time of treatment, and 2.39 and 3.41 respectively at the follow-up. But the mandibular asymmetry between the both groups showed no statistical differences. CONCLUSION: The TMJ of the operative group showed more significant osseous changes than the conservative group, but the mandibular asymmetry between the both groups showed no statistical difference.

The relationship between mandibular asymmetry and temporomandibular joint disc displacement on mri

PURPOSE: This study was aimed to investigate the relationship between the mandibular asymmetry and the internal derangement of temporomandibular joint. MATERIALS AND METHODS: One hundred and sixty eight patients had been assessed through clinical examinations, panoramic radi-ographs and magnetic resonance imagings (MRIs), were selected. The samples were classified into three subgroups according to the severity of the mandibular asymmetries in the panoramic radiographs and the status of TMJ discs on the MRI were compared among each groups. RESULTS: In an apparent asymmetry group, there was a significant difference in the number of temporomandibular disk displacement without reduction between the long and short side (66.7%, 18/27 joints on the short side) when the ratio of condylar process and coro-noid process was used (P<0.05), but there was no statistically significant difference when the ratio of condyle and ramus was used. CONCLUSION: The probability of the disc displacement without reduction was higher at the side with relatively shorter condylar process on the panoramic radiograph, and also it might be more effective to use ratio of condylar process and coronoid process in the assessment of mandibular asymmetry. Therefore, a careful assessment on the temporomandibular disorders is necessary to diagnose and establish the treatment plans for the patients with a mandibular asymmetry and the panoramic radiograph can be used effectively on that way.