Study on the transverse relationship of the mandible between different skeletal vertical patterns in patients with skeletal ClassⅠ malocclusion / 口腔疾病防治

Objective@#To analyze the correlation between skeletal vertical patterns and mandibular dental arch width, basal arch width and the dental buccolingual inclination of patients with skeletal ClassⅠ@*Methods@#The CBCT data of 62 skeletal ClassⅠ malocclusion patients were collected and divided into a high-angle group with 19 cases, a mean-angle group with 22 cases, and a low-angle group with 21 cases according to the GoGn-SN angle. Mandible 3D reconstruction of the three groups was performed using Dolphin software, and dental arch widths, basal arch widths and buccolingual inclination of canines, first premolars and first molars, were measured and statistically analyzed respectively. @*Redults@#Mandibular dental arch width showed no significant difference among the three groups (P>0.05). The basal arch widths of mandibular canines and first premolars in low-angle group were larger than those in the other groups (P<0.05). The buccolingual inclinations of mandibular canines and first premolars in high-angle group were larger than those in the other groups (P<0.05). The buccolingual inclination and basal arch width of the first molars among the three groups showed no significant differences (P>0.05). Pearson correlation tests showed that the basal arch widths of mandibular canines and first premolars were negatively correlated with GoGn-SN angle. Excluding the influence of dental arch width and basal arch width, there was still a significant positive correlation between the buccolingual inclination of mandibular canines and first premolars and the GoGn-SN angle (P<0.05).@*Conclusion@#The width of the basal bone arch between different skeletal vertical patterns mainly differs in the canine segment and the premolar segment, and the difference in the buccolingual inclination of the teeth is mainly to compensate for the difference in the GoGn-SN angle. In clinical practice, individualized therapy should be adopted according to the differences to achieve the long-term efficacy of correction.

Comparison of airway dimensions in skeletal Class I malocclusion subjects with different vertical facial patterns

ABSTRACT Objective: The aim of this study was to compare upper airway widths among skeletal Class I malocclusion subjects with different vertical facial patterns. Methods: The sample included a total of 99 lateral cephalograms of post pubertal individuals (18.19 ± 1.76 years old). The vertical facial pattern was determined by the Vert index. The McNamara method was used to quantify upper airway widths. ANOVA test and Student's t test for independent groups were used, when normal distribution was not supported Kruskal-Wallis test and U-Mann-Whitney test were used. A multiple linear regression analysis was also performed. Results: Statistically significant differences in several nasopharyngeal widths were found among the distinct vertical facial patterns. Subjects with brachyfacial pattern presented larger nasopharyngeal widths than subjects with mesofacial (p= 0.030) or dolichofacial (p= 0.034) patterns. The larger the Vert value, the larger the nasopharyngeal widths (R2= 26.2%, p< 0.001). At the level of oropharynx no statistically significant differences were found. Conclusion: It was concluded that nasopharyngeal linear anteroposterior widths in Class I malocclusion brachyfacial are larger than in mesofacial and dolichofacial individuals. The Vert index only explained 25% of the total variability. No correlation was found for the oropharyngeal widths.

RESUMO Objetivo: o objetivo desse estudo foi comparar as dimensões das vias aéreas superiores em indivíduos portadores de má oclusão de Classe I esquelética com diferentes padrões faciais verticais. Métodos: a amostra consistiu de 99 cefalogramas laterais de indivíduos na pós-puberdade (18,19 ± 1,76 anos). O padrão facial vertical foi determinado por meio do índice VERT. O método de McNamara foi utilizado para quantificar as dimensões das vias aéreas superiores. O teste ANOVA e o teste t de Student para grupos independentes foram utilizados e, quando a distribuição normal não era possível, o teste de Kruskal-Wallis e o teste U de Mann-Whitney foram aplicados. Foi também realizada uma análise de regressão linear múltipla. Resultados: diferenças estatisticamente significativas nas dimensões da nasofaringe foram encontradas entre os diferentes padrões faciais verticais. Os indivíduos com padrão braquifacial apresentaram dimensões nasofaríngeas maiores do que os indivíduos com padrão mesofacial (p= 0,030) ou dolicofacial (p= 0,034). Quanto maior o valor do VERT, maior a dimensão nasofaríngea (R2 = 26,2%, p< 0,001). Não foram encontradas, entretanto, diferenças estatisticamente significativas ao nível da orofaringe. Conclusão: pode-se concluir que as dimensões anteroposteriores lineares da nasofaringe nos indivíduos braquifaciais com má oclusão de Classe I são maiores do que nos indivíduos mesofaciais e dolicofaciais. O índice VERT foi capaz de explicar apenas 25% da variabilidade total. Não foi encontrada correlação para as dimensões da orofaringe.

Post-treatment stability of the occlusal plane according to different vertical facial patterns / 대한치과교정학회지

OBJECTIVE: The purpose of this study was to find changes in the occlusal plane related to different vertical facial patterns and suggest treatment goals and conduct possible treatment mechanisms. METHODS: 60 adult patients (28 males, 32 females) who had been diagnosed as Class I skeletal malocclusion and treated without extraction were selected. Patients were divided into three groups; short face type (group 1), average face type (group 2) and long face type (group 3), using the data on normal occlusion of Korean adults. RESULTS: The results were achieved by analyzing cephalometric tracings of each group at pre-treatment, end-treatment and post-treatment (about 1 year recall check). The inclination of the occlusion plane tends to gradually increase as the face becomes longer. In group 1, COP-X, FOP-X, L6/L1, MP-L6 were significantly decreased, and L1-FOP was significantly increased during the retention period (T3-T2). Group 2 showed no significant change. In group 3, FOP-X was significantly increased during the retention period (T3-T2). During the retention period, FOP-X showed significant change among each group, especially between group 1 and group 3. CONCLUSION: These results suggest that changes of occlusal plane inclination according to facial vertical pattern need to be considered during the retention period for intrusion, extrusion, and incisor overbite.

A study on the position of tongue and hyoid bone in relation to vertical facial patterns in skeletal Class III malocclusion / 대한치과교정학회지

The purpose of this study was to evaluate the position of tongue and hyoid bone in relation to vertical facial patterns in the adult and child. Lateral cephalograms taken in adults(63 cases, 11.7 years in average age) and children(69 cases, 22.6 years in average age) were traced and measured about position and posture of tongue and hyoid bone using the horizontal and vertical reference lines. The angle of mandibular plane to SN plane was employed to classify the samples into groups of hypodivergent and hyperdivergent. The comparison of the tongue/hyoid bone measurements between hypodivergent group and hyperdivergent group in the adult and child were statistically executed with Student's t-test. The results were as follows; 1. The tongue height was lower in the hyperdivergent group than in hypodivergent group, and higher in children than in adults. 2. The vertical height of hyoid bone was higher in hypodivergent group than in hyperdivergent group and also higher in children than in adults. 3. The anteroposterior position was of no significant difference in relation to age or vertical facial pattern. 4. The inclination of hyoid bone in relation to cranial base was steeper in children than in adults.

A study on relationship between TMD and skeletodental form in long face patterns / 대한치과교정학회지

Forty-four females with normal temporomandibular joint were compared with fifty-one females with abnormal temporomandibular joint, An orthodontic study model and lateral cephalometric radiographic were used to investigate the relationship between TMD group and non-TMD group in long face patterns. The result were followed that : 1. There were no significant in oberbite and overjet amount. 2. A mandibular 1`st molar inclination and height to the mandibular plane were more mesial inclined in TMD group. 3. The functional factors, which were craniocervical posture, tongue posture and hyoid bone position, were no significant.