New classification of lingual arch form in normal occlusion using three dimensional virtual models / 대한치과교정학회지

OBJECTIVE: The purposes of this study were 1) to classify lingual dental arch form types based on the lingual bracket points and 2) to provide a new lingual arch form template based on this classification for clinical application through the analysis of three-dimensional virtual models of normal occlusion sample. METHODS: Maxillary and mandibular casts of 115 young adults with normal occlusion were scanned in their occluded positions and lingual bracket points were digitized on the virtual models by using Rapidform 2006 software. Sixty-eight cases (dataset 1) were used in K-means cluster analysis to classify arch forms with intercanine, interpremolar and intermolar widths and width/depth ratios as determinants. The best-fit curves of the mean arch forms were generated. The remaining cases (dataset 2) were mapped into the obtained clusters and a multivariate test was performed to assess the differences between the clusters. RESULTS: Four-cluster classification demonstrated maximum intercluster distance. Wide, narrow, tapering, and ovoid types were described according to the intercanine and intermolar widths and their best-fit curves were depicted. No significant differences in arch depths existed among the clusters. Strong to moderate correlations were found between maxillary and mandibular arch widths. CONCLUSIONS: Lingual arch forms have been classified into 4 types based on their anterior and posterior dimensions. A template of the 4 arch forms has been depicted. Three-dimensional analysis of the lingual bracket points provides more accurate identification of arch form and, consequently, archwire selection.

New classification of lingual arch form in normal occlusion using three dimensional virtual models / 대한치과교정학회지

OBJECTIVE: The purposes of this study were 1) to classify lingual dental arch form types based on the lingual bracket points and 2) to provide a new lingual arch form template based on this classification for clinical application through the analysis of three-dimensional virtual models of normal occlusion sample. METHODS: Maxillary and mandibular casts of 115 young adults with normal occlusion were scanned in their occluded positions and lingual bracket points were digitized on the virtual models by using Rapidform 2006 software. Sixty-eight cases (dataset 1) were used in K-means cluster analysis to classify arch forms with intercanine, interpremolar and intermolar widths and width/depth ratios as determinants. The best-fit curves of the mean arch forms were generated. The remaining cases (dataset 2) were mapped into the obtained clusters and a multivariate test was performed to assess the differences between the clusters. RESULTS: Four-cluster classification demonstrated maximum intercluster distance. Wide, narrow, tapering, and ovoid types were described according to the intercanine and intermolar widths and their best-fit curves were depicted. No significant differences in arch depths existed among the clusters. Strong to moderate correlations were found between maxillary and mandibular arch widths. CONCLUSIONS: Lingual arch forms have been classified into 4 types based on their anterior and posterior dimensions. A template of the 4 arch forms has been depicted. Three-dimensional analysis of the lingual bracket points provides more accurate identification of arch form and, consequently, archwire selection.

Análise morfológica dos fissurados de lábio e palato do Centro de Tratamento de Anomalias Craniofaciais do Estado do Rio de Janeiro / Morphological analysis of patients with cleft of lip and palate from Treatment Center of Craniofacial Anomalies of Rio de Janeiro state

OBJETIVO: caracterizar o padrão oclusal e facial para diagnosticar as necessidades reabilitadoras dos fissurados de lábio e palato do Centro de Tratamento de Anomalias Craniofaciais do Estado do Rio de Janeiro. METODOLOGIA: vinte indivíduos, com fissura transforame incisivo unilateral, operados de lábio e palato, sem histórico de tratamento ortodôntico, foram avaliados, por meio de modelos de gesso superior, quanto à dimensão transversa e forma do arco superior, assim como a presença de mordidas cruzadas, com os modelos em MIH. O padrão facial, analisado por meio de fotografias de perfil, e a presença de enxerto ósseo na área da fissura, diagnosticada através de radiografias oclusais, foram também determinados. Os dados referentes à dimensão transversa foram confrontados com as médias de um grupo com oclusão normal (n=22). RESULTADOS: a comparação indicou forte atresia do arco superior associada a diferentes mordidas cruzadas na amostra fissurada. Já o padrão facial revelou clara deficiência do terço médio, enquanto o enxerto ósseo alveolar não se fez presente no processo de reabilitação. CONCLUSÃO: a atresia maxilar em associação com as mordidas cruzadas são fatos que comprovam o impacto negativo das cirurgias de lábio e palato no crescimento tridimensional da maxila. A busca pelo padrão ouro de reabilitação não será possível sem o enxerto ósseo, uma modalidade cirúrgica que confere unidade à base óssea maxilar e provê integridade ao rebordo alveolar.

AIM: To characterize the occlusion and facial pattern to diagnose the rehabilitation requirements of patients with cleft of lip and palate from Center for Treatment of Craniofacial Anomalies of Rio de Janeiro state. METHODS: A sample of 20 cleft lip and palate patients, operated of lip and palate, without orthodontic treatment were selected. The transversal dimensions and morphology of maxillary dental arches, as well as facial pattern and inherent characteristics of rehabilitation process were evaluated. Transversal dimensions were compared with a normal occlusion group (n=22). RESULTS: Data indicated transverse maxillary deficiency associated to different kinds of cross-bites in the cleft group. Facial profile shows strong tendency for maxillary hypoplasia, while alveolar bone graft was absent in the rehabilitation process. CONCLUSION: The findings suggest the impact of primary surgeries of lip and palate on the three-dimensional growing of maxilla. The gold pattern of rehabilitation cannot be reached without alveolar bone graft, a therapy that provides unity and integrity to alveolar maxillary bone.

A comparative study on crowding according to the status of the third molars in mandibular arch / 대한치과교정학회지

It has been generally believed that the impaction or eruption of mandibular third molars has significant correlations with the growth of the mandible, size of mandibular arch and size of teeth. The purpose of this study was to examine if there is any correlation between the status of eruption of mandibular third molars and the amount of mandibular crowding. The effect of missing of third moalrs to mandibular crowding was studied as well. 140 adult students of Yonsei University were selected and divided into three groups according to the status of mandibular third molars, Group 1) congenital missing group, Group 2) eruption group, and Group 3) impaction group. The tooth size, dimensions of the mandibular dental arch, and the amount of crowding were measured and compared. Results were as follows; 1. There was no statistically significant difference in tooth size between the missing group and the eruption group(p<0.05). Impaction group showed larger total tooth material, incisal tooth material, and individual tooth size except central incisors compared to missing group (p<0.05). Impaction group showed larger total tooth material, incisal tooth material compared to eruption group as well(p<0.05). When individual tooth size was compared, impaction group had larger central incisors, canines, and second premolars than eruption group(p<0.05). 2. Missing group showed larger intermolar width than impaction group and it was statistically significant(p<0.05). 3. When compared the amount of total crowding, impaction group showed the largest amount of crowding, then eruption group, and missing group showed the least amount of crowding respectively(p<0.05). There was no statistically significant difference between missing group and eruption group in the amount of incisal crowding (p<0.05). Impaction group showed the largest amount of incisal crowding among all three groups(p<0.05).