ABSTRACT
Objective@#Exploring the position and bone wall thickness characteristics of the maxillary central incisors in Southern Chinese adults to provide a clinical reference for the design of immediate maxillary central incisor implantation surgery.@*Methods@#The hospital ethics committee approved the study, and the patients provided informed consent. CBCT images of 990 adult patients (aged 20-79 years) from the Stomatology Hospital (January 2018 to December 2021) were categorized based on the dental arch form and age-sex groups. Sagittal CBCT images of the maxillary central incisors were used to measure the labial and palatal bone thickness wall at 4 mm the CEJ to apical, the middle of the root, and the angle between the tooth long axis and the long axis of the alveolar process, to compare the thickness of the labial and palatal bone walls in samples of male and female patients, and to explore the relationship between the angle between the tooth long axis and the alveolar process long axis in samples of male and female patients in different age groups (20-39 years; 40-59 years; 60-79 years).@*Results@#Significant differences were found in the labiopalatine side of the alveolar bone of the maxillary incisor root position. A total of 95.8% (948/990) of the maxillary incisors were positioned more buccally, 4.1% (41/990) were positioned more midway, and 0.1% (1/990) were positioned more palatally. The thicknesses of the bone wall at the CEJ of 4 mm below the palatal side, the middle of the root, and at the apex were greater (1.82 ± 0.56 mm, 3.20 ± 1.10 mm, and 7.70 ± 2.00 mm, respectively) than those at the labial side (1.21 ± 0.32 mm, 0.89 ± 0.35 mm, and 1.86 ± 0.82 mm, respectively), with statistical significance (P<0.05). Male bone wall thickness was generally greater than female bone wall thickness (P<0.05). The angle between the long axis of male teeth and the alveolar bone was 14.77° ± 5.66°, while that of female teeth was 12.80° ± 5.70°, with a statistically significant difference (P<0.05). The angle between the long axis of teeth and the alveolar bone in the 40-59-year-old group and the 60-79-year-old group was greater than that in the 20-39-year-old group, and the difference was statistically significant (P<0.05).@*Conclusion@#A total of 95.8% of adults in South China have maxillary central incisors with root deviation toward the labial bone cortex. The thickness of the labial bone wall is much thinner than that of the labial bone wall, which is the middle of the thickness of the root. In Southern Chinese adults, the angle between the upper central incisor and the long axis of the alveolar bone in males is greater than that in females, and the degree of the angle increases with age. It is recommended to pay attention to the thickness of the bone wall around the root and the angle between the teeth before immediate implantation surgery to choose a reasonable implantation plan.
ABSTRACT
Objective@# To study the remodeling of alveolar bone after retraction of the maxillary incisors assisting with micro-implant anchorage in adult patients with maxillary protrusion by CBCT.@*Methods@#Forty patients who were treated with extraction of the maxillary first premolars with microimplant anchorage meeting the inclusion criteria were selected. The CBCT data before and after treatment were collected, and the Dolphin Imaging 3D measurement software was used to measure and analyze the height and thickness of the alveolar bone of the 80 upper central incisors and the 80 lateral incisors.@*Results @#After retraction of the incisors assisting with microimplant anchorage, the labial alveolar bone height of the maxillary central incisors decreased (0.11 ± 0.33) mm, and the lingual alveolar bone height of the maxillary central incisors decreased (0.85 ± 1.23) mm. The labial alveolar bone height of the maxillary lateral incisors decreased (0.18 ± 0.42) mm, and the lingual alveolar bone height of the maxillary lateral incisors decreased (1.13 ± 1.14 ) mm. The reduction in the lingual alveolar bone height was greater than that of the labial side, and the difference was statistically significant (P < 0.05). The labial alveolar bone thickness of the maxillary central incisors increased (the root cervix, the root media and the root apex), and the difference was statistically significant (P < 0.001). The labial alveolar bone thickness of the maxillary lateral incisors also increased (P < 0.05), while the lingual alveolar bone thickness and the total alveolar bone thickness of the maxillary central and lateral incisors decreased (P < 0.001). @*Conclusion@#In adults with maxillary protrusion, the microimplant was used to assist the reduction of the anterior teeth. The alveolar bone height of the maxillary incisors was reduced, and the palatal alveolar bone height decreased more than that of the labial side. The alveolar bone of the labrum was thickened, and the palatal alveolar bone thickness and the total alveolar bone thickness of the maxillary incisors were reduced after treatment.
ABSTRACT
O presente estudo propôs avaliar, cefalometricamente, a alteração do ponto A no plano sagital após mudança na inclinação dos incisivos superiores. Métodos: 21 pares de telerradiografias tomadas, no início e no final do tratamento ortodôntico, foram coletados de uma clínica particular na cidade de Aracaju (SE). A amostra foi dividida em dois grupos, de acordo com a movimentação dos incisivos pós-tratamento: Ipro, onde os incisivos proclinaram (n=12); e Iretro, onde os incisivos retroinclinaram (n=9). O ponto A e a inclinação dos incisivos maxilares foram mensurados em relação às linhas ortogonais formadas pelo plano horizontal de Frankfurt e pelo plano pterigoideo vertical. Todos os dados foram medidos duas vezes, com um intervalo de 15 dias, e as médias foram submetidas ao teste t emparelhado e ao teste de correlação de Pearson. Resultados: quando os incisivos maxilares proclinaram 5,26°, o ponto A retraiu 1,54 mm (r=0,75; p < 0,0001), em uma taxa de 1:3,4 mm/graus. Quando os incisivos maxilares retroinclinaram 5,44º, o ponto A avançou 0,71 mm (r=0,81; p < 0,05), em uma taxa de 1:7,7 mm/graus. Conclusão: o ponto A é influenciado diretamente pela alteração na inclinação dos incisivos superiores e tende a acompanhar o movimento do ápice destes dentes.
This study aims to cephalometrically evaluate the changes at point A on the sagittal plane by measuring dental incisor inclinations before and after treatment. Methods: a total of 21 pairs of pre- and post-treatment lateral cephalograms were collected from a private clinic in Aracaju (SE). The sample was divided into 2 groups according to incisors inclination after treatment: Ipro, proclination after treatment (n=12) and Iretro: retroclination after treatment (n=9). The point A and the maxillary incisor inclinations were measured in relation to the orthogonal lines formed between the Frankfurt horizontal and the pterygoid vertical planes. Data were measured twice within a fifteen day interval, and means were subjected to the paired t and Pearson's correlation tests. Results: when maxillary incisors proclined 5.26° degrees, point A retracted 1.54 mm (r=0.75; p < 0.0001), establishing a ratio of 1:3.4 mm/degrees. When the maxillary incisors retroclined 5.44 degrees, the point A advanced 0.71 mm (r=0.81; p < 0.05), establishing a ratio of 1:7.7 mm/degrees. Conclusion: the point A is directly affected by changes in the upper incisor inclinations and tends to follow the apex movement of these teeth.