Distalization of the entire maxillary arch with mini-implants in the posterior palatal alveolus- A case report / Distalização de todo o arco maxilar com mini-implantes na região alveolar posterior palatina - Relato de caso

A 22 year old male patient reported to the hospital with a chief complaint of forwardly placed teeth. On examination patient had Angle's Class I malocclusion and proclination of the anterior teeth. There were signs of frictional keratosis on the buccal mucosa. Treatment plan was to extract the third molars alone and distalize the entire maxillary arch with palatal mini-implants. 0.022 MBT brackets were bonded on the buccal aspect. 0.019" x 0.025" stainless steel wire was placed sequentially. Mini-implants were placed on the posterior alveolus on the palatal surface of maxilla. Retractive force was applied from an attachment bonded on the palatal aspect of the maxillary canine. Patient was reviewed periodically. Comparison of pre-treatment and post-treatment results revealed that the entire maxillary arch intruded and translated distally with a counter-clockwise rotation of the mandible with reduction in LAFH. There was a mild reduction in inter-canine with marginal expansion in the premolar and molar region. An improvement in facial profile was noted with no sign of root resorption. Thus, the posterior alveolus may be considered as a new and appropriate site for placement of mini-implant to bring about distal movement of the entire maxillary dentition (AU)

Um Paciente do sexo masculino, 22 anos, foi encaminhado ao hospital com queixa principal de dentes posicionados para a frente. Ao exame clínico o paciente apresentava má oclusão de Classe I de Angle e inclinação vestibular dos dentes anteriores. Havia sinais de queratose friccional na mucosa bucal. O plano de tratamento foi extrair os terceiros molares e distalizar todo o arco maxilar com mini-implantes por palatino. Bráquetes MBT 0,022 foram colados por vestibular. Fio de aço inoxidável 0,019 "x 0,025" foi colocado seqüencialmente. Mini-implantes foram instalados na região alveolar posterior da superfície palatina da maxila. A força de retração foi aplicada a partir de acessórios colados nas faces palatinas dos caninos superiores. O paciente foi reavaliado periodicamente. Os resultados da comparação pré-tratamento e pós-tratamento revelaram que todo o arco maxilar intruiu e transladou distalmente com rotação da mandíbula no sentido anti-horário com redução da AFAI. Houve uma ligeira redução na distância intercanina com expansão marginal nas regiões de pré-molar e molar. Foi percebida melhora no perfil facial sem sinal de reabsorção radicular. Assim, a região alveolar posterior pode ser considerada como um novo e apropriado local para instalação de mini-implante para promover movimento distal de toda a dentição maxilar. (AU)

Quantification of intrusive/retraction force and moment generated during en-masse retraction of maxillary anterior teeth using mini-implants: A conceptual approach

ABSTRACT Objective: The aim of the present study was to clarify the biomechanics of en-masse retraction of the upper anterior teeth and attempt to quantify the different forces and moments generated using mini-implants and to calculate the amount of applied force optimal for en-masse intrusion and retraction using mini-implants. Methods: The optimum force required for en-masse intrusion and retraction can be calculated by using simple mathematical formulae. Depending on the position of the mini-implant and the relationship of the attachment to the center of resistance of the anterior segment, different clinical outcomes are encountered. Using certain mathematical formulae, accurate measurements of the magnitude of force and moment generated on the teeth can be calculated for each clinical outcome. Results: Optimum force for en-masse intrusion and retraction of maxillary anterior teeth is 212 grams per side. Force applied at an angle of 5o to 16o from the occlusal plane produce intrusive and retraction force components that are within the physiologic limit. Conclusion: Different clinical outcomes are encountered depending on the position of the mini-implant and the length of the attachment. It is possible to calculate the forces and moments generated for any given magnitude of applied force. The orthodontist can apply the basic biomechanical principles mentioned in this study to calculate the forces and moments for different hypothetical clinical scenarios.

RESUMO Objetivo: o objetivo do presente estudo foi explicar o funcionamento da biomecânica de retração em massa dos dentes anterossuperiores e tentar quantificar as diferentes forças e momentos gerados ao se usar mini-implantes, além de calcular a quantidade ideal de força a ser aplicada para se obter a intrusão/retração em massa ancorada em mini-implantes. Métodos: a força ideal necessária para se realizar a intrusão/retração em massa pode ser calculada por meio de fórmulas matemáticas simples. Dependendo da posição do mini-implante e da posição do acessório, a ele conectado, com relação ao centro de resistência do segmento anterior, obtêm-se desfechos clínicos diferentes. Aplicando certas fórmulas matemáticas, pode-se calcular com precisão a magnitude da força e do momento gerado nos dentes, para cada desfecho clínico. Resultados: a força ideal para se obter a intrusão/retração em massa dos dentes anterossuperiores é de 212 gramas por lado. A força aplicada em um ângulo de 5° a 16° em relação ao plano oclusal produz componentes de força de intrusão/retração que se encontram dentro dos limites fisiológicos. Conclusão: podem ser encontrados diferentes desfechos clínicos dependendo da posição do mini-implante e do comprimento do acessório. É possível calcular as forças e os momentos gerados para qualquer magnitude de força aplicada. Assim, o ortodontista clínico pode aplicar os princípios biomecânicos básicos apresentados nesse estudo para calcular as forças e os momentos em diferentes cenários clínicos hipotéticos.

Determination of craniofacial relation among the subethnic Indian population: A modified approach (vertical evaluation).

Aim: To measure the vertical linear cephalometric dimensions of the anterior and posterior segments of the craniofacial complex and establish ratios between vertical linear dimensions in subjects with normal occlusion, pleasing profile, and facial harmony. Setting and Sample Population: Department of Orthodontics, Saveetha University. Lateral cephalograms of 120 subjects of both sexes in the age group of 17-28 years with normal occlusion belonging to Chennai, India. Materials and Methods: The vertical segments measured are anterior maxilla, posterior maxilla, and ramus-cranial floor vertical. The facial heights were measured in the anterior and posterior region of the craniofacial complex. Establish ratios and proportions between the vertical segments and different facial heights. Results: In both the sexes, the ratio between anterior maxilla, posterior maxilla, and ramus-cranial floor vertical is 1:1:1, PTFH:ATFH is 1:1, AUFH:ATFH is 2:5, ALFH:ATFH is 3:5, PUFH:PTFH is 1:2, PLFH:PTFH is 1:2, AUDH:ALDH is 2:3, and facial depth is 2:1. PUDH:PLDH is 7:9 in females and 3:4 in males. There was a statistically significant difference in posterior total facial height:anterior total facial height ratio between the two sexes with a "P" value of 95%. Conclusion: Thus, the anterior maxilla, posterior maxilla, and cranial floor-ramus vertical composite are in dimensional balance in subjects with normal occlusion and facial harmony. This analysis helps to identify skeletal deviations in size and position in the vertical dimension and allows the clinician to outline an appropriate treatment.

Determination of craniofacial relation among the subethnic Indian population: A modified approach - (Sagittal relation).

Aim : To measure the linear cephalometric dimensions of anterior and posterior segments of the craniofacial complex sagittally, to establish ratios between different linear dimensions of sagittal segments and check for dimensional balance among the various segments in subjects with normal occlusion, pleasing profile and facial harmony. Setting and Sample Population : Department of Orthodontics, Saveetha University. Lateral cephalograms of 120 subjects of both sexes in the age group of 17-28 years with normal occlusion belonging to Chennai, India Materials and Methods : Linear dimensions of anterior and posterior segments of the craniofacial complex were measured sagittally with the posterior maxillary plane as a key reference plane. Ratios were established between the various parameters in the anterior and posterior region. Results : A ratio of 1:1 was found to exist between the individual and aggregate sagittal segments of the craniofacial complex in both sexes. There was a statistically significant sexual dimorphism in the aggregate lengths(P=0.028,P=0.005).However, the ratio between the anterior cranial floor and effective maxillary length was 2:3 and 5:8 and that between anterior cranial floor to effective mandibular length was 5:8 and 3:5 in females and males respectively. The difference in the above values was not statistically significant. Conclusion : A dimensional balance was found to exist between the maxilla and mandible both at the dentoalveolar and skeletal level with a ratio of 1:1. There was also a dimensional balance between the posterior cranial floor and ramus width. However, there was no architectural balance between the anterior cranial floor and maxilla and mandible.