Influência da classe II, subdivisão, tipo 1, e das extrações assimétricas no posicionamento dos terceiros molares inferiores – relato de caso / Influence of Type 1 class II subdivision malocclusion and asymmetric extractions on mandibular third molar positioning – a case report

Este relato de caso teve como objetivo exemplificar e discutir, à luz da literatura científica, a influência da Classe II, subdivisão, tipo 1, sobre a posição dos terceiros molares inferiores, bem como avaliar o impacto das extrações assimétricas de 3 pré-molares sobre a erupção destes dentes. Previamente ao tratamento, a paciente apresentava os terceiros molares inferiores impactados, sendo que no lado da relação molar de Classe II a impacção era mais severa, provavelmente em decorrência da característica dentoalveolar determinante desta má oclusão, que é a posição mais distal do primeiro molar inferior no lado da Classe II. Após o tratamento observou-se a desimpacção do terceiro molar inferior no lado da Classe I, onde foi realizada a extração de um pré-molar. Porém, no lado oposto, onde nenhuma extração foi realizada, o terceiro molar inferior permaneceu impactado. Concluiu-se que o profissional deve atentar para a propensão da Classe II, subdivisão, tipo 1, apresentar o terceiro molar inferior no lado da Classe II em condição mais desfavorável à erupção, e que este fato, por si, não justificaria a realização de extrações simétricas de 4 pré-molares em razão da menor proporção de sucesso deste protocolo, quando aplicado à Classe II, subdivisão, tipo 1. A extração assimétrica de 2 pré-molares superiores e um pré-molar inferior no lado da Classe I pode favorecer a erupção e/ou desimpacção do terceiro molar inferior neste lado, indicando a necessidade de postergar a decisão da extração.

This case report aimed to illustrate and discuss, in the light of scientific literature, the influence of Type 1 Class II subdivision malocclusion on the positioning of the mandibular third molar and to evaluate the impact of the asymmetric extraction of 3 premolars on the eruption of that tooth. Before treatment, the patient had impacted mandibular third molars. The Class II side showed more severe impaction, probably due to the main dentoalveolar feature of this malocclusion, which is the mandibular first molar more distally positioned on the Class II side. After treatment, mandibular third molar were disimpacted on the Class I side, where premolar extraction was performed. However, in the opposite side, where no extraction was performed, the impaction of the mandibular third molar was kept unchanged. It was concluded that the professional should be aware that the Type 1 Class II subdivision malocclusion is prone to present less favorable condition for eruption of the mandibular third molar on the Class II side. Nevertheless, this fact itself could not justify making symmetric extraction of 4 premolars because this protocol presents a smaller occlusal success rate when applied to the Type 1 Class II subdivision malocclusion. In addition, asymmetric extraction of 2-maxillary premolars and a mandibular premolar on the Class I side can benefit the eruption and/or disimpaction of the mandibular third molar in this side, indicating the need to postpone the extraction decision.

Extreme Dental Compensation in an Adult Skeletal Class III Malocclusion: 3-Year Follow-up of a Successfully Compromised Treatment.

Nonsurgical orthodontic treatment of a patient with severe skeletal Class III malocclusion, negative overjet, increased overbite and maxillary crowding is described Although the treatment options included an orthodontic-surgical approach, high cost of the surgical procedure was the main reason for extreme dental compensation to have been performed. Four-premolar extraction protocol associated with intermaxillary Class III elastics were used to correct the malocclusion at the expense of increasing the initial dental compensation without producing any noticeable skeletal change. Satisfactory and stable occlusion was achieved with dental and smile esthetics improvement, but the amount of facial changes was limited by the nonsurgical protocol. The clinical results and implications of compensatory treatment as well as its relevance within the patient context are discussed based on scientific evidences.

Alterações dos arcos dentários com aparelho autoligado e convencional – um estudo controlado em typodont / Dental arch changes with self-ligating and conventional appliances – a controlled typodont study

Objetivo: comparar as alterações produzidas pelos braquetes autoligados e convencionais durante o estágio inicial de alinhamento, realizado em arcos dentários inicialmente compatibilizados. Material e métodos: dez typodonts com uma mesma má-oclusão de classe I foram igualmente distribuídos para receber braquetes autoligados e convencionais, colados em posição padronizada. As imagens digitais dos typodonts foram obtidas nas fases pré e pós-alinhamento com arcos .012" e .014" nitinol. Uma medição computadorizada foi realizada para avaliar o índice de irregularidade de Little, as dimensões transversal e sagital dos arcos, e o grau de rotação dos dentes em cada fase do experimento. A comparação dos grupos foi realizada pelo teste U de Mann-Whitney. Resultados: após o alinhamento inicial, o grau de irregularidade dos dentes foi semelhante entre os grupos. O grupo com braquete autoligado foi propenso a apresentar arcos mais largos e menor protrusão dos incisivos superiores, mas a diferença foi pequena e de significado clínico questionável. O grupo com braquetes convencionais apresentou um melhor controle da rotação dos dentes nesta fase inicial do alinhamento. Conclusão: o tipo de braquete não influenciou no grau de mudança do índice de irregularidade de Little. As diferenças estatísticas observadas nas dimensões transversal e sagital dos arcos devem ser consideradas com cautela quanto à sua significância clínica. O controle da rotação dentária com o aparelho convencional foi um pouco melhor nesta fase específica do alinhamento.

Objective: to compare the changes produced by self-ligating and conventional brackets during initial alignment stage on dental arches initially matched. Material and methods: ten typodont sets with standardized Class I malocclusion were equally divided to receive self-ligating and conventional brackets bonded in a standardized position. Digital images of the typodonts were obtained pre- and post-alignment with .012- and .014-inch archwires. Computerized measurement was performed to evaluate the Little's irregularity index, transverse and sagittal arch dimensions and tooth rotation. Groups comparison were performed with Mann-Whitney U test. Results: teeth irregularity degree was similar between the groups after initial alignment. Self-ligating group was prone to present wider arches and smaller upper incisors proclination, but the difference was small and its clinical significance is questionable. Conventional group showed a better tooth rotational control in this specific alignment phase. Conclusion: bracket type cannot predict Little's irregularity index change. Significant statistical differences in transverse and sagittal arch dimensions should be considered with caution regarding its clinical significance. Rotational control of the conventional appliance was a bit better for this specific alignment phase.

Stability of class II subdivision malocclusion treatment with 3 and 4 premolar extractions.

BACKGROUND: The purpose of this study was to compare the occlusal stability of class II subdivision malocclusion treatment with 3 and 4 first premolar extractions. A sample of 156 dental casts from 52 patients with class II subdivision malocclusion was divided into two groups according to the extraction protocol. Group 1 comprised 24 patients treated with 3 premolar extractions and group 2 included 28 patients treated with 4 premolar extractions. METHODS: Peer assessment rating (PAR) indexes were measured on the dental casts obtained before (T1) and after treatment (T2) and at a mean of 6.9 years after the end of treatment (T3). The groups were matching regarding sex distribution, pretreatment, posttreatment and long-term posttreatment ages, and treatment and long-term posttreatment times. They were also comparable concerning the initial malocclusion severity and the occlusal results at the end of treatment. Stability evaluation was calculated by subtracting the posttreatment from the long-term posttreatment index values (T3 - T2). T tests were used to compare the amount and percentage of long-term posttreatment changes. RESULTS: There were no intergroup differences regarding the amount and percentage of long-term posttreatment changes. CONCLUSION: Treatment of class II subdivision malocclusion with 3 and 4 premolar extractions have a similar long-term posttreatment occlusal stability.

Effect of recycling protocol on mechanical strength of used mini-implants.

Purpose. This study evaluated the influence of recycling process on the torsional strength of mini-implants. Materials and Methods. Two hundred mini-implants were divided into 4 groups with 50 screws equally distributed in five diameters (1.3 to 1.7 mm): control group (CG): unused mini-implants, G1: mini-implants inserted in pig iliac bone and removed, G2: same protocol of group 1 followed by sonication for cleaning and autoclave sterilization, and G3: same insertion protocol of group 1 followed by sonication for cleaning before and after sandblasting (Al2O3-90 µ) and autoclave sterilization. G2 and G3 mini-implants were weighed after recycling process to evaluate weight loss (W). All the screws were broken to determine the fracture torque (FT). The influence of recycling process on FT and W was evaluated by ANOVA, Mann-Whitney, and multiple linear regression analysis. Results. FT was not influenced by recycling protocols even when sandblasting was added. Sandblasting caused weight loss due to abrasive mechanical stripping of screw surface. Screw diameter was the only variable that affected FT. Conclusions. Torsional strengths of screws that underwent the recycling protocols were not changed. Thus, screw diameter choice can be a more critical step to avoid screw fracture than recycling decision.

Selective use of hand and forearm muscles during mini-implant insertion: a natural torquimeter.

OBJECTIVE: To compare maximum torque produced by different muscular groups and its influence on mini-implant insertion torque and fracture prevention. DESIGN: A prospective study involving in vivo and in vitro laboratory experiments. MATERIALS AND METHODS: Eighty-seven professionals were evaluated for maximum torque produced using a screwdriver with combined action between thumb and index fingers [maximum digital torque (MDT)] and by forearm supination movement [maximum brachial torque (MBT)]. Ninety mini-implants distributed over nine different diameters and twenty commercially available mini-implants of two different diameters and trademarks were fractured to determine the fracture torque (FT). The fracture resistance index (FRI) was obtained from: FRI_MDT = FT/MDT and FRI_MBT = FT/MBT. The analysis of variance (ANOVA) and t tests were used to compare the groups. RESULTS: MDT was smaller than MBT and both were smaller in females. FT increased for each 0·1 mm of diameter increment. FRI_MDT was greater than FRI_MBT for all diameters. FRI_MDT>1 was found when the diameter was greater than or equal to 1·5 mm. FRI_MBT>1 occurred with diameters equal or greater than 1·7 mm for females and 1·8 mm for males. The 1.5 mm and 1.6 mm diameter of commercially available and mini-implants presented FRI_MBT<1 and FRI_MDT>1. CONCLUSIONS: Digital torque was 42% smaller than brachial torque, and it was mechanically safer and biologically more compatible, allowing fracture prevention of 1·5 mm or thicker mini-implant diameter due to insertion torque limitation at 15 N/cm.

Uso seletivo dos músculos da mão e antebraço durante a inserção de mini-implantes: um torquímetro natural / Selective use of hand and forearm muscles during mini-implant insertion: a natural torque meter

Proposição: comparar o torque máximo produzido pelaação de dois diferentes grupos musculares e sua influência na limitaçãodo toque de inserção e prevenção à fratura dos mini-implantes. Materiale Métodos: uma amostra de 87 profissionais foi avaliada quanto àintensidade máxima do torque aplicado à chave de inserção pela açãoconjunta dos dedos polegar e indicador (torque digital máximo - TOM),e pela ação supinadora do antebraço (torque braquial máximo - TBM).Foram fraturados 90 mini-implantes igualmente distribuídos entrenove diferentes diâmetros, determinando o torque de fratura (TF). Oíndice de resistência à fratura (lRF)foi calculado a partir das relações:IRF_TOM= TF/TDM e IRF_TBM = TF/TBM. As variáveis foram comparadaspelos testes te Anova, utilizando-se um nível de significânciade 5%. Resultados: o valor de TDM foi significantemente menor queTBM, e ambos foram menores no sexo feminino. TF mostrou aumentosignificante para cada 0,1 mm de aumento do diâmetro. IRF_TOMfoi maior que IRF_TBM para todos os diâmetros de mini-implantes.Entretanto, IRF_TOM > 1 foi observado apenas para mini-implantescom diâmetro maior que 1,5 mm, enquanto IRF_TBM > 1 ocorreu apartir do diâmetro de 1,7 mm para o sexo feminino e 1,8 mm para omasculino. Conclusão: o valor médio do torque digital foi 42% menordo que o torque braquial e mostrou-se mecanicamente mais seguro ebiologicamente mais compatível, prevenindo a fratura de mini-implantescom diâmetro maior ou igual a 1,5 mm devido à limitação do torquemédio de inserção em 15 Nem.

Objective: to compare the maximum torque producedby different muscular groups and its influence on mini-implant insertiontorque and fracture prevention. Materiais and Methods: eighty-sevenprofessionals were evaluated regarding the maximum torque producedon a screwdriver by a combined action between the thumb and indexfingers (Maximum Digital Torque - MDT), and by the forearm supinationmovement (Maximum Brachial Torque - MBT). Ninety mini-implantsdistributed in nine different diameters were fractured to determine thefracture torque (FT). The fracture resistance index (FRI) was obtainedfrom: FRI_MDT = FT/MDT and FRI_MBT = FT/MBT. Anova and t testswere used to compare the groups at a significance levei of 5%. Results:the MOT was smaller than MBr, and both were smaller in female. TheFT increased for each 0.1 mm in diameter incremento The FRI_MDT wasgreater than FRI_MBT for ali the diameters. The FRI_MDT> 1was foundwhen the diameter was greater than or equal to 1.5 mm. The FRLMBT> 1occurred with diameters equal or greater than 1.7mm for femalesand 1.8 mm for males. Conclusion: the digital torque was 42% smallerthan brachial torque, and it was mechanically safer and biologicallymore compatible, allowing fracture prevention of 1.5 mm or thickermini-implant diameter due to insertion torque limitation at 15 Ncm.

Versatility and benefits of mini-implants for vertical and sagittal anchorage in a growing open bite class II patient.

This case report presents the details of a growing patient with a class II malocclusion, anterior open bite, and posterior crossbite, where the side effects of treatment mechanics were significantly reduced by the use of mini-implants for anchorage.

Influência do diâmetro do mini-implante no risco de fratura e na eficácia de autoperfuração / Mini-implant diameter influence on fracture risk and self-drilling efficacy

Proposição: avaliar a influência do diâmetro do mini-implante sobre o risco de fratura e a eficácia de autoperfuração. Material e Métodos: uma amostra padronizada de 405 mini-implantes com diâmetros de 1,2; 1,3; 1,4; 1,5; 1,6; 1,7; 1,8; 1,9 e 2 mm foi utilizada. Dez mini-implantes de cada diâmetro foram inseridos em osso artificial, enquanto 25 foram inseridos em osso de animal para avaliar o torque de inserção (TI) e a carga axial deinserção (CAI), a qual é representativa da eficácia da autoperfuração. A fratura de dez miniimplantes de cada diâmetro determinou o torque de fratura (TF). Os diferentes diâmetros de mini-implantes foram comparados quanto ao TI, TF e CAI. Em seguida, estas variáveis foramcorrelacionadas ao diâmetro. O risco de fratura em cada diâmetro foi avaliado pelo índice de resistência à fratura (lRF = TF/TI x (TF-TI)).A variação do TI durante os procedimentos de inserção foi correlacionada à variação da CAI. Resultados: apenas TI e TF mostraram diferença significante para todas as variações do diâmetro. O TI e o TF apresentaram forte correlação com o diâmetro, enquanto a CAIapresentou correlação de fraca a moderada. O IRFfoi notoriamente maior para cada 0,1 mm de aumento do diâmetro. Durante os procedimentos de inserção, o TI aumentou significantemente enquanto a CAI diminuiu progressivamente.Conclusão: o aumento do diâmetro do mini-implante influenciou significantemente o aumento de TI e TF em quantidades que reduziram progressivamente o risco de fratura. A eficácia da autoperfuração não foi fortemente influenciada pelo diâmetro.

Objectives: this study evaluated the mini-implant diameter influence on fracture risk and self-drilling etticacy. Material and Methods: a standardized sample composed by four hundred five mini-implants with diameter of 1.2; 1.3; 1.4; 1.5; 1.6; 1.7; 1.8; 1.9 and 2mm was used. Ten mini-implants of each diameter were inserted in artificial bone, while 25were inserted in animal bone to evaluate insertion torque (IT) and axial insertion load (AIL), which is representa tive of self-drilling etticacy. The intentional fracture of ten mini-implants foreach diameter determined the fracture torque (FT). The different diameters were compared regarding IT, FT and AIL. The fracture risk of each diameter was evaluated by fracture resistance index (FRI = FTIIT x (FT-IT)). The IT and AIL changes during insertion procedurewere correlated. Results: only IT and FT were significantly different for ali mini-implant diameter changes. The IT and FT showed a strong correlation with the mini-implant diameter, while theAIL was weakly to moderately correlated. The FRI was notoriously greater for each 0.1mm added in diameter. The IT increased significantly, while the AIL was progressively reducedduring insertion procedures. Conclusions: the increase in mini-implant diameter significantly influenced the IT and FT increase on quantities that progressively reduced the fracture risk. The self-drilling eiiicecv, represented by AIL, was not strongly influenced by mini-implant diameter.

Predictable drill-free screw positioning with a graduated 3-dimensional radiographic-surgical guide: a preliminary report.

INTRODUCTION: Mini-implants are placed in restricted sites, requiring an accurate surgical technique. However, no systematic study has quantified technique accuracy to reliably predict the surgical risks. Therefore, a graduated 3-dimensional radiographic-surgical guide (G-RSG) was proposed, and its inaccuracy and risk index (RI) were estimated. METHODS: The sample consisted of 6 subjects (4 male, 2 female), who used mini-implant anchorage. Ten drill-free screws (DFS) were placed by using the G-RSG. The central point of the mesiodistal septum width (SW) was the selected implant site on the presurgical radiograph. The distances between DFS and the adjacent teeth (5-DFS and 6-DFS) were measured to evaluate screw centralization and inaccuracy degree (ID). These distances were statistically compared by independent t tests, and inaccuracy was determined by the expression ID = (5-DFS - 6-DFS)/2, which represents deviation of the mini-implant's final position regarding the central point initially selected. Then SW, ID, and screw diameter (SØ) were combined to estimate the surgical risk with RI expressed by RI = SØ/SW - ID. RESULTS: The 5-DFS and 6-DFS distances were not significantly different. The ID of the G-RSG was 0.17 mm. The low ID ensured a safe RI (<1) in spite of the restricted SW. CONCLUSIONS: The G-RSG accuracy allowed fine prediction of the final DFS position in the interradicular septum, with a low RI, which is a helpful tool to estimate surgical risks.