A machine learning approach to determine the prognosis of patients with Class III malocclusion.

INTRODUCTION: The conundrum of determining how to treat a patient with Class III malocclusion is significant, creating a burden on the patient and challenging the orthodontist. The objective of this study was to employ a statistical prediction model derived from our previous cephalometric data on 5 predominant subtypes of skeletal Class III malocclusion to test the hypothesis that Class III subtypes are associated with treatment modalities (eg, surgical vs nonsurgical) and treatment outcome. METHODS: Pretreatment lateral cephalometric records of 148 patients were digitized for 67 cephalometric variables, and measurements were applied to a mathematical equation to assign a Class III subtype. Subjects were assigned to either a surgical or nonsurgical group depending on the treatment received. Treatment outcome was determined by facial profile and clinical photographs. Log binomial models were used for statistical analysis. RESULTS: Subtype 1 (mandibular prognathic) patients were 3.5 × more likely to undergo orthognathic surgery than subtypes 2/3 (maxillary deficient) and 5.3 × more likely than 4/5 (combination). Subtype 1 patients were also 1.5 × more likely to experience treatment failure than subtypes 2/3 (maxillary deficient) and 4/5 (combination). CONCLUSIONS: This assessment of a systematic method to characterize patients with Class III malocclusion into subtypes revealed that subtype 1 (mandibular prognathic) showed a likelihood to undergo orthognathic surgery while subtypes 2/3 experienced significantly lower treatment failure (in response to orthodontics alone). Further refinement of the equation may yield a reliable prediction model for earlier identification of surgical patients and also provide predictive power of Class III treatment outcomes.

An interview with Sylvia Frazier-Bowers.

Dr. Frazier-Bowers is an associate professor at the University of North Carolina, Chapel Hill (UNC-CH), in the Department of Orthodontics. She received a BA from the University of Illinois, Urbana-Champaign, and a DDS from the University of Illinois, Chicago. After completing the NIH Dentist-Scientist Program at UNC-CH in Orthodontics (Certificate, 97') and Genetics and Molecular Biology (PhD, 99'), she completed a post-doctoral fellowship at the University of Texas Health Science Center, Houston (UTHSC), in the Department of Orthodontics. Leadership positions include president of local NC-AADR (North Carolina (2005-2006); director of the AADR Craniofacial Biology group (CBG) 2004-2007; IADR/AADR councilor for NC-AADR (2007, 2008, 2012) and for the CBG (2012-2015); member of Southern Association of Orthodontists Scientific Affairs Committee (2005-2013) and the American Association of Orthodontists Council on Scientific Affairs (2014 ­ Present). Dr. Frazier-Bowers also serves various editorial boards including the Journal of Dental Research and the Scientific Advisory board for the Consortium on Orthodontic Advances in Science and Technology. Her current role as faculty at UNC-CH includes conducting human genetic studies to determine the etiology of inherited tooth disorders, mentoring students at all levels, teaching graduate and pre-doctoral level Growth and Development courses and treating patients in the UNC School of Dentistry faculty practice in Orthodontics.

Orthodontic and surgical treatment of a patient with hemifacial microsomia.

This article describes the surgical and orthodontic treatment of a 12-year-old boy with a significant deformity and functional involvement caused by hemifacial microsomia. The left mandibular ramus and condyle were hypoplastic and abnormal in form and location. The lower third of the face was increased, with mandibular retrusion and significant facial asymmetry. He had difficulties in speaking and chewing and problems related to his facial appearance, which caused severe psychosocial disturbances. The patient received orthodontic treatment and temporomandibular joint reconstruction with a costochondral graft on the left side while he was still growing. Three-year follow-up records are presented.

Is traditional treatment a good option for an adult with a Class II deepbite malocclusion?

The Tweed-Merrifield directional force technique is a useful treatment approach for a patient with a Class II malocclusion with dentoalveolar protrusion. The purpose of this case report was to present the diagnosis and treatment descriptions of a patient with an Angle Class II malocclusion complicated by tooth losses, severe dentoalveolar protrusion, and skeletal discrepancy. Treatment involved extraction of the maxillary first premolars, high-pull headgear to enhance anchorage, and high-pull J-hook headgear to retract and intrude the maxillary anterior segments. A successful outcome was achieved with traditional orthodontic treatment in this borderline surgical case.

Class III camouflage using skeletal anchorage and Pendex appliance.

This case report describes the orthodontic treatment for a young female, aged 18 years 4 months, with a Class III malocclusion on the right side, with a combination of a posterior and anterior crossbite. Two rigid orthodontic mini-implants were placed in the retromolar region in order to move the entire lower arch distally with nickel-titanium coil springs. In addition, a Pendex appliance was used to create space and to improve the arch form and the transverse relationship. The active treatment period was 17 months. Normal overjet and overbite were obtained, and facial balance was improved. Although the cephalometric superimposition has demonstrated the effects of dental compensation, the final dental and facial results were satisfactory and stable after the second year in retention.

Caracterização fenotípica dos pacientes Classe III: avaliação de um novo modelo estatístico para diagnóstico e predição dos resultados do tratamento / Phenotypic characterization of Class III patients: evaluation of a novel statistical model for diagnosis and prediction of the treatment outcomes

A maloclusão de Classe III é um dos problemas mais desafiadores aos ortodontistas, especialmente no que diz respeito à elaboração de um correto diagnóstico e de um plano de tratamento adequado. Intervenções ortopédicas precoces têm sido defendidas para pacientes com esse tipo de problema. No entanto, muitos pacientes que foram tratados com sucesso em uma idade precoce sofreram recidiva durante o crescimento subsequente. O prognóstico destes pacientes pode ser melhor estabelecido se for possível identificar e aplicar clinicamente medidas cefalométricas que possam predizer o padrão de crescimento e o potencial de crescimento final. Além disso, uma caracterização completa de indivíduos Classe III esquelética e uma futura correlação com fatores genéticos podem representar uma grande promessa para a ortodontia. Este trabalho teve como objetivo, portanto, aplicar e validar um novo método diagnóstico de classificação, o modelo estatístico de predição para pacientes Classe III (MEP3), a fim de testar a hipótese de que diferentes tipos de Classe III podem ser mais reprodutivelmente diagnosticados com a utilização de uma equação matemática, quando comparado à perspicácia clínica de cada ortodontista. Também se investigou a correlação entre os subgrupos de Classe III provenientes do MEP3 e os resultados do tratamento para estabelecer quais variáveis cefalométricas são capazes de predizer o sucesso do tratamento destes pacientes. Assim, o diagnóstico fornecido pelo MEP3 foi comparado ao de 3 ortodontistas experientes, em uma amostra de 600 pacientes Classe III. Os resultados do estudo revelaram que, quando comparado à acuidade clínica individual dos ortodontistas, o MEP3 oferece uma solução de diagnóstico mais precisa e reprodutível. Em uma amostra de 131 pacientes, o MEP3 identificou cinco subgrupos de Classe III. O Teste exato de Fischer mostrou uma relação estatisticamente significativa entre estes subgrupos e o tipo de tratamento realizado nestes pacientes, sendo que pacientes pertencentes aos subgrupos 2 e 3 (deficiência de maxila) foram mais propensos a serem tratados pela camuflagem ortodôntica sem extrações dentárias. A Análise de Significância para Microarranjos mostrou que existem variáveis cefalométricas específicas diretamente ligadas a determinados subgrupos de maloclusão de Classe III. O método de Discriminação Ponderada da Distância MultiClasses Esparsas e o teste de Permutação-Direção-Projeção Multiclasses revelaram que algumas medidas cefalométricas pré-tratamento estão fortemente associadas ao: tipo de tratamento realizado nos pacientes (ângulo interincisal, ângulo goníaco e relação de Holdaway); sucesso do tratamento (relação de Holdaway, inclinação dos incisivos superiores em relação à base craniana anterior e grau de protrusão dos incisivos inferiores); e à estabilidade (ângulo interincisal, diferença de comprimento da unidade maxilo-mandibular e inclinação dos incisivos superiores em relação à base craniana anterior). Os resultados deste estudo forneceram uma ferramenta sistemática para diagnosticar a maloclusão de Classe III e podem ajudar em análises genéticas futuras, como a genotipagem e os estudos de ligação, que exigem fenotipagem rigorosa.

Class III malocclusion is one of the most challenging of the malocclusion classifications to manage. Specifically, the development of an optimal diagnosis and treatment plan is difficult. Early orthopedic interventions have been advocated for skeletal Class III patients. However, many patients that are treated successfully at an early age experience relapse during subsequent growth. The prognosis of such patients can be greatly enhanced if accurate predictors of growth pattern and ultimate growth potential are identified and applied clinically. Moreover, a complete characterization of skeletal Class III individuals and future correlation with specific genetic factors holds great promise for the orthodontic specialty. The aim of this study is therefore to validate and apply a novel classification method, the statistical prediction model for Class III patients (SPM3), to test the hypothesis that distinct Class III subtypes can be more reproducibly diagnosed using a mathematical predictive model when compared to the clinical acumen of an individual orthodontist. We also aim to investigate the relationship between the clusters from the SPM3 and treatment outcomes to establish which cephalometric variables are predictive for successful treatment of Class III patients. Thus, the diagnosis provided by MEP3 was compared to the diagnosis of three experienced orthodontists in a sample of 600 Class III patients. The results of this first part of the study revealed that when compared to the clinical acumen of individual orthodontists, the MEP3 provides a more accurate and reproducible diagnostic solution. In a sample of 131 patients, MEP3 identified five clusters of Class III. Fischer exact test showed a significant statistical relationship between the 5 clusters and the modality of treatment performed in those patients, and patients of clusters 2 and 3 (maxillary deficients) were more likely to be treated by orthodontic camouflage without extractions. Significance Analysis of Microarrays indicated that some pre-treatment cephalometric variables are highly associated with specific clusters of Class III malocclusion. The Sparse Multiclass Distance Weighted Discrimination method and the Multiclass Direction-Projection-Permutation test indicated revealed some pre-treatment cephalometric variables highly associated with: treatment modality (interincisal angle, gonial angle and Holdaway ratio); treatment success (Holdaway ratio, inclination of upper incisors with S-N plane and lower incisors protrusion); and stability (interincisal angle, maxillo-mandibular unit length difference, and inclination of upper incisors with S-N). The findings from this study provided a systematic tool to diagnose Class III malocclusion and can aid in future genetic analyses, such as genotyping and linkage studies, which require rigorous phenotyping.

Tracionamento de incisivo central superior impactado / Traction of impacted maxillary central incisor

A impacção dentária representa um desafio ao cirurgião-dentista, especialmente quando essa envolve dentes anteriores, devido à grande preocupação estética por parte dos pacientes. Os dentes podem se encontrar impactados por uma série de fatores etiológicos, incluindo a falta de espaço na arcada dentária; a presença de elementos supranumerários, cistos ou tumores; o posicionamento ectópico do germe dentário, entre outros; o que pode levar a uma má-oclusão dentária. Este artigo descreve o tracionamento ortodôntico-cirúrgico de um incisivo central superior impactado em um indivíduo do sexo masculino de 11 anos de idade. A sequência do tratamento, desde a abertura de espaço na arcada dentária superior à exposição cirúrgica da coroa e ao tracionamento do elemento impactado mostrou a importância do correto diagnóstico e planejamento e – sobretudo – de uma abordagem multidisciplinar, o que levou a um resultado bastante satisfatório, com excelente resposta à mecânica utilizada.

Dental impaction represents a challenge to the general dentist, especially when it involves anterior teeth, due to the great esthetic concern of the patients. Teeth may be impacted due to númerous etiological factors, including lack of space in the dental arch, the presence of supranumerary teeth and ectopic positioning of the dental germ, which can lead to malocclusion. This article describes the surgical-orthodontic traction of an impacted maxillary central incisor in a male patient aged 11 years. The sequence of treatment, since the opening of space in the upper dental arch to the surgical exposure of the crown and the traction of the impacted teeth showed the importance of correct diagnosis and planning and of a multidisciplinary approach, which led to a very satisfactory result with excellent response to the mechanics.