Class I malocclusion treatment: Influence of a missing mandibular incisor on anterior guidance

This case report describes the orthodontic treatment of a patient with a deep-overbite Angle Class I malocclusion, agenesis of a mandibular central incisor, and 2 supernumerary teeth, which caused impaction of the mandibular first premolars. The 15-year-old patient also had a convex profile, maxillary dentoalveolar protrusion, and deficiency of space for the correct alignment of teeth. Therefore, treatment consisted of fixed appliance therapy, cervical headgear, extraction of the supernumeraries and the mandibular and maxillary first premolars, and mesiodistal reduction of the maxillary incisors to solve the arch perimeter discrepancy as much as possible with interproximal stripping. This method of treatment significantly improved the patient`s facial and dental esthetics and provided a good functional occlusion, despite the absence of a mandibular incisor, which generally impairs achieving adequate incisal guidance. (Am J Orthod Dentofacial Orthop 2010;138:109-17)

Study of the number of occlusal contacts in maximum intercuspation before orthodontic treatment in subjects with Angle Class I and Class II Division 1 malocclusion

OBJECTIVE: Define and compare numbers and types of occlusal contacts in maximum intercuspation. METHODS: The study consisted of clinical and photographic analysis of occlusal contacts in maximum intercuspation. Twenty-six Caucasian Brazilian subjects were selected before orthodontic treatment, 20 males and 6 females, with ages ranging between 12 and 18 years. The subjects were diagnosed and grouped as follows: 13 with Angle Class I malocclusion and 13 with Angle Class II Division 1 malocclusion. After analysis, the occlusal contacts were classified according to the established criteria as: tripodism, bipodism, monopodism (respectively, three, two or one contact point with the slope of the fossa); cuspid to a marginal ridge; cuspid to two marginal ridges; cuspid tip to opposite inclined plane; surface to surface; and edge to edge. RESULTS: The mean number of occlusal contacts per subject in Class I malocclusion was 43.38 and for Class II Division 1 malocclusion it was 44.38, this difference was not statistically significant (p>0.05). CONCLUSIONS: There is a variety of factors that influence the number of occlusal contacts between a Class I and a Class II, Division 1 malocclusion. There is no standardization of occlusal contact type according to the studied malocclusions. A proper selection of occlusal contact types such as cuspid to fossa or cuspid to marginal ridge and its location in the teeth should be individually defined according to the demands of each case. The existence of an adequate occlusal contact leads to a correct distribution of forces, promoting periodontal health.

Stability and relapse of maxillary anterior crowding treatment in Class I and Class II Division 1 malocclusions

Introduction: The maxillary anterior teeth are the most important to facial esthetics because they are the first to show on a smile. Therefore, stability of the maxillary anterior teeth alignment is an important issue. The objective of this study was to compare the stability of maxillary anterior tooth alignment in Class I and Class II Division 1 malocclusions. Methods: The sample comprised dental casts of 70 patients with Class I and Class II Division 1 malocclusions and a minimum of 3 mm of maxillary anterior crowding measured by an irregularity index. The patients were treated with extractions and evaluated at pretreatment and posttreatment and at least 5 years after treatment. The sample was divided into 3 groups: group 1, Class I malocclusion treated with 4 first premolar extractions comprising 30 subjects, with an initial age of 13.16 years and 8.59 mm of initial maxillary irregularity; group 2, Class II malocclusion treated with 4 first premolar extractions comprising 20 subjects, with an initial age of 12.95 years and 11.10 mm of maxillary irregularity; and group 3, Class II malocclusion treated with 2 first maxillary premolar extractions comprising 20 subjects, with an initial age of 13.09 years and 9.68 mm of maxillary irregularity. Results: The decrease in the maxillary irregularity index was significantly greater in group 2 than in group 1 during treatment. The stability of maxillary anterior alignment was 88.12% over the long term; 77% of the linear displacement of the anatomic contact points tended to return to their original positions. Conclusions: Stability of maxillary anterior alignment between the 3 groups was similar. The stability of maxillary anterior alignment was high over the long term, but a high percentage of teeth tended to return to their original positions. (Am J Orthod Dentofacial Orthop 2011; 139: 768-74)

Longitudinal study of mandibular behavior in Class I subjects with vertical and horizontal growth

OBJETIVO: avaliar as possíveis diferenças no comportamento mandibular em indivíduos Classe I com crescimento vertical e horizontal. MÉTODOS: a amostra desse estudo consistiu de 20 indivíduos Classe I não tratados, sendo o grupo 1 composto por 10 indivíduos com padrão de crescimento vertical e o grupo 2 por 10 indivíduos com padrão de crescimento horizontal, pertencentes aos arquivos do Burlington Growth Center, University of Toronto, no Canadá, acompanhados radiograficamente nas idade de 9, 12 e 21 anos. Determinou-se, por meio de telerradiografias cefalométricas, em norma lateral, os valores médios para a avaliação longitudinal do comportamento da mandíbula utilizando as medidas SNB, Co-Gn, SN.GoMe, altura facial anterior e altura facial posterior. RESULTADOS: o valor de SNB e Co-Gn foram maiores no grupo com crescimento horizontal em todas as idades. A medida Sn.GoMe foi significativamente menor no grupo com crescimento horizontal, a altura facial anterior (AFH) apresentou valores menores nos indivíduos com padrão de crescimento horizontal, e a altura facial posterior (PFH) apresentou valores menores nos indivíduos com crescimento vertical. CONCLUSÃO: as comparações longitudinais das tendências de crescimento de indivíduos Classe I indicam que existe diferenças significativas entre os dois grupos. A mandíbula apresentou tendência à rotação horária no grupo 1. O grupo 2 exibiu tendência à característica de indivíduos braquicefálicos, na forma facial, devido ao déficit no desenvolvimento vertical na altura facial anterior.

Correction of Class II malocclusion with Class II elastics: a systematic review

Introduction: The aim of this prospective clinical study was to investigate the cephalometric changes produced by bonded spurs associated with high-pull chincup therapy in children with Angle Class I malocclusion and anterior open bite. Methods: Thirty patients with an initial mean age of 8.14 years and a mean anterior open bite of 3.93 mm were treated with bonded spurs associated with chincup therapy for 12 months. An untreated control group of 30 subjects with an initial mean age of 8.36 years and a mean anterior open bite of 3.93 mm and the same malocclusion was followed for 12 months for comparison. Student t tests were used for intergroup comparisons. Results: The treated group demonstrated a significantly greater decrease of the gonial angle, and increase in overbite, palatal tipping of the maxillary incisors, and vertical dentoalveolar development of the maxillary and mandibular incisors compared with the control group. Conclusions: The association of bonded spurs with high-pull chincup therapy was efficient for the correction of the open bite in 86.7% of the patients, with a 5.23-mm (SD, 61.69) overbite increase.

AVALIAÇÃO DA PROPORÇÃO DENTAL DE BOLTON EM INDIVÍDUOS COM OCLUSÃO NORMAL NATURAL E MALOCLUSÕES DE CLASSE I E CLASSE II DIVISÃO 1 DE ANGLE.

Introdução: A análise de Bolton, análise que quantifica o tamanho dentário, é uma referência importante para profissionais que buscam finalizações ortodônticas adequadas. Objetivo: O objetivo deste trabalho é verificar se há discrepância entre os indivíduos com oclusão normal natural e maloclusões de Classe I e de Classe II divisão 1 de Angle pertencentes a amostra selecionada, em relação aos valores encontrados por Bolton, bem como verificar também se há dimorfismo sexual. Metodologia: 3 grupos contendo 35 pares e modelos em gesso cada, separados pelo tipo de oclusão, pertencentes ao acervo do programa de pós-graduação em Ortodontia da Universidade Metodista de São Paulo foram medidos com paquímetro digital em sua maior distância mésiodistal desde 1º molar direito a 1º molar esquerdo, dos arcos superiores e inferiores, com dentição permanente. Os valores foram tabulados e a proporção de Bolton foi aplicada. Resultados: Respectivamente para os grupos 1, 2 e 3, a proporção total encontrada foi de 90,36 (DP±1,70), 91,17 (DP±2,58) e 90,76 (DP±2,45), e a proporção anterior foi de 77,73 (DP±2,39), 78,01 (DP±2,66) e 77,30 (DP±2,65). Conclusão: não houve dimorfismo sexual nem diferença estatisticamente significante comparando os valores aos sugeridos por Bolton.

Segmental LeFort I osteotomy for treatment of a class III malocclusion with temporomandibular disorder

This article reports the case of a 19-year-old young man with Class III malocclusion and posterior crossbite with concerns about temporomandibular disorder (TMD), esthetics and functional problems. Surgical-orthodontic treatment was carried out by decompensation of the mandibular incisors and segmentation of the maxilla in 4 pieces, which allowed expansion and advancement. Remission of the signs and symptoms occurred after surgical-orthodontic intervention. The maxillary dental arch presented normal transverse dimension. Satisfactory static and functional occlusion and esthetic results were achieved and remained stable. Three years after the surgical-orthodontic treatment, no TMD sign or symptom was observed and the occlusal results had not changed. When vertical or horizontal movements of the maxilla in the presence of moderate maxillary constriction are necessary, segmental LeFort I osteotomy can be an important part of treatment planning.

Lower incisor dentoalveolar compensation and symphysis dimensions among Class I and III malocclusion patients with different facial vertical skeletal patterns

Objective: To compare lower incisor dentoalveolar compensation and mandible symphysis morphology among Class I and Class III malocclusion patients with different facial vertical skeletal patterns. Materials and Methods: Lower incisor extrusion and inclination, as well as buccal (LA) and lingual (LP) cortex depth, and mandibular symphysis height (LH) were measured in 107 lateral cephalometric x-rays of adult patients without prior orthodontic treatment. In addition, malocclusion type (Class I or III) and facial vertical skeletal pattern were considered. Through a principal component analysis (PCA) related variables were reduced. Simple regression equation and multivariate analyses of variance were also used. Results: Incisor mandibular plane angle (P < .001) and extrusion (P  =  .03) values showed significant differences between the sagittal malocclusion groups. Variations in the mandibular plane have a negative correlation with LA (Class I P  =  .03 and Class III P  =  .01) and a positive correlation with LH (Class I P  =  .01 and Class III P  =  .02) in both groups. Within the Class III group, there was a negative correlation between the mandibular plane and LP (P  =  .02). PCA showed that the tendency toward a long face causes the symphysis to elongate and narrow. In Class III, alveolar narrowing is also found in normal faces. Conclusions: Vertical facial pattern is a significant factor in mandibular symphysis alveolar morphology and lower incisor positioning, both for Class I and Class III patients. Short-faced Class III patients have a widened alveolar bone. However, for long-faced and normal-faced Class III, natural compensation elongates the symphysis and influences lower incisor position.

PAR evaluation of treated Class I extraction patients

Objective: To evaluate treatment changes and quality of finishing occlusion in Class I patients treated with four premolar extractions. Material and Methods: Dental casts of 94 subjects (50 males and 44 females) were evaluated. Mean pretreatment age was 13.46 years, and mean treatment time was 2.09 years. The peer assessment rating (PAR) index was obtained from pretreatment and posttreatment dental casts. Results: The mean pretreatment PAR index of 29.46 was reduced to 6.32 at posttreatment stage, achieving a reduction of 78.54% with treatment. There was correlation between the initial PAR and correction during treatment, that is, the more severe the malocclusion the greater the treatment changes. Conclusion: The cases evaluated showed a high-standard orthodontic finishing.

Treatment stability in patients with Class II malocclusion treated with 2 maxillary premolar extractions or without extractions

Introduction: The purpose of this study was to compare the occlusal stability of Class II malocclusion treatment with and without extraction of 2 maxillary premolars. Methods: A sample of 59 records from patients with complete Class II malocclusion was used. This sample was divided into 2 groups with the following characteristics: group 1, comprising 29 patients treated without extractions, and group 2, comprising 30 patients treated with extraction of 2 maxillary premolars. Dental cast measurements were obtained before and after treatment and at a minimum of 2.4 years after treatment. The pretreatment, posttreatment, and postretention occlusal statuses were evaluated with the peer assesment rating index. The occlusal indexes at the postretention stage and the posttreatment changes and percentages of posttreatment changes were compared with t tests. Results: The nonextraction and the 2 maxillary premolar extraction treatment protocols of complete Class II malocclusions had no statistically significant differences in occlusal stability. Conclusions: Finishing Class II malocclusion treatment with the molars in a Class II relationship has similar occlusal stability as finishing with the molars in a Class I relationship. (Am J Orthod Dentofacial Orthop 2010;138:16-22)

Nonextraction treatment of a skeletal Class III malocclusion

This case report describes the nonsurgical, nonextraction therapy of a 16-year-old boy with a skeletal Class III malocclusion, a prognathic mandible, and a retrusive maxilla. He was initially classified as needing orthognathic surgery, but he and his parents wanted to avoid that. The Class III malocclusion was corrected with a rapid palatal expander and a maxillary protraction mask followed by nonextraction orthodontic treatment with fixed appliances, combined with short Class III and vertical elastics in the anterior area. The height of the maxillary alveolar process and the vertical face height were slightly increased with treatment. Class I molar and canine relationships were achieved, and the facial profile improved substantially. (Am J Orthod Dentofacial Orthop 2009; 136: 736-45)

Early cephalometric characteristics in Class III malocclusion

OBJECTIVE: Early identification of craniofacial morphological characteristics allows orthopedic segmented interventions to attenuate dentoskeletal discrepancies, which may be partially disguised by natural dental compensation. To investigate the morphological characteristics of Brazilian children with Class III malocclusion, in stages I and II of cervical vertebrae maturation and compare them with the characteristics of Class I control patients. METHODS: Pre-orthodontic treatment records of 20 patients with Class III malocclusion and 20 control Class I patients, matched by the same skeletal maturity index and sex, were selected. The craniofacial structures and their relationships were divided into different categories for analysis. Angular and linear measures were adopted from the analyses previously described by Downs, Jarabak, Jacobson and McNamara. The differences found between the groups of Class III patients and Class I control group, both subdivided according to the stage of cervical vertebrae maturation (I or II), were assessed by analysis of variance (ANOVA), complemented by Bonferroni's multiple mean comparisons test. RESULTS: The analysis of variance showed statistically significant differences in the different studied groups, between the mean values found for some angular (SNA, SNB, ANB) and linear variables (Co - Gn, N - Perp Pog, Go - Me, Wits, S - Go, Ar - Go). CONCLUSION: Assessed children displaying Class III malocclusion show normal anterior base of skull and maxilla, and anterior positioning of the mandible partially related to increased posterior facial height with consequent mandibular counterclockwise rotation.

Oral myofunctional and electromyographic evaluation of the anterior suprahyoid muscles and tongue thrust in patients with class II/1 malocclusion submitted to first premolar extraction

Objective: The aim of this study was to assess the existence of myofunctional alterations before and after first premolar extraction in Class II/1 malocclusion patients that could endanger the long-term dental arch stability. Materials and Methods: The study was performed by means of morphological, functional and electromyographic analyses in 17 Class II/1 malocclusion patients (group T) and 17 Class I malocclusion patients (group C), both groups with 12-30-year age range (mean age: 20.93 ± 4.94 years). Results: Data analyzed statistically by Student's t-test showed a significant decrease in the maxillary and mandibular dental arch perimeters after orthodontic treatment (p<0.05). The Kruskal-Wallis test analyzed data from tongue posture at rest and during swallowing, not showing significant differences after treatment (groups Tb and Ta) (p>0.05). However, group T differed significantly from group C (p<0.05). The electromyographic data showed that the anterior right and left suprahyoid muscles acted synergistically in both groups, while having a lower myoelectric activity in group T during swallowing. Conclusions: Myofunctional alterations observed after the orthodontic treatment in Class II/1 malocclusion seemed to jeopardize the long-term orthodontic stability, making recurrence possible. Further research should be conducted to compare electromyographic data before and after orthodontic treatment in order to corroborate the results of the present investigation.

Cone-beam evaluation of pharyngeal airway space in class I, II, and III patients

The purpose of this study is to make a 3-dimensional (3-D) evaluation of the pharyngeal airway space (PAS) in patients with class I, II, and III malocclusion. Sixty patients were evaluated. The patients were divided in 3 groups according to their occlusion classification. The volume and area of PAS were evaluated using the software Dolphin 3-D Imaging in the preoperative period for orthognathic surgery. PAS volume and area were influenced by different patterns of malocclusion. The mean volume and area for class III patients were statistically bigger than for classes I and II patients (P < .001). There was also a significant difference for volume values between class I and II patients, being the bigger volume for the class I patients (P < .05). It was possible to conclude that the class III patients presented a bigger PAS compared with classes I and II patients.

Evaluation of the dental arch asymmetry in natural normal occlusion and Class II malocclusion individuals

OBJECTIVE: To verify the presence and degree of asymmetry of dental arches in Brazilian individuals with natural normal occlusion and Class II, Divisions 1 and 2 malocclusions. METHODS: The study evaluated the symmetry of the maxillary and mandibular dental arches of 180 pairs of dental casts, divided into: Group I = 60 pairs of natural normal occlusion individuals; Group II = 60 pairs of Class II, Division 1 malocclusion individuals; and Group III = 60 pairs of Class II, Division 2 malocclusion individuals. A device was used to measure dental midline deviation and the canine tip in the dental arches (in degrees). It was also verified the distance of the upper canines from the palatal suture, intercanine distance, and anteroposterior upper and lower first molar position. RESULTS: Dental arches of individuals from all groups presented asymmetry, regardless of the presence of malocclusion. Group I showed a lower asymmetry degree in relation to Groups II and III. The asymmetry in Groups II and III was similar. CONCLUSION: The dental arches of individuals with natural normal occlusion and with Class II, Division 1 and Division 2 malocclusions showed asymmetry. The asymmetry degree was higher in the mandibular dental arches than in the maxillary dental arches in all 3 evaluated groups.