Evaluation of the posterior maxillary teeth movements during Class II correction: 3-dimensional superimposition of casts.

AIM AND OBJECTIVES: The aim of this study was to analyze the changes of the posterior dentition during Class II correction with the crown Herbst appliance (cHerbst) and intermaxillary Class II elastics. SAMPLE: Class II patients were divided into 2 groups: those who were treated with the cHerbst appliances (n=40, mean age 14.1±1.3) and those who were treated with fixed appliances and Class II elastics (n=20, mean age 16.7±2.7). MATERIALS AND METHODS: The scans of pre- and post-treatment casts the patients were superimposed and registered using the freeware Blender 2.67. The linear measurements in the anteroposterior, transversal and vertical planes along with the rotation angles of the first molars were assessed. RESULTS: In the cHerbst group clinically significant derotation (13.8±5.0°) and distalization (3.2±1.2 mm) of the upper first molars were recorded compared to the intermaxillary Class II elastics group (4.2±5.5°, -0.3±1.5, respectively). In the cHerbst group the second and first premolars followed the distal movements of the upper first molars. The premolars expanded slightly more than the molars in both groups. The posterior teeth extruded in both groups, except the molars in the cHerbst group. CONCLUSIONS: The crown Herbst appliance is significantly more effective in molar derotation and distalization than intermaxillary Class II elastics.

Digital platform for planning facial asymmetry orthodontic-surgical treatment preparation.

Dentofacial deformities usually are surgically treated, and 3D virtual planning has been used to favor accurate outcomes. Cases reported in the present article show that orthognathic surgery carried out to correct facial asymmetries does not comprise only one treatment protocol. 3D virtual planning might be used for surgical planning, but it should also be used to diagnose the deformity, thus allowing for an analysis of the best-recommended possibilities for the orthodontic preparation that suits each individual case.

Digital platform for planning facial asymmetry orthodontic-surgical treatment preparation

ABSTRACT Dentofacial deformities usually are surgically treated, and 3D virtual planning has been used to favor accurate outcomes. Cases reported in the present article show that orthognathic surgery carried out to correct facial asymmetries does not comprise only one treatment protocol. 3D virtual planning might be used for surgical planning, but it should also be used to diagnose the deformity, thus allowing for an analysis of the best-recommended possibilities for the orthodontic preparation that suits each individual case.

RESUMO As deformidades dentofaciais são, geralmente, tratadas de forma cirúrgica, e o planejamento virtual 3D tem sido utilizado para aumentar a precisão dos resultados. Os casos exemplificados no presente artigo mostram que a cirurgia ortognática para correção das assimetrias faciais não apresenta um único protocolo de tratamento. O planejamento virtual 3D pode ser adotado para planejar a cirurgia, mas também deve ser utilizado na fase de diagnóstico da deformidade, assim permitindo uma análise das possibilidades mais indicadas para o preparo ortodôntico mais adequado em cada caso.

Aspartate aminotransferase activity in the pulp of teeth treated for 6 months with fixed orthodontic appliances.

OBJECTIVE: To measure aspartate aminotransferase (AST) activity in the pulp of teeth treated with fixed appliances for 6 months, and compare it with AST activity measured in untreated teeth. METHODS: The study sample consisted of 16 healthy subjects (mean age 25.7 ± 4.3 years) who required the extraction of maxillary premolars for orthodontic reasons. Of these, 6 individuals had a total of 11 sound teeth extracted without any orthodontic treatment (the control group), and 10 individuals had a total of 20 sound teeth extracted after 6 months of orthodontic alignment (the experimental group). Dental pulp samples were extracted from all control and experimental teeth, and the AST activity exhibited by these samples was determined spectrophotometrically at 20℃. RESULTS: Mean AST values were 25.29 × 10(-5) U/mg (standard deviation [SD] 9.95) in the control group and 27.54 × 10(-5) U/mg (SD 31.81) in the experimental group. The difference between these means was not statistically significantly (p = 0.778), and the distribution of the AST values was also similar in both groups. CONCLUSIONS: No statistically significant increase in AST activity in the pulp of mechanically loaded teeth was detected after 6 months of orthodontic alignment, as compared to that of teeth extracted from individuals who had not undergone orthodontic treatment. This suggests that time-related regenerative processes occur in the dental pulp.

Mechanisms of Class II correction induced by the crown Herbst appliance as a single-phase Class II therapy: 1 year follow-up.

BACKGROUND: The objective of this study is to evaluate the skeletal and dentoalveolar effects of the crown Herbst appliance used alone for a single phase of therapy followed by a 1-year observation period. METHODS: Forty patients (mean age 13.6±1.3 years) with a stable Class I occlusion 1 year following the treatment with the crown Herbst appliance were selected from a prospective sample of 180 consecutively treated Class II patients. No other appliances were used during treatment or during the follow-up period. The dentoskeletal changes were compared with a matched sample of untreated Class II subjects (mean age 13.9±1.6 years). Lateral cephalograms were taken before treatment, after Herbst treatment (1 year), and after 1-year follow-up. Overcorrection was avoided intentionally. RESULTS: Treatment produced an increase in mandibular length, a decrease in ANB angle, and a restriction in the vertical growth of posterior maxilla. The maxillary molars moved backward and tipped distally. The lower incisors proclined markedly, and the upper incisors became retroclined. During the follow-up period, the changes primarily were dentoalveolar in nature, with marked rebound of the upper molars and lower incisors, resulting in some increases in overbite and overjet. CONCLUSIONS: The occlusal correction of Class II malocclusion observed 1 year after the crown Herbst appliance as a single-phase therapy was achieved primary due to the dentoalveolar changes and only limited skeletal change occurred.

Immediate post-treatment crowned Herbst effects in growing patients.

OBJECTIVE. The aim of this prospective study was to describe the mechanism of Class II correction in growing patients induced by crown Herbst (cHerbst) appliance as an immediate result of therapy. MATERIALS AND METHODS. Forty patients (mean age 13.6 ± 1.3 years) with stable Class I occlusion 1 year following treatment with the cHerbst appliance were selected from a prospective sample of 180 consecutively treated Class II patients. No other appliances were used during treatment. The immediate dentoskeletal changes after discontinuing cHerbst therapy were compared with a matched sample of untreated Class II subjects (mean age 13.9 ± 1.6 years). Lateral cephalograms were taken before treatment and immediately after one year therapy. RESULTS. Treatment produced significant skeletal changes: increase in mandibular length and SNB angle, decrease of ANB angle, restricted growth of posterior maxilla. Significant dentoalveolar changes: maxillary molars moved backwards and tipped distally, lower first molars moved forward and extruded, lower incisors proclined, upper incisors retroclined, overjet and overbite decreased. CONCLUSIONS. Immediate postreatment results revealed that Class II was mainly corrected due to dentoalveolar changes and only limited skeletal change.

A prospective study on the clinical effectiveness of the stainless steel crown Herbst appliance.

OBJECTIVES: To evaluate the clinical performance of the stainless steel crown Herbst (cHerbst) used as a single appliance for a single phase therapy. MATERIALS AND METHODS: A total of 180 consecutive Class II patients were treated with cHerbst for one year and followed up one year after the end of treatment. RESULTS: Class I relationship was achieved in all 175 patients who finished the functional phase of treatment, 58 patients continued treatment with fixed appliances while 21 patients (12%) showed relapse. Seventy two patients (41.1%) obtained and maintained stable Class I relationship one year after treatment with the cHerbst appliance used as a single appliance. Altogether 46 episodes of appliance breakages were observed and most of them could be repaired at the chair side. Patients' questionnaire revealed that in general the appliance was easy to tolerate and did not cause esthetic or functional problems. CONCLUSIONS: The crown Herbst appliance is a viable therapeutical option in patients with Class II malocclusions and it is characterized by low complication rate along with good patient compliance.

Influence of premolar extractions on tooth size discrepancy. part one: analysis of Bolton index.

The purpose of this study is to determine the influence on four premolar extractions for upper and lower anterior tooth size discrepancy (for total Bolton index (TBI=Overall ratio) and for Bolton value (BV)) and to find out the differences of four first and second premolar extractions tooth size discrepancies (TSD). 148 pretreatment dental casts have been examined. It has been determined that upper teeth of 93 patients suited lower teeth sizes (normal TBI - 91.3%+/-1.91), 27 patients had upper teeth wider than lower ones (low TBI<89.39%) and 28 patients had wider teeth in lower jaw (high TBI>93.21%). In this study the influence of four hypothetical first and second premolar extractions (1. all first premolars, 2. all second premolars, 3. upper first and lower second premolars, 4. upper second and lower first premolars) on TSD frequency appearance and size has been estimated. After performing the analysis it was estimated that in normal Bolton index group TSD is more frequent, when four first premolars are extracted (p<0.05 after comparing with extraction of four second premolars). When TBI is high, in all four hypothetical teeth extraction variations TBI remain increased, which determine 100% TSD. In low TBI group TSD is more usual when four-second premolars are extracted (p<0.01, after comparing with teeth extractions using 1-st or 3-rd method).