Atypical orthodontic extraction pattern managed by differential en-masse retraction against a temporary skeletal anchorage device in the treatment of bimaxillary protrusion

Factors influencing the successful eruption of the maxillary third molar after extraction of the maxillary second molar

INTRODUCTION

This study evaluated the occlusal status of the maxillary third molars that erupted spontaneously after extraction of the maxillary second molars and investigated the factors that influenced the occlusal status of the maxillary third molars.

METHODS

We assessed 136 maxillary third molars in 87 patients. Alignment, marginal ridge discrepancy, occlusal contact, interproximal contact, and buccal overjet were used to score the occlusal status. Occlusal status was classified as good (G group), acceptable (A group), and poor (P group) for the maxillary third molar at its full eruption (T1). The Nolla's stage, long axis angle, the vertical and horizontal position of the maxillary third molar, and the maxillary tuberosity space were assessed at the time of maxillary second molar extraction (T0) and T1 to identify factors influencing the eruption of the maxillary third molar.

RESULTS

G, A, and P groups comprised 47.8%, 17.6,% and 34.6% of the sample, respectively. Age was the lowest in the G group at both T0 and T1. The maxillary tuberosity space at T1 and the amount of the change of maxillary tuberosity space were the largest in the G group. There was a significant difference in the distribution of the Nolla's stage at T0. The proportions of the G group were 60.0% in stage 4, 46.8% in stages 5 and 6, 70.4% in stage 7, and 15.0% in stages 8-10. According to multiple logistic regression analysis, stages 8-10 for the maxillary third molar at T0 and the amount of the change of maxillary tuberosity were negatively associated with the G group.

CONCLUSIONS

Good-to-acceptable occlusion was seen in 65.4% of the maxillary third molars after maxillary second molar extraction. Insufficient increase in the maxillary tuberosity space and Nolla stage 8 or higher at T0 negatively influenced the maxillary third molar eruption.

Class III malocclusion with traumatic unilateral maxillary central incisor loss treated using orthodontic miniscrews: a case report

The present article reports the successful non-extraction orthodontic treatment using miniscrew anchorage in a patient who presented with maxillary left central incisor loss and unstable jaw movements. The chief complaints of the 23-year-old female patient were her protruding teeth and crowding of the mandibular anterior segment. The patient lost her maxillary left central incisor as a result of a traumatic injury during childhood. However, the crown was saved and attached to the adjacent teeth. The patient was diagnosed with a skeletal Class III and Angle Class III dental malocclusion. The jaw movements determined by a 6 degrees of freedom jaw movement recording system were unstable and irregular. Miniscrew anchorage was applied for distalisation of the maxillary right dentition and the mandibular dentition during non-extraction treatment. The maxillary left dentition was mesialised using miniscrew anchorage to close the space as a result of the lost maxillary left central incisor. After an active treatment duration of 36 months, the patient achieved a Class II molar relationship on the left side, a Class I on the right side, an optimal overjet and overbite, and a pleasing facial profile. Despite the asymmetric molar relationships, functionally stable and smooth jaw movements were established. The skeletal, occlusal and functional stability remained satisfactory after a 2-year retention period. In conclusion, miniscrew anchorage was valuable in supporting asymmetric tooth movement during non-extraction appliance treatment in a patient who presented with traumatic unilateral tooth loss.

Severe skeletal bimaxillary protrusion treated with micro-implants and a self-made four-curvature torquing auxiliary: A case report

BACKGROUND

Bimaxillary protrusion is a clinically common dentofacial deformity, particularly among Chinese patients. This kind of malformation can severely affect facial esthetics and, even in mild cases, is difficult to correct without surgery. Unfortunately, many patients abandon treatment because of fear of surgery. Here, we describe a case of severe skeletal bimaxillary protrusion treated with nonsurgical orthodontic treatments, highlighting an alternative treatment option.

CASE SUMMARY

A 31-year-old woman wished to address a severe protrusion profile (approximately 8 mm overbite) and gummy smile. Cephalometric analysis and superimposition showed a severe skeletal class II pattern with a mandibular retrusion, and proclined and protrusive mandibular incisors. Panoramic radiograph showed a missing mandibular right third molar. A diagnosis of severe bimaxillary dentoalveolar protrusion was made. Taking into account the patient’s fear of orthognathic surgery, she accepted the proposed alternative treatment using micro-implants and a self-made four-curvature torquing auxiliary. The treatment allowed for maximal en masse anterior tooth retraction, proper relocation of incisors, and alleviation of the skeletal class II pattern. Esthetically, the patient’s lip protrusion was significantly decreased as was the overjet (from 10.5 mm to 1.8 mm), and the results remained stable throughout the 2-year follow-up.

CONCLUSION

Nonsurgical treatment using micro-implants and a four-curvature torquing auxiliary may benefit severe cases of skeletal bimaxillary protrusion in adults.

Finite element study of controlling factors of anterior intrusion and torque during Temporary Skeletal Anchorage Device (TSAD) dependent en masse retraction without posterior appliances: Biocreative hybrid retractor (CH-retractor)

OBJECTIVES

To evaluate, using the finite element method (FEM), the factors that allow control of the anterior teeth during en masse retraction with the Biocreative hybrid retractor (CH-retractor) using different sizes of nickel-titanium (NiTi) archwires and various gable bends on the stainless-steel (SS) archwires.

MATERIALS AND METHODS

Using FEM, the anterior archwire section, engaged on the anterior dentition, was modeled in NiTi, and another assembly, the posterior guiding archwire, was modeled in SS. Two dimensions (0.016 × 0.022- and 0.017 × 0.025-inch NiTi) of the anterior archwires and different degrees (0°, 15°, 30°, 45°, and 60°) of the gable bends on the guiding wire were applied to the CH-retractor on the anterior segment to evaluate torque and intrusion with 100-g retraction force to TSADs. Finite element analysis permitted sophisticated analysis of anterior tooth displacement.

RESULTS

With a 0° gable bend all anterior teeth experienced extrusion. The canines showed a larger amount of extrusion than did the central and lateral incisors. With a gable bend of >15°, all anterior teeth exhibited intrusion. Bodily movement of the central incisor required a 30°∼45° gable bend when using anterior segments of 0.016 × 0.022-inch NiTi and 15°∼30° gable bend with the 0.017 × 0.025-inch NiTi.

CONCLUSIONS

With the CH-retractor, varying the size of the NiTi archwire and/or varying the amount of gable bend on the SS archwire affects control of the anterior teeth during en masse retraction without a posterior appliance.

Effects of force magnitude on torque control in the correction of bimaxillary protrusion with mass retraction

OBJECTIVES:

This study was designed to explore whether force magnitude would influence incisor torque control and the overall outcome in patients with bimaxillary protrusion who need mass incisor retraction.

MATERIALS AND METHODS:

Forty-one female patients (aged > 15 years) with bimaxillary protrusion requiring mass incisor retraction were selected. Two sliding mechanics were utilized, with the elastic group receiving a light force of ~100 g by wearing elastics and the power chain group receiving a moderate force of ~250 g by power chain. Lateral cephalograms obtained before and after treatment were traced and measured.

RESULTS:

Patients in both groups displayed maxillary protrusion with a similar skeletal class II tendency. A longer treatment time was found in the elastic group. No difference in the distance of incisor tip movement was observed between the two groups; however, a larger inclination of upper incisors was found in the elastic group, indicating less loss of torque. In addition, larger reduction in Sella-Nasion-A and A-Nasion-B angle was observed in the elastic group, which was accompanied by a larger ratio of upper lip retraction to upper incisor retraction as well as more upper lip retraction.

CONCLUSIONS:

Sliding mechanics with elastics to generate light forces can achieve better torque control with more reduction in skeletal and soft tissue protrusion.

Nonsurgical treatment of severe Class II malocclusion with anterior open bite using mini-implants and maxillary lateral incisor and mandibular first molar extractions

This clinical case report presents the nonsurgical orthodontic treatment of a patient with skeletal Class II malocclusion, posterior crossbite, anterior open bite, accentuated dental discrepancies in both arches, and an odontoma. The proposed treatment involved maxillary expansion, extraction of atypical maxillary lateral incisors and mandibular first molars, and intrusion of maxillary teeth with the aid of mini-implants. The results obtained with these procedures included good tooth alignment, normal overbite and overjet, removal of the odontoma, and a harmonious smile. In complex cases, an accurate diagnosis is the key to a favorable outcome.

En-masse retraction with a preformed nickel-titanium and stainless steel archwire assembly and temporary skeletal anchorage devices without posterior bonding

Objective

To evaluate the therapeutic effects of a preformed assembly of nickel-titanium (NiTi) and stainless steel (SS) archwires (preformed C-wire) combined with temporary skeletal anchorage devices (TSADs) as the sole source of anchorage and to compare these effects with those of a SS version of C-wire (conventional C-wire) for en-masse retraction.

Methods

Thirty-one adult female patients with skeletal Class I or II dentoalveolar protrusion, mild-to-moderate anterior crowding (3.0-6.0 mm), and stable Class I posterior occlusion were divided into conventional (n = 15) and preformed (n = 16) C-wire groups. All subjects underwent first premolar extractions and en-masse retraction with pre-adjusted edgewise anterior brackets, the assigned C-wire, and maxillary C-tubes or C-implants; bonded mesh-tube appliances were used in the mandibular dentition. Differences in pretreatment and post-retraction measurements of skeletal, dental, and soft-tissue cephalometric variables were statistically analyzed.

Results

Both groups showed full retraction of the maxillary anterior teeth by controlled tipping and space closure without altered posterior occlusion. However, the preformed C-wire group had a shorter retraction period (by 3.2 months). Furthermore, the maxillary molars in this group showed no significant mesialization, mesial tipping, or extrusion; some mesialization and mesial tipping occurred in the conventional C-wire group.

Conclusions

Preformed C-wires combined with maxillary TSADs enable simultaneous leveling and space closure from the beginning of the treatment without maxillary posterior bonding. This allows for faster treatment of dentoalveolar protrusion without unwanted side effects, when compared with conventional C-wire, evidencing its clinical expediency.

Class I malocclusion with severe double protrusion treated with first premolars extraction

Angle Class I malocclusion with bymaxillary protrusion is characterized by severe buccal tipping of incisors, which causes upper and lower lip protrusion. First premolars extraction is recommended to reduce facial convexity as a result of anterior teeth retraction, which keeps canines and first molars in key to occlusion. In order to yield orthodontic results that are compatible with ideal esthetic and cephalometric outcomes, the space closure phase needs to be carried out with overbite and incisors torque control. The majority of cases also requires maximum anchorage of posterior teeth. This case was presented to the Brazilian Board of Orthodontics and Facial Orthopedics (BBO) as a requirement for the title of certified by the BBO.