Controlling incisor torque with completely customized lingual appliances

Effect of torque customization with composite resin bases on the shear bond strength and adhesive remnant patterns of lingual brackets : An in vitro evaluation

PURPOSE

This study evaluated the effect of torque customization of lingual brackets with resin-modified bases on their shear bond strength (SBS), adhesive remnant index (ARI), and bond failure patterns (BFP).

METHODS

The sample comprised 200 lingual lower incisor brackets (DTC® ORG, DTC Medical Apparatus, Hangzhou, China); 40 brackets were tested as-received and 4 groups with 40 brackets each were customized for -10, -20, +10 and +20° torque respectively with light-cured composite resin (Transbond XT™, 3M Unitek, Monrovia, CA, USA) bases. All brackets were bonded to bovine mandibular incisors. Their SBS were estimated in a universal testing machine (INSTRON®, Norwood, MA, USA) with a gingivally directed force applied at the incisal bracket-adhesive interface with 1 mm/min crosshead speed. Their ARI and BFP were evaluated under 20× magnification.

RESULTS

The SBS was 19.9 ± 7.6 MPa for noncustomized brackets, 20.1 ± 9.0 and 18.7 ± 8.2 MPa for brackets with 10 and 20° of negative torque, and 16.6 ± 5.68 and 19.45 ± 5.84 MPa for brackets with 10 and 20° of positive torque, respectively. The differences were not statistically significant (p = 0.097). Teeth with the -20° brackets exhibited higher median ARI scores than noncustomized brackets (1.5 vs 2, p = 0.018). Adhesive-cohesive bond failure with nearly axial split was more frequent in noncustomized brackets than customized ones, the reverse being true for adhesive-cohesive failure with nearly vertical split (p < 0.05). Truly cohesive bond failures were seen only in brackets with positive torque.

CONCLUSIONS

Torque customization with a resin base is an acceptable strategy for metal orthodontic brackets as it does not affect their SBS. However, their BFP differed from noncustomized brackets, depending on the type of torque introduced.

Non-extraction camouflage on a fully cooperative full-step class II division 2 adult patient treated with en-masse distalization, class II elastics and preadjusted lingual appliance: A case report

This article describes one adult bilateral full-step class II case with severe initial upper incisors retroclination successfully treated by a completely invisible lingual appliance. A non-extraction treatment to compensate for the severe sagittal discrepancy was made possible following the excellent patient cooperation with intermaxillary elastics, combined with upper arch en-masse effective distalization with miniscrews. The application of an auxiliary torque spring was essential to increase upper incisors torque during class II mechanics. This case report shows the possibility of obtaining a full-step class II correction in an hypodivergent adult patient with a completely invisible appliance, taking advantage for the patient cooperation, for a more straightforward and faster non-extraction case resolution. It also underlines on the other hand the importance of successfully controlling incisors torque with auxiliaries in cases of severe retroclination in an adult class II malocclusion, in combination with the simultaneous distalization mechanics for monolateral full-step class II correction, by means of a completely invisible appliance.

Favourable dentoalveolar changes after lower premolar extractions for Class III camouflage with completely customized lingual appliances

BACKGROUND

The aim of the investigation was to evaluate if the inclination of the lower anterior teeth can be controlled reliably after lower premolar extraction for Class III camouflage treatment with completely customized lingual appliances (CCLAs). Treatment outcome was tested against the null hypothesis that lower premolar extractions for non-surgical camouflage treatment of a Class III malocclusion will lead to further compensation by retroclining mandibular incisors during CCLA treatment.

METHODS

This retrospective study included 25 patients (f/m 12/13; mean age 20.7 years, SD 9.5 years) with uni- or bilateral Class III molar relationship and a Wits value of ≤ -2 mm. In all consecutively debonded patients, lower premolars were extracted to correct the sagittal relationship with a non-surgical camouflage approach. Lateral head films prior to (T1) and at the end of lingual orthodontic treatment (T2) were used to evaluate skeletal and dentoalveolar effects. A paired t-test with alpha = 5% was used to define differences between the endpoints. The linear correlation between the inclination of the mandibular incisors at T1 and the achieved correction was measured with the Pearson correlation coefficient (PCC). A Schuirmann's TOST equivalence test was used to check if the final lower incisor inclination was within the defined norms.

RESULTS

The null hypothesis was rejected as the mean lower incisor inclination was improved by 1.8° despite lower premolar extractions (T1: 86.8°/ T2: 88.6°). There was a strong correlation (-0.75) between the lower incisor inclination at T1 and the achieved correction indicating a controlled correction towards the norm regardless of the initial incisor position. At T2, the interincisal angle as well as the lower incisor inclination were within the norm.

CONCLUSION

Lower premolar extractions for non-surgical camouflage treatment of a Class III malocclusion will not lead to undesired retroclining of mandibular incisors during CCLA treatment even in severe cases.

Quality of occlusal outcome in adult Class II patients treated with completely customized lingual appliances and Class II elastics compared to adult Class I patients

OBJECTIVES

The aim of this investigation was to evaluate whether Class II malocclusion in adult patients can be successfully corrected using a completely customized lingual appliance (CCLA) in combination with Class II elastics.

METHODS

In order to detect differences in the final treatment outcome, two groups were matched for age and gender. Treatment results of 40 adult orthodontic patients with a Class I malocclusion (Group 1) were compared to 40 adults with a Class II malocclusion (Group 2). All patients had completed treatment with a CCLA (WIN, DW Lingual Systems, Bad Essen, Germany) without known centric occlusion-centric relation discrepancies, issues of compliance, or overcorrection in the individual treatment plan which was defined by a target set-up. In order to compare the treatment results of the two groups, 7 measurements using the American Board of Orthodontics Model Grading System (ABO MGS) and linear measurements for anterior-posterior (AP) and vertical dimensions were assessed at the start of lingual treatment (T1), after debonding (T2B) and compared to the individual target set-up (T2A).

RESULTS

A statistically significant AP correction was achieved in Group 2 which represented 95% of the planned amount. The planned overbite correction was fully achieved in the Class I and Class II group. In both groups, there was a statistically significant improvement in the ABO scores, with no significant difference between the two groups at T2. 100% of the patients in Group 2 and 92.5% in Group 1 would meet the ABO standards after CCLA treatment.

LIMITATIONS

The main limitation of this study is that only patients who were wearing the elastics as prescribed were retrospectively included. Therefore, the results of this study may have limited generalizability.

CONCLUSIONS

Completely customized lingual appliances in combination with Class II elastics can correct a Class II malocclusion successfully in adult patients. The final treatment outcome can be of a similar high quality in Class I and Class II patients.

Quality of occlusal outcome in adult class II patients after maxillary total arch distalization with interradicular mini-screws

BACKGROUND

The aim of the investigation was to evaluate if a Class II malocclusion in adult patients can be successfully corrected by maxillary total arch distalization with interradicular mini-screws in combination with completely customized lingual appliances (CCLA).

METHODS

Two patient groups were matched for age and gender to determine differences in the quality of final treatment outcome. The treatment results of 40 adult patients with a Class I malocclusion (Group 1) were compared with those of 40 adult patients with a moderate to severe Class II malocclusion (Group 2). All patients had completed treatment with a CCLA (WIN, DW Lingual Systems, Bad Essen, Germany) without overcorrection in the individual treatment plan defined by a target set-up. To compare the treatment results of the two groups, 7 measurements using the American Board of Orthodontics Model Grading System (ABO MGS) and linear measurements for anterior-posterior (AP) and vertical dimensions were assessed at the start of lingual treatment (T1), after debonding (T2B), and compared to the individual target set-up (T2A).

RESULTS

A statistically significant AP correction (mean 4.5 mm, min/max 2.1/8.6, SD 1.09) was achieved in Group 2, representing 99% of the planned amount. The planned overbite correction was fully achieved in both the Class I and Class II groups. There was a statistically significant improvement in the ABO scores in both groups (Group 1: 39.4 to 17.7, Group 2: 55.8 to 17.1), with no significant difference between the two groups at T2B. 95% of the adult patients in Group 1 and 95% in Group 2 would meet the ABO standards after maxillary total arch distalization with a CCLA and interradicular mini-screws.

CONCLUSIONS

CCLAs in combination with interradicular mini-screws for maxillary total arch distalization can successfully correct moderate to severe Class II malocclusions in adult patients. The quality of the final occlusal outcome is high and the amount of the sagittal correction can be predicted by the individual target set-up.

Invisible treatment with lingual appliance for the correction of an adult class II subdivision with asymmetrical Wilson and Spee curves: A case report

This article describes a class II subdivision malocclusion successfully treated by an invisible lingual appliance. The combination of en-masse distalization by interradicular palatal mini-screws and inner unilateral class II auxiliaries, first by intermaxillary elastic, later by a class II coil spring, resulted in a dento-alveolar correction, allowing one to maintain the appliance completely invisible. At the same time, the inclination of buccal sectors was normalized by a correct torque expression with set-up overcorrections, resulting in a significant improvement of the buccal corridors. This case report demonstrates the possibility of successfully solving class II division 2 subdivision malocclusion in adult patients without surgery by means of a completely invisible appliance. It also demonstrates that correct levelling and torque expression, for the correction of asymmetrical Spee and Wilson curves, are achievable with an accurate set-up planning. On the other hand, it underlines the necessity of mini-screws, auxiliaries and set-up overcorrections in order to obtain the best results.

Non-Surgical Transversal Dentoalveolar Compensation with Completely Customized Lingual Appliances versus Surgically Assisted Rapid Palatal Expansion in Adults-The Amount of Posterior Crossbite Correction

The aim of this study was to compare the crossbite correction of a group (n = 43; f/m 19/24; mean age 27.6 ± 9.5 years) with surgically assisted rapid palatal expansion (SARPE) versus a non-surgical transversal dentoalveolar compensation (DC) group (n = 38; f/m 25/13; mean age 30.4 ± 12.9 years) with completely customized lingual appliances (CCLA). Arch width was measured on digital models at the canines (C), second premolars (P2), first molars (M1) and second molars (M2). Measurements were obtained before treatment (T0) and at the end of lingual treatment (T1) or after orthodontic alignment prior to a second surgical intervention for three-dimensional bite correction. There was no statistically significant difference (p > 0.05) in the amount of total crossbite correction between the SARPE and DC-CCLA group at C, P2, M1 and M2. Maxillary expansion was greater in the SARPE group and mandibular compression was greater in the DC-CCLA group. Crossbite correction in the DC-CCLA group was mainly a combination of maxillary expansion and mandibular compression. Dentoalveolar compensation with CCLAs as a combination of maxillary expansion and mandibular compression seems to be a clinically effective procedure to correct a transverse maxillo-mandibular discrepancy without the need for surgical assistance.

A comparison of treatment results of adult deep-bite cases treated with lingual and labial fixed appliances

OBJECTIVES

To compare the cephalometric treatment results of adult deep-bite cases after labial and lingual fixed orthodontic treatment.

MATERIALS AND METHODS

A total of 102 patients underwent lingual orthodontic treatment and complete records were evaluated. The following inclusion criteria were used: patients who had Angle Class I or mild Class II malocclusion; comprehensive orthodontic treatment that did not include intrusion mechanics or any extractions; patients with an initial overbite of more than 3.7 mm. Thirteen patients met the inclusion criteria. These cases were matched with the same number of patients according to age with a labial orthodontic treatment group. Pre- and post-treatment cephalometric radiographs were evaluated. Independent t test or Fisher exact tests were performed to assess the differences between the groups.

RESULTS

Proclination of the upper incisors was higher in the labial group. Incisor mandibular plane angle (IMPA) showed an increase of 1.2° in the lingual group and 9.7° in the labial group. Lower incisor edge was approximately in a stable sagittal position in the lingual group but significant lower incisor proclination was seen in the labial group. The lower incisors were intruded (-1 mm) in the lingual group but lower incisors were minimally extruded (0.3 mm) in the labial group. No significant difference was found in the movements of upper and lower molars for both groups.

CONCLUSIONS

The nature of lower incisor movement involved less protrusion in lingual orthodontics than the labial treatment. Lingual orthodontic treatment is a better option in adult cases where intrusion of lower incisors without labial tipping is desired.

Implications of pretreatment incisor inclinations for the achievement of cephalometric normal values-a study on two patient collectives

PURPOSE

The objective was to clarify whether standardized multibracket therapies-differing only in finishing-wire dimensions (0.016 × 0.022 inch vs. 0.017 × 0.025 inch CNA [Connecticut New Archwire]) and excluding any extraction treatment or additional appliances other than intermaxillary elastics-can produce normal incisor inclinations starting from different baseline inclinations.

METHODS

We analyzed pre- and posttreatment cephalograms of 156 patients (age: 15.6 ± 1.3 years) treated with Roth system (0.018 inch slot). Each archwire group (n = 89 or 67) was divided into subjects with initially retroclined, orthograde, or proclined upper and/or lower incisors (U1, L1). For the resultant 12 subgroups, descriptive statistics were compiled relative to five reference planes (NL, ML, NA, NB, BOP), followed by multiple intragroup (Kolmogoroff-Smirnoff and Wilcoxon signed-rank test) and intergroup (Kruskal-Wallis and Mann-Whitney U test) comparisons relative to NL or ML.

RESULTS

The following intra- (1, 2) and intergroup (3, 4) differences were statistically significant (p ≤ 0.05) in both archwire groups: (1) post- vs. pretreatment inclinations in the subgroups initially retroclined U1, retroclined L1 and orthograde U1, but without normal values being achieved (subgroups retroclined U1, L1) or preserved (subgroup orthograde U1); (2) observed vs. expected alterations for the subgroups initially orthograde and proclined U1 and L1; (3) posttreatment inclinations for the subgroups initially retroclined vs. orthograde L1 and proclined L1; (4) observed alterations for the subgroups initially retroclined vs. proclined U1 and L1, but neither retroclined nor proclined vs. orthograde. Archwire thickness influenced the outcome to only a limited extent under the special circumstances of this study.

CONCLUSION

The bracket/archwire combinations evaluated did not lead to normal incisor inclinations in most cases. Posttreatment values did significantly depend on the pretreatment situation. Most frequently, alterations were protrusive in direction, which notably even included incisors that showed norm values at the outset of treatment. It can be concluded that bracket torque will influence but not dominate incisor inclinations.

Class II correction by maxillary en masse distalization using a completely customized lingual appliance and a novel mini-screw anchorage concept - preliminary results

Background

The aim of the study was to evaluate the efficacy of a novel en masse distalization method in the maxillary arch in combination with a completely customized lingual appliance (CCLA; WIN, DW Lingual Systems, Germany). Therefore, we tested the null-hypothesis of a significant deviation from an Angle-Class I canine relationship and a normal overjet defined by an individual target set-up after dentoalveolar compensation in Angle Class II subjects.

Methods

This retrospective study included 23 patients, (m/f 3/20, mean age 29.6 years (min/max, 13.6/50.9 years)), with inclusion criteria of an Angle Class II occlusion of more than half a cusp prior to en masse distalization and treatment completed consecutively with a CCLA in combination with a mini-screw (MS) anchorage for uni- or bilateral maxillary distalization (12 bilateral situations, totalling 35). Plaster casts taken prior to (T0) and following CCLA treatment (T3) were compared with the treatment plan / set-up (TxP, with a Class I canine relationship and a normal overjet as the treatment objective). MSs were placed following levelling and aligning (T1) and removed at the end of en masse distalization at T2. Statistical analysis was carried out using Schuirmann’s TOST [two one-sided tests] equivalence test, based on a one-sample t-test with α = 0.025 on each side (total α = 0.05).

Results

Ninety-seven percent of planned correction of the canine relationship was achieved (mean 3.6 of 3.7 mm) and also 97 % of the planned overjet correction (mean 3.1 of 3.2 mm), with a statistically significant equivalence (p < 0.0001) for canine relationship and overjet between the individual treatment plan (set-up) and the final outcome. Adverse effects were limited to the loss of n = 2 of 35 mini-screws. However, in each instance, the treatment was completed, as scheduled, without replacing them. Accordingly, the null-hypothesis was rejected.

Conclusions

The technique presented allows for a predictable correction of an Angle-Class II malocclusion via dentoalveolar compensation with maxillary en masse distalization.

Lingual treatment of an adult patient with an iatrogenic class II anterior open bite: Report of a case with a non-surgical orthodontic approach

INTRODUCTION

The treatment of adult patients presenting an open bite is a real challenge for orthodontists due to the complexity of the malocclusion. The diagnosis is essential to identify aetiological factors and establish the best aesthetic and functional therapeutic prognosis. Among the aetiological factors, iatrogenic treatment history has to be considered. It is the case here where a regrettable unsuitable splint for bruxism treatment forced an open bite to appear.

MATERIAL AND METHOD

This case report presents an adult women with a large open bite due to an occlusal splint not covering the last mandibular molars. It was not really a vertical skeletal excess but more a mandibular clockwise rotation linked to the molar extrusions, which created a dento-alveolar open bite and labio-mental contractions during lip closure. Treatment objectives were the intrusion of the third and second molars, the extrusion of incisors to obtain a counter clockwise mandibular rotation. The patient was treated with an aesthetic and customized lingual appliance with no orthognathic surgery. A physiotherapy was followed by the patient when the open bite was closed in order to facilitate and stabilize the intercuspation.

RESULTS

A complete closing of the open bite was reached after two years of treatment. The superimposition showed the anticlockwise mandibular rotation. The levelling with posterior intrusion and the incisors extrusion reduced the vertical dimension with success. After 3years of retention, the occlusal stability was obtained.

CONCLUSION

The intrusion of the molars associated with a counter clockwise mandibular rotation made it possible the incisor extrusion. The occlusal balance with physiotherapy and patient compliance maintained the closure. In this way, the iatrogenic effects of the poorly designed bite splint were repaired.