Comparison between direct vs indirect anchorage in two miniscrew-supported distalizing devices

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.

Clear aligner treatment assisted by mini screw for an adult with Class II division 2 malocclusion and a right upper canine completely outside of the dental arch: A case report

This case report describes a 19-year-old man presented with a 5.7-mm deep overbite, Class II division 2 malocclusion with the right upper maxillary canine completely buccal ectopia, deviated midline in the upper arch, severe crowding and retroclination of the maxillary and mandibular incisors. The patient was treated with clear aligners to correct the Class II relationship and the deep overbite. A series of clear aligners were used to move bilateral maxillary molars distally with unilateral mini-screw anchorage. The final results showed that clear aligners with mini-screws could effectively achieve the required upper distal molar movement thanks to a reasonable design of the stages and anchorage. The treatment was completed in 19 months and the patient was satisfied with the treatment outcome in this context of mild to moderate Class II division 2 malocclusion.

Effectiveness of miniscrew-supported maxillary molar distalization according to temporary anchorage device features and appliance design: systematic review and meta-analysis

OBJECTIVES

To evaluate the effectiveness of distalizing maxillary first molars (U6) by temporary anchorage devices (TADs) according to their location (palatal, buccal, and zygomatic), their number, and appliance design.

MATERIALS AND METHODS

An electronic search of maxillary molar distalization with TADs was done through April 2023. After study selection, data extraction, and risk-of-bias assessment, meta-analyses were performed for the extent of distalization, distal tipping, and vertical movement of U6 using the generic inverse variance and random-effects model. The significance level was set at 0.05.

RESULTS

Forty studies met the inclusion criteria: 4 randomized controlled trials (RCTs), 13 prospective studies, and 23 retrospective studies (total of 1182 patients). Distalization of the U6 was not significantly greater (P = .64) by palatal (3.74 mm) and zygomatic (3.68 mm) than by buccal (3.23 mm) TADs. Distal tipping was significantly higher (P < .001) in nonrigid (9.84°) than in rigid (1.97°) appliances. Vertical movement was mostly intrusive and higher but not significantly different (P = .28) in zygomatic anchorage (-1.16 mm).

CONCLUSIONS

Distalization of U6 with TADs can be an effective and stable treatment procedure, especially when performed with rigid palatal appliances. However, further RCTs or prospective cohort studies are strongly recommended to provide more clinical evidence.

Finite element analysis of two skeletally anchored maxillary molar distalisation methods

OBJECTIVE

To compare two methods of maxillary molar distalisation with skeletal anchorage using finite element analysis (FEA).

METHODS

Two digitised models were created: the miniscrew-anchored distaliser, which consisted of a distalisation method anchored in a buccal miniscrew between the first molar and second premolar (Model 1), and the miniscrew-anchored palatal appliance, which consisted of a distalisation method anchored in a miniscrew on the anterior region of the palate (Model 2). FEA was used to simulate both methods, assessing teeth displacements and stress concentration.

RESULTS

The miniscrew-anchored distaliser showed greater buccal than distal displacement of the first molar, while the opposite was observed in the miniscrew-anchored palatal appliance. The second molar responded similarly in the transverse and anteroposterior perspectives with both appliances. Greater displacements were observed at crown level than in apical regions. Greater stress concentration was observed at the buccal and cervical regions of the crown in the miniscrew-anchored distaliser and the palatal and cervical regions in the palatal appliance. The stress progressively spread in the buccal side of the alveolar bone for the miniscrew-anchored distaliser and in the palatal root and alveolar bone for the palatal appliance.

CONCLUSION

FEA assumes that both appliances would promote maxillary molar distalisation. A skeletally anchored palatal distalisation force seems to provide a greater molar bodily movement with less undesirable effects. Greater stress is expected at the crown and cervical regions during distalisation, and the stress concentration in the roots and alveolar bone depends directly on the region the force was applied.

Three-dimensional changes after maxillary molar distalization with a miniscrew-anchored cantilever

OBJECTIVES

To evaluate the changes after maxillary molar distalization in Class II malocclusion using the miniscrew-anchored cantilever with an extension arm.

MATERIALS AND METHODS

The sample included 20 patients (9 male, 11 female; mean age 13.21 ± 1.54 years) with Class II malocclusion, treated with the miniscrew-anchored cantilever. Lateral cephalograms and dental models obtained before (T1) and after molar distalization (T2) were evaluated using Dolphin software and 3D Slicer. Superimposition of digital dental models using regions of interest on the palate was performed to evaluate three-dimensional displacement of maxillary teeth. Intragroup change comparisons were performed using dependent t-test and Wilcoxon test (P < 0.05).

RESULTS

The maxillary first molars were distalized to overcorrected Class I. The mean distalization time was 0.43 ± 0.13 years. Cephalometric analysis demonstrated significant distal movement of the maxillary first premolar (-1.21 mm, 95% confidence interval [CI]: -0.45, -1.96) and maxillary first (-3.38 mm, 95% CI: -2.88, -3.87) and second molars (-2.12 mm, 95% CI: -1.53, -2.71). Distal movements increased progressively from the incisors to the molars. The first molar showed small intrusion (-0.72 mm, 95% CI: 0.49, -1.34). In the digital model analysis, the first and second molars showed a crown distal rotation of 19.31° ± 5.71° and 10.17° ± 3.84°, respectively. The increase in maxillary intermolar distance, evaluated at the mesiobuccal cusps, was 2.63 ± 1.56 mm.

CONCLUSIONS

The miniscrew-anchored cantilever was effective for maxillary molar distalization. Sagittal, lateral, and vertical movements were observed for all maxillary teeth. Distal movement was progressively greater from anterior to posterior teeth.

Class II malocclusion treatment with a customized dual force distalizer

Intraoral distalizers associated with skeletal anchorage provide the major benefit of promoting molar distalization with minimum anchorage loss and patient cooperation. This case report presents the treatment of a 17-year-old female with Class II Division 2 malocclusion, maxillary dentoalveolar protrusion, mild mandibular retrusion, increased overjet, deepbite, and lip incompetence. The treatment plan involved initial maxillary molar distalization with a customized version of the skeletally anchored dual force distalizer (DFD). The customized DFD used smaller mini-implants and included a fixed anterior biteplane. The device applied simultaneous forces from the buccal and palatal sides directly to the molars using nickel-titanium coil springs and allowed orthodontic mechanics in the mandibular teeth. An overcorrected Class I molar relationship was obtained after 6 months. After the distalization phase, retraction mechanics began with retraction loops and using a modified transpalatal bar reinforced with the mini-implants as anchorage. Moreover, the finishing phase was performed with multiloop edgewise archwires and intermaxillary elastics to enable an individualized control of each tooth. Total treatment time comprised 2 years 4 months, and significant improvements regarding the facial and occlusal perspectives were noticed. Similarly, these favorable changes remained stable during the 2-year follow-up period. The customized version of the skeletally anchored DFD followed by fixed appliances showed effectiveness and stability in Class II malocclusion treatment.

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.

Distalization in Orthodontics: A Review and Case Series

Distalization is a conservative method that is utilized in orthodontics to gain space by moving posterior teeth distally. It may be combined with other space gaining strategies, such as expansion, or can be used alone. Many methods have been used for distalization. These methods differ significantly in their place, whether to be extraoral or intraoral, site of action in upper and/or lower arch, and cooperation needed by the patient if it is removable or fixed. This review illustrates some of the most commonly used methods for distalization with a brief presentation of three cases that incorporated successful distalization techniques.

Class II malocclusion treatment changes with the Jones jig, Distal jet and First Class appliances

Objective Maxillary molar distalization with intraoral distalizer appliances is a non-extraction orthodontic treatment used to correct molar relationship in patients with Class II malocclusion presenting maxillary dentoalveolar protrusion and minor skeletal discrepancies. This study compares the changes caused by three distalizers with different force systems. Methodology 71 patients, divided into three groups, were included. The Jones jig group (JJG, n=30; 16 male, 14 female, 13.17 years mean age) was treated with the Jones jig for 0.8 years. The Distal jet group (DJG, n=25; 8 male, 17 female, 12.57 years mean age) was treated with the Distal jet for 1.06 years. The First Class group (FCG, n=16; 6 male, 10 female, 12.84 years mean age) was treated with the First Class for 0.69 years. Intergroup treatment changes were compared using one-way ANOVA, followed by post-hoc Tukey's tests. Results Intergroup comparisons showed significantly greater maxillary incisor protrusion in DJG than in FCG (2.56±2.24 mm vs. 0.74±1.39mm, p=0.015). The maxillary first premolars showed progressive and significantly smaller mesial angulation in JJG, FCG and DJG, respectively (14.65±6.31º, 8.43±3.99º, 0.97±3.16º; p<0.001). They also showed greater mesialization in JJG than FCG (3.76±1.46 mm vs. 2.27±1.47 mm, p=0.010), and greater extrusion in DJG compared to JJG (0.90±0.77 mm vs 0.11±0.60 mm, p=0.004). The maxillary second premolars showed progressive and significantly smaller mesial angulation and mesialization in JJG, FCG and DJG, respectively (12.77±5.78º, 3.20±3.94º, -2.12±3.71º and 3.87±1.34 mm, 2.25±1.40 mm, 1.24±1.26 mm, respectively; p<0.001). DJG showed smaller distal angulation of maxillary first molars (-2.14±5.09º vs. -7.73±4.28º and -6.05±3.76º, for the JJG and FCG, respectively; p<0.001) and greater maxillary second molars extrusion (1.17±1.41 mm vs -0.02±1.16 mm and 0.16±1.40 mm, for the JJG and FCG, respectively; p=0.003). Overjet change was significantly larger in DJG compared to FCG (1.79±1.67 mm vs 0.68±0.84; p=0.046). Treatment time was smaller in FCG (0.69±0.22 years vs 0.81±0.33 years and 1.06±0.42 years, comparing it with the JJG and DJG, respectively; p=0.005). Conclusion The three appliances corrected the Class II molar relationship by dentoalveolar changes. The Distal jet produced smaller molar distal angulation than the Jones jig and First Class. The First Class appliance showed less anchorage loss, greater percentage of distalization and shorter treatment time than the Jones jig and Distal jet.

Maxillary molar distalization in treatment of angle class II malocclusion growing patients: Uncontrolled clinical trial

OBJECTIVE

This study was conducted to evaluate the clinical effectiveness treatment effects of a simple buccal technique for maxillary molar distalization using direct buccal skeletal anchorage.

MATERIALS AND METHODS

After sample size calculation, fourteen female patients with bilateral Class II molar relationship (age 11-14 years) were selected from the clinic of the Department of Orthodontics, Faculty of Dentistry, Mansoura University, Egypt. After the application of the eligibility criteria, only eleven patients remained to final evaluation. The criteria included: erupted second maxillary molars, mild to moderate maxillary crowding not exceeding 6mm with/without increased overjet and non-extraction treatment in the lower arch. After alignment and levelling, a miniscrew (1. 8mm diameter - 0. 8mm long) was placed buccally between the maxillary second premolar and the first molar in each side. The maxillary molar distalization was done using 250 grams of force produced from NiTi closed coil spring stretched to a buccal miniscrew. Records including cephalometric x-rays and study casts were taken for all patients before and after molar distalization. Statistical evaluation was performed for the data obtained from analysis of cephalometric tracing and cast photocopies.

RESULTS

The maxillary first molars were distalized with a rate of 0. 89±0. 30mm (95% CI 0.76-1.02) (P<0.001) and distalization amount of 4.09±0. 92mm (CI 3.68-4.50) (P<0.001). They were distally tipped by 2.48°±6. 16 (CI -0.26-5.21) (P=0.073) and rotated distopalatally by 11.89°±5.86 with negligible change in their vertical position about 0.11±0.63mm (CI -0.40-0.17) (P=0.411). There was no anchorage loss evident by the distal movement of all the maxillary teeth (P<0.001). Overjet significantly reduced by 0. 86±0. 50 (CI 0.52-1.20) (P=0.004).

CONCLUSIONS

Maxillary molar distalization using a closed coil and buccal miniscrew is an effective and non-compliance dependent technique in a relatively short time.

Two distalization methods compared in a novel patient-specific finite element analysis

INTRODUCTION

Orthodontic mini-implants aid in the correction of distocclusions via direct anchorage (pull from mini-implant to teeth) and indirect anchorage (teeth pulled against other teeth anchored by the mini-implant). The aim of this study was to compare stress levels on the periodontal ligament (PDL) of maxillary buccal teeth in direct and indirect distalization against orthodontic mini-implants and accounting for individual variation in maxillary anatomy and biomechanical characteristics of the compact bone.

METHODS

A 3D model of the maxilla containing the different components (teeth, PDL, trabecular and cortical bones) was generated from a computed tomographic scan. Cortical bone was divided into several areas according to previously defined zones. Bone stiffness and thickness data, obtained from 11 and 12 cadavers, respectively, were incorporated into the initial model to simulate the individual cortical bone variation at the different locations. Subsequently, a finite element analysis was used to simulate the distalization modalities.

RESULTS

Stresses at the buccal, palatal, mesial, and distal surfaces were significantly different between adjacent teeth under stiffness but not thickness variation. In both distalization modalities, low or no significant correlations were found between stress values and corresponding cortical bone thicknesses. High significant and inverted correlations were observed at the first molar between stress amounts and cortical bone stiffness (direct modality: -0.68 < r < -0.72; indirect modality: -0.80 < r < -0.82; P <0.05).

CONCLUSIONS

With the use of a novel finite element approach that integrated human data on variations in bone properties, findings suggested that cortical bone stiffness may influence tooth movement more than bone thickness. Significant clinical implications could be related to these findings.

Maxillary molar distalization using conventional versus skeletal anchorage devices: A systematic review and meta-analysis

INTRODUCTION

The purpose of this study was to systematically review the evidence regarding conventional versus skeletal anchorage devices for molar distalization.

METHOD

An electronic search was conducted. Hand searching was done in the reference lists of included studies and some journals. Studies comparing conventional and skeletal anchorage for molar distalization in Angle class I or II malocclusions were assessed. Presence of periodontal disease, second or third molar extraction and application of tooth accelerating methods led to exclusion of studies. Generic-inverse variance approach was used for meta-analysis by use of the mean difference and random-effect model. Risk of bias was evaluated in included studies.

RESULTS

A total of 1996 articles were found; of which, 1991 were excluded. The mean amounts of molar distalization/tipping in skeletal anchorage and conventional anchorage groups were 5.35mm/8.44° and 4.25mm/8.31°, respectively, which were not significantly different. The mean amounts of premolar movement in skeletal anchorage and conventional anchorage groups were -0.96mm and +2.21mm, respectively, which was statistically significant (P=0.004). Duration of treatment in skeletal anchorage and conventional anchorage groups was 8.23 months and 7.95 months, respectively, which were significantly different (P=0.0001). Risk of bias was assessed to be high.

CONCLUSION

The conventional and skeletal anchorage devices were not significantly different in terms of the amount of molar distalization/tipping. However, the anchorage loss was lower in the skeletal anchorage group. The treatment time was shorter in the conventional anchorage group. More studies with proper design are required.

Maxillary molar distalization with miniscrew-supported appliances in Class II malocclusion: A systematic review

OBJECTIVES

To evaluate the quantitative effects of miniscrew supported appliances for maxillary molar distalization in Class II malocclusion.

MATERIALS AND METHODS

The systematic search included MEDLINE, EMBASE, CINAHL, PsychINFO, Scopus, and key journals and review articles. The date of the last search was January 30, 2017. Methodological quality of the retrospective studies was graded by means of the Quality Assessment Tool for Quantitative Studies, developed for the Effective Public Health Practice Project (EPHPP) and prospective studies by means of Newcastle-Ottawa Scale.

RESULTS

In total, 298 studies were identified for screening, and 14 studies were eligible. The Quality Assessment Tool for Quantitative Studies rated all of the four included retrospective studies as moderate. The Newcastle-Ottawa Scale rated seven studies as high quality and three studies as low quality. The mean molar distalization values varied from 1.8 mm to 6.4 mm. Mean distal tipping of molars varied from 1.65° to 11.3°. The mean distal movement of premolars and incisors varied from 1.75 mm to 5.4 mm and 0.1 mm to 2.7 mm, respectively.

CONCLUSIONS

Miniscrew-supported appliances are effective in molar distalization with distal movement of premolars with minimal anchorage loss and distal tipping of the molar teeth.

Assessment of agreement between molar landmarks: Repeatability, reproducibility, and comparability

INTRODUCTION

The aims of this research were to test the repeatability and reproducibility of measurements obtained by different molar landmarks and to determine whether the treatment changes measured by them are comparable.

MATERIALS

Pretreatment (T0) and postdistalization (T1) lateral cephalograms of 40 patients with a Class II molar relationship were used. Using the mesial cusp tip, distal crown contour, and centroid, 6 linear and 3 angular measurements were evaluated. The intraexaminer and interexaminer reliabilities were assessed with the Bland-Altman method. The T0 to T1 differences were compared by analysis of variance, followed by multiple comparisons with the Bonferroni adjustment.

RESULTS

The greatest intraexaminer agreement intervals were correlated with centroid for tipping and vertical movement, and with distal crown contour for anteroposterior movement at T0 and T1. The narrowest interexaminer agreement intervals were observed with mesial cusp tip for all measurements and comparisons at both time points, except for the anteroposterior measurements at T1. Statistical significance was observed between the measurements made with mesial cusp tip and distal crown contour for tipping and with mesial cusp tip and centroid for distalization. For vertical movement, the treatment changes were statistically significantly greater with distal crown contour.

CONCLUSIONS

Mesial cusp tip was the most repeatable and reproducible landmark. Clinically unimportant differences were found in some comparisons of treatment changes obtained by different landmarks.