Noncompliance maxillary molar distalization with the first class appliance: a randomized controlled trial

Molar Distalization by Clear Aligners with Sequential Distalization Protocol: A Systematic Review and Meta-Analysis

INTRODUCTION

With the popularity of clear aligners, the sequential distalization protocol has been more commonly used for molar distalization. However, the amount of molar distalization that can be achieved, as well as the accompanying side effects on the sagittal dimension, are unclear.

METHODS

Registered with PROSPERO (CRD42023447211), relevant original studies were screened from seven databases (MEDLINE [PubMed], EBSCOhost, Web of Science, Elsevier [SCOPUS], Cochrane, LILACS [Latin American and Caribbean Health Sciences Literature], and Google Scholar) supplemented by a manual search of the references of the full-reading manuscripts by two investigators independently. A risk of bias assessment was conducted, relevant data were extracted, and meta-analysis was performed using RStudio.

RESULTS

After the screening, 13 articles (11 involving maxillary distalization, two involving mandibular distalization) met the inclusion criteria. All studies had a high or medium risk of bias. The meta-analysis revealed that the maxillary first molar (U6) mesiobuccal cusp was distalized 2.07 mm [1.38 mm, 2.77 mm] based on the post-distalization dental model superimposition, and the U6 crown was distalized 2.00 mm [0.77 mm, 3.24 mm] based on the post-treatment lateral cephalometric evaluation. However, the U6 mesiobuccal root showed less distalization of 1.13 mm [-1.34 mm, 3.60 mm], indicating crown distal tipping, which was validated by meta-analysis (U6-PP angle: 2.19° [1.06°, 3.33°]). In addition, intra-arch anchorage loss was observed at the post-distalization time point (U1 protrusion: 0.39 mm [0.27 mm, 0.51 mm]), which was corrected at the post-treatment time point (incisal edge-PTV distance: -1.50 mm [-2.61 mm, -0.39 mm]).

CONCLUSION

About 2 mm maxillary molar distalization can be achieved with the sequential distalization protocol, accompanied by slight molar crown distal tipping. Additional studies on this topic are needed due to the high risk of bias in currently available studies.

Retrospective investigation of the 3D effects of the Carriere Motion 3D appliance using model and cephalometric superimposition

OBJECTIVES

Carriere Motion 3D™ appliance (CMA) represents a method for molar distalization and correction of class II malocclusion. The aim was to investigate the 3D effects of the CMA by superimposing digital models and cephalometric X-rays.

MATERIALS AND METHODS

We retrospectively examined 16 patients treated with CMA in combination with class II elastics. We compared digitized models and cephalometric X-rays of records taken before therapy and after the removal of CMA. The records were superimposed to assess the skeletal and dentoalveolar changes. The results of the cephalometric X-ray analysis were compared to an untreated age- and gender-matched sample.

RESULTS

Class II occlusion was corrected after 11.85 ± 4.70 months by 3.45 ± 2.33 mm. The average distalization of the upper first molars was 0.96 ± 0.80 mm. The analysis of the cephalometric X-rays confirmed a distalization of the upper first molars with distal tipping and revealed a mesialization of the lower first molars of 1.91 ± 1.72 mm. Importantly, CMA resulted in a mild correction of the skeletal class II relationship (ANB: - 0.71 ± 0.77°; Wits: - 1.99 ± 1.74 mm) and a protrusion of the lower incisors (2.94 ± 2.52°). Compared to the untreated control group, there was significant distalization of the upper first molars and canines with mesialization and extrusion of the lower first molars.

CONCLUSION AND CLINICAL RELEVANCE

CMA is an efficient method for treating class II malocclusions. However, the class II correction is only partially caused by a distalization of the upper molars.

Dentoskeletal and soft-tissue changes of class II malocclusion treatment with modified first class appliances: a prospective clinical trial

Background/Objectives

Intraoral distalizers are effective and conservative alternatives for Class II malocclusion treatment. However, the literature is still controversial regarding the effects of using skeletal anchorage in intraoral distalizers with different designs. The aim of this study is to compare dentoskeletal and soft-tissue changes of Class II malocclusion patients treated with three types of First Class (FC) distalizers.

Materials/Methods

The sample of this prospective clinical trial included 30 consecutive patients divided into three groups: G1—FC conventionally anchored; G2—FC skeletally anchored Type 1; G3—FC skeletally anchored Type 2. Each group consisted of 10 patients. Lateral cephalograms were analyzed in two stages: at pre-treatment (T0) and after distalization (T1). The radiographs were digitized and analyzed using the software Dolphin Imaging 11.5. Comparisons of treatment changes between groups (T1–T0) were performed using one-way analysis of variance (ANOVA), followed by the Tukey test.

Results

Patients treated with the conventionally anchored FC showed significantly greater incisors protrusion and labial inclination, second premolars mesial inclination and mesialization than the FCs skeletally anchored. No differences were observed regarding the amount of molar distalization and molar angulation between groups.

Limitations

It can be considered that the limitation of this study lies in its non-randomized design.

Conclusions/Implications

First Class distalizers with conventional and skeletal anchorage are effective alternatives for Class II molar distalization. Distalization associated with indirect skeletal anchorage reduce the undesirable effects observed in the incisors and premolars during distalization when compared to distalization conventionally anchored.

Class II Correction with Microimplant Supported Molar Distalization: A Report of Two Cases

Introduction

Orthodontic treatment of class II malocclusion with conventional treatment modalities can be challenging for the clinician. The use of microimplants to obtain absolute anchorage has become very popular in recent years especially in noncompliant patients. Microimplants are convenient, save time, and produce good treatment results with no need for patient cooperation. A special approach for class II correction with microimplant supported molar distalization has been developed by the authors and is illustrated through two clinical cases. Description. For each clinical case, 0.022” preadjusted brackets were bonded on both arches except on the maxillary first and second premolars with bands on the first and second molars. After leveling and alignment, a 0.017^” × 0.025^” stainless steel wire was fitted on the upper arch, and two microimplants were placed bilaterally between the maxillary second premolar and the first molar. Open coil springs were inserted in the upper archwire on both sides and compressed via a steel ligature on sliding hooks to the microimplants pushing distally simultaneously the first and second maxillary molars. En-masse retraction of the maxillary anterior teeth was then carried out on a 0.019^” × 0.025^” stainless steel closing loop archwire while the posterior segment was anchored to the microimplant with a steel ligature to the first premolar.

Results

Class I canine and molar relationship were achieved, and an ideal occlusion was established. Both ANB and FMA angles decreased by 1° due to the counterclockwise rotation effect of the maxillomandibular complex. Skeletal and dental results remained stable three years later.

Conclusion

Maxillary molar distalization using coils and buccal microimplants can be regarded as an effective technique in a relatively short time and might be considered a breakthrough in the treatment of class II malocclusions. Microimplants enable the clinician to perform a nonextraction treatment in noncompliant patients who would alternatively be treated only with extractions.

Match of the Bimaxillary Basal Bone Arches and Its Variations among Individuals

INTRODUCTION

This study is aimed at illustrating the bimaxillary basal bone contours, to clarify the match of the basal bone arches of the upper and lower, especially the posterior segments, including the second molar and retromolar region.

METHODS

Based on 100 cone-beam computed tomography (CBCT) images (50 males and 50 females), we obtained 100 pairs of basal bone arches, which were the horizontal inner cortex contours passing the furcation of the first molar paralleled to the lower occlusal plane. The Generalized Procrustes Analysis (GPA) was applied to depict average contours and calculate the ratio and difference width of both upper and lower dental arches in different positions. Variations of the basal bone morphology among individuals were revealed using Principal Component Analysis (PCA).

RESULTS

The width discrepancy occurred at 7-7 segment (male: upper 65.62 mm and lower 68.81 mm and female: upper 62.98 mm and lower 68.38 mm) and the retromolar region (male: upper 64.67 mm and lower 71.96 mm and female: upper 62.34 mm and lower 71.44 mm). The ratio (p = 0.006) and difference value (p = 0.009) of 7-7 segment and the ratio of retromolar region (p = 0.044) differed in genders. Setting 2 mm overjet, the upper basal bone arch was wider than the lower by approximate 2 mm on both sides, except the second molar and retromolar region. According to PCA, the variation of basal bone arches appeared mainly at terminal segments.

CONCLUSIONS

For both male and female, the bimaxillary basal bone matched except terminal segments. Mismatch of female bimaxillary posterior basal bone was more pronounced than male. The basal bone arches of male were wider and longer than that of female.

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.

Sagittal, rotational and transverse changes with three intraoral distalization force systems: Jones jig, distal jet and first class

Background

To compare the maxillary dentoalveolar changes of patients treated with three distalization force systems: Jones Jig, Distal Jet and First Class appliances, using digitized models.

Material and Methods

The retrospective sample comprised 118 digitized models of 59 patients with Class II malocclusion divided into three groups: Group 1 consisted of 22 patients treated with the Jones Jig appliance; Group 2 consisted of 20 patients treated with the Distal Jet, and Group 3 comprised 17 patients treated with the First Class appliance. Pretreatment and post-distalization plaster models of all patients were digitized and evaluated with OrthoAnalyzerTM software. The pretreatment and post-distalization variables regarding sagittal, rotational and transverse changes were compared by the One-way Analysis of Variance (ANOVA) and Kruskal-Wallis tests, depending on normality.

Results

All appliances presented similar amounts of distalization. The Distal Jet appliance promoted significantly smaller mesial displacement of premolars and greater expansion of posterior teeth. The First Class presented the smallest rotation of the maxillary molars and treatment time.

Conclusions

The distalizers were effective in correcting Class II molar relationship, however, a palatal force seems to provide fewer undesirable effects. Additionally, the degree of rotation and expansion was associated with the side of force application.

Key words:Malocclusion, Angle Class II, Orthodontics, Corrective, Distalizers.

Characteristics and Dynamics of Full Arch Distalization Using Transpalatal Arches with Midpalatal and Interradicular Miniscrews as Temporary Anchorage Devices: A Preliminary Finite Element Analysis

INTRODUCTION

Miniscrews have proved quite effective in fixed orthodontic treatment. They can be placed in areas like palatal interradicular zones or midpalatal suture. Despite the value of these methods and their ever-increasing use, their characteristics are not assessed before when implanted in palatal interradicular areas or in the midpalatal suture. We aimed to assess, for the first time, the dynamics of full arch distalization using such miniscrews.

METHODS

A 3D model of maxilla with all permanent dentition was created from a CT scan volume. Tissues were segmented and differentiated. Afterward, miniscrews and appliances were designed, and the whole model was registered within a finite element analysis software by assigning proper mechanical properties to tissues and orthodontic appliances. The full arches were distalized using transpalatal arches with miniscrews as anchorage devices (in two different models). The extents of stresses and patterns of movements of various elements (teeth, miniscrews, appliances, tissues) were estimated. Results and Conclusions. Comparing the two models, it is obvious that in both models, the stress distribution is the highest in the TPA arms and the head of the miniscrew where the spring is connected. In comparison with the displacement in the X-axis, the "mesial in" rotation is seen in the first molar of both models. But there is one exception and that is the "mesial out" rotation of the right second molar. In all measurements, the amount of movement in Model 2 (with palatal interradicular miniscrews) is more than that in Model 1 (with midpalatal miniscrew). In the Y-axis, more tipping is seen in Model 2, especially the anterior teeth (detorque) and the first molar, but in Model 1, bodily movement of the first molar is more evident. Along the Z-axis, the mesial intrusion of the first molar and the distal extrusion of this tooth can be seen in both models. Again, the displacement values are higher in the second model (with interradicular miniscrews). In comparison with micromotion and stress distribution of miniscrews, in Model 1, maximum stress and micromotion is observed at the head of the miniscrew where it is attached to the spring. Of course, this amount of micromotion increases over time. The same is true for Model 2, but with a lower micromotion. As for the amount of stress, the stress distribution in both miniscrews of both models is almost uniform and rather severe.

Time of maxillary molar distalization with non-compliance intraoral distalizing appliances: a meta-analysis

BACKGROUND/OBJECTIVE

To assess the mean maxillary molar distalization time with non-compliance intraoral distalizing appliances.

SEARCH METHODS AND SELECTION CRITERIA

Database search included PubMed, Web of Science, Scopus, The Cochrane Library, Lilacs, and a partial grey literature through Google Scholar and OpenGrey. The search was performed until May 2017 and updated on February 2019, without limitations regarding publication year or language. Controlled clinical trials (randomized and non-randomized prospective studies) reporting duration of maxillary molar distalization of Class II patients treated with intraoral distalizers were included.

DATA COLLECTION AND ANALYSIS

For the trials' quality assessment, the Cochrane Risk of Bias tool and the Cochrane Collaboration's ROBINS-I tool were used for the randomized controlled trials and non-randomized prospective studies, respectively. Database research, risk of bias (RoB) assessment, and extraction of data were performed by two independent investigators, with inclusion of a third reviewer, if disagreements emerged. Data was combined through a random-effects meta-analysis. Subgroup analyses regarding side of force application, type of anchorage, amount of molar distalization, and sensitivity analysis comparing study designs were also performed. Quality of evidence was assessed using the GRADE and SORT approaches.

RESULTS

Nine studies were included in the qualitative analysis; however, a meta-analysis was performed with only four studies, due to the presence of high RoB in the other studies. The random-effects meta-analysis assumes that the mean distalization time with distalizers is 8.34 months (95% confidence interval: 6.10, 10.58). Another meta-analysis was performed to evaluate the relationship between distalization time and the type of anchorage (conventional or skeletal), resulting in no significant difference. Both meta-analyses presented low-quality evidence.

LIMITATIONS

The major limitation of this meta-analysis is the fact that distalization time can be affected by a great range of factors.

CONCLUSIONS AND IMPLICATIONS

Correction of a half-to-full cusp Class II molar relationship with intraoral distalizers can be achieved in 8.34 months, and this distalization time may not be affected by the kind of anchorage used.

REGISTRATION

The protocol for this systematic review was based on the Cochrane Handbook for Systematic Reviews of Interventions 5.1.0 and was registered at PROSPERO database (http://www.crd.york.ac.uk/PROSPERO/display_record.php?ID=CRD42017068737). This systematic review is reported according to the PRISMA statement.

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.

Effect of local administration of simvastatin on orthodontic tooth movement in rabbits

INTRODUCTION

Maintaining tooth anchorage during orthodontic treatment has challenged orthodontists and threatening the success of some orthodontic therapy. The objective of this study was to evaluate the effect of local administration of simvastatin on orthodontic tooth movement.

METHODS

Nickel-titanium coil springs were used to induce orthodontic tooth movement in 10 white New Zealand rabbits for 21 days. A split-mouth design was implemented where one mandibular quadrant received local administration of simvastatin and the corresponding mandibular quadrant received control vehicle solution on a weekly basis. Magnitudes of tooth movement were measured on 3-dimensional models of the experimental teeth. Animals were killed at the end of the experimental period to allow histomorphometric analysis of alveolar bone modeling.

RESULTS

The total magnitude of tooth movement in the quadrant receiving simvastatin was significantly less than that in the quadrant receiving control vehicle solution. Local administration of simvastatin resulted in a significant percentage of inhibition of tooth movement of 39.8 ± 22.6%. Histomorphometric analysis revealed a significant reduction in the numbers of osteoclasts and areas of active bone-resorptive lacunae hindering bone resorption processes in the quadrant receiving simvastatin.

CONCLUSIONS

Local administration of simvastatin can reduce the rate and magnitude of orthodontic tooth movement. Moreover, local administration of simvastatin diminishes bone resorption processes associated with orthodontic tooth movement reducing the number of osteoclasts and the subsequent area of active bone resorption.

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.

Bilateral en-masse distalization of maxillary posterior teeth with skeletal anchorage: a case report

Objective:

The aim of this study was to introduce a new method for bilateral distal movement of the entire maxillary posterior segment.

Case report:

A 17-year-old girl with Class I skeletal malocclusion (end-to-end molar relationships, deviated midline and space deficiency for left maxillary canine) was referred for orthodontic treatment. She did not accept maxillary first premolars extraction. A modified Hyrax appliance (Dentaurum Ispringen, Germany) was used for bilateral distalization of maxillary posterior teeth simultaneously. Expansion vector was set anteroposteriorly. Posterior legs of Hyrax were welded to first maxillary molar bands. All posterior teeth on each side consolidated with a segment of 0.017 × 0.025-in stainless steel wire from the buccal side. Anterior legs of Hyrax were bent into eyelet form and attached to the anterior palate with two mini-screws (2 × 10 mm) (Jeil Medical Corporation Seoul, South Korea). Hyrax opening rate was 0.8 mm per month. Lateral cephalometric radiographs were used to evaluate the extent of distal movement. 3.5-mm distalization of posterior maxillary teeth was achieved in five months.

Results:

A nearly bodily distal movement without anchorage loss was obtained.

Conclusion:

The mini-screw-supported modified Hyrax appliance was found to be helpful for achieving en-masse distal movement of maxillary posterior teeth.

Comparison of transverse dental changes induced by the palatally applied Frog appliance and buccally applied Karad's integrated distalizing system

Objective

To compare the transverse dental changes induced by the palatally applied Frog appliance and buccally applied Karad's integrated distalizing system (KIDS).

Methods

We evaluated the pre- and post distalization orthodontic models of 39 patients, including 19 treated using the Frog appliance, which is palatally positioned (Frog group), and 20 treated using KIDS, which is buccally positioned (KIDS group). Changes in intermolar and interpremolar distances and the amount of maxillary premolar and molar rotation were evaluated on model photocopies. Wilcoxon and Mann-Whitney U tests were used for statistical evaluations. A p-value of < 0.05 was considered statistically significant.

Results

Significant distopalatal rotation of premolars and distobuccal rotation of molars were observed in Frog group (p < 0.05), while significant distopalatal rotation of molars (p < 0.05), with no significant changes in premolars, was observed in KIDS group. The amount of second premolar and first molar rotation was significantly different between the two groups (p < 0.05 and p < 0.001, respectively). Furthermore, expansion in the region of the first molars and second premolars was significantly greater in KIDS group than in Frog group (p < 0.001 for both).

Conclusions

Our results suggest that the type and amount of first molar rotation and expansion vary with the design of the distalization appliance used.

Reinforcement of anchorage during orthodontic brace treatment with implants or other surgical methods

BACKGROUND

The term anchorage in orthodontic treatment refers to methods of controlling unwanted tooth movement. This is provided either by anchor sites within the mouth, such as the teeth and the palate, or from outside the mouth (headgear). Recently, new methods of providing anchorage have been developed using orthodontic implants which are surgically inserted into the bone in the mouth. This is termed surgical anchorage. This is an update of a Cochrane review first published in 2007.

OBJECTIVES

To assess the effects of surgical anchorage techniques compared to conventional anchorage in the prevention of unwanted tooth movement in patients undergoing orthodontic treatment by evaluating the mesiodistal movement of upper first molar teeth. A secondary objective was to compare the effects of one type of surgical anchorage with another.

SEARCH METHODS

We searched the Cochrane Oral Health Group's Trials Register (to 28 October 2013), the Cochrane Central Register of Controlled Trials (CENTRAL) (The Cochrane Library 2013, Issue 9), MEDLINE via OVID (1946 to 28 October 2013) and EMBASE via OVID (1980 to 28 October 2013). We handsearched key international orthodontic and dental journals, and searched the trial database ClinicalTrials.gov and the World Health Organization (WHO) International Clinical Trials Registry Platform for ongoing and unpublished studies.

SELECTION CRITERIA

Randomised controlled trials comparing surgical anchorage with conventional anchorage in orthodontic patients. Trials comparing two types of surgical anchorage were also included.

DATA COLLECTION AND ANALYSIS

At least two review authors independently and in duplicate extracted data and carried out risk of bias assessments. We contacted study authors to clarify aspects of study design and conduct, and to obtain unreported data.

MAIN RESULTS

Fourteen new studies were added in this update resulting in a total of 15 studies reporting data from 561 randomised patients. The studies were conducted in Europe, India, China, South Korea and the USA. The age range of patients was commonly restricted to adolescents or young adults, however the participants of two studies were from a much wider age range (12 to 54 years). The distribution of males and females was similar in eight of the studies, with a predominance of female patients in seven studies.Eight studies were assessed to be at high overall risk of bias; six studies at unclear risk of bias; one study at low risk of bias.Ten studies with 407 randomised and 390 analysed patients compared surgical anchorage with conventional anchorage for the primary outcome of mesiodistal movement of upper first molars. We carried out a random-effects model meta-analysis for the seven studies that fully reported this outcome. There was strong evidence of an effect of surgical anchorage on this outcome. Compared with conventional anchorage, surgical anchorage was more effective in the reinforcement of anchorage by 1.68 mm (95% confidence interval (CI) -2.27 mm to -1.09 mm; seven studies, 308 participants analysed) with moderate quality of evidence (one study at high overall risk of bias, five studies at unclear risk of bias, one study at low risk of bias). This result should be interpreted with some caution, however, as there was a substantial degree of heterogeneity for this comparison. There was no evidence of a difference in overall duration of treatment between surgical and conventional anchorage (-0.15 years; 95% CI -0.37 years to 0.07 years; three studies, 111 analysed patients) with low quality of evidence (one study at high overall risk of bias and two studies at unclear risk of bias). Information on patient-reported outcomes such as pain and acceptability was limited and inconclusive.When direct comparisons were made between two types of surgical anchorage, there was a lack of evidence to suggest that any one technique was better than another.No included studies reported adverse effects.

AUTHORS' CONCLUSIONS

There is moderate quality evidence that reinforcement of anchorage is more effective with surgical anchorage than conventional anchorage, and that results from mini-screw implants are particularly promising. While surgical anchorage is not associated with the inherent risks and compliance issues related to extraoral headgear, none of the included studies reported on harms of surgical or conventional anchorage.

Maxillary molar distalization with first class appliance

Non-extraction treatment has gained popularity for corrections of mild-to-moderate class II malocclusion over the past few decades. The distalization of maxillary molars is of significant value for treatment of cases with minimal arch discrepancy and mild class II molar relation associated with a normal mandibular arch and acceptable profile. This paper describes our experience with a 16-year-old female patient who reported with irregularly placed upper front teeth and unpleasant smile. The patient was diagnosed to have angles class II malocclusion with moderate maxillary anterior crowding, deep bite of 4 mm on a skeletal class II base with an orthognathic maxilla and retrognathic mandible and normal growth pattern. She presented an ideal profile and so molar distalization was planned with the first-class appliance. Molars were distalised by 8 mm on the right and left quadrants and class I molar relation achieved within 4 months. The space gained was utilised effectively to align the arch and establish a class I molar and canine relation.

Orthodontic treatment for distalising upper first molars in children and adolescents

BACKGROUND

When orthodontic treatment is provided with fixed appliances, it is sometimes necessary to move the upper molar teeth backwards (distalise) to create space or help to overcome anchorage requirements. This can be achieved with the use of extraoral or intraoral appliances. The most common appliance is extraoral headgear, which requires considerable patient co-operation. Further, reports of serious injuries have been published. Intraoral appliances have been developed to overcome such shortcomings. The comparative effects of extraoral and intraoral appliances have not been fully evaluated.

OBJECTIVES

To assess the effects of orthodontic treatment for distalising upper first molars in children and adolescents.

SEARCH METHODS

We searched the following electronic databases: the Cochrane Oral Health Group's Trials Register (to 10 December 2012), the Cochrane Central Register of Controlled Trials (CENTRAL) (The Cochrane Library 2012, Issue 11), MEDLINE via OVID (1946 to 10 December 2012) and EMBASE via OVID (1980 to 10 December 2012). No restrictions were placed on the language or date of publication when searching the electronic databases.

SELECTION CRITERIA

Randomised clinical trials involving the use of removable or fixed orthodontic appliances intended to distalise upper first molars in children and adolescents.

DATA COLLECTION AND ANALYSIS

We used the standard methodological procedures expected by The Cochrane Collaboration. We performed data extraction and assessment of the risk of bias independently and in duplicate. We contacted authors to clarify the inclusion criteria of the studies.

MAIN RESULTS

Ten studies, reporting data from 354 participants, were included in this review, the majority of which were carried out in a university dental hospital setting. The studies were published between 2005 and 2011 and were conducted in Europe and in Brazil. The age range of participants was from nine to 15 years, with an even distribution of males and females in seven of the studies, and a slight predominance of female patients in three of the studies. The quality of the studies was generally poor; seven studies were at an overall high risk of bias, three studies were at an unclear risk of bias, and we judged no study to be at low risk of bias.We carried out random-effects meta-analyses as appropriate for the primary clinical outcomes of movement of upper first molars (mm), and loss of anterior anchorage, where there were sufficient data reported in the primary studies. Four studies, involving 159 participants, compared a distalising appliance to an untreated control. Meta-analyses were not undertaken for all primary outcomes due to incomplete reporting of all summary statistics, expected outcomes, and differences between the types of appliances. The degree and direction of molar movement and loss of anterior anchorage varied with the type of appliance. Four studies, involving 150 participants, compared a distalising appliance versus headgear. The mean molar movement for intraoral distalising appliances was -2.20 mm and -1.04 mm for headgear. There was a statistically significant difference in mean distal molar movement (mean difference (MD) -1.45 mm; 95% confidence interval (CI) -2.74 to -0.15) favouring intraoral appliances compared to headgear (four studies, high or unclear risk of bias, 150 participants analysed). However, a statistically significant difference in mean mesial upper incisor movement (MD 1.82 mm; 95% CI 1.39 to 2.24) and overjet (fixed-effect: MD 1.64 mm; 95% CI 1.26 to 2.02; two studies, unclear risk of bias, 70 participants analysed) favoured headgear, i.e. there was less loss of anterior anchorage with headgear. We reported direct comparisons of intraoral appliances narratively due to the variation in interventions (three studies, high or unclear risk of bias, 93 participants randomised). All appliances were reported to provide some degree of distal movement, and loss of anterior anchorage varied with the type of appliance.No included studies reported on the incidence of adverse effects (harm, injury), number of attendances or rate of non-compliance.

AUTHORS' CONCLUSIONS

It is suggested that intraoral appliances are more effective than headgear in distalising upper first molars. However, this effect is counteracted by loss of anterior anchorage, which was not found to occur with headgear when compared with intraoral distalising appliance in a small number of studies. The number of trials assessing the effects of orthodontic treatment for distilisation is low, and the current evidence is of low or very low quality.

Miniscrew design and bone characteristics: an experimental study of primary stability

INTRODUCTION

The purpose of this study was to evaluate the correlations between bone characteristics, orthodontic miniscrew designs, and primary stability.

METHODS

Four different miniscrews were placed in pig ribs. The miniscrews were first scanned with a scanning electron microscope to obtain measurable images of their threads. Subsequently, the maximum insertion torque of the screws and the maximum load value in the pullout force tests were measured; furthermore, bone specimen characteristics were analyzed by using cone-beam computed tomography. For each bone sample, the insertion site cortical thickness as well as both cortical and marrow bone density were evaluated. The nonparametric Kendall rank correlation (tau) was used to evaluate the strength of the associations among the characteristics measured. The nonparametric Kruskall-Wallis test was used to evaluate the differences among the groups, and post-hoc comparisons were assessed by using the Nemenyi-Damico-Wolfe-Dunn test.

RESULTS

A significant dependence was found between pitch and maximum insertion torque (tau, -0.49). Positive correlations were also found between pullout force and maximum insertion torque (tau, 0.64), cortical thickness (tau, 0.36), and marrow bone density (tau, 0.35).

CONCLUSIONS

In this in-vitro experimental study, strong correlations were observed among miniscrew geometry, bone characteristics, and primary stability.

Distalization pattern of the maxillary arch depending on the number of orthodontic miniscrews

OBJECTIVE

To determine the effects of linear force vector(s) from interradicular miniscrews on the distalization pattern of the maxillary arch in adult Class II patients.

MATERIALS AND METHODS

Twenty-five adult patients with mild to moderate Class II dentition and minimal crowding were collected. Either single (group A, n  =  12) or dual (group B, n  =  13) miniscrews were inserted on the posterior interradicular area to deliver a distalizing force to the main archwire. The displacement patterns of maxillary incisors and molars were measured and compared.

RESULTS

  Significant distalization in the molars and incisors was shown in both groups. Significantly greater distalization and intrusion of the first molar and intrusive displacement of the incisor, together with significant reduction of the mandibular plane, were noted in group B, in contrast to the rotation of the occlusal plane in group A.

CONCLUSIONS

Interradicular miniscrews predictably induced total arch distalization, leading to the correction of Class II. Additional miniscrews in the premolar area appear to facilitate intrusion and distalization of the entire arch according to the position of the force vectors.