Factors predisposing to maxillary anchorage loss: a retrospective study of 1403 cases

Soft tissue changes with skeletal anchorage in comparison to conventional anchorage protocols in the treatment of bimaxillary proclination patients treated with premolar extraction : A systematic review

PURPOSE

This review systematically evaluates the evidence related to comparisons between skeletal and conventional anchorage protocols in the treatment of bimaxillary proclination patients who underwent premolars extraction with respect to soft tissue profile changes, treatment duration and three-dimensional (3D) soft tissue changes.

METHODS

Electronic database search and hand search with no language limitations were conducted in the Cochrane Library, PubMed, Ovid, Web of Science, Scopus and ClinicalTrials.gov. The selection criteria were set to include studies with patients aged 13 years and above requiring extractions of upper and lower first premolars to treat bimaxillary proclination with high anchorage demand. Risk of bias assessment was undertaken with Cochrane's Risk Of Bias tool 2.0 (ROB 2.0) for randomised controlled trials (RCTs) and ROBINS‑I tool for nonrandomised prospective studies. The Grading of Recommendations, Assessment, Development and Evaluation (GRADE) approach was used for quality assessment. Results were summarised qualitatively; no meta-analysis was conducted.

RESULTS

Two RCTs and two nonrandomised prospective studies were included. According to the GRADE approach, there is low to very low quality of evidence that treatment using mini-implant anchorage may significantly change nasolabial angle, upper and lower lip procumbence, and facial convexity angle compared to treatment with conventional anchorage. Similarly, very low quality evidence exists showing no differences in treatment duration between treatments with skeletal or conventional anchorage.

CONCLUSIONS

The overall existing evidence regarding the effect of anchorage protocols on soft tissue changes in patients with bimaxillary protrusion and premolar extraction treatment plans is of low quality.

TRIAL REGISTRATION NUMBER

PROSPERO CRD42020216684.

Hard and soft tissue shape variation and changes in Class II division 1 malocclusion during orthodontic treatment: a geometric morphometric analysis

BACKGROUND

This study aims to determine the hard and soft tissue shape variation and its changes in Class II division 1 malocclusion before and after orthodontic treatment using Geometric Morphometric Analysis.

METHODS

This retrospective study included 141 pre-treatment and near-end treatment lateral cephalometric radiographs of Class II division 1 malocclusion patients aged 16-40 years with a skeletal II pattern (ANB > 4o). 32 landmarks in Cartesian coordinates were created and identified using MorphoJ software to establish a shape analysis.

RESULTS

The vertical dimensions (hypodivergent to hyperdivergent facial profiles) showed the largest variation in the general shape of hard and soft tissue, followed by the anteroposterior dimensions (mild to severe skeletal II patterns). Variations of lip shape (long to short), lip protuberance (everted to inverted), and nasolabial angle (obtuse to acute) were present. Orthodontic treatment affected the shape of the hard and soft tissue significantly (p < 0.0001). T2 showed significant uprighting of upper incisors (17.5o) and lower incisors (3.7o), improved NLA (8o), an increase in upper lip thickness (1.5 mm), and a reduction in lower lip thickness (0.7 mm) (p < 0.05).

CONCLUSION

Vertical and anteroposterior shape variations were found. Orthodontic treatment had an impact on both hard and soft tissue shapes. Hence, understanding both the hard and soft tissue shape variations and the orthodontic treatment changes is crucial for an accurate diagnosis and treatment plan to achieve a successful outcome and excellent patient satisfaction.

Mesial movement of maxillary first molars and vertical dimensional changes in orthodontic extraction treatment for patients with different facial morphology

Objectives: Primarily, to compare anchorage loss and changes in mandibular plane (MP) angle, overbite, and amount of horizontal, vertical, and angular movements of maxillary incisors in groups of hypodivergent, hyperdivergent, and normodivergent patients. Secondarily, to analyze the relationship between those factors. Methods: Pre- and post-treatment cephalograms of 89 patients treated with extraction of four bicuspids or two maxillary bicuspids were analyzed. The sample was divided into three groups based on their facial pattern measured by SN-MP angle (hypodivergent: < 270, hyperdivergent: >380, and normodivergent: 270-380). Linear and angular measurements included the distances of U1 tip and U6 mesial height of contour to Y-axis (i.e., line perpendicular to the X-axis, passing through Sella turcica), distance of U1 tip to Sella on X-axis, overbite, angulation of U1 to palatal plane, and SN-MP and ANB angles. Inferential statistics included one-way ANOVA, Chi-square test, independent t-test, and Pearson’s correlation coefficients. Results: Facial morphology did not primarily affect anchorage loss, because other factors such as crowding, severity of Class II molar relationship, and extraction modality played more impactful role (P< 0.01). Change in mandibular plane angle was neither influenced by, nor correlated with, initial facial morphology or anchorage loss (P> 0.05). Positive change in overbite was significantly correlated with facial pattern, incisor extrusion and retroclination (r= 0.30, 0.44, and -0.35, respectively, P< 0.01). Conclusion: Anchorage loss in extraction orthodontic treatment is not influenced primarily by initial facial morphology. Anchorage loss is not significantly associated with MP angle reduction. Change in overbite can be achieved through incisor extrusion and retroclination.

Analysis of canine retraction and anchorage loss in different facial types with and without piezocision: a split-mouth-design, randomized clinical trial

OBJECTIVES

To investigate canine retraction (CR) and anchorage loss (AL) among average facial height (AFH) and high facial height subjects (HFH) with or without piezocision surgery (PS).

MATERIALS AND METHODS

This was a split-mouth, randomized clinical trial. Twenty-three females (aged 19.05 ± 2.95 years) who presented with Class II division I malocclusion requiring bilateral maxillary extraction and who fulfilled eligibility criteria were included and categorized into two groups: AFH (12 participants) and HFH (11 participants). Atraumatic extractions were performed 10 weeks following bonding. Before space closure, impressions were taken to fabricate models, which were scanned to generate digital models. Each participant had PS on the randomly assigned side. Space closure was undertaken using 100-g nickel-titanium coil closing springs on 0.019 × 0.025-inch stainless steel archwire. Digital models were collected 6 and 12 weeks post-PS. They were superimposed using reliable reference points and a region of interest on the palate, and crown movements were analyzed in three dimensions.

RESULTS

Three months post-PS, intergroup comparisons showed that rates of CR for control sides (mean = 1.88 ± 0.83 mm for AFH, mean = 1.76 ± 0.62 mm for HFH) and intervention sides (mean = 1.48 ± 0.74 mm for AFH, mean = 1.40 ± 0.85 mm for HFH) were not significantly different. AL was not significantly different (P > .05) between groups.

CONCLUSION

Regardless of whether the patient underwent PS, CR and AL rates for AFH and HFH patients were not significantly different.

Risk factors for midcourse correction during treatment of first series of aligners with Invisalign

INTRODUCTION

This study aimed to analyze risk factors for midcourse correction (MC) during the first series of aligners in treatments with Invisalign (Align Technology, Santa Clara, Calif).

METHODS

Three hundred and fourteen patients treated with Invisalign were divided into MC and non-midcourse correction groups according to whether they completed the first series of aligners. Differences between these groups were compared with independent sample t tests, chi-square tests, and Wilcoxon rank sum tests. A multivariate logistic regression analysis was performed to identify independent risk factors, including gender, age, extraction treatment, interproximal reduction, correction steps (steps in first series treatment), overbite, overjet, the curve of Spee, Angle classification, and crowding.

RESULTS

The percentage of females (86.3%), Angle Class I malocclusion (62.4%), and nonextraction (56.1%) was relatively higher in all 314 patients. More than half of the patients (73.6%) completed the first series of aligners. Differences between the groups in the number of patients with extraction, correction steps, and the curve of Spee were significant (P <0.05). The proportions of MC were 41.3% and 14.8% in extraction and nonextraction patients, respectively. More initially planned correction steps were seen in the MC group (53.4 ± 15.6 steps). Extraction (adjusted odds ratio, 0.375; P = 0.001) and correction steps (adjusted odds ratio, 1.06; P <0.001) were independent risk factors for MC.

CONCLUSIONS

Extraction and the number of initially planned correction steps are independent risk factors for MC. In patients with complex dentofacial abnormalities, such as extraction, MC may be needed to achieve predicted changes.

Difference in the alveolar bone remodeling between the adolescents and adults during upper incisor retraction: a retrospective study

The purpose of this study was to compare the difference of alveolar bone remodeling between the adolescents and adults in the maxillary incisor area during retraction. This retrospective study included 72 female patients who needed moderate anchorage to correct the bimaxillary protrusion. Subjects were further divided into the minor group (n = 36, 11-16 years old) and adult group (n = 36, 18-35 years old). Digital lateral cephalography and cone beam CT scanning were taken in each patient before (T0) and after treatment (T1). Cephalometry was conducted to assess incisor retraction, while alveolar bone thickness (ABT), alveolar bone distance (ABD), and alveolar bone area (ABA) were detected to assess changes in the alveolar bone. No difference in the inclination of upper incisors was observed at both T0 and T1 between two groups. Changes in the alveolar bone showed a similar tendency with bone apposition on the labial side and bone resorption on the palatal side in both groups. Less increase in the labial ABT (T1-T0) and more decrease in the palatal ABT (T1-T0) was found in the adult group, leading to less total ABT in the adult group. Higher reduction in ABD (T1-T0) was found in the adult group. Moreover, more decrease in the ABA (T1-T0) was found in the adult group. Adult patients have less alveolar bone support after treatment when compared with young adolescents. Orthodontists should take the age into consideration to reduce the potential periodontal risks during the treatment planning.

PASS versus MBT™ for evaluation of anchorage control in three-dimensional measurements: a randomized controlled trial

BACKGROUND

Growth and development might lead to anchorage loss during orthodontic treatment, such as the mesial drift of molars, the compensation characteristics of upper molars following mandibular growth, or the angulation of molars before treatment. Different anchorage reinforcement devices have been developed to prevent mechanical anchorage loss, but the anchorage loss resulting from physiological factors should also be taken into account.

OBJECTIVE

To explore the efficacy of a new strategy to control physiologic anchorage compared with that of the conventional straight-wire appliance.

TRIAL DESIGN

Randomized controlled trial (RCT).

METHODS

Participants of Han ethnicity were randomized into the physiologic anchorage spee-wire system (PASS) group or McLaughlin-Bennett-Trevisi (MBT™) straight-wire group by minimization random allocation. The eligibility criteria were patients with a Class I or II molar relationship, permanent dentition (11-35 years old), fixed appliances involving the extraction of at least two upper first premolars, and medium or maximum anchorage requirements. Pre-treatment and post-treatment dental casts were scanned into digital casts and measured using a blinded method. Mesial displacements of the upper first molars were considered as the primary outcome for evaluating anchorage control. Measurements were taken for subgroups based on age.

RESULTS

Data from 60 participants were analysed. The baseline characteristics were not significantly different between groups. Mesial displacement of the upper first molar (in mm) was 2.96 ± 1.52 in the PASS group and 2.70 ± 1.66 in the MBT group (P = 0.521). The variation in incisor torque was -6.94 ± 6.35 degree in the PASS group and -11.76 ± 7.65 degree in the MBT group (P = 0. 010). The incisor retraction (in mm) was 4.24 ± 1.99 and 5.67 ± 2.27 in the PASS and MBT groups, respectively (P = 0.012). Adverse effects were not documented in any patient.

LIMITATION

The study was a single-centre study.

CONCLUSIONS

Compared with the MBT group, the PASS group without additional anchorage devices could attain well anchorage control by considering the dentoalveolar compensation of anchor teeth.

REGISTRATION

This RCT was registered at the Chinese Clinical Trial Registry (Chictr.org.cn) ChiCTR-TRC-13003260.

Does anchorage loss differ with 0.018-inch and 0.022-inch slot bracket systems?

OBJECTIVES

To compare maxillary first molar anchorage loss between 0.018-inch and 0.022-inch slot fixed appliance systems.

MATERIALS AND METHODS

Patients requiring bilateral maxillary premolar extractions (n = 74) within a randomized clinical trial comparing the effectiveness of 0.018-inch and 0.022-inch slot MBT bracket systems (3M-Unitek, Monrovia, Calif) were included. Three-dimensional pre- and posttreatment digital models were landmarked and measured (R700 scanner and OrthoAnalyzer software, 3Shape, Copenhagen, Denmark). Anteroposterior position of the first molars was measured using the third medial rugae point as a reference. Anchorage loss (AL) represented the subtraction of the posttreatment distance from the pretreatment distance for both anchorage loss right (ALR) and left (ALL) sides. The values were then compared using a two-way analysis of variance.

RESULTS

There were 41 and 33 cases for the 0.018-inch and 0.022-inch bracket slot systems, respectively. The baseline characteristics were similar between groups, except for the presence or absence of anchorage devices (P = .050). For the total sample: 0.018-inch ALR = 3.86 mm, ALL = 3.30 mm and 0.022-inch ALR = 3.73 mm, ALL = 3.47 mm (P = .970). There was also no significant difference between the 0.018-inch and 0.022-inch groups when subjects with anchorage devices were excluded (P = .383).

CONCLUSIONS

Bracket slot size does not influence maxillary molar anchorage loss during orthodontic treatment.

Comparison of orthodontic tooth movement between adolescents and adults based on implant superimposition

OBJECTIVE

We compared tooth movement under maximum anchorage control with mini-screw implants in growing and non-growing patients.

METHODS

In total, 15 adolescent (G1) and 19 adult (G2) patients with prognathic profiles were selected. All patients underwent first premolar extraction treatment with mini-screw implants for maximum anchorage control. Cone-beam computed tomography (CBCT) data were obtained immediately after implant placement (T1) and at the end of anterior tooth retraction (T2). Tooth movement and root length changes of the maxillary first molar, canine, and incisors were evaluated with three-dimensional models constructed using CBCT data obtained before and after orthodontic retraction through the superimposition of stable implants.

RESULTS

Distal movement of the molar crown was observed in G2, but mesial movement was observed in G1. Mesial tipping of the first molar (1.82 ± 6.76°) was seen in G1 and distal tipping (4.44 ± 3.77°) was observed in G2. For the canines, mesial crown tipping (0.33 ± 4.99°) was noted in G1 and distal crown tipping (8.00 ± 5.57°) was observed in G2. In adults, the lingual inclinations of the lateral and central incisors were 11.91 ± 7.01° and 11.47 ± 6.70°, with 0.99 ± 1.22 mm and 1.08 ± 1.20 mm root retraction, respectively. In adolescents, the torque changes were smaller (lateral incisors, 8.25 ± 10.15°; central incisors, 9.82 ± 8.97°) and the root retractions were 0.31 ± 1.81 mm and 0.77 ± 1.59 mm, respectively. Less shortening of the central incisor roots occurred in adolescents than in adults.

CONCLUSIONS

Tooth movements, such as anchor molar angular change, the canine tipping pattern, and the amount of incisor retraction, differed between adolescents and adults treated using the same anchorage with mini-screw implants, bracket prescription, and en masse retraction method. Anchorage strength of the first molars, canine movement patterns, and incisor retraction ranges are not determined by the anchorage device alone; growth and alveolar limitations also play roles.

How effective is the Invisalign® system in expansion movement with Ex30' aligners?

OBJECTIVES

The aims of this study are to validate a new method for quantifying the predictability of expansion movement with the Invisalign® system and to determine whether there are statistically significant differences between planned expansion with ClinCheck® and actual clinical quantification using upper post-treatment model comparisons.

MATERIALS AND METHODS

A sample of 116 patients subjected to expansion with Invisalign® was studied. The following variables were measured at T1 and T2 on 3D models and ClinCheck®: canine gingival width, first premolar gingival width, second premolar gingival width, first molar gingival width, canine cuspid width, first premolar cuspid width, second premolar cuspid width, first molar cuspid width, canine depth, arch depth, first molar rotation, first right and left molar rotation, and first molar inclination.

RESULTS

Measurement error was tested, showing good precision for all variables. The paired test showed non-significant differences between the 3D model and ClinCheck® at T1 for all variables except first molar cuspid width and arch depth. Statistically significant differences were found for canine gingival width, first premolar gingival width, second premolar gingival width, first molar gingival width, canine cuspid width, first premolar cuspid width, second premolar cuspid width, first molar cuspid width, and canine depth when the 3D model and ClinCheck® were compared at T2.

CONCLUSIONS

Differences between the 3D model and ClinCheck® at T2 showed that planned expansion at the end of treatment is not predictable.

CLINICAL RELEVANCE

This is the first in vivo human study to quantify the predictability of expansion in patients with Invisalign® Ex30 material.