Maxillary expansion or contraction and occlusal contact adjustment: effectiveness of current aligner treatment

How well does Invisalign ClinCheck predict actual results: A prospective study

INTRODUCTION

This study aimed to compare achieved movements with predicted movements after 28-week use of Invisalign Lite aligners.

SETTINGS AND SAMPLE POPULATION

The digital impressions of 21 subjects treated with Invisalign Lite at a private practice and in the dental clinic (Milan, Italy) were taken and analysed. Subjects were Caucasian with a mean age of 20.1 years.

METHODS

Patients were analysed at two time points: at T0, before starting therapy, and at T1, after 28 weeks of treatment with Invisalign clear aligners, with a 2-week change interval. The changes that occurred between T0 and T1 were compared to the predicted changes between T0 and Ts (setup/ClinCheck). Tooth movement performance was estimated through variables calculated as the difference between obtained and planned movements.

RESULTS

In both maxillary and mandibular arches, the teeth that exhibited the least accurate expression of torque were the central incisors. Tip was not accurate on maxillary central incisors and canines, mandibular central incisors, lateral incisors, first premolars, second premolars and first molars. Rotations were under-expressed on maxillary lateral incisors, canines and second premolars and on mandibular central incisors, canines, first premolars, second premolars and first molars. The overall angular changes showed a tendency to underperformance. Transverse linear changes were accurate with a significant overperformance on maxillary and mandibular first molars.

CONCLUSIONS

Torque correction of maxillary central incisors, as well as rotational correction of most of the teeth, showed significant differences between what was planned and what was obtained.

Accuracy of Digital Orthodontic Treatment Planning: Assessing Aligner-Directed Tooth Movements and Exploring Inherent Intramaxillary Side Effects

Background: The attainment of precise posterior occlusion alignment necessitates a deeper understanding of the clinical efficacy of aligner therapy. This study aims to determine whether the treatment goals defined in the virtual planning of aligner therapy are effectively implemented in clinical practice, with a particular focus on the influence of distalization distances on potential vertical side effects. Methods: In this retrospective, non-interventional investigation, a cohort of 20 individuals undergoing Invisalign® treatment was examined. Pre- and post-treatment maxillary clinical and ClinCheck® casts were superimposed utilizing a surface-surface matching algorithm on palatal folds, median palatine raphe, and unmoved teeth as the stable references. The effectivity of planned versus clinical movements was evaluated. Groupings were based on distalization distances, planned vertical movements, and Class II elastic prescription. Statistics were performed with a two-sample t-test and p-value < 0.05. Results: Clinically achieved distalization was significantly lower than virtually planned distalization, regardless of additional vertical movements, where a lack of implementation was contingent upon the extent of distalization, with no mitigating effects observed with the application of Class II elastics. Intriguingly, no adverse vertical side effects were noted; however, the intended intrusions or extrusions, as per the therapeutic plans, remained unattainable regardless of the magnitude of distalization. Conclusions: These findings underscore the imperative for future investigations to delve deeper into the intricacies surrounding translational mesio-distal and vertical movements, thereby enhancing predictability within orthodontic practice. To facilitate successful clinical implementation of vertical and translational movements via aligners, the incorporation of sliders emerges as a promising strategy for bolstering anchorage reinforcement.

Comparison of the efficiency of initial dental alignment with Invisalign® aligners changed every 7 or 14 days in mature adults: Randomized clinical trial

OBJECTIVE

To compare the anterior crowding correction after sequential use of the first 5 aligners between two aligner exchange protocols (7 and 14 days) in mature adult patients.

MATERIALS AND METHODS

Thirty-six patients over 35 years who received orthodontic treatment with Invisalign® were randomly allocated to two different aligner replacement sequence protocols: Group 1: exchange every 7 days (n = 18); and Group 2: exchange every 14 days (n = 18). All patients were scanned with iTero Element 5D® (Align Technology) in two treatment times: at pre-treatment (T1) and after using the first five aligners (T2). Little's Irregularity Index (LII) and arch widths were evaluated with OrthoCAD software. Intra and intergroup comparisons were performed with the dependent and independent t-tests. The results were considered significant for P < .05.

RESULTS

Thirty-five patients completed the study. Both groups' maxillary and mandibular Irregularity Indexesi were significantly lower at T2. There was no significant difference in inter-canine, inter-premolar, and intermolar distances. G2 (14 days) presented a greater decrease in mandibular irregularity than G1 (7 days).

CONCLUSION

Both exchange protocols (7 and 14 days) effectively correct anterior crowding in the initial phase of orthodontic treatment with aligners in mature adult patients. However, the 14-day exchange protocol provided a greater correction in mandibular anterior crowding in the evaluated period than the 7-day exchange protocol.

An evaluation of the Invisalign® Aligner Technique and consideration of the force system: a systematic review

OBJECTIVE

Since its introduction 25 years ago, the Invisalign® system has undergone multiple digital and biomechanical evolutions and its effectiveness is often compared to traditional systems without considering the many differences which characterize them. The main aim of this systematic review is to look at the literature dealing with studies on teeth movements using the Invisalign® system and the management of these movements through digital planning and artificial intelligence.

MATERIALS AND METHODS

The following electronic databases were searched: MEDLINE, Embase, the Cochrane Oral Health Group's Trials Register, and CENTRAL. Unpublished studies were searched on ClinicalTrials.gov, the National Research Register, and Pro-Quest Dissertation Abstracts and Thesis database.

RESULTS

Twenty-four studies (15 retrospective, 5 prospective, 2 pilot, and 2 case-control) were included. The results of the analysis carried out on the available literature show that the Invisalign® system is recognized to be a valid alternative to conventional orthodontic treatment in no-extraction cases. The results are influenced by the methods for assessing the effectiveness of this technique and by the comparison bias of the traditional system with the innovative digital system.

CONCLUSIONS

Since the introduction of SmartForce and SmartTrack material, the efficacy of the treatment has improved. There is still a shortage of high-quality evidence concerning the treatment modality. In order to make the treatment with the aligners more efficient, a correct management of the ClinCheck® software and a proper use of the biomechanics are necessary. The aligned force-driven system should be taken into account when developing the digital planning.

Dimensional changes in the palate associated with Invisalign First System: a pilot study

OBJECTIVES

To compare palatal dimensions and molar inclinations after Invisalign First System (IFS) to those in patients treated with slow maxillary expansion (SME) and normal controls.

MATERIALS AND METHODS

Twenty-three mixed dentition patients treated with IFS were gender- and dental age-matched to another two groups: Haas-type SME and control group. The intercanine width (ICW), intermolar width (IMW), palatal surface area (SA), volume (V), and first molar buccolingual inclinations (MI) were measured before (T1) and after (T2) treatment. Analysis of variance was used to compare the differences among the three groups.

RESULTS

The ICW increased significantly by 3.10 mm after IFS, 4.77 mm with SME, and 0.54 mm in controls; the difference among the groups was statistically significant (P < .001). The IMW increased by 1.95 mm in IFS, 4.76 mm in SME, and 0.54 mm in controls, with significant intra- and intergroup differences. Palatal SA and volume increased by 43.50 mm2 and 294.85 mm3 in the IFS group, which differed significantly from SME, but was similar to controls. The right and left MI increased 0.24° and 0.08° buccally, respectively, in the IFS group, which was comparable to controls, while significantly increased buccal MI was observed in the SME group.

CONCLUSIONS

IFS expands the upper arch with increased ICW and IMW compared to controls, but the expansion amount is smaller than SME. Unlike SME, IFS has no effects on palatal dimensions and molar inclinations.

The accuracy of virtual setup in simulating treatment outcomes in orthodontic practice: a systematic review

OBJECTIVES

To evaluate the accuracy of virtual orthodontic setup in simulating treatment outcomes and to determine whether virtual setup should be used in orthodontic practice and education.

MATERIALS AND METHODS

A systematic search was performed in five electronic databases: PubMed, Scopus, Embase, ProQuest Dissertations & Theses Global, and Google Scholar from January 2000 to November 2022 to identify all potentially relevant evidence. The reference lists of identified articles were also screened for relevant literature. The last search was conducted on 30 November 2022.

RESULTS

This systematic review included twenty-one articles, where all of them were assessed as moderate risk of bias. The extracted data were categorized into three groups, which were: (1) Virtual setup and manual setup; (2) Virtual setup and actual outcomes in clear aligner treatment; (3) Virtual setup and actual outcomes in fixed appliance treatment. There appeared to be statistically significant differences between virtual setups and actual treatment outcomes, however the discrepancies were clinically acceptable.

CONCLUSION

This systematic review supports the use of orthodontic virtual setups, and therefore they should be implemented in orthodontic practice and education with clinically acceptable accuracy. However, high-quality research should be required to confirm the accuracy of virtual setups in simulating treatment outcomes.

Clinical outcomes of arch expansion with Invisalign: a systematic review

OBJECTIVE

This study aims to assess the scientific evidence regarding the clinical outcomes of Invisalign therapy in controlling orthodontic tooth movement.

MATERIALS AND METHODS

An electronic search was conducted on PubMed, Cochrane Library, Web of Science, Embase, and Scopus from November 2015 to November 2022 to identify relevant articles. Methodological shortcomings were highlighted, and an evaluation of the quality of the included studies was completed using the Risk of Bias in Non-randomized Studies of Interventions (ROBINS-I) tool.

RESULTS

Fifteen non-randomized controlled trials were included in the analysis. Most non-randomized controlled trials (n=11; 73%) were rated with a moderate risk of bias according to the ROBINS-I tool. There were statistically significant differences between the pretreatment and posttreatment arches. The average expansion was significantly different from that predicted for each type of tooth in both the maxilla and mandible. Furthermore, the efficiency decreased from the anterior area to the posterior area in the upper arch.

CONCLUSION

Despite the fact that arch expansion with Invisalign® is not entirely predictable, clear aligner treatment is a viable option for addressing dentition crowding. The efficacy of expansion is greatest in the premolar area. More research focusing on treatment outcomes with different materials of aligners should be conducted in the future. Overcorrection should be considered when planning arch expansion with Invisalign. In the maxilla, the expansion rate decreases from the anterior to the posterior, and presetting sufficient buccal root torque of posterior teeth may result in improved efficiency of expansion.

Is maxillary arch expansion with Invisalign® efficient and predictable? A systematic review

BACKGROUND

The main objective of this review is to assess the effectiveness and predictability of the transverse expansion movement performed by Invisalign®. The secondary objectives are to determine whether the expansion is of a dentoalveolar or skeletal nature, and to locate the areas of expansion on the dental arch.

METHODS

Two investigators used the PubMed database to search for articles related to the subject. After using a research equation, specific inclusion and exclusion criteria were applied and the final selection of articles was done after being read in full. The ROBINS-I tool for non-randomized studies was applied to assess risk of bias in the results of each included study.

RESULTS

After reading the articles in full, 12 articles were included. Regarding effectiveness, most studies showed an increase in all measured interdental distances, with a maximum expansion at the premolar level. As for predictability, significant differences were found between post-treatment models and Clincheck® models, making it generally weak. Concerning the nature and areas of expansion, increase of arch width was due to buccal tipping of the crowns following a decreasing gradient from anterior to posterior.

CONCLUSIONS

Invisalign® treatment is effective in achieving a maxillary transverse expansion. However, this expansion is mainly dentoalveolar, with a facial crown tipping of the posterior teeth. Clincheck® software tends to overestimate the expansion movement when compared to the clinical outcome, therefore the predictability of movement is low.

Occlusal Changes with Clear Aligners and the Case Complexity Influence: A Longitudinal Cohort Clinical Study

BACKGROUND

Clear aligners (CA) are used 22 h daily, creating a bite-block effect. This work aims to (i) analyze occlusal changes before the beginning of treatment, after the first set of CA and after the use of additional aligners; (ii) compare planned occlusal contacts with the ones obtained after the first set of CA; (iii) analyze the occlusal changes occurred after reaching the orthodontic goals after 3 months of using CA only at night; (iv) evaluate and characterize which tooth movements did not allow the treatment to be completed at the end of the first set of aligners, and finally (v) verify the possible relation between the changes in occlusal contact and areas and parameters such as case complexity and facial biotype.

MATERIALS AND METHODS

A quantitative, comparative, and observational longitudinal cohort study design was implemented to evaluate the clinical data and the complexity levels of cases receiving CA. A non-probabilistic and convenience sample of 82 individuals was recruited. The orthodontic malocclusion traits were classified as simple, moderate, or complex corrections based on the basis of the Align^® recommendations with the Invisalign^® evaluation tool. According to the Invisalign^® criteria, patients need only one complex problem for their case to be classified as complex. Meshlab^® v. 2022.02, ClinCheck^® version Pro 6.0, My-Itero^® version 2.7.9.601 5d plus, and IBM^® SPSS Statistics software (Statistical Program for Social Sciences), version 27.0 for Windows were the software^® used.

RESULTS

A statistically significant decrease in area and occlusal contacts number were observed from before the start of orthodontic treatment (T0) to the end of treatment (T1). The changes in the occlusal area (from T0 to T1) were statistically different between hyperdivergent (28.24 [15.51-40.91]) and hypodivergent (16.23 [8.11-24.97]) biotypes (p = 0.031). A significant difference between the hyperdivergent (4.0 [2.0-5.0]) and normodivergent (5.5 [4.0-8.0]) group was found in T1 for the anterior contacts (p = 0.044). Anterior contacts obtained were significantly higher than the planned (p = 0.037) Between T1 and T2 statistically significant increases of occlusal areas, posterior and total contacts were observed.

CONCLUSIONS

Occlusal contact and area were decreased, either at the end of the first set or after the use of additional aligners. Anterior occlusal contacts obtained were higher than planned as opposed to posterior occlusal contacts obtained. The hardest tooth movements to achieve to complete the treatment were distalization, rotation, and posterior extrusion. After completing orthodontic treatment (T1) to 3 months after (T2) using additional aligners only at night, posterior occlusal contacts were significantly increased, which could be due to the natural settling of the teeth in this period.

The Predictability of Transverse Changes in Patients Treated with Clear Aligners

Arch expansion might be used to correct buccal corridors, improve smile aesthetics, resolve dental cross bite, and gain space to resolve crowding. In clear aligner treatment, the predictability of the expansion is still unclear. The purpose of this study was to evaluate the predictability of dentoalveolar expansion and molar inclination with clear aligners. In the study, 30 adult patients (27 ± 6.1 years old) treated with clear aligners were selected (treatment time: 8.8 ± 2.2 months). The upper and lower arch transverse diameters were measured for canines, first and second premolars, and first molars on two different sides (gingival margins and cusp tips); moreover, molar inclination was measured. A paired t-test and Wilcoxon test were used to compare prescription (planned movement) and achieved movement. In all cases, except for molar inclination, a statistically significant difference was found between achieved movement and prescription (p < 0.05). Our findings showed a total accuracy of 64% for the lower arch, 67% at the cusp level, and 59% at the gingival level, with a total accuracy of 67% for the upper arch, 71% at the cusp level, and 60% at the gingival level. The mean accuracy for molar inclination was 40%. Average expansion was greater at cusps of canines than for premolars, and it was lowest for molars. The expansion achieved with aligners is mainly due to the tipping of the crown rather than bodily movement of the tooth. The virtual plan overestimates the expansion of the teeth; thus, it is reasonable to plan an overcorrection when the arches are highly contracted.

Arch Expansion Efficiency of Clear Aligner on Patients with Mixed Dentition Using 3ship Digital Oral Scanner

The aim of this study to evaluate the maxillary and mandibular arch expansion efficiency of clear aligner. A total of 15 patients aged between 8–11 who were admitted from January 2020 to December 2021. The 3ship digital oral scanner was used to establish a digital oral model for the patients before and after the correction. The three-dimensional model before and after correction was established by ClinCheck software to measure and record the width of each tooth position and evaluate the efficiency of arch expansion. The dental arch width was greater after correction of the width between the maxillary and maxillary canines, the width between the first premolars, the width between the second premolars, and the width between the first molars, showing statistically significant differences (P <0.05). The arch expansion efficiency in the maxillary canine area > the maxillary first premolar efficiency > the maxillary second premolar efficiency > the maxillary first molar efficiency. Through the linear regression equation, the preset expansion amount of each tooth position was reasonably predicted.Taken together our data suggested that the clear aligner efficiency can be improved by adding accessories and torque in the base bone range when necessary.

Analysis of Maxillary First Molar Derotation with Invisalign Clear Aligners in Permanent Dentition

The objective of this study was to examine the distal rotation of mesial rotated maxillary first permanent molars in a sample of Class II dental malocclusion adult patients treated with Invisalign Clear Aligners (CA). Forty patients (20 males, 20 females, 22.4 ± 3.9 years) were included in the study sample (Department of Orthodontics of University of Rome “Tor Vergata”). Inclusion criteria were: Caucasian ancestry, complete permanent dentition with fully erupted upper second molars, Class II molar relationship, absence of tooth or craniofacial anomalies or caries and periodontal diseases. Pre-treatment (T1), post-treatment (T2) digital casts, and final ClinCheck simulation models (T2CC) were analysed. To measure the rotation of maxillary first molars, Henry’s angle (H°) was evaluated. Maxillary first molars with an H° > 11° were considered mesio-rotated (in total 59 teeth). The treatment CA protocol included disto-rotation without distalization movements. At T1, T2 and T2CC five measurements on the collected dental casts were analysed: Henry’s angle (H°); mesial buccal expansion (ME); distal buccal expansion (DE); mesial buccal sagittal (MS); and distal buccal sagittal (DS). A comparison between the results of T2-T1 and T2CC-T2 was performed using a paired t-test. The differences between T2-T1 highlighted a significant distal rotation of the maxillary first molars (−7.4°) and an expansion movement of 2.20 mm for ME and 1.50 mm for DE. In the post-treatment, the mesial buccal cusps shifted of 1.0 mm, while the distal buccal cusps showed a distal movement of 0.9 mm. Analysing the H° comparison between T2CC-T2, the difference was −1.1°. The T2CC-T2 comparison in the sagittal plane showed a difference of 0.9 mm for the MS and 0.7 mm for the DS. The accuracy was 82% for molar derotation movement. In conclusion, CA provides the upper arch expansion associated with the upper first molars’ distal rotation. These movements provide 2 mm of improvement in arch perimeter and molar intercuspation.