Treatment Efficiency of Maxillary and Mandibular Orovestibular Tooth Expansion and Compression Movements with the Invisalign® System in Adolescents and Adults.

OBJECTIVES: Aligners are an effective and esthetic orthodontic treatment option for permanent and mixed dentition. There are only a few studies dealing with the effectiveness of orovestibular tooth movement using aligners and applying adequate examination methods. In the present retrospective study, the aligner efficiency of orovestibular movements for the entire dentition was systematically evaluated using 3D superimposition, taking into account the influence of jaw, tooth type and Invisalign® system. METHODS: Group 1 (n = 18 adults, Invisalign®) and Group 2 (n = 17 adolescents, Invisalign® Teen) were treated with Invisalign® Ex30 aligner material and Invisalign® specific auxiliary means. In this non-interventional retrospective study, pre- and post-treatment maxillary and mandibular plaster cast models were scanned and superimposed with ClinChecks® via Surface-Surface Matching Algorithm on unmoved teeth providing stable references. Effectivity of planned versus clinically realized movements was evaluated for each tooth. Statistics were performed with a t-test and Bonferroni-Holm correction (α = 0.05). RESULTS: Orovestibular movement efficiency was excellent without statistical significance regarding jaw, tooth type or Invisalign® system. Mandibular translational tooth movements were highly effective, and outstanding for premolars (91-98%). Maxillary translational tooth movements were successful for incisors and premolars, but less effective for canines and molars. Almost all teeth were moderately or very effectively corrected by crown tipping, performing better for mandibular (70-92%) than maxillary (22-31%) canines as much as for adolescent upper front teeth (81-85%) and lower canines (92%). CONCLUSIONS: Aligners are able to effectively implement translational orovestibular movements, supported by tilting the crowns for even more efficient implementation of the movements. This phenomenon was observed in our studies for all teeth in both jaws, regardless of the Invisalign® system used. Treatment planning should nevertheless take into account the individual patient parameters with regard to the movements to be performed in order to make the aligner therapy as successful as possible in terms of realizing the desired therapeutic goal.

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.

Evaluation of effectiveness and stability of aligner treatments using the Peer Assessment Rating Index.

AIMS: The aims of this study were to measure treatment effects of aligner treatments in adult patients directly after treatment and the stability of these effects after a short-term retention period using the Peer Assessment Rating (PAR) Index. METHODS: This double-center trial consecutively screened 98 adult patients of whom 33 patients were treated according to predefined inclusion and exclusion criteria. The study sample was shown to be representative for adult orthodontic reality with regard to gender, age, and distribution of malocclusion type. Malocclusion severity was rated by using the PAR Index measured at baseline (T0), after finishing orthodontic treatment with Invisalign® (T1; Align Technology Inc., Santa Clara, CA, USA) and after a mean retention period of 10 months (T2). Furthermore, to better understand the observed treatment modality, specific treatment characteristics were recorded and analyzed. RESULTS: The average PAR score at T0 was 22.18 (standard deviation [SD] ± 8.68). Posttreatment PAR score was 4.64 (SD ± 4.23) at T1 and was stable after a retention period of 10.07 months at T2 (SD ± 126.80 days; PAR 4.36, SD ± 3.93). All of the study cases showed a significant reduction of the total PAR score between T0 and T1 (p < 0.001), but no further difference between T1 and T2 (PAR 4.64 vs. 4.36). Cases were either classified 'improved' (n = 23) or 'greatly improved' (n = 10); no case was classified into the third PAR Index category 'worse or no different'. On average, 72 aligners (SD ± 22) with 12 attachments per treatment (SD ± 4) were used to align teeth. Six patients needed a case refinement with a mean of 23 (SD ± 8) further aligners. The maximum number of needed ClinCheck® (Align Technology Inc., Santa Clara, CA, USA) treatment plan revisions was 18 (mean 7, SD ± 4). CONCLUSION: The detected improvement rate indicated a good standard of orthodontic treatment using aligners. Treatment effects were stable throughout a short-term retention period using a specific retention protocol. Effectiveness and stability were equally achieved in mild, moderate, and rather severe cases within this consecutive sample. A critical focus should be placed on accurate treatment planning in order to make tooth movements predictable, realistic, and stable.

Influence of attachment bonding protocol on precision of the attachment in aligner treatments.

AIM: Precise bonding of attachments in aligner treatment is crucial to achieve the intended tooth movement. Thus, we evaluated five different bonding protocols for attachments used in aligner treatments with the goal of identifying the most precise protocol. METHODS: One ellipsoid and one rectangular attachment were exemplarily chosen and examined. All attachments were bonded using the same template aligner, which was produced by thermoforming. The bonding process was repeated 30 times with each protocol for statistical analysis. The protocols differed in the type of composite used (high viscous, low viscous), the additional application of a perforation in the attachment reservoir, and the use of a two-phase procedure with high viscous composite. All bonded attachments were laser scanned and compared to the attachments of a master model using a surface/surface matching algorithm to determine the precision, i.e., highest aberrations (maximum vertical distance) between the attachment of the master and results obtained from the various bonding protocols. Furthermore, the excessive amounts of composite bonded around the attachments were measured and compared. RESULTS: The two-phase procedure had a median aberration of 0.13 mm and a median amount of excessive composite of 7.40 mm2 (ellipsoid attachment). With the low viscous composite without a perforation in the template reservoir, similar results were achieved (median 0.13 mm) regarding the maximum vertical distance, but had an excess area of 33.50 mm2. CONCLUSION: In this in vitro study, the bonding protocol influenced the precision of bonded attachments. The bonding protocol with high viscous composite without a perforation in the attachment reservoir was the most inaccurate. The use of a low viscous composite or attachments made by a two-phase procedure with high viscous composite revealed more precise results.

Treatment outcome and efficacy of an aligner technique--regarding incisor torque, premolar derotation and molar distalization.

BACKGROUND: The aim of this study was to investigate the efficacy of orthodontic treatment using the Invisalign® system. Particularly, we analyzed the influence of auxiliaries (Attachment/Power Ridge) as well as the staging (movement per aligner) on treatment efficacy. METHODS: We reviewed the tooth movements of 30 consecutive patients who required orthodontic treatment with Invisalign®. In all patients, one of the following tooth movements was performed: (1) Incisor Torque >10°, (2) Premolar derotation >10° (3) Molar distalization >1.5 mm. The groups (1)-(3) were subdivided: in the first subgroup (a) the movements were supported with the use of an attachment, while in the subgroup (b) no auxiliaries were used (except incisor torque, in which Power Ridges were used). All tooth movements were performed in a split-mouth design. To analyze the clinical efficacy, pre-treatment and final plaster cast models were laser-scanned and the achieved tooth movement was determined by way of a surface/surface matching algorithm. The results were compared with the amount of tooth movement predicted by ClinCheck®. RESULTS: The overall mean efficacy was 59% (SD = 0.2). The mean accuracy for upper incisor torque was 42% (SD = 0.2). Premolar derotation showed the lowest accuracy with approximately 40% (SD = 0.3). Distalization of an upper molar was the most effective movement, with efficacy approximately 87% (SD = 0.2). CONCLUSION: Incisor torque, premolar derotation and molar distalization can be performed using Invisalign® aligners. The staging (movement/aligner) and the total amount of planned movement have an significant impact on treatment efficacy.

Forces and moments generated by removable thermoplastic aligners: incisor torque, premolar derotation, and molar distalization.

INTRODUCTION: The exact force systems as well as their progressions generated by removable thermoplastic appliances have not been investigated. Thus, the purposes of this experimental study were to quantify the forces and moments delivered by a single aligner and a series of aligners (Invisalign; Align Technology, Santa Clara, Calif) and to investigate the influence of attachments and power ridges on the force transfer. METHODS: We studied 970 aligners of the Invisalign system (60 series of aligners). The aligners came from 30 consecutive patients, of which 3 tooth movements (incisor torque, premolar derotation, molar distalization) with 20 movements each were analyzed. The 3 movement groups were subdivided so that 10 movements were supported with an attachment and 10 were not. The patients' ClinCheck (Align Technology, Santa Clara, Calif) was planned so that the movements to be investigated were performed in isolation in the respective quadrant. Resin replicas of the patients' intraoral situation before the start of the investigated movement were taken and mounted in a biomechanical measurement system. An aligner was put on the model, the force systems were measured, and the calculated movements were experimentally performed until no further forces or moments were generated. Subsequently, the next aligners were installed, and the measurements were repeated. RESULTS: The initial mean moments were about 7.3 N·mm for maxillary incisor torque and about 1.0 N for distalization. Significant differences in the generated moments were measured in the premolar derotation group, whether they were supported with an attachment (8.8 N·mm) or not (1.2 N·mm). All measurements showed an exponential force change. CONCLUSIONS: Apart from a few maximal initial force systems, the forces and moments generated by aligners of the Invisalign system are within the range of orthodontic forces. The force change is exponential while a patient is wearing removable thermoplastic appliances.