OBJECTIVES: To investigate the predictability of transverse changes with Invisalign®. MATERIALS AND METHODS: Sixty-four adult Caucasians patients were selected to be part of this retrospective study. Pre and post-treatment digital models created from an iTero® scan were obtained from a single orthodontist practitioner. Linear values of upper and lower arch widths were measured for canines, premolars and first molars. RESULTS: For every maxillary measurement, there was a statistically significant difference between Clincheck® and final outcome. (P < .05) For every lower arch measurement at the gingival margin, there was a statistically significant difference between the Clincheck® planned expansion and the final outcome. (P < .05) CONCLUSIONS: The mean accuracy of expansion planned with Invisalign® for the maxilla was 72.8%, (82.9% for the cusp tips and 62.7% for the gingival margins.) Lower arch presented an overall accuracy of 87.7%, (98.9 % for the cusp tips and 76.4% for the gingival margins.) / May 2016

AIM: To assess root parallelism after Invisalign® treatment. MATERIALS AND METHODS: The sample consisted of 101 patients (mean age: 22.7 years, 29 males, 72 females) treated non-extraction with Invisalign® by one orthodontist. Root angulations were assessed using the 4-point angulation tool (Dolphin imaging©); the long axes of adjacent teeth were traced, yielding a convergence/divergence angle. Acceptable root parallelism was assessed if the root angulation did not converge/diverge more than 7 degrees. Sites evaluated: between 1st molars and 2nd premolars, 2nd and 1st premolars, lateral and central incisors, and between central incisors in all four quadrants. The average change in mesio-distal root angulation was assessed between pre- and post-treatment panoramic radiographs. RESULTS: Paired t-tests were used to analyze the average change in mesiodistal root angulation. Statistically significant differences were obtained indicating a reduction in the convergence/divergence angles between teeth #16-15, #15-14, #11-21, #24-25, #25-26, #45-44, #42-41, #41-31, #31-32, and #34-35 (at p-value <0.05). The average change in root angulation was not affected (p>0.05) by age (Pearson correlation coefficient), gender, occlusion type (I, II, or III), or elastic use (unpaired, 2 sample t-test at p<0.05). Intra and inter-rater reliability for 20% of the studied sample was assessed using the interclass correlation coefficient 3 test. All measured areas except teeth #16-15, #26-25, and #36-35 yielded good ICC reliability scores above 0.7. CONCLUSION: Root parallelism was improved post-Invisalign® treatment in ten of the fourteen areas evaluated. Thus, Invisalign® may be an effective treatment modality in controlling root angulation in non-extraction cases. / May 2016

OBJECTIVES: Investigate changes in mandibular incisor position resulting from Invisalign correction of the crowded dentition. MATERIALS AND METHODS: A retrospective chart review was undertaken on 61 adult Caucasian patients. Subjects were categorized into 3 groups based on the value of pre-treatment crowding of the lower dentition; 20 mild (2.0-3.9mm), 22 moderate (4.0-5.9mm) and 19 severe (>6.0mm). Cephalometric radiographs were measured to determine lower incisor changes. Interproximal reduction (IPR) and changes in arch width were also measured. Statistical evaluation of T0 and T1 values using paired t-tests and ANCOVA were applied to evaluate mean value changes. RESULTS: Lower incisor position and angulation changes were statistically significant in the severe crowding group. There were no statistically significant differences in lower incisor position between the mild and moderate crowding groups. There was a statistically significant increase in buccal expansion in each of the 3 groups. CONCLUSIONS: Invisalign® treatment can successfully resolve mandibular arch crowding using a combination of buccal arch expansion, interproximal reduction and lower incisor proclination. When there is <6mm of crowding, lower incisor position remained relatively stable. In more severely crowded dentitions (>6mm), the lower incisors proclined and protruded to allow for arch alignment.

No description available.

Objectives: Qualitative research is a standard research method in social sciences. It elicits the opinions of studied individuals to understand the issues to be solved. Findings commonly lead to hypotheses for subsequent studies. In medicine, it has been utilized only sporadically despite arguments to understand quality of life of patients. We applied the phenomenological qualitative research method to understand the thought process of distinguished Invisalign practitioners. In the absence of experimental evidence, clinicians typically rely on their past clinical experience, opinions of experts, and limited published case studies. In an effort to develop a more robust knowledge base to build clinician skills, this study was designed to assess how expert clinicians address the divergence between ClinCheck® simulation and actual tooth movements with Invisalign. Methods: Structured, open-ended interviews were conducted with five orthodontists who are known Invisalign experts of complex cases. Information were collected on: their approach to difficult transverse, vertical, and extraction treatment. Interviews utilized the conventional qualitative research protocol of recording, and then transcribing to analyze the data. Results: Some experts seek to push the limits of the aligner appliance whereas others still rely upon auxiliaries, such as fixed appliances, to achieve the treatment goals. In extraction treatment, the difficulty of tipping and root paralleling were counteracted by designing ClinCheck with virtual Tweed mechanics, where the plastic and attachments create “couple” type forces. Constricted arches receive expansion of ≤3mm, coupled with flattening of curve of Wilson by buccal root torque of approximately 5-10o. Open-bite treatment relies upon intrusion of molars and “relative” extrusion of incisors whereas, deep-bite receives overcorrection with premolar extrusion to level the curve of Spee. Conclusions: The expert orthodontist’s faith in Invisalign attachments, over-correction, and efficacy of virtual mechanics in ClinCheck are influenced by the malocclusion and their previous experience. Some experts seek to push the limits by re-configuring mechanics of the aligner appliance while others rely upon auxiliaries and braces to improve predictability. Hypothesis-driven experimental studies may now be designed. / Oral Biology

The aim of the investigation was to search the current literature (from April 2005 to December 2012) and determine the effectiveness of orthodontic tooth movement using the Invisalign system. With changes in attachments implemented within the past few years, a more recent appraisal of the available literature is of value. It is expected that this systematic review will provide a more up-to-date understanding of the treatment effects (efficacy in tooth movement and stability) of the Invisalign system. Additionally, an evaluation of the indications and case selection using Invisalign will be conducted A computerized search was conducted using PubMed, Evidence Based Medicine (EBM) Reviews Database (Cochrane Database of Systematic Reviews), Database of Abstracts of Reviews of Effects and Cochrane Central Register of Controlled Trials, Science Direct, and Thomsen's ISI Web of Science. Inclusion criteria that were to be satisfied by the literature search results were publications in English and human clinical trials. Studies not pertaining to the question of clinical effectiveness of Invisalign were selected for exclusion. Case reports, book chapters, and review papers were considered separately for analysis and contribution to the general information gathering in the systematic review. Book chapters were excluded. Quality assessment was performed on the studies that fulfilled the inclusion criteria. The quality and design of the study was considered. Of the studies that passed the quality assessment stage, a thorough evaluation was completed. Summaries of the included articles were prepared and information regarding study design, subjects, treatment times, and outcomes were organized in tabulated form. Appraisal of the included studies was performed using the 2010 CONSORT statement and 2009 ADA Clinical Recommendations Handbook. Overall, of the 271 studies reviewed (Stage I), 23 were selected for further review (Stage II). Ultimately, 10 studies were included in the systematic review (Stage III). In summary, after thorough analysis of the studies, it has been shown that Invisalign is an effective appliance for minor space closure, lingual constriction, and correction of anterior rotations and marginal ridge height discrepancies. However, Invisalign lacks the ability to correct anteroposterior discrepancies, occlusal contacts, extrusion, and rotations greater than 15 degrees. While the achieved and predicted tooth movement discrepancy was very minimal, it was found that overbite must be overcorrected. / Oral Biology

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The relationship between applied force and aligner thickness is poorly understood. Therefore, the aims of the present study were to: 1) Evaluate the effect of initial material thickness on force output of clear aligners; and 2) Recommend a consistent, repeatable method for measuring aligner cross-section and distribution. A total of 40 clear aligners were fabricated over stereolithographic (SLA) models with ideal dentition, using proprietary gRxh material in four different thicknesses: (10) Rx15 [0.015h], (10) Rx20 [0.020h], (10) Rx30 [0.030h], (10) Rx40 [0.040h]. For measuring initial force output when tipping a tooth, a custom-made force measurement apparatus (FMA) was used with the upper right central incisor translated facially 0.25 mm. All six components of force and torque were measured (Fx, Fy, Fz, Tx, Ty, Tz) over a 16 second period of time upon seating each aligner. After gathering FMA data, cross-section and distribution of aligner material thickness was then measured using three methods for comparison: hall effect transduction, computed tomography (CT) scanning, and cross-sectional analysis under a stereomicroscope. All measurements were taken along the mid-sagittal plane of the facial surface of the upper right central incisor. Force output and variability both generally increased with an increase in material thickness. The range of measured forces were 3.5 to 28 times higher than ideal tipping forces reported by Proffit. The results for lingual force correlated well with those of total force (ã(Fx)2 + (Fy)2 + (Fz)2). As for the thickness measurement results, the hall effect transducer (HET) data correlated well with that of the CT scan. The stereomicroscope produced values that were relatively elevated. Mean measurements taken with both HET and CT consistently got smaller when moving from occlusal to middle to gingival points. The same trend was noted with the stereomicroscope, but with less consistency. The thinner Rx15 material appeared best suited for lingual tipping of a maxillary central incisor in vitro. The hall effect transducer produced simple measurements that were extremely similar to those from the CT scan, and appears to be a suitable stand-in for the more expensive and labor intensive CT scanning process. / Oral Biology