Clear Aligner Therapy Research Articles

The hybrid approach: A solution to overcome unpredictable movements in clear aligner therapy

The clear aligner system has been radically improved in many aspects: New materials, protocols, attachments, and auxiliaries were developed to improve biomechanics. Many movements remain unpredictable, outlining the limits of clear aligners treatment, but a hybrid approach, which combines clear aligners with fixed appliance, is an efficient treatment alternative. This approach significantly reduces overall treatment time and unpredictable movements. The aim of this article is to show the application of the hybrid approach for different types of movements.

Bimaxillary protrusion and gummy smile treated with clear aligners: Closing premolar extraction spaces with bone screw anchorage

Inadequate posterior anchorage is a serious limitation for aligner treatment involving extraction of four first premolars. Inappropriate axial inclinations may compromise intermaxillary occlusion and stability. OrthoBoneScrew® (OBS) anchorage is designed to augment the Invisalign® clear aligner G6 solution to produce more predictable outcomes as illustrated by the current case report. An 18-year-old female presented with two chief complains: (1) Protrusive, incompetent lips, and (2) excessive gingival exposure when smiling (“gummy smile”). Clinical evaluation revealed bimaxillary protrusion, hypermentalis activity, anterior crowding, and excessive anterior axial inclinations, particularly of the lower incisors (116°). The American Board of Orthodontic (ABO) discrepancy index (DI) was 21. The treatment plan was extraction of all four first premolars, and clear aligner (Invisalign®) therapy anchored with four OBSs: Infra-zygomatic crest (IZC), and between the roots of the upper central and lateral incisors (Incisal) bilaterally. Eighteen months of initial treatment with 45 aligners retracted and intruded the anterior segments in both arches by closing the extraction spaces with supplemental anchorage provided by IZC and Incisal OBSs. The final series of 20 refinement aligners achieved an excellent outcome as evidenced by an ABO cast-radiograph evaluation (CRE) score of 10, and a pink and white (P&W) dental esthetic score of 3. Post-treatment analysis revealed multiple opportunities for improvement. The patient was well satisfied with the final outcome.

Esthetic perception of clear aligner therapy attachments using eye-tracking technology

The purpose of this research was to assess and compare esthetic perceptions of clear aligner therapy with attachments and esthetic brackets by measuring differences in eye fixations using eye-tracking technology. The sample involved 250 adult subjects. The subjects gave verbal consent, then viewed photographs showing 4 variations of orthodontic appliances: clear aligner control with minimal attachments, clear aligner with anterior and posterior attachments, esthetic brackets, and clear aligner with posterior attachments. Images were displayed for 6seconds each on a computer monitor. Location and time to first fixation, total fixation duration, and total visit count and duration for each type of appliance were measured. Subjects were then asked to complete an online survey. Participants spent the least amount of time looking at the photograph of the control, followed by those of the ceramic brackets, posterior attachments, and anterior and/or posterior attachments. The anterior and/or posterior image had the least number of visits but garnered the longest visit duration (1.32 visits averaging 0.74seconds per visit). This was followed by the images of the posterior attachments (1.40 visits, 0.70seconds per visit), ceramic brackets (1.43 visits, 0.65seconds per visit), and minimal attachments control (1.45 visits, 0.61seconds per visit). The hierarchy of most preferred appliances across all 250 respondents was as follows: minimal attachments control, ceramic brackets, posterior attachments, and anterior and/or posterior attachments. Overall, 88.4% of subjects would compromise appliance esthetics during treatment for a better outcome (n=221). Eye-tracking data show that time to the first fixation was negatively correlated with its survey ranking and that an increase in attachments led to an increase in total fixation duration. There is a general desire for clear aligners without attachments and ceramic brackets over clear aligners with multiple attachments. Survey data suggest that although respondents viewed appliance esthetics as highly important, nearly all would compromise appliance esthetics during treatment if it resulted in a better outcome.

Clear aligners for maxillary anterior en masse retraction: a 3D finite element study

To evaluate tooth behaviours under various maxillary incisor retraction protocols for clear aligner therapy. A three-dimensional finite element model of maxillary dentition was constructed for first premolar extraction. A loading method was developed to mimic the mode of action of clear aligners for incisor en masse retraction. Three protocols with different amounts of retraction and intrusion on incisors were designed. Initial tooth displacements and stresses on periodontal ligaments were analysed with ANSYS software. The central (U1) and lateral (U2) incisors exhibited uncontrolled lingual tipping and extrusion upon 0.25 mm retraction. U1 exhibited translation movement, while U2 underwent less tipping during 0.2 mm retraction and 0.15 mm intrusion. Labial tipping and intrusion of U1 and bodily intrusion of U2 were observed during 0.1 mm of retraction and 0.23 mm of intrusion. With the additional intrusion on incisors, canine showed extrusion movement, and higher stresses on periodontal ligaments were shifted from U2 to canines. Incisors also exhibited different mesial-distal angulation in the three simulations, while posterior teeth all suffered mesial inclination. Incorporating intrusion displacement in clear aligners led to a tendency of lingual root movement during incisor retraction. The complexity of tooth movement should be recognized regarding clear aligner therapy.

Enamel demineralization during clear aligner orthodontic treatment compared with fixed appliance therapy, evaluated with quantitative light-induced fluorescence: A randomized clinical trial

The objective of this prospective randomized clinical trial was to investigate the relationship between clear aligner (CA) therapy and the development of white spot lesions and compare it with orthodontic fixed appliance (FA) therapy. This was a prospective randomized clinical trial. The setting was the postgraduate orthodontic clinic at Jordan University of Science and Technology. A total of 49 patients (39 female, 10 male; mean age±standard deviation, 21.25±3years) who required orthodontic treatment with either FAs or CAs were randomly allocated into 1 of 2 study groups. Eligibility criteria included healthy patients of both sexes (age range 17-24years), Class I malocclusion with mild-to-moderate crowding (≤5mm), nonextraction treatment plan, and optimum oral hygiene before treatment as determined by clinical examination. The participants were randomly assigned to a study group according to a simple randomization method using a coin toss by the patient; the text or tail side of the coin indicated treatment with CA (group 1), and the head side of the coin indicated orthodontic treatment with FA (group 2). Blinding was applicable for outcome assessment only. CA therapy was performed for group 1 and FA for group 2. Quantitative light-induced fluorescence (QLF) images were taken before treatment (T0) and 3months later (T1). The QLF images were then analyzed to assess the research outcomes. The main outcome was the mean amount of fluorescence loss (ΔF). Number of newly developed lesions, deepest point in the lesion (ΔFMax), lesion area (pixels), and plaque surface area (ΔR30) were measured as secondary outcomes. Descriptive statistics and comparison within and between groups were calculated. In total, 42 of the 49 participants recruited completed the study (19 in the CA group and 23 in the FA group). The mean amount of fluorescence loss was 0.4% for the CA group (P=0.283) and 1.2% for the FA group (P=0.013). The difference between the 2 groups was significant (confidence interval [CI], -1.8 to -0.4; P=0.002). The mean increase in lesion area was 82.2 pixels for the CA group (P <0.001) and 9.3 pixels for the FA group (P=0.225). The difference between the 2 groups was significant (CI, -117 to -75.0; P<0.001). ΔR30 was 1.2% for the CA group and 10.9% for the FA group (CI, 6.847-12.479; P<0.001). The number of newly developed lesions in the CA group was 6 lesions/patient and 8.25 in the FA group (P=0.039). No serious harm on the oral health of the participants in the 2 study groups was observed other than mild gingivitis associated with plaque accumulation. No serious harm was reported by any of the participants. Orthodontic treatment with CAs and FAs caused enamel demineralization. The CA group developed larger but shallower white spot lesions, whereas the FA group developed more new lesions with greater severity, but they were smaller in area. More plaque accumulation was found in the FA group compared with the CA group. NCT04107012. The protocol was published after trial commencement.

Clear aligner therapy for adult patient - A case report

Clear aligner therapy for adult patient - A case report - IJODR- Print ISSN No: - 2581-9356 Online ISSN No:- 2581-9364 Article DOI No:- 10.18231/j.ijodr.2020.009, IP Indian Journal of Orthodontics and Dentofacial Research-IP Indian J Orthod Dentofacial Res

Clear Aligner Therapy May Not Prevent But May Decrease the Incidence of External Root Resorption Compared to Full Fixed Appliances

Root resorption in orthodontic treatment with clear aligners: A systematic review and meta-analysis. Fang X, Qi R, Liu C. J Orthod Craniofacial Res 2019; Jul 19. doi: 10.1111. Natural Science Foundation of Guangdong Province, China. Systematic review-Meta-Analysis of Randomized Controlled Trials.

Comparison of external apical root resorption with clear aligners and pre-adjusted edgewise appliances in non-extraction cases: a systematic review and meta-analysis.

The aim of this study was to evaluate and compare the amount of external apical root resorption (EARR) observed during the orthodontic treatment with pre-adjusted edgewise appliance (PEA) or clear aligner therapy (CAT) and with 2D or 3D radiographic methods of measuring the root resorption. A search of PubMed MEDLINE, Scopus, Cochrane Central Register of Controlled Trials, LILACS, Web of Science, Dissertations & Theses Global, ClinicalTrials.gov registry, and the ISRCTN Registry was performed. Studies that have evaluated the amount of root resorption in non-extraction cases using CAT or PEA were selected for the systematic review. A meta-analysis was performed for the amount of root resorption of permanent maxillary incisors using PEA or CAT treatment modalities by either 2D or cone-beam computed tomography radiographic examination. Database research, elimination of duplicate studies, data extraction, and risk of bias were performed by authors independently and in duplication. A random-effect meta-analysis followed by subgroup comparisons were performed to evaluate EARR. A total of 16 studies (4 were prospective and 12 were retrospective) were identified for inclusion in the systematic review. The mean root resorption for the permanent maxillary incisors was in the range from 0.25 to 1.13 mm (overall: 0.49 mm; 95% confidence interval [CI] = 0.24 to 0.75 mm). The mean root resorption difference between CAT and PEA was statistically significant (P < 0.05) for 12 but not for 21, 11, or 22. One of the drawbacks is a lack of good quality prospective studies, specifically randomized clinical trials in the literature. Neither PEA or CAT technique leads to clinically significant root resorption (1 mm) of the maxillary incisors. The amount of EARR of maxillary incisors is not significant in comparing two treatment modalities (PEA and CAT), except for 12, where the PEA group has significantly more EARR when compared to CAT. 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 (https://www.crd.york.ac.uk/prospero/display_record.php?ID=CRD42018113051). This systematic review is reported according to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses statement.

Clear aligner therapy––Narrative review

Clear aligners are gaining more popularity, as most patients, especially adults, dislike the appearance of fixed appliances. In 1997, Align Technology© (Santa Clara, CA) released the Invisalign® system. The company used both computer-aided design (CAD) and computer-aided manufacturing (CAM) to produce its orthodontic appliances. This technology, which allows for multiple tooth movements from a single impression, introduced the clear aligner as it is now known. At the beginning, the Invisalign® system was used to treat simple tooth movement. However, as it developed, the manufacturer began using attachments and intermaxillary elastics to obtain different movements, so Invisalign® became a viable alternative to fixed appliances. Different aligner systems similar to Invisalign®, such as ClearCorrect, etc., became available on the market, and they use the same principle to obtain the desired results. This review investigated the indications and contraindications of clear aligner therapy (CAT), including its efficiency and limitations; patient comfort and acceptance; and periodontal health, root resorption, and stability. In conclusion, CAT has been improved over the last 18 years and is still being improved. The treatment results depend on the clinician’s own experience, case selection, and patient adherence. The clinician should be clear about the advantages and disadvantages of CAT, and the patient should be made aware that he/she should wear the appliance for 22–23h/day and only remove it while eating. The limitations of this study are lack of comparison between available CAT systems, the types and mechanics of movement produced by different types of attachments, and the cost.

The incidence and severity of root resorption following orthodontic treatment using clear aligners

Abstract Introduction The aim of this study was to assess the incidence and severity of root resorption in patients who were orthodontically treated by clear aligner therapy. Methods Linear tooth lengths of maxillary and mandibular teeth from the second molar to second molar were measured from pre- and post-treatment cone beam computed tomography examinations of 25 patients who were treated by a clear aligner system. Results Mean reductions in tooth length varied according to tooth type, with maxillary central and lateral incisors experiencing the most resorption, of 0.5 ± 0.41 mm and 0.4 ± 0.56 mm respectively. All tooth types had most resorption fall within the &lt;0.25 mm range, with 7% of central and lateral incisors accounting for resorption &gt;1.5 mm. Although the level of resorption identified in this study was less than that reported for fixed appliances, overall, the trends were similar. Conclusions Orthodontic treatment carried out with clear aligners resulted in root resorption that was largely clinically insignificant. There was a general trend towards more resorption affecting anterior teeth in both the maxilla and mandible. Original tooth length was found to be a predictor of the amount of resorption.

Effects of clear aligner therapy for Class II malocclusion on upper airway morphology and daytime sleepiness in adults: A case series

To evaluate the effects of clear aligner therapy (CAT) on the upper airway dimensions and on daytime sleepiness in adults with dentoskeletal Class II malocclusion. This study was conducted from August 2017 to February 2019. Inclusion criteria were healthy adults≥18years old, Angle Class II division 1 malocclusion, first-molar relationship of end-to-end or greater, overjet<10mm, and presenting for multi-arch comprehensive orthodontic treatment with aligners. Treatment mechanics included mandibular dentoalveolar advancement with Class II elastics without maxillary sequential distalization programmed into aligners. Post-treatment changes in dentoskeletal and upper airway dimensions were assessed using CBCT images. The treatment effect on daytime sleepiness was evaluated using an Epworth Sleepiness Scale (ESS). Eight subjects were included in this pilot study (mean age at treatment initiation=44.6years [SD=15.3]). The mean treatment duration was 12.2months (SD=3.4). No statistically significant treatment changes were observed in upper airway dimensions or dentoskeletal cephalometric analyses. Subjects with excessive daytime sleepiness at pre-treatment reported an improvement post-treatment, but no significant difference in the mean ESS score was found. Treatment of Class II division 1 malocclusion in adults by mandibular dentoalveolar advancement using CAT has no statistically significant effects on the airway and dentoskeletal measurements, or daytime sleepiness.

Comparison of Short-Term Oral Impacts Experienced by Patients Treated with Invisalign or Conventional Fixed Orthodontic Appliances

Objectives: Our objective was to test the hypothesis that thermoplastic clear aligners (Invisalign®; Align Technology, Santa Clara, CA, USA) are more pleasant for patients than conventional fixed orthodontic appliances. Subjects and Methods: This was an observational retrospective study in which subjects were matched for age, treatment modality, and the treating orthodontist. A total of 60 adult patients (30 in the Invisalign group and 30 in the conventional buccal fixed appliance group) who met the inclusion criteria completed a validated self-reporting questionnaire, rating their experience after appliance activation in regard to oral impact experience and satisfaction of both treatment modalities. Categorical variables were compared using the χ² test, Fisher’s exact test, and the Z test. Continuous variables such as pain level and age were analyzed using the 2-sample t test. Results: Patients on clear aligner therapy reported significantly more difficulty in speech (p = 0.035) necessitating change in speech delivery (p = 0.003). In addition, they reported better chewing ability (p < 0.001), no restrictions on amounts or types of food (p = 0.02), and less mucosal ulcerations (p = 0.01). Effects on daily routine, use of analgesics, and overall treatment satisfaction were not significantly different between the 2 groups. Conclusion: Clear aligner therapy is not necessarily more pleasant, but it is more tolerable as it satisfies patient needs over food consumption and absence of mucosal ulcerations. However, clear aligners affect pronunciation and speech delivery in the short term.

Clear aligner therapy: risks and clinical strategies

Clear aligner, as a transparent and removable appliance, offers an alternative to conventional fixed appliance to patients with high demands for esthetics and comfort. Meanwhile, the rapid development of materials and techniques has made clear aligner more widely used in orthodontics. However, there are still several concerns and risks in clinical practice of clear aligners, which may result in unfavorable outcomes. Herein, we have discussed the clinical risks of clear aligner therapy, and provided some targeted strategies, in order to promote the clinical application of clear aligners.

Effectiveness of clear aligner therapy for orthodontic treatment: A systematic review.

To analyse through a systematic review the effectiveness of clear aligners by assessing: (a) predictability of clear aligners and (b) treatment outcome comparison of clear aligner therapy with fixed appliance therapy. An electronic search was made from January 2014 to April 2019 using MEDLINE, Embase, Web of Science and LILACS databases without any limitations on language. Three reviewers independently assessed the articles. Quality assessment of observational studies and randomized control trial was done by using the ROBINS tool and Cochrane risk of bias tool, respectively. GRADE instrument was used to assess certainty level for each identified outcome. Seven eligible articles (one randomized controlled trial and six retrospective cohort) were included in our systematic review. Most of the studies (six out of seven) had a moderate risk of bias and one had a high risk of bias. 'Low to moderate level' of certainty in regard to specific clear aligner therapy tooth movements' efficiency was identified. Clear aligners may produce clinically acceptable outcomes that could be comparable to fixed appliance therapy for buccolingual inclination of upper and lower incisors in mild to moderate malocclusions. However, not all potential clinical scenarios have been assessed in the included studies. Most of the tooth movements may not be predictable enough to be accomplished with only one set of trays with clear aligners despite the recent advances in technology.

Direct-to-consumer clear aligner therapy comes to the UK

Direct-to-consumer clear aligner therapy comes to the UK

Referral patterns of pediatric dentists and general practitioners to orthodontists based on case complexity.

The objectives of this research were to investigate and compare general and pediatric dentists' subjective judgments of orthodontic case complexity and to determine how their perceptions of case complexity influence their decisions to refer the patient to an orthodontist. Twenty pediatric dentists and 21 general dentists participated in the study. Pretreatment orthodontic records of 20 patients with a variety of malocclusions and a range of American Board of Orthodontics Discrepancy Index (DI) scores were used. Respondents were asked about their background and training in orthodontics. They were also asked to identify the subjective complexity of each case with the use of a 100-point visual analog scale (VAS) and whether they would refer the patient to an orthodontic specialist. A mixed-model multivariate data analysis was used to evaluate the subjective case complexity with the use of fixed factors such as DI score, type of panel member, experience, annual continuing education rate, and gender. Generalized linear mixed models were used to investigate the referral patterns of the general dentists and pediatric dentists. Level of significance was set at P<0.05 for all statistical analyses. General dentists appeared to provide more overall orthodontic treatment than pediatric dentists; many general dentists provide limited orthodontic treatment and clear aligner therapy (P<0.05). The perceived complexity score for cases was not significantly different between the 2 groups (P=0.82). The association between DI score and perceived complexity was similar in both groups (P=0.183) and there was a high correlation between DI and VAS score in the sample (r=0.71; 95% Cl 0.38-0.87). Pediatric dentists had higher referral rates for cases with DI scores both below and above 20. Significant differences were noted between the pediatric and general dentists in the individual case referral decision as evaluated by the DI (P<0.037) and VAS (P<0.042) scores. General dentists provided more orthodontic care than the pediatric dentists. Both groups identified case complexity similarly, with only minor differences, but pediatric dentists had higher referral rates to orthodontic specialists regardless of the initial case complexity.

Clear Aligner Therapy Might Provide a Better Oral Health Environment for Orthodontic Treatment Among Patients at Increased Periodontal Risk

Periodontal health during orthodontic treatment with clear aligners and fixed appliances: A meta-analysis. Jiang Q, Li J, Mei L, Du J, Levrini L, Abbate GM, LiH. J Am Dent Assoc 2018;149(8):712-20.e12. The work was supported by grants 81470712 and 81670960 from the National Natural Science Foundation of China, by grant BK20171123 from the Natural Science Foundation of Jiangsu Province, and by grant YKK17140 from the Medical Science and Technology Development Foundation, Nanjing Department of Health. Systematic review with meta-analysis of data.

Clear Aligner Orthognathic Splints

Orthodontic treatment has been transformed by the introduction and overwhelming adoption of clear aligner therapy (CAT). Many patients are demanding esthetic and metal-free treatment alternatives, including those requiring orthognathic surgery (OGS), to correct their dentofacial deformities. The adoption of performing OGS for CAT has been cautious and challenging for many reasons. Intermaxillary fixation, postoperative occlusal control, preoperative decompensation management, and long-term stability need to be tested and assessed. This report presents an accurate 3-dimensional (3D) printed hard acrylic splint specifically for patients without any orthodontic attachment to be used in the positioning and fixation of osteotomized jaws. It is simple to manufacture and its use intraoperatively is efficient, straightforward, and accurate. This report introduces the Clear Aligner Orthognathic Splint for surgery and the steps required for 3D planning with recommendations for perioperative orthodontic support.

Cephalometric comparison of adult anterior open bite treatment using clear aligners and fixed appliances.

To compare fixed appliances and clear aligner therapy in correcting anterior open bite and in controlling the vertical dimension in adult patients with hyperdivergent skeletal patterns. In this retrospective study, two treatment groups of adult (≥18 years old) hyperdivergent patients (mandibular plane angles of ≥38°) with anterior open bites were included: 17 fixed appliance patients and 36 clear aligner patients. Thirteen cephalometric measurements representing the vertical dimension were reported for each group. A two-sample t-test was used to assess differences in changes in mandibular plane angle and overbite between the two treatment groups. There were no statistical differences found in the magnitude of overbite correction and the changes in any of the cephalometric measurements for vertical control. The clear aligner group showed a slightly greater amount of lower incisor extrusion ( P = .009). The main mechanism of open bite correction was similar between the two treatment groups and was accomplished through retroclination of the upper and lower incisors while maintaining the vertical position of the upper and lower molars. Cephalometric comparison of anterior open bite correction and changes in the mandibular plane angle associated with use of clear aligners and fixed appliances did not demonstrate statistically significant differences in adult hyperdivergent patients.

Apical root resorption during orthodontic treatment with clear aligners: A retrospective study using cone-beam computed tomography.

We aimed to investigate the incidence and severity of orthodontically induced inflammatory root resorption (OIIRR) on maxillary incisors with clear aligner therapy using cone-beam computed tomography and to identify possible risk factors. The root lengths of maxillary incisors were measured on orthogonal images from pretreatment and posttreatment cone-beam computed tomography examinations of 160 patients who received comprehensive orthodontic treatment with clear aligners. Mean absolute reductions in root length varied between 0.47±0.61mm and 0.55±0.70mm and were not significantly different between maxillary central and lateral incisors. The prevalence of severe OIIRR, defined as both maxillary central incisors experiencing greater than a 25% reduction in root length, was found to be 1.25%. Potential risk factors included sex, malocclusion, crowding, and posttreatment approximation of apices to the cortical plates. Race, interproximal reduction, previous trauma to the teeth, elastics, age, treatment duration, and pretreatment approximation of apices to the cortical plates did not significantly affect the amount of OIIRR. Comprehensive treatment with clear aligners resulted in minimal root resorption. Sex, malocclusion, crowding, and posttreatment approximation to the cortical plates significantly affected the percentage of change in root length. Posttreatment approximation of root apices to the palatal cortical plate showed the strongest association for increased OIIRR.