Efficiency, effectiveness and treatment stability of clear aligners: A systematic review and meta-analysis

The best method of reconditioning ceramic brackets to get an optimum shear bond strength compared with new ceramic brackets - Systematic review and meta-analysis of in vitro studies

PURPOSE

Bracket debonding is an undesirable problem during fixed orthodontic treatment. As ceramic brackets have no flexibility, there is no change in the slot dimension. So, reconditioning a ceramic bracket can be done without compromising the quality of treatment and could be a cost-effective measure. The objective of this systematic review is to deduce and validate the best method of reconditioning ceramic bracket in order to get optimum clinical shear bond strength.

MATERIAL AND METHODS

Studies such as randomized controlled trials (RCTs); In vitro studies comparing different interventions with control group, cross sectional studies were included. Electronic databases such as Cochrane database, PubMed, Web of Science, Embase were searched up to July 2022. Grey literature search and cross-referencing/snowballing methods were also used. Two reviewers independently selected studies and assessed the risk of bias using amalgamation of five tools for in vitro studies. Then meta-analysis was performed using random effects model.

RESULTS

Eleven studies were included in which ten studies were considered as good quality studies. According the meta-analysis performed, the best performance in terms of shear bond strength was of new brackets. Among the different reconditioning methods, the meta-analysis showed that the method with the closest bond strength to the new brackets was silicatisation with a mean difference of 6.35MPa (95% CI between 2.39 and 10.31) followed by sandblasting+silane application with a mean difference of 3.36MPa (95% CI between 0.3 and 6.96) compared to other methods.

CONCLUSIONS

Due to the lack of in vivo studies, only in vitro studies were evaluated. The data available from the in vitro studies was considered to be of good quality, leading to the conclusion that the best method for reconditioning debonded ceramic brackets is silicatisation followed by sandblasting and silane application.

Maxillary Impacted Canine and Upper Lateral Incisor Agenesis Treatment with "Canine First Technique" and Clear Aligners: A Case Report

The aim of this study was to show a case of an impacted canine in an adult patient with agenesis of the maxillary lateral incisor treated with clear aligners (CA). A 19-year-old male with a persistence of 5.3 and absence of 1.2 came to our department of the School of Orthodontics at the University of Federico II in Naples and asked for an aesthetic treatment. The Canine First approach was used to surgically expose the canine and pull it into the dental arch. In order to ensure long-term aesthetic, periodontal, and occlusal results, a treatment with CAs to close the space through the mesial placement of the canine and the enameloplasty of the tooth crown was performed. At the end of the treatment, the occlusal objectives were achieved.

Perceived esthetics and value of clear aligner therapy systems: A survey among dental school instructors and undergraduate students

OBJECTIVE

To investigate the attractiveness, acceptability, visibility and willingness-to-pay for clear aligner therapy (CAT) systems in first-year and final-year dental students and instructors.

METHODS

A questionnaire designed to collect information regarding esthetic preferences and intentions related to seven CAT systems was handed out to 120 undergraduate students and instructors at the Academic Centre for Dentistry Amsterdam (ACTA). Proportional odds models and population average generalized estimating equation models were used to examine potential association between participant characteristics, esthetic perceptions and CAT systems.

RESULTS

Overall, the examined CAT systems received favorable esthetic ratings. Expertise status was significantly associated with willingness-to-pay additionally for CAT, compared to fixed orthodontic appliances. There was no association between sex, previous orthodontic treatment history, satisfaction with own dental appearance and potential interest in treatment and aligner visibility and willingness-to-pay. CAT system was significantly associated with the perceived aligner visibility, acceptability and attractiveness by students and instructors.

CONCLUSIONS

CAT systems were considered to a great extent attractive and acceptable for future treatment by dental school instructors and students. Willingness-to-pay for CAT systems was significantly associated with expertise status, with instructors appearing more reluctant to pay for CAT.

Three-dimensional spatial analysis of the temporomandibular joint in adult patients with Class II division 2 malocclusion before and after orthodontic treatment: a retrospective study

BACKGROUND

To investigate changes in the three-dimensional (3D) spatial morphology of the temporomandibular joint (TMJ) and condyle position in adult patients with Class II division 2 malocclusion using a 3D spatial measurement method and to investigate the similarities and differences in the effects of fixed appliance and clear aligner treatments on the TMJ.

METHODS

Cone-beam computed tomography (CBCT) data of 47 adult patients with Class II division 2 malocclusion (25, fixed appliance group; 22, clear aligner group) were collected before and after treatment. Mimics 21.0 was used to reconstruct the TMJ 3D model. Fourteen measurement items, such as the anterior, upper, and posterior joint spaces, were measured directly on the 3D model and compared.

RESULTS

Post-orthodontic treatment, the shape and position of the condyle changed in adult patients with Class II division 2 malocclusion. Reduction in the anterior joint space and increase in the posterior joint space after orthodontic treatment were significant in both fixed appliance and clear aligner treatments; the condyle moved forward to the center of the fossa. The superior joint space and depth of the glenoid fossa increased after clear aligner treatment, but there was no significant change after fixed appliance treatment.

CONCLUSIONS

The condylar shape and position in patients with Class II division 2 malocclusion changed significantly post-treatment, indicating that the condyle undergoes adaptive reconstruction during orthodontic treatment in these patients. These results provide a reference for diagnosis, design of treatment plan, and monitoring of treatment in orthodontic clinics.

Dental Restorations

Fulfilling a patient's request for a healthy, functional and esthetic smile represents a daily challenge for dental practitioners [...].

Effect of thermomechanical aging of orthodontic aligners on force and torque generation: An in vitro study

The aim of the study is to investigate the effects of artificial aging by thermocycling and mechanical loading on force/torque delivery by thermoplastic orthodontic aligners. Ten thermoformed aligners, made of Zendura™ thermoplastic polyurethane sheets, were aged over two weeks in deionized water by thermocycling alone (n = 5) and by both thermocycling and mechanical loading (n = 5). The force/torque generated on upper second premolar (Tooth 25) of a plastic model was measured before aging (as control), and after 2, 4, 6, 10, and 14 days of aging, using a biomechanical set-up. Before aging, the extrusion-intrusion forces were in the range of 2.4-3.0 N, the oro-vestibular forces were 1.8-2.0 N, and the torques on mesio-distal rotation were 13.6-40.0 Nmm. Pure thermocycling had no significant effect on the force decay of the aligners. However, there was a significant decrease in force/torque after 2 days of aging for both thermocycling and mechanical loading aging group, which is no longer significant over 14 days of aging. In conclusion, artificial aging of aligners in deionized water with both thermocycling and mechanical loading results in a significant decrease in force/torque generation. However, mechanical loading of aligners has a greater impact than pure thermocycling.

Effects of different designs of orthodontic clear aligners on the maxillary central incisors in the tooth extraction cases: a biomechanical study

BACKGROUND

Controlling the 3D movement of central incisors during tooth extraction cases with clear aligners is important but challenging in invisible orthodontic treatment. This study aimed to explore the biomechanical effects of central incisors in tooth extraction cases with clear aligners under different power ridge design schemes and propose appropriate advice for orthodontic clinic.

METHODS

A series of Finite Element models was constructed to simulate anterior teeth retraction or no retraction with different power ridge designs. These models all consisted of maxillary dentition with extracted first premolars, alveolar bone, periodontal ligaments and clear aligner. And the biomechanical effects were analysed and compared in each model.

RESULTS

For the model of anterior teeth retraction without power ridge and for the model of anterior teeth no retraction with a single power ridge, the central incisors exhibited crown lingual inclination and relative extrusion. For the model of anterior teeth no retraction with double power ridges, the central incisors tended to have crown labial inclination and relative intrusion. For the model of anterior tooth retraction with double power ridges, the central incisors exhibited a similar trend to the first kind of model, but as the depth of the power ridge increased, there was a gradual decrease in crown retraction value and an increase in crown extrusion value. The simulated results showed that von-Mises stress concentration was observed in the cervical and apical regions of the periodontal ligaments of the central incisors. The clear aligner connection areas of adjacent teeth and power ridge areas also exhibited von-Mises stress concentration and the addition of power ridge caused the clear aligner to spread out on the labial and lingual sides.

CONCLUSIONS

The central incisors are prone to losing torque and extruding in tooth extraction cases. Double power ridges have a certain root torque effect when there are no auxiliary designs, but they still cannot rescue tooth inclination during tooth retraction period. For tooth translation, it may be a better clinical procedure to change the one-step aligner design to two-step process: tilting retraction and root control.

Effectiveness and predictability of treatment with clear orthodontic aligners: A scoping review

INTRODUCTION

In an ideal clinical setting, orthodontic therapy with clear aligners (CA) should improve the patients' initial malocclusion and must guarantee equivalence between the results predicted and those obtained clinically to be considered an effective treatment. Therefore, this scoping review aimed to identify the orthodontic literature concerning the effectiveness and predictability of CA treatments.

METHODS

A systematic computerized search was performed in 3 databases: PubMed, Scopus, and Embase. Inclusion criteria selected observational and clinical studies performed in at least 10 adult orthodontic patients, whose results of CA treatment's effectiveness and/or predictability were assessed.

RESULTS

The 3 database computerized searches resulted in 1,553 articles, and 169 full texts were considered potentially relevant. After applying the eligibility criteria, 33 studies were included. Most studies (76%) were designed as cohort studies and have been published in the last 5 years (79%). The majority included only non-extraction treatments (73%), and 79% reported results achieved with the Invisalign® system. The most predictable movement was the buccolingual tipping, while the least predictable movements were rotation, intrusion, and extrusion. Aligner treatment was effective for mild to moderate crowding resolution, and the success of overbite correction still seems to be limited.

CONCLUSIONS

The studies have demonstrated improvement of initial malocclusion through CA treatments. Still, predictability degree is overestimated and does not accurately reflect the occlusion immediately at the end of treatment. In future studies, there should be an effort to broaden the utilization of alternative aligner systems beyond Invisalign® and broadly disseminate their outcomes to strengthen clear aligners evidence base.

Alveolar bone changes following bi-maxillary vertical molars' movements using clear aligners

OBJECTIVE

This study aimed to assess the alveolar bone changes following maxillary and mandibular molars' intrusion and extrusion movements using Clear Aligners using Cone-Beam Computed Tomography (CBCT).

MATERIALS AND METHODS

This is a retrospective clinical study in which 24 adult patients with pre-designed selection criteria and a mean age of 31.1 + 9.9 years were enrolled. The alveolar bone changes around one hundred thirty-three maxillary and mandibular molars intruded or extruded by Clear Aligners therapy were analyzed from CBCT using Invivo 6.0 software. Intra- and inter-examiner reliability analysis was performed using the intra-class correlation coefficient (ICC) and Cronbach's Alpha statistics. The paired t-test was used to analyze significant differences before and after treatment (T0-T1). The significance level was considered at P < 0.05.

RESULT

The patients were divided into two groups: extrusion (48.9%, n = 65 molars' root) and intrusion (51.1%, n = 68 molars' root) group. There was a significant decrease in the alveolar bone changes in the buccal surface of the mandibular right and left 1st molars in the extrusion group (-1.05 ± 0.97, -0.76 ± 1.12 mm, respectively) and the maxillary left 2nd molars in intrusion group (-0.42 ± 0.77 mm), and the lingual surface of intrusion of the mandibular left 1st molar (-0.64 ± 0.76 mm). Comparing the mean maxillary and mandibular changes (T0-T1) of both studied groups showed that the buccal alveolar bone changes for the left 1st and right 2nd molars showed a significant difference in extrusion and intrusion groups, respectively.

CONCLUSIONS

The buccal alveolar bone changes is considered the most affected surface following maxillary and mandibular molars' intrusion and extrusion movements using clear aligners, with mandibular molars being more affected than the maxillary ones.

The effects of aligner anchorage preparation on mandibular first molars during premolar-extraction space closure with clear aligners: A finite element study

INTRODUCTION

This study aimed to determine the effectiveness of different aligner anchorage preparations on mandibular first molars during premolar-extraction space closure with clear aligners and to assess the effects of different modes of Class II elastics on mandibular first molars.

METHODS

Finite element models were constructed on the basis of cone-beam computed tomography data from an orthodontic patient. The models comprised maxilla, mandible, maxillary and mandibular teeth without first premolars, periodontal ligaments, attachments and aligners. Tooth displacement tendencies were calculated using different aligner anchorage preparations and Class II elastics on the models from the same patient. Three group sets were designed on the basis of the positions of aligner cutouts and buttons (mesiobuccal, distobuccal and lingual). Four groups were established in each of the 3 group sets. Four groups were created: (1) no elastic traction + no anchorage preparation, (2) anchorage preparation only, (3) elastic traction only, and (4) elastic traction + anchorage preparation. Different aligner anchorage preparations (0°, 1°, 2°, 3°) were applied on mandibular second premolars and molars. The Class II traction force was set to 100 g.

RESULTS

With clear aligners, mandibular first molars were subject to mesial tipping, lingual tipping and intrusion. In the condition of no elastic traction, aligner anchorage preparation resulted in distal tipping, buccal tipping, and extrusion effect on mandibular first molars. Aligner anchorage preparation was more effective in the distal and lingual cutout groups than in the mesial cutout group. In the condition of Class II elastic traction, the bodily movement of mandibular first molars was achieved with a 3° anchorage preparation for the mesial cutout group and a 1.7° anchorage preparation for distal and lingual cutout groups. Absolute maximal anchorage was achieved with a 2° anchorage preparation for distal and lingual cutout groups.

CONCLUSIONS

Clear aligner therapy caused mesial tipping, lingual tipping and intrusion of mandibular first molars during premolar-extraction space closure. Aligner anchorage preparation effectively prevented mesial and lingual tipping of mandibular molars. Distal and lingual cutout modes were more effective than mesial cutout modes in aligner anchorage preparation. For each aligner stage (0.25 mm), 1.7° aligner anchorage preparation and Class II elastics with distal or lingual cutouts led to the bodily movement of mandibular first molars, whereas 2° anchorage preparation reached absolute maximal anchorage.

Advances in orthodontic clear aligner materials

Rapid technological improvements in biomaterials, computer-aided design (CAD) and manufacturing (CAM) have endorsed clear aligner therapy (CAT) as a mainstay of orthodontic treatment, and the materials employed for aligner fabrication play an all-important role in determining the clinical performance of clear aligners. This narrative review has attempted to comprehensively encompass the entire gamut of materials currently used for the fabrication of clear aligners and elucidate their characteristics that are crucial in determining their performance in an oral environment. Historical developments and current protocols in aligner fabrication, features of contemporary bioactive materials, and emerging trends related to CAT are discussed. Advances in aligner material chemistry and engineering possess the potential to bring about radical transformations in the therapeutic applications of CAT; in the absence of which, clear aligners would continue to underperform clinically, due to their inherent biomechanical constraints. Finally, while innovations in aligner materials such as shape memory polymers, direct three-dimensional (3D) printed clear aligners and bioactive materials combined with clear aligner materials are essential to further advance the applications of CAT; increased awareness of environmental responsibilities among aligner manufacturers, aligner prescribing clinicians and aligner users is essential for better alignment of our climate change goals towards a sustainable planet.

Biomechanical factors in the open gingival embrasure region during the intrusion of mandibular incisors: A new model through finite element analysis

Introduction: Open gingival embrasure (OGE) is a common complication in adults following clear aligner therapy and the influence of gingival or alveolar bone biotype on OGE is of great concern. Unfortunately, due to the limited number of patients with clearaligner therapy and the clinical methods to distinguish the gingival biotype of patients being invasive, it is difficult to carry out clinical studies on the gingival or alveolar bone biotype of the OGE. In the meanwhile, the detailed biomechanics of the occurrence of OGE remains unknown. The goal of this study was to establish a new model to simulate the virtual space region, namely, the OGE region, to investigate the relationship between alveolar bone biotype and the occurrence of OGE, and explore potential biomechanical factors related to OGE.

Methods: The OGE region in the interproximal space was established using a filler with a very low modulus of elasticity (1 × 10−6 MPa). To illustrate the biomechanics of OGE more exhaustively, a line was created at the top of the alveolar crest along the proximal tooth root. FEA was then used to analyze the biomechanics of the surrounding tissues, the OGE region and the line at the top of the alveolar crest along the proximal tooth root of the central incisor under two different labial bone thicknesses (thick and thin) with an axial inclination of 80°, 90° and 100°.

Results: During intrusion of the incisors in clear aligner therapy, as inclination increased or bone tissue became thinner, the stress in the surrounding tissues [tooth root, alveolar crest, and periodontal ligament (PDL)] was greater. In the OGE region and interproximal alveolar crest, the strain increased with increasing inclination and labial bone thinning. The results from the line at the top of the alveolar crest along the proximal tooth root showed more detailed biomechanics: In all groups, stress and strain were focused on the mesial-labial alveolar crest. Interestingly, our results also demonstrated that when OGE occurs, other complications may arise, including root resorption and bone dehiscence.

Short-term effect of orthodontic clear aligners on muscular activity and occlusal contacts: A cohort study

INTRODUCTION

The simultaneous presence of maxillary and mandibular clear aligners alters the vertical dimension and the quantity and quality of occlusal contacts. Few data in the literature explain how this occurs and the effects on neuromuscular coordination. This study aimed to evaluate occlusal contacts and muscular balance during treatment with clear aligners over a short follow-up time.

METHODS

Twenty-six female adult patients were enrolled in this study. The center of occlusal force (COF) was evaluated using a T-Scan II device, whereas muscular symmetry and balance were determined through surface electromyography using a standardized protocol that reduces anthropometric and electrode variations. Both evaluations were performed in centric occlusion and with aligners worn before treatment, after 3 months, and after 6 months.

RESULTS

A statistically significant variation in COF position was reported in the sagittal plane but not in the transverse plane. The shift in the COF position was followed by a change in muscular balance evaluated through surface electromyography.

CONCLUSIONS

Treatment with clear aligners resulted in an anterior shift of the COF when biting in centric occlusion and a posterior shift when the aligners were worn in healthy female patients after 6 months of observation. This change in occlusal contact was followed by an improvement in muscular function symmetry in the short term when aligners were worn, compared with the centric occlusion during treatment.

Combined use of F22 aligners and intermaxillary elastics in mild skeletal Class II: Two case reports

INTRODUCTION

The aim of these two case-reports is to illustrate and compare the therapeutic effects of Class II elastics in combination with F22 aligners in an adult and an adolescent patient, respectively.

CASE PRESENTATION

Two patients with a mild skeletal Class II malocclusion, associated with mild-to-moderate crowding, presented for orthodontic treatment. The first patient was 12 years old, while the second was 40 years old. In both cases, the goal was to obtain bilateral molar and canine Class I with ideal overjet and overbite, and Class II skeletal relationship improvement in the young patient as well. Both treatments were approached without extractions and using clear aligners (CAs) in combination with Class II elastics, giving the patient the opportunity to take advantage of a therapy that is both comfortable and aesthetic.

DISCUSSION

Final records of both cases demonstrate how appropriate analysis and diagnosis enable CAs in conjunction with Class II elastics to be used with considerable efficiency and efficacy for Class II treatment. In the first case, the key to success was exploiting residual jaw growth, while in the second case it was careful orthodontic digital planning.

CONCLUSION

In the presence of good patient compliance, CAs associated with Class II elastics provide satisfactory occlusal outcomes if biomechanics and digital set-up are carefully evaluated and executed and if diagnosis is appropriate.

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.

Clear Aligners Treatment of Class III Subdivision with an Extraction of a Lower Bicuspid

The aim of this study was to show a case of a Class III subdivision adult patient treated with clear aligners (CA) and the extraction of a lower bicuspid. A 19-year-old male with a class III canine and molar relationship on the right side and a deviation of lower dental midline to the left asked for an aesthetic treatment. He refused orthognathic surgical procedures, so he was offered a camouflage orthodontic treatment with the extraction of lower right first premolar to achieve a canine Class I relationship and to center the lower midline. The treatment was performed with clear aligners and the use of Class III elastics to maintain distal anchorage on the right side during the canine distalization. At the end of the treatment, the occlusal objectives were achieved.

Quality assessment of online information on orthodontic Web sites in the United States

INTRODUCTION

The objective of this study was to assess the quality of online information on orthodontic treatment provided by orthodontic Web sites in the United States and investigate their claims.

METHODS

Three hundred and one American orthodontic Web sites were identified after an advanced Google search. Data collection included: the location of the clinic, treatment options offered, quality-of-information assessment using the DISCERN tool, and finally, claims when promoting 1 treatment option against another, as well as the presence of information on relapse risk and retention needs.

RESULTS

All Web sites belonged to private clinics, with more than half (60.5%) in a single location. Invisalign (Align Technology, Santa Clara, Calif) was the most commonly promoted treatment option (94%), followed by the full fixed appliance (FFA) (92%). The mean DISCERN total score was poor (36.78 out of 80.00), whereas the mean reliability (questions 1-8) and quality-of-information (questions 9-15) scores were 17.06 out of 40.00 and 16.85 out of 35.00, respectively. Almost one-third (28%) of the Web sites compared aligners to FFA, whereas 25% claimed that aligners are less painful than FFA, faster than FFA (14%), or give better results than FFA (1%). Almost half of the Web sites (47%) failed to display information on relapse risk and retention needs after orthodontic treatment (41%). The Web sites that displayed such info had higher DISCERN total scores (P <0.001).

CONCLUSIONS

Invisalign seems to be the treatment modality most commonly mentioned online. According to DISCERN, U.S. orthodontic Web sites display poor or fair quality information. On many Web sites, aligner treatment was compared with FFA, with some stating that aligners cause less pain than FFA or are more efficient/faster than FFA. Moreover, almost half of the American orthodontic Web sites failed to display information on the relapse risk or retention need. Display of such information can be an indicator of better-quality Web sites. There is ample room for improvement in the online information American orthodontists provide to potential patients.

Predictability of the deep overbite correction using clear aligners

INTRODUCTION

The objective of this study was to investigate the predictability of overbite correction in patients with deepbite using the clear aligners (Invisalign, Align Technology, San Jose, Calif) and examine the accuracy of vertical movement and inclination change of individual teeth.

METHODS

This retrospective study included 24 deepbite patients (10 males and 14 females; aged 32.8 ± 11.9 years; an initial overbite of 5.20 ± 0.95 mm; an average treatment period of 11.04 ± 4.14 months) consecutively treated from September 2016 and completed before August 2021. SmartTrack materials were used for all patients. The initial, predicted, and achieved final models were exported from ClinCheck and superimposed via best-fit surface-based registration using Slicer CMF (version 4.9.0; cmf.slicer.org). The overbite correction, changes in vertical movement, and inclination for individual teeth were measured. Descriptive statistics and a paired t test or Wilcoxon signed-rank test were performed. P <0.05 was considered statistically significant.

RESULTS

Mean overbite correction was 33%, with a 1.15 mm improvement after the first set of aligners. All teeth demonstrated statistically significant differences between planned and achieved amounts in vertical movement and inclination change, with the largest difference in maxillary central incisors. Mandibular incisor intrusion and mandibular premolar extrusion had similar accuracies. Regarding inclination change, maxillary central incisors showed the lowest accuracy of 13.3%.

CONCLUSIONS

Clear aligner treatment showed an average of 33% overbite correction. Overcorrection and additional refinement treatments are needed in most patients with a deepbite.

IPR treatment and attachments design in clear aligner therapy and risk of open gingival embrasures in adults

BACKGROUND

The incidence of open gingival embrasures (OGE) in patients after fixed appliance treatment is relatively high, while there are no detailed reports on patients after clear aligner therapy. Also, no clinical studies with large sample size have investigated whether interproximal enamel reduction (IPR) can actually avoid OGE. The purpose of this study was to determine the prevalence of OGE in adults after clear aligner therapy and to investigate the risk of OGE associated with IPR treatment and attachment design, focusing on the amount and distribution in mandibular anterior teeth.

METHODS

Pre-treatment and post-treatment intraoral frontal photographs of 225 non-extraction patients were evaluated retrospectively for the occurrence and severity of OGE. The amount of IPR and the number of attachments in the anterior teeth from subjects after screening were recorded according to the first version of clear aligner software (Clincheck, San Jose, USA) and clinical medical documents. Logistic regression analysis was performed to identify the factors contributing to OGE.

RESULTS

The incidence of OGE in non-extraction patients after clear therapy between maxillary and mandibular central incisors was 25.7% and 40.3%, respectively. IPR was not associated with the occurrence of OGE but was associated with severity (P < 0.05). The number of attachments in the anterior teeth or central incisors was significantly related to the incidence of OGE (P < 0.05) but was not associated with severity.

CONCLUSION

A high rate of OGE occurs after clear aligner therapy. Clinicians should be aware of the application of IPR and the design of attachments during clear aligner therapy.

Analysis of overcorrection to be included for planning clear aligner therapy: a retrospective study

OBJECTIVES

To provide clinical information on overcorrection to be included in the initial digital setup to make clear aligner therapy (CAT) more efficient.

MATERIALS AND METHODS

Prescription data for 150 patients (80 women and 70 men; mean age 33.7 ± 12.7 years) treated successfully with CAT (F22 Aligners, Sweden & Martina, Due Carrare, Italy) and requiring only a single, minimal finishing phase were acquired retrospectively. The inclusion criteria were Class I dental malocclusion with only minimal crowding (≤3 mm), 12-20 aligner steps per arch, no use of auxiliaries or interarch elastics, and rotations ≤25° for round-shaped teeth. The prescribed and corrective movements to be achieved in the main and finishing treatment phases, respectively, were quantified by the dedicated clear aligner setup software. The magnitudes of inclination (buccal-lingual crown tipping), angulation (mesial-distal crown tipping), rotation, intrusion, and extrusion were extracted and analyzed by tooth type, maxilla and mandible, and both arches. Descriptive statistics, that is, mean, standard deviation, and percentage, were calculated for each movement investigated. Classification and regression trees (CART) were generated using the model-based recursive partitioning approach, and the corrective movements were correlated with respect to both the amount of the movements prescribed and the tooth type. Statistical significance was set at 5%.

RESULTS

Inclination and rotation required the greatest correction, whereas angulation, intrusion, and extrusion required only minimal correction. Expressed as a percentage of prescribed movement, mean corrective movements were 20.5% for inclination, 14.5% angulation, 28.4% rotation, 11.7% extrusion, and 22% intrusion. According to CART, all corrective movements except extrusion depended on both tooth type and the magnitude of prescribed movement.

CONCLUSIONS

To achieve more efficient CAT, approximately 20% overcorrection should be added to the initial planning phase when planning challenging movements such as inclination and rotation.

Edge level of aligners and periodontal health: a clinical perspective study in young patients

INTRODUCTION

Although the superiority of clear aligners over multi-bracket appliances in keeping gingiva healthy has been suggested, the possible benefits of one aligner design over another have not yet been investigated, especially with regard to the vestibular edge.

OBJECTIVE

The aim of this study was to measure several periodontal indexes in adolescents undergoing orthodontic treatment with aligners, comparing two different types of rim.

METHODS

The study involved 43 patients aged between 14 and 18 years. The periodontal health was assessed using plaque index (PI), gingival index (GI), and gingival bleeding index (GBI), at the start of the treatment with aligners (T0), with a vestibular rim (VR) reaching up to 3 mm beyond the gingival margin. Three months later (T1), aligners were set to obtain a juxtagingival rim (JR) on the second quadrant and VR on the first quadrant. The periodontal indexes were measured again, both at T1 and then three months later (T2).

RESULTS

Intra-quadrant comparisons revealed a statistically significant worsening of the periodontal indexes only for the second quadrant (p<0.05), at T1 (GI), and especially at T2 (PI, GI, GBI), while no statistically significant changes were found for the first quadrant.

CONCLUSIONS

More severe mechanical irritation, especially during insertion and removal of the aligner, can explain the worsening inflammatory indexes with the JR. In addition, the pressure exerted by the JR on the gingival sulcus seemed to facilitate plaque deposition, whereas the VR had a protective effect, reducing the risk of mechanical trauma.

Upper arch dimensional changes with clear aligners in the early mixed dentition : A prospective study

BACKGROUND

One goal of orthodontic treatment in mixed dentition is to expand the maxillary arch to allow proper tooth alignment and a correction of sagittal and vertical malocclusions. However, for most treatment protocols, expected outcome is not really clear to allow for a standardization of phase I orthodontic treatments. This lack of information makes it difficult for clinicians to predict tooth movements, including transverse expansion efficacy with Invisalign® (Align Technology, Santa Clara, CA, USA) in children. Therefore, the aim of the present study was to evaluate the transverse maxillary arch development with the Invisalign First System® in growing subjects.

METHODS

The study group included 23 subjects (9 females, 14 males, mean age 9.4 ± 1.2 years). Patients were treated nonextraction with Invisalign First System® clear aligners with no auxiliaries other than Invisalign® attachments. Transverse interdental widths were measured only in the upper arch on each model at the start (T1) and at the end (T2) of treatment. A paired t‑test was chosen to compare T2-T1 changes. The level of significance was set at 5%.

RESULTS

The greatest increase of maxillary width was detected at the level of the upper first deciduous molars (+3.7 ± 1.4 mm; P < 0.001), followed by the level of the second deciduous molars (+3.4 ± 1.6 mm; P < 0.001) and by the deciduous canine (+2.6 ± 2.0 mm; P < 0.001). Upper first molars showed a greater expansion in the intermolar mesial width (+3.2 ± 1.2 mm; P < 0.001) than in the intermolar distal (+1.7 ± 1.2 mm; P < 0.001) and transpalatal width (+1.2 ± 1.2 mm; P < 0.01).

CONCLUSIONS

The Invisalign First System® can be considered effective in growing patients who require maxillary arch development. The greatest net increase was detected at the level of upper first deciduous molars, whereas the upper first molars showed a greater expansion in the intermolar mesial width due to a rotation that occurs around its palatal root.

Treatment of severe Class II skeletal malocclusion in a hyperdivergent adult patient via hybrid clear aligner approach: A case report of successful camouflage therapy

This case report describes the camouflage treatment of an adult patient with hyperdivergent facial pattern presenting with severe Class II skeletal malocclusion, through the use of a hybrid clear aligner approach, that relies on both a partial lingual fixed appliance and the continuous use of Class II elastics throughout therapy. After 11 months of treatment, the goals had been achieved, highlighting that the correct diagnostic framework, proper patient selection and careful digital planning of a compromise treatment can provide satisfactory aesthetic and functional outcomes.

Comparison of the Compression and Tensile Modulus of Two Chosen Resins Used in Dentistry for 3D Printing

(1) The CAD/CAM technique exploiting 3D printing is becoming more and more popular in dentistry. The resins are used in all the dental specialties, including conservative dentistry, prosthodontics, surgery, and orthodontics. The interest in investigating the different properties of dental materials has been an aim of researchers. The purpose of the presented study was to compare the properties of two 3D-printable dental resins (both rigid, used for medical purposes). (2) Methods: Ten blocks of two-type shapes were printed on a printer designed for medical use. The tensile modulus and compression were investigated and compared. The axial compression test was performed according to the PN-EN ISO 604:2003 norm, while the tensile test was performed according to the PN-En ISO 527-1-2019 (E) norm. In the first test, the sample size of the perpendicular shape was 10 ± 0.2 mm × 10 ± 0.2 mm × 4 ± 0.2 mm and in the second it was 75 mm, the end width 10 mm, and the thickness 2 mm. (3) Results: The statistical analysis based on ANOVA tests showed that all the obtained results were statistically significant. Both of the examined materials had similar properties and were resistant and stable in shape. The tensile modulus and compression tests performed on them gave similar results. They also showed high durability to compression and tensility. (4) Conclusions: Both of the examined materials were durable and rigid materials. BioMed Amber was more resistant to compression, while Dental LT clear was more resistant in the tensility test. Although both resins had similar physical properties, it is still disputable whether the chosen materials could be used interchangeably.

Orthodontics on autopilot through digital customization and Programmed Non-Sliding Mechanics

Orthodontic tooth movement occurs in six degrees of freedom, which includes opening and closing spaces. Traditionally, opening and closing spaces are achieved with auxiliaries such as power chains or springs because all traditional bracket systems cannot achieve this tooth movement by themselves. The InBrace system has the capability to program tooth movement in all six degrees of freedom, including opening and closing spaces, through digital customization and its use of Programmed Non-Sliding Mechanics.

Dynamics of Social Media Popularity of “Do It Yourself” Orthodontic Aligners: A YouTube Case Study

Objective

To have an understanding of the fact how the popularity of “do it yourself” (DIY) videos available on YouTube correlate with authorship, content, quality, reliability, and how they appeal to and influence the customers.

Materials and Methods

A new YouTube account was created, this was followed by a determination of the most commonly used keywords regarding DIY aligners by using “Google Trends.” The keywords were used to search the YouTube website. A total of 112 videos were assessed for various parameters, such as completeness of the content, reliability using a modified version of the DISCERN tool, and quality using a Global Quality Score (GQS). Out of 112 videos, 26 were rejected based on their relevance, duplication, videos without audio, and video language. Pearson’s correlation coefficient was used to study the relationship between the variables, authorship, popularity, and recommendations.

Results

The majority of the videos were uploaded by the laypeople (43%), followed by DIY aligner companies (38%), and dentists and orthodontists (16%). The content for most of the videos was poor (82%), with DISCERN reliability score of zero (65%), and GQS of 1 and 2 (poor to generally poor quality). The view of uploaded videos, view rate, and likes was in proportion to the quality of the videos, their popularity, and reliability. Further authors with a financial interest and poor quality, content, and less reliability of the videos usually recommended the DIY aligners. The reduced cost was one of the important factors for the customers to consider DIY aligner treatment.

Conclusion

YouTube videos on DIY aligners should not be considered a reliable source for the public in general who are looking for orthodontic treatment for correction of their dentofacial irregularities. The dental professional bodies and orthodontists should use social media platforms (YouTube) to increase awareness about the DIY aligners among the public.

Public perception of Invisalign® clear aligner treatment: A cross-sectional survey-based study

Objectives:

The demand for clear aligner treatment has increased in recent years. Thus, this study investigated public knowledge regarding Invisalign clear aligner treatment.

Material and Methods:

A web-based survey was administered through different social media platforms covering different aspects of Invisalign treatment, namely: Treatment efficiency, patient discomfort, appliance esthetic attractiveness, oral hygiene maintenance, and treatment aesthetic results. Participants were also asked to outline their perception of Invisalign treatment cost. A Likert-type scale was used to rank the participant responses. Data were analyzed with the Chi-square test and Bonferroni correction for multiple comparisons.

Results:

Out of 934 eligible adult participants, 19.6% were aware of Invisalign. Most of the Invisalign-familiar respondents were unaware of its cost (27.9%) but agree it is generally better (49.7%), requires fewer visits (38.2%), results in shorter treatment duration (39.4%) and reduced teeth discomfort (35%), more esthetically attractive (64%), yields easier oral hygiene maintenance (55.2%), and produces superior esthetic results (43.7%) than traditional braces. In addition, males and average-income participants were more likely to believe that Invisalign treatment produces superior esthetic results than traditional braces (P = 0.0002 and P = 0.002, respectively). Average-income participants also believed that Invisalign treatment was generally better (P < 0.0001). While participants in the age-range 55–64 years strongly believe, it is cheaper (P < 0.0001) than traditional braces.

Conclusion:

This study highlighted the lack of public knowledge about Invisalign treatment. The results also indicated the importance of ensuring public access to reliable information backed up by high-quality evidence.

Assessment of orthodontic treatment efficacy of Clarity Aligners using the Peer Assessment Rating index and the American Board of Orthodontics Cast-Radiograph Evaluation

INTRODUCTION

3M Oral Care Solutions (St Paul, Minn) has recently introduced Clarity Aligners into the market. This cohort study evaluated the orthodontic treatment efficacy of this clear aligner system using the Peer Assessment Rating (PAR) index and the American Board of Orthodontics Cast-Radiograph Evaluation (CR-Eval).

METHODS

Pretreatment and posttreatment dental models of 87 subjects who had undergone orthodontic treatment using Clarity Aligners in both arches to align their teeth to a target setup were independently evaluated by 4 examiners using the PAR index and the American Board of Orthodontics CR-Eval. Changes in CR-Eval and PAR scores from pretreatment to posttreatment were calculated, with PAR score reductions also expressed as percentages.

RESULTS

Treatment with Clarity Aligners reduced the CR-Eval scores from 39.05 ± 14.98 to 30.34 ± 8.76, resulting in a statistically significant difference of 8.76 ± 11.45 between pretreatment and posttreatment scores. Similarly, aligner treatment reduced the weighted PAR scores from 13.40 ± 9.26 to 5.80 ± 4.84, resulting in a statistically significant difference of 7.50 ± 7.56 between pretreatment and posttreatment scores. The overall median PAR reduction was 53%, with 94% of the subjects having reduced PAR scores after treatment. Seventy-eight percent of subjects had >30% PAR reduction, 57% had >50% PAR reduction, and 33% had >70% PAR reduction.

CONCLUSIONS

The results suggest that Clarity Aligners may be an effective treatment modality in mild to moderate malocclusions.

Biomechanical Characteristics of Maxillary Molar Distalization Using Different Attachments with Clear Aligners: A 3-Dimensional Finite Element Analysis

This study aimed to compare the biomechanical characteristics of maxillary teeth in molar distalization with different orthodontic attachments. A 3-dimensional finite model of maxillary molar distalization with clear aligners was generated by computed tomography and contained different components. Four models—non-attachment (model A), horizontal rectangular attachment (model B), vertical rectangular attachment (model C), and combined attachment (model D)—were set up. The modalities of molar distalization were simulated using a finite element analysis. The results showed that the minimum displacement (rotation center) of the second molar in models A and B was located at the root furcation. In model C, the minimum displacement was located in the middle third of the palatal root. In model D, the minimum displacement was located at the apical third of the root. The anchorage teeth in all the four groups tended to have mesial tipping movement. Models B and D had more uniform stress distribution of the periodontal ligament than models A and C. Models with attachment had a larger tooth displacement pattern than that without attachment. Collectively, if molar distalization is planned before treatment, the appropriate application of attachments can help achieve the desired tooth movements more efficiently.

Interceptive Treatment with Invisalign® First in Moderate and Severe Cases: A Case Series

The increasing demand for more aesthetic/comfortable orthodontic alternatives fostered the utilization of clear aligners in recent years. However, the efficacy of clear aligners for treating complex malocclusions is often treated with scepticism. This case series aims to evaluate the predictability of the Invisalign® First system in moderate and severe cases requiring interceptive orthodontic treatments in mixed dentition. A total of 23 patients with 102 interceptive orthodontic malocclusion traits were selected for orthodontic treatment with Invisalign® First and were examined over 18 months (Phase 1). Clinical assessments included ClinCheck® predictions, cephalometric measurements, and measuring tools commonly used to quantify tooth movement. Measurements taken at the beginning and end of the treatment were compared. The complexity degree of each case was established based on the set of problems presented by each patient. All treatment objectives were achieved within 18 months, except for two Class II cases, with 69% of them solved with the first set of aligners. Additional aligners were used in the remaining cases. Even though these 23 cases suggest that the Invisalign® First (Phase 1) may be effective in most interceptive problems, controlled randomized clinical trials are required to evaluate movement predictability and how this relates to the problem complexity and additional aligners required.

Stress Relaxation Properties of Five Orthodontic Aligner Materials: A 14-Day In-Vitro Study

We aimed to investigate the stress relaxation properties of five different thermoplastic aligner materials subjected to 14 days of constant deflection. Five different thermoplastic aligner materials were selected, whose elastic properties varied: F22 Evoflex, F22 Aligner, Durasoft, Erkoloc-Pro and Duran. The static properties of these materials—in particular, stiffness, stress–strain curve and yield stress—were measured with a three-point bending test. For all the tests that were performed, a minimum of three samples per material were tested. The yield load, yield strength, deformation and particularly the stiffness of each material were found to be similar in the single-layer samples, while the double-layer samples showed far lower stiffness values and were similar one to another. F22 Evoflex and Erkoloc-Pro maintained the highest percentages of stress, 39.2% and 36.9%, respectively, during the 15-day period. Duran and Durasoft obtained the lowest final stress values, 0.5 MPa and 0.4 MPa, respectively, and the lowest percentage of normalized stress, 4.6% and 3.9%, respectively, during the 15-day period. All the materials that we tested showed a rapidity of stress decay during the first few hours of application, before reaching a plateau phase. The F22 Evoflex material showed the greatest level of final stress, with relatively constant stress release during the entire 15-day period. Further research after in vivo aging is necessary in order to study the real aligners’ behavior during orthodontic treatment.

Effectiveness and Efficacy of Thermoformed and 3D Printed Aligners in Correcting Malocclusion (Spacing) and Its Impact on Periodontal Oral Health and Oral Microbiome: A Double-Blinded Parallel Randomized Controlled Multicenter Clinical Trial

Aligners are the common devices used in orthodontics for the correction of malocclusion. Various materials and techniques are employed to fabricate aligners. One of those includes thermoformed and 3D aligners. These aligners can be worn for several days, and their impact on periodontal health is not known. Therefore, the aim of our protocol is to determine the effectiveness of these aligners in correcting malocclusion and their impact on periodontal health and oral microbiome. A double-blinded randomized controlled clinical trial with a total of n = 60 patients will be included with n = 30 in each group (Test: 3D printed aligners and Control: Thermoformed). The evaluation of oral health indices such as basic periodontal examination (BPE), periodontal screening and recording (PSR) that provide the status of periodontal health will be recorded. The oral microbiome assessment will be conducted with polymerase chain reaction (PCR). The primary endpoint will be the correction of malocclusion, and the secondary end point will be the status of periodontal health and oral microbiome. The duration of follow-up for each group will be 7 days for periodontal health and oral microbiome and 6 months for the space closure of 5 mm by 3D and thermoformed aligners.

Association between initial complexity, frequency of refinements, treatment duration, and outcome in Invisalign orthodontic treatment

INTRODUCTION

This study explored possible associations between treatment duration, initial complexity, outcomes in Invisalign therapy, and the number of refinements.

METHODS

Three-dimensional models (initial, final, and refinements) of 355 Invisalign patients (114 males and 241 females; 33.8 ± 17.1 years) were analyzed using the Peer Assessment Rating (PAR) index questionnaire tool in the Ortho Analyzer software (version 2.0; 3Shape, Copenhagen, Denmark) to calculate the weighted total and individual PAR index scores for each component of the PAR index. Data related to demographics, treatment duration, and the number of refinements were collected.

RESULTS

Treatment duration increased as the number of refinements increased. Percent of improvement was higher in PAR ≥22 group than PAR <22 with an increase in the number of refinements: 83.3% vs 73.8% for 2 refinements; 94.7% vs 91.2% for 3 refinements; and 100% vs 85.7% for ≥4 refinements. Those who achieved great improvement or improvement and those who did not were significantly different in treatment duration (P <0.001 and P = 0.027), number of refinements (≥3 refinements; P <0.001), initial occlusal severity (PAR ≥22; P <0.01 and P = 0.031). Most subjects achieved improvement after the first refinement (64.5% for PAR <22 and 78.5% for PAR ≥22). Few had ≥4 refinements, and if they did, none achieved improvement with additional refinements.

CONCLUSIONS

Initial complexity for an Invisalign case is associated with treatment duration, achieved outcomes, and the number of refinements. Treatment duration increased with an increased number of refinements. Great improvement or improvement for the first time dropped to 0 if additional refinements were carried out after 3. Therefore, performing additional refinements does not necessarily mean better occlusal outcomes.

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.

Accuracy of 3D Tooth Movements in the Fabrication of Manual Setup Models for Aligner Therapy

Background: The clinical outcome of aligner therapy is closely related to the precision of its setup, which can be manually or digitally fabricated. The aim of the study is to investigate the suitability of manual setups made for aligner therapy in terms of the precision of tooth movements. Methods: Six dental technicians were instructed to adjust each of eleven duplicate plaster casts of a patient models as follows: a 1 mm pure vestibular translation of tooth 11 and a 15° pure mesial rotation of tooth 23. The processed setup models were 3D scanned and matched with the reference model. The one-sample Wilcoxon signed-rank test (p < 0.05) was used for evaluation. Results: The overall precision of the translational movement covers a wide range of values from 0.25 to 2.26 mm (median: 1.09 mm). The target value for the rotation of tooth 23 was achieved with a median rotation of 9.76° in the apical-occlusal direction. Unwanted movements in the other planes also accompanied the rotation. Conclusions: A manual setup can only be fabricated with limited precision. Besides the very high variability between technicians, additional unwanted movements in other spatial planes occurred. Manually fabricated setups should not be favored for aligner therapy due to limited precision.

Orthodontic Management of Skeletal Class II Malocclusion with the Invisalign Mandibular Advancement Feature Appliance: A Case Report and Review of the Literature

The treatment of Class II malocclusion due to mandibular retrognathia is one of the most common challenges met in orthodontic practice. When it comes to a growing patient, functional appliances are the optimal way to achieve growth modification by enhancing mandibular growth. Clear aligners have been part of the orthodontic treatment for several decades but until recently they were only used to correct mild malocclusions. In 2017, Align Technology introduced the Invisalign with Mandibular Advancement Feature (IMAF) which replicates the action of functional appliances. As this device is new to clinical practice, there is limited literature on its clinical efficiency. This case report describes the orthodontic management of a 12-year-old male patient having skeletal Class II malocclusion due to mandibular retrognathia. As the patient was experiencing active growth, the IMAF appliance was chosen for his treatment. The IMAF appliance appears to be successful in the treatment of Class II malocclusion with mandibular retrognathism in a growing patient. As with all functional appliances, the correction of the malocclusion is a result of both skeletal and dental effects and the IMAF presents the advantage of producing less proclination of the lower incisors compared to other functional appliances.

Accuracy evaluation of orthodontic movements with aligners: a prospective observational study

BACKGROUND

Since their introduction in orthodontics, clear aligners have been appreciated by patients, including adults, for their comfort and low aesthetic impact. Despite the enormous mobilization of financial resources all over the world aimed at producing new product lines, few clinical studies or high-quality evidence have been produced regarding the real effectiveness of such treatment. Given the few limited kinds of research on the subject, this study aims to produce and critically evaluate other data, to establish the concrete reliability of clear aligners in orthodontic therapy.

RESULTS

Significant sample sizes were obtained for intrusion, vestibulo/lingual (V/L) crown tipping, and rotation. The overall accuracy for rotation resulted in 86%, ranging from 96% for maxillary central incisors to 70.4% for mandibular first premolars. The intrusion was registered only for anterior teeth; mean predictability was 92%, with the worst result being 86.7% for mandibular canines and the best being 98% for mandibular central incisors. V/L tipping was the most accurate movement: 93.1% of the prescribed movement was completed. Maxillary central incisors showed the lowest accuracy (80.7%), while mandibular central incisors were the highest (97.5%).

CONCLUSIONS

The present study provided reassuring data in support of the accuracy of the Invisalign® system. Vestibulo/lingual tipping was the most predictable movement, while rotation of canines, premolars, and lateral incisors were the least predictable. Intrusion resulted highly predictable up to 2 mm. When careful treatment planning follows a correct diagnosis, together with the use of auxiliary features and refinements, the planned results can be achieved in a clinically successful way. Authors believe that there is a major need for greater samples to overcome bias related to variables if we want to answer the unsolved questions, such as the predictability of severe malocclusions treatment.

Evaluation of Tooth Movement Accuracy with Aligners: A Prospective Study

Background. Clear aligners treatment (CAT) is a common solution in orthodontics to treat both simple and complex malocclusions. This study aimed to evaluate the predictability of CAT, comparing the virtually planned and the achieved tooth movement at the end of stage 15, which is often the time of first refinement. Methods. Seventeen patients (mean age: 28.3 years) were enrolled in the study. Torque, tip and rotation were analyzed in 238 maxillary teeth on digital models at Pre-treatment (T0), at the end of stage 15 (T15) and at virtually planned stage 15 (T15i). Prescription, Achieved movement and performance values were calculated to compare the virtually planned and the clinical tooth position. Data were analyzed by means of Student’s t test with a level of significance set at p < 0.05. Results. The largest iper-performance was the torque correction of the second molars (+2.3° ± 3.1°), the greatest under-performance was the tip correction of the first molars (−2.3° ± 3.3°), while rotation corrections of all the teeth showed more accurate performance. No significant differences were found between mean Prescription and mean Achieved movement for all the assessed movements (p < 0.05). Conclusions. An accurate evaluation of CAT after the 15th aligner is fundamental in order to individuate the movements that are not matching the digital set-up.

Cleaning and Disinfection Protocols for Clear Orthodontic Aligners: A Systematic Review

(1) Background: Clear orthodontic aligners support the development of oral biofilms, which could lead to interferences with the oral microbiota already existing and the deterioration of oral health, with the development of dental caries, periodontal disease and even systemic infections. Therefore, preventive oral health care requires a cleaning and disinfection procedure for aligners. (2) Methods: A systematic review of the literature was conducted across four databases following the PRISMA guidelines up to May 2021, combining an electronic and a manual search. Prospective studies, including randomized controlled trials (RCTs), crossover studies (COSs) and controlled clinical trials (CCTs), published in the English language without time restrictions, evaluating the efficacy of cleaning and disinfection protocols for clear orthodontic aligners by comparing them with a placebo or a negative control, were included. The article selection, data extraction and risk of bias assessment were performed by two independent blinded review authors. In case of disagreement, a third author was solicited throughout the selection process. (3) Results: Among the 221 articles screened in the search process, 4 studies were included in the review, all designed as crossover studies (single arm without randomization with the same sequence of different cleaning and disinfection protocols for each participant). Different cleaning and disinfection methods were studied such as mechanical methods (brushing with toothpaste or vibration), chemical methods/pharmaceutical products (chlorhexidine antibacterial substance, anionic or cationic detergents or effervescent tablets) or combinations of both. (4) Conclusion: Although the determination of the most remarkable method of cleaning and disinfection was impossible because no direct comparison was conducted between all these methods, a multi-step protocol, including the combination of a mechanical and a chemical method, seems to be the most effective approach. Further research is needed to define the most preventive oral health care protocol. Registration: PROSPERO CRD 42021278498.

Efficacy of clear aligners in producing molar distalization: Systematic review

Objectives:

The aim of this review is to systematically analyze the efficacy of molar distalization using clear aligners in non-growing Class II patients.

Materials and Methods:

A complete search across the electronic database through PubMed, Cochrane, Google scholar, LILACS, and manual search of orthodontic journals were done till 2019. Studies were selected on the basis of PRISMA guidelines.

Results:

A total of four articles were included in this review. The amount of molar distalization reported was 2–3 mm.

Conclusion:

Out of the four studies included. In all the studies a significant amount of distalization was reported. Three retrospective studies concluded that distalization with aligners is the most effective of all tooth movements. One study concluded that aligners effectively achieved distalization with an efficacy of 87%, other two studies concluded that aligners effectively distalized the molars with good control over vertical dimension and mesiodistal tipping.

Clinical effectiveness of clear aligner treatment compared to fixed appliance treatment: an overview of systematic reviews

OBJECTIVE

To evaluate the available evidence regarding clinical effectiveness of clear aligner treatment (CAT).

MATERIALS AND METHODS

A comprehensive literature search was conducted for systematic reviews investigating effectiveness of CAT published up to July 15, 2021. This was accomplished using different electronic databases. No language restriction was applied. Screening, quality assessment, and data extraction were performed by two authors independently. Information was categorized and narratively synthesized for the key findings from moderate and high-quality reviews.

RESULTS

A total of 361 potentially eligible reviews were identified. After excluding the non-relevant/low-quality reviews, 18 systematic reviews were included. CAT was found to be effective for mild to moderate malocclusions, and was associated with inferior outcomes when treating severe cases or with achieving specific tooth movements. There were conflicting results regarding treatment duration; however, CAT may be associated with shorter treatment in mild to moderate cases. Relapse was greater with CAT, while periodontal health was better. The risk of root resorption tended to be lower with CAT. Regarding pain, the results were unclear, although CAT was found to be more comfortable and associated with a reduced impact on eating and chewing.

CONCLUSIONS

The level of evidence regarding CAT is moderate; hence, further high-quality randomized clinical trials are required. Evidence supports use of aligners as an alternate to fixed appliances in patients with mild-to-moderate malocclusion but not in severe cases. Advancement in technology could enhance the accuracy of CAT in delivering planned outcomes.

CLINICAL RELEVANCE

CAT can be used effectively for selected cases with mild to moderate malocclusion.

REGISTRATION

PROSPERO registration number: CRD42021246855.

Clear Aligners in Patients with Amelogenesis and Dentinogenesis Imperfecta

Dentinogenesis imperfecta (DI) and amelogenesis imperfecta (AI) are hereditary abnormalities of dental hard tissues. Dental abnormalities may also be accompanied by symptoms of disorders such as osteogenesis imperfecta. AI and DI have a significant burden on socializing, function, and comfort; therefore, frequent screening and accurate diagnosis is the cornerstone of managing such conditions. Both AI and DI could be treated with many strategies, including restorative, prosthetic, periodontal, surgical, and orthodontics treatment. The interdisciplinary combination of orthodontic, prosthodontic, and periodontic treatment has been proven to improve the prognosis of AI and DI. Regarding orthodontic treatment, the most difficult element of orthodontic therapy may be maintaining a high level of motivation for what might be a prolonged form of treatment spanning several years. There are many forms of orthodontic management for AI and DI, including removable appliances, functional appliances, and fixed appliances. Clear aligner therapy (CAT) contains a broad range of equipment that works in different ways, has different construction processes, and is compatible with different malocclusion procedures. The application of CAT in patients with AI and DI is favorable over the fixed applicants. However, the available evidence regarding the application of CAT in AI is weak and heterogeneous. In this review, we discussed the current evidence regarding the application of clear CAT in patients with AI and DI.

The Biological Effects of 3D Resins Used in Orthodontics: A Systematic Review

Three-dimensional (3D) resin medical-dental devices have been increasingly used in recent years after the emergence of digital technologies. In Orthodontics, therapies with aligners have gained popularity, mainly due to the aggressive promotion policies developed by the industry. However, their systemic effects are largely unknown, with few studies evaluating the systemic toxicity of these materials. The release of bisphenol A and other residual monomers have cytotoxic, genotoxic, and estrogenic effects. This systematic review aims to analyze the release of toxic substances from 3D resins used in Orthodontics and their toxic systemic effects systematically. The PICO question asked was, "Does the use of 3D resins in orthodontic devices induce cytotoxic effects or changes in estrogen levels?". The search was carried out in several databases and according to PRISMA guidelines. In vitro, in vivo, and clinical studies were included. The in vitro studies' risk of bias was assessed using the guidelines for the reporting of pre-clinical studies on dental materials by Faggion Jr. For the in vivo studies, the SYRCLE risk of bias tool was used, and for the clinical studies, the Cochrane tool. A total of 400 articles retrieved from the databases were initially scrutinized. Fourteen articles were included for qualitative analysis. The risk of bias was considered medium to high. Cytotoxic effects or estrogen levels cannot be confirmed based on the limited preliminary evidence given by in vitro studies. Evidence of the release of bisphenol A and other monomers from 3D resin devices, either in vitro or clinical studies, remains ambiguous. The few robust results in the current literature demonstrate the absolute need for further studies, especially given the possible implications for the young patient's fertility, which constitutes one of the largest groups of patients using these orthodontic devices.

Does Clear Aligner Treatment Result in Different Patient Perceptions of Treatment Process and Outcomes Compared to Conventional/Traditional Fixed Appliance Treatment: A Literature Review

This study sought to systematically review the literature to determine whether clear aligner treatment results in different patient perceptions of treatment process and outcomes compared with conventional fixed appliance treatment. A systematic review was conducted to identify studies that examined differences in patient perceptions between clear aligners and conventional fixed appliance treatment. Studies were identified through searching relevant terms using PubMed and Embase. Following review of identified articles, key information about the studies including study design, setting, comparison groups, sample size/response rate, study location, primary outcomes, and statistical tests used were extracted. A total of 13 articles were identified that met the inclusion criteria for this study. These studies described a variety of outcomes which were divided into two broad categories: treatment process (pain, chewing, speech, daily routine, etc.) and treatment outcomes (satisfaction level, smile outcome perceptions, etc.). There was the strongest evidence that clear aligners had a positive impact with respect to treatment process compared with fixed orthodontic appliances. This study highlights that clear aligners may be effective for improving treatment-process-related outcomes among orthodontic patients. More studies need to be conducted to determine whether clear aligners have a beneficial impact with respect to treatment outcomes.

Maxillary arch development with Invisalign system

OBJECTIVES

To evaluate tooth movements during maxillary arch expansion with clear aligner treatment.

MATERIALS AND METHODS

The study group included 28 subjects (16 females, 12 males, mean age 31.9 ± 5.4 years) collected prospectively from January 2018 to May 2019. Inclusion criteria were European ancestry, posterior transverse discrepancy of 3-6 mm, permanent dentition stage, presence of second permanent molars, mild or moderate crowding, and good compliance with aligners. Treatment protocol included nonextraction strategies, application of Invisalign clear aligner system, and no auxiliaries other than Invisalign attachments. Linear and angular measurements were performed before treatment (T1), at the end of treatment (T2), and on final virtual models (T2 ClinCheck). A paired t-test was used to compare T2-T1 and T2-T2 ClinCheck changes. The level of significance was set at 5%.

RESULTS

Statistically significant differences were found for all measurements, except for ones at the upper second molars. The greatest increase in maxillary width was detected at the upper first and second premolars: +3.5 mm for the first premolar and +3.8 mm for the second premolar at T2. Comparison of T2-T1 angular outcomes showed statistically significant changes in the inclinations of all teeth except for the second permanent molars. T2-T2 ClinCheck showed significant differences for both linear and angular measurements for maxillary canines, resulting in poor predictability.

CONCLUSIONS

Maxillary arch development revealed a progressive reduction of the expansion rate and buccal tipping in the anterior, lateral, and posterior regions, with the greatest net increase at the first and second premolars. Clinical attention should be paid to maxillary canine movements, and overcorrection should be planned for them during dentoalveolar expansion.

The Implications of the COVID-19 Pandemic on the Interest in Orthodontic Treatment and Perspectives for the Future. Real-Time Surveillance Using Google Trends

Background: The COVID-19 pandemic outbreak may have a large impact on orthodontic treatment. Regular orthodontic visits were strongly and widely interrupted by the unprecedented epidemiological threat. Methods: The data regarding orthodontic queries were investigated in a real-time surveillance using Google Trends. Search terms “braces”, “invisalign”, “get braces”, “get braces off”, “braces pain” and the phrase “social distancing” were analyzed regarding the year preceding the pandemic outbreak and the time of the pandemic. Moreover, the five-year trend for queries “braces” vs. “invisalign”, as an example of different types of orthodontic appliances, was compared. Results: There was a significant decrease in orthodontics phrase queries in the spring of 2020, connected with the worldwide restrictions and lockdowns announced all over the world. There was a lower interest in the “braces pain” query during the first lockdown in 2020. The number of searches for “invisalign” increased steadily over time, while the number of searches for “braces” was relatively stable across the investigated time period. Conclusions: The course of the COVID-19 pandemic has had a large impact on the orthodontic-related search queries. Orthodontists must be better-prepared for any sudden changes in the possible future in the epidemiological situation that may change accessibility to dental offices.

Treatment of mild Class II malocclusion in growing patients with clear aligners versus fixed multibracket therapy: A retrospective study

Objective

To compare the dental and skeletal effects of intermaxillary elastics on the correction of mild Angle's Class II division 1 malocclusion with clear aligner treatment (CA) versus fixed multibracket (FMB) in growing patients.

Settings and sample population

The study sample consisted of 49 consecutively patients (mean age ± SD 12.9 ± 1.7 years), 32 females and 17 males referred from the School of Orthodontics of the University of Bratislava Comenius (Slovakia). All patients were treated with a non‐extraction orthodontic treatment, 25 with FMB and 24 with CA.

Methods

The cephalometric analysis was performed at the beginning (T0) and the end of the treatment (T1). The t test for unpaired data was carried out to compare cephalometric values at T0 and changes at T1‐T0 between the two groups. The level of significance was set as P < .0035.

Results

The two groups showed no statistically significant differences (ANPg = −0.1°; P = .762) in the correction of the sagittal intermaxillary relation. The analysis of vertical skeletal changes showed no statistically significant effects on mandibular inclination (SN/MP = 0.1°; P = .840). The two treatments had a statistically significant and clinically relevant difference in controlling the inclination of the lower incisors (L1/GoGn = 4.8°, CAG = −0.5°± 3.9°; FMB = 4.3°± 5.8°; P < .001).

Conclusions

Class II elastics combined with CA and FMB produce a similar correction on sagittal discrepancies in growing patients. CA presented a better control in the proclination of the lower incisors. CA and elastics might be a good alternative in the correction of mild Class II malocclusion in cases where a proclination of lower incisors is unwanted.