Differences in finished case quality between Invisalign and traditional fixed appliances

Clear aligner therapy practice among orthodontists in the United Kingdom and the Republic of Ireland: A cross-sectional survey of the British Orthodontic Society membership

OBJECTIVE

To investigate clear aligner therapy (CAT) practice among orthodontists in the British Orthodontic Society (BOS).

DESIGN

A cross-sectional online survey.

METHODS

An electronic survey was distributed to members of the BOS in 2022. The survey comprised questions regarding respondent demographics, general use of CAT, the choice of proprietary CAT appliances, CAT planning, case selection, treatment protocols and orthodontist-reported CAT problems.

RESULTS

Overall, there were 233 (19.5%) respondants with the majority (n = 121, 53.1%) being female. Most respondents reported practising in England (n = 171, 74.7%). The majority (n = 177, 77.3%) indicated that they used CAT in their practice, with 48.1% (n = 81) treating 1-20 patients with CAT annually. The most frequently prescribed CAT system was Invisalign (n = 138, 81.2%). One to three changes to the initial digital treatment plan were made by 72.9% (n = 121) with final tooth positions being the most common reason for adjustment (64.4%). Most (n = 97, 60.3%) rarely or never performed premolar extractions with CAT. Of the respondents, 23 12.7%) reported that they always or mostly used a remote monitoring system in conjunction with CAT, with a wide range of aligner change protocols reported. The median number of months required to complete non-extraction CAT reported by the respondents was 12. Most respondents (n = 77, 51.7%) did not feel that CAT provides superior outcomes compared with fixed appliance therapy.

CONCLUSION

CAT practice varied widely among the surveyed orthodontists. A predilection for the use of Invisalign and utility in less severe cases was noted.

Effect of post-printing curing time on cytotoxicity of direct printed aligners: A pilot study

INTRODUCTION

The aim of this in vitro study was to examine the potential impact of different curing times of 3D-printed orthodontic aligners on their cytotoxicity.

METHOD

Some 60 samples of aligner material were directly 3D printed using Tera Harz TC-85 DAC resin and randomly allocated to three different curing time groups (14, 24 and 50 min). Zendura FLX samples were used as control. The samples were incubated in saliva for 14 days, and then the supernatant was collected. Human gingival fibroblasts (HGF-1)-CRL2014 were used to evaluate potential cytotoxicity. Furthermore, HGF-1 cells were plated on the samples as well as on a glass control sample. After 72 h of growth, their viability was tested.

RESULTS

Compared with the glass, only the 50-min curing time markedly reduced fibroblast cell growth. Additionally, a negative linear trend was observed between curing time and fibroblast growth. In comparison with the aligner control group, all samples, including the aligner control samples, exhibited a significant reduction in the viability of human fibroblasts when exposed to saliva.

CONCLUSIONS

3D directly printed aligners showed a cytotoxic effect similar to that of thermoformed conventional aligners in terms of fibroblasts growth. A linear trend was found between curing time and cells growth, indicating that directly printed aligners could exhibit higher cytotoxicity if exposed to a longer curing time. This dependence on curing time underscores the importance of following a strict manufacturing process.

Efficacy of clear aligner therapy over conventional fixed appliances in controlling orthodontic movement: A systematic review

OBJECTIVE

The purpose of the current systematic review was to answer the clinical research question "Is Clear Aligner Therapy (CAT) effective in controlling the orthodontic movement?" by bringing together the most up-to-date information about the available evidence for CAT.

METHODOLOGY

On January 1, 2023, a search was conducted in PubMed, ERIC, Embase, and CINHAL for any research papers published in the previous 10 years that provided an overview of the PICO questions. Both the titles and abstracts of the selected studies were evaluated independently by two different authors, and if there was any disagreement between the two review authors, a third reviewer was brought in to settle it.

RESULTS

Among included studies, three were retrospective non-randomized and two studies were prospective randomized clinical trials. Various authors reported better outcome for fixed orthodontic appliances than for clear aligner treatment (CAT) in relation to mandibular incisor proclination. The mean objective grading system score was better for braces (17) than for CAT (12) with no clinically significant difference, while staging had a significant impact on treatment efficacy.

CONCLUSION

The results of this study suggest that clear aligners may be an effective alternative to traditional braces, but more research is needed to confirm these findings and determine the optimal size of future prospective studies evaluating this treatment.

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

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

Duration of orthodontic treatment with clear aligners versus fixed appliances in crowding cases: a systematic review

OBJECTIVE

To critically appraise and assess the currently observed evidence about the difference in orthodontic treatment duration between clear aligners and fixed appliances in crowding cases.

MATERIALS AND METHODS

An electronic search without limitations was conducted from inception to June 2023 covering nine databases: The Cochrane Central Register of Controlled Trials (CENTRAL), PubMed, Scopus, Web of Science, Google Scholar, Trip, CINAHL via EBSCO, EMBASE via OVID and ProQuest. Randomized controlled trials (RCTs) and matched non-randomized studies were included in this systematic review. Risk of Bias was assessed via Cochrane's tool (RoB 2) for RCTs and ROBINS-I tool for non-randomized studies. The Grading of Recommendations Assessment, Development, and Evaluation (GRADE) framework was employed to evaluate the overall quality of evidence.

RESULTS

Out of the 3537 articles initially identified, ten eligible studies were included in this systematic review; six were RCTs. Only one study offered extraction-based treatment, while the other nine adopted non-extraction treatments. According to the GRADE, there is low evidence that treatment duration in mild to moderate crowding cases with clear aligners is similar to that in fixed orthodontic appliances. Meta-analysis was not administered due to high inconsistency.

CONCLUSIONS

Based on currently available information, there was no significant difference in the treatment duration between the CA and FA groups in mild to moderate crowding cases. Further well-performed RCTs, especially in severe cases, are required.

CLINICAL RELEVANCE

Time efficiency is an essential outcome measure for clinical orthodontic practice. While the type of appliance used is a critical determinant of treatment duration, orthodontists should be aware of other factors that can significantly impact treatment time, such as patient and treatment-related factors.

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

OBJECTIVE

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

MATERIALS AND METHODS

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

RESULTS

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

CONCLUSION

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

Predicted and achieved overjet and overbite measurements with the Invisalign appliance: a retrospective study

OBJECTIVES

To determine whether achieved outcome regarding overjet and overbite matched the predicted outcome following treatment with Invisalign (Align Technology, San Jose, Calif) aligner appliances.

MATERIALS AND METHODS

Data including pretreatment, predicted and achieved overjet, and overbite measurements provided by Align's digital treatment facility, ClinCheck Pro, were evaluated. Descriptive statistics, Mann-Whitney U-test, and Wilcoxon rank-sum intraclass correlation (ICC) test results were calculated.

RESULTS

From an initial sample of 600, 355 adult patients satisfied the inclusion and exclusion criteria. ICC scores for data input were excellent. Median (interquartile range [IQR]) age was 30.14 (23.33, 39.92) years and most (n = 259; 72.95%) were women. Almost one-third (n = 101; 28.45%) had undergone extraction as part of their treatment. More aligners were prescribed in the initial digital treatment plan for patients (median, 44; IQR: 35, 51.5; minimum, 17; maximum, 92) undergoing extractions as part of their orthodontic treatment than those who were not (median, 24; IQR: 18.25, 32; minimum, 13; maximum, 85) (P < .0001). Planned changes in overjet differed significantly from achieved outcomes (P < .001). Planned increases in overbite resulted in up to more than twice (222.72%) as much increase than predicted. Planned reduction of overbite achieved 8.69% of its predicted reduction in extraction cases.

CONCLUSIONS

Achieved overjet and overbite measurements differed significantly from the predicted outcomes at the end of an initial sequence of aligners. Planned increases in overbite resulted in greater overbite correction than predicted, particularly in extraction cases. Planned overbite reduction was challenging, especially in patients with extractions.

The displacement of teeth and stress distribution on periodontal ligament under different upper incisors proclination with clear aligner in cases of extraction: a finite element study

OBJECTIVES

To investigate the displacement of dentition and stress distribution on periodontal ligament (PDL) during retraction and intrusion of anterior teeth under different proclination of incisors using clear aligner (CA) in cases involving extraction of the first premolars.

METHODS

Models were constructed, consisting of the maxilla, PDLs, CA and maxillary dentition without first premolars. These models were then imported to finite element analysis (FEA) software. The incisor proclination determined the division of the models into three groups: Small torque (ST) with U1-SN = 100°, Middle torque (MT) with U1-SN = 110°, and High torque (HT) with U1-SN = 120°. Following space closure, a 200 g intrusion force was applied at angles of 60°, 70°, 80°, and 90° to the occlusal plane, respectively.

RESULTS

CA therapy caused lingual tipping and extrusion of incisors, mesial tipping and intrusion of canines, and mesial tipping of posterior teeth in each group. As the proclination of incisors increased, the incisors presented more extrusion and minor retraction, and the teeth from the canine to the second molar displayed an increased tendency of intrusion. The peak Von Mises equivalent stress (VMES) value successively decreased from the central incisor to the canine and from the second premolar to the second molar, and the VMES of the second molar was the lowest among the three groups. When the angle between the intrusion force and occlusal plane got larger, the incisors exhibited greater intrusion but minor retraction.

CONCLUSIONS

The "roller coaster effect" usually occurred in cases involving premolar extraction with CA, especially in patients with protruded incisors. The force closer to the vertical direction were more effective in achieving incisor intrusion. The stress on PDLs mainly concentrated on the cervix and apex of incisors during the retraction process, indicating a possibility of root resorption.

Effect of clear aligner attachment design on extrusion of maxillary lateral incisors: A multicenter, single-blind randomized clinical trial

INTRODUCTION

Extrusion of maxillary lateral incisors during aligner treatment is a difficult movement to achieve accurately. Despite recommendations regarding attachment design, few studies and no prospective trials compare predictability among attachments. This study aimed to compare the efficacy between optimized and horizontal attachment designs for achieving maxillary lateral incisor extrusion during clear aligner treatment.

METHODS

The study included maxillary lateral incisors in 3 orthodontic practices requiring at least 0.3 mm of extrusion during the first series of 20-25 aligners in patients aged ≥16 years who were scheduled to begin clear aligner treatment (Invisalign; Align Technology, San Jose, Calif). Teeth were randomly assigned to receive optimized (O), rectangular horizontal nonbeveled (H), rectangular horizontal incisally-beveled (HIB), or rectangular horizontal gingivally-beveled (HGB) attachments. After the first series, a blinded evaluator measured extrusion using superimpositions with initial and predicted models. Linear models determined the difference in the predicted extrusion percentage achieved on the basis of attachment design. Other covariates were patient age, sex, number of trays, and self-reported compliance.

RESULTS

Forty patients (74 teeth) were enrolled, and 38 patients (71 teeth) completed the study. Intraexaminer and interexaminer reliability for extrusion measurements was high (intraclass correlation coefficient, 0.985 and 0.991, respectively). The achieved extrusion was significantly less than predicted (mean, 73%; P <0.0001). The average achieved extrusion was 62%, 79%, 78%, and 78% for O, H, HIB, and HGB attachments, respectively, with H significantly more effective than O (P = 0.0403). Horizontal attachments (H, HIB, and HGB combined) were significantly more effective than O attachments (P = 0.0060), with an average difference in achieved extrusion of 14% of the predicted amount (95% confidence interval, 4-23; estimated 76% vs 62%). Horizontal attachments were an estimated 22% more effective than O attachments for extruding maxillary lateral incisors.

CONCLUSIONS

Horizontal attachments are more effective than O attachments for predicted maxillary lateral incisor extrusion between 0.3 and 2.5 mm. The 3 horizontal attachment designs evaluated performed similarly for achieving predicted extrusion.

TRIAL REGISTRATION

This randomized clinical trial was registered and reported at clinicaltrials.gov (NCT04968353).

PROTOCOL

The protocol was not published before trial commencement.

FUNDING

This study was funded in part by the Alexander Fellowship of the Virginia Commonwealth University School of Dentistry, the Southern Association of Orthodontists, and the Virginia Orthodontic Education and Research Foundation. No funding source influenced the study design, the collection, analysis or interpretation of data, writing of the report, or the decision to submit the article for publication.

The Position of the Virtual Hinge Axis in Relation to the Maxilla in Digital Orthognathic Surgery Planning-A k-Means Cluster Analysis

The aim of this study was to investigate a possible relation between skeletal phenotypes and virtual mounting data in orthognathic surgery patients. A retrospective cohort study including 323 female (26.1 ± 8.7 years) and 191 male (27.9 ± 8.3 years) orthognathic surgery patients was conducted. A k-means cluster analysis was performed on the mounting parameters: the angle α between the upper occlusal plane (uOP) and the axis orbital plane (AOP); the perpendicular distance (AxV) from the uOP to the hinge axis; and the horizontal length (AxH) of the uOP from upper incisor edge to AxV, with subsequent statistical analysis of related cepalometric values. Three clusters of mounting data were identified, representing three skeletal phenotypes: (1) balanced face with marginal skeletal class II or III and α=8∘, AxV = 36 mm and AxH = 99 mm; (2) vertical face with skeletal class II and α=11∘, AxV = 27 mm and AxH = 88 mm; (3) horizontal face with class III and α=2∘, AxV = 36 mm and AxH = 86 mm. The obtained data on the position of the hinge axis can be applied to any digital planning in orthognathic surgery using CBCT or a virtual articulator, provided that the case can be clearly assigned to one of the calculated clusters.

[Comparison of the outcome of orthodontic dental movement using aligners versus fixed orthodontics: a review]

Introduction

The aligners have become a preferred alternative in terms of orthodontic treatment, surpassing the choice of conventional brackets, due to the comfort and aesthetics that the aligners represent, however, the final result with this system continues to be a controversial issue. The objective of this review was to verify the effectiveness of the treatment completed with aligners versus conventional brackets.

Materials and methods

An exhaustive search was carried out in the PubMed, ScienceDirect, Scopus and Embase databases up to the date of January 5, 2023, including comparative studies that evaluated the final result and treatment time of the aligners compared to conventional braces. Two researchers carefully selected the articles evaluated and analyzed different key topics on the subject.

Results

In this study, 8 articles were included, according to the studies, the vast majority did not find significant differences in completion between the compared groups. In addition to this, the treatment time in 3 articles was faster with aligners, in 3 articles it was faster with conventional brackets, and in one article no significant difference was found, so it is not yet established whether a system is faster than the other.

Conclusions

Both aligners and conventional fixed orthodontics had good results at the end of orthodontic treatment and presented a similar treatment time, however, the majority of treated cases belonged to malocclusions of medium to low complexity, so these cannot be generalized. findings to all malocclusions.

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.

Comparison between clear aligners and 2 × 4 mechanics in the mixed dentition: a randomized clinical trial

OBJECTIVES

To compare the efficacy and efficiency between clear aligners and 2 × 4 fixed appliances for correcting maxillary incisor position irregularities in the mixed dentition.

MATERIALS AND METHODS

The sample comprised 32 patients from 7 to 11 years of age randomly allocated into two parallel treatment groups: the clear aligners group, 14 patients (6 girls, 8 boys) with a mean initial age of 9.33 years (standard deviation [SD] = 1.01) treated with clear aligners; and the fixed appliances group, 13 patients (9 girls, 4 boys) with a mean initial age of 9.65 years (SD = 0.80) treated with partial (2 × 4) fixed appliances. Digital models were acquired before treatment and after appliance removal. Primary outcomes were incisor irregularity index and treatment time. Secondary outcomes were arch width, perimeter, length, size and shape, incisor leveling, incisor mesiodistal angulation, plaque index, and white spot lesion formation (International Caries Detection and Assessment System index). Intergroup comparisons were evaluated using t-tests or Mann-Whitney U-tests with Holm-Bonferroni correction (P < .05).

RESULTS

Treatment time was approximately 8 months in both groups. No intergroup differences were observed for changes in any of the variables. Similar posttreatment arch shapes were observed in both groups.

CONCLUSIONS

Clear aligners and 2 × 4 mechanics displayed similar efficacy and efficiency for maxillary incisor position corrections in the mixed dentition. The choice of appliance should be guided by clinician and family preference.

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

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

Perception of Need for Further Refinement in a Clear Aligner Treatment among Orthodontists, Dentists and Laypeople: A Retrospective Study

Clear aligner treatment often requires further refinement to improve the orthodontic treatment outcome. However, the perceptions of treatment outcomes evaluated by orthodontists and dentists are sparse, and laypeople's perceptions have yet to be explored. Here, we explore the perceptions of orthodontists, dentists, and laypeople concerning the treatment outcomes achieved after completing the first sequence of aligners. This cross-sectional study involved 37 orthodontists, 67 dentists, and 93 laypeople. We administered an online questionnaire containing intra-oral photographs of nine completed cases with pre- and post-first sequences of aligners. As a control, we used a digital prediction system for the treatment outcome. Self-perception was reported using a visual analog scale. Both orthodontists and dentists had similar perceptions about treatment outcomes (p = 0.363) but significantly differed from laypeople (p ≤ 0.0001). Both orthodontists and dentists recommended further treatment; orthodontists were more critical than dentists (p ≤ 0.001). Orthodontists were more critical than dentists in their evaluations of the need for further treatments; however, their perceptions of treatment outcomes were similar. Laypeople were more satisfied with the treatment outcomes, were less concerned with occlusion, and were more focused on the aesthetic results of the treatment.

Assessment of malalignment factors related to the Invisalign treatment time aided by automated imaging processes

OBJECTIVES

To identify predictors regarding the type and severity of malocclusion that affect total Invisalign treatment duration based on an intraoral digital scan.

MATERIALS AND METHODS

The subjects of this retrospective clinical cohort were 116 patients treated with Invisalign. A deep learning method was used for automated tooth segmentation and landmark identification of the initial and final digital models. The changes in the six degrees of freedom (DOF), representing types of malalignment, were measured. Linear regression was performed to find the contributing factors associated with treatment time. In addition, the Peer Assessment Rating (PAR) score and a composite score combining 6 DOF were correlated separately to the treatment time.

RESULTS

The number of trays differed between sexes (P = .0015). The absolute maximum torque was marginally associated with the total number of trays (P = .0518), while the rest of the orthodontic tooth movement showed no correlation. The composite score showed a higher correlation with the total number of trays (P = .0045) than did individual tooth movement. Pretreatment upper and lower anterior segment PAR scores were positively associated with the treatment time (P < .001).

CONCLUSIONS

There is not enough evidence to conclude that certain types of tooth movement affect the total aligner treatment time. A composite score seems to be a better predictor for total treatment time than do individual malalignment factors in aligner treatment. Upper and lower anterior malalignment factors have a significant effect on the treatment duration.

The Prediction Accuracy of Digital Orthodontic Setups for the Orthodontic Phase before Orthognathic Surgery

The purpose of this study was to verify whether pre-treatment digital setups can accurately predict the tooth positions after presurgical orthodontic treatment has been performed in a 3-dimensional way. Twenty-six patients who underwent a combined orthodontic-orthognathic surgical treatment were included. Pre-treatment digital dental models were merged with cone beam computed tomography (CBCT) scans. One operator fabricated virtual setups to simulate the tooth movements of the presurgical orthodontic treatment. Prior to surgery, digital dental models were merged with the CBCT scans. Differences between de virtual setups and the presurgical dental models were calculated using linear mixed model analyses. Differences in tooth displacements exceeding the boundaries of clinical acceptance (>2 degrees for rotations and >0.6 mm for translations) were found in 75% of the rotational and 52% of translational mean differences in the maxilla and in 74% of the rotational mean differences and 44% of the translational mean differences in the mandible. Significant differences were found for all tooth types and in all tooth displacement directions with significant effects of extractions and surgically assisted rapid maxillary expansion (SARME) procedures. The accuracy of the digital setup is still too limited to correctly simulate the presurgical orthodontic treatment.

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.

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.

Cytotoxicity and estrogenicity of a novel 3-dimensional printed orthodontic aligner

INTRODUCTION

Orthodontic aligners printed with in-office 3-dimensional (3D) procedures have been described, but no data on their biocompatibility exist. This study investigates the cytotoxicity and estrogenicity of a 3D-printed orthodontic aligner by assessing its biological and behavioral effects.

METHODS

Ten sets of 1 type of aligner were immersed in sterile deionized water for 14 days, and the cytotoxicity and estrogenicity of released factors were assessed via MTT (3-[4,5-dimethylthiazol-2-yl]-2,5-diphenyltetrazolium bromide) assays on human gingival fibroblasts and the estrogen-sensitive MCF-7 and the estrogen-insensitive MDA-MB-231 breast cancer cell lines. 17β-Estradiol and bisphenol-A were used as positive controls. The statistical analysis of data was performed with generalized linear models at a 0.05 level of significance.

RESULTS

No signs of cytotoxicity were seen for the aligner samples for concentrations (v/v) of 20% (P = 0.32), 10% (P = 0.79), or 5% (P = 0.76). The antioxidant activity expressed as the capacity to reduce intracellular levels of reactive oxygen species was not affected in the aligner samples (P = 0.08). No significant estrogenicity was induced by the aligner samples compared with eluents from the negative control for both MCF-7 (P = 0.65) and MDA-MB-231 (P = 0.78). As expected, 17β-Estradiol and bisphenol-A stimulated MCF-7 cell proliferation, whereas no effect was observed on MDA-MB-231 cells.

CONCLUSIONS

In conclusion, if any factors were released during the 14-day aging of 3D-printed aligners in water, these were not found to be cytotoxic for human gingival fibroblasts and did not affect their intracellular reactive oxygen species levels. Moreover, no estrogenic effects of these putative eluates were observed based on an E-screen assay.