External apical root resorption in non-extraction cases after clear aligner therapy or fixed orthodontic treatment

Root resorption in clear aligner treatment detected by CBCT: a Systematic review and Meta-analysis

OBJECTIVE

The aim of this study was to evaluate the amount of external apical root resorption in patients who had undergone orthodontic treatment with clear aligners evaluated using cone beam computed tomography.

METHODS

Studies that evaluated external apical root resorption before and after comprehensive orthodontic treatment with clear aligners were assessed by performing an electronic search from 5 databases comprising PubMed, SCOPUS, EBSCO, Cochrane Library, and LILACS and manual searches in the relevant journals and the reference lists of the included studies. Database search, elimination of duplicate studies, and data extraction were performed independently by 2 authors. The quality of the included studies was assessed using the Risk of Bias in Non-randomised Studies-of Interventions and the Cochrane Collaboration's Risk of Bias Tool. Studies that reported the tooth length or volume were used for quantitative analyses.

RESULTS

Nine studies were included in the meta-analysis. The overall root length after clear aligner treatment was significantly decreased compared with the pre-treatment length using cone beam computed tomography (mean differences = -0.56 mm, 95% confidence interval [-0.73, -0.38], P < .00001). However, only the maxillary central incisors, maxillary lateral incisors, and mandibular central incisors had significant reduction in root length. The meta-analysis from 3 studies also indicated that the root volume of the upper incisors also significantly decreased (mean differences = -13.34 mm3, 95% confidence interval [-16.57, -10.10], P < .00001).

CONCLUSIONS

Current evidence suggests that clear aligners can cause minimal root resorption. The highest amount of root resorption was observed in the maxillary central incisors.

Panoramic evaluation of external root resorption in mandibular molars during orthodontic treatment: a comparison between root-filled and vital teeth treated with fixed appliances or clear aligners

BACKGROUND

This investigation compared the extent of external apical root resorption (EARR) in root-filled teeth (RFT) and their contralateral vital pulp teeth (VPT) counterparts during orthodontic treatment (OT) with clear aligner (CA) treatment or fixed appliance (FA) treatment.

METHODS

Sixty-six patients with similar baseline American Board of Orthodontics (ABO) discrepancy index scores were divided into two groups: 37 patients (21 females, 16 males; mean age 17.45 ± 2.67 years) in the FA group, and 29 patients (18 females, 11 males; mean age 18.33 ± 1.96 years) in the CA group. Digital panoramic radiographs captured pre- and post-OT were used to measure tooth lengths and root surface measurements in mandibular molars. EARR in both RFT and contralateral VPT was evaluated pre- and post-OT. Statistical analysis employed paired t-tests, independent t-tests, and analysis of covariance (ANCOVA) (p < .05).

RESULTS

All teeth exhibited varying degrees of EARR following OT. FA treatment resulted in significantly longer treatment duration (p < .05) and greater EARR compared to CA treatment (p < .05). Moreover, statistically significant differences in EARR were observed within both groups between RFT and VPT (p < .05).

CONCLUSIONS

Comparison of pre- and post-OT radiographs revealed different degrees of EARR in all teeth. CA treatment resulted in less frequent and less severe EARR compared to FA treatment. RFT demonstrated greater resistance to EARR than VPT in both treatment groups.

Comparative assessment of external apical root resorption between subjects treated with clear aligners and fixed orthodontic appliances: A systematic review and meta-analysis

This review aims to collate and analyze the existing evidence on the comparison of external apical root resorption (EARR) in subjects treated with clear aligners (CAs) and fixed appliances (FA). An electronic search was conducted in six databases for articles published in all languages until July 2023. Studies that evaluated EARR in subjects treated with CAs and FAs were included. The RoB 2 tool for RCTs and the ROBINS-I tool for non-randomized studies were used to analyze the risk of bias (ROB). A random effects meta-analysis was performed to assess EARR extent in maxillary and mandibular anterior teeth for subjects treated with CAs and FAs. Ten studies (eight retrospective, one RCT, and one CCT) were included in this review, out of which six studies reported a moderate ROB, one reported a serious ROB, and three reported a low ROB on qualitative analysis. The quantitative analysis of six studies revealed a significant intergroup difference (P<0.05) in the mean EARR for maxillary central (SMD=-0.62, P<0.00001) and lateral incisors (SMD=-0.47, P=0.01) with a moderate heterogeneity (I2=56%), as well as the mandibular central incisors (SMD=-0.27, P=0.04) with high heterogeneity (I2=79%). EARR was lower in subjects treated with CAs than FAs. A moderate quality of the available evidence suggests that EARR was less evident in subjects treated with CAs when compared with FAs.

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.

In vitro analysis of the influence of the thermocycling and the applied force on orthodontic clear aligners

The mechanical properties of polyurethane dental aligners have been studied in an oral environment at 37°C and subjected to thermal cycling between 5°C and 55°C for long periods of time at different mechanical stresses. The aim is to determine the efficacy of the orthodontic aligner at different stress levels, the effect of thermal cycling with therapy time on tooth position correction. Sixty aligners with the same design were studied applying tensions of 0, 3 and 30 N and determining the deformation at different times from 1 to 760 h. Half of these aligners were subjected to stresses submerged in artificial saliva at 37°C and the other half were subjected to thermal cycles between 2°C and 55°C in salivary medium. Deformation was determined using a high-resolution stereo magnifier and ImageJ image analysis software. Water adsorption by the polyurethane was determined at the different test times. The results showed that in the unloaded aligners there is no appreciable deformation, but with thermal cycling there is a light shrinkage of the aligner due to the semi-crystallization process (ordering of polymeric chains) of the polyurethane. When applying loads of 3 and 30 N, creep curves with constant deformation transition zones can be seen. The transition zones decrease as the applied mechanical load increases. In addition, the significant effect of thermal cycling on the reduction of the transition zone of the aligners has been demonstrated. The transition zones are optimal for dental correction as constant stresses are exerted for tooth movement. The effect of thermal cycling shortens the constant deformation zone and reduces tooth alignment time. It was observed that the absorption of water in the aligner is constant after 1 h of immersion and does not exceed 0.4% by weight of absorbed water.

Comparison of efficacy between MBT preadjusted edgewise appliance and clear aligner therapy among class I crowding cases: A randomized controlled trial

Background

To compare the efficacy of McLaughlin Bennett Trevisi (MBT) appliance and Clear Aligner Therapy (CAT) among nonextraction Class I crowding cases.

Methods

The study sample (60 patients) was allotted into two equal groups (30 patients each) using block randomization wherein Group 1: treated with 0.018" MBT appliance and Group 2: treated with CAT for correction of malocclusion. At the end of treatment (T1), treatment duration, chairside time, laboratory time, number, and type of appointments were noted from treatment record cards. For comparing the acceptability among patients treated with both modalities at T1, the patients were interviewed regarding the comfort and ease of using an appliance with a questionnaire-based survey.

Results

The median number of nonscheduled/emergency and finishing stage appointments was significantly higher in Group 1 compared to Group 2 (P-value <0.001). The median duration of treatment at the scheduled, finishing, and overall appointments, was significantly higher in Group 1 compared to Group 2 (P-value <0.001). The median chairside time of all appointments was significantly higher in Group 1 compared to Group 2 (P-value <0.001). The experience with treatment and overall acceptability was significantly higher in Group 2 compared to Group 1 (P-value <0.001). However, mean laboratory time per aligner fabrication in Group 2 was 30.26 ± 3.45 min against no laboratory time consumed in Group 1.

Conclusions

CAT significantly reduces treatment duration, chairside time, number of nonscheduled/emergency, and finishing stage appointments in nonextraction Class I crowding cases. Prospective studies with 3D aligner systems are recommended to add further evidence in this regard.

Clinical Trials Registry-India Registration No

CTRI/2018/04/013301.

Does maxillary sinus proximity affect molar root resorption during distalization using Invisalign? a CBCT study

BACKGROUND

This study aimed to assess the correlation between maxillary sinus proximity to root apices of maxillary molars and root resorption during molar distalization using clear aligner therapy (CAT).

MATERIALS AND METHODS

Thirty-eight cone beam computed tomography scans (CBCTs) obtained pre- (T0) and post-treatment (T1) from 19 adult patients (36.68 ± 13.50 years), who underwent maxillary molar distalization using Invisalign® aligners (Align Technology, Inc., San José, CA, USA) with a minimum of 2 mm distalization, were evaluated in this study At least 22 h of aligner wear per day was a main inclusion criterion. Sinus proximity and changes in root lengths were measured for 61 molars (183 roots). Spearman coefficient analysis was used for assessing correlation between sinus proximity and root resorption. The level of significance was set at p ≤ 0.05. The reproducibility of measurements was assessed by intraclass correlation coefficient (ICC).

RESULTS

Spearman coefficient revealed no significant correlation between sinus proximity and molar root resorption for mesiobuccal, distobuccal or palatal roots (p = 0.558, p = 0.334, p = 0.931, respectively).

CONCLUSION

There was no correlation between maxillary sinus proximity to root apices of maxillary molars and root resorption.

Fused filament fabrication (FFF): influence of layer height on forces and moments delivered by aligners-an in vitro study

OBJECTIVES

To investigate the effect of layer height of FFF-printed models on aligner force transmission to a second maxillary premolar during buccal torquing, distalization, extrusion, and rotation using differing foil thicknesses.

MATERIALS AND METHODS

Utilizing OnyxCeph3™ Lab (Image Instruments GmbH, Chemnitz, Germany, Release Version 3.2.185), the following movements were programmed for the second premolar: buccal torque (0.1-0.5 mm), distalization (0.1-0.4 mm), extrusion (0.1-0.4 mm), rotation (0.1-0.5 mm), and staging 0.1 mm. Via FFF, 91 maxillary models were printed for each staging at different layer heights (100 µm, 150 µm, 200 µm, 250 µm, 300 µm). Hence, 182 aligners, made of polyethylene terephthalate glycol (PET-G) with two thicknesses (0.5 mm and 0.75 mm), were prepared. The test setup comprised an acrylic maxillary model with the second premolar separated and mounted on a sensor, measuring initial forces and moments exerted by the aligners. A generalized linear model for the gamma distribution was applied, evaluating the significance of the factors layer height, type of movement, aligner thickness, and staging on aligner force transmission.

RESULTS

Foil thickness and staging were found to have a significant influence on forces delivered by aligners, whereas no significance was determined for layer height and type of movement. Nevertheless, at a layer height of 150 µm, the most appropriate force transmission was observed.

CONCLUSIONS

Printing aligner models at particularly low layer heights leads to uneconomically high print time without perceptible better force delivery properties, whereas higher layer heights provoke higher unpredictability of forces due to scattering. A z-resolution of 150 µm appears ideal for in-office aligner production combining advantages of economic print time and optimal force transmission.

Investigating the Effectiveness of Low-Level Laser in Reducing Root Resorption of the Upper Incisors During Intrusion Movement Using Mini-Implants in Adult Patients With Deep Overbite: A Randomized Controlled Clinical Trial

BACKGROUND

Deep bite is a common characteristic of malocclusion, and many methods are used to treat it, including mini-implants used for the intrusion of the upper incisors. Orthodontically induced inflammatory root resorption (OIIRR) is an inevitable and unexpected side effect of orthodontic therapy. However, resorption of the root could be affected by the type of tooth movement, such as intrusion. Several studies have indicated the effectiveness of low-level laser therapy (LLLT) in accelerating orthodontic movement, but studies that have evaluated the role of this laser in reducing the risk of OIIRR have been limited. This trial aimed to investigate the effectiveness of LLLT in reducing the resorption of the roots of the upper incisors during their intrusion in the context of deep bite correction.

MATERIALS AND METHODS

Thirty patients (13 males, 17 females; mean age 22.4±3.37 years) with deep overbite were recruited and allocated to the laser or the control groups. Mini-implants were inserted between the roots of the upper central incisors and the lateral incisors from the labial aspect at the gingival-mucosal junction on both sides with a force of 40 g on each side through an NiTi coil spring. A low-level laser (Ga-Al-As) with 808 nm wavelength in a continuous mode, with the parameters 250 milliwatt power output, 4 Joules/point energy density, and 16 seconds irradiation per point, was applied to the root of each of the upper incisors. The laser was applied on the first day of the upper incisor intrusion (T1), then on days 3, 7, and 14 of the first month. In the second month, the laser was applied every 15 days, adjusting the spring strength every four weeks until the end of the intrusion stage (T2), which was determined by reaching a normal overbite. As for patients in the control group, the strength of the nickel-titanium springs was adjusted every four weeks to the required strength of 40 g on each end until reaching a normal overbite.

RESULTS

There was a volumetric decrease in both groups' upper central and lateral incisors roots, and this decrease was statistically significant (P<0.001). However, the difference between the two groups was not statistically significant in each central and lateral incisor volume root (P=0.345 and 0.263 for U1 and U2, respectively). Also, both groups had a linear decrease in upper central and lateral incisors roots, which was statistically significant (P<0.001). At the same time, the difference between the two groups was not statistically significant in each central and lateral incisor root length (P=0.343 and 0.461 for U1 and U2, respectively).

CONCLUSION

The low-level laser irradiation using the current protocol did not significantly affect the amount of root resorption induced by incisor intrusion in the experimental group compared to the control group.

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.

Three-dimensional analysis of root changes after orthodontic treatment for patients at different stages of root development

INTRODUCTION

We investigated changes in the roots of maxillary incisors at different stages of root development after fixed-appliance treatment using cone-beam computed tomography.

METHODS

Data from 52 subjects receiving fixed-appliance treatment were collected retrospectively. The subjects were divided into 3 groups: mixed dentition group (aged 7-10 years; root development stage: Nolla eighth-10th; n = 16), early permanent dentition group (aged 12-18 years; root development stage: Nolla 10th; n = 20), and adult group (aged 18-35 years; root development stage: Nolla 10th; n = 16). Changes in root lengths and volume of the maxillary central incisors were measured using pretreatment and posttreatment cone-beam computed tomography.

RESULTS

The root lengths and volumes of maxillary central incisors in the mixed dentition group significantly increased after orthodontic treatment (P >0.05). No significant differences were found when comparing the final root length and volume of the mixed dentition group with the pretreatment maxillary incisor values of the early permanent dentition group (P >0.05). The early permanent dentition group showed a significant decrease in root length (P <0.05), and both the root length and volume of the adult group significantly decreased after treatment (P <0.05). The differences in root length and volume reduction between the 2 groups were not significant (P >0.05).

CONCLUSIONS

Orthodontic treatment had no significant negative impact on the continued root development of incomplete roots with two-thirds root formation. Both the early permanent dentition and adult groups exhibited root resorption after orthodontic treatment. It seemed age was not a factor that resulted in significant root resorption during routine orthodontic leveling and alignment treatment once the roots were fully developed.

Evaluation of external apical root resorption caused by fixed functional treatment of class II malocclusion : Cast splint Herbst appliance vs. Forsus fatigue resistant device

INTRODUCTION

The aim of this study was to evaluate and compare the effects of class II fixed functional treatment with a cast splint Herbst appliance (HA; Herbst Set I, Dentaurum, Ispringen, Germany) and Forsus fatigue resistant device (FRD; 3M Unitek Corp., Monrovia, CA, USA) on external apical root resorption (EARR) in posterior teeth.

METHODS

In all, 40 patients (15 male and 25 female) with class II division 1 malocclusion were treated with two fixed functional appliances: HA (20 patients, mean age 14.60 ± 1.14 years) and FRD (20 patients, mean age 14.15 ± 1.28 years). The vestibular lengths of the first molars and premolars were measured on panoramic radiographs and converted to actual tooth length using the magnification coefficient (MC), which was calculated using dental models. Intragroup comparisons of pre- and posttreatment tooth lengths were performed with the paired t‑test and Wilcoxon signed-rank test, while intergroup comparisons were performed with the Mann-Whitney U test.

RESULTS

Pretreatment tooth length values decreased significantly with HA and FRD therapies for all posterior teeth. The maximum resorption was observed in the mandibular first premolar with a mean of 0.81 mm following HA and 1.55 mm following FRD treatment. While no significant difference existed between the EARR values of the HA and FRD groups for maxillary teeth, the amount of EARR of mandibular posterior teeth in the FRD group was significantly higher than in the HA group.

CONCLUSIONS

In patients treated with HA or FRD, the tooth length of posterior teeth decreased to a clinically minor but statistically significant degree. The root resorption effect of FRD therapy in mandibular posterior teeth was significantly higher than that of HA therapy.

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.

External apical root resorption 6 months after initiation of orthodontic treatment: A randomized clinical trial comparing fixed appliances and orthodontic aligners

Objective

To compare the magnitude of external apical root resorption (EARR) 6 months after starting orthodontic treatment using orthodontic aligners (OAs) and fixed appliances (FAs).

Methods

This parallel randomized clinical trial included 40 patients randomized into two groups OA group (n = 20, 160 incisors) and FA group (n = 20, 160 incisors). For evaluation of the tooth length, periapical radiographs and standardized linear measurements of the maxillary and mandibular incisors were acquired before (T0) and 6 months after treatment initiation (T1). EARR was calculated through the difference in length between the two time points (T1–T0). Statistical comparisons were performed by means of using t-tests, chi-squared test and covariance analysis (a = 5%).

Results

Rounding of the root apex was observed in both groups; the resorption involved 2.88% of the root length, so 97.12% of the tooth length remained intact. Intragroup comparisons between the two time points revealed a significant difference, with (T1–T0) ranging from −0.52 to −0.88 mm in the FA group and from −0.52 to −0.85 mm in the OA group. In the intergroup comparisons, only tooth #21 presented a statistically significant difference (OA −0.52 ± 0.57 mm, FA −0.86 ± 0.60 mm); however, the overall differences between groups were not clinically relevant, ranging from 0.03 to 0.35 mm.

Conclusions

OA and FA treatment resulted in a similar degree of EARR in the maxillary and mandibular incisors at 6 months after treatment initiation. However, the amount of resorption was small and does not impair tooth longevity.

Biocompatible orthodontic cement with antibacterial capability and protein repellency

BACKGROUND

White spot lesions (WSLs) often occur in orthodontic treatments. The objectives of this study were to develop a novel orthodontic cement using particles of nano silver (NAg), N-acetylcysteine (NAC) and 2-methacryloyloxyethyl phosphorylcholine (MPC), and to investigate the effects on bonding strength, biofilms and biocompatibility.

METHODS

A commercial resin-modified glass ionomer cement (RMGIC) was modified by adding NAg, NAC and MPC. The unmodified RMGIC served as the control. Enamel bond strength and cytotoxicity of the cements were investigated. The protein repellent behavior of cements was also evaluated. The metabolic assay, lactic acid production assay and colony-forming unit assay of biofilms were used to determine the antibacterial capability of cements.

RESULTS

The new bioactive cement with NAg, NAC and MPC had clinically acceptable bond strength and biocompatibility. Compared to commercial control, the new cement suppressed metabolic activity and lactic acid production of biofilms by 59.03% and 70.02% respectively (p < 0.05), reduced biofilm CFU by 2 logs (p < 0.05) and reduced protein adsorption by 76.87% (p < 0.05).

CONCLUSIONS

The new cement with NAg, NAC and MPC had strong antibacterial capability, protein-repellent ability and acceptable biocompatibility. The new cement is promising to protect enamel from demineralization during orthodontic treatments.

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

OBJECTIVE

The aim of this study was to evaluate and compare the amount of external apical root resorption (EARR) observed during the orthodontic treatment with pre-adjusted edgewise appliance (PEA) or clear aligner therapy (CAT) and with 2D or 3D radiographic methods of measuring the root resorption.

SEARCH STRATEGY AND SELECTION CRITERIA

A search of PubMed MEDLINE, Scopus, Cochrane Central Register of Controlled Trials, LILACS, Web of Science, Dissertations & Theses Global, ClinicalTrials.gov registry, and the ISRCTN Registry was performed. Studies that have evaluated the amount of root resorption in non-extraction cases using CAT or PEA were selected for the systematic review. A meta-analysis was performed for the amount of root resorption of permanent maxillary incisors using PEA or CAT treatment modalities by either 2D or cone-beam computed tomography radiographic examination.

DATA COLLECTION AND ANALYSIS

Database research, elimination of duplicate studies, data extraction, and risk of bias were performed by authors independently and in duplication. A random-effect meta-analysis followed by subgroup comparisons were performed to evaluate EARR.

RESULTS

A total of 16 studies (4 were prospective and 12 were retrospective) were identified for inclusion in the systematic review. The mean root resorption for the permanent maxillary incisors was in the range from 0.25 to 1.13 mm (overall: 0.49 mm; 95% confidence interval [CI] = 0.24 to 0.75 mm). The mean root resorption difference between CAT and PEA was statistically significant (P < 0.05) for 12 but not for 21, 11, or 22.

LIMITATIONS

One of the drawbacks is a lack of good quality prospective studies, specifically randomized clinical trials in the literature.

CONCLUSIONS AND IMPLICATIONS

Neither PEA or CAT technique leads to clinically significant root resorption (1 mm) of the maxillary incisors. The amount of EARR of maxillary incisors is not significant in comparing two treatment modalities (PEA and CAT), except for 12, where the PEA group has significantly more EARR when compared to CAT.

REGISTRATION

The protocol for this systematic review was based on the Cochrane Handbook for Systematic Reviews of Interventions 5.1.0 and was registered at PROSPERO database (https://www.crd.york.ac.uk/prospero/display_record.php?ID=CRD42018113051). This systematic review is reported according to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses statement.

Risk Factors of Composite Attachment Loss in Orthodontic Patients during Orthodontic Clear Aligner Therapy: A Prospective Study

BACKGROUND

The composite attachment loss during orthodontic clear aligner therapy is an adverse event that commonly happens in our daily practice. However, there is a lack of related statistical analysis and studies analyzing the related risk factors. Therefore, the aim of this study is to assess the incidence of attachment loss during orthodontic clear aligner therapy and to identify rick factors that may predict such event.

MATERIALS AND METHODS

The demographics and clinical variables of 94 patients undergoing clear aligner therapy (27 males and 67 females; average age: 27.60 ± 0.86 years) were recorded. Both patient-related and tooth-related attachment loss was recorded. The chi-squared test and logistic regressive analysis were applied to identify the potential risk factors. SPSS for Mac (version 23.0, IBM, USA) was used for statistical analyses. P < 0.05 was considered statistically significant.

RESULTS

Our study suggested that the risk factors for attachment loss include frequent aligner removal (≥ 5 times a day) (losing rate = 60.0%, P = 0.005), aligner wear time less than 18 hours a day (losing rate = 50.8%, P = 0.014), eating without aligners inserted (losing rate = 47.9%, P = 0.034), utilizing aligner tray seaters (losing rate = 48.2%, P = 0.006), and unilateral mastication (losing rate = 52.1%, P = 0.002). The multivariable logistic regression analysis indicates that aligner wear time less than 18 hours a day (P = 0.020, B = 0.925), using aligner tray seaters (P = 0.007, B = 1.168), and unilateral mastication (P = 0.034, B = -0.458) were considered independent factors that can predict the composite attachment loss in orthodontic clear aligner therapy.

CONCLUSION

Wearing aligner less than 18 hours a day, using aligner tray seaters, and unilateral mastication may contribute to increased incidence of composite attachment loss during orthodontic clear aligner therapy.

The effectiveness of traditional corticotomy vs flapless corticotomy in miniscrew-supported en-masse retraction of maxillary anterior teeth in patients with Class II Division 1 malocclusion: A single-centered, randomized controlled clinical trial

INTRODUCTION

This single-centered, parallel-groups trial aimed to evaluate the efficacy of traditional corticotomy vs flapless corticotomy in accelerating en-masse retraction. In addition, to assess the skeletal, dental, and soft-tissue variables, as well as the external apical root resorption (EARR) of the maxillary anterior teeth.

METHODS

Forty patients with Class II Division 1 malocclusion aged >18 years at the beginning of treatment, requiring maxillary first premolar extractions, were randomly distributed into 2 groups (n = 20 each): 1 group was treated using traditional corticotomy, and the other group was treated with flapless corticotomy in en-masse retraction with anchorage based on miniscrews placed between maxillary second premolars and first molars bilaterally. Randomization was implemented with a computer-generated list of random numbers; allocation was concealed in sequentially numbered, opaque, sealed envelopes. The study was single-blinded (outcomes' assessor). The primary outcome was the en-masse retraction duration. Secondary outcomes were the skeletal, dental, and soft-tissue changes on lateral cephalometric and the EARR of maxillary anterior teeth on digital panoramic radiographs.

RESULTS

The en-masse retraction duration in the flapless corticotomy group was longer than the traditional corticotomy group. The average retraction duration was 4.04 ± 1.10 months for the flapless corticotomy group and 3.75 ± 2.14 months for the traditional corticotomy group, with no significant difference between the 2 groups (95% confidence interval [CI], -0.81 to 1.39; P = 0.59). No significant differences were observed between the 2 groups regarding changes in several lateral cephalometric variables (eg, SNA angle [95% CI, -2.55° to 1.66°; P = 0.67], SN-U1 angle [95% CI, -1.70° to 1.32°; P = 0.80], and UL-E [95% CI: -1.33 to 1.00 mm; P = 0.78]) or in the amount of EARR in the maxillary anterior teeth (P = 0.31). The proportion of the observed EARR ranged from 1% to 6% of root length in both corticotomy groups. No serious harms were observed in both groups.

CONCLUSIONS

No significant differences between the flapless and traditional corticotomies were found in terms of the skeletal, dental, and soft-tissue variables as well as in the amount of EARR. Corticotomy-assisted en-masse retraction led to improvements in skeletal structures and facial profile and resulted in sufficient retraction of maxillary anterior teeth, slight distal movement of maxillary first molars, and an intrusion movement for both anterior and posterior teeth. Both corticotomy techniques did not cause significant EARR.

REGISTRATION

ClinicalTrials.gov (Identifier: NCT03279042).

PROTOCOL

The protocol was not published before the trial commencement.

Treatment outcome with orthodontic aligners and fixed appliances: a systematic review with meta-analyses

Background

The use of orthodontic aligners to treat a variety of malocclusions has seen considerable increase in the last years, yet evidence about their efficacy and adverse effects relative to conventional fixed orthodontic appliances remains unclear.

Objective

This systematic review assesses the efficacy of aligners and fixed appliances for comprehensive orthodontic treatment.

Search methods

Eight databases were searched without limitations in April 2019.

Selection criteria

Randomized or matched non-randomized studies.

Data collection and analysis

Study selection, data extraction, and risk of bias assessment was done independently in triplicate. Random-effects meta-analyses of mean differences (MDs) or relative risks (RRs) with their 95% confidence intervals (CIs) were conducted, followed by sensitivity analyses, and the GRADE analysis of the evidence quality.

Results

A total of 11 studies (4 randomized/7 non-randomized) were included comparing aligners with braces (887 patients; mean age 28.0 years; 33% male). Moderate quality evidence indicated that treatment with orthodontic aligners is associated with worse occlusal outcome with the American Board of Orthodontics Objective Grading System (3 studies; MD = 9.9; 95% CI = 3.6–16.2) and more patients with unacceptable results (3 studies; RR = 1.6; 95% CI = 1.2–2.0). No significant differences were seen for treatment duration. The main limitations of existing evidence pertained to risk of bias, inconsistency, and imprecision of included studies.

Conclusions

Orthodontic treatment with aligners is associated with worse treatment outcome compared to fixed appliances in adult patients. Current evidence does not support the clinical use of aligners as a treatment modality that is equally effective to the gold standard of braces.

Registration

PROSPERO (CRD42019131589).

Force direction using miniscrews in sliding mechanics differentially affected maxillary central incisor retraction: Finite element simulation and typodont model

Background/purpose

En masse retraction was still controversy in orthodontics. The aim of this study was to investigate the effect of force directions created by different miniscrew positions and lever arm heights on maxillary central incisor movement using Finite Element (FE) simulation and a Typodont model.

Materials and methods

A typodont model and 3-dimensional FE were used to simulate en masse anterior teeth retraction in sliding mechanics. The lever arm and the miniscrew positions were varied to change the force direction. The maxillary central incisor displacement was recorded and analyzed.

Results

The typodont results revealed that miniscrew vertical position and lever arm height affected the type of tooth movement. The best control in the vertical plane was achieved by a 7 mm lever arm height and miniscrew 9 mm from the archwire. When the lever arm height and miniscrew were 7 mm from the archwire, the tooth extruded. When the lever arm height was 9 mm and the miniscrew was 7 or 9 mm from the archwire, the tooth intruded. The FE stimulation determined that near bodily movement of the maxillary central incisor was achieved when the lever arm height and miniscrew was 9 mm from the archwire. The highest strain distribution in the periodontal ligament was observed at the apical third of the lateral incisor.

Conclusion

In en masse retraction, the appropriate direction of force or the height of the miniscrew and the lever arm may enable orthodontists to maintain better control of the anterior teeth in sliding mechanics.