Interproximal Enamel Reduction Research Articles

Friction and wear behavior of a mechanical oscillating strip system used for interproximal enamel reduction: a quantitative and qualitative scanning electronic microscope evaluation.

To evaluate wear and friction properties of oscillating strips in order to validate the importance of a standardized interproximal enamel reduction (IPR) sequence to preserve their efficiency and lifetime. Fifteen complete oscillating IPR sequences were tested by means of tribological tests (Linear Reciprocating Tribometer, C.S.M. Instruments, Peseaux, Switzerland). Fifteen single 0.2-mm metallic strips underwent a long continuous cycle of 240 minutes. Strip surface roughness and waviness measurements were assessed by means of a contact probe surface profiler (TalySurf CLI 2000; Taylor Hobson, Leicester, UK) and TayMap software. Statistical analysis was performed with independent-samples t-test. Significance was at the P < .05 level. Scanning electronic microscopy analysis of strip surfaces was conducted with an FEI Quanta 200 (Hillsboro, Ore) in high vacuum at 30.00 kV. Resin strips revealed a significant reduction in surface roughness (Ra, Rt, RDq) and a significant increase in waviness parameters (Wa, Wt). Rt and RDq values significantly decreased upon use of the metallic strips. Significantly higher values of Wa (+ 2.84 µm) and Wt (+0.1 µm) were observed only for the 0.2-mm metallic strips. Higher friction values were observed when the metallic strips were tested singularly rather than within the entire sequence. Lower Ra and Rt values were revealed when 0.2-mm metallic strips were tested up to 240 minutes. The application of a standardized oscillating sequence allows for more efficient wear performance of the strips with a significant impact on their abrasive power and lifetime.

Novel Technique of Interproximal Enamel Reduction Based on Computer-Aided Navigation Technique-An In Vitro Study.

The aim of this study was to analyze and compare the accuracy of a novel interproximal enamel reduction (IPR) technique based on a computer-aided static navigation technique with respect to a conventional free-hand-based technique for interproximal enamel reduction. Twenty anatomical-based experimental cast models of polyurethane were randomly distributed into the following IPR techniques: IPR technique based on computer-aided static navigation technique (n = 10) (GI) for Group A and conventional free-hand-based technique for the IPR (n = 10) (FHT) for Group B. The anatomical-based experimental cast models of polyurethane randomly assigned to the GI study group were submitted for a preoperative 3D intraoral surface scan; then, datasets were uploaded into 3D implant-planning software to design virtual templates for the interproximal enamel reduction technique. Afterward, the anatomical-based experimental cast models of polyurethane of both GI and FHT study groups were subjected to a postoperative digital impression by a 3D intraoral surface scan to compare the accuracy of the interproximal enamel reduction techniques at the buccal (mm), lingual/palatal (mm), and angular (◦) levels using the Student t-test. Statistically significant differences between the interproximal enamel reduction technique based on the computer-aided static navigation technique and the conventional free-hand-based technique for the interproximal enamel reduction at the buccal (p = 0.0008) and lingual/palatal (p < 0.0001) levels; however, no statistically significant differences were shown at the angular level (p = 0.1042). The interproximal enamel reduction technique based on computer-aided static navigation technique was more accurate than the conventional free-hand-based technique for interproximal enamel reduction.

Predictability of Dental Distalization with Clear Aligners: A Systematic Review.

The current review aims to evaluate the scientific evidence relating to the effectiveness of treatment with clear aligners (CAs) in controlling distalization orthodontic tooth movement. "Orthodontics, aligners" and "distalization" were the search terms used on the Scopus, Web of Science and Pubmed databases with the Boolean operator "AND". The results of the last ten years of research were 146 studies; of these, 19 publications were included for this review. The distalization movement is possible with invisible masks alone, but the risk of losing anchorage in the anterior sectors is very probable. The stability of the results and the reduction of unwanted effects can be guaranteed by the use of skeletal anchoring devices and interproximal enamel reduction (IPR), with which compensations are obtained to reduce the initial overjet. Temporary anchorage devices (TADs) can be used to manage posterior anchorage after distalization of maxillary molars with aligners. This hybrid approach has demonstrated the greatest orthodontic success. TADs are useful aids to provide direct and indirect skeletal anchorage. The opposite effect must be considered when planning dental distalization, especially of the molars, in patients with large overjet, and corrective measures or the use of auxiliaries may be necessary to prevent midcourse corrections. This systematic review provides a critical evidence-based assessment of the predictability of dental distalization with CAs, an ever-evolving orthodontic technique.

Correlation between the Crowding Severity, the Amount of IPR and the Number of Teeth Moved

The aim of this study is to determine the relationship between the severity of crowding, the need of the interproximal enamel reduction (IPR, stripping), and the number of moved teeth.&#x0D; One hundred and twenty-seven patients aged from 18 to 62 years, of whom 99 (78%) women and 28 (22%) men in need of active orthodontic treatment were included in the study. All patients underwent orthodontic treatment with DENT@LIGN digital aligners on etsablished protocol. The severity of crowding and the amount of IPR were measured.&#x0D; The stripping is coded in six groups, based on amount (≤ 1 mm; 1.1 to 2.0 mm; 2.1 to 3.0 mm; 3.1 to 4.0 mm; 4.1 to 5.0 mm, and greater than 5.1), and the crowding in four groups: no crowding; mild crowding (0.1 mm to 3.0 mm); moderate crowding (3.1 mm to 7.0 mm); severe crowding (over 7.1 mm).&#x0D; The Spearman test showed a significant positive correlation between stripping size and crowding severity in both jaws. In the upper jaw the correlation coefficient is rs = 0.430, p &lt; 0.001. In the lower jaw, the correlation coefficient was higher rs = 0.514), p &lt;0.001.&#x0D; The results of the Pearson test showed a direct proportional relationship between the number of teeth in need of movement and the size of stripping in the upper and lower jaws.&#x0D; Based on the number of moved teeth, the size of the stripping can be predicted by the following formulas: Upper jaw stripping (mm) = –0.3891 + 0.1711 × Number of moved teeth, with predictive value of R-square = 17.2%; Lower jaw stripping (mm) = –0.8965 + 0.2773 × Number of teeth moved, with predictive value of R-square = 28.1%.

Experimental validation of mechanical oscillating IPR system.

Interproximal enamel reduction (IPR) is a clinical procedure which involves reduction and anatomic recontouring of interproximal surfaces of enamel as a method of gaining space. The biological effects related to this clinical procedure have long been discussed. Thus, the aim of this study was to evaluate the enamel reduction efficiency and the effects on enamel surfaces of the oscillating mechanical system for interproximal enamel reduction (IPR). Fifteen complete oscillating IPR sequences included one opener (0.1 mm), two metallic strips for active IPR phase (0.2 and 0.3 mm), three resin strips for active and initial polishing phases (0.4 and 0.5 mm), and one resin strip for polishing phase (0.15 mm). Sequences were selected and tested on fifteen freshly extracted teeth by means of tribological tests with alternative dry-sliding motion (Linear Reciprocating Tribometer; C.S.M. Instruments, Peseaux, Switzerland). A 3D analysis of treated surfaces was performed by using a TayMap software. Then, enamel surfaces were qualitatively evaluated before and after the tribological analysis, with a FEI Quanta 200 (FEI, Hillsboro, OR, USA) in high vacuum at 30.00 kV. Images were acquired at a 30×, 100× and 300× magnification. Minimum surface irregularities were observed on all treated enamel surfaces when compared with untreated ones. The 3D analysis showed a uniform wear pattern after tribological tests. Meanwhile, the SEM analysis revealed smooth and regular wear lines on treated surfaces after the entire mechanical IPR sequence. The macroscopic irregularities illustrated can be considered similar to those of untreated surfaces. The adoption of a standardized oscillating IPR sequence allows an efficient reduction of the interproximal enamel, leaving regular and harmonious surfaces. Adequate polishing procedures should always be performed at the end of active IPR phases in order to guarantee a good long-term prognosis and proper respect of biological structures.

The incidence and severity of open gingival embrasures in adults treated with clear aligners and fixed appliances: a retrospective cohort study

BackgroundTo evaluate the incidence and severity of open gingival embrasures (OGEs) in adult patients treated with clear aligners and fixed appliances.MethodsTwo hundred non-extraction adult subjects with less than 5 mm of crowding (mean age, 24.6 ± 3.8 years) were enrolled in this retrospective study. The subjects were divided into the clear aligner (n = 100) and fixed appliance group (n = 100). The intraoral photographs were utilized to determine the incidence of OGEs in the upper arch between maxillary central incisors, as well as the lower arch between mandibular central incisors. Crown overlap, crown shape, posttreatment root angulation, the distance from the interproximal contact point (ICP) to the alveolar bone crest (ABC) after treatment and interproximal enamel reduction (IPR) were determined in the two groups.ResultsThe incidence of OGEs between maxillary and mandibular central incisors after orthodontic treatment was 35.0% and 38.0% in the clear aligner group, respectively, significantly higher than that (18.0% and 24.0%) in the fixed appliance group (P < 0.05). The average area of an OGE after clear aligner treatment was larger both in the maxilla (0.16 ± 0.12mm2) and mandible (0.21 ± 0.24mm2) compared with that (0.05 ± 0.03mm2 and 0.05 ± 0.06mm2) after fixed appliance treatment (P < 0.05). No difference was found regarding pretreatment crown overlap, crown shape, treatment duration, posttreatment root angulation, amount and distribution of IPR and the distance from ICP to ABC.ConclusionsThe incidence and severity of OGEs were higher in adults treated with clear aligners. Clinicians should be aware of the risk of OGEs during treatment with clear aligners.

Long-term stability of mandibular incisor alignment in patients treated nonextraction with or without interproximal enamel reduction

This study aimed to compare long-term mandibular incisor stability in nongrowing patients with moderate crowding treated nonextraction with and without interproximal enamel reduction (IPR). Forty-two nongrowing patients with Class I dental and skeletal malocclusion with moderate crowding were divided into 2 groups with an equal number of patients depending on whether IPR was used (IPR group) or not (non-IPR group) during treatment. All patients were treated by the same practitioner and used thermoplastic retainers full-time for 12 ± 1 months at the end of the active treatment. Changes in Peer Assessment Rating scores, Little's irregularity index (LII), intercanine width (ICW), and mandibular incisor inclination (IMPA and L1-NB°) were evaluated using pretreatment, posttreatment, and 8 ± 1 years postretention dental models and lateral cephalograms. At the end of the treatment, Peer Assessment Rating scores and LII decreased, and ICW, IMPA, and L1-NB° increased significantly (P<0.001) in both groups. At the end of the postretention period, in both groups, LII increased, and ICW decreased significantly (P<0.001) compared with posttreatment values, whereas IMPA and L1-NB remained stable. When treatment changes were compared, increases in ICW, IMPA, and L1-NB were significantly (P<0.001) higher in the non-IPR group. When postretention changes were compared, the only significant difference between 2 groups was observed in ICW. The decrease in ICW was significantly higher in the non-IPR group. Long-term stability of mandibular incisor alignment in Class I nongrowing patients with moderate crowding treated nonextraction with and without IPR was similar.

Effects of IPR by mechanical oscillating strips system on biological structures: a quantitative and qualitative evaluation

BackgroundTo evaluate by means of profilometric analysis and scanning electronic microscope (SEM) the effects on enamel surfaces of oscillating mechanical systems for interproximal enamel reduction (IPR). Fifteen complete (Group 1) oscillating IPR sequence and 15 single metallic strips (Group 2) for active IPR phase of 0.2 mm were selected and tested on 30 freshly extracted teeth by means of tribological tests with alternative dry-sliding motion (Linear Reciprocating Tribometer, C.S.M. Instruments, Peseaux, Switzerland). Enamel surface roughness and waviness measurements were assessed by contact probe surface profiler (TalySurf CLI 2000; Taylor Hobson, Leicester, UK) and a TayMap software for the 3D analysis. Statistical analysis was performed with independent samples t-test. Significance was established at the P < .05 level. SEM analysis of enamel surfaces was conducted with a FEI Quanta 200 (Hillsboro, USA) in high vacuum at 30.00 kV. Images were acquired at 30X, 100X, and 300X of magnification.ResultsTeeth undergone Group 1 showed lower values of surface roughness (Ra − 0.34 µm, Rt − 1.55 µm) and significant increase of waviness parameters (Wa 0.25 µm, Wt 4.02 µm) when compared with those treated with Group 2. SEM evaluation showed smoothers and more regular surfaces when IPR was performed by complete IPR sequence. Single metallic strip determined more irregular surfaces characterized by extended grooves, alternated with enamel ridges and irregular fragments.ConclusionThe adoption of a standardized oscillating IPR sequence determines more regular and harmonious enamel surfaces at the end of the procedure. An adequate polishing after IPR plays a crucial role to guarantee a good long-term prognosis and a good respect of biological structures.

Efficacy and Accuracy of Maxillary Arch Expansion with Clear Aligner Treatment.

The aim of this work was to evaluate the efficacy and accuracy of maxillary arch transverse expansion using the Invisalign® clear aligner system without auxiliaries other than Invisalign attachments. Knowing the accuracy of a movement through a clear aligner system allows the clinician to plan the treatment with greater precision and to achieve the expected result faster. The study group included 28 patients with a mean age of 17 ± 3.2 years. The treatment protocol for all the selected patients included the application of the Invisalign® clear aligner system without auxiliaries, except for the Invisalign® attachments; in no case were tooth extraction or interproximal enamel reduction (IPR) performed. Linear measurements of the expansion were assessed before treatment (T0), at the end of treatment (T1), and on final virtual models by ClinCheck® (TC). A paired t-test was used to compare T0-T1 and T1-TC differences. A paired t-test was applied, and one normality was validated with the Shapiro-Wilks test. If normality was not met, the nonparametric test (Mann-Whitney U test) was applied. The level of significance was set at 5%. Statistically significant differences were found for all measurements at T0-T1. The results showed an average accuracy of efficacy of 70.88%. The differences in predictability between the various vestibular measurements (intercanine, inter-premolar, and intermolar) were not statistically significant, while they were for gingival measurements. The overall accuracy of the expansion treatment was 70%, regardless of tooth type.

Evaluation of Enamel Surfaces after Different Techniques of Interproximal Enamel Reduction

According to the literature, interproximal enamel reduction (IER) has become a consolidated technique used in orthodontic treatments to gain space in particular situations such as dental crowding, non-extractive therapies, tooth-size discrepancies, and prevention of dental relapse. There are different methods to realize stripping, and enamel surfaces resulting after this procedure can be analyzed with SEM. The aim of this study was to analyze how different devices of IER leave the surface of the teeth. One hundred and sixty freshly extracted, intact human lower incisors were included in the study, fixed in a plaster support, and then processed with four different techniques of enamel reduction and finishing. Then, they were divided randomly into eight groups (A1-A2, B1-B2, C1-C2, D, and E), each containing twenty teeth. The A, B, and C groups were divided into two subgroups and then all the teeth were observed at SEM. Each digital image acquired by SEM showed that there were streaks on the surfaces, due to the cutter used. The results of this study showed that only group C2 (tungsten carbide bur followed by twelve steps of medium-fine-ultrafine 3M Soft Lex disks) has a few line, which is very similar to group E (untreated group), while the other groups have a lot of lines and show a rougher final surface.

Evaluation of Resin Infiltration, Fluoride and the Biomimetic Mineralization of CPP-ACP in Protecting Enamel after Orthodontic Inter-Proximal Enamel Reduction

This study investigated the effect of using different agents for protecting enamel proximal surfaces against acidic attack after interproximal reduction (IPR) using the trans micro radiography technique. Seventy-five sound-proximal surfaces were obtained from extracted premolars for orthodontic reasons. All teeth were measured miso-distally and mounted before being stripped. The proximal surfaces of all teeth were hand stripped with single-sided diamond strips (OrthoTechnology, West Columbia, SC, USA) followed by polishing via Sof-Lex polishing strips (3M, Maplewood, MN, USA). Three-hundred micrometers of enamel thickness was reduced from each proximal surface. The teeth were randomly divided into 5 groups: group 1 (control un-demineralized) received no treatment, group 2 (control demineralized) had their surfaces demineralized after the IPR procedure, group 3 (fluoride) specimens were treated with fluoride gel (NUPRO, DENTSPLY, Charlotte, NC, USA) after the IPR, group 4 (Icon) resin infiltration material (Icon Proximal Mini Kit, DMG, Bielefeld, Germany) was applied after IPR, group 5 (MI varnish) specimens were treated with Casein phosphopeptide-amorphous calcium phosphate (CPP-ACP) containing varnish (MI Varnish, G.C, USA, St. Alsip, IL, USA) after the IPR. The specimens in (groups 2-5) were stored in a 4.5 pH demineralization solution for 4 days. The trans-micro-radiography (TMR) technique was conducted to evaluate the mineral loss (∆Z) and lesion depth of all specimens after the acid challenge. The obtained results were analyzed statistically using a one-way ANOVA at a significance level of α = 0.05. The MI varnish recorded significant ∆Z and lesion depth values compared to the other groups p > 0.05. There was no significant difference in ∆Z and lesion depth between the control demineralized, Icon, and fluoride groups p < 0.05. The MI varnish increased the enamel resistance to acidic attack, and thus can be considered an agent capable of protecting the proximal enamel surface after IPR.

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

BackgroundThe 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.MethodsPre-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.ResultsThe 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.ConclusionA 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.

Interproximal Enamel Reduction (Stripping) Techniques in Orthodontic Treatment

Interproximal Enamel Reduction (Stripping) Techniques in Orthodontic Treatment

Evaluation of the enamel nano-topography influenced by different techniques of interproximal reduction: An atomic force microscopic study.

Interproximal enamel reduction is a part of the orthodontic treatment as a method of space generation in addition to other vast indications. Some studies found that different techniques might impose changes to the enamel surface that alter its topography, which in turn might influence its integrity and susceptibility to caries. Polishing, however, after this procedure is thought to be helpful to reduce these adverse effects. To evaluate the nano-topography of the enamel surfaces after interproximal reduction (IPR) and determine its influence on enamel surface roughness and examine the need for polishing to minimise these influences, when combined with topical fluoride application. A total of 60 proximal surfaces of 40 extracted maxillary premolars (10 premolars left unprepared as the control group) were reduced with different stripping instruments (discs, burs and manual strip system). The surface roughness of enamel was analysed with an atomic force microscope to determine the results quantitatively as well as qualitatively on the nanoscopic scale. One of each proximal surface was followed by polishing and fluoride varnish after the reduction. The results showed that surface roughness was increased in all groups without polishing. The greatest mean roughness was recorded for the disc group (212 ±125.7), followed by the bur group (172 ±93.1) and manual strips (153.8±106.7). The difference between the groups, however, was not significant for both mean roughness (P = 0.656) and height (P = 0.737). The parameters were decreased after polishing in all groups but the difference between methods was not significant for both parameters (P = 0.946 and P = 0.849); however, the mean height was reduced to nearly half the reading in the bur and manual strip method. The disc group only showed a statistically significant decrease in surface roughness with polishing (P < 0.05). All other results were not significant. All methods of interproximal reduction do not influence enamel surface nanotopography significantly with and without polishing. Polishing resulted in significant reduction of surface roughness only in the disc group.

Proximal enamel thickness quantification in orthodontics for interproximal reduction: A systematic review

Background: Interproximal enamel reduction is a valuable procedure in orthodontics used in several conditions, however, not knowing the average value of proximal enamel thickness might lead to excess enamel removal and consequently to adverse effects.&#x0D; Objective: The objective of this systematic review is to expose the average proximal enamel thicknesses found in the literature, and the differences that might be found between different ethnicities and age groups.&#x0D; Search Methods: 5 electronic databases were used to perform the search. Representative keywords comprised of “enamel”, “thickness”, “orthodontics” “proximal thickness” and “quantification”; different combination of these keywords with truncation, and medical subject headings (MESH) were used.&#x0D; Selection Criteria: In vitro and in vivo studies, where the quantification of the proximal enamel thickness of the mesial and distal sides were evaluated independently.&#x0D; Data Collection and Analysis: The PICO model was used to evaluate and select the in vitro and in vivo studies. ROBINS-I tool was used to assess the risk of bias of non-randomized clinical studies and a modification of Cochrane risk of bias tool was implemented for the in vitro studies. The quality of evidence and results were evaluated using The Joanna Briggs Institute (JBI) Critical Appraisal checklist tools for Quasi-Experimental Studies.&#x0D; Results: Literature search identified 3298 records from 5 databases. Ultimately, nine eligible studies were included in the review.&#x0D; Conclusions: The proximal enamel thickness increases as we move distal through the arch and is greater on the distal side compared to the mesial side of each individual tooth. Additionally, there is no difference in the proximal enamel thickness between genders but there is between ethnicities.

Effects of interproximal enamel reduction techniques used for orthodontics: A systematic review.

This systematic review aimed to determine the effects of the interproximal enamel reduction (IPR) techniques used in orthodontics. Six databases were searched: PubMed, Scopus, Web of Science, Dentistry & Oral Sciences Source, ScienceDirect and Clinical Trials. Grey literature was sourced from Google Scholar. The risk of bias was assessed by Risk of Bias 2, Newcastle-Ottawa Scale and Robins-I depending on the design of the evaluated study. Additionally, the quality of the included studies was determined using Grading of Recommendations Assessment, Development and Evaluation (GRADE) criteria. This systematic review included randomized clinical trials, non-randomized clinical trials and observational studies with a control group that reported the effects of IPR for orthodontic purposes on the teeth and periodontium. Case reports, and in vitro and in vivo studies were excluded. Eight clinical studies match the eligibility criteria. As a result, no demineralization of the enamel, no increase in caries incidence, no periodontal changes or dental sensitivity was found after IPR. Also, considering the duration of orthodontic treatment, IPR resulted in a quicker technique than dental extractions. At the risk-of-bias assessment, all observational studies showed low risk, the non-randomized clinical trial had a critical bias, and all randomized clinical trials exhibited some concerns. The overall quality of the studies was found to be between low and very low. After the analysis of the data from included studies, it was concluded that the IPR procedures could be useful to treat dental crowding in orthodontic clinical practice without negative effects. However, more randomized controlled clinical trials with a longer follow-up time and high-quality studies are required to generate robust statements.

Guidelines for clear aligner orthodontic treatment (2021)

The content of the guidelines is based on monographs and literatures on the clear aligner orthodontic treatment in the past five years, and the clinical consensus of all the members of Expert Group for Writing Project of Clear Aligner Technology. This guidelines provide guidance and reference for orthodontists who want carry out clear aligner orthodontic treatment in three parts: overview, diagnosis and design, and common treatment strategies. In the part of the overview, the instructions for the preparation of this guide were described. The requirements for practitioners providing clear aligner orthodontic treatment were put forward, and the risks associated with clear aligner orthodontic treatment were suggested. In the part of diagnosis and design, the indications and selection of clear aligner orthodontic treatment were defined. The requirements of collecting data in orthodontic cases and the design process of clear aligner orthodontic treatment were also explained. The present common treatment strategies for clear aligner orthodontic treatment were summarized in the third part of the guidelines. The elaboration of the treatment methods such as distalization of molar, interproximal enamel reduction and stepwise tooth movement were explained.

Predictability of rotational tooth movement with orthodontic aligners comparing software-based and achieved data: A systematic review and meta-analysis of observational studies.

Objective:To evaluate all available evidence on the prediction of rotational tooth movements with aligners.Data sources:Seven databases of published and unpublished literature were searched up to 4 August 2020 for eligible studies.Data selection:Studies were deemed eligible if they included evaluation of rotational tooth movement with any type of aligner, through the comparison of software-based and actually achieved data after patient treatment.Data extraction and data synthesis:Data extraction was done independently and in duplicate and risk of bias assessment was performed with the use of the QUADAS-2 tool. Random effects meta-analyses with effect sizes and their 95% confidence intervals (CIs) were performed and the quality of the evidence was assessed through GRADE.Results:Seven articles were included in the qualitative synthesis, of which three contributed to meta-analyses. Overall results revealed a non-accurate prediction of the outcome for the software-based data, irrespective of the use of attachments or interproximal enamel reduction (IPR). Maxillary canines demonstrated the lowest percentage accuracy for rotational tooth movement (three studies: effect size = 47.9%; 95% CI = 27.2–69.5; P < 0.001), although high levels of heterogeneity were identified (I2: 86.9%; P < 0.001). Contrary, mandibular incisors presented the highest percentage accuracy for predicted rotational movement (two studies: effect size = 70.7%; 95% CI = 58.9–82.5; P < 0.001; I2: 0.0%; P = 0.48). Risk of bias was unclear to low overall, while quality of the evidence ranged from low to moderate.Conclusion:Allowing for all identified caveats, prediction of rotational tooth movements with aligner treatment does not appear accurate, especially for canines. Careful selection of patients and malocclusions for aligner treatment decisions remain challenging.

Enamel interproximal reduction during treatment with clear aligners: digital planning versus OrthoCAD analysis

BackgroundThe aim of the study was to compare the amount of interproximal enamel reduction (IPR) provided on ClinCheck software with the amount of IPR carried out by the orthodontist during treatment with clear aligners.Methods30 subjects (14 males, 16 females; mean age of 24.53 ± 13.41 years) randomly recruited from the Invisalign account of the Department of Orthodontics at the University of Rome “Tor Vergata” from November 2018 to October 2019, were collected according to the following inclusion criteria: mild to moderate dento-alveolar discrepancy (1.5–6.5 mm); Class I canine and molar relationship; full permanent dentition (excluding third molars); both arches treated only using Comprehensive Package by Invisalign system; treatment plan including IPR. Pre- (T0) and post-treatment (T1) digital models (.stl files), created from an iTero scan, were collected from all selected patients. The OrthoCAD digital software was used to measure tooth mesiodistal width in upper and lower arches before (T0) and at the end of treatment (T1) before any refinement. The widest mesio-distal diameter was measured for each tooth excluding molars by “Diagnostic” OrthoCAD tool. The total amount of IPR performed during treatment was obtained comparing the sum of mesio-distal widths of all measured teeth at T0 and T1. Significant T1–T0 differences were tested with dependent sample t-test (P < 0.05).ResultsIn the upper arch, IPR was digitally planned on average for 0.62 mm while in the lower arch was on average for 1.92 mm. As for the amount of enamel actually removed after IPR performing, it was on average 0.62 mm in the maxillary arch. In the mandibular arch, the mean of IPR carried out was 1.93 mm. The difference between planned IPR and performed IPR is described: this difference was on average 0.00 mm in the upper arch and 0.01 in the lower arch.ConclusionsThe amount of enamel removed in vivo corresponded with the amount of IPR planned by the Orthodontist using ClinCheck software.

A Novel Digital Technique to Quantify the Area and Volume of Enamel Removal after Interproximal Enamel Reduction

The aim of this study was to show a novel and accurate digital measurement protocol by analyzing the area and volume for interproximal tooth enamel surface reduction. In total, 14 lower teeth from all dental sectors were embedded into an epoxy resin and distributed as the lower dental arch, keeping the contact points. The experimental model was submitted to an intraoral digital impression before and after interproximal tooth enamel surface reduction using air-rotor strips and then re-contouring and polishing the interproximal enamel surfaces. These steps helped obtain standard tessellation language (STL) digital files. Furthermore, each tooth in the preoperative and postoperative full-arch STL digital files was segmented individually and aligned to analyze the area and volume of the interproximal tooth enamel surface reduction using engineering morphometry software. Descriptive analysis of the area and volume of the interproximal tooth enamel surface reduction was performed using a Student t-test. Higher enamel reduction area (3.53 ± 3.08 mm2) and volume (0.32 ± 0.22 mm3) values were shown on the distal surface compared with the area (2.97 ± 3.05 mm2) and volume (0.22 ± 0.16 mm3) of the enamel reduction on the mesial surface measured using the morphometric measurement digital protocol. The morphometric measurement protocol is an accurate digital measurement protocol for analyzing the area and volume of interproximal enamel surface reduction.