Inter-proximal enamel reduction in contemporary orthodontics

Interproximal reduction in the refinement phase of Invisalign treatment: A quantitative analysis

INTRODUCTION

Interproximal reduction (IPR) is a common adjunct to contemporary orthodontic treatment. This study aimed to carry out a quantitative analysis of IPR prescribed in the refinement phases of clear aligner therapy with the Invisalign appliance (Align Technology, San Jose, Calif).

METHODS

The digital treatment plans (DTPs) of a total of 330 patients treated by 11 orthodontists were evaluated. Relevant data regarding patient age, gender, and prescription of IPR in the initial and refined DTPs were obtained from Align Technology's digital interface, ClinCheck. Computational analyses included descriptive statistics, Mann-Whitney U, and Kruskal-Wallis tests.

RESULTS

Most (n = 182; 75.2%) of the 242 patients who satisfied inclusion criteria were females. The median (interquartile range [IQR]) age was 29.2 (22.1-40.2) years. More than 60% of the contact sites prescribed IPR related to the initial DTP (n = 1312; 60.4%), with 39.6% (n = 859) recorded in the refinement DTPs. A median (IQR) of 1.1 (0.6-2.1) mm of IPR was prescribed per patient in the initial DTP compared with a median (IQR) of 0.6 (0.3-1.3) mm in the refinement DTPs. The most common site for prescribed IPR in all DTPs was the mandibular anterior region. Almost half (n = 108; 44.6%) of the patients were prescribed IPR at the same contact point site more than once during treatment.

CONCLUSIONS

Almost 40% of the contact points that were prescribed IPR were in the patients' refinement DTPs. Most IPR was prescribed for the anterior region of the mandible. Almost half of the patients had IPR repeatedly prescribed at the same sites during treatment.

Non-extraction Approach in a Borderline Case of a Growing Patient: A Case Report

This case presents the effective non-extraction orthodontic treatment of a 13-year-old boy with crowding in both upper and lower arches and deep bite. The patient's chief complaint was irregularly placed maxillary anterior teeth. The active treatment duration lasted for 10 months, which resulted in the successful alleviation of arch crowding and correction of the deep bite without the extraction of any sound erupted tooth. Posttreatment, all of the patient's chief complaints were relieved. Essix retainers were fitted post-debonding, with instructions for the patient to wear them for the subsequent year to maintain the achieved results. This case highlights the efficacy of non-extraction orthodontic strategies in addressing crowding and deep bite issues, drawing the importance of individualized treatment plans to achieve optimal outcomes.

A digitalized analysis of incisal changes among orthodontically treated patients: A retrospective comparative study

Background

To compare incisor angulation and/or position changes among orthodontically treated patients with metal brackets and clear aligners.

Methods

A total of sixty-two participants of both sexes, aged-16-40 years old, with CL I skeletal pattern and mild crowding following strict eligibility criteria were included. The patients were divided into two groups based on their treatment approach. Pre and post lateral cephalograms were collected from Riyadh Elm University (REU) and then digitally analyzed using WEBCEPH (Medical Image Analysis) software. Eight angular and two linear measurements were used for the assessment.

Results

The upper incisor angulation and position showed statistically significant differences when orthodontic clear aligners were used. In contrast, no significant difference was observed with the conventional orthodontic treatment. However, the upper incisal palatal root torque decreased after clear aligner therapy compared to conventional treatment. The inter-incisal angle demonstrated a significant increase with clear aligners compared to conventional treatment.

Conclusions

The current study revealed the importance of definitive guidelines upon and after treatment, in addition to determining incisor changes. Orthodontic clear aligners are distinct from conventional treatments in controlling the incisors' angulation and position. The expansion treatment modality precedes Interproximal reduction in increasing the arch perimeter.

The Role of Interproximal Reduction (IPR) in Clear Aligner Therapy: A Critical Analysis of Indications, Techniques, and Outcomes

Interproximal reduction (IPR) has become a standard practice in orthodontic treatment, particularly in the clear aligner therapy. It became an integral part of the digital plan when using clear aligners. Given the irreversible nature of IPR, precise planning and performance is essential. This article aims to analyze and summarize the existing literature on IPR in the context of clear aligners. The goal is to help clinicians to gain essential knowledge for safely and effectively navigating IPR. The review critically examines different perspectives found in the literature, covering indications, methods, and outcomes. Topics exploring the impact of IPR on treatment outcomes include space gaining, addressing tooth size discrepancies, tooth shape adjustments, resolving malocclusion, and enhancing aesthetics. Emphasizing precision of the procedure by the clinician and awareness of contraindications, the article also discusses the impact of IPR on patients. This includes considerations like increased pulp temperature, susceptibility to cavities due to changes in enamel roughness, effects on soft tissues, and post-IPR tooth sensitivity.

Does surface enamel composition and characteristics vary with inter proximal enamel reduction?

OBJECTIVE

This study aimed to evaluate the chemical composition of the proximal enamel surface and the surface characteristics subjected to different extents of interproximal reduction (IPR) in a clinical setting.

MATERIALS AND METHODS

Premolars of orthodontic patients which were designated for extraction were subjected to .2 mm, .3 mm, and .5 mm of IPR. After 1 month, the teeth were extracted and the teeth were subjected to scanning electron microscope (SEM) and energy-dispersive x-ray spectroscopy (EDX).

RESULTS

The SEM images of the three experimental groups (taken at magnification of 500 × and 2000 ×) showed that the enamel surfaces were irregular and rough compared to the honey comb appearance of the unstripped group. Small areas of erosion of enamel surface were seen in Group I (0.2 mm) under 2000 × magnification compared to Group IV (control) which showed typical arrangement of enamel rods in alternating orientation. The enamel surfaces of stripped and unstripped enamel contained calcium, phosphorus, carbon, oxygen, and nitrogen. The differences were not statistically significant and neither were the calcium phosphorous stoichiometric ratios between the four groups.

CONCLUSIONS

On analyzing the surface characteristics of enamel using SEM between the stripped and unstripped surfaces, there were irregularities and roughness seen in stripped surface whereas honey comb pattern was observed in unstripped enamel surfaces. The elements found in unstripped and stripped enamel surfaces were calcium, phosphorous, carbon, oxygen, and nitrogen. Although the calcium and phosphorus were high in the 0.5 mm IPR group, the difference between stripped and unstripped enamel surfaces was statistically not significant.

CLINICAL RELEVANCE

There have been concerns that IPR can remove the superficial mineral-rich layer making the deeper layers more susceptible to carious attack. No study has evaluated the mineral content in different layers of enamel in response to IPR in vivo and this study found no significant difference between pristine enamel and enamel subjected to IPR. The results of this study strengthen the validity of the clinical protocol employed.

Interproximal Reduction Facilitating Orthodontic Teeth Extraction

Extractions are routinely performed in orthodontics to gain space for teeth alignment. Crowded, malaligned, and overlapped teeth make it difficult for the dental surgeon to engage the beaks of the extraction forceps on the concerned tooth for extraction. An improper grip often leads to complications of instrument slippage, crown fracture, and more commonly, luxation of adjacent teeth. This article aims to help with atraumatic orthodontic extractions and reduce such complications. This case report examines an interproximal reduction technique using standard grit, taper, flat-end diamond bur (Mani TF-20, ISO 171/014, Mani, Inc., Tochigi, Japan) for the tooth to be extracted to create enough space for proper placement of the forceps and to prevent injury to adjacent structures. It can be useful for orthodontic extractions or other cases of tooth extractions with inadequate access.

Effect of Interdental Enamel Reduction on Clinical Attachment Loss, Bleeding on Probing, and Incidence of Caries in Treating Class I Malocclusion Cases: A Retrospective Cohort Study

Introduction Interdental Enamel Reduction (IER) is a clinical procedure that reduces the mesiodistal size of permanent teeth by enamel removal and anatomical re-contouring. The aim of this study was to investigate the effect of IER on patients' gingival health status, including clinical attachment loss (CAL) and bleeding on probing (BOP). Furthermore, in this study, the incidence of caries after IER with or without fluoride therapy was evaluated. Methods In this retrospective cohort study, 90 patients who had started and completed their orthodontic treatment within the past two years were divided into three groups as follows: In group 1, patients had received interproximal stripping on their anterior mandibular teeth. Patients in group 2 had also received interproximal stripping on their mandibular anterior teeth and topical fluoride had been applied after IER. Patients in group 3 had only received orthodontic treatment without any interproximal stripping. Then, patients were examined for CAL, BOP, and incidence of caries. Results CAL for patients in the IER and control groups were 2.06±0.18 and 2.08±0.16, respectively. Also, BOP for patients in the IER and control groups were 3.01±0.14 and 3.05±0.19, respectively. Incidences of caries, BOP, and CAL were not significantly different between the group of patients who received IER and the control group (P>0.05). Moreover, the incidence of caries was not significantly different between the patients who received topical fluoride after IER and those who did not receive fluoride (P=0.999). Conclusion Interproximal stripping of mandibular anterior teeth before orthodontic treatment does not significantly increase the incidence of caries, BOP, and CAL. Moreover, the application of topical fluoride after IER has no significant effect on the incidence of caries.

The effectiveness of adjuncts or alternatives to the use of orthodontic retainers in preserving posttreatment outcomes: A systematic review

INTRODUCTION

The objective of this study was to systematically evaluate the efficacy of adjuncts or alternatives to mechanical retention in preserving postorthodontic treatment outcomes.

METHODS

Electronic databases, unpublished literature, and ongoing trials were searched until July 22, 2022 (PROSPERO CRD42021291165). Randomized and nonrandomized controlled trials investigating the efficacy of adjuncts and alternatives to conventional orthodontic retainers were included. Stability, periodontal effects, cost-effectiveness, and patient-reported outcomes were to be evaluated. The Cochrane Risk of Bias Tool and Risk of Bias In Nonrandomized Studies of Interventions (ROBINS-I) were used for risk of bias assessment. The certainty of the evidence was appraised using the Grading of Recommendations Assessment, Development, and Evaluation system. Exploratory sensitivity analysis was undertaken to calculate the weighted treatment effects of the intervention.

RESULTS

A total of 5128 records were screened. Seven trials fulfilled the inclusion criteria, of which 5 were randomized controlled trials. Five trials were judged to be at high risk of bias, with 2 studies of unclear risk of bias. Heterogeneity between the limited number of included studies precluded the conduct of meta-analysis. Circumferential supracrestal fibrotomy resulted in less increase in the mandibular Little's Irregularity Index (mean difference, -2.30 mm; 95% confidence interval, -2.86 to -1.74). The overall level of evidence was of very low quality.

CONCLUSIONS

Adjuncts and alternatives to mechanical retention have promise, but based on the existing evidence, the reliance on mechanical retention cannot be reduced. There is weak evidence supporting circumferential supracrestal fibrotomy to improve stability outcomes. Further high-quality prospective research focusing on the predictability and acceptability of these approaches is needed.

Evaluation of interproximal reduction in individual teeth, and full arch assessment in clear aligner therapy: digital planning versus 3D model analysis after reduction

Aim

To evaluate the correspondence between the interproximal reduction (IPR) performed clinically and that programmed in ClinCheck® and further assess which teeth showed an amount of implemented IPR (I-IPR) that corresponds with that programmed in ClinCheck®.

Materials and methods

Pre- (T0) and post-treatment (T1) ClinCheck® digital models for 75 subjects (30 males and 45 females), mean age (38 ± 15) years, were included. To calculate the amount of I-IPR, Ortho Analyzer software (3Shape, Copenhagen, Denmark) was used to measure the mesiodistal widths for the maxillary and mandibular teeth from second premolar to the contralateral second premolar on the initial (T0) and final (T1) STL models. I- IPR performed by tooth was obtained by comparing the mesiodistal width of each tooth at T0 and T1. The amount of programmed IPR (P-IPR) in ClinCheck® was compared to that implemented clinically using the following formula: IPR difference = (P-IPR) − (I-IPR).

Results

Statistically significant differences were observed between the average value of digitally programmed and implemented IPR per tooth for both the maxillary (p < .0001) and mandibular (p < .0001) teeth. The mean P-IPR for the maxillary teeth was 0.28 ± 0.16 mm versus the mean I-IPR of 0.15 ± 0.15 mm. In the mandibular arch, the mean P-IPR was 0.31 ± 0.17 mm, while the I-IPR was 0.17 ± 0.16 mm. The mean I-IPR was consistently lower than the mean P-IPR regardless of teeth and sites (p < 0.0001). The difference between the P-IPR compared to the I-IPR was larger for mandibular anterior teeth than for maxillary anterior teeth (p = 0.0302) and larger for maxillary posterior teeth than mandibular posterior teeth (p = 0.0059).

Conclusion

The amount of implemented-IPR in clear aligner therapy is less than that digitally programmed for most teeth. Regardless of the regions, I-IPR was consistently lower than that programmed. Mandibular anterior teeth and maxillary posterior teeth showed greater discrepancy between P-IPR and I-IPR than the maxillary anterior and mandibular posteriors. Further prospective studies are needed to determine the factors affecting the precision of IPR and the clinical implications of a significantly reduced I-IPR on treatment outcomes.

The rationale for orthodontic retention: piecing together the jigsaw

Retaining teeth in their corrected positions following orthodontic treatment is one of the most challenging aspects of orthodontic practice. Despite much research, the rationale for retention is not entirely clear. Teeth tend to revert to their pre-treatment positions due to periodontal and gingival, soft tissue, occlusal and growth factors. Changes may also follow normal dentofacial ageing and are unpredictable with great variability. In this overview, each of these factors are discussed with their implications for retention, along with adjunctive procedures to minimise relapse. The state of current knowledge, methods used to assess relapse, factors regarded as predictive of or associated with stability as well as overcorrection are outlined. Potential areas requiring further investigation are suggested. The way in which the clinician may manage current retention practice, with a need for individualised retention plans and selective retainer wear, is also considered.

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

BACKGROUND

The 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.

METHODS

30 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).

RESULTS

In 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.

CONCLUSIONS

The amount of enamel removed in vivo corresponded with the amount of IPR planned by the Orthodontist using ClinCheck software.

Distalization in Orthodontics: A Review and Case Series

Distalization is a conservative method that is utilized in orthodontics to gain space by moving posterior teeth distally. It may be combined with other space gaining strategies, such as expansion, or can be used alone. Many methods have been used for distalization. These methods differ significantly in their place, whether to be extraoral or intraoral, site of action in upper and/or lower arch, and cooperation needed by the patient if it is removable or fixed. This review illustrates some of the most commonly used methods for distalization with a brief presentation of three cases that incorporated successful distalization techniques.

Quantitative evaluation of implemented interproximal enamel reduction during aligner therapy

OBJECTIVES

To investigate the correspondence between programmed interproximal reduction (p-IPR) and implemented interproximal reduction (i-IPR) in an everyday-practice scenario. The secondary objective was to estimate factors that might influence i-IPR to make the process more efficient.

MATERIALS AND METHODS

Fifty patients treated with aligner therapy by six orthodontists were included in this prospective observational study. Impressions were taken at the beginning of treatment and after the first set of aligners. Data on p-IPR, i-IPR and technical aspects of IPR were gathered for 464 teeth. Statistical analyses included the Wilcoxon signed-rank test, Kruskal-Wallis, and multilevel mixed regression.

RESULTS

Mean difference between p-IPR and i-IPR was 0.15 mm (SD: 0.14 mm; P = .0001), with lower canines showing the highest discrepancy. Use of burs and measuring gauges resulted in a smaller difference (respectively: coeff.: 0.09, P = .029; coeff.: -0.06, P = .013). IPR was performed more accurately on the mesial surface of teeth than on the distal surface. Round tripping before IPR resulted in a slightly more precise i-IPR compared to the previous alignment (coeff.: -0.021, P = .041).

CONCLUSIONS

Implemented IPR tends to be less than p-IPR, especially for lower canines and distal surfaces of teeth. Burs tend to provide more precise i-IPR, especially compared to manual strips; however, there is variation between the techniques. Using a measuring gauge tends to increase the precision of i-iPR. As several factors influence the implementation of IPR, particular attention must be paid during the procedure to maximize its precision.

Dissipating tooth-mass discrepancy caused by a set of mandibular incisor anomalies

Dental anomalies are complicating factors of orthodontic treatment, especially when 1 or more anterior teeth are affected. In this case report, a girl, aged 12.5 years with a retrognathic chin; number, size, and position anomalies of the mandibular incisors; and bilateral Class I molar relationship sought orthodontic treatment. Tooth-size ratio discrepancy was dissipated without extraction or prosthetic rehabilitation, and the initial molar relationship was maintained, as well as the straight soft tissue profile. Tipping of maxillary and mandibular incisors, crown torque of canines, restoration of anomalous incisor, and maxillary interproximal enamel reduction were key points for successful treatment. After 18 months, the orthodontic records showed stable results, excellent static and functional occlusion, and good smile esthetics and facial appearance, in addition to a high degree of patient satisfaction with the achieved results.

Accuracy of interproximal enamel reduction during clear aligner treatment

Aim

The aim of the present study was to compare the accuracy of the actual space obtained through interproximal enamel reduction (IPR) compared to the amount of IPR planned through the digital setup during clear aligner treatment (CAT).

Materials and methods

A total of 10 clinicians were randomly recruited using the Doctor Locator by Align Technology (California). For each clinician, four consecutive patients treated with CAT and manual stripping were selected for a total of 40 subjects and 80 dental arches. For each patient, the amount of planned IPR and the amount of actual IPR performed were recorded. Each arch was considered individually. For each arch, the mesio-distal tooth measurements were obtained from second to second premolars.

Results

No systematic measurement errors were identified. In 25 cases, stripping was planned and performed in both arches; in 4 cases only in the upper arch and in the remaining 7 cases only in the lower arch. The difference between planned IPR and performed IPR was on average 0.55 mm (SD, 0.67; P = 0.022) in the upper arch and 0.82 mm (SD, 0.84; P = 0.026) in the lower arch. The accuracy of IPR in the upper arch was estimated to be 44.95% for the upper arch and 37.02% for the lower arch.

Conclusion

Overall, this study showed that the amount of enamel removed in vivo did not correspond with the amount of IPR planned. In most cases, the performed IPR amount was lower than planned. When considering the actual amount in millimeter, these differences may not be considered clinically relevant.