Assessment of interproximal enamel reduction planned by the digital set-up of a customized lingual orthodontic appliance: A comparison cohort study.

Objectives: Interproximal enamel reduction (IER), commonly known as stripping, is a frequently used technique in orthodontic treatment to address issues related to arch length discrepancies and tooth size discrepancies (TSD). The use of digital set-up allows for precise prediction of the amount of IER required. TSD occurs when the sizes of maxillary and mandibular teeth are not in proportion to each other. This study aims to evaluate and compare the suggested IER values generated by the digital set-up of a customized lingual orthodontic appliance in both upper and lower arches, across sextants, and among different teeth concerning TSD. Materials and methods: We analyzed suggested IER values from 809 cases. The statistical analysis was divided into two parts: part 1 focused on the number of stripped surfaces, and part 2 assessed the quantity of enamel removed. Comparisons were made between upper and lower arches, sextants, and teeth using the Friedman test, followed by pairwise Wilcoxon tests with Bonferroni correction. Results: The study found that mandibular and frontal stripping were more frequently suggested than maxillary and posterior stripping. Lower canines were the teeth most commonly recommended for stripping, followed by upper incisors. Conclusion: Within the scope and limits of this cohort study, we conclude that, in general, more IER is required in the mandible as compared to the maxilla. Particularly in the anterior sextants, IER might be necessary to achieve optimal alignment and occlusion.

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.

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

OBJECTIVES: 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. MATERIALS AND METHODS: 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. RESULTS: 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. CONCLUSIONS: 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.

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

BACKGROUND: To 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. RESULTS: Teeth 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. CONCLUSION: The 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.

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.

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

BACKGROUND: The incidence of open gingival embrasures (OGE) in patients after fixed appliance treatment is relatively high, while there are no detailed reports on patients after clear aligner therapy. Also, no clinical studies with large sample size have investigated whether interproximal enamel reduction (IPR) can actually avoid OGE. The purpose of this study was to determine the prevalence of OGE in adults after clear aligner therapy and to investigate the risk of OGE associated with IPR treatment and attachment design, focusing on the amount and distribution in mandibular anterior teeth. METHODS: Pre-treatment and post-treatment intraoral frontal photographs of 225 non-extraction patients were evaluated retrospectively for the occurrence and severity of OGE. The amount of IPR and the number of attachments in the anterior teeth from subjects after screening were recorded according to the first version of clear aligner software (Clincheck, San Jose, USA) and clinical medical documents. Logistic regression analysis was performed to identify the factors contributing to OGE. RESULTS: The incidence of OGE in non-extraction patients after clear therapy between maxillary and mandibular central incisors was 25.7% and 40.3%, respectively. IPR was not associated with the occurrence of OGE but was associated with severity (P < 0.05). The number of attachments in the anterior teeth or central incisors was significantly related to the incidence of OGE (P < 0.05) but was not associated with severity. CONCLUSION: A high rate of OGE occurs after clear aligner therapy. Clinicians should be aware of the application of IPR and the design of attachments during clear aligner therapy.

How does arch form and interproximal contact size affect the 3D displacements and rotations of teeth: a finite element analysis

ABSTRACT Objective: The objective of this study was to determine how arch form and interproximal contact size displace mandibular teeth subjected to an anterior component of force (ACF). Methods: Nine finite element models (FEM) of the mandibular arch were developed using Ansys® v. 16.0 software. They were designed to evaluate the effects of three arch forms (triangular, oval, and square) and three contact sizes (point-to-point, 1 mm diameter, and 2 mm diameter). All nine models were subjected to an ACF of 53.8 N (5486 gm). Three-dimensional tooth rotations and displacements of the mandibular teeth were evaluated, from the right first molar to the left first molar. Results: Arch form had a greater effect on tooth movements than contact size. Triangular arches and point-to-point contacts produced the greatest displacements and rotations of teeth. Oval arches with 2 mm wide interproximal contact points showed the greatest stability. The right first premolar showed the greatest displacements in all of the models. Conclusions: Arch form and contact size affect interproximal tooth stability. Teeth are least stable in narrow arches with point-to-point interproximal contacts, and most stable in wider arches with larger contacts.

RESUMO Objetivo: O objetivo deste estudo foi determinar como o formato da arcada e o tamanho do contato interproximal deslocam os dentes inferiores submetidos a um componente anterior de força (CAF). Métodos: Nove modelos de elementos finitos (MEF) da arcada inferior foram desenvolvidos utilizando o software Ansys® v. 16.0. Eles foram projetados para avaliar os efeitos de três formatos de arcada (triangular, oval e quadrado) e três tamanhos de contato interproximal (ponto a ponto, 1 mm de diâmetro e 2 mm de diâmetro). Todos os nove modelos foram submetidos a um CAF de 53,8 N (5486 gm). Foram avaliados tridimensionalmente as rotações dentárias e os deslocamentos dos dentes inferiores, do primeiro molar direito ao primeiro molar esquerdo. Resultados: A forma da arcada teve um efeito maior no movimento dos dentes do que o tamanho do contato interproximal. Arcadas triangulares e contatos ponto a ponto produziram os maiores deslocamentos e rotações dos dentes. Arcadas ovais com pontos de contato interproximal de 2 mm de largura apresentaram maior estabilidade. O primeiro pré-molar direito apresentou os maiores deslocamentos em todos os modelos. Conclusões: O formato da arcada e o tamanho do contato interproximal afetam a estabilidade dos dentes. Os dentes foram menos estáveis nas arcadas estreitas com contatos interproximais ponto a ponto, e mais estáveis nas arcadas mais largas com contatos maiores.

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.

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.

Evaluation of temperature rise in the pulp during various IPR techniques-an in vivo study.

BACKGROUND: Non-extraction treatment protocol has gained a lot of popularity over extraction for orthodontic treatment. Interproximal enamel reduction is one such method that makes it possible to do orthodontic treatment without extractions. This procedure, which can be done by various techniques, leads to a rise in the temperature of the pulp of the teeth. Previously, studies have been done which have evaluated the temperature changes inside the pulp chamber of extracted teeth, during interproximal enamel reduction. However, no documented literature exists that has evaluated these changes in the live pulp of the teeth whilst interproximal enamel reduction (IPR) is being performed. Therefore, this study aimed to evaluate the temperature changes inside the live pulp of the teeth during various interproximal enamel reduction techniques in vivo. AIMS: Evaluation of temperature rise in the pulp during various interproximal enamel reduction techniques, done in vivo. MATERIAL AND METHOD: The study was performed on patients for whom extraction of premolars had been advised for their orthodontic treatment. Fifty-one premolar teeth were randomly divided into three groups of IPR, i.e. using airotor and bur, handheld metal strip and orthodontic IPR kit (oscillating system). IPR was performed on the mesial and distal sides after access opening, temperature change was recorded during IPR and the readings were compared. The Shapiro-Wilk test was utilized for checking whether the data satisfied the requirement of normal distribution. RESULTS: The highest temperature rise was seen in group 1 in which interproximal enamel reduction was performed using airotor and bur. The minimum temperature rise was observed in group 2 in which interproximal enamel reduction was done using the handheld metal strip, whereas the temperature rise observed in group 3, in which interproximal enamel reduction was done using IPR kit, was between the range of group 1 and group 3. The temperature change was in the following order-group 1 (2.08 °C) > group 3 (1.22 °C) > group 2 (0.52 °C). CONCLUSION: None of the methods used to perform interproximal enamel reduction caused a temperature increase more than 5.5 °C, beyond which pulp necrosis may occur. Therefore, all three methods used in the study for IPR were found to be safe.

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.

[Measurement of proximal enamel thickness of 182 permanent teeth].

Objective: To measure the proximal enamel thickness (PET) at the mesial and distal contact areas of the permanent teeth and to provide a reference for interproximal enamel reduction (IPR). Methods: From May 2016 to February 2018, 182 isolated permanent teeth were collected and screened from patients who underwent extraction at Department of Oral and Maxillofacial Surgery, Capital Medical University School of Stomatology. These teeth were extracted for orthodontic purpose or due to severe periodontitis. The patients having teeth extracted were all Beijing residents, Han nationality, and aged (39.5±10.6) years. Ninety percent of the teeth came from patients under 50 years old. These teeth were classified according to different tooth type. The mesial and distal contact areas of these teeth were marked with fluid resin. The isolated teeth were scanned using micro-CT and the enamel thickness was measured and analyzed. The parameters measured included mesial PET (PETm), distal PET (PETd), the distance from mesial contact area to occlusal plane (CAm-OP), the distance from distal contact area to occlusal plane (CAd-OP), the distance from mesial contact area to the cementoenamel junction (CAm-CEJ), the distance from distal contact area to cementoenamel junction (CAd-CEJ) and tooth width (TWmd). Results: The PET gradually increased from the anterior tooth area [(0.63±0.16) mm] to the molar area [(1.46±0.25) mm]. The sum of the PET from the second molar to the contralateral second molar in the maxillary dentition was 31.60 mm, and that of the PET from the second molar to the contralateral second molar in the mandibular dentition was 29.68 mm. The contact areas were located on the occlusal third of the proximal walls of anterior teeth and the middle third of the proximal walls of posterior teeth. The PET were positively correlated with the tooth width between the mesial and distal contact areas (P<0.05). Conclusions: The PET was thinner in the incisor area and thicker in the molar area. IPR should be carried out close to the occlusal side of the proximal walls in anterior teeth and the cementoenamel junction side of the proximal walls in posterior teeth.

Comparison of the abrasive properties of two different systems for interproximal enamel reduction: oscillating versus manual strips.

BACKGROUND: The aim of the present investigation was to evaluate enamel reduction efficiency, abrasive property decay, and enamel effects between oscillating mechanical and manual systems for interproximal enamel reduction (IPR). METHODS: Three oscillating strips and three manual strips were tested on twelve freshly extracted premolars blocked in an acrylic cylinder pot by means of a material testing machine. Each strip underwent one test of 8 cycles (30 s each). Both abrasive tracks and teeth surfaces were qualitative evaluated before and after IPR by means of SEM analysis. Efficiency and abrasive property decay of both IPR systems were investigated by the amount of enamel reduction within the eight-cycle testing. Independent t-test was used to evaluate differences in variables between the two systems. RESULTS: Mechanical IPR system showed higher efficiency in terms of enamel reduction (p < 0.005) when compared with manual IPR system (0.16 mm and 0.09 mm, respectively). Quantity of removed enamel decreased throughout the 8 cycles for both systems. Less presence of enamel debris and detachment of abrasive grains were observed on mechanical strips rather than manual strips. SEM analysis revealed more regular surface of teeth undergone mechanical IPR procedures. CONCLUSION: Oscillating diamond strips showed more controlled efficiency when compared with the manual IPR system leading to a more regular enamel surface.

In vitro and in vivo evaluation of diamond-coated strips.

OBJECTIVE: To test in vitro and in vivo the wear performance of diamond-coated strips by means of tribological testing and scanning electronic microscope (SEM). MATERIALS AND METHODS: To evaluate the in vitro wear performance, a tribological test was performed by a standard tribometer. The abrasive strips slid against stationary, freshly extracted premolars fixed in resin blocks, at a 2-newton load. At the end of the tribological test, the residual surface of the strip was observed by means of SEM analysis, which was performed every 50 meters until reaching 300 meters. For the in vivo analysis, the strip was used for 300 seconds, corresponding to 250 meters. RESULTS: The strips presented a fenestrated structure characterized by diamond granules alternating with voids. After the first 50 meters, it was possible to observe tooth material deposited on the surface of the strips and a certain number of abrasive grains detached. The surface of the strip after 250 meters appeared smoother and therefore less effective in its abrasive power. After 300 seconds of in vivo utilization of the strip, it was possible to observe the detachment of diamond abrasive grains, the near absence of the grains and, therefore, loss of abrasive power. CONCLUSIONS: Under ideal conditions, after 5 minutes (30 meters) of use, the strip loses its abrasive capacity by about 60%. In vivo, a more rapid loss of abrasive power was observed due to the greater load applied by the clinician in forcing the strip into the contact point.

Influence of Invisalign treatment with interproximal enamel reduction (IER) on bone volume for adult crowding: a retrospective three-dimensional cone beam computed tomography study.

BACKGROUND: The aim of this study was to use three-dimensional datasets to identify associations between treatment for adult crowding using Invisalign and interproximal enamel reduction (IER) and changes in the bone volume. METHODS: A total of 60 digital cone beam computed tomography (CBCT) scans from 30 patients (28 women, two men; 30 CBCTs pretreatment, 30 posttreatment) were examined retrospectively in order to record bone volume three-dimensionally before and after treatment. The patients' average age was 36.03 ± 9.7 years. The data were collected and analyzed using the computer programs Mimics 15.0 and OsiriX. Differences in bone between T0 and T1 were analyzed with IBM SPSS 21.0 using the Wilcoxon test for paired samples. RESULTS: Analysis of the orovestibular bone volume showed highly significant changes (bone change P <0.001) only in the mandible where more expansion of the dental arch was carried out using proclination or protrusion. The bone lamella was thinner buccally and thicker lingually. In general, bone increases in the oral direction were slightly greater than bone losses in the vestibular direction. No significant changes were detected in the maxilla (bone change P = 0.13). Significant vertical bone loss in the bone height was detected in both the maxilla and the mandible. The largest bone loss was observed in the vestibular direction in the mandible, at a high level of significance (P <0.001). CONCLUSIONS: Particularly in the mandible, therapeutic reduction of the vertical and sagittal bone volume shows that caution should be used in the treatment of tertiary crowding with proclination and expansion. The cortical walls appear to represent the limits for orthodontic tooth movement, at least in adult female patients.

Efficiency of powered systems for interproximal enamel reduction (IER) and enamel roughness before and after polishing-an in vitro study.

OBJECTIVE: This aims to evaluate the efficiency of three different powered interproximal enamel reduction (IER) systems and to assess enamel roughness before and after polishing using different polishing times. MATERIAL AND METHODS: Four metal strips of the G5 ProLign Set (swissdentacare, SDC, Grancia, Switzerland), four segmental discs of the ASR-Set 4594 and two sonic tips of the SonicLine Set (both Gebr. Basseler GmbH & Co. KG, Komet, Lemgo, Germany) were evaluated. Human extracted incisors served as the medium. Enamel reduction was determined in five intervals of 15 s each. Polishing was performed for 15 and 30 s using the manufacturers' recommended polishing systems. Enamel roughness (Ra) was quantitatively assessed by confocal laser scanning microscopy (CLSM). RESULTS: Significant differences in terms of enamel reduction were found among the working ends of all tested systems. The time needed to remove 0.1, 0.2 and 0.3 mm of enamel was determined. Surface analysis showed significantly higher mean Ra values for nine out of ten working ends before polishing. This was still the case for five working ends after 15 s and for two after 30 s of polishing. CONCLUSION: The graining and the system used have a significant influence on enamel reduction. The time needed for polishing depends on the last working end used; a polishing time of 30 s is not always appropriate. CLINICAL RELEVANCE: Knowledge about the cutting efficiency of powered IER working ends might help the clinician to estimate better the amount of enamel reduction during the stripping process.

Enamel roughness and incidence of caries after interproximal enamel reduction: a systematic review.

The aim of this study was to investigate the effect of interproximal enamel reduction (IER) on tooth surfaces regarding the level of enamel roughness after applying different IER methods and the caries risk of treated teeth. Seven electronic databases were systematically searched. Two independent reviewers rated the articles at every step according to predetermined eligibility criteria. Data on enamel roughness were pooled if the same IER method was used and arithmetic values were available. Data on occurrence of caries were suitable for the analysis if the same units for caries development were used. From 2396 citations initially identified, 18 articles met the inclusion criteria and were further considered (14 studying enamel roughness and four studying the risk of caries after IER). A meta-analysis of quantitative data regarding enamel roughness was not possible due to statistical heterogeneity; instead, the enamel roughness findings are only described. The meta-analysis of studies focusing on the incidence of caries revealed no statistical difference between treated and untreated enamel surfaces (p = NS) from 1 to 7 years after IER. Drawing reliable conclusions on enamel roughness after IER is difficult owing to the diversity of the available studies. Statistically, the occurrence of caries on surfaces previously treated with IER was the same as that on intact surfaces, indicating that IER does not increase the risk of caries on treated teeth.

Enamel reduction techniques in orthodontics: a literature review.

Artificial abrasion of interproximal surfaces has been described for almost seventy years as orthodontic intervention for achievement and maintenance of ideal treatment outcome. A variety of terms and approaches have been introduced throughout this period implying a growing clinicians' interest. Nevertheless, the widespread recognition of enamel stripping technique was initiated by the advent of bonded orthodontic attachments and a 2-article series of Sheridan in the 80's. Since then, experimental and clinical research has been focused on the investigation of instrumentation efficacy and potential iatrogenic sequelae related to interproximal stripping. This review discusses the evolution, technical aspects and trends of enamel reduction procedures as documented in the literature.

Redução de esmalte interproximal como alternativa no tratamento ortodôntico de casos limítrofes: [revisão] / Interproximal enamel stripping as orthodontic treatment alternative in borderline cases: [review]

INTRODUÇÃO: o plano de tratamento ortodôntico deve considerar fatores como apinhamento dentário, protrusão dentoalveolar, discrepâncias maxilares e necessidade de alteração do perfil facial. Também se deve ter em mente as características de normalidade conforme a raça do paciente. Assim, buscando uma abordagem individual do paciente, em casos limítrofes, a terapia ortodôntica pode ser realizada com ou sem extrações. OBJETIVO: realizar uma revisão da literatura sobre a terapia de redução de esmalte interproximal como uma alternativa de tratamento ortodôntico sem extrações para pacientes considerados limítrofes e exemplificar a técnica a partir do relato de um caso clínico. MÉTODOS: para a execução da redução, usou-se brocas Carbide em alta rotação para a remoção do esmalte, discos Sof-Lex para o acabamento e polimento das superfícies desgastadas e aplicação tópica de fluoretos, visando aumentar a proteção do esmalte. CONCLUSÃO: concluiu-se que a técnica é indicada na resolução de discrepâncias no comprimento do arco dentário de até 8,5mm, a fim de evitar as extrações dentárias em pacientes com bom perfil facial. Preferencialmente, os dentes submetidos à técnica devem ser largos, com forma triangular e paredes de esmalte espessas.

INTRODUCTION: The orthodontic treatment plan must consider factors like dental crowding, dental alveolar protrusion, maxillary discrepancies and the facial profile change necessity. It must be considered that the normal characteristics changes in conformity with the ethnic origin of the patient. Then, searching for the individualization of treatment for each patient, in borderlines cases the orthodontic therapy can be done with or without extractions. AIM: To review the literature about the interproximal enamel reduction therapy as an orthodontic treatment alternative to extractions in this borderline patients and to exemplify the technic with a case report. METHODS: To execute the enamel reduction it was used the high-speed Carbide bur and Sof-Lex discs to polish the striped surfaces, followed by topic application of fluoride to increase enamel protection. CONCLUSION: Technic is indicated to solve discrepancies in the dental arch smaller than 8,5mm, to avoid extractions in patients with good facial profile. It's mandatory that the teeth to be striped must be large, triangular and with thick proximal enamel layers.