Removal Of Orthodontic Brackets Research Articles

An In Vivo Study to Compare the Clinical Effectiveness of Clear Retainer Made on a Conventional and a Digitally Fabricated Model Over a Six-Month Period After Debonding.

Background With the advent of 3D printing, many more possibilities have arisen for treatment planning. 3D rapid prototyping has enabled us to see a whole other dimension that has helped us to give the best possible care for our patients. With more and more advancements being made in this subject, it becomes necessary to check the reliability of the equipment and its effectiveness in the management of the problem at hand. This original study was conducted with the aim of checking the accuracy, dimensional stability, and reliability of orthodontic retainers made on a conventional and digitally fabricated model over a six-month period after debonding. Material and methods The patients were selected from those who have completed fixed orthodontic mechanotherapy from the Department of Orthodontics and Dentofacial Orthopaedics, Sri Guru Ram Das Institute of Dental Sciences and Research, Sri Amritsar. Fifty patients received a clear retainer, which was fabricated for the upper and lower arch after removing the brackets. Patients were included in this study irrespective of their age groups.The manual method used a vacuum-forming machine to fabricate six retainers on stone models. In the digital method, new impressions were taken after three months, and digital models were obtained through 3D scanning and printing, followed by clear retainer fabrication. The data were gathered through a systematic process involving manual and digital methods for clear retainer fabrication and subsequent evaluation. The data obtained was computed for statistical evaluation and comparison. Results Mean and standard deviations of conventional (manual) and digital variables in the two groups were calculated. An ANOVA test was used to evaluate statistically significant differences for mesiodistal widthand buccolingual width, and a post hoc Tuckey test was applied for multiple comparisons. The results indicated that most mesiodistal and buccolingual width measurements showed non-significant variations and exhibited a good correlation. Extraction space opening, assessed through an independent t-test for both the maxilla and mandible, also yielded non-significant and comparable results. Additionally, intra-operator and inter-operator measurements using a digital caliper demonstrated high agreement. Intra-class correlation (ICC) values exceeded 0.75, and inter-operator ICC results reflected a high level of agreement ranging from 0.8 to 0.99. Conclusion The primary objective of this study was to establish a correlation between the accuracy, dependability, and clinical efficacy of orthodontic retainers produced using both conventional and digitally created models. This investigation spanned a duration of six months following the removal of orthodontic brackets. The results showed that most of the statistically significant values were due to the inherent potential of the 3D printer for polymerization shrinkage, which, being a stereolithographic 3D printer, had a potential for a slight dimensional shift in the transverse dimension. However, the mean difference between all the models printed was slight and clinically insignificant.

Deep learning for virtual orthodontic bracket removal: tool establishment and application.

We aimed to develop a tool for virtual orthodontic bracket removal based on deep learning algorithms for feature extraction from bonded teeth and to demonstrate its application in a bracket position assessment scenario. Our segmentation network for virtual bracket removal was trained using dataset A, containing 978 bonded teeth, 20 original teeth, and 20 brackets generated by scanners. The accuracy and segmentation time of the network were tested by dataset B, which included an additional 118 bonded teeth without knowing the original tooth morphology. This tool was then applied for bracket position assessment. The clinical crown center, bracket center, and orientations of separated teeth and brackets were extracted for analyzing the linear distribution and angular deviation of bonded brackets. This tool performed virtual bracket removal in 2.9ms per tooth with accuracies of 98.93% and 97.42% (P < 0.01) in datasets A and B, respectively. The tooth surface and bracket characteristics were extracted and used to evaluate the results of manually bonded brackets by 49 orthodontists. Personal preferences for bracket angulation and bracket distribution were displayed graphically and tabularly. The tool's efficiency and precision are satisfactory, and it can be operated without original tooth data. It can be used to display the bonding deviation in the bracket position assessment scenario. With the aid of this tool, unnecessary bracket removal can be avoided when evaluating bracket positions and modifying treatment plans. It has the potential to produce retainers and orthodontic devices prior to tooth debonding.

Effects of Maxillary Movements on Lips Following Orthognathic Surgery: A Retrospective Non-Randomized Clinical Trial.

Introduction Lips play a fundamental role in facial attractiveness and in decisions pertaining to orthognathic surgery. Objective To assess the upper lip changes following Le Fort I osteotomy for maxillary advancement and/or impaction. Methods In the present retrospective non-randomized clinical trial, we evaluated 3 groups of patients who underwent Le Fort I osteotomy of the maxilla. Group 1 (n = 35) underwent maxillary advancement, group 2 (n = 14), maxillary impaction, and group 3 (n = 11) was submitted to both maxillary advancement and impaction. The lip thickness of all patients was measured preoperatively, and the participants in each group were categorized into two subgroups: thin (< 12 mm) and thick (> 12 mm) lip. The primary (before orthognathic surgery) and final (after orthodontic bracket removal) lateral cephalograms of the patients were analyzed using the Dolphin software. Comparisons were made using the paired t -test and linear regression in the IBM SPSS Statistics for Windows software. Results The length of the upper lip increased by 1 mm ( p = 0.012) on average following maxillary advancement, and it decreased by 0.43 mm ( p = 0.24) on average following maxillary impaction. In the maxillary advancement group, the change in angulation of the incisors predicted the incisal display ( p = 0.03). In the maxillary impaction group, skeletal changes in the vertical dimension predicted changes in upper lip length ( p = 0.033). Conclusions Le Fort I osteotomy for maxillary advancement significantly increases the length of the upper lip. The assessment of lip thickness prior to surgery can help predict the postoperative results. Changing the angulation of the incisors can predict the incisal display. In maxillary impaction, skeletal changes in the vertical dimension can predict the changes in the length of the upper lip.

Introducing and assessing the efficacy of a novel method to reduce enamel damage after orthodontic bracket removal using two herbal-based resin colouring agents: An in vitro study

The differentiation of resin remnants from enamel is a critical factor to minimize enamel damage after bracket debonding. This study was conducted to produce, and ascertain the efficacy of two colouring agents in minimizing enamel loss, adhesive and bonding remnants, and surface roughness after debonding. Two dyes containing annatto (orange colour) and curcumin (yellow colour) were produced. Seventy-two maxillary premolars were divided into three groups. After bracket bonding and debonding, the adhesive remnant was removed with a fine diamond bur. In groups 1 and 2, the orange and yellow dyes were utilized during the removal process, respectively. In group 3 (control) adhesive was removed with no colouring agent. The buccolingual dimension of the teeth was measured at the occlusal, middle, and apical areas, before bonding and after clean-up. The adhesive remnant index (ARI) and bonding remnant index (BRI) scores were recorded and the surface roughness parameters were measured. Data were analysed by ANOVA, Tukey, and Fisher's exact tests (α=0.05). Enamel loss was significantly lower in the groups cleaned by the use of colouring agents than that of the control group (P<0.05). No bonding agent was observed when the dyes were used, whereas 65% of teeth in the control group showed the remaining bonding material (P<0.001). There was no significant difference in ARI scores or surface roughness alterations among the study groups (P>0.05). The two dyes produced in this study were effective in enhancing the visibility of residual resin materials and minimizing enamel loss during the clean-up process.

EFFECT OF FIXED ORTHODONTIC TREATMENT BY UNLICENSED DENTAL SERVICE ON DENTAL HEALTH

Orthodontic treatment is a treatment that induces light pressure on the teeth by using an orthodontic appliance so that the teeth move in a determined direction. Fixed orthodontic treatment must be following the instructions of an orthodontist however many unlicensed dental services and online shop sites offer free braces. Side effects can occur in patients with a fixed orthodontic appliance, but this has been minimized by dentists in the treatment process so that patients get greater benefits. Fixed orthodontic treatment by unlicensed dental services is done without any responsibility in case of an error that threatens dental health. It was reported that 22 years old woman complained that her lower anterior teeth were mobile and there was a white spot on the part where the bracket was set up. The patient wanted to remove the braces that were attached by the unlicensed dental services several years ago. Patients diagnosed with periodontitis localized of teeth 32-42 with mobility grade II et causa trauma of fixed orthodontic appliances. The dental emergencies of tooth mobility, in this case, were carried out by orthodontic bracket removal on the upper and lower teeth and followed by periodontal treatment. So that it does not cause further damage to the underlying supporting tissue and cause the tooth to extrude.

Orthodontic Bracket Removal Using LASER-Technology-A Short Systematic Literature Review of the Past 30 Years.

Background: Since fixed orthodontic treatment is widely spread and one of its inconveniences is bracket removal, as this affects enamel integrity as well as being a cause of discomfort to the patient, studies have searched for the most adequate bracket removal technique, many of them focusing on using laser-technology. Methods: Our review focused on articles published investigating methods of orthodontic bracket removal using laser technology in the last 30 years. Results: 19 relevant studies were taken into consideration after a thorough selection. Different types of laser devices, with specific settings and various testing conditions were tested and the investigators presented their pertinent conclusions. Conclusions: Most studies were performed using ceramic brackets and the best results in terms of prevention of enamel loss, temperature stability for the tooth as well as reduced chair time were obtained with Er:YAG lasers.

Color heterogeneity and individual color changes in dentin and enamel bleached in the presence of a metallic orthodontic bracket.

This in-vitro study evaluated the color changes in enamel and dentin bleached in the presence of an orthodontic bracket, as well as the heterogeneity of the color and contribution of each tissue to the color change (CTCC). Enamel-dentin specimens from extracted bovine teeth were bleached before or after bracket removal or maintained without any treatment (control). The colors of the dentin and enamel were measured individually and after recombining these substrates. The changes in the color (ΔE00 ) and whitening index (ΔWID) were estimated by the color difference between the bleached specimens and those of the control. The CTCC was also calculated by recombining the tissues from different treatments. Images of specimens obtained from a stereomicroscope were used to analyze the color homogeneity within each tissue. The highest values of ΔE00 and ΔWID were observed in the specimens bleached in the absence of a bracket. Bleaching in the presence of a bracket resulted in enamel with a center that was whiter than the periphery. Dentin and enamel presented similar CTCC values. Tooth bleaching performed in the presence of a metallic bracket resulted in a reduced bleaching effect and increased color heterogeneity within both tissues. Tooth bleaching before the orthodontic bracket removal reduces the bleaching effect in both dentin and enamel. Moreover, a heterogeneous color of enamel surface can be observed after tooth bleaching in the presence of a nickel-free metallic orthodontic bracket.

Reducing iatrogenic complications in the treatment of cleft lip and palate

Abstract All patients receiving orthodontic treatment with fixed appliances have a significantly higher risk of developing white spot lesions (WSLs), which are considered the most common iatrogenic complication of treatment. Cleft lip and/or palate (CLP) is a common craniofacial anomaly occurring in approximately one in 800 births. Patients affected by cleft lip and/or palate tend to have poorer oral hygiene and a greater risk of WSLs and caries than non-cleft sibling controls. Patients presenting with a cleft lip and/or palate also have a higher prevalence of molar-incisor hypomineralisation (MIH), which suggests that clinicians involved in the oral health management of cleft patients need to consider all available caries prevention protocols. Cases presenting with hypomineralised teeth create more difficulty in bonding attachments to affected enamel using an acid etch technique and a composite resin material due to the abnormal prism structure. The bond strength to hypomineralised enamel can be as low as two-thirds that of the bond strength to unaffected enamel, which may not be adequate for routine fixed appliance treatment. Furthermore, the removal of orthodontic brackets from hypomineralised enamel may lead to more severe damage to the affected teeth. Resin modified glass-ionomer cement (RMGIC), bonded after conditioning the enamel with polyacrylic acid, creates no resin tags as a result of a chemical rather than a mechanical bond. Therefore, there is less enamel loss during bracket debonding when compared with acid-etch preparation and composite resin bonding. Furthermore, in cases in which the quality of the enamel is deficient causing limits to the shear bond strength of the acid-etched composite resin, the chemical bonding action of RMGIC overcomes the lack of adherence and protects the enamel. RMGIC has cariostatic properties and clinical evidence supports the routine use of these adhesives for bonding in all fixed appliance cases as a strategy for reducing the incidence of white spot lesions and damage to the enamel during bracket debonding.

Effect of organic solvents and ultrasound on the removal of orthodontic brackets.

To evaluate the effect of organic gel solvents (70% acetone and 90% ethanol) and ultrasound in the removal of metallic brackets. Metallic brackets were bonded with light-cured orthodontic composite (Transbond XT) in 120 human bicuspids and divided into 6 groups for the enamel etch-and-rinse adhesive system (XT) and 6 groups to self-etching system (SEPT) according to pretreatment to removal test: control, 70% acetone, 90% ethanol, ultrasound, 70% acetone+ultrasound, and 90% ethanol+ultrasound. The brackets were subjected to removal by shear testing and Adhesive Remnant Index (ARI) evaluation. Some specimens were prepared and its adhesive interface and etching ability observed by scanning electron microscopy (SEM). Only the factor 'ultrasound' and its interaction with 'adhesive' were detected as a source of variance, with the SEPT/ultrasound showing the lowest shear strength than the other groups. Regardless the factor 'ultrasound', XT showed a higher ARI than SEPT; however, when the solvents were used, no differences were detected between XT and SEPT. The organic solvents were not effective in reducing shear bond strength. The etch-and-rinse adhesive system showed a higher and more favorable ARI score than the self-etching primer. The behavior of the organic solvents on ARI showed to be better when associated with the self-etching primer. The ultrasound was effective in reducing the shear bond strength of the self-etching adhesive system but not in affecting the ARI of the adhesive systems.

Evaluation of different types of polishing of composite resin surfaces after the removal of metal and ceramic brackets

Objective: To evaluate the effectivenessof different methods ofcomposite resin polishingafter the removaloforthodontic brackets. Material and Methods: 160resindiscsmade froma matrix ofacrylic resinwere divided into4 groups,according to thetype of composite resinused: G1 - microfilled(n = 40), G2 -microhybrid(n = 40), G3 -nanohybrid(n = 40)and G4-nanofilled(n = 40). One half of the samples wassubjectedto thermocycling, at 2000 cycles from 5 ? 2 ºC to 55 ? 2 ºC, for 1 min each. Halfof each group of resins was bonded with Gemini™ metallic brackets (3MUnitek) andthe otherhalf with Transcend™ ceramic brackets (3MUnitek). Thebrackets were transferred to auniversal testing machine (EMIC DLmodel2000).Half of the specimensfrom eachsubgroupwere polishedwith diamond burs andthe other halfwithSof-Lex discs. The averagesurface roughness of composite resin discswas measured,using aprofilometer,before the bondingof brackets, after the removal of brackets, after removing theexcess resinandafter polishing. Results: After removal of bracketsandafter polishing, the surface roughnesswas greater in the microhybridgroup(ANOVA, p &lt; 0.05).After removalof ceramicbrackets, the groups showedhigher surfaceroughness (ANOVA, p &lt; 0.05). There was no significantdifference inroughnessrelated tothermocyclingand the type ofpolishing.Conclusion:The qualityof thepolishis subjectedto the type ofresinused. Ceramicbrackets provided rougher surfacesafter removal. Both types ofpolishingusedare effective.

Automatic method of analysis of OCT images in the assessment of the tooth enamel surface after orthodontic treatment with fixed braces.

IntroductionFixed orthodontic appliances, despite years of research and development, still raise a lot of controversy because of its potentially destructive influence on enamel. Therefore, it is necessary to quantitatively assess the condition and therein the thickness of tooth enamel in order to select the appropriate orthodontic bonding and debonding methodology as well as to assess the quality of enamel after treatment and clean-up procedure in order to choose the most advantageous course of treatment. One of the assessment methods is computed tomography where the measurement of enamel thickness and the 3D reconstruction of image sequences can be performed fully automatically.Material and methodOCT images of 180 teeth were obtained from the Topcon 3D OCT-2000 camera. The images were obtained in vitro by performing sequentially 7 stages of treatment on all the teeth: before any interference into enamel, polishing with orthodontic paste, etching and application of a bonding system, orthodontic bracket bonding, orthodontic bracket removal, cleaning off adhesive residue. A dedicated method for the analysis and processing of images involving median filtering, mathematical morphology, binarization, polynomial approximation and the active contour method has been proposed.ResultsThe obtained results enable automatic measurement of tooth enamel thickness in 5 seconds using the Core i5 CPU M460 @ 2.5GHz 4GB RAM. For one patient, the proposed method of analysis confirms enamel thickness loss of 80 μm (from 730 ± 165 μm to 650 ± 129 μm) after polishing with paste, enamel thickness loss of 435 μm (from 730 ± 165 μm to 295 ± 55 μm) after etching and bonding resin application, growth of a layer having a thickness of 265 μm (from 295 ± 55 μm to 560 ± 98 μm after etching) which is the adhesive system. After removing an orthodontic bracket, the adhesive residue was 105 μm and after cleaning it off, the enamel thickness was 605 μm. The enamel thickness before and after the whole treatment decreased by about 125 μm.ConclusionsThis paper presents an automatic quantitative method for the assessment of tooth enamel thickness. This method has proven to be an effective diagnostic tool that allows evaluation of the surface and cross section of tooth enamel after orthodontic treatment with fixed thin-arched braces and proper selection of the methodology and course of treatment.

Methods for removal of resin remaining after debonding of orthodontic brackets: A literature review

The removal of resin debris and/or resin cement from the enamel surface without causing iatrogenic is the main objective when removing the orthodontic brackets. Some factors such as the time required for removal, damage to the tooth structure, are essential factors for the clinician at the time of removal. Various techniques are used for the removal of orthodontic brackets after the treatment; it is known that the use of clinical procedures such as the use of diamond burs and some pliers removers can damage the structure of the enamel, often depending on the bond strength that should be taken into consideration at the time of removal. This literature review aims to gather the most relevant studies that can clarify the clinical technique, which may be more suitable for removal of the brackets.

Bond strength of 4 orthodontic adhesives used with a caries-protective resin sealant

The purpose of this study was to investigate the shear peel bond strength (SPBS) and resin remnant retention after removal of orthodontic brackets bonded with 1 of 4 orthodontic adhesives (Transbond XT [3M/Unitek, Monrovia, Calif], Blugloo [Ormco Corp, Glendora, Calif], Light Bond [Reliance Orthodontic Products, Itasca, Ill], and APC Plus [3M/Unitek]) applied over a filled, resin sealant (ProSeal [Reliance Orthodontic Products]). Extracted premolars were first acid etched and then coated with the sealant used as a primer. This was followed by cementation of a stainless steel orthodontic bracket to the buccal surface with 1 of the 4 adhesive systems. Two adhesive systems (Transbond XT and Blugloo), without the filled sealant applied, were used as references. All specimens were stored in deionized water at 37 degrees C for 30 days, thermocycled for 24 hours at 30-second intervals between 10 degrees C and 50 degrees C water baths, and debonded with a universal testing machine. The 4 adhesive-sealant combination groups had mean SPBS values slightly lower than the 2 adhesive-only reference systems, but all were greater than 10 MPa (range, 10.1-15.9 MPa), which is considered a clinically acceptable bond strength. ANOVA showed a statistically significant difference (P <0.05) in mean SPBS among the 4 adhesive-sealant combinations. The most frequent site of bond failure at debonding for the adhesive-sealant combinations was within the adhesive.

An electromyographic evaluation of bilateral symmetry of masticatory, neck and trunk muscles activity in patients wearing a positioner

This study was designed to investigate the attitude of a positioner (Finition) or an Hawley's retention appliance to create a symmetric function of the masticatory, neck and trunk muscles during the orthodontic retention phase. Sixteen patients (18.5 +/- 2.2 years) were included in the sample. All the patients received an orthodontic therapy for the treatment of an Angle's class I malocclusion and skeletal class I, for a period of 2 years. After removal of orthodontic brackets, eight patients wore a teeth positioner (group I) as retention appliance and eight subjects wore an Hawley's appliance as upper retention (group II). Surface electromyographic (sEMG) activity was recorded from the bilateral anterior temporal, posterior temporal, masseter, sternocleidomastoid (SCM), upper and lower trapezius and cervical muscles at mandibular rest position and during maximal voluntary clenching (MVC) at T0, i.e. soon after the removal of orthodontic brackets and at T1, i.e. after 3 months of retention treatment. No significant difference was observed between the two groups at T0. At T1, at mandibular rest position, the group I showed a significantly lower sEMG activity of anterior temporal and SCM muscles compared with the group II. During MVC, at T1, the group I showed a significantly lower sEMG activity of the SCM and posterior cervicals, compared with the group II. The positioner seems to show a relevant effect on the sEMG activity of masticatory, neck and trunk muscles.

Selective removal of composite sealants with near-ultraviolet laser pulses of nanosecond duration

It is often necessary to replace pit and fissure sealants and composite restorations. This task is complicated by the necessity for complete removal of the remaining composite to enable suitable adhesion of new composite. Previous studies have shown that 355-nm laser pulses from a frequency-tripled Nd:YAG laser can selectively remove residual composite after orthodontic bracket removal on enamel surfaces. Our objective is to determine if such laser pulses are suitable for selective removal of composite pit and fissure sealants and restorations. Optical coherence tomography is used to acquire optical cross sections of the occlusal topography nondestructively before sealant application, after sealant application, and after sealant removal. Thermocouples are used to monitor the temperature in the pulp chamber during composite removal under clinically relevant ablation rates, i.e., 30 Hz and 30 mJ/pulse. At an irradiation intensity of 1.3 J/cm2, pit and fissure sealants are completely removed without visible damage to the underlying enamel. At intensities above 1.5 J/cm2, incident laser pulses remove the resin layer while at the same time preferentially etching the surface of the enamel. Temperature excursions in the pulp chamber of extracted teeth are limited to less than 5 degrees C if air-cooling is used during the rapid removal (1 to 2 min) of sealants, water-cooling is not necessary. Selective removal of composite restorative materials is possible without damage to the underlying sound tooth structure.

In vitro comparison of debonding force and intrapulpal temperature changes during ceramic orthodontic bracket removal using a carbon dioxide laser

The aim of this study was to develop a method to reduce the fracture of ceramic orthodontics brackets during debonding procedures. Lasers have been used to thermally soften the bonding resin, which reduces the tensile debonding force. Thermal effects of lasers may create adverse effects to the dental pulp. Previous studies have shown that no pulpal injury occurs when the maximum intrapulpal temperature rise stayed below 2 degrees C. This study investigated the effect of lasing time on intrapulpal temperature increase and tensile debonding force with a 18 watt carbon dioxide laser. Ceramic brackets were bonded to mandibular deciduous bovine teeth and human mandibular first premolars with a photoactivated bonding resin. Modified debonding pliers was used to accurately position the laser beam onto the ceramic bracket. Lasing time required to keep the maximum intrapulpal temperature rise below 2 degrees C was determined by the use of thermocouples inserted into the pulp chambers of the specimens. A tensile debonding force was applied on the control group without lasing and the experimental group was debonded after applying a predetermined lasing time with a carbon dioxide laser. It was found that there was a significance difference (P < 0.05) in tensile debonding force between the control group and the experimental group. It is feasible to use a laser for the debonding of ceramic brackets while keeping the intrapulpal temperature rise below the threshold of pulpal damage.

Orthodontic bracket removal using conventional and ultrasonic debonding techniques, enamel loss, and time requirements

The purpose of this study was to examine the effects of ultrasonic orthodontic bracket removal and cleanup and compare them with conventional debonding and cleaning of the enamel surfaces with burs and polishing disks. The amount of enamel loss and time for bracket removal and clean-up were also addressed. Thirty extracted human premolars were collected. The teeth were randomly placed in one of the three debonding groups: debonding with orthodontic pliers and enamel clean-up with finishing burs and polishing disks (group 1), debonding with orthodontic pliers and ultrasonic clean-up of the enamel surface (group 2), and ultrasonic debonding enamel clean-up (group 3). The teeth were stored for 48 hours in 100% humidity before bracket removal. All brackets were then removed. Polyvinyl siloxane impressions were made before and after bracket removal. Direct measurements of the teeth in micrometers were made at all steps. An additional 30 teeth were similarly prepared, and the brackets were debonded and cleaned-up as in the three groups previously described. The total time for bracket removal and enamel clean-up for each group was recorded in seconds.(ABSTRACT TRUNCATED AT 250 WORDS)

Fracture incidence on debonding of orthodontic brackets from porcelain veneer laminates

The bonding force and the incidence of porcelain fracture for two porcelain systems, on removal of orthodontic brackets bonded to porcelain veneer laminates after thermocycling, were determined. A factorial design with a total sample size of 256 was used. The factors tested were (1) porcelain type (feldspathic [porcelaince]or high alumina [porcelain VI]), (2) surface treatment (glazed or roughened), (3) priming agent (silane or alcohol), (4) bonding resin (macrofilled or microfilled), and (5) debonding time (30 minutes or 24 hours). An analysis of variance revealed that surface treatment, primer, resin type, and debonding time each contributed significantly to the debonding force. The probability, of porcelain fracture was dependent on the porcelain type and the debonding force, with porcelain VI exhibiting a significantly higher probability of fracture than porcelain CE at the same debonding force. The etched surface of porcelain CE exhibited a more retentive microstructure than porcelain VI. The success of using bonded orthodontic brackets on porcelain veneer laminates depends on both the bond of resin to porcelain and the resistance of porcelain to fracture during debonding. For a given porcelain veneer, factors that provide a higher debonding force result in a higher probability of porcelain veneer fracture.

Enamel surface evaluations after clinical treatment and removal of orthodontic brackets

Methods for the removal of resins attached to acid-etched enamel are receiving increased attention. An evaluation method which permitted convenient statistical comparisons of the effectiveness of various removal procedures was used. The method was based on ranking of SEM photomicrographs of epoxy replicas of teeth from clinical cases. Forty-five orthodontically treated teeth were evaluated after removal of brackets and a heavily filled bonding resin, using three basic procedures. Eleven raters ranked photomicrographs on the basis of the apparent smoothness of the replicated enamel surface. There was no significant difference in the judgment of smoothness by the raters. Significant differences were found between the three removal techniques. Enamel roughness decreased with removal technique in the following order: (1) hand scaler, (2) twelve-fluted carbide bur, and (3) ultrafine bur. A final pumicing treatment was also found to be beneficial, although it did not remove any deep scratches.

Tooth surface appearance after debonding.

The microscopic and clinical appearance of enamel after removal of orthodontic brackets is discussed. The possibility that residual adhesive particles may become discoloured is examined.