Evaluation of facial hard and soft tissue asymmetry using cone-beam computed tomography.

INTRODUCTION: The purposes of this study were to (1) evaluate facial asymmetry 3 dimensionally using cone-beam computed tomography (CBCT) and (2) compare the right and left facial hard and soft tissues volumetrically and their interferences on each other. METHODS: The CBCT data of 49 asymmetric (soft tissue menton deviation, ≥4 mm; distance from the facial midline) (mean age, 19.9 ± 5.6 years) and 39 symmetric patients (soft tissue menton deviation, <4 mm) (mean age, 17.8 ± 5.5 years) were exported to the MIMICS software program (version 13.0; Materialise, Leuven, Belgium). Linear, surface distance, angular, volumetric, and surface area measurements were performed 3 dimensionally to assess and compare intragroup and intergroup differences. RESULTS: In the asymmetry group, linear measurements such as ramus height, mandibular effective and corpus length, and absolute mandibular volumetric measurements were significantly decreased (P <0.001), whereas facial mandibular, and soft and hard tissue volumetric measurements made on 3-dimensional images, and linear measurements on 2-dimensional images were increased (P <0.001) on the deviation side. CONCLUSIONS: Facial hard and soft tissue asymmetries can be precisely quantified using CBCT. However, especially in the gonial region where the surface topography shows alterations caused by asymmetry, many anatomic landmarks should be chosen for the assessment of asymmetry. At the gonial level, the compensation of the soft tissues for the hard tissues was found on 2-dimensional images; nevertheless, 3-dimensional right and left volumetric soft tissue evaluations provide evidence for asymmetry.

Effect of Er:YAG laser on debonding strength of laminate veneers.

OBJECTIVE: The purpose of this study was to evaluate the debonding strength of laminate veneers after using erbium-doped: yttrium aluminium garnet (Er:YAG) laser. MATERIALS AND METHODS: A total of 60 bovine mandibular incisor teeth were divided into two groups (n = 30). Cylindrical specimens (0.7 mm × 5 mm) were fabricated from Empress II ceramic. Then, they were cemented to incisors using dual-cured resin cement (Variolink II). In the first group, no laser application was performed. The Er:YAG laser was applied on each laminate veneer at the test group for 9 s by using the scanning method. Shear force to remove the laminate veneers were applied with universal testing machine at a crosshead speed of 1 mm/min. RESULTS: Results of this study exhibited significant differences between the control (27.28 ± 2.24 MPa) and test group (3.44 ± 0.69 MPa) (P < 0.05). CONCLUSION: This study shows that application of Er:YAG laser decreased the bond strength of laminate veneers.

Periodontal status of ectopic canines after orthodontic treatment.

OBJECTIVE: To evaluate the periodontal health and tooth vitality of palatally impacted and buccal ectopic maxillary canines after completion of orthodontic treatment. MATERIALS AND METHODS: Fifteen patients who had unilateral, palatally impacted canines and 15 patients who had unilateral, buccal ectopic canines comprised the subjects of the study. Clinical and radiographic data was collected by recalling the patients in both groups after a mean period of 3.82 ± 1.54 years following completion of their orthodontic treatment. In both groups, the contralateral, normally placed canines served as controls. RESULTS: Palatally impacted canines had greater pocket depths, higher gingival levels, higher electric pulp testing scores, and reduced bone levels compared to their contralaterals. Buccal ectopic canines had increased plaque and gingival bleeding index, greater pocket depths, reduced attached gingival width, higher gingival levels, increased clinical crown lengths, and higher electric pulp testing scores compared to their contralaterals. Buccal ectopic canines had lower electric pulp testing scores and higher bone levels compared to palatally impacted canines. CONCLUSION: All ectopic canines had increased plaque and gingival bleeding index, greater pocket depths, reduced attached gingival width, higher gingival levels, increased crown lengths, higher electric pulp testing scores, and reduced bone levels compared to their contralaterals.

Prevention of demineralization around orthodontic brackets using two different fluoride varnishes.

OBJECTIVE: This in-vitro study was done to evaluate the effects of two different seal materials, Duraflor™ and Enamel Pro(®) Varnish, on enamel demineralization adjacent to orthodontic fixed appliances. METHODS: Seventy-two extracted solid premolars were allocated to three groups as one control and two study groups after brackets were placed and bonded with Transbond™ XT. The control group received no topical fluoride application after bonding, whereas in the study groups two fluoride varnishes, Enamel Pro(®) Varnish and Duraflor™ were applied on the teeth adjacent to brackets. All specimens were then immersed separately in demineralization solution for 96 hours at constant temperature. Demineralization of the enamel surface was evaluated quantitatively by cross-sectional microhardness testing: indentations were made at the edge of the bracket base (0 µm) and at 100 and 200 µm distant from it. In all of these positions, 5 indentations were made at 10, 20, 40, 70 and 90 µm of depths from the external surface of the enamel. RESULTS: The results revealed that, Enamel Pro(®) Varnish and Duraflor™ group values are higher than the values of control group at every depth. The differences between the depths showed that the microhardness values decreased significantly when the depth increased. In the control group, more demineralization occurred in every indentation compared to the study group. CONCLUSION: Duraflor™ and Enamel Pro(®) Varnish can be considered for use in clinic as an effective method to prevent or reduce demineralization during orthodontic treatment, especially in patients with poor oral hygiene.

The effects of three different mouth rinses in a 4-day supragingival plaque regrowth study.

OBJECTIVE: This study compares the effects of three different mouth rinses with respect to reducing Streptococcus mutans (S. mutans) colony counts on the teeth and tongue surfaces. MATERIALS AND METHODS: In this study, comparison tests using the alcohol-free 0.1% chlorhexidine mouth rinse, alcohol-containing essential oil mouth rinse, and alcohol-free essential oil-containing mouth rinse were conducted. Patients were instructed to avoid mechanical cleaning with either a toothbrush or toothpick for 4 days. The first samples were collected from teeth surfaces and the dorsum of the tongue after a professional cleaning, and the second samples were collected after a 4-day plaque re-growth period. The supragingival plaque from the buccal surfaces of teeth #11, 14, 31, 34 as well as samples from the dorsum of the tongue, were assessed using the Dentocult(®) strips. RESULTS: The Listerine(®) and Ondrohexidine(®) groups did not show any statistically significant differences between the values of the two samples (P = 0.734, P = 0.307). The MC(®) group and the control group showed significantly higher results than the first sample values. The effectiveness of the mouth rinses on S. mutans colony counts from the teeth surfaces were higher in the Listerine(®), Ondrohexidine(®), and Mouthwash Concentrate(®) groups. The difference between the first and second samples of the S. mutans colony counts from the tongue surface was found to be statistically significant, and S. mutans colony counts were higher than the first sample (P = 0.015). CONCLUSION: Alcohol and essential oil-containing Listerine(®) mouth rinse, alcohol-free Ondrohexidine(®), alcohol-free essential oil-containing MC(®) mouth rinse had the same effect on S. mutans counts, higher than the 1% alcohol solution on teeth surface. They had the ability to maintain the S. mutans counts at the same level for 4 days in patients who did not perform any mechanical oral hygiene regimen.

A cephalometric comparative study of class II correction with Sabbagh Universal Spring (SUS(2)) and Forsus FRD appliances.

OBJECTIVE: The purpose of this clinical prospective study was to compare the dentofacial changes produced by the Sabbagh Universal Spring (SUS(2)) and Forsus FRD appliances in late adolescent patients with Class II malocclusion, and quantify them in comparison with an untreated group. METHOD: The study was carried out on 59 patients with skeletal and dental Class II malocclusion due to retrognatic mandible. Among these, 20 were treated with SUS(2), 20 were treated with FRD, and no treatment was done to 19 subjects as the control group. 36 cephalometric landmarks were identified on each lateral cephalometric radiograph. RESULTS: The effects of both appliances were dentoalveolar and no significant vertical and sagittal skeletal effect on maxilla and mandible was achieved. The retrusion and extrusion of the maxillary incisors as well as the protrusion and intrusion of mandibular incisors were found to be statistically significant in both treatment groups. Soft tissue profile improvement was limited in both treatment groups. CONCLUSIONS: Both appliances corrected Class II discrepancies through dentoalveolar changes; however lower incisor proclination was more prominent with the Forsus FRD.

FEM analysis of a new miniplate: stress distribution on the plate, screws and the bone.

OBJECTIVES: Non-homogeneous force distribution along the miniplates and the screws is an unsolved question for skeletal anchorage in orthodontics. To overcome this issue, a miniplate structure was designed featuring spikes placed on the surface facing the cortical bone. The aim of this study was to examine and compare the force distribution of the newly designed plate-screw systems with the conventional one. METHODS: A model of bone surface with 1.5 mm cortical thickness, along with the two newly designed miniplates and a standard miniplate-screw were simulated on the three-dimensional model. 200 g experimental force was applied to the tip of the miniplates and the consequential effects on the screws and cortical bone was evaluated using three-dimensional finite element method. RESULTS: As a result of this finite element study, remarkably lower stresses were observed on the screws and the cortical bone around the screws with the newly designed miniplate when compared with the conventional one. CONCLUSION: The newly designed miniplate that has spikes was found effective in reducing the stress on and around the screws and the force was distributed more equivalently.

Effects of different application durations of scanning laser method on debonding strength of laminate veneers.

Porcelain laminate veneers as esthetic and minimally invasive restorations are being used as an alternative to full veneer crowns. However, the removal of porcelain veneers that have failed may be an uncomfortable and time-consuming procedure because of the high bond strength between the porcelain laminate veneers and the tooth surface. The purpose of this study was to prepare a simple and reliable method for porcelain laminate veneer debonding by using an Er:YAG laser with the scanning method and to determine the amount of lasing time required. Eighty cylindrical specimens with a thickness of 0.7 mm and a diameter of 5 mm were fabricated from Empress II ceramic material. They were cemented on the labial surface of extracted bovine mandibular incisors using Variolink II (Ivoclar Vivadent AG, Schaan, Liechtenstein) and light cured for 40 s. The specimens were randomly divided into four groups of 20. The first group was assigned as the control group and no laser application was performed. The Er:YAG laser was applied on each specimen in the other three study groups for 3, 6, and 9 s by using the scanning method. One second after the lasing, a mechanical force was applied to remove the laminate veneers by using an Instron Universal Testing machine. Results of this study exhibited statistically significant differences between the control group and the three study groups. Intergroup comparison of shear bond strengths of the three study groups showed a statistically significant difference (p = 0.0001). This study showed that all three application times of Er-YAG laser were effective for debonding ceramic laminate veneers by softening the adhesive resin.

Comparison of shear bond strengths of ceramic brackets after different time lags between lasing and debonding.

Laser use is effective in the debonding of ceramic brackets. However, a standardization of the laser debonding techniques used has not yet been implemented. The purpose of this study was to evaluate the effect of the time lag elapsed between lasing and shearing on debonding of ceramic brackets. One hundred polycrystalline ceramic brackets were placed on human premolar teeth, which were randomly divided into five groups of 20. One group was assigned as the control. The Er-YAG laser was applied on each bracket in four experimental groups at 5 W for 6 s with the scanning method. Debonding was performed 1 s, 18 s, 30 s, or 60 s after laser exposure. Shear bond strengths and adhesive remnant index scores were measured. Statistically significant difference was observed between the control and experimental groups when the data for the shear bond strengths was considered (p < 0.05). Adhesive remnant index scores of the groups were not statistically different (p > 0.05). Debonding ceramic brackets after 18 s when lased 6 s using an Er-YAG laser with the scanning method is safe and also suitable for clinical use since three brackets can be debonded at a time in succession.

Effects of different application durations of ER:YAG laser on intrapulpal temperature change during debonding.

This study was done to determine the amount of lasing time required to remove ceramic brackets safely without causing intrapulpal damage by using Er:YAG laser with the scanning method. Part 1: 80 bovine mandibular incisors with ceramic brackets were randomly assigned into four groups of 20 as one control and three study groups. In the study groups, brackets were debonded after lasing for 3, 6, and 9 s, whereas debonding was performed without lasing in the control group. Shear bond strengths and ARI scores were also measured. Part 2: 30 human premolars with ceramic brackets were randomly divided into three groups of ten, as 3, 6, and 9 s of lasing durations. Intrapulpal temperature was measured at the same lasing times by a thermocouple. Statistically significant lower shear bond strengths were found in study groups compared to the control. A negative correlation was seen between the bond strengths and ARI scores in such a way that, as the shear bond strengths decreased, the ARI scores increased. Temperature increases for all the study groups were measured below the 5.5°C benchmark. All lasing times were effective for debonding without causing enamel tear outs or bracket failures. The temperature proportionally increased with the extension of the lasing duration. Six-second lasing by the scanning method using Er:YAG laser was found to be the most effective and safest way of removing the ceramic brackets without causing damage to the enamel and pulpal tissues.

Evaluation of the Immediate Dentofacial Changes in Late Adolescent Patients Treated with the Forsus(™) FRD.

OBJECTIVES: The purpose of this study was to evaluate the short-term dentoalveolar and soft tissue changes in late adolescent patients treated with the Forsus™ FRD. METHODS: A prospective study was carried out on 54 lateral cephalometric radiograms that were taken before placement and after removal of the appliance in the treatment group (15 subjects) and at the beginning and six months after in the control group (12 subjects). The patient selection criteria were as follows: skeletal and dental Class II malocclusion due to retrognatic mandible, normal or low-angle growth pattern, post-peak growth period, no extracted or congenitally missing permanent teeth, and minimum crowding in the lower dental arch. RESULTS: THE STATISTICAL ASSESMENT OF THE DATA SUGGESTED THE FOLLOWING RESULTS: No sagital and vertical skeletal changes were induced. The mandibular incisors were protruded and intruded, while the maxillary incisors were retruded and extruded. The occlusal plane was rotated in clockwise direction as a result of these dentoalveolar changes. Overbite and overjet were reduced in all patients. Soft tissue profile slightly improved. CONCLUSIONS: The results revealed that, in late-adolescent patients Forsus™ FRD corrected Class II discrepancies through maxillary and mandibular dentoalveolar changes.

Evaluation of metal concentrations in hair and nail after orthognathic surgery.

INTRODUCTION: Titanium miniplates are widely used in orthognathic surgery. Titanium is considered to be a bioinert material, although its long-term accumulation in distant human tissues is unclear. The study was designed to evaluate the concentrations of aluminum (Al), titanium (Ti), and vanadium (V) in the hair and nail of patients who underwent orthognathic surgery. METHODS: The study group comprised 20 patients who had had orthognathic surgery minimum 14 and maximum 96 months previously (mean [SD], 54.7 [3.5] mo). Miniplates and miniscrews were made of Ti-6Al-4V alloys (Trimed, Ankara, Turkey). The control group comprised 10 healthy adults not operated on. Metal concentrations in the hair and nail of the subjects were measured by inductively coupled plasma mass spectroscope (Thermo Elemental X7 series; Thermo Electron, London, England). Descriptive statistical methods were used for data analysis, and Mann-Whitney test was used to compare both groups. RESULTS: Concentrations of Al, Ti, and V in the hair of the study group were significantly higher than those in the control group (P < 0.001). Nail Ti and V concentrations of the study group were also significantly higher than those of the control group (P < 0.001 and P < 0.01, respectively). Nail Al concentration was similar in both groups (P > 0.05). CONCLUSIONS: Increased corrosive element concentrations may be observed in the hair and nail of patients who underwent orthognathic surgery.

Comparison of facial soft tissue measurements on three-dimensional images and models obtained with different methods.

AIM: The aim of this study was to compare the clinical facial soft tissue measurements with the measurements of facial plaster cast, three-dimensional scanned facial plaster cast, 3-dimensional digital photogrammetrical images, and three-dimensional laser scanner images. MATERIALS AND METHODS: Three-dimensional facial images of 15 adults were obtained with stereophotogrammetry and a three-dimensional laser scanner. Facial models of subjects were obtained using silicone impression and were scanned. Landmarks were marked on the subjects and plaster casts, digitized on three-dimensional models, and measured in Mimics 12.0 software (Materialise's Interactive Medical Image Control System, Leuven, Belgium). RESULTS: No statistically significant differences were found between all three-dimensional measurement methods in mouth width, philtrum median height, and nasal width. Comparison of clinical measurements with facial plaster cast measurements revealed that philtral width, nasal tip protrusion, and right lip and nostril heights were wider and longer in clinical measurements than in facial plaster cast measurements. Comparison of clinical measurements to the laser scanned and stereophotogrammetric model measurements revealed that philtrum lateral and lip heights and philtral width were significantly different between methods. When laser scanned and stereophotogrammetric measurements were compared, significant differences were observed in lip and nostril heights. CONCLUSIONS: Facial impression may be problematic owing to the depression caused by the impression material especially on the tip of the nose. Laser scanning is not sensitive enough to visualize the deeper indentations such as nostrils. Stereophotogrammetry is promising for three-dimensional facial measurements and even will be better when color identification between mucocutaneous junctions of the lip region is achieved.

Debonding of ceramic brackets by a new scanning laser method.

INTRODUCTION: The purpose of this in-vitro study was to develop a new method to debond ceramic brackets by scanning with an Er:YAG laser. METHODS: Sixty bovine mandibular incisors were randomly divided into 2 groups of 30. Polycrystalline ceramic brackets were placed on their labial surfaces by using the orthodontic composite adhesive Transbond XT (3M Unitek, Monrovia, Calif) and light cured for a total of 40 seconds. The first group was the control group, with no laser application performed. The Er:YAG laser was used on each bracket in the study group at 4.2 W for 9 seconds with the scanning method. The force required for debonding the brackets was applied 45 seconds after laser exposure. Shear bond strengths were measured in megapascals with a universal testing machine, and adhesive remnant index scores were assigned to each specimen. RESULTS: Statistically significant (P <0.001) lower shear bond strengths were found in the laser group (9.52 MPa) compared with the control group (20.75 MPa). Likewise, the adhesive remnant index scores were statistically different (P <0.001); the laser group had twice as many samples with adhesive, with the adhesive remnant index scores of 2 or 3. CONCLUSIONS: The application of the Er:YAG laser with the scanning method is effective for debonding ceramic brackets by degrading the adhesive through thermal softening.

Enamel colour changes at debonding and after finishing procedures using five different adhesives.

The purpose of this study was to evaluate enamel colour alteration of five different orthodontic bonding adhesives by means of digital measurements after exposure to photoageing in order to simulate discolouration of adhesives in vivo. Seventy-five non-carious premolars were randomly divided into five equal groups. The brackets were bonded with five different adhesives (Transbond XT, Eagle Bond, Light Bond, Blugloo, Unite) and subjected to artificial accelerated photoageing for 24 hours. The enamel surfaces were colourimetrically evaluated before bonding, following debonding and cleaning with a tungsten carbide bur, after polishing with Stainbuster, and after photoageing of the debonded enamel surface. The Commission Internationale de l'Eclairage(CIE) colour parameters (L*a*b*) were recorded and colour differences (DeltaE) were calculated. The results were statistically analyzed using the Kruskall-Wallis test. Further investigation among subgroups was performed using Dunn's multiple correlation test (P < 0.05). The clinical detection threshold for DeltaE value was set at 3.7 units. DeltaE values between the first and second measurements showed an increase in the Transbond XT, Eagle Bond, and Light Bond groups. The highest DeltaE value was 1.51 +/- 1.15 in the Transbond XT group. No clinically significant DeltaE value was observed. Colour changes of orthodontic bonding systems induced by photoageing cannot be clinically observed. Polishing with Stainbuster eliminates enamel surface roughness, which may improve light reflection.

Effects of different silanes and acid concentrations on bond strength of brackets to porcelain surfaces.

The aim of this study was to determine the optimum silane-coupling agent and the optimum concentration of acid agent when bonding to porcelain surfaces. Eighty deglazed feldspathic porcelain discs with a diameter of 10 mm and a thickness of 2 mm mounted in acrylic resin blocks were randomly divided into four groups. In groups 1 and 2, the porcelain surfaces were etched with 9.6 per cent hydrofluoric (HF) acid and in groups 3 and 4 with 5 per cent HF acid. In groups 1 and 3, the Dynalock maxillary central incisor brackets were bonded with Pulpdent silane and Unite bonding adhesive and in groups 2 and 4 with Reliance silane and Unite. Shear forces were applied to the samples using an Instron universal test machine. The non-parametric Kruskal-Wallis test was used to determine significant differences in bond strengths between the four groups and Dunn's multiple comparison test to compare subgroups. The mean bond strengths and standard deviations of groups 1 to 4 were 5.51 +/- 1.19, 6.54 +/- 0.002, 4.55 +/- 1.93, and 6.39 +/- 0.45 MPa, respectively. Specimens bonded with Reliance showed a statistically significantly higher in vitro bond strength than those bonded with Pulpdent. The concentration of etching gels did not result in any statistically significant difference on the in vitro bond strength when evaluated separately.

Reduction of salivary mutans streptococci in orthodontic patients during daily consumption of yoghurt containing probiotic bacteria.

Previous studies have suggested that probiotic supplements in dairy products may affect the oral microbial ecology, but the effect in orthodontic patients has not previously been reported. The aim of the present study was to examine whether short-term consumption of fruit yogurt containing probiotic bifidobacteria would affect the levels of salivary mutans streptococci and lactobacilli in patients with fixed orthodontic appliances. A double-blind, randomized crossover study was performed and 24 healthy adolescents (12-16 years) undergoing orthodontic treatment were followed over four periods. During periods 2 and 4 (2 weeks each), the subjects ingested 200 g fruit yogurt containing Bifidobacterium animalis subsp. lactis DN-173010 (2 x 10(8) colony forming units/g) once daily or a control yogurt without viable bacteria. Periods 1 and 3 were run-in and wash-out periods of 1 and 6 weeks, respectively. Salivary mutans streptococci and lactobacilli were enumerated with chair-side kits before and after the yogurt consumption periods. Pre- and post-treatment values within each regimen were compared with a two-tailed marginal homogeneity test for categorical data. A statistically significant reduction of salivary mutans streptococci was recorded after probiotic yogurt consumption (P < 0.05), which was in contrast to the control yogurt. No significant alterations of the salivary lactobacilli counts were observed. Short-term daily consumption of fruit yogurt containing Bifidobacterium animalis subsp. lactis DN-173010 may reduce the levels of mutans streptococci in saliva during orthodontic treatment with fixed appliances.

Perception of pain and discomfort during tooth separation.

OBJECTIVES: To evaluate patients' perceptions of pain and discomfort during tooth separation and to compare the effectiveness of brass wire and elastomeric separators. METHODS: The participants were 87 adults with a mean age of 22.1 +/- 1.9 years. Elastomeric and brass wire separators were inserted mesial and distal to upper right (elastomeric separators) and upper left first molars (brass wire separators) in each subject. After seven days, the amount of tooth separation was measured with a leaf gauge, and pain perception and discomfort were evaluated with a visual analogue scale and questionnaire. RESULTS: The elastomeric separators produced significantly more separation than the wire separators. There was a statistically significant difference in the subjects' perceptions of pain and discomfort at rest and during chewing between the different separators (p < 0.001). In general, the brass wire separators caused the greatest pain and discomfort immediately after insertion. Pain from the wire separators subsided over seven days, whereas elastomeric separators caused the greatest pain on the first two days after insertion. Eating was negatively influenced by the separation in 61 per cent of the subjects on the first day. On the other hand, other daily activities were affected minimally. CONCLUSIONS: The different levels of pain and discomfort caused by these separators, together with their advantages and disadvantages, can help the clinician to choose an appropriate separator. Patients should be warned that pain due to separation may affect their chewing, social life, school work and sleeping. Analgesics and soft food are recommended following placement of separators.

Shear bond strength of brackets bonded to amalgam with different intermediate resins and adhesives.

The aims of this study were to compare, in vitro, the shear bond strength (SBS) of stainless steel orthodontic brackets bonded to silver amalgam with the use of three different intermediate resins and two different adhesives, and to evaluate bond failure mode. Forty-five amalgam specimens were divided into three equal groups. In groups 1 and 2, the brackets were bonded with Unite (3M Unitek) using Reliance Metal Primer (RMP; Reliance Orthodontic Products) and Power Bond OLC (PB OLC; Ortho Organizers Inc.) as intermediate resins, respectively. In group 3, Resinomer and One-Step Plus (OS+; Bisco Inc.) were used. Thirty bovine teeth served as the controls to test bracket bonding to acid-etched enamel with Unite and Resinomer-OS+. After thermocycling from 10 to 50 degrees C 1000 times, all samples were tested for SBS. Bond failure sites were classified using a modified adhesive remnant index (ARI) system. Data were analyzed with one-way analysis of variance, post hoc Tukey multiple comparison and chi-square tests. The results showed that the mean SBS to amalgam surfaces were significantly lower than those to etched bovine enamel (P<0.001). There were no statistically significant differences in mean SBS between the amalgam bonding groups (P>0.05). For the ARI, significant differences were found between the amalgam- and enamel-bonding groups (P<0.001). The mean SBS of stainless steel orthodontic brackets bonded to amalgam surfaces with RMP, PB OLC, OS+ intermediate resins and Unite and Resinomer adhesives was significantly lower than to etched bovine enamel. Bond failure occurred at the amalgam-adhesive interface regardless of the adhesive system and without damage to the amalgam restoration.