Shear bond strength of rebonded mechanically retentive ceramic brackets

Comparison of shear bond strength and residual adhesive remnants on the enamel surface after debonding of three different orthodontic molar tubes : A scanning electron microscope study

BACKGROUND

The aim for this research was to evaluate and compare the impact, bond strength, and residual adhesive on the enamel surface after debonding of different orthodontic molar tubes. The tested materials were metal, composite, and newly introduced ceramic orthodontic molar tubes.

MATERIALS AND METHODS

In all, 66 first molar teeth were randomly divided into three groups. Metal, glass-fiber composite and ceramic orthodontic molar tubes were bonded and shear bond strength (SBS) tests were performed. The adhesive remnant index (ARI) scores after debonding were recorded and the enamel surfaces were investigated using scanning electron microscopy (SEM) after the adhesives were cleaned.

RESULTS

The mean SBS values of the metal and ceramic tube groups were significantly higher than that of the glass-fiber composite tube group. The highest SBS values were recorded for the ceramic tube group (11.09 ± 2.51 MPa). Failure typically occurred at the adhesive-enamel interface in the ceramic group, whereas the majority of the samples in the glass-fiber composite group showed failure at the adhesive-tube base interface according to ARI and SEM investigations. ARI 1 and ARI 2 scores were commonly observed for the metal tube group.

CONCLUSIONS

All the molar tubes tested had generated clinically acceptable SBS values; however, the values for glass-fiber composite molar tubes were significantly lower than those for the ceramic and metal molar tubes. If the debonding procedure is performed carefully, the ceramic molar tubes may be an enamel-safe product for patients seeking fully esthetic orthodontic treatment.

The effect of different mechanical retention forms on shear bond strength of rebonding of ceramic brackets

The objective of this study is to compare the shear bond strength (SBS) and the morphological characteristics and chemical compositions of the base surface of newly bonded and rebonded ceramic brackets with different mechanical retention bases. Sixty extracted human premolars were divided into the newly bonded and rebonded groups. Ceramic brackets with patterned, laser-etched, and particle-coated patterned bases were randomly bonded to the tooth samples in each group (n=10 per base type). The rebonded brackets exhibited significantly lower SBS than the newly bonded brackets (p<0.05). The main chemical composition of the brackets in both groups was aluminum on the energy-dispersive X-ray spectroscopy. Scanning electron microscopy imaging showed the presence of regular-shaped undercuts or irregular micro-undercuts on the bracket bases which mostly remained intact even after debonding and sandblasting, while coated particles disappeared. The rebonded ceramic brackets with mechanical retention bases exhibited clinically acceptable bond strength regardless of retentive forms.

The best method of reconditioning ceramic brackets to get an optimum shear bond strength compared with new ceramic brackets - Systematic review and meta-analysis of in vitro studies

PURPOSE

Bracket debonding is an undesirable problem during fixed orthodontic treatment. As ceramic brackets have no flexibility, there is no change in the slot dimension. So, reconditioning a ceramic bracket can be done without compromising the quality of treatment and could be a cost-effective measure. The objective of this systematic review is to deduce and validate the best method of reconditioning ceramic bracket in order to get optimum clinical shear bond strength.

MATERIAL AND METHODS

Studies such as randomized controlled trials (RCTs); In vitro studies comparing different interventions with control group, cross sectional studies were included. Electronic databases such as Cochrane database, PubMed, Web of Science, Embase were searched up to July 2022. Grey literature search and cross-referencing/snowballing methods were also used. Two reviewers independently selected studies and assessed the risk of bias using amalgamation of five tools for in vitro studies. Then meta-analysis was performed using random effects model.

RESULTS

Eleven studies were included in which ten studies were considered as good quality studies. According the meta-analysis performed, the best performance in terms of shear bond strength was of new brackets. Among the different reconditioning methods, the meta-analysis showed that the method with the closest bond strength to the new brackets was silicatisation with a mean difference of 6.35MPa (95% CI between 2.39 and 10.31) followed by sandblasting+silane application with a mean difference of 3.36MPa (95% CI between 0.3 and 6.96) compared to other methods.

CONCLUSIONS

Due to the lack of in vivo studies, only in vitro studies were evaluated. The data available from the in vitro studies was considered to be of good quality, leading to the conclusion that the best method for reconditioning debonded ceramic brackets is silicatisation followed by sandblasting and silane application.

Evaluation of Different Adhesive Resin Removal Methods after Debonding Ceramic Orthodontic Molar Tubes: A Scanning Electron Microscope Study

OBJECTIVES

To evaluate and compare the impacts, bond strength, residual adhesive, and time invested on the enamel surface after debonding of recently introduced ceramic buccal molar tubes with different systems.

MATERIALS AND METHODS

Ceramic molar tubes were bonded to fifty-four maxillary molar teeth, and a shear bond strength (SBS) test was performed. The adhesive remnant index (ARI) scores were recorded, and the samples were divided into two groups for adhesive removal with low-speed instruments: tungsten carbide bur or diamond-coated micropolisher point. The time to clean the enamel surfaces was also noted down for each tooth. The enamel surfaces were investigated with scanning electron microscope (SEM) after adhesives were cleaned. Shapiro-Wilk's, Kolmogorov-Smirnov's, and Student's independent t tests were used for statistical analysis.

RESULTS

The mean SBS value of the tested ceramic molar tubes was 9.78 ± 1.85 MPa, and the majority of the samples were scored as ARI 1 and ARI 2. No statistically significant difference between PoGo micropolisher and TCB was found in terms of time values for surface cleaning. The enamel surface characteristics of TCB for adhesive remnant removal resulted in a better enamel surface than the single-step diamond polisher when the samples were investigated by using SEM.

CONCLUSIONS

Ceramic molar tubes may be an enamel-safe product for patients seeking for fully aesthetic orthodontic treatment, if used in carefully handled clinical conditions. One-step polishing systems utilised with low-speed instruments could be used confidentially for cleaning the resin remnants on enamel after orthodontic treatment.

Shear Bond Strength and Bracket Base Morphology of New and Rebonded Orthodontic Ceramic Brackets

The objectives of this study were to (1) to evaluate the shear bond strength (SBS) of two ceramic brackets when new and when rebonded following various bracket base conditioning methods, and (2) to determine bond failure mode relative to bracket base morphology. 100 Symetri Clear^TM (SC) and 100 Radiance Plus^® (RP) ceramic brackets were bonded to bovine incisors and divided into five groups: one group served as controls and four had brackets rebonded following conditioning by: no surface treatment, sealant, sandblasting, and flame then steam. SBS, adhesive remnant index, and bracket base morphology were evaluated. SBS showed no statistical difference between new and rebonded with no surface treatment or sealant (SC brackets) and with sealant or flame and steam (RP brackets). When comparing SC to RP, SBS was higher with SC, no surface treatment, and sandblasted groups. All groups had varying amounts of adhesive left on the tooth, with the sandblasted group having the most. SEM analysis showed that sandblasting damaged the retention features of bracket bases. In conclusion, when rebonded, the SBS of SC brackets that had no surface treatment and both SC and RP brackets that had sealant showed no significant differences to new brackets. Sandblasting damaged the retention features of SC and RP bracket bases, resulting in low SBS.

Comparison of tensile bond strength of new and rebonded Symetri Clear™ ceramic brackets with Transbond™ XT or BluGloo™, with or without surface treatment: An in vitro study

OBJECTIVES

This study sought to determine the bond strength of the Symetri Clear™ bracket after rebonding (reused) for a second and third time.

MATERIALS AND METHODS

Symetri Clear™ mandibular incisor brackets were bonded to bovine incisors and divided into six experimental groups. Two groups underwent tensile bond strength testing, and the remaining four groups were debonded using the manufacturer's recommended plier. Two groups were rebonded twice following surface preparation with Ortho SoloTM and two groups were rebonded twice without surface preparation. The rebonded brackets also underwent tensile bond strength testing after each rebonding event as well as receiving an Adhesive Remnant Index score.

RESULTS

One-way ANOVA found a statistically significant difference in bond strength among the six groups (P<0.0001). Tukey's Studentized Range (HSD, honestly significant difference) Test found significant differences in tensile bond strength of groups which did not undergo surface preparation prior to rebonding. One-way ANOVA found a P-value of 0.2563 and thus no significant difference in ARI among the different groups.

CONCLUSIONS

There was no significant difference in the tensile bond strength of Symetri ClearTM brackets initially bonded with either Transbond™ XT or BluGloo™ and no significant difference between the initial tensile bond strength and the first or second rebond tensile bond strength. Rebonding Symetri Clear™ brackets without surface treatment did show significantly reduced tensile bond strength.

Effect of Displacement of Bracket Position after Initial Placement on Shear Bond Strength: An In vitro Study

Context:

Displacement of bracket after initial placement on tooth surface in the precure phase of bonding influences the shear bond strength.

Aims:

The aim of this study was to evaluate the influence of bracket displacement during the precure phase after initial placement on the tooth surface on shear bond strength of chemical cure and light cure composites.

Settings and Design:

In vitro experimental study.

Subjects and Methods:

Stainless steel orthodontic premolar brackets were bonded to the buccal surfaces of 88 maxillary 1^st premolar teeth. Teeth were divided into four groups: (1) Group 1 – Control group for light-cure composites, (2) Group 2 – Displacement group for light-cure composites, (3) Group 3 – Control group for chemical cure composites, and (4) Group 4 –Displacement group for chemical cure composites. In the control groups, the brackets were bonded with no precure bracket displacement. In the displacement groups, the brackets were bonded with 2 mm precure linear displacement. Photoactivation was carried out for light-cure composites. Shear bond strength tests were carried out using the universal testing machine. Statistical analysis used: Data were analyzed using the one-way analysis of variance test.

Results:

The mean shear bond strength of Groups 1, 2, 3, and 4 were observed to be 14.49 ± 0.75, 13.40 ± 0.61, 12.34 ± 0.53, and 11.55 ± 2.43MPa, respectively, with the displacement groups showing lower shear bond strength when compared to the control groups. Whether displaced or not, chemically cured composites showed lower bond strength when compared to light-cured composites.

Conclusions:

Displacement of brackets during bracket placement seemed to reduce the enamel bond strength after the final positioning of the bracket.

Effect of Er:YAG Laser and Sandblasting in Recycling of Ceramic Brackets

Introduction: This study was performed to determine the shear bond strength of rebonded mechanically retentive ceramic brackets after recycling with Erbium-Doped Yttrium Aluminum Garnet (Er:YAG) laser or sandblasting. Methods: Twenty-eight debonded ceramic brackets plus 14 intact new ceramic brackets were used in this study. Debonded brackets were randomly divided into 2 groups of 14. One group was treated by Er:YAG laser and the other with sandblasting. All the specimens were randomly bonded to 42 intact human upper premolars. The shear bond strength of all specimens was determined with a universal testing machine at a crosshead speed of 0.5 mm/min until bond failure occurred. The recycled bracket base surfaces were observed under a scanning electron microscope (SEM). Analysis of variance (ANOVA) and Tukey tests were used to compare the shear bond strength of the 3 groups. Fisher exact test was used to evaluate the differences in adhesive remnant index (ARI) scores. Results: The highest bond strength belonged to brackets recycled by Sandblasting (16.83 MPa). There was no significant difference between the shear bond strength of laser and control groups. SEM photographs showed differences in 2 recycling methods. The laser recycled bracket appeared to have as well-cleaned base as the new bracket. Although the sandblasted bracket photographs showed no remnant adhesives, remarkable micro-roughening of the base of the bracket was apparent. Conclusion: According to the results of this study, both Er:YAG laser and sandblasting were efficient to mechanically recondition retentive ceramic brackets. Also, Er:YAG laser did not change the design of bracket base while removing the remnant adhesives which might encourage its application in clinical practice.

Effect of different surface treatments for ceramic bracket base on bond strength of rebonded brackets

The aim of this study was to evaluate the shear bond strength of rebonded ceramic brackets after subjecting the bracket base to different treatments. Seventy-five premolars were selected and randomly distributed into five groups (n=15), according to the type of the bracket surface treatment: I, no treatment, first bonding (control); II, sandblasting with aluminum oxide; III, sandblasting + silane; IV, silica coating + silane; and V, silicatization performed in a laboratory (Rocatec system). The brackets were fixed on an enamel surface with Transbond XT resin without acid etching. The brackets were then removed and their bases were subjected to different treatments. Thereafter, the brackets were fixed again to the enamel surface and the specimens were subjected to shear bond strength (SBS) test. The adhesive remnant index (ARI) was then evaluated for each specimen. Data were subjected to ANOVA and Tukey's tests (α=0.05). A statistically significant difference was observed only between Rocatec and the other groups; the Rocatec group showed the lowest SBS values. The highest SBS values were observed for group 1, without any significant difference from the values for groups II, III and IV. Most groups had a higher percentage of failures at the enamel-resin interface (score 1). It was concluded that the surface treatments of rebonded ceramic brackets were effective, with SBS values similar to that of the control group, except Rocatec group.

Analysis of Shear Bond Strength and Morphology of Er:YAG Laser-Recycled Ceramic Orthodontic Brackets

Objective. The aim of this study was to compare the recycling of deboned ceramic brackets via an Er:YAG laser or via the traditional chairside processing methods of flaming and sandblasting; shear bond strength and morphological changes were evaluated in recycled brackets versus new brackets. Materials and Methods. 3M Clarity Self-Ligating Ceramic Brackets with a microcrystalline base were divided into groups subjected to flaming, sandblasting, or exposure to an Er:YAG laser. New ceramic brackets served as a control group. Shear bond strengths were determined with an Electroforce test machine and tested for statistical significance through analysis of variance. Morphological examinations of the recycled ceramic bracket bases were conducted with scanning electron microscopy and confocal laser scanning microscopy. Residue on the bracket base was analyzed with Raman spectroscopy. Results. Faded, dark adhesive was left on recycled bracket bases processed via flaming. Adhesive was thoroughly removed by both sandblasting and exposure to an Er:YAG laser. Compared with new brackets, shear bond strength was lower after sandblasting (p < 0.05), but not after exposure to an Er:YAG laser. The Er:YAG laser caused no damage to the bracket. Conclusion. Er:YAG lasers effectively remove adhesive from the bases of ceramic brackets without damaging them; thus, this method may be preferred over other recycling methods.

A comparative evaluation of the effectiveness of erbium-doped yttrium aluminum garnet laser with other in house refurbishing methods for reconditioning stainless steel and ceramic brackets. An environmental scanning electron microscope and shear bond strength analysis: An in-vitro study

Introduction

Brackets can be recycled by sending them to a commercial recycling company but it is time consuming and the bracket cannot be bonded in the same appointment. Hence in-house methods for recycling of brackets would be beneficial to both the orthodontist and the patient.

Aim

In our study, we compared the shear bond strength of brackets after being recycled with erbium-doped yttrium aluminum garnet (ER:YAG) laser, sandblasting and the thermal method.

Materials and Methods

The study was carried out on 126 extracted premolars. The bonding procedure was performed with mandibular premolar metal and premolar ceramic brackets. Eighty-four teeth were subdivided into three groups for each method of recycling. These groups were further subdivided into two groups of 14 teeth each for the types of brackets used. Prior to the initial bonding the bracket was also viewed under an environmental scanning electron microscope to examine the meshwork of the brackets and once again after the respective recycling methods had been performed.

Results

We found that for stainless steel brackets, the sandblasting method was superior to the ER:YAG laser, as the recycled brackets showed a higher shear bond strength. For ceramic brackets the ER:YAG laser recycled group had the highest recycled shear bond strength therefore was the best method of recycling ceramic brackets.

Shear bond strength and morphological analysis of KrF laser-recycled metal brackets

OBJECTIVE

The aim of this study was to compare the effect of a KrF excimer laser versus traditional chairside deboned bracket processing methods of grinding, flaming, and sandblasting on the shear bond strength and morphological change of recycled brackets.

BACKGROUND DATA

Bracket dislodgement happens frequently in orthodontic treatment.

METHODS

The Victory Series bracket with a foil-mesh base and the Mini Sprint bracket with a raised base were chosen in this research. Grind, flame, sandblast, and laser groups acted as the experimental groups, and the new bracket group served as control. The shear bond strengths were determined with an Electroforce test machine and statistically tested by an analysis of variance (ANOVA). Morphological examinations of the recycled bracket bases were conducted with scanning electron microscopy and confocal laser scanning microscopy. Bracket base residue content was analyzed using Raman spectroscopy.

RESULTS

The study showed that adhesive was left on the recycled bracket base processed by grinding and flaming, with significantly decreased shear bond strength (p<0.05). Sandblasting and KrF excimer lasering both thoroughly removed the adhesive. Shear bond strength decreased with sandblasting in the Victory bracket but not in the Mini Sprint bracket. Shear bond strength of KrF-lasered recycled brackets did not differ statistically from that of both kinds of new brackets. The study also showed that KrF excimer laser caused limited damage to the bracket.

CONCLUSIONS

The KrF excimer laser can remove adhesive on the two different bracket bases effectively, causing little damage to the bracket; therefore, it is a superior bracket refurbishing method worth further study.

Heat treatment following surface silanization in rebonded tribochemical silica-coated ceramic brackets: shear bond strength analysis

OBJECTIVE

This study aimed to evaluate the effects of heat treatment on the tribochemical silica coating and silane surface conditioning and the bond strength of rebonded alumina monocrystalline brackets.

MATERIAL AND METHODS

Sixty alumina monocrystalline brackets were randomly divided according to adhesive base surface treatments (n=20): Gc, no treatment (control); Gt, tribochemical silica coating + silane application; Gh, as per Gt + post-heat treatment (air flux at 100ºC for 60 s). Brackets were bonded to the enamel premolars surface with a light-polymerized resin and stored in distilled water at 37ºC for 100 days. Additionally, half the specimens of each group were thermocycled (6,000 cycles between 5-55ºC) (TC). The specimens were submitted to the shear bond strength (SBS) test using a universal testing machine (1 mm/min). Failure mode was assessed using optical and scanning electron microscopy (SEM), together with the surface roughness (Ra) of the resin cement in the bracket using interference microscopy (IM). 2-way ANOVA and the Tukey test were used to compare the data (p>0.05).

RESULTS

The strategies used to treat the bracket surface had an effect on the SBS results (p=0.0), but thermocycling did not (p=0.6974). Considering the SBS results (MPa), Gh-TC and Gc showed the highest values (27.59±6.4 and 27.18±2.9) and Gt-TC showed the lowest (8.45±6.7). For the Ra parameter, ANOVA revealed that the aging method had an effect (p=0.0157) but the surface treatments did not (p=0.458). For the thermocycled and non-thermocycled groups, Ra (µm) was 0.69±0.16 and 1.12±0.52, respectively. The most frequent failure mode exhibited was mixed failure involving the enamel-resin-bracket interfaces.

CONCLUSION

Regardless of the aging method, Gh promoted similar SBS results to Gc, suggesting that rebonded ceramic brackets are a more effective strategy.

Effects of silica coating and silane surface conditioning on the bond strength of rebonded metal and ceramic brackets

Objective

The aim of this study was to evaluate the effects of tribochemical silica coating and silane surface conditioning on the bond strength of rebonded metal and ceramic brackets.

Material and Methods

Twenty debonded metal and 20 debonded ceramic brackets were randomly assigned to receive one of the following surface treatments (n=10 for each group): (1) sandblasting (control); (2) tribochemical silica coating combined with silane. Brackets were rebonded to the enamel surface on the labial and lingual sides of premolars with a light-polymerized resin composite. All specimens were stored in distilled water for 1 week and then thermocycled (5,000 cycles) between 5-55°C. Shear bond strength values were measured using a universal testing machine. Student's t-test was used to compare the data (α=0.05). Failure mode was assessed using a stereomicroscope, and the treated and non-treated bracket surfaces were observed by scanning electron microscopy.

Results

Rebonded ceramic brackets treated with silica coating followed by silanization had significantly greater bond strength values (17.7±4.4 MPa) than the sandblasting group (2.4±0.8 MPa, P<0.001). No significant difference was observed between the rebonded metal brackets treated with silica coating with silanization (15±3.9 MPa) and the sandblasted brackets (13.6±3.9 MPa). Treated rebonded ceramic specimens primarily exhibited cohesive failure in resin and adhesive failure at the enamel-adhesive interface.

Conclusions

In comparison to sandblasting, silica coating with aluminum trioxide particles followed by silanization resulted in higher bond strengths of rebonded ceramic brackets.

Rebonding performance of different ceramic brackets conditioned with a new silane coupling agent

The objective of this study was to investigate the rebonding effect of a new silane coupling agent on various ceramic brackets bonded to ceramic specimen. Different ceramic brackets (Fascination 2, Clarity SL, and In-OvationC) were assigned to three groups: rebonding with new silane coupling agent, rebonding with conventional silane coupling agent, or regular bonding as control (n = 16). Bracket adhesion was calculated with a shear test in a universal testing machine. The bracket-composite-ceramic interface was evaluated using the adhesive remnant index score. One-way analysis of variance was applied for inferential statistics. Rebonding with the new silane coupling agent resulted in high shear bond strengths (SBSs; mean values: 37.44-41.24 MPa) and ceramic specimen fractures. Rebonding with the conventional silane coupling agent resulted in significantly (P < 0.001) lower clinically adequate SBS (mean values: 20.20-29.92 MPa) with the least ceramic specimen fractures. Regularly bonded ceramic brackets resulted in clinically adequate to high SBS (mean values: 17.06-41.56 MPa) depending on their bracket base design. Rebonded ceramic brackets showed sufficient SBS to ceramic specimen surfaces. However, increased bracket adhesion was associated with a risk of ceramic specimen surface damage. Therefore, ceramic brackets rebonded with the new silane coupling should be debonded cautiously using alternative debonding methods.

Shear bond strength of rebonded brackets after removal of adhesives with Er,Cr:YSGG laser

This study was conducted to examine the bond strength of rebonded orthodontic brackets after adhesive residuals on the surface of the bracket bases were removed by Er,Cr:YSGG lasers. Seventy-six brackets bonded to premolars with a self-etching primer adhesive system were equally divided into four groups after the first debonding with the bracket bases (Group 1) untreated, and treated by (Group 2) Er,Cr:YSGG laser, (Group 3) sandblaster, and (Group 4) Er,Cr:YSGG laser/sandblaster. The treated brackets were rebonded to the new premolars in the same manner as the first-stage experiment. The shear bond strengths were measured, with the bonding/debonding procedures repeated once after the first debonding, and the bracket/adhesive failure modes were evaluated after each debonding. The treated bracket base surfaces were observed under a scanning electron microscopy (SEM). The mean rebond strengths were significantly lower in group 1 than in other groups, and there were no significant differences between the other groups. The mean initial bond strength was significantly higher than the mean rebond strength in group 1 but there was no significant difference between the two in the other three groups. Failures at the bracket-adhesive interface occurred frequently at second debonding in group 1. Under the SEM, residual adhesive was removed from the bracket bases by Er,Cr:YSGG laser, while adhesive remnant was seen underneath the meshwork of the bracket bases and microroughness appeared on the meshwork after sandblasting. Er,Cr:YSGG laser certainly could serve the purpose of promoting the use of recycled orthodontic brackets.

Bond strength and debonding characteristics of a new ceramic bracket

INTRODUCTION

The purposes of this study were to evaluate the shear bond strength of a new collapsible monocrystalline bracket (Inspire, Ormco, Orange, Calif) and compare it with another collapsible ceramic bracket (Clarity, 3M Unitek, Monrovia, Calif) and a metal bracket; to examine the modes of failure after shear bond strength testing; and to observe the tooth surface after debonding the ceramic brackets with pliers.

METHODS

One hundred extracted human premolars were selected for bonding. Three types of brackets and 2 orthodontic adhesives (Transbond XT, 3M Unitek; and Enlight, Ormco) were used. After bonding, all samples were placed in a distilled water bath at 37 degrees C for 24 hours. The shear bond strength of 60 samples was measured, and the remaining 40 samples with ceramic brackets were debonded with pliers.

RESULTS

No statistically significant differences in bond strengths among the different combinations of brackets and adhesives were found (P > .05). The mode of failure after debonding by either shear bond strength testing or with pliers was predominantly at the bracket/adhesive interface in all groups. Enamel and bracket fractures were noted in 2 and 5 of 20 samples for Inspire, and 1 and 0 of 20 samples for Clarity after debonding with pliers.

CONCLUSIONS

Bond strength and mode of failure of Inspire were similar to those of Clarity, but the risk of bracket fracture after debonding for Inspire was greater.

Effect of saliva on shear bond strength of an orthodontic adhesive used with moisture-insensitive and self-etching primers

The purpose of this study was to investigate the effect of saliva contamination on the shear bond strength of an orthodontic adhesive used with Transbond Moisture-Insensitive Primer (MIP, 3M Unitek, Monrovia, Calif) and Transbond Plus Self-Etching Primer (SEP, 3M Unitek). Hydrophobic Transbond XT primer (XT, 3M Unitek) was used as a control. A total of 162 extracted premolars were collected and divided equally into 9 groups of 18 teeth each, and brackets were bonded with Transbond XT adhesive (3M Unitek) under different experimental conditions: (1) control: etch/dry/XT, (2) etch/dry/MIP, (3) etch/dry/MIP/wet (saliva)/MIP, (4) etch/wet/MIP, (5) etch/wet/MIP/wet/MIP, (6) dry/SEP, (7) dry/SEP/wet/SEP, (8) wet/SEP, and (9) wet/SEP/wet/SEP. Shear bond strength of each sample was examined with a testing machine. The results showed that the control group had the highest mean shear bond strength (group 1, 21.3 +/- 6.8 MPa), followed by the MIP group in a dry field (group 2, 20.7 +/- 5.0 MPa). No significant difference was found between groups 1 and 2. Groups 3 through 9 had similar mean strengths, ranging from 12.7 to 15.0 MPa (P >.05), which were significantly lower than in groups 1 and 2 (P <.05). There was no significant difference in bond-failure site among the 9 groups. It was concluded that (1) Transbond XT adhesive with Transbond XT primer and MIP in a dry field yields similar bond strengths, which are greater than all other groups, (2) saliva contamination significantly lowers the bond strength of Transbond MIP, (3) saliva has no effect on the bond strength of Transbond SEP, (4) Transbond XT adhesive with Transbond MIP and SEP might have clinically acceptable bond strengths in either dry or wet fields.