Shear bond strength of brackets bonded with hydrophilic and hydrophobic bond systems under contamination

Objective:To compare, in vitro, the shear bond strength (SBS) of two bond systems: Transbond XT/XT primer (TXT/XT) and Transbond Plus Color Change/Transbond Self Etching Primer (TPCC/TSEP).Materials and Methods:Each system was examined under four enamel surface conditions (dry, water, saliva, and blood), and 160 bovine teeth were divided into eight groups of 20 according to enamel surface condition. Group 1 used TPCC/TSEP and Group 2 used TXT/XT under dry conditions; Group 3 used TPCC/TSEP and Group 4 used TXT/XT with water; Group 5 used TPCC/TSEP and Group 6 used TXT/XT under saliva; and Group 7 used TPCC/TSEP and Group 8 used TXT/XT with blood. Brackets were bonded, and the samples were thermocycled 500 times between 5°C and 55°C; they were then submitted to a shear bond test with a universal testing machine with a 50 kgf load cell at 5 mm/min.Results:Although water and saliva affected TXT/XT more than they affected TPCC/TSEP, there were no significant differences among the groups (Groups 3 and 4: P  =  .940; Groups 3 and 5 and Groups 4 and 6: P  =  1.000; Groups 3 and 6: P  =  .988; Groups 4 and 5: P  =  .690; and Groups 5 and 6: P  =  .861).Conclusions:The presence of blood resulted in the lowest SBS from both bond systems, but especially from TXT/XT. TPCC/TSEP resulted in a higher SBS than TXT/XT under all conditions except the dry enamel surface.     

Effect of adhesion boosters on indirect bracket bonding

Objective:To determine the influence of two adhesion boosters on shear bond strength and on the bond failure location of indirectly bonded brackets.Materials and Methods:Sixty bovine incisors were randomly divided into three groups (n  =  20), and their buccal faces were etched using 37% phosphoric acid. In group 1 (control), brackets were indirectly bonded using only Sondhi adhesive. In groups 2 and 3, the adhesion boosters Enhance Adhesion Booster and Assure Universal Bonding Resin, respectively, were applied before bonding with Sondhi. Maximum bond strength was measured with a universal testing machine, and the location of bond failure was evaluated using the Adhesive Remnant Index (ARI). One-way analysis of variance followed by the Tukey test (P < .05) was used to compare the shear bond strength among groups, and the differences in ARI scores were evaluated using the Kruskal-Wallis test (P < .05). The Pearson correlation coefficient was calculated to determine whether there was any correlation between bond strength and ARI scores.Results:The mean shear bond strength in group 3 was significantly higher (P < .01) than in the other groups. Evaluation of the locations of bond failure revealed differences (P < .05) among the three groups. There was a moderate correlation between bond strength and ARI scores within group 3 (r  =  0.5860, P < .01).Conclusion:In vitro shear bond strength was acceptable in all groups. The use of the Assure adhesion booster significantly increased both the shear bond strength of indirectly bonded brackets and the amount of adhesive that remained on the enamel after bracket debonding.     

Effects of remineralization procedures on shear bond strengths of brackets bonded to demineralized enamel surfaces with self-etch systems

Objective:To compare the effects of different remineralization procedures on the surface roughness of teeth, shear bond strengths (SBSs), and Adhesive Remnant Index scores of self-etching primer (SEP) used to bond orthodontic brackets to previously treated demineralized enamel surfaces.Materials and Methods:A total of 140 extracted human premolar teeth were randomly divided into seven equal groups. Group I was the control group. A demineralization procedure was performed in the other six groups. A remineralization procedure was performed before bonding by using casein phosphopeptide-amorphous calcium phosphate, fluoride, a microabrasion mixture (18% hydrochloric acid-fine pumice), a microabrasion agent, and resin infiltration in groups III to VII. Brackets were bonded using a self-etching primer/adhesive system. The specimens were tested for SBS. The roughness and morphology of the enamel surfaces were analyzed using profilometer and scanning electron microscopy. Data were analyzed with analysis of variance, Tukey, and G-tests at the α  =  .05 level.Results:Significant differences were found in the SBS values among the seven groups (F  =  32.69, P  =  .003). The lowest SBS value was found in group II (2.62 ± 1.46 MPa). No significant differences were found between groups I, III, and VII, between groups III and IV, or between groups V and VI. The differences in the roughness values were statistically significant among the groups (P  =  .002).Conclusions:Remineralization procedures restore the decreased SBS of orthodontic brackets and decrease surface roughness caused by enamel demineralization. SEPs provide clinically acceptable SBS values for bonding orthodontic brackets to previously treated demineralized enamel surfaces.     

Effects of surface treatment and artificial aging on the shear bond strength of orthodontic brackets bonded to four different provisional restorations

Objective:To evaluate the combined effects of material type, surface treatment, and thermocycling on the bond strength of orthodontic brackets to materials used for the fabrication of provisional crowns.Materials and Methods:Four materials were included in this study (ProTemp, Trim Plus, Trim II, and Superpont C+B). Sixty cylindrical specimens (1 × 3 cm) were prepared from each material and equally divided into three groups. The first group was ground with silica carbide paper, the second was polished with pumice, and the last group was sandblasted with 50-µm aluminum oxide particles. Stainless-steel maxillary central incisor brackets (Victory Series, 3M) were bonded to the provisional material specimens with Transbond XT light-cured composite resin, and half of the specimens from each group were thermocycled 500 times in 5°C and 55°C water baths. Then the brackets were debonded with shear testing, and the results were statistically analyzed by three-way analysis of variance and Tukey''s multiple-comparison tests at α  =  0.05. Adhesive Remnant Index (ARI) was also identified.Results:Before and after thermocycling, ProTemp materials showed the highest shear bond strength with orthodontic brackets (10.3 and 13.1 MPa, respectively). The statistical analysis indicated an interaction among the three independent variables (P < .05) and statistically significant differences in bond strength among provisional materials (P < .001), surface treatments (P < .001), and thermocycling (P < .05). According to the ARI, most groups demonstrated adhesive failure.Conclusions:The provisional material type, surface treatment, and artificial aging have a significant effect on bond strength. Sandblasting treatment exerts a beneficial effect on shear bond strength.     

Shear bond strength of orthodontic resins after caries infiltrant preconditioning

Objective:To investigate the influence of caries infiltrant preconditioning on the shear bond strength of orthodontic resin cements on sound and demineralized enamel.Materials and Methods:Stainless-steel brackets were bonded to sound or artificially demineralized (14 d, acidic buffer, pH 5.0) bovine enamel specimens using a resin cement or a combination of caries infiltrant preconditioning (Icon, DMG) and the respective resin cement (light-curing composite: Heliosit Orthodontic, Transbond XT, using either Transbond XT Primer or Transbond Plus Self Etching Primer; light-curing resin-modified glass ionomer cement: Fuji Ortho; or self-curing composite: Concise Orthodontic Bonding System). Each group consisted of 15 specimens. Shear bond strength was evaluated after thermo-cycling (10,000×, 5°C to 55°C) at a crosshead speed of 1 mm/min, and data were statistically analyzed by analysis of variance, Mann-Whitney test, and Weibull statistics. Adhesive Remnant Index (ARI) scores and enamel fractures were determined at 25× magnification and were statistically analyzed by regression analyses (P < .05).Results:The caries infiltrant system significantly increased the shear bond strength of Transbond XT Primer, Transbond Plus Self Etching Primer, and Fuji Ortho in sound specimens, and of all resin cements except for the Concise Orthodontic Bonding System in demineralized enamel. Overall, caries infiltrant preconditioning decreased significantly the number of enamel fractures, but it did not affect ARI scores.Conclusion:Preconditioning of sound and demineralized enamel with the caries infiltrant system did not impair but rather increased the shear bond strength of most orthodontic resin cements while decreasing the risk of enamel fracture at debonding.     

In vitro evaluation of self-etch bonding in orthodontics using cyclic fatigue: Part I,Shear testing methods

Objective:To evaluate the bond strength of a self-etch bonding system using static loading and cyclic fatigue with shear testing. This is a two-part evaluation; the first part will evaluate shear testing, the second part tensile testing.Materials and Methods:Bovine teeth (n  =  82) were randomly distributed to either a self-etch (Transbond Plus) or total-etch (37% phosphoric-acid + Transbond XT) group. The static shear (SSBS) and cyclic shear (CSBS) bond strengths were measured 24 hours after the bonding of mesh-based brackets. The adhesive remnant index (ARI) and failure sites were evaluated.Results:The mean SSBS was 34.25 ± 9.21 and 24.64 ± 9.42 MPa for the total- and self-etch groups, respectively. CSBS was 24.07 ± 0.65 MPa and 18.92 ± 1.08 MPa for the total- and self-etch groups, respectively. Cyclic loading produced lower bond strengths compared to static testing for both adhesives; the difference was only statistically significant for the total-etch system. Comparison of the two materials showed a statistically significant difference between the two techniques. The total-etch had higher bond strengths than the self-etch bonding system. The samples showed a predominance of ARI scored of 2 and 1, and their bonding failure sites were cohesive within the composite.Conclusion:Cyclic loading, simulating occlusal forces, reduces the bond strength of both bonding systems. Even though the self-etch bonding system had lower shear bond strength than the total-etch system, both were still clinically acceptable.     

Adjunctive use of fluoride rinsing and brush-on gel increased incipient caries-like lesion remineralization compared with fluoride toothpaste alone in situ

Objective: The objective of this study was to compare the remineralizing effect of sodium fluoride (NaF) mouth rinse or NaF gel as an adjunct to NaF dentifrice on incipient caries-like lesions in an in situ cross-over design study, with three sessions of 30 days each.

Materials and methods: Orthodontic brackets with artificial demineralized enamel slabs were attached to the upper first molars of 12 participants. A set of 3 test specimens from the same tooth was randomly assigned to each participant and allocated into three 30-day sessions: 1) brushing with 0.22% NaF dentifrice 2 times/day (F dentifrice), 2) brushing with 0.22% NaF dentifrice 2 times/day+?rinsing with 0.05% NaF before bedtime (F mouth rinse), 3) brushing with 0.22% NaF dentifrice 2 times/day?+?brushing with 1.1% NaF gel before bedtime (F brush-on gel). The mineral gain and lesion depth of the specimens were evaluated by micro-computed tomography.

Results: The mean mineral gain from the NaF mouth rinse and the NaF brush-on gel was similar, but greater than that from the NaF dentifrice (p?p?Conclusions: Both 0.05% NaF mouth rinse and 1.1% NaF brush-on gel, used at bedtime, increased incipient caries-like lesion remineralization in situ in combination with brushing with NaF dentifrice twice a day.     

Caries infiltrant combined with conventional adhesives for sealing sound enamel in vitro

Objective:To test the null hypothesis that combining low-viscosity caries infiltrant with conventional adhesive resins would not improve sealing of sound enamel against demineralization in vitro.Materials and Methods:Bovine enamel discs (N  =  60) with diameter of 3 mm were randomly assigned to six groups (n  =  10). The discs were etched with 37% phosphoric acid for 30 seconds and treated with resins of different monomer content forming the following groups: (1) Icon (DMG), (2) Transbond XT Primer (3M ESPE), (3) Heliobond (Ivoclar Vivadent), (4) Icon + Transbond XT Primer, and (5) Icon + Heliobond. Untreated etched samples served as the negative control. Specimens were subjected to demineralization by immersion in hydrochloric acid (pH 2.6) for 80 hours. Calcium dissolution into the acid was assessed by colorimetric analysis using Arsenazo III method at 16-hour intervals. Groups presenting high protection against demineralization were subjected to further acidic challenge for 15 days with calcium measurements repeated at 24-hour intervals. Data were analyzed by Kruskal-Wallis test and Mann-Whitney U-test.Results:Untreated specimens showed the highest amount of demineralization. Icon and Transbond XT primer decreased the mineral loss significantly compared to the control. Heliobond performed significantly better than both Icon and Transbond XT primer. Combination of Icon both with Transbond XT primer or Heliobond served as the best protective measures and maintained the protective effect for the additional 15-day acidic challenge.Conclusions:Within the limitations of this in vitro study, it could be concluded that the use of low-viscosity caries infiltrant prior to application of the tested conventional adhesives increases their protective effect against demineralization.     

Analysis of the effect of CPP-ACP tooth mousse on enamel remineralization by circularly polarized images

Objective:To evaluate the effect of casein phosphopeptide–amorphous calcium phosphate tooth mousse on the remineralization of bovine incisor by circularly polarized images.Methods:Eighty bovine incisors, each with a 4 × 4 mm artificially demineralized area, were used. The samples were divided into four groups: Group A, casein phosphopeptide–amorphous calcium phosphate tooth mousse; Group B, fluoride toothpaste; Group C, casein phosphopeptide–amorphous calcium phosphate tooth mousse and fluoride toothpaste; and Group D, no treatment. Circularly polarized images were taken after the specimens were treated for 3, 6, 9, or 12 weeks, and the size of the demineralized area and the mean grey level were measured. Data analysis was done using repeated measures variance analysis. Pearson correlation coefficients were computed to evaluate the correlation between the size of the demineralized area and the mean grey level.Results:In all four groups, the size of the demineralized area and the mean grey level declined with time. The size of the demineralized area of Group C was significantly smaller than that of Group A at the end of the third and sixth weeks (P  =  .039, P  =  .000, respectively), and the mean grey level of Group C was lower than that of Group A at the end of the 6th and 12th weeks (P  =  .037, P  =  .004, respectively). At the end of the 6th, 9th, and 12th weeks, the size of the demineralized area of Group C was smaller (P  =  .000, P  =  .005, P  =  .005, respectively) and the mean grey level was lower (P  =  .000) than those of Group B. No statistically significant correlations were detected between the size of the demineralized area and the mean grey level.Conclusion:Casein phosphopeptide–amorphous calcium phosphate tooth mousse can reduce the size and mean grey level of demineralized areas and promote the remineralization of bovine enamel. Combined application with fluoride toothpaste strengthens the effect.     

Adhesive performance of precoated brackets after expiration

Objective:To evaluate adhesive performance in terms of debonding forces of precoated metal and ceramic brackets 4 years after expiration.Materials and Methods:Buccal and lingual surfaces of embedded extracted maxillary premolars were etched with 34% Tooth Conditioner Gel (Dentsply Caulk, Milford, Del), rinsed, and dried. Transbond MIP (3M Unitek, Monrovia, Calif) was applied prior to placing adhesive precoated brackets (APC II Victory stainless steel and APC Plus Clarity ceramic brackets, 3M Unitek). The preexpiration brackets had 29–35 months before, and the postexpiration brackets were 45–52 months past, their expiration dates. Sample size was 17–21 per group. Debonding forces were determined by subjecting the bonded brackets to a shear force in a universal testing machine. Debonding forces were compared using two-way ANOVA. Debonded surfaces were examined under a stereomicroscope to determine failure modes, which were compared using the chi-square test.Results:No statistically significant difference was found in debonding forces (P  =  .8581) or failure modes (P  =  .4538) between expired and unexpired brackets. Metal brackets required statistically significantly higher debonding forces than did ceramic brackets (P  =  .0001). For both expired and unexpired brackets, failure modes were mostly cohesive in the adhesive layer for ceramic brackets, and mixed between adhesive and cohesive failure in the adhesive layer for metal brackets.Conclusions:Adhesive precoated brackets did not have any reduction in enamel-adhesion properties up to 4 years after their expiration date. Extended shelf life testing for precoated dental brackets may be worth considering.     

Effect of fluoride on root resorption following heavy and light orthodontic force application for 4 weeks and 12 weeks of retention

Objective:To evaluate the null hypothesis that fluoride intake via drinking water has no effect on orthodontic root resorption in humans after orthodontic force application for 4 weeks and 12 weeks of retention.Materials and Methods:Forty-eight patients who required maxillary premolar extractions as part of their orthodontic treatment were selected from two cities in Turkey. These cities had a high and low fluoride concentration in public water of ≥2 pm and ≤0.05 pm, respectively. The patients were randomly separated into four groups of 12 each: group 1HH, high fluoride (≥2 ppm) and heavy force (225 g); group 2LH, low fluoride (≤0.05 ppm) and heavy force; group 3HL, high fluoride and light force (25 g); and group 4LL, low fluoride and light force. Light or heavy buccal tipping force was applied on the upper first premolars for 28 days. At day 28, the left premolars were extracted (positive control side); the right premolars (experimental side) were extracted after 12 weeks of retention. The samples were analyzed with microcomputed tomography.Results:On the positive control side, under heavy force application, the high fluoride groups exhibited less root resorption (P  =  .015). On the experimental side, it was found that fluoride reduced the total volume of root resorption craters; however, this effect was not statistically significant (P  =  .237). Moreover, the results revealed that under heavy force application experimental teeth exhibited more root resorption than positive control groups.Conclusion:The null hypothesis could not be rejected. High fluoride intake from public water did not have a beneficial effect on the severity of root resorption after a 4-week orthodontic force application and 12 weeks of passive retention.     

Laterality of Asymmetry in Movements of the Corners of the Mouth during Voluntary Smile

Objectives:To examine (1) the laterality of asymmetry in movements of the right and left corners of the mouth in space during voluntary smile and (2) the laterality of asymmetry in relation to the difference between the right and left hemiface size and the handedness.Materials and Methods:Participants were 155 volunteer Japanese female adults. They were categorized into the symmetric group (n  =  120) and the right-side hemiface dominant group (n  =  26) according to the hemiface size. In addition, the symmetric group was categorized into the right-handed group (n  =  98) and the left-handed group (n  =  22) according to the Edinburgh Handedness Inventory. Position vectors of the right and left corners of the mouth were obtained from the three-dimensional facial images for the rest, the maximal lip corner retraction, and the portrait smile. The displacements of the right and left corners of the mouth for each expression and the proportions of the subjects with the right- and left-sided laterality were compared.Results:The left corner of the mouth showed significantly greater displacement (P < .01) than the right in the symmetric group for the portrait smile. The left-sided laterality was found regardless of the handedness.Conclusions:Displacements of the right and left corners of the mouth during voluntary smile were asymmetric, and the left-sided laterality was found. Also, the laterality of the facedness differed in relation to the hemiface size, but was not related to the handedness.     

Physical Properties of Conventional and Super Slick Elastomeric Ligatures after Intraoral Use

Objective:To investigate the change in the physical properties of conventional and Super Slick elastomeric ligatures after they have been in the mouth.Materials and Methods:Nine healthy volunteers took part. One orthodontic bracket was bonded to a premolar tooth in each of the four quadrants of the mouth. Two conventional and two Super Slick elastomeric ligatures were placed at random locations on either side of the mouth. The ligatures were collected after various time intervals and tested using an Instron Universal testing machine. The two outcome measures were failure load and the static frictional resistance.Results:The failure load for conventional ligatures was reduced to 67% of the original value after 6 weeks in situ. Super Slick elastomeric ligatures showed a comparable reduction after 6 weeks in situ (63% of original value). There were no statistical differences in the static friction between conventional and Super Slick elastomerics that had been in situ for either 24 hours (P  =  .686) or 6 weeks (P  =  .416). There was a good correlation between failure load and static friction (r  =  .49).Conclusions:There were statistically significant differences in the failure loads of elastomerics that had not be placed in the mouth and those that had been in the mouth for 6 weeks. There were no differences in the static frictional forces produced by conventional and Super Slick ligatures either before or after they had been placed in the mouth. There appears to be a direct proportional relationship between failure load and static friction of elastomeric ligatures.     

Changes in temporomandibular joint disc position and form following Herbst and fixed orthodontic treatment

Objective:To determine the changes in the position and form of the temporomandibular joint articular disc in adolescents with Class II division 1 malocclusion and mandibular retrognathism treated with the Herbst appliance (phase I) and fixed orthodontic appliance (phase II).Materials and Methods:Thirty-two consecutive adolescents went through phase I of treatment and 23 completed phase II. The temporomandibular joints were evaluated qualitatively by means of magnetic resonance images at the beginning of treatment (T1), during phase I (T2), at the end of phase I (T3), and at the end of phase II (T4).Results:Significant changes in disc position were not observed with the mouth closed between T1 × T3 (P  =  .317), T3 × T4 (P  =  .287), or T1 × T4 (P  =  .261). At T2, on average, the disc was positioned regressively. With the mouth open, no difference was observed between T1 × T3 (P  =  .223) or T1 × T4 (P  =  .082). We did observe a significant difference between T3 × T4 (P < .05). Significant changes in the disc form were found with the mouth closed between T1 × T2 (P < .001) and T2 × T3 (P < .001).Conclusions:At the end of the two-phase treatment, in general terms, the position and form of the initial articular discs were maintained; however, in some temporomandibular joints some seemingly adverse effects were observed at T4.     

Orthodontic bracket bonding without previous adhesive priming: A meta-regression analysis

Objective:To determine the consensus among studies that adhesive resin application improves the bond strength of orthodontic brackets and the association of methodological variables on the influence of bond strength outcome.Materials and Methods:In vitro studies were selected to answer whether adhesive resin application increases the immediate shear bond strength of metal orthodontic brackets bonded with a photo-cured orthodontic adhesive. Studies included were those comparing a group having adhesive resin to a group without adhesive resin with the primary outcome measurement shear bond strength in MPa. A systematic electronic search was performed in PubMed and Scopus databases.Results:Nine studies were included in the analysis. Based on the pooled data and due to a high heterogeneity among studies (I²  =  93.3), a meta-regression analysis was conducted. The analysis demonstrated that five experimental conditions explained 86.1% of heterogeneity and four of them had significantly affected in vitro shear bond testing. The shear bond strength of metal brackets was not significantly affected when bonded with adhesive resin, when compared to those without adhesive resin.Conclusions:The adhesive resin application can be set aside during metal bracket bonding to enamel regardless of the type of orthodontic adhesive used.     

Effects of different fluoride recharging protocols on fluoride ion release from various orthodontic adhesives

Objective

The purpose of this study was to find the most effective fluoride recharging protocol for orthodontic adhesives.

Methods

Five orthodontic adhesives were used: a non-fluoride-releasing composite, a fluoride-releasing composite, a polyacid-modified composite (compomer), and two resin-modified glass-ionomer cements (RMGICs). Each specimen was placed into deionized water (DW) and the initial fluoride ion release was measured for 2 months. Each specimen was then subjected to four different treatments to simulate a fluoride recharge: 1000 ppm NaF solution, acidulated phosphate fluoride gel (APF), fluoride-containing dentifrice and DW (control). After topical fluoride treatment, each specimen was submitted to fluoride re-release tests.

Results

Fluoride-containing adhesives initially showed higher rates of fluoride ion release, but significantly declined to lower levels. The overall cumulative fluoride ion release during the initial period was RMGICs > compomer > fluoride-containing composite > non-fluoride-releasing composite. After topical fluoride treatment, the amount of fluoride ion re-released was proportional to the amount of fluoride ion previously released from the adhesives. However, the amount of fluoride ions released only lasted for 2 days and then returned to the levels before fluoride application. The overall cumulative fluoride ion re-release according to the fluoride treatments was APF and NaF solution > dentifrice.

Conclusion

This study suggests that using the combination of RMGICs and a fluoride-containing mouth rinse solution is the most effective protocol for long-term fluoride re-release from orthodontic adhesives, given the difficulty of routine use of APF at home, although all topical fluoride treatments can recharge fluoride ion in adhesives.     

Bracket bond strength comparison between new unfilled experimental self-etching primer adhesive and conventional filled adhesives

Objective:To determine if a new unfilled experimental self-etching primer (SEP) adhesive system (SBP-40TX + C&B Metabond) that incorporates a methyl methacrylate–based 4-META/TBB (4-methacryloxyethyl trimellitate anhydride tri-n-butyl borane) resin can provide adequate shear bond strength (SBS) when used for bonding orthodontic brackets.Methods and Materials:Forty-eight human maxillary premolars were randomly divided into three groups of 16 specimens each. Brackets were bonded with three bonding systems. A filled Bis-GMA/TEGDM (triethylene glycol dimethacrylate)–based SEP adhesive system (Transbond Plus) and an unfilled conventional etch-and-rinse adhesive system (C&B Metabond) were used for comparison. The SBS for each sample was examined with a universal testing machine, and the Adhesive Remnant Index score was calculated. Enamel surfaces after conditioning were examined using a scanning electron microscope. Data were compared by one-way analysis of variance and a χ² test.Results:The experimental SEP showed a milder etching pattern than Transbond Plus SEP. No statistically significant differences in the mean SBS were found between the specimens bonded with the unfilled experimental SEP adhesive system (10.0 MPa) and the filled SEP adhesive system (8.7 MPa). The unfilled experimental SEP adhesive system showed less residual adhesive than the filled SEP adhesive system.Conclusions:The unfilled experimental SEP adhesive system showed a clinically sufficient SBS that was equivalent to the filled SEP adhesive system.     

Effects of different etching methods and bonding procedures on shear bond strength of orthodontic metal brackets applied to different CAD/CAM ceramic materials

Objective:To investigate the shear bond strength (SBS) of orthodontic metal brackets applied to different types of ceramic surfaces treated with different etching procedures and bonding agents.Materials and Methods:Monolithic CAD/CAM ceramic specimens (N = 120; n = 40 each group) of feldspathic ceramic Vita Mark II, resin nanoceramic Lava Ultimate, and hybrid ceramic Vita Enamic were fabricated (14 × 12 × 3 mm). Ceramic specimens were separated into four subgroups (n = 10) according to type of surface treatment and bonding onto the ceramic surface. Within each group, four subgroups were prepared by phosphoric acid, hydrofluoric acid, Transbond XT primer, and Clearfill Ceramic primer. Mandibular central incisor metal brackets were bonded with light-cure composite. The SBS data were analyzed using three-way analysis of variance (ANOVA) and Tukey HSD tests.Results:The highest SBS was found in the Vita Enamic group, which is a hybrid ceramic, etched with hydrofluoric acid and applied Transbond XT Adhesive primer (7.28 ± 2.49 MPa). The lowest SBS was found in the Lava Ultimate group, which is a resin nano-ceramic etched with hydrofluoric acid and applied Clearfill ceramic primer (2.20 ± 1.21 MPa).Conclusions:CAD/CAM material types and bonding procedures affected bond strength (P < .05), but the etching procedure did not (P > .05). The use of Transbond XT as a primer bonding agent resulted in higher SBS.     

Effect of enamel protective agents on shear bond strength of orthodontic brackets

Background

This paper aimed to study the effect of two enamel protective agents on the shear bond strength (SBS) of orthodontic brackets bonded with conventional and self-etching primer (SEP) adhesive systems.

Methods

The two protective agents used were resin infiltrate (ICON) and Clinpro; the two adhesive systems used were self-etching primer system (Transbond Plus Self Etching Primer + Transbond XT adhesive) and a conventional adhesive system (37% phosphoric acid etch + Transbond XT primer + Transbond XT adhesive ). Sixty premolars divided into three major groups and six subgroups were included. The shear bond strength was tested 72 h after bracket bonding. Adhesive remnant index scores (ARI) were assessed. Statistical analysis consisted of a one-way ANOVA for the SBS and Kruskal-Wallis test followed by Mann-Whitney test for the ARI scores.

Results

In the control group, the mean SBS when using the conventional adhesive was 21.1 ± 7.5 MPa while when using SEP was 20.2 ± 4.0 MPa. When ICON was used with the conventional adhesive system, the SBS was 20.2 ± 5.6 MPa while with SEP was 17.6 ± 4.1 MPa. When Clinpro was used with the conventional adhesive system, the SBS was 24.3 ± 7.6 MPa while with SEP was 11.2 ± 3.5 MPa. Significant differences in the shear bond strength of the different groups (P = .000) was found as well as in the ARI scores distribution (P = .000).

Conclusion

The type of the adhesive system used to bond the orthodontic brackets, either conventional or self-etching primer, influenced the SBS, while the enamel protective material influenced the adhesive remnant on the enamel surface after debonding.