2种不同粘接水门汀对树脂类冠修复材料和全瓷托槽剪切粘接力的影响

目的 评价两种不同粘接水门汀对树脂类冠修复材料和全瓷托槽剪切粘接力的影响。方法 选用2种水门汀Transbond XT和RelyX Ultimate,将上颌前磨牙全瓷托槽Inspire Ice与4种树脂类冠修复材料粘接。试件冷热循环5 000次后测量断裂载荷（N）,并观察破坏形态。结果 单因素方差分析结果F=4.52（P＜0.001）,显示粘接条件对陶瓷托槽和树脂类冠修复材料的剪切粘接力影响具有统计学意义。其中Lava Ultimate+Transbond XT组和Lava Ultimate+ RelyX Ultimate+托槽喷砂组分别为（325.10±135.54）N和（304.71±35.71）N,较其他组高,Lava Ultimate+ Transbond XT+托槽喷砂组最低,为（118.12±57.58）N。结论 树脂基陶瓷材料Lava Ultimate和全瓷托槽的剪切粘接力较暂时冠修复材料高。全瓷托槽未喷砂时,正畸全瓷托槽粘接水门汀Transbond XT和修复用水门汀RelyX Ultimate的粘接力未见明显区别,喷砂后全瓷托槽失去固位小球,RelyX Ultimate有更高的粘接力。     

Torsional strength of computer-aided design/computer-aided manufacturing–fabricated esthetic orthodontic brackets

Objective:To fabricate orthodontic brackets from esthetic materials and determine their fracture resistance during archwire torsion.Materials and Methods:Computer-aided design/computer-aided manufacturing technology (Cerec inLab, Sirona) was used to mill brackets with a 0.018 × 0.025-inch slot. Materials used were Paradigm MZ100 and Lava Ultimate resin composite (3M ESPE), Mark II feldspathic porcelain (Vita Zahnfabrik), and In-Ceram YZ zirconia (Vita Zahnfabrik). Ten brackets of each material were subjected to torque by a 0.018 × 0.025-inch stainless steel archwire (G&H) using a specially designed apparatus. The average moments and degrees of torsion necessary to fracture the brackets were determined and compared with those of commercially available alumina brackets, Mystique MB (Dentsply GAC).Results:The YZ brackets were statistically significantly stronger than any other tested material in their resistance to torsion (P < .05). The mean torques at failure ranged from 3467 g.mm for Mark II to 11,902 g.mm for YZ. The mean torsion angles at failure ranged from 15.3° to 40.9°.Conclusion:Zirconia had the highest torsional strength among the tested esthetic brackets. Resistance of MZ100 and Lava Ultimate composite resin brackets to archwire torsion was comparable to commercially available alumina ceramic brackets.     

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.     

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.     

Stain susceptibility of composite and ceramic CAD/CAM blocks versus direct resin composites with different resinous matrices

To evaluate the stain susceptibility of CAD/CAM blocks and direct composite after long term exposure to various staining agents. 40 disk-shaped samples were fabricated from each of nine materials; six CAD/CAM (Vitablocs Mark II, Paradigm MZ100, Experimental Vita Hybrid Ceramic, Vita Enamic, Experimental Kerr and Lava Ultimate) and three direct composites (Filtek Supreme, Venus Diamond and Filtek Silorane). Samples were randomly divided into five groups (n = 8) according to different staining solutions (distilled water, tea, red wine, coffee and artificial saliva). Initial L*a*b* values were assessed using a calibrated digital spectrophotometer. Specimens were immersed in staining solutions and stored in an incubator at 37 °C for 120 days. L*a*b* values were assessed again and color change (?E) was calculated as difference between recorded L*a*b* values. ANOVA, and Duncan test were used to identify differences between groups (α = 0.05). Significant differences in ?E values were detected between materials (p = 0.000). Among all staining solutions, the highest ?E value was observed with red wine. The new CAD/CAM blocks (Vita Enamic, Vita Hybrid Ceramic and Lava Ultimate) showed the highest resistance to staining compared to the MZ100 composite resin blocks. Filtek Silorane, a direct composite, showed high stain resistance values compared to CAD/CAM materials and other direct composites. Ceramic and composite CAD/CAM blocks had lower staining susceptibility than methacrylate based direct composite. Staining susceptibility of the new resin based CAD/CAM materials Vita Enamic and Lava Ultimate was comparable to feldspathic ceramic blocks (Vitablocs Mark II). Filtek Silorane showed promising results that were comparable to some CAD/CAM blocks.     

Durability of resin bonding to lithium disilicate using different self-etching and conventional ceramic primers after long-term aging

ObjectivesTo evaluate the bonding durability after artificial aging provided by a self-etching and a no-etching ceramic primer compared to primers, which are applied by the etch and rinse method.MethodsLithium disilicate blocks were bonded to a composite resin (Clearfill Core, Kuraray) using 5 bonding methods (N = 24). Specimens of group MEP were bonded using a self-etching primer and the corresponding luting resin (Monobond Etch&Prime/Variolink Esthetic, Ivoclar Vivadent) Specimens of group UBE were bonded using a two-bottle silane solution (Universal Primer/Estecem, Tokuyama) without hydrofluoric acid ceramic etching. Specimens of the other 3 groups were bonded using etch and rinse bonding systems with prior hydrofluoric acid ceramic etching (MPV: Monobond Plus/Variolink Esthetic, Ivoclar Vivadent; SUR: Scotchbond Universal/RelyX Ultimate, 3 M; GML: G-Multi Primer/G-CEM LinkForce, GC). Each group was divided into 3 subgroups (n = 8) according to the storage conditions (3 days water storage (37 °C), 30 days water storage, 7,500 thermal cycles (5–55 °C) and 150 days water storage, 37,500 thermal cycles). The tensile bond strength (TBS) was measured and the data was statistically analyzed.ResultsAfter 3 days the median TBS ranged from 14.6 to 41.7 MPa, after 30 days from 4.2 to 39.0 MPa and after 150 days from 0 to 29.7 MPa. Both bonding systems utilizing a self-etching primer showed a significantly lower TBS than group MPV using a conventional ceramic bonding system.SignificanceEspecially after long-term storage with additional thermal cycling the bonding systems using primers without hydrofluoric acid ceramic etching do not provide a high bond strength.     

Effect of artificial toothbrushing and water storage on the surface roughness and micromechanical properties of tooth-colored CAD-CAM materials

Statement of problem

Because of the different composition of resin-ceramic computer-aided design and computer-aided manufacturing (CAD-CAM) materials, their polishability and their micromechanical properties vary. Moreover, depending on the composition of the materials, their surface roughness and micromechanical properties are likely to change with time.

Micro-shear bond strengths of resin-matrix ceramics subjected to different surface conditioning strategies with or without coupling agent application

PURPOSEThis study aimed to assess the influence of various micromechanical surface conditioning (MSC) strategies with or without coupling agent (silane) application on the micro-shear bond strength (µSBS) of resin- matrix ceramics (RMCs).MATERIALS AND METHODSGC Cerasmart (GC), Lava Ultimate (LU), Vita Enamic (VE), Voco Grandio (VG), and Brilliant Crios (BC) were cut into 1.0-mm-thick slices (n = 32 per RMC) and separated into four groups according to the MSC strategy applied: control-no conditioning (C), air-borne particle abrasion with aluminum oxide particles (APA), 2W- and 3W-Er,Cr:YSGG group coding is missing. The specimens in each group were further separated into silane-applied and silane-free subgroups. Each specimen received two resin cement microtubules (n = 8 per subgroup). A shear force was applied to the adhesive interface through a universal test machine and µSBS values were measured. Data were statistically analyzed by using 3-way ANOVA and Tukey HSD test. Failure patterns were scrutinized under stereomicroscope.RESULTSRMC material type, MSC strategy, and silanization influenced the µSBS values (P<.05). In comparison to the control group, µSBS values increased after all other MSC strategies (P<.05) while the differences among these strategies were insignificant (P>.05). For control and APA, there were insignificant differences between RMCs (P>.05). The silanization decreased µSBS values of RMCs except for VE. Considerable declines were observed in GC and BC (P<.05).CONCLUSIONMSC strategies can enhance bond strength values at the RMC - cement interface. However, the choice of MSC strategy is dependent on RMC material type and each RMC can require a dedicated way of conditioning.     

3种可切削树脂陶瓷复合材料机械性能比较

目的:采用体外研究方法,比较3种可切削树脂陶瓷复合材料的挠曲性能、断裂韧性及硬度。方法:选择Upcera Hyramic、3M Lava Ultimate、Vita Enamic和对照组玻璃陶瓷Vitablocs MarkⅡ,分别制作成长、宽、高为16 mm×4 mm×1.0 mm、2.0 mm的挠曲强度实验试件,17 mm×4 mm×3 mm的断裂韧性实验试件和厚度为4 mm的硬度实验试件。应用万能实验机以 0.5 mm/min 的加载速度,测量并计算试件挠曲强度值和断裂韧性值;应用显微硬度仪测量并计算硬度值;扫描电镜观察试件断面粗糙程度。采用SPSS17.0软件包对实验数据进行单因素方差分析。结果:厚度1 mm时,各组挠曲强度值为Hyramic（207.7515±13.12） MPa>Vita Enamic（182.0286 ±15.18）MPa>Lava Ultimate（145.8469±8.98）MPa>Vitablocs MarkⅡ（103.0542 ±18.19）MPa;挠曲模量为Vitablocs MarkⅡ（49.49±5.50）GPa>Vita Enamic（40.65±3.80）GPa>Hyramic（14.89±2.38）GPa>Lava Ultimate（7.09±1.24）GPa。厚度2 mm时,各组挠曲强度值为Hyramic（208.1986±25.07）MPa>Lava Ultimate（172.9297±12.73） MPa>Vitablocs MarkⅡ（158.6587±15.37）MPa>Vita Enamic（155.3670±13.77）MPa;挠曲模量为Vitablocs MarkⅡ（24.07±1.86）GPa>Vita Enamic（19.64±0.98）GPa>Hyramic（10.35±0.87）GPa>Lava Ultimate（8.68±0.86）GPa。断裂韧性为Vita Enamic（1.6357±0.16）MPa·m^1/2>Lava Ultimate（1.4286±0.11）MPa·m^1/2>Vitablocs MarkⅡ（1.3233±0.10）MPa·m^1/2>Hyramic（1.0614±0.09） MPa·m^1/2。各实验组硬度均显著低于对照组。结论:根据ISO 6872/2008,3种可切削树脂陶瓷复合材料均满足临床强度需要。其中,Hyramic在不同厚度条件下都表现出了较高的挠曲强度,是比较理想的后牙修复材料;而Vita Enamic在1 mm时具有更高的机械强度,且韧性好,适用于后牙咬合空间有限且咬合力较大的患者的修复,即贴面。     

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.     

Influence of surface treatments on bond strength of metal and ceramic brackets to a novel CAD/CAM hybrid ceramic material

This study evaluated the effect of four different surface treatments methods on the shear bond strength (SBS) of ceramic and metal brackets to Vita Enamic (VE) CAD/CAM hybrid ceramic. A total of 240 plates (10 mm × 10 mm × 3 mm) were cut from VE ceramic blocks and divided into two groups. In each group, four subgroups were prepared by hydrofluoric acid (HF); phosphoric acid (H₃PO₄); diamond ceramic grinding bur; and silica coating using CoJet system (CJ). Maxillary central incisor metal (Victory Series) and ceramic (Clarity) brackets were bonded with light-cure composite and then stored in artificial saliva for 1 week and thermocycled. The SBS test was performed, and the failure types were classified with adhesive remnant index scores. Surface morphology of the ceramic was characterized after treatment using a scanning electron microscope. Data were analyzed using two-way ANOVA, Tukey HSD test, and Weibull analysis. SBS was significantly affected by the type of bracket and by type of treatment (P < 0.001). Specimens treated with CJ presented with significantly higher SBS compared to other groups (P < 0.05). Improvements in SBS values (MPa) were found in the following order: CJ > HF > Bur > H₃PO₄. Ceramic bracket showed higher SBS compared to metal bracket. Adhesive failures between the ceramic and composite resin were the predominant mode of failure in all groups. Surface treatment of VE CAD/CAM hybrid ceramic with silica coating enhanced the adhesion with ceramic and metal brackets.     

Influence of Adhesives and Methods of Enamel Pretreatment on the Shear Bond Strength of Orthodontic Brackets

Aim

The objective of present study was to examine influence of adhesives and methods of enamel pretreatment on the shear bond strength (SBS) of orthodontic brackets. The adhesives used were resin-reinforced glass ionomer cements-GIC (Fuji Ortho LC) and composite resin (Transbond XT).

Material and Methods

The experimental sample consisted of 80 extracted human first premolars. The sample was divided into four equal groups, and the metal brackets were bonded with different enamel pretreatments by using two adhesives: group A-10% polyacrylic acid; Fuji Ortho LC, group B–37% phosphoric acid; Fuji Ortho LC, group C–self etching primer; Transbond XT, group D–37% phosphoric acid, primer; Transbond XT. SBS of brackets was measured. After debonding of brackets, the adhesive remnant index (ARI) was evaluated.

Results

After the statistical analysis of the collected data was performed (ANOVA; Sheffe post-hoc test), the results showed that significantly lower SBS of the group B was found in relation to the groups C (p=0.031) and D (p=0.026). The results of ARI were similar in all testing groups and it was not possible to determine any statistically significant difference of the ARI (Chi- square test) between all four experimental groups.

Conclusion

The conclusion is that the use of composite resins material with appropriate enamel pretreatment according to manufacturer’s recommendation is the “gold standard” for brackets bonding for fixed orthodontic appliances.Key words: orthodontic brackets, shear strength, adhesive, enamel preparation     

Impact of different pretreatments and attachment materials on shear bond strength of indirectly bonded brackets using CAD/CAM transfer trays to monolithic zirconia

ObjectiveInvestigating the impact of different pretreatment methods, attachment materials and aging regimens on shear bond strength (SBS) between zirconia and indirectly bonded brackets using CAD/CAM transfer trays.MethodsZirconia substrates were conditioned with silica coated alumina (CoJet) and a) Clearfil Ceramic Primer Plus (CF), b) RelyX Ceramic Primer (RXP), c) Futurabond U (FU). Brackets were virtually placed, transfer tray designed (OnyxCeph) and 3D-printed for indirect bonding with a) Transbond LV (TBL), b) Nexus NX3 (NX3), c) Maximum Cure (MC). SBS testing was performed with a universal testing machine after 24 h, 500 thermal cycles, 90 d. Directly bonded brackets to human enamel using Transbond XT Adhesive served as control. The adhesive remnant index (ARI) was evaluated. Data was analyzed with Shapiro–Wilk, Kruskal–Wallis and Dunn’s post-hoc test with Bonferroni correction, Chi² test (p < 0.05), and the Weibull modulus was calculated.ResultsSBS ranged from 0.1 to 15.5 MPa and were influenced mostly by the attachment material. NX3 generally showed the highest values (9.5–15.8 MPa). Initially RXP/TBL and FU/TBL presented the lowest values (4.3/4.8 MPa). Aging regimens reduced SBS of MC irrespective of pretreatment, after 90 d values ranged from 0.1 to 0.9 MPa. ARI 1 was predominant in all MC groups and FU/NX3, 2 and 3 in the other groups. Weibull moduli ranged between 0.15 (MC/RXP/500 TC) and 6.24 (NX3/RXP/500 TC).SignificanceMC seems not to be suitable for indirect bonding using CAD/CAM transfer trays to zirconia. NX3 showed similar SBS values compared to the control, TBL lower.     

Plant Extract Ankaferd Blood Stopper Effect on Bond Strength

Objective:To determine the effect of Ankaferd Blood Stopper (ABS) on the shear bond strength (SBS) of orthodontic attachments.Materials and Methods:The study material consisted of 60 freshly extracted bovine permanent mandibular incisor teeth. All teeth were cleaned and randomly divided into three groups of 20 specimens and etched with 37% phosphoric acid for 15 seconds, washed, and air-dried. Teeth in groups 1 and 2 were contaminated with ABS and blood, respectively. Teeth in group 3 were only air-dried. Roth Generous maxillary central incisor brackets were bonded with Transbond XT to all teeth. SBS was applied using a universal test machine. The one-way analysis of variance (ANOVA) test was used to determine significant differences in SBS between the three groups, and Tukey honestly significant post hoc test was used to compare subgroups.Results:The mean bond strengths and standard deviations of groups 1, 2, and 3 were 9.58 ± 0.95, 4.04 ± 0.69, and 19.56 ± 1.84 MPa, respectively.Conclusions:Specimens contaminated with blood showed a statistically significant lower in vitro SBS than those contaminated with ABS. ABS may be used clinically for obtaining a blood-free tooth surface during application of the brackets on surgically exposed, impacted teeth.     

Effect of bonding material, etching time and silane on the bond strength of metallic orthodontic brackets to ceramic

The purpose of this study was to evaluate the bond strength of metallic orthodontic brackets to feldspathic ceramic with different etching times, bonding materials and with or without silane application. Cylinders of feldspathic ceramic were etched with 10% hydrofluoric acid for 20 or 60 s. For each etching time, half of the cylinders received two layers of silane. Metallic brackets were bonded to the cylinders using Transbond XT (3M Unitek) or Fuji Ortho LC (GC). Light-activation was carried out with total exposure time of 40 s using UltraLume 5. Shear bond strength testing was performed after 24 h storage. Data were submitted to three-way ANOVA and Tukey's test (α=0.05). The adhesive remnant index (ARI) was used to evaluate the amount of adhesive remaining on the ceramic surface at ×8 magnification. Specimens etched for 60 s had significantly higher bond strength compared with 20 s. The application of silane was efficient in increasing the shear bond strength between ceramic and both fixed materials. Transbond XT showed significantly higher (p<0.05) bond strength than Fuji Orth LC. There was a predominance of ARI score 0 (clean ceramic failure surface) for all groups, with an increase in scores 1, 2 and 3 (adhesive material increasingly present on ceramic failure aspect) for the 60-s etching time. In conclusion, 60-s etching time, silane and Transbond XT improved significantly the shear bond strength of brackets to ceramic.     

Improvement of the orthodontic bracket bond strength with pre-heated composite restoratives

Abstract

Aim. This study aimed to evaluate the effect of pre-heated composite restoratives on the shear bond strength (SBS) of orthodontic brackets. Methods. The following materials were tested: a microhybrid composite restorative (Filtek Z250), two nanofilled composite restoratives (Filtek Z350 and NT Premium), a nanohybrid composite restorative (Brilliant) and a conventional orthodontic adhesive (Transbond XT). All materials were stored for 1 h in the incubator either at 25°C (room temperature simulation) or 60°C before bonding 100 orthodontic brackets on bovine lower incisors (n = 10). One Coat Bond SL and Transbond XT were used to bond the composite restoratives and the Transbond XT adhesive paste, respectively. After storage in distilled water for 24 h, the brackets were subjected to SBS test at a speed of 0.5 mm/min until bracket debonding. The Adhesive Remnant Index (ARI) was assigned to the fractured specimens. Data were analyzed using the one-way ANOVA and the Tukey post-hoc test (p < 0.05). The Kruskal-Wallis test was used to compare ARI scores between the groups (p < 0.05). Results. There was no statistically significant difference between the materials at room temperature. Samples bonded with pre-heated materials showed a statistically higher SBS than those bonded with room temperature materials. Samples bonded with the pre-heated orthodontic adhesive showed the highest SBS among all the pre-heated materials. All preheated composite restoratives produced an SBS mean higher than that of Transbond XT stored at room temperature. Conclusion. The use of pre-heated composite restoratives and orthodontic adhesives might be an alternative approach to bond orthodontic brackets.     

Effects of different bleaching methods on shear bond strengths of orthodontic brackets

Objective:To evaluate the effects of different bleaching methods on the shear bond strength (SBS) of orthodontic brackets.Materials and Methods:Forty-five freshly extracted premolars were randomly divided into three groups (n  =  15 per group). In group I, bleaching was performed with the office bleaching method. In group II, bleaching was performed with the home bleaching method. Group III served as the control. Orthodontic brackets were bonded with a light cure composite resin and cured with an LED light. After bonding, the SBS of the brackets were tested with a Universal testing machine.Results:Analysis of variance indicated a significant difference between groups (P < .001). The highest values for SBS were measured in group III (20.99 ± 2.32 MPa). The SBS was significantly lower in groups I and II than in group III (P < .001). The lowest values for SBS were measured in group II (6.42 ± 0.81 MPa). SBS was significantly higher in group I than in group II (P < .001).Conclusions:Both of the bleaching methods significantly affected the SBS of orthodontic brackets on human enamel. Bleaching with the home bleaching method affected SBS more adversely than did bleaching with the office bleaching method.     

Clinical evaluation of the failure rates of metallic brackets

Objectives

The aim of this study was to evaluate in vivo the bonding of metallic orthodontic brackets with different adhesive systems.

Material and Methods

Twenty patients (10.5-15.1 years old) who had sought corrective orthodontic treatment at a University Orthodontic Clinic were evaluated. Brackets were bonded from the right second premolar to the left second premolar in the upper and lower arches using: Orthodontic Concise, conventional Transbond XT, Transbond XT without primer, and Transbond XT associated with Transbond Plus Self-etching Primer (TPSEP). The 4 adhesive systems were used in all patients using a split-mouth design; each adhesive system was used in one quadrant of each dental arch, so that each group of 5 patients received the same bonding sequence. Initial archwires were inserted 1 week after bracket bonding. The number of bracket failures for each adhesive system was quantified over a 6-month period.

Results

The number of debonded brackets was: 8- Orthodontic Concise, 2- conventional Transbond XT, 9- Transbond XT without primer, and 1- Transbond XT + TPSEP. By using the Kaplan-Meier methods, statistically significant differences were found between the materials (p=0.0198), and the Logrank test identified these differences. Conventional Transbond XT and Transbond XT + TPSEP adhesive systems were statistically superior to Orthodontic Concise and Transbond XT without primer (p<0.05). There was no statistically significant difference between the dental arches (upper and lower), between the dental arch sides (right and left), and among the quadrants.

Conclusions

The largest number of bracket failures occurred with Orthodontic Concise and Transbond XT without primer systems and few bracket failures occurred with conventional Transbond XT and Transbond XT+TPSEP. More bracket failures were observed in the posterior region compared with the anterior region.     

Effects of self-etching primer on shear bond strength of orthodontic brackets at different debond times

OBJECTIVE: To evaluate the effect of a self-etching primer on shear bond strengths (SBS) at the different debond times of 5, 15, 30, and 60 minutes and 24 hours. MATERIALS AND METHODS: Brackets were bonded to human premolars with different etching protocols. In the control group (conventional method [CM]) teeth were etched with 37% phosphoric acid. In the study group, a self-etching primer (SEP; Transbond Plus Self Etching Primer; 3M Unitek, Monrovia, Calif) was applied as recommended by the manufacturer. Brackets were bonded with light-cure adhesive paste (Transbond XT; 3M Unitek) and light-cured for 20 seconds in both groups. The shear bond test was performed at the different debond times of 5, 15, 30 and 60 minutes and 24 hours. RESULTS: Lowest SBS was attained with a debond time of 5 minutes for the CM group (9.51 MPa) and the SEP group (8.97 MPa). Highest SBS was obtained with a debond time of 24 hours for the CM group (16.82 MPa) and the SEP group (19.11 MPa). Statistically significant differences between the two groups were not observed for debond times of 5, 15, 30, or 60 minutes. However, the SBS values obtained at 24 hours were significantly different (P < .001). CONCLUSIONS: Adequate SBS was obtained with self-etching primer during the first 60 minutes (5, 15, 30 and 60 minutes) when compared with the conventional method. It is reliable to load the bracket 5 minutes after bonding using self-etching primer (Transbond Plus) with the light-cure adhesive (Transbond XT).     

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.