Evaluation of a new curing light on the shear bond strength of orthodontic brackets

With the introduction of photosensitive (light-cured) restorative materials in dentistry, various methods were suggested to enhance their polymerization and to shorten the curing time including layering and the use of more powerful light-curing devices. The purpose of this study was to determine the effect of using a new light-curing apparatus that uses a light-emitting diode (LED) on the shear bond strength of an orthodontic adhesive. The new light-curing apparatus used in the study was UltraLume 2 (Ultradent USA, South Jordan, Utah) that has an 8-mm footprint and can simultaneously cure two orthodontic brackets. Forty teeth were etched with 37% phosphoric acid, washed and dried, and sealant applied, and then precoated brackets with the Transbond adhesive (APC II, 3M Unitek, Monrovia, Calif) were placed. The teeth were randomly divided into two groups according to the curing light used. In group I (control), 20 brackets were cured using an Ortholux (3M Unitek) halogen curing light for 20 seconds. In group II, 20 brackets were cured using the new LED light for 20 seconds. The findings indicated no significant (P = .343) differences in the shear bond strength between the Ortholux halogen light (5.1 +/- 2.5 MPa) and the UltraLume 2 LED light when the two groups were compared using Student's t-test (t = -0.961). In conclusion, the advantages of the new unit include the ability to cure two brackets at a time and a smaller light-emitting apparatus for the clinician to handle.     

Waterline disinfectant effect on the shear bond strength of orthodontic brackets

The purpose of this study was to determine whether the use of an iodine compound for disinfecting the waterlines in dental units has an effect on the shear bond strength of orthodontic brackets bonded to enamel. Forty molar teeth were divided randomly into two groups- group 1 control: twenty teeth were etched for 15 seconds with 35% phosphoric acid, washed with a distilled water spray for 10 seconds, stored in distilled water for 5 minutes, dried to a chalky white appearance, and the sealant applied to the etched surface; group 2 experimental: twenty teeth were etched for 15 seconds with 35% phosphoric acid and washed for 10 seconds with water containing iodine. The teeth were stored for five minutes in the iodinated water, dried to a chalky white appearance, and the sealant applied to the etched surface as in the control group. Precoated brackets were placed on all the teeth and light cured for 20 seconds. All teeth were debonded within 30 minutes from the initial time of bonding. The t-test results (t = 1.74) indicated that there were no significant (P = .09) differences in the shear bond strengths of the teeth that were washed and immersed in the iodine solution and the control group in which distilled water was used. The mean shear bond strengths for the two groups were 6.5 +/- 3.5 MPa and 4.7 +/- 3.1 MPa, respectively.     

自酸蚀偶联剂不同作用时间对托槽与牙面剪切粘接强度影响的研究

目的测量自酸蚀偶联剂不同作用时间下托槽与牙面间剪切粘接强度,以探讨正畸临床上运用自酸蚀偶联剂粘接托槽的最佳作用时间.方法选择48颗正畸减数的恒双尖牙,随机分为四组,自酸蚀偶联剂作用时间分别为5秒、15秒、30秒和60秒.所有样本均用光固化粘接剂粘接托槽.半小时后测量四组的剪切粘接强度(Shear bond strength,SBS)及粘接剂残留指数(Adhesive remnant index,ARI),并通过扫描电子显微镜观察树脂-牙釉质界面形态学改变.结果四组托槽与牙面平均剪切粘接强度范围5.1609 Mpa～5.5146 Mpa,组间剪切粘接强度无显著性差异(p＞0.05);ARI评分表明自酸蚀偶联剂作用时间为60秒时,牙面上残留的粘接剂明显多于其他三组;电镜观察结果显示随着自酸蚀偶联剂作用时间的延长,树脂突的形态更规则,结构更致密.结论自酸蚀偶联剂作用时间在5～60秒范围内较厂家推荐时间延长或缩短均不会影响其剪切粘接强度.     

Early shear bond strength of a one-step self-adhesive on orthodontic brackets

OBJECTIVE: The purpose of this study was to determine whether a self-adhesive universal cement, RelyX Unicem (3M ESPE, Seefeld, Germany), can be used successfully to bond orthodontic brackets to enamel. MATERIALS AND METHODS: Forty human molars were cleaned, mounted, and randomly divided into two groups: 20 orthodontic brackets were bonded to teeth using RelyX Unicem, and 20 brackets were bonded using the Transbond XT (3M Unitex, Monrovia, Calif) adhesive system. The teeth were debonded within 30 minutes after initial bonding using a universal testing machine. After debonding, the enamel surface was examined under 10x magnification to determine the amount of residual adhesive remaining on the tooth. Student's t-test was used to compare the shear bond strength (SBS) of the two groups, and the chi-square test was used to compare the Adhesive Remnant Index (ARI) scores for the two adhesive systems. RESULTS: The mean SBS of the brackets bonded using the RelyX Unicem was 3.7 +/- 2.1 MPa and was significantly lower (t = 2.07, P = .048) than the SBS of the brackets bonded with the Transbond system (x = 5.97 +/- 4.2 MPa). The comparisons of the ARI scores between the two groups (chi(2) = 17.4) indicated that bracket failure mode was significantly different (P = .002) with more adhesive remaining on the teeth bonded with Transbond XT. CONCLUSIONS: The SBS of the self-adhesive universal cement needs to be increased for it to be successfully used for bonding orthodontic brackets.     

Effects of different surface preparations on shear bond strength of orthodontic brackets to porcelain

The aim of this study was to assess bonding of orthodontic metal brackets to porcelain surfaces using various surface treatment methods. Etching the porcelain with 9.6 percent HF followed by a bonding agent or silane application provided high and acceptable shear bond strengths.     

不同处理方法对托槽再黏结强度的影响

目的:比较不同处理方法对金属托槽再黏结强度的影响。方法:选择40颗离体前磨牙为实验对象,随机分为4组。粘结托槽后,选择3组剥离托槽,采用磨除、烧灼、喷砂3种不同托槽底板处理后予以再次黏结,经体外pH循环30 d后,测定托槽的抗剪切强度。采用SPSS 13.0软件包对所得数据进行单因素方差分析。另选取试样通过扫描电镜观察托槽底板的形态及结构。结果:4组间有显著差异,托槽烧灼再黏结组与其他各组间有显著差异,其余各组两两相比,均无显著性差异。结论:托槽底板残留黏结剂经磨除或喷砂处理,可获得与初次黏结相近的黏结强度。     

Effects of two adhesion boosters on the shear bond strength of new and rebonded orthodontic brackets.

The purpose of this study was to evaluate the effects of 2 adhesion boosters, Enhance LC (Reliance, Itasca, Ill) and All-Bond 2 (Bisco, Schaumburg, Ill), on the shear bond strength of new and rebonded (previously debonded) brackets. Sixty new and 60 sandblasted rebonded brackets were bonded to 120 extracted human premolars with composite resin and divided equally into 6 groups based on the 2 adhesion boosters used: (1) new brackets/no booster (2) rebonded brackets/no booster (3) new brackets/Enhance (4) rebonded brackets/Enhance (5) new brackets/All-Bond (6) rebonded brackets/All-Bond. Shear bond strength of each sample was tested with an Instron machine (Instron Corp, Canton, Mass). Results show that the new brackets/All-Bond group yielded the highest strength (20.8 +/- 7.5 MPa), followed by the new brackets/Enhance group (18.6 +/- 6.5 MPa), rebond brackets/All-Bond group (17.3 +/- 7.2 MPa), new brackets/no booster group (16.8 +/- 6.3 MPa), rebonded brackets/no booster group (14.2 +/- 7.2 MPa), and rebonded brackets/Enhance group (13.6 +/- 6.7 MPa). No statistically significant difference was found among the 3 groups utilizing new brackets. For groups of rebonded brackets/no booster and rebonded brackets/Enhance, bond strength was significantly lower than groups of 3 new brackets and rebonded brackets/All-Bond. Rebonded brackets/All-Bond group had comparable bond strength to all 3 new brackets groups. It was concluded that in the process of replacing a failed bracket, (1) when new brackets are used, neither All-Bond 2 or Enhance LC improves bond strength significantly, (2) without the use of any adhesion booster, sandblasted rebonded brackets yield significantly less bond strength than new brackets, (3) Enhance LC fails to increase bond strength of sandblasted rebonded brackets, (4) All-Bond 2 significantly increases bond strength of sandblasted rebonded brackets, (5) sandblasted rebonded brackets with All-Bond 2 yield comparable bond strength to new brackets.     

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).     

Effect of primer precuring on the shear bond strength of orthodontic brackets

Two adhesive systems, Transbond APC II (3M Unitek, Monrovia, Calif) and Quick Cure (Reliance Orthodontic Products, Itasca, Ill), were used to determine the efficacy of precuring the liquid resin primer phase of the systems to increase shear bond strength. One hundred sixty bovine incisors were divided into groups of 20 specimens. In 1 group, the primer was cured before placement of the bracket with the filled adhesive material, and, in the other group, the primer was not precured. The shear-peel bond strength was tested with a testing machine at 30 minutes and 24 hours. No statistically significant difference in bond strength was found between the groups that had or had not been precured. More adhesive remained on the teeth with the Transbond when the primer was not precured. There is no advantage or disadvantage in bracket bond strength by precuring the primer before placing the bracket and filled component of the adhesive.     

Effect of antimicrobial monomer-containing adhesive on shear bond strength of orthodontic brackets

A new antibacterial and fluoride-releasing bonding system consists of a self-etching primer that contains an antibacterial monomer and a bonding agent that contains sodium fluoride. This study was to determine the effect of using this new adhesive on the shear bond strength of orthodontic brackets. Forty molar teeth were randomly divided into two groups. Group 1 consisted of 20 teeth that were etched for 15 seconds with 35% phosphoric acid, washed with a water spray for 10 seconds, and dried to a chalky white appearance, and the sealant was applied to the etched surface. The precoated brackets were placed on the teeth and light cured. Group 2 consisted of 20 teeth that were etched with 35% phosphoric acid for 15 seconds as suggested by the manufacturer when bonding to intact enamel. The teeth were washed with a water spray for 10 seconds and dried to a chalky white appearance, and the primer containing antibacterial monomer was applied to the etched surface, left for 20 seconds, and sprayed with a mild airstream. The adhesive was applied to each tooth, and the precoated bracket was placed and light cured. There were no significant differences (P = .220) in the shear bond strengths of the two groups. The mean shear bond strength for the antibacterial fluoride-releasing adhesive was 11.7 +/- 5.6 MPa and for the control was 9.6 +/- 5.0 MPa. The use of an antibacterial fluoride-releasing adhesive system did not affect the shear bond strength of the orthodontic brackets within the first half hour after initial bonding.     

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.     

Factors affecting the shear bond strength of orthodontic brackets to porcelain

The aim of this investigation was to establish a regime for orthodontic bonding to feldspathic porcelain, which ensures adequate bond strength (6-8 MPa) with minimal damage on debond and consisted of an ex vivo investigation measuring the effects of porcelain surface preparation and thermocycling on shear bond strength of orthodontic brackets. One-hundred-and-twenty feldspathic porcelain bonded crown surfaces were divided into 12 equally-sized groups to assess the effects of: (1) glaze removal, (2) application of hydrofluoric acid, phosphoric acid, or omission of acid treatment, and (3) silane priming upon the bond strength of premolar brackets bonded with Right-on (TM) composite resin adhesive. Specimens were subjected to thermocycling and then to shear debonding forces on an Instron machine. Removal of the porcelain glaze, or use of hydrofluoric acid, prior to bonding were found to be unnecessary to secure the target bond strength. Hydrofluoric acid application was associated with increased porcelain surface damage. Thermocycling caused a significant reduction in shear bond strength to porcelain (P < 0*001). The best regime for orthodontic bonding to feldspathic porcelain was to apply phosphoric acid for 60 seconds, and prime with silane prior to bonding. Usually the porcelain surfaces could be repolished. Refereed Paper     

托槽重复黏结及不同处理方法对抗剪强度的影响

目的:观察正畸托槽脱落后第2、3次黏结时托槽底板残留黏结剂的不同处理方法对抗剪强度的影响。方法:选择60颗离体人前磨牙,随机分成3组,每组20个样本,第1组为更换新托槽组(简称更新组),即在第2、3次黏结时分别更换新托槽;第2组为燃烧去除底板残胶组(简称燃烧组),即在进行第2、3次黏结时对托槽底板上的残留黏结剂进行燃烧处理;第3组为磨除法去除底板残胶组(简称磨除组),即在第2、3次黏结时对托槽底板上的黏结剂进行磨除处理。3组分别按常规操作对黏结托槽进行剪切试验,记录每组抗剪强度数值的变化并观察ARI指数(牙面残留黏结剂指数)。结果:3组托槽初次黏结的抗剪强度分别(10.00±2.95)MPa;(9.57±2.45)MPa;(9.09±2.58)MPa;更新组第2、3次黏结的抗剪强度分别为(9.55±2.84)MPa;(10.32±2.59)MPa。燃烧组第2、3次黏结抗剪强度分别为(7.30±2.15)MPa;(7.14±1.93)MPa;磨除组的第2、3次黏结抗剪切强度分别为(12.13±2.93)MPa;(12.86±3.08)MPa;燃烧组抗剪强度下降,磨除组抗剪强度则升高,两者均有统计学意义。结论:黏结脱落托槽时宜采用磨除法对脱落托槽底板上残留的黏结剂进行处理,避免使用燃烧底板残胶的方法。     

Electrothermal bonding: shear bond strength of orthodontic brackets after two weeks.

Abstract

Electrothermal bonding is based on acceleration of the setting reaction of a bonding: resin by the selective application of heat to the orthodontic bracket through the passage of a low voltage electric current. The purpose of this study was to compare the shear bond strength of nine resins comprising chemically-cured, light-cured, and glass ionomer types, 14 days after electrothermal and conventional bonding. Mean shear and bond strengths ranged from a low of 7.4 MPa for Sequence (electrothermally bonded) to a high of 15.4 MPa Concise (control). There was no statistically significant difference between the electrothermal and conventional bonding methods. All the resins produced bond strengths adequate for clinical orthodontics at 14 days.     

The effect of tooth bleaching on the shear bond strength of orthodontic brackets

INTRODUCTION: The purpose of this study was to determine the effect of enamel bleaching on the shear bond strength of orthodontic brackets bonded with a composite adhesive. METHODS: Two protocols were used on 60 human molars. In the at-home bleaching group (n = 30), Opalescence bleaching agent (Ultradent, South Jordan, Utah), which contains 10% carbamide peroxide, was brushed onto the teeth daily for 14 days and left for 6 hours each day. Teeth in the in-office group (n = 30) were treated with Zoom! (Discus Dental, Culver City, Calif), which contains 25% hydrogen peroxide gel, and then exposed to a light source for 20 minutes; these teeth were treated twice. After bleaching, the specimens were randomly divided into equal subgroups and stored in artificial saliva at 37 degrees C for 7 or 14 days before bonding. Shear bond strength testing was performed on all teeth. The Kruskal-Wallis test for nonparametric means was used to determine whether significant differences existed between the various subgroups and an unbleached control group. RESULTS: The mean shear bond strength for the control group was 5.6 +/- 1.8 MPa. Means for the at-home groups were 5.2 +/- 3.6 MPa and 7.2 +/- 3.2 MPa for the 7- and 14-day waiting periods, respectively. Means for the in-office groups were 5.1 +/- 5.3 MPa and 6.6 +/- 2.6 MPa for the 7- and 14-day waiting periods, respectively. The Kruskal-Wallis test (X(2) = 8.089) indicated no significant differences between the 5 subgroups (P = .088). CONCLUSIONS: The results showed that in-office and at-home bleaching did not affect the shear bond strength of orthodontic brackets to enamel.