Direct bonding comparing a polyacrylic acid and a phosphoric acid technique

The purpose of this study was to compare in vitro a polyacrylic acid technique (crystal bonding) with a conventional phosphoric acid-etch technique for the preparation of teeth for bonding. The potential value of the polyacrylic acid technique was evaluated for bond strength, enamel loss, cleanup, and fracture location--with and without the use of a sealant. Ninety-six premolars were evenly divided into two groups. Group A was preconditioned with polyacrylic acid and group B with phosphoric acid. Half of each group was treated with a sealant before direct bonding of orthodontic brackets. Sealant was not used on the other half of each group and brackets were bonded directly to the conditioned labial surfaces with a composite cement. Bonding and rebonding shear strength tests were carried out for both groups. Results indicated that shear bond strength values for the polyacrylic acid group were approximately one third those of the phosphoric acid group using a composite cement as the adhesive. Enamel loss was measured on the lingual surfaces of 30 of the 96 premolars. The lingual surfaces were conditioned with polyacrylic acid. Following debonding and cleanup procedures, the polyacrylic acid treated surface was left slightly pitted with no resin tags remaining. Cleanup procedures required only a rubber-cup silicate prophylaxis. The total enamel loss was minimal (4.5 micron), thus preserving most of the outermost fluoride-rich layer of enamel.     

Shear bond strength of self-etch adhesives to enamel with additional phosphoric acid etching

This study evaluated the shear bond strength of self-etch adhesives to enamel and the effect of additional phosphoric acid etching. Seventy sound human molars were randomly divided into three test groups and one control group. The enamel surfaces of the control group (n=10) were treated with Syntac Classic (SC). Each test group was subdivided into two groups (each n=10). In half of each test group, ground enamel surfaces were coated with the self-etch adhesives AdheSe (ADH), Xeno III (XE) or Futurabond NR (FNR). In the remaining half of each test group, an additional phosphoric acid etching of the enamel surface was performed prior to applying the adhesives. The shear bond strength was measured with a universal testing machine at a crosshead speed of 1 mm/minute after storing the samples in distilled water at 37 degrees C for 24 hours. Fracture modes were determined by SEM examination. For statistical analysis, one-way ANOVA and the two-sided Dunnett Test were used (p>0.05). Additional phosphoric etching significantly increased the shear bond strength of all the examined self-etch adhesives (p<0.001). The highest shear bond strength was found for FNR after phosphoric acid etching. Without phosphoric acid etching, only FNR showed no significant differences compared to the control (SC). SEM evaluations showed mostly adhesive fractures. For all the self-etch adhesives, a slight increase in mixed fractures occurred after conditioning with phosphoric acid. An additional phosphoric acid etching of enamel should be considered when using self-etch adhesives. More clinical studies are needed to evaluate the long-term success of the examined adhesives.     

Shear bond strength of a resin composite to enamel etched with maleic or phosphoric acid

The purpose of this study was to evaluate the effect of 10 per cent maleic and 37 per cent phosphoric acid on the shear bond strength of Z100 composite resin with Scotchbond Multi-Purpose adhesive to primary and permanent tooth enamel. Four groups of 20 teeth each were established: 1, permanent teeth, 10 percent maleic acid etched for 15 seconds; 2, permanent teeth, 10 per cent maleic acid etched for 30 seconds; 3, permanent teeth, 37 per cent phosphoric acid etched for 15 seconds; 4, primary teeth, 10 per cent maleic acid etched for 15 seconds. Five teeth from each group were randomly assigned for SEM examination of the etched enamel surface. Scotchbond Multi-Purpose primer and adhesive were applied to the etched enamel surface of the remaining 15 teeth and cured following the manufacturer's instructions. Z100 composite resin was placed in a nylon cylinder and cured for two 40 second intervals. Following thermocycling, the specimens were sheared on an universal testing machine and debonded areas were examined visually with a stereo microscope and with SEM. The mean shear bond strengths in MPa were: 1,17.00; 2, 14.58; 3, 14.66; 4, 11.18. ANOVA and Student-Newman-Keuls analyses revealed no statistically significant difference among the groups. SEM examination showed the majority of specimens fractured at the adhesive-resin interface.     

Tensile strength of the bond between resin to enamel etched with phosphoric acid containing fluoride

The tensile bond strength of Epoxylite 9075 and Enamelite to enamel treated with NaF and SnF2, at two concentrations, in the etching acid (H3PO4) was determined. The average fracture stress of those samples in which fracture occurred in the resin only, may be considered as the tensile strength of the resin, 69.8 +/- 5.6 kg/cm2. The mean fracture stresses of the Epoxy 9075 systems etched with pure phosphoric acid or with acid solutions containing 0.5% F salts were significantly higher than those treated with acid solutions containing 2% F salts. Incorporation of NaF or SnF2 in the etching solutions highly increased the fluoride concentration of enamel. The fluoride increase dependend on the fluoride concentration of the etching solution and was greater for NaF than SnF2.     

The effect of fluoride in phosphoric acid on enamel fluoride uptake and the tensile bond strength of an orthodontic bonding resin

Decalcification that occurs adjacent to bonded orthodontic brackets is of great concern to orthodontists. Among the many procedures suggested to overcome this problem is the addition of fluoride to the phosphoric acid (H3PO4) etching solution. The purposes of this study were to determine the loss of fluoride from the acidic etching solutions, to evaluate the effect of various fluoride concentrations in H3PO4 on the tensile bond strength of an orthodontic bonding resin, to determine the amount of total and bound fluoride acquired by etched enamel, and to evaluate the effect of these etching solutions on enamel by scanning electron microscopy. Solutions of 50 m/m% H3PO4 containing 0 and approximately 0.01, 0.04, 0.08, 0.2, 0.4 and 0.9% fluoride were prepared. The fluoride concentrations in the etching solutions remained stable up to 3 months after preparation. The tensile bond strengths of the bonding resin to the etched enamel surfaces were not significantly different. Enamel acquired the greatest amount of total fluoride from H3PO4 solutions containing 0.215% fluoride while the bound fluoride acquired by enamel from the fluoride-containing etching solutions was not significantly different. The addition of fluoride to H3PO4 did not impede the etching effect on enamel.     

Glass ionomer bond strength and treatment of dentin with polyacrylic acid

This investigation compared the effect of smear layer removal using various treatments with polyacrylic acid on the shear bond strength of glass ionomer restorative materials to dentin. Three brands of glass ionomer were applied to prepared dentin surfaces of extracted human molars, after one of four treatments with polyacrylic acid. Samples using dentin surfaces with the smear layer left intact served as controls. Comparison of mean shear bond strength values for all possible combinations of restorative material and polyacrylic acid treatment indicated that samples produced using 25% polyacrylic acid had lower (p less than 0.05) values in some instances. No other significant differences were found when test values were compared with each other or with control values. The authors concluded that removal of the smear layer does not enhance the dentin-glass ionomer restorative bond strength, as has been suggested by other investigators. Scanning electron photomicrographs indicate that treatment with higher concentrations of polyacrylic acid produces higher degrees of dentinal tubular orifice patency.     

氟对托槽粘结强度及牙釉质抗酸性影响的实验研究

目的 探讨氟化物在正畸治疗中预防牙釉质脱矿的最佳使用方法.方法 制备正畸拔除的前磨牙96颗,随机分成4组(A,B,C,D),分别为对照组及酸蚀前、中、后用氟组,粘结托槽后,将每个样本分别放入装有2 ml酸性人工唾液的试管.分别在实验后第1、2、3、4周从每组样本中随机抽取6个,测定托槽抗剪粘结强度及酸性人工唾液中的Ca2 浓度,并对实验结果进行统计学分析.结果 酸蚀前、中、后用氟对托槽抗剪粘结强度及粘结材料残留指数均无显著性影响(P＞0.05),而对人工唾液中钙离子Ca2 浓度均有显著性影响(P＜0.05),Ca2 浓度顺序从大到小依次为:对照组、酸蚀前用氟组、酸蚀中用氟组、酸蚀后用氟组.结论 酸蚀前、中、后用氟对托槽的抗剪粘结强度及粘结材料残留指数均无显著性影响,且均可增加牙釉质的抗酸性,酸蚀后使用氟化物的效果最好.     

Durability of enamel bond strength of simplified bonding systems

The purpose of this study was to investigate the influence of thermal cycling on enamel bond strength of 2-step bonding systems. The systems used were self-etching primer systems; Imperva Fluoro Bond, Clearfil Liner Bond II, and Mac Bond II; and self-priming adhesive systems; One Step, OptiBond Solo, Prime & Bond 2.0, and Single Bond. Bovine mandibular incisors were mounted in self-curing resin and the facial surfaces were wet ground with #600 SiC paper. Enamel surfaces were treated following each manufacturer's instructions. Adhesives were applied and composites were condensed into a Teflon mold (phi 4 x 2 mm) and light cured. Bonded specimens were divided into four groups; stored in 37 degrees C water for 24 hours, followed by thermal cycling between 5 degrees C and 60 degrees C for 3,000, 10,000, and 30,000 cycles. Ten samples per test group were tested in shear mode at a crosshead speed of 1.0 mm/min. One-way ANOVAs followed by Duncan's multiple range test (p < 0.05) were done. For self-etching primer systems, a significant decrease in bond strength was observed for the thermal cycling groups. For the self-priming adhesive systems, a small decrease in bond strength was observed but no significant differences were found for thermal cycling groups. The changes in bond strength after thermal cycling were different between the bonding systems.     

Shear bond strength after multiple bracket bonding with or without repeated etching

The purpose of the study was to measure the in vitro shear bond strength (SBS) of metal brackets after multiple bonding and debonding with and without repeated etching. One hundred and twenty extracted premolars were divided into three equal groups. In group 1, the brackets were bonded and debonded three times with repeated enamel etching and in groups 2 and 3 without repeated etching. In group 2, all composite remnants were removed before bonding, while in group 3, the remnants were levelled. Analysis of variance was used to determine significant differences in SBS with Bonferroni adjustment for the multiple testing procedures. The results showed that in group 1, the mean SBS was 11.69 MPa (SD 2.65) at the first, 14.30 MPa (SD 2.69) at the second, and 12.19 MPa (SD 2.26) at the third debonding. In group 2, SBS decreased from 12.57 MPa (SD 2.54) to below 8.0 MPa. In group 3, SBS remained constant from the first (11.93 MPa; SD 2.14) to the second (12.06 MPa; SD 1.65) debonding and only decreased significantly to 9.74 MPa (SD 1.80) at the third debonding. Less composite remained on the teeth after each debonding sequence. This was characterized by a shift from adhesive remnant index (ARI) scores 2 and 3 after the first debonding to ARI scores 1 and 2 after the second debonding to predominantly scores 0 and 1 after the third debonding. After bracket loss and levelling of composite remnants, the SBS is sufficient for application of orthodontic forces. Repeated etching may involve a higher risk of enamel tear-outs during debonding.     

Tensile bond strength and SEM analysis of enamel etched with Er:YAG laser and phosphoric acid: a comparative study in vitro

Er:YAG laser has been studied as a potential tool for restorative dentistry due to its ability to selectively remove oral hard tissue with minimal or no thermal damage to the surrounding tissues. The purpose of this study was to evaluate in vitro the tensile bond strength (TBS) of an adhesive/composite resin system to human enamel surfaces treated with 37% phosphoric acid, Er:YAG laser (lambda=2.94 mum) with a total energy of 16 J (80 mJ/pulse, 2Hz, 200 pulses, 250 ms pulse width), and Er:YAG laser followed by phosphoric acid etching. Analysis of the treated surfaces was performed by scanning electron microscopy (SEM) to assess morphological differences among the groups. TBS means (in MPa) were as follows: Er:YAG laser + acid (11.7 MPa) > acid (8.2 MPa) > Er:YAG laser (6.1 MPa), with the group treated with laser+acid being significantly from the other groups (p=0.0006 and p= 0.00019, respectively). The groups treated with acid alone and laser alone were significantly different from each other (p=0.0003). The SEM analysis revealed morphological changes that corroborate the TBS results, suggesting that the differences in TBS means among the groups are related to the different etching patterns produced by each type of surface treatment. The findings of this study indicate that the association between Er:YAG laser and phosphoric acid can be used as a valuable resource to increase bond strength to laser-prepared enamel.     

In vitro bracket bond strength to acid-etched or air-abraded enamel.

PURPOSE: This study evaluated, in vitro, the capacity of a dentin bonding agent to improve the bond strength of orthodontic brackets using air abrasion enamel preparation. METHODS: Each of the enamel surfaces received a different treatment prior to bonding procedures. Group 1 received acid-etched with 38% phosphoric acid for 30 seconds. Group 2 received acid-etched with 38% phosphoric acid for 30 seconds, dentin bonding agent (Scotchbond MultiPurpose) applied after rinse completed. Group 3 received abrasion-etched (particle size 50 microns, 120 psi). Group 4 received abrasion-etched, dentin bonding agent applied after etching completed. Unfilled adhesive resin (Ormco light cured sealant) was applied followed by a premolar bracket (Ormco meshed mini-twin) with adhesive (Ormco light cured adhesive) placed on the back. Shear bond strengths were measured using an INSTRON machine and the site of bond failure was determined under 3X magnification. RESULTS: The shear bond strength obtained with a traditional acid-etch, in vitro, was not improved significantly by the use of a dentin bonding agent. Air abraded surfaces showed very low bond strengths with all treatments. CONCLUSIONS: Tested in vitro, air-abraded surfaces provide clinically unacceptable bond strength when compared to acid-etched enamel surfaces.     

Effects of phosphoric acid concentration and etch duration on the shear bond strength of an orthodontic bonding resin to enamel : An in vitro study

The purpose of this in vitro study was to determine the effects of phosphoric acid (H3PO4) concentration and duration of etching on the shear bond strength of an orthodontic bonding resin to enamel. Nine bonding procedures, each involving 18 extracted human maxillary permanent canines, were used. Ground enamel surfaces were etched with a 37% H3PO4 solution, a 15% H3PO4 gel, or a 5% H3PO4 solution for 60, 30, and 15 seconds, respectively. Cylinders of an orthodontic bonding resin, Concise, were prepared in a special device. The test specimens were disassembled 15 minutes after preparation and stored in distilled water at 37 degrees C for 24 hours. A shear load was applied to the bonded cylinders at a crosshead speed of 0.02 in.min-1 in an Instron testing machine, and the shear bond strengths were calculated and expressed in MN.m-2. A two-factor analysis of the data showed that the H3PO4 concentration had no significant effect on the shear bond strength, but the duration of etching affected shear bond strength significantly. The enamel aspects of the fractured test specimens were examined microscopically and the percent failure within the bonding resin at the bonding sites estimated. The correlation between shear bond strength and percentage failure within the bonding resin was not significant. The effects of the nine etching procedures on ground and unground enamel surfaces were studied by scanning electron microscopy. The etching procedures produced well-defined etching patterns on both ground and unground enamel surfaces.     

用于正畸托槽粘接的玻璃离子粘固剂的抗剪切强度

目的　研究用于正畸托槽粘接的树脂改良型玻璃离子粘固剂的抗剪切强度。方法　 30颗离体前磨牙平均分为 2组。一组用树脂改良型玻璃离子粘固剂 (Advance)粘接方丝弓正畸托槽 ,另一组用复合树脂釉质粘接剂 (DM)粘接。 2 4h后用材料力学试验机检测两种材料的抗剪切强度 ,统计牙面上粘接材料的残留指数。结果　 2种粘接材料的抗剪切强度相似 [玻璃离子粘固剂为 (6 86 2±2 142 )MPa,复合树脂粘接剂为 (7 183± 3 2 0 5 )Mpa],差异无显著性。结论　体外研究中 ,树脂改良型玻璃离子粘固剂的抗剪切强度已达到复合树脂釉质粘接剂的水平 ,具有临床应用前景     

2种耐湿性托槽粘结体系粘结强度的比较研究

目的比较3M Transbond MIP处理液+3M Transbond PLUS变色光固化粘结剂与GC Ortho LC光固化树脂加强型玻璃离子2种粘结体系的粘结强度。方法收集因正畸治疗而拔除的上颌前磨牙80颗,按照随机化原则分成8组,每组10颗。将2种粘结体系分别在干燥、水分污染、唾液污染和血液污染的条件下完成托槽粘结,用电子万能试验机测试剪切强度,并在显微镜下用ARI指数评价各组牙齿表面残余的粘结剂。结果在剪切强度测试中,第1组与第5组比较,第2组与第6组比较,第3组与第7组比较,P>0.05,均无统计学差异;第4组与第8组比较,P<0.01,有统计学差异。ARI评分结果提示两者在干燥、水分污染及唾液污染环境下的ARI平均分值无统计学差异,但在血液污染的条件下,GC Ortho LC的ARI值明显降低。结论 3M Transbond MIP处理液+3M Transbond PLUS变色光固化粘结剂与GC Ortho LC光固化树脂加强型玻璃离子在干燥、水分污染及唾液污染的环境下,粘结强度无明显差异,在血液污染的条件下,推荐使用3M Transbond MIP粘结体系。     

Assessment of bracket placement and bond strength when comparing direct bonding to indirect bonding techniques

A clinical evaluation was made to determine the advantages and disadvantages of two currently used techniques for bonding brackets to teeth of orthodontic patients. The two techniques were compared with respect to (1) bracket placement, (2) bond strength, (3) rate of failure, and (4) clinical and laboratory time involved in the two procedures. Vertical bracket placement showed no statistically significant differences. The only exceptions were the maxillary canines, where the indirect technique yielded better results (P less than 0.05), and the mandibular second premolars where the direct-bonded brackets were placed closer to ideal (P less than 0.01). Angular bracket placement showed statistically significant differences on the maxillary (P less than 0.01) and mandibular (P less than 0.05) canines, with the indirect bonds being more accurate. The bond strength results indicated great variability from one patient to another. The bracket failures, recorded 3 months after appliance placement, were 4.5 percent for the indirect technique and 5.3 percent for the direct technique. Average time needed for completion of the direct bonding technique was 42.18 minutes. The indirect technique and laboratory procedures required 53.73 minutes, of which 23.91 minutes represented actual clinical time.     

A clinical comparison of bracket bond failures in association with direct and indirect bonding

OBJECTIVE: To compare bond failure rates between direct and indirect techniques for bonding orthodontic brackets. DESIGN: A two-centre single blinded prospective randomized controlled clinical trial. MATERIALS AND METHODS: This study was undertaken at the Birmingham Dental Hospital and Good Hope Hospital, Sutton Coldfield. Thirty-three subjects meeting the inclusion criteria were selected from orthodontic waiting lists and assigned to either of two study groups according to a split-mouth study design. The number and site of bracket failures between tooth types was recorded over 1 year. Statistical analysis was carried out using chi-square tests. RESULTS: Brackets were lost from 14 of the 553 teeth bonded, giving an overall bond failure rate of 2.5%. There were no significant differences in bond failures between direct and indirect bonding or in the tooth types of the failures. CONCLUSIONS: There was no significant difference in the bond failure rates between direct and indirect bonding.