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。     

Effect of blood contamination on shear bond strength of orthodontic brackets and disinclusion buttons

Our aim was to assess the effect of blood contamination on the shear bonding strength and sites of failure of orthodontic brackets and bondable buttons. We randomly divided 160 bovine permanent mandibular incisors into 8 groups of 20 specimens each. Both orthodontic brackets (Step brackets, Leone, Sesto Fiorentino, Italy) and bondable buttons (Flat orthodontic buttons, Leone, Sesto Fiorentino, Italy) were tested on four different enamel surfaces: dry; contamination with blood before priming; after priming; and before and after priming. Brackets and buttons were bonded to the teeth and subsequently tested using a Instron universal testing machine. Shear bonding strength and the rate of adhesive failures were recorded. Data were analysed using the analysis of variance (ANOVA), Scheffè tests, and the chi-square test. Uncontaminated enamel surfaces showed the highest bonding strengths for both brackets and buttons. When they were contaminated with blood, orthodontic brackets had significantly lower shear strengths than bondable buttons (P = 0.0001). There were significant differences in sites of failure among the groups for the various enamel surfaces (P = 0.001). Contamination of enamel by blood during bonding lowers the strength of the bond, more so with orthodontic brackets than with bondable buttons.     

瓷表面处理对正畸托槽与瓷黏结抗剪强度的影响

目的:探讨不同瓷表面处理技术对正畸托槽与瓷黏结抗剪强度的影响。方法:采用4组不同的瓷表面处理方式,使用光固化正畸黏结剂将瓷面分别与金属和陶瓷托槽黏结,每组再平均分为2组分别在37℃水浴24h和7d后冷热循环500次(5～55℃),测量黏结抗剪强度,并统计其黏结剂残留指数,在扫描电镜下观察其瓷面显微结构的变化。结果:4种瓷表面处理技术对2种不同材料托槽处理的结果近似,均可达到有效正畸黏结强度。结论:磷酸酸蚀结合硅烷偶联剂是正畸托槽与瓷黏结的较佳方式之一。     

不同处理剂对氧化锆与正畸托槽间黏结强度的影响

目的:比较不同表面处理剂对氧化锆修复体表面与正畸托槽间黏结强度的影响.方法:将50个氧化锆陶瓷试件随机分为5组(n=10),进行喷砂和磷酸处理,A组为对照组;B组以硅烷偶联剂处理;C组以硅烷偶联剂+SE Bond 处理;D组以Z-PrimeTM Plus氧化锆处理剂处理;E组以Z-PrimeTM Plus+SE Bond处理.所有试件均用3M Transbond 光固化树脂黏结剂与右上中切牙的托槽黏结,经24 h、37℃恒水浴后,进行抗剪切强度测试;去除托槽后,对氧化锆表面黏结剂残留指数进行统计.其中,每组1个氧化锆表面处理后用扫描电镜观察其表面形态变化,并对氧化锆及处理剂进行红外光谱分析.采用SPSS17.0软件包对数据进行统计学分析.结果:各组的抗剪切强度分别为A组(3.12±0.84) MPa、B组(1.92±0.83) MPa、C组(5.26±0.80) MPa、D组(6.54±0.98)MPa和E组(9.47±2.11) MPa,各组间差异均具有显著性(P＜0.05).A组和B组残留指数最低,E组最高.D组和E组达到了有效的黏结强度.结论:单独使用氧化锆处理剂能获得有效的黏结强度,但是略偏低.建议Z-PrimeTM Plus+SE Bond处理联合使用,以达到正畸临床所需的较高的黏结强度.     

Influence of orthodontic brackets design and surface properties on the cariogenic Streptococcus mutans adhesion

ObjectiveTo compare the surface properties of self-ligating metallic (SLM), ceramic esthetic, and conventional metallic (CM) brackets, and evaluate the adhesion of Streptococcus mutans biofilms to their surface, attempting to interpret the correlation between bracket type and enamel demineralization from a microbiological perspective.Materials and methodsTwenty-two brackets of each group were used. The brackets’ surface roughness was defined and the bacterial adhesion was performed using the strain S. mutans ATCC25175 with 8 h or 24 h of incubation time. The total bacterial adhesion (TBA) of biofilms was assessed using optical density (OD) methodology. To quantify bacteria viability (BV), the colony forming units (CFU) were counted. A scanning electron microscopy (SEM) observation of biofilms was also performed. Results: Ceramic brackets exhibited significantly higher roughness (0.304) compared to CM (0.090) and SLM (0.067) ones (C > CM = SLM). The data obtained with the TBA and BV tests showed that S. mutans biofilm formed on bracket groups exhibited similar results for both incubation periods. From the SEM images it is possible to observe that biofilm structure formed for 24 h was denser than that for 8 h of incubation with significantly more aggregates and cells for three groups.ConclusionThis in vitro study suggests that despite the higher surface roughness of ceramic brackets, this alone does not influence the adhesion of the S. mutans biofilms.Clinical relevanceFrom a microbiological perspective, the bracket's design may be more relevant than its surface roughness with respect to the adhesion of cariogenic bacteria biofilm with potential risk to dental enamel integrity.     

Effect of remineralizing agents on bond strength of orthodontic brackets: an in vitro study

Background

The purpose of this study is to evaluate the effect of casein phosphopeptide amorphous calcium phosphate (CPP-ACP) and CPP-ACP with fluoride (CPP-ACP-F) on the shear bond strength (SBS) of orthodontic brackets bonded with two different adhesive systems.

Methods

One hundred twenty-six human premolar teeth were selected. One hundred twenty teeth were used for SBS testing, and six teeth were used for scanning electron microscope (SEM) examination. One hundred twenty premolars were divided into mainly three groups: CPP-ACP (group A), CPP-ACP-F (group B), and control group (group C). Each group was sub-divided into two groups according to the bonding adhesive, light cure (groups A1, B1, and C1) and chemical cure (groups A2, B2, and C2). The teeth were pre-treated with the group-specified preventive agent 1 h/day for five consecutive days. Standard edgewise brackets were bonded with the respective adhesives. SBS evaluation was done with the universal testing machine. After debonding, all the teeth were scored for adhesive remaining on the buccal surface, in accordance to adhesive remnant index, under a stereomicroscope. The acid-etched enamel surfaces were observed under SEM after treatment with CPP-ACP, CPP-ACP-F, and artificial saliva.

Result

In light-cure adhesive group, CPP-ACP-F (B1) showed superior results compared to the control group (C1), whereas the CPP-ACP group (A1) showed lower mean SBS than the control group (C1). Both these differences were not statistically significant (p > 0.05). In chemical-cure adhesive group, control group C2 showed significantly superior results (p < 0.05) compared to group A2 and group B2. The results of two-way ANOVA showed highly significant difference due to adhesive types (p < 0.01), whereas enamel pre-treatment showed non-significant difference (p > 0.01).

Conclusion

The SBS of the orthodontic brackets was non-significantly affected when the brackets were cured with light-cure bonding system and treated with either CPP-ACP or CPP-ACP-F, whereas with chemical-cure adhesive, decreased bond strength was seen, which was within the clinically acceptable limits.     

In vivo effects of two acidic soft drinks on shear bond strength of metal orthodontic brackets with and without resin infiltration treatment

Objectives:To evaluate the in vivo effects of two acidic soft drinks (Coca-Cola and Sprite) on the shear bond strength of metal orthodontic brackets with and without resin infiltration treatment. In addition, the enamel surface was evaluated, after debonding, using a scanning electron microscope.Materials and Methods:Sixty noncarious maxillary premolars, scheduled for extraction in 30 orthodontic patients, were used. Patients were randomly divided into two groups according to the soft drink tested (Coca-Cola or Sprite). In each group, application of resin infiltration (Icon. DMG, Hamburg, Germany) was done on one side only before bonding of brackets. Patients were told to rinse their mouth with their respective soft drink at room temperature for 5minutes, three times a day for 3months. Shear bond strength was tested with a universal testing machine. After shearing test, a scanning electron microscope was used to evaluate enamel erosion. Statistical analysis was performed by twoway analysis of variance followed by the least significant difference test.Results:The Coca-Cola group without resin infiltration showed the lowest resistance to shearing forces. Scanning electron micrographs of both groups after resin application showed a significant improvement compared with results without resin use, as the enamel appeared smoother and less erosive.Conclusion:Pretreatment with the infiltrating resin has proved to result in a significant improvement in shear bond strength, regardless of the type of soft drink consumed.     

Physical and chemical properties of orthodontic brackets after 12 and 24 months: in situ study

Objective

The aim of this article was to assess how intraoral biodegradation influenced the surface characteristics and friction levels of metallic brackets used during 12 and 24 months of orthodontic treatment and also to compare the static friction generated in these brackets with four different methods of the ligation of orthodontic wires.

Material and Methods

Seventy premolar brackets as received from the manufacturer and 224 brackets that were used in previous orthodontic treatments were evaluated in this experiment. The surface morphology and the composition of the deposits found in the brackets were evaluated with rugosimetry, scanning electron microscopy, and energy dispersive X-ray spectroscopy. Friction was analyzed by applying tensile tests simulating sliding mechanics with a 0.019x0.025" steel wire. The static friction levels produced by the following ligation methods were evaluated: loosely attached steel ligature around all four bracket wings, steel ligature attached to only two wings, conventional elastomeric ligation around all 4 bracket wings, and non-conventional Slide^® elastomeric ligature.

Results

The results demonstrated the presence of biodegradation effects such as corrosion pits, plastic deformation, cracks, and material deposits. The main chemical elements found on these deposits were Carbon and Oxygen. The maximum friction produced by each ligation method changed according to the time of intraoral use. The steel ligature loosely attached to all four bracket wings produced the lowest friction levels in the new brackets. The conventional elastic ligatures generated the highest friction levels. The metallic brackets underwent significant degradation during orthodontic treatment, showing an increase in surface roughness and the deposit of chemical elements on the surface.

Conclusion

The levels of static friction decreased with use. The non-conventional elastic ligatures were the best alternative to reduce friction.     

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.     

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.     

Effect of orthodontic treatment on oral health–related quality of life

Objective:To assess changes in oral health–related quality of life (OHQoL) in children undergoing fixed orthodontic treatment and compare it to that of two groups not receiving treatment.Materials and Methods:Two hundred eighty-four subjects aged 12–15 years were followed for 2 years; 87 were undergoing treatment at a university clinic (TG), 101 were waiting for treatment at this clinic (WG), and 96 were attending a public school and had never sought treatment (SG). OHQoL was assessed using the Oral Health Impact Profile (OHIP-14). All subjects were examined and interviewed at baseline (T1), 1 year later (T2), and 2 years later (T3). OHIP-14 scores were analyzed using negative binomial regression in generalized estimating equations for correlated data.Results:During the follow-up period, the WG and TG OHIP-14 scores showed a statistically significant increase and decrease, respectively (P < .001). At T1, the TG had an OHIP-14 score that was 1.9 times higher than that of the SG; however at T3, the TG score was 60% lower than the initial score of the SG. Adjusting for age, gender, dental health status (DMFT), socioeconomic position, malocclusion severity, and self-perceived esthetics did not change the effect of orthodontic treatment on OHQoL.Conclusion:Fixed orthodontic treatment in Brazilian children resulted in significantly improved OHQoL after 2 years.     

The effect of N-acetylcysteine on the antibacterial capability and biocompatibility of nano silver–containing orthodontic cement

ObjectivesTo determine whether the incorporation of N-acetylcysteine (NAC) improves the antibacterial ability and biocompatibility of nano silver (NAg)–containing orthodontic cement.Materials and MethodsNAg was synthesized using a sodium citrate reduction method. NAg particles were characterized using transmission electron microscopy and ultraviolet-visible absorption spectra. NAg and NAC were incorporated into a resin-modified glass ionomer cement. Enamel shear bond strength (SBS), antibacterial capability, and cytotoxicity were evaluated.ResultsIncorporating 0.15% NAg and 20% NAC had no adverse effect on the SBS of orthodontic cement (P > .1). Adding NAC into NAg-containing cement greatly reduced the biofilm metabolic activity and lactic acid production (P < .05) and lowered the colony unit–forming counts by approximately 1 log (P < .05). The cell viability against NAg-containing cement was improved by NAC (P < .05).ConclusionsThe incorporation of NAC into NAg-containing cement achieved stronger antibacterial capability and better biocompatibility, without compromising the enamel SBS. The combined use of NAC and NAg is promising to combat caries in orthodontic practice.