脉冲激光辅助去除正畸金属托槽方法初探

目的 探讨脉冲Nd:YAG激光辅助去除正畸金属托槽的可行性,以期为临床提供一种优于机械性去除金属托槽的方法.方法 选择因正畸治疗拔除的50颗前磨牙,粘接托槽后根据随机数字表随机分为5组,每组10颗,实验1-4组分别接受13.0、13.5、14.0、14.5 A电流强度的激光照射,同时给予4.9 N的外力,直至托槽脱落,记录托槽脱落时间及牙髓腔内温度;剩余1组为对照组,使用持针器去除托槽.在体视显微镜下测量并计算粘接剂残留指数(adhesive remnant index,ARI).扫描电镜观察各组釉质表面情况.结果 实验1-4组的托槽脱落时间分别为(67.70 4±7.18)、(35.90±4.28)、(24.90 ±3.76)、(6.90±2.33)s.各组间差异均有统计学意义(P<0.01).实验1-4组牙髓腔内温度分别升高(20.97±3.10)、(12.75±3.14)、(8.99±2.47)、(2.91±1.88)℃,各组间差异均有统计学意义(P<0.05).实验1-4组和对照组Arl分别为(8.55±5.02)%、(15.42±7.37)%、(5.55±3.79)%、(13.72±6.69)%和(74.36±29.44)%,两两比较显示对照组与不同实验组间差异均有统计学意义(P<0.05),实验1-4组间差异无统计学意义(P>0.05).扫描电镜下可见对照组釉面横纹已被破坏,釉质表面粗糙不平;实验组釉质表面清洁,未见划痕、弹坑样及蜂窝样改变.结论 脉冲Nd:YAG激光辅助去除正畸金属托槽是一种可行的方法;与机械法相比,脉冲Nd:YAG激光辅助去除托槽及粘接剂的过程不破坏釉质表面结构.     

自锁托槽非拔牙矫治下牙列拥挤的临床研究

目的 比较自锁托槽和传统结扎式托槽非拔牙矫治牙列拥挤患者的下牙列变化,探讨自锁托槽解除牙列拥挤的机制.方法 选择26例下牙列拥挤患者,分为自锁组和传统组,每组13例,分别使用自锁托槽(Damon3)和传统托槽(传统结扎式托槽)进行非拔牙矫治.对矫治前后变化进行配对t检验,逐步回归分析拥挤解除机制以及影响下切牙唇倾度改变量的相关因素.结果 矫治前后两组患者下颌尖牙间、前磨牙间牙弓宽度改变量及下切牙唇倾度改变量比较,差异均无统计学意义(P>0.1);矫治后自锁组下颌第一磨牙间牙弓宽度增加1.42 mm、下切牙凸距增加2.66 mm,传统组下颌第一磨牙间牙弓宽度增加0.65 mm、下切牙凸距增加1.57 mm,两组比较,差异有统计学意义(P<0.1).回归分析显示,自锁组对下切牙唇倾度变化量解释的总测定系数高达96.6%,被选入模型的变量为矫治前下颌拥挤度、下颌平面角、第一磨牙间牙弓宽度,以及矫治前后尖牙及第一前磨牙间牙弓宽度改变量.结论 非拔牙矫治下牙列拥挤时,自锁组和传统组患者均出现下切牙唇倾及下牙弓宽度增加,自锁组第一磨牙间牙弓宽度增加量及下切牙前移量较传统组多;自锁组下切牙唇倾度的改变不仅受拥挤度和矫治前牙弓宽度影响,而且受患者自身骨面型及牙弓宽度变化的影响.     

Spectrophotometric analysis of dental bleaching after bonding and debonding of orthodontic brackets

IntroductionThe aim of this study was to evaluate the bleaching effect after aging simulation in teeth submitted to bonding and debonding of orthodontic brackets.Materials and methodsFor this study, 90 human premolars were selected, and randomly divided into 6 groups: control, bleaching, and other 4 groups submitted to bleaching after bonding and debonding brackets using different methods. Color measurement of sample through the CIE L*a*b* system was performed in three moments: T1 – after brackets debonding, T2 – after staining cycling, and T3 – after bleaching. For evaluation of results among the components L*, a* and b*, the two criteria analysis of variance and the multiple comparison Tukey test (p < 0.05) were used.ResultsStatistically significant difference was observed among the groups submitted to brackets bonding and debonding through self-conditioning adhesive system and tungsten drill, also the control and bleaching groups between the moments T1 e T2.ConclusionBonding and debonding brackets methods tested in this study showed influence on the sample color change, and after the tooth bleaching process, only the group without brackets previous bonding achieved the color value presented before the staining and aging of samples in the brackets absence.     

Debris and friction of self-ligating and conventional orthodontic brackets after clinical use

Objective:To compare the degree of debris and friction of conventional and self-ligating orthodontic brackets before and after clinical use.Materials and Methods:Two sets of three conventional and self-ligating brackets were bonded from the first molar to the first premolar in eight individuals, for a total of 16 sets per type of brackets. A passive segment of 0.019 × 0.025-inch stainless steel archwire was inserted into each group of brackets. Frictional force and debris level were evaluated as received and after 8 weeks of intraoral exposure. Two-way analysis of variance and Wilcoxon signed-rank test were applied at P < .05.Results:After the intraoral exposure, there was a significant increase of debris accumulation in both systems of brackets (P < .05). However, the self-ligating brackets showed a higher amount of debris compared with the conventional brackets. The frictional force in conventional brackets was significantly higher when compared with self-ligating brackets before clinical use (P < .001). Clinical exposure for 8 weeks provided a significant increase of friction (P < .001) on both systems. In the self-ligating system, the mean of friction increase was 0.21 N (191%), while 0.52 N (47.2%) was observed for the conventional system.Conclusion:Self-ligating and conventional brackets, when exposed to the intraoral environment, showed a significant increase in frictional force during the sliding mechanics. Debris accumulation was higher for the self-ligating system.     

Comparison of static friction with self-ligating,modified slot design and conventional brackets

Objective

To compare the static frictional forces generated at the bracket/wire interface of stainless steel brackets with different geometries and angulations, combined with orthodontic wires of different diameters.

Material and Methods

The frictional forces were evaluated with three different types of metal brackets: a passive self-ligating (SmartClip^TM, 3M/Unitek, Monrovia, USA), with a modified slot design (Mini Uni Twin^TM, 3M/Unitek, Monrovia, USA) and conventional (Kirium, Abzil, São José do Rio Preto, Brazil). The samples were mounted in a testing device with three different angulations and tested with 0.014" and 0.018" stainless steel wires (American Orthodontics, Sheboygan, USA). The static frictional force was measured using a universal testing machine (DL 500, EMIC^®, São José dos Pinhais, Brazil) with a crosshead speed of 1 mm/min. Statistical analysis was performed by two-way ANOVA followed by Bonferroni''s post hoc test.

Results

There was a significant difference (p<0.05) in static friction when the three types of brackets were tested with the same wire size. The wire diameter influenced friction only when the brackets had a 10º angulation (p<0.05). The angulation influenced friction (p<0.05) when the brackets were associated with a 0.018" wire.

Conclusion

Brackets with a modified slot design showed intermediate static frictional force values between the conventional and self-ligating brackets tested.     

自锁托槽与传统托槽矫治器对牙周健康影响的比较研究

目的 对比戴用自锁托槽与传统托槽矫治器后牙周指数的变化.材料和方法选取12～18岁正畸患者80例,按矫治器类型分为两组：实验组,40例采用AO公司生产的T3自锁托槽矫正的患者;对照组,采用杭州西湖公司生产的徐氏托槽矫正的患者40例.由同一牙周专科医师分别检测80例患者治疗前和治疗6个月的各项牙周指数（GI,PLI,SBI,PD）.结果 治疗6个月后两组间牙周指数（GI,PLI,SBI,PD）差异无显著性.结论 自锁托槽矫治器不会更有利于牙周组织的健康,牙周的健康状况取决于患者的口腔卫生状况.     

Frictional resistance of self-ligating versus conventional brackets in different bracket-archwire-angle combinations

Objective

To compare the influence of archwire material (NiTi, beta-Ti and stainless steel) and brackets design (self-ligating and conventional) on the frictional force resistance.

Material and Methods

Two types of brackets (self-ligating brackets - Smartclip, 3M/Unitek - and conventional brackets - Gemini, 3M/Unitek) with three (0, 5, and 10 degrees) slot angulation attached with elastomeric ligatures (TP Orthodontics) were tested. All brackets were tested with archwire 0.019"x0.025" nickel-titanium, beta-titanium, and stainless steel (Unitek/3M). The mechanical testing was performed with a universal testing machine eMIC DL 10000 (eMIC Co, Brazil). The wires were pulled from the bracket slots at a cross-head speed of 3 mm/min until 2 mm displacement.

Results

Self-ligating brackets produced significantly lower friction values compared with those of conventional brackets. Frictional force resistance values were directly proportional to the increase in the bracket/ wire angulation. With regard to conventional brackets, stainless steel wires had the lowest friction force values, followed by nickel-titanium and beta-titanium ones. With regard to self-ligating brackets, the nickel-titanium wires had the lowest friction values, significantly lower than those of other materials.

Conclusion

even at different angulations, the self-ligating brackets showed significantly lower friction force values than the conventional brackets. Combined with nickel-titanium wires, the self-ligating brackets exhibit much lower friction, possibly due to the contact between nickel-titanium clips and wires of the same material.     

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.     

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.     

Effect of lingual enamel sandblasting with aluminum oxide of different particle sizes in combination with phosphoric acid etching on indirect bonding of lingual brackets

Objective:To compare bond strength and bond failure location of lingual brackets indirectly bonded after lingual enamel sandblasting with 27-, 50-, and 90-µm aluminum oxide particles followed by 37% phosphoric acid etching.Material and Methods:Eighty maxillary premolars were randomly divided into four equal groups according to the method of lingual enamel surface conditioning: Group 1 (control) was etched with 37% phosphoric acid, and group 2, group 3, and group 4 were sandblasted with 27-, 50-, and 90-µm aluminum oxide particles, respectively, prior to acid etching. Lingual brackets were indirectly bonded using the same protocol and adhesive (Sondhi) in all groups. The maximum shear bond strength required to debond the brackets was measured using a testing machine, and the bond failure location was classified according to the adhesive remnant index (ARI). Analysis of variance was used to compare the mean bond strength between groups. The differences between ARI scores were evaluated using the Kruskal-Wallis test.Results:There were no statistically significant differences in mean shear bond strength or ARI scores between the four enamel-conditioning procedures.Conclusion:Lingual enamel sandblasting using different particle sizes of aluminum oxide prior to phosphoric acid etching did not increase the shear bond strength of indirectly bonded brackets and did not affect the amount of adhesive remnant on the enamel.     

Influence of different acid etching times on the shear bond strength of brackets bonded to bovine enamel

IntroductionThe most used product for surface acid conditioning for enamel is 37–40% phosphoric acid, which promotes greater mechanical retention.AimThe objective of this study was to compare the shear bond strength (SBS) of brackets bonded to bovine enamel with different acid conditioning protocols and to analyze the surface morphology.Materials and methods169 teeth (n = 13) were divided into 4 groups: control group without conditioning (G1), Dental Gel 37% phosphoric acid (Dentsply) (G2), Ultra Etch 35% (Ultradent) (G3) and Attaque gel 37% (Biodinâmica) (G4). Groups G2, G3 and G4 were subdivided according to the conditioning time into: 10 s (a), 15 s (b), 30 s (c) and 60 s (d). The superficial enamel morphology (n = 3) was analyzed using a scanning electron microscopy (SEM) to analyze the depth of the microporosities. The samples were submitted to the shear test (SBS) with the aid of a universal testing machine (INSTRON) with a speed of 1 mm/min. The enamel after debonding was analyzed to determine the adhesive remnant index (ARI) in a stereoscopic magnifying glass.Statistical analysis usedThe SBS data were analyzed using two-way ANOVA. ARI data were analyzed using generalized linear models and SEM measurements were analyzed using Kruskal Wallis and Dunn tests. The 95% significance level was used.ResultsThe SBS within G2, G3 and G4 ranged from 11.11 to 12.66 MPa. ARI score 3 was observed in 35% of the samples. The samples analyzed in the SEM showed microporosity depth rangingfrom 1.28 to 2.48 μm.ConclusionsThere was no difference between the acids and times evaluated for SBS. The ARI analysis showed that the studied acids provide protection to the enamel surface, keeping the adhesive attached to the buccal surface after debonding. The increase in conditioning time is directly proportional to the deterioration of the prismatic and interprismatic content.     

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.     

自锁托槽与传统托槽对非拔牙矫治牙弓宽度影响的meta分析

目的:系统评价自锁托槽与传统托槽在非拔牙矫治中牙弓宽度的变化。方法:检索Cochrane Library、ScienceDirect、PubMed、CBM、CNKI、维普全文数据库、万方数据库及Google文献检索,查找自锁托槽与传统托槽对非拔牙矫治牙弓形态影响的临床研究,检索时限从建库截至2013年5月。由2名研究者独立评价纳入研究的质量并提取资料,采用Sata10.0软件对纳入的研究进行meta分析。结果:纳入8项研究,共364例患者。Meta分析结果显示,自锁组与传统组相比,矫治前、后在上颌第一前磨牙区[WMD=0.724,95%CI(0.288,1.160);PU﹤0.01]、下颌第一磨牙区[WMD=0.564,95%CI(0.219,0.909);PL﹤0.01]宽度增加量和上前牙倾斜度增加量有显著差异。结论:现有的临床证据表明,在轻中度拥挤非拔牙矫治中,自锁托槽对上颌第一前磨牙和下颌第一磨牙区的扩弓效果优于传统托槽,且能更好地控制上前牙的倾斜度,但仍需更多高质量的临床研究予以验证。     

自锁托槽与传统托槽非减数矫治安氏Ⅱ类2分类错(牙合)机制初探

目的 比较自锁和传统托槽非减数矫治安氏Ⅱ类2分类错(牙合)畸形后牙弓及头影测量项目的变化,探讨各自解除拥挤的机制.方法 选取40例非减数矫治的安氏Ⅱ类2分类错(牙合)畸形患者,分别使用自锁托槽(自锁组,20例)和传统托槽(传统组,20例)解除牙列拥挤.测量两组患者治疗前后模型和头影测量项目,比较每组治疗前后差异及治疗差值的组间差异,并分析两组牙列拥挤解除的相关因素.结果 自锁组上颌第一前磨牙区牙弓宽度增加量[ (4.45 ±2.60) mm]和上颌牙弓周长增加量[(6.69±3.65) mm]显著大于传统组[分别为(2.41 ±2.74)和(3.60±2.82) mm] (P＜0.05).回归分析显示两组拥挤解除的相关因素均是牙弓宽度及牙弓长度的增加,但自锁组牙弓宽度对拥挤解除的贡献大于牙弓长度.结论 非减数矫治安氏Ⅱ类2分类牙列拥挤时,自锁组和传统组均通过牙弓宽度及牙弓长度的增加来解除拥挤,但自锁组更倾向于通过牙弓宽度增加解除拥挤,表现出更强的扩弓效果.     

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.