Transfer accuracy of vinyl polysiloxane trays for indirect bonding

Objective:To elicit the magnitude, directional bias, and frequency of bracket positioning errors caused by the transfer of brackets from a dental cast to the patient’s dentition in a clinical setting.Materials and Methods:A total of 136 brackets were evaluated. The brackets were placed on dental casts and scanned using cone beam computed tomography (CBCT) to capture 3-D positioning data. The brackets were then transferred to the patient’s dentition with an indirect bonding method using vinyl polysiloxane (VPS) trays and later scanned using CBCT to capture the final bracket positioning on the teeth. Virtual models were constructed from the two sets of scan data and digitally superimposed utilizing best-fit, surface-based registration. Individual bracket positioning differences were quantified using customized software. One-tailed t tests were used to determine whether bracket positioning was within limits of 0.5 mm in the mesiodistal, buccolingual, and vertical dimensions, and 2° for torque, tip, and rotation.Results:Individual bracket positioning differences were not statistically significant, indicating, in general, final bracket positions within the selected limits. Transfer accuracy was lowest for torque (80.15%) and highest for mesiodistal and buccolingual bracket placement (both 98.53%). There was a modest directional bias toward the buccal and gingival.Conclusion:Indirect bonding using VPS trays transfers the planned bracket position from the dental cast to the patient’s dentition with generally high positional accuracy.     

Treatment time,outcome, and anchorage loss comparisons of self-ligating and conventional brackets

Objective:To compare the treatment time, outcome, and anchorage loss among orthodontic patients treated by self-ligating brackets (SLBs) and conventional brackets (CBs).Materials and Methods:A retrospective cohort study compared 34 patients (SLB group) treated by SmartClip brackets (3M Unitek, Monrovia, Calif) to 35 patients (CB group) treated by conventional preadjusted Victory series brackets (3M Unitek) and ligated by stainless steel wire ligatures. Pretreatment (T1) and posttreatment (T2) lateral cephalograms were traced and analyzed using Pancherz sagittal-occlusion analysis to obtain skeletal and dental changes in the maxilla and the mandible. The dental cast models were assessed by the Peer Assessment Rating (PAR) Index for the treatment outcomes.Results:The mean treatment time for SLBs (19.19 months) did not show a statistically significant difference from 21.25 months of CBs; the treatment time and pretreatment PAR scores were strongly correlated. There was no difference in anchorage loss between the SLB and CB groups. There were significant dental and skeletal changes among adolescent orthodontic patients regardless of the bracket used. The lingual inclination of the mandibular incisors in the CB group was 3.62° more than in the SLB group (P < .01).Conclusions:The treatment time and anchorage loss are not influenced by the type of bracket used. There are significant dental and skeletal changes among adolescent orthodontic patients regardless of the bracket used. There is significantly greater lingual inclination of mandibular incisors in the CB group than in the SLB group.     

The effect of two different bracket types on the salivary levels of S mutans and S sobrinus in the early phase of orthodontic treatment

Objective:To determine the difference in the levels of Streptococcus mutans and S sobrinus in stimulated saliva in orthodontic patients with different bracket types (stainless steel and esthetic brackets) using polymerase chain reaction and cultivation method.Materials and Methods:Thirty-two patients, aged 13 to 30 years, were selected following these criteria: 1) orthodontic treatment indication, 2) systemic health, and 3) no tobacco and antibiotic consummation for three months prior to the commencement of the study. Patients were divided into two groups according to the bracket type; 16 patients formed the conventional bracket group (stainless steel brackets), and 16 patients formed the esthetic bracket group (plastic brackets). The levels of S mutans and S sobrinus in stimulated whole saliva samples were collected prior to fixed orthodontic appliance placement (T1) and 12 weeks after placement (T2), as were the Decayed, Missing, and Filled Surface Index (DMFS) and Oral Hygiene Index-Simplified (OHI-S). Mann-Whitney, Wilcoxon, and chi-square tests were used for statistical analysis.Results:Statistical analysis (chi-square test) showed no difference in S mutans and S sobrinus counts among patients with different brackets at either T1 or T2. There was no difference in total bacteria counts after fixed orthodontic appliance placement.Conclusion:The number of colony-forming units of S mutans and S sobrinus in stimulated saliva samples does not seem to be significantly different between patients with stainless steel brackets and patients with plastic brackets.     

A comparison of accuracy in bracket positioning between two techniques--localizing the centre of the clinical crown and measuring the distance from the incisal edge

The placement of orthodontic brackets is guided either by localizing the centre of the clinical crown (CC) or by measuring the distance from incisal edge (ME). The purpose of this study was to examine if there are any significant differences in the accuracy of bracket positioning between these two techniques. Typodont models were simulated with a Class I malocclusion with severe crowding. Nineteen experienced orthodontists (12 males, seven females) with a mean age of 40.6 years bonded pre-adjusted straight-wire brackets (Victory MBT) on the typodonts. Each orthodontist was asked to bond 20 brackets on one typodont using the CC method and 20 brackets on another typodont using the ME method. The teeth were removed from the typodont and photographed for imaging analysis. The errors of bracket placement in the vertical, mesiodistal, and angular/tip dimensions were measured and the data were statistically assessed. An overall test of significance, using all the data, rather than the means, demonstrated a significant vertical difference between the CC and ME methods, with the ME method more accurate vertically (mean CC = 1.19, mean ME = 1.10, P = 0.002) but no significant differences for mesiodistal (mean CC = -0.08, mean ME = -0.05, P = 0.28) or for tip (mean CC = -1.61, mean ME = -1.35, P = 0.34) errors. Analysis of the overall means and the arches independently showed that there was no significant difference in bracket accuracy between the two techniques (P > 0.05). Analysis of the teeth individually showed that the ME method was better in the vertical positioning for several upper and lower anterior teeth (P < 0.01) and poorer for the upper first premolars. The mean time taken to bond the 20 brackets showed no significant difference between two methods (CC 28.53 +/- 9.51 versus ME 28.21 +/- 10.43 minutes, P > 0.05). It is suggested that bracket bonding guided by measuring the distance from incisal edge may result in improved placement for anterior teeth. Archwire bending or bracket repositioning is still necessary to compensate for the inaccuracies with both techniques.     

A retrospective survey of the causes of bracket- and tube-bonding failures

Objective:To investigate the causes of bonding failures of orthodontic brackets and tubes and the effect of premedicating for saliva reduction.Materials and Methods:Premedication with atropine sulfate was administered randomly. Failure rate of brackets and tubes placed in a group of 158 consecutive patients was evaluated after a mean period of 67 weeks after bonding.Results:The failure rate in the group without atropine sulfate premedication was 2.4%. In the group with premedication, the failure rate was 2.7%. The Cox regression analysis of these groups showed that atropine application did not lead to a reduction in bond failures. Statistically significant differences in the hazard ratio were found for the bracket regions and for the dental assistants who prepared for the bonding procedure.Conclusions:Premedication did not lead to fewer bracket failures. The roles of the dental assistant and patient in preventing failures was relevant. A significantly higher failure rate for orthodontic appliances was found in the posterior regions.     

The impact of recycling and repeated recycling on shear bond strength of stainless steel orthodontic brackets

PurposeTo compare Shear Bond Strength (SBS) of new, recycled and repeated recycled stainless steel orthodontic brackets with and without bracket base primer.Materials and methods120 extracted human premolar teeth and 120 premolar stainless steel orthodontic brackets were divided into six groups for 20 teeth each. Orthodontic brackets of four groups were sandblasted with 50 μm aluminum oxide powder and half of them were recycled for second time. Light cure orthodontic adhesive primer was applied for half of total brackets. Light cure composite was applied for all brackets and polymerization was carried out. Groups 1–6 were subjected to a shear force within half hour to simulate as done clinically with a universal testing machine (Shimadzu Trapezium X) until the bracket debond.ResultsThe results of this study demonstrated that the mean SBS of all groups were more than that recommended by Reynolds in 1975, there was no significant difference between new and recycled brackets. Only one group (repeated recycled without bond) has significantly lower SBS.ConclusionIt can be concluded that: sandblasted recycled orthodontic brackets can be used as an alternative to new brackets which might provide cost reduction and in case of using repeated recycled brackets, better to apply bonding agent on bracket base for more bond strength.     

计算机辅助正畸托槽间接粘接技术的研究

目的研究计算机辅助下的正畸托槽间接粘接技术的可行性。方法采用激光扫描仪获取石膏牙颌模型的数字化信息,利用工程软件绘制真实大小的直丝弓托槽,在虚拟模型上实现托槽的定位,通过计算机辅助设计出用于托槽定位的个体托盘,并利用快速成型技术进行加工。结果通过计算机辅助设计及快速成型技术可以实现正畸托槽的间接粘接。结论计算机辅助正畸托槽的间接粘接,能够保证托槽的精确位置,同时节约椅旁占用时间,减少实验室操作步骤,可作为托槽间接粘接的新技术。     

Clinical bond failure of pre-coated and operator-coated orthodontic brackets

Objectives – To test the hypothesis that there is no significant difference in clinical bracket failure between the 3M APC Mini Twin? bracket system and the Transbond XT? adhesive during orthodontic treatment. Design – A randomized, split mouth, prospective clinical trial. Setting and Sample Population – The Department of Orthodontics and Dentofacial Orthopedics at University of Missouri, Kansas City. Twenty‐nine subjects who were treatment planned to receive comprehensive orthodontics using 0.018 slot appliances. Experimental Variable – The adhesive pre‐coated brackets (APC ) system was randomly assigned to one side of the mouth and the Transbond XT^TMwas assigned to the opposite side. Outcome Measure – The absence of any of the brackets at the time of a regular or emergency orthodontic appointment. Results – There was no significant difference (P > 0.05) in bracket failure between the 3M APC Mini Twin^TM bracket system and the Transbond XT^TM adhesive at any time period (90, 180, or 365 days). The failure rate of brackets on premolars was higher than on incisors or canines. Conclusion – APC Mini Twin^TM bracket system and Transbond XT^TMadhesive are equally effective in maintaining brackets clinically. Inexperienced operators had an overall 7.5% bond failure 12 months following bracket placement.     

Torque Expression in Stainless Steel Orthodontic Brackets: A Systematic Review

Objective:To evaluate the quantitative effects on torque expression of varying the slot size of stainless steel orthodontic brackets and the dimension of stainless steel wire, and to analyze the limitations of the experimental methods used.Materials and Methods:In vitro studies measuring torque expression in conventional and self-ligating stainless steel brackets with a torque-measuring device, with the use of straight stainless steel orthodontic wire without second-order mechanics and without loops, coils, or auxiliary wires, were sought through a systematic review process.Results:Eleven articles were selected. Direct comparison of different studies was limited by differences in the measuring devices used and in the parameters measured. On the basis of the selected studies, in a 0.018 inch stainless steel bracket slot, the engagement angle ranges from 31 degrees with a 0.016 × 0.016 inch stainless steel archwire to 4.6 degrees with a 0.018 × 0.025 inch stainless steel archwire. In a 0.022 inch stainless steel bracket slot, the engagement angle ranges from 18 degrees with a 0.018 × 0.025 inch stainless steel archwire to 6 degrees with a 0.021 × 0.025 inch stainless steel archwire. Active stainless steel self-ligating brackets demonstrate an engagement angle of approximately 7.5 degrees, whereas passive stainless steel self-ligating brackets show an engagement angle of approximately 14 degrees with 0.019 × 0.025 inch stainless steel wire in a 0.022 inch slot.Conclusions:The engagement angle depends on archwire dimension and edge shape, as well as on bracket slot dimension, and is variable and larger than published theoretical values. Clinically effective torque can be achieved in a 0.022 inch bracket slot with archwire torsion of 15 to 31 degrees for active self-ligating brackets and of 23 to 35 degrees for passive self-ligating brackets with a 0.019 × 0.025 inch stainless steel wire.     

双丝弓个性化舌侧托槽的计算机辅助设计

目的实现一种个性化托槽的计算机辅助设计,以便在临床矫治中显著减小前牙控根力,并且能够应用于拔牙病例。方法在包括患者牙根的整合牙颌模型上进行虚拟排牙,在排牙后的模型上绘制直丝弓和设计双丝直丝弓托槽,托槽通过托槽体的厚度补偿来实现弓丝的直丝化,在托槽上设计双槽沟,主槽沟为方槽沟,辅槽沟为圆槽沟,在主槽沟用方丝虚拟定位托槽后,用计算机辅助设计和制作的个性化托槽,将托槽的虚拟位置转移到患者牙齿上的实际粘接位置进行矫治。结果与方丝控根相比,双丝控根矫治力显著减小;唇侧或舌侧矫治时可以使用直丝弓,简化了临床弓丝弯制;虚拟排牙基于3D整合牙颌模型,可以在虚拟排牙中避免牙根的骨开裂、骨开窗和明显不平行。结论本研究为双丝弓个性化托槽的临床应用奠定了基础。     

一种尖牙控轴直丝托槽的结构设计

目的 设计一种用于错畸形的正畸治疗的新型托槽——尖牙控轴直丝托槽,对其结构设计和应用原理进行探讨分析.方法 定性设计矫治器的结构,托槽两个对角旋转翼与另两个对角翼可以通过旋转轴发生转动,能灵活选择放入弓丝前不锈钢丝结扎托槽与放入弓丝后弹性结扎托槽等结扎方式.结果 设计出一种尖牙正畸控轴直丝托槽,其特征是两对角托槽翼与另两个对角翼可以通过旋转轴发生转动,从而改变托槽槽沟的高度及宽度.结论 使用尖牙控轴托槽时,可以通过结扎尖牙控轴托槽的合龈翼来选择采取不同的矫治系统.     

Galvanic corrosion of metal injection molded (MIM) and conventional brackets with nickel-titanium and copper-nickel-titanium archwires

OBJECTIVE: To compare the galvanic coupling of conventional and metal injection molded (MIM) brackets with commonly used orthodontic archwires. MATERIALS AND METHODS: Six of each type of bracket were suspended in lactic acid along with a sample of orthodontic wire (three nickel-titanium and three copper-nickel-titanium) for 28 days at 37 degrees C. The potential differences between the wires and brackets were recorded per second throughout the duration of the experiment. RESULTS: The MIM brackets exhibited potential differences similar to those seen for the conventional brackets. The greatest potential difference was found for MIM brackets with nickel-titanium wires (512 mV), whereas MIM brackets with copper-nickel-titanium wires had the smallest difference (115 mV). Scanning electron microscope (SEM)-energy-dispersive spectroscopic analysis of the tie-wing area of each bracket type indicated similar elemental composition in both brackets, but in slightly different percentages by weight. The MIM bracket exhibited extensive internal porosity, whereas the conventional bracket was more solid internally. CONCLUSION: The composition and manufacturing processes involved in fabricating MIM brackets impart corrosive properties similar to those seen in the bracket-wing area of conventional brackets and may provide a measurable benefit when taking into account the increased corrosion between the bracket and brazing alloy of conventional brackets.     

自锁托槽对关闭拔牙间隙阶段滑动阻力的影响

目的 比较在牙齿关闭拔牙间隙过程中不同自锁托槽和传统托槽与不锈钢丝组合所产生的滑动阻力。方法 在干燥环境下,分别选择2种自锁托槽(被动Damon^®和主动Tomy^®)和传统托槽的2种结扎方式(橡皮结扎圈和结扎丝)与0.019×0.025英寸不锈钢丝组合,测量严重牙列拥挤患者在拔牙后排齐整平的下颌模型上关闭拔牙间隙阶段的滑动阻力。采用方差分析的方法对各项测量数据进行统计学处理。结果 在关闭拔牙间隙阶段,不同托槽组合、组间的滑动阻力的差异均具有显著的统计学意义(P<0.01),最大静摩擦力和滑动摩擦力由小到大依次为被动Damon组<主动Tomy组<结扎丝结扎组<结扎圈结扎组。结论 在关闭拔牙间隙阶段,被动自锁托槽的滑动阻力明显小于主动自锁托槽的滑动阻力,自锁托槽的滑动阻力明显小于传统托槽的滑动阻力。     

托槽在数字化牙颌模型上位置与间接粘结转移后实际位置的一致性研究

目的 本研究比较托槽在数字化牙颌模型上的位置与转移至初始石膏模型上的位置的差异,以期为数字化托槽间接粘结位置的一致性提供实验依据.方法 选取在含牙根的数字化牙颌模型上进行托槽定位的15个数字化模型,通过间接粘结转移托盘将托槽转移至初始石膏模型上,用OrthoRx软件工具测量每个托槽在数字化牙颌模型上的位置与初始石膏模型上位置的线距差.结果 所有牙位托槽在数字化牙颌模型上的位置与初始石膏模型上位置的线距差值均小于检验值0.20 mm,与检验值差异有统计学意义(P<0.05).结论 托槽在数字化牙颌模型上的位置与初始石膏模型上位置具有一致性.     

The reliability of positioning pre-adjusted brackets: an in vitro study.

To investigate the reliability of bracket positioning, twelve operators, familiar with the straight-wire appliance, placed 0.022" straight-wire brackets on the anterior teeth of a typodont study model, on three different occasions. Bracket position was assessed using a Magiscan image analyser. Angular judgements by the operators were found to be less consistently identified than linear assessments. Slot angulation showed the largest variability and vertical bracket placement the least. The clinical implications of bracket misplacement are discussed.     

The influence of orthodontic bracket base diameter and mesh size on bond strength.

Previous studies have shown that the size of the foil mesh and surface area of the bracket base correlated to bond strength to tooth enamel. The purpose of this study was to investigate the in vitro shear bond strength (SBS) of orthodontic brackets with 80 and 100 gauge mesh bases as well as mini and standard size bases. Eighty extracted human premolar teeth were randomly allocated into four groups of twenty teeth each. Premolar brackets of different mesh and bracket base area sizes were bonded to the enamel with a conventional 'two paste' orthodontic bonding agent. The SBS was determined and the bond failure sites were assessed using light-optical microscope and SEM. Bond failure occurred in all groups primarily at the bracket/adhesive interface. Mean values for SBS were 9.97 +/- 2.94 MPa and 10.72 +/- 2.54 MPa for 80 gauge mini and standard size respectively, and 10.45 +/- 3.27 MPa and 11.39 +/- 3.32 MPa for 100 gauge mini and standard size. A one-way ANOVA and an unpaired t-test revealed no significant difference in mean SBS (P > 0.05) between 80 and 100 gauge mini and standard size brackets, and no significant difference in mean SBS between brackets of the same surface area with a different gauge mesh size. The clinical relevance of this finding is that the clinician can select smaller brackets with no reduction in effectiveness of the treatment procedure.     

Changes in physical properties of new,non-BPA containing,polymeric orthodontic bracket materials over time: A 2-year clinical study

PurposeThe purpose of this study was to develop new, biocompatible plastic brackets which are esthetic and do not release bisphenol A (BPA).Materials and methodsIn this study, brackets were fabricated using four different materials: polyacetal (POM), polyester (PE) and polycarbonate (PC), and a filled polycarbonate (PCF) as a control. Clinical testing using 46 subjects was conducted to evaluate changes in their physical properties (fracture frequency of bracket wings, strength of bracket wings and bracket wear) over 2 years (at baseline, year 1 and year 2) to assess the suitability of these materials for clinical use.Results(1) PE brackets were the only group that showed fracture in the fracture frequency test. (2) POM showed low wear rates. (3) POM showed great variation in bracket wing strength, but no statistical significant difference was observed between PE and POM.ConclusionThis 2-year clinical study concludes that POM and PE are more promising materials for the fabrication of orthodontic brackets than PCF.     

A novel biomimetic orthodontic bonding agent helps prevent white spot lesions adjacent to brackets

Objective:To compare changes in enamel microhardness adjacent to orthodontic brackets after using bonding agents containing various compositions of bioactive glass compared to a traditional resin adhesive following a simulated caries challenge.Materials and Methods:Extracted human third molars (n  =  10 per group) had orthodontic brackets bonded using one of four novel bioactive glass (BAG)-containing orthodontic bonding agents (BAG-Bonds) or commercially available Transbond-XT. The four new adhesives contained BAG in varying percentages incorporated into a traditional resin monomer mixture. Teeth were cycled through low-pH demineralizing and physiologic-pH remineralizing solutions once each day over 14 days. Microhardness was measured on longitudinal sections of the teeth 100, 200, and 300 µm from the bracket edge and beneath the brackets, at depths of 25 to 200 µm from the enamel surface. Normalized hardness values were compared using three-way analysis of variance.Results:Significantly less reduction in enamel microhardness was found with the experimental adhesives at depths of 25 and 50 µm at all distances from the bracket edge. In all groups, there were no significant changes in enamel microhardness past 125-µm depth. Results varied with the different BAG-Bonds, with 81BAG-Bond showing the smallest decrease in enamel microhardness.Conclusions:The BAG-Bonds tested in this study showed a reduction in the amount of superficial enamel softening surrounding orthodontic brackets compared to a traditional bonding agent. The results indicate that clinically, BAG-Bonds may aid in maintaining enamel surface hardness, therefore helping prevent white spot lesions adjacent to orthodontic brackets.     

Microbial profile on metallic and ceramic bracket materials

The placement of orthodontic appliances creates a favorable environment for the accumulation of a microbiota and food residues, which, in time, may cause caries or exacerbate any pre-existing periodontal disease. The purpose of the present study was to compare the total bacterial counts present on metallic and ceramic orthodontic brackets in order to clarify which bracket type has a higher plaque retaining capacity and to determine the levels of Streptococcus mutans and Lactobacillus spp on both types of brackets. Thirty-two metallic brackets and 24 ceramic brackets were collected from orthodontic patients at the day of debonding. Two brackets were collected from each patient; one from a maxillary central incisor and another from a maxillary second premolar. Sixteen patients who used metallic brackets and 12 patients who used ceramic brackets were sampled. Bacterial populations were studied using "checkerboard" DNA-DNA hybridization, which uses DNA probes to identify species in complex microbial samples. The significance of differences between groups was determined using the Mann-Whitney U-test. Results showed no significant differences between metallic and ceramic brackets with respect to the caries-inducing S mutans and L acidophilus spp counts. Mean counts of 8 of 35 additional species differed significantly between metallic and ceramic brackets with no obvious pattern favoring one bracket type over the other. This study showed higher mean counts of Treponema denticola, Actinobacillus actinomycetemcomitans, Fusobacterium nucleatum ss vincentii, Streptococcus anginosus, and Eubacterium nodatum on metallic brackets while higher counts of Eikenella corrodens, Campylobacter showae, and Selenomonas noxia were found on ceramic brackets.     

Distortion of Metallic Orthodontic Brackets After Clinical Use and Debond by Two Methods

Abstract

The objective of this paper was to compare distortion of the wings and bases of metallic orthodontic brackets following clinical use and after debond by either of two methods, and took the form of a prospective random control trial. Five-hundred-and-seven brackets were debonded using either bracket removing pliers or a lift off debonding instrument (LODI). By a system of random allocation contralateral opposing quadrants were debonded with a 0.019 × 0.0025-inch archwire either in place or removed. After debond brackets were tested for slot closure by the fit of rectangular test wires from 0.016 × 0.022 to 0.021 × 0.025 inch size. The LODI produced few slot closures sufficient to affect the fit of all but the largest test wire. Bracket removing pliers used after removal of the archwire produced significantly greater numbers of distorted brackets in response to testing with all but the largest wire. With the 0.021 × 0.025 inch wire in place the presence or absence of the archwire at the time of debond made no difference to the number of slot closures. Ten per cent of the brackets debonded using bracket removing pliers had distorted bases, no base damage was produced by the LODI. The use of bracket removing pliers at debond caused significantly more slot closures than use of the LODI. When bracket removing pliers are used the archwire should be left in place at the time of debond since this reduces the number of distortions.