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。     

Clinical and microbiological parameters in patients with self-ligating and conventional brackets during early phase of orthodontic treatment

Objective:To determine the effect of different bracket designs (conventional brackets and self-ligating brackets) on periodontal clinical parameters and periodontal pathogens in subgingival plaque.Material and Methods:The following inclusion criteria were used: requirement of orthodontic treatment plan starting with alignment and leveling, good general health, healthy periodontium, no antibiotic therapy in the previous 6 months before the beginning of the study, and no smoking. The study sample totaled 38 patients (13 male, 25 female; mean age, 14.6 ± 2.0 years). Patients were divided into two groups with random distribution of brackets. Recording of clinical parameters was done before the placement of the orthodontic appliance (T0) and at 6 weeks (T1), 12 weeks (T2), and 18 weeks (T3) after full bonding of orthodontic appliances. Periodontal pathogens of subgingival microflora were detected at T3 using a commercially available polymerase chain reaction test (micro-Dent test) that contains probes for Aggregatibacter actinomycetemcomitans, Porphyromonas gingivalis, Prevotella intermedia, Tannerella forsythia, and Treponema denticola.Results:There was a statistically significant higher prevalence of A actinomycetemcomitans in patients with conventional brackets than in patients with self-ligating brackets, but there was no statistically significant difference for other putative periodontal pathogens. The two different types of brackets did not show statistically significant differences in periodontal clinical parameters.Conclusion:Bracket design does not seem to have a strong influence on periodontal clinical parameters and periodontal pathogens in subgingival plaque. The correlation between some periodontal pathogens and clinical periodontal parameters was weak.     

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.     

Speech performance and oral impairments with lingual and labial orthodontic appliances in the first stage of fixed treatment: A randomized controlled trial

Objectives:To compare (1) speech performance based on an auditive analysis and sonagraphy and (2) levels of oral impairment between fixed lingual and labial orthodontic appliances.Materials and Methods:Thirty-four patients with Class I division 1 malocclusion and moderate crowding of upper teeth were distributed randomly into two groups. Seventeen patients in group A (mean age: 20.6 years; standard deviation [SD]: 2.9 years) were treated with fixed lingual appliances (Stealth®, AO, Sheboygan, Wisc), whereas 17 patients in group B (mean age: 21.8 years; SD: 3.3 years) were treated with conventional fixed labial appliances. Speech performance was tested using spectrographic analysis of fricative /s/ sound before, immediately after (T1), 1 month after, and 3 months after bracket placement. The levels of oral impairment were assessed using standardized questionnaires.Results:A significant deterioration in articulation was recorded at all assessment times in group A but only at T1 in group B. Significant intergroup differences were recorded at all assessment times (P < .001). Speech difficulties were significantly higher in the lingual brackets group after 1 month of bracket placement (P < .001). Soft tissue irritation and chewing difficulty were significantly higher in the lingual appliance group after 24 hours of bracket placement (P < .001).Conclusions:The lingual appliance is more problematic than the labial one in terms of speech articulation. Although patients with both appliances suffered from different degrees of oral impairment, patients with lingual appliances had more untoward effects, particularly during the first month of treatment.     

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 the bracket types on microbial colonization and periodontal status

Objective:To evaluate the effect of different bracket types on the levels of Streptococcus mutans (SM) and Lactobacillus (LB) in saliva, in plaque, and on the periodontal condition.Materials and Methods:Forty patients aged 14 to 16 years, who had Angle Class I malocclusion with minimal crowding, were nonsmokers, were without systematic disease, and did not use antibiotics or oral mouth rinses during the 3-month period before the study were randomly selected. The patients were subdivided into two groups with random allocation of bracket type: conventional brackets (CB; Avex Mx, OPAL orth.) with steel wire ligature or self-ligating brackets (SLB; F1000, Leone S.p.A.). Microbial and periodontal records were obtained before bonding (T₁) and 1 month after bonding (T₂). Microbial samples were collected from the stimulated saliva and the plaque from the labial surfaces of the upper and lower lateral incisors. To estimate the number of colony-forming units of SM and LB, Dentocult SM and LB kits were used. The plaque index (PI), gingival index (GI), and pocket depth (PD) values were recorded to evaluate the periodontal condition. Paired t-test and Mann-Whitney U-test were used to compare the groups statistically.Results:No significant differences occurred in SM or LB colonization between the groups. In the SLB group, PI, GI, and PD values increased significantly (P < .05). A greater increase was found in PD value in the SLB group (0.98 mm) compared with the CB group (0.04 mm; P < .05).Conclusions:The F1000 SLB do not have an advantage over Avex Mx CB with respect to periodontal status and colonization of SM and LB.     

Caries Risk Factors in Children under Treatment with Sectional Brackets

Objective:To longitudinally investigate the caries risk levels in children undergoing orthodontic treatment with sectional brackets.Materials and Methods:A total of 42 children scheduled for orthodontic treatment with sectional orthodontic appliances participated in this study. They were divided into two groups based on decayed, missing, and filled permanent and deciduous teeth (DMFT/dmft) scores and counts of mutans streptococci (MS) prior to treatment. One was the low caries risk group (n  =  26) and the other was the high caries risk group (n  =  16). Paraffin-stimulated whole saliva was collected for examination of salivary flow rate, buffer capacity, and MS and lactobacilli (LB) levels before treatment, 2 and 4 months after appliance placement, and 2, 4, and 8 months after appliance removal.Results:The pretreatment salivary flow rates, buffer capacity, and MS levels remained statistically unchanged during and after active orthodontic treatment in both groups. The levels of LB in the high caries risk group were significantly elevated by appliance placement, but upon appliance removal started to fall significantly and came a little short of the pretreatment levels. In the low caries risk group, the pretreatment levels of LB remained statistically unchanged during and after treatment. There were no significant differences in salivary flow rate or buffer capacity, but there were significant differences in MS and LB scores between the two groups at every measurement time.Conclusions:In children undergoing orthodontic treatment with sectional brackets, LB levels are an important part in making caries risk assessment.     

Canine retraction rate with self-ligating brackets vs conventional edgewise brackets

Objective:To compare the rates of retraction down an archwire of maxillary canine teeth when bracketed with a self-ligating bracket was used on one side and a conventional bracket on the other.Materials and Methods:In 43 patients requiring maxillary premolar extraction, a self-ligating bracket (Damon3, SmartClip) was used on the maxillary canine on one side and a conventional bracket (Victory Series) on the other. The teeth were retracted down a 0.018-inch stainless steel archwire, using a medium Sentalloy retraction spring (150 g). The rates of retraction were analyzed using a paired t-test.Results:The mean movement per 28 days for the conventional bracket was 1.17 mm. For the Damon bracket it was 0.9 mm and for the SmartClip bracket it was 1.10 mm. The differences between the conventional and self-ligating brackets were statistically significant: paired t-test, SmartClip, P < .0043; Damon3, P < .0001).Conclusion:The retraction rate is faster with the conventional bracket, probably because of the narrower bracket width of the self-ligating brackets.     

A study on changes in caries risk and microbial flora with the placement of edgewise appliance

The aim of this study was to evaluate the changes of caries risk and oral microbial flora in the patients having edgewise appliance. Forty-two patients treated at the Orthodontic Clinic of Niigata University Hospital participated. Using a caries risk examination kit by Bio Medical Laboratory (BML, Tokyo), stimulated saliva test was performed to investigate the salivary flow rate, pH of saliva, buffer capacity, and the levels of lactobacilli. Modified Mitis–Salivarius–Bacitracin (MSB) agar plates were used to detect and count Streptococcus mutans and S. sobrinus. Furthermore, the members of commensal bacteria and transient bacteria in aerobic culture medium were examined in salivary level to investigate the alterations in oral microbial flora. The number of mutans streptococci and lactobacilli decreased after 1 month of treatment, and then increased to reach the initial level at 3 months. While the amount of plaque increased and saliva pH deteriorated after the onset of treatment, the salivary flow rate improved. The number of transient bacteria showed a tendency toward an increase. These results demonstrate that both caries risk and oral microbial flora balance possibly change with the placement of appliances. Therefore, caries risk test should be performed before and during orthodontic treatment to monitor alterations in intraoral environment of the orthodontic patients not to cause an iatrogenic caries.     

Evaluation of stresses developed in different bracket-cement-enamel systems using finite element analysis with in vitro bond strength tests

Background

The purpose of this study was to determine the bond strength of different orthodontic bracket materials (ceramic, stainless steel, and titanium) as well as stresses developed in bracket-cement-enamel systems using finite element (FE) analysis.

Methods

One hundred and thirty-five extracted human caries-free upper central incisors were divided into three groups (n = 45/group) according to the type of orthodontic bracket materials (stainless steel, ceramic, and titanium). Each group was further subdivided into three subgroups (n = 15/group) according to the bond strength test loading mode (shear short side, shear long side, and tensile). After debonding, the fractured specimen was examined, and the adhesive remnant index (ARI) was determined. FE analysis models analyzed the stress distribution within the cement and enamel. Bond strengths were analyzed using ANOVA and Tukey''s test, and the ARI scores were analyzed using chi-square (χ²) test.

Results

Shear loading at the short side of the bracket resulted in the highest bond strength and lowest maximum principal stress both on cement and enamel compared with the other loading modes (P < 0.05). Ceramic brackets presented with higher bond strength and lower maximum principal stress than metallic brackets (P < 0.05). There was a significant difference for ARI scores between the type of brackets (χ² = 64.852, P < 0.001).

Conclusion

The findings suggest that the manner of loading orthodontic brackets and the selection of orthodontic bracket materials affect the bond strength and stresses developed both on cement and enamel.     

Orthodontic appliances did not increase risk of dental caries and periodontal disease under preventive protocol

Objectives:To assess periodontal parameters and microbial species levels after orthodontic appliance placement in patients who received oral hygiene instructions and who were monitored and motivated throughout the study.Materials and Methods:The Periodontal Index was recorded and saliva collection was performed before (T0) and 30 (T1), 60 (T2), and 90 (T3) days after orthodontic appliance placement in 15 patients (mean age 17.53 ± 8.0 years). Analysis was carried out using checkerboard DNA-DNA hybridization. Nonparametric statistical analysis was performed.Results:The Periodontal Index did not change. The total amount of the purple and red complexes and Candida species showed a significant decrease from T2. The green, yellow, and orange complex showed a significant decrease at T3. The specific species analysis showed that Prevotella nigrescens, Pseudomonas putida, Fusobacterium periodonticum, Pseudomonas aeruginosa, Peptostreptococcus anaerobius, and Tanerella forsythia showed high incidence before bonding, and their levels decreased at T2 and T3. Only Porphyromonas gingivalis showed increased levels at T2 and displayed the highest level at T3. The Streptococcus group decreased their levels from T2 onward.Conclusions:A dynamic change in microbial levels was identified. The decrease in the levels of complexes present was only possible due to the mechanical method of oral hygiene implemented in this sample.     

Failure patterns of different bracket systems and their influence on treatment duration: A retrospective cohort study

Objectives:To compare the failure pattern of four different bracket types and to assess its effect on treatment duration.Materials and Methods:A total of 78 white patients (28 male, 50 female) with a mean age of 12.6 years were included in this retrospective cohort study and treated for a mean period of 30.6 months. The patients were treated in a private practice with stainless steel conventionally ligated brackets, ceramic conventionally ligated brackets, stainless steel self-ligating brackets, or nickel-free self-ligating brackets. The loss of at least one bracket during the course of treatment was analyzed with Cox proportional hazards survival analyses and generalized linear regression.Results:The overall bracket failure rate at the tooth level was 14.1% (217 brackets), with significant differences according to tooth type (between 8.0%–23.4%) and bracket type (between 11.2%–20.0%). After taking confounders into account, patients treated with ceramic brackets lost more brackets (hazard ratio = 1.62; 95% confidence interval = 1.14–2.29; P = .007) than patients with stainless steel brackets. On average, treatment time increased by 0.6 months (95% confidence interval = 0.21–1.05; P = .004) for each additional failed bracket.Conclusions:Bracket failure was more often observed with ceramic brackets and was associated with increased treatment duration.     

Quantitative analysis of S. mutans and S. sobrinus cultivated independently and adhered to polished orthodontic composite resins

In Orthodontics, fixed appliances placed in the oral cavity are colonized by microorganisms.

Objective

The purpose of this study was to quantitatively determine the independent bacterial colonization of S. mutans and S. sobrinus in orthodontic composite resins.

Material and methods

Seven orthodontic composite adhesives for bonding brackets were selected and classified into 14 groups; (GIm, GIs) Enlight, (GIIm, GIIs) Grengloo, (GIIIm, GIIIs) Kurasper F, (GIVm, GIVs) BeautyOrtho Bond, (GVm, GVs) Transbond CC, (GVIm, GVIs) Turbo Bond II, (GVIIm, GVIIs) Blugloo. 60 blocks of 4x4x1 mm of each orthodontic composite resin were made (total 420 blocks), and gently polished with sand-paper and ultrasonically cleaned. S. mutans and S. sobrinus were independently cultivated. For the quantitative analysis, a radioactive marker was used to codify the bacteria ⁽³H) adhered to the surface of the materials. The blocks were submerged in a solution with microorganisms previously radiolabeled and separated (210 blocks for S. mutans and 210 blocks for S. sobrinus) for 2 hours at 37ºC. Next, the blocks were placed in a combustion system, to capture the residues and measure the radiation. The statistical analysis was calculated with the ANOVA test (Sheffè post-hoc).

Results

Significant differences of bacterial adhesion were found amongst the groups. In the GIm and GIs the significant lowest scores for both microorganisms were shown; in contrast, the values of GVII for both bacteria were significantly the highest.

Conclusions

This study showed that the orthodontic composite resin evaluated in the GIm and GIs, obtained the lowest adherence of S. mutans and S. sobrinus, which may reduce the enamel demineralization and the risk of white spot lesion formation.     

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.     

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.     

Use of the checkerboard DNA-DNA hybridisation technique for in vivo detection of cariogenic microorganisms on metallic brackets, with or without use of an antimicrobial agent

Objective

Using checkerboard DNA-DNA hybridisation (CDDH) assay, this randomised clinical study evaluated the contamination of metallic brackets by four cariogenic bacterial strains (Streptococcus mutans, Streptococcus sobrinus, Lactobacillus casei and Lactobacillus acidophilus) and the efficacy of 0.12% chlorhexidine gluconate (CHX) mouthwashes in reducing bacterial contamination.

Methods

Thirty-nine 11-33-year-old patients under treatment with fixed orthodontic appliances were enrolled in the study and had 2 new metallic brackets bonded to premolars. Nineteen patients used a 0.12% CHX mouthwash (Periogard^®) and 20 patients used a placebo mouthwash (control) twice a week. After 30 days, the brackets were removed and samples were obtained for analysis by CDDH. Data were analysed statistically by the Kruskal-Wallis test (α = 0.05) using the SAS software.

Results

S. mutans, S. sobrinus, L. casei and L. acidophilus were detected in 100% of the samples from both groups. However, brackets of the control group were more heavily contaminated by S. mutans and S. sobrinus (P < 0.01). In the experimental group, although all counts decreased after rinsing with the chlorhexidine solution, there was significant difference only for S. mutans (P = 0.03).

Conclusions

The use of 0.12% chlorhexidine gluconate mouthwashes can be useful in clinical practice to reduce the levels of cariogenic microorganisms in patients under treatment with fixed orthodontic appliances.     

Adhesion of Streptococcus mutans to different types of brackets

OBJECTIVE: To examine the difference in the adhesion of Streptococcus mutans to three different types of orthodontic brackets and the effect of the presence of an early salivary pellicle and Streptococcus sanguis on adhesion. MATERIALS AND METHODS: Three adhesion experiments were performed using stainless steel, ceramic, and plastic orthodontic brackets. In the first experiment a clinical strain of S mutans adhered to the three different types of brackets (n = 6 for each). For the second, the brackets were treated with saliva before adhesion of S mutans (n = 6 per type of bracket). Finally, the third experiment concerned saliva coated brackets (n = 6 per type of bracket), but before S mutans, S sanguis bacteria were allowed to adhere. The bacteria were always allowed to adhere for 90 minutes in all the experiments. Adhesion was quantitated by a microbial culture technique by treating the brackets with adhering bacteria with trypsin and enumerating the total viable counts of bacteria recovered after cultivation. RESULTS: There were consistently no differences in the adherence to stainless steel, ceramic, or plastic brackets. The presence of an early salivary pellicle and S sanguis reduced the number of adhering S mutans to all three types of brackets. CONCLUSIONS: Adhesion of bacteria to orthodontic brackets depends on several factors. The presence of a salivary pellicle and other bacterial species seem to have a significant effect on the adhesion of S mutans, reducing their numbers and further limiting any differences between types of brackets.     

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.     

A randomized clinical trial comparing ‘one-step’ and ‘two-step’ orthodontic bonding systems

Abstract

Objective: The primary objective of this prospective clinical trial was to assess the clinical bond failure rates of orthodontic brackets bonded using a self-etching primer (SEP), compared with brackets bonded using a conventional acid-etched technique with control adhesive (Transbond?). A secondary aim was to investigate whether characteristics of the operator, patient or tooth bonded had any influence on bracket failure.

Design: Single-centre randomized controlled clinical trial. Thirty-four patients were bonded, each being randomly assigned to either the test or control adhesive.

Setting: NHS Hospital Orthodontic Department, Chester, UK.

Subjects: Orthodontic patients requiring fixed appliance treatment.

Main outcome measures: Bond failure.

Main outcome results: Failure rates over the initial 6-month period were 2.0% (Transbond?) and 1.7% (SEP) with no statistically significant difference between the two groups. Over the duration of the fixed appliance treatment, bond failure rates increased, but remained acceptable at 7.4 % (TB) and 7.0% (SEP), respectively. When operator, patient and tooth characteristics were analysed, only the bracket location was found to be significant. Maxillary brackets were more likely to fail than mandibular brackets (RR 0.47%; 95% CI 0.22, 1.03). The failure rate for brackets in our study was low when compared with previous studies.

Conclusions: Both the acid-etched control and self-etching primer in combination with adhesive pre-coated brackets were successful for clinical bonding. Their combined failure rate was lower than that reported in similar trials.