Bond failure patterns in vivo

Comparative in-vivo bond failure rate of orthodontic brackets when bracket base is treated with micro-abrasive blasting vs. acid etching: eighteen month randomized control trial and scanning electron microscope study

Background

The aim of this study was threefold. Firstly, it aimed to introduce and detail a novel method for chemically etching the bases of stainless-steel orthodontic brackets. Secondly, the study sought to investigate the structural alterations within the brackets' microstructure following chemical etching compared to those with sandblasted bases, using electron microscopy analysis. Lastly, the study aimed to evaluate and compare the long-term durability and survivability of orthodontic brackets with chemically etched bases versus those with sandblasted bases, both bonded using the conventional acid etch technique with Transbond XT adhesive, over an 18-month follow-up period.

Methods

The study was a randomized clinical control trial with triple blinding and split-mouth study design and consisted of two groups. The brackets in the sandblasted group were prepared by sandblasting the intaglio surface of the base of the bracket with 50 µm SiO2 particles. Hydrofluoric acid was used to roughen the base in the acid-etched group. The bases of the brackets were viewed under an electron microscope to analyze the topographical changes.

Results

A total of 5,803 brackets (3,006 acid-etch, 2,797 sandblasted) in 310 patients were bonded, in a split-mouth design by the same operator. The patients were followed for 18 months. The failure rate of 2.59% and 2.7% was noted in an acid-etched and sandblasted group, respectively. There was a close approximation of curves in the Kaplan-Meier plot, and the survival distribution of the two groups in the log-rank (Mantel-Cox) test was insignificant; x2 = 0.062 (P value = 0.804).

Conclusion

Acid etching if the bases of the brackets can be used as an alternative to sandblasting furthermore acid etching can be performed on the chair side.

Clinical performance of short fiber reinforced composite and glass hybrid on hypomineralized molars: A 36-month randomized split-mouth study

OBJECTIVES

This study aimed to assess the clinical performance outcome at 36 months of molars with molar incisor hypomineralization and carious lesions, treated with two different restorative approaches following selective caries removal.

METHODS

The children aged 6 to 12 years (18 female, 13 male) included in the study had at least two carious permanent first molars diagnosed with molar incisor hypomineralization. Sixty-two molars were restored in a split-mouth design. In all subjects, selective caries removal was performed so that caries was completely removed from the cavosurface walls and only soft dentin was left above the pulp chamber. Short fiber reinforced composite (SFRC; EverX Flow™) covered by micro-hybrid composite (G-Aenial® posterior composite) and Glass Hybrid (GH; Equia Forte® HT) were used as restorative materials. The restorations were evaluated according to modified United States Public Health Service (USPHS) criteria at baseline, 6, 12, 18, 24, and 36 month follow-ups.

RESULTS

During the 36-month follow-up, eight GH and four SFRC restorations failed. The clinical success of both restorations decreased statistically over time (p < 0.001 for both). When variables such as restoration type, sex, age, tooth type, and time were included in the model, the risk of failure of the restorations of the left lower first molar was statistically significantly higher than that of the left upper first molar (p < 0.002).

CONCLUSION

Direct composite restorations with SFRC and GH restorations perform similar clinical success with selective caries removal in the management of permanent molars affected by molar incisor hypomineralization.

CLINICAL SIGNIFICANCE

SFRC or GH restorations with similar clinical success might be preferred for the management of MIH-affected molars.

An Assessment of Mineral Concentration of Dental Enamel Neighbouring Hypothetical Orthodontic Brackets Using X-ray Microtomography

OBJECTIVES

Differences in the mineral concentration (MC) level of dental enamel may represent a precursor of white spot lesions adjacent to fixed orthodontic brackets. The aim of the current in vitro study was to compare the MC level central, occlusal and cervical to orthodontic attachments.

METHODS AND MATERIALS

A total of 16 enamel blocks were obtained from sound human premolar samples extracted for orthodontic reasons. The buccal portion of the dental enamel blocks was divided into central, occlusal, and cervical regions and then imaged and measured to calculate the level of MC using quantitative X-ray microtomography methods (XMT) at each site.

RESULTS

There was a substantial variation in the mineral concentration with the lowest level being detected in the cervical region when compared with other regions. The MC of the gingival zone was significantly lower than that of the middle zone (P<0.05) and was insignificantly lower than that of the occlusal zone.

CONCLUSION

Within the limitations of the current study, it can be concluded that the cervical region of the permanent enamel had the lowest mineral concentration using XMT. The cervical region may therefore be more vulnerable to the development of white spot lesions (WSLs) adjacent to a fixed orthodontic appliance during orthodontic treatment.

CLINICAL SIGNIFICANCE

Using X-ray microtomography lower mineral concentration in the cervical region of the enamel was observed. This may make these areas particularly susceptible to demineralisation during fixed appliance-based orthodontic treatment and may influence the bond strength of fixed orthodontic attachments.

Bracket Failure in Orthodontic Patients: The Incidence and the Influence of Different Factors

Failure of brackets is a common problem in orthodontics. This affects the treatment time, cost, and compliance of the patient. This study was conducted to estimate the bracket failure rate and the related factors for the long term. Methodology. This ambidirectional cohort study included 150 nonsyndromic orthodontic patients undergoing fixed appliance therapy for the last two years. The same patients were followed for 7 months. Different variables related to bracket failure were evaluated. The available data were analyzed descriptively, and the Kaplan-Meier estimate was used to measure the bracket survival rate from the date of bonding to failure. Results. A total of 180 bracket bond failures in the 150 included patients (52.2% males and 47.8% females) with a median age of 17 years (range 10-25 years). 69% of brackets failures were reported within the first 6 months after bonding. About 58.3% of bracket failure was noticed in adolescent patients before the age of 18 years. The majority of the cohort (81.1%) has good oral hygiene. The failure rate in patients with normal overbite was 41.1%, in decreased overbite cases was 15%, while in deep bite cases the failure rate was 43.9% with a statistically significant difference. Adults show less bracket failure (41.7%) than adolescent patients (58.3%). More bracket failure was noted in the lower arch (55%) than the upper arch (45%), and there were more bond failures posteriorly (61%) than on the anterior teeth (39%). Majority (41.1%) of the bracket failed on round NiTi wires. Conclusion. The bracket failure rate was 6.4%, with most bracket failure occurring in the first 6 months after bonding with individual difference. There was more incidence of bond failure in an increased overbite, adolescents, lower arch, posterior teeth, and lighter alignment wires.

Comparison of enamel surface roughness and color alteration after bracket debonding and polishing with 2 systems: A split-mouth clinical trial

INTRODUCTION

This split-mouth randomized clinical trial aimed to compare the enamel surface roughness (SR) and color alteration after bracket debonding and polishing using 2 systems.

METHODS

After removal of excess adhesive using a 12-blade tungsten carbide bur on a low-speed handpiece, a randomized polishing procedure using Sof-Lex discs was applied on 1 side (n = 36) and Sof-Lex Spiral Wheels on the contralateral side (n = 36). Dental replicas were obtained with epoxy resin before bracket bonding and after tooth polishing. The SR was evaluated using a profilometer. The color was assessed using an Easyshade spectrophotometer before bracket bonding, immediately after tooth polishing, and 30 days after polishing. Two-way analysis of variance and t tests were applied for statistical analysis.

RESULTS

The SR of enamel showed similar results between the polishing systems (P = 0.309) and between moments (before bracket bonding and after tooth polishing) (P = 0.317). The color change was also similar between the polishing systems (P >0.05).

CONCLUSIONS

The Sof-Lex discs and Sof-Lex Spiral Wheel polishing systems used after removal of excess adhesive using a 12-blade tungsten carbide bur on a low-speed handpiece did not appear to significantly damage the enamel surface, and the color change was similar between them.

Failure rates among metal brackets cured with two high-intensity LED light-curing lamps: an in vivo study

OBJECTIVE

The objective of this split-mouth clinical trial was to compare bonding failure rates of metal brackets bonded with two different light-emitting diode (LED) light-curing lamps with different high-intensity power outputs.

MATERIALS AND METHODS

Forty patients were included for a total of 800 brackets that were randomly bonded (left and right sides in a 1:1 ratio) in maxillary and mandibular arches using two different LED devices. An LED of 3200 mW/cm2 and an LED of 5000 mW/cm2 were used in this split-mouth clinical trial. Bonding failures during the initial 6 months of orthodontic treatment were recorded as maxillary versus mandibular, anterior teeth versus posterior teeth, and left side versus right side.

RESULTS

Five dropouts were recorded for discontinuing orthodontic treatment and 700 brackets were analysed in total. The bonding failure rates for 3200 and 5000 mW/cm2 LEDs were 6.0 and 7.4 per cent, respectively (P = 0.450), which were not statistically significantly different. There were no significant differences in bracket survival rates between the LEDs used (P = 0.866). The posterior teeth presented a higher index of bond failures (odds ratio, 3.14; 95% confidence interval, 1.68-5.87; P < 0.001).

LIMITATIONS

Direct comparison was only done between two high-intensity LED lights rather than against conventionally used halogen lights.

CONCLUSION

Similar bonding failures were recorded using both LED devices (3200 and 5000 mW/cm2). Significantly more bonding failures occurred in premolar teeth than in anterior teeth.

Appointment impact and orthodontic emergency occurrence during the coronavirus disease 2019 pandemic: A retrospective study

Introduction

This retrospective study aimed to quantify the impact of coronavirus disease 2019 (COVID-19) on the orthodontic appointment and make an analysis of orthodontic emergencies (OEs) that occurred during the pandemic.

Methods

A total of 628 patients were randomly sampled from 3489 subjects who were undergoing active orthodontic treatment with fixed appliances, and the medical records were reviewed. OE occurrence was analyzed from 617 patients who had explicit return-visit records after the COVID-19 outbreak. Wilcoxon signed rank tests, chi-square tests, and a binary logistic regression were performed.

Results

The return-visit of 98.6% of the patients was delayed significantly with an increase over 8.98 ± 4.76 weeks (P <0.001). In general, 32.3% of the patients suffered from various OEs while waiting for their first return-visit, and bracket or band debonding was the most frequently reported category. Most OEs did not receive timely treatments because of the lockdown. The incidence was nearly 2 times higher than that of the normal appointment times. No correlation was found between OE occurrence and different demographic and clinical characteristics of patients. The therapeutic progress of patients, especially those in stage 3, was postponed because of the occurrence of OEs.

Conclusions

Regardless of the limitations, our study suggested that it is highly possible that the COVID-19 pandemic has delayed appointments of fixed orthodontic patients. OEs did bother a minority of patients and could not be settled in time during the lockdown, which had a negative impact on the near-term treatment progress and should have been prevented. Further studies are required to investigate the long-dated influence of COVID-19 on orthodontic practices.

Influence of Patient Attitude on Bracket Failure Rate: A Prospective Study

Objective:

The aim of this study is to assess the influence of general attitude and attitude toward orthodontic treatment on bracket failure rate.

Methods and Materials:

The sample comprised 128 orthodontic patients of both genders (82 women and 46 men), divided into two groups—adolescents (12-18 years old) and adults (19-25 years old), who underwent fixed orthodontic treatment with metallic braces. Two questionnaires were handed out—one before beginning the treatment and, the second, 6 months after the start of treatment. Both the questionnaires consisted of 12 questions with 5 options each, in which the attitude was scored from 1 to 5.

Conclusion:

Patients with poor attitude scoring had higher bracket failure rate and vice versa.

Urgencies and emergencies in orthodontics during the coronavirus disease 2019 pandemic: Brazilian orthodontists' experience

Introduction

The present study aimed to evaluate the most common urgencies and emergencies in orthodontics during the coronavirus disease 2019 (COVID-19) pandemic and to assess how orthodontists in Brazil were dealing with patients and challenges.

Methods

Early in 2020, as the COVID-19 pandemic spread around the world, routine dental care was suspended in many countries, and only patients needing urgent or emergency care could be seen. During this period, orthodontists in Brazil were invited to participate in an anonymous online survey. Over 48 hours (May 1-3, 2020), 395 orthodontists (specialists, MScs, and PhDs) responded. They answered questions regarding dental office and appointments during the pandemic, the type of urgency or emergency care provided, the type of appliance and urgencies, etc. The level of concern about the impact of the pandemic on patients' orthodontic treatments and the financial impact on the dental office was also evaluated. Descriptive statistics were performed with percentages, and responses were compared between specialists, MScs, and PhDs, using chi-square tests.

Results

Specialists were the majority of respondents. Most orthodontists were handling only emergencies or urgencies. The most frequent urgencies were bracket breakage, archwire breakage, and breakage of molar tubes and/or bands. Stainless steel fixed appliances were the most common type of appliance related to unscheduled appointments. The majority of patients got in touch with the orthodontist using the professional WhatsApp messenger (WhatsApp Inc, Menlo Park, Calif). Orthodontists were more concerned with the financial impact of the pandemic than with the orthodontic treatment itself.

Conclusions

Breakage of brackets, archwires, or tubes and/or bands were the most common causes of urgency and/or emergency appointments during the pandemic. The level of concern about the financial impact of the stay-at-home orders and the COVID-19 pandemic was significantly greater for specialists and MScs than for PhDs.

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We surveyed orthodontists in Brazil during the coronavirus disease 2019 pandemic.

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Most frequent urgencies were breakages of brackets, archwires, molar tubes, or bands.

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Stainless steel fixed appliances were the type most related to unscheduled appointments.

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Most patients contacted the orthodontist using the professional WhatsApp messenger.

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Orthodontic specialists and MScs were more concerned than PhDs about financial impacts.

Influence of enamel sealing with a light-cured filled sealant before bracket bonding on the bond failure rate during fixed orthodontic therapy

PURPOSE

Fluoride-containing adhesives for enamel sealing are commonly used for the prevention of white spot lesions during fixed orthodontic treatment. Thus, we examined whether enamel sealing with L.E.D. ProSeal® (Reliance Orthodontic Products Inc., Itasca, IL, USA) before bracket bonding increases the rate of bond failure during orthodontic treatment.

METHODS

In 20 adolescents (11-16 years, 10 male/10 female) at the start of fixed therapy, self-ligating SmartClip™SL3 metal brackets (3M Unitek, Monovia, CA, USA) were bonded to cleaned and conditioned (40% H₃PO₄, 30 s) buccal enamel surfaces of all permanent teeth except molars using Transbond™ XT (3M Unitek). In a split-mouth design, either L.E.D. ProSeal® (1st/3rd quadrant) or Clinpro™ XT Varnish (2nd/4th quadrant; 3M Unitek) was applied to enamel surfaces before (ProSeal®) or after (Clinpro™ XT Varnish) bracket bonding (200 teeth each; light curing: 20 s, Ortholux™ Luminous, 3M Unitek). Cumulative bond failure as total number of teeth with bracket detachment since start of therapy was documented every 3 months for a total of 12 months.

RESULTS

Cumulative bond failure was higher for enamel sealing before bonding from 6 months onward reaching significance at 12 months (34/200) compared to sealing after bonding (24/200): p = 0.038; Cramér's V = 0.488; odds ratio (OR) = 1.5; relative risk (RR) = 1.4. The higher loss rate was limited to the lower arch, but evident within 3 months reaching significance at 9 and 12 months (p = 0.019/0.011, V = 0.636/0.630; OR = 1.7/1.75, RR = 1.5/1.6). In general, cumulative bond failure at 12 months was higher in the lower arch, but this was only significant for teeth sealed before bonding (p = 0.001, V = 0.303, OR = 3.4, RR = 2.8).

CONCLUSIONS

Enamel sealing with L.E.D. ProSeal® should be performed after bracket bonding to prevent increased bond failure and bracket loss in the lower dental arch.

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.

Six-month bracket failure rate with a flowable composite: A split-mouth randomized controlled trial

INTRODUCTION:

The use of flowable composites as an orthodontic bonding adhesive merits great attention because of their adequate bond strength, ease of clinical handling and reduced number of steps in bonding.

OBJECTIVE:

The aim of this Randomized Controlled Trial was to comparatively evaluate over a 6-month period the bond failure rate of a flowable composite (Heliosit Orthodontic, Ivoclar Vivadent AG, Schaan) and a conventional orthodontic bonding adhesive (Transbond XT, 3M Unitek).

METHODS:

53 consecutive patients (23 males and 30 females) who fulfilled the inclusion and exclusion criteria were included in the study. A total of 891 brackets were analyzed, where 444 brackets were bonded using Heliosit Orthodontic and 447 brackets were bonded using Transbond XT. The survival rates of brackets were estimated with the Kaplan-Meier analysis. Bracket survival distributions for bonding adhesives, tooth location and dental arch were compared with the log-rank test.

RESULTS:

The failure rates of the Transbond XT and the Heliosit Orthodontic groups were 8.1% and 6% respectively. No significant differences in the survival rates were observed between them (p= 0.242). There was no statistically significant difference in the bond failure rates when the clinical performance of the maxillary versus the mandibular arches and the anterior versus the posterior segments were compared.

CONCLUSIONS:

Both systems had clinically acceptable bond failure rates and are adequate for orthodontic bonding needs.

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.

Comparing orthodontic bond failures of light-cured composite resin with chemical-cured composite resin: A 12-month clinical trial

INTRODUCTION

In this clinical trial, we evaluated and compared bond failure rates of light-cured composite resin vs chemical-cured composite resin for 12 months.

METHODS

Twenty-two subjects (356 stainless steel brackets) were included in this study, and a split-mouth design was used to randomly allocate diagonally opposite quadrants to either chemical-cured (178 brackets) or light-cured (178 brackets) composite resin; the brackets came from the same manufacturer. The survival and failure rates of the brackets were evaluated by the mode of polymerization. The overall bracket survival rates were estimated using the Kaplan-Meier product limit estimate.

RESULTS

There were no significant differences in the bond failure rates between the chemical-cured and the light-cured composites (P = 0.52). Bond failures were greater in posterior teeth (6.7%) than in anterior teeth (1.2%). The highest failure rate was observed in the second premolars (7.7%).

CONCLUSIONS

The overall failure rate of brackets with the 2 bonding systems was 2.8%, which is acceptable for clinical use. The polymerization mode did not influence the bracket survival rate significantly.

Comparative study on direct and indirect bracket bonding techniques regarding time length and bracket detachment

OBJECTIVE

The aim of this study was to assess the time spent for direct (DBB - direct bracket bonding) and indirect (IBB - indirect bracket bonding) bracket bonding techniques. The time length of laboratorial (IBB) and clinical steps (DBB and IBB) as well as the prevalence of loose bracket after a 24-week follow-up were evaluated.

METHODS

Seventeen patients (7 men and 10 women) with a mean age of 21 years, requiring orthodontic treatment were selected for this study. A total of 304 brackets was used (151 DBB and 153 IBB). The same bracket type and bonding material were used in both groups. Data were submitted to statistical analysis by Wilcoxon non-parametric test at 5% level of significance.

RESULTS

Considering the total time length, the IBB technique was more time-consuming than the DBB (p < 0.001). However, considering only the clinical phase, the IBB took less time than the DBB (p < 0.001). There was no significant difference (p = 0.910) for the time spent during laboratorial positioning of the brackets and clinical session for IBB in comparison to the clinical procedure for DBB. Additionally, no difference was found as for the prevalence of loose bracket between both groups.

CONCLUSIONS

The IBB can be suggested as a valid clinical procedure since the clinical session was faster and the total time spent for laboratorial positioning of the brackets and clinical procedure was similar to that of DBB. In addition, both approaches resulted in similar frequency of loose brackets.

Do we need primer for orthodontic bonding? A randomized controlled trial

OBJECTIVE

To evaluate the clinical performance of APC™II Victory Series™ (3M Unitek) brackets in direct orthodontic bonding with and without the use of primer.

DESIGN

A single-operator, two-centre prospective, non-inferiority randomized controlled clinical trial.

SETTING

The Orthodontic departments at the Leeds Dental Institute and St Luke's Hospital, Bradford, UK.

ETHICAL APPROVAL

Ethical approval was granted by Leeds (East) Research Ethics Committee on 18th of December 2009 (Reference 09/H1306/102).

PROTOCOL

The protocol was not published prior to trial commencement.

SUBJECTS AND METHODS

Ninety-two patients requiring orthodontic treatment with fixed appliances were randomly allocated to the control (bonded with primer) or test groups (bonded without primer). Patients were randomly allocated to either the control or experimental group. This was performed by preparing opaque numbered sealed envelopes in advance using a random numbers table generated by a computer by an independent third party . Once the envelopes were opened, blinding of the operator and the patient was no longer possible due to the nature of the intervention. Patients were approached for inclusion in the trial if they qualified for NHS orthodontic treatment requiring fixed appliances and had no previous orthodontic treatment.

MAIN OUTCOME MEASURES

Number of bracket failures, time to bond-up appliances, and the adhesive remnant index (ARI) when bracket failure occurred, over a 12-month period

RESULTS

Failure rate with primer was 11.1 per cent and without primer was 15.8 per cent. Bonding without primer was shown statistically to be non-inferior to bonding with primer odds ratio 0.95-2.25 (P = 0.08). Mean difference in bond-up time per bracket was 0.068 minutes (4 seconds), which was not statistically significant (P = 0.402). There was a statistically significant difference in the Adhesive Remnant Index - ARI 0 with primer 49.4 per cent, no primer 76.5 per cent, (P < 0.0001).

LIMITATIONS

As the study was only performed by one operator, the results can therefore only be truly be applied to their practice. Also this study was powered to ascertain if there was no difference between the 2 groups up to 5%, however orthodontists may consider a change in the bracket failure rate of 2% to be clinically significant.

CONCLUSION

When bonding with APC™II Victory Series™ brackets without primer was shown statistically to be non-inferior to bonding with primer (P =0.08). There was no significant difference in bond-up times. Bond failure was more likely to happen at the composite-enamel interface when bonded without a primer.

CONFLICT OF INTEREST

No conflict of interest for all authors.

FUNDING

No funding sources were used.

REGISTRATION

Study was not registered on external databases.

Survival analysis of brackets and tubes: A twelve-month assessment

OBJECTIVE

To compare the clinical performance of brackets bonded to anterior and posterior teeth, including second molars.

MATERIALS AND METHODS

One operator, using the straight-wire technique, bonded metallic brackets to the teeth of 127 consecutive patients. All patients were observed for 12 months during their regular orthodontic appointments. Bracket failures were recorded and summarized for statistical analysis. The Cox proportional hazards regression analysis was performed to evaluate bracket failure rates.

RESULTS

Statistically significant differences in survival rates were observed between molar tubes and anterior brackets (P < .05). Twelve-month failure rates of incisor, canine, premolar, and molar brackets were 3.6, 1.6, 4.8, and 11.6%, respectively. The first and second molar did not show significant difference in bond failure. Young patients (age <18 years) showed a higher failure rate than old patients (≥18 years).

CONCLUSIONS

Brackets directly bonded to the buccal surfaces of molars failed significantly more often than those directly bonded to anterior teeth or premolars, but showed acceptable failure rate especially in adult patients. Bonding on second molars seems to be as reliable as bonding on the first molars.

Shear bond strength of rebonded brackets after removal of adhesives with Er,Cr:YSGG laser

This study was conducted to examine the bond strength of rebonded orthodontic brackets after adhesive residuals on the surface of the bracket bases were removed by Er,Cr:YSGG lasers. Seventy-six brackets bonded to premolars with a self-etching primer adhesive system were equally divided into four groups after the first debonding with the bracket bases (Group 1) untreated, and treated by (Group 2) Er,Cr:YSGG laser, (Group 3) sandblaster, and (Group 4) Er,Cr:YSGG laser/sandblaster. The treated brackets were rebonded to the new premolars in the same manner as the first-stage experiment. The shear bond strengths were measured, with the bonding/debonding procedures repeated once after the first debonding, and the bracket/adhesive failure modes were evaluated after each debonding. The treated bracket base surfaces were observed under a scanning electron microscopy (SEM). The mean rebond strengths were significantly lower in group 1 than in other groups, and there were no significant differences between the other groups. The mean initial bond strength was significantly higher than the mean rebond strength in group 1 but there was no significant difference between the two in the other three groups. Failures at the bracket-adhesive interface occurred frequently at second debonding in group 1. Under the SEM, residual adhesive was removed from the bracket bases by Er,Cr:YSGG laser, while adhesive remnant was seen underneath the meshwork of the bracket bases and microroughness appeared on the meshwork after sandblasting. Er,Cr:YSGG laser certainly could serve the purpose of promoting the use of recycled orthodontic brackets.

In vitro evaluation of an alternative method to bond molar tubes

Despite the advances in bonding materials, many clinicians today still prefer to place bands on molar teeth. Molar bonding procedures need improvement to be widely accepted clinically.

Effect of saliva contamination on bracket failure with a self-etching primer: a prospective controlled clinical trial

INTRODUCTION

The aim of this study was to evaluate in vivo the effect of saliva contamination at different stages of the bonding procedure on the bond failure rate and the adhesive remaining on teeth after debonding brackets bonded with a hydrophilic self-etching primer (Transbond Plus self-etching primer [TSEP], 3M Unitek, Monrovia, Calif).

METHODS

This was a prospective controlled clinical trial. The sample consisted of 46 patients with similar treatment plans and mechanotherapies. Stainless steel brackets (n = 531) were bonded with TSEP. The patients were divided into 2 groups: contamination with saliva before TSEP application and contamination with saliva after TSEP application. In both groups, saliva was applied in a split-mouth design. Diagonally opposite quadrants were allocated to either the contaminated group (contamination before [153 teeth] or after [115 teeth] TSEP application) or to the uncontaminated control group (263 teeth). Recording of failed brackets involved only first-time failures, and the observation period was a minimum of 6 months.

RESULTS

The chi-squared test showed no significant differences (P = 0.11) in bracket failures between the groups. Kaplan-Meier survival analysis detected no significant differences in the survival rates between the 3 groups (P = 0.51). Most bond failures occurred during the first 3 months. In all 3 groups, the adhesive remaining on teeth after debonding tended to be less than half.

CONCLUSIONS

These findings suggest that saliva contamination before or after application of self-etching primer does not increase the clinical risk of bond failure.

Bond failure of gingivally offset mandibular premolar brackets: a randomized controlled clinical trial

INTRODUCTION

The purpose of this randomized controlled clinical trial was to examine the clinical bond failure rate of gingivally offset mandibular premolar brackets and compare it with that of standard mandibular premolar brackets.

METHODS

Eighty-three patients were enrolled in this trial. A total of 240 brackets--120 standard and 120 offset--were bonded in a split-mouth design.

RESULTS

Ten standard brackets and 1 offset bracket debonded during the trial period. Survival times were analyzed by using the Kaplan-Meier nonparametric test, and comparisons between bracket types were made with the Mantel-Haenszel log rank test. These tests showed that the failure rate between the bracket types was statistically significant (P <0.0058).

CONCLUSIONS

Gingivally offset mandibular premolar brackets have a lower bond failure rate than standard mandibular premolar brackets.

Influence of different tooth types on the bond strength of two orthodontic adhesive systems

The aim of this investigation was to evaluate the effects of different tooth types on the shear bond strength (SBS) of two orthodontic resin adhesive systems in vitro.

Two hundred extracted sound human teeth were used in the study. Ten teeth of each tooth type were the mounted in acrylic resin leaving the buccal surface of the crowns parallel to the base of the moulds. In each experimental group, the adhesives (Transbond XT™ and Light Bond™) were applied to the etched enamel surfaces. The orthodontic composite resins were then applied to the surface in cylindrical-shaped plastic matrices. For SBS testing, a force transducer (Ultradent™) was applied at a crosshead speed of 1 mm/minute at the interface between the tooth and composite until failure occurred. Data were analysed using two-way analysis of variance (ANOVA), Kruskal–Wallis one-way ANOVA, a Bonferroni adjusted Mann–Whitney U-test, and an independent t-test.

Generally, it was found that tooth type had a significant effect on SBS (P < 0.05) with Light Bond™ showing a higher SBS than Transbond XT™ (P < 0.05). The highest bond strengths were observed for the upper central incisor and lower molars with Light Bond™ (P < 0.05) and the lowest mean bond strengths for the upper molars and lower canine with Transbond XT™ (P <0.05). The results demonstrated that enamel SBS was significantly altered by both tooth type and adhesive system. Thus, the findings of this study confirm that enamel bond strength is not uniform for all teeth. These results may also explain the variability in the enamel-bonding efficacy of adhesives.

Bond Failure with a No-Mix Adhesive System

Objective: To determine the bond failure pattern and time to first bond failure at an orthodontic clinic.

Materials and Methods: The study included 63 subjects meeting the study criteria. A total of 1074 brackets (Roth prescription 0.022 slot) were bonded to incisors, canines, and premolars using a no-mix adhesive (Unite, 3M Unitek). The survival and failure rates of the brackets were evaluated by tooth position in the dental arch, sagittal occlusal relationship, and gender of the patients. Overall bracket survival rates were estimated using the Kaplan-Meier test.

Results: The total percentage of bond failure was 17.87%. The mean survival time for the sample was 235 days (SE = 32.27 days). Significantly higher failure rates were observed for posterior than anterior teeth (P &lt; .05) and in the Class II division 2 malocclusion group than other malocclusion groups (P &lt; .05). No difference was observed between dental arches or genders. However, in terms of survival time, the difference was marginally significant for gender (P = .051)

Conclusion: For 1074 brackets bonded with a no-mix adhesive system in 63 patients, the mean time until first bracket failure was 235 days. The overall failure rate of brackets was 17.87%.

Does atropine sulphate improve orthodontic bond survival? A randomized clinical trial

INTRODUCTION

The antisialagogue atropine sulphate has been used for many years as an adjunct to orthodontic bonding to reduce moisture contamination. The aims of this study were to investigate the effect of atropine sulphate premedication on orthodontic bond failures and to evaluate the attitudes of patients and parents toward its use in orthodontics.

METHODS

After ethics committee approval, 51 patients (mean age, 14 years 7 months) were enrolled in this clinical trial. They were randomized to receive 2 interventions, atropine sulphate premedication (600 microg) or no premedication (control) with a Battenburg design (split-mouth). Overall, 852 brackets and 362 molar tubes were bonded. Bond failure data were collected over a 12-month period and analyzed with Kaplan-Meier survival probabilities and the log rank and Wilcoxon tests. Patient-centered outcome measures included a questionnaire relating to treatment with antisialagogues.

RESULTS

The results showed no statistically significant difference in the bond survival rates between the 2 interventions--antisialagogue premedication or no premedication (P >.05). From the questionnaire, 94.1% of the subjects said they took the atropine sulphate before the bond appointment. Approximately 76% of them thought that taking medication before placement of orthodontic appliances was an acceptable part of treatment.

CONCLUSIONS

Although the use of a premedication to induce hypo-salivation before orthodontic bonding appears to be an acceptable procedure to most patients and their parents, we did not find a statistically significant effect on the observed bond failure rates. There is no evidence to support the routine use of atropine sulphate before orthodontic bonding.