An in vivo comparison between a visible light-cured bonding system and a chemically cured bonding system

Clinical bracket failure rates between different bonding techniques: a systematic review and meta-analysis

BACKGROUND

Bracket failure increases the treatment time of orthodontic therapy and burdens patients with unnecessary costs, increased chair time, and possible new appointments.

OBJECTIVE

To compare the bond failures of different orthodontic materials based on the results of available clinical studies.

SEARCH METHODS

A systematic search of clinical trials was performed in the Cochrane, Embase, and Pubmed databases with no limitations. The list of investigated techniques contained conventional acid-etch primer (CM-AEP), self-etch primer (SEP), self-cure resin (SCR), and simple or resin-modified glass ionomer (RM-GIC) materials and procedures.

SELECTION CRITERIA

Clinical studies reporting the failure rate of bonded brackets after using direct adhesive techniques on buccal sites of healthy teeth were included.

DATA COLLECTION AND ANALYSIS

Bracket failure rates from eligible studies were extracted by two authors independently. Risk ratios (RRs) were pooled using the random-effects model with DerSimonian-Laird estimation.

RESULTS

Thirty-four publications, involving 1221 patients, were included. Our meta-analysis revealed no significant difference in the risk of bracket failures between SEP and CM-AEP. After 6, 12, and 18 months of bonding, the values of RR were 1.04 [95% confidence interval (CI), 0.67-1.61], 1.37 (95% CI, 0.98-1.92), and 0.93 (95% CI, 0.72-1.20), respectively. At 18 months, bracket failure was 4.9 and 5.2% for SEP and CM-AEP, respectively. Heterogeneity was good or moderate (I2 < 42.2%). The results of RM-GIC at 12 months indicated a 57% lower risk of bracket failure using SCR as compared with RM-GIC (RR: 0.38; 95% CI, 0.24-0.61). At 18 months, bracket failures for SCR and RM-GIC were 15.8 and 36.6%, respectively (RR: 0.44; 95% CI, 0.37-0.52, I2 = 78.9%), demonstrating three to six times higher failure rate than in the case of etching primer applications.

LIMITATIONS

A major limitation of the present work is that the included clinical trials, with no exceptions, showed variable levels of risk of bias. Another possible problem affecting the outcome is the difference between the clustering effects of the split mouth and the parallel group bracket allocation methods.

CONCLUSIONS AND IMPLICATIONS

The results revealed no significant difference between SEP and CM-AEP up to 18 months after application. RM-GIC had much worse failure rates than acid-etching methods; additionally, the superiority of SCR over RM-GIC was evident, indicating strong clinical relevance.

REGISTRATION

Prospero with CRD42020163362.

A new method for successful indirect bonding in relation to bond strength

The aim of the work was to develop a new transfer method for indirect bonding of brackets to improve the bond strength by applying a uniform contact pressure over the entire dental arch. This has a great potential to reduce the bracket loss rate during clinical treatment. A suitable shape memory polymer (SMP) was selected and prepared in the chemistry laboratory. This SMP applies a force to the brackets during bonding and thus increases the bond strength by applying uniform contact pressure. Various transfer trays were equipped with SMP platelets and the transfer of brackets from the plaster model to the real human tooth model was performed in vitro. The transfer accuracy and bond strength of the bonded brackets were investigated by 3D-overlay and shear tests, respectively. The transfer accuracy was technique sensitive and showed higher accuracy for the trays with SMPs and self-curing silicones than for the vacuum formed trays with SMPs. The bond strength of the indirectly bonded brackets with SMPs was on average 1-2 MPa higher than the bond strength of the brackets indirectly bonded with a conventional two-layer vacuum formed tray without SMPs. Thus, transfer trays with SMPs can provide a significant improvement in bond strength during indirect bonding after appropriate adjustment.

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.

Evaluation of sandblasting with acid etching versus acid etching alone in the preparation of enamel for rebonding orthodontic brackets: An in vitro study and a randomized controlled trial

BACKGROUND

No clinical studies have evaluated shear bond strength and the clinical failure rates of the rebonded metallic brackets following different enamel-reconditioning methods. The objective of the study was to compare the in vivo clinical failure rate and the in vitro rebond strength of bonded brackets following two enamel surface preparation methods.

METHODS

For the in vitro study, 45 extracted human premolars were etched; brackets were bonded using light-cured composite resin. Forty-five premolars were divided into three groups (15 in each group): the initial bonding group (IB group), the rebonding group in which enamel was reconditioned using sandblasting before acid etching (SBE group), and the rebonding group in which enamel was reconditioned using acid etching only (E group). For the in vivo study, 80 premolars in 20 patients (13-18 years old) were rebonded using the same procedures in the SBE group and E group. The two methods were used in all patients using a split-mouth design. The number of failing brackets was quantified over 6 months. Differences were statistically analyzed by one-way analysis of variance, followed by post hoc tests.

RESULTS

The mean shear bond strength for the IB, SBE, and E groups was 19.38, 22.37, and 17.31 MPa, respectively. A significant difference was observed in the bond strength of the three evaluated groups (P < 0.001). The differences in the bond strength were significant between the IB group and the SBE group, as well as between the SBE group and the E group. The clinical failure rate for bonded brackets was 10% in the SBE group, and 25% in the E group and this difference was statistically significant (P < 0.001).

CONCLUSIONS

Reconditioning of enamel surfaces using both intraoral air abrasion and etching in the rebonding process led to higher rebond strength than using acid etching alone and even higher than the initial brackets bonding. This trial was retrospectively registered at ClinicalTrials.gov (ID: NCT04606043).

Adhesives for fixed orthodontic brackets

BACKGROUND

Bonding of orthodontic brackets to teeth is important to enable effective and efficient treatment with fixed appliances. The problem is bracket failure during treatment which increases operator chairside time and lengthens treatment time. A prolonged treatment is likely to increase the oral health risks of orthodontic treatment with fixed appliances one of which is irreversible enamel decalcification. This is an update of the Cochrane Review first published in 2003. A new full search was conducted on 26 September 2017 but no new studies were identified. We have only updated the search methods section in this new version. The conclusions of this Cochrane Review remain the same.

OBJECTIVES

To evaluate the effects of different orthodontic adhesives for bonding.

SEARCH METHODS

Cochrane Oral Health's Information Specialist searched the following databases: Cochrane Oral Health's Trials Register (to 26 September 2017), the Cochrane Central Register of Controlled Trials (CENTRAL; 2017, Issue 8) in the Cochrane Library (searched 26 September 2017), MEDLINE Ovid (1946 to 26 September 2017), and Embase Ovid (1980 to 26 September 2017). The US National Institutes of Health Ongoing Trials Register (ClinicalTrials.gov) and the World Health Organization International Clinical Trials Registry Platform were searched for ongoing trials. No restrictions were placed on the language or date of publication when searching the electronic databases.

SELECTION CRITERIA

Trials were selected if they met the following criteria: randomised controlled trials (RCTs) and controlled clinical trials (CCTs) comparing two different adhesive groups. Participants were patients with fixed orthodontic appliances. The interventions were adhesives that bonded stainless steel brackets to all teeth except the molars. The primary outcome was debond or bracket failure.

DATA COLLECTION AND ANALYSIS

Data were recorded on decalcification as a secondary outcome, if present. Information regarding methods, participants, interventions, outcome measures and results were extracted in duplicate by pairs of review authors. Since the data were not presented in a form that was amenable to meta-analysis, the results of the review are presented in narrative form only.

MAIN RESULTS

Three trials satisfied the inclusion criteria. A chemical cured composite was compared with a light cured composite (one trial), a conventional glass ionomer cement (one trial) and a polyacid-modified resin composite (compomer) (one trial). The quality of the trial reports was generally poor.

AUTHORS' CONCLUSIONS

There is no clear evidence on which to make a clinical decision of the type of orthodontic adhesive to use.

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.

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

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.

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.

How and why of orthodontic bond failures: An in vivo study

Introduction:

The bonding of orthodontic brackets and their failure rates by both direct and in-direct procedures are well-documented in orthodontic literature. Over the years different adhesive materials and various indirect bonding transfer procedures have been compared and evaluated for bond failure rates. The aim of our study is to highlight the use of a simple, inexpensive and ease of manipulation of a single thermo-plastic transfer tray and the use the of a single light cure adhesive to evaluate the bond failure rates in clinical situations.

Materials and Methods:

A total of 30 patients were randomly divided into two groups (Group A and Group B). A split-mouth study design was used, for, both the groups so that they were distributed equally with-out bias. After initial prophylaxis, both the procedures were done as per manufactures instructions. All patients were initially motivated and reviewed for bond failures rates for 6 months.

Results:

Bond failure rates were assessed for over-all direct and indirect procedures, anterior and posterior arches, and for individual tooth. Z-test was used for statistically analyzing, the normal distribution of the sample in a spilt mouth study. The results of the two groups were compared and P value was calculated using Z-proportion test to assess the significance of the bond failure.

Conclusion:

Over-all bond failure was more for direct bonding. Anterior bracket failure was more in-direct bonding than indirect procedure, which showed more posterior bracket failures. In individual tooth bond failure, mandibular incisor, and premolar brackets showed more failure, followed by maxillary premolars and canines.

Comparative study of enamel adhesion between RelyX™ Unicem® (3M), a self-adhesive bonding agent, and the combination of MIP® (3M), a hydrophilic adhesive, and Transbond Supreme Low Viscosity® (3M), a traditional hydrophobic adhesive

Although the bond strength of self-adhesive bonding agents is inferior to that of other families of adhesives, it is still adequate for orthodontic purposes provided prior enamel etching is performed.

AIM

To determine the efficacy of RelyX™ Unicem(®) (3M) self-adhesive cement both in vitro and in vivo and to compare it with the combination of MIP(®) (3M), a moisture-insensitive primer, with a traditional hydrophobic adhesive, Transbond Supreme Low Viscosity(®) (3M).

IN VITRO

Comparison of bonding results on 23 trial dentures using RelyX™ Unicem(®) (3M) with bonding results on 29 trial dentures using a combination of MIP(®) and Transbond Supreme Low Viscosity(®) (3M), by means of a multipurpose Instron(®) 4444 testing machine.

RESULTS

the breaking force of MIP(®)/Transbond Supreme Low Viscosity(®) (3M) (mean: 144±37.5 Newtons) was significantly higher than that of RelyX™ Unicem(®) (3M) (mean=110±26 Newtons) (P=0.001).

IN VIVO

A 12-month prospective, randomized, monocentric, single-blind clinical study in order to investigate the failure rate of orthodontic attachments according to the type of adhesive used, and the precise site of the debonding. Bracket bonding was performed on 16 patients with randomized allocation of the two adhesives to each of the semi-arches.

RESULTS

The failure rates were: 15.3% for the MIP(®)/Transbond Supreme Low Viscosity(®) (3M) combination and 8.2% for the RelyX™ Unicem(®) (3M), with a significant difference (P=0.039). The more posterior the bonded teeth, the greater the superiority of RelyX™ Unicem(®) (3M). The in vivo results did not concord with those obtained in vitro. RelyX™ Unicem(®) (3M) exhibited lower adhesion values in vitro and yet it presented a debonding rate almost half that of the MIP(®)/Transbond Supreme Low Viscosity(®) (3M). The viscosity of RelyX™ Unicem(®) (3M) and its moisture tolerance would appear to account for these results.

CONCLUSION

With prior etching, RelyX™ Unicem(®) (3M), a self-adhesive, self-etching bonding agent is compatible with use in the orthodontic indirect bonding technique. The MIP(®)/Transbond Supreme Low Viscosity(®) (3M) combination, though very effective, still remains sensitive and requires special care during usage.

Effect of short curing times with a high-intensity light-emitting diode or high-power halogen on shear bond strength of metal brackets before and after thermocycling

OBJECTIVE

To test the hypothesis that short curing times using a high-intensity light-emitting diode (LED) or high-power halogen are not associated with compromised shear bond strength (SBS) of metal brackets before and after thermocycling.

MATERIALS AND METHODS

Two hundred forty extracted human premolar teeth were divided into six groups of 40 each. Metal brackets were bonded using a light-cured composite (Transbond XT). In group 1 a conventional halogen light (Hilux) was used for 40 seconds. In groups 2, 3, and 4 a high-power halogen light (Swiss Master) was used for 2, 3, and 6 seconds, respectively. In groups 5 and 6 a high-intensity LED (Bluephase) was used for 10 and 20 seconds, respectively. After bonding, half of the specimens in each group were thermocycled, and all specimens were tested for SBS. After debonding, the bracket bases and the enamel surfaces were scored according to the Adhesive Remnant Index.

RESULTS

Two-way analysis of variance detected significant differences in SBS values with respect to curing method (type of light-curing unit and curing time) (P  =  .0001) and thermocycling (P  =  .01). Tukey post hoc analysis showed that with or without thermocycling the mean SBS values of groups 1, 4, 5, and 6 were not significantly different, whereas group 2 showed the lowest SBS values. The predominant failure site for groups 2 and 3 was between the bracket and the adhesive and for groups 4, 5, 6 it was at the tooth/adhesive interface.

CONCLUSION

Curing time can be reduced to 6 seconds with high-power halogen light and to 10 seconds with high-intensity LED without compromising in vitro SBS of metal brackets.

Effect of flexural strength of orthodontic resin cement on bond strength of metal brackets to enamel surfaces

Three types of experimental resin cements with different curing systems, dual, light, and chemical, were designed. The relationship between the flexural strengths of the three experimental and five commercial (Beauty Ortho Bond, Transbond™ XT, Light Cure Bond, Kurasper® F, and Super Bond) orthodontic resin cements on the tensile bond strength (TBS) and shear bond strength (SBS) of metal brackets to enamel was determined. Seven specimen bars of each resin were prepared for measuring the flexural strengths of the resins. Bonded specimens of each resin were prepared, seven for measuring TBS and seven SBS for after bonding of a metal bracket to a maxillary central human labial anterior tooth using experimental and commercial resin cements. The results were analysed by one-way analysis of variance and Scheffé's multiple comparison tests. The level of statistical significance was set at 0.05. Increases in the flexural strength of the resin cements were related to increases in the TBS and SBS of the metal bracket. While the light-curing cements exhibited a strong linear correlation between flexural strengths and TBS or SBS, the dual- and chemical-curing cements exhibited a different flexural strength effect on both TBS and SBS. This was a result of the adhesive layer under the metal bracket, which could be chemically cured, in contrast to the light-curing cement. To control setting time and to obtain higher initial TBS and SBS by polymerizing the resin cement under the bracket, a dual-curing system, that combines both light- and chemical-curing systems, is essential.

A new acrylic-based fluoride-releasing cement as a potential orthodontic bonding agent

OBJECTIVE

To develop a fluoride-releasing, acrylic-based 'easy on, easy off' bracket cement as a potential orthodontic bonding agent.

MATERIAL AND METHODS

Three experimental cements were prepared in powder/liquid forms by mixing different ratios of methylmethacrylate (MMA) and 2-hydroxyethyl methacrylate (HEMA) to form the liquid (L) and sodium fluoride (NaF) and polymethylmethacrylate (PMMA) to form the powder (P). The resultant materials were tested for setting characteristics, fluoride release, hardness, strength, shear bond strength (SBS) and adhesive remnant index in comparison with resin composite and glass ionomer, which were used as control materials. The data were analyzed using ANOVA and the Kruskal-Wallis and Mann-Whitney tests.

RESULTS

The experimental groups had satisfactory setting characteristics. Fluoride release of the group containing P (10% NaF, 90% PMMA) and L (60% MMA and 40% HEMA) was similar to that of glass ionomer. When experimental materials were stored in water for 7 days, their hardness was reduced and stabilized at a value lower than those for composite and PMMA. Strength was only slightly affected by water storage. The SBSs of the experimental groups were considered clinically acceptable at both 30 min and 1 month. The group containing P (10% NaF, 90% PMMA) and L (90% MMA and 10% HEMA) had a higher mean SBS than the other two experimental groups. At 1 month, there were significantly less adhesive remnants observed on the surface of enamel after debonding for the experimental groups compared with the composite.

CONCLUSION

The new cement could potentially be useful as an orthodontic bonding agent.

[Comparison of 1-stage orthodontic bonding systems and 2-stage bonding systems: a review of the literature and the results of a randomized clinical trial]

OBJECTIVE

The main objectives of this study are to present a literature review of self-etching primer's (SEP's) and present the outcomes of a prospective clinical trial 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 a 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

Orthodontic Department Countess of Chester Hospital, 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 (relative risk 0.47%; 95% confidence interval 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. The literature on SEP's supports the findings of this study.

LED vs Halogen Light-Curing of Adhesive-Precoated Brackets

Objective: To test the hypothesis that bonding with a blue light-emitting diode (LED) curing unit produces no more failures in adhesive-precoated (APC) orthodontic brackets than bonding carried out by a conventional halogen lamp.

Materials and Methods: Sixty-five patients were selected for this randomized clinical trial, in which a total of 1152 stainless steel APC brackets were employed. In order to carry out a valid comparison of the bracket failure rate following use of each type of curing unit, each patient's mouth was divided into four quadrants. In 34 of the randomly selected patients, designated group A, the APC brackets of the right maxillary and left mandibular quadrants were bonded using a halogen light, while the remaining quadrants were treated with an LED curing unit. In the other 31 patients, designated group B, halogen light was used to cure the left maxillary and right mandibular quadrants, whereas the APC brackets in the remaining quadrants were bonded using an LED dental curing light. The bonding date, the type of light used for curing, and the date of any bracket failures over a mean period of 8.9 months were recorded for each bracket and, subsequently, the chi-square test, the Yates-corrected chi-square test, the Fisher exact test, Kaplan-Meier survival estimates, and the log-rank test were employed in statistical analyses of the results.

Results: No statistically significant difference in bond failure rate was found between APC brackets bonded with the halogen light-curing unit and those cured with LED light. However, significantly fewer bonding failures were noted in the maxillary arch (1.67%) than in the mandibular arch (4.35%) after each light-curing technique.

Conclusions: The hypothesis cannot be rejected since use of an LED curing unit produces similar APC bracket failure rates to use of conventional halogen light, with the advantage of a far shorter curing time (10 seconds).

Clinical Evaluation of Bracket Bonding Using Two Different Polymerization Sources

Objective: To comparatively assess clinical failure rate of brackets cured with two different photopolymerization sources after nine months of orthodontic treatment.

Materials and Methods: The sample of this study comprised 30 patients who received comprehensive orthodontic treatment by means of fixed appliances. Using the same adhesive, 600 stainless steel brackets were directly bonded and light cured for 10 seconds with the light-emitting diode (LED) lamp or for 20 seconds with the conventional halogen lamp. A split-mouth design randomly alternated from patient to patient was applied. Failure rates were recorded for nine months and analyzed with Pearson χ2 test, and log-rank test at α = .05 level of significance.

Results: The overall failure rate recorded with the halogen unit (3.33%) was not significantly different from the failure rate for the LED lamp (5.00%). Significantly more failures were found in boys compared with girls, in the mandibular dental arch compared with the maxillary arch, and in posterior segments compared with anterior segments. However, no significant difference was found between the right and left segments.

Conclusion: Both light-curing units showed sufficiently low bond failure rates. LED curing units are an advantageous alternative to conventional halogen sources in orthodontics because they enable a reduced chair-time bonding procedure without significantly affecting bond failure rate.

A randomised clinical trial to investigate bond failure rates using a self-etching primer

This clinical trial evaluated, over a 12-month period, the performance of brackets bonded to teeth etched and primed with Transbond Plus Self-Etching Primer (SEP) when compared with a conventional separate two-step etch and primer system. Thirty-nine randomly selected patients requiring fixed appliance therapy were entered into the study. Random allocation of each etching system, along with a 'split-mouth cross-quadrant' design was used. A total of 661 brackets were placed by two operators. The failure and survival rates of the brackets were determined for age and gender of the patients, each etching system, operator, mode of failure, tooth position in the dental arch, and number of manipulations prior to curing the adhesive. Statistical analysis showed that SEP had a significantly higher bond failure rate (11.2 per cent) than the conventional etch and primer system (3.9 per cent) at the P = 0.001 level. Cox's proportional hazards regression showed the conventional etch and primer system to have a 60 per cent reduced chance of bracket failure over a 12-month observation period, while males had a 2.4 times increased risk compared with females. The predominant mode of failure was at the composite enamel interface for the SEP, while for the conventional etch and primer system, it was within the composite adhesive. No statistically significant differences were found for the failure rate with respect to the age of the patient, operator, tooth location, or the number of manipulations of the bracket. This in vivo study showed that brackets bonded using SEP had an increased clinical bond failure rate compared with the conventional, separate, etch and prime system.

A comparison of tungsten-quartz-halogen, plasma arc and light-emitting diode light sources for the polymerization of an orthodontic adhesive

This study investigated whether there were differences between the debond stress and adhesive remnant index (ARI) of an adhesive cured with three different orthodontic light sources. Sixty sound premolar teeth were divided into three groups of 20. A standard pre-adjusted edgewise premolar bracket (Victory Series) was bonded to each tooth using a light-cured orthodontic adhesive, Transbond X. Group 1 (control) specimens were cured with an Ortholux XT (tungsten-quartz-halogen bulb) light for 20 seconds, group 2 with an Ortho lite (plasma arc) for 6 seconds and group 3 with an Ortholux LED light-emitting diode for 10 seconds. The specimens were debonded 24 hours later using a universal mechanical testing machine, operating at a crosshead speed of 0.5 mm minute(-1). The Weibull modulus and a Logrank test showed no statistically significant differences between the three groups for debond stress. The ARI was assessed at x10 magnification. The ARI scores for group 2 were significantly different (P < 0.01) from those of groups 1 and 3 (between which there was no significant difference). For group 2 there was a greater tendency for failure to occur at the adhesive/tooth interface than for the other two groups. There appears to be no reason why any of the three types of light source cannot be used in orthodontics. Polymerization, as effective as that produced by conventional bulb light sources, was obtained with the short exposure times recommended for the plasma arc or light-emitting diode sources.

Plasma arc versus halogen light-curing of adhesive-precoated orthodontic brackets: A 12-month clinical study of bond failures

The purpose of this randomized clinical trial was to evaluate the performance of adhesive-precoated brackets cured with 2 different light-curing units (conventional halogen light and plasma arc light). Thirty patients treated with fixed appliances were included in the investigation. Each patient's mouth was divided by the split-mouth design into 4 quadrants. In 15 randomly selected patients, the maxillary left and mandibular right quadrants were cured with the halogen light, and the remaining quadrants were cured with the plasma arc light. In the other 15 patients, the quadrants were inverted. A total of 600 adhesive precoated stainless steel brackets were examined: 300 were cured with a conventional halogen light for 20 seconds, and the others were cured with the plasma arc light for 5 seconds. The number, cause, and date of bracket failures were recorded for each light-curing unit over 12 months. Statistical analysis was performed with the Fisher exact test, Kaplan-Meier survival estimates, and the log-rank test. No statistically significant differences in bond failure rates were found between the adhesive-precoated brackets cured with the halogen light and those cured with the plasma arc light; neither were any significant differences in performance found with each light-curing unit between the maxillary and mandibular arches. Plasma arc lights can be considered an advantageous alternative to conventional light curing, because they enable the clinician to reduce the curing time of adhesive-precoated orthodontic brackets without significantly affecting their bond failure rate.

Plasma arc versus halogen light curing of orthodontic brackets: a 12-month clinical study of bond failures

The purpose of this randomized clinical trial was to evaluate the clinical performance of brackets cured with 2 different light-curing units (conventional halogen light and plasma arc light); 83 patients treated with fixed appliances were included in the study. With the "split-mouth" design, each patient's mouth was divided into 4 quadrants. In 42 randomly selected patients, the maxillary left and mandibular right quadrants were cured with the halogen light, and the remaining quadrants were cured with the plasma arc light. In the other 41 patients, the quadrants were inverted. A total of 1434 stainless steel brackets were examined: 717 were cured with a conventional halogen light for 20 seconds; the remaining 717 were cured with the plasma arc light for 5 seconds. The number, cause, and date of bracket failures were recorded for each light-curing unit over 12 months. Statistical analysis was performed with the Fisher exact test, the Kaplan-Meier survival estimates, and the log-rank test. No statistically significant differences were found between the total bond failure rates of the brackets cured with the halogen light and those cured with the plasma arc light. Neither were significant differences found when the clinical performances of the maxillary versus mandibular arches or the anterior versus posterior segments were compared. These findings demonstrate that plasma arc lights are an advantageous alternative to conventional light curing, because they significantly reduce the curing time of orthodontic brackets without affecting the bond failure rate.

Clinical trial comparing plasma arc and conventional halogen curing lights for orthodontic bonding

The purpose of this clinical trial was to evaluate the reliability and time saved with a plasma arc curing unit (Apollo 95E, Dental/Medical Diagnostic Systems, Woodland Hills, Calif) compared with a conventional curing unit (Ortholux XL 3000, 3M Unitek, St Paul, Minn) for direct bracket bonding with resin adhesive. Forty-five patients were involved in the study, and 608 brackets were bonded in a contralateral quadrant pattern. The patients were followed for a mean (+/- standard deviation) period of 11 +/- 3.2 months. Survival analysis was carried out to compare the failure rate for the 2 techniques. The time required for bonding with each technique was also recorded. The mean survival time was 399 days, and there were no significant differences in survival time between the 2 bonding methods. Twelve bonding failures were reported with each technique. The curing time per bracket was significantly reduced with the plasma curing light compared with a conventional curing unit (65 +/- 19 vs 82 +/- 31 seconds). The plasma arc curing light can save chair-time without affecting the bonding failure rate.

In vivo evaluation of two new moisture-resistant orthodontic adhesive systems: a comparative clinical trial

OBJECTIVE

To evaluate and compare the clinical performance of two new moisture-resistant orthodontic adhesive systems: a chemically-cured composite resin (Unite, 3M Unitek, Monrovia, California, USA) in conjunction with a special moisture-resistant primer (Transbond MIP, 3M Unitek, Monrovia, California, USA); and a fluoride-releasing light-cured compomer (Assure, Reliance Orthodontic Products, Inc., Itasca, Illinois, USA).

DESIGN

Randomized controlled clinical trial using the 'split-mouth' technique.

SETTING

Department of Orthodontics, Aristotle University of Thessaloniki.

SUBJECTS (MATERIALS) AND METHODS

Twenty-five consecutively started patients (13 females and 12 males) requiring fixed appliance orthodontic treatment.

INTERVENTIONS

Four-hundred-and-thirty-six stainless steel brackets bonded to all teeth except molars using two different moisture-resistant orthodontic adhesive systems.

MAIN OUTCOME MEASURES

Bond failure rates during a period of 9 months were estimated for each adhesive system and the corresponding bracket survival curves were plotted using the Kaplan- Meier product-limit estimate. Bracket survival distributions with respect to adhesive material, tooth location, patient's gender and operator, were then compared by means of a log-rank test. Bond failure interface was determined using the Adhesive Remnant Index.

RESULTS

Assure recorded a higher bond failure rate (13.8 per cent) than Unite & MIP (7.3 per cent). The corresponding bracket survival curves were found to be significantly different (P < 0.05). Premolars exhibited higher bond failures than incisors and canines (P < 0.001), while half (49.8 per cent) of the total bond failures occurred during the first 2 months of treatment. The predominant mode of failure was within the bonding material.

CONCLUSION

The new moisture-resistant adhesive systems under study were found to be clinically efficient, though Assure exhibited a significantly higher bond failure rate than Unite and Transbond MIP. The higher frequency of adhesive failures observed with Assure might indicate a possible weak point at the adhesive-bracket interface.

Clinical trials in orthodontics I: demographic details of clinical trials published in three orthodontic journals between 1989 and 1998

AIM

To test the hypothesis that there is insufficient evidence available, from clinical trials, to allow evidence-based decisions to be made on the effectiveness of orthodontic treatment.

OBJECTIVES

To identify reports of orthodontic clinical trials and assess their demographic characteristics.

DESIGN

A retrospective, observational study.

SETTING

The American Journal of Orthodontics and Dentofacial Orthopedics, British Journal of Orthodontics, and European Journal Orthodontics.

DATA SOURCE

Clinical trials published between 1989 and 1998.

METHOD

A hand-search was performed to identify all clinical trials. The journal and year of publication, research method, interventions, and sample size of the trials reported were recorded.

RESULTS

One-hundred-and-fifty-five trial reports were identified of which 56 (36.1%) were published from 1989 to 1993 and 99 (69%) from 1994 to 1998. Ninety-nine (69%) reports were published in the AJO-DO, 18 (11.6%) in the BJO and 38 (24.5%) in the EJO. Eighty-five (54.8%) were reports of randomized controlled trials and 70 (45.2%) of controlled clinical trials. The interventions most frequently assessed were bonding materials (21.9%), growth modification treatments (21.3%), and oral hygiene procedures (9.0%). The median sample size was 32 (IQR 19.5, 50).

CONCLUSION

There is sufficient evidence available from clinical trials to warrant doing systematic reviews of orthodontic clinical trials to aid decision-making.

Adhesives for fixed orthodontic brackets

BACKGROUND

Bonding of orthodontic brackets to teeth is important to enable effective and efficient treatment with fixed appliances. The problem is bracket failure during treatment which increases operator chairside time and lengthens treatment time. A prolonged treatment is likely to increase the oral health risks of orthodontic treatment with fixed appliances one of which is irreversible enamel decalcification.

OBJECTIVES

To evaluate the effectiveness of different orthodontic adhesives for bonding.

SEARCH STRATEGY

Electronic databases: the Cochrane Oral Health Group's Trials Register, the Cochrane Central Register of Controlled Trials (CENTRAL), MEDLINE and EMBASE. Date of most recent searches: August 2002 (CENTRAL) (The Cochrane Library Issue 2, 2002).

SELECTION CRITERIA

Trials were selected if they met the following criteria: randomised controlled trials (RCTs) and controlled clinical trials (CCTs) comparing two different adhesive groups. Participants were patients with fixed orthodontic appliances. The interventions were adhesives that bonded stainless steel brackets to all teeth except the molars. The primary outcome was debond or bracket failure.

DATA COLLECTION AND ANALYSIS

Data were recorded on decalcification as a secondary outcome, if present. Information regarding methods, participants, interventions, outcome measures and results were extracted in duplicate by pairs of reviewers (Nicky Mandall (NM) and Rye Mattick (CRM); Declan Millett (DTM) and Joy Hickman (JH2)). Since the data were not presented in a form that was amenable to meta-analysis, the results of the review are presented in narrative form only.

MAIN RESULTS

Three trials satisfied the inclusion criteria. A chemical cured composite was compared with a light cure composite (one trial), a conventional glass ionomer cement (one trial) and a polyacid-modified resin composite (compomer) (one trial). The quality of the trial reports was generally poor.

REVIEWER'S CONCLUSIONS

It is difficult to draw any conclusions from this review, however, suggestions are made for methods of improving future research involving orthodontic adhesives.

Orthodontic adhesives: a systematic review

OBJECTIVES

To evaluate which orthodontic adhesives (a). bond orthodontic brackets to teeth more reliably and (b). are more effective at preventing decalcification.

DATA SOURCES

The search strategy for the literature review was carried out according to the standard Cochrane systematic review methodology. The Cochrane Clinical Trials Register and the Cochrane Oral Health Group Specialized Register were searched for randomized clinical trials and controlled clinical trials. All volumes that had not already been assessed by the Oral Health Group in the European Journal of Orthodontics, American Journal of Orthodontics, Journals of Orthodontics, and Angle Orthodontist were hand-searched. Inclusion and exclusion criteria were applied when considering the studies to be included in this review.

DATA SELECTION

The primary outcome measure was the failure of the orthodontic adhesive. A secondary outcome of decalcification occurring around the orthodontic bracket was also recorded, if data were available.

DATA EXTRACTION

Two randomized clinical trials and one controlled clinical trial were identified that fulfilled all the inclusion and exclusion criteria. The trials compared: (a). light- and chemically-cured composite; (b). chemically-cured composite and conventional glass ionomer cement; and (c). chemically-cured composite and light-cured compomer.

DATA SYNTHESIS

Each paper was quality assessed by two people independently. A qualitative analysis of the trials in the review is presented. The data presentation, for the majority of the trials, precluded the use of suggested Cochrane Health Group statistical analysis.

CONCLUSIONS

It is difficult to draw any conclusions from this review; however, suggestions are made for methods of improving future research involving orthodontic adhesives.

Bond failure of a no-mix adhesive during orthodontic treatment

Bond failure of a no-mix adhesive was evaluated in 320 patients followed longitudinally during orthodontic treatment. Factors evaluated were the patient's gender, the complexity of the appliance, the bond site location, initial crowding, and caries development. The overall bond failure rate was 7.2%. Bond failures were significantly higher in the mandible, with the second premolars showing the highest prevalence (23%) (P <.001). There were significantly higher bond failure rates in boys than in girls (P <.05). There was a significant negative correlation between initial crowding and bond failure. Increased white spot lesions during treatment and complex appliance design were significantly correlated with high bond failure rates.

In vivo evaluation of a moisture-activated orthodontic adhesive: a comparative clinical trial

OBJECTIVES

To evaluate and compare the clinical performance of a water-activated, ethyl-cyanoacrylate adhesive to a conventional composite resin. The null hypothesis tested was that there was no difference in bracket survival distribution, over a period of orthodontic treatment, for brackets bonded with either bonding agent.

DESIGN

Single center randomized controlled clinical study.

SETTING AND SAMPLE POPULATION

Twenty-five consecutive patients (15 females and 10 males) were selected and treated with fixed appliances in a university postgraduate orthodontic clinic. All teeth, but the molars, were bonded with twin stainless steel brackets (n = 429) using a split-mouth technique and random allocation of the two adhesives.

OUTCOME MEASURE

Bond failure rates during a period of 9 months were estimated for each adhesive system and the corresponding bracket survival curves were plotted using the Kaplan-Meier product-limit estimate. Bracket survival distributions with respect to adhesive material, tooth location, investigator, and bond failure interface were then compared by means of a log-rank test. Bond failure interface was determined using the Adhesive Remnant Index (ARI).

RESULTS

The water-activated bonding material recorded a significantly higher bond failure (22.4%) than the composite resin (5.1%). There were also statistically significant differences in bracket survival distributions between the two adhesives (log-rank test: p < 0.001). Premolars exhibited higher bond failure rates than incisors and canines (p < 0001). The predominant mode of failure was within the bonding material.

CONCLUSION

Further investigations focused on the improvement of the physical and mechanical properties of the water-activated bonding system are needed to make it a reliable alternative adhesive for the direct bonding of orthodontic brackets.

Halogen versus high-intensity light-curing of uncoated and pre-coated brackets: a shear bond strength study

AIM

To evaluate the shear bond strengths of adhesive pre-coated brackets (APC) and conventional uncoated brackets (Victory) cured with two different light-curing units: a conventional halogen light (Visilux 2) and a micro-xenon light (Aurys).

SETTING

Ex vivo study

MATERIALS AND METHODS

Sixty freshly extracted bovine permanent mandibular incisors were randomly assigned to one of four groups, each group consisting of 15 specimens. Two groups (one for each type of bracket) were exposed to the halogen light for 20 seconds and used as controls. The remaining two groups were cured with the micro-xenon light for 2 seconds. After 24 hours, all samples were tested in a shear mode on an Instron Machine. Analysis was by two-way ANOVA with Scheffé's test for comparisons, Kaplan-Meier survival estimates, and Cox model. The Chi-square (chi(2)) test was used to determine significant differences in the ARI scores.

RESULTS

The mean shear bond strength of the uncoated brackets cured with Visilux 2 was significantly higher than those of all the other groups tested. Both groups cured with Visilux 2 produced significantly higher mean shear bond strengths than those of the corresponding groups cured with Aurys. No statistically significant differences were found between the two groups cured with Aurys.

CONCLUSIONS

Compared to halogen light-curing, the micro-xenon light enables the clinician to reduce significantly the curing time of both APC and uncoated brackets, and although significantly lower, their shear bond strengths may be clinically acceptable.

An ex vivo study to investigate bond strengths of different tooth types

This study aimed to identify the presence and pattern of differences in ex vivo shear bond strength between tooth types when bonding orthodontic brackets using Right-On, and took the form of a prospective laboratory study of bond strength on different tooth types, at the Newcastle University Dental School Materials Science Laboratory, 1997-1999. Ex vivo bond strength testing was undertaken using the technique described by Fox et al. (BJO 18, 125-130, 1991) on a total of 120 extracted incisor, canine, and premolar teeth of each dental arch. Analysis was by one-way ANOVA with Tukey's pairwise comparisons, and by Weibull Analysis. Shear stress to failure (measured in MPa) was recorded on Instron 5567 universal testing machine. Significant differences in mean bond strength existed between different tooth-type series. Canine (upper 12.3, lower 12.1) and premolar (upper 11.9, lower 10.9) teeth exhibited higher strengths than incisors (upper 6.9, lower 9.0). The results of this study confirm that ex vivo bond strength is not uniform across all teeth.