A clinical trial comparing the failure rates of two orthodontic bonding systems

Analysing the potential of hydrophilic adhesive systems to optimise orthodontic bracket rebonding

Introduction

Bond failure during fixed orthodontic treatment is a frequently occurring problem. As bracket rebonding is associated with reduced shear bond strength, the aim of the present investigation is to analyse the effect of different innovative rebonding systems to identify optimised rebonding protocols for orthodontic patient care.

Methods

Metallic brackets were bonded to the frontal enamel surfaces of 240 bovine lower incisors embedded in resin bases. Teeth were randomly divided into two major experimental groups: in group 1 a hydrophilic primer (Assure™ PLUS) was compared to commonly used orthodontic adhesives (Transbond XT™, BrackFix®, Grengloo™) and a zero control. In group 2 different rebonding systems were analysed using a hydrophilic primer (Assure™ PLUS), a methyl methacrylate-consisting primer (Plastic Conditioner) and a conventional adhesive (Transbond XT™). All teeth were tested for shear bond strength according to the DIN-13990 standard, the Adhesive Remnant Index and enamel fracture rate.

Results

The hydrophilic primer enhanced shear bond strength at first bonding (Assure™ PLUS 20.29 ± 4.95 MPa vs. Transbond XT™ 18.45 ± 2.57 MPa; BrackFix® 17 ± 5.2 MPa; Grengloo™ 19.08 ± 3.19 MPa; Meron 8.7 ± 3.9 MPa) and second bonding (Assure™ PLUS 16.76 ± 3.71 MPa vs. Transbond XT™ 13.06 ± 3.19 MPa). Using Plastic Conditioner did not seem to improve shear bond strength at rebonding (13.57 ± 2.94). When enamel etching was left out, required shear bond strength could not be achieved (Plastic Conditioner + Assure™ PLUS 8.12 ± 3.34 MPa; Plastic Conditioner: 3.7 ± 1.95 MPa). Hydrophilic priming systems showed decreased ARI-scores (second bonding: 2.63) and increased enamel fracture rates (first bonding: 55%; second bonding 21,05%).

Conclusions

Based on the present study we found that rebonding strength could be compensated by the use of hydrophilic priming systems. The additional use of a methyl methacrylate-consisting primer does not seem to enhance shear bond strength. No etching approaches resulted in non-sufficient bond strength.

Bond Strength of an Orthodontic Adhesive Containing an Antibiofilm Agent (Octafluoropentyl Methacrylate)

Objective

The objective of this study was to determine whether an adhesive containing antibiofilm agent octafluoropentyl methacrylate (OFPA) has an acceptable bond strength as an orthodontic adhesive.

Methods

Sixty human premolars were divided into four groups. In Groups 1 and 2, brackets were bonded to the teeth using experimental nanohybrid adhesive containing OFPA (ENH-OFPA) and Transbond XT (TXT) was used in Groups 3 and 4. In Groups 1 and 3, the samples were stored in water at 37°C for 24 h and in Groups 2 and 4 thermocycled between 5°C and 55°C. The entire samples were debonded utilizing a universal testing machine. Two-way ANOVA test employed to compare the shear bond strength (SBS) between two adhesives. Independent Student's t-test was utilized to compare the SBS at 24 h and followed thermocycling in each adhesive group. Adhesive remnant index (ARI) evaluated in different groups using Chi-square test.

Results

The mean value for SBS in ENH and TXT groups were 8.13 MPa and 8.10 MPa, respectively. The inference of P = 0.260 was observed and concluded to be nonsignificant for adhesives in terms of SBS. Statistically, differences that observed in SBS at 24 h and following thermocycling in TXT (P = 0.288) and ENH-OFPA (P = 0.145) groups did not consider to be significant. Comparing ARI scores with bracket failure mode resulted in no significant difference (P = 1) between two adhesives in both 24 h and following thermocycling.

Conclusion

Adding OFPA does not compromise SBS of the experimented orthodontic adhesive.

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.

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.

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.

Comparative Evaluation of Two Bis-GMA Based Orthodontic Bonding Adhesives - A Randomized Clinical Trial

INTRODUCTION

Of the various orthodontic bonding materials, orthofix is a fairly new entrant into this field. This material was exclusively introduced for orthodontic bonding purposes; however, the application of this material for orthodontic purpose has not been scientifically evaluated so far.

AIM

The aim of the present study was to evaluate by an in-vivo double blinded split mouth rando mized clinical trial, the overall bond failure rates of two Bis-GMA based composite materials namely Transbond XT and Orthofix.

MATERIALS AND METHODS

Thirty three participants who fulfilled the inclusion criteria were randomly allocated by lottery method into two groups. Group A participants had maxillary right and the mandibular left quadrants bonded using Orthofix and the remaining quadrants were bonded using Transbond XT. In Group B, the quadrants were reversed. Both groups were followed for a period of six months and were reviewed every 3-4 weeks. If a bond failed, the details were recorded and the duration of treatment before each breakage was calculated. Data were analyzed using Independent t-test and chi-square test. (p< 0.05) at 90% power.

RESULTS

The overall bond failure rate for 263 brackets was 2.7% for Orthofix and 3.6% for Transbond XT. The mean esitmated survival time was 221.58 days for Transbond XT and for Orthofix was 220.07 days. The difference between these mean values were statistically insignificant (p>0.05). Similarly, failure rates of the anterior and posterior segment were compared and no difference was observed between the groups (p>0.05). The maxillary and mandibular teeth were compared and more failures were found in the mandibular teeth among both the groups but they were not statistically significant (p>0.05).

CONCLUSION

The overall bond failure rate and mean survival time for Transbond XT was similar to Orthofix with no statistically significant difference.

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.

Orthodontic bonding with and without primer: a randomized controlled trial

OBJECTIVE

To evaluate the incidence of failure of brackets bonded with and without primer.

DESIGN

A single-operator, cross-mouth, randomized controlled trial (RCT).

SETTING

The Orthodontic Department at the Postgraduate Dental Education Centre, Örebro, Sweden.

ETHICAL APPROVAL

Ethical approval was granted by the Regional Ethical Review Board, Uppsala, Sweden.

PROTOCOL

The protocol was not published before trial commencement.

SUBJECTS AND METHODS

Fifty consecutive patients requiring bimaxillary orthodontic treatment with fixed appliances and with an equal number of teeth on each side of the dental arch, were included in this RCT. A cross-mouth methodology was applied. In each patient, two diagonal quadrants (i.e. upper right and lower left, or vice versa) were randomly assigned to the primer group (control group) and the contralateral diagonal quadrants to the non-primer group (experimental group). The randomization process was as follows: A computer-manufactured block-randomization list was acquired and stored with a research secretary at the Postgraduate Dental Education Centre. Each time a patient gave consent, the secretary was contacted by e-mail, and information about which quadrants were to be bonded with and without primer was obtained. All incidents of bracket failure and debonding noted in patient records during the 2012-14 observation period were compiled by the other co-author, whom was blinded to the study and did not perform any orthodontic treatment on the study patients.

MAIN OUTCOME MEASURES

Number of bracket failures over 18 months.

RESULTS

Failure rate without primer was 5.5 per cent and with primer 3.1 per cent; P = 0.063, odds ratio (OR) 1.89 [95% confidence interval (CI) 0.97-3.68] in the adjusted model. Younger ages (10-13 years), boys, and mandible were significantly associated with higher failure rates. Interaction tests indicated that younger patients had significantly higher failure rates without (12.1 per cent) than with primer (4.1 per cent), P < 0.001, OR 3.51 (95% CI 1.93-6.38) in the adjusted model. No failure rate differences between study settings were found for older patients (14-18 years).

LIMITATIONS

The difference between two groups was powered at 5 per cent. Some clinicians may consider a difference less than 5 per cent clinically significant.

CONCLUSION

Bonding Victory Series™ brackets with Transbond™ XT with or without Transbond™ MIP primer seems overall to work equally well in a clinical setting, except in younger children where lower failure rate was found in the primer setting.

Clinical effect of reducing curing times with high-intensity LED lights

OBJECTIVE

To evaluate the clinical performance of brackets cured with a high-intensity, light-emitting diode (LED) with a shorter curing time.

MATERIALS AND METHODS

Thirty-four patients and a total of 680 brackets were examined using a randomized split-mouth design. The maxillary right and mandibular left quadrants were cured for 6 seconds with a high-intensity LED light (3200 mW/cm(2)) and the maxillary left and mandibular right quadrants were cured for 20 seconds with a standard-intensity LED light (1200 mW/cm(2)). Alternating patients had the quadrants inverted for the curing protocol. The number and date of each first-time bracket failure was recorded from 199 to 585 days posttreatment.

RESULTS

The bracket failure rate was 1.18% for both curing methods. The proportion of bracket failure was not significantly different between curing methods (P  =  1.000), genders (P  =  1.000), jaws (P  =  .725), sides (P  =  .725), or quadrants (P  =  .547). Posterior teeth exhibited a greater proportion of failures (2.21%) relative to anterior teeth (0.49%), although the difference was not statistically significant (P  =  .065).

CONCLUSIONS

No difference was found in bond failure rates between the two curing methods. Both methods showed bond failure rates low enough to be considered clinically sufficient. The high-intensity LED light used with a shorter curing time may be considered an advantage due to the reduced chair time.

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.

Clinical bond failure rates of adhesive precoated self-ligating brackets using a self-etching primer

OBJECTIVE

To comparatively assess the failure rate of adhesive precoated (APC) self-ligating metal brackets bonded with two different enamel surface preparation techniques: self-etching primer (SEP) and conventional two-step etch and primer method (CM).

MATERIALS AND METHODS

Fifty-seven patients with complete permanent dentition were included in this study. A total of 1140 APC self-ligating brackets (3M Unitek, Monrovia, Calif) were bonded using a split-mouth design. For each patient, SEP (Transbond Plus SEP, 3M Unitek) and CM (37% phosphoric acid) were used in alternate quadrants. All brackets were bonded by the same investigator after pumicing and rinsing of all of the teeth. The number, site, and date of first-time bracket failures were monitored throughout orthodontic treatment (mean, 22 months). The survival rates of the brackets were estimated by Kaplan-Meier and log-rank tests (P < .05). The adhesive remnant index was used to determine the bond failure interface.

RESULTS

The bond failure rates were 2.97% and 2.18% for the CM and SEP, respectively. No statistically significant difference in failure rates was found between the groups. The bond failure sites were predominantly at the enamel-adhesive interface in both groups.

CONCLUSION

This long-term in vivo study showed that the combined use of SEP and the APC bracket system can be used effectively for bonding brackets after pumicing the enamel surfaces in clinical orthodontics.

Twelve-month bracket failure rate with amorphous calcium phosphate bonding system

The aim of the study was to compare the survival rate of orthodontic brackets over a 12-month period using amorphous calcium phosphate (ACP) bonding system with a conventional adhesive (CA). In 30 patients with a mean age of 15 years 7 months, one operator bonded 138 brackets with a split-mouth design, using a resin-based CA and ACP-containing adhesive. The survival rate of the brackets was estimated by Kaplan-Meier analysis. Bracket survival distributions with respect to bonding procedure, dental arch, type of tooth (incisor, canine, and premolar), and patients' gender were compared using the log-rank test. The bond failure interface was determined using the Adhesive Remnant Index (ARI). The bond failure rates of the CA and ACP-containing adhesive were 2.67 and 3.8 per cent, respectively. There was no significant difference between the failure rates of ACP and CA-bonded systems (P > 0.05). Survival rates did not show significant differences between the upper and lower dental arches (P > 0.05). Lower survival rates were found for canine and premolar teeth than incisors (P < 0.05). Bond failure rates were higher for males than females (P < 0.05). There was a significant difference for ARI scores between the adhesive materials (P = 0.028); more of the ACP-based adhesive was left on the tooth at debond. ACP-containing adhesive can be effectively used to bond orthodontic brackets and can serve as a practicable alternative to the conventional bonding adhesives.

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.

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.

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%.

Kinetics of fluoride release from and reuptake by orthodontic cements

INTRODUCTION

The purposes of this in-vitro study were to compare the fluoride-release profiles and the fluoride release, reuptake, and rerelease characteristics of orthodontic cements before and after topical fluoride treatment.

METHODS

The orthodontic cements tested were 2 resin-modified glass ionomers (Vitremer [3M Dental Products, St Paul, Minn] and Fuji Ortho LC [GC Dental, Tokyo, Japan]), a glass ionomer (Ketac-Cem [Espe-Premier Dental Products, Norristown, Pa]), and a composite (Concise [3M Dental Products]). Fifteen specimens of each material were stored in plastic vials containing deionized water at 37 degrees C. Fluoride release was measured daily for the first 15 days and then weekly for a 57-day period. After initial elusion, specimens were exposed to 1.23% acidulated phosphate fluoride gel, and the fluoride release was monitored daily for 7 consecutive days. The fluoridation/elution procedure was repeated once, and the specimen surfaces were then examined with a scannning electron microscope.

RESULTS

Kinetic release profiles of the test materials were deduced. All materials except Concise had similar fluoride-release profiles. Vitremer demonstrated the highest fluoride release, followed by Fuji Ortho LC and then Ketac-Cem in the time period of the study (P <.01). All glass-ionomer cements, but especially Fuji Ortho LC, showed enhanced uptake and release on repeated exposure to the topical fluoride treatment. Nevertheless, Vitremer showed the greatest surface degradation after refluoridation.

CONCLUSIONS

All resin-modified and conventional glass ionomers studied exhibited the capacity for fluoride release and reuptake after fluoridation, but the subsequent fluoride release was transitory. Thus, the benefit from fluoride reuptake in these orthodontic cements should be balanced with the risk of weakening them after repeated fluoridation.

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.

Clinical comparison between a modified light-curing denture base resin and a conventional composite resin for orthodontic bonding

The purpose of this in vivo study was to evaluate and compare the bond failure rate of a modified visible light-cured denture base resin (Triad VLC Provisional Material; Dentsply International Inc., York, PA) with that of a conventional visible light-cured composite resin (Transbond XT; 3M/Unitek, Monrovia, CA) for the bonding of orthodontic brackets. Both adhesives were used in each patient following a split-mouth design. Thirty-five consecutive patients with fixed appliances were included in the study, and the performance of 655 stainless steel brackets was evaluated: 325 brackets were bonded with the modified Triad VLC resin and 330 were bonded with Transbond XT resin. The incidence and site of bond failures were recorded over a period of 12 months. The overall failure rate of Triad VLC (4.3%) was not significantly different (p>0.05) from that of Transbond XT (3.6%). No significant differences in the failure rates of upper and lower arches within each material or between the two materials were found (p>0.05). Transbond XT showed a significantly higher failure rate (p<0.05) in the anterior (4.8%) than in the posterior teeth (1.6%). The present findings demonstrate that Triad VLC could be used as an alternative bonding material for direct bonding of orthodontic brackets.

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.

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.

Metallic bracket to enamel bonding with a photopolymerizable resin-reinforced glass ionomer

Enamel acid etching plays an important role in treatment on direct bracket bonding. Several studies have been carried out concerning the damage this procedure causes to the enamel. A valuable alternative seems to be the use of photopolymerizable resin-reinforced glass ionomer without acid etching of enamel. This study compares the strength of bracket debonding, the amount of remnant adhesive on the tooth, and the enamel condition in 3 adhesive systems. Three groups were set; in the first group, a glass ionomer with a photopolymerizable resin reinforce and enamel etching with orthophosphoric acid at 37% was used; in the second group, the same ionomer was used but without acid etching; and in the third group, a photopolymerizable resin was used after etching enamel with orthophosphoric acid at 37%. Debonding strength was determined in MPa; a stereoscopic microscope was used to determine the amount of remnant adhesive on the tooth in accordance to ARI and a scanning electron microscope study was made to observe the enamel conditions, existing in debonding among groups (P <.0001), with etching and without etching. The remnant adhesive on the tooth did not show a significant difference (P = 1.000); greater irregularities were found in the enamel in the etching groups. It was demonstrated that the etching was a critical factor in obtaining adequate adhesion strength and that it alters the enamel conditions. Teeth with ionomer and etching had a greater material remnant.

Bonded molar tubes: a retrospective evaluation of clinical performance

This study investigated time to first failure of stainless steel orthodontic first permanent molar tubes (Ormco Corp) bonded with a light-cured resin adhesive (Transbond) and assessed whether this was related to patient gender, age of the patient at the start of treatment, the presenting malocclusion, or the operator. All first molar tubes were bonded to intact buccal enamel, free of any restoration. Survival analysis was carried out on data from 483 patients with 1190 bonded first molar tubes. For each case, a single molar tube, either that which was first to fail or had the shortest follow-up time, was chosen for analysis. The median time until first bonded tube failure was 699 days with an overall failure rate of 21% recorded. There was no significant difference in time to first failure of molar tubes with respect to patient gender or presenting malocclusion but significant differences were recorded with respect to the patients' age at the start of treatment and the operator. Age at the start of treatment and operator were identified as independently useful predictors of bonded molar tube survival.

A clinical evaluation of the effectiveness of a fluoride-releasing visible light-activated bonding system to reduce demineralization around orthodontic brackets

The presence of decalcification (white spots) after the removal of orthodontic appliances still remains a problem. A method to deliver fluoride to the area beneath and around the bonded attachments, independent of patient compliance, could be very helpful. Therefore special attention is being currently directed to the so-called "fluoride releasing bonding adhesives." A clinical trial was carried out to compare the effect of a visible light-cured fluoride-releasing (F-releasing) material with a chemically cured nonfluoride resin on white spot formation during fixed orthodontic therapy. Fifty patients entered the trial, and 762 brackets were bonded in a crossover design. Intraoral slides were taken before and after treatment and were evaluated for white spot formation. Statistical data analysis was carried out by means of a chi-square test. The results of this clinical study indicate that there was no significant difference between the decalcification rates for both types of adhesives. When the appearance of white spots was evaluated in an overall manner, there was significantly more upper than lower decalcification.