Evaluation of the sealant in orthodontic bonding

Enamel shear bond strength of different primers combined with an orthodontic adhesive paste

AIM

The aim of this study was a comparison of shear bond strength (SBS) on tooth enamel of different primers combined with the adhesive paste Transbond XT.

MATERIALS AND METHODS

Forty bovine teeth were used in order to create 40 test blocks. The blocks were divided into four groups of 10 blocks each: group A - sample primer (SP); group B - Opal Seal (OS); group C - Transbond Plus SEP (TSEP); group D - Transbond XT Primer (TXT). After surface preparation and application of the primer, respectively, two stainless steel brackets were fixed on each tooth by using Transbond XT. Accordingly, 80 brackets were debonded (n=20). Shear bond strength and adhesive remnant index (ARI) scores were evaluated. Statistical analyses were performed by using the Student's t-test and Mann-Whitney U test.

RESULTS

All tested groups revealed high shear bond strength in a similar size range. There were no significant differences between the groups concerning shear bond strength. The ARI scores of group C showed significantly lower ARI scores (0 and 1) than that of group D. Apart from that there was no statistical difference.

CONCLUSION

In combination with the adhesive paste Transbond XT, all tested primers were suitable for fixing orthodontic brackets. The primers could be changed according to the clinical situation.

Orthodontic bracket bonding without previous adhesive priming: A meta-regression analysis

OBJECTIVE

To determine the consensus among studies that adhesive resin application improves the bond strength of orthodontic brackets and the association of methodological variables on the influence of bond strength outcome.

MATERIALS AND METHODS

In vitro studies were selected to answer whether adhesive resin application increases the immediate shear bond strength of metal orthodontic brackets bonded with a photo-cured orthodontic adhesive. Studies included were those comparing a group having adhesive resin to a group without adhesive resin with the primary outcome measurement shear bond strength in MPa. A systematic electronic search was performed in PubMed and Scopus databases.

RESULTS

Nine studies were included in the analysis. Based on the pooled data and due to a high heterogeneity among studies (I(2)  =  93.3), a meta-regression analysis was conducted. The analysis demonstrated that five experimental conditions explained 86.1% of heterogeneity and four of them had significantly affected in vitro shear bond testing. The shear bond strength of metal brackets was not significantly affected when bonded with adhesive resin, when compared to those without adhesive resin.

CONCLUSIONS

The adhesive resin application can be set aside during metal bracket bonding to enamel regardless of the type of orthodontic adhesive used.

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.

Laboratory evaluation of toothbrush/toothpaste abrasion resistance after smooth enamel surface sealing

OBJECTIVES

The use of dental sealants has been extended to smooth enamel surfaces. The present study was conducted to test the in vitro performance of four sealants with different characteristics (highly and lowly filled, self-etching features).

MATERIALS AND METHODS

Eighty human teeth (lower incisors and premolars) were randomly divided into following sealant test groups: ProSeal(TM), LightBond(TM), OrthoSolo(TM), and Seal&Protect(®). Twenty untreated teeth served as a control group. Tooth brushing was conducted for a period of time simulating 12, 18, and 24 months. During the toothbrush abrasion protocol, the specimens were subjected to thermal and acidic challenge. Sealant thickness was determined with μCT imaging, and qualitative and quantitative surface effects were investigated using stereo microscopy and raster electron microscopy, respectively. Data were subjected to t test or Kruskal-Wallis/Mann-Whitney tests (alpha, 5%).

RESULTS

The wear behavior and film integrity of highly filled sealants were superior to lowly filled sealants. Even after 1 year of tooth brushing, significant surface deterioration with deleterious loss of enamel and discoloration was observed in all tested materials (χ(2) = 15.349; P = 0.004). The size of the observed defects increased over time.

CONCLUSION

These results suggest that the application of sealants on smooth enamel surfaces should be limited to special indications, and their usefulness has to be revisited.

CLINICAL RELEVANCE

Based on the results of this in vitro study, the general overall application of enamel sealants needs to be questioned.

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.

Retrospective study of orthodontic bonding without liquid resin

The aim of this study was to evaluate the retention of fixed orthodontic appliances bonded without liquid resin with the use of a retrospective study design. Patients from each of 2 consultant orthodontists in the same specialty clinic were chosen under strict selection criteria. In the test group (n = 37), composite material (Phase II) without liquid resin was used to bond full arch fixed appliances onto patients' upper teeth. Patients' appliances, which were bonded with Phase II composite and liquid resin, were used as the control group (n = 37). The duration of the appliance survival, from the date of appliance bonding to the date of first accidental bracket loss, was analyzed by Kaplan-Meier product limit method and log-rank test. Our data suggested that supragingival orthodontic metal brackets seemed to bond on healthy enamel surfaces and to work equally well either with or without the use of liquid resin. The total percentages of bond failure, roughly 6%, were similar in both test and control groups. Approximately 73% of all patients in the test group and 57% of the patients in the control group experienced no bond failure at all throughout the entire course of treatment.

Prevention of enamel demineralization during orthodontic treatment: an in vitro study using pit and fissure sealants

Enamel demineralization during active orthodontic treatment remains a significant problem. The purpose of this in vitro study was to evaluate the efficacy of applying a light-cured unfilled resin, a conventional pit and fissure sealant, to the labial surface of teeth with previously placed orthodontic appliances to prevent demineralization. Orthodontic brackets were bonded to 40 extracted human teeth with a commercially available orthodontic adhesive. The exposed labial surfaces of 30 teeth (experimental group) were sealed with a clear, light-cured, unfilled resin. The remaining 10 teeth (control group) were left unsealed. Both groups were placed in a demineralization environment, and then all teeth were sectioned and examined under polarized light microscopy for the presence or absence of enamel demineralization. Every member of the control group exhibited demineralization of the entire exposed labial surface, whereas 80% of the sealed teeth exhibited no demineralization. Small, isolated areas of enamel loss were seen in six of the sealed teeth representing "breaks" in the sealant layer. The results of this study indicate that light-cured sealant treatment after orthodontic appliance placement significantly reduces enamel demineralization.