Raed Ajlouni

Comparison of shear bond strength of two self-etch primer/adhesive systems.

Orthodontic brackets adhesive systems use three different agents, an enamel conditioner, a primer solution, and an adhesive resin. A unique characteristic of some new bonding systems is that they combine the conditioning, priming, and adhesive agents into a single application. The purpose of this study was to assess and compare the effects of using one-step and two-step self-etch primer/adhesive systems on the shear bond strength of orthodontic brackets. The brackets were bonded to extracted human molars according to one of two protocols. Group I (control): a two-step self-etch acidic primer/adhesive system was used, Transbond Plus was applied to the enamel surface as suggested by the manufacturer. The brackets were bonded with Transbond XT and light cured for 20 seconds. Group II: a one-step self-etch, self-adhesive resin cement system, Maxcem, was applied directly to the bracket. The self-etch primer/adhesive is made of two components that mix automatically during application. The brackets were then light cured for 20 seconds. The mean shear bond strength of the two-step acid-etch primer/adhesive was 5.9 +/- 2.7 Mpa and the mean for the one-step system was 3.1 +/- 1.7 MPa. The in vitro findings of this study indicated that the shear bond strengths (t = 3.79) of the two adhesive systems were significantly different (P = .001). One-step adhesive systems could potentially be advantageous for orthodontic purposes if their bond strength can be improved.

Effect of a Fluoride-Releasing Self-Etch Acidic Primer on the Shear Bond Strength of Orthodontic Brackets

Conventional adhesive systems use three different agents--an enamel conditioner, a primer solution, and an adhesive resin--during the bonding of orthodontic brackets to enamel. A unique characteristic of some new bonding systems in operative dentistry is that they combine the conditioning and priming agents into a single application. Combining conditioning and priming saves time and should be more cost-effective to the clinician and indirectly to the patient. The purpose of this study was to assess and compare the effects of self-etching primers, including a fluoride-releasing primer, on the shear bond strength of orthodontic brackets. The brackets were bonded to extracted human teeth according to one of four protocols. In group 1 (control), teeth were etched with 37% phosphoric acid; after the sealant was applied, the brackets were bonded with Transbond XT (3M Unitek, Monrovia, Calif) and light cured for 20 seconds. In group 2, a self-etch acidic primer (3M ESPE, St Paul, Minn) was applied as suggested by the manufacturer, and the brackets were then bonded with Transbond XT as in the first group. In group 3, an experimental self-etch primer EXL #547 (3M ESPE) was applied to the teeth as suggested by the manufacturer, and the brackets were then bonded as in groups 1 and 2. In group 4, a fluoride-releasing self-etch primer, One-Up Bond F (J. Mortia, USA Inc. Irvine, Calif) that also has a novel dye-sensitized photo polymerization initiator system was applied as suggested by the manufacturer, and the brackets were then bonded as in the other groups. The present in vitro findings indicated that the shear bond strengths of the four groups were significantly different (P = .001). Duncan multiple range tests indicated that One-Up Bond F (mean +/- SD strength, 5.1+/-2.5 MPa) and Prompt L-Pop (strength, 7.1+/-4.4 MPa) had significantly lower shear bond strengths than both the EXL #547 self-etch primer (strength, 9.7+/-3.7 MPa) or the phosphoric acid etch and the conventional adhesive system (strength, 10.4+/-2.8 MPa).

The effect of saliva contamination on shear bond strength of orthodontic brackets when using a self-etch primer.

The purpose of this study was to assess the effect of saliva contamination on the shear bond strength of orthodontic brackets, at various stages of the bonding procedure using a new self-etch primer. Brackets were bonded to 52 extracted human molars according to one of the following four protocols. Group I (uncontaminated control): A self-etch acidic primer, Angel I (3M/ESPE Minneapolis, Minn) was placed on the enamel for 15 seconds, gently dried with air, and light cured for 10 seconds. Precoated brackets APC II (3M Unitek, Monrovia, Calif) were then placed on the teeth and light cured for 20 seconds. Group II: The enamel surface was first contaminated with human saliva for 10 seconds, blown off with an air syringe for five seconds. The bonding procedure was then repeated as in group I. Group III: The self-etch primer was applied for 15 seconds, gently dried with air, and light cured for 10 seconds. The surface was then contaminated with human saliva for 10 seconds, blown off with an air syringe for five seconds. The precoated brackets were then bonded as in groups I and II. Group IV: The enamel surface was contaminated with human saliva for 10 seconds, blown off with an air syringe for five seconds. The self-etch primer was applied. The surface was then re-contaminated with human saliva for 10 seconds, blown off with an air-syringe for five seconds. The precoated brackets were then bonded as in groups I, II, and III. The results of the analysis of variance (F = 4.79) indicated that the shear bond strengths of the four groups were significantly different (P = .005). Tukey HSD tests indicated that contamination both before and after the application of the acid-etch primer resulted in a significantly lower (=1.7+/-1.4 MPa) shear bond strength than either the control group (=6.0+/-3.5 MPa) or the groups where contamination occurred either before (=4.8+/-3.3 MPa) or after (=4.8+/-3.3 MPa) the application of the primer. The new acid-etch primer can maintain adequate shear bond strength if contamination occurs either before or after the application of the primer. On the other hand, contamination both before and after the application of the primer significantly reduced the shear bond strength of orthodontic brackets.

Evaluation of a new curing light on the shear bond strength of orthodontic brackets.

With the introduction of photosensitive (light-cured) restorative materials in dentistry, various methods were suggested to enhance their polymerization and to shorten the curing time including layering and the use of more powerful light-curing devices. The purpose of this study was to determine the effect of using a new light-curing apparatus that uses a light-emitting diode (LED) on the shear bond strength of an orthodontic adhesive. The new light-curing apparatus used in the study was UltraLume 2 (Ultradent USA, South Jordan, Utah) that has an 8-mm footprint and can simultaneously cure two orthodontic brackets. Forty teeth were etched with 37% phosphoric acid, washed and dried, and sealant applied, and then precoated brackets with the Transbond adhesive (APC II, 3M Unitek, Monrovia, Calif) were placed. The teeth were randomly divided into two groups according to the curing light used. In group I (control), 20 brackets were cured using an Ortholux (3M Unitek) halogen curing light for 20 seconds. In group II, 20 brackets were cured using the new LED light for 20 seconds. The findings indicated no significant (P = .343) differences in the shear bond strength between the Ortholux halogen light (5.1 +/- 2.5 MPa) and the UltraLume 2 LED light when the two groups were compared using Students t-test (t = -0.961). In conclusion, the advantages of the new unit include the ability to cure two brackets at a time and a smaller light-emitting apparatus for the clinician to handle.

Comparison of bonding time and shear bond strength between a conventional and a new integrated bonding system.

Conventional adhesive systems use 3 different agents, an enamel conditioner, a primer solution, and an adhesive resin during the bonding of orthodontic brackets to enamel. A characteristic of some new bonding systems is that they combine the conditioning and priming agents into a single application as well as precoat the bracket with the adhesive in an attempt to save time during the bonding procedure. This study compared the total bonding time and shear bond strength (SBS) of 2 bracket-bonding systems: (1) an integrated system that incorporates a self-etching primer and precoated brackets and (2) a conventional system in which the etchant and primer are applied separately and the adhesive applied to the bracket by the clinician. The results of the SBS and the total bonding time comparisons (t = 3.451) of the 2 adhesive systems showed a significant difference (P = .0001). The mean SBS was 9.4+/-3.7 MPa for the new bonding system and 6.2+/-4.4 MPa for the conventional system. The mean total bonding time was 36.5 s/tooth for the new system and 46.7 s/tooth for the conventional system. The clinician has to decide whether the increase in bond strength, the decrease in the total bonding time, and the steps saved during the bonding procedure with the new bonding system balance the increased cost incurred.

The effect of porcelain surface conditioning on bonding orthodontic brackets.

The purpose of this study was to evaluate the effects of a new self-etching primer/ adhesive used to enhance the shear strength of orthodontic brackets bonded to porcelain surfaces. Forty-five porcelain maxillary central incisor teeth were used in the study. The teeth were divided randomly into three groups: group I (control), the porcelain teeth were etched with 37% phosphoric acid followed by a sealant and the brackets were bonded with a composite adhesive; group II, the porcelain teeth were microetched and hydrofluoric acid and silane applied and metal brackets were then bonded with the composite adhesive; and group III, the porcelain teeth were etched with phosphoric acid and a self-etching primer/adhesive applied before bonding. Brackets precoated with the adhesive were used on all three groups of teeth. All teeth were stored for 24 hours at 37 degrees C before debonding. The results of the analysis of variance (F = 10.7) indicated that there was a significant difference (P = .001) between the three groups. The mean shear bond strengths of conventional bonding using a 37% phosphoric acid and sealant was 4.4 +/- 2.7 MPa, whereas that of microetching followed by the application of hydrofluoric acid and silane was 11.2 +/- 4.7 MPa, and for the new self-etching primer/adhesive it was 10.3 +/- 5.3 MPa. The last two groups had the highest bond strength values and were not significantly different from each other.

Effects of Modifying the Adhesive Composition on the Bond Strength of Orthodontic Brackets

In an attempt to save chair time during bonding, metal brackets have been precoated with the adhesive material. Although the adhesive used on the precoated brackets is basically similar in composition to that used for bonding uncoated brackets, there are differences in the percentages of the various ingredients incorporated in the material. These changes are intended to enhance specific clinical properties. The purpose of this study was to determine whether modifications in the composition of the adhesives, used on precoated and uncoated metal brackets, affect their shear bond strengths during the first half hour after bonding. This is the time span when the initial arch wires are ligated. Sixty freshly extracted human molars were bonded with three different compositions of the same basic adhesive. The teeth were mounted in phenolic rings. An occlusogingival load was applied to the brackets producing a shear force at the bracket-tooth interface utilizing a Zwick Universal Test Machine. Analysis of variance was used to compare the three adhesives. Significance was predetermined at < or =.05 level of confidence. The present findings indicated that the shear bond strengths of the various modifications of the adhesive used on two different precoated metal brackets were not significantly different (F-ratio = .729 and P = .407) from those obtained with the conventional adhesive used on uncoated brackets. The mean values for the shear bond strengths of the two precoated brackets were: APC = 5.1+/-1.7 MPa and APC II = 4.9+/-2.1 MPa. The shear bond strength for the conventional adhesive used on the uncoated brackets was = 5.7+/-2.4 MPa. All bracket/adhesive combinations tested provided clinically acceptable shear bond forces within the first 30 minutes after initial bonding.

Early shear bond strength of a one-step self-adhesive on orthodontic brackets.

OBJECTIVE The purpose of this study was to determine whether a self-adhesive universal cement, RelyX Unicem (3M ESPE, Seefeld, Germany), can be used successfully to bond orthodontic brackets to enamel. MATERIALS AND METHODS Forty human molars were cleaned, mounted, and randomly divided into two groups: 20 orthodontic brackets were bonded to teeth using RelyX Unicem, and 20 brackets were bonded using the Transbond XT (3M Unitex, Monrovia, Calif) adhesive system. The teeth were debonded within 30 minutes after initial bonding using a universal testing machine. After debonding, the enamel surface was examined under 10x magnification to determine the amount of residual adhesive remaining on the tooth. Students t-test was used to compare the shear bond strength (SBS) of the two groups, and the chi-square test was used to compare the Adhesive Remnant Index (ARI) scores for the two adhesive systems. RESULTS The mean SBS of the brackets bonded using the RelyX Unicem was 3.7 +/- 2.1 MPa and was significantly lower (t = 2.07, P = .048) than the SBS of the brackets bonded with the Transbond system (x = 5.97 +/- 4.2 MPa). The comparisons of the ARI scores between the two groups (chi(2) = 17.4) indicated that bracket failure mode was significantly different (P = .002) with more adhesive remaining on the teeth bonded with Transbond XT. CONCLUSIONS The SBS of the self-adhesive universal cement needs to be increased for it to be successfully used for bonding orthodontic brackets.

The Effect of Variation in Mesh-Base Design on the Shear Bond Strength of Orthodontic Brackets

This study compared the shear bond strengths of two metallic orthodontic brackets, one with a single-mesh bracket base and the other with a double-mesh bracket base. The Transbond XT adhesive system was used to bond all brackets to the teeth. Two types of brackets were compared, ie, 20 Ovation metal bracket series, with a double-mesh base (Super-mesh) and an 81.50 gauge (0.126 inch), and 20 Victory series metal brackets that have a miniature single-mesh base. The teeth were bonded and debonded within half an hour from the initial bonding. The enamel surface was examined under 10x magnification to determine how much residual adhesive remained on the tooth. Students t-test was used to compare the shear bond strength of the two groups. Chi-square test was used to compare the adhesive remnant index (ARI) scores for the two bracket types. The mean shear bond strength for the double-mesh brackets was 5.2 +/- 3.9 MPa and for the single-mesh brackets was 5.8 +/- 2.8 MPa. The t-test comparisons indicated that they were not significantly different from each other (P = .157). The ARI comparisons indicated that both bracket types had similar bracket failure modes and were not significantly different from each other (chi2 = 2.0, P = .5). These results indicated that single- and double-mesh bracket bases have comparable shear bond strength and bracket failure modes.

A new premixed self-etch adhesive for bonding orthodontic brackets.

OBJECTIVE To determine if a new premixed self-etch adhesive can be used to successfully bond orthodontic brackets to enamel. MATERIALS AND METHODS Forty human molars were cleaned, mounted, and randomly divided into two groups. In group 1, 20 teeth were conditioned using the self-etching primer Transbond Plus (3M Unitek, Monrovia, Calif). In group 2, 20 teeth were conditioned using a new premixed self-etching adhesive, AdheSE One (Ivoclar Vivadent Inc, Amherst, NY). Both groups were bonded using brackets precoated with a composite adhesive. The teeth were debonded within half an hour following initial bonding using a universal testing machine. After debonding, the enamel surface was examined under 10x magnifications to determine the amount of residual adhesive remaining on the tooth. A Students t-test was used to compare the shear bond strength (SBS) of the two groups, and the Chi-square test was used to compare the adhesive remnant index (ARI) scores for the two adhesive systems. RESULTS The mean SBS of the brackets bonded to the teeth using AdhesSE One was 3.6 +/- 1.3 MPa and was significantly lower (t = 2.80, P = .01) than the SBS of the brackets bonded using Transbond Plus (x = 5.9 +/- 3.2 MPa). The comparisons of the ARI scores between the two groups (chi2 = 19.26) indicated that bracket failure mode was also significantly different (P < .001), with more adhesive remaining on the teeth bonded using Transbond Plus. CONCLUSIONS The SBS of the new premixed self-etching adhesive needs to be increased for it to be successfully used for bonding orthodontic brackets.