Protect Bond Research Articles

Antimicrobial properties of dentine bonding agents determined using in vitro and ex vivo methods

Aims To determine the antimicrobial properties of a selection of dentine bonding agents [DBAs] using the disc diffusion and direct contact methods and an ex vivo method using extracted carious permanent molar teeth. Methods DBAs ( n = 15) were tested using Streptococcus mutans UA159 in disc diffusion and direct contact methods. In the ex vivo study 6 DBAs were selected and pre- and post-treatment samples of carious dentine ( n ≤ 12) were taken. Samples were also taken post-acid-etching. The number of microorganisms in dentine sample was determined and compared. Results The inhibition zones and percent growth inhibition were related to the pH of the culture medium containing the DBA ( p < 0.01). Clearfill Protect Bond exhibited the greatest bacterial killing followed by ibond (99.8% ± 0.08 and 98.2 ± 1.4, respectively). The phosphoric acid etchant alone resulted in an 83% killing. The in vitro tests results did not correlate. The ex vivo killing reflected the percent growth inhibition observed in the direct contact method. Conclusion A guide to the potential antimicrobial activity of a DBA may be gained from an assessment of its pH when added to bacteriological culture medium. The direct contact method gives a better reflection of the killing of bacteria in infected dentine than the disk diffusion method. Killing in the ex vivo model gives a more realistic and more reliable method for determining the antibacterial activity of a given DBA and that comparisons of the relative inhibitory activity of DBAs should be tested using this ex vivo model.

Reinforcement of dentin in self-etch adhesive technology: A new concept

Objective Characterize the ultramorphology and secondary caries inhibition potential of different dentin adhesive systems in order to find a satisfactory explanation resist to recurrent caries. Methods Human premolar dentin was treated with one of the two self-etching adhesive systems, Clearfil SE Bond, Clearfil Protect Bond or an acid-etching adhesive system, Single Bond. The bonded interface was exposed to an artificial demineralizing solution (pH 4.5) for 90 min and then 5% sodium hypochlorite for 20 min. Transmission electron microscopic observation was performed at the adhesive–dentin interface. The width of the reinforced zone was measured and data were analyzed with univariate analysis of variance under general linear model. In order to identify type of crystallites in the reinforced zone selected area electron diffraction was performed. Results An acid–base resistant zone (ABRZ) was found adjacent to the hybrid layer in the outer lesion front with only Clearfil SE Bond and Clearfil Protect Bond, while Single Bond was devoid of this protective zone. Crystallite arrangement and the ultramorphology were almost similar in the corresponding regions of Clearfil SE Bond and Clearfil Protect Bond. However, thickness of the ABRZ at the mid portion was 1159(±41.91) nm in Clearfil protect Bond, which was significantly thicker than that of Clearfil SE Bond ( F = 514.84, p < 0.001). Selected area electron diffraction confirmed the crystallites in the zone as apatite. Conclusions The self-etching adhesive systems created a new reinforced acid resistant dentin under the hybrid layer. Difference in the thickness of the zone expressed a different potential for demineralization inhibition.

Evaluation of shear bond strengths of self-etching and total-etching dental adhesives to enamel and dentin

To evaluate the shear bond strengths of four dental adhesives in vitro. The facial surfaces of 20 human maxillary incisors were prepared to expose fresh enamel and randomly divided into four groups, in each group 5 teeth were bonded with one adhesives: group A (Clearfil Protect Bond, self-etching two steps), group B (Adper( Prompt, self-etching one step), group C (SwissTEC SL Bond, total-etching two steps), group D (Single Bond, total-etching two steps). Shear bond strengths were determined using an universal testing machine after being stored in distilled water for 24 h at 37 degrees C. The bond strengths to enamel and dentin were (25.33 +/- 2.84) and (26.07 +/- 5.56) MPa in group A, (17.08 +/- 5.13) and (17.93 +/- 4.70) MPa in group B, (33.14 +/- 6.05) and (41.92 +/- 6.25) MPa in group C, (22.51 +/- 6.25) and (21.45 +/- 7.34) MPa in group D. Group C showed the highest and group B the lowest shear bond strength to enamel and dentin among the four groups. The two-step self-etching adhesive showed comparable shear bond strength to some of the total-etching adhesives and higher shear bond strength than one-step self-etching adhesive.

Influence of drying time and temperature on bond strength of contemporary adhesives to dentine

Objectives To evaluate the bond strength (μTBS) of self-etching adhesives in different solvent evaporation conditions. Methods Flat dentine surfaces from extracted human third molars were bonded with: (1) 2 two-steps self-etching adhesives (Clearfil SE Bond—CSEB); (Protect Bond—PB) and (2) 2 one-step self-etch systems (Adper Prompt L Pop—ADPLP); (Xeno III—XIII). Bonded dentine surfaces were air-dried for 5 s, 20 s, 30 s or 40 s at either 21 °C or 38 °C. Composite build-ups were constructed incrementally. After storage in water for 24 h at 37 °C, the specimens were prepared for microtensile bond strength testing. Data were analyzed by two-way ANOVA and Student–Newman–Keuls at α = 0.05. Results CSEB and PB performed better at warm temperature with only 20 s of air-blowing. The bond strength increased when XIII was performed at warm temperature at 40 s air-blowing. Extended air-blowing not affect the performance of ADPLP, except at 30 s air-blowing time at warm temperature. Conclusions The use of a warm air-dry stream seems to be a clinical tool to improve the bond strength to self-etching adhesives.

Editor's Summary, Q & A, Reviewer's Critique: Effect of fluoride-releasing light-cured resin on shear bond strength of orthodontic brackets

<h3>Introduction</h3> The aim of this study was to analyze the effect of an enamel-protective resin on the shear bond strength (SBS) of orthodontic brackets bonded with self-etching primer. <h3>Methods</h3> Eighty extracted premolars were randomly divided into 4 groups of 20, and metal brackets were bonded. Group 1 specimens were bonded with Transbond Plus self-etching primer (3M Unitek, Monrovia, Calif) and no fluoride resin; in group 2, a fluoride-releasing resin (Ortho-Coat, Pulpdent, Watertown, Mass) was used with the Transbond Plus self-etching primer; group 3 teeth were bonded with a new antimicrobial self-etching primer (Clearfil Protect Bond, Kuraray Medical, Osaka, Japan) with no fluoride resin; and the same protocol was used in group 4 with an application of Ortho-Coat. A universal testing machine was used to determine the SBS, and the adhesive remaining after debonding was assessed. <h3>Results</h3> There was no difference in SBS whether fluoride-releasing resin was used. Groups 3 and 4 had higher SBS values than the other groups (<i>P</i> <0.001). The Kruskal-Wallis test showed no significant differences in the adhesive remnant index (chi-square = 0.019, <i>P</i> = 0.990). <h3>Conclusions</h3> The application of enamel-protective resin did not affect the bond strength of orthodontic brackets to enamel with self-etching primer systems.

Effect of fluoride-releasing light-cured resin on shear bond strength of orthodontic brackets

The aim of this study was to analyze the effect of an enamel-protective resin on the shear bond strength (SBS) of orthodontic brackets bonded with self-etching primer. Eighty extracted premolars were randomly divided into 4 groups of 20, and metal brackets were bonded. Group 1 specimens were bonded with Transbond Plus self-etching primer (3M Unitek, Monrovia, Calif) and no fluoride resin; in group 2, a fluoride-releasing resin (Ortho-Coat, Pulpdent, Watertown, Mass) was used with the Transbond Plus self-etching primer; group 3 teeth were bonded with a new antimicrobial self-etching primer (Clearfil Protect Bond, Kuraray Medical, Osaka, Japan) with no fluoride resin; and the same protocol was used in group 4 with an application of Ortho-Coat. A universal testing machine was used to determine the SBS, and the adhesive remaining after debonding was assessed. There was no difference in SBS whether fluoride-releasing resin was used. Groups 3 and 4 had higher SBS values than the other groups (P <0.001). The Kruskal-Wallis test showed no significant differences in the adhesive remnant index (chi-square = 0.019, P = 0.990). The application of enamel-protective resin did not affect the bond strength of orthodontic brackets to enamel with self-etching primer systems.

Transdentinal diffusion and cytotoxicity of self-etching adhesive systems

To evaluated the transdentinal diffusion and subsequent cytotoxicity of self-etching adhesives on odontoblast-like cells. Sixty dentin disks (0.4-mm thick) were produced from human molars and divided into six groups (n = 10). The dentin disks were placed in in vitro pulp chambers where MDPC-23 cells were planted on 0.28 cm(2) of exposed dentin on the pulpal side. The adhesives Clearfil SE Bond (CSE), Clearfil Protect Bond (CPB), Adper Prompt (PR), and Xeno III (XE) were applied on the occlusal side. Single Bond (SB) was used as positive and phosphate buffer solution (PBS) as negative control. The cytotoxicity was measured by MTT assay and cell characteristics were assessed by SEM. The transdentinal diffusion was qualified by GC/MS. Kruskal-Wallis and Mann-Whitney tests demonstrated a significant difference among the adhesives and PBS. Cellular viability reduction promoted by the self-etching systems was lower than that of SB (53.1%), except for CSE. Cell metabolism was reduced in 47.8%, 42.1%, 28.0%, and 46.5% for CSE, CPB, PR, and XE, respectively. HEMA was identified as the main diffused component. Components from all investigated self-etching adhesive systems were able to diffuse through the dentin resulting in significant reduction of the cellular metabolism.

Comparison of the sealing of different dentin bonding adhesives in root-end cavities: a bacterial leakage study

To compare the root-end sealing of the different dentin-bonding adhesives (DBAs) in root-end cavities using a bacterial leakage system. One hundred extracted single-rooted teeth were instrumented, and root-ends were resected and ultrasonically prepared. All teeth were then randomly assigned to 6 experimental groups (n = 15) and 2 control groups (positive and negative control; n = 5) for root-end filling with iBond (Heraeus Kulzer, Hanau, Germany), G-bond (GC Co., Tokyo, Japan), Xeno III Bond (Dentsply/Caulk, Milford, DE), AdheSe Bond (Ivoclar Vivadent, Schaa, Liechenstein), Clearfil Protect Bond (Kuraray, Osaka, Japan), or Clearfil Tri-S Bond (Kuraray). All preparations were further restored with a hybrid resin composite (Renew; Bisco, Schaumburg, IL). Nail varnish was applied to all external root surfaces to the level of the resected root-ends to prevent lateral microleakage. Samples were sterilized in an ethylene oxide sterilizer for 12 h. The apical 3-4 mm of the roots were immersed in brain-heart infusion culture medium with phenol red indicator within culture chambers. The coronal access of each specimen was inoculated every 48 h with a suspension of Enterococcus faecalis. Bacterial leakage was monitored every 24 h for 4 weeks. The data obtained were analyzed using a chi-squared test, with alpha = .05 as the level for statistical significance. All positive controls leaked within 24 h; none of the negative controls leaked. Under the conditions of the study, despite some variations, there were no statistically significant differences in rate of bacterial leakage among the experimental test materials at 1-4 weeks (P > .05). The type of DBA had no influence in the bacterial leakage of the root-end fillings.

A New Generation of Self-etching Adhesives: Comparison with Traditional Acid Etch Technique

The aim of this study was to determine the shear bond strength (SBS), etching pattern and depth, and debonding performance of several market-leading, self-etching (SE) adhesives primarily used in restorative dentistry (iBond, Clearfil S(3) Bond, Clearfil Protect Bond, AdheSE, XenoIII), two experimental self-etching adhesives (exp. Bond 1, exp. Bond 2) and one experimental self-etching cement (SE Zement) used with and without prior phosphoric acid-etching, and to compare them to an orthodontic self-etching product (Transbond Plus SE Primer) and to traditional acid-etch technique (Transbond XT Primer, phosphoric acid) All adhesives were applied on pumiced and embedded bovine incisors following the manufacturers' instructions. Then one bracket each (coated with Transbond XT composite) was bonded (n = 20). Transbond XT was polymerized for 20 s from the incisal and gingival sides using a halogen device positioned at a constant 5 mm from and a 45 degrees angle to the specimen. The specimens were stored in distilled water for 24 h at 37 degrees C before measuring SBS. The ARI (adhesive remnant index) for all specimens was determined from the sheared-off brackets of each. After conditioning, the surface texture was morphologically evaluated from scanning electron microscope (SEM) images, while the etching depth was determined using a confocal laser-scanning microscope (CLSM). All groups were tested for normal distribution and analyzed by applying ANOVA, Kruskal-Wallis or the t test. In addition, a Bonferroni correction was used. The median values of the SBS tests were: SE Zement 3.0 MPa, SE Zement preceded by phosphoric acid etching 11.2 MPa, experimental bond 1: 7.4 MPa, experimental bond 2: 5.6 MPa, iBond 8.1 MPa, Clearfil S(3) Bond 14.1 MPa, Clearfil Protect Bond 16.6 MPa, Clearfil SE Bond 15.9 MPa, AdheSE 16.0 MPa, XenoIII 16.1 MPa, Transbond SE Primer 20.7 MPa, acid-etching+Transbond XT Primer 21.0 MPa. With the exception of iBond, we observed no significant differences among the self-etching adhesives used in Restorative Dentistry or in comparison to the Transbond Plus SE Primer. No significant differences were apparent even when compared to the Transbond XT Primer after phosphoric acid-etching. Both experimental bonding agents and SE Zement without acid etching performed significantly worse than the products mentioned above, failing to demonstrate sufficient adhesive strength. SEM examination revealed less distinctive enamel-etching patterns for self-etching products than for phosphoric acid-etching. CLSM analysis revealed etching depths between 0.5 and 20 microm depending on the product. When self-etching products were used, less residual composite remained on the enamel surface than after phosphoric acid-etching. All the adhesives tested are suitable for bonding orthodontic brackets and to reduce the risk of enamel fracture while minimizing etching depth, which in turns means less conditioning-related enamel loss. More development is needed to improve the etching performance of both experimental bonding agents and SE Zement.

Effects of One-year Storage in Water on Bond Strength of Self-etching Adhesives to Enamel and Dentin

The aim of this study was to compare the bond strengths of three self-etching materials during one year of storage. Clearfil SE Bond (SE), Clearfil Protect Bond (PB), and Clearfil Tri-S Bond (TS) were used for bonding to dentin and enamel according to manufacturer's instructions. Microshear bond strength values were measured after 24 hours, six months, and one year. Two-way ANOVA showed that the interaction of material type and storage time was significant for dentin. At baseline, SE had the highest bond strength to dentin. There were no significant changes in bond strength for each material during the storage period, except for PB which showed increased bond strength to dentin after one year. All materials performed reliably after one year. However, the antibacterial and fluoride-releasing effects of PB would further contribute to the long-term clinical benefits of this material.

Comparison of the Antibacterial Activity of Different Self-etching Primers and Adhesives

The aim of this study was to evaluate the antibacterial effects of different one-step and two-step self-etching primer/adhesives on Streptococcus mutans (S. mutans), Lactobacillus casei (L. casei), and Lactobacillus acidophilus (L. acidophilus). The antibacterial effects of Clearfil Protect Bond Primer and Bonding agent; AdheSE Primer and Bonding agent; Adper Prompt L-Pop; Futurabond NR; Clearfil Tri S Bond; and Cervitec (positive control, 1% chlorhexidine varnish) were tested against standard strains of S. mutans, L. Casei, and L. acidophilus using the disk diffusion method. Standard filter paper disks (n=5) impregnated with 20 microL of each material were prepared. After incubation at 37 masculineC for 48 hours in a 5-10% CO2 atmosphere, the diameter of inhibition zones were measured in millimeters. Data were analyzed using one way analysis of variance (ANOVA) and multivariate analysis of variance (MANOVA). Duncan's Multiple Range Test was used for pairwise comparison. The size of inhibition zones produced by primer/adhesives varied among the brands. AdheSE Primer: S. mutans (20.6+/-1.51); L. casei (14.8+/-1.78); L. acidophilus (11.4+/-0.54). Adper Prompt L-Pop: S. mutans (19.6+/-1.51); L. casei (13.8+/-1.64); L. acidophilus (13.8+/-1.09). Cervitec: S. mutans (23+/-0.00); L. casei (27+/-0.70); L. acidophilus (22.4+/-0.54). Clearfil Protect Bond Primer: S. mutans (17+/-0.00); L. casei (17.6+/-0.54); L. acidophilus (22.4+/-0.54). Futurabond NR was found effective only against S. mutans (14.6+/-1.67). Of all the materials tested, AdheSE Bonding agent, Clearfil Protect Bond Bonding agent, and Clearfil Tri S Bond exhibited no inhibition zone (-) for all bacteria tested. Among the adhesives tested Clearafil Protect Bond Primer based upon monomer methacryloyloxydodecylpyridiniium bromide (MDPB) was found to be the most potent material against L. acidophilus and L. casei. AdheSE Primer and Adper Prompt L-Pop are highly effective against S. mutans. Compared with other adhesive systems, Clearfil Protect Bond Primer (containing MDPB) showed a high antibacterial effect against all microorganizms tested. Two-step, self-etching primer/adhesive system Clearfil Protect Bond might be a suitable choice under minimally invasive restorations. The recently developed one-step, self-etching system Clearfil Tri S Bond showed no antibacterial effect against microorgazims tested.

An evaluation and comparison of shear bond strength of composite resin to dentin, using newer dentin bonding agents

The purpose of this study was to assess the shear bond strength of Total etch Prime and Bond NT and self etch newer dentin bonding agents Clearfil S3, Xeno III Bond, Clearfil Protect Bond and G Bond used to bond composite resin to dentin, and to compare the difference in the shear bond strengths of the self etch newer dentin bonding agents. Hundred freshly extracted noncarious human maxillary premolar teeth were selected. The occlusal surfaces of each tooth were ground to prepare flat dentin surfaces at a depth of 1.5 mm and were randomly grouped, with twenty specimens in each: Group I - Prime and Bond NT, Group II - Clearfil Protect Bond, Group III - Xeno III Bond, Group IV - Clearfil S3 Bond, Group V - G Bond. Each group was treated with its respective bonding agents, as per the manufacturers' instructions Clearfill – Kuraray, Japan, G bond – GC Tokyo, Japan, Xeno- De Trey Densply, Germany. Blocks or Cylinders of composite resin were built up using Teflon mold and cured. Shear bond strengths were tested using Instron Universal testing machine and recorded in Mpa. The results were statistically analyzed using One-way anova and Tukeys HSD test. The total etch adhesive showed higher shear bond strength than self etching adhesives (P < 0.001). Within the limitations of this in vitro study, it can be concluded that all the adhesive agents evaluated showed optimal shear bond strength 17-20 Mpa, except G bond. However, shear bond strength of composite resin to dentin is better with one bottle total etch adhesive than with the newer self etching bonding agents.

Bond strength of adhesive systems to dentin and enamel—Human vs. bovine primary teeth in vitro

Objectives This in vitro study compared the bonding performance of four adhesive luting agents to dentin and enamel of human and bovine primary teeth, in order to evaluate the suitability of primary bovine hard tissues for replacement of those of human origin for bond testing. Methods A composite (Clearfil AP-X) was bonded to specimens from 167 extracted human ( n = 88) and bovine ( n = 88) primary teeth using the following adhesive systems: Syntac Assortment (SY), Adaper Prompt L-Pop (PLP), iBond Gluma inside (IB) and Clearfil Protect Bond (PB). After 24 h storage in distilled water, shear bond strength was determined according to ISO/TS 11405:2003. The data ( n = 11 per group) were statistically analyzed with the Mann–Whitney U-test and the error-rates method (ERM). The fracture modes were analyzed with the χ 2-test. Results Bond strength data (ERM) and fracture modes ( χ 2-test) using human primary teeth were, in general, not statistically different from those of bovine origin. With few exceptions, pair wise comparisons showed the same results. The bond strength data for SY, PLP and PB bonded to primary human and bovine enamel were higher than those to primary human and bovine dentin, for IB vice versa. Significance Bovine teeth may be considered as a suitable alternative to human teeth in bond strength tests for primary dentition.

Histomorphologic characterization and bond strength evaluation of caries-affected dentin/resin interfaces: Effects of long-term water exposure

Objectives To evaluate the longevity of sound (SD) and caries-affected dentin (CAD) bonds made with etch-and-rinse and self-etching adhesives after a 6-month water-storage period, using bond strength and morphological evaluations. Methods Extracted human molars with coronal carious lesions were selected. Flat surfaces of CAD surrounded by SD were bonded with etch-and-rinse (Adper Scotchbond 1) or with self-etching (Clearfil Protect Bond and AdheSE) adhesives. Trimmed resin–dentin bonded interfaces (1 mm 2) were stored in distilled water for 24 h or 6 months and subjected to microtensile bond strength (μTBS) evaluation. The quality of the dentin beneath fractured specimens was measured by Knoop microhardness (KHN). ANOVA and multiple comparisons tests were used ( P < 0.05). Fractographic analysis and interfacial nanoleakage evaluation were performed by scanning electron microscopy (SEM). Resin–dentin bonded sections (10 μm thick) were stained with Masson's trichrome and examined using light microscopy. Collagen exposure and adhesive penetration were examined qualitatively. Results μTBS to SD was significantly higher than that to CAD for all bonding agents. Bonds made with AdheSE were weaker than the other adhesives after 6-months storage regardless of the dentin substrate. CAD bonded specimens presented a significant μTBS decrease over time. Lower KHN was recorded in CAD compared to SD. An increase in the exposed collagen zone and a decrease in the quality of the adhesive infiltration were observed in CAD interfaces. Significance CAD bonded interfaces are more prone to hydrolytic degradation than SD bonds. Additionally, as compared to SD, there were remarkable differences in depth of demineralization, adhesive infiltration and interfacial bond strength with CAD.

The induction of oxidative stress, cytotoxicity, and genotoxicity by dental adhesives

Objectives Polymerized dental resin materials release residual monomers that may interact with pulp tissues. We hypothesized that dental adhesives might cause cytotoxicity in pulp cells via the generation of reactive oxygen species (ROS), which may also contribute to genotoxic effects in vitro. Methods For cytotoxicity testing, transformed human pulp-derived cells were exposed to extracts of primers and bonding agents of Clearfil SE bond, Clearfil Protect bond, AdheSE, Prompt L-Pop, and Excite for 24 h. The cytotoxicity of the same materials was also analyzed in a dentin barrier test device using three-dimensional pulp cell cultures. The generation of ROS in monolayer cultures was measured after a 1 h exposure period by flow cytometry (FACS), and genotoxicity as indicated by the formation of micronuclei was determined in V79 cells after a 24 h exposure period. Results The dentin primers and bonding agents decrease cell survival in a dose-related manner. Cytotoxicity of bonding agents based on concentrations which caused 50% cell death (EC50) were ranked as follows: Excite (0.16 mg/ml) > AdheSE bond (0.30 mg/ml) > Clearfil Protect bond (0.35 mg/ml) > Clearfil SE bond (0.37 mg/ml), and Prompt L-Pop bond (0.68 mg/ml). Dentin primers were about 10-fold less effective. In contrast, no cytotoxic effects of the dental adhesives were observed in a dentin barrier test device. Yet, all dental adhesives increased the amounts of ROS about fivefold in pulp cells in a dose-related manner, and, again, the bonding agents were more efficient than the dentin primers. Finally, the number of micronuclei was increased about sixfold by extracts of the AdheSE primer. Significance Our results suggest that the cytotoxic potencies demonstrated by these materials might be of clinical relevance, since all dental adhesives disturbed the cellular redox state of pulp cells in monolayer cultures. As a result, the concentrations of biologically active ingredients of some of the agents may be high enough to modify pulp cell metabolism when the materials are used in deep cavities or directly contact pulp tissue.

Evaluation of the shear bond strength of 3 curing bracket bonding systems combined with an antibacterial adhesive

The purpose of this in-vitro study was to investigate the shear/peel bond strength of metal brackets bonded to human enamel with differently cured bonded systems combined with an antibacterial adhesive component. One hundred twenty extracted molars were divided into 3 groups. Stainless steel brackets were bonded with 1 of 3 systems: group 1, no-mix bonding adhesive (Unite, 3M Unitek, Monrovia, Calif) (n = 40); group 2, 2-paste chemically cured bonding resin (Concise, 3M Unitek) (n = 40); and group 3, light-cured adhesive (Transbond XT, 3M Unitek) (n = 40). Each bonding group was separated into experimental (n = 20) and control groups (n = 20). In the 3 experimental groups, an antibacterial self-etch adhesive (Clearfil Protect Bond, Kurary, Osaka, Japan) was also applied to the enamel. Specimens in the control groups were bonded only with their relevant bonding systems according to the manufacturers' instructions. All specimens were stored in distilled water for 24 hours and thermocycled before testing. Debonded specimens were scored with the adhesive remnant index. The mean bond strengths (in megapascals) were 9.8 (control, 15.7) in group 1, 12.0 (control, 18.5) in group 2, and 11.6 (control, 12.4) in group 3. Statistical analysis with t tests showed no difference between group 3 and its control (P = .178), whereas groups 1 and 2 were statistically different from their controls (P = .000). The results indicated that the newly developed antibacterial self-etch adhesive can be combined with various bonding systems; achieved bond strengths were clinically more than satisfactory.

Shear Bond Strength of Orthodontic Brackets Bonded using Conventional vs One and Two Step Self-etching/adhesive Systems

To assess and compare the effects of one- and two-step self-etching primer and adhesive with conventional acid-etching and bonding system on the shear bond strength of orthodontic brackets. The one-step self-etching primer and adhesive used was Clearfil tri-S bond, the two-step fluoride-releasing antibacterial self-etching primer and adhesive was Clearfil Protect Bond, and the fluoride-releasing conventional acid-etching and bonding system was Kurasper F Bond. Brackets were bonded to defect-free human premolars (n = 14 per group) according to each manufacturer's recommendations by using light-cured bracket adhesive Kurasper F Paste with a light-emitting diode of a light-curing unit. The specimens were stored in deionized water at 37 degrees C for 48 hours and then tested in shear with a universal testing machine at a crosshead speed of 5 mm/min until the brackets debonded. The mode of failure of the brackets was determined by a modified adhesive remnant index. Mean shear bond strength values were 9.00 MPa for Kurasper F Bond, 9.55 MPa for Clearfil Protect Bond, and 9.48 MPa for Clearfil tri-S Bond. One-way analysis of variance detected no statistically significant difference among groups (P = .98, P > .05). The predominant failure for the three groups was at the bracket-adhesive interface leaving less than 25% of the adhesive on the bracket base. One-step self-etching adhesive and two-step fluoride-releasing antibacterial self-etching adhesive have sufficient mechanical properties for the bonding of orthodontic brackets.

Antibacterial properties of self-etching dental adhesive systems

Dental adhesives with antibacterial properties may reduce recurrent or secondary caries. The authors conducted a study to examine the immediate and long-lasting antibacterial properties of four self-etching adhesive systems. The authors used the agar diffusion test (ADT) and direct contact test (DCT) to measure the antibacterial properties of AdheSe (Ivoclar Vivadent, Schaan, Liechtenstein), Adper Prompt L-Pop (3M ESPE, Seefeld, Germany), Clearfil Protect Bond (Kuraray, Kurashiki, Okayama, Japan) and Xeno III (Dentsply, Konstanz, Germany) on Streptoccocus mutans after aging samples in phosphate-buffered saline for one, two, seven and 14 days. Only Clearfil Protect Bond showed an inhibition halo in the ADT. In the DCT, fresh samples of all of the tested materials exhibited potent antibacterial properties, which were maintained by AdheSe for one day and Clearfil Protect Bond for seven days. None of the adhesive systems exhibited any antibacterial properties after 14 days. All of the tested adhesives had an immediate bactericidal effect on S. mutans. None, however, had long-lasting antibacterial properties. The application of self-etching adhesive materials could contribute to the immediate elimination of residual bacteria. The likelihood of developing secondary caries as a consequence of bacterial microleakage may not be affected by the use of the adhesive systems tested in this study.

Bonding to ground versus unground enamel in fluorosed teeth

Objectives To determine the effect of grinding on the bonding effectiveness of a self-etch and an etch-and-rinse adhesive to fluorosed enamel. Methods The teeth were classified using the Thylstrup and Fejerskov index (TFI). Fluorosed teeth (TFI = 5) obtained from Isparta (Turkey) and control teeth (TFI = 0) obtained from Leuven (Belgium) were used. Using a depth-marking diamond bur, 0.3 mm of enamel was removed from mid-buccal and mid-palatal/lingual surfaces of the teeth, whereas the area adjacent to the ground area was left unprepared. A two-step self-etch (Clearfil Protect Bond, Kuraray) and a three-step etch-and-rinse adhesive (Optibond FL, Kerr) were used to bond the resin composite to the ground and unground enamel. Rectangular micro-specimens were prepared using the slow-speed diamond saw and tested in tensile to determine the micro-tensile bond strength (μTBS). Results The μTBS to unground fluorosed enamel was significantly lower than to ground fluorosed enamel for Clearfil Protect Bond (15.8 ± 15.2 and 45.0 ± 12.4 MPa, p < 0.0001) and for Optibond FL (35.5 ± 21.4 and 50.5 ± 12.3 MPa, p < 0.05), respectively. In control teeth, Clearfil Protect Bond bonded better to ground enamel ( p < 0.01), whereas OptiBond FL exhibited a similar bonding effectiveness to ground and unground enamel ( p = 0.0634). Significance Preparation of enamel improved the resin–enamel bond strength in fluorosed teeth. The bonding effectiveness to unground enamel was lower in fluorosed teeth than in control teeth for the self-etch adhesive tested.

Effect of Two Light-emitting Diode (LED) and One Halogen Curing Light on the Microleakage of Class V Flowable Composite Restorations

The disadvantages of light cured composite resin materials with respect to microleakage are predominantly a result of polymerization shrinkage upon curing. It has been shown curing methods play a significant role in polymerization shrinkage of light-cured composite resins. The purpose of this study was to investigate the effect of light-emitting diode (LED) light curing units (LCUs) compared with a halogen LCU on microleakage of three different flowable composites using self-etch adhesives. A total of 63 extracted human premolars were prepared with standardized Class V cavity preparations on the buccal and lingual surfaces of each tooth. The occlusal margin of the cavities was located on the enamel and the gingival margin was on dentin. Teeth were randomly assigned to three groups of 21 teeth each as follows: Group 1: Adper Prompt L-Pop + Filtek Flow (3M ESPE); Group 2: AdheSE + Tetric Flow (Ivoclar, Vivadent); and Group 3: Clearfil Protect Bond + Clearfil Protect Liner F (Kuraray Medical Inc.). All the groups were subdivided into three groups according to the curing lights used (n=7). Two LED LCUs, Elipar FreeLight and Elipar FreeLight 2 (3M ESPE), and one halogen-based LCU, Hilux Expert (Benlioglu ), were used. All teeth were then immersed in 0.5% basic fuchsin dye solution for 24 hours after thermocycling (500 cycles; between 5 degrees C to 55 degrees C). The teeth then were longitudinally sectioned and observed under a stereomicroscope (40X magnification) by two examiners. The degree of dye penetration was recorded separately for enamel and dentin. Data were analyzed with the Kruskal-Wallis and Mann-Whitney tests with the Bonferroni correction. No statistically significant differences in microleakage were observed between groups either on enamel or dentin (p>0.05). With the limitation of this in vitro study, the differences in microleakage between LCUs used were not statistically significantly different. Elipar Free Light 2 reduces curing time which can be considered as an advantage.