The Journal of Adhesive Dentistry, 01/2006

Purpose: To assess the enamel-protective potential of a newly devised adhesive patch for smooth enamel sealing. Materials and Methods: Approximal surfaces of 30 extracted molars were divided into three areas: the buccal thirds were treated with a flowable composite (Tetric Flow, Ivoclar Vivadent) and served as negative control sites, the lingual thirds were left untreated and served as positive control sites, and the middle thirds served as the test areas. This was sealed with either 1. a twofold application of an unfilled resin (Heliobond, Ivoclar Vivadent), 2. an adhesive prototype patch (Ivoclar Vivadent), or 3. an adhesive patch in combination with a flowable composite. After thermomechanical loading and demineralization in a microbial-based artificial caries chamber, demineralization depth was assessed using a confocal laser scanning microscope. Results: Negative control sites treated with the flowable composite showed no signs of demineralization. Areas treated with the patch showed no signs of demineralization, irrespective of whether it was used in combination with a flowable composite or directly bonded to the enamel. Caries-like lesions in untreated sites showed a mean depth of 134.3 ± 35.9 µm. Demineralization depth at sites treated with the unfilled resin was 76.2 ± 26.5 µm (p = 0.023). Conclusions: Under the conditions of the present study, the adhesive patch under investigation completely protected the underlying enamel from demineralization. This merits further study to assess its potential as an interproximal sealant. Keywords: caries, adhesive patch, CLSM, Streptococcus mutans, in vitro

Purpose: Few studies have been performed on the cohesive tensile strength of flowable resin composites and hybrids, or on the coupling strength of flowables to hybrid composites. Thus, the purpose of this study was to measure interfacial microtensile bond strengths between hybrid resin composite and flowable resin composite/compomer. Materials and Methods: A polyvinyl siloxane mold was used to fabricate specimens for 9 groups, each consisting of 15 rectangular beams (2 x 2 x 20 mm). Flowable and hybrid resin composites and their paired couplings with each manufacturer's product line were tested. Materials include Heliomolarflow, Revolution, and Dyractflow as representative flowable resin composites and compomer. Heliomolar HB, Prodigy, and Esthet X were selected as representive hybrid resin composites. Resin specimens were cured for a total of 80 s and immersed in water for 7 days. A microspecimen former was used to trim rectangular specimens into specimens with a circular cross section (diameter = 1.0 mm) with a 2 mm gauge length. Specimens were subjected to tensile forces in a passive-gripping space mounted on a Vitrodyne machine. Results: The results are expressed in MPa. Kruskal-Wallis one-way ANOVA on ranks demonstrated significant differences in microtensile bond strength among groups (p 0.001). Conclusion: The cohesive tensile strength of resin composites were material dependent. Flowable and hybrid composites from the same manufacturer have comparable cohesive tensile strengths. The coupling strength of flowable/ hybrid combinations were comparable to cohesive strength of the hybrid composites with the exception of Esthet X/Dyractflow, where the coupling was stronger than the cohesive strength of either resin composite alone. Keywords: cohesive strength of composites, composite coupling strength, SEM evaluation

Purpose: The purpose of this study was to evaluate the effect of different acid etching times with 9.6% hydrofluoric acid gel and two adhesive systems on shear bond strengths of resin composite to porcelain. Materials and Methods: Ninety-eight 7 x 7 x 2 mm feldspathic porcelain blocks (VMK 95, Vita) were prepared. The specimens were divided into 7 groups: 1 control (no surface treatment) and 6 groups acid etched with 9.6% hydrofluoric acid gel for different etching times, including 30 s, 30+30 s, 60 s, 60+60 s, 120 s, and 180 s. Each of the etching time groups was divided into two bonding agent (Single Bond, AdheSE) subgroups (n = 7). Microhybrid composite (Filtek Z250) was condensed using a teflon mold and light polymerized for 20 s on the porcelain specimens. The prepared specimens were then stored in distilled water at 37°C for 24 h before mechanical testing. Shear testing of all groups was performed on a universal testing machine (Lloyd LRX) at a crosshead speed of 0.5 mm/min. The bond strength data were analyzed with two-way ANOVA. The means were compared using the Tukey HSD test (α = 0.05). Results: Acid etching time and bonding agent statistically significantly influenced bond strength (p 0.05). In the Single Bond group, the bond strengths between group 0 (10.48 MPa) and Group 30 (11.17 MPa) did not differ significantly, with these groups exhibiting the lowest bond strength values. The highest bond strength in Single Bond group was observed in group 120 (15.07 MPa) and group 60+60 (15.42 MPa), which did not differ significantly from each other. In the AdheSE group, the bond strengths of group 0 (9.33 MPa) and group 30 (9.49 MPa) did not differ significantly, and these groups exhibited the lowest bond strength values. The highest bond strengths in the AdheSE subgroup were observed in group 120 (14.84 MPa) and group 60+60 (14.96 MPa), which were not significantly different. Comparing the two different adhesive systems, Single Bond exhibited higher bond strength values than did the selfetching adhesive AdheSE. Conclusions: Acid etching of porcelain with 9.6% hydrofluoric acid gel for 120 s provided adequate bond strength for composite repair with a microhybrid composite. When a porcelain restoration is repaired with composite, Single Bond adhesive should be preferred to the AdheSE self-etching adhesive system. Keywords: acid etching time, self-etching adhesive, porcelain, composite resin

Purpose: The aim of this study was to compare the bond strengths of two new self-etching one-step (Prompt L-Pop 2 and Adper Prompt L-pop) to a total-etch three-step dentin bonding system (Scotchbond Multipurpose Plus). Materials and Methods: One hundred twenty human molars were randomly divided into 3 groups of 40 specimens each. Dentin surfaces of each group were bonded with either Scotchbond Multipurpose Plus (SMP), a three-step system, Prompt L-Pop 2 (PLP), or Adper Prompt L-Pop (APLP), two one-step bonding systems - according to manufacturers' recommendations. After adhesive application, a composite resin cylinder was incrementally built in a Teflon mold (5 mm high and 5 mm in diameter). The samples of each group were randomly divided into 2 subgroups of 20 samples each and were tested in a shear bond or in a tensile bond strength mode (crosshead speed 5 mm/min). Statistical analyses were performed with one-way ANOVA and Student's t-test. Results: The significantly lowest shear and tensile bond strength values were obtained with APLP. PLP revealed higher shear bond strengths than APLP and SMP. There were no differences in tensile bond strengths between PLP and SMP (p 0.05). Conclusion: The results of this in vitro study showed that the chemical modifications (adjunction of monomers and copolymers) of the self-etching all-in-one system APLP did not improve its mechanical properties. Keywords: adhesive systems, human dentin, shear bond strength, tensile bond strength

Purpose: To investigate the influence of eugenol-containing temporary cement on bonding of resin composite to dentin mediated by self-etching adhesives. Materials and Methods: Flat dentin surfaces were produced by grinding of extracted human molars. The dentin surfaces were either used directly or after a one-week exposure to a zinc oxide-eugenol cement (IRM). A resin composite (Herculite XRV) was bonded to the dentin surfaces following treatment with 1 of 6 self-etching adhesives (AdheSE, Adper Prompt L-Pop, Clearfil SE Bond, iBond, OptiBond Solo Plus - Self-Etch Adhesive System, and Xeno III). An adhesive system containing 0.5 M EDTA as dentin conditioner (Gluma Classic) was included as negative control, and an etch-and-rinse adhesive system (OptiBond FL) was included as positive control. After storage in water at 37°C for 1 week, the bonded specimens were fractured in shear (n = 8 in each group). Results: Previous contact of dentin with zinc oxide-eugenol cement significantly decreased the bond strength mediated by the negative control and did not affect the bond strength mediated by the positive control. For the self-etching adhesives, no effect was found of previous contact with zinc oxide-eugenol cement. With and without previous contact with zinc oxide-eugenol cement, the etch-and-rinse adhesive system yielded a significantly higher bond strength than all other adhesive systems. Conclusion: Previous contact with zinc oxide-eugenol cement did not decrease the bond strength of resin composite to dentin mediated by self-etching adhesives. This finding suggests that eugenol-containing temporary cements may be safe to use in combination with self-etching adhesives. Keywords: adhesion, bond strength, resin composite

Purpose: Matrices of adhesive restorative materials and repair procedures may both influence bond strength of repaired adhesive materials. This study examined the bond strength of adhesive filling materials to mature adhesive materials after pretreatment with Co-Jet, Monobond S, and Silibond. Materials and Methods: A hybrid composite (Tetric Ceram), a polyacid-modified composite resin (Dyract), and an ormocer (Definite) and their corresponding bonding agents were tested in combination with the repair systems. Restorative materials were placed in molds and polymerized. In group A (control), homologous materials were applied on the polymerized surface directly. In group B, homologous filling materials were placed onto the respective material with the corresponding bonding agent. In group C, adhesive repair filling material was applied after solely pretreating with the repair systems. In group D, the restorative material was applied after pretreatment with the repair systems and application of the corresponding bonding agent. Each subgroup consisted of 20 specimens. The shear bond strength of the samples was measured in a universal testing machine according to the test procedure ISO 10477. Results: The significantly best bond strength of repair filling material on Tetric was achieved by pretreating with Co-Jet followed by application of the corresponding bonding agent (25.5 ± 5.4 MPa, p0.05). A single application of the bonding agent or use of Monobond with bonding agent also yielded bond strengths of 20 MPa or more on Tetric. For Dyract or Definite, bond strengths of 15.5 ± 5.3 MPa or less were achieved with the different repair procedures. Conclusion: Successful pretreatment of hybrid composites for repair can be achieved by application of Co-Jet followed by the corresponding bonding material, whereas sufficient repair of ormocers and polyacid-modified resin composites is limited. Keywords: composite, repair, bond strength

Purpose: The purpose of this study was to evaluate the effects of different light-curing techniques on the microtensile bond strength of hybrid and packable resin composite to dentin. The null hypotheses were that different light-curing techniques do not affect the adhesion of resin composites to tooth structure and that different resin composites do not have a similar bond to dentin. Materials and Methods: One hundred four box-shaped buccal preparations were made and dentin/enamel adhesive was applied according to the manufacturer's instructions (Single Bond 3M ESPE). A hybrid resin composite (Filtek Z250, A2, 3M ESPE) or a packable resin composite (Solitaire 2, A2, Heraeus Kulzer) were inserted in bulk and polymerized using one of these techniques (n = 13): (a) Soft-start (SS) using a halogen lamp (QTH); (b) LED low intensity; (c) Plasma arc (PAC) curing for 6 s for packable resin composite and 3 s for the hybrid resin composite; (d) Conventional (C) QTH curing for 40 s. Afterwards, specimens were thermocycled 1,000 times between 5°C and 55°C in tap water, and were sectioned into beams with a rectangular cross-sectional area of approximately 1 mm2. Microtensile bond strength testing was performed using a universal testing machine at a crosshead speed of 0.5 mm/min. Results: Bond strength means ± (SD) in MPa were: Filtek Z250: SSQTH = 17.9 (5.4); LED = 17.9 (6.4); PAC = 16.8 (6.8); CQTH = 16.1 (4.6). Solitaire 2: SSQTH = 12.4 (6.4); LED = 15.5 (4.3); PAC = 16.2 (4.4); CQTH = 13.8 (5.7). The data were structured in a split-plot design and analyzed by a two-way ANOVA and Tukey's tests (α = 0.05). Conclusion: The light-curing method did not significantly affect bond strengths. However, the bond strengths of the packable resin composite were significantly lower than those of the hybrid resin composite for all polymerization techniques, suggesting that the restorative material itself might be a more critical factor in adhesion than the curing method. Keywords: light curing, resin composite, bond strength

Purpose: This two-centre study evaluated the clinical performance of Class I and Class II restorations of the giomer material Beautifil, placed using Fluorobond, a self-etching adhesive system, to determine the suitability of the test system as an alternative for the restoration of posterior teeth. Materials and Methods: A total of 108 restorations, comprising 72 Class II and 36 Class I restorations, was placed predominantly in molars (82%). Evaulations using modified USPHS/Ryge criteria were conducted at baseline and thereafter at 6 months and 1, 2, and 3 years. Die stone replicas of the restored teeth were examined retrospectively. Results: A total of 5 restorations was found to fail during the study - 3 in the first year and 2 during the third year of the study. Occlusal marginal adaptation was less than ideal at baseline in 11% of cases, primarily as a consequence of overcontouring, as observed in the die stone replicas. The combined percentage Alpha ratings at 3 years were: colour match, 98%; marginal adaptation (occlusal), 78%; marginal adaptation (proximal), 97%; anatomic form (occlusal), 99%; anatomic form (proximal), 95%; surface roughness (occlusal), 100%; surface roughness (proximal), 100%; marginal staining (occlusal), 90%; marginal staining (proximal) 81%; interfacial staining (occlusal), 99%; interfacial staining (proximal), 100%; contacts (occlusal), 95%; contacts (proximal), 93%; sensitivity, 100%; secondary caries, 100%; lustre of restoration, 100%. Conclusion: It is concluded that the 3-year performance of Fluorobond-bonded Beautifil for Class I and II restorations demonstrated some marginal changes, but most of the direct evaluation ratings were > 90% Alpha, with the performance observed being similar in the two centres. Keywords: giomer, self etching adhesive, clinical trial, posterior restoration

Purpose: This study evaluated the postoperative sensitivity of posterior Class I composite resin restorations, restored with a self-etching or a total-etch one-bottle adhesive system. Materials and Methods: One hundred four restorations were replaced by one clinician in 52 patients. Each patient received two restorations. After cavity preparations were completed under rubber-dam isolation, they were restored using Clearfil SE Bond or Single Bond and a resin-based restorative material (Filtek Z250). Sensitivity was evaluated at 0 and 7 days and 6 months using cold stimuli, and recorded using a visual analogue scale. If sensitivity was experienced on day 7, patients were also contacted on days 14 and 30 to assess the degree of sensitivity. The scores were analyzed as nonparametric data by means of the Friedman and Wilcoxon tests. Results: No statistically significant differences in sensitivity were found between the two adhesives systems at days 0 and 7 or at 6 months. No spontaneous postoperative sensitivity was reported. Conclusions: The adhesives systems used in this study showed no differences in postoperative sensitivity, and did not show spontaneous sensitivity after 6 months. Keywords: postoperative sensitivity, adhesive system, composite resin

Adhesively luted all-ceramic inlay-retained fixed partial dentures can be a clinical alternative for the replacement of missing posterior teeth in certain situations. This type of restoration allows satisfactory esthetics and reduced tooth preparation compared to a conventional metal-ceramic fixed restoration. This case report describes the use of an inlay-retained fixed partial denture as a conservative alternative for the replacement of missing posterior teeth. Keywords: missing posterior teeth, all-ceramic, inlay fixed partial denture