The Journal of Adhesive Dentistry, 01/2010

Purpose: To demonstrate that hydrolytically stable methacrylamide monomers allow one-component self-etching adhesives with comparable adhesive properties and better storage stability than hitherto available methyacrylate-based adhesive formulations. Materials and Methods: The shear bond strength and storage stability of the new one-component self-etching, methacrylamide-based adhesive AdheSE One F (Ivoclar Vivadent) to enamel and dentin was compared to the methacrylate-based Clearfil S3 Bond (Kuraray), G-Bond (GC), Hybrid Bond (Sun Medical), iBond (Heraeus Kulzer), Optibond All In One (Sybron-Kerr), and the methacrylamide-based Xeno V (Dentsply). Hydrolytic stability and adhesive performance of these adhesives was evaluated by accelerated aging at 42°C over 16 weeks and monthly assessment of shear bond strength to dentin. The null hypothesis was that the bond strength of one-bottle self-etching dental adhesives is independent of storage duration and that, disregarding their higher stability against hydrolysis, methacrylamide- based materials offer performance beyond shelf-life time, comparable to methacrylate-based adhesives. Statistical analysis included 1-way-ANOVA and the Tukey-B post-hoc test (p 0.05). Results: Shear bond strengths on enamel ranged from 32.7 MPa (AdheSE One F) to 16.6 MPa (iBond) and on dentin from 36.1 MPa (Optibond All In One) to 20.5 MPa (G-Bond). During accelerated aging, methacrylate-based adhesives with a pH 2 exhibited decreasing bond strengths over time with material-dependent losses of up to 68% (Hybrid Bond, 8 weeks, 42°C). Under the same conditions, the methacrylamide-based formulations AdheSE One F and Xeno V were stable for 16 weeks regarding shear bond strength to dentin. Conclusions: The shelf life of one-component self-etching adhesives is determined by their chemical composition. In conventional methacrylate-based adhesives, the inherently acidic environment of such formulations leads to monomer degradation due to hydrolysis. In contrast, methacrylamide-based adhesives are stable to aqueous acid and exhibit much superior storage stability without monomer degradation-related losses in adhesion performance. Keywords: self-etching adhesive, acrylamide, acidic monomer, degradation, dentin sealing, hydrolytic stability

Purpose: To evaluate the bond strengths of an etch-and-rinse adhesive and a self-etching adhesive to human dentin in vitro and under two in situ conditions: non-anesthetization and anesthetization of the teeth with a local anesthetic containing vasoconstrictor. Materials and Methods: An in situ study was performed on 49 maxillary premolars scheduled for extraction due to orthodontic reasons. For the bond strength test, occlusal cavities were prepared either with or without a local anesthetic containing vasoconstrictor. The cavities were bonded with Adper Single Bond or Clearfil SE Bond and filled with a resin composite, Filtek Z250. The teeth were then extracted, sectioned, trimmed, and tested for microtensile bond strength. For the observation of dentin surfaces, 20 premolars were used. The impressions of the cavity floors in the anesthetized and non-anesthetized groups were taken before and after acid etching. The replicas were observed under a scanning electron microscope. In vitro, the bond strength test and the SEM observation were also carried out on 24 extracted premolars with the same procedures used in the in situ study. Results: The bond strengths of the two adhesives bonded to dentin in situ were significantly lower than those in vitro. When both adhesives were tested under in situ conditions, there were no significant differences between the bond strengths to dentin of anesthetized and non-anesthetized groups (p > 0.05). No fluid droplets were found on dentin on the cavity floor prepared in vitro, either before or after acid-etching. For the unetched dentin prepared in situ, fluid droplets were found and covered on the smear layer in anesthetized and non-anesthetized groups, but the droplets were slightly larger in the non-anesthetized group. In the non-anesthetized, acid-etched group, dentin surfaces were covered with coalescent dentinal fluid in most specimens. However, in the anesthetized, acid-etched group, patent tubules and some dentinal fluid were observed on the surfaces. Conclusion: It was concluded that in situ, dentinal fluid had a detrimental effect on the dentin bond strengths of an etch-and-rinse adhesive and a self-etching adhesive. However, reduction in dentinal fluid due to the effect of a local anesthetic containing vasoconstrictor did not improve the bond strengths in either adhesives. Keywords: local anesthetic, microtensile bond strength, dentin adhesive, in situ experiment

Purpose: This study compared the microshear bond strengths to ground enamel of three one-step self-etching adhesive systems, a self-etching primer system and an etch-and-rinse adhesive system. Materials and Methods: Three self-etching adhesives, Futurabond DC (Voco), Clearfil S Tri Bond (Kuraray) and Hybrid bond (Sun-Medical), a self-etching primer, Clearfil SE Bond (Kuraray), and an etch-and-rinse system, Admira Bond (Voco), were selected. Thirty human molars were used. The root of each tooth was removed and the crown was sectioned into halves. The convex enamel surfaces were reduced by polishing on silicone paper to prepare a flat surface. The bonding systems were applied on this surface. Prior to adhesive curing, a hollow cylinder (2.0 mm height/0.75 mm internal diameter) was placed on the treated surfaces. A resin composite was then inserted into the tube and cured. After water storage for 24 h, the tube was removed and shear bond strength was determined in a universal testing machine at a crosshead speed of 0.5 mm/min. The results were analyzed with ANOVA and the Tukey.-Kramer test at a 59° confidence level. The enamel of five additional teeth was ground, and the etching component of each adhesive was applied and removed with absolute ethanol instead of being light cured. These teeth and selected fractured surfaces were examined by SEM. Results: Adhesion to ground enamel of the Futurabond DC (25 ± 3.5 MPa) and Clearfil SE Bond (23 ± 2.9 MPa) selfetching systems was not significantly different from the etch-and-rinse system Admira Bond (27 ± 2.3 MPa). The two self-etching adhesives Clearfil S Tri bond and Hybrid Bond demonstrated significantly lower bond strengths (14 ± 1.4 MPa; 11 ± 1.9 MPa) with no significant differences between them (p 0.05). Conclusion: Bond strengths to ground enamel of self-etching adhesive systems are dependant on the type of adhesive system. Some of the new adhesive systems showed bond strength values comparable to that of etch-and-rinse systems. There was no correlation between bond strength and morphological changes in enamel. Keywords: bond strength, self-etching adhesives, microshear

Purpose: To investigate whether the application of chlorhexidine in a two-step self-etching adhesive has an adverse effect on the immediate resin-dentin bond strength. Materials and Methods: Different amounts of 20 wt% chlorhexidine digluconate were added directly to the Clearfil SE Bond primer to prepare mixtures of 4 different concentrations of chlorhexidine: 0.05 wt%, 0.1 wt%, 0.5 wt%, and 1.0 wt%. Sixteen extracted third molars were randomly divided into 4 groups. Each group corresponded to one of the 4 chlorhexidine concentrations. Each of the 16 teeth was sectioned into halves. One half was customarily bonded with Clearfil SE Bond without chlorhexidine, and the other half was bonded with Clearfil SE Bond containing different concentrations of chlorhexidine. Microtensile bond strengths were tested immediately after specimen preparation. The modes of fractures were examined under a stereomicroscope. Results: No significant difference of immediate resin-dentin bond strength was observed between the control groups and any of the experimental groups containing chlorhexidine (p > 0.05). Conclusion: The addition of chlorhexidine to a two-step self-etching adhesive primer (Clearfil SE Bond primer) has no adverse effect on the immediate resin-dentin bond strength when the chlorhexidine concentration in the primer is lower than or equal to 1.0 wt%. Keywords: chlorhexidine, bond degradation, matrix metalloproteinases, self-etching adhesives, microtensile bond test

Purpose: This study was designed to compare the self-etching with the etch-and-rinse adhesives regarding the degree of conversion and antimicrobial activity against cariogenic bacteria. Materials and Methods: The materials used were AdheSE (two-step self-etching), Adper Prompt L-Pop (self-etching, single-step) and Excite (etch-and-rinse) adhesives. The degree of conversion was measured using Fourier Transformation Infrared Spectroscopy. The absorbance peaks of infrared rays by the aliphatic C=C was detected at 1632 to 1637cm-1 and the aromatic C=C peak at 1610 to 1500 cm-1.The antimicrobial activity was evaluated using the microorganisms Streptococcus mutans, Lactobacillus salivarius, and Actinomyces odontolyticus, with a disk diffusion method. Chlorhexidine digluconate solution 0.2% was used as a positive control. Zones of inhibited bacterial growth were observed and measured. Results: AdheSE showed the highest degree of conversion, followed by Excite, while Adper Prompt L-Pop had the lowest values. A significant difference in the degree of conversion was found between Excite and Adper Prompt L-Pop as well as AdheSE and Adper Prompt L-Pop. On the other hand, there was no significant difference between Excite and AdheSE. Adper Prompt L-Pop showed an antimicrobial effect against Streptococcus mutans and Actinomyces odontolyticus while it was unable to inhibit the growth of Lactobacillus salivarius. AdheSE could inhibit the growth of Streptococcus mutans only. Excite did not produce inhibition zones to the tested microorganisms. Conclusion: Adper Prompt L-Pop showed the worst degree of conversion. AdheSE and Excite had the highest degree of conversion. Appreciable antimicrobial activity was noted with self-etching adhesives, while the etch-and-rinse demonstrated no antimicrobial action. Keywords: etch-and-rinse, self-etching, degree of conversion, antimicrobial action, two-step adhesive, single-step adhesive

Purpose: To evaluate and compare the water sorption and water solubility of four self-etching, self-adhesive resin luting agents. Materials and Methods: Four self-etching, self-adhesive resin luting agents (RelyX Unicem, Maxcem, Biscem, Multilink Sprint) and one classic resin luting agent (Multilink Automix) as a control group were used. Twelve disks (8 mm x 1 mm) of each material were prepared according to ISO 4049. Water sorption and solubility were calculated, using the formulae which the ISO 4049 specification provides. Results: Maxcem and Biscem were found to have very high water sorption values. RelyX Unicem and Multilink Sprint exhibited water sorption values only slightly higher than the control group. Regarding water solubility, the greater mass loss was found for Maxcem. Multilink Sprint exhibited no mass change. Biscem was found to have low solubility values, whereas RelyX Unicem and Multilink Automix exhibited negative solubility. Conclusion: Multilink Sprint and RelyX Unicem were found to comply with the ISO requirements regarding water sorption and solubility, while Maxcem and Biscem did not. Materials of the same group exhibited very different behavior during their interaction with water. Keywords: resin luting agents, self-etching, self-adhesive resin luting agents, water sorption, water solubility, dual-set materials

Purpose: The aim was to determine the in vitro fracture resistance of incisors restored with veneers and full ceramic crowns compared to unrestored teeth. Materials and Methods: Seventy intact, extracted human maxillary central incisors were randomized and assigned to 7 groups (n = 10). The teeth in group 1 remained intact (control). The teeth in groups 2 to 6 were prepared and IPS Empress restorations were conditioned and bonded using an adhesive luting cement, Variolink II/Syntac (group 2: labial veneer with incisal overlap, group 3: 3/4 veneer with margin in enamel, group 4: 3/4 veneer with margin in dentin, group 5: crown with margin in enamel, group 6: crown with margin in dentin group 7: veneer on worn tooth. After finishing and polishing, specimens were stored in water and thermocycled for 2000 cycles between 5°C and 55°C. The maximal fracture load of the specimens (40-degree inclination) was determined using the universal testing machine (Zwick) at a constant crosshead speed (0.5 mm/min). The statistical analysis was performed using the Kruskal-Wallis test with Bonferroni correction (p 0.05). Fracture surfaces were qualitatively analyzed by SEM. Results: All restored teeth with cervical preparation margins in enamel showed a fracture load not significantly different from the intact teeth (control). Restored teeth with cervical preparation margins in dentin showed a significantly lower fracture load. All restorations showed a fracture load far above 400 N, serving as functional reference for anterior teeth. The failures were predominantly cohesive. Conclusion: For the restoration of tooth strength, defining the finishing lines of veneers and crowns in enamel is recommended. Restorations with finishing lines in dentin resulted in significant loss of strength. Three-quarter veneers with finishing lines in enamel are functionally equal to crowns with the advantage of conserving tooth structure. Keywords: dental material, ceramic veneer, full ceramic crowns, adhesion, adhesive luting, fracture load

Purpose: To determine whether two-step cementation of prefabricated fiber posts leads to higher bond strengths. Materials and Methods: Forty-eight human canine teeth were divided into six groups and fiber posts were cemented with DC Core, RelyX Unicem and Panavia F2.0, according to a one-step or two-step procedure. Per root, four cross-sections were prepared. The differences in push-out strength between procedure, cement and location within the root were determined. Results: For all cements, the push-out strengths for the two-step procedure were significantly higher than for the onestep procedure (p 0.001). Differences between the cements for both the one-step and two-step procedure were not statistically significant (p = 0.05). Conclusion: The reduction of the C-factor by means of a two-step cementation, a procedure equivalent to the layering technique of composite restorations, resulted in significantly higher bond strengths. The increase of 60% in bond strength may be beneficial to the retention of post and core restorations. Keywords: prefabricated fiber post, cementation procedure, C-factor, push-out strength, polymerization shrinkage

Purpose: To evaluate the effect of 6 irrigant regimens on the microshear bond strength of different adhesives to pulp chamber dentin and to determine their interfacial morphology by SEM. Materials and Methods: Forty-three human molars were split into halves and ground to provide flat pulp chamber dentin. Eighty-five halves were used. The specimens were assigned to 6 groups according to the irrigant regimen used. Group I (n=10) was irrigated with distilled water (control). The remaining 5 groups (n=15 each) were irrigated with 5.25% NaOCl followed by either 5.25% NaOCl, 17% EDTA, benzalkonium chloride (Tubilcid Plus) or MTAD (Biopure), either rinsed or not. Irrigated specimens were bonded using Clearfil S3 Bond or Adper Single Bond 2, which was employed with or without etching. Resin composite cylinders were bonded using tygon tubes for microshear bond strength testing. Data were analyzed using two-way ANOVA followed by Tukey's post-hoc test. Representative specimens of each group were prepared from 17 further mmolars for interfacial SEM examination. Results: The different irrigant regimens used did not significantly alter the microshear bond strength values using either of the bonding systems, except NaOCl, which significantly reduced the microshear bond strength values with Adper Single Bond 2. Bonding irrigated specimens directly using the Adper Single Bond 2 without prior etching provided significantly reduced values. Conclusion: The irrigant regimens examined could be used safely prior to bonding except for the NaOCl, which should be negated if it is to be followed by Adper Single Bond 2, and the etching step cannot be omitted if an etch-and-rinse adhesive system is the adhesive of choice. Keywords: pulp chamber dentin, irrigants, microshear bond strength, etch-and-rinse adhesive, self-etching adhesive, SEM

The loss of anterior teeth due to trauma requires immediate attention for function and esthetics. While implant- supported or conventional fixed prostheses may be the treatments of choice for adults, relatively noninvasive and reversible provisional procedures for tooth replacement are necessary for adolescents. In recent years, developments in fiber and composite technology offer a conservative treatment approach to restore the anterior edentulous space as a fixed provisional tooth replacement. This case report presents the chairside procedures of anterior tooth replacement in an adolescent using the avulsed tooth crowns as pontics which were bonded to teeth on either side of the edentulous space and reinforced with a preimpregnated fiber. Keywords: avulsion, chairside tooth replacement, preimpregnated fiber