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dental materials 26S (2010) e1–e84 e13 Table 1 – Contact angle measured in degrees, collagen matrix expansion expressed as percentage of fully hydrated expanded matrix. Solvent (wt%) 0% 1% 2% 3% 4% 5% Contact angle ( ◦ ) 48± 1.3 a 44 ± 2.1 b 36 ± 2 c 30 ± 1.4 d 29 ± 1.7 d 25 ± 1.9 e Solvent (wt%) 5% 10% a 20% 30% 40% 50% Expansion of dried demineralized dentin 98% ± 2% 92.5% a 84% ± 3% 78% ± 4% 70% ± 3% 66% ± 3% Same superscripts letters indicate no statistically significant difference (p > 0.05). a 10% expansion extrapolated from 5% and 15% results. adhesive and the dentin surface. LVDT results showed that collagen matrix did not expand more fully with the aid of the solvent. The change in contact angle may therefore be a result of improved infiltration into acid etched dentin. Such effect would be beneficial in maximizing monomer permeation into acid-etched dentin during bonding. doi:10.1016/j.dental.2010.08.033 26 The anti-MMP activity of benzalkonium chloride M.M. Mutluay 1 , A. Tezvergil-Mutluay 1 , K.A. Agee 2 , R.M. Carvalho 3 , A. Manso 4 , F.R. Tay 2 , B.-Y. Suh 4 , D.H. Pashley 2 1 University of Turku, Finland 2 Medical College of Georgia, USA 3 University of Sao Paulo, Brazil 4 Bisco Inc., USA Objectives: Matrix metalloproteinases (MMPs) bound to dentin are known to contribute to progressive degradation of collagen fibrils in hybrid layers. Inhibition of host-derived MMPs by quaternary ammonium compounds was shown to slow the degradation. Benzalkonium chloride is a cationic surface-acting agent belonging to the quaternary ammonium group of compounds and widely used for antibacterial properties. This study evaluated the ability of benzalkonium chloride (BAC) to inhibit soluble versus bound dentine matrix metalloproteinases (MMPs). Materials and methods: The inhibitory effects of four different BAC concentrations (0.5–5 wt%) on soluble rhMMP- 2, 8 and 9 were initially screened using a commercially available colorimetric assay kit. Matrix-bound endogenous MMP-activity was evaluated in completely demineralized beams using two different concentrations of BAC (0.5 and 1 wt%). Each beam was either dipped into BAC for 10 or 30 s and then dropped into 1 mL of an complete medium (CM) or alternatively they were placed in either 1 mL of CM containing BAC or only CM for 30 days (control). After 30 days, changes in the dry mass of the beams or in the hydroxyproline (HYP) content of hydrolyzates of the media were quantitated as indirect measures of matrix collagen hydrolysis. The data were analyzed using ANOVA, at ˛ = 0.05. Results: All tested BAC concentrations showed an inhibition of 93–100% and were highly effective (p < 0.05) in inhibiting soluble rhMMP-2, 8 or 9. Matrix-bound MMP model showed similar trend. BAC inhibited matrix-bound MMPs between 55 and 66% when measured as mass loss or 76–81% when measured as solubilization of collagen peptide fragments. ANOVA showed significant effect of BAC compared to control (p < 0.05). Conclusions: BAC is very effective at inhibiting both soluble and matrix-bound dentine MMPs in the absence of resins. Supported, in part, by grants R01 DE015306-06 from the NIH/NIDCR (P.I. DP) and by the Finnish Academy (P.I. ATM). doi:10.1016/j.dental.2010.08.034 27 CHX-containing adhesive inhibits dentin MMPs: A zymographic assay F. Nato 1,2 , A. Mazzoni 2 , P. Gobbi 1 , M. Carrilho 3 , G. Mazzotti 2 , F.R. Tay 4 , D.H. Pashley 4 , L. Breschi 5 1 University of Urbino, Italy 2 University of Bologna, Italy 3 UNIBAN, Brazil 4 Medical College of Georgia, USA 5 University of Trieste, Italy Objectives: Matrix metalloproteases (MMPs) are a family of Zn- and Ca-dependent enzymes involved in several developmental and disease-associated processes. Since these enzymes have been suggested as playing key roles in the degradation of resin–dentin matrices, the use of chlorhexidine (CHX, a non-toxic MMP inhibitor) as additional primer during bonding procedures has been reported to be effective in the preservation of the hybrid layer over time. The purpose of this study was to identify the effectiveness of including CHX within the formulation of a self-etch adhesive system on MMP-2 and -9 activity by means of gelatin zymography. Materials and methods: Dentin powder was pulverized from freshly extracted human molars. Four lots of dentin powder were obtained and randomly assigned to the following treatment group: (1) mineralized dentin + Adper Easy Bond (AEB; 3M ESPE, St Paul, USA); (2) mineralized dentin + 0.2% CHX-containing AEB (experimental adhesive, 3M ESPE); (3) demineralized with 1% aqueous solution of H3PO4 for 10 min; (4) untreated mineralized dentin (control). After rinsing in acetone to remove the uncured adhesive system, protein extracts obtained from the treated dentin powder were then electrophoresed by gelatin zymography, for detection of MMPs enzyme activity.
e14 dental materials 26S (2010) e1–e84 Results: Zymograms of AEB-treated dentin showed MMP- 2 proform (72-kDa) and active form, and a faint band of MMP-9 active form, while zymograms of CHX-containing AEB showed complete inhibition of MMPs activity. Zymograms of demineralized dentin extracts showed MMP-2 and -9 active forms (66 and 86-kDa, respectively). No enzymatic activity was found in proteins extracted from mineralized dentin. Conclusions: Human dentin matrices exhibit collagenolytic and gelatinolytic activity when mixed with AEB, while the incorporation of 0.2% CHX within AEB formulation resulted in complete inhibition of MMP-2 and -9 activity. Further in vitro and in vivo studies are needed to clarify the benefits of incorporation of MMPs inhibitors within the adhesive formulation. doi:10.1016/j.dental.2010.08.035 28 Influence of dentin adhesive on bond strength of selfadhesive cements F. Ozer, M.B. Blatz, A. Atlas, L. Daneshmehr, K. Kashyap, F. Mante University of Pennsylvania, Philadelphia, USA Objectives: The aim of this study was to assess and compare the bonding performance of four new self-adhesive and one resin cement to human dentin with and without application of chlorhexidine 2% and a self-etch adhesive bonding agent. Materials and methods: Occlusal, buccal, lingual, mesial and distal dentin surfaces of 80 human molar teeth were abraded with #600 SiC-paper directly below the enamel. Each test group comprised 5 teeth and 20 dentin sections (4 sections for each surface). Four self-adhesive cements ICem(IC), Clearfil SA Cement (CSA), G-Cem (GC), Bis-Cem (BC) and one resin cement NX3 were applied to the dentinal surfaces in cylindrical-shaped plastic matrices according to the manufacturers’ recommendations with or without application of chlorhexidine 2% and a self-etch adhesive (Protect Bond). GC-Fuji Plus (FP) group was the control. Shear bond strengths were determined at a cross-head speed of 1 mm/min immediately after application of cements to the flat dentinal surfaces. Bond strengths were then calculated and expressed in MPa. Data were analyzed with ANOVA & Tukey’s HSD test. Results: Cement Bond strength (MPa) ± standard deviation groups Intact dentin Protect bond Chlorhexidine CSA 1.5 ± 0.6 ab 8.5 ± 2.0 fgh 0.5 ± 0.7 a IC 4.8 ± 1.7 cde 15.7 ± 5.2 j 3.0 ± 1.9 abcd BC 5.0 ± 2.5 de 12.9 ± 2.7 i 2.3 ± 2.5 abc GC 6.1 ± 1.6 ef 11.2 ± 2.0 hi 3.9 ± 1.6 bcde NX3 0.0 12.2 ± 2.6 i 9.4 ± 2 gh FP 7.9 ± 3.1 fg n/a 6.3 ± 2.2 ef The same superscripts in the table indicate no statistical difference. Protect bond application dramatically increased bond strength values for all resin cements. FP and GC showed highest bond strengths to intact dentin surfaces. Chlorhexidine application decreased bond strengths of study cements. Conclusions: Bond strength values of self-adhesive cements are not reliable without application of an adhesive to dentin surfaces. Application of chlorhexidine 2% to dentin surfaces is not recommended for self-adhesive cements. doi:10.1016/j.dental.2010.08.036 29 Shear-bond strength of a new restorative material to primary dentin E. Pacifici 1 , A. Giovannetti 2 , C. Goracci 1 , A. Vichi 1 ,A. Polimeni 2 , M. Ferrari 1 1 University of Siena, Italy 2 “Sapienza” University of Rome, Italy Objectives: To assess the shear bond strength to deciduous dentin of a new self-adhesive flowable resin composite in comparison with a conventional glass-ionomer cement and with a flowable composite used in combination with the proprietary etch-and-rinse adhesive. Materials and methods: A flat dentin substrate was obtained on the occlusal surface of 40 primary molars by grinding with wet abrasive paper (320 grit). Teeth were randomly divided into 4 groups (n = 10): OFL, phosphoric acid [PA]/optibond flow/premise flow (Kerr); IX, polyacrylic acid/Fuji IX (GC); V, vertise flow (Kerr); PV, PA/vertise flow. The latter group was included in order to assess the contribution to V bonding mechanism of preliminary PA etching. Using rubber moulds of 3 mm in diameter, cylinders of restorative material were built-up over the dentin surface. A shear load (1 mm/min crosshead speed) was applied with a steel blade in a direction parallel to the bonded interface until failure occurred. The failure mode of each specimen was assessed using a stereomicroscope. Bond strength and failure mode data were statistically analysed. As shear bond strength data distribution was not normal, the Kruskall–Wallis analysis of variance was applied followed by the Dunn’s Multiple range test (p < 0.05). Differences in failure mode distribution were assessed with the chi-square test (p < 0.05). Results: With OFL significantly higher bond strengths than in the other groups were recorded. Failures were adhesive in all groups except OFL, in which also cohesive failures in dentin were observed. Shear bond strength (MPa) Failure mode (%) Mean SD Median 25–75% p < 0.05 %Adhesive %Cohesive p < 0.05 OFL 16.02 4.80 17.95 15.48–18.41 A 60% 40% A IX 6.04 3.75 4.86 4.0–6.82 B 100% 0% B PV 4.71 1.87 5.30 3.42–6.22 B 100% 0% B V 4.30 2.66 3.50 3.29–6.27 B 100% 0% B Conclusions: The new self-adhesive flowable composite vertise flow produced on deciduous dentin bond strengths similar to those of a conventional glass ionomer cement that has been routinely used for primary teeth restorations. Preliminary phosphoric acid etching did not significantly change vertise flow bonding potential to primary dentin. The
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