Effects of dentine moisture on the permeability of total-etch and one-step self-etch adhesives.

OBJECTIVES: The aim of this study was to compare the technique sensitivity of a one-bottle total-etch adhesive and a self-etch primer adhesive to the moisture condition of the dentine substrate. METHODS: The methods used were hydraulic conductance, light microscopy and scanning electron microscopy. RESULTS: When the moisture conditions of the dentine surface are modified with respect to the standard, the bonded interfaces obtained with the one-bottle total-etch Adper Scotch Bond 1 XT (SB) and the all-in-one self-etch Adper Prompt L-Pop (AP) are morphologically highly perturbed. But, although this study also showed a significant (p<0.01) relationship between increases in permeability of resin-bonded dentine and variations of dentine moisture conditions with SB, a significant relationship was found only for the influence of the over-wet condition with AP. CONCLUSION: Within the limitations of this study, the self-etch primer tested gave a greater reduction in dentine permeability than the one-bottle adhesive, while being more tolerant to handling. Although excess water should be avoided with both these systems, air-drying can be an alternative to wet-bonding with the self-etch primers, thus reducing the sensitivity to technique.

Effect of self-etching adhesives on dentin permeability in a fluid flow model.

STATEMENT OF PROBLEM: Numerous self-etching bonding systems exist, with composition differing from one product to another. It is important for the clinician to know if they are all equally effective, and whether they provide an effective seal between dentin and restorative materials. PURPOSE: This study was designed to measure the hydraulic conductance of physiologic saline across dentin after application of various self-etching bonding systems or of a 1-bottle adhesive system preceded by a phosphoric acid etch. MATERIAL AND METHODS: One hundred extracted noncarious human third molars from patients 18-25 years old were used for this study. Dentin disks were cut from crown segments parallel to the occlusal surface at the top of the pulp cavity. The 100 disks, each 1 mm thick, were divided into 10 groups (n=10 per group), each of which was treated with 1 of 9 self-etching systems-AdheSE, Adper Prompt L-Pop, Clearfil SE Bond, Etch & Prime 3.0, Prime & Bond NRC Nt, One-Up Bond F, optiBond solo Plus Self Etch, Prompt L-Pop, or Xeno III-or a control bonding system (Prime & Bond NT) preceded by a phosphoric acid etch. Hydraulic conductance, the volume of fluid transported across a known area of surface (0.28 cm2) per unit time under a unit pressure gradient (200 cm H2O), was analyzed for the adhesive systems using a fluid flow apparatus (Flodec). First, both sides of each specimen were etched with 36% phosphoric acid for 30 seconds, and the hydraulic conductance was measured every 30 seconds for 15 minutes. The initial set of measurements served as the reference value for each specimen. The measurements were repeated when a smear layer had been formed and, finally, after 1 of the 10 bonding systems had been applied. The data were analyzed using a 1-way ANOVA and Duncan's multiple range test (alpha=.05). RESULTS: The control 1-bottle adhesive used with a phosphoric acid pre-etch did not provide the largest reduction in penetration (42.3%). The greatest mean reduction (68.9%, P<.05) was observed with the self-etching product Xeno III. The mean reduction for the other materials tested were: One-Up Bond F, 60.5%; AdheSE, 58.2%; Etch & Prime 3.0, 56.8%; Adper Prompt L-Pop, 51%; optiBond solo Plus Self Etch, 45%; Clearfil SE Bond, 35.5%, Prime & Bond NRC Nt, 16.4%; and Prompt L-Pop, 16.3%. CONCLUSION: Within the limitations of this study, the self-etching systems tested produced different reductions in dentin permeability. For some, the reduction was much greater than the decrease in dentin permeability provided by the bonding system with a phosphoric acid pre-etch; for others, the reduction was small.

Dentin permeability: self-etching and one-bottle dentin bonding systems.

STATEMENT OF PROBLEM: There are many bonding systems available, with or without a prior acid etch. The mechanisms differ from system to system. Therefore it is important that the clinician know which are the most effective and which provide the best seal. PURPOSE: This study measured the infiltration of physiological saline solution across dentin after application of self-etching or 1-bottle dentin bonding systems. MATERIALS AND METHODS: Thirty-six extracted noncarious human third molars from patients 18 to 25 years old were used for this study. Dentin disks were cut from crown segments parallel to the occlusal surface at the incisal portion of the pulp cavity. The 36 disks, each 1 mm thick, were divided into 6 groups (n=6 per group), each of which received one of the following dentin bonding systems: Optibond Solo Plus and Excite, which have ethanol as the solvent; Prime & Bond NT, which has acetone as the solvent; Single Bond, which has a mixed solvent; and Clearfil SE Bond or Prompt L-Pop, both self-etching systems The hydraulic conductance, the volume of fluid transported across a known area of surface (0.28 cm(2)) per unit time under a unit pressure gradient (200 cm H(2)O), was analyzed for the self-etching and 1-bottle dentin bonding systems with the Flodec apparatus. Both sides of each specimen were etched with 36% phosphoric acid for 30 seconds. Measurements were made every 30 seconds for 15 minutes. The initial measurement served as the reference value for each specimen. The measurements were repeated when a smear layer had been formed and, finally, after one of the 6 bonding systems had been applied. The data were analyzed by use of analysis of variance and a posteriori tests (Fischer's PLSD, Duncan's new multiple range) with alpha=.05. RESULTS: The greatest mean reduction (40%, P<.05) in penetration was observed with the 4 products with conventional etching: Optibond Solo Plus, Single Bond, Excite, and Prime & Bond NT. The self-etching products were associated with reductions of 36% (Clearfil SE Bond) and 16% (Prompt L Pop). Standard deviations were high, 50% of the mean value, except for the Single Bond group (-42 +/- 13) and Prime & Bond NT (-41 +/- 14). CONCLUSION: Within the limitations of this study, the 4 bonding systems tested with a phosphoric acid before etching provided a greater decrease in dentin permeability than the 2 self-etching systems. The difference in permeability decrease was significant for Prompt L-Pop but not for Clearfil SE Bond.