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Purpose: By altering either ferric chloride concentration in 10% citric acid (1 % ferric chloride = 10-1; 5 % ferric chloride =10-5; 10 % ferric chloride = 10-10) or conditioning periods with an aqueous mixture of 1% citric acid and 1% ferric chloride (1-1), the influence of dentin substrate on bond strength and hybridized dentin in wet bonding of 4-META/MMA-TBB resin was examined. Materials and Methods: Dentin surfaces of fresh bovine incisors were conditioned either with 10-1, 10-5, or 10-10 mixtures for 10 s (10-1-10s, 10-5-10s, 10-10-10s groups) or with a 1-1 mixture for 5, 10, 30 or 60 s (1-1-5s, 1-1-10s, 1-1-30s, 1-1-60s groups). Rinsed, demineralized dentin samples were kept wet, primed with 5% 4-META in acetone for 60 s, and bonded with 4-META/MMA-TBB resin. Bonded specimens were trimmed to a mini-dumbbell shape for tensile testing. The cross sections of bonded specimens were modified with HCl and NaOCl in order to assess the hybrid layer. The fractured surfaces of specimens and the hybridized dentin were investigated with SEM. Results: No significant difference (p > 0.01) in tensile strength was identified between 10-1-10s and 10-5-10s groups (30 MPa), 10-10-10s and 1-1-5s groups (15 MPa), and the three groups conditioned by 1-1-10s, -30s and -60s (40 MPa). The thickness of the hybrid layer increased with increasing either ferric chloride or conditioning periods. Conclusion: The concentration of ferric chloride in 10% citric acid for wet bonding must be less than 5% in order to provide a reliable bond. When applied from 10 to 60 s, the 1-1 conditioner provided hybridized dentin with reliable tensile bond strength. The thickness of the hybrid layer did not influence the tensile bond strength. [ABSTRACT FROM AUTHOR]

Purpose: The purpose of this study was to determine the marginal discrepancy and retention of silver-palladium crowns cemented with zinc phosphate (Phosphacap) and glass-ionomer cement (Fuji Cap 1) using different seating forces on preparations with various margin designs. Materials and Methods: Crown preparations with three finish lines--chamfer, shoulder, and shoulder with a 45-degree bevel--were sequentially prepared on a dentoform premolar. A metal die for each of the three finish lines was constructed. Complete metal crowns were fabricated for each metal die using a silver palladium alloy. Three different seating forces--25, 100, and 300 N--were used to load the crowns until initial set of the cement. The marginal discrepancy was calculated by measuring the change in crown height before and after cementation using a digimatic indicator. Retention was determined by measuring the tensile strength using the Lloyd universal testing machine. Results: The higher seating forces produced better crown seating but had no significant effect on crown retention. The shoulder and shoulder with bevel finish lines provided better crown retention than the chamfer. Glass-ionomer cement provided greater crown retention than zinc phosphate cement. No significant correlation between marginal seating and crown retention was revealed using a Pearson analysis. Conclusion: Marginal seal was not influenced by either margin design or type of luting cement, but was improved with higher seating force. Crown retention was affected by the margin finish line and the luting agent. [ABSTRACT FROM AUTHOR]

ABSTRACT: The purpose of this study was to evaluate the distance and/or thickness of dye penetration at enamel and cementum/dentin margins of restorations before and after vital bleaching. Class V cavities were prepared on extracted human premolars and restored with light‐cured resin composite using either AQ‐Bond or Single‐Bond2 adhesives. Four conditions: no bleaching (control), restored before bleaching (RB), bleached and immediately restored (BIR), bleached and stored in artificial saliva for 7 days then restored (B7R), were used for each adhesive group. After soaking in basic fuchsin dye for 24 hours, all specimens were vertically sectioned through the middle of restorations to measure the distance and/or the thickness of dye penetration. No microleakage was found either on enamel and cementum/dentin margins of control group using AQ‐Bond. Whereas leakage was found in the control group using Single‐Bond2 and bleached groups. Statistically significant differences in leakage distance and/or thickness were found among groups at the cementum/dentin margin (P < .05). Dye could penetrate into the pulp chamber of BIR (60%) and B7R (15%) specimens. Clinical Significance: The negative control or leakage‐free group is very important when discussing the effects of bleaching on marginal seal or microleakage. Bleaching using 38% H2O2 increases the microleakage distance and dye penetration area of cementum/dentin margin more than that of enamel margin. The bleached tooth is not a good substrate for reliable bonding and complete seal and it is also a channel for external stimuli reaching the pulp. [ABSTRACT FROM AUTHOR]

Purpose: To visualize the complete protection of restored dentin in the acidic environment by the complete impregnation of resin into demineralized dentin. Methods: Class V cavities prepared in extracted human molars composed of enamel, cementum and dentin surfaces were sealed using either 4-META/MMA-TBB resin with conditioning periods of 10, 30, 60 seconds with 10% citric acid and 3% ferric chloride mixed aqueous solution (10-3) or Single-Bond 2 adhesives prior to restoration with light-cured resin-composite. Specimens were either immersed in artificial saliva or 0.1 mol/L buffered lactic acid solutions at 37°C for 14 days. After immersion in 0.5% basic fuchsin dye for 24 hours, the extent of dye penetration at the margin was measured. SEM micrography was used to investigate the quality of hybridized dentin when immersed in HC1 followed by NaOCl solutions. Results: After lactic acid exposure, dye penetration into the adjacent demineralized cementum/dentin was found to be significantly lower than the leakage distance under 30 and 60 seconds and Single-Bond 2 specimens. Leakage-free margins were found in 10-second conditioning period specimens for both control and after soaking in buffered lactic solution with the stable hybridized dentin after chemical challenge. [ABSTRACT FROM AUTHOR]

Purpose: To identify the remaining demineralized dentin (the permeable layer that allows leakage) when using primer-less wet bonding with a total etching period of 10 to 60 seconds compared with contemporary resin adhesives. Methods: Extracted human molars were selected and Class V cavities were prepared on the axial surfaces at the CEJ, providing margins in enamel and dentin for leakage testing using a basic dye (n= 10). Seven groups of conditioned teeth [1-1 etched for 10, 30, and 60 seconds (primer-less wet), All-Bond 2 and Single-Bond 2 (wet), AQ- Bond (self-etched), Super-Bond C&B (dry)J were used as bonding systems for resin composite restoration. All specimens were stored in water at 37°C for 24 hours before soaking in a 0.5% basic fuchsin solution for 24 hours. The distance of dye penetration was measured using stereomicroscopy. Results: No leakage at the enamel- and dentin-resin interfaces was found for all etching periods of 1-1 primer-less, Super-Bond C&B, and AQ-Bond specimens. However, leakage was observed at dentin margins in two wet with primer systems, All-Bond 2 (1.31 ± 1.39 mm) and Single-Bond 2 (0.37 ± 0.28 mm), which required phosphoric etching to remove a weak smear layer on prepared dentin. [ABSTRACT FROM AUTHOR]

Purpose: To evaluate the stability of the interfacial layer and leakage patterns between enamel, DEJ, dentin and three adhesive systems as demonstrated by either a dye or a silver nitrate technique to understand the marginal integrity of restored tooth substrates. Methods: Extracted human molars were cross-sectioned to prepare enamel, DEJ and dentin surfaces. Areas with the DEJ aligned in the middle were restored with prefabricated flat composite blocks using either Superbond C&B (SB), Panavia Fluorocement (PN) or Variolink II (VL) cements. 7 restored specimens for each cement were prepared to investigate the interfacial layer after chemical challenge using SEM. Restored and control specimens for each cement were prepared for leakage tests by soaking either in 0.5% basic fuchsin or 50% silver nitrate solutions for 24 hours (n= 8). The penetration depth of tracer was measured using stereoscopy and a digital micrometer. SEM backscattered electron image and energy dispersive x-ray spectrometry were used to detect the location of the silver. Results: Prepared SB hybridized enamel, dentin and DEJ were stable against soaking in HC1 followed by NaOC1 solutions whereas prepared DEJ- and dentin-resin interfacial layers were degraded, detached and thiimer than that of enamel in VL and PN specimens. No leakage was found at the enamel-resin interface for all cements and at the DEJ- and dentin-resin interfaces for SB specimens. VL specimens showed significantly greater leakage at the interface of dentin and DEJ than did PN specimens. (Am JDent 2010;23:285-291). [ABSTRACT FROM AUTHOR]

Purpose: To evaluate the tensile strength and staining of enamel and dentin after extracoronal or intracoronal bleaching using conventional bleaching agents. Methods: Extracted bovine incisors were divided into eight groups of 10 specimens. Individual groups were treated by extracoronal bleaching (E) using in-office and home techniques with different concentrations of hydrogen peroxide (H2O2) and carbamide peroxide (CP); no bleaching (EN). 35% H2O2 and 10% CP (E35H-10C), 35% H2O2 and 20% CP (E35H-20C), 35% CP and 10% CP (E35C-10C), 35% CP and 20% CP (E35C-20C). Intracoronal "walking bleaching" (I) was performed after 24 hours of root canal treatment in the three remaining groups; no bleaching (IN); sodium perborate dissolved in 35% H2O2 (ISP-35H); and sodium perborate in distilled water (ISP-W). Mini dumbbell shapes of enamel and dentin with central cross-section diameters of 1.5 x 0.5 mm and 3 x 1 mm respectively were prepared for tensile testing using an Instron machine. Fracture surfaces were examined using SEM. Bleached enamel and dentin specimens were stained and evaluated using Caries Detector solution. Staining scores were analyzed using Kruskal-Wallis H and Mann-Whitney test (P< 0.05). Results: Tensile strengths (mean ± SD) of enamel and dentin respectively for each group in MPa were: EN = 30.5 ± 3.3 and 85.4 ± 3.0, E35H-10C = 14.8 ± 2.3 and 58.9 ± 20, E35H-20C=10.6 ± 2.6 and 55.5 ± 2.2. E35C-10C=25.4 ± 3.4 and 70.8 ± 2.5, E35C-20C=20.3 ± 4.1 and 67.2±3.3, IN = 26.5 ± 4.1 and 85.9 ± 2.5. ISP-35H = 13.6 ± 3.1 and 46.7 ± 2.3, ISP-W= 21.7 ± 3.3 and 68.3 ± 4.4. ANOVA and Tukey HSD test found statistically significant differences among and between groups respectively (P< 0.05). No significant difference was found between non-bleached groups (IN and EN) of enamel and dentin. Mean tensile strengths of all bleached groups were significantly lower than those of non-bleached groups. Fracture surfaces demonstrated the different morphologies for bleached and non-bleached enamel and dentin. [ABSTRACT FROM AUTHOR]

This study evaluated the conditions of the non-invasive resin-bonded fixed dental prostheses (FDP) and patient satisfaction up to 10 years of clinical function. A total of 23 patients who required fixed prostheses in the areas of mandibular anterior and premolar, and maxillary anterior region received resin-bonded restorations between 1999-2003. In 13 patients with 14 edentulous areas were restored with an adhesive pontic (natural tooth, acrylic and porcelain). Two indirect proximal veneers using resin composite were placed in each space in 10 patients having 13 edentulous spaces. All prostheses were bonded to the proximal surface of adjacent teeth using resin cement based on 4-META/MMA-TBB. No debonding of proximal veneers but 4 pontic debonding was observed which were rebonded and remained functional until final follow up. The abutments in pontic and proximal veneer groups were free of caries and hypersensitivity. Periodontal health was improved after treatment and was maintained for 10 years except for 4 abutments that still showed some bleeding on probing. Non-invasive resin-bonded FDPs are simple, pain-free, less costly treatment procedures that could provide acceptable clinical longevity with high patient satisfaction.