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PubMed2003

Self-etching bonding agents.

Efforts to bond resins to dentin have been underway for many years. Early attempts focused on bonding resins either to the collagenous structure or to the inorganic component. While considerable progress was achieved during the first 20 years, success was finally achieved by using a different approach. Specifically, Nakabayashi conditioned dentin with an acid, resulting in a superficial demineralization of dentin. A low-viscosity monomer was then diffused into the evacuated spaces, thereby replacing the inorganic phase. This current technique, rather than bonding chemically to the dentin, is based on microretention. The resulting bond strength approaches the inherent strength of dentin itself.

Acid Etching, Dental↗
PubMedDate not supplied

Effect of dentinal tubule orientation on the microtensile bond strength to primary dentin.

Direction of dentin tubules is an important factor that affects bond strength of contemporary adhesive materials. Because conservative proximal cavity preparations in primary teeth contain more dentin tubules running oblique or parallel to the cavity walls, this study was conducted to evaluate the influence of tubule orientation on the bond strength to primary dentin. A polyacid-modified resin composite material was used as the test material. A microtensile test was utilized to enable evaluation of bond strengths in three different tubule orientations (perpendicular, oblique, parallel) following aging of the resindentin bonds by long-term immersion of the test samples in water. Samples bonded parallel to the dentin tubules showed the highest microtensile bond strength, followed by the oblique and perpendicular groups. Statistical analysis of the data showed no significant difference between the bond strength of parallel and oblique groups. Independent of the tubule orientation, all samples revealed cohesive fracture within dentin.

Analysis of Variance↗
PubMedDate not supplied

Radiopacity of direct esthetic restorative materials.

This study determined the radiopacity of 21 commercially available direct esthetic restorative materials with reference to an aluminum step wedge and an equivalent thickness of enamel and dentin. A total of 168 samples measuring 6 mm in diameter and 1 mm in thickness, with eight samples of each material, were prepared from restorative materials. Enamel and dentin samples 1-mm thick were also prepared by longitudinally sectioning eight extracted human permanent molars using a microslicing machine. The optical densities of each restorative material, along with one tooth section and an aluminum step wedge were measured from radiographic images using a transmission photodensitometer. The optical density values of the specimens were used to determine the aluminum thickness equivalent values. The data were analyzed with one-way analysis of variance (ANOVA) and Duncan's multiple range tests. The results showed statistically significant differences among materials. Tetric Ceram had the greatest radiopacity value and was higher than enamel. All materials except for the microfilled resin composite Filtek A 110 had radiopacity values greater than dentin and possessed sufficient radiopacity to meet ISO 4049 standard. Significant differences were found among materials of the same composition when compared to enamel.

Analysis of Variance↗
PubMedDate not supplied

Effect of food-simulating liquids on the shear punch strength of composite and polyacid-modified composite restoratives.

This study evaluated the effects of food-simulating liquids on the shear punch strength of two composites (Tetric Ceram [TC], Vivadent; Esthet X [EX], Dentsply), a conventional (Compoglass [CG], Vivadent) and a posterior polyacid-modified (Dyract Posterior [DP], Dentsply) composite. Thirty-two specimens (10-mm in diameter and 1.6-mm thick) of each material were made, randomly divided into four groups of eight and conditioned for one week as follows--Group 1 (control): air at 37 degrees C; Group 2: distilled water at 37 degrees C; Group 3: 75% ethanol-water solution at 37 degrees C and Group 4: heptane at 37 degrees C. After conditioning, the specimens were restrained within the test apparatus and subjected to shear punch strength testing using a 3.2 mm diameter punch at a crosshead speed of 0.5 mm/minute. The shear punch strength of the specimens was computed and the data was subjected to ANOVA/Scheffe's tests at significance level 0.05. The effect of food-simulating liquids on shear strength was found to be material dependent. All materials with the exception of EX were significantly weakened by ethanol solution. For DP, a significant increase in strength was observed after conditioning in water. EX was significantly stronger than TC and DY after conditioning in air, water and ethanol solution. The shear punch strength of EX and CG was significantly higher than DY after conditioning in heptane.

Analysis of Variance↗
PubMedDate not supplied

Effect of home-use bleaching gels on fluoride releasing restorative materials.

To evaluate the effects of two home-use bleaching gels (Nite-White and Contrast PM) on the surface roughness of one high-viscosity glass ionomer cement (Fuji IX GP), four polyacid-modified resin-based composites (Dyract AP, F2000, Elan and Compoglass F), two resin-modified glass-ionomer cements (Vitremer and Fuji II LC), a microfilled fluoride-releasing resin-based composite (Tetric) and a microfilled non-fluoridated resin-based composite (Valux) were used as controls. The null hypotheses tested were: (1) the use of bleaching gels would not result in surface roughness values different from those obtained at baseline; (2) differences in the amount of carbamide peroxide present in the gels would not influence surface roughness. Thirty specimen disks (the first 10 used for controls and the balance divided randomly into two groups) were made for each material according to the manufacturers' instructions. Finishing and polishing of the test and control specimens was performed after 24 hours using a sequential series of three (medium, fine and superfine) Sof-Lex disks, keeping the restoration surface wet. For every sequence, 10 strokes were made in one direction using a low-speed handpiece. Ultrasonic cleaning of the polished specimens was performed for two minutes in distilled water to remove any surface debris. Prior to bleaching treatment, the specimens were stored in 37 degrees C deionized water for 24 hours. The specimens were exposed to the bleaching gels for a period that simulated the equivalent of 15 days (eight hours/day) under bleaching treatment. The average surface roughness (Ra) of the control and treated specimens was measured. Three separate Ra measurements along the direction of rotation of the finishing and perpendicular to the finishing direction and edge of the mold were made for each specimen surface. After treatment with bleaching gels, there was an increase in surface roughness for F2000, Dyract AP, Elan, Valux and Tetric, while Fuji IX, Fuji II LC, Vitremer and Compoglass F displayed decreased surface roughness values, suggesting that the effects of the gels appear to be material-dependent. Although Contrast PM contains 5% more carbamide peroxide as the active ingredient, the second null hypothesis was rejected for Fuji IX, Vitremer, Dyract AP, Compoglass F, Elan and Valux.

Carbamide Peroxide↗
PubMedDate not supplied

In vitro evaluation of the marginal seal of four restoration materials on deciduous molars.

The aim of this study was to compare the marginal microleakage of Fuji II LC (A), composite resin Z250 (B), Fuji IX GP (C), and Dyract AP (F) in class V cavities and at the Fuji II LC/Z250 (D) and Fuji IX GP/composite resin Z250 (E) interfaces of an open sandwich technique on deciduous teeth. After thermocycling the mean marginal dye penetration at the enamel junction was 21.6 microns +/- 14.2 for group A; 83.6 microns +/- 32.3 for group B; 7.5 microns +/- 7.5 for group C; 38.7 microns +/- 27.5 for group D, and 0 micron for groups E and F. Mean dye penetration at the cementum junction was 37.1 +/- 20.2 (A); 123 +/- 42.1 (B); 28.7 +/- 17.1 (C); 0 (D); 14.4 +/- 14.4 (E); and 0 (F) microns. No leakage was seen at the junction between Fuji II LC and Z250 (0 micron), whereas a mean leakage of 184 microns between Fuji IX and Z250 was measured. In enamel the best seal was obtained with Dyract AP, but with differences at the limit of significance (P = 0.07). Sealing was significantly worse with Z250 (p = 0.03 versus Fuji II LC; p = 0.006 versus Fuji IX GP; and p = 0.003 versus Dyract AP). In cementum, the comparison between the grouped data Z250-Fuji II LC versus Fuji IX GP-Dyract AP was highly significant (p < 0.001), while there was no detectable difference between Z250 and Fuji II LC.

Coloring Agents↗
PubMedDate not supplied

Incompatibility of self-etch adhesives with chemical/dual-cured composites: two-step vs one-step systems.

This study tested the null hypothesis that there no difference between two-step and one-step self-etch adhesives in their compatibility with these composites. The microtensile bond strengths (microTBS) of two two-step systems (Clearfil SE Bond, Kuraray and Tyrian SPE/One-Step Plus, BISCO) were compared with two one-step systems (Xeno III, Dentsply DeTrey and Brush&Bond, Parkell) for their coupling to a dual-cured composite. Silver tracer penetration of the four adhesives bonded to a light-cured or a chemical-cured composite was examined using TEM. Significant differences in microTBSs between composite curing modes were seen only in the one-step adhesives. For one-step self-etch adhesives bonded to the chemical-cured composite, TEM revealed signs of frank composite uncoupling along the adhesive-composite interface, which may be attributed to the adverse chemical interaction between the acidic adhesive and the composite. In addition, "water trees" that represent channels of increased permeability with the polymerized adhesive layer were also observed in the one-step adhesives. Both features were absent along the resin-dentin interfaces when chemical-cured composites were coupled to the two-step self-etch adhesives.

Adhesiveness↗
PubMedDate not supplied

Initial in situ secondary caries formation: effect of various fluoride-containing restorative materials.

This study evaluated the effects of various restorative materials (Ariston pHc; Dyract; Vitremer; Tetric Ceram; Compoglass F, F2000; Hytac and Ketac Molar) on initial secondary caries formation in situ. Eighty-eight enamel slabs from sound human molars were sterilized (ethylene dioxide) and embedded in epoxy resin. Standardized tooth preparations were filled with the various restorative materials according to manufacturers' recommendations. One specimen from each group was inserted into one of two buccal aspects of an intraoral appliance worn by 11 volunteers for four weeks, day and night. Oral hygiene was performed without additional fluoride application. During meals and oral hygiene procedures, the appliances were stored in sucrose solution (10%). After in situ exposure, the samples were prepared for microradiographic assessment. Mineral content and lesion depth were evaluated by a dedicated software package (TMR 1.24). Lesion depth and mineral loss of the carious lesions close to Ariston pHc was significantly lower when compared to distant parts of the same lesions (p < 0.05; t-test, Bonferroni-Holm correction). All other materials containing fluoride showed no caries protective effect on surrounding enamel (p > 0.05; t-test, Bonferroni-Holm correction). A hydroxyl-, calcium- and fluoride-containing restorative material hampers demineralization next to the restoration, whereas, fluoride release of various fluoride-containing restorative materials does not affect demineralization of adjacent enamel in situ.

Adult↗
PubMedDate not supplied

Influence of different repair procedures on bond strength of adhesive filling materials to etched enamel in vitro.

Contamination of etched enamel with repair bond agents during repair of dental restorations may interfere with the bonding of composite to enamel. This study examined the bond strength of adhesive filling materials to etched bovine enamel after pre-treatment with the repair systems Monobond S, Silibond and Co-Jet. The materials Tetric Ceram, Dyract and Definite and their corresponding bonding agents (Syntac Single Comp, Prime & Bond NT, Etch and Prime) were tested in combination with the repair systems. One hundred and thirty-five enamel specimens were etched (37% phosphoric acid, 60 seconds) and equally distributed among three groups (A-C). In Group A, the repair materials were applied on etched enamel followed by applying the composite materials without using their respective bonding material. In Group B, the composite materials were placed on etched enamel after applying the repair materials and bonding agents. In control Group C, the composite materials and bonding agents were applied on etched enamel without using the repair systems. In each sub-group, every composite material was applied on 15 specimens. Samples were stored in artificial saliva for 14 days and thermocycled 1,000 times (5 degrees C/55 degrees C). The shear bond strength of the samples were then determined in a universal testing machine (ISO 10477). Applying Monobond or Silibond followed by the use of its respective bonding agents resulted in a bond strength that was not statistically different from the controls for all filling materials (Group C). The three composites that used Monobond and Silibond without applying the corresponding bonding agent resulted in bond strengths that were significantly lower than the controls. Utilizing the Co-Jet-System drastically reduced the bond strength of composites on etched enamel. Contamination of etched enamel with the repairing bonding agents Monobond and Silibond does not interfere with bond strength if the application of Monobond and Silibond is followed by using its corresponding bonding system of the composites tested.

Acid Etching, Dental↗
PubMed2003

Bond strengths of polyacid-modified resin composites and a resin-modified glass-ionomer cement to primary dentin.

PURPOSE: To evaluate the bond strengths of three polyacid-modified resin composites and one resin-modified glass-ionomer cement to caries-simulated primary dentin after 18-months' water immersion. METHODS: Dyract AP, Compoglass F, F2000 and Vitremer were used as test materials. Standardized preparations cavities with a C-factor of 5 were prepared in primary molars. Half of the cavities were stored in a demineralizing media for 7 days to simulate caries-affected dentin. Thereafter, all preparations were restored with the test materials, after which the specimens were stored in water for 18 months, changing the water every week. The specimens were subjected to a microtensile test and all bond strength data (in MPa) were statistically analyzed using one-way analysis of variance (ANOVA) and Tukey HSD tests at P < 0.01. RESULTS: The mean microtensile bond strength to normal primary dentin specimens were 11.2 +/- 1.5 (Dyract AP), 10.6 +/- 2.1 (Compoglass F), 10.8 +/- 1.1 (F2000) and 7.3 +/- 1.6 (Vitremer), while those to the caries-simulated dentin were 4.1 +/- 0.7 (Dyract AP), 3.0 +/- 0.6 (Compoglass F), 2.3 +/- 0.9 (F2000) and 1.9 +/- 0.5 (Vitremer). SEM evaluation of the unfractured specimens revealed evidence of gap formation in the adhesive interface in all samples.

Analysis of Variance↗
PubMed2003

Ultra-morphology of self-etching adhesives on ground enamel: a high resolution SEM study.

PURPOSE: To evaluate the effect of different commercial self-etching agents on enamel morphology using high-resolution in-lens scanning electron microscopy (FEISEM). METHODS: The bonding systems selected for the study were: Prime & Bond NT (no-etch technique), Prime & Bond 2.1 (no-etch technique), NRC/Prime and Bond NT, Syntac Single Component, Prompt L-Pop, F2000, and Clearfil SE Bond. The positive control group was prepared with Single Bond upon etching enamel with the proprietary 35% phosphoric acid gel. 24 extracted human molars were equally and randomly assigned to the experimental and control groups. All bonding materials were applied on enamel following the manufacturers' instructions. A thin layer of composite was applied on the polymerized adhesive agent, after which the enamel was dissolved to obtain replicas that were observed under a FEISEM. RESULTS: Observations revealed different morphological features brought about by the adhesive systems. A relationship between the morphological appearance and the pH of the adhesive solutions was found. Three different groups of self etching were identified: Group 1 showed no or little evidence of modifications on the enamel surface (Prime & Bond NT and Prime & Bond 2.1, no-etch technique), Group 2 revealed major aggressive properties that were able to disclose the prism morphology (Syntac Single Component, F2000, Clearfil SE Bond), and Group 3 (NRC/Prime & Bond NT and Prompt L-Pop) revealed morphological features similar to those obtained with Single Bond after etching with phosphoric acid (control group).

Acetone↗
PubMed2003

Enamel demineralization inhibition by cements at orthodontic band margins.

PURPOSE: To examine the demineralization inhibition effects of glass ionomer cement and polyacid-modified resin-based composite cement, in comparison to non-fluoride releasing zinc phosphate cement. METHODS: Twenty-seven extracted molars were obtained and randomly assigned to three groups. An orthodontic band was sized and cemented using one of three cements. The teeth were painted with an acid-protective varnish, excluding a 1 mm area gingival to the orthodontic band. The teeth were placed in separate closed environments of a non-fluoridated acid challenge to induce demineralization for 5 days. The teeth were then sectioned two times buccolingually and two times mesiodistally. The sections were photographed with polarized light microscopy in an imbition media of water. The body of each lesion was measured with a computerized imaging system. The areas of the lesions, from each cement group, were compared. RESULTS: An analysis of variance (ANOVA) indicated significance in variance among groups (P < 0.001). Results of a multiple comparison analysis demonstrated significantly less demineralization adjacent to the glass ionomer cement group compared with the polyacid-modified resin cement group and non-fluoride releasing zinc phosphate control group (P < 0.05). There was no significant difference in adjacent demineralization inhibition between the zinc phosphate cement group and polyacid-modified resin cement group (P < 0.05).

Analysis of Variance↗
PubMed2003

Comparison of the effect of topical fluorides on the commercially available conventional glass ionomers, resin modified glass ionomers and polyacid modified composite resins--an in vitro study.

This study was undertaken to assess the effect of a single application of three professionally applied topical fluoride agents (Sodium fluoride 2%, Stannous fluoride 8% and APF 1.23%) on the surfaces of six modern esthetic restorative materials used in pediatric dentistry viz., two conventional glass ionomers (Fuji II and Shofu-restorative), two resin modified glass ionomers (Vitremer, with and without glaze, and Photac-fil Quick) and two Polyacid modified composite resins (Luxat and Hytac Aplitip). Mean surface roughness and surface micro hardness (SMH) measurements were the parameters employed for comparison. Results showed that APF gel applications significantly increased the surface roughness measurements and decreased SMH of all tested materials, which was pronounced in conventional glass ionomers when compared with resin modified glass ionomers and polyacid modified composite resins. NaF and SnF2 produced a statistically significant increase in the surface roughness of conventional glass ionomers without any significant change in surface roughness and SMH on rest of the materials tested, except for NaF on SMH values of Fuji II, which was statistically significant.

Acidulated Phosphate Fluoride↗
PubMed2003

[Review of poly(vinyl alcohol) hydrogel and its compounds in the application of artificial cartilage materials].

Poly(vinyl alcohol) (PVA) hydrogel is a kind of material which has excellent biocompatibility and mechanical properties. In this paper, the researches and developments of PVA hydrogel preparation and the modifications of PVA with other material were introduced. The potential for the use of PVA hydrogels as implant materials in cartilage reparation was reviewed.

Biocompatible Materials↗
PubMedDate not supplied

Simultaneous release of fluoride and aluminum from dental materials in various immersion media.

Since fluoride (F-) and aluminum (Al3+) present anticariogenic properties and F- release from ionomeric materials depends on the media used in the evaluation, this study tested the hypothesis whether release of Al3+ also depends on the testing media. The simultaneous release of F- and Al3+ was assessed over 15 days in three media: (i) distilled and deionized water (H2O), (ii) artificial saliva (AS) and (iii) solutions simulating a cariogenic challenge (pH-cycling in demineralizing and remineralizing solutions, De-Re-). Six cylindrical samples of each tested material (Ketac-Fil, Vitremer, Fuji Ortho LC and F 2000) were prepared and suspended individually in 1.0 mL of each solution. All solutions were changed daily. F- and Al3+ were determined by ion-selective electrode and atomic absorption, respectively. ANOVA showed statistical significance for the interaction of material, time, media (p < 0.05), either for F- or Al3+ release. The resin-modified glass ionomer Vitremer released the highest amount of F- and Al3+ in De-Re- solutions compared to the other materials (p < 0.05); differences among the materials in H2O and AS were statistically consistent. The data suggest that the media used to evaluate the simultaneous release of F- and Al3+ should be taken into account when the anticariogenic potential of different dental materials is assessed.

Acetates↗
PubMed2003

Five-year double-blind randomized clinical evaluation of a resin-modified glass ionomer and a polyacid-modified resin in noncarious cervical lesions.

PURPOSE: The aim of this double-blind randomized study was to compare the clinical performance of a resin-modified glass ionomer (Vitremer, 3M) and a polyacid-modified resin (Dyract, Dentsply DeTrey) in noncarious Class V restorations after 5 years. MATERIALS AND METHODS: Twelve patients, having at least one pair of equal-sized noncarious cervical lesions under occlusion and a mean age of 40 years (range 19 to 63 years; median 41), were enrolled in this study. A total of 32 restorations (16 with each material) were placed according to the manufacturers' instructions by two calibrated operators. Two other independent examiners evaluated the restorations at baseline and after 5 years according to the USPHS criteria. The assessment criteria were: retention, anatomical form, marginal adaptation and marginal discoloration, color match, surface texture, and secondary caries. Statistical analysis was conducted using Fisher's exact test (alpha = 0.05). RESULTS: No secondary caries was detected with either material. The retention rate for Vitremer (93%) and for Dyract (78.5%) did not differ significantly (p > 0.05). Regarding anatomical form, only two restorations of each material were recorded as bravo. In terms of marginal adaptation, 38.5% of Dyract restorations were rated alpha and 61.5% bravo, while 84.6% of Vitremer restorations were rated alpha and only 15.4% bravo (p < 0.05). For marginal discoloration, 18.2% of Dyract restorations and 84.6% of Vitremer restorations were rated alpha, with the remaining rated bravo. 86% of Vitremer restorations were rated as bravo and 23% alpha for both surface texture and color match. All Dyract restorations were classified as alpha regarding surface texture, and only two Dyract restorations (18.2%) were classified as bravo in the color match item. CONCLUSION: The marginal adaptation of the RMGIC (Vitremer) was significantly better, the marginal discoloration lower, and the retention rate higher (though not significantly) than that of the PMRC (Dyract) after 5 years in situ. Dyract performed better in terms of surface texture and color match in noncarious Class V restorations after 5 years.

Adult↗
PubMedDate not supplied

Eliminating microleakage from the composite resin system.

Research indicates that microleakage is the major cause of composite restoration failure. Because the different physical properties of composite resin and tooth structure cause microleakage in composite tooth restorations, it is possible to eliminate microleakage by making composite's physical properties more similar to those of tooth structure. This article reviews the physical properties of composite resin systems last as they relate to tooth structure and microleakage.

Compomers↗
PubMed2004

Assessment of coronal microleakage of three materials used in endodontically treated teeth.

This study compared the coronal microleakage of three restorative materials used to seal the access cavity in root treated teeth. Thirty six teeth were prepared and three experimental groups were obturated and the access cavity filled with different materials; Group A--Intermediate Restorative Material, Group B--Fuji II and Group C--Dyract AP. Microleakage was assessed by Indian ink penetration. The mean coronal dye leakage for Group A was 0.895 mm, for Group B 1.914 mm and for Group C 3.245 mm. There was significantly (p < 0.05) more dye leakage in teeth restored with Dyract AP compared to those with Fuji II or IRM.

Analysis of Variance↗