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1.
Effect of filler loading on resin cement bonding to silanized buildup composites.
Kajihara, H, Suzuki, S, Minesaki, Y, Kurashige, H, Tanaka, T
American journal of dentistry. 2005;(2):109-12
Abstract
PURPOSE To determine the effects of silanation for core buildup composites on bond strength of resin cement. METHODS Three core buildup composites including FluoroCore LV, Core Restore, and Clearfil Photo Core, of which filler loadings were 65 wt%, 74 wt%, and 83 wt% respectively, were used. All composite specimens were randomly divided into four surface treatment groups of eight each as following; 1) 600-grit ground only, 2) 600-grit ground plus silanation, 3) 600-grit ground plus air-particle abrasion, 4) air-particle abrasion plus silanation. Following these treatments, 4-META/MMA-TBB resin (C&B Metabond) was bonded to the specimen surfaces. Completed specimens were stored in 37 degree C water for 24 hours, and then thermocycled 20,000 times (4 degree C - 60 degree C) before shear bond strengths were tested. Data were analyzed by two-way ANOVA and Scheffé's test for statistical significance (P < 0.05). RESULTS Clearfil Photo Core, of which filler loading was the highest among the resin composites tested, treated with air-particle abrasion plus silanation obtained the highest bond strength. However, silanation alone was not effective for improving the bond strength.
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2.
Shear bond strength of self-etching bonding systems in combination with various composites used for repairing aged composites.
Teixeira, EC, Bayne, SC, Thompson, JY, Ritter, AV, Swift, EJ
The journal of adhesive dentistry. 2005;(2):159-64
Abstract
PURPOSE Repair of worn, broken or discolored composite restorations can be accomplished using new composite material and dentin bonding systems. The purpose of this study was to investigate the effectiveness of self-etching adhesive systems for composite re-bonding procedures onto different composite substrates that had been aged for 6 years prior to testing. MATERIALS AND METHODS Two hundred cylinders (4 mm x 5 mm) of composite were fabricated using 4 hybrid composites [AeliteFil (Bisco), Prodigy (SDS Kerr), TPH (Dentsply Caulk), and Z100 (3M ESPE)] following manufacturers' directions and stored for 6 years in 1% NaCl solution. After aging, each specimen was wet polished through 600-grit SiC and randomly assigned to a self-etching bonding system (Adper Prompt L-Pop/Z100 [3M ESPE]; Tyrian One-Step Plus/AeliteFil [Bisco]; OptiBond Solo Plus SE/Prodigy [SDS Kerr], Xeno III/TPH [Dentsply Caulk]) or a total-etch control (Prime&Bond NT/TPH [Dentsply Caulk]) (n = 10 per group). Shear bond strengths (SBS) for repairs were evaluated after 48 h (crosshead speed = 0.5 mm/min) and were compared by two-way ANOVA (p = 0.05) with Tukey post-hoc tests. RESULTS Significant differences (p < or = 0.05) were detected for the main effects (substrates and bonding systems), but the interaction was not significant. SBS for bonding systems were from highest to lowest: (1) Prime&Bond NT, (2) OptiBond Solo Plus SE, (3) Adper Prompt L-Pop, (4) Xeno III, (5) Tyrian One-Step Plus. SBS of the repair systems to Z100 were significantly lower than those to the other composite substrates. CONCLUSION Self-etching systems can be used to repair aged composite, but the efficacy of repair of aged composite is system dependent.
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3.
The influence of fatigue loading on the quality of the cement layer and retention strength of carbon fiber post-resin composite core restorations.
Bolhuis, P, de Gee, A, Feilzer, A
Operative dentistry. 2005;(2):220-7
Abstract
Clinical studies have shown that endodontically treated teeth restored with short posts or deficient ferrules show a high failure risk. This study. evaluated the influence of fatigue loading on the quality of the cement layer between prefabricated quartz coated carbon fiber posts with restricted length and the root canal wall in maxillary pre-molars. Two adhesive resin composite cements, chemical-cured Panavia 21 (Group 1) and dual-cured RelyX-ARC (Group 2), and one resin-modified glass-ionomer cement, chemical-cured RelyX (Group 3), delta were selected for this study. Post- and-core restorations were made on single-rooted human maxillary premolars from which the coronal sections were removed at the level of the proximal cemento-enamel junction (CEJ). Following endodontic treatment, a post-and-core restoration with 6-mm post length was prepared for each tooth. The posts were directly cemented into the root canal and, after applying an adhesive (Clearfil Photo Bond), they were built up with a core build-up composite (Clearfil Photo Core). For each group (n=8), half of the specimens were exposed to fatigue loading (10(6) load cycles) almost perpendicular to the axial axis (85 degrees), while the other half were used as the control. Three parallel, transverse root sections, 1.5-mm thick, were cut from each specimen at the apical, medial and coronal location. These sections were examined by Scanning Electron Microscopy (SEM) to evaluate the integrity of the cement layer, while the retention strength of the cemented post sections was determined with the push-out test. The multivariate results of MANOVA showed that the condition main effect (fatigue or control) was not significant (p=0.059); the two other main effects, type of cement and section location, were significant (p=0.001 and p=0.008). For both the push-out strength and SEM evaluation of the cement layer integrity, the results significantly improved from RelyX to RelyX-ARC to Panavia 21 and also from apical to coronal.
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4.
Endodontic complications after plastic restorations in general practice.
Whitworth, JM, Myers, PM, Smith, J, Walls, AW, McCabe, JF
International endodontic journal. 2005;(6):409-16
Abstract
AIM: To test the hypothesis that dentine and pulp protection by conditioning-and-sealing is no less effective than using a conventional calcium hydroxide lining. METHODOLOGY A cohort of healthy adults requiring a new or replacement restoration in a posterior tooth was recruited in six general practices. All procedures received local Ethics Committee approval. Exclusion criteria included signs and symptoms of pulp necrosis or inflammation, and patients unable to commit to a long-term trial. Cavity preparations were randomized to receive a calcium hydroxide lining or conditioning-and-sealing with a smear-removing bonding system. Choice of bulk restorative material (composite resin or amalgam) was at the discretion of the dentist. The key outcome measure was evidence of pulpal breakdown identified at unscheduled (emergency) or scheduled recall examinations. Postoperative sensitivity was recorded on 100 mm VAS at 24 h, 4 days and 7 days. Pulp status was assessed at 6, 12, 24 and 36 month recall, and at any emergency recall appointment. The relationship between pre-treatment and treatment variables and pulp breakdown was assessed by logistic regression (P = 0.05). RESULTS A total of 602 teeth were recruited, with comparable numbers of cavities lined (288, 47.8%) or conditioned and sealed (314, 52.2%). The majority (492, 81.7%) were replacement restorations, and amalgam was the most common bulk restorative material (377, 62.6%). A total of 390 (64.8%) restored teeth were reviewed at 6 months, 307 (51%) at 12 months, 363 (60.3%) at 24 months, and 279 (46.3%) at 36 months post-restoration. Sixteen cases of pulp breakdown were identified within 36 months of restoration placement, 11 presenting as emergencies and five detected at routine recall examination. Logistic regression showed that preoperative pain, cavity treatment by lining or conditioning-and-sealing and the use of rubber dam isolation had no association with pulp breakdown. Pulp breakdown was associated with deep or pulpally exposed cavities (P < 0.001, odds ratio 7.8) and with composite rather than amalgam restorations (P = 0.001, odds ratio 2.13). Re-coding to identify teeth with pulp exposures revealed that pulpal exposure was the key determinant of adverse pulp outcomes (P < 0.0001, odds ratio 28.4) and that composite resin restorations were again more likely to be associated with pulp breakdown than amalgam (P = 0.017, odds ratio 3.92). CONCLUSIONS Considered within the context of routine primary dental care: Dentists can be confident that pulps will be equally well protected from post-restorative breakdown up to 36 months by calcium hydroxide lining and conditioning-and-sealing with adhesive resins. Residual dentine thickness appears to be a key determinant of pulp responses after restorative dental treatment. In deep and pulpally exposed cavities in posterior teeth, composites were associated with more pulpal breakdown than amalgams.
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5.
Fluoride uptake by enamel and dentin from bonding agents and composite resins: a comparative study.
Shashikiran, ND, Kumar, NC, Subba Reddy, VV
Journal of the Indian Society of Pedodontics and Preventive Dentistry. 2003;(4):125-30
Abstract
The present study was performed to compare the amount of in vitro fluoride uptake by enamel and dentin from fluoridated bonding agent with non-fluoridated composite (Group I), non-fluoridated bonding agent with fluoridated composite (Group II) and fluoridated bonding agent with fluoridated composite resin (Group III). Sixty extracted premolars were selected and divided into three groups of 20 teeth each. Restorative materials were applied according to manufacturer's instructions into standard windows created in the teeth, cured and placed in de-ionised water for three months. The fluoride content of successive acid etch biopsy was determined by specific ion-electrode analysis. Although significant amount of fluoride uptake occurred in all the test groups, fluoride uptake was found to be highly significant in dentin when compared to enamel in Group, I, II and III (P<0.001). The fluoride uptake was greater by both enamel and dentin in Group III ie fluoridated bonding agent with fluoridated composite resin.
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6.
Tensile strength and ultrastructure of a compomer and a composite in aqueous and non-aqueous storage media.
Huang, C, Tay, FR, Wei, SH, Kei, LH, Cheung, GS, Pashley, DH
American journal of dentistry. 2003;:82A-87A
Abstract
PURPOSE To compare the ultimate tensile strength (UTS) of a compomer (Dyract AP) and a composite (Spectrum TPH) that were stored in an aqueous or a non-aqueous medium for up to 180 days. METHODS 156 hourglass-shaped specimens of each material with cylindrical cross-sectional areas along the test regions were prepared. For each material, 12 beams were stressed to failure using a microtensile testing method to obtain the baseline UTS data. The rest were divided into two groups. One group was stored in de-ionized water (W), and the other (control) in silicone fluid (O) at 37 degrees C. 12 beams were removed from the respective storage medium after 1, 7, 14, 30, 90, 180 days for evaluation of the NTS. Materials retrieved from the intact central cylindrical portion of the fractured 180-day specimens were prepared for transmission electron microscopy (TEM). RESULTS Baseline UTS for Dyract AP (D) and Spectrum TPH (S) were 76 +/- 16 MPa and 92 +/- 13 MPa, respectively. One-way ANOVA on ranks and Dunn's multiple comparison tests showed that UTS of Groups D-O, S-O and S-W remained stable during 180 days and were not significantly different from the baseline results. There was a significant drop in UTS in Group D-W after 90 and 180 days when compared with the 1-day result (P < 0.05). A highly significant nonlinear correlation was also observed in Group D-W between the mean UTS after the first day and the storage time (P < 0.01). No difference could be seen between the filler-matrix interface in S-O and S-W. A very thin glass-ionomer phase (ca. 200 nm thick siliceous hydrogel layer) could be observed in D-W, but not in D-O.
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7.
The effect of prophylactic polishing pastes and toothbrushing on the surface roughness of resin composite materials in vitro.
Neme, AM, Wagner, WC, Pink, FE, Frazier, KB
Operative dentistry. 2003;(6):808-15
Abstract
Polishing composite restorations at recall prophylaxis may affect their surface roughness. This investigation evaluated the effect of prophy paste on the surface roughness of a microfilled (Filtek A110) and a microhybrid (Filtek Z250) resin composite before and after simulated toothbrushing. Twenty, two-sided samples of both materials were fabricated in acrylic molds against a Mylar strip (baseline). Three roughness readings were recorded for each surface using a Surfanalyzer 5400 to determine the mean roughness. The samples were finished and polished with the Sof-Lex disk system and the surface roughness (Ra) was re-measured. Samples were randomly assigned and five surfaces for each material were polished with Nupro coarse, medium, fine or Clinpro prophy paste and the surface roughness measured again. All surfaces were brushed 60,000 times at 1.5Hz using a 2N brush-head force (Manly V-8 cross-brushing machine) in a 50:50 (w/w) slurry of toothpaste and water. The surface roughness was measured followed by the application of prophy paste as previously described and this final roughness recorded. Data were analyzed using repeated measures two-factor ANOVA with TUKEY HSD pairwise comparison as appropriate (alpha = 0.05). No significant difference in surface roughness was determined between the microfilled and microhybrid materials at baseline or disk treatment, yet significant differences were observed following brushing and/or prophy paste application. In conclusion, although baseline and disk treated surfaces were not significantly different in microfilled versus microhybrid composites, subsequent prophy paste application and/or simulated toothbrushing caused significant differences.
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8.
Shear bond strengths of composite bonded to porcelain using porcelain repair systems.
Knight, JS, Holmes, JR, Bradford, H, Lawson, C
American journal of dentistry. 2003;(4):252-4
Abstract
PURPOSE To measure and compare the shear bond strengths to porcelain of two composites used with each of two different porcelain bonding systems. METHODS 40 porcelain specimens were mounted in acrylic resin, ground flat using 120 and 320 grit sandpaper, and randomly divided into four groups of 10 for specimen fabrication as follows: Group 1: Premier MicroDose Porcelain Bonding/Optibond FL adhesive/Prodigy composite; Group 2: Premier MicroDose Porcelain Bonding/PQ1 adhesive/Amelogen composite; Group 3: Ultradent Porcelain Etch/Optibond FL adhesive/Prodigy composite; Group 4: Ultradent Porcelain Etch/PQ1 adhesive/Amelogen composite. Manufacturers' directions were followed to treat the porcelain surface and apply the adhesive and composite to each specimen. Following storage in distilled water at 37 degrees C for 7 days, the specimens were subjected to shear testing using an MTS 858 Universal Testing Machine. Data were recorded and analyzed using a one-way ANOVA and t-test. RESULTS There was no significant difference in mean shear bond strength among the four groups (P = 0.575) or between the two groups with the highest and lowest mean shear bond strength (P = 0.288). The mean shear bond strength for all groups exceeded 21 MPa and 39 of 40 specimens exhibited cohesive fracture in porcelain.
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9.
Evaluation of hard tissue replacement composite graft material as a ridge preservation/augmentation material in conjunction with immediate hydroxyapatite-coated dental implants.
Yukna, RA, Castellon, P, Saenz-Nasr, AM, Owens, K, Simmons, J, Thunthy, KH, Mayer, ET
Journal of periodontology. 2003;(5):679-86
Abstract
BACKGROUND Immediate placement of dental implants (DI) in fresh extraction sockets is associated with remaining voids around the DI and often a partial dehiscence or thin facial alveolar plate. Bone replacement grafts are often used to correct these problems. This study evaluated the use of a layered composite of PMMA (poly-methyl-methacrylate), PHEMA (poly-hydroxyl-ethyl-methacrylate), and calcium hydroxide grafts (HTR) as a ridge preservation/ augmentation material used in conjunction with an immediate DI placement technique. METHODS Twenty-three patients requiring 1 or 2 extractions that were treatment planned for immediate DI placement received 4.0 or 3.25 mm diameter hydroxyapatite-coated cylindrical implants in the extraction sockets. HTR was used to fill the remaining socket void and enhance the facial ridge width. A collagen hemostatic was placed to cover the DI sites, flaps released, and primary closure attempted with sutures. DI uncovering was performed at about 6 months. Measurements were taken to the nearest 0.5 mm of the internal socket width and total ridge width at DI placement and uncovering. RESULTS Thirty DIs were placed in the 23 patients. Mean initial internal socket width was 6.9 mm. The total ridge width showed a mean change from 9.1 mm to 8.4 mm; 60% of the areas showed a net increase or no change, while 40% showed a decrease in overall ridge width. DI success rate was 97% out to 6 months of loading. CONCLUSION The results of this study suggest that HTR is a useful adjunct in the placement of immediate DIs for filling of socket voids and preservation of ridge width.
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10.
The influence of different cements on the fracture resistance and marginal adaptation of all-ceramic and fiber-reinforced crowns.
Behr, M, Rosentritt, M, Mangelkramer, M, Handel, G
The International journal of prosthodontics. 2003;(5):538-42
Abstract
PURPOSE This in vitro study investigated the marginal adaptation and fracture resistance of heat-pressed glass-ceramic and fiber-reinforced composite molar crowns luted with resin, resin-modified glass-ionomer, or zinc-oxide-eugenol-free cements. MATERIALS AND METHODS A total of 24 heat-pressed all-ceramic and 24 glass fiber-reinforced composite crowns were constructed and cemented using the above-mentioned luting agents (eight crowns per cement). The restorations were thermocycled and mechanically stressed, and fracture resistance was determined. Marginal adaptation was evaluated before and after stress application using semiquantitative analysis in a scanning electron microscope. RESULTS All-ceramic and fiber-reinforced composite crowns reached the highest fracture resistance after stress application in combination with the resin cement. When luted with resin-modified glass-ionomer or zinc-oxide-eugenol-free cements, the fracture resistance of all-ceramics decreased significantly, while the fiber-reinforced composite crowns maintained their fracture resistance level; the lowest values were found for zinc-oxide-eugenol-free cements. The marginal adaptation remained unchanged after stress for all-ceramics and fiber-reinforced composite restorations if they were luted with resin cements. Luting with resin-modified glass-ionomers significantly deteriorated the marginal adaptation after stress application, with the exception of the crown-cement interface of all-ceramics. CONCLUSION The highest fracture resistance and marginal adaptation were found for all-ceramic and glass fiber-reinforced composite molar crowns if they were luted with resin cement.