Aim: To test the hypothesis that antimicrobial agents can be incorporated into bis-acryl resin and that the material will inhibit bacterial growth in vitro. Materials and Methods: 0.5%, 1% and 2% triclosan (5-chloro-2-(2,4-dichlorophenoxy)phenol) and 0.05% 0.01% and 0.15% cetylpyridinium chloride were incorporated into bis-acryl resins and molded into 1 mm × 10 mm discs. The discs were placed on bacterial culture media inoculated with Aggregatibacter actinomycetemcomitans strain Y4, Porphyromonas gingivalis strain SUNYaB A7A1-28 or Streptococcus gordonii strain 10558, incubated and examined for growth inhibition. Results: Triclosan-containing bisacryl resin discs produced dose-dependent zones of growth inhibition for A. actinomycetemcomitans but not S. gordonii or P. gingivalis. Cetylpyridinium chloride-containing discs produced dose-dependent zones of growth inhibition for Porphyromonas gingivalis and Streptococcus gordonii but not A. actinomycetemcomitans. Conclusion: Triclosan and cetylpyridinium chloride can be incorporated into bis-acryl resin and can inhibit the growth of plaque bacteria in a dose dependent manner. Bis-acryl resin containing antimicrobial agents may inhibit in vivo plaque accumulation and gingival inflammation.

Statement of problem. Despite the expanded applications for zirconia in restorative dentistry, there is no clear recommendation in the literature regarding surface treatment before bonding.Purpose. The purpose of this study was to evaluate the effect of mechanical surface treatment of yttria-partially stabilized zirconia on its flexural strength and the effect of mechanical and chemical surface treatments on its bond strength to a resin cement.Material and methods. For flexural strength evaluation, zirconia bars (4 x 5 x 40 mm) were prepared from zirconia blocks, finished using a diamond rotary cutting instrument, sintered, then assigned into 4 groups: (1) control (no treatment), (2) airborne-particle abrasion, (3) silicoating, and (4) wet hand grinding. After storage for 24 hours at 37 C, flexural strength was determined using a 3-point bending test, and the results were analyzed using 1-way ANOVA (alpha=.05). For shear bond strength evaluation, zirconia rods (2.5 x 3 mm) were prepared from zirconia blocks, sintered, and assigned into 16 groups. Each group underwent a combination of the following mechanical and chemical treatments. Mechanical treatment included: (1) control (no treatment), (2) airborne-particle abrasion, (3) silicoating, or (4) wet hand grinding. Chemical treatment included: (1) control (no treatment), (2) acid etching followed by silanation, (3) silanation only, or (4) application of zirconia primer. Dentin specimens were prepared from extracted molars stored in 0.5% chloramine-T Zirconia rods were bonded to dentin using a resin cement (Multilink Automix), then light polymerized. After storage, the specimens were loaded to failure with the notched shear bond test method in a universal loading apparatus. For artificial aging analysis, the groups that achieved the highest bond strength values were duplicated, stored at 37 degrees C and 100% humidity for 90 days, and thermal cycled before being loaded to failure.Results were analyzed using 2-way ANOVA (alpha=.05). Results. Airborne-particle abrasion and hand grinding significantly increased flexural strength. The highest shear bond strength values were achieved for the following groups: silicoated + silanated > hand ground + zirconia primer > airborne-particle abraded + silanated > zirconia primer > airborne-particle abraded + zirconia primer. Artificial aging resulted in significantly lower shear bond strength for the silicoated/silanated and the zirconia primer groups.Conclusions. Mechanical modification of the surface increased the flexural strength of Y-TZP. The resin bond to Y-TZP was improved by surface treatment. A combination of mechanical and chemical conditioning of the zirconia surface was essential to develop a durable resin bond to zirconia. (J Prosthet Dent 2010;103:210-220)

S. Howard Payne was an icon in prosthetic dentistry, and his love for The Journal of Prosthetic Dentistry was evident to all. During the early days of the Journal, Howard, as part of a close-knit group including Louis Block, Carl Boucher, Judson Hickey, and Danny Gehl, helped establish the publication as a major contributor to prosthetic dentistry for both general dentists and prosthodontists. Dr Payne served the Journal for 32 years. For 6 of those years he served as a member of the Board of Directors of the Editorial Council, representing the Academy of Denture Prosthetics (now the Academy of Prosthodontics). He was coeditor for Dental Techniques, assistant editor for Complete Prosthodontics, and, later, a clinical consultant. Howard spoke with affection and gratitude of the experiences he had and the friends he enjoyed through his association with the Journal. He appreciated the opportunities the Journal extended to him, stating that reviewing and editing the work of authors was a delight for him. “Few individuals have his spirit and dedication to all that he loved doing,” said Dr Brien Lang, Chair of the Editorial Council for the JPD, in reference to Dr Payne's legacy to the Council and the Journal.

The Journal of Prosthetic Dentistry Kim et al Machado et al 13.Rodrigues Garcia RC, Joane Augusto de S Jr, Rached RN, Del Bel Cury AA. Effect of denture cleansers on the surface roughness and hardness of a microwave-cured acrylic resin and dental alloys. J Prosthodont 2004;13:173-8. 14.Devlin H, Kaushik P. The effect of water absorption on acrylic surface properties. J Prosthodont 2005;14:233-8. 15.Azevedo A, Machado AL, Vergani CE, Giampaolo ET, Pavarina AC, Magnani R. Effect of disinfectants on the hardness and roughness of reline acrylic resins. J Prosthodont 2006;15:235-42. 16.Paranhos HF, Silva-Lovato CH, Souza RF, Cruz PC, Freitas KM, Peracini A. Effects of mechanical and chemical methods on denture biofilm accumulation. J Oral Rehabil 2007;34:606-12. 17.Dixon DL, Breeding LC, Faler TA. Microwave disinfection of denture base materials colonized with Candida albicans. J Prosthet Dent 1999;81:207-14. 18.Neppelenbroek KH, Pavarina AC, Spolidorio DM, Vergani CE, Mima EG, Machado AL. Effectiveness of microwave sterilization on three hard chairside reline resins. Int J Prosthodont 2003;16:616-20. 19.Campanha NH, Pavarina AC, Vergani CE, Machado AL. Effect of microwave sterilization and water storage on the Vickers hardness of acrylic resin denture teeth. J Prosthet Dent 2005;93:483-7. 20.Sartori EA, Schmidt CB, Walber LF, Shinkai RS. Effect of microwave disinfection on denture base adaptation and resin surface roughness. Braz Dent J 2006;17:195-200. 21.Sartori EA, Schmidt CB, Mota EG, Hirakata LM, Shinkai RS. Cumulative effect of disinfection procedures on the microhardness and tridimensional stability of a poly(methyl methacrylate) denture base resin. J Biomed Mater Res B Appl Biomater 2008;86B:360-4. 22.Verran J, Maryan CJ. Retention of Candida albicans on acrylic resin and silicone of different surface topography. J Prosthet Dent 1997;77:535-9. 23.Radford DR, Sweet SP, Challacombe SJ, Walter JD. Adherence of Candida albicans to denture-base materials with different surface finishes. J Dent 1998;26:577-83. 24.Bollen CM, Lambrechts P, Quirynen M. Comparison of surface roughness of oral hard materials to the threshold surface roughness for bacterial plaque retention: a review of the literature. Dent Mater 1997;13:258-69. 25.Powers JM, Sakaguchi RL. Craig’s restorative dental materials. 12th ed. St. Louis: Elsevier; 2006. p. 79. 26.Loxley EC, Liewehr FR, Buxton TB, McPherson JC 3rd. The effect of various intracanal oxidizing agents on the push-out strength of various perforation repair materials. Oral Surg Oral Med Oral Pathol Oral Radiol Endod 2003;95:490-4. 27.Weiger R, Kuhn A, Löst C. Effect of various types of sodium perborate on the pH of bleaching agents. J Endod 1993;19:239-41. 28.Lamb DJ, Ellis B, Priestley D. The effects of process variables on levels of residual monomer in autopolymerizing dental acrylic resin. J Dent 1983;11:80-8. 29.Vallittu PK, Miettinen V, Alakuijala P. Residual monomer content and its release into water from denture base materials. Dent Mater 1995;11:338-42. 30.Vallittu PK, Ruyter IE, Buykuilmaz S. Effect of polymerization temperature and time on the residual monomer content of denture base polymers. Eur J Oral Sci 1998;106:588-93. 31.Kedjarune U, Charoenworaluk N, Koontongkaew S. Release of methyl methacrylate from heat-cured and autopolymerized resins: cytotoxicity testing related to residual monomer. Aust Dent J 1999;44:25-30. 32.Urban VM, Machado AL, Oliveira RV, Vergani CE, Pavarina AC, Cass QB. Residual monomer of reline acrylic resins. Effect of water-bath and microwave postpolymerization treatments. Dent Mater 2007;23:363-8. 33.Frangou MJ, Polyzois GL. Effect of microwave polymerisation on indentation creep, recovery and hardness of acrylic denture base materials. Eur J Prosthodont Restor Dent 1993;1:111-5. 34.Lee SY, Lai YL, Hsu TS. Influence of polymerization conditions on monomer elution and microhardness of autopolymerized polymethyl methacrylate resin. Eur J Oral Sci 2002;110:179-83. 35.Braun KO, Mello JA, Rached RN, Del Bel Cury AA. Surface texture and some properties of acrylic resins submitted to chemical polishing. J Oral Rehabil 2003;30:91-8. 36.Faltermeier A, Rosentritt M, Müssig D. Acrylic removable appliances: comparative evaluation of different postpolymerization methods. Am J Orthod Dentofacial Orthop 2007;131:301.e16-22. 37.Yatabe M, Seki H, Shirasu N, Sone M. Effect of the reducing agent on the oxygeninhibited layer of the cross-linked reline material. J Oral Rehabil 2001;28:180-5. 38.International Standards Organization. ISO 1567:1999/Amd 1:2003. Dentistry-denture base polymers. Amendment. Available at: http://www.iso.ch/iso/en/prods-services/ ISOstore/store.html. Accessed on May 8, 2009. 39.Low IM. Effects of load and time on the hardness of a viscoelastic polymer. 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This article describes a method of fabricating a customized weighted metal base for the mandibular complete denture using a processed denture base and a plaster index of the tooth arrangement. (Prosther Dent 2009;102:123-125)

STATEMENT OF PROBLEM:The adequacy of the strength of dental zirconia abutments under heavy occlusal load conditions is questionable, with degradation of the mechanical properties of zirconia having been reported. Therefore, some alternatives must be considered. PURPOSE:The purpose of this study was to determine the efficacy of fabricating pressable metal ceramic custom implant (Pr) abutments, and to evaluate the fracture resistance of these abutments. MATERIAL AND METHODS:Two groups of implant abutment specimens were fabricated (n=10). The experimental group consisted of Pr abutments, and the control group consisted of CAD/CAM-designed zirconia-based ceramic (Zr) abutments. For the experimental group, custom metal abutments were cast using a compatible metal alloy (Lodestar); this was followed by injection molding with lithium disilicate pressable ceramic (IPS e.max Press) around the metal column of the custom implant abutment. For the control group, 10 specimens were fabricated from CAD/CAM-designed zirconia abutments (Procera Zirconia). Following scanning, all-ceramic crowns with the average dimensions of a human central incisor were fabricated for the experimental and control abutments (n=20) using lithium disilicate pressable ceramic (IPS e.max Press). Each crown was cemented to the implant abutments with a resin luting agent (Variolink II). The crown-abutment test specimens were fixed to titanium implant analogs and placed in a test stand at 30 degrees from the vertical axis of the specimens in a computer-controlled universal testing device. The independent t test was used to detect if the mean values of the fracture load differed significantly (alpha=.05) between the 2 groups. RESULTS:The mean (SD) fracture load was significantly higher in the Pr group (901.67 (102.05) N) than in the Zr group (480.01 (174.46) N, P<.005). CONCLUSIONS:This study found that Pr abutments are stronger than Zr abutments.

Statement of problem. Although the superior qualities of microwave technology are common knowledge in the industry, effects of microwave glazing of dental ceramics have not been investigated.Purpose. The purpose of this study was to investigate the surface roughness and flexural strength achieved by glazing porcelain specimens in a conventional and microwave oven.Material and methods. Thirty specimens of each type of porcelain (Omega 900 and IPS d.Sign) were fabricated and sintered in a conventional oven. The specimens were further divided into 3 groups (n=10): hand polished (using diamond rotary ceramic polishers), microwave glazed, and conventional oven glazed. Each specimen was evaluated for surface roughness using a profilometer. The flexural strength of each specimen was measured using a universal testing machine. A 2-way ANOVA and Tukey HSD post hoc analysis were used to determine significant intergroup differences in surface roughness (alpha=.05). Flexural strength results were also analyzed using 2-way ANOVA, and the Weibull modulus was determined for each of the 6 groups. The surfaces of the specimens were subjectively evaluated for cracks and porosities using a scanning electron microscope (SEM).Results. A significant difference in surface roughness was found among the surface treatments (P=.02). Follow-up tests showed a significant difference in surface roughness between oven-glazed and microwave-glazed treatments (P=.02). There was a significant difference in flexural strength between the 2 porcelains (P<.005), but no significant difference in flexural strength by surface treatment (P=.48). The Weibull modulus value for the Omega 900 microwave-glazed group was the highest (1.9) as compared to the other groups.Conclusions. The surface character of microwave-glazed porcelain was superior to oven-glazed porcelain. Omega 900 had an overall higher flexural strength than IPS d.Sign. Weibull distributions of flexural strengths for Omega 900 oven-glazed and microwave-glazed specimens were similar. SEM analysis demonstrated a greater number of surface voids and imperfections in IPS d.Sign as compared to Omega 900. (J Prosthet Dent 2009;101:20-28)

STATEMENT OF PROBLEM:Most all-ceramic fixed dental prostheses (FDPs) fail at the connectors. PURPOSE:The purpose of this study was to determine the effect of 2 connector designs on the fracture resistance of core materials used for all-ceramic FDPs. MATERIAL AND METHODS:Three materials were tested: (1) heat-pressed lithium disilicate glass ceramic (IPS e.max Press (Press)), (2) milled lithium disilicate glass ceramic (IPS e.max CAD (CAD)), and (3) milled yttrium-stabilized tetragonal zirconia polycrystals (Y-TZP) (IPS e.max ZirCAD (ZirCAD)). Specimens were made into 30 x 4 x 4-mm bars to represent 3-unit FDPs. Two connector designs, round (0.60 +/-0.01-mm radius of curvature) and sharp (0.06 +/-0.001-mm radius of curvature), with a 3.00 +/-0.05-mm cross-section for each connector, were studied (n=5). Each specimen was loaded to fracture in a universal testing machine with a crosshead speed of 0.1 mm/min. Data were analyzed with a 2-way univariate ANOVA and Tukey HSD test (alpha=.05). RESULTS:Mean (SD) failure loads for round connector designs were 684.2 (70.1) N for ZirCAD, 260 (7.8) N for CAD, and 172.9 (35.5) N for Press. Mean (SD) failure loads for sharp connector designs were 386.3 (51.5) N for ZirCAD, 87.9 (7.0) N for CAD, and 125.1 (15.1) N for Press. The 2-way univariate ANOVA indicated statistically significant differences (P<.005) for material and connector design, and, also, a significant interaction between material and connector design. Higher maximum failure loads were found for the round connector design when compared to the sharp connector design, for ZirCAD and CAD. However, this difference was not statistically significant for the Press groups. SEM subjective assessment of the fractured specimens revealed that the fracture initiated from the gingival surface (tensile) of the connector toward the pontic (central loading point). CONCLUSIONS:Fracture resistance of ceramic core materials is affected by fabrication technique and connector design. Connector design affected fracture resistance of the milled ceramic, but not the pressed ceramic.

Statement of problem. There are several electronic shade-matching instruments available for clinical use, but the reliability and accuracy of these instruments have not been thoroughly investigated.Purpose. The purpose of this in vitro study was to evaluate the reliability and accuracy of 4 dental shade-matching instruments in a standardized environment.Material and methods. Four shade-matching devices were tested: SpectroShade, ShadeVision, VITA Easyshade, and ShadeScan. Color measurements were made of 3 commercial shade guides (Vitapan Classical, Vitapan 3D-Master, and Chromascop). Shade tabs were placed in the middle of a gingival matrix (Shofu GUMY) with shade tabs of the same nominal shade from additional shade guides placed on both sides. Measurements were made of the central region of the shade tab positioned inside a black box. For the reliability assessment, each shade tab from each of the 3 shade guide types was measured 10 times. For the accuracy assessment, each shade tab from 10 guides of each of the 3 types evaluated was measured once. Differences in reliability and accuracy were evaluated using the Standard Normal z test (2 sided) (alpha=.05) with Bonferroni correction.Results. Reliability of devices was as follows: ShadeVision, 99.0%; SpectroShade, 96.9%; VITA Easyshade, 96.4%; and ShadeScan, 87.4%. A significant difference in reliability was found between ShadeVision and ShadeScan (P=.008). All other comparisons showed similar reliability. Accuracy of devices was as follows: VITA Easyshade, 92.6%; ShadeVision, 84.8%; SpectroShade, 80.2%; and ShadeScan, 66.8%. Significant differences in accuracy were found between all device pairs (P<.001) for all comparisons except for SpectroShade versus ShadeVision (P=.033).Conclusions. Most devices had similar high reliability (over 96%), indicating predictable shade values from repeated measurements. However, there was more variability in accuracy among devices (67-93%), and differences in accuracy were seen with most device comparisons. (J Prosthet Dent 2009;101:193-199)

Statement of problem. The natural tooth color space reported by a manufacturer may not represent the comprehensive spectrum of natural teeth for all population groups.Purpose. The purpose of this study was to define a natural tooth color space within the Greater Buffalo, New York population and to compare that to the color space determined by a manufacturer.Material and methods. Nine hundred and thirty-three maxillary central incisors (501 patients) were measured with a shade-taking device (Vita Easyshade). For each tooth, L*, a*, b* values, chroma, hue, and the closest shade (Vita 3D-Master) were recorded. A linear regression analysis was performed to determine how well the manufacturer's values predict actual values for L*, a*, and b*. Color differences (Delta E*) between the Buffalo population and the closest shade were also calculated. A I-sample t test was used to determine whether the color differences seen in the sample were statistically different from the perceptibility threshold, Delta E*=3.7 ((alpha=.05).Results. All 3 attributes of the Buffalo population displayed a broader range than those from the shade guide. However, the regression analysis revealed a significantly positive relationship between the L*, a*, and b* values of the 2 methods (P <.001). The I-sample t test revealed a significant Delta E* (mean AE*=6.1 5) difference from the perceptibility threshold of Delta E*=3.7 (P <.001).Conclusions. Color differences between the Buffalo population and the shade guide were frequently above published perceptibility thresholds, but within the range of acceptability. The Buffalo population tooth color space encompassed the manufacturer's color space.

Recent advances in color matching have been driven by the market demand for high-quality esthetic restorations. Improved shade guides, availability of shade-taking devices, and research in the area of human color vision have improved the potential of clinicians to achieve excellent color-matched restorations. A thorough understanding of appearance attributes of natural teeth is required along with these new tools to maximize shade-matching results.

STATEMENT OF PROBLEM:Many investigations in the field of metal ceramics have examined materials, manipulative variables, and the relationship of these factors to a restoration's color. However, the effect of the artistic component of restoration fabrication is not known. PURPOSE:The purpose of this study was to determine through instrumental colorimetry the variability in color reproduction for metal ceramic crowns fabricated by commercial dental laboratory technicians. MATERIALS AND METHODS:Fifty metal ceramic crowns were fabricated on standardized metal frameworks to the same shade specifications by 5 commercial dental laboratories (n=10). Laboratory prescriptions requested that the technician match the shade and translucency of a provided Vita Lumin A3.5 shade tab. Technicians used the porcelain and technique of their own selection to match the tab. Color differences were determined by use of a colorimeter between crowns and the prescribed shade tab at middle and incisal sites. Analysis of variance was used to determine whether differences in color reproduction existed among laboratories. Where statistically significant interactions existed, the Tukey honestly significant difference test was used to determine significant differences between laboratories according to sites (alpha=.05). RESULTS:Color reproduction was significantly different (P <.0001) among laboratories for both sites. Mean color difference from shade tabs ranged from 3.5 to 11.1 DeltaE units. All laboratories were better at matching shades in the incisal third of the crown. CONCLUSION:Within the limitations of this study, the ability to reproduce the color of the target shade tab differed among laboratories. Most crowns fabricated by the laboratories in this study, when compared to the prescribed shade tab, were above the clinical threshold for an acceptable shade match under intraoral conditions (DeltaE 3.7).

Statement of problem. Application of technology that quantify color and color differences is currently used in esthetic restorative materials research. However, parameters for the size of perceptible and accept able color differences in metal ceramic crowns have not been determined.Purpose. The CIELAB colorimetric system was used to study the relationship between instrumentally measured color differences (Delta E) and human observer assessment of color differences in metal ceramic crowns.Material and methods. Subjects were shown pairs of metal ceramic crowns whose color difference varied from indistinguishable to obvious. The subjects attempted to discern a difference in each pair's color and indicated the clinical acceptability of the shade difference between the crown pairs.Results. Correlations between instrumental and visual assessment of color differences in these crown pairs did not agree in all dimensions of color space. Thresholds acceptability of color differences were 1.1 Delta E units for red-varying crowns and 2.1 Delta E units for yellow-varying crowns. Thresholds for perceptibility judgments were significantly lower than thresholds for acceptability judgments.Conclusions. Acceptability thresholds were found to be dependent on chromaticity. Observers were more sensitive and critical of crowns whose color differed in redness as opposed to crowns whose color differed to the same extent in yellowness.

Spectrometric analysis has been used previously to examine color differences among various porcelains and metal ceramic systems. This study determined whether nongreening porcelain of a single shade fused to high-gold and palladium-silver alloys results in the same final color. Both conventional (VMK-68) and nongreening (VMK-68N) porcelains were fused to metal coupons of high gold (Will-Ceram Y) and palladium-silver (Will-Ceram W-1) to make up four groups. CIELAB colorimetric data were collected at each of seven fabrication steps to define color differences between steps for each alloy-porcelain group as well as between groups at each step. For the shade tested, perceptible color differences between high-gold/conventional porcelain and palladium-silver/nongreening porcelain coupons did not support manufacturers' claims.

Precementation refinements of porcelain-fused-to-metal crowns often require reglazing or polishing of the porcelain surface. This study was done to determine whether visual inspection differences exist between glazed and polished porcelain surfaces. Prosthodontists, general dentists, and students (six in each group) rated esthetic properties of 12 porcelain-fused-to-metal crowns. All crowns were initially autoglazed. For phase 1 observations, six crowns were air abraded and polished and six retained their glazed surface. For phase 2 observations, the surface treatments were reversed. At both observations, crowns were rated on 5-point Likert scales for outline form, porosity, smoothness, reflectance, texture, dullness, defects, and general esthetic appearances. Phase 1 polished and glazed crowns had different means for outline form sharpness, porosity, reflectance, dullness, and general esthetic appearance. Phase 2 crowns were different for dullness. Polished and glazed crowns alike were more dull at phase 1 than at phase 2. Glazed crowns were different between phases for reflectance and general esthetic appearance. All reported differences were significant at p less than .01. Significant differences occurred among raters with polished and glazed crowns for several variables.

Journal of Dental EducationVolume 52, Issue 3 p. 164-166 Article Use of videotape feedback in a communication skills course EL Davis, EL DavisSearch for more papers by this authorLA Tedesco, LA TedescoSearch for more papers by this authorNE Nicosia, NE NicosiaSearch for more papers by this authorJD Brewer, JD BrewerSearch for more papers by this authorTE Harnett, TE HarnettSearch for more papers by this authorGW Ferry, GW FerrySearch for more papers by this author EL Davis, EL DavisSearch for more papers by this authorLA Tedesco, LA TedescoSearch for more papers by this authorNE Nicosia, NE NicosiaSearch for more papers by this authorJD Brewer, JD BrewerSearch for more papers by this authorTE Harnett, TE HarnettSearch for more papers by this authorGW Ferry, GW FerrySearch for more papers by this author First published: 01 March 1988 https://doi.org/10.1002/j.0022-0337.1988.52.3.tb02184.xCitations: 5About ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onFacebookTwitterLinkedInRedditWechat No abstract is available for this article.Citing Literature Volume52, Issue3March 1988Pages 164-166 RelatedInformation