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Ma L, Xie Q, Evelina A, Long W, Ma C, Zhou F, Cha R. The Effect of Different Additives on the Hydration and Gelation Properties of Composite Dental Gypsum. Gels 2021; 7:gels7030117. [PMID: 34449595 PMCID: PMC8395839 DOI: 10.3390/gels7030117] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/15/2021] [Revised: 08/04/2021] [Accepted: 08/06/2021] [Indexed: 11/16/2022] Open
Abstract
Dental mold gypsum materials require fine powder, appropriate liquidity, fast curing, and easy-to-perform clinical operations. They require low linear expansion coefficient and high strength, reflecting the master model and facilitating demolding. In this article, the suitable accelerators and reinforcing agents were selected as additives to modify dental gypsum. The main experimental methods used were to compare the trends of linear expansion coefficients of several commercially available dental gypsum products over 72 h and to observe the cross-sectional microstructure of cured bodies before and after dental gypsum modification using scanning electron microscopy. By adjusting the application of additives, the linear expansion coefficient of dental gypsum decreased from 0.26% to 0.06%, while the flexural strength increased from 6.7 MPa to 7.4 MPa at 2 h. Formulated samples showed good stability and gelation properties with linear expansion completed within 12 h. It is indicated that the performance of dental gypsum materials can be improved by adding additives and nanomaterials, which provided a good reference for clinical preparation of high-precision dental prosthesis.
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Affiliation(s)
- Liang Ma
- Beijing Key Laboratory of Materials Utilization of Nonmetallic Minerals and Solid Wastes, National Laboratory of Mineral Materials, School of Materials Science and Technology, China University of Geosciences Beijing, Haidian District, Beijing 100083, China; (L.M.); (Q.X.); (A.E.); (W.L.); (C.M.)
| | - Qianting Xie
- Beijing Key Laboratory of Materials Utilization of Nonmetallic Minerals and Solid Wastes, National Laboratory of Mineral Materials, School of Materials Science and Technology, China University of Geosciences Beijing, Haidian District, Beijing 100083, China; (L.M.); (Q.X.); (A.E.); (W.L.); (C.M.)
| | - Amutenya Evelina
- Beijing Key Laboratory of Materials Utilization of Nonmetallic Minerals and Solid Wastes, National Laboratory of Mineral Materials, School of Materials Science and Technology, China University of Geosciences Beijing, Haidian District, Beijing 100083, China; (L.M.); (Q.X.); (A.E.); (W.L.); (C.M.)
| | - Wenjun Long
- Beijing Key Laboratory of Materials Utilization of Nonmetallic Minerals and Solid Wastes, National Laboratory of Mineral Materials, School of Materials Science and Technology, China University of Geosciences Beijing, Haidian District, Beijing 100083, China; (L.M.); (Q.X.); (A.E.); (W.L.); (C.M.)
| | - Cunfa Ma
- Beijing Key Laboratory of Materials Utilization of Nonmetallic Minerals and Solid Wastes, National Laboratory of Mineral Materials, School of Materials Science and Technology, China University of Geosciences Beijing, Haidian District, Beijing 100083, China; (L.M.); (Q.X.); (A.E.); (W.L.); (C.M.)
| | - Fengshan Zhou
- Beijing Key Laboratory of Materials Utilization of Nonmetallic Minerals and Solid Wastes, National Laboratory of Mineral Materials, School of Materials Science and Technology, China University of Geosciences Beijing, Haidian District, Beijing 100083, China; (L.M.); (Q.X.); (A.E.); (W.L.); (C.M.)
- Correspondence:
| | - Ruitao Cha
- CAS Key Laboratory for Biomedical Effects of Nanomaterials and Nanosafety, National Center for NanoScience and Technology, No. 11, Haidian District, Beijing 100190, China;
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Blasi A, Henarejos-Domingo V, Madeira S, Blasi G, Roig M. Stone verification device for verifying the definitive cast of an implant-supported restoration: A dental technique. J Prosthet Dent 2021; 128:858-863. [PMID: 33640084 DOI: 10.1016/j.prosdent.2021.01.005] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/27/2020] [Revised: 01/16/2021] [Accepted: 01/19/2021] [Indexed: 11/28/2022]
Abstract
To reduce the risk of implant and prosthetic complications, implant-supported prostheses should be passive. A verification device is used to verify the abutment analog position on the definitive cast, and hence its accuracy. This article describes the fabrication of a Type IV stone implant verification device for verifying the accuracy of the definitive cast.
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Affiliation(s)
- Alvaro Blasi
- Private practice, Barcelona, Spain; Adjunct Assistant Professor, Department of Restorative Sciences, Dental College of Georgia at Augusta University, Augusta, Ga
| | - Víctor Henarejos-Domingo
- Private practice, Barcelona, Spain; Assistant Professor, Department of Restorative Dentistry, School of Dentistry, International University of Catalunya, Barcelona, Spain.
| | - Sara Madeira
- Private practice, Barcelona, Spain; Assistant Professor, Department of Integrated Dentistry Department, School of Dentistry, International University of Catalunya, Barcelona, Spain
| | - Gonzalo Blasi
- Private practice, Barcelona, Spain; Assistant Professor, Department of Periodontology, School of Dentistry, International University of Catalunya, Barcelona, Spain; Adjunct Assistant Professor, Division of periodontology, University of Maryland School of Dentistry, Baltimore, Md
| | - Miguel Roig
- Chairman and Professor, Department of Restorative Dentistry, School of Dentistry, International University of Catalunya, Barcelona, Spain
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Abstract
The objective of this study was to assess if the setting expansion, compressive strength, compressive modulus and Knoop hardness is reduced in Type III, IV and V gypsum products when excess water is added to recommended water/powder (W/P) ratios for full-arch implant master casts. Four properties were measured: linear setting expansion, compressive strength, compressive modulus, and Knoop hardness. Three dental stones were evaluated: ISO Type III, Type IV, and Type V. Water was added to recommended W/P ratios as follows: (1) 0%, the manufacturer’s recommend W/P ratio, (2) 50%, 1.5 times the manufacturer’s recommendation of water, (3) 100%, three times the manufacturer’s recommendation of water, (4) 150%, 2.5 times the manufacturer’s recommendation of water, and (5) 200%, three times the manufacturer’s recommendation of water. For all three gypsum types, 50% water additions minimally affected the setting expansion and compressive modulus (p > 0.05), but lowered compressive strength by 26% to 52% (p < 0.05). Knoop hardness was lowered by 24% and 48% for Types V and III (p < 0.05), whereas Type IV was not significantly affected (p > 0.05). With few exceptions, the physical properties for the three gypsum types reached minimum values at 100% dilution, with few changes noted at higher dilutions. Increased W/P ratios did not adequately reduce the setting expansion and adversely affected other physical properties. Of the gypsums tested, Type IV is still recommended due to its lower setting expansion for full-arch implant master casts.
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Maria R, Tan MY, Wong KM, Lee BCH, Chia VAP, Tan KBC. Accuracy of Implant Analogs in 3D Printed Resin Models. J Prosthodont 2020; 30:57-64. [PMID: 32567126 DOI: 10.1111/jopr.13217] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2020] [Revised: 06/14/2020] [Accepted: 06/15/2020] [Indexed: 11/29/2022] Open
Abstract
PURPOSE To study the effect of implant analog system, print orientation, and analog holder radial offset on 3D linear and absolute angular distortions of implant analogs in 3D printed resin models. MATERIALS AND METHODS A sectional master model simulating a 2-implant, 3-unit fixed prosthesis in a partially edentulous jaw was fabricated. Three implant analog systems for 3D printed resin models-Straumann (ST), Core3DCentres (CD) and Medentika (MD)-were tested. The corresponding scan bodies were secured onto the implants and scanned using an intraoral scanner. Models were obtained with a Digital Light Processing printer. Each implant analog system had 2 print orientations (transverse [X] and perpendicular [Y] to the printer door) and 2 analog holder radial offsets (0.04 mm and 0.06 mm), for a total of 60 models. The physical positions of the implants in the master model and the analogs in the printed resin models were directly measured with a Coordinate Measuring Machine (CMM). 3D linear distortion (ΔR) and absolute angular distortion (Absdθ) defined the 3D accuracy of the analogs in the printed models. Univariate ANOVA was used to analyse data followed by post hoc tests (Tukey HSD, α = 0.05). RESULTS Mean ΔR for ST (-155.7 ± 60.6 µm), CD (124.9 ± 65.0 µm) and MD (-92.9 ± 48.0 µm) were significantly different (p < 0.01). Mean Absdθ was not significantly different between ST (0.57 ± 0.48°) and CD (0.41 ± 0.27°), but both were significantly different from MD (2.11 ± 1.14°) (p < 0.01). Print orientation had a significant effect on ΔR only but no discernible trend could be found. Analog holder radial offset had no significant effect on ΔR and Absdθ. CONCLUSIONS Implant analog system had a significant effect on ΔR and Absdθ. Compared to the master model, CD produced greater mean interanalog distances, while ST and MD produced smaller mean interanalog distances. MD exhibited the greatest mean angular distortion which was significantly greater than ST and CD.
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Affiliation(s)
- Rahmat Maria
- Department of Restorative Dentistry, National Dental Centre of Singapore, Republic of Singapore
| | - Ming Yi Tan
- Faculty of Dentistry, National University of Singapore, Republic of Singapore
| | - Keng Mun Wong
- Faculty of Dentistry, National University of Singapore, Republic of Singapore
| | - Bruce Chi Hong Lee
- Faculty of Dentistry, National University of Singapore, Republic of Singapore
| | - Vanessa Ai Ping Chia
- Department of Restorative Dentistry, National Dental Centre of Singapore, Republic of Singapore
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Schott TC, Arsalan R, Weimer K. Students' perspectives on the use of digital versus conventional dental impression techniques in orthodontics. BMC MEDICAL EDUCATION 2019; 19:81. [PMID: 30866910 PMCID: PMC6417015 DOI: 10.1186/s12909-019-1512-3] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/08/2018] [Accepted: 03/04/2019] [Indexed: 06/09/2023]
Abstract
BACKGROUND Despite the increasing use of digital impressions in orthodontics, this technique does not usually form part of the learning objectives in dental training. The aim of this study was to determine how students assess the user-friendliness of intraoral scanners compared to a conventional impression technique after a theoretical and practical teaching module. METHODS Thirty-one dental students in their seventh semester (4th year) received and conducted digital (3 M, St. Paul, NM) and conventional (alginate) impressions from: (i) the dentist's perspective, and (ii) the patient's perspective. Each student completed four questionnaires to evaluate: (i) the user-friendliness of intraoral scanning, and (ii) intraoral scanning compared to the conventional method. RESULTS Thirty (97%) students had not previously performed digital impressions. Twenty-four (77%) students were overall "very" or "rather" satisfied with the handling of the intraoral scanning method, and 18 (58%) preferred digital to alginate impressions from the dentist's perspective. From the "patient's" perspective, the students did not report any significant differences between the two methods. However, the impression tray in conventional impressions reduced "patient" comfort significantly more than the camera in digital impressions (Z = - 3.496, p < 0.001). CONCLUSIONS Dental students were able to practice both conventional alginate and modern digital impressions without prior knowledge of intraoral impression techniques after basic training and an introduction from dentists. Students reported a preference for the digital technique. Implementing digital intraoral impressions into undergraduate training is recommended to familiarise students with this rapidly developing digital technique at an early stage.
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Affiliation(s)
- Timm C. Schott
- Department of Orthodontics and Orofacial Orthopedics, University Hospital of Dentistry, Oral Medicine, and Maxillofacial Surgery, Eberhard Karls University Tübingen, Osianderstr. 2-8, 72076 Tübingen, Germany
| | - Rahima Arsalan
- Department of Orthodontics and Orofacial Orthopedics, University Hospital of Dentistry, Oral Medicine, and Maxillofacial Surgery, Eberhard Karls University Tübingen, Osianderstr. 2-8, 72076 Tübingen, Germany
| | - Katja Weimer
- Department of Psychosomatic Medicine and Psychotherapy, University Hospital Tübingen, Tübingen, Germany
- Department of Psychosomatic Medicine and Psychotherapy, Ulm University Medical Center, Ulm, Germany
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Kioleoglou I, Pissiotis A, Konstantinos M. Accuracy of fit of implant-supported bars fabricated on definitive casts made by different dental stones. J Clin Exp Dent 2018; 10:e252-e263. [PMID: 29721227 PMCID: PMC5923891 DOI: 10.4317/jced.54603] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/26/2017] [Accepted: 02/17/2018] [Indexed: 11/17/2022] Open
Abstract
BACKGROUND The purpose of this study was to evaluate the accuracy of fitting of an implant supported screw-retained bar made on definitive casts produced by 4 different dental stone products. MATERIAL AND METHODS The dental stones tested were QuickRock (Protechno), FujiRock (GC), Jade Stone (Whip Mix) and Moldasynt (Heraeus). Three external hexagon implants were placed in a polyoxymethylene block. Definitive impressions were made using monophase high viscosity polyvinylsiloxane in combination with custom trays. Then, definitive models from the different types of dental stones were fabricated. Three castable cylinders with a machined non-enganging base were cast and connected with a very small quantity of PMMA to a cast bar, which was used to verify the marginal discrepancies between the abutments and the prosthetic platforms of the implants. For that purpose special software and a camera mounted on an optical microscope were used. The gap was measured by taking 10 measurements on each abutment, after the Sheffield test was applied. Twelve definitive casts were fabricated for each gypsum product and 40 measurements were performed for each cast. Mean, minimum, and maximum values were calculated. The Shapiro-Wilk test of normality was performed. Mann-Whitney test (P<.06) was used for the statistical analysis of the measurements. RESULTS The non-parametric Kruskal-Wallis test revealed a statistically significant effect of the stone factor on the marginal discrepancy for all Sheffield test combinations: 1. Abutment 2 when screw was fastened on abutment 1 (χ2=3, df=35.33, P<0.01), 2. Abutment 3 when the screw was fastened on abutment 1 (χ2=3, df=37.74, P<0.01), 3. Abutment 1 when the screw was fastened on abutment 3 (χ2=3, df=39.79, P<0.01), 4. Abutment 2 when the screw was fastened on abutment 3 (χ2=3, df=37.26, P<0.01). CONCLUSIONS A significant correlation exists between marginal discrepancy and different dental gypsum products used for the fabrication of definitive casts for implant supported bars. The smallest marginal discrepancy was noted on implant supported bars fabricated on definitive casts made by Type III mounting stone. The biggest marginal discrepancy was noted on implant supported bars fabricated on definitive casts made by Type V dental stone. The marginal discrepancies presented on implant supported bars fabricated on definitive casts made by two types of Type IV dental stone were not significantly different. Key words:Dental implant, passive fit, dental stones, marginal discrepancy.
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Affiliation(s)
- Ioannis Kioleoglou
- DDS, MS, Former postgraduate resident, Dept. of Prosthodontics, School of Dentistry, Faculty of Health Sciences, Aristotle University, Thessaloniki, Greece. ITI Scholar and Honorary Clinical Research Fellow, Department of Restorative Dentistry and Adult Oral Health, Barts and the London School of Medicine and Dentistry, Queen Mary University of London, United Kingdom
| | - Argirios Pissiotis
- DDS, MS, PhD, Professor and Chair, Division of Removable Prosthodontics, Dept. of Prosthodontics, School of Dentistry, Faculty of Health Sciences, Aristotle University, Thessaloniki, Greece
| | - Michalakis Konstantinos
- DDS, MSc, PhD, FACP, Associate Professor and Clinical Director of Postgraduate Prosthodontics, Dept. of Prosthodontics, School of Dentistry, Faculty of Health Sciences, Aristotle University, Thessaloniki, Greece. Adjunct Associate Professor, Division of Postgraduate Prosthodontics, Dept. of Prosthodontics, Tufts University School of Dental Medicine, Boston, MA, USA
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Pramodh NR, Kumar CNV, Pradeep MR, Naik R, Mahesh CS, Kumari MR. Comparative Evaluation of Tensile Strength in Die Stone Incorporated with Sodium and Calcium Hypochlorite as Disinfectants: An in vitro Study. J Contemp Dent Pract 2017; 18:1185-1189. [PMID: 29208796 DOI: 10.5005/jp-journals-10024-2197] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
AIM The aim of this study was to evaluate the tensile strength of die stone incorporated with sodium and calcium hypochlorite as disinfectants. MATERIALS AND METHODS Two commercially available type IV die stone (Kalrock: Kalabhai Karson Pvt., Ltd and Pearlstone: Asian Chemicals) and two commercially available disinfectant solutions (sodium hypochlorite and calcium hypochlorite: Beachem Laboratory Chemical Private Limited, Chennai and Leo Chem Private Limited, Bengaluru) were used in this study, and the tensile strength was measured using Lloyd's Universal Testing Machine. RESULTS The results show that incorporating the disinfecting solutions decreases the tensile strength of both products. The effect of decreasing tensile strength on type IV gypsum product is seen more in calcium hypochlorite when compared with sodium hypochlorite disinfecting solution, and the tensile strength of Kalrock specimens is higher than Pearlstone specimens after disinfecting with sodium hypochlorite and calcium hypochlorite solution. The statistical results also show significant results in all the groups when compared with the control group. CONCLUSION The incorporation of sodium and calcium hypochlorite disinfecting solutions is not an encouraging method for both die materials as it reduces the tensile strength of type IV gypsum product. Tensile strength of Kalstone® die material is superior than Pearlstone® die material after mixing with sodium hypochlorite and calcium hypochlorite. CLINICAL SIGNIFICANCE According to the recommendations of Americans with Disability Act (ADA) and the Centers for Disease Control and Prevention, disinfecting the whole cast without or minimal changes in physical and mechanical properties was the motto of the study. The tensile strength in type IV gypsum product plays a most important role in retrieval of cast from impression, especially in narrow tooth preparation. This study reveals that incorporating method of disinfecting solutions is not recommended as it reduces the tensile strength.
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Affiliation(s)
- N R Pramodh
- Department of Prosthodontics, Subbaiah Institute of Dental Sciences, Shimoga, Karnataka, India
| | - C N Vijay Kumar
- Department of Conservative and Endodontics, Subbaiah Institute of Dental Sciences, Shimoga, Karnataka, India, e-mail:
| | - M R Pradeep
- Department of Prosthodontics, Subbaiah Institute of Dental Sciences, Shimoga, Karnataka, India
| | - Ravi Naik
- Department of Prosthodontics, Subbaiah Institute of Dental Sciences, Shimoga, Karnataka, India
| | - C S Mahesh
- Department of Prosthodontics, Subbaiah Institute of Dental Sciences, Shimoga, Karnataka, India
| | - Manju R Kumari
- Department of Conservative and Endodontics, Subbaiah Institute of Dental Sciences, Shimoga, Karnataka, India
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Interproximal distance analysis of stereolithographic casts made by CAD-CAM technology: An in vitro study. J Prosthet Dent 2017; 118:624-630. [PMID: 28477918 DOI: 10.1016/j.prosdent.2017.01.027] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/22/2016] [Revised: 01/27/2017] [Accepted: 01/27/2017] [Indexed: 11/22/2022]
Abstract
STATEMENT OF PROBLEM The accuracy of interproximal distances of the definitive casts made by computer-aided design and computer-aided manufacturing (CAD-CAM) technology is not yet known. PURPOSE The purpose of this in vitro study was to compare the interproximal distances of stereolithographic casts made by CAD-CAM technology with those of stone casts made by the conventional method. MATERIAL AND METHODS Dentoform teeth were prepared for a single ceramic crown on the maxillary left central incisor, a 3-unit fixed dental prosthesis (FDP) on the second premolar for a metal-ceramic crown, and a maxillary right first molar for a metal crown. Twenty digital intraoral impressions were made on the dentoform with an intraoral digital impression scanner. The digital impression files were used to fabricate 20 sets of stereolithographic casts, 10 definitive casts for the single ceramic crown, and 10 definitive casts for the FDP. Furthermore, 20 stone casts were made by the conventional method using polyvinyl siloxane impression material with a custom tray. Each definitive cast for stereolithographic cast and stone cast consisted of removable die-sectioned casts (DC) and nonsectioned solid casts (SC). Measurements of interproximal distance of each cast were made using CAD software to provide mean ±standard deviation (SD) values. Data were first analyzed by repeated measures analysis of variance (ANOVA), using different methods of cast fabrication (stone and stereolithography) as one within subject factor and different cast types (DC and SC) as another within subject factor. Post hoc analyses were performed to investigate the differences between stone and stereolithographic casts depending upon the results from the repeated measures ANOVA (α=.05). RESULTS Analysis of interproximal distances showed the mean ±SD value of the single ceramic crown group was 31.2 ±24.5 μm for stone casts and 261.0 ±116.1 μm for stereolithographic casts, whereas the mean ±SD value for the FDP group was 46.0 ±35.0 μm for stone casts and 292.8 ±216.6 μm for stereolithographic casts. For both the single ceramic crown and the FDP groups, there were significant differences in interproximal distances between stereolithographic casts and stone casts (P<.001). In addition, the comparisons of DC with SC of stone and stereolithographic casts for the single ceramic crown and FDP groups demonstrated there was statistically significant differences among interproximal distances between DC stereolithographic casts and SC stereolithographic casts only for the FDP group (P<.001). CONCLUSIONS For both the single ceramic crown and the FDP groups, the stereolithographic cast group showed significantly larger interproximal distances than the stone cast group. In terms of the comparison between DC and SC, DC stereolithographic casts for the FDP group only showed significantly larger interproximal values than those of the SC stereolithographic casts for the FDP group.
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De Cesero L, de Oliveira EMN, Burnett Junior LH, Papaléo RM, Mota EG. The addition of silica nanoparticles on the mechanical properties of dental stone. J Prosthet Dent 2017; 118:535-539. [PMID: 28274469 DOI: 10.1016/j.prosdent.2017.01.001] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/08/2016] [Revised: 12/31/2016] [Accepted: 01/03/2017] [Indexed: 10/20/2022]
Abstract
STATEMENT OF PROBLEM The current application of nanotechnology in dentistry is limited to nanoparticles incorporated into adhesive systems and composite resins. Dental stone is a widely used material, and the incorporation of silica nanoparticles is still unexplored. PURPOSE The purpose of this in vitro study was to evaluate the mechanical properties of dental stone after the addition of silica nanoparticles in different concentrations. MATERIAL AND METHODS A total of 180 specimens were prepared, 90 for each dental stone (Durone and Fuji Rock). For the control group (CG), no silica particles were added, while test group TGnI had silica nanoparticles added to 1 wt%, and test group TGnV had silica nanoparticles added to 5 wt%. The roughness, diametral tensile strength (DTS), and compressive strength were measured 24 hours after the start of spatulation. RESULTS The mean roughness values for Durone were 0.55, 0.36, and 0.28 μm for CG, TGnI, and TGnV; for Fuji Rock, the mean roughness values were 0.47 for CG, 0.31 for TGnI, and 0.35 μm for TGnV. The mean DTS values for Durone were 6.0, 5.1, and 5.0 MPa for CG, TGnI, and TGnV, respectively, and for Fuji Rock, the mean DTS values were 6.4, 5.2, and 4.5 MPa for CG, TGnI, and TGnV, respectively. The mean compressive strength values for Durone were 35.4, 32.7, and 32.4 MPa for CG, TGnI, and TGnV, respectively, and for Fuji Rock, the mean compressive strength values were 42.9, 31.2, and 29.8 MPa for CG, TGnI, and TGnV respectively. CONCLUSIONS Surface roughness was statistically lower for the Durone and Fuji Rock stones (P<.001) when silica nanoparticles were added. The addition of silica nanoparticles did not significantly affect the DTS and compressive strength of Durone compared with CG (P>.05) but did affect the DTS of Fuji Rock when 5 wt% was added and the compressive strength in both concentrations (P<.05).
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Affiliation(s)
- Leonardo De Cesero
- Postgraduate student, Postgraduate in Dental Materials, Department of Restorative Dentistry, Pontifical Catholic University of Rio Grande do Sul (PUCRS), Porto Alegre, Brazil.
| | - Elisa Magno Nunes de Oliveira
- Postgraduate student, Department of Physical, Pontifical Catholic University of Rio Grande do Sul (PUCRS), Porto Alegre, Brazil
| | - Luiz Henrique Burnett Junior
- Professor, Department of Restorative Dentistry, Pontifical Catholic University of Rio Grande do Sul (PUCRS), Porto Alegre, Brazil
| | - Ricardo Meurer Papaléo
- Coordinator, Interdisciplinary Center of Nanoscience and Micro-Nanotechnology, Pontifical Catholic University of Rio Grande do Sul (PUCRS), Porto Alegre, Brazil
| | - Eduardo Gonçalves Mota
- Professor, Department of Restorative Dentistry, Pontifical Catholic University of Rio Grande do Sul (PUCRS), Porto Alegre, Brazil
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Niekawa CT, Kreve S, A'vila GB, Godoy GG, Eduardo Vieira da Silva JR, Dias SC. Analysis of the Mechanical Behavior and Surface Rugosity of Different Dental Die Materials. J Int Soc Prev Community Dent 2017; 7:34-40. [PMID: 28316947 PMCID: PMC5343681 DOI: 10.4103/2231-0762.200706] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/10/2016] [Accepted: 01/04/2017] [Indexed: 11/04/2022] Open
Abstract
AIM This work evaluated the mechanical and surface behavior of different die materials. The studied materials are polyurethane resin Exakto-Form (Bredent), Gypsum type IV, Fuji Rock EP (Gc), and Durone (Dentsply). MATERIALS AND METHODS Two metallic matrices molded in polyvinyl siloxane provided 30 cylindrical test specimens for the diametral compression test and 30 hemispherical test specimens for the surface rugosity test. The cylindrical test specimens were submitted to tests of diametral compression strength using a DL2000 universal assay machine, with a load cell of 2000 Kgf and constant speed of 1 mm/min connected to the software. Kruskal-Wallis and Dunn's nonparametric tests were used to analyze the results. The hemispheres were submitted to the surface rugosity assay using a SJ201-P rugosimeter with a sensitivity of 300 μm, speed of 0.5 mm/s, and cut-off of 0.8 mm, and the readings were taken on the convex surface of the test specimens and metallic matrix. Results were analyzed using with Fisher's least significant differences test (LSD) and Dunnett's test. RESULTS Kruskal-Wallis test showed significant difference between die materials for diametral compression strength (P = 0.002). Dunn's test showed significantly higher values for modified polyurethane resin (Exakto-Form). The gypsum type IV, which did not significantly differ regarding diametral compression strength, showed 34.0% (Durone) and 42.7% (Fuji Rock) lower values in comparison to Exakto-Form. CONCLUSION Within the parameters adopted in this study, it is possible to conclude that Exakto-Form polyurethane resin showed higher resistance to compression and was closer to the metallic matrix rugosity, and, along with the gypsum type IV Durone, showed better reproducibility of details relative to the Fuji Rock.
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Affiliation(s)
- Ciro T. Niekawa
- Department of Restorative Dentistry, São Leopoldo Mandic Dental School, Campinas-São Paulo, Brazil
| | - Simone Kreve
- Department of Restorative Dentistry, São Leopoldo Mandic Dental School, Campinas-São Paulo, Brazil
| | - Gisseli Bertozzi A'vila
- Department of Restorative Dentistry, São Leopoldo Mandic Dental School, Campinas-São Paulo, Brazil
| | - Gilmar Gil Godoy
- Department of Restorative Dentistry, São Leopoldo Mandic Dental School, Campinas-São Paulo, Brazil
| | | | - Sergio Candido Dias
- Department of Restorative Dentistry, São Leopoldo Mandic Dental School, Campinas-São Paulo, Brazil
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Livas C, Halazonetis DJ, Booij JW, Katsaros C, Ren Y. Does fixed retention prevent overeruption of unopposed mandibular second molars in maxillary first molar extraction cases? Prog Orthod 2016; 17:6. [PMID: 26798065 PMCID: PMC4722044 DOI: 10.1186/s40510-016-0119-z] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/23/2015] [Accepted: 01/13/2016] [Indexed: 11/26/2022] Open
Abstract
Background The objective of this study was to investigate whether multistranded fixed retainers prevented overeruption of unopposed mandibular second molars in maxillary first molar extraction cases. Methods The panoramic radiographs of 65 Class II Division 1 Caucasian Whites (28 females, 37 males) consecutively treated with bilateral maxillary first molar extraction and the Begg technique, and with records taken after treatment (T1) and in retention (T2), were withdrawn from private practice records. After appliance removal, mandibular second molars were retained with sectional wires till at least T2 in case of lack of occlusal contact with the antagonist. The subjects were assigned to study-retention and control-nonretention groups based on the retention status of mandibular second molars. Radiographic analysis was carried out to determine inclination of mandibular molars and the resulting movement of second molar centroids. Parametric and nonparametric tests were performed to assess the changes between T1 and T2. Results No statistically significant differences in molar inclination were observed between groups and timepoints (P > 0.05). There were no statistically significant differences in molar movement percentages (P > 0.05) irrespective of whether fixed retention had been used or not. Conclusions No significant eruption occurred in unopposed mandibular second molars bonded with fixed sectional retainers compared to molars partially occluded with the antagonists without fixed retention. Given the study limitations, fixed retention should be considered with caution in restricting tooth overeruption in unopposed molars.
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Affiliation(s)
- Christos Livas
- Department of Orthodontics, University of Groningen, University Medical Center Groningen, Hanzeplein 1, Triade gebouw, Ingang 24, 9700 RB, Groningen, The Netherlands.
| | - Demetrios J Halazonetis
- Department of Orthodontics, School of Dentistry, National and Kapodistrian University of Athens, 2 Thivon Str, 115 27, Goudi, Athens, Greece
| | - Johan W Booij
- Private practice, Schelluinsevliet 5, 4203 NB, Gorinchem, The Netherlands
| | - Christos Katsaros
- Department of Orthodontics and Dentofacial Orthopedics, School of Dental Medicine, University of Bern, Freiburgstrasse 7, CH-3010, Bern, Switzerland
| | - Yijin Ren
- Department of Orthodontics, University of Groningen, University Medical Center Groningen, Hanzeplein 1, Triade gebouw, Ingang 24, 9700 RB, Groningen, The Netherlands
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12
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Kim KB, Kim JH, Kim SH. Impact of surface roughness of gypsum materials on adaptation of zirconia cores. J Adv Prosthodont 2015; 7:199-206. [PMID: 26140171 PMCID: PMC4486615 DOI: 10.4047/jap.2015.7.3.199] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2014] [Revised: 01/30/2015] [Accepted: 02/09/2015] [Indexed: 11/22/2022] Open
Abstract
PURPOSE The present study investigated the influences of various gypsum materials on the precision of fit of CAD/CAM-fabricated prostheses and analyzed their correlation with surface roughness. MATERIALS AND METHODS The master model of the mandibular right first molar was replicated, and four experimental groups based on two types of Type IV stone (GC Fujirock EP, Die keen) and two types of scannable stone (Aesthetic-Basegold, Everest Rock) were created to include a total of 40 specimens, 10 in each group. The surface roughness of the working models for the respective experimental groups was measured. Once the zirconia cores had been fabricated, the marginal and internal fits were measured with a digital microscope using the silicone replica technique. The mean and standard deviation of the respective points of measurement were computed and analyzed through the one-way ANOVA and Tukey's HSD test. The correlation between surface roughness and the precision of fit of the zirconia core was analyzed using the Pearson correlation analysis (α=.05). RESULTS The zirconia cores fabricated from the scannable stone working models exhibited a superior precision of fit as compared to those fabricated from the Type IV stone working models. The correlation analysis results showed a clear positive correlation between surface roughness and the precision of fit of zirconia cores in all of the experimental groups (P<.05). CONCLUSION The results confirmed that the surface roughness of dental working models has a decisive influence on the precision of fit of zirconia cores.
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Affiliation(s)
- Ki-Baek Kim
- Institute for Health Science, College of Health Science, Korea University, Seoul, Republic of Korea
| | - Jae-Hong Kim
- Institute for Health Science, College of Health Science, Korea University, Seoul, Republic of Korea
| | - Sa-Hak Kim
- Department of Dental Technology, School of Medical and Public Health, Kyungdong University, Goseong, Gangwondo, Republic of Korea
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Kim JH, Kim KB, Kim WC, Rhee HS, Lee IH, Kim JH. Influence of various gypsum materials on precision of fit of CAD/CAM-fabricated zirconia copings. Dent Mater J 2015; 34:19-24. [PMID: 25748454 DOI: 10.4012/dmj.2014-141] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
The clinical applicability of CAD/CAM-fabricated zirconia copings is tested using working models made from four different highstrength Type IV gypsum materials. Each of the four materials was used to fabricate 15 zirconia copings. Precision of fit was measured with a digital electron microscope using the silicone replica technique. The mean and standard deviation of each reference point were analyzed using the one-way analysis of the variance (ANOVA) and Tukey's honest significant difference (HSD) tests (α=0.05). The overall marginal and internal fits of the zirconia copings were as follows: GS (GS: Grey Stone) group: 91.43 μm, LS (LS: Light green Stone) Group: 87.89 μm, RS (RS: Red Stone) Group: 88.75 μm, BS (BS: Beige Stone) Group: 82.78 μm. There were no significant differences between the mean adaptations of the gypsum varieties (p>0.05). This confirmed that the type of gypsum material used does not determine the precision of fit of a prosthesis.
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Affiliation(s)
- Jae-Hong Kim
- Department of Dental Laboratory Science and Engineering, College of Health Science, Korea University
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14
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De Cesero L, Mota EG, Burnett LH, Spohr AM. The influence of postpouring time on the roughness, compressive strength, and diametric tensile strength of dental stone. J Prosthet Dent 2014; 112:1573-7. [PMID: 25258259 DOI: 10.1016/j.prosdent.2013.07.032] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2012] [Revised: 06/20/2013] [Accepted: 07/06/2013] [Indexed: 11/15/2022]
Abstract
STATEMENT OF PROBLEM The optimum time after pouring a dental impression before removing the dental cast is unknown with regard to the strength and roughness of the stone. Setting times and the commercial products used are important variables. PURPOSE The purpose of this study was to evaluate the effect of postpouring time on the surface roughness, compressive strength, and diametric tensile strength of Type IV dental stone. MATERIAL AND METHODS A total of 270 specimens were prepared from 3 commercial brands of dental stone (Durone, Fuji Rock, and Tuff Rock). Surface roughness, compressive strength, and diametric tensile strength were assessed at 1 hour, 24 hours, and 7 days after pouring. Specimens 6 mm in diameter and 3 mm in height were produced for roughness and diametric tensile strength tests. Specimens 3 mm in diameter and 6 mm in height were used to measure compressive strength. The results were analyzed with the general linear model and Tukey honestly significant difference test (α=.05). RESULTS The surface roughness measured for the different types of dental stone tested varied from 0.3 μm (Durone, 1 hour) to 0.64 μm (Tuff Rock, 7 days). The diametric tensile strength ranged from 3.94 MPa (Tuff Rock, 1 hour) to 9.20 MPa (Durone, 7 days). The compressive strength varied from 26.67 MPa (Durone, 1 hour) to 65.14 MPa (Fuji Rock, 7 days). CONCLUSIONS Surface roughness (P=.005), diametric tensile strength (P=.001), and compressive strength (P=.001) increased significantly with time after pouring. The commercial brand used affected roughness (P=.001), diametric tensile strength (P=.004), and compressive strength (P=.001). Tuff Rock exhibited the highest surface roughness. The highest diametric tensile strength values were recorded for Durone and Fuji Rock. Fuji Rock exhibited the highest compressive strength.
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Affiliation(s)
- Leonardo De Cesero
- Postgraduate student, Postgraduate Program in Dentistry, Pontifical Catholic University of Rio Grande do Sul, Porto Alegre, Brazil
| | - Eduardo Gonçalves Mota
- Associate Professor, Clinical Department, Pontifical Catholic University of Rio Grande do Sul, Porto Alegre, Brazil.
| | - Luiz Henrique Burnett
- Associate Professor, Clinical Department, Pontifical Catholic University of Rio Grande do Sul, Porto Alegre, Brazil
| | - Ana Maria Spohr
- Associate Professor, Clinical Department, Pontifical Catholic University of Rio Grande do Sul, Porto Alegre, Brazil
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Yuzbasioglu E, Kurt H, Turunc R, Bilir H. Comparison of digital and conventional impression techniques: evaluation of patients' perception, treatment comfort, effectiveness and clinical outcomes. BMC Oral Health 2014; 14:10. [PMID: 24479892 PMCID: PMC3913616 DOI: 10.1186/1472-6831-14-10] [Citation(s) in RCA: 243] [Impact Index Per Article: 24.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/25/2013] [Accepted: 01/29/2014] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND The purpose of this study was to compare two impression techniques from the perspective of patient preferences and treatment comfort. METHODS Twenty-four (12 male, 12 female) subjects who had no previous experience with either conventional or digital impression participated in this study. Conventional impressions of maxillary and mandibular dental arches were taken with a polyether impression material (Impregum, 3 M ESPE), and bite registrations were made with polysiloxane bite registration material (Futar D, Kettenbach). Two weeks later, digital impressions and bite scans were performed using an intra-oral scanner (CEREC Omnicam, Sirona). Immediately after the impressions were made, the subjects' attitudes, preferences and perceptions towards impression techniques were evaluated using a standardized questionnaire. The perceived source of stress was evaluated using the State-Trait Anxiety Scale. Processing steps of the impression techniques (tray selection, working time etc.) were recorded in seconds. Statistical analyses were performed with the Wilcoxon Rank test, and p < 0.05 was considered significant. RESULTS There were significant differences among the groups (p < 0.05) in terms of total working time and processing steps. Patients stated that digital impressions were more comfortable than conventional techniques. CONCLUSIONS Digital impressions resulted in a more time-efficient technique than conventional impressions. Patients preferred the digital impression technique rather than conventional techniques.
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Affiliation(s)
- Emir Yuzbasioglu
- Department of Prosthodontics, School of Dentistry, Istanbul Medipol University, Istanbul, Turkey.
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16
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Nandini Y, Vinitha KB, Manvi S, Smitha M. Comparison of dimensional accuracy of four different die materials before and after disinfection of the impression: an in vitro study. J Contemp Dent Pract 2013; 14:668-74. [PMID: 24309347 DOI: 10.5005/jp-journals-10024-1383] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
BACKGROUND This study was conducted to compare the linear dimensional accuracy of die materials before and after disinfection of the impression. Type IV and V conventional dental stone, type IV-resin impregnated and copper-plated die materials were studied. MATERIALS AND METHODS A stainless-steel master die analogs to a complete veneer crown preparation with three scribed lines (I: vertical, II and III: horizontal) was machined and measurements were made from these scribed reference lines. Impressions were made with monophase addition silicone impression material for each of the specimens. 2% glutaraldehyde was used as a disinfectant. The fabricated dies were measured to the nearest 0.0001 mm. ANOVA and post hoc was carried out using Scheffe multiple comparison test at significance level of 0.05. RESULTS Type IV resin-impregnated dental stone and copperplated dies approximated the dimensions of the master die. Type IV and V conventional dental stone dies showed greater variation in measurements. Statistically significant differences were observed for type IV resin-impregnated and copper-plated dies in dimension I and III. For dimension II no significant differences were found for dies fabricated from four die materials. A one-way analysis of variance indicated no statistical significant differences among the two groups of dies fabricated from disinfectant treated impressions and those fabricated from nondisinfectant treated impressions. CONCLUSION Type IV resin-impregnated dental stone and copper-plated dies are dimensionally more accurate than type IV and V conventional dental stone die materials. No significant linear distortion in the dies fabricated from the disinfected impressions was observed.
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Affiliation(s)
- Yamini Nandini
- Reader, Department of Prosthodontics, KLE Society's Institute of Dental Sciences, Bengaluru, Karnataka, India
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17
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Michalakis KX, Asar NV, Kapsampeli V, Magkavali-Trikka P, Pissiotis AL, Hirayama H. Delayed linear dimensional changes of five high strength gypsum products used for the fabrication of definitive casts. J Prosthet Dent 2012; 108:189-95. [DOI: 10.1016/s0022-3913(12)60146-2] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
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18
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Acar O, Erkut S, Lakshmipathy M. Surface detail reproduction under simulated pulpal pressure: a 3-dimensional optical profilometer and scanning electron microscopy evaluation. J Prosthet Dent 2012; 108:102-13. [PMID: 22867807 DOI: 10.1016/s0022-3913(12)60116-4] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
STATEMENT OF PROBLEM It is not clear whether more hydrophilic impression materials are better able to copy and transfer dentin surface detail than less hydrophilic ones. PURPOSE The purpose of this study was to evaluate the reproduction of dentin surface detail by means of hydrophobic and hydrophilic elastomeric impression materials under simulated pulpal pressure and their ability to transfer surface detail onto casts produced from such impressions. MATERIAL AND METHODS The wettability of the impression materials (n=8) was determined by contact angle measurement with an evolution period of 135 seconds. Dentin moisture was provided by means of pulpal pressure simulation, and objective analyses were performed by measuring the average roughness value (Ra) with a 3-D optical profilometer (n=10). One specimen from each group was analyzed with scanning electron microscopy. Contact-angle values were analyzed with a repeated measures ANOVA, and detail reproduction was tested with 3-way ANOVA (α=.05). The Bonferroni correction was used to control Type I error for follow-up analyses. RESULTS Contact angle measurements revealed significant differences depending on the impression material used and time of the measurement (P<.001). The Ra values of the hydrophilic impression materials, which were made from dry specimens, and the pulpal pressure simulated dentin surfaces did not differ from the dentin surfaces (P>.013). The hydrophobic impression material showed similar detail reproduction ability in a dry field, but loss of detail (evaluated subjectively) and increased roughness values (evaluated objectively) were recorded in a moisturized field (P=.004). Polyurethane-based cast material successfully reproduced the surface texture (P≥.006), whereas Type IV gypsum material was unable to reproduce this texture to the same extent. CONCLUSIONS The hydrophilic impression materials tested showed similar ability to reproduce detail under simulated pulpal pressure. Polyurethane-based cast material successfully reproduced the surface texture.
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Affiliation(s)
- Ozlem Acar
- Department of Prosthetics, Faculty of Dentistry, Baskent University, Ankara, Turkey.
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19
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Gujjarlapudi MC, Reddy SV, Madineni PK, Ealla KKR, Nunna VN, Manne SD. Comparative evaluation of few physical properties of epoxy resin, resin-modified gypsum and conventional type IV gypsum die materials: an in vitro study. J Contemp Dent Pract 2012; 13:48-54. [PMID: 22430693 DOI: 10.5005/jp-journals-10024-1094] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
Abstract
AIM To compare and evaluate few physical properties of epoxy resin, resin-modified gypsum and conventional type-IV gypsum die material. MATERIALS AND METHODS In the present study, dimensional accuracy, surface detail reproduction and transverse strength of three die materials like epoxy resin (Diemet-E), resin-modified gypsum (Synarock) and conventional type-IV gypsum (Ultrarock) are analyzed. For dimensional accuracy, master die (Bailey's die) is used and calibrations were made with digital microscope. For surface detail reproduction and transverse strength, rectangular stainless steel master die (Duke's die) was used and calibrations were made with Toolmaker's microscope and Instron universal testing machine respectively. One-way analysis of variance (ANOVA) was performed on the means and standard deviation for groups of each test. RESULTS The results of the study showed statistically significant difference among these materials in dimensional accuracy, surface detail reproduction and transverse strength. CONCLUSION Epoxy resin exhibited superiority in dimensional accuracy, surface detail reproduction and transverse strength and is nearest to the standards of accurate die material.
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20
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Queiroz DA, Cunha LG, Duarte JLP, Neves ACC, Silva-Concílio LRD. Influence of the casting material on the dimensional accuracy of dental dies. Braz Oral Res 2011. [DOI: 10.1590/s1806-83242011005000011] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
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21
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Prisco R, Cozzolino G, Vigolo P. Dimensional accuracy of an epoxy die material using different polymerization methods. J Prosthodont 2008; 18:156-61. [PMID: 19054302 DOI: 10.1111/j.1532-849x.2008.00399.x] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022] Open
Abstract
PURPOSE Shrinkage of resinous die materials during setting reaction limits their acceptance, even though these materials show several advantages compared to stone die materials with respect to strength, abrasion resistance, and detail reproduction. The purpose of this study was to determine if retarding the setting reaction during polymerization and altering the base-to-catalyst ratio, as suggested by previous studies, can be recommended for resinous die materials to reduce the inaccuracy in transferring the spatial position of teeth or implants from the oral cavity to the master cast. MATERIALS AND METHODS A Blue Star Type E epoxy resin die material was tested. A reference triangular metal master die was fabricated. Forty medium-consistency polyether impressions of this model were made. Four groups (S, M, N, P) were compared, and ten dies were fabricated for each group. In the S group, the epoxy resin die material was manipulated according to the manufacturer's instructions; in the other three groups, the epoxy resin die material was manipulated by retarding the setting reaction and by modifying the epoxy resin base/activator ratio. RESULTS One-way ANOVA revealed significant differences between the four groups of the epoxy resin die material (p < 0.0001). Tukey's multiple comparisons test (p < 0.05) revealed that none of the resin groups was similar to the metal master die for each of the tested dimensions (A, B, and C). For the specific dimension C, however, the P group was statistically closer to the metal master die than the S group. CONCLUSION The epoxy resin die material tested in this research did not improve its dimensional accuracy following retarding polymerization or modifying the epoxy resin base/activator ratio. The epoxy resin material exhibited higher contraction variability across all tested groups. This shrinkage can significantly affect the dimension of the master cast.
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Affiliation(s)
- Rosario Prisco
- Department of Clinical Odontostomatology, University of Padova, Institute of Clinical Dentistry, Padova, Italy
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22
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Effect of mixing methods on the physical properties of dental stones. J Dent 2008; 36:736-44. [DOI: 10.1016/j.jdent.2008.05.010] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/13/2008] [Revised: 05/12/2008] [Accepted: 05/13/2008] [Indexed: 11/18/2022] Open
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Persson ASK, Andersson M, Odén A, Sandborgh-Englund G. Computer aided analysis of digitized dental stone replicas by dental CAD/CAM technology. Dent Mater 2008; 24:1123-30. [PMID: 18336900 DOI: 10.1016/j.dental.2008.01.008] [Citation(s) in RCA: 60] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/11/2007] [Revised: 12/28/2007] [Accepted: 01/07/2008] [Indexed: 10/22/2022]
Abstract
OBJECTIVES To determine the reproducibility of digitized dental stone replicas compared to the master model and the reliability of the computer aided analysis. METHODS Four master dies, prepared for complete crowns were fabricated in presintered yttria-stabilized tetragonal zirconia (Y-TZP). Eight vinyl polysiloxane impressions (PROVIL novo; Heraeus Kulzer) were taken of each die and stone replicas were poured in type IV stone (Vel-Mix Stone; Kerr). The master dies and the stone replicas were digitized in a touch-probe scanner (Procera Forte; Nobel Biocare AB), to create triangulated surface-models. The point-cloud from the first of the repeated digitizations of each master die was used as CAD-reference-models (CRM). Discrepancies between the points in the triangulated surface-models and the corresponding CRM were measured by a matching-software (CopyCAD 6.504 SP2; Delcam Plc). The distribution of the discrepancies was analyzed and presented in color-difference-maps. RESULTS The precision of the measuring method, presented as the repeatability coefficient, ranged between 7 and 16 microm (entire surface), whereas the analysis of the stone replicas revealed a precision (repeatability coefficient) ranging from 19 to 26 microm. The accuracy of the replica to master (the mean discrepancy) ranged from 0.5 to 2.0 microm (95% confidence interval 1.5-2.9 microm). SIGNIFICANCE The greatest precision of the measurement was seen in the jacket surface of the die. The size of the stone replicas varied and the repeatability coefficient was on average 15 microm (2-25 microm) greater for the replica-to-master alignment than the repeated digitizations of the master.
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Affiliation(s)
- Anna S K Persson
- Institute of Odontology, Karolinska Institutet, Huddinge, Sweden
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24
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Sabooni M, . JG. Comparison of Tap Water, Distilled Water and Slurry Water on Surface Hardness of Gypsum Die. JOURNAL OF MEDICAL SCIENCES 2007. [DOI: 10.3923/jms.2007.1350.1353] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
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Fonseca RB, Correr-Sobrinho L, Fernandes-Neto AJ, Quagliatto PS, Soares CJ. The influence of the cavity preparation design on marginal accuracy of laboratory-processed resin composite restorations. Clin Oral Investig 2007; 12:53-9. [PMID: 17690921 DOI: 10.1007/s00784-007-0145-9] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2007] [Accepted: 07/19/2007] [Indexed: 11/26/2022]
Abstract
The aim of this study was to evaluate the influence of different cavity preparation designs on marginal accuracy of laboratory-processed resin composite restored teeth. Eighty mandibular human third molars were selected. There were two experimental factors, occlusal isthmus width (narrow vs wide) and cuspal coverage (inlay, one-cusp onlay, two-cusp onlay, and all-cusp onlay), resulting on eight groups (N = 10). Indirect composite restorations (SR Adoro, Ivoclar-Vivadent) were manufactured and positioned over each respective preparation. Marginal accuracy evaluation was accomplished using a stereomicroscope at three points on buccal, lingual, mesial, and distal regions with 40x magnification. The results showed significant differences (P = 0.00) with wide inlay showing the best overall marginal accuracy and narrow inlay the worst one. Two-way analysis of variance (ANOVA) showed significant differences when considering the factor occlusal isthmus width (P = 0.00). In general, preparations with wide occlusal isthmus presented better results than narrow ones, except for wide all-cusp onlays; however, the test failed to show differences when considering the cuspal coverage (P = 0.42) or the interaction between both factors (P = 0.30). The effect of occlusal width extension on marginal accuracy of indirect composite resin restorations is significant, with lower values of gaps width in wide preparations, but since in a clinical situation this would mean greater removal of sound tooth structure, less-aggressive preparations combined with other restorative procedures seem to be more feasible.
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Affiliation(s)
- Rodrigo Borges Fonseca
- Department of Dental Materials, Piracicaba Dental School, University of Campinas, Campinas, Brazil
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Abstract
PURPOSE The purpose of this study was to compare the linear dimensional accuracy and the handling characteristics of 7 die materials. MATERIALS AND METHODS A master die analogous to a complete veneer crown preparation was machined from medical grade stainless steel, and 3 measurements (1: vertical; 2 and 3: horizontal) were made from 3 scribed reference lines. Individual polyvinylsiloxane impressions were made (n = 10) for each of the specimens. The fabricated dies were measured (50x) to the nearest 0.0001 mm. Data were subject to ANOVA/Duncan tests at significance level 0.05 and pairwise comparisons. RESULTS Type IV resin-impregnated dental stone and copper-plated dies most closely approximated the dimensions of the master die, and were not significantly different from each other in any of the pairwise comparisons. Conventional Types IV and V dental stone dies exhibited setting expansion within the range appropriate for gypsum. Epoxy resin die materials demonstrated shrinkage comparable to the expansion of the Types IV and V dies. Polyurethane dies displayed a combination of linear expansion and shrinkage. Bis-acryl composite resin dies had excessive shrinkage. CONCLUSIONS Type IV resin-impregnated dental stone and copper-plated dies were more dimensionally accurate than the other die materials tested.
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Affiliation(s)
- Brian J Kenyon
- Department of Restorative Dentistry, University of the Pacific School of Dentistry, San Francisco, CA 94115, USA.
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Harris PE, Hoyer S, Lindquist TJ, Stanford CM. Alterations of surface hardness with gypsum die hardeners. J Prosthet Dent 2004; 92:35-8. [PMID: 15232562 DOI: 10.1016/j.prosdent.2004.04.002] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
STATEMENT OF PROBLEM Die stones require abrasion resistance, dimensional stability with time, and high surface wettability material properties. PURPOSE The purpose of this study was to compare the surface microhardness (Knoop) of 4 contemporary gypsum materials with and without surface die hardener. MATERIAL AND METHODS Materials used were a Type III stone (Microstone) and 3 die stones (Die-Keen, Silky-Rock, and ResinRock). Die hardener was cyanoacrylate (Permabond 910) or Clear Coat. Specimens of stone were hand mixed with distilled room temperature water and vacuum spatulated according to manufacturer's directions. Five cylinders (15 x 15 mm) per group were poured, using vibration, into phenolic ring molds positioned on top of a glass slide. The face of each specimen was polished with 2400-grit Al2O sandpaper. One face of each of 5 specimens/material was coated with cyanoacrylate; 5 specimens/material were coated with Clear Coat, air thinned and dried; and 5 specimens/material had no treatment (control). Knoop hardness (kg/mm2) readings were made on each face (5 readings/time point) 3, 12, and 24 hours after pouring. An ANOVA procedure with post hoc Tukey tests were performed (alpha=.05). RESULTS Microhardness did not vary between 3 and 24 hours for any material (P>.05). Microstone had significantly lower surface hardness (P<.0001) than the die stones. Specimens coated with die hardener had lower hardness values (P<.001 in all cases) CONCLUSIONS The 3 types of die stones evaluated in this study did not differ significantly in surface microhardness. Under these conditions, die hardener coatings reduced the surface hardness of the gypsum material.
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Affiliation(s)
- Paul E Harris
- University of Iowa, College of Dentistry, Iowa City, USA
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Lindquist TJ, Stanford CM, Knox E. Influence of surface hardener on gypsum abrasion resistance and water sorption. J Prosthet Dent 2003; 90:441-6. [PMID: 14586307 DOI: 10.1016/s0022-3913(03)00544-4] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
STATEMENT OF PROBLEM Abrasion is a major concern when gypsum products are used for dies, leading to the frequent recommendation that surface hardeners should be used before waxing or scanning. PURPOSE This study evaluated abrasion resistance and water sorption with 4 commonly used gypsum die materials with and without the application of surface die hardeners. MATERIAL AND METHODS Three ADA Type IV (Vel-Mix, ResinRock, and Silky-Rock) and 1 Type V die material (Die-Keen) were evaluated for abrasion resistance after application of 2 surface hardeners (Permabond 910 cyanoacrylate and Clear Coat). Thirty specimens of each material were fabricated using an impression of a standard brass die machined with 1-mm high ridges, sloped 45 degrees. Gypsum materials were mixed according to manufacturers' recommendations and allowed to set 1 hour before separating. All replicated dies were allowed to bench set for 14 days before testing. One hour before testing, specimens were arbitrarily assigned to 1 of 3 treatment subgroups (n=10/group): no treatment (control), coated with Permabond 910, or coated with Clear Coat. In the coated groups, die hardener was painted over the grooves and air dried. Abrasion resistance (measured by weight loss) was evaluated using a reciprocal abrasion device in which a stylus applied a 50-g mass perpendicular to the ridges. Mass loss was determined using an analytical balance before and after each test cycle. Five sets of 20 unidirectional passes were made on each specimen. A scanning electron microscope was used to evaluate the surface of specimens in each treatment subgroup. Water sorption was also evaluated using 2 Type IV (Silky-Rock, ResinRock) and 1 Type III (Microstone) gypsum materials. Specimen dies were separated 1 hour after pouring the impression and allowed to bench set 1 week before testing. Five specimens from each material group received a coating of a surface hardener 1 hour before testing. Specimens were placed in distilled water for 15 minutes and differences in mass were determined using an analytical balance before and after each test. A 2-way analysis of variance was completed followed by a Tukey post hoc test (alpha=.05). RESULTS The 2-way analysis of variance revealed an interaction between product and surface coating (P=.0459). Given this interaction, the 12 combinations determined by surface treatment and material type were considered individually using the Tukey method. Vel-Mix, control (2.62 +/- 2.64 mg) had the most material loss and Vel-Mix, Clear Coat (0.48 +/- 0.29 mg) had the least material loss. Water sorption results indicated an interaction between the gypsum material and the surface treatment (P<.0001). The control groups of Microstone (299.2 +/- 49.6 mg) and Silky-Rock (159.0 +/- 8.5 mg) showed the most water sorption compared with the other treatment groups. CONCLUSIONS This study demonstrated that a significant improvement in abrasion resistance occurred only with specific gypsum/surface hardener material combinations. Also, water sorption decreased significantly for Microstone and Silky-Rock gypsum materials when a surface hardener was used.
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Affiliation(s)
- Terry J Lindquist
- Department of Prosthodontics, College of Dentistry, University of Iowa, Iowa City 52242, USA.
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Allen EP, Bayne SC, Brodine AH, Cronin RJ, Donovan TE, Kois JC, Summitt JB. Annual review of selected dental literature: report of the committee on scientific investigation of the American Academy of Restorative Dentistry. J Prosthet Dent 2001; 86:33-56. [PMID: 11458262 DOI: 10.1067/mpr.2001.116232] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/17/2023]
Affiliation(s)
- E P Allen
- Department of Periodontics, Baylor College of Dentistry, Member of The Texas A&M University System, Dallas, Texas, USA
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