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Okano H, Tasaka A, Matsunaga S, Kasahara M, Wadachi J, Hattori M, Abe S, Yamashita S. Effects of hollow structures added by selective laser sintering on the mechanical properties of Co-Cr alloy. J Prosthodont Res 2023; 67:460-467. [PMID: 36403960 DOI: 10.2186/jpr.jpr_d_22_00150] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 08/01/2023]
Abstract
PURPOSE This study investigates the effects of hollow structures, added by selective laser sintering (SLS), on the mechanical properties of a Co-Cr alloy for providing an optimal structural property to the framework components of removable partial dentures (RPDs). METHODS The specimens produced using the 3D data of the dumbbell-shaped cylinders were divided into four groups based on the manufacturing method: Cast, Mill, SLS-solid, and SLS-hollow. Tensile tests were performed to measure the mechanical properties of the specimens. The mechanical property values among the four groups were statistically compared using the Kruskal-Wallis test followed by the Steel-Dwass test (α = 0.05). RESULTS The median elastic modulus was the largest in the Cast, followed by SLS-solid, Mill, and SLS-hollow, with no significant differences observed between all conditions. The median ultimate tensile strength was the largest in the order of SLS-solid, Mill, SLS-hollow, and Cast. The median 0.2% proof stress was the largest in SLS-solid, followed by SLS-hollow, Cast, and Mill. The median elongation was the highest in the order of Mill, SLS-solid, SLS-hollow, and Cast. CONCLUSIONS With the addition of hollow structures, the elastic modulus decreased while the mechanical strength and proof stress remained high in SLS specimens. In addition, the ISO 22674 standard for dental metals was met, suggesting that SLS may be a possible method to design RPD frameworks with high strength and optimal structural properties.
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Affiliation(s)
- Haruna Okano
- Department of Removable Partial Prosthodontics, Tokyo Dental College, Tokyo, Japan
| | - Akinori Tasaka
- Department of Removable Partial Prosthodontics, Tokyo Dental College, Tokyo, Japan
| | | | - Masaaki Kasahara
- Department of Dental Materials Science, Tokyo Dental College, Tokyo, Japan
| | - Juro Wadachi
- Department of Removable Partial Prosthodontics, Tokyo Dental College, Tokyo, Japan
| | - Masayuki Hattori
- Department of Dental Materials Science, Tokyo Dental College, Tokyo, Japan
| | - Shinichi Abe
- Department of Anatomy, Tokyo Dental College, Tokyo, Japan
| | - Shuichiro Yamashita
- Department of Removable Partial Prosthodontics, Tokyo Dental College, Tokyo, Japan
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Guidelines for the choice of circumferential wrought wire and cast clasp arms for removable partial dentures. Int Dent J 2021; 72:58-66. [PMID: 33622544 PMCID: PMC9275311 DOI: 10.1016/j.identj.2021.01.005] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/03/2022] Open
Abstract
Purpose The aim of this study was to establish guidelines for the selection of cast and wrought-wire clasps for removable partial dentures (RPDs) that would be appropriate for clinically encountered undercuts and facial curvatures. Methods Randomly selected discarded casts were collected and 30 premolars and 30 molars were surveyed, sectioned to a line representing the clasp and scanned using a flatbed scanner. The average clasp curvature and length for each group was determined and a three-dimensional model printed, to which wrought wire clasps of 0.9- and 1.0-mm diameter were adapted. Standard wax clasp patterns were adapted and cast in a stellite alloy. Each clasp was deformed beyond its proportional limit; and the forces exerted at that limit and at deflections of 0.25 mm, 0.5 mm, and 0.75 mm were measured, and a safety limit was calculated that would ensure elastic deformation at the required undercuts. Results A table was produced with guidelines for those clasps that would provide the highest retentive force within the proposed safety limit. The highest forces were provided by cast clasps in a 0.25-mm undercut. Wrought round wire of 1-mm diameter provided the next highest retentive forces, in a 0.25-mm undercut for premolar clasps arms and 0.5-mm for molar clasps. Conclusions The results provide valid guidelines for the use of combinations of clasp material and undercut that would exert the maximum retentive force without deformation for both short (premolar) as well as long (molar) clasps, for wrought and cast clasps.
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Effect of cyclic bend loading on a cobalt-chromium clasp fabricated by direct metal laser sintering. J Prosthet Dent 2018; 119:1027.e1-1027.e7. [PMID: 29980268 DOI: 10.1016/j.prosdent.2018.03.016] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/28/2015] [Revised: 03/12/2018] [Accepted: 03/13/2018] [Indexed: 10/28/2022]
Abstract
STATEMENT OF PROBLEM Limited information is available regarding the mechanical properties of a partial removable dental prosthesis clasp fabricated by direct metal laser sintering (DMLS). PURPOSE The purpose of this in vitro study was to measure the mechanical properties of cast clasps, DMLS clasps, and annealed DMLS clasps and to determine the correlation between cyclic bend loading, annealing, and mechanical properties. MATERIAL AND METHODS Sixty half round clasp specimens were fabricated, with a length of 20 mm and a diameter of 1.5 mm at 10 mm from the tip. The specimens were divided into 6 groups (n=10). Twenty specimens were fabricated by casting (CS, CSAC), and 40 specimens were fabricated by DMLS (DS, DSAC, ADS, ADSAC). Of the DMLS specimens, 20 underwent annealing (ADS, ADSAC). Equivalent to 5 years of clinical use, 0.25 mm of bending was applied to group CSAC, DSAC, and ADSAC 14 600 times. After cyclic bending loads, a cantilever bend test was conducted on all groups, and the loads were measured. To compare the load values, 1-way ANOVA and the Tukey HSD test were performed and statistical significance among the groups was evaluated (α=.05). Scanning electron microscopy and energy-dispersive spectroscopy analyses were also used for surface morphology evaluation and element analysis. RESULTS Bending loads of the DMLS specimens were significantly lower than those of the cast specimens (P<.05). The influence of cyclic bending loads was significant for cast specimens (P<.05), but not for DMLS specimens (P>.05), in terms of variation of loads. Annealed DMLS specimens had significantly higher bending loads than DMLS specimens (P<.05). CONCLUSIONS The DMLS specimens had lower load values at 0.25 mm bending than cast specimens. The DMLS specimens were less influenced by cyclic bending loads than the cast specimens. Annealing increased load values of the DMLS specimens at 0.25 mm bending.
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Oyar P, Soyarslan C, Can G, Demirci E. Finite element analysis of stress distribution on modified retentive tips of bar clasp. Comput Methods Biomech Biomed Engin 2011; 15:609-13. [PMID: 21347911 DOI: 10.1080/10255842.2011.554406] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
Abstract
This study used finite element analysis to evaluate the retentive tips of bar clasps made from different alloys and using different designs in order to determine whether or not different materials and tip forms are suitable for bar clasp applications. Co-Cr, Ti and Type IV Au alloys were selected based on their physical and mechanical properties. The 3D finite element models of three different bar clasp retentive tip geometries prepared from Co-Cr, Ti and Type IV Au alloys were constructed using the finite element software package MSC.Marc. Analysis of a concentrated load of 5 N applied to the removable partial denture approach arms in an occlusal direction was performed. Although stress distribution and localisation within bar clasps with different retentive tips were observed to be similar and were concentrated in the approach arm, stress intensities differed in all models.
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Affiliation(s)
- P Oyar
- School of Dental Technology, Hacettepe University, Ankara, Turkey.
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Narva KK, Lassila LVJ, Vallittu PK. Fatigue resistance and stiffness of glass fiber-reinforced urethane dimethacrylate composite. J Prosthet Dent 2004; 91:158-63. [PMID: 14970762 DOI: 10.1016/j.prosdent.2003.10.024] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
STATEMENT OF PROBLEM Retentive properties of cast metal clasps decrease over time because of metal fatigue. Novel fiber-reinforced composite materials are purported to have increased fatigue resistance compared with metals and may offer a solution to the problem of metal fatigue. PURPOSE The aim of this study was to investigate the fatigue resistance and stiffness of E-glass fiber-reinforced composite. MATERIAL AND METHODS Twelve cylindrical fiber-reinforced composite test cylinders (2 mm in diameter and 60 mm in length) were made from light-polymerized urethane dimethacrylate monomer with unidirectional, single-stranded, polymer preimpregnated E-glass fiber reinforcement. Six cylinders were stored in dry conditions and 6 in distilled water for 30 days before testing. Fatigue resistance was measured by a constant-deflection fatigue test with 1 mm of deflection across a specimen span of 11 mm for a maximum of 150,000 loading cycles. The resistance of the cylinder against deflection was measured (N) and the mean values of the force were compared by 1-way analysis of variance (alpha = .05). The flexural modulus (GPa) was calculated for the dry and water-stored cylinders for the first loading cycle. Scanning electron microscopy was used to assess the distribution of the fibers, and the volume percent of fibers and polymer were assessed by combustion analysis. RESULTS The test cylinders did not fracture due to fatigue following 150,000 loading cycles. Flexural modulus at the first loading cycle was 18.9 (+/- 2.9) GPa and 17.5 (+/- 1.7) GPa for the dry and water-stored cylinders, respectively. The mean force required to cause the first 1-mm deflection was 33.5 (+/- 5.2) N and 37.7 (+/- 3.6) N for the dry and water stored cylinders, respectively; however, the differences were not significant. After 150,000 cycles the mean force to cause 1-mm deflection was significantly reduced to 23.4 (+/- 8.5) N and 13.1 (+/- 3.5) N, respectively (P < .0001). Scanning electron microscopy highlighted fiber- and polymer-rich areas within the specimens and indicated that individual fibers were well impregnated with resin. The combustion analysis studies identified the fiber content to be 35.9 vol%. CONCLUSION The results of this study suggest that the fatigue resistance of the fiber-reinforced material examined was increased; however, the reduction in flexural modulus of fiber-reinforced composites may restrict their use where high rigidity is required, such as in removable partial denture clasps.
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Affiliation(s)
- Katja K Narva
- Department of Prosthetic Dentistry and Biomaterials Research, Institute of Dentistry, University of Turku, Finland.
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Naik PR, Duncanson MG, Mitchell DL, Wiebelt FJ, Johnson DL, Ghosh J. Evaluation of stresses and forces in selected I-bars using the finite element method. J Prosthodont 1997; 6:43-54. [PMID: 9497768 DOI: 10.1111/j.1532-849x.1997.tb00064.x] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
PURPOSE Three-dimensional models of half-round, tapered and full-round, untapered I-bar clasps of varying configurations and material properties were constructed. The purpose of this study was to examine the stresses and reaction forces produced within each model upon deflection to 0.01 in (0.254 mm), 0.02 in (0.508 mm), and 0.03 in (0.762 mm) at 1 mm from the tip using the finite element method. MATERIALS AND METHODS Three-dimensional computer models of half-round and full-round clasps were constructed using solid eight-node brick elements. The half-round, tapered I-bar clasp model was 2.4 and 1.4 mm in diameter at the base and tip, respectively. The full-round, untapered I-bar clasp model was 1 mm in diameter. Three design groups were created for each clasp form. Group A had 25% of the total length in the straight anchor end of the I-bar clasp, B had 35%, and C had 50%. All models were 31 mm in length and had a radius of curvature of 5 mm. Different material properties were incorporated into the models. Each model was deflected at a point 1 mm from the tip to 0.01 in (0.254 mm), 0.02 in (0.508 mm), and 0.03 in (0.762 mm). RESULTS The stresses and forces produced as a result of the deflection applied to each clasp were viewed and displayed graphically. The maximum von Mises stresses in megapascals and the reaction force in newtons (N) were recorded. Stresses varied in each clasp in the range of 0 to 154.3 MPa for the half-round, tapered I-bar clasp models, and 0 to 100.9 MPa for the full-round I-bar clasp models at 0.01-in deflection. Reaction force measured near the tip of the clasp models was between 1.60 N and 6.31 N for the half-round, and between 0.22 N to 2.13 N for the full-round I-bar clasp models. For all clasps studied, as the deflection increased, the location of stress within each group remained the same regardless of the material properties; however, the stress and force values increased linearly. CONCLUSIONS The location of maximum stress varied with the length of the anchor portion of the clasps studied. Maximum stresses were located on the flat side of the half-round, tapered I-bar clasp model.
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Affiliation(s)
- P R Naik
- Department of Removable Prosthodontics, University of Oklahoma, College of Dentistry, Oklahoma City 73190, USA
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Waldmeier MD, Grasso JE, Norberg GJ, Nowak MD. Bend testing of wrought wire removable partial denture alloys. J Prosthet Dent 1996; 76:559-65. [PMID: 8933451 DOI: 10.1016/s0022-3913(96)90019-0] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
The flexibility of the wrought wire clasp is related to a number of factors, including the type and gauge of the alloy. The purpose of this study was to compare the bend behavior of five wrought wire alloys used in removable partial dentures. The alloys and their gauge diameters (in millimeters) were Ticonium (18, 19, 20), platinum-gold-palladium (18, 19), Wironium (18, 20), Jelenko Standard (18, 19, 20), and Denture Clasp (18, 19, 20). A total of 12 to 15 samples of each dental alloy were tested. Three-point bending was performed on a servohydraulic testing system controlled by a computer at 1.00 mm/sec until fracture or actuator contact occurred. Maximum stress and elastic modulus in bending were determined for each gauge diameter. Analysis of variance and post hoc Scheffe statistical analyses revealed significant maximum stress and elastic modulus in bending differences for different alloys of the same gauge and for different gauges of the same alloy. The choice of material and the gauge diameter significantly influenced the mechanical property of bending for wrought wire removable partial denture alloys. The Ticonium alloy had the greatest elastic modulus (stiffest) at all levels and the Denture Clasp and the Jelenko Standard alloys had the lowest elastic modulus (most flexible). These data indicate that knowledge of the bending properties of an alloy is equally as important as the gauge size when selecting a wire clasp.
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Affiliation(s)
- M D Waldmeier
- School of Dental Medicine, University of Connecticut Health Center, Farmington, USA
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VandenBrink JP, Wolfaardt JF, Faulkner MG. A comparison of various removable partial denture clasp materials and fabrication procedure for placing clasps on canine and premolar teeth. J Prosthet Dent 1993; 70:180-8. [PMID: 8103801 DOI: 10.1016/0022-3913(93)90016-h] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Abstract
There is no established protocol for selection among the different retentive material-attachment combinations for clasps other than tradition or laboratory preference. Various wrought-wire, cast-metal, and thermoplastic materials were subjected to several fabrication procedures and tested in a custom-designed force displacement apparatus. The wrought wires included ADA Spec. No. 7 type I and type II alloys and other precious and nonprecious alloys. A graphic means was devised to allow the rational selection of wrought-wire clasp-arm combinations for placing clasps on canine and premolar teeth. Guidelines for using straight wire data for curved wire applications are indicated.
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Affiliation(s)
- J P VandenBrink
- Faculty of Dentistry, University of Alberta, Edmonton, Canada
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Yuasa Y, Sato Y, Ohkawa S, Nagasawa T, Tsuru H. Finite element analysis of the relationship between clasp dimensions and flexibility. J Dent Res 1990; 69:1664-8. [PMID: 2212211 DOI: 10.1177/00220345900690100701] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022] Open
Abstract
A parameter study with use of the finite element method was conducted for examination of the relationships between the shape parameters of a clasp (width and thickness at the base and tip of the clasp) and its displacement or stress. By synthesis of these relationships, a simple formula defining the clasp tip displacement in terms of clasp dimensions ("displacement formula") was obtained. A stiffness parameter "Fd" (the load producing a 1-mm displacement of the clasp tip) was proposed, and a formula defining Fd in terms of shape parameters was derived from the displacement formula. Fd would be a practical parameter for the definition of clasp retention, and the present formulae appear to be useful tools for investigation of the retention of removable partial dentures.
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Affiliation(s)
- Y Yuasa
- Department of Removable Prosthodontics, Hiroshima University School of Dentistry, Japan
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Abstract
Cast cobalt-chromium clasps, long and short, tapered and untapered, were studied. It is shown that the behaviour of apparently identical clasps is inconsistent. Permanent deformation appears to commence during the first month of wear, and after 6 months' wear the retentive quality of almost all of the clasps is impaired.
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Affiliation(s)
- F Ghani
- Institute of Dental Surgery, University of London, U.K
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Matheson GR, Brudvik JS, Nicholls JI. Behavior of wrought wire clasps after repeated permanent deformation. J Prosthet Dent 1986; 55:226-31. [PMID: 3514861 DOI: 10.1016/0022-3913(86)90350-1] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
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Abstract
During the polishing of clasps, two possible changes that could affect their properties are thinning of the clasp and work hardening of the alloy. Two distinctly different clasp pattern forms were selected and 20 samples of each were cast. They were then divided into two groups, polished and unpolished, in an effort to determine the total influence of the polishing procedure on clasp behavior. The results indicate that polishing produces a slightly more flexible clasp. Any influence resulting from possible work hardening is offset by the reduction of clasp thickness. Effects of width/thickness ratios and magnitude of deflections on finishing and polishing techniques may also alter clasp flexibility in the polished clasp.
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Cunningham JL. Clasping using Wiptam wrought wire. J Dent 1985; 13:311-7. [PMID: 3910683 DOI: 10.1016/0300-5712(85)90027-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023] Open
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Firtell DN, Muncheryan AM, Green AJ. Laboratory accuracy in casting removable partial denture frameworks. J Prosthet Dent 1985; 54:856-62. [PMID: 3908666 DOI: 10.1016/0022-3913(85)90488-3] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
Abstract
An attempt was made to compare the clinical accuracy of two types of cast metals used in the fabrication of removable partial dentures as they were prepared by commercial laboratories. No comparison of the metals could be made, because the discrepancies that were found were too gross and were related to technical error. Suprabulge clasps were placed in less undercut than prescribed. Infrabulge clasps were placed in more undercut than prescribed. The laboratories produced better accuracy when they were informed of the purpose of the cast frameworks than when the frameworks were made without the knowledge that their work would be tested. One laboratory produced better results than the other under similar conditions.
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Stade EH, Stewart GP, Morris HF, Pesavento JR. Influence of fabrication technique on wrought wire clasp flexibility. J Prosthet Dent 1985; 54:538-43. [PMID: 3900348 DOI: 10.1016/0022-3913(85)90430-5] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
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Causton BE, Braden M, Brown D, Combe EC, Fletcher AM, Lloyd CH, McCabe JF, Prosser HJ, Waters NE, Watts DC. Dental materials: 1981 literature review. Part 2. J Dent 1984; 12:95-121. [PMID: 6379004 DOI: 10.1016/0300-5712(84)90044-7] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023] Open
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Causton BE, Braden M, Brown D, Combe EC, Fletcher AM, Lloyd CH, McCabe JF, Prosser HJ, Waters NE, Watts DC. Dental materials: 1981 literature review. Part 1. J Dent 1984; 12:1-28. [PMID: 6368624 DOI: 10.1016/0300-5712(84)90002-2] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023] Open
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Morris HF, Asgar K, Brudvik JS, Winkler S, Roberts EP. Stress-relaxation testing. Part IV: Clasp pattern dimensions and their influence on clasp behavior. J Prosthet Dent 1983; 50:319-26. [PMID: 6352918 DOI: 10.1016/s0022-3913(83)80084-5] [Citation(s) in RCA: 23] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
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Johnson DL, Stratton RJ, Duncanson MG. The effect of single plane curvature on half-round cast clasps. J Dent Res 1983; 62:833-6. [PMID: 6345616 DOI: 10.1177/00220345830620071501] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023] Open
Abstract
The quality of retention produced by a half-round cast clasp is affected by its curvature in the plane of its flat side. Uncurved clasps and those that curve 90 degrees, 180 degrees, and 270 degrees become progressively stiffer. Conversely, as the radius of the curvature increases, so does the flexibility of the clasp.
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Frank RP, Brudvik JS, Nicholls JI. A comparison of the flexibility of wrought wire and cast circumferential clasps. J Prosthet Dent 1983; 49:471-6. [PMID: 6341557 DOI: 10.1016/0022-3913(83)90305-0] [Citation(s) in RCA: 21] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
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