Comparative stability of two removable die systems

Miranda, Frank; Dilts, Walter E.; Duncanson, Manville G.; Collard, Earl W.

doi:10.1016/0022-3913(76)90191-8

Cited by 13 publications

(6 citation statements)

References 8 publications

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“…Sectioning can release stress in the gypsum so that the dies can be repositioned to the original position granted by the acrylic base [30]. The distortion of the conventional cast making steps represented in this study are similar to what has been found in other studies [25, 28, 30]. There have been studies that evaluate the trueness and precision of extraoral scanners by using solo abutments [35], silicone impression material [11], or by an easy-to-measure metric cast [34], but there is hardly any information about the factors that influence accuracy between the making of the gypsum cast and the CAD/CAM production of the final prostheses using life-like samples.…”

Section: Discussionsupporting

confidence: 72%

“…Not more than 24 h after taking the impressions, the 10 impressions were casted in the dental laboratory with type IV gypsum (GC Fujirock EP, GC Corp., Tokyo, Japan) [25, 28, 30]. The mixing of the gypsum was performed with distilled water (100 g/25 ml) first by hand, then with a vacuum mixer (20 s, BEGO Motova SL, BEGO USA Inc., Lincoln, RI, USA).…”

Section: Methodsmentioning

confidence: 99%

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Trueness of CAD/CAM digitization with a desktop scanner – an in vitro study

et al. 2019

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BackgroundDesktop scanners are devices for digitization of conventional impressions or gypsum casts by indirect Computer-Aided Design/Computer-Assisted Manufacturing (CAD/CAM) in dentistry. The purpose of this in vitro study was: 1, to investigate whether virtual models produced by the extraoral scanner have the same trueness as sectioned casts; and 2, to assess if digitization with an extraoral scanner influences the surface information.MethodsA polimethyl-methacrilic acid (PMMA) cast and a reference scanner (TwoCam 3D, SCAN technology A/S, Ringsted, Denmark; field of view 200 mm, resolution 0.1 mm ± 0.025 mm) were used to create the reference data in standard tessellation format (STL). According to the extraoral CAD/CAM digitization steps, impressions, mastercasts, and sectioned casts were made, and STL files were generated with the reference scanner. The pivotal point of the study was to digitalize these sectioned casts with the extraoral scanner (Straumann CARES Scan CS2 Visual 8.0 software, InstitutStraumann AG, Basel, Switzerland) and STL files were exported. Virtual caliper measurements were performed. Absolute deviations were compared using multilevel mixed-effects linear regression. Relative distortions were calculated with mean absolute errors and reference values.ResultsDifferences were observed in measurements of tooth sizes. All four prepared teeth were affected. No relationship was observed in relative deviations. Absolute differences between all the indirect digitization steps considering arch distances were: impressions, − 0.004 mm; mastercasts, 0.136 mm; sectioned casts, − 0.028 mm; and extraoral scanner, − 0.089 mm. Prepared dies on the virtual casts (extraoral scanner) were closer to each other than those on the sectioned gypsum casts. Relative deviation calculations revealed no relationship with the position of the dies in the arch.ConclusionThe trueness of the virtual models generated by the extraoral scanner system used in this study was different from the dimensions of the sectioned casts. The digitization of gypsum casts changes both the dimensions of dies and the distances between the dies. The virtual casts had smaller distances than any distances measured at previous steps. Either bigger dies or longer distances did not result in greater distortions. We cannot, however, generalize our results to all scanners available on the market, because they might give different results.

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Section: Discussionsupporting

confidence: 72%

Section: Methodsmentioning

confidence: 99%

Trueness of CAD/CAM digitization with a desktop scanner – an in vitro study

et al. 2019

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“…This was similar to the results obtained in the previous studies. 2,3,12,14 The displacement of the dies can be attributed to:…”

Section: Discussionmentioning

confidence: 99%

“…This was in agreement with the result of the other investigators. 2,3,[12][13][14][15][16][17] This difference indicated the amount of vertical and horizontal displacements of each die within a group. The displacement exhibited both a positive value and a negative value.…”

Section: Discussionmentioning

confidence: 99%

Evaluation of Relative Accuracy of Three Commercially Available Removable Die Systems of Different Configurations: An in vitro Study

Pasam¹,

Arora²,

Gupta³

et al. 2017

Journal of Oral Health and Community Dentistry

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Introduction:The positional shift observed in removable die systems before and after sectioning the master cast may result in a cast restoration with improper occlusal and proximal contacts and marginal fit, thereby requiring time-consuming chairside adjustments.Aim: This study was done to evaluate the relative accuracy of three commercially available removable die systems with different configurations by measuring the average die displacement before and after sectioning of the cast. Materials and methods:A total of 60 impressions were made of the standardized brass master model using polyvinylsiloxane. Impressions were divided into three groups. For each group, a different removable die system was used. Group I: cross pin; group II: M R pin; and group III: conventional brass dowel pin. The presectioning measurement both in the horizontal and vertical directions of all the 60 casts obtained were made using profile projector. The casts were then sectioned and removed and replaced 30 times, and the postsectioning measurements were made using the same references. The differences between the presectioning and the postsectioning measurements were calculated Statistical analysis used: The data were analyzed using analysis of variance (ANOVA) and Tukey's multiple comparison test.Results: All the three die systems exhibited displacement both in the horizontal and vertical directions before and after sectioning the casts. Brass dowel pin exhibited the greatest amount of displacement both in the horizontal and vertical directions. Conclusion:The use of more than one pin and the presence of metallic or plastic sleeves can result in improved accuracy and stability of the die system.

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“…Maxillary and mandibular full‐arch impressions were made using methylmethacrylate acrylic resin custom trays (SR Ivolen, Ivoclar Vivadent) and polyether impression material (Impregum Penta) 21–23 . Final impressions were poured in Type IV dental stone, and master casts were fabricated using the Accutrac system (Accutrak Precision Die System, Coltène/Whaledent Inc., Cuyahoga Falls, OH) 24 . Impressions of the interim restorations were made with irreversible hydrocolloid and poured with Type III dental stone.…”

Section: Treatmentmentioning

confidence: 99%

Fixed Rehabilitation of an ACP PDI Class III Patient

Michalakis

2006

Journal of Prosthodontics

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This clinical report documents the treatment of a 63-year-old Caucasian female Prosthodontic Diagnostic Index Class III patient using dental implants and a fixed prosthetic reconstruction. The treatment involved the fabrication of single crowns and fixed partial dentures retained by natural teeth in the maxillary arch. The posterior segments of the mandibular arch were rehabilitated with fixed partial dentures retained by endosseous implants.

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Comparative stability of two removable die systems

Cited by 13 publications

References 8 publications

Trueness of CAD/CAM digitization with a desktop scanner – an in vitro study

Trueness of CAD/CAM digitization with a desktop scanner – an in vitro study

Evaluation of Relative Accuracy of Three Commercially Available Removable Die Systems of Different Configurations: An in vitro Study

Fixed Rehabilitation of an ACP PDI Class III Patient

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