Three factors affecting investment setting expansion and casting size

Lacy, Alton M.; Fukui, Hisao; Jendresen, Malcolm D.

doi:10.1016/0022-3913(83)90238-x

Cited by 24 publications

(12 citation statements)

References 5 publications

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“…Load was removed and marginal discrepancy was measured on the Travelling microscope to the nearest of 0.01 mm at 910 magnification on each casting ( Fig. 3) at 4 predetermined sites [10]. All readings were done from a perpendicular line of view [5].…”

Section: Measurement Of Marginal Discrepancymentioning

confidence: 99%

Investigation of Marginal Fit and Surface Roughness of Crowns, Due to Different Bench Set and Different Burnout Temperature Using Base Metal Alloy

Hasti

Patil

2010

J Indian Prosthodont Soc

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The conventional investing technique is used most commonly for casting. Inspite of the popularity of this technique, it is very time consuming. To save time of the patient, dentist and dental laboratory technician, accelerated casting technique can be used. This study uses different bench set and different burnout temperatures and has been carried to investigate their effects on marginal fit and surface roughness. A total of 40 wax patterns were made simulating the artificial crown from the first master die and 20 rectangular wax patterns were made from the second master die. Twenty castings simulating the crown and 10 castings of rectangular plates were obtained by short protocol represented as Group A and C, similarly the remaining castings were obtained by standard protocol and represented as Group B and D. Marginal discrepancy of both Group A and B were determined by using Travelling microscope, whereas Perthometer was used for quantitative evaluation of average surface roughness of both Group C and D. Scanning electron microscope evaluated the surface roughness qualitatively for the specimens of both Groups C and D. The obtained values of Group A and C and Group C and D were subjected to statistical analysis. Qualitative analysis of Group C and D were done. Accelerated/short protocol gives similar results in terms of marginal fit and surface roughness as compared to the conventional/standard protocol and is definitely a time saving procedure.

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Section: Measurement Of Marginal Discrepancymentioning

confidence: 99%

Investigation of Marginal Fit and Surface Roughness of Crowns, Due to Different Bench Set and Different Burnout Temperature Using Base Metal Alloy

Hasti

Patil

2010

J Indian Prosthodont Soc

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“…• Restraining factors-rigidity of the pattern material, casting ring, and ring liner [1][2][3][17][18][19] • Nonrestraining factors-mixing time, mixing liquid, mixing device, volume mixed, and storage time and condition 17,[20][21][22] • Heating rate [23][24][25][26] • Environmental conditions.…”

Section: Resultsmentioning

confidence: 99%

Marginal Accuracy of Castings Fabricated with Ringless Casting Investment System and Metal Ring Casting Investment System: A Comparative Study

Kalavathi

Sachin

Prasanna

et al. 2016

The Journal of Contemporary Dental Practice

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Background:The thermal expansion of the investment can be restricted by the metal casting ring because the thermal expansion of the ring is less than that of the investment. The ringless casting procedure is in use in clinical dentistry, though there is little scientific data to support its use in fixed partial dentures. In this study, marginal discrepancy of castings produced with the ringless casting technique and the conventional technique using the metal rings were compared. Materials and methods:A total of 30 wax patterns were fabricated directly on a metal die. Optical stereomicroscope was used to measure the marginal discrepancy between the metal die and wax patterns. A total of 15 castings were invested using Bellavest T phosphate-bonded investment with the ringless technique and 15 were invested with the same investment with a metal ring; 30 castings were produced using a nickel-chromium ceramo-metal alloy. The internal surface of the castings was not modified and seated with finger pressure. The vertical marginal discrepancy was measured using an optical stereomicroscope at a magnification of 100×. The data obtained were statistically analyzed using students t-test (paired t-test and unpaired t-test). Results

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“…[ 13 ] The materials are also characterized by their high thermal expansions in comparison to gypsum-bonded investments. [ 13 14 ] It would be reasonable to assume that storing the waxed refractory casts for long periods would have resulted in some shrinkage. Despite its high thermal expansion, the investment material when heated exhibited an insufficient shrinkage compensation that further increased the inaccuracy of the final castings.…”

Section: Discussionmentioning

confidence: 99%

Effect of storage time and framework design on the accuracy of maxillary cobalt-chromium cast removable partial dentures

Viswambaran

Sundaram

2015

Contemp Clin Dent

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Statement of Problem:Inaccuracies in the fit of palatal major connectors may be related to distortion of the wax pattern due to prolonged storage time and faulty major connector design.Purpose:This in vitro study was carried out to find out the effect of storage time and major connector design on the accuracy of cobalt-chromium cast removable partial dentures (RPDs).Materials and Methods:A brass metal die with a Kennedy Class III, modification 1, the partially edentulous arch was used as a master die. Thirty-six refractory casts were fabricated from the master die. The refractory casts were divided into three groups (Group I: Anterior-posterior palatal bar, Group II: Palatal strap and Group III: Palatal plate) based on the design of maxillary major connector and subdivided into four groups (sub Group A: 01 h, sub Group B: 03 h, Sub Group C: 06 h, and sub Group D: 24 h) based on the storage time. For each group, 12 frameworks were fabricated. The influence of wax pattern storage time and the accuracy of the fit palatal major connector designs on the master die were compared. Casting defects (nodules/incompleteness) of the frameworks were also evaluated before finishing and polishing. Repeated measures analysis of variance was used to analyze the data.Results:The gap discrepancy was least in sub Group A (01 h) followed by sub Group B (03 h) and C (06 h) and most in sub Group D (24 h). Statistically significant differences (P < 0.05 in all locations L1–L5) in the fit of the framework were related to the design of the major connector. The gap discrepancy was least in Group I (anterior-posterior palatal bar) followed by Group II (palatal strap) and most in Group II (palatal plate).Conclusions:It is recommended that the wax patterns for RPD to be invested immediately on completion of the wax procedure. The selection of a major connector design is crucial for an accurate fit of RPD.

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Three factors affecting investment setting expansion and casting size

Cited by 24 publications

References 5 publications

Investigation of Marginal Fit and Surface Roughness of Crowns, Due to Different Bench Set and Different Burnout Temperature Using Base Metal Alloy

Investigation of Marginal Fit and Surface Roughness of Crowns, Due to Different Bench Set and Different Burnout Temperature Using Base Metal Alloy

Marginal Accuracy of Castings Fabricated with Ringless Casting Investment System and Metal Ring Casting Investment System: A Comparative Study

Effect of storage time and framework design on the accuracy of maxillary cobalt-chromium cast removable partial dentures

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