Dimensional Accuracy of Castings Fabricated with Ring-less and Metal Ring Investment Systems for Implant Supported Fixed Dental Prosthesis: An In-vitro Comparative Study

Shah, Rakesh; Jp, Singh; Kumar, Manjit; D'Souza, Dsj

doi:10.1016/s0377-1237(11)80012-2

Cited by 5 publications

(8 citation statements)

References 2 publications

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“…The great importance in the investing of wax pattern is the fact that the molten used alloy for dental restoration shrink upon solidification, this problem caused casting will be that much smaller (1)(2)(3)(4)(5).…”

Section: Introductionmentioning

confidence: 99%

“…This gap can create a plaque-retentive area that leads to cavities which ultimately harms the tooth and the work done for the restoration (1,2,4,5).…”

Section: Introductionmentioning

confidence: 99%

“…Other factors that affect the accuracy of castings for restorations include the precision of the tooth preparation, impression and working cast (1,2,4,5).…”

Section: Introductionmentioning

confidence: 99%

“…There are four methods used to produce an expanded mold that compensates for metal shrinkage: 1) setting expansion of the investment, 2) hygroscopic expansion, 3) thermal expansion of the investment and 4) wax pattern expansion (1,2,4,5). In the conventional investing procedure, the metal ring restricts the setting and thermal expansion of the investment, forcing the expansion inward toward the mold, resulting in a distortion of the casting.…”

Section: Introductionmentioning

confidence: 99%

“…In the conventional investing procedure, the metal ring restricts the setting and thermal expansion of the investment, forcing the expansion inward toward the mold, resulting in a distortion of the casting. For this reason, a resilient liner is placed on the inside of the metal ring to permit the expansion and easier removal of the investment and casting from the ring later (1,2,(4)(5)(6)(7).…”

Section: Introductionmentioning

confidence: 99%

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The Comparison of Vertical Margin Discrepancy in Casting Fabricated With Metal Ring, Ringless and Metal Ring With Hygroscopic Expansion Investment Systems

Sabouhi¹,

Hedayatipanah²

2015

Avicenna J Dent Res

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Background: The use of casting ring to produce accurate casting has been challenged with the introduction of a ringless casting technique. This study compared the vertical margin discrepancy of castings fabricated with the ringless technique, conventional (ring and liner) technique and conventional technique with hygroscopic expansion investment systems. Objectives: The current study aimed to determine and compare the mean values of vertical margin discrepancies of castings in three investing procedures: the ringless technique and conventional investing technique. Materials and Methods:In the first step, 39 coping wax patterns for Porcelain fused to metal restoration (P.F.M). With chamfer finish line were fabricated on the metal die and then divided into three groups of 13. The first group used conventional investing (with ring and liner), the second group used the ringless technique and the third group used the conventional ring technique with liner and hygroscopic expansion. All groups were invested using Thermovest phosphate bonded investment. Then wax patterns were cast with Ni-Cr alloy (super cast). Castings were divested, cleaned and seated on the metal die after minimal internal surface adjustment. The vertical margin discrepancy was measured in four sites: on the buccal, lingual, mesial and distal surfaces of the die. Castings were measured on an optical microscope. The vertical margin discrepancy in each group was used for statistical analysis. Results: After statistical evaluation, the following results were obtained: the mean vertical margin discrepancy for conventional investing was 156.72 ± 64.67µ; for the ringless technique it was 117.3 ± 26.77µ; and for the conventional metal ring technique with hygroscopic expansion it was 96.15 ± 38.31 µ. There is a significant difference between castings of the conventional investing technique and the ringless and ring plus hygroscopic expansion techniques (P < 0.001). No significant difference was found between the ringless and ring plus hygroscopic expansion techniques (P = 0.183). Conclusions:The castings fabricated from the ringless technique with non-precious alloy are acceptable. This investing system is useable for the fabrication of fixed restorations.

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Section: Introductionmentioning

confidence: 99%

“…This gap can create a plaque-retentive area that leads to cavities which ultimately harms the tooth and the work done for the restoration (1,2,4,5).…”

Section: Introductionmentioning

confidence: 99%

“…Other factors that affect the accuracy of castings for restorations include the precision of the tooth preparation, impression and working cast (1,2,4,5).…”

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 3 more Smart Citations

The Comparison of Vertical Margin Discrepancy in Casting Fabricated With Metal Ring, Ringless and Metal Ring With Hygroscopic Expansion Investment Systems

Sabouhi¹,

Hedayatipanah²

2015

Avicenna J Dent Res

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Marginal accuracy of nickel chromium copings fabricated by conventional and accelerated casting procedures, produced with ringless and metal ring investment procedures: A comparative in vitro study

Alex¹,

Shetty²,

Miranda³

et al. 2015

J Indian Prosthodont Soc

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Background:Conventional investing and casting techniques are time-consuming and usually requires 2–4 h for completion. Accelerated nonstandard, casting techniques have been reported to achieve similar quality results in significantly less time, namely, in 30–40 min. During casting, it is essential to achieve compensation for the shrinkage of solidifying alloy by investment expansion. The metal casting ring restricts the thermal expansion of investment because the thermal expansion of the ring is lesser than that of the investment. The use of casting ring was challenged with the introduction of the ringless technique.Materials and Methods:A total of 40 test samples of nickel chromium (Ni-Cr) cast copings were obtained from the patterns fabricated using inlay casting wax. The 20 wax patterns were invested using metal ring and 20 wax patterns were invested using the ringless investment system. Of both the groups, 10 samples underwent conventional casting, and the other 10 underwent accelerated casting. The patterns were casted using the induction casting technique. All the test samples of cast copings were evaluated for vertical marginal gaps at four points on the die employing a stereo optical microscope.Results:The vertical marginal discrepancy data obtained were tabulated. Mean and standard deviations were obtained. Vertical discrepancies were analyzed using analysis of variance and Tukey honestly significantly different. The data obtained were found to be very highly significant (P < 0.001). Mean vertical gap was the maximum for Group II (53.64 μm) followed by Group IV (47.62 μm), Group I (44.83 μm) and Group III (35.35 μm).Conclusion:The Ni-Cr cast copings fabricated with the conventional casting using ringless investment system showed significantly better marginal fit than that of cast copings fabricated from conventional and accelerated casting with metal ring investment and accelerated casting using ringless investment since those copings had shown the least vertical marginal discrepancies among the four methods evaluated in this study.

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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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Dimensional Accuracy of Castings Fabricated with Ring-less and Metal Ring Investment Systems for Implant Supported Fixed Dental Prosthesis: An In-vitro Comparative Study

Abstract: Ring-less system of casting can be recommended for use in fabricating implant supported fixed dental restorations.

Cited by 5 publications

References 2 publications

The Comparison of Vertical Margin Discrepancy in Casting Fabricated With Metal Ring, Ringless and Metal Ring With Hygroscopic Expansion Investment Systems

The Comparison of Vertical Margin Discrepancy in Casting Fabricated With Metal Ring, Ringless and Metal Ring With Hygroscopic Expansion Investment Systems

Marginal accuracy of nickel chromium copings fabricated by conventional and accelerated casting procedures, produced with ringless and metal ring investment procedures: A comparative in vitro study

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

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