Impact of Water Quality and Water Powder Ratio on the Properties of Type 4 - Die Stones (Gypsum Products) used in Dentistry

Jayaprakash, K; Upadhya, P. Nagaraja; Nandish, Bantarahalli Thopegowda; Shetty, A. Nityananda; Shetty, K Harish Kumar; Ginjupalli, Kishore; Voddya, Shama Bhat; Prabhu, Sudeendra

doi:10.5455/ijhrs.000000056

Cited by 12 publications

(18 citation statements)

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“…This was borne by results presented for Type V and III undiluted mixtures, where Type V, with a lower W/P ratio, was 2.6 times higher (Figure 1). Although Types IV and V have similar W/P ratios, salts are added to Type IV to reduce expansion [19]. This, too, is supported by Figure 1, where mean expansion values for undiluted Type IV are lower than Type V, and similar to Type III.…”

Section: Discussionmentioning

confidence: 70%

“…For Type II gypsum, increasing volumetric water additions by 1/3 reportedly causes expansion to fall by 43% and compressive strength to decrease by 32% [18]. In Type IV stone, Brinell hardness has been shown to decrease by 26-36% with water increases of 16-17% [19]. With multiple properties affected by changes in water/powder (W/P) ratio, improving the fit of implant-supported prostheses by reducing setting expansion also may be accompanied by reductions in a master cast's strength and hardness.…”

Section: Introductionmentioning

confidence: 99%

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Effect of Water Dilution on Full-Arch Gypsum Implant Master Casts

Sheets

Wee

Simetich³

et al. 2020

Prosthesis

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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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Section: Discussionmentioning

confidence: 70%

Section: Introductionmentioning

confidence: 99%

Effect of Water Dilution on Full-Arch Gypsum Implant Master Casts

Sheets

Wee

Simetich³

et al. 2020

Prosthesis

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“…the final strength, surface microhardness and dimensional stability of the set gypsum material. Any factor which may alters these parameters or interferes with the crystals growth will affect their strength and abrasion resistance [7].…”

Section: Setting Expansionmentioning

confidence: 99%

“…Numerous attempts were done to improve the compressive strength and microhardness of the die materials. These attempts are primarily aimed at to reduce the amount of the required water or by adding reinforcing additives such as calcium oxide and calcium carbonate [7]. Aluminum oxide is a commonly naturally occurring ceramic oxides, which are extensively used in dentistry as reinforcement fillers that can raise the mechanical properties and surface microhardness of their composite [8].…”

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confidence: 99%

Effect of Aluminum Oxide Addition on Compressive Strength, Microhardness and Setting Expansion of Dental Plaster.

Hamdy¹,

Restorative²

2019

IJAR

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Introduction: Gypsum products are widely used in clinical dentistry for construction of dental models (casts) and dies. The ideal requirement of model and die materials include a high compressive strength and resistance to abrasion, in addition to high dimensional stability. Dental plaster, stone, and improved stone are the three types of gypsum products used in dentistry differ in their physical and mechanical characteristics. Although dental plaster is considered as the least expensive of the three gypsum products, but their low strength, microhardness and dimensional stability limit their use as mater cast and die materials. Aim: The aim of this study was to evaluate the effect of addition of 15 weight% aluminum oxide fillers on compressive strength, microhardness and setting expansion of the dental plaster. Materials and Methods: A total of 60 specimens; 30 specimens per each group were prepared. The control group was made by mixing dental plaster with water. The other group was made by addition of 15 wt.% aluminum oxide fillers to the conventional dental plaster prior to mixing with water. Water-powder was done according to the manufacturer's recommendations among all groups. After 24 hours compressive strength, surface microhardness and setting expansion were evaluated by Universal testing machine; Vickers microhardness testing and extensometer respectively. Results: Dental plaster reinforced by 15 wt.% aluminum oxide fillers demonstrated higher mean compressive strength and microhardness values, while lower mean setting expansion values compared to that of conventional dental plaster (p < 0.05). Conclusion: Dental plaster reinforced by 15 wt.% aluminum oxide fillers could be used alternatively to type IV: high strength dental stone (improved stone) to be used as master cast and die materials.

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“…The FDM process has capability for producing cost-effective tailor-made products at low cycle time that are best suited for dental applications [27,28]. In the past some researchers have prepared denture samples using double distilled water and sea water with higher W/P ratio (than recommended by commercial manufacturers) that has significant effects on the setting time, hardness and compressive strength [29]. Similarly, dimensional accuracy by comparison of different die materials has good response by using AM technology [30,31].…”

Section: Introductionmentioning

confidence: 99%

Partial dentures by centrifugal casting assisted by additive manufacturing

Singh

2019

Sādhanā

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This research work focuses on preparation of partial dentures (as functional prototypes) by additive manufacturing (AM)-assisted centrifugal casting (CC). The master pattern for partial dentures was prepared on fused deposition modelling (FDM) set-up (established by AM technique at low cost). The final dentures as functional prototypes were prepared with a nickel-chromium (Ni-Cr)-based alloy by varying different proportions of Ni% (N) by weight %. The other input parameters were powder to water P/W ratio (W) and pH value (H) of water used for mixing the investment. The samples prepared were ascertained for dimensional deviation (Dd), surface finish (R a ) and micro-hardness (HV) as output parameters. Finally, multifactor optimization has been applied on output parameters of functional prototypes prepared. This study highlights that partial denture prepared with W-100/15, H-7 and N-61% gives overall better results from mechanical properties and dimensional accuracy viewpoint. The results are also supported by photo-micrographic analysis.

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Impact of Water Quality and Water Powder Ratio on the Properties of Type 4 - Die Stones (Gypsum Products) used in Dentistry

Cited by 12 publications

References 0 publications

Effect of Water Dilution on Full-Arch Gypsum Implant Master Casts

Effect of Water Dilution on Full-Arch Gypsum Implant Master Casts

Effect of Aluminum Oxide Addition on Compressive Strength, Microhardness and Setting Expansion of Dental Plaster.

Partial dentures by centrifugal casting assisted by additive manufacturing

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