The determination of phosphorus containing compounds in dental casting investment products by 31P solid-state MAS-NMR spectroscopy

Scrimgeour, S. N.; Chudek, J. A.; Lloyd, C.H.

doi:10.1016/j.dental.2006.02.010

Cited by 25 publications

(23 citation statements)

References 19 publications

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“…The refractory (X) comprised silica fillers (cristobalite and quartz), excess magnesium oxide (B), and additives. For the phosphate-bonded investment to set and harden, the binder underwent the following chemical reaction to convert to NH 4MgPO4· 6H2O (D) [4][5][6][7][8] :…”

Section: Setting Reactionmentioning

confidence: 99%

“…An equimolar mixture of setting agents, monoammonium dihydrogen phosphate (NH 4H2PO4) and magnesium oxide (MgO), reacts with water to form ammonium magnesium phosphate hexahydrate (NH 4MgPO4· 6H2O), which aggregates around excess unreacted MgO and fillers [4][5][6] . X-ray analysis revealed that phosphate compounds, excess unreacted MgO, and solid mixed phosphate co-exist in a set compact 2,7,8) . During heating, the mixed phosphate decomposes.…”

Section: Introductionmentioning

confidence: 99%

“…Basically, the single-phase NH 4MgPO4· 6H2O dehydrates during heating to convert to magnesium pyrophosphate (Mg 2P2O4) at 800°C 6,7,9) . The thermal reaction is also a complex reaction because it yields a mixture of magnesium metaphosphate (Mg(PO 3)2) and farringtonite (Mg3(PO4)2) [5][6][7][8] . Besides, chemical reactions may occur between the phosphate compounds and refractory components of silica (cristobalite and quartz), MgO, and additives such as zircon (ZrSiO 4) 10) .…”

Section: Introductionmentioning

confidence: 99%

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Porosity of dental phosphate-bonded investments after setting and heating processes

2012

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Porosities of set and burnout compacts of phosphate-bonded investments were determined. A gas pycnometer was used to measure the volumes, and hence the densities, of fine powders and porous compacts. Porosities of set and burnout compacts were then obtained from these data for as-received powders and dry set compacts by a numerical simulation method, subsequently leading on to the estimated compositions of conventional and rapid-heating investments used in this study. Excess water content in the hardening investment compact was evaluated as a function of setting time elapsed from the start of mixing. Porosities were about 24-32% for set compacts and 43% for burnout compacts, which well agreed with the numerically computed results. It was concluded that the functional composition of investment powder needed to achieve the optimal porosity as well as process parameters such as water-powder (W/P) ratio and keeping time of mixed investment casting slurry before heat treatment could be determined using the numerical simulation method developed in this study.

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Section: Setting Reactionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Porosity of dental phosphate-bonded investments after setting and heating processes

2012

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“…Although phosphate-bonded dental casting investment materials have been successfully used in dentistry for more than 40 years, they still present characteristics that remain unclear. 24 Dental refractory die products are used to construct Figure 1. Differences in the a* value for the control groups.…”

Section: Discussionmentioning

confidence: 99%

“…7,15 Therefore, the ceramic is subjected to the influence of the investment according to its composition, surface, and physical-chemical properties. 17,18 Although several studies have analyzed the mechanical properties of refractory phosphatebonded investment materials, 16,[20][21][22][23][24][25] investment influence on the final color of ceramics remains unclear 17,18,26 and deserves further investigation. Because color is considered a sensation obtained through proprioceptive mechanisms, and thus considered subjective, standardized colorimetric techniques were developed with the objective of transforming colors in numeric values.…”

Section: Introductionmentioning

confidence: 99%

The Effect of Investment Materials on the Color of Feldspathic Ceramics

et al. 2011

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Objectives:The aim of this study was to evaluate the influence of investment type on the color of feldspathic ceramics.Methods:Ceramic specimens were constructed using the refractory die technique, using four investments (i.e., Vitadurvest, Duravest, Duceralay Superfit, and Fortune) to observe their effect on the color of five commercially available ceramics (i.e., Super Porcelain EX-3, Vision Esthetic, Vintage Halo, IPS Classic, and Vitadur Alpha). The color analysis of the ceramics was performed with a colorimeter using the CIE L*a*b* color coordinates.Results:The investments produced significant alterations on a*, b*, and L* color parameters of the ceramics tested. The ceramic Vision Esthetic was influenced by the type of investment in all color parameters (P<.05). Two investments (Duravest and Fortune) produced alterations in color parameters with three of the five ceramics tested.Conclusions:The investment materials produced alterations on the ceramic color parameters, resulting in unacceptable chromatic alterations (ΔE*).

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The suitability of dental investment materials as dies for superplastic forming of medical and dental prostheses

Curtis

2008

Materialwissenschaft Werkst

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Dental investment materials have long been used in the manufacture of a whole variety of customised prostheses for dental restorative procedures. The metal castings produced often have very complex shapes and unless certain protocols are followed the range of casting errors can be great. Fortunately, the dental profession has a long experience with the Lost Wax Casting procedure and such problems are rare.More recently, the investment materials commonly used to manufacture the casting moulds have been applied to the manufacture of dies for the production of dental and maxillofacial prostheses in titanium materials, such as Ti-6Al-4V and SP700 alloys. A range of studies has been conducted to assess the suitability of a variety of investment material types, all of which are available commercially. This paper will focus upon the physical properties of dental investment materials that are used to manufacture dies for the superplastic forming of dental and maxillofacial prostheses. In addition to the consideration of the physical properties of the die materials, other relevant issues include the die -titanium sheet interactions and post-forming titanium sheet properties such as contamination and biocompatibility.Such issues will be discussed in relation to regulatory issues concerning the use of biomaterials for the restoration of bodily function.

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The determination of phosphorus containing compounds in dental casting investment products by 31P solid-state MAS-NMR spectroscopy

Cited by 25 publications

References 19 publications

Porosity of dental phosphate-bonded investments after setting and heating processes

Porosity of dental phosphate-bonded investments after setting and heating processes

The Effect of Investment Materials on the Color of Feldspathic Ceramics

The suitability of dental investment materials as dies for superplastic forming of medical and dental prostheses

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