+ Site Statistics
+ Search Articles
+ PDF Full Text Service
How our service works
Request PDF Full Text
+ Follow Us
Follow on Facebook
Follow on Twitter
Follow on LinkedIn
+ Subscribe to Site Feeds
Most Shared
PDF Full Text
+ Translate
+ Recently Requested

Delayed setting and hygroscopic linear expansion of three gypsum products used for cast articulation



Delayed setting and hygroscopic linear expansion of three gypsum products used for cast articulation



Journal of Prosthetic Dentistry 102(5): 313-318



Wetting of the set gypsum product used for cast articulation may result in additional expansion. The purpose of this study was to evaluate the linear expansion of 2 type II and 1 type III gypsum products with and without addition of water after setting, over a time period of 120 hours. The gypsum products tested in this study were Model Plaster, Lab Plaster, and Mounting Stone. All materials were hand mixed for 5 seconds and mechanically mixed under vacuum for another 15 seconds. The mixes were poured into a linear expansion-measuring instrument (n=20). Half of the specimens were wet with 25 ml of water immediately after the setting time recommended by the manufacturer, and at all time intervals, immediately after data collection. No treatment was performed on the remainder of the specimens. The expansion values were recorded with an expansion-measuring device over a period of 120 hours. Collected data were subjected to a 2-way repeated-measures analysis of variance (ANOVA) (alpha=.05). The highest expansion values for all gypsum products were recorded at 96 and 120 hours. No significant difference in setting expansion values was recorded between these 2 time intervals for any of the materials and treatment conditions (dry vs. wet). Mean expansion values ranged between 0.08% +/-0.06% for dry Mounting Stone specimens at 15 minutes, to 0.57% +/- 0.02% for wet Lab Plaster specimens at 96 and 120 hours. Significant differences (P<.001) between different mounting gypsum products and time were identified. A significant difference between wet and dry specimens was not observed. The expansion of all gypsum products used for articulation purposes was complete at 96 hours. The type III gypsum product demonstrated lower mean expansion values than type II products. Time and material were more important factors than the dry/wet condition when measuring total expansion values. Type II gypsum products demonstrated 80% or more of the total expansion values in the first 45 minutes, while type III stone demonstrated the same expansion after 24 hours.

Please choose payment method:






(PDF emailed within 0-6 h: $19.90)

Accession: 052476441

Download citation: RISBibTeXText

PMID: 19853173

DOI: 10.1016/S0022-3913(09)60181-5


Related references

Delayed "hygroscopic" expansion of gypsum products. Journal of Prosthetic Dentistry 52(3): 366-370, 1984

An explanation for the hygroscopic setting expansion of dental gypsum products. Journal of Dental Research 39: 578-589, 1960

The Hygroscopic Setting Expansion of Gypsum. Acta Odontologica Scandinavica 18(4): 461-477, 1960

The effect of restrictive stress on the hygroscopic setting expansion of gypsum-bonded investments. Australian Dental Journal 14(1): 22-29, 1969

Hygroscopic setting expansion of gypsum-bonded investment under restrictive stress in dental casting. Journal of Materials Science 25(6): 2891-2896, 1990

Linear changes in the cervical region of M.O.D. blocks cast in copper aluminum alloy with hygroscopic expansion and thermic techniques. Revista Da Faculdade de Odontologia de Lins 3(2): 17-21, 1990

Hygroscopic and thermal setting expansion of 3 phosphate bonded investments. I. Free expansion of investments (hygroscopic and thermal setting). Ars Curandi Em Odontologia 5(11): 16-24, 1979

Delayed linear dimensional changes of five high strength gypsum products used for the fabrication of definitive casts. Journal of Prosthetic Dentistry 108(3): 189-195, 2013

The effect of restrictive stress on the thermal expansion of gypsum-bonded investments. II. Inlay casting investments, "hygroscopic expansion" type. Australian Dental Journal 12(2): 123-126, 1967

A calorimetric study of the hygroscopic setting of calcined gypsum. Australian Dental Journal 5(5): 269-272, 1960

Hygroscopic and thermal setting expansion of 3 phosphate bonded investments. II. Evaluation of investment expansion through casting. Ars Curandi Em Odontologia 6(1): 19-24, 1979

Effectiveness of setting expansion and semi-hygroscopic expansion of dental casting investments. I. Wax pattern preparation. Revista Da Faculdade de Odontologia Da Universidade de Sao Paulo 12(1): 55-62, 1974

Effectiveness of normal setting expansion and semi-hygroscopic expansion of dental casting investments. II. Occlusal wax pattern: preparation and inclusion. Revista Da Faculdade de Odontologia Da Universidade de Sao Paulo 12(1): 63-67, 1974

Setting and hygroscopic expansion of investments. British Dental Journal 129(1): 22-26, 1970

Effects of additives on the thermal expansion of cast gypsum. Journal of Dental Research 55(3): 518, 1976