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Teeth Displacement and Palatal Adaptation of Autoclave Cured acrylic resin with Various Palates and Investments

Authors: Abdalbasit A Fatihallah عبد الباسط احمد عبد الفتاح --- Rola W.A رولا وليد --- Ali N.A علي نعة
Journal: Journal of baghdad college of dentistry مجلة كلية طب الاسنان بغداد ISSN: 16800087 Year: 2016 Volume: 28 Issue: 1 Pages: 1-10
Publisher: Baghdad University جامعة بغداد

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Abstract

Background: The denture base inaccuracies during processing negatively influence the retention and stability offinished complete denture. The aims of this study were to evaluate teeth movement and palatal adaptation ofautoclave cured denture bases and their relationship with palatal depths and investments.Materials and methods: A nightly maxillary complete dentures prepared, processed and organized to be tested asfollows: 1. Processing methods: water bath and autoclave with both fast and slow cycles. 2. Palatal depth: shallow,medium and deep. 3. Investing medium: stone and silicone. For every finished denture, two measurements weredone: first: teeth movement by attaching metallic reference screws on the right and left centrals, first premolars andsecond molars. Second: palatal adaptation by sectioning the posterior part of the denture and measuring thedistances between five selected points which were on the right and left: ridge crest, center of the vestibule andmiddle of the palate. Then two measurements were done before and after curing by using travelling microscope of0.001% of accuracy. The collected data organized statistically by three ways analysis of variance for curing methods,investments and palatal depth. Also, least significant test and t test for detection of difference.Results: High significant improvements in dimensional stability shows when autoclave was used compared with thewater bath. Results show that autoclave curing reduces the amount of teeth movements and improves palataladaptation with silicone investment compared with stone.Conclusions: resin curing by autoclave is a better alternative to water bath. The dimensional stability were improvedespecially when silicone were used instead of stone


Article
The Effects of Different Investment Materials on Dimensional Accuracy and Surface Roughness of Thermosens Maxillary Complete Dentures

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Abstract

Background: Limited data are available on the dimensional stability and surface roughness of ThermoSens, which is a material used in denture processing. This study aimed to measure the vertical teeth changes and surface roughness of ThermoSens dentures prepared using three different investment materials.Materials and methods: For the dimensional changes test, 30 complete maxillary dentures were prepared using different investment methods: group I, dental stone; group II, silicone putty; and group III, a mixture of dental stone and plaster (ratio, 1:1; n = 10 for each group). Four screws were attached to the dentures: two were attached to the buccal surface of the canine and first molar, and the other two were attached in the flange areas of the canine and first molar in line with the previously mentioned screws. Measurements were made using a micrometer microscope in the wax stage before flasking and in the deflasking stage. The above investment techniques were also used to prepare samples for a surface roughness test (n = 10 per group). These samples were prepared according to the specifications of the American Dental Association. Data were examined using analysis of variance (ANOVA) and the least significant difference (LSD) test.Results: One-way ANOVA and LSD revealed that dimensional changes significantly differed among all groups, except that the vertical teeth changes on the left side did not differ between groups I and II for both the canine and molar regions. Surface roughness was significantly higher in group I than in group II, and in group III than in group II.Conclusion: The use of putty silicone for investing ThermoSens complete dentures reduced dimensional changes and resulted in dentures with a better fit. Surface roughness could be reduced by the addition of a putty silicone layer over the denture before the addition of the second investment layer during denture processing

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