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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


Article
Dimensional stability of acrylic denture base material after poly vinyl pyrrolidone addition

Author: Israa Mouhammed Humoudi.
Journal: Tikrit Journal for Dental Sciences مجلة تكريت لعلوم طب الاسنان ISSN: 20731213 Year: 2016 Volume: 4 Issue: 1 Pages: 29-38
Publisher: Tikrit University جامعة تكريت

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Abstract

Problem Denture base dimensional changes were found with commercial theremocured acrylic resins. The dimensional stability of acrylic resin denture base is the main necessity effects the retention and stability of the denture. This study was conducted to measure the dimensional accuracy of experimental prepared material in comparison with control material before and after thermo cycling cured by water bath and microwave. In this stady the total (40) specimens of heat cure acrylic resin lower denture base were cured by water bath and microwave after addition poly vinyl pyrrolidone (PVP). (Experimental). Preparation of modified heat cured denture base acrylic resin was carried out by preparing of (PMMA) (80%) and poly vinyl pyrrolidone (PVP) (20%) and the liquid part composed of methyl methacrylate (MMA) monomer. Evaluation was made by measuring dimensional stability and accuracy. Distances were measured between (3) points marked on denture bases "AB, AC and BC" before and after thermo cycling for both control and experimental groups. The result of this study showed that there was no significant differences (p>0.05) between control and experimental groups at three point "AB, AC and BC" before and after thremocycling. Dimensional stability and accuracy was not influenced by addition of PVP to acrylic denture base resin before and after thermo cycling in both heat and microwave treatment.


Article
Estimation of the linear dimensional changes of autoclave cured acrylic resin with multiple palatal depths and investment materials

Authors: Rola W.A رولا وليد --- Ali N.A علي نعمة
Journal: Journal of baghdad college of dentistry مجلة كلية طب الاسنان بغداد ISSN: 16800087 Year: 2015 Volume: 27 Issue: 2 Pages: 32-42
Publisher: Baghdad University جامعة بغداد

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Abstract

Background: Dimensional changes of acrylic denture bases after polymerization results in need for furtheradjustments or even ends with technical failure of the finished dentures. The purpose of this study was to estimate thelinear dimensional changes for different palatal depths when using multiple investment materials and polymerizationtechniques.Materials and methods: Ninety upper complete denture bases were constructed for this study. They were dividedinto two main groups according to the polymerization methods: conventional water bath and experimentalautoclave (short and long cycles). Each main group was further subdivided into three subgroups according to thepalatal depth (shallow, medium and deep). Furthermore, for each palatal depth; complete denture bases wereinvested either with dental stone or laboratory silicone. For each upper complete denture, measurements of lineardimensional changes were done by fixation of metallic screws on the tissue surface of the denture base. Thedistances were measured by using travelling microscope with an accuracy of 0.001 %. The data were statisticallyanalyzed using three way analysis of variance (ANOVA) for three variables, which were (palatal depth, investmentsand polymerization techniques), LSD test and student T test for comparisons between groups.Results: There were significant improvements in the dimensional accuracy of denture bases cured with autoclavecompared with water bath. Also, silicone investments were a successful alternative to stone, study data shows thatshort autoclave processing with silicone reduces the magnitude of the linear dimensional changes. On the otherhand, long autoclave processing and stone investments were better than silicone in reducing dimensional changes.Conclusion: The findings of this study indicates that the use of autoclave processing in acrylic curing is a promisingalternative to the conventional water bath and leads to better dimensional stability for the finished dentures in alloral configurations and palatal depths. Also, Silicone is more preferable than stone, although it's not as stronginvesting materials when compared with stone


Article
Evaluation of Dimensional Stability for Denture Bases in different Curing Techniques

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Abstract

Stable record base is critical for recording an accurate maxillo-mandibular relationship and evaluation of the esthetics and phonetics of the wax trial prosthesis. To ensure intra-oral stability and retention of the record base, the base should maintain close adaptation to the cast and be dimensionally stable, this study compare the dimensional stability of visible light cure acrylic both conventionally and by using new technique of short curing cycle. Thirty maxillary cast edentulous models poured with a type IV dental di-stone, the specimen divided into three subgroups each group consist of ten cast. In the first group denture base constructed from heat cure acrylic resin using short curing cycle, while in the second group it constructed by using visible light cure acrylic resin and for the third group from visible light cure acrylic resin using new technique, the gap space occurs between the denture base and the cast measured by using traveling microscope measuring device. In this study the reading for the gap space occur between the denture base and the cast show that significantly both the short cycle and VLC new technique more dimensionally stable than that of VLC conventional technique when compared by ANOVA Table and LSD multiple comparison. The dimensional accuracy or fit for the denture base improved by using either a heat cured acrylic resin (using short curing cycle or by using light activated poly methylmethacrylate with the aid of new technique so that better stability and retention of the record bases obtained.

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