The use of alginate impression materials today is prevalent because of its efficiency and simplicity in clinical settings. Unfortunately, the simplicity of the procedure tends to lull the dentist into a sense of well-being, and lead him into using careless or sloppy technique. Alginate impression materials are used to fabricate diagnostic and preliminary casts, and the final cast. Incorrect use of this material is known to affect the accuracy of the final prosthesis. The purpose of this study was to compare the effect of different mixing methods of alginate impression material and tray adhesive on the accuracy of the stone cast produced by each method. A total of 30 stone casts were produced by using 3 different types of mixing methods (10 stone cast for each mixing method, respectively) The first method utilized an automatic-mixing machine to mix alginate while the second method was carried out manually, strictly following manufacturer's instructions. The third method also involved manual mixing, but did not follow the manufacturer's instructions and was done in a random fashion. Also, 20 additional stone casts were produced by using alginate with or without tray adhesives were included in the study to evaluate effects of tray adhesives on the accuracy of alginate impression. 10 stone casts were produced by adding tray adhesives to the interior surface of the impression tray prior to taking the impression. The other 10 excluded this step. A total of 50 stone casts were analyzed by the three-dimensional measuring machine to measure and compare the dimensional changes of the impression material of each group. The results are as follows. 1. No significant difference was found between the automatic mixing group and the manually-mixing group(p>0.05). 2. For the group that followed manufacturer's instructions, less dimensional changes were recorded than the group that didn't in measuring distance d4(p<0.05) 3. The group that used tray adhesives showed less dimensional changes(p<0.05). The findings revealed that mechanical methods of mixing alginate impression materials had little influence on dimensional changes. However, it is proven that following manufacturers instructions in alginate impression taking is an important step in acquiring accurate impressions and tray adhesives may play an important role in enhancing the results.
Adhesives* ; Dentists ; Humans ; Prostheses and Implants

No abstract available.
Denture Bases* ; Dentures*

In spite of the progress in techniques and materials of the prosthodontic rehabilitation of patients with complete edentulous arches, prosthodontists still face patients' complaints about dissatisfaction and discomfort from their dentures. In the past several decades, prosthodontists tried to find the factors that influence the patient's satisfaction with dentures. However the results are contraversial especially with the psychological factor. In this study using patient denture satisfaction questionnaire' and Hopkins Symptom Checklist, we tried to find the correlation between the patient's denture satisfaction and the patient's psychological aspects. 23 complete edentulous patients who have visited the Department of Prosthodontics, Yonsei University Dental Hospital from September 1998 to June 1999 for complete denture treatment were asked to complete the questionnaires 4 to 6 weeks after the upper and lower complete delivery. After the measurement of validity of the questionnaires, correlations between the patient's general satisfaction with their new upper and lower complete dentures and the other satisfaction questions including the satisfactions with esthetics, retention, mastication, speech, comfort and other peoples's opinion and between the patient's general satisfaction with their new upper and lower complete dentures and the 5 symptoms of Hopkins Symptoms Checklist including somatic, obsessivecompulsive, interpersonal sensitivity, depression and anxiety were analyzed. Among the several satisfaction questionnaire items, comfort with the lower denture showed highest relation to the patient's general satisfaction with dentures. However, only the anxiety scale of Hopkins Symptom Checklist among the other symptom scales was related to the patient's general satisfaction with dentures. The two questionaires used in this study turned out to be valid means of analyzing patient's denture satisfaction and psychological status before and after the complete denture treatment.
Anxiety ; Checklist ; Denture, Complete* ; Dentures ; Depression ; Esthetics ; Humans ; Mastication ; Patient Satisfaction* ; Prosthodontics ; Psychology ; Surveys and Questionnaires ; Rehabilitation ; Weights and Measures

No abstract available.
Humans ; Korean War* ; MMPI* ; Stress Disorders, Post-Traumatic* ; Veterans*

To demonstrate possible influences of general bone density on the mandible, histomorphometric analysis was carried out in mandibles and iliac bones and the correlation of the two bone densities was tested. Comparison of bony density in women and men over 60 years in the mandible was carried out too. Quantitative computed tomography (GCT) was taken in cross-section of mandibles at the same site where histomorphometric analysis was performed to evaluate the reliability of QCT. The analysis included 40 cadavers with no known disease affecting the bones. The subjects consisted of 15 females and 25 males with a mean age of 60.3 years. Spearman correlation analysis and Wilcoxon rank sum test was performed. The results were as follows. 1. There was statistically no correlation between the mandible and iliac bone in the walues of corrected cortical width (CCW), cortical porosity (POR) in cortex, and total bone volume(TBV), mean trabecular plate thickness (MTPT), mean trabecular plate density (MTPD), and mean trabecular plate separation (MTPS) in trabecular bone. 2. Comparison of women and men over 60 years, men had statistically higher bone density than women except for POR of buccal and lingual cortex, and MTPD of alveolar trabeculae in mandible. 3. There was statistically significant correlation between TBV of trabecular bone and CT NO., but not between POR and CT No. In mandible. According to the results above, there was no correlation between mandible and iliac bone density and between mandibular bony density and age. Further studies are required to support the results. A more noninvasive method to be able to measure the bone density of mandible should be developed and it is necessary to accumulate data on the normal values of bone density of mandible according to age and sex. Further study should be carried out about QCT to measure mandibular bony density using QCT.
Bone Density* ; Cadaver ; Female ; Humans ; Male ; Mandible* ; Porosity ; Reference Values

No abstract available.
Animals ; Dogs* ; Guided Tissue Regeneration*

The aim of this study was to compare wear resistance of resin denture teeth opposing various restorative materials. The wear resistance of conventional acrylic resin teeth (Trubyte Biotone) and three high-strength resin teeth(Bioform IPN, Endura, SR-Orthosit-PE) opposing different restorative materials (gold alloys, dental porcelain, composite resin) was compared. Wear tests were conducted with a sliding-induced wear testing apparatus which applied 100,000 strokes to the specimen in an mesio-distal direction under conditions of 100 stroke/min and constant loading of 1Kgf/tooth. Wear resistance of the resin denture teeth was evaluated by the following criteria : 1) wear depth, 2)weight loss, and 3) SEM observation. Results were as follows. 1. When opposed to gold alloys and composite resin, high-strength resin teeth showed superior wear resistance compared to acrylic resin teeth. But, in cases opposing dental porcelain, differences between the wear of the high-strength and acrylic resin teeth were not statistically significant (p<0.05). 2. When comparing wear resistance among high-strength resin teeth, opposing gold alloys, Endura was slightly more resistant and while in cases opposing dental porcelain, SR-Orthosit-PE was showed to be slightly resistant(p<0.05). 3. The wear of high-strength resin teeth was greater by 5 to 7 times when opposing porcelain and 2 to 3 times when opposing composite resin compared to gold alloys(p<0.05). 4. SEM observations of the wear surface showed that wear of resin teeth opposing gold alloys is a fatigue type of wear and wear of resin teeth opposing dental porcelain is fatigue and abrasion type of wear. Trubyte Biotone showed more severe fatigue type of wear than high-strength resin teeth. In conclusion, the use of dental porcelain should seriously be considered as restorative material in cases opposing resin denture teeth and improvement seems to be needed on resin teeth in the areas of wear resistance.
Dental Alloys ; Dental Porcelain ; Dentures* ; Fatigue ; Gold Alloys ; Stroke ; Tooth*

No abstract available.
Animals ; Knee Joint* ; Knee* ; Rats* ; Tretinoin*

For many years permanent soft denture liners has been widely used in dental practice directly or indirectly because of its function in absorbing and distributing the impact force. However, it reveals problems such as lack of permanency and decreased bond strength in long term use. The purpose of this study is to measure the bond strength and failure between denture base resin and several permanent liners. Lucitone 199 was used as denture base resin with soft acrylic liners (Triad, Tokuso Rebase) and silicone elastomers (Tokuyama, Ufi Gel C) bonded to measure the tensile strength before and after thermocycling. The thermocycling was done in 2000 cycles at 5degrees C, 26degrees C and 55degrees C and the measured tensile strength values before and after thermocycling were compared. The mode of failure was investigated in the separated specimens. The results are as follows. 1. As to tensile strength, the strongest material is Tokuso Rebase followed by Triad, Tokuyama, Ufi Gel C in before thermocycling and the order of Triad, Tokuso Rebase, Tokuyama, Ufi Gel C in after thermocycling state. There was significant difference between the values of Triad, Tokuso Rebase and Tokuyama, Ufi Gel C(p<0.05). 2. As to degree of displacement, Ufi Gel C showed most displacement with or without thermocycling treatment and also the difference was significant with the other materials(p<0.05). 3. As to comparisons before and after thermocycling, Tokuso Rebase and Tokuyama showed significant difference in bond strength, whereas Triad and Tokuso Rebase showed significant difference in the degree of displacement(p<0.05). 4. In debonded specimens, Triad and Ufi Gel C showed adhesion failure and Tokuyama showed cohesion failure. Both failures were observed in Tokuso Rebase with adhesion failure up to 70%. The results of this study showed that degree of bond strength between permanent soft denture liner and denture base resin were variable. There was a significant difference between soft acrylics and silicone elastomers with regard to bond strength. Further research in improving bond strength of widely used silicone elastomers and in developing the method of measuring bond strength between denture base resin and the lining materials is needed.
Denture Bases* ; Denture Liners* ; Dentures* ; Silicone Elastomers ; Tensile Strength

No abstract available.
Dental Arch* ; Humans