Search

Aim Assessment of flexural strength values of dental base polymers reinforced with different glass fibers ("dental" and "industrial" origin) after performed artificial ageing procedures. Methods Three hundred specimens (dimensions 18 x 10 x 3 ram) were produced of denture base polymers reinforced with different glass fibers. The "short beam" testing method was used to determine the flexural strength of the specimens after polymerization, immersion in water of temperature 37°C for 28 days, and thermo-cycling. Results Flexural strength of the polymer specimens was 91.76- 122.75 MPa, while specimens reinforced with glass fibers demonstrated rise of flexural strength values ( 103.10-163.88 M Pa), no matter which type ("dental" or "industrial") of fibers was used. Microscopic examination revealed partial bonding between the glass fibers and polymer material. Conclusion Both of the investigated glass fibers had similar strengthening effect, but due to better investment/benefit ratio "industrial" glass fibers could be recommended for dental laboratory use. Prolonged polymerization of denture base materials should be proposed because it had direct impact on the improvement of flexural strength values. [ABSTRACT FROM AUTHOR]

The paper describes different effects on the mechanical properties of fibre reinforced polymers, such as direction and the amount of fibres, impregnation of fibres with the polymer matrix, and adhesion between fibres and the polymer matrix. Direction of the fibres can be unidirectional (vertical to the direction of loading), i.e. bidirectional or multidirectional (under different angles to the direction of loading), or even in random order. The amount of fibres also increases the strength of the composite, although reinforcement with fibres can only be efficient when loading is transferred from the matrix to the fibres. This requires good impregnation of the fibres with the polymer matrix, which depends on the type and viscosity of the polymer matrix (prior to polymerisation), and possibility of good wetting of each fibre. For improvement of adhesion between the polymer matrix and glass fibres bonding/ coupling agents are used, particularly silane. They bond to the surface of the glass by silane bridges and by co-polymerisation initiated by free radicals bond with the polymer matrix, thus improving adhesion between fibres and the polymer matrix. Apart from the mechanical properties, such good bonding is also important for reducing the unfavourable effect of water on the marginal surface of the fibre-base. [ABSTRACT FROM AUTHOR]

Copyright of Acta Stomatologica Croatica is the property of Acta Stomatologica Croatica and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Collegium Antropologicum is the property of Croatian Anthropological Society and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The author reflects on the celebration of the 50th anniversary of independence of the School of Dental Medicine at the University of Zagreb in Croatia. He says that the celebration is the moment to recount the long history of the dental profession and the study of dental medicine as well as to consider all the aspects of its present and future. He provides a brief history of the history of dental medicine in Croatia. He also notes the creation of the University of Zagreb's School of Dental Medicine pursuant to the decision of the Croatian Parliament Numner 688-62 Article 1 on September 26, 1962.

Aim To reveal patients' satisfaction with their old, usually poorly fitting dentures and the effect of denture relining to the patient's satisfaction. Methods Thirty-seven denture wearers participated in study by filling out questionnaires about their satisfaction with dentures before and after relining. In that way the data indicating the subjective patient's experience and satisfaction were collected. Results Relined removable dentures included in study were on average 5.52 years (upper) or 4.86 years old (lower). Most of study participants (57%) were satisfied with their poor fitting dentures. Statistically significant was correlation between chewing discomfort and satisfaction, and the time elapsed from last tooth extraction to denture production. As this period was shorter, chewing discomfort was greater and satisfaction with chewing lower. Majority (53.3%) of denture wearers were considerably more satisfied with the chewing ability and felt better regarding the chewing discomfort after denture relining. Minority of the patients (22%) still used an adhesive for fixing the dentures after relining. Conclusion Denture relining affects, patient's satisfaction with their dentures. After relining patient's masticatory function was improved, satisfaction with chewing ability and comfort were greater, and denture hygiene better. Denture relining should be performed in order to improve denture fitting to a denture bearing area, thus positively affecting patient's satisfaction with his denture(s). [ABSTRACT FROM AUTHOR]

Fractures of polymer material are one of the most frequent reasons for the repair of removable dental prostheses. Therefore, there is a constant endeavor to strengthen them, and polymer materials with high resistance to fracture are being developed. The aim of this study was to determine the flexural strength of polymer materials and their reinforcements and thus give preference to their clinical use. Specimens with dimensions 18 x 10 x 3 mm were tested after polymerization, immersion in water at a temperature 37 degrees C for 28 days, and thermocycling by using the "short-beam" method to determine the flexural strength. Microscopic examination was performed to determine the quality of bonding between the glass fibers and matrix. Common polymer materials (control group) demonstrated the lowest flexural strength, although, when reinforced with fibers they showed higher flexural strength, matching that of the tested high-impact strength resin. Thermocycled specimens had the highest flexural strength, whereas there was no difference (p > 0.05) between specimens tested after polymerization and immersion in water. [ABSTRACT FROM AUTHOR]