Ankara Universitesi Dis Hekimligi Fakultesi dergisi = The Journal of the Dental Faculty of Ankara University最新文献

The bonding of metal and porcelain through a firing process is rather a complex phenomenon. Besides the factors that act in bonding, the thermal properties of both materials also affect this mechanism. Different expansion and contraction behaviours of porcelain and metal cause some interface stresses. It is observed that the major objectives of the researches are to measure and determine these stresses and expose the variables affecting them. Porcelain glass transition temperature is one of the variables that the studies have focused on.

Many researchers defended the thesis of eradicating the apical foramen microleakage for a successful root canal treatment. This study has been designed to defect whether microorganisms will grow or not at the empty root canals as a result of the perfect obstruction of the apical foramen with histoacryl of least microleakage retrogradely. The study has been realized on 24 teeth of 6 adult dogs. Histoacryl was used to obstruct the apical foramens and the experimental animals were anesthetized with general anesthesia. Experimental animals were divided into three groups before the operation. At each group, eight teeth of two experimental animals were studied on. Consequently, a great amount of streptococcus kind, lactobacillus and staphylococcus were isolated at the cultures taken from the root canals of 15 days cases. At 30 day cases, peptostreptococus, lacto bacillus and staphylococcus were isolated while at 60 day cases streptococcus pneumonia, and lactobacillus were isolated and evaluated as meaningless.

Both lingual and incisal rest seats are used on anterior teeth. Lingual rest seats are preferred since they are more acceptable esthetically and located closer to the centre of rotation of the tooth. Lingual rest seats can be prepared directly on the abutment teeth as grooves, shoulders or may require restorations such as crowns, inlays and prefabricated rest seats to provide proper contour. In this study, the stress induced by two conventionally applied rest seats were compared with that of the U shaped rest seats which were recently induced. As a result it is found that more uniform stress distribution occurred in U and inverted "v" type rest seat designs.

The adherence of cariogenic S. mutans, to dental restorative materials in vitro has been reported previously. The purpose of this study was to evaluate the ability of S. mutans, to colonize on metallic and nonmetallic composite restorative materials in vivo. A total of 30 plaque samples from patients with metallic restorations, and 30 plaque samples from the patients with nonmetallic restorations obtained. This study indicates that, composite restorative materials and unpolished surfaces tend to be more highly colonized by S. mutans, than metallic and polished surfaces.

Alpha-1-antitrypsin (AAT) is a serum protease inhibitor, with a well established role in bodily defense against destructive inflammatory disease. In order to investigate the role of this protease inhibitor in the periapical lesions, 13 patients were investigated. Serum alpha-1-antitrypsin levels of 13 patients were 871.8 +/- 73.6 mg/dl whereas 296.6 +/- 32.6 mg/dl in the control group. Difference was important between both groups (P less than 0.01). Alpha-1-antitrypsin levels were 40.2 +/- 13.7 mg/dl in the cyst fluid. Although the alpha-1-antitrypsin levels in the patients serum were elevated, it was not found in sufficient levels in the cyst fluid. This results suggest that, the regulation of proteolytic activity afforded by AAT, plays an important role in the pathogenesis of periapical lesions.

This investigation was carried on eight patients who had undergone partial maxillary resection for the eradication of tumors. Two types of obturators, one being hollow-bulb and the other buccal flange were constructed for each patient, using different impression techniques. When these were compared clinically, it was concluded that buccal flange obturators which were constructed without closed hollow sections were superior to the hollow-bulb obturators with closed nasal sections extending as far as possible into the anterior and lateral aspects of the defect, in comfort, function, speech and stabilization.

Overlay dentures which are accepted as superposition appliances have been presented by three cases in this article. These kind of dentures are dedicated as prosthodontic restorations which are applied to extend maxillary arch horizontally in the cases of maxillary collapse. These restorations also increase the vertical dimension which has been lost and so help to improve the facial contour as well as esthetics of the individual-these dentures classified as removable partial or complete overlay dentures are generally applied in the cases of bilateral or unilateral maxillary collapse which have been caused by trauma or tumor resection.

Calculus plays an important role in chronic inflammatory periodontal diseases. Currently, there is much interest in dentifrices that have the capacity to reduce the formation of calculus. Recent clinical studies have indicated that dentifrices containing soluble pyrophosphate and sodium fluoride can reduce the formation of supragingival calculus. The purpose of this study was to compare the effect on supragingival calculus of a dentifrice containing soluble pyrophosphate and 0.24% sodium fluoride to a placebo dentifrice. Thirty five subjects were stratified into balanced groups based on initial calculus scores. They then received an oral prophylaxis and were assigned to the use of either the placebo or soluble pyrophosphate/sodium fluoride dentifrice for the next 3 months. The results from the 3-month examinations indicated that the dentifrice containing the soluble pyrophosphate and sodium fluoride did not significantly reduce supragingival calculus as compared to the placebo dentifrice. However, both dentifrices reduced the calculus significantly.

The research in the field of metal casting has recorded a continual progress in dentistry. Particularly, due to the economic problems posed by the use of gold alloys relatively inexpensive metal alloys tend to gain increased popularity. Application of such alloys physically in dentistry and their adaptability to various preparations are being studied. In castings where investment expansion methods are employed, and marginal adaptability of castings are evaluated, the results of variance analysis have indicated little significant difference due to the applied methods. However, the hygroscopic method has proved highly successful in terms of marginal adaptability.

To be used as a model in dental and medical research, an animal must fulfil experimental needs and information on the composition and variation of its oral flora must be available. Only limited data are available on the indigenous oral bacterial flora of dogs. In this research, a total of 100 isolates from the same sites of the oral cavities of dogs were identified. Only 17 different species were isolated. The predominant species of the total cultivable flora were Staphylococcus (coagulase +, and - types), and E. coli species. This is thought to be occurred as a result of constant licking habit of these animals.