The effect of heating rate and sintering temperature on the elastic modulus of porcelain tiles.

The scope of the present study is to investigate the change of elastic modulus with the physical and mechanical properties of porcelain tiles. In the study, porcelain tiles were sintered at different temperatures and at different heating rates to obtain minimum water absorption (%). After this, the time of flight of longitudinal and shear ultrasonic waves was measured through the tile. The time of flight of ultrasonic waves was measured using contact ultrasonic transducers operating on a pulse-echo mode. Using the time of flight of the ultrasonic waves and the thickness of the tiles, the velocity of the waves was determined. Using the ultrasonic velocities and bulk density, the elastic modulus of the tiles was determined. Helium pycnometry, a bend test, scanning electron microscopy (SEM) and X-ray diffraction (XRD) analyses were also carried out. The results show that the elastic modulus decreased with an increase of total porosity, but increased with bulk density and firing shrinkage. There is a polynomial relationship between elastic modulus and strength.

Difficulties in health care for female Turkish immigrants with type 2 diabetes: a qualitative study in Vienna.

According to studies, type 2 diabetes mellitus (DMT2) is more commonly encountered among Turkish immigrants than resident populations in Europe and Turkish people living in Turkey. Within this context this study focused on female Turkish immigrants with DMT2 who are living in Vienna. The purpose of this study was to determine the needs, expectations, special conditions and cultural characteristics of Turkish women with DMT2 by gathering information about their own perceptions about DMT2, difficulties encountered during the diagnosis, treatment and their experiences living with the disease. A qualitative phenomenological design was utilized with a sample of 13 participants recruited from the Turkish mosques in Vienna. The interview guide, which included semi-structured questions, was based on previous studies conducted on DMT2 and immigration. Interviews were transcribed verbally from tape recordings, translated into German and each statement paraphrased for further analysis. The interviews indicated participants' degree of knowledge about DMT2 and was the most significant factor affecting approaches to the disease. The most important difficulty for the participants was the re-organization of nutritional habits to DMT2 because of the Turkish cuisine culture. The results of this study can be utilized by the health care providers to gain an understanding of Turkish immigrants and DMT2. Thus, it will enable them to adapt their health care and education to meet the needs of this population better.

A 5 year retrospective study of biopsied jaw lesions with the assessment of concordance between clinical and histopathological diagnoses.

INTRODUCTION: The jaw can be affected by several lesions that manifest in the oral cavity, but little is known about their distribution patterns in various populations. AIMS AND OBJECTIVES: This study presents the frequency and distribution of biopsied jaw lesions recorded in Faculty of Dentistry and gathers the information including provisional and final diagnosis of the lesions. MATERIAL AND METHODS: Biopsy of 1938 lesions (2008-2013) was reviewed and 1473 lesions were included in this study. The provisional diagnosis and histopathological validations of lesions were compared. Data on the location of the lesion, as well as patient demographics, were also evaluated. The lesions were divided into three major groups as 1 - developmental/reactive and inflammatory lesions of the jaw, 2 - cystic lesion and 3 - tumor and tumor-like lesions. STATISTICAL ANALYSIS: The variables were recorded and analysed using descriptive statistics. RESULTS AND OBSERVATIONS: Three hundred and ninety-six lesions were in Group 1 and periapical granuloma was the most frequent diagnosis. Seven hundred and eighty-nine lesions were in Group 2 and the radicular cyst was the most frequent diagnosis. Two hundred and eighty-eight lesions were in Group 3 and the keratocystic odontogenic tumor was the most frequent. Two hundred and ninety-one biopsied lesions were in disagreement with respect to the diagnoses on clinical and histopathological examination. CONCLUSION: Consequently, a provisional diagnosis of some of the malignant lesions was reactive, inflammatory, cystic or benign lesions, therefore the importance of evaluation of the specimen is emphasized.

Expression of p16 protein is associated with human papillomavirus status in tonsillar carcinomas and has implications on survival.

Our recent analysis of papillomavirus (HPV) DNA in different malignant head and neck tumors revealed that HPV infections occurred most frequently in tonsillar carcinomas (58%) and that 84% of positive cases contained the highly oncogenic HPV type 16. We could also present data in favor of the hypothesis that in view of their clinical behavior and the involved risk factors HPV-positive and HPV-negative tonsillar carcinomas may represent two separate tumor entities. Looking for a surrogate marker, which in further epidemiological studies could replace the laborious and expensive HPV detection/typing we analyzed p16 protein expression in 34 tonsillar carcinomas for their correlation with HPV status. p16 is an inhibitor of cyclin-dependent kinases 4 and 6 which activate the negative cell cycle regulator protein pRB which in turn downregulates p16 expression. It could be shown that in neoplastic cells of the cervix uteri E7 protein of the high-risk HPVs can interfere with this regulatory circuit by its virtue to inactivate pRB and thus lead to the overexpession of p16. We found 53% of the tested tonsillar carcinomas to be HPV positive. 56% of all tumors tested were immunohistochemically positive for the p16 protein. In 16 of 18 of the HPV-positive carcinomas diffuse p16 expression was observed. In contrast, only 1 of the HPV-negative carcinomas showed focal p16 staining (p < 0.001). Clinical outcome analysis revealed a significant correlation of p16 expression with increased disease-free survival (p = 0.02). These data indicate that p16 is a technically simple immunohistological marker, applicable for routine pathological histology, and its prognostic value for survival is fully equivalent to HPV DNA detection.

Evaluation of periodontal healing in class II furcation defects following guided tissue regeneration with two different types of polylactic acid membranes.

BACKGROUND: Guided tissue regeneration procedures provide predictable reconstruction of periodontal tissues in the treatment of furcation involvements in animals and humans. This study was to compare long-term effectiveness of two different types of polylactic acid (PLA) membranes on periodontal regeneration in surgically created class II furcation defects in dogs. METHODS: Full thickness mucoperiosteal flap was raised on the buccal aspects of the experimental teeth and class II furcation defects having 5 mm vertical dimensions were created on mandibular premolar III and IV on each quadrant. The exposed root surfaces were thoroughly planed and PLA membranes were placed over the experimental defects on both sites. One site received liquid polymer membrane (LPM), and resorbable periodontal mesh (RPM) membranes were applied to the other site. The animals were sacrificed at 7 months after surgery and the specimens were processed for histological evaluation. RESULTS: The average length of new attachment formed on the treated roots in both groups ranged from 3.02 mm to 4.5 mm. Complete bone filling was observed at the furcation sites. No statistically significant differences were found between two membranes in any of the parameters (P > 0.05). CONCLUSION: This study demonstrates favorable regenerative outcomes by the use of two different types of PLA membranes that could be used as alternatives for guided tissue regeneration (GTR).

Expression of p16 protein identifies a distinct entity of tonsillar carcinomas associated with human papillomavirus.

Recent analyses of head and neck squamous cell carcinomas revealed frequent infections by oncogenic human papillomavirus (HPV) type 16 in tonsillar carcinomas. Concerning involvement of risk factors, clinical course of the disease, and prognosis there are strong indications arguing that the HPV-positive tonsillar carcinomas may represent a separate tumor entity. Looking for a surrogate marker, which in further epidemiological studies could replace the laborious and expensive HPV detection and typing we analyzed p16 protein expression in 34 tonsillar carcinoma for correlation to HPV status and load of viral DNA. p16 has been shown to be of diagnostic value for clinical evaluation of cervical dysplasia. We found 53% of the tested tonsillar carcinomas to be HPV-positive. Fifty-six percent of all tumors tested were immunohistochemically positive for the p16 protein. In 16 of 18 of the HPV-positive carcinomas diffuse p16 expression was observed. In contrast, only one of the HPV-negative carcinomas showed focal p16 staining (P < 0.001). As determined by laser-assisted microdissection and quantitative real-time polymerase chain reaction, p16 expression correlated with the presence of HPV-DNA in the individual tumor specimens. Clinical outcome analysis revealed significant correlation of p16 expression with increased disease-free survival (P = 0.02). These data indicate that p16 is a technically simple immunohistological marker, applicable for routine pathological histology, and its prognostic value for survival is fully equivalent to HPV-DNA detection.

Effect of polylactide/glycolide (PLGA) membranes loaded with metronidazole on periodontal regeneration following guided tissue regeneration in dogs.

BACKGROUND: Bioabsorbable membranes have been successfully used for guided tissue regeneration (GTR) and local delivery systems because they are biocompatible and do not require second surgery for removal. Several studies have demonstrated that metronidazole, when applied topically, produced immediate effects on microbiological and clinical parameters, most notably a reduction in probing depth and loss of attachment. The purpose of this study was to evaluate the regenerative potential of a metronidazole-loaded biodegradable (polylactide/glycolide) (PLGA) GTR membrane in dogs. METHODS: Six male adult dogs with 36 created osseous defects were enrolled. Bilateral dehiscence type defects in 5 mm diameter were created at buccal aspect of the alveolar bone in maxillary premolar teeth. After full thickness flap elevation, exposed root surfaces were thoroughly planed. In the experimental sites, PLGA membranes with or without metronidazole were fitted and placed over the defects. On the control defects only root planing was performed. Gingival flaps were replaced slightly coronal to the cemento-enamel junction. Animals were sacrificed at 60 days. The histometric analysis was evaluated with the following parameters: defect height (DH), apical extension of junctional epithelium (AEJE), new cementum height (NCH), new bone height (NBH), and new gingival connective tissue height (NCTH). RESULTS: Postoperative clinical healing was similar in the 3 groups. There were no statistically significant differences between the 2 experimental groups in any parameters. Statistically significant differences were observed for AEJE, NCH, NBH, and NCTH in experimental groups when compared with the controls. Statistically significantly greater NCH, NBH, and NCTH were seen in the experimental groups than the controls and control defects showed longer AEJE than the experimental defects. CONCLUSIONS: These results suggest that PLGA membranes with and without metronidazole may have a beneficial effect on periodontal regeneration.