The Effect of Al2O3 Addition on the Thermal Diffusivity of Heat Activated Acrylic Resin.

AIM: This study aimed at investigating the effect of adding 5% to 20% by weight aluminium oxide powder (Al2O3) on thermal diffusivity of heat-polymerized acrylic resin. MATERIAL AND METHODS: Twenty five cylindrical test specimens with an embedded thermocouple were used to determine thermal diffusivity over a physiologic temperature range (0 to 70°C). The specimens were divided into five groups (5 specimens/group) which were coded A to E. Group A was the control group (unmodified acrylic resin specimens). The specimens of the remaining four groups were reinforced with 5%, 10%, 15%, and 20% Al2O3 by weight. RESULTS were analysed by using one-way analysis of variance (ANOVA). RESULTS: Test specimens which belonged to Group E showed the highest mean thermal diffusivity value of 10.7mm(2)/sec, followed by D (9.09mm(2)/sec), C (8.49mm(2)/sec), B(8.28mm(2)/sec) and A(6.48mm(2)/sec) groups respectively. Thermal diffusivities of the reinforced acrylic resins were found to be significantly higher than that of the unmodified acrylic resin. Thermal diffusivity was found to increase in proportion to the weight percentage of alumina filler. CONCLUSION: Al2O3 fillers have potential to provide increased thermal diffusivity. Increasing the heat transfer characteristics of the acrylic resin base material could lead to more patient satisfaction.

A Non-Invasive Technique which Demonstrates the Iron in the Buccal Mucosa of Sickle Cell Anaemia and Thalassaemia Patients who Undergo Repeated Blood Transfusions.

BACKGROUND: Iron is vital for all the living organisms. However, excess iron is hazardous because it produces free radical formation. Therefore, the iron absorption is carefully regulated to maintain an equilibrium between the absorption and the body loss of iron. Considering the lack of specific excretory pathways for iron in humans, an iron overload in the tissues is frequently encountered. It can be precipitated by a variety of conditions such as increased iron absorption, as is seen in haemochromatosis or a frequent parenteral iron administration, as is seen in thalassaemia and sickle cell anaemia patients (a transfusional overload). OBJECTIVES: To demonstrate the iron overload at an early stage by oral exfoliative cytology in the oral mucosal cells of thalassaemia and sickle cell anaemia patients and to compare the presence of iron in the exfoliated oral epithelial cells with that of the serum ferritin levels in those patients. MATERIALS AND METHODS: The present study comprised of 40 ß- thalassaemia major and 20 sickle cell anaemia patients who were undergoing repeated blood transfusions of a minimum of 15/more, along with 60 clinically healthy individuals. Scrapings were obtained from the buccal mucosa and they were smeared onto glass slides. Then the slides were stained with a Perl's Prussian staining kit and they were examined under a light microscope. RESULTS: 72.5% of the thalassaemia patients and 35% of the sickle cell anaemia patients revealed a positivity for the Perl's Prussian blue reaction and none of the controls showed this positivity. It was also observed that as the serum ferritin levels increased, the iron overload in the oral mucosal cells of the thalassaemia patients also increased, which was not statistically significant, whereas it was statistically significant in case of the sickle cell anemia patients. CONCLUSION: Since the exfoliative cytology is a simple, painless, non-invasive and a quick procedure to perform, a lot of research should be carried out on the correlation of the Perl's Prussian blue reaction to the serum ferritin levels.

Immunohistochemical Expression of PCNA in Epithelial Linings of Selected Odontogenic Lesions.

AIM: Though odontogenic lesions have in common origin from the primitive odontogenic epithelium , there is a diversity in their initiation behavior and growth. The aggressive nature of odontogenic keratocyst similar to ameloblastoma in comparision with the other common odontogenic (dentigerous and radicular) cyst could be due to possible differences in their epithelial linings. PCNA (Proliferating cell nuclear antigen) is a cell cycle related antigen, used in the study of cell kinetics of these epithelial linings, to corelate the biological behaviour among these common odontogenic lesions. OBJECTIVES: This paper has intended to study the cell kinetics of 4 selected odontogenic lesions (dentigerous cyst, radicular cyst,odontogenic keratocyst and ameloblastoma) to demonstrate differences in their epithelial linings. MATERIAL AND METHODS: Sixty samples of paraffin embedded tissue specimens (archival tissues) were included (15 radicularcysts, 15 odontogenic keratocysts; 15 dentigerous cysts and15 Ameloblastoma. RESULTS: Among cyst OKC had higher values than DC and RC. When staining results of all the cyst were compared individually with ameloblastoma ,the staining results of OKC was similar to ameloblastoma ,and ameloblastoma presented higher values than OKC (p=0.000). CONCLUSION: The results of this study show 1) Though OKC and DC are developmental in origin and radicular cyst is inflammatory, OKC has intrinsic growth potential among these cyst 2). Ameloblastoma has similar proliferative potential as OKC and hence it has been reinforced as KCOT(Keratocystic odontogenic tumour) in the recent classification.