Comparison of three different techniques for histological tooth preparation

Abstract: The histological processing of teeth is highly complicated because of containing both mineralized hard tissues and soft tissues. Depending on the type of decalcification agents used in processing, mild-to-severe deterioration in the tissue structure and inadequacies on clear staining of details by the histological stain may be observed. This study aims to compare the histological staining differences in the preparations from decalcified and undecalcified tooth roots by three different embedding materials and techniques. Following extraction, human single-rooted teeth crowns were cut off and roots were placed in 10% buffered neutral formalin. After fixation, roots were divided into two groups. One part of samples was decalcified in formic acid solution and the other was remained undecalcified. Decalcified roots were embedded in paraffin and glycol methacrylate (GMA)-based resin and undecalcified roots were embedded in methyl methacrylate (MMA)-based resin. Sections from all groups were stained with hematoxylin and eosin. The groups were compared in terms of general staining, brightness, density, density of the base stain, general morphology of cells, nuclear/cytoplasmic contrast, distinguish ability of pulp, odontoblast layer, predentin and dentin, preservation and traceability of dentinal tubule. In the preparations which were embedded into the MMA-based embedding material, an output lower than the paraffin group buthigher than the GMA-embedded group was provided. As a result, the best histological detail was obtained from the decalcified, paraffin-embedded sections

ATF-2 immunoreactivity in post-mitotic and terminally differentiated human odontoblasts

Activating transcription factor 2 (ATF-2/CRE-BP1; cAMP-responsive element binding protein 1) is a member of nuclear transcription factor activator protein-1 (AP-1) family. AP-1 regulates cellular processes including growth, proliferation, differentiation and apoptosis. However, biological relationship of cellular process to each member of the AP-1 family is not clear yet. The objective of the present study was to compare the ATF-2 immunoreactivity in the post-mitotic and terminally differentiated odontoblasts and in the pulpal fibroblasts which can be divided by mitosis when required. Fibroblasts at various stages of differentiation co-exist in the human dental pulp. ATF-2 was investigated immunohistochemically in 20 permanent human teeth. According to the findings obtained, the mean percentage of ATF-2 positive cells was 68.5 +/- A 19.2 % in the odontoblasts and 22.8 +/- A 13.7 % in the pulpal fibroblasts. The comparison of ATF-2 positivity revealed a statistically significant difference between odontoblasts and pulpal fibroblasts. These findings have suggested that ATF-2 is more associated with cell survival rather than cell proliferation, and revealed much of effectiveness in maintaining terminal differentiation than the various differentiation stages of the cells

Comparison of three different techniques for histological tooth preparation

The histological processing of teeth is highly complicated because of containing both mineralized hard tissues and soft tissues. Depending on the type of decalcification agents used in processing, mild-to-severe deterioration in the tissue structure and inadequacies on clear staining of details by the histological stain may be observed. This study aims to compare the histological staining differences in the preparations from decalcified and undecalcified tooth roots by three different embedding materials and techniques. Following extraction, human single-rooted teeth crowns were cut off and roots were placed in 10% buffered neutral formalin. After fixation, roots were divided into two groups. One part of samples was decalcified in formic acid solution and the other was remained undecalcified. Decalcified roots were embedded in paraffin and glycol methacrylate (GMA)-based resin and undecalcified roots were embedded in methyl methacrylate (MMA)-based resin. Sections from all groups were stained with hematoxylin and eosin. The groups were compared in terms of general staining, brightness, density, density of the base stain, general morphology of cells, nuclear/cytoplasmic contrast, distinguishability of pulp, odontoblast layer, predentin and dentin, preservation and traceability of dentinal tubule. In the preparations which were embedded into the MMA-based embedding material, an output lower than the paraffin group but higher than the GMA-embedded group was provided. As a result, the best histological detail was obtained from the decalcified, paraffin-embedded sections

CELLULAR ROLE of TELOMERES

Proliferation capacity of normal somatic cells are limited. The most important reason of it is the fact that, the structure called telomere which is consist of DNA repetition, gets shorter in every cell cycle and it limits cell replication. Telomeres are formed of many repetition of hexanucleotide series (TTAGGG)n. Mentioned hexanucleotides are located on the end of eukaryotic lineer chromosomes and they have no protein code. Morever, telomeres accompanied by many forms of specific proteins are necessary in order to prevent undesired effects such as edge-fusions and nucleotic effects, and it is also necessary in order to preserve genomic integrity. Cells with limited replication capacity enters in replicative ageing through shortening of telomeres in every consecutive cell division. These proliferatively incapacitated cells in the stage of irreversible ageing are metabolically active. It is reported that, in various diseases, age is the most important risk factor and there is a relation between the length of telomere and diseases depend on ageing. The preservation of telomere length and its stability is provided by telomerase enzyme complex which has its own RNA and proteins. In human cells, while telomerase enzyme activity is observed every region of body in first weeks of embryo, after that in most of the cells, the telomerase activity decreases depending on age factor. In time, some cells proliferate indefinably after telomerase enzyme regulation or reactivation. Cancer cells are this type of cells. Telomere shortening is considered to be an effective tumor supressor mechanism