Comparative histologic evaluation of teeth decalcified by conventional method versus microwave induced decalcification

Introduction: Complete demineralization of hard tissues with preservation of organic components to retain their tissue architecture and to obtain thin section for histological examination is done by a process known as "decalcification". Tooth decalcification may be achieved by subjecting the tissue to a decalcifying chemical agent and employing heat, vacuum, or electric current to enhance the procedure. Completion of decalcification is adjudged by determination of end-point. Histological examination of hard tooth tissues and pulp is essential for diagnosis of developmental pathologies, pulp pathologies, and forensic odontology analysis as well as for research purpose.

Aim: In our study, we studied the time consumed for decalcification procedure by conventional decalcification method and with the microwave-assisted decalcification method for teeth, using 5% nitric acid, 5% trichloracetic acid, and 14% EDTA (Ethylenediaminetetraacetic acid), respectively, along with morphological preservation of dentin and pulp tissue by analyzing preservation of their issue structure (pulp shrinkage, odontoblastic layer damage) and staining efficacy (patchy staining) for the three types of decalcifying agents used.

Materials and method: The sample for this study included 120 freshly extracted teeth consisting of teeth of mandibular dentition. Samples were divided into two study groups:Group I: Decalcified by Conventional methodGroup II: Decalcified by Microwave method.Each group consisted of, three sub-groups employing a different decalcifying agent from among the three decalcifying agents used, that is, 5% nitric acids, 5% trichloroacetic acid, and 14%EDTA respectively.

Result: The difference in speed of decalcification for both groups showed significant result. In either group, decalcification was fastest using 5% nitric acid. The difference in number of decalcified teeth sections showing shrinkage of pulp was not statistically significant for both groups. Damaged odontoblastic layer was evident only in the teeth treated with 5% nitric acid by microwave method. Patchy staining was observed in a few samples of all sample groups except those decalcified with EDTA by conventional method but the results were not statistically different on intercomparison.

Discussion and conclusion: Our results are similar to those of previous studies and we found that microwave method is an option that can reduce the time of decalcification. Tooth tissue morphology also was noted to be well preserved with 5% trichloracetic acid and 14% EDTA in comparison to 5% Nitric acid.