Comparative analysis of two fixating and two decalcifying solutions for processing of human primary teeth with inactive dentin carious lesion

Abstract

O objetivo deste estudo foi analisar qualitativamente a preservação das características teciduais pulpares de dentes decíduos ântero-superiores humanos com lesão cariosa de natureza inativa em dentina, comparando-se duas soluções fixadoras (paraformaldeído a 4% e formalina a 10%, ambos com tampão fosfato 0,1 M) e descalcificadoras [ácido fórmico/citrato de sódio û solução de Ana Morse e EDTA (ácido etileno diamino tetracético) a 10%]. Oito dentes foram subdivididos em 4 grupos (n = 2), variando-se o agente fixador e descalcificador. Grupo 1: paraformaldeído a 4% e solução de Ana Morse; Grupo 2: formalina a 10% e solução de Ana Morse; Grupo 3: paraformaldeído a 4% e EDTA a 10%; Grupo 4: formalina a 10% e EDTA a 10%. Os dentes foram fixados e posteriormente descalcificados até que uma consistência borrachóide fosse obtida. Cortes histológicos de 6μm de espessura foram corados com hematoxilina e eosina (H&E). A fixação com ambas as soluções demonstrou boa conservação tecidual, enquanto que a descalcificação com a solução de Ana Morse pareceu mais adequada, por requerer um menor tempo de processamento das amostras e promover uma melhor preservação dos componentes celulares e da matriz extracelular do tecido pulpar. O EDTA, além de exigir um tempo mais longo de processamento das peças, alterou as características morfológicas da polpa. A combinação formol a 10% û solução de Ana Morse pareceu ser favorável para a metodologia deste estudo.

The aim of this study was to analyze qualitatively the pulp tissue characteristics of maxillary anterior human primary teeth with inactive dentin carious lesion. Two buffered fixating solutions (4% paraformaldehyde and 10% formalin) and two decalcifying solutions (formic acid plus sodium citrate – Ana Morse solution and 10% ethylene-diaminotetraacetic acid (EDTA) were evaluated. Eight teeth were assigned to 4 groups (n=2), according to the fixating and decalcifying agents used. Group 1: 4% paraformaldehyde and Ana Morse solution; Group 2: 10% formalin and Ana Morse solution; Group 3: 4% paraformaldehyde and 10% EDTA; Group 4: 10% formalin and 10% EDTA. The teeth were fixed and thereafter decalcified until a rubber-like consistency was obtained. After histological processing, serial 6-μm-thick sections were obtained and stained with hematoxylin and eosin (H & E). Both fixating solutions provided good preservation of the pulp tissue, showing the normal tissue topography. However, the use of 10% EDTA caused tissue damage, which was evidenced by the cell aspect and the altered extracellular matrix (ECM) characteristics. Decalcification with Ana Morse solution seemed to produce better preservation of cells and ECM morphology. The association of Ana Morse solution and 10% formalin was more favorable for the pulp tissue. In conclusion, fixation with either solution yielded good tissue preservation, while decalcification with Ana Morse solution required a shorter time for specimen processing and promoted better preservation of cell components and pulpal ECM. EDTA modified the pulpal morphological properties and required a longer processing time. The combination of 10% formalin and Ana Morse solution seemed to be the most favorable for the proposed methodology.