A simplified method for detecting Gram-positive and Gram-negative bacteria in dental histological samples: A preliminary and comparative study

• Published in: Acta histochemica 2023-01, Vol.125 (1), p.151992-151992, Article 151992
• Main Authors: Savadori, Paolo, Dalfino, Sophia, Piazzoni, Marco, Parrini, Matteo, Del Fabbro, Massimo, Tartaglia, Gianluca Martino, Giardino, Luciano
• Format: Article
• Language: English
• Subjects: Anti-Bacterial Agents; Bacteria; Dental tubules; Gram-Negative Bacteria; Gram-Positive Bacteria; Histological staining; Histology; Humans; Staining and Labeling
• ISSN: 0065-1281; 1618-0372
• DOI: 10.1016/j.acthis.2022.151992

Bacteria identification inside the dental tissue is a complex procedure requiring specific protocols. This study aimed to compare two classical Gram staining methods with a new staining method proposed by the authors to detect Gram-positive and Gram-negative bacteria in dental histological samples of human dentin. Ten human teeth, extracted because of various pathologies, were decalcified, dehydrated, and paraffin-embedded. Then, approximately 100 serial sections of 4 µm thickness were made per sample. The serial sections were placed on glass slides and were stained according to Brown-Brenn, Brown-Hopps, and a proposed modification of Brown-Brenn staining. Both ATCC strains, smeared on glass slides, were stained following each method's instructions used in histological samples. From a qualitative evaluation, the Brown-Brenn method resulted in better staining of Gram-positive bacteria, while the authors' proposed staining technique was more oriented towards Gram-negative bacteria. On the other hand, the Brown-Hopps showed quite a balance in detecting Gram-positive and Gram-negative bacteria. Unlike the Brown-Brenn stain, the other two protocols showed better stainability of Gram-negative microorganisms in bacterial-smeared samples. All staining techniques evaluated in this article can identify bacteria, but the outcome can change according to the staining procedure used. •G&S stain by changing the differentiation method could enhance Gram – bacteria identification in paraffin embeddend samples.