Morphological and chemical changes of dentin after applying different sterilization methods

Cláudio Antonio Talge Carvalho,Marcia Maciel Menezes Ferraz,Luciane Dias De Oliveira,Ana Claudia Carvalho Xavier,Antonio Olavo Cardoso Jorge,Márcia Carneiro Valera

doi:10.1590/1807-2577.1076

Cláudio Antonio Talge Carvalho, Marcia Maciel Menezes Ferraz + Show 4 more

Open Access

https://doi.org/10.1590/1807-2577.1076

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Abstract

Aim The present study evaluated the morphological and chemical changes of dentin produced by different sterilization methods, using scanning electron microscopy (SEM) and energy-dispersive X-ray spectrometry (EDS) analysis. Material and method Five human teeth were sectioned into 4 samples, each divided into 3 specimens. The specimens were separated into sterilization groups, as follows: wet heat under pressure; cobalt 60 gamma radiation; and control (without sterilization). After sterilization, the 60 specimens were analyzed by SEM under 3 magnifications: 1500X, 5000X, and 10000X. The images were analyzed by 3 calibrated examiners, who assigned scores according to the changes observed in the dentinal tubules: 0 = no morphological change; 1, 2 and 3 = slight, medium and complete obliteration of the dentinal tubules. The chemical composition of dentin was assessed by EDS, with 15 kV incidence and 1 μm penetration. Result The data obtained were submitted to the statistical tests of Kruskall-Wallis and ANOVA. It was observed that both sterilization methods – with autoclave and with cobalt 60 gamma radiation – produced no significant changes to the morphology of the dentinal tubules or to the chemical composition of dentin. Conclusion Both methods may thus be used to sterilize teeth for research conducted in vitro.

Highlights

Several in vitro studies utilize extracted human teeth, which must be submitted to sterilization in order to ensure greater safety to the researcher and obviate cross contamination
Other studies have demonstrated that dentin microhardness is affected when this kind of sterilization is used on teeth, insofar as this method could interfere with the ionic bond between collagen and hydroxyapatite[2], possibly producing biomechanical changes that may have gone undetected when the Pashley and Brown assessments were performed
A study conducted by Rodrigues et al.[13] showed that there is no significant difference between the initial microhardness of enamel and that observed after sterilization with gamma radiation

Summary

Introduction

Several in vitro studies utilize extracted human teeth, which must be submitted to sterilization in order to ensure greater safety to the researcher and obviate cross contamination. In order to obtain results closer to the clinical reality in in vitro research, no structural alteration of the tooth should occur during sterilization. Several authors have used different methods of tooth sterilization: wet heat under pressure (autoclave)[1,2], cobalt 60 gamma radiation[3,4,5], ethylene oxide[6], and chemical solutions[7]. It is essential to assess whether these methods produce any chemical or morphological alterations, and whether there are significant differences among them. Other studies have demonstrated that dentin microhardness is affected when this kind of sterilization is used on teeth, insofar as this method could interfere with the ionic bond between collagen and hydroxyapatite[2], possibly producing biomechanical changes that may have gone undetected when the Pashley and Brown assessments were performed

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