Demineralization of tooth enamel following radiation therapy; An in vitro microstructure and microhardness analysis
Jagadish Kudkuli1, Ashish Agrawal2, Om Prakash Gurjar3, Sunil Dutt Sharma4, PD Rekha1, Muhammed A. P. Manzoor1, Balwant Singh2, BS Rao1, Riaz Abdulla5
1 Yenepoya Research Centre, Yenepoya (Deemed to be University), Indore, India
2 Imaging Beamline (BL-4), BARC Beamline Section, Technical Physics Division, Indus-2, RRCAT, Indore, India
3 Department of Radiotherapy, Sri Aurobindo Institute of Medical Sciences, Indore, Madhya Pradesh, India
4 Radiological Physics and Advisory Division, Bhabha Atomic Research Centre; Department of Health Sciences, Homi Bhabha National Institute, Mumbai, Maharashtra, India
5 Depatment of Biomaterials & Research centre, Department of Oral pathology, Yenepoya Dental College, Yenepoya (Deemed to be University), Indore, India
Deparment of Biomaterials & Research centre Professor, Department of Oral pathology, Yenepoya Dental College, Yenepoya (Deemed to be University)
Source of Support: None, Conflict of Interest: None
Objective: The objective of this study is to evaluate the effects of radiotherapy doses on mineral density and percentage mineral volume of human permanent tooth enamel.
Materials and Methods: Synchrotron radiation Xray microcomputed tomography (SRμCT) and microhardness testing were carried out on 8 and 20 tooth samples, respectively. Enamel mineral density was derived from SRμCT technique using ImageJ software. Microhardness samples were subjected to Vickers indentations followed by calculation of microhardness and percentage mineral volume values using respective mathematical measures. Data were analyzed using paired t-test at a significance level of 5%. Qualitative analysis of the enamel microstructure was done with two-dimensional projection images and scanned electron micrographs using μCT and field emission scanning electron microscopy, respectively.
Results: Vickers microhardness and SRμCT techniques showed a decrease in microhardness and an increase in mineral density, respectively, in postirradiated samples. These changes were related to mineral density variation and alteration of hydroxyapatite crystal lattice in enamel surface. Enamel microstructure showed key features such as microporosities and loss of smooth homogeneous surface. These indicate tribological loss and delamination of enamel which might lead to radiation caries.
Conclusions: Tooth surface loss might be a major contributing factor for radiation caries in head-and-neck cancer patients prescribed to radiotherapy. Such direct effects of radiotherapy cause enamel abrasion, delamination, and damage to the dentinoenamel junction. Suitable measures should, therefore, be worked out to protect nontarget oral tissues such as teeth while delivering effective dosages to target regions.