Vol.:(0123456789) 1 3 Radiat Environ Biophys (2017) 56:187–192 DOI 10.1007/s00411-017-0690-9 ORIGINAL ARTICLE The role of fuoride and chlorhexidine in preserving hardness and mineralization of enamel and cementum after gamma irradiation Rowida Abdalla 1,4  · Maha A. Niazy 2  · Wael E. Jamil 2  · Hala A. Hazzaa 3  · Amal A. Elbatouti 4   Received: 23 September 2016 / Accepted: 15 March 2017 / Published online: 23 March 2017 © Springer-Verlag Berlin Heidelberg 2017 with chlorhexidine resulted in a signifcantly lower micro- hardness compared to sodium fuoride, both for the irra- diated and non-irradiated groups. It is concluded that gamma irradiation with therapeutic doses typically used for head and neck carcinoma treatment has a direct efect in reducing micro-hardness of tooth enamel and cementum. Mouthwash protocols including, for example, application of 0.05% sodium fuoride or 0.12% chlorhexidine three times per day for 6 weeks, can protect enamel and cemen- tum against the reduction in hardness and demineralization caused by gamma irradiation. Sodium fuoride ofers more protection compared to chlorhexidine. Keywords Radiotherapy · Enamel · Cementum · Gamma irradiation Introduction Recently, a relatively high incidence of head and neck car- cinoma including those of the oral cavity has been reported (Filion et al. 2010). Gamma irradiation is an important treatment regimen, either applied solely or as an adjuvant to surgery and chemotherapy (Wilken et al. 2011). Unfortu- nately, radiation therapy may also have devastating dento- oral efects. One of the most common late complications of head and neck radiotherapy is rampant caries afecting the entire dentition. This is commonly referred to as radiation caries (Konjhodzic-Prcici et al. 2010). Radiation caries is a rapidly progressing, and a highly destructive type of dental caries (Vissink et al. 2003). While it was assumed that this process is the result of xerostomia caused by gamma irradiation on salivary secre- tion, other disorders that cause xerostomia do not produce rampant caries that is nearly as destructive as the caries Abstract The purpose of this study was to evaluate the efect of 0.05% sodium fuoride and 0.12% chlorhexidine mouthwashes on the micro-hardness of tooth enamel and cementum that was exposed to therapeutic doses of gamma radiation. Sixty extracted human teeth were divided into two groups, one was irradiated, the other was not irradi- ated. The two groups were further subdivided into three subgroups, which were each treated either with 0.05% sodium fuoride or with 0.12% chlorhexidine; the third sub- group served as a control. After demineralization–reminer- alization cycling, teeth from the irradiated groups showed a signifcantly lower micro-hardness when compared to those from the non-irradiated groups. Both in the irradiated and non-irradiated groups, teeth from the control subgroups showed a signifcantly lower micro-hardness, as compared to teeth treated with sodium fuoride and chlorhexidine. For non-irradiated enamel samples, those treated with chlorhexidine showed a signifcantly less micro-hardness compared to those treated with sodium fuoride. In con- trast, irradiated enamel showed no signifcant diference in micro-hardness, whatever treatment (chlorhexidine or sodium fuoride) was applied. For cementum, treatment * Rowida Abdalla Rowida.abdalla@uky.edu 1 Division of Restorative Dentistry, Department of Oral Health Practice, University of Kentucky, Lexington, KY 40536-0297, USA 2 Operative Dentistry Department, Faculty of Dental Medicine, Al-Azhar University, Girls Branch, Cairo, Egypt 3 Oral medicine, Periodontology, Diagnosis and Radiology Department, Al-Azhar University, Girls Branch, Cairo, Egypt 4 Health Radiation Research Department, National Center for Radiation Research and Technology (NCRRT), Atomic Energy Authority, Cairo, Egypt