Impact of hypo-salivation on severe tooth wear: A ten-year cohort of patients received radiotherapy for nasopharyngeal carcinoma

Abstract

ObjectivesThis study was conducted to examine the tooth wear status of nasopharyngeal-carcinoma (NPC) patients who had received radiotherapy at least 5-year previously, and to investigate the salivary parameters that may be associated with the tooth wear. MethodsTooth wear status of NPC survivors were clinically assessed using the Exact Tooth Wear Index. A tooth was graded to have severe wear when more than one-third of its buccal/occlusal/lingual surface had dentine loss. At the subject-level, percentages of anterior/posterior/all teeth with severe wear were calculated. Age, number of teeth, flow-rate/buffering capacity/pH of stimulated whole (SWS) and parotid (SPS) saliva’s were collected. Correlation and multiple-linear regression tests were performed at the significance level α = 0.05. ResultSixty-eight participants (mean age of 60.0 ± 8.9), 697 anterior and 686 posterior teeth were examined with a mean of 10-years post-radiotherapy. Severe tooth wear was found in 63 (92.6 percent) participants, 288 anterior and 83 posterior teeth. The mean percentage of anterior/posterior/all teeth with severe wear were 42.3 ± 28.1, 14.5 ± 19.9 and 30.0 ± 21.7. Anterior teeth, particularly the incisal surface of central incisors were most affected. The mean flow-rate of SWS and SPS were 0.1 ± 0.1 ml/min and 0.03 ± 0.07 ml/min respectively. Thirty (44.1 percent) and 48 (70.6 percent) participants were found to have low/no buffering capacity of SWS and SPS respectively. Multiple-regression analyses revealed the SWS flow-rate was associated with the percentage of anterior teeth with severe wear (p=0.03). ConclusionAnterior tooth wear is a significant dental problem among NPC survivors and was associated with hypo-salivation. Clinical significancePatients with hypo-salivation should be being monitored for tooth wear particularly on the anterior teeth.