Study On The Protective Effect Of Individual Prolonged PMMA Stent On Oral Mucosa In Radiotherapy Of Nasopharyngeal Carcinoma

Research background and objectIntensity modulated radiation therapy(IMRT),as the most effective treatment for Nasopharyngeal carcinoma,not only affects tumor cells,but also causes damage to normal oral tissue around the target area.At present,in IMRT,it is common to increase the space distance between the target area and the tongue and oral mucosa by wearing the oral stent,so as to reduce radiation-induced oral mucositis(RIOM)and protect the oral mucosa around the target area.However,there are shortcomings and deficiencies in various materials and processes of making oral stent.In this study,individualized extended polymethyl methacrylate(PMMA)oral stent(hereinafter referred to as PMMA oral stent)was compared with the commonly used mold used for high density foam plug(hereinafter referred to as simple plug)to explore its protective effect on normal oral mucosa in nasopharyngeal carcinoma IMRT.Materials and methodsFrom December 2017 to June 2019,40 patients with nasopharynx undergoing IMRT in the Radiotherapy Department of Weihai Municipal Hospital were randomly divided into the experimental group and the control group.The experimental group(20 cases)made PMMA oral stent and wore it in IMRT,and the control group(20 cases)made simple oral plug and wore it in IMRT.Both groups were given IMRT and conventional radiotherapy care.To compare the homogeneity index(HI),conformal index(CI)and irradiation dose of organs at risk(tip of tongue,body of tongue and root of tongue)between the two groups,and to collect and analyze the Riom pain degree,oral mucosa injury degree,dry mouth degree,taste injury degree during and after the treatment.ResultsThere was no significant difference in HI and CI between the two groups(P > 0.05).The mean dose of exposure(Dmean)in different parts of the tongue was calculated.In theexperimental group,23.725 ± 16.055 Gy in the root of tongue,20.976 ± 14.441 Gy in the body of tongue and 21.810 ± 15.109 Gy in the tip of tongue;In the control group,26.626 ±16.276 Gy in the root of tongue,32.445 ± 10.896 Gy in the body of tongue and 35.297 ±11.393 Gy in the tip of tongue.There was a significant difference in Dmean between the two groups in the body of the tongue and the tip of the tongue(P<0.05),but no significant difference in the root of the tongue(P > 0.05).The mucosal damage degree of the soft palate,posterior pharyngeal wall,tongue tip,tongue body and tongue root was compared,and the mucosal damage degree of the patients in the control group was more serious,and the difference was statistically significant(P<0.05).There was no significant difference in the injury degree of buccal mucosa,inferior buccal mucosa and hard palate mucosa(P >0.05).The number of pain was 3,4,10,2,1,0 in the experimental group and 0,1,7,2,8,2 in the control group respectively.Compared with the degree of pain in the two groups,the difference was statistically significant(P < 0.05).Both groups had different degrees of taste impairment and dry mouth symptoms,but the degree of the experimental group was mild,the difference was statistically significant(P < 0.05).ConclusionWearing individualized prolonged PMMA stent can reduce the dose of IMRT on the tongue and tip without affecting the effect of IMRT,and reduce the complications of IMRT such as soft palate,posterior pharyngeal wall,tongue tip,tongue body,tongue root,RIOM and dry mouth,taste damage,so as to protect the normal oral mucosa,which has good clinical promotion value.