Effect and mechanism of photodynamic therapy on dental caries in rats
10.7683/xxyxyxb.2018.01.004
- VernacularTitle:光动力疗法对大鼠龋齿模型的防龋效果及机制
- Author:
Ying-Ying MA
1
;
Zhao-Hui ZOU
Author Information
1. 郑州市口腔医院牙体牙髓科
- Keywords:
rat;
dental caries;
hematoporyrin monomethyl ether;
photodynamic therapy;
Keyes score
- From:
Journal of Xinxiang Medical College
2018;35(1):16-21
- CountryChina
- Language:Chinese
-
Abstract:
Objective To evaluate the effect of photodynamic therapy (PDT) on dental caries in rats,and to investigate the mechanism.Methods Forty male Wistar rats (21 days old,specific pathogen-free,weaned) with dental caries induced by Streptococcus mutans were randomly divided into saline group,hematoporphyrin monomethyl ether (HMME)-PDT group,simple laser group,simple photosensitizer group and sodium fluoride group,with eight rats in each group.The molars of rats in the saline group were smear repeatedly for 5 minutes with cotton balls containing 150 μL normal saline.The molars of rats in HMME-PDT group were incubated for 5 minutes without light by placing the cotton balls containing 150 μL HMME (40 mg · L-1) on the tooth surface,then molars were irradiated vertically by 532 nm semiconductor laser,the power density was 140 mW · cm-2,the irradiation time was 90 s,and the energy density was 12.6 J · cm-2.The molars of rats in the simple laser group were irradiated vertically by 532 nm semiconductor laser;the irradiation time,power density and energy density were the same as those in HMME-PDT group;but the molars were not treated with HMME.The molars of rats in the simple photosensitizer group were smear repeatedly for 5 minutes with cotton balls containing 150 μL HMME (40 mg · L-1),but the molars were not irradiated by laser.The molars of rats in the sodium fluoride group were smear repeatedly for 5 minutes with cotton balls containing 150 μL fluorinse (2 g · L-1).The rats in each group were treated once a week for 4 weeks.Streptococcus mutans were collected from oral cavity of rats after each treatment,and bacterial inhibition was recorded by plate count.The rats were killed after 4 weeks,and the Keyes caries score was recorded.The surface morphology of the teeth was observed by scanning electron microscope.Results The time factor had no effect on the growth of oral Streptococcus mutans (F =0.11,P ＞ 0.05),the treatment factor had effect on the growth of oral Streptococcus mutans (F =230.89,P ＜ 0.05),and there was interaction effect between treatment factor and time factor (F =6.36,P ＜ 0.05).The colony number of Streptococcus mutans in HMME-PDT group and sodium fluoride group was lower than that in saline group,photosensitizer group and simple laser group at the first,second,third and fourth week after treatment (P ＜ 0.05).The colony number of Streptococcus mutans in HMME-PDT group was lower than that in sodium fluoride group at the first,second and third week after treatment (P ＜ 0.05).The Dx caries lesion of smooth surface caries wasn't found in each group.The Dm caries lesion of smooth surface caries wasn't found in the HMME-PDT group and sodium fluoride group.The Keyes scores of E and Ds caries lesion of smooth surface caries in the HMME-PDT group and sodium fluoride group was lower than that in the saline group,simple photosensitizer group and simple laser group(P ＜0.05),but there was no significant difference in the Keyes scores of E and Ds caries lesion of smooth surface caries between the HMME-PDT group and sodium fluoride group(P ＞0.05).The Dx caries lesion of pit and fissure caries was found in the saline group only.The Keyes score of E,Ds and Dm caries lesion of pit and fissure caries in the HMME-PDT group and sodium fluoride group was lower than that in the saline group,simple photosensitizer group and simple laser group (P ＜ 0.05),but there was no significant difference in the Keyes scores of E,Ds and Dm caries lesion of pit and fissure caries between the HMME-PDT group and sodium fluoride group(P ＞ 0.05).The results of scanning electron microscopy showed that the enamel surface was rough,uneven and there was a large number of scratch in the saline group and simple photosensitizer group.Relatively the enamel surface in the simple laser group was smooth,and there was a small circular scallops and dents was found in the structure;in the sodium fluoride group,the enamel surface was relatively smooth,take off the mining area was less,and remineralization was found.In the HMME-PDT group,the enamel surface was smooth,pitting was reduced and take off the mining area was small.Conclusion HMME-PDT had significant inhibitive efficacy on caries development in rats by reducing the number of cariogenic bacteria and improving the structure of the teeth.
