1Experimental study on the bonding strength of pure titanium after treatment with cold atmospheric plasma to zirconiaGE Xin, XIE Yan-ting, GU Shu-yang, DENG Chun-fu, LIN Zeng, LI Shao-jie, JIANG Lu-lu, WANG Dan-ning, ZHAO Bao-hongORIGINAL CONTRIBUTIONS532-537,5422A comparative study of demographic sociological characteristics between refractory and general recurrent aphthous ulcerLIU Qin, DUAN Ning, WANG Xiang, RUAN Huan-huan, SONG Yue-feng, LIN Lin, JIANG Hong-liu, LI Jing-jing, WANG Wen-meiORIGINAL CONTRIBUTIONS538-5423Detection and analysis of four anaerobic bacteria in different types of infected root canalsHUANG Yan-hua, LIU Shu, GE Jiu-yuORIGINAL CONTRIBUTIONS547-5514Research progress of correlation between Helicobacter pylori infection and periodontitisSUN Jing, YUAN Shao-zhongREVIEW565-5685Effect of storage medium of avulsed tooth on periodontal ligament cells and the mechanismJI Ling-li, CHEN XuREVIEW569-5726The effect and possible mechanisms of suspected periodontal pathogens on chronic kidney diseaseWANG Yi-fan, HU Wei, FANG Shu, GAO Yi-fan, GUO BinREVIEW573-576