00326nam a22001217a 4500003000400000020001800004082001800022100002500040245004300065260006400108300001300172650001900185SGT  a9780323400800  a617.645bU15F  aFrank A. Scannapieco  aUnanswered Questions in Periodontology  aPhiladelphia, United StatesbHealth Sciences Divisionc2015  a761-1002  aPeriodontology