Architecture ofIntact Natural HumanPlaque Biofilms Studied byConfocal Laser Scanning Microscopy

ofthestructure ofhumanplaque willbeofgreat benefit intheprediction ofits formation andalsotheeffects oftreatment. However, aproblem lies intheharvesting of undisturbed intact plaque samples fromhuman volunteers andtheviewing ofthebiofilms intheir natural state. Inthisstudy, weusedaninsitu device fortheinvivogeneration ofintact dental plaque biofilms onnatural tooth surfaces inhuman subjects. Twodevices wereplaced inthemouths ofeach of healthy volunteers andleft to generate biofilm for4days. Immediately upon removal fromthemouth, theintact, undisturbed biofilms wereimagedbythenon-invasive technique ofconfocal microscopy inbothreflected light andfluorescence mode.Depthmeasurements indicated that theplaque formed inthedevices was thicker roundtheedgesattheenamel/nylon junction (range = 75-220 pm)thaninthecenter of thedevices (range = 35-215Vim). Thereflected- light confocal imagesshowedaheterogeneous structure inalloftheplaque biofilms examined; channels andvoids wereclearly visible. Thisisin contrast toimages generated previously byelectron microscopy, suggesting amorecompact structure. Staining ofthebiofilms withfluorescein in conjunction withfluorescence imaging suggested that thevoids werefluid-filled. Thismoreopen architecture isconsistent withrecent models of biofilm structure fromother habitats andhas important implications forthedelivery of therapeutics todesired targets within theplaque.