Formation of Periodontal Tissues around Subcutaneously Transplanted Hamster Molars

Abstract

Thepurpose ofthepresent investigation istodetermine whether thedeveloping tooth hasaformative influence uponthetissues whichsurround itand,ifso,howfarthe influence extends andhowlongitlasts. Invitro microdissection studies haveindicated thattheenamel organofthedeveloping tooth exerts avariety ofinfluences inwardly uponthemesenchyme within itthedental papilla. Itsepithelium isbelieved toinfluencetheinitial condensation ofmesenchyme toformthedental papilla, thedifferentiationofodontoblasts, andthegeneral shaping ofthetooth crownandroots. However, thepossibility thattheenamel organmightalsoexert influence outwardly uponthe surrounding mesenchyme ofthedental sachasnotbeenexperimentally tested. The transformation ofthedental sacintothedefinitive periodontium, consisting ofthe periodontal ligament andalveolar bone, proceeds simultaneously withthegrowth and development oftheroots. Thissuggests somekindofco-ordinating influence between periodontium development andthedevelopment ofthetooth proper. Inorder totest whether suchaninfluence exists, theenamel organ anddental papilla ofthedeveloping hamster molar weredissected fromtheir dental sacbefore rootformation, transplanted intoconnective tissue whichordinarily doesnotformperiodontium, andallowed to develop. Itwasfoundthatallhealthy specimens recovered after 4weeksinthehost hadorganized periodontium around themselves; this suggests theexistence ofanorganizing influence emanating fromthedeveloping root. Theextent oftheinfluence wasfoundtobelimited totheperiodontal ligament anda relatively thinshell of alveolar bonearound theroots andboneinthespace between theroots. Cells forming bonearound transplants seemtohavebeensupplied bythehost. The stimulus forconversion ofhostcells intoosteoblasts probably camefromtheenamel organanditsderivative-Hertwig's epithelial rootsheath. Thisstimulus wasfound to