dear chakrapani sorry for our delayed answer promising u that our site services including fast replying to all requests won't be delayed any more ,
for remaining root if they can't be used to retain or support an over denture , it's prefered to extract them even if asypyomatic as act as contineous source of irritation & infection , u can take ur 1ry impression several days after extraction, but ur 2ry must be after complete healing at least 3 weeks to one month later & if these roots are embedded ones that were fractured during extraction , denture insertion & the forces will be loaded over bone during function will induce these embedded remnants to erupt so once u can palpate them , incise & remove otherwise will act as pressure area under the denture .
For bony exostoses, if they are excessive to extent that they produce undercuts can't be relived or bypassed & will jeopardize the denture bearing area , remove them surgically in a step that's known as pre-prosthetic surgery , for more data , the following link can help u
http://www.prosth.net/forum_thread_105_Pre-Prosthetic-Surgery.html
For ur 65y pt , if other features of the previous denture are satisfactory , reline it , no problem , if teeth wear is severe that jeopardize ur VDO & will put ur pt in the category of low vertical dimension drawbacks , new vertical dimension should be considred .
Hope I was helpful to u , u're welcome anytime if u still need any more clarifications ,
thx for sharing us that site