the treatment of in completely formed pulpless teeth has presented considrable problems. these teeth have wide open apexes and the walls of the root canal diverge toward the apical tissues. mechanical preparation cannot be done in the normal manner beacause of the large initial size and the taper of apical part of the canal , a mechanical stop cannot be produced at the apex of the canal and , therefore , control of root filling materials is difficalt. friend has shown that the canals are usually elliptic in section , the larger diameter is the bucco lingual .there fore a normal intraoral radiograph cannot show whether the canal is obliterated with root filling material . pulpless teeth with open apexes some times have been treated by cleaning the canal. overfilling with a standard root filling material , and then per forming in modified root resection. this stops root formation , and the result is a short weak tooth with a doubtful prognosis.