What can I do to prevent the gutta-percha from blocking the occlusal openings to other canals?
In a multi-canal tooth you may place a tiny “damp dry” cotton pledget in the canals to be obturated to keep the gutta-percha from blocking the orifices. This will also prevent metal filings from dropping into these canals as you sever the shafts. Another option is to removed the upper 1/3 of gutta-percha on all but the last obturator with a pair of sterile cotton pliers, forceps or scalpel blade. This will reduce the excess accumulation at the orifice.