The teeth were divided into 5 groups of 10 specimens each , according to the gutta-percha removal techniques : group 1 : GPX ( 21-mm-long teeth ) ; group 2 : GPX and xylol as solvent ( 21-mm-long teeth ) ; group 3 : GPX ( 25-mm-long teeth ) ; group 4 : GPX and xylol as solvent ( 25-mm-long teeth ) ; and group 5 : hand files and xylol as solvent .
