Large tooth model  portrays a molar  w/three  root  from  the  upper  jaw.  About  15  times normal size for ease of study. Divide the molar longitudinally to  expose  its  intenrior  from crown to root. Next remove the pulp from one half of the tooth. Then extract a section of the crown,  from  the  other  half. Finally,  Insert  any  of  four additional   interchageable sections   exhibiting   abvancing stages of caries. The tooth pivots on a plastic base. Size:18X18X40CM