Stereological determination of the volume of the rat hemimandible tissues

Rodent incisors are useful models to study the development and behavior of dental and periodontal tissues. Some studies require three-dimensional reco nstructions of the tooth but none of the described methods yield actual vol umetric data. Unlike the rat lower incisors the hemimandible can be easily isolated and its volume was determined by Cavalieri's geometrical principle . This method associated with point-counting volumetry was used to calculat e the volume of the structures found in that bone mainly those related to t he lower incisor. For 172 g male rats the mean volume of the hemimandible w as 182.7 mm(3), statistically not different from 184.9 mm(3) the mean volum e of the same hemimandibles determined by Archimedes' principle. The coeffi cients of error (CE) of Cavalieri's estimates for the hemimandible, incisor as a whole (the tooth itself, odontogenic region and periodontium) and bon e tissue were less than 0.04. For the incisor individual tissues the CEs we re usually above 0.05, however their calculated volumes are probably not di fferent from the actual ones. The data for incisors and their periodontal t issues and for bone, because of continuous growth of these structures, are meaningful only for rats of the same gender, strain and weight range. Anat Rec 263:255-259, 2001. (C) 2001 Wiley-Liss, Inc.