[The anatomical characteristics of the root furcations in the molar teeth]

The aim of the present study has been to realize a morphometrical and morphological study on the anatomical characteristics of molar teeth root furcations. Two hundred ninety four molars (147 upper and 147 lower teeth), after extraction and elimination of periodontal ligament residuals by trypsin, have been morphometrically evaluated recording the principal anatomical characters of the furcal and radicular region (root and radicular trunk lengths, mesio-distal and vestibulo-palatal diameters at the cementum-enamel junction, inter-radicular angle width and furcal area extension). By the Pearson's correlation test data such obtained were analyzed to verify the existence of statistically significant correlations among the above mentioned anatomical characteristics. Thirty teeth, selected among the most representatives of the whole sample for their anatomical characters, have been morphologically evaluated: 10 by stereo-microscopical examination, 10 by the observation of non-demineralized histological sections and 10 by scanning electron microscopical examination. Results of the morphometrical evaluation showed that from first to second molar the radicular angle, root length and furcal area width undergo a reduction; differently radicular trunk increases his length. On the basis of this results the Authors try to explain data from recent clinical research testifying that second upper molar is the most frequently extracted tooth. In fact a long radicular trunk is associated with a more apical placement of the furcation entrance and this situation, in conjunction with a narrow inter-radicular angle, can obstruct the insertion of therapeutical instruments, justifying the bad prognosis of the second upper molar involved by periodontal disease. The statistical analysis of anatomical data showed a significant correlation (r = -0.46) among radicular trunk length and inter-radicular angle width (in upper first molars; reverse correlation), root length and inter-radicular angle width (r = 0.51) (lower first molars), vestibular-buccal diameter at the cementum-enamel junction and width of mesial and distal furcal angles (r = 0.43) (upper second molars), the extension of furcal area and the wideness of inter-radicular angle (r = 0.89/0.43). These data are in accord with those from other Authors. Morphological analysis showed the high structural complexity of furcal area in molar teeth with the common observation of cemental crests and pulpal accessory canals orifices; these structures can offer a good receptacle to the subgingival dental plaque and can cause difficulties in debridement and therapeutical treatment of the molar furcal region involved by periodontal disease.(ABSTRACT TRUNCATED AT 400 WORDS)