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Extent of the odontoblastic process. Analysis by SEM and confocal microscopy.

BACKGROUND
Towards the middle of the eighteenth century, Tomes described membranous structures of cellular origin inside the dentinal tubules. Subsequent studies of the terminal segment of the odontoblasts have been controversial. According to Fusayama, this cellular process reaches as far as the junction; others, including Brännström, affirm that this process is present only in the inner third of the dentin.


AIMS
The aim of the present study was to verify the exact length of the odontoblastic terminal segment with the aid of advanced confocal microscopy (CLSM) and high resolution field-emission scanning electron microscopy (FE-SEM).


METHODS
Premolars due for extraction for orthodontic reasons, were used for this study; vestibular class V cavities about 2 mm in diameter and 3 mm in depth prepared and subsequently filled with IRM (Caulk Dentsply). All teeth were extracted after four weeks fixed and prepared for examination under SEM and CLSM.


RESULTS
CLSM revealed cylindrical structures inside the tubules even in the absence of odontoblasts. SEM evidenced the presence tubular structures only in the inner third of the dentin (towards the pulp).


CONCLUSIONS
Structures previously described as cellular processes can be identified as the lamina limitans of the peritubular dentin.