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

Area of Science:

• Dentistry
• Microscopy
• Histology

Background:

• Historical descriptions of cellular structures within dentinal tubules date back to the eighteenth century.
• The exact extent of the odontoblast's terminal segment within dentinal tubules has been a subject of ongoing debate among researchers.
• Conflicting theories proposed by Fusayama and Brännström highlight the controversy surrounding odontoblast process length.

Purpose of the Study:

• To precisely determine the length of the odontoblastic terminal segment using advanced imaging techniques.
• To resolve the long-standing controversy regarding the extent of odontoblast processes in dentinal tubules.

Main Methods:

• Utilized Confocal Laser Scanning Microscopy (CLSM) and Field-Emission Scanning Electron Microscopy (FE-SEM) for high-resolution imaging.
• Prepared Class V cavities in premolars, filled with IRM, and extracted teeth after four weeks for analysis.
• Examined fixed teeth using both CLSM and FE-SEM to visualize dentinal tubule structures.

Main Results:

• CLSM detected cylindrical structures within dentinal tubules, even where odontoblasts were absent.
• FE-SEM revealed tubular structures exclusively in the inner third of the dentin, closer to the pulp.
• These findings indicate the presence of non-cellular tubular structures.

Conclusions:

• The structures observed and previously identified as odontoblast cellular processes are, in fact, the lamina limitans of the peritubular dentin.
• This study clarifies the nature and location of these structures within the dentinal tubules.
• The findings contribute to a better understanding of dentin microstructure and its formation.