Pulp Calcification; SEM Analysis on a Nanoscale Level

Introduction: The mechanism of calcification within the human dental pulp tissue is not well understood. An organic matrix was found to support calcium phosphate crystal nucleationand growth and in previous dental hard tissue studies. This study assumes that organic matrix may also play a key role in the pulp calcification phenomenon.

Objectives: The study aim was to morphologically analyze the outer and inner surfaces of pulp calcifications on a micro and nanoscale levels with the use of a Scanning Electron Microscope (SEM) and correlate it with the organic template guided biomineralization theory.

Materials and methods: 50 extracted human teeth were collected and x-rayed. The x-ray film was analyzed and teeth that were suspected to have pulp calcification were split. All pulp calcifications were analyzed by a light microscope and SEM with Energy dispersive X-ray analysis (EDX) capability.

Results: Twelve out of the 50 examined teeth revealed pulp calcifications with two major consistencies (hard and soft). Hard samples resembled in part nontubular dentin structure with partly disorganized and partly organized calcified structure. A few hollow tubules that resembled dentinal tubules were found in some samples. Soft samples analysis revealed nano size ribbon like organic structures that were covered by calcium phosphate spheres of various dimensions in the nanometer range. Calcified nanosferes with diameter of ~20nm were observed in some samples. On a lower magnification, calcium phosphate clusters appeared organized in an elongated microstructure fashion along the tooth long axis.

Conclusion: Within its limitations, this study supports the hypothesis of organic compound initiation and guidance of crystal growth and calcification of dental pulp stone. Organic fiber-like structures were observed at what seamed to be the initial stage of pulp calcification. The organic fibers function as a site for calcium phosphate nanocrystals initial nucleation, development and growth.