Effects of thyro-parathyroidectomy and parathyroidectomy upon dentinogenesis: Part II: Electron microscopy

Area of Science:

• Biomineralization
• Cell Biology
• Endocrinology

Background:

• Previous studies indicated alterations in dentinogenesis.
• Ultrastructural analysis is crucial for detailed characterization of cellular and matrix changes.

Purpose of the Study:

• To ultrastructurally characterize symmetrical cross-banded structures in the dentin of rats with altered parathyroid function.
• To investigate the relationship between these structures, dentinogenesis, and parathyroid hormone levels.

Main Methods:

• Ultrastructural examination of predentin and dentin in thyro-parathyroidectomized (TPTX) and parathyroidectomized (PTX) rats.
• Comparison of findings with normal and previously studied pathologic rat incisors.

Main Results:

• Symmetrical cross-banded structures were observed in the predentin and dentin of TPTX and PTX rats.
• Differences in the distribution and amount of these structures were noted between TPTX and PTX groups as dentinogenesis progressed.
• These structures correlate with previously described symmetrical Segments of Longitudinal Striation (SLS).

Conclusions:

• The presence of symmetrical banded structures indicates that odontoblasts are sensitive to parathyroid hormone deficiency and/or hypocalcemia.
• This sensitivity occurs at a specific stage of odontoblast maturation during incisor development.