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Incremental lines in human acellular tooth cementum - New insights by SEM analysis
Christopher Hinrichs1, Nicole Nicklisch1, Cezarina C Mardare2
1Danube Private University, Steiner Landstrasse 124, 3500 Krems-Stein, Austria.
Summary
Scanning electron microscopy successfully visualized incremental lines in acellular extrinsic fibre cementum (AEFC). These lines, formed by alternating fiber-rich and fiber-poor layers, reveal crucial structural details of tooth cementum formation.
Area of Science:
- Dental Anatomy
- Histology
- Biomaterials Science
Background:
- Tooth cementum, vital for root dentine, is continuously formed throughout life.
- Acellular extrinsic fibre cementum (AEFC) covers the root's cervical and middle thirds.
- AEFC exhibits lamellar patterns known as incremental lines, with a suspected seasonal rhythm in humans.
Purpose of the Study:
- To detect incremental lines in AEFC using scanning electron microscopy (SEM).
- To analyze the underlying structure of these incremental lines.
- To overcome previous limitations in visualizing AEFC incremental lines with SEM.
Main Methods:
- Investigation of non-embedded and resin-embedded transverse and longitudinal tooth sections.
- Utilized SEM for high-resolution imaging without pre-treatment like etching or coating.
- Examined sections from three single-rooted teeth from different patients.
Main Results:
- Incremental lines, appearing as lamellar structures, were detected in both transverse and longitudinal sections.
- The lamellar pattern consists of alternating broad, fiber-rich layers and narrow, fiber-poor layers.
- Collagen fiber orientation varied between layers, shifting from transverse to radial directions.
Conclusions:
- SEM enables the detection and structural analysis of incremental lines in AEFC.
- Fiber density and orientation are key factors in incremental line formation.
- Functional aspects appear to be critically important in cementum incremental line development.
