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UKCD HIsto Cem/Bone
learning objective answers for cementum and alveolar bone
Question | Answer |
---|---|
What initiates cementum formation? | Breakdown of the epithelial root sheath so that cells of the dental sac touch exposed dentin. |
What cells secrete cemntoid? | Cementoblasts (differentiated cells of the dental sac). |
What happens to these cemntoid-secreting cells when the matrix mineralizes? | Some become trapped within the mineralized cementoid (cementum) as cementocytes. |
Where is the cementum layer thinnest? | At the cervix and upper 1/3 (cervical portion) of the root. |
What is primary cementum and where is it located? | - Primary cementum is acellular and covers cervical 1/3 of the root. |
What is secondary cementum? | Cementum formed after the tooth reaches functional occlusion. This cementum contains trapped cementocytes and is referred to as cellular cementum. |
What inserts into the cementum layer from the PDL aspect? | Sharpey’s fibers (groups of collagen fibers). |
What is an arrest line? | A highly mineralized layer of cementum marking a pause in the depoistion of cementum. They are smooth in appearance. |
What is a reversal line? | A line indicating where the resorption of cementum stopped prior to deposition of new cementum. This is more common in bone. Reversal lines are scalloped (irregular) in appearance. |
What is the function of a cementoclast? | To resorb cementum. |
Why ar reversal lines scalloped but arrest lines smooth? | Reversal lines indicate the activity of individual cementoclasts (irregular) whereas arrest lines indicate a pause in the wave-like, regular deposition of cementum. |
What is a cementicle? | Mineralized bodies within the periodontal ligament – mineralized remnants of the epithelial root sheath (epithelial rests). |
Name three patterns exhibited at the cementumenamel junction (CEJ) and their frequency of occurance. | Touching (25%), gapping (10%) and overlapping (65%) |
What is the clinical implication of these configurations found at the CEJ? | Gapping laves dentin exposed and can lead to radicular dentin caries. |
What is alveolar bone compared to basal bone? | Alveolar bone is the region of the jaw in which the bony tooth sockets are located. Basal bone is more compact and forms the structural portion of each jaw. |
How is alveolar bone composed? | The inner and outer cortical plates of alveolar bone are compact bone. The cortical plate of the tooth socket is cribriform and is composed of and outer layer of bundle bone overlying an inner layer of compact, lamellar bone. |
The inner cortical plate of alveolar bone is referred to as being cribriform. What does this mean and what is its function? | Cribriform refers to having openings or pores within it. These openings allow nerves and blood vessels to gain access to the periodontal ligament from the alveolar bone plates |
What is the interdental septum? | The plates of cribriform bone between two adjacent teeth. |
How does the interdental septum differ from the interradicular septum? | The interdental septum separates individual teeth whereas the interradicular septum separates roots of the same (multi-rooted) tooth. |
How does the bone of the bony tooth socket respond to physical pressure? | Pressure against bone of the tooth socket causes resorption, tension on bone (taut PDL) causes deposition. |
What specific field of dentistry uses the ability of tooth sockets to resorb as an axiom? | Orthodontics. |