PARATHYROID

• there are 20 deciduous teeth and 28 to 32 permanent teeth
• deposition of salts in early forming teeth are affected by

  i) calcium and phosphate in diet

  ii) vitamin d

  iii) rate of PTH secretion
• PTH is synthesized in the ribosomes
• parathyroid tumors are more common in women than men
• the molecular weight of PTH is 9500
• teeth are provided with projections and facets to allow them to interdigitate
• front teeth have an occlusive force of 50 to 100 pounds

  jaw teeth have an occlusive force of 150 to 200 pounds
• when half of the parathyroid glands are removed, there are no major physiologic abnormalities
• enamel is composed of dense hydroxyapatite crystals and ions embedded in a meshwork of proteins that are similar to keratin
• hypercalcemia results to a depression of the central and peripheral nervous systems
• the crown is the portion of the tooth that protrudes out from the gum
• an important diagnostic finding for osteitis fibrosa cystica in hyperthyroidism is a high level of plasma alkaline phosphatase
• once the tooth has erupted, enamel can no longer be formed
• lactation will cause a decrease in calcium
• rate of development and eruption of teeth are accelerated by growth and thyroid hormones
• osteitis fibrosa cystica is secondary to hyperparathyroidism
• osteoclastic activity is enhanced in hyperparathyroidism with prolonged PTH excess
• magnesium and hydrogen ions have a greater absorption along with PTH secretion
• secondary hyperparathyroidism occurs as a compensation for hypocalcemia
• fluorine does not make enamel harder but makes it less soluble
• PTH is synthesized first as a preprohormone
• pregnant women's parathyroid glands will undergo hypertrophy due to calcium depletion
• the neck is the collar between the crown and root where the tooth is surrounded by gum
• hyperparathyroidism is associated with extensive decalcification and large cystic areas of bone that are filled with osteoclast
• renal calculi formation is greater in alkaline urine
• the main body of the tooth is composed of dentin
• prohormone PTH is composed of 90 amino acids
• cementum becomes thicker and stronger due to an increase in age and exposure to excessive strain
• when there is hypercalcemia in hyperthyroidism, there is a depressed relaxation of the heart during diastole
• cementum increases in thickness and strength with age, causing the teeth to become firmly seated in the jaws in adulthood
• dentin contains odontoblast cells
• constipation is a cause of hypercalcemia in hyperparathyroidism
• 9.4 mg/dl is the normal calcium level in blood
• vitamin D deficiency and chronic renal diseases can cause secondary hyperparathyroidism
• dentin does not stop growing and the pulp cavity decreases in size
• the collagen fibers in dentin make it tough and resistant to tensional forces.
• the calcium salts in dentin make it resistant to compressional forces
• the cells lining the surface of the pulp cavity are the odontoblasts that lay down dentin eventually making the pulp cavity smaller
• a calcium level of 6 mg/dl is a consequence of tetany
• enamel is formed by ameloblast cells