Podcast
Questions and Answers
What is the primary purpose of the regional acceleratory phenomenon (RAP) in the context of bone healing after an invasive procedure?
What is the primary purpose of the regional acceleratory phenomenon (RAP) in the context of bone healing after an invasive procedure?
- To immediately halt any further bone growth following the procedure.
- To slow down the remodeling process to prevent excessive bone loss.
- To evenly distribute the osteocytes throughout the bone matrix.
- To initiate a localized remodeling process that spreads through the adjacent bone, aiding postoperative healing. (correct)
Hormones and metabolic agents exert the primary control over bone modeling, while mechanical loads play only a minor role.
Hormones and metabolic agents exert the primary control over bone modeling, while mechanical loads play only a minor role.
False (B)
What is the approximate annual remodeling rate of trabecular bone in the vertebral column, as indicated by bone scans with Te-bisphosphate?
What is the approximate annual remodeling rate of trabecular bone in the vertebral column, as indicated by bone scans with Te-bisphosphate?
20% to 30%
The stiffness and strength of bone are related directly to its ___________.
The stiffness and strength of bone are related directly to its ___________.
Match each term with its correct description.
Match each term with its correct description.
What characterizes the metabolic fraction of bone?
What characterizes the metabolic fraction of bone?
Adding new osseous tissue at the endosteal surface significantly enhances overall bone strength.
Adding new osseous tissue at the endosteal surface significantly enhances overall bone strength.
How does the rigidity of a wire (or bone) change when its diameter is doubled?
How does the rigidity of a wire (or bone) change when its diameter is doubled?
Within limits, loss of bone at the ___________ surface has little effect on bone rigidity.
Within limits, loss of bone at the ___________ surface has little effect on bone rigidity.
Why don't patients with osteoporosis experience a significant change in bone diameter?
Why don't patients with osteoporosis experience a significant change in bone diameter?
The alveolar processes in the mandible have a lower remodeling rate compared to the basilar mandible.
The alveolar processes in the mandible have a lower remodeling rate compared to the basilar mandible.
What are the two main categories of signals that control bone modeling and remodeling?
What are the two main categories of signals that control bone modeling and remodeling?
What is the structural optimization achieved through the modification of long bones and the mandible into tubular shapes?
What is the structural optimization achieved through the modification of long bones and the mandible into tubular shapes?
The structural fraction of cortical bone is the relatively ___________ outer portion of the cortex.
The structural fraction of cortical bone is the relatively ___________ outer portion of the cortex.
Local growth factors and prostaglandins can suppress the mechanical control mechanism during wound healing.
Local growth factors and prostaglandins can suppress the mechanical control mechanism during wound healing.
After an osteotomy or placement of an endosseous implant, what processes occur?
After an osteotomy or placement of an endosseous implant, what processes occur?
What is the effect on diaphyseal rigidity when a circumferential lamella is added at the periosteal surface?
What is the effect on diaphyseal rigidity when a circumferential lamella is added at the periosteal surface?
Internal replacement of ___________ cortical bone is a remodeling activity.
Internal replacement of ___________ cortical bone is a remodeling activity.
Aside from localized remodeling, what is another result of traumatic or surgical wounding?
Aside from localized remodeling, what is another result of traumatic or surgical wounding?
Bone remodeling primarily uses mechanical signals, such as functional applied loads, to vary the rate of bone turnover.
Bone remodeling primarily uses mechanical signals, such as functional applied loads, to vary the rate of bone turnover.
Flashcards
Regional Acceleratory Phenomenon (RAP)
Regional Acceleratory Phenomenon (RAP)
Localized bone response to trauma or surgery, involving intense modeling and remodeling.
Callus Formation
Callus Formation
Bone formation and resorption after procedures like osteotomy or implant placement.
Bone Modeling
Bone Modeling
Bone adaptation primarily controlled by functional loads.
Bone Remodeling
Bone Remodeling
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Structural Fraction
Structural Fraction
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Metabolic Fraction
Metabolic Fraction
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Wire Rigidity
Wire Rigidity
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Optimal Bone Design
Optimal Bone Design
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Osteoporosis
Osteoporosis
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Study Notes
- Traumatic or surgical wounding leads to intense, localized bone modeling and remodeling.
- Callus formation and resorption of necrotic osseous margins post-osteotomy or implant placement are modeling processes.
- Internal replacement of devitalized cortical bone around these sites is a remodeling activity.
- The regional acceleratory phenomenon involves a gradient of localized remodeling that spreads through bone near invasive procedures and is important for postoperative healing.
- Orthodontists can leverage postoperative modeling and remodeling to position the maxilla after a LeFort osteotomy or to finish orthodontic alignment after orthognathic surgery.
Control of Bone Modeling and Remodeling
- Modeling is largely under the biomechanical control of functional loads, while hormones have a secondary influence.
- Remodeling responds to metabolic mediators, like PTH and estrogen, by varying bone turnover rate.
- Alveolar processes have a high remodeling rate, similar to trabecular bone, while the basilar mandible does not.
- Bone scans indicate that alveolar bone remodeling occurs at 20% to 30% per year, while most cortical bone turns over at 2% to 10% per year.
- Metabolic mediation of bone turnover ensures a controllable flow of calcium to and from the skeleton.
Bone Structure
- Cortical bone has a structural fraction (stable outer portion) and a metabolic fraction (reactive inner aspect).
- Trabecular bone and the endosteal half of cortices are primary metabolic calcium reserves, forming the metabolic fraction.
- Bone stiffness and strength are directly related to cross-sectional area, similar to orthodontic wires.
- Adding a circumferential lamella at the periosteal surface enhances diaphyseal rigidity because it increases the diameter of the bone.
- Bone stiffness increases as the fourth power of diameter: doubling the diameter of bone or wire increases stiffness 16 times.
- Adding new osseous tissue at the endosteal surface has little effect on overall bone strength.
- Long bones and the mandible are modified tubes optimized for maximal strength with minimal mass.
- Loss of bone at the endosteal surface or within the inner third of the compacta has little effect on bone rigidity.
- The inner cortex can be mobilized for metabolic needs without severely compromising bone strength.
- Osteoporosis patients have bones with normal diameter but thin cortices.
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