Question 1:
Which theory proposed that bone bending was responsible for orthodontic tooth movement?
- A. Piezo-electric forces theory
- B. Pressure-tension hypothesis
- C. Bone bending theory
- D. Mechanotransduction theory
Answer: C. Bone bending theory
Question 2:
What was the main flaw in the pressure-tension hypothesis?
- A. It assumed a closed system for the periodontal ligament.
- B. It did not consider the role of osteoblasts and osteoclasts.
- C. It failed to account for the electrical effects in bone.
- D. It disregarded the influence of cytokines and growth factors.
Answer: A. It assumed a closed system for the periodontal ligament.
Question 3:
Which theory suggested that electrical effects in bone were responsible for orthodontic tooth movement?
- A. Piezo-electric forces theory
- B. Pressure-tension hypothesis
- C. Bone bending theory
- D. Mechanotransduction theory
Answer: A. Piezo-electric forces theory
Question 4:
According to Meikle’s overview, what is the primary mechanism underlying orthodontic tooth movement?
- A. Bone bending
- B. Electrical effects
- C. Mechanotransduction
- D. Pressure-tension
Answer: C. Mechanotransduction
Question 5:
Which of the following theories have been largely discounted by contemporary research?
- A. Bone bending and pressure-tension hypothesis
- B. Piezo-electric forces theory
- C. Mechanotransduction theory
- D. All of the above
Answer: A. Bone bending and pressure-tension hypothesis
Historical Theories of Orthodontic Tooth Movement
Bone Bending Theory:
- Pressure applied to teeth bends the bone.
- This bending triggers bone resorption and deposition, similar to what happens in long bones.
Pressure-Tension Hypothesis:
- Forces applied to teeth are transmitted through the periodontal ligament to the bone.
- Differential pressures in the periodontal ligament cause bone remodeling.
- This theory has been largely dismissed due to the hydrostatic nature of the periodontal ligament.
Piezoelectric Forces Theory:
- Bending bone generates electrical charges (piezoelectric and streaming potentials).
- These electrical charges were thought to be responsible for bone remodeling.
- However, it’s now believed that these electrical effects are a secondary phenomenon and not the primary cause of bone remodeling.
Contemporary Understanding:
- Orthodontic tooth movement is a complex biological process.
- Mechanical forces applied to teeth trigger a series of cellular responses.
- Osteoblasts, the bone-forming cells, play a crucial role in this process.
- They respond to mechanical stimuli by producing signaling molecules (cytokines).
- These signaling molecules influence the behavior of other cells involved in bone remodeling.
Dentowesome 