Fourth Stage Tooth Movement Lecture Notes

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What consequences can arise if orthodontic forces are grossly excessive?

Resorption of root surfaces, non-vitality, ankylosis of the tooth

What is the term used to describe bone resorption that occurs in the adjacent marrow spaces under hyalinized areas?

Undermining indirect or rearward resorption

What happens to the periodontal ligament on the tension side when it gets overstretched?

Tearing of blood vessels and ischemia

Why does the tooth become loosened in its socket when there is an increased osteoclastic activity?

Due to tearing of blood vessels and ischemia Signup and view all the answers

What are the possible consequences of applying very heavy orthodontic forces?

Pain, loosening of the tooth, healing by ankylosis Signup and view all the answers

What is secondary bone remodeling?

Addition of bone to endosteal surface under pressure areas and resorption under tension areas Signup and view all the answers

What is the role of the periodontal ligament in tooth movement?

The periodontal ligament forms a dense network of capillaries or plexus around the tooth, occupying up to half of the periodontal space, facilitating tooth movement. Signup and view all the answers

Describe the three phases of physiological tooth movement.

The three phases are: 1) Pre-eruptive tooth movement, 2) Eruptive tooth movement, and 3) Post-eruptive tooth movement. Signup and view all the answers

What is the primary force behind eruptive tooth movement?

Eruptive tooth movement is primarily brought about by the periodontal ligament traction. Signup and view all the answers

When does eruptive tooth movement typically begin?

Eruptive tooth movement generally begins when about 2/3 portion of the root is formed. Signup and view all the answers

What is the purpose of post-eruptive tooth movement?

Post-eruptive tooth movement helps maintain the teeth's position in occlusion until jaw growth is completed. Signup and view all the answers

Classify the different types of tooth movements mentioned in the text.

The text mentions three types of tooth movements: physiological, pathological, and orthodontic. Signup and view all the answers

What is the optimal orthodontic force required for different types of tooth movement?

The optimal force for tooth movement varies depending on the type of movement:- Tipping: 35-60 grams- Bodily: 70-120 grams - Root uprighting: 50-100 grams- Rotation: 35-60 grams- Extrusion: 35-60 grams- Intrusion: 10-20 grams Signup and view all the answers

What happens on the pressure side of the periodontal ligament when heavy orthodontic forces are applied?

When heavy forces are applied, the periodontal ligament on the pressure side becomes extremely compressed and crushed, possibly causing contact between the tooth and the alveolar bone. This leads to occlusion of blood vessels in that area, depriving the periodontal ligament of nutrients and causing regressive changes like hyalinization. Due to the ischemia and hyalinization, there is no recruitment of osteoclasts, and no resorption occurs on the periosteal surface of the socket, preventing the tooth from moving. Signup and view all the answers

Why is it not true that heavier orthodontic forces can bring about faster tooth movement?

Although it might seem logical that heavier forces could lead to faster tooth movement, this is not the case. Heavy forces can cause compression and crushing of the periodontal ligament on the pressure side, leading to occlusion of blood vessels, ischemia, and hyalinization. This prevents the recruitment of osteoclasts and resorption on the periosteal surface, ultimately preventing the tooth from moving for a period of time. Signup and view all the answers

What is the relationship between the area of the periodontal ligament (PDL) and the optimal orthodontic force?

The optimal orthodontic force depends on the area of the PDL that the applied force is spread across. For example, a low force should be used to intrude a tooth, where the force is concentrated in a small area at the apex. A higher force can be used to bodily move teeth, where the force is spread across the whole side of a tooth root. Signup and view all the answers

What is the main consequence of the regressive changes in the periodontal ligament caused by heavy orthodontic forces?

The main consequence of the regressive changes, such as hyalinization, caused by heavy orthodontic forces is that there is no recruitment of osteoclasts on the pressure side of the periodontal ligament. This leads to no resorption occurring on the periosteal surface of the socket, preventing the tooth from moving for a period of time. Signup and view all the answers

How does the optimal orthodontic force differ for intrusion compared to bodily tooth movement?

For intrusion, a low force of 10-20 grams should be used, as the force is concentrated in a small area at the tooth apex. In contrast, for bodily tooth movement, a higher force of 70-120 grams can be used, as the force is spread across the whole side of the tooth root. Signup and view all the answers

What is the main problem mentioned in the text?

The main problem mentioned in the text is to find something that primarily works locally. Signup and view all the answers

What are the two types of drugs known to depress the response to orthodontic force?

The two types of drugs known to depress the response to orthodontic force are prostaglandin inhibitors for pain control and bisphosphonates used in the treatment of osteoporosis. Signup and view all the answers

What is the relationship between local injury (cortectomy) and orthodontic tooth movement?

Orthodontic tooth movement and bone remodeling is accelerated during wound healing (via the regional acceleratory phenomenon described by Frost) after local injury to the alveolar process. Signup and view all the answers

What other classes of drugs can decrease prostaglandin levels and slow the response to orthodontic force?

Other classes of drugs that can decrease prostaglandin levels and slow the response to orthodontic force include tricyclic antidepressants, antiarrhythmic agents, antimalarial drugs, anticonvulsant drugs, and doxycycline. Signup and view all the answers

What is the significance of the regional acceleratory phenomenon described by Frost in relation to orthodontic tooth movement?

The regional acceleratory phenomenon described by Frost is what accelerates orthodontic tooth movement and bone remodeling during wound healing after local injury to the alveolar process. Signup and view all the answers

What is the significance of the finding that drugs that inhibit tooth movement are frequently encountered, although not yet prescribed for their tooth-stabilizing effect?

The finding that drugs that inhibit tooth movement are frequently encountered, although not yet prescribed for their tooth-stabilizing effect, suggests that there is potential to utilize these drugs to control tooth movement in orthodontic treatment. Signup and view all the answers

What is the primary role of osteoblasts in orthodontic tooth movement?

Osteoblasts release factors that recruit and activate osteoclasts, which are responsible for bone resorption during orthodontic tooth movement. Signup and view all the answers

How do osteoblasts facilitate access for osteoclasts during orthodontic tooth movement?

Osteoblasts lining the bone represent a physical barrier to resorption, and their retraction provides access for bone-resorbing osteoclasts. Signup and view all the answers

What is another barrier that osteoblasts remove to facilitate osteoclast activity?

Osteoblasts remove the unmineralized collagen or osteoid that lines the bone surface, which acts as a further physical barrier to osteoclasts. Signup and view all the answers

Name one of the theories mentioned in the text that attempts to explain the mechanism of orthodontic tooth movement.

Any one of the following: Pressure tension theory by Schwartz, Blood flow theory by Bien, Bone bending/piezoelectricity by Picton, Cochran and Grimm, or Mechanochemical theory by Justus and Luft. Signup and view all the answers

What is the general consensus about the cellular reactions that result in bone resorption and deposition during orthodontic tooth movement?

There is a consensus about the general nature of the cellular reactions involving osteoblastic and osteoclastic activities that lead to bone resorption and deposition during orthodontic tooth movement. Signup and view all the answers

What is the relationship between osteoclasts and osteoblasts in the context of orthodontic tooth movement?

Osteoclasts show little bone-resorbing activity in isolation, and they appear to be recruited and activated by the presence of osteoblasts. Signup and view all the answers