Orthodontic Therapy and Tooth Movement

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Questions and Answers

What is the primary mediator of bony response in tooth movement?

Lamina dura

Periodontal ligament (PDL) (correct)

Alveolar bone

Cementum of the root surface

What is the width of the space occupied by the periodontal ligament around the root?

0.1 mm

1 mm

0.5 mm (correct)

2 mm

What is the primary function of the collagenous fibers in the periodontal ligament?

To provide nutrition to the tooth

To transmit forces from the tooth to the bone (correct)

To protect the tooth from infection

To maintain the position of the tooth

What is the function of the fluid-filled chamber in PDL during masticatory function?

To act as a shock absorber and reduce heavy forces Signup and view all the answers

What is the source of multinucleated giant cells in the periodontal ligament?

Both A and B Signup and view all the answers

What is the typical duration of tooth contacts during mastication?

1 second or less Signup and view all the answers

What is the effect of calcitonin on periodontal ligament fibroblasts?

Induction of differentiation Signup and view all the answers

What is the significance of tissue fluids in the periodontal ligament?

They play an important part in making orthodontic movements Signup and view all the answers

What happens to the alveolar bone when a tooth is subjected to heavy loads?

It bends in response to the load Signup and view all the answers

What type of nerve endings are found within the periodontal ligament?

Both proprioceptive and nociceptive nerve endings Signup and view all the answers

What is the effect of wide mouth opening on the distance between mandibular molars?

It decreases by 2-3 mm Signup and view all the answers

What is the effect of mechanical strain on periodontal ligament fibroblasts?

It induces differentiation Signup and view all the answers

What is the result of bone bending in response to normal function?

Generation of piezoelectric currents Signup and view all the answers

What occurs when a force is applied to a crystalline structure such as bone or collagen?

A flow of current is produced Signup and view all the answers

How long does it take for pain to be normally felt after heavy force application?

3-5 seconds Signup and view all the answers

What is made possible by the application of prolonged forces?

Orthodontic tooth movement Signup and view all the answers

Study Notes

Tooth Movement and Periodontal Ligament

Tooth movement occurs due to bone remodeling around the tooth, primarily mediated by the periodontal ligament (PDL)
The PDL occupies a 0.5 mm wide space around the root, comprising parallel collagenous fibers, cellular elements, tissue fluids, and vascular and neural elements

Structure and Components of Periodontal Ligament

The PDL has a network of parallel collagenous fibers inserting into cementum on one side and the lamina dura on the other
Supporting fibers run at an angle, attaching farther apically on the tooth than on the adjacent alveolar bone
The ligament contains cellular elements, including mesenchymal cells, vascular and neural elements, and tissue fluids
The collagen of the ligament is constantly remodeled and renewed during normal function

Response to Orthodontic Therapy

Biological response to orthodontic therapy includes the response of the PDL and growing areas distant from the dentition
Forces applied to teeth can affect bone apposition and resorption at sites distant from the teeth, particularly the sutures of the maxilla and bony surfaces on both sides of the temporomandibular joint

Function and Response of PDL

During masticatory function, teeth and periodontal structures are subjected to intermittent heavy forces
Tooth contacts last for 1 second or less, with forces ranging from 1 or 2 kg to 50 kg depending on the object being chewed
Heavy loads on a tooth cause quick displacement within the PDL, transmitted to the alveolar bone, which bends in response
Bone bending in response to normal function generates piezoelectric currents, stimulating skeletal regeneration and repair
Piezoelectricity is the production of a flow of current when a force is applied to a crystalline structure, such as bone or collagen

Pain Response and Remodeling

Pain is normally felt after 3 to 5 seconds of heavy force application
Prolonged force, even of low magnitude, produces a different physiologic response—remodeling of the adjacent bone
Orthodontic tooth movement is made possible by the application of prolonged forces

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Description

This quiz covers the biological response to orthodontic therapy, including tooth movement, bone remodeling, and the role of the periodontal ligament. It also explores the effects of forces on bone apposition and resorption.