BIOLOGY OF TOOTH MOVEMENT

MOST ACCEPTED THEORY OF ORTHODONTIC TOOTH MOVEMENT

• PRESSURE TENSION THEORY

• BLOOD FLOW THEORY

• BONE BENDING THEORY

• PERIODONTAL TRACTION THEORY

CELLS INVOLVED IN BONE RESORPTION

• OSTEOBLAST

• OSTEOCYTE

• OSTEOCLAST

• NONE OF THE ABOVE

OSTEOBLAST ARE FOUND MORE IN

• TENSION SIDE

• COMPRESSION SIDE

• BOTH SIDES EQUALLY

• NOT FOUND

HEAVY FORCES ON PERIODONTAL LIGAMENT CAUSE

• HYALINIZATION

• OSTEOCLASTIC ACTIVITY AROUND TOOTH

• OSTEOBLASTIC ACTIVITY AROUND TOOTH

• CRESTAL BONE RESORPTION

OPTIMUM ORTHODONTIC FORCE IS

• 20-26 g/cm²

• 40-50 g/cm²

• 8-10 g/cm²

• 60-70 g/cm²

FRONTAL OR DIRECT RESORPTION OCCURS

• AS A RESULT OF MILD ORTHODONTIC FORCE

• OCCURS ON THE PRESSURE SIDE OF TOOTH MOVEMENT

• DOES NOT CAUSE RESORPTION OF ROOT

• ALL OF THE ABOVE

WHEN A FORCE IS APPLIED TO A TOOTH

• AREA OF PRESSURE ARE CREATED

• AREA OF TENSION ARE CREATED

• BONE RESORTION AND DEPOSITION OCCURS

• ALL OF THE ABOVE

UNDERMINING OR REARWARD RESORPTION OCCURS AS A RESULT OF

• CHANGES FOLLOWING MILD FORCES

• CHANGES FOLLOWING MODERATE FORCES

• CHANGES FOLLOWING EXTREME FORCES

• NONE OF THE ABOVE

DURATION OF LAG PHASE

• 12 DAYS

• 2 TO 10 DAYS

• 30 DAYS

• 21 DAYS

MINIMUM DURATION OF FORCE REQUIRED TO BRING ABOUT TOOTH MOVEMENT

• 10 MIN

• 10 HOURS

• 6 HOURS

• 1 DAY