Tooth Movement Flashcards
Describe the physiological process of tooth movement when an optimum force is applied to a tooth on
Pressure side
On the pressure side the PDL is compressed. Within seconds the alveolar bone bends and the blood supply is altered. When this pressure is continued over a period of hours there is a chemical reaction within the blood cells which release cykotonis (cytokines) and prostaglandins which in turn signals the need for osteoclasts to migrate to the area.
Within two days osteoclasts migrate to the area and begin bone resorption, which allows the teeth to move.
(1-5 seconds)- PDL compressed, change in cell shape
(Minutes)- O2 levels change, chemicals released e.g. prostaglandins, cytokines
(<4 hours)-osteoclasts differentiate
Describe the physiological process of tooth movement when an optimum force is applied to a tooth on
Tension side
On the tension side the PDL is stretched which again alters the capillary pressure and blood flow, but this time in a different way. This signals the need for osteoblasts and fibroblasts to migrate to the area and lay down osteoid onto the socket wall and new PDL fibres.
Osteoid is premature bone, and has a jelly consistency which is why teeth can feel mobile until they have settled.
The osteoid becomes calcified within six weeks and matures into woven bone. It later remodels to become mature bone.
(1-5 seconds)- PDL stretched, change in cell shape
(Minutes)- O2 levels change, chemicals released e.g. prostaglandins, cytokines
(<4 hours)-osteoblasts differentiate
Describe the physiological process of tooth movement that occurs when the force applied is very high
Pressure side
Pressure side
The PDL is compressed as the tooth moves within the socket, which occludes the capillaries and the blood flow is stopped within a matter of minutes
If this pressure is sustained within hours cell death will occur. This is known as sterile necrosis of hyalinisation. This gives the appearance of glass if it were to be examined under the microscope.
Cell proliferation begins in the surrounding areas of bone which have been compressed but not occluded thus causing undermining resorption of the alveolar bone.
7-10 days later the cell proliferation migrate to the hyalinised area which then leads to tooth movement.
The tooth movement is therefore more painful and delayed.
Describe the physiological process of tooth movement that occurs when the force applied is very high
Tension side
On the tension side the movement is exactly the same as with optimal pressure. However delayed owing to the lack of movement for the first 7-10 days owing to the lack of movement on the pressure side.
On the pressure side the PDL is stretched which again alters the capillary pressure and blood flow, but this time in a different way. This signals the need for osteoblasts and fibroblasts to migrate to the area and lay down osteoid onto the socket wall and new PDL fibers.
Osteoid is premature bone, and has a jelly consistency which is why teeth can feel mobile until they have settled.
The osteoid becomes calcified within six weeks and matures into woven bone. It later remodels to become mature bone.
List 8 reasons for possible reason for slow space closure during this phase in a
patient wearing fixed appliance
• Exesive force used with mechanice
• Not a high enough force being used
• Biology / genetics
• Using hi friction accessories
• Using high friction brackets, like porcilane
• Using hi friction wire, NITI.
• Patient non compliamnce with wearing intra oral elastics
• Pt breaking the appliance
Heavy forces- above capillary blood pressure
(Seconds)- Blood vessels occlude on pressure side, stretch/rupture on tension side
(Minutes)- Blood flow cut to pressure side- HYALINISATION
(3-5 days)- Cells differentiate at distant site- UNDERMINING RESORPTION
(7-14 days)-Tooth movement occurs
Tooth movement forces
Intrusion
10-20g
Tooth movement forces
Extrusion
35-60g
Tooth movement forces
Extrusion
35-60g
Tooth movement forces
Tipping
35-60g
Tooth movement forces
Rotation
35-60g
Tooth movement forces
Root uprighting
50-100g
Tooth movement forces
Bodily
70-120g
Tooth movement forces
Bodily
70-120g
How much space closure in mm do we usually expect per month?
1mm per month
