Periodontal Physiology and concepts of occlusal load

Question 1

The PDL links the tooth to the alveolar bone by what joint?

Answer 1

Gomphosis

Question 2

What is the definition of the biologic width?

Answer 2

2-3mm from the alveolar crest to the tip of the junctional epithelium. Important for tooth function in heath

Question 3

What is the importance of the gomphosis joint?

Answer 3

To distribute the pressure of the occlusion onto the bone and PDL

Question 4

What is the importance of the gomphosis joint?

Answer 4

To distribute the pressure of the occlusion onto the bone and PDL

Question 5

What is the name of the joint when the teeth are directly connected to bone with no PDL?

Answer 5

Ankylosis

Question 6

What are the 3 main roles of PDL?

Answer 6

1) Absorption of occlusal forces
2) Mechanoreceptors, pain fibres and proprioceptors
3) PDL remodelling

Question 7

What is the impact of occlusal load on the PDL?

Answer 7

• PDL maintenance width is done by regular mechanical stimulation
• In hypofunction, there is thinning of the PDL
• In hyperfunction, the PDL width increases

Question 8

Explain why hypofunction of the PDL leads to narrowing

Answer 8

Reduced loading means the PDL gets narrower.
Results in bone formation.
PDL gets smaller
Less load leads to change in collagen fibres, the collagen gets more disorganised, lower intensity

Thinner PDL = more bone

Question 9

Explain how hyperfunction affects the PDL

Answer 9

Excess pressure on the tooth
Pressure-tensile forces uses as basis on orthodontics
Pressure causes osteoclasts to eat the bone.
Osteoblasts produce more bone where there is tension.
PDL width is maintained.

Question 10

When a tooth tilts, there is one side of pressure and the other of tension, what happens on each side?

Answer 10

Pressure = loss of fibre orientation, osteoclasts bone resorption, localised areas of pressure necrosis

Tension = stretching of fibres, bone formation

Question 11

What happens with multi-directional forces?

Answer 11

1) Get an abnormal occlusion function (excessive loading, periodontal hyperfunction), likely due to parafunction

2) Absence of neuromuscular control of mastication

3) Abnormal occlusal support - loss of bone can occur if the patient has periodontitis

Question 12

What is the effect of occlusal load on the PDL?

Answer 12

The PDL remodells and shows adaptive changes in response to increased loading.
These changes are reversible following removal of these forces.
This is clinically associated with increased mobility and widening of PDL radiographically.

Question 13

What causes occlusal trauma?

Answer 13

Abnormal occlusal function
Absence of neuromuscular control of mastication
Abnormal occlusal support

Question 14

What is an occlusal disharmonies?

Answer 14

1) Premature contacts when going into ICP - leads to a tooth with extreme loading on it

2) Irregular contacts during protrusive movements

3) Irregular contacts during lateral excursion

Question 15

What is parafunction?

Answer 15

Multidirectional forces can also be due to parafunction.
These exert an extreme pressure on the tooth leading to a change in PDL physiology.

Question 16

What does periodontal disease do to the surface area of the pdl?

Answer 16

Decreases the SA.
Less PDL means a normal masticatory force can produce abnormal occlusal load.
Resultant movement of tooth.

Question 17

What is the difference between primary and secondary occlusal trauma?

Answer 17

Primary = excessive occlusal load on periodontally healthy teeth.

Secondary = excessive occlusal loads on periodontally diseased teeth

Question 18

How is occlusal trauma related to periodontitis?

Answer 18

Occlusal loading causes increased tooth mobility.
Occlusal loading does not cause attachment loss.
Occlusal loading does not cause periodontal disease.
In the presence of destructive periodontitis, excess occlusal loading may enhance periodontal breakdown.