16. Border positions of the mandible. Types of occlusions. Angle’s perfect occlusion.

refer back to essay 15 till retrusion

whats in it

all jaw positions

• normal occlusion

• ideal oclusion

• border occlusions: = protrusive, lateral occlusion, balanced oclclusion, canine guidance, group function, angle’s 3 classes

normal occl

Normal Occlusion

- -

-

Normal occlusion implies a situation commonly found in the absence of disease. It should include not only a range of anatomically acceptable values but also physiological adaptability.

It is always a range never a point, as it varies with each person differently

Ideal Occlusion:

The concept of ideal or optimal occlusion refers both to an aesthetic and physiologic ideal. It includes functional harmony, stability of masticatory system and neuromuscular harmony.

1. Protrusive occlusion

• Occlusion of the teeth when the mandible is protruded (pushed forward)

• -  The frontal teeth have an edge-to-edge relationship, and the posterior teeth have a

  disocclusion

lateral occlusion

• working side and on working side

• working = occlusal contacts of teeth on the side towards which the mandible has moved

• working side is more towards cheek and the condyle pivots in the socket, and it is better supported

• non working = balancing (more towards tongue) - more prone to injury and NO contact usually

balanced occlusion

• bilateral simultaneous ant and post occlusal contact of teeth in BOTH centric AND eccentric relations

• eccentric = protusive and lateral in both working and balancing side

• optimal for dneture stability

canine guidance

• mutually protected articulation

• vertical and horizontal overlap of canines, disengage posterior teeth during excursive movements

• aka canine protected function

group function

• max and mand arches having multiple contacts relations in lateral movements on working side w simulatenous contact which distrubytes occlusal forces

ANGLES CLASSIFICATION OF OCCLUSION

class 1 (neutroclossion)

• normal ant/post relation of jaws

• can be seen by correct alighment of max and mand molars aka MB cusp fits into MB groove OF FIRST max molar and mand molar

• however there is crowding elsewhere - can be caused by dysplasia or small arch

class 2 - disto

• mand arch = post to max arch

• can be on one lateral side or both (but generally when mand 1st moalr is behind max 1st molar)

• causes deep bite

class 3 - mesio

• mand arch is ant to max arch

• can be lateral or both sides

• in conclusion 1st max molar = in front of 1st mand molar

• underbite

class 4 (half mesio half disto)

• but this class is no longer used

• left side sits ant and right side is post