Occlusion: Intercuspal Position
Biological Variation in Occlusal Relationships:
Anteroposterior Horizontal(Transverse) Vertical Plane
Occlusion
The static and dynamic tooth contact and arrangements of the teeth relationships between the dental arches. Impacts directly on masticatory function including mastication, swallowing, and speech.
Cusp/Fossa Relationships (Angle I): Contact Relationship Variation
1. Cusp to marginal ridges (tooth to 2 teeth) - contacts stratle marginal ridges (PICTURE) 2. Cusp to fossa or single marginal ridge (tooth to tooth)
Intercuspal Position (IP)
A tooth determined position. When arches are closest together, vertical dimension is least.
IDEAL IP:
All posterior teeth to hit simultaneously. Posterior teeth loaded vertically. Anterior teeth in slightly lighter contact.
Posterior Dentition IP
Cusps: Tripodized cusp tip Fossa: Flat fossa
Vertical Plane
Decreased vertical facial height. -Tendency for "deep bite" with increased vertical overlap. -Strong anterior guidance. -Dont see as much teeth, square jaw Increased vertical facial height -Tendency for anterior open bite. -Lack of anterior guidance.
Loading of the Anterior Teeth
Do not want vertical loading because teeth will move Want lighter contact, not heavier loading than posterior. Posterior teeth protect the anterior teeth as tooth position allows vertical loading of posterior teeth but not anterior teeth.
Loading of Posterior Teeth
Loaded vertically. Balanced contact - loads opposite to push each way. Posterior teeth protect anterior teeth.
Tooth to tooth cusp fossa relationship
MLi cusp of Mx 1st molar into central fossa of opposing Mn 1st molar. Mx Li cusps into Distal fossae of opposing Mn teeth. Mn Bu cusps into Mesial fossae of opposing Mx teeth.
Posterior Dentition IP: Centric Cusps (Centric stops)
Maxillary teeth: Lingual Mn teeth: Buccal (root centered on long axis) Morphology: Broader, bulkier Function: To grind and masticate food
Horizontal (Transverse)
Mn arch outside Mx arch. (Crossbite) Centric cusps are reversed. (Mx Buccal, Mn Lingual) Unilateral or bilateral.
Posterior Dentition IP: Non-centric cusps
Mx teeth: Buccal Mn teeth: Lingual Morphology: Sharper, longer Function: To tear food, keep soft tissues off biting surface
Anteroposterior
Of upper and lower. Angle class I - ideal relationship. Look at: 1. relationship of 1st molars(opposes Bu groove) 2. Relationship of canine Angle class II - MBu cusp ahead a whole cusp, anterior teeth sit way out. Angle class III - Full cusp distal relative to class I.
Anterior Dentition: Vertical overlap
Overbite. Incisors together. (Patients tend to mix up overbite and overjet)
Anterior Dentition: Horizontal overlap
Overjet. Upper teeth are outside of lower teeth.
Centric Occlusion (CO)
Synonym of Intercuspal Position. "Centered occlusal position" (but isn't always centered to cranium)