A diagnostic norm is a standard that helps to determine the extent to which a patient deviates from normal. An objective norm is a norm based on a measurement technique that is repeatable, reliable, and based on scientific method. A biometric norm is an objective norm derived from the measurement of a biologic variable in a random sample of persons who are considered normal

The Mean versus the Range of Normal Relationships

Normal Occlusion

Andrew 6 key of normal Occlusion

1. Molar relationship: The mesiobuccal cusp of the upper first molar occludes with the groove between the mesiobuccal and middle buccal cusp of the lower first molar. The distobuccal cusp of the uper first molar contacts the mesiobuccal cusp of the lower second and molar.
2. Crown angulation: All tooth crowns are angulated crowns are mesially (mesiodistal tip)
3. Crown inclination: Inclination refers to the labiolingual or buccolingual inclination of the crowns of the teeth a. Incisors are inclined toward the buccal or labial surface b.Upper posterior teeth are inclined lingualy, simlarity from the canine to the premolars. Upper molar crowns are inclined siightly more than the canines and premolars. c.Lower posterior teeth are inclined lingually, progressively more from canine to molars
4. Rotations: Rotations are not present
5. Spaces: Spaces are not present between teeth
6. Occlusal plane: The plane is either flat or slightly curved