Լight modeDark mode

Introduction to Ideal Occlusion

Where do the teeth need to be to achieve ideal occlusion? To find out, we'll turn to two of the most inventive pioneers in orthodontics: Dr Angle and Dr Andrews.

Dr Edward Angle

Born on a Pennsylvania farm In 1855, Dr Edward Angle is considered the father of modern orthodontics. He Invented Ingenious mechanical appliances for moving teeth and created the broad classifications of malocclusion that orthodontists still use today.

See below to find out more about these classifications:

Molar Relationship Class I: Dr Angle believed that the most fundamental characteristic of Ideal occlusion was a proper molar relationship. He found that in patients with healthy bites, the mesial-buccal cusp of the first upper molar occludes in the buccal groove of the first lower molar. He called this ideal configuration a Class I molar relationship.

Molar Relationship Class II: If the mesial-buccal cusp of the upper first molar is anterior to this groove, by the width of a premolar or more, it's considered a Class II molar relationship. The molar relationship shows the mesiobuccal groove of the mandibular first molar is DISTALLY (posteriorly) positioned when in occlusion with the mesiobuccal cusp of the maxillary first molar. Usually, the mesiobuccal cusp of the maxillary first molar rests in between the first mandibular molar and second premolar.

Molar Relationship Class II Div 1: The molar relationships are like that of Class II and the maxillary anterior teeth are protruded. Teeth are proclined and a large overjet Is present.

Molar Relationship Class II Div 2: The molar relationships are Class Il where the maxillary central incisors are retroclined. The maxillary lateral incisor teeth may be proclined or normally inclined. Retroclined and a deep overbite exist.

Molar Relationship Class II: If the upper cusp is posterior to this groove, by the width of a premolar or more, it's called a Class Ill molar relationship. The mesiobuccal cusp of the maxillary first permanent molar occludes DISTALLY (posteriorly) to the mesiobuccal groove of the mandibular first molar.

Angle's system is very useful but there are still many kinds of malocclusion that can't be summed up by a simple class number Now let's take a look at Dr Lawrence Andrews.

Dr Lawrence Andrew

In 1960, an orthodontist in San Diego named Lawrence Andrews grew frustrated with this imprecision. He reasoned that to accurately diagnose all various types of malocclusion, you would first need to identify and define the fundamental characteristics of ideal occlusion. Dr Andrews began collecting study models from people with naturally ideal dentition to discover the traits they held in common.

See below to find out more about his study:

Six Keys to Normal Occlusion

Key 1 - Molar relationship: Teeth in Ideal occlusion should have a Class I molar and canine relationship as described by Dr Angle. Dr Andrews also specified that the distal surface of the upper first molars distobuccal cusp should occlude with the mesial surface of the lower second molars mesial-buccal cusp.

Key 2 - Crown Angulation: Some doctors refer to crown angulation as "tip". This is the angle formed by the facial axis of the clinical crown and aligned perpendicular to the occlusal plane from a facial perspective. Crown angulation is considered positive if the occlusal portion of the facial axis Is mesial to the gingival portion and negative if it is distal.

What is the ideal arch?

In an ideal arch, all the crowns should be angled positively. In other words, the crowns should tilt mesially from the gums.

Key 3 - Crown Inclination: This is the facial or lingual angle of the crown-the angle formed by the facial axis of the clinical crown and the line perpendicular to the occlusal plane from a mesial perspective. Crown Inclination is considered positive if the occlusal portion of the facial axis Is facial to the gingival portion and negative if it is lingual.

Key 4 - Rotations: The teeth should be free of undesirable rotations. A rotated molar won't occlude properly and may occupy too much space In the arch.

Key 5-Spacing: The teeth should be free of undesirable spaces. Unless there's a genuine tooth size discrepancy, the contacts should be tight.

Key 6-Curve of Spee: This describes the curvature of the occlusal plane. The Curve of Spee should be flat or slightly concave. A concave curve that is too deep won't allow enough space for the upper teeth and a convex curve will spread them out too far.