Comparative Comparative dental anatomydental anatomy

The dentition in human is different in The dentition in human is different in many ways from other vertebrates in many ways from other vertebrates in form and function. form and function.

There are four classes of tooth forms:There are four classes of tooth forms: Single cone (haplodont)Single cone (haplodont) Three cusps in line (triconodont)Three cusps in line (triconodont) Three cusps in a triangle Three cusps in a triangle

(tritubercular molar)(tritubercular molar) Four cusps in a quadrangle Four cusps in a quadrangle

(quadritubercular molar)(quadritubercular molar)

The haplodont classThe haplodont class::

Is the simplest form of tooth (the Is the simplest form of tooth (the single cone), this type of dentition single cone), this type of dentition includes many teeth in both jaws includes many teeth in both jaws where jaw movements are limited to where jaw movements are limited to simple open and close (hinge) simple open and close (hinge) movements and no occlusion of teeth movements and no occlusion of teeth occurs in this class, like in alligator occurs in this class, like in alligator

The triconodont classThe triconodont class::

Exhibits three cusps in line in Exhibits three cusps in line in posterior teeth the largest cusp is posterior teeth the largest cusp is centered with a smaller cusp located centered with a smaller cusp located anteriorly and another posteriorly. anteriorly and another posteriorly. Purely triconodont dentitions are not Purely triconodont dentitions are not seen, although certain breeds of seen, although certain breeds of dogs and dogs and

other carnivores have teeth other carnivores have teeth

reflecting the triconodont form.reflecting the triconodont form.

Tritubercular classTritubercular class:: The three-cusp The three-cusp

arrangement of the arrangement of the tritubercular molar tritubercular molar class and the more class and the more efficient three-efficient three-cornered cornered tritubercular molar tritubercular molar arrangement are arrangement are both consistent with both consistent with bypassing each other bypassing each other more or less when more or less when the jaw is opened or the jaw is opened or closed. (dogs and closed. (dogs and other animals)other animals)

Quadritubercular classQuadritubercular class::

It reflects an occlusal contact It reflects an occlusal contact relationship between the teeth of the relationship between the teeth of the upper and lower jaws. upper and lower jaws.

Animals that have dentitions similar Animals that have dentitions similar to that of humans are anthropoid to that of humans are anthropoid apes. apes.

OcclusionOcclusion: when the teeth in the : when the teeth in the upper jaw come to contact with upper jaw come to contact with teeth in the lower jaw this is called teeth in the lower jaw this is called occlusion (the way the teeth meet occlusion (the way the teeth meet and function)and function)

Malocclusion: any deviation from Malocclusion: any deviation from normal occlusion is said to be a normal occlusion is said to be a malocclusion.malocclusion.

The Key to occlusionThe Key to occlusion

When the When the mesiolingual cusp mesiolingual cusp of the maxillary 1of the maxillary 1stst molar occluded in molar occluded in the Buccal Groove the Buccal Groove of the mandibular of the mandibular 11stst molar this is molar this is named the key to named the key to occlusion by occlusion by Angle.Angle.

AngleAngle’’s classification of s classification of malocclusionmalocclusion