SURFACES OF THE TEETH

Facial, Mesial, Distal, Lingual, and Incisal Surfaces

• The facial is the surface of a tooth that "faces" toward the lips or cheeks. When there is a requirement to be more specific, terms like labial and buccal are used. The labial is the surface of an anterior tooth that faces toward the lips. The buccal is the surface of a posterior tooth that faces toward the cheek.
• The mesial is the proximal surface closest to the midline of the arch. The distal is the opposite of mesial. The distal is the proximal surface oriented away from the midline of the arch.
• The lingual is the surface of an anterior or posterior tooth that faces toward the tongue. Incisal edges are narrow cutting edges found only in the anterior teeth (incisors). Incisors have one incisal edge
• Proximal Surfaces

A tooth has two proximal surfaces, one that is oriented toward the midline of the dental arch (mesial) and another that is oriented away from the midline of the arch (distal).

MANDIBULAR THIRD MOLAR

Facial: The crown is often short and has a rounded outline.

Lingual: Similarly, the crown is short and the crown is bulbous.

Proximal: Mesially and distally, this tooth resembles the first and second molars. The crown of the third molar, however, is shorter than either of the other molars

Occlusal: Four or five cusps may be present. Occlusal surface is a same as of the first or second molar, or poorly developed with many accessory grooves. The occlusal outline is often ovoid and the occlusal surface is constricted. Occasionally, the surface has so many grooves that it is described as crenulated--a condition seen in the great apes

Contact Points; The rounded mesial surface has its contact area more cervical than any other lower molar. There is no tooth distal to the third molar..

Roots:-The roots, two in number, are shorter in length and tend to be fused together. they show a distinct distal curve

Stationary Relationship

a) .Centric Relation is the most superior relationship of the condyle of the mandible to the articular fossa of the temporal bone as determined by the bones ligaments. and muscles of the temporomandibular joint; in an ideal dentition it is the same as centric occlusion.

(b) Canines may also be used to confirm the molar relationships to classify occlusion when molars are missing; a class I canine relationship shows the cusp tip of the maxillary canine facial to the mesiobuccal cusp of the first permanent molar

c) Second primary molars are used to classify the occlusion in a primary dentition

(d) In a mixed  dentition the first permanent molars will erupt into a normal occlusion if there is a terminal step between the distal  surfaces of maxillarv and mandibular second primary molars; if these surfaces are flush, a terminal plane exists and the first permanent molars will first erupt into an end-to-end relationship until there is a shifting of space or exfoliation of the second primary molar

THE DECIDUOUS DENTITION

I. The Deciduous Dentition

-It is also known as the primary, baby, milk or lacteal dentition.

diphyodont, that is, with two sets of teeth. The term deciduous means literally 'to fall off.'

  There are twenty deciduous teeth that are classified into three classes. There are ten maxillary teeth and ten mandibular teeth. The dentition consists of incisors, canines and molars.

Nutrition and tooth development

As in other aspects of human growth and development, nutrition has an effect on the developing tooth. Essential nutrients for a healthy tooth include calcium, phosphorus, fluoride, and vitamins A, C, and D. Calcium and phosphorus are needed to properly form the hydroxyapatite crystals, and their levels in the blood are maintained by Vitamin D. Vitamin A is necessary for the formation of keratin, as Vitamin C is for collagen. Fluoride is incorporated into the hydroxyapatite crystal of a developing tooth and makes it more resistant to demineralization and subsequent decay.

Deficiencies of these nutrients can have a wide range of effects on tooth development. In situations where calcium, phosphorus, and vitamin D are deficient, the hard structures of a tooth may be less mineralized. A lack of vitamin A can cause a reduction in the amount of enamel formation. Fluoride deficency causes increased demineralization when the tooth is exposed to an acidic environment, and also delays remineralization. Furthermore, an excess of fluoride while a tooth is in development can lead to a condition known as fluorosis.

The pre-dentition period.

-This is from birth to six months.

-At this stage, there are no teeth. Clinically, the infant is edentulous

-Both jaws undergo rapid growth; the growth is in three planes of space: downward, forward, and laterally (to the side). Forward growth for the mandible is greater.

-The maxillary and mandibular alveolar processes are not well developed at birth.

-occasionally, there is a neonatal tooth present at birth. It is a supernumerary and is often lost soon after birth.

-At birth, bulges in the developing alveoli precede eruption of the deciduous teeth. At birth, the molar pads can touch.