NEET MDS Lessons
Dental Anatomy
Genetics and Environment: Introduction
The size of the teeth and the timing of the developing dentition and its eruption are genetically determined. Teeth are highly independent in their development. Also, teeth tend to develop along a genetically predetermined course.: tooth development and general physical development are rather independent of one another. Serious illness, nutritional deprivation, and trauma can significantly impact development of the teeth. This genetic independence (and their durability) gives teeth special importance in the study of evolution.
Teeth erupt full size and are ideal for study throughout life. Most important, age and sex can be recorded.
When teeth erupt into the oral cavity, a new set of factors influence tooth position. As the teeth come into function, genetic and environment determine tooth position.
In real life, however, girls shed deciduous teeth and receive their permanent teeth slightly earlier than boys, possibly reflecting the earlier physical maturation achieved by girls. Teeth are slightly larger in boys that in girls
MAXILLARY LATERAL INCISORS
it is shorter, narrower, and thinner.
Facial: The maxillary lateral incisor resembles the central incisor, but is narrower mesio-distally. The mesial outline resembles the adjacent central incisor; the distal outline--and particularly the distal incisal angle is more rounded than the mesial incisal angle (which resembles that of the adjacent central incisor. The distal incisal angle resembling the mesial of the adjacent canine.
Lingual: On the lingual surface, the marginal ridges are usually prominent and terminate into a prominent cingulum. There is often a deep pit where the marginal ridges converge gingivally. A developmental groove often extends across the distal of the cingulum onto the root continuing for part or all of its length.
Proximal: In proximal view, the maxillary lateral incisor resembles the central except that the root appears longer--about 1 1/2 times longer than the crown. A line through the long axis of the tooth bisects the crown.
Incisal: In incisal view, this tooth can resemble either the central or the canine to varying degrees. The tooth is narrower mesiodistally than the upper central incisor; however, it is nearly as thick labiolingually.
Contact Points: The mesial contact is at the junction of the incisal third and the middle third. The distal contact is is located at the center of the middle third of the distal surface.
Root Surface:-The root is conical (cone-shaped) but somewhat flattened mesiodistally.
Time for tooth development
Entire primary dentition initiated between 6 and 8 weeks of embryonic development.
Successional permanent teeth initiated between 20th week in utero and 10th month after birth Permanent molars between 20th week in utero (first molar) and 5th year of life (third molar)
TYPES OF TEETH
The human permanent dentition is divided into four classes of teeth based on appearance and function or position.
Incisors, Canines, Premolars & Molars
INNERVATION OF THE DENTIN-PULP COMPLEX
- Dentine Pulp
- Dentin
- Nerve Fibre Bundle
- Nerve fibres
The nerve bundles entering the tooth pulp consist principally of sensory afferent fibers from the trigeminal nerve and sympathetic branches from the superior cervical ganglion. There are non-myelinated (C fibers) and myelinated (less than non, A-delta, A-beta) fibers. Some nerve endings terminate on or in association with the odontoblasts and others in the predentinal tubules of the crown. Few fibers are found among odontoblasts of the root.
In the cell-free zone one can find the plexus of Raschkow.