Transient structures during tooth development

Enamel knot: Thickening of the internal dental epithelium at the center of the dental organ.
Enamel cord: Epithelial proliferation that seems to divide the dental organ in two.
 

Review the role of these two structures
Enamel niche: It is an artifact that is produced during section of the tissue. It occurs because the dental organ is a sheet of proliferating cells rather than a single strand. It looks like a concavity that contains ectomesenchyme.

MORPHOLOGY OF THE DECIDUOUS TEETH

Deciduous Anterior Teeth.

 -The primary anteriors are morphologically similar to the permanent anteriors.

-The incisors are relatively simple in their morphology.

-The roots are long and narrow.

-When compared to the permanent incisors, the mesiodistal dimension is relatively larger when compared to axial crown length

-At the time of eruption, mamelons are not present in deciduous incisors

-They are narrower mesiodistally than their permanent successors.

Maxillary First Deciduous Molar.

-The notation is B or I.

-It looks a bit like an upper 1st premolar.

-There are three roots.

-It has a strong bulbous enamel bulge that protrudes buccally at the mesial.

-It is the smallest of the deciduous molars in crown height and in the mesiodistal dimension.

MANDIBULAR FIRST BICUSPID

Facial: The outline is very nearly symmetrical bilaterally, displaying a large, pointed buccal cusp. From it descends a large, well developed buccal ridge.

Lingual: This tooth has the smallest and most ill-defined lingual cusp of any of the premolars. A distinctive feature is the mesiolingual developmental groove

Proximal: The large buccal cusp tip is centered over the root tip, about at the long axis of this tooth. The very large buccal cusp and much reduced lingual cusp are very evident. You should keep in mind that the mesial marginal ridge is more cervical than the distal contact ridge; each anticipate the shape of their respective adjacent teeth.

Occlusal: The occlusal outline is diamond-shaped. The large buccal cusp dominates the occlusal surface. Marginal ridges are well developed and the mesiolingual developmental groove is consistently present. There are mesial and distal fossae with pits,

Contact Points: When viewed from the facial, each contact area/height of curvature is at about the same height.

Root Surface:-The root of the mandibular first bicuspid is usually single, but on occasion can be bifurcated (two roots).

 lntraarch relationship refers to the alignment of the teeth within an arch

1. In an ideal alignment teeth should contact at their proximal crests of curvature. A continuous arch form is observed in occlusal view

Curves of the occlusal plane (a line connecting the cusp tips of the canines, premolars, and molars) are observed from the proximal view

Curve of Spee: anterior to posterior curve; for mandibular teeth the curve is concave and for maxillary teeth it is convex

Curve of Wilson- medial to lateral curve for mandibular teeth the curve is also convex and for the maxillary it is convex

2. Contact does not always exist Some permanent dentitions have normal spacing

Primary dentitions often have developmental spacing in the anterior area: some primary den titions have a pattern of spacing called primate spaces between the primary maxillary lateral incisors and canine and between the mandibular canine and first mo1ar

Disturbances to the intraarch alignment are described as

a. Qpen contact where interproximal space exist  because of missing teeth oral habits, dental disease, or overdeveloped frena

b. where contact or position is at an unexpected area because of developmental disturbances, crowding, dental caries or periodontal ligament for their misplaced position: facial, lingual. mesial, supra(supraerupted) infra (infraerupted) and torso (rotated) version

The very first histological evidence of tooth development appear during the second month of intrauterine life. Calcification of deciduous incisors begins at 3-4 months in utero.