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.

MAXILLARY CUSPIDS (CANINE)

The maxillary cuspid is usually the longest tooth in either jaw. canines are considered the corner stones of the dental arch They are the only teeth in the dentition with a single cusp.

Facial Surface:- The facial surface of the crown differs considerably from that of the maxillary central or lateral incisors. In that the incisal edges of the central and lateral incisor are nearly straight, the cuspid has a definite point, or cusp.  There are two cutting edges, the mesioincisal and the distoincisal. The distoincisal cutting edge is the longer of the two. The developmental grooves prominent on the facial surface  extending two-thirds of the distance from the tip of the cusp to the cervical line.  The distal cusp ridge is longer than the mesial cusp ridge

Lingual Surface:  Distinct mesial and distal marginal ridges, a well-devloped cingulum, and the cusp ridges form the boundries of the lingual surface. The prominent lingual ridge extends from the cusp tip to the cingulum, dividing the lingual surface into mesial and distal fossae.

Proximal: The mesial and distal aspects present a triangular outline. They resemble the incisors, but are more robust--especially in the cingulum region

Incisal: The asymmetry of this tooth is readily apparent from this aspect. It usually thicker labiolingually than it is mesiodistally. The tip of the cusp is displaced labially and mesial to the central long axis of this tooth.

Root Surface:-The root is single and is the longest root in the arch. It is usually twice the length of the crown.

FORMATION OF THE PERMANENT DENTITION

Twenty deciduous tooth buds are formed initially.
Proliferative activity of the dental lamina during the bell stage that leads to formation of permanent tooth buds (cap stage) lingual of each deciduous tooth germ.
Molars have no predecessors; they are formed by posterior proliferation of the dental lamina.

HARD TISSUE FORMATION

Hard tissue formation starts at the late stages of the bell stage.
Differentiatioin of cells into odontoblasts and ameloblasts.
The cells of the inner dental epithelium will become ameloblasts.
The cells of the dental papilla opposite to the inner dental epithelium will become odontoblasts.
Dentin is formed before enamel.
Dentin initiates the formation of enamel.

ROOT FORMATION

The root of the tooth is composed by dentin and cementum.
Dentinogenesis is initiated by the odontoblasts.
Odontoblasts are formed as epithelial cells continue to proliferate from the cervical loop as a double layer of cells known as Hertwig's root sheath.

TOOTH SHAPE

The shape of the crowns results from the interaction of inner dental epithelium and the dental papilla.
The cells of the inner dental epithelium have a programmed proliferation.
This internal program determines the tooth form.

The fate of the dental lamina

Rests of Serres
The rest of Serres are rests of the dental lamina identified in the gingival soft tissues.
They are round to ovoid aggregates of epithelial cells that have clear cytoplasm (glucogen rich).
They result from early breakup of the dental lamina during bell stage.

Rests of Malassez
The rests of Malassez result from breakup of the Hertwig's root sheath during root formation.
They can be identified in the periodontal ligament and are responsible for the development of radicular cysts.

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).

MANDIBULAR SECOND BICUSPID

Facial: From this aspect, the tooth somewhat resembles the first, but the buccal cusp is less pronounced. The tooth is larger than the first.

Lingual: Two significant variations are seen in this view. The most common is the three-cusp form which has two lingual cusps. The mesial of those is the larger of the two. The other form is the two-cusp for with a single lingual cusp. In that variant, the lingual cusp tip is shifted to the mesial.

Proximal: The buccal cusp is shorter than the first. The lingual cusp (or cusps) are much better developed than the first and give the lingual a full, well-developed profile.

Occlusal: The two or three cusp versions become clearly evident. In the three-cusp version, the developmental grooves present a distinctive 'Y' shape and have a central pit. In the two cusp version, a single developmental groove crosses the transverse ridge from mesial to distal

Contact Points; Height of Curvature: From the facial, the mesial contact is more occlusal than the distal contact.The distal marginal ridge is lower than the mesial marginal ridge

Root Surface:-The root of the tooth is single, that is usually larger than that of the first premolar  

the lower second premolar is larger than the first, while the upper first premolar is just slightly larger than the upper second

There may be one or two lingual cusps

Cementum & Cementogenesis

Cementum formation is called cementogenesis and occurs late in the development of teeth. Cementoblasts are the cells responsible for cementogenesis. Two types of cementum form: cellular and acellular.

Acellular cementum forms first. The cementoblasts differentiate from follicular cells, which can only reach the surface of the tooth's root once Hertwig's Epithelial Root Sheath (HERS) has begun to deteriorate. The cementoblasts secrete fine collagen fibrils along the root surface at right angles before migrating away from the tooth. As the cementoblasts move, more collagen is deposited to lengthen and thicken the bundles of fibers. Noncollagenous proteins, such as bone sialoprotein and osteocalcin, are also secreted. Acellular cementum contains a secreted matrix of proteins and fibers. As mineralization takes place, the cementoblasts move away from the cementum, and the fibers left along the surface eventually join the forming periodontal ligmaments.

Cellular cementum develops after most of the tooth formation is complete and after the tooth occludes (in contact) with a tooth in the opposite arch. This type of cementum forms around the fiber bundles of the periodontal ligaments. The cementoblasts forming cellular cementum become trapped in the cementum they produce.

The origin of the formative cementoblasts is believed to be different for cellular cementum and acellular cementum. One of the major current hypotheses is that cells producing cellular cementum migrate from the adjacent area of bone, while cells producing acellular cementum arise from the dental follicle. Nonetheless, it is known that cellular cementum is usually not found in teeth with one root. In premolars and molars, cellular cementum is found only in the part of the root closest to the apex and in interradicular areas between multiple roots.