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.

The periodontium, which is the supporting structure of a tooth, consists of the cementum, periodontal ligaments, gingiva, and alveolar bone. Cementum is the only one of these that is a part of a tooth. Alveolar bone surrounds the roots of teeth to provide support and creates what is commonly called a "socket". Periodontal ligaments connect the alveolar bone to the cementum, and the gingiva is the surrounding tissue visible in the mouth.

Periodontal ligaments

Histology of the Periodontal Ligament (PDL)

Embryogenesis of the periodontal ligament
The PDL forms from the dental follicle shortly after root development begins
The periodontal ligament is characterized by connective tissue. The thinnest portion is at the middle third of the root. Its width decreases with age. It is a tissue with a high turnover rate.

Maxillary Third Permanent Molar

They are the teeth most often congenitally missing

Facial: The crown is usually shorter in both axial and mesiodistal dimensions. Two buccal roots are present, but in most cases they are fused. The mesial buccal cusp is larger than the distal buccal cusp.

Lingual: In most thirds, there is just one large lingual cusp. In some cases there is a poorly developed distolingual cusp and a lingual groove. The lingual root is often fused to the to buccal cusps.

Proximal: The outline of the crown is rounded; it is often described as bulbous in dental literature. Technically, the mesial surface is the only 'proximal' surface. The distal surface does not contact another tooth.

Occlusal: The crown of this tooth is the smallest of the maxillary molars. The outline of the occlusal surface can be described as heart-shaped. The mesial lingual cusp is the largest, the mesial buccal is second in size, and the distal buccal cusp is the smallest.

Root Surface:-The root may have from one to as many as eight divisions. These divisions are usually fused and very often curved distally.

Deciduous dentition period.

-The deciduous teeth start to erupt at the age of six months and the deciduous dentition is complete by the age of approximately two and one half years of age.

-The jaws continue to increase in size at all points until about age one year.

-After this, growth of the arches is lengthening of the arches at their posterior (distal) ends. Also, there is slightly more forward growth of the mandible than the maxilla.

1. Many early developmental events take place.

-The tooth buds anticipate the ultimate occlusal pattern.

-Mandibular teeth tend to erupt first. The pattern for the deciduous incisors is usually in this distinctive order:

(1) mandibular central

(2) maxillary central incisors

(3) then all four lateral incisors.

-By one year, the deciduous molars begin to erupt.

-The eruption pattern for the deciduous dentition as a whole is:

(1) central incisor

(2) lateral incisor

(3) deciduous first molar

(4) then the canine

(5) then finally the second molar.

-Eruption times can be variable.

2. Occlusal changes in the deciduous dentition.

-The overjet tends to diminish with age. Wear and mandibular growth are a factor in this process.

-The overbite often diminishes with the teeth being worn to a flat plane occlusion.

-Spacing of the incisors in anticipation of the soon-to-erupt permanent incisors appears late. Permanent anterior teeth (incisors and canines) are wider mesiodistally than deciduous anterior teeth. In contrast, the deciduous molar are wider mesiodistally that the premolars that later replace them.

-Primate spaces occur in about 50% of children. They appear in the deciduous dentition. The spaces appear between the upper lateral incisor and the upper canine. They also appear between the lower canine and the deciduous first molar.