Primary Teeth (Milk Teeth): Development, Formation, Eruption and Abnormalities

Teeth development is a complex process that begins in early fetal development terms (during pregnancy) and lasts up to 18-20 years. During the fetal development period tooth rudiments are formed, which eventually transform first into temporary (milk) and then in permanent teeth.

Development, formation and differentiation of tooth rudiments

This process begins at 6-8 weeks of fetal development. First a roll is formed along the top and bottom of the mouth slit, which is converted into a plate divided into two parts: lip and tooth. Along the free edge of dental plates appear growths of tissue in the form of bell-shaped bulges, 10 in each jaw.

They are so-called “dental organs”. Along with the growth the dental body gradually eliminates from dental plate and remains connected with it only by a thin layer of cells – the cervix of dental organ. Around the tooth organ a dental sac is formed.

Gradually the differentiation of tissues starts to happen – first homogeneous cells begin to acquire different shapes and function. The fluid dissecting the cells begins to accumulate in the tooth organ between the cells of the central department – this is how the soft tissue of the tooth is formed – the pulp.

Cells surrounding the pulp acquire another form – they form hard tissues – dentin (at the 4th month of fetal life) and enamel (at the 5th month of fetal life).

Development of roots of milk teeth occurs after birth and coincides with the beginning of teething. At this point, the crown of teeth is usually fully formed.

How the milk tooth is formed

Milk teeth have the same shape as the permanent ones, but there are some differences: they are smaller than permanent, their enamel has a bluish tint, the roots are shorter, and lumps of milk incisors and canines on the cutting surface are less developed.

Eruption of primary teeth

Tooth eruption is a complex metabolic process that involves both nervous and endocrine systems. A variety of causes affect teething: heredity, diet of mother and child, geographical conditions.
Milk (temporary) teeth erupt from 6 months to 2.5 years in a certain period and in a certain sequence, usually in pairs.

There are 20 milk teeth in total: 8 incisors, 4 canines, 8 molars (4 central and 4 laterals).

In the center of set of teeth there are teeth that are adapted for biting and tearing food (incisors and canines), and on the sides – for its milling and grinding (molars). The order of the teeth is written in the form of dental formula, in which individual teeth or groups of teeth are designated by figures.

The calculation starts from the middle of dentition separately for each side of the upper and lower row. For example, from center to periphery: the central incisor, lateral incisor, canine, central molar, lateral molar (dental formula has four series, two for each jaw).

Correct sign of teething is symmetrical eruption of teeth in a certain sequence. The central incisors on the lower jaw are usually the first to erupt, and then the central incisors on the upper jaw follow (6-8 months). Lateral incisors erupt at 8-12 months, central molars – in 12-16 months, canines – in 16-20 months, side molars – in 20-30 months.

There can be significant lapse from this scheme in one or the other way. Cases of eruption of incisors before birth happen very seldom. Mineralization of teeth (enamel saturation with minerals, mainly calcium) ends by 3,5 – 4 years. By five years the resorption of roots of milk teeth begins.

Abnormalities of primary teeth development

The abnormalities of teeth development include: violations of the shape, size, number of teeth, and timing of eruption, position and structure of dental hard tissues. These anomalies may arise from different causes: hereditary characteristics, maternal nutrition during pregnancy, her diseases, the use of various toxic substances, and so on.

Abnormalities of tooth shape occur during the prenatal period. Both the crown and root may have irregular shape. This anomaly is most common in the upper lateral incisors. Anomalies in the size of the tooth may show a change in its width, height and thickness. Shapes and sizes of crowns can be changed under the influence of various diseases of hard dental tissues. Anomalies of the teeth number mean the increase (excessive teething) or decrease (and sometimes complete absence) of number of teeth.

Any abnormalities of primary teeth should be consulted with your dentist who will determine further treatment policy for such a child.

Read more about Primary Teeth (Milk Teeth):

1. Primary Teeth (Milk Teeth): Development, Formation, Eruption and Abnormalities
2. Primary Teeth (Milk Teeth): Dental Caries, Pulpitis, Periodontitis and Treatment
3. Primary Teeth (Milk Teeth): Losing Milk Teeth, Baby Bottle Caries, Treatment under Anesthesia