Basic Guide to Oral Health Education and Promotion. Alison Chapman
after birth.
Figure 1.6 Cleft lip and palate in a six‐month‐old baby.
Source: Dreamstime.com/Pattarawit Chompipat | ID 84347343. Reproduced with permission of Dreamstime.com.
Upward growth of bone begins along the mandibular arch forming the alveolar process, which will go on to surround the developing tooth germs.
Week 8
By week 8, ossification (bone development) of the maxilla begins.
Tooth germ development in the foetus
Tooth germ (tissue mass) develops in three stages known as bud, cap, and bell. The developing tooth germ can be affected by the mother’s health (see Chapter 20).
1 Bud – at 8 weeks, clumps of cells form swellings called enamel organs. Each enamel organ is responsible for the development of a tooth.
2 Cap – the enamel organ continues to grow and by 12 weeks (the late cap stage), cells have formed the inner enamel epithelium and the outer enamel epithelium. Beneath the inner enamel epithelium, the concentration of cells will eventually become the pulp. The enamel organ is surrounded by a fibrous capsule (the dental follicle), which will eventually form the periodontal ligament.
3 Bell – by 14 weeks, the enamel organ will comprise different layers, which will continue to develop to form the various parts of the tooth.
MAIN FUNCTIONS OF THE ORAL CAVITY
The oral cavity is uniquely designed to carry out two main functions:
1 Begin the process of digestion. The cavity’s hard and soft tissues, lubricated by saliva, are designed to withstand the stresses of:
Biting.
Chewing.
Swallowing.
1 Produce speech.
TEETH
Different types of teeth are designed (shaped) to carry out different functions. For example, canines are sharp and pointed for gripping and tearing food, while molars have flatter surfaces for chewing. Tooth form in relation to function is called morphology.
Dental nurses and healthcare workers may remember from their elementary studies that there are two types of dentition (a term used to describe the type, number and arrangement of natural teeth):
1 Primary (deciduous) dentition – consisting of 20 baby teeth.
2 Secondary (permanent) dentition – consisting of 32 adult teeth.
Primary dentition
There are three types of deciduous teeth that make up the primary dentition (Figure 1.7): incisors, canines, and molars (first and second). Table 1.1 details their notation (the code used by the dental profession to identify teeth), approximate eruption dates, and functions.
Figure 1.7 Primary dentition.
Source: From [1]. Reproduced with permission of Elsevier.
Table 1.1 Primary dentition (notation, approximate eruption dates, and functions).
| Tooth | Notation | Approximate eruption date | Function |
|---|---|---|---|
| Incisors | (a & b) | 6–12 months (usually lowers first) | Biting |
| First molars | (d) | 12–24 months | Chewing |
| Canines | (c) | 14–20 months | Tearing |
| Second molars | (e) | 18–30 months | Chewing |
Table 1.2 FDI World Dental Federation notation for deciduous (primary) dentition.
| Patient’s upper right (5) | Patient’s upper left (6) |
|---|---|
| 55 54 53 52 51 | 61 62 63 64 65 |
| 85 84 83 82 81 | 71 72 73 74 75 |
| Patient’s lower right (8) | Patient’s lower left (7) |
Table 1.2 details the FDI World Dental Federation notation for primary dentition, which is a charting system commonly used by dentists to associate information to a specific tooth; where the quadrant number is the first digit applied, and the second number identifies the individual tooth.
Secondary dentition
There are four types of permanent teeth that make up the secondary dentition (Figure 1.8): incisors, canines, premolars, and molars. Table 1.3 details their notation, approximate exfoliation/eruption dates, and functions. Table 1.4 details the FDI World Dental Federation notation for secondary dentition.
It is important to remember that these exfoliation/eruption dates are only approximate and vary considerably in children and adolescents. The educator should be prepared to answer questions from parents who are worried that their child’s teeth are not erupting at the same age as their friends’ teeth. Parents often do not realise, for example, that no teeth fall out to make room for the first permanent molars (sixes), which appear behind the deciduous molars.