1

DENTAL DEVELOPMENT

3

Reasons for learning dental development;

Understand the changes that take place at different ages

Basis of diagnosis and treatment plan

4

Tooth development starts from dental lamina which is an epithelial thickening appearing at the sites of the future dental arches

5

Epithelium – develops into enamel organ

Odontogenic mesenchyme is divided into the dental papilla cells which are progenitors of odontoblast and pulpal tissue

6

Dental sac (follicle) cells give rise to periodontal tissues

Connective tissue starts mineralization of hard dental tissues

7

Root formation starts when dentin and enamel deposition have reached the junction of the inner and outer enamel epithelia (after crown formation)

Root formation is initiated by epithelial root sheath

8

Information on chronology of tooth development is given as mean values from series of observations

9

Normal range within a given population may be large and should not be considered pathological

6-7 weeks intrauterine

Dental Lamina is initiated and positions of primary teeth are determined

10

8-9 weeks intrauterine

Toothbuds of primary teeth are formed

20 weeks intrauterine

Secondary dentition is initiated, usually first molars

11

From 5 months intrauterine to 10 months postnatal

Toothbuds of secondary dentition: central incisors to second premolars are formed

12

POSTNATAL

First year of life: 2nd molar initiated

4-5 years of life: 3rd molar initiated

13

Primary Dentition

Calcification of the primary dentition takes about 4 years

Calcification of crowns starts at 14 to 18 weeks intrauterine

It is mostly complete at birth

14

Root formation of the primary dentition for incisors and first molars starts at 6 months of age

Root formation of the primary canines and second molars starts at 12 months

15

Root formation is completed (apices close) between 1 ½ – 3 years of age, or 1 year after clinical eruption

16

Calcification of permanent dentition starts around birth with the cusps of first molars

Calcification of incisors and canines starts during the first year of life

17

Tooth eruption is the movement of the developing tooth in axial direction

The tooth moves from its original location in the jaw bone to its functional position

18

Eruption of the tooth continues until it meets the teeth in the opposing jaw.

The teeth exhibit continued vertical, mesial, and transverse drift until adult age

19

Bone, resorption occlusal to the crown, and bone deposition apical to the developing roots, facilitates the tooth to break through

20

Tooth eruption has been divided into five phases;

Pre-eruptive

Intraosseous

Mucosal penetration

Preocclusal

Postocclusal

21

Tooth crown is formed

During this stage, the position of the tooth in the jaw bone is relatively stable

22

The root begins to form

The tooth starts moving inside the jaw bone towards the oral cavity

23

Starts when half to three fourths of the root is formed or when the root is 1-2 mm long

What will happen in case the tooth emerges before a root is formed?

24

The tooth locally pierces the gum without symptoms i.e.

No bleeding (dental and oral epithelial fuse)

No pain (discomfort, itching?)

25

Tooth movements from mucosal penetration to pre-occlusion

Relatively takes a short time

26

Characterized by much slower movements

Takes several years

27

Causes of tooth eruption

Root growth

Vascular or tissue pressure

Alveolar bone remodeling

Periodontal ligament traction

*Last two theories receive most attention

28