TOOTH ROOT FORMATION- STAGES. RESORPTION OF PRIMARY TEETH
The development of tooth root begins after the formation of the crown.
Phases of Development:
- Pre-eruptive
- Eruptive
- Functional Eruptive
Phases of Tooth Root Formation:
- Start of Tooth Root Development
- Short Root Walls
- Root Walls, close to final length
- Constructed root walls but undeveloped apex
- Constructed apex
START OF TOOTH ROOT DEVELOPMENT
- Crown is formed and root wall construction begins
SHORT ROOT WALLS
- Can be seen as short, thin, tapered root
- Walls are diverging. Around the end of the root is situated the growth zone known as the dental follicle
- Dental Pulp is wider apically than cervical
- Periodontium is built only where there are root walls and is very wide
- PDL are not connected
ROOT WALLS CLOSE TO FINAL LENGTH AND ELONGATED
- Root walls are elongated. Root walls are thickened
- They are parallel and tapered like a spear.
- Proliferative zone (Growth zone) is clearly visible. Pulp is almost equally wide in the cervical area and at the end of root walls.
- Growth zone can be mistaken for periodontitis. Timing of development of teeth must be known in order to avoid fatal errors.
- Periodontium is created only at the level of forming root. Periodontal space is large
ROOT WALLS ARE CONSTRUCTED BUT UNDERDEVELOPED APEX
- Eruption is completed and tooth is in function
- Root walls have reached a length, leading to their thickening and slightly convergent
- Pulp is wider cervical and narrower apically
- Apex not built yet so leads to the decreasing of the proliferative zone
CONSTRUCTED APEX
- At this point, the apex is built, the periodontium is built, not only along the walls of the root but in the area of the apex
- Proliferative zone decreases
SHEDDING OF PRIMARY TEETH
Humans are considered diphyodont. We posses two dentitions: primary and permanent
- Teeth in primary dentition are smaller and fewer in number than permanent dentition to conform to the smaller jaws of the young person
- Functioning of Dentition:
- Primary Dentition: from about 2 to 6 yo
- Mixed Dentition: from about six to 10/11 yo
- Permanent Dentition: after this period
MIXED DENTITION
- Only part of primary teeth root is present while they undergo resorption
- Only part of permanent roots is present while they are in formative stage.
- Nearly 50 teeth can be present in the jaws during these 4 years
PHYSIOLOGICAL RESORPTION
- Physiological resorption of primary teeth is implemented by the resorptive organ