Tooth Eruption

Tooth Eruption

The process by which developing teeth emerge through soft tissue of jaw/musosa.

The eruptive phase is not _____ and it is not _______

The eruptive phase is not RAPID and it is not CONTINUOUS.

Tooth eruption ends only when _____

the tooth is lost.

Three phases of Tooth Eruption:

1. Preeruptive phase
2. Prefunctional eruptive phase
3. Functional eruptive phase
(pasteruptive phase)

Preeruptive Phase:

includes all movements of primary and permanent tooth crowns from the time of their initiation and formation to the time of crown completion.

All movements occur within the crypts of bones and before _______ begins.

ROOT FORMATION

This phase ends when ______

ROOT FORMATION BEGINS.

Permanent anterior teeth-

Develop lingual to incisal level of primary teeth.

Permanent premolars and molars develop near-

Occlusal area of primary molars.

Prefunctional Eruptive Phase:
Begins with-
Ends with-

BEGINS with the initiation of root formation.
ENDS when the teeth reach occlusal contact.

Four Phases of Prefunctional Eruptive Phase:

1. Root formatioin
2. Incisal or occlusal movement
3. Emergence
4. Occlusal Contact

Root Formation-

Proliferation of epithelial root sheath stimulates formation of root dentin and pulp tissue. More space required for developing root.

Incisal or Occlusal movement-

Developing tooth needs more room.
Eruption pathway beings to develop.
REE fuses with oral epithelium.

Emergence-

Crown tip penetrates through fused epithelial layers and into oral cavity.

Occlusal contact-

Movement occurs until contact is made with opposing tooth.
Sized of clinical crown grows larger (size of anatomical crown is constant)
Gingival attachment migrates apically.

Eruption pathway-

The area of the DENTAL FOLLICLE degenerates to form a pathway for the crown towards oral mucosa.
(blood vessels decrease and nerve fibers break apart)
**osteoclasts and blasts involved**

Gubernacular cord-

Fibers help guid crown along pathway.
Degenerated area develops into an inverted triangular shape.

Reduced Enamel Epithelium (REE)

surrounds crown of tooth.
FUSES with ORAL EPITHELIUM to form REDUCED EPITHELIUM LAYER.

Reduced Epithelium Layer

As tooth emerges into oral cavity, the epithelial attachment shifts farther down into the crown until entire crown erupts.

** Eventually becomes known as Junctional Epithelium.**

As tooth emerges fiber bundles attach to___

tooth surface.

PDL fiber development-
First fibers formed in____

Cervical Area

Direction of collagen fiber bundles changes as _____

tooth erupts

Collage fibers have a __________ at this stage to accomodate the tooth eruption and constant arrangement.

HIGH TURNOVER RATE (24 hrs)

When tooth reaches occlusion, the orientation of the fiber bundles____

become complete.

Apical fibers develop where?

at the ends of the root along with bony trabeculae.

Functional Eruptive Phase
(Posteruptive Phate)
BEGINS when-

The tooth comes into occlusal contact and CONTINUES for as long as the tooth is in the mouth.

Occlusal contact results in these changes:

1. Principal fibers of PDL arrange themsevels in perferred directions.
2. Principal fibers increase in size.
3. BV and nerves become more organized in interstitial spaces.
4. Mineral density of alveolar bone increases.

Tooth Movement During Posteruptive phase Continues for as long as______

Tooth is present.

Physiological-

1. Occlusal Wear: occlusal changes with attrition and abrasion
2. Mesial Drift: Teeth shift toward midline with age.
3. Perioral forces: Cheek/tongue movements or habit.

Pathological-

1. Mesial Drift: Tooth loss- to mid.
2. Excessive parafunction: grinding
3. Periodontal disease: tooth movement
4. Bulimia: loss of enamel.

Causes of Tooth Eruption:

1. Root Growth
2. Vascular Pressure
3. Bone Growth
4. Ligament Traction

Root Growth-

Pushes crown up

Vascular Pressure-

Increase in tissue fluid pressure in periapical region moves tooth.

Bone Growth-

Selective resorption and deposition of bone causes tooth to move.

Ligament Traction-

Cells and fibers of PDL pull tooth into occlusion

6/4 Rule:

4 teeth emerge for every 6 mo.

Order of Emergence of Primary Teeth:

Central, Lateral, 1st molar, Canine, 2nd Molar

Mandibular Centrals erupt at______

About 6 months of age.

Mandibular Sequence of Permanent Teeth:

(Central OR 1st Molar), Lateral, Canine, 1st Premolar, 2nd Premolar, 2nd Molar, 3rd Molar.

Maxillary Sequence of Permanent Teeth:

1st Molar, Central, Lateral, 1st Premolar, 2nd Premolar, Canine, 2nd Molar, 3rd Molar.

Mandibular centrals, Maxillary Molars, and Mandibular Molars erupt at _____

Age 6-7 Years old.

Primary Dentition:

2-8 Yrs.

Mixed Dentition:

8-12 Yrs.

Permanent Dentition:

12+ Yrs.

Succesional Teeth:

Permanent teeth that replace the 20 primary teeth

Accessional Teeth:

Permanent teeth that do not replace a primary tooth (12)

Leeway space-

accounts for the difference in size btw primary teeth and permanent teeth. (Molars and premolars)

Maxillary Arch size:

1.3 mm

Mandibular Arch size:

3.1 mm