Define anchorage e classification of anchorage according to gauri shankar
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anchorage orthodontics definition classification Gauri Shankar
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https://www.scribd.com/presentation/954252754/Anchorage
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anchorage classification "Gauri Shankar" orthodontics types
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https://www.slideshare.net/slideshow/anchorage-231911364/231…
Note: The author's name is S. Gowri Shankar (not "Gauri Shankar") - this is a well-known orthodontics textbook author. The slide presentation above references "Textbook of Orthodontics, S Gowri Shankar (1st Edition)" and its classification scheme. Here is the full detailed answer:
Anchorage in Orthodontics
Definition
Several key definitions have been given:
- T.M. Graber: "The nature and degree of resistance to displacement offered by an anatomic unit when used for the purpose of effecting tooth movement."
- White and Gardiner: "Anchorage is the site of delivery from which a force is exerted."
- In simple terms: anchorage is the resistance to unwanted/reactive tooth movement while desired tooth movement is being produced.
Classification of Anchorage (as per S. Gowri Shankar's Textbook of Orthodontics)
Gowri Shankar classifies anchorage under five major headings:
1. According to the Manner of Force Application
| Type | Description |
|---|---|
| Simple Anchorage | Force application tends to tip/change the axial inclination of the anchor tooth. The anchor unit may tilt but resists displacement. Example: upper removable appliance with reverse loop canine retractor. |
| Stationary Anchorage | The anchor tooth undergoes bodily (translatory) movement - the entire root and crown move together. Offers much greater resistance than simple anchorage. |
| Reciprocal Anchorage | Two teeth or groups of teeth with equal root surface area are used to move each other simultaneously toward or away from each other. Neither unit is truly fixed - both move equally. Example: expansion of upper arch using a screw appliance. |
2. According to the Jaws Involved
| Type | Description |
|---|---|
| Intramaxillary Anchorage | Both the active unit (teeth to be moved) and the anchor unit are in the same jaw/arch. |
| Intermaxillary Anchorage | Anchor units are in opposite jaws - forces from one jaw act on the other. Example: Class II or Class III elastics. |
3. According to the Site of Anchorage
| Type | Description |
|---|---|
| Intraoral Anchorage | Anchor units are within the oral cavity - teeth, alveolar bone, palate, lingual surface of mandible (Nance button, transpalatal arch, lingual arch). |
| Extraoral Anchorage | Extends outside the mouth to structures like the cranium (occipital/parietal), facial bones, or cervical region. Example: headgear (cervical pull, occipital pull). |
| Muscular Anchorage | Uses the forces of perioral musculature as anchorage. Example: lip bumper, Frankel appliance. |
4. According to the Number of Anchorage Units
| Type | Description |
|---|---|
| Single (Primary) Anchorage | Only one tooth acts as the anchor. Offers the least resistance. |
| Compound Anchorage | Two or more teeth are joined together to act as a single anchorage unit, increasing total root surface area and resistance. |
| Multiple (Reinforced) Anchorage | Multiple teeth + additional means (e.g., extraoral traction, implants, palatal arch) are combined for maximum anchorage. |
5. According to the Amount of Contribution to Space Closure (Gianelly & Goldman's Terms - often covered in Gowri Shankar)
| Type | Description |
|---|---|
| Maximum Anchorage | Minimal or no movement of anchor teeth is desired. All extraction space should be used up by the active (anterior) unit. |
| Moderate Anchorage | Equal distribution of space closure between anterior and posterior units. |
| Minimum Anchorage | Maximum movement of posterior (anchor) teeth is desired/acceptable. |
Anchorage Value
The anchorage value of any tooth is roughly proportional to its root surface area (modified from Freeman DC's thesis). This is why molars provide much greater anchorage than incisors.
Sources of Anchorage
- Intraoral: Teeth, alveolar bone, hard palate (Nance button), lingual surface of mandible
- Extraoral: Cranium (occipital, parietal), cervical region, facial bones (via headgear)
- Muscular: Perioral musculature (lip bumper, functional appliances)
Reference: S. Gowri Shankar, Textbook of Orthodontics, 1st Edition - the standard classification referenced across orthodontic study presentations and board examinations.
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