Ortho Procedures - Anchorage

Anchorage is a method of resisting the movement of one or more teeth through various techniques. Anchorage is important within the orthodontics as it is commonly used in the correction of malocclusions. The unintended movement of the teeth can negatively impact a treatment plan. Through the use of anchorage, the prevention of tooth movement is critical. Anchorage can be used on many different areas including on teeth, bone and implants.

Specific factors associated with the anatomy of teeth can impact the specific type of anchorage which will be used. Multi-rooted, longer-rooted and triangularly shaped root teeth typically provide more anchorage compared to single-rooted, short-rooted and ovoid rooted teeth.

History

An early use of anchorage was from Henry Albert Baker when he used the intermaxillary anchorage or Baker's Anchorage. This type of anchorage device uses elastic attached from one jaw to the other. They are typically in the form of either Class 2 elastics which are used to move the upper teeth back when the lower molar teeth serve as an anchor. This can also include Class 3 elastics which are used to move the lower teeth back in the case when the upper molars serve as an anchor. Intramaxillary anchorage can also be used in the form of an E-chain. In an E-chain anchorage, elastics are attached to the back molar teeth and connected to the front teeth in the same jaw in order to move teeth back of the mouth.

Site Classifications

1. Intraoral: A type of anchorage that is established within the mouth. This form involves both primary and compound anchorage.

2. Extraoral: A type of anchorage which is established outside of the mouth. This anchorage involves the use of headgear and/or face masks. One of the downsides of using an extraoral anchorage is that the anchorage is far from the site of the tooth itself. Additionally, when patients wear orthodontic headgear, adolescent patients have a lower compliance. Though there is typically a high success rate with using headgear for pre-teenage patients. The patient will wear the appliance for a shorter amount of time. As a result, less effects are seen. Numerous studies have proven that headgear is useful in providing anchorage during the movement of teeth.

Orthodontic headgear often consists of three main components to move the teeth:

• Occipital: Uses the occipital bone and the surrounding area
• Cervical: Uses the neck and surrounding area
• Combination: Uses a combination of both the occipital and cervical bones

Robert Moyers classified anchorage based on the number of units that were impacted.

• Simple/primary: Anchorage involving one tooth
• Compound: Anchorage involving two or more teeth
• Reinforced: Anchorage which uses additional teeth or other appliances to assist the primary anchorage. This can involve an extraoral or muscular anchorage. A reinforced anchorage based on additional appliances can include the following;
• Transpalatal Arch
• Nance Appliance
• Lower Lingual Holding Arch
• Reciprocal: Anchorage used when two units of teeth move towards each other with an equal distance.
• Stationary: Anchorage used when the teeth move in a translation manner and are not tipping.