The process of pulling a tooth down with a chain, formally known as surgical exposure and bonding with orthodontic traction, is a specialized procedure used to bring an impacted tooth into the dental arch. This technique is most commonly applied to the maxillary canine (eyetooth), which is the second most likely tooth to become impacted after the wisdom teeth. The canine’s complex developmental path can sometimes result in it getting stuck in the jawbone or soft tissue, preventing natural eruption. A combined surgical and orthodontic effort is then necessary to guide the embedded tooth into its correct position.
The Initial Phase: Surgical Exposure and Chain Placement
The treatment begins with a minor surgical procedure performed by an oral surgeon to gain access to the impacted tooth. This step, known as surgical exposure, is performed after the orthodontist has created sufficient space in the dental arch. The surgeon makes an incision in the gum tissue, often lifting a flap, to expose the crown of the buried tooth.
If the tooth is covered by bone, removal of bone tissue (ostectomy) may be necessary to fully expose the enamel surface. Once visible, a specialized orthodontic attachment, typically a small bracket with an attached chain or ligature wire, is bonded directly onto the tooth’s crown.
After the bracket and chain are secured, the gum tissue is repositioned and sutured back into place, leaving the end of the chain visible in the mouth. This chain is connected to the main orthodontic archwire on the surrounding teeth. The orthodontist uses the chain to apply a continuous pulling force, which begins coaxing the tooth out of the bone and into the arch. This setup provides controlled, slow traction to minimize trauma to the tooth and surrounding structures.
Timeline for Active Movement
The active phase of moving an impacted tooth from its buried location into the dental arch is a slow process that typically spans several months to over a year. The total time for the forced eruption phase, measured from the first application of force until the tooth is level with adjacent teeth, commonly ranges from six months to a year. Studies have reported the average duration for this traction phase around 13.0 months.
The rate of movement is slow to promote biological bone remodeling and prevent damage to the tooth root or surrounding teeth. An expected rate of movement for an impacted canine is between 0.5 to 1.5 millimeters per month. This movement occurs in two phases: an initial, slower phase through the dense jawbone, and a final, potentially faster phase once the crown emerges through the softer gum tissue.
Research shows that the average forced-eruption time for palatally impacted canines can be around 21 months using conventional techniques, though newer methods may reduce this time. Once the tooth crown reaches the level of the archwire, the chain is removed, and a standard bracket is placed on the tooth. This allows the orthodontist to complete the final alignment and rotation within the dental arch, which is separate from the forced eruption time.
Key Variables Influencing Treatment Duration
The variation in treatment time is due to several biological and positional factors that influence how quickly the tooth can move. A primary variable is the depth of impaction, measured by the distance the tooth’s cusp tip is from the chewing surface of adjacent teeth. A greater distance means the tooth has a longer path to travel, directly increasing the treatment duration.
The angulation and location of the impacted tooth within the jawbone also influence the timeline. Teeth positioned horizontally or angled severely often require more complex movements and more time compared to those in a vertical orientation. Patient age is another factor, as younger patients typically have less dense bone and a higher metabolic rate, which facilitates faster tooth movement than in older adults.
Complications can extend or halt the timeline, most notably the presence of ankylosis. Ankylosis is a condition where the tooth root has fused directly to the surrounding jawbone, making orthodontic movement impossible and often leading to treatment failure. Other factors, such as the tooth’s rotation, the status of its root formation, and the presence of surrounding dental abnormalities, are considered when estimating the overall treatment length.