Phase 1/Interceptive Orthodontics

The American Association of Orthodontics recommends children have an evaluation by an orthodontist by the age of 7. Many children require the guidance of dental and facial development as a first phase of orthodontic treatment, commonly called Phase 1 or Interceptive Orthodontics. If indicated, this is typically attempted in the mixed dentition or very early in the permanent dentition. For crowding problems, some lost space can be regained using appliances to reposition teeth to their original positions. Attempts to regain space are usually limited to mild or moderate crowding, depending on a number of variables. In a case with very mild crowding, space regaining can be postponed until the patient is ready for comprehensive orthodontic treatment in the permanent dentition. Some patients have dramatic space shortages due to a general lack of space or space loss. If the crowding amounts to more than approximately 5 mm extraction of permanent teeth must be considered.

When the crowding approaches 10 mm per arch, serial extraction can be attempted if the molars are in a Class I relationship and the teeth present are in good health. The classic serial extraction procedure involves the extraction of the primary canines, which allows alignment of the incisors. The primary first molars then are extracted when the permanent first premolars have at least half of their root development. The permanent first premolars are thus encouraged to erupt before the permanent canines. Once erupted, the permanent first premolars are extracted to create space for the permanent canines. During serial extraction sequence, the patient must be monitored so as to avoid loss of space and ensure the teeth erupt in proper alignment. A form of space maintenance, such as a Lower Lingual Holding Arch or a Nance Holding Arch may be useful and prudent throughout this process.24

The correction of an anterior or posterior crossbite should also be done early on. Crossbites can be of a single tooth or many teeth. A single tooth anterior crossbite can occur due to trauma, a retained primary tooth or crowding. If enough space is present, it is relatively easy to correct. Any appliance that applies a force to the lingual surface of the tooth can be used. One effective appliance is an acrylic removable appliance with a finger spring. Another treatment option is limited bonding and banding of the affected and adjacent teeth. The upper and lower teeth may need to be disclosed while the crossbite is being actively corrected to avoid occlusal interferences. An anterior crossbite involving more than one tooth is typically indicative of more severe problems. In this case, a determination must be made if the patient initially contacts edge to edge and then slides the mandible forward into the crossbite at full closure, indicating a pseudo Class III malocclusion. Pseudo Class IIIs can be treated with orthodontics alone to correct the crossbite and slide. If there is no slide and the patient is in crossbite in centric relation, then the patient likely has a true skeletal Class III malocclusion, which should be confirmed with a lateral cephalometric radiograph and full records. A true Class III presents a more serious challenge that may require a functional appliance, orthodontics, and even orthognathic surgery in the future. Many of these also have a genetic component in which the Class III malocclusion also may present in one of the parents or siblings as well.

Posterior crossbites present with the buccal cusps of the maxillary teeth lingual to the buccal cusps of the mandibular teeth and can consist of a single tooth or multiple teeth. Whenever a posterior crossbite is present, one should examine for mandibular lateral shifts on closure. Other indications of mandibular lateral shifts are midline deviations without asymmetric crowding and facial asymmetries involving the chin. The severity of the crossbite should be evaluated with the patient in CR and treated to this position. Single-tooth crossbites are typically corrected with a crossbite elastic or with archwires in full orthodontic treatment. A W-arch or quad-helix appliance can be used to correct crossbites of multiple teeth in young children.

Posterior crossbites in the near adolescent or adolescent age groups are typically corrected using a rapid palatal expander (RPE) (Figure 26). Most RPEs consist of a midline screw, attached to bands on the permanent first molars with a heavy wire extending anteriorly along the lingual surfaces of the premolars and possibly the canines. The screw is typically activated once or twice per day by the patient using a key. Each turn expands the screw 0.25 mm, and the force produced causes opening of the midline palatal suture. The opening of the diastema between the central incisors is a common sequela of RPE use and is indicative of skeletal expansion of the suture area, although the overall result of using an RPE is a combination of skeletal and dental expansion. The maxillary suture fuses around age 14-15 and occurs in females typically before males. Once this suture fuses, expansion efforts result in mostly dental movements, indicated by buccal tipping of the crowns, lack of diastema opening, and an overall unstable outcome. Once the expansion is sufficient, RPEs should be stabilized with a stainless steel tie or with composite or acrylic to seal the key hole to prevent unturning and thus relapse. All expanders should be maintained for 3-6 months post-expansion for sutural healing and stability.

Figure 26.

Rapid or slow palatal expander

Rapid or slow palatal expander. (A) Prior to rapid palatal expansion (B) After expansion is complete. The expander is been tied off using a stainless steel tie to ensure the screw does not unturn during the 3-6 months of retention.

Early correction of skeletal disharmonies is a great challenge in orthodontics, with the most common being a skeletal Class II malocclusion. The goal of treatment in a skeletal Class II is to redirect the growth of the jaw contributing to the skeletal problem. Early headgear and functional appliance use can result in positive changes in the skeletal positions, but research shows the outcomes are the same if treated in the permanent or late mixed dentition when the patient is ready for full orthodontic treatment.25,26 Therefore, early treatment for Class II patients should be reserved for patients with psychosocial concerns, esthetic complaints, or increased risk of trauma to the maxillary incisors due to excess protrusion. Early treatment for Class III problems due to maxillary retrognathia can also be attempted using a facemask or bone anchored maxillary protraction using miniplates in the jaws. The most promising results using facemask are seen when begun prior to age 10. For Class III malocclusions due to mandibular protrusion, early treatment is not recommended.