Preventative orthodontics focuses on the elimination of factors, which if left uncorrected, would result in a worsening of the malocclusion. One example would be space maintenance due to premature loss of deciduous teeth, most commonly the canines and molars. Maintaining space is primarily indicated when permanent tooth eruption will not occur for another six months or more. Depending on the clinical situation, several techniques can be used to maintain space. Early exfoliation of canines or the deciduous molars might be an indication of ectopic eruption patterns or severe crowding and should be carefully evaluated along with the space maintenance. Another example of preventative orthodontics would be habit cessation due to a finger habit or tongue thrust.
Band and Loop Space Maintainer
This appliance is typically used to maintain space when a single primary first or second molar is lost unilaterally. It consists of a band and a wire loop to maintain the space (Figure 22). It can be used in either the maxillary or mandibular arch. If the primary second molar is lost before eruption of the permanent first molar, space maintenance is uniquely accomplished by the distal shoe, which helps to guide eruption of the first permanent molar and maintain space for the second premolar.
Band and loop space maintainer.
Lower Lingual Holding Arch
This appliance is used in the mandibular arch when bilateral space maintenance is required after loss of deciduous canines or molars. It is typically soldered to bands on the first permanent molars (Figure 23). Anteriorly, the wire rests on the lingual surfaces of the incisors. In the case of early loss of a deciduous canine, a wire spur can be soldered distal to the lateral incisor to prevent drifting of the midline. If in doubt about whether to use a Lower Lingual Holding Arch, it is usually best to put one in as there are few to no negative side effects and the potential benefits are great.
Lingual arch space maintainer.
Nance Holding Arch and Transpalatal Arch
The Nance Holding Arch is used in the maxilla to maintain space (Figure 24). The wire in this appliance is attached to permanent first molar bands and extends to the anterior palate. An acrylic button along the anterior palate provides resistance to anterior drifting of the molars. The appliance is tolerated well, but soft tissue irritation can be a problem.
Nance space maintainer.
Alternatively, some practitioners use a Transpalatal Arch (TPA) for the same purpose. A TPA consists of a rigid wire traversing the palate from one molar to the other with an omega loop in the center. By maintaining the transverse, the TPA maintains the molars in their A-P position as they cannot drift to a narrower part of the arch due to the cortical plate. The TPA is less irritating and easier to keep clean, but some question whether its general concept of space maintenance holds true. In cases where space maintenance is critical, the Nance Holding Arch may be a more reliable option.
Tongue Crib and Tongue Rake
Finger and tongue thrusting habits have the potential to have serious consequences if they continue after the permanent teeth erupt. They can result in open bites and narrowing of the maxillary arch, which left untreated for long periods can result in skeletal changes and require complex orthodontic and possibly surgical intervention. The use of a tongue crib or tongue rake to aid in cessation of the habit early on and correct of the malocclusion can be a simple treatment modality. These appliances consist of bands on the permanent maxillary first molars with soldered wires extending anteriorly. From these wires in the anterior, the crib or rake appliance extends down vertically to the linguo-gingival portion of the lower incisors. The crib serves to keep the tongue out of the interincisal area and as a reminder to the patient to keep their finger out of the mouth. The rake is a sharper appliance that serves as a harsher reminder. When used properly, the bite often closes spontaneously over a period of 6-9 months with good stability if the habit is truly broken. It is important to note that in order to break the habit properly, the patient has to truly understand the problem and want to break the habit. If the habit has been ongoing for a long time, with overeruption of the molars, resulting in excess vertical dimension, and a posterior crossbite, it would be best to refer the patient to an orthodontist for more comprehensive treatment.
Lingual rake used to break a thumb habit.