Spacing of teeth
Birgit Thilander and Krister Bjerklin
- Median diastema
- Missing maxillary incisors
- Pathological migration of teeth
- Congenitally missing premolars
- Partial edentulous dentitions
- General spacing of teeth
- To be able to discuss treatment principles in patients with a median diastema
- To be able to describe treatment alternatives in patients with missing maxillary incisors
- To understand problems, associated with orthodontic treatment in patients, treated for periodontitis
- To understand the importance of multidisciplinary co-operation in treatment of patients with partial edentulous dentition
Excess of space in the dental arch is diagnosed as a generalised spacing or a local divergence, often observed in the maxillary anterior region, as a median diastema, traumatic loss of central incisors, or congenital absence of lateral incisors. Furthermore, spacing is observed in aging individuals, due to pathological migration of teeth caused by periodontitis. Finally, adult individuals with partial edentulous jaws demand pre-prosthetic orthodontic treatment from functional aspects. Thus, indication for orthodontic treatment in subjects with spacing of teeth exists for aesthetic reasons, but also for facilitating prosthetic restorations with optimal occlusal stability.
A maxillary diastema is common in early mixed dentition and can be regarded as a normal feature in connection with eruption of the central incisors. In most cases, there is a progressive reduction, especially at the eruption of the lateral incisors and the canines. In permanent dentition, the frequency is about 4% in a Swedish population (Thilander and Myrberg, 1973).
A hypertrophic labial frenulum (thick and/or attached to the gingival margin) has been debated as a causative factor or a consequence of a persistent diastema (Figure 7.1). It is not in itself a hindrance to spontaneous closure of the diastema, but excision hastens the spontaneous closure, especially in the ‘divergent type’. The frenotomy should be performed before the eruption of the lateral incisors in order to create enough space for them in the dental arch. However, in cases with ‘parallel’ central incisors or generalised spacing, as well as in adolescents, spontaneous closure should not be expected (Figure 7.1). Such cases need appliance therapy.
Before orthodontic closure of the diastema, it is important to verify by radiographs that no obstacles (e.g. mesiodens, odontoma) exist between the central incisors, and if occurring, they should be removed. Maxillary median diastemas are relatively simple to close with fixed appliances, which at the same time ensure adequate root paralleling and correct torque of the incisors. Tipping of the teeth with removable appliances should normally be avoided, since the roots may be left diverging, which commonly results in space reopening.
Adult patients frequently demand a closure of the anterior diastema for aesthetic reasons. The treatment principles in general are the same as for adolescents. However, in adults, compromise solutions can be chosen. Median diastema closure is relatively simple if the overjet will allow a palatally shift of the incisors (Figure 7.2). If an overjet reduction is impossible, the teeth must be moved into ideally separated positions and the crowns built up with porcelain veneers or composite resins. Diastema closure needs bodily movements to avoid tipping, while fixed appliances must be used to control both crown and root positions. Due to the risk of relapse, retention appliances must be used for a long time, and in some cases even require permanent retention.
Missing teeth, because of trauma or congenital absence, generally affect the maxillary anterior region. Aesthetic improvement is the real desire of the patient. Treatment solutions include orthodontic space closure, auto-transplantation or prosthetic replacement (bonded or fixed dental bridges, or implant-supported crowns). All alternatives have their advantages as well as disadvantages and proper decisions should be made already in young ages. A comprehensive treatment plan often implies a compromise in the individual case, and should be discussed in a multidisciplinary team. Then, the patient and his/her parents should be thoroughly informed of each step of the total treatment procedure.
Missing maxillary central incisors are usually caused by a traumatic injury. The immediate measure, following the trauma, is descried in some textbooks (Andreasen, 1992), while this present chapter focuses on the orthodontic problem.
Space closure by moving a tooth through the mid-palatal suture has shown to be unsuccessful in an experimental study in beagle dogs (Follin et al., 1984). Hence, the gap should be closed from both sides, resulting in three incisors. It is, however, important to correct the axial inclination and mesio-distal position when a lateral incisor is used to replace a central one. Some patients may accept such an alternative, if the incisors are of the same size and their axial inclination has been corrected.
Autotransplantation of a premolar to this area in young patients with an optimal stage of three-quarters root development (Slagsvold and Bjercke, 1978) has shown good long-term results (Czochrowska et al., 2002; Kvint et al., 2010) (Figure 7.3). Replacement by a single tooth implant-supported crown is usually the alternative in young adults, thus leaving the adjacent teeth intact. However, in some cases, a fixed dental prosthesis is another alternative in adult patients. Resin-retained construction, serving as a space maintainer during the dental development while awaiting the final treatment decision, is the best alternative in young and adolescent individuals.