The patient in Fig. 11.7 had a maxillary midline diastema in mixed dentition. She was complaining about the unpleasant appearance of the spacings and irregularities. Although the physiological process was explained, she preferred not to wait for the eruption of the canines for psychological reasons. A removable appliance with finger springs was used to close the median diastema. Once the median diastema is closed, the finger spring on the left lateral incisor will be activated. Although the left lateral incisor’s medial movement is indicated, the right lateral incisor’s mesial tipping is contraindicated because the cusps of the erupting canines are in close proximity with the roots of the lateral incisors at the early stages of dental development. Tipping the mesially inclined crowns of the lateral incisors in the ugly duckling stage will result in distal movement of the roots into the eruption path of the developing canines; thus, early orthodontic treatment may create risk of root resorption or canine impaction. Bishara [6] suggested to begin orthodontics after the cusp tips of the erupting canines have passed the apical third of the root of the lateral incisors. Therefore, orthodontic intervention should be avoided in the early mixed dentition period. The exceptions are midline diastema larger than 4 mm which may complicate eruption of the lateral incisors, presence of a midline pathology (mesiodens, odontome etc.) or bad oral habits.

A 12-year-old boy, at the end of mixed dentition stage, presented with proclined maxillary and mandibular incisors and generalised spacings (Fig. 11.8a–d). Although the maxillary canines had not fully erupted, the tooth-arch dimension analysis (Hays Nance analysis, see Chap. 8) revealed excess spacing at permanent dentition. The maxillary and mandibular spacings were closed using fixed orthodontic appliances with elastic chains and a consolidation arch aiming to control root divergence and torque (Fig. 11.8e–g).

An 11-year-old female patient presented with generalised maxillary spacing of 7 mm (Fig. 11.9a, b). Her history revealed that she was sucking her lower lip in her sleep throughout the night (Fig. 11.9c). Lower lip sucking habit caused proclination of the maxillary incisors which could not have been opposed by the forces of the upper lip. The aim was to normalise the extraoral muscle force and establish the equilibrium. A lip bumper appliance was used to break the sucking habit (Fig. 11.9d). This prefabricated appliance was placed at the level of the gingiva 2–3 mm in front of the lower incisors and 4–5 mm away from the buccal segments and was fixed to the molar tubes. It was reactivated when necessary. After 3 months of lip bumper therapy (full-time wear), the lower lip sucking habit was stopped, maxillary incisors spontaneously retroclined due to elimination of increased forces generated by sucking, and thus, maxillary diastemas were reduced (Fig. 11.9e, f). The residual diastemas were closed with fixed orthodontic therapy (Fig. 11.9g, h).

A female patient in early transitional dentition having a finger sucking habit showed increased overjet, labial inclination of the incisors and maxillary spacing (beyond physiologic diastema of mixed dentition) particularly on the right side where she inserted her right finger to suck (Fig. 11.10a–d). A myofunctional appliance was used for 3 months (only at night) to stop finger sucking habit (Fig. 11.10e). This soft appliance with vestibular screens broke the finger sucking habit and thus eliminated the abnormal pressure caused by the finger sucking and established a balance between intraoral and extraoral muscles. In addition, it generated palatally directed forces to the overproclined right maxillary incisors. The final result was decreased maxillary spacing. At the end of myofunctional therapy, the maxillary spacing was reduced but not totally eliminated (ideal for a transitional period, see Chap. 2), and the overproclined incisors and the increased overjet were corrected (Fig. 11.10f–h).