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root and is ready for eruption. The appropriate treatment here is to extract the deciduous and supernumerary teeth and hope that this will encourage eruption of the permanent incisor. In many scenarios, spontaneous eruption may be expected even with a closed apex, provided there is adequate space in the dental arch and little or no displacement of the impacted tooth [15, 16].

      As we shall see in subsequent chapters, there are several situations and tooth types where spontaneous eruption may not occur, or may not occur in a reasonable time‐frame. This will be so in the case of severe displacement of the affected tooth. In these instances, it may be necessary to supplement the natural eruptive potential of the tooth and divert it mechanically, with the use of an orthodontic appliance.

Photos depict (a) chance finding of mesiodens in a 4-year-old child. (b) Chance finding of odontoma in a 1-year-old infant. Photo depcits an 8-year-old child exhibits an unerupted maxillary left central incisor with two supernumerary teeth superimposed, pointing in opposite directions.

      Angle’s class II malocclusion is to be found in 20–25% of the child population in most countries of the Western world [17, 18]. However, this is not reflected in an orthodontic practitioner’s office, where one finds that up to 75% of patients are being treated for this malocclusion. The reason for this incongruity in seeking treatment is entirely facial appearance, since the visible manifestation of the condition causes the patient’s appearance to be adversely affected to a much greater extent than by most other conditions. In other words, appearance plays an extremely large part in the initiative and motivation of the parent to seek treatment for the child and for the child to be ready to be treated.

      Most of the other patients on the orthodontist’s roster are being treated for additional (though arguably less unsightly) conditions (such as crowding, single ectopic teeth, open bites or class III relationships). It follows that relatively few patients with acceptable appearance have been referred for strictly health reasons, which may not normally be apparent to the patient. This small number of patients will have agreed to orthodontic treatment only after being motivated by the careful and persuasive explanations of a general or paediatric dentist, orthodontist, periodontist, prosthodontist or oral surgeon, who will have warned them of the ills that are otherwise likely to befall them and their dentition.

      Aside from maxillary central incisors, most impactions are symptomless and do not usually present an obviously abnormal appearance. The natural result is that motivation for treatment in symptom‐less cases is minimal and much time has to be spent in explanations to patients before they accept that treatment is appropriate and before they are prepared to accept the constraints entailed in its execution.

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      11 11. Gràhnen H. Hypodontia in the permanent dentition. A clinical and genetic investigation. Odontol Revy 1956; 79 (Suppl 3): 1–100.

      12 12. Alvesalo L, Portin P. The inheritance pattern of missing, peg‐shaped and strongly mesio‐distally reduced upper lateral incisors. Acta Odontol Scand 1969; 27: 563–575.

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      14 14. Shafer WG, Hine MK, Levy BM. A Textbook of Oral Pathology, 4th edn. Philadelphia, PA: WB Saunders, 1983.

      15 15. DiBiase DD. The effects of variations in tooth morphology and position on eruption. Dent Pract Dent Rec 1971; 22: 95–108.

      16 16. Mitchell L, Bennett TG. Supernumerary teeth causing delayed eruption – a retrospective study. Br J Orthod 1992; 19: 41–46.

      17 17. Brin I, Becker A, Shalhav M. Position of the maxillary permanent canine in relation to anomalous or missing lateral incisors: a population study. Eur J Orthod 1986; 8: 12–16.

      18 18. Massler M, Frankel JM. Prevalence of malocclusion in children aged 14–18 yrs. Am J Orthod 1951; 37: 751–760.

       Adrian Becker

        The anchor unit

        Attachments

        Intermediaries/connectors

        Elastic ties and modules versus auxiliary springs

        Temporary anchorage devices

       

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