An Overview of Selected Orthodontic Treatment Need Indices

Dentistry is unique in utilizing objective indices to measure the deviation of oral health components from ideal. Examples include various plaque, caries experience, tooth wear and periodontal indices (Quigley & Hein, 1962; Silness & Löe, 1964; Acharya, 2006; Hooper et al., 2004; Ainamo et al., 1982; Croxson, 1984). However, objective assessment of malocclusion has been different since malocclusion is a developmental condition and deviation from normal. Malocclusion is not an acute condition, and therefore, treatment of malocclusion has been associated with a great degree of subjectivity and distorted perceptions of treatment need. The main traditional reasons to justify providing orthodontic treatment are (I) improvement in the functioning of the dentition, (II) improvement in oral or dental health and (III) improvement in facial or dental aesthetic. In the era of evidencebased orthodontics; however, it is hard to justify the treatment based on improvement in oral or dental health for the majority of orthodontic patients (Burden, 2007; Bollen, 2008). Occlusal indices were used initially as epidemiological tools to rank or classify the occlusion. A large number of occlusal indices started to appear in the 1950s and 1960s to assist epidemiological studies. The orthodontic treatment need index is a form of occlusal index used to prioritize the need for treatment. Their use minimizes the subjectivity related to the diagnosis, outcome and complexity assessment of orthodontic treatment. A well-developed occlusal index should be reliable (indicate reproducibility) and valid. Validity means whether an index measures what it claims to measure (e.g. determination of treatment need) (Carlos, 1970). Indices should be able to identify people not needing treatment (specificity) and those in need of treatment (sensitivity). An index should be quick and easy to use, acceptable to cultural norms, and finally be adaptable to available resources. Dr William Shaw and co-workers divided occlusal indices into five different categories (Shaw et al., 1995). These are the diagnostic, epidemiologic, orthodontic treatment need, treatment outcome, and Orthodontic treatment complexity indices (Table 1). The purpose of this chapter is to provide an overview on the most commonly used American and European orthodontic treatment need indices. The modifications, advantages, and limitations of these orthodontic treatment need indices are discussed briefly.