The aim of the study is to follow a group of preschool children from early permanent dentition to determine the prevalence and incidence of caries malocclusions and to investigated the related risk factors as age, gender, ethnic origin and non-nutritive sucking habits, breathing disturbances, allergies, Dietary habits, oral hygiene status and dental care.

Once a year a clinical examination were performed. Data were collected with a questionnaire, that was filled out by the parents before the clinical examination, which included questions on child's clinical history, the type of feeding, the use of baby-bottle, the history of non-nutritive sucking habits (dummy-sucking and digit sucking) and the consent to the clinical examination. Two World Health Organization (WHO) calibrated examiners carried out the clinical examinations. They were blinded to the information collected from the parental questionnaires. Dental examinations were performed in a classroom environment under natural light, using gloves and masks in compliance with the infection control protocol, mouth mirrors and disposable paper rulers to measure overjet and overbite (in millimeters). The occlusion was assessed in centric occlusion and was classified according to Foster and Hamilton criteria [Foster and Hamilton, 1969] Radiographic examination was not performed.

Inclusion Criteria:

• children born in 2008 and 2009 in Chiavari District (Italy)

Exclusion Criteria:

• parents' lack of consent
• absence at the date of the visit; no compliance
• orthodontic treatment; marked occlusal wear or early
• loss of primary teeth
• alterations in the number, size and shape of teeth
• syndromes or systemic problems affecting craniofacial growth
• cleft palate.

Children born in 2008 and 2009 in Chiavari District (Italy)