Summary Background Severe malocclusions appear in up to 20 per cent of the population. Many neuropsychiatric diseases are likely to have a neurodevelopmental, partially genetic background with their origins as early as fetal life. However, the possible relationship between neurodevelopmental disorders and severe malocclusions is unclear. The aim of this study was in a population-based setting (270 000 inhabitants) to investigate whether patients with severe malocclusions have more mental and behavioural disorders and growth or speech problems than controls without severe malocclusion. Material and Methods The study group consisted of patients from the Espoo Health Care Center, Finland, born in year 2000, who were retrospectively screened for their medical and dental records, including their possible mental and behavioural disorders (i.e. attention deficit hyperactivity disorder, Asperger’s syndrome, autism, mood disorder, or broadly defined behavioural abnormalities, learning problems, mental disorders, sleep disturbances, anxiety symptoms, depressive symptoms, and eating-related symptoms) and their need of orthodontic treatment according to the Treatment Priority Index (TPI). The study group consisted of a severe malocclusion group (n =1008; TPI 8–10) and a control group (n = 1068) with no severe malocclusion (TPI 0–7). Results Patients with severe mandibular retrognatia (P < 0.000), lip incompetence (P = 0.006), or neurodevelopmental disorders (mental and behavioural; P = 0.002) were found to have significantly more speech problems than the controls. The patients with severe malocclusions were leaner, that is, body mass index (kg/m2) <17, underweight; 17–25, normal weight; >25, overweight) than controls (P = 0.003), and underweight patients had a significant association with retrognathic maxilla (P < 0.000) compared to normal or overweight patients. No significant relationship between neurodevelopmental disorders and severe malocclusions, that is, retrognatia of maxilla, hypodontia, and severe dental crowding was observed. Conclusion Our results indicate that patients with severe mandibular retrognatia, lip incompetence, or neurodevelopmental disorders were found to have significantly more speech problems than controls. During orthodontic treatment of patients with severe malocclusion, special attention should be paid to patients with severe mandibular retrognatia, lip incompetence, and speech problems to detect signs of possible neurodevelopmental disorders and record if potential follow-up measures are in place.

This follow-up of the oral health of children and young adults in Espoo, Finland, has been carried out using annual check-ups done by dentists at the Espoo Health Center. There was about 80% participation in municipal dental care by 3- to 18-yr-olds. Each age group included 1700-2300 individuals. The DMFT-index for 12-yr-olds was 6.9 initially and only 2.2 at the end of the 12-yr follow-up. The reduced DMFT and increased number of clinically caries free children is probably the cumulative effect of various preventive measures adopted during the follow-up period. The proportional influence of each procedure is unknown.

An annual check-up was made in groups of 12- and 16-yr-old children by dentists of the Public Health Center of Espoo. The D index was used instead of DMFT index, because it expresses the need for conservative treatment. This information, again, is essential for planning public dental care. The children were divided into four groups according to the number of decayed teeth developed during a period of approximately 1 yr. Children with D = 0 were classified as healthy, D = 1 as low, D = 2 as moderate, and D = 3 or more as high caries incidence. In 1980 the percentage of the group D = 0 was about 52% in the 12-yr-olds. In 1988 the percentage had increased up to about 73%. The corresponding figures of the 16-yr-olds were 33% and 62%. Simultaneously, the high caries incidence groups had decreased in 12-yr-olds from 13% in 1980 to 5% in 1988 and in 16-yr-olds from 31% to 10%. These observations emphasize the need for retargeting prevention of caries in order to provide additional preventive treatment to the high incidence groups while the routine prophylaxis given to the other groups may be decreased.