Malocclusion and traumatic dental injuries in relation to over-jet and lip posture in 12-15 year old in Nairobi
Aim: To determine the prevalence and pattern of occurrence of malocclusion and traumatic injuries to permanent anterior teeth and establish any association between traumatic injuries, over-jet and lip posture. Design: This was a descriptive cross-sectional survey. Setting: The study was carried out in public primary schools in the City of Nairobi, Kenya over a period of three months. Subjects and methods: A sample of 1382 boys and girls aged 12-15 years was obtained by multi-stage random sampling of children in 8 divisions, then 16 zones, then schools were interviewed. Registration for malocclusion was done using the Dental Aesthetic Index (DAI) and tae variables sought included missing teeth, crowding, over-jet and antero-posterior molar relations. Two hundred and twenty two children with history of traumatic dental injuries were identified. A structured questionnaire was used to obtain information on the trauma, symptoms associated, cause, site of trauma and if any treatment was sought. The data was collected by clinical examination of permanent anterior teeth of the children based on a modification of the WHO criteria with some variables sought including: number of teeth injured, type of teeth injured, classification of the trauma and type of treatment if any. Data was analysed aided by computer using the Statistical Package for Social Sciences (SPSS) programme. Chi-square and odds ratios statistical tests were done to determine the differences in malocclusion and trauma experience between males and females and the difference in trauma experience by different overjet groupings and lip posture. Student's t-test was used to determine difference in mean overjet between Xll children who had sustained traumatic dental injuries and those who had not. A p value of less than 0.05 was considered significant. Results: Seven hundred and thirty two (53.0%) of the children examined had either no abnormality or only minor malocclusion, 318(23%) had definite malocclusion, 176(12.7%) and 156(11.3%) had severe malocclusion and very severe or handicapping malocclusion respectively. The mean OAI was 26.6. Prevalence and severity of malocclusion for male and female children did not differ significantly (p=0.139). The prevalence of TOls was 16.1%. Males had experienced a significantly higher prevalence of trauma (18.8%) than females (13.5%) p=0.008. Amongst the male children, falls were the leading cause of TOls (37.3%). Approximately half (44.8%) of the females did not remember the • cause of injury while 31(36.5%) had sustained TOls due to falls. One hundred and seventy two (77.5%) children who had experienced TOls had no symptoms associated with the traumatized teeth. Ninety six (43.2%) of the children were injured while in the home environment. The maxillary central incisors were the most commonly traumatized teeth accounting for 220(73.5%) out of 299 injured teeth. The most frequently observed type of dental trauma was enamel fracture 206(68.9%) followed by enamel-dentin fracture 71(23.8%). Two hundred (90%) children had not sought treatment for TOls. When frequency of TOls in the children was related to overjet, it was found that out of the 886 children with overjet of 0-3 mm 104(11.8%) had experienced TOls. Out of the 502 children with overjet greater than 3 mm, 118 (23.5%) were found to have TOI. The prevalence of TOls in children with overjet greater than 3 mm was significantly higher than that in children with overjet of 3 mm and less (p=O.OOO).A significantly higher prevalence of TOls was found when children with incompetent lips 124(55.9%) were compared to those with competent lips 98(44.1%), (p=O.OOO). Conclusion: There was an overall high prevalence of malocclusion among the children with no significant gender difference for most of the traits. The OAI criteria produced a mean OAI score of 26.6, with 11.3% of subjects exhibiting handicapping malocclusion. Overall traumatized permanent incisors were found to occur fairly frequently with 68.9% of the injured teeth having sustained enamel injuries. A very high proportion of traumatized teeth were untreated. Male gender, overjet greater than 3 mm and incompetent lips were found to be statistically significant risk factors for traumatic dental injuries. Recommendation: Facilities and personnel should be put in place so that children with very severe or handicapping malocclusion can benefit from subsidized orthodontic therapy by specialists. There is need to improve oral health policies in Kenya so as to incorporate periodic checks ups in order to promptly diagnose and give advice on treatment of TOIs. The high proportion of untreated dental trauma among the children calls for improvement in children, parents and teacher education.