DENTAL CONDITIONS AMONG THE POLYNESIANS OF PUKAPUKA (DANGER ISLAND)

I. GENERAL BACKGROUND AND THE PREVALENCE OF MALOCCLUSION

¹ Department of Preventive Dentistry, University of Otago Dental School, Dunedin, New Zealand

1. A definite malocclusion was found in 168 (35.6 per cent) of 472 natives examined. The proportion affected was highest among youths and adults with permanent dentitions and lowest among young children with deciduous dentitions

2. Of the 168 with malocclusion, 93 were classified as Class I, 18 as Class II, and 57 as Class III.

3. When the incidence of malocclusion among Pukapukans was compared with that among white children from Wisconsin, the following differences were found to be statistically significant: (a) the incidence of malocclusion (all types) and of Class I and Class II malocclusion is lower in Pukapuka than in Wisconsin; (b) the incidence of Class III malocclusion is higher in Pukapuka than in Wisconsin.

4. There was no significant difference between the incidence of malocclusion in males and females.

5. Of the 221 subjects with third molars present, 99 (44.8 per cent) had one or more of these teeth either in poor occlusion or impacted. Thirty-one of these subjects had impacted third molars, all located in the mandible. Since no radiographs were taken, the actual incidence must be higher than this.

6. Men showed a higher incidence of impacted third molars than women. This difference was found to be significant at the 1 per cent level.

7. An index of tooth function was devised and used to determine the effect of function on third molar occlusion. It was concluded that function as measured had no significant influence on third molar occlusion.

8. A total of 12 supernumerary teeth were found in 10, or 2.1 per cent, of the 472 patients examined.

9. Twelve persons were found to have open bite; 7 of these were associated with a Class I malocclusion, 2 with a Class II malocclusion, and 3 with a Class III malocclusion.

10. Anterior overbite was comparatively uncommon; only 3 cases were recorded.

11. Posterior crossbite was found in 69 (14.6 per cent) of the 472 patients examined. There was no significant difference between the proportions of males and females affected.

12. Crowded anterior teeth were found in 16.52 per cent of individuals, a result almost identical with that found by Kirkpatrick at Manus Island.

13. Prolonged retention of deciduous teeth, premature loss of deciduous teeth, and abnormal habits were found to be contributing causes of malocclusion in only a very small proportion of cases.

14. In a consideration of familial traits, the data show the following tendencies: (a) children do not resemble one parent more than the other; and (b) a striking resemblance exists between children and parents when both parents have a normal occlusion or a normal relationship of the mandible to skull anatomy.

15. The relative effects of function and heredity on the incidence of malocclusion are discussed and it is concluded that function is not the main determining factor but that adequate function is important in that it controls whether or not a child will fulfill his inherited growth potential.