Introduction: An increase for oral health care uptakes in Tanzanian through current surge of health insurance establishments has placed adult individuals to seek for orthodontic care which was nonexistent at their adolescent age. However, prevalence of malocclusion and magnitude of orthodontic treatment needs not known in Tanzanian adults. This study aimed to survey on the prevalence of malocclusion and objective orthodontic treatment needs among the adult population in Tanzania. Study Design: Survey study.

Setting: Conducted at Kilimanjaro Christian Medical Centre Teaching Hospital, Moshi, Tanzania.

Period: January to April in 2014.

Subjects and methods: A population of 217 nursing student at Kilimanjaro Christian Medical Centre Teaching Hospital in Moshi, Tanzania were involved for clinical examination of malocclusion traits. The traits were registered according to the criteria developed by Bjork, Krebs and Solow in 1964. Dental Aesthetic Index (DAI) was used to determine orthodontic treatment needs in this group of Tanzanian adults. Data for malocclusion traits were analyzed using Statistical Package for Social Sciences. The Intraclass Correlation Coefficient (ICC) was used to determine intra-examiner reliability of the discrete variables of Bjork criteria and DAI components. ICC value classification was based on those developed by Landis and Koch in 1977. The intra-examiner reliability by ICC in our study was almost perfect (ICC=0.895-1.000).

Results: The overall prevalence of malocclusion was 94.4%. Angle’s Class II and Class III malocclusion occurred in 12.9% and 6.7% respectively of the studied population. Aplasia or impacted teeth excluding the last molar occurred in 8.4% of the students. Deep bites occurred in 7% and frontal open bites in 9.3% of the students studied respectively. Crowding in both jaws were found in almost half of the students with more crowding in mandibular incisors. Midline displacement was registered in 38.8% of the students. The populations mean DAI score was 27.7 (8.64 ±SD). About 51% of the students had either no need or slight orthodontic treatments. About 49% were found with orthodontic treatment needs ranging from elective, highly desirable to mandatory.

Conclusion: The current findings showed presence of malocclusion traits in this population with tendency for some of the traits to increase in severity compared to the findings in the adolescents studied previously in Tanzania. Higher overall prevalence of malocclusion according to Bjork criteria in this population corresponded with considerable orthodontic treatment needs assessed by DAI scores.