The distribution of malocclusion using the index of orthodontic treatment needs at a university dental hospital in and around Pretoria, South Africa

: The study described the patterns of malocclusion traits and the orthodontic treatment needs at a Dental Hospital using the Index of Orthodontic Treatment Needs (IOTN), Dental Health Component (DHC). We evaluated 2079 pre-treatment study models and clinical records of orthodontic patients from the Department of Orthodontics waiting list. The assessment of malocclusion was measured according to the molar relationship using Angle's classification.The DHC was further used to assess the five malocclusion traits: - missing teeth, overjet, crossbite, displacement of contact point, and overbite, including open bite (MOCDO). The MOCDO score was calculated to determine the orthodontic treatment needed based on the DHC grades 1–5. The data was analysed using SPSS version 28 and the level of significance was set at p≤ 0.05.: The sample consisted of 59.3% (n=1232) females and 40.7% (n= 847) males. The mean age of the study sample was 14 years (SD±2.3) and ranged between 12 to 20 years. Angle's Class I malocclusion was found in 57.7% of the sample, followed by Class II (35.4%) and Class III (6.9%). The orthodontic treatment needs DHC grade were: 53% grade 4 (need for orthodontic treatment), 21% grade 5 (great need for orthodontic treatment), 17% grade 3 (borderline need for orthodontic treatment), 6% grade 2 (little need for orthodontic treatment), and 3% grade 1 (no orthodontic treatment need). A statistically significant difference was found in Angle Class I malocclusion and the DHC grades (p=0.001), as well as MOCDO variables and DHC grades (p=0.001).Angle's Class I malocclusion was the most predominant in our study sample compared to Class II and Class III malocclusions. The DHC of IOTN was successfully used to evaluate the severity of malocclusion with the majority of the sample in Grades 4 and 5, requiring mandatory orthodontic treatment. A high frequency of the occlusal traits included missing teeth, overjet, crossbite, displaced contacts and overbite. The results of our study showed that most patients on the orthodontic waiting list require mandatory orthodontic treatment. Therefore, it is recommended that DHC be used to place patients on the waiting list to prioritise orthodontic treatment.