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The Nature of Orthodontic Problems and Malocclusion Evolution of Orthodontics Angel’s Molar Classification The focus of modern orthodontic treatment is on improving not only dental and skeletal but also soft tissue aspects of orthodontic problems, in combination with other dental treatment as needed. Malocclusion • Any deviation from the ideal occlusal scheme Epidemiology of Malocclusion • Ideal occlusion as defined by Angle is a rare occurance • 65% of the US population present some type of malocclusion Crowding • Space required by the dentition for all teeth to be aligned normally exceeds the space available in the dental arch. • Rotations, incisor irregularity etc. What percentage of the population presents with severe crowding? • About 15-20% • Crowding increases with age • Is worst in the lower arch Overjet • Horizontal overlap of incisors • Approx 2mm is considered normal Malocclusion What is the prevalence of severe overjet ? (> 6mm) Malocclusion • 5 – 10% • Correlates with the prevalence of Class II malocclusion Malocclusion What is the prevalence of negative overjet? Malocclusion • Less than 1% in the US • Is a characteristic of Class III malocclusions • Much more prevalent in Japan and China Overbite • Overbite is the vertical overlap of incisors. • 1-2mm overbite is considered normal. • Excessive overbite is called deep bite • >5mm overbite is considered severed deep bite • Overbite <0mm is called an open bite Malocclusion Deep bites are more prevalent in which ethnic group? A. Black B. White Malocclusion • Open bites are more prevalent in blacks • Deep bites are more prevalent in whites Posterior Crossbite • Maxillary posterior teeth are lingually positioned to mandibular posterior teeth. • Discrepancy in the widths of maxillary and mandibular arches. • Can arise from dental causes as well How many patients in a typical US population have a posterior crossbite? About 10 % Is very similar between whites, blacks and hispanics Diastema • A space between two adjacent teeth is called a diastema. • Maxillary midline diastema is most commonly seen in mixed dentition phase Malocclusion • Which ethnic group has the higher prevalence of midline diastemas A. White B. Black C. Hispanic Malocclusion • Blacks have double the prevalence of anterior diastema compared to whites Assigned reading Contemporary Orthodontics: Chapter 1 Pg 3-22 Bhoomika Ahuja Department of Orthoodnitcs [email protected] Room 3213
