Orthodontic Indices: Concepts, Classification, and Clinical Applications: A Narrative Review

AbstractOrthodontic indices are standardized tools designed to quantify malocclusion, assess treatment need, determine treatment complexity, and evaluate treatment outcomes. They play a crucial role in clinical decision-making, epidemiological surveys, resource allocation, and quality assurance in orthodontics. Over the years, multiple indices have been developed, ranging from diagnostic classifications to epidemiologic, treatment priority, complexity, and outcome indices. This review provides a concise overview of the evolution, indications, advantages, and limitations of commonly used orthodontic indices, including Angle’s classification, Occlusal Index, Little’s Irregularity Index, Treatment Priority Index, Dental Aesthetic Index, Index of Orthodontic Treatment Need, and Index of Complexity, Outcome and Need. Recent advances, including the application of artificial intelligence, are also discussed.