Proposed parameters of optimal central incisor positioning in orthodontic treatment planning: A systematic review

Objective: Planning of incisal position is crucial for optimal orthodontic treatment outcomes due to its consequences on facial esthetics and occlusion. A systematic summary of the proposed parameters is presented. Methods: Studies on Google Scholar (c), PubMed (c), and Cochrane Library, providing quantitative information on optimal central incisor position were included. Results: Upper incisors supero-inferior position (4-5 mm to upper lip, 67-73 mm to axial plane through pupils), antero-posterior position (3-4 mm to Nasion-A, 3-6 mm to A-Pogonion, 9-12 mm to true vertical line, 5 mm to A-projection, 9-10 mm to coronal plane through pupils), bucco-lingual angulation (4-7 degrees to occlusal plane perpendicular on models, 20-22 degrees to Nasion-A, 57-58 degrees to upper occlusal plane, 16-20 degrees to coronal plane through pupils, 108-110 degrees to anterior-posterior nasal spine), mesio-distal angulation (5 degrees to occlusal plane perpendicular on models). Lower incisors supero-inferior position (41-48 mm to soft-tissue mandibular plane), antero-posterior position (3-4 mm to Nasion-B, 1-3 mm to A-Pogonion, 12-15 mm to true vertical line, 6-8 mm to coronal plane through pupils), bucco-lingual angulation (1-4 degrees to occlusal plane perpendicular on models, 87-94 degrees to mandibular plane, 68 degrees to Frankfurt plane, 22-25 degrees to Nasion-B, 105 degrees to occlusal plane, 64 degrees to lower occlusal plane, 21 degrees to A-Pogonion), mesiodistal angulation (2 degrees to occlusal plane perpendicular on models). Conclusions: Although these findings can provide clinical guideline, they derive from heterogeneous studies in terms of subject characteristics and reference methods. Therefore, the optimal incisal position remains debatable.