Incisor inclination determined by the light reflection zone on the tooth's surface

Objective: Maxillary incisors are the most prominent teeth, and their inclination plays an important role in esthetics. In orthodontics, the inclination of central incisors is usually determined by cephalometric analysis. This publication suggests an adjunctive clinical measure to determine this inclination. The objective of the study was to examine the correlation between the inclinations of maxillary incisors measured on a cephalometric lateral headfilm and the light reflection zone appearing on the buccal surface of the teeth on anterior intraoral photographs. Method and Materials: Maxillary incisor inclination, divided into three levels-proclination, normal inclination, and retroclination-of 65 patients was determined by means of cephalometric analysis, using three angular measurements (maxillary incisor to sella-nasion, maxillary incisor to Frankfort horizontal, and maxillary incisor to nasion-point A). The anterior intraoral photographs of the 65 patients were divided into 3 groups according to the reflection zone on the maxillary central incisors as determined from the photographs: incisal, middle, and gingival. The correlation and agreement between the two parameters were evaluated by chi-square and kappa statistics. Results: The light reflection zone on the tooth surface as it appears on intraoral photographs- incisal, middle, or gingival-correlated with statistical significance to the angular inclination of the teeth-proclination, normal inclination, and retroclination, respectively-as determined by means of cephalometric analysis (P .001). Conclusion: Incisor inclination can be determined by not only cephalometric analysis but also the light reflection zone viewed on the buccal surface of intraoral photographs. This method might be used as a new screening tool and further as an additional clinical tool for assessing treatment plans in orthodontics and other fields of dentistry. Keywords: cephalometric analysis, incisor inclination, light reflection zone, orthodontics