Optimizing the analysis of dental enamel microstructure in intact teeth

Abstract

In most mammalian species enamel prisms are regularly arranged in layers of alternating directions forming an angle of approximately 90°. These successive layers of prisms are known as Hunter-Schreger bands (HSBs). The analysis of HSBs may provide valuable information regarding the species life history, taxon and personal identification, with evident applicability in physical anthropology and forensics. Obtaining good quality digital images of HSBs in intact specimens is not always a feasible task. The major problems are the low contrast of images; the reflection of incident light, which may create areas of intense shine in digital images; and the abrupt decrease in the degree of illumination that occurs after light crosses the vertical cracks, frequently present in enamel. We show here that the area of intense shine can be minimized by a polarizing filter coupled to the camera objective, and the filling of enamel cracks with corn oil can reduce refraction of light in enamel cracks. These procedures can significantly increase the quality and the area of HSBs that can be recorded in intact teeth.

Digital enhancement of dental enamel microstructure images from intact teeth

“…Twelve extracted teeth that were impregnated with corn oil for 5 min. This treatment significantly decreases the refraction of light in the crack that are frequent in enamel, improving the quality of images (Arrieta & Line, ).…”

“…Obtaining clear and sharp images of HSBs in intact teeth is not always possible. The low contrast between light and dark bands, which is observed in many specimens (Arrieta & Line, ; Holwerda et al, 1994; Line & Bergqvist, ), may impose serious difficulties in the analysis of HSBs. Additionally, the area closer to the light source (medial or distal surface of tooth) is usually overexposed while the contralateral surface is poorly illuminated.…”

Bandas de Hunter-Schreger: Propuesta Terminológica

“…El término BHS, describe a las bandas claro-oscuras presentes en el esmalte de un diente seccionado longitudinalmente al momento de incidir la luz en él, formadas por las secciones de los prismas, pudiendo invertirse al cambiar la dirección de la fuente de luz (Arrieta & Line, 2017). El nombre es en reconocimiento de los primeros investigadores acreditados con la observación de este curioso fenómeno; John Hunter, cirujano, anatomista, fisiólogo y patólogo Escocés (1728-1793) y Christian H.T.…”

“…Estructuras relevantes al momento de evaluar patrones de evolución, alimentación, y adaptación. El estudio del patrón de BHS, se considera escasamente explorado y con potencial de análisis (Arrieta & Line, 2017) en las disciplinas anteriormente mencionadas.…”

Segmentation of tooth enamel microstructure images using classical image processing and U-Net approaches

“…Some desirable characteristics of biometrics data are to be highly unique, easily obtainable, time-invariant (no significant changes over time), easily transmittable, non-intrusively acquirable and distinguishable by humans without special training [9]. Previous works show that a photograph of a tooth with side lighting enhances the HSB appearance [10] and the digital image of the HSB can be treated to highlight the bands [11]. The light and dark patterns formed by the HSB resembles fingerprints and also seems to be unique for each tooth and between individuals [8].…”