The butterfly effect: an investigation of sectioned roots

The butterfly effect is an optical phenomenon seen in some sections of tooth roots. The aim of this work was to investigate the density of dentinal tubules in mesiodistal and buccolingual cross-sections of roots exhibiting the butterfly effect and to determine if the effect is featured throughout the length of roots and is age related.

Thirty extracted single-rooted teeth were allocated to the following groups according to patient age: group 1: 15-24 years, group 2: 25-44 years, and group 3: 45 years and over. The teeth were decoronated, and their roots were embedded in acrylic and cut into ten 1 mm-thick cross-sections. Sections were viewed under a light microscope and coded (1 or 2) according to presence or absence of the butterfly effect. A root scored 20 when all levels exhibited the butterfly appearance. The 2 teeth with the highest score from each group and 2 control teeth with the minimum score (of 10) were selected. Two adjacent, consecutive cross-sections were chosen with the most coronal cut mesiodistally and the other buccolingually. Scanning electron micrographs (×850) were taken of the central portion of their canal lumina and the density of the dentinal tubules determined.

The butterfly effect was found at all levels in the roots of the affected teeth. The tubule density was highest in the buccolingual root sections (45,348 mm(-2)) and lowest mesiodistally (12,605 mm(-2)), a significant difference (P = .02). This trend was found across all age groups.

Root sections with the butterfly effect have a lower density of dentinal tubules mesiodistally corresponding to the wings of the butterfly. The pattern was observed in teeth from all age groups and was absent in controls.