Green bone.

Objective: To describe the unusual finding of yellow-green-colored bone during routine orbital surgery, to detail its investigation, and to demonstrate its benign nature.

Methods: When green bone was found, specimens were sent for light and fluorescent microscopy, ultraviolet photography, and spectrophotometry.

Results: Yellow-green bone was encountered in 3 patients during orbital tumor excision or orbital fracture repair procedures. The only common cause was prior use of tetracycline during adolescence. All patients had healthy white dentition. In all cases, absence of neoplasia was demonstrated histologically. The bone fluoresced with a bright yellow-green color when exposed to 365-nm ultraviolet light. Histologic analysis demonstrated fluorescence located near the haversian canals. Spectrophotometry revealed absorption at 4 wavelengths specific to tetracycline: 230, 275, 380, and 440 nm.

Conclusions: Fixation of tetracycline and ensuing fluorescence occurs mostly in areas of new bone growth and mineralization. This happens during childhood but also with bone remodeling associated with tumors or fractures. Once mineralized, teeth should therefore not be affected if tetracycline exposure occurs after ages 8 to 10 years. This paucity of external clues can lead to the surprising but innocuous surgical finding of green bone. Careful history and proper investigation can confirm its origin.