The Sweden Dental Center was established 1996, specializing in the treatment of periodontics and implants. It got its name from Dr. Hirooka's experience receiving advanced training in periodontology from Gothenburg University in Sweden. After graduating from dental school, he spent ten years practicing dentistry in Japan, then another five years studying periodontology (the study of gum disease and implantology) in Sweden. He also spent time investigating the effects of government programs on the prevention of tooth decay and other dental diseases.

Dr. Hirooka applied Sweden's advanced knowledge of dental care to Japan, sharing his findings in frequent lectures.