In September 2014, cervical and thoracic OPLL were confirmed by a spine specialist on magnetic resonance imaging, and the patient was advised to undergo regular conservative observation. Serum zinc level was measured using atomic absorption spectrophotometry. Blood was collected using a disposable syringe, transferred to a dedicated plastic tube, and incubated under refrigeration. When measuring zinc concentration in serum, plastic test tubes with non-rubber stoppers were used to ensure accurate zinc data.
Before the administration of a zinc supplement, a mineral scan of the skin of the hand was performed in April 2017 [67 μg/mg tissue (normal range 125–155 μg/mg tissue); Oligoscan; Luxometrix-ipc-eu, Windhof, Luxembourg]. The patient was confirmed to have a low zinc concentration and was prescribed a zinc supplement (6–15 mg/day) orally, which was continued until 2019 at the time of periapical periodontitis eradication.
Given the patient’s condition, substantial amounts of zinc were needed before reconstruction of the ligament tissue. In patients with OPLL, other ligament tissues, such as the periodontal ligament, should be monitored. In 2019, when the patient’s periapical periodontitis had completely resolved (Fig. 5c), her serum zinc level remained at 64 mg/dL (normal 80–130 mg/dL). The patient’s serum was zinc deficient despite zinc administration. The results suggested that the patient had multiple ligament disorders and did not have sufficient zinc concentration for ligament tissue regeneration.
In addition, her serum CXCL7 level was 5.1 mg/dL (normal range 7.3–10.3 mg/dL), serum manganese level was < 0.01 mEq/L (normal range 0.6–1.2 mEq/L), serum calcium level was 8.5 mg/dL (normal range 8.6–10.4 mg/dL), serum chromium level was 0.57 μg/dL (normal range < 1.0 μg/dL), serum manganese level was 2.2 mg/dL (normal range 1.8–2.6 mg/dL), and serum selenium level was 14.1 μg/L (normal range 107–171 μg/L). Patients with OPLL generally have high serum glucose levels and a high incidence of combined diabetes mellitus . However, in the present case, the patient’s blood glucose level was normal.
Figures 2 and 5 show the root canal treatment progression during zinc administration in the present case. The patient underwent regular dental examinations. On conservative follow-up by an orthopedic surgeon, the patient did not report any limitations to daily work or life due to OPLL.