Hydroxyapatite, the natural mineral of teeth and bone, is used in toothpaste to rebuild enamel and as a calcium supplement. As toothpaste, it eases sensitivity and protects against new cavities about as well as fluoride (a match still open), without reported product-related side effects. A bone-derived supplement appears to slow bone loss slightly better than ordinary calcium; no study shows fewer fractures. Risks mirror calcium supplements; much research involved manufacturers. (Full Review)
| Marker | Target | Why |
|---|---|---|
| Dental caries assessment | No new cavities or progressing lesions | Tracks caries prevention |
| Tooth sensitivity score (0–10) | 0–2 | Tracks desensitizing effect |
| Serum calcium | 9.2–10.0 mg/dL | Detects calcium overload |
| Parathyroid hormone | 15–45 pg/mL | Reveals hidden hyperparathyroidism |
| 25-hydroxyvitamin D | 40–60 ng/mL | Governs calcium absorption |
| eGFR (kidney function) | Above 90 mL/min/1.73 m² | Kidney handling of calcium |
| 24-hour urinary calcium | Below 200 mg/day | Kidney-stone risk |
| Bone mineral density T-score | Above −1.0 | Tracks bone preservation |
| Blood lead | Below 1 µg/dL | Detects contamination exposure |
Cadence: Baseline before starting; sensitivity re-rated at 4 and 8 weeks; dental examinations every 6 months; supplement users repeat serum calcium and kidney function at 3 months, then every 12 months; bone density scans every 1–2 years