Cnidium and Rehmannia Powder

The 黃 in the name is 生乾地黃, rehmannia, not rhubarb — the formula is the 川芎-and-地黃 pair with angelica and peony, which is 四物湯 with prepared rehmannia swapped for the raw dried root, plus yam, licorice and a little agarwood. Nothing in it is toxic. **Agarwood is CITES Appendix II**, so the 沈香 should not be newly sourced, although at 5 don in a batch it is the smallest concern this section raises. The two routes are worth noticing: half a don swallowed in hot water, and the same dry powder rubbed on the gums twice daily. Rubbing a gritty aromatic powder on an infant's gums is not pharmacology — it is counter-pressure, and counter-pressure genuinely does soothe a teething child, which is why a clean cold teething ring works. It also carries a real hazard that the text could not have known: anything rubbed on the gums of a baby goes into the mouth and may be aspirated, and this is why modern practice has abandoned teething powders and gels, most notoriously the ones containing benzocaine (methaemoglobinaemia) or the lead- and mercury-containing teething powders of the nineteenth and twentieth centuries. **齒不生 belongs with 髮不生 beside it, with 解顱 and with 龜背龜胷: all four are rickets — vitamin D deficiency.** The statement is written in full at 三神散 in 解顱 and holds here without modification. Delayed eruption of the primary teeth is one of the textbook signs, and the chapter's own reading — 髓不能充於骨, the marrow unable to fill the bone — is a description of unmineralised bone arrived at without the concept that would explain it. The other causes of genuinely late teeth are worth naming because two of them are found by screening and are treatable: **congenital hypothyroidism** (newborn screening finds it; thyroxine makes the child normal and the damage of leaving it is permanent), hypopituitarism, and the inherited conditions — amelogenesis imperfecta, ectodermal dysplasia, cleidocranial dysplasia. Most late teeth, though, are simply late: the normal range for the first tooth runs from four months to well past a year, and a healthy child with no tooth at twelve months needs nothing but reassurance. — Eui Young (Justin) Chung, L.Ac., Dipl. O.M.