This charm appeared in the Wrexham Advertiser as one that was used in Coedpoeth and Bwlch Gwyn.  But the words appear in "Y Gwyliedydd" for May, 1826, page 151.  The Welsh heading to the charm informs us that it was obtained from an Irish priest in county Cork, Ireland.  The words are:—

Fel yr oedd Pedr yn eistedd ar faen Mynor,
Crist a ddaeth atto, ac efe yn unig.
Pedr, beth a ddarfu i ti?  Y Ddanodd, fy Arglwydd Dduw.
Cyfod, Pedr, a rhydd fyddi;
A bydd pob dyn a dynes iach oddiwrth y ddanodd
Y rhai a gredant i'r geiriau hyn,
Yr wyf fi yn gwneuthur yn enw Duw.

The translation is:—

Peter sat on a marble stone,
Jesus came to him all alone.
Peter, what is the matter?  The toothache, my Lord God.
Rise Peter, and thou shalt be cured;
And every man and woman who believes these words
Shall be cured of the toothache,
Which I perform in the name of God.
(Welsh Folk-lore, Owen, 1896)