Tuesday, 4 March 2014

Gum-filled teeth, golfballs and telegraph cables


Ten years ago, Stuart Brown of Fortune magazine was having his root canal filled with gutta percha. A few months ago Neville Walsh of the Royal Botanic Gardens Melbourne was doing the same.

As is their wont, the dental guy working in Neville’s mouth struck up a conversation with him while his mouth was full of scaffolding and pointy metal implements. He mentioned that gutta percha was a plant product, and one with an interesting history.

He was right, on both fronts. Stuart Brown explains that gutta percha is the sap of a tree native to South-east Asia called Isonandra gutta (these days we call it Palaquium gutta). It was overharvested at first, leading to destruction of native populations and a collapse of the market. Later, and today, it is grown in plantations in Asia and South America.

According to Wikipedia (a handy if not always impeccable source), gutta percha means ‘percha sap’, after the Malayan common name for the species, Getah Perca. (To confuse things a little, a Northern Australian species that produces nice timber but no toothsome sap, Excoecaria parvifolia, is called the Guttapercha Tree.)

Palaquium is a genus in the Sapotaceae, a plant family providing various foods, medicines, soaps and poisons to us humans. You'll remember the miracle fruit of last year.

Like rubber, gutta percha is an isoprene, but with different chemical bonds making it not as elastic, a better insulator and rather plastic when heated. It started its commercial life as an insulating material for telegraph cables stretching across firstly the English Channel in 1851 and then later across the Atlantic. Unlike previous compounds used for this purpose it wasn’t favoured by marine plants and animals.

It also found its way into golf balls, replacing feathers stuffed inside leather. As well as furniture, jewelry, guns and (according to my impeccable source) the orifices of victims of criminal Wo Fat in the 70s television show Hawai Five-O. Nowadays gutta percha has been replaced by synthetic products (except in quaint nineteenth century reenactments by historically inclined golf enthusiasts, and possibly by some television crims).


Dentistry discovered gutta pecha in the later nineteenth century, firstly for filling cavities and then in 1887, according to Stuart Brown, for stuffing root canals where its plasticity and ability to extrude into distant parts of the canal was ideal. So far, a better product, ‘natural’ or synthetic has yet to be found and the gutta percha industry in 2003 was worth $30-40 million, with most of the US product coming from Brazil.

Yet, endodontists are not entirely happy with gutta percha and Stuart Brown reported on research then to replace it with synthetic product that would be easier to work with and didn’t leak quite as much. A paper published last year by Brazilian researchers confirmed that a polymer called Resolin performed better than gutta percha, although it did depend on the filling technique. Enjoy your gum-filled teeth before they go the way of the gutta percha golf ball.

Image: The plant illustration is from Encyclopedia of Life (published by Leo Shapiro, photographer Franz Eugen Köhler, from Köhler's Medizinal-Pflanzen) - this genus doesn't seem to be represented in the Royal Botanic Gardens Melbourne living collection. The gutta percah golf balls are from the Golf for all Ages! site, and the mouth is my own (the gutta percha is hidden towards the back).

2 comments:

Gerry Kraft said...

Tim, interesting story. Any chance of planting a few of these trees in the Gardens? How fast do they grow, and would they make it through a Melbourne winter?

Tim Entwisle said...

I don't think it will grow outdoors but we could try it in our glasshouse. Not a looker, but nice story.