PARIS: Man's first known trip to the dentist occurred as early as 9,000 years ago, when at least nine people living in a Neolithic village in present-day Pakistan had holes drilled into their molars and survived the procedure.

The findings, being reported Thursday in the scientific review Nature, push back the dawn of dentistry by 4,000 years, to around 7000 B.C. The drilled molars come from a sample of 300 individuals buried in graves at the Mehrgarh site in western Pakistan, believed to be the oldest Stone Age complex in the Indus River valley.

"This is certainly the first case of drilling a person's teeth," said David Frayer, professor of anthropology at the University of Kansas and lead author of the report. "But even more significant, this practice lasted some 1,500 years and was a tradition at this site. It wasn't just a sporadic event."

The earliest previously known evidence of dental work done in vivo was a drilled molar found in a Neolithic graveyard in Denmark dating from about 3000 B.C.

All nine of the Mehrgarh dental patients were adults - four females, twomales and three individuals of unknown gender; they ranged in age from about 20 to over 40. Most of the drilling was done on the chewing surfaces of their molars, in both the upper and lower jaws, probably using a flint point attached to a bow that made a high- speed drill, the researchers say. Concentric ridges carved by the drilling device were found inside the holes.

The drilling may have been done to relieve the suffering and damage of tooth rot, but only 4 of the total of 11 teeth showed signs of decay associated with the holes. The scientists say it is clear that the holes were not made for aesthetic reasons, given their position deep in the mouth and on the erosion- prone surface of the teeth.

There also is no evidence of fillings, but because some of the holes were bored deep into the teeth, the researchers believe something was used to plug the holes. What that substance was is not known. The holes ranged in depth from a shallow half-a-millimeter to 3.5 millimeters, deep enough to pierce the enamel and enter the sensitive dentin.

Dental health was poor at Mehrgarh, though the problems were less often tooth decay than brutal wear and tear. Roberto Macchiarelli, professor of paleoanthropology at the University of Poitiers, France, and the report's lead anthropological researcher, attributed the bad teeth to the Neolithic diet, which included newly domesticated wheat and barley.

"A lot of abrasive mineral material was introduced when grains were ground on a stone," he said, "and as these people moved to a grain diet, their teeth wore down, dentin was exposed and the risk of infection rose."

The Mehrgarh complex, occupied for 4,000 years, sits beside the Bolan River in Baluchistan on a plain that was repeatedly buried in alluvial deposits that not only destroyed mud-brick buildings but crushed many skeletons in the graveyard.

The excavation of 300 individuals was begun by a French team in the 1980s; international groups followed until 2001, when it became too dangerous to work in Baluchistan.

None of the individuals with drilled teeth appear to have come from a special tomb or sanctuary, indicating that the oral health care they received was available to any and all.

Frayer said that, given the position of the holes and the angles of the drilling, "we're pretty sure these were not self- induced." That the patients were alive and lived to tell the tale of their dental visit is proved, he says, by subsequent wearing down of their teeth and by deliberate smoothing and widening of the holes later on.

Improbably, one of the 11 drilled molars was pierced on the back of the tooth between it and the next molar, which evidently had either first been removed to make way for the drill or lost earlier. Even so, it remains a mystery how the hole was drilled behind the tooth deep in the mouth.

One of the nine individuals saw the dentist several times, apparently, and had three molars drilled. Another person had two drillings on the same tooth.

The dentists may have been highly skilled artisans at Mehrgarh, where beads of imported lapis lazuli, turquoise and carnelian were found drilled with holes even smaller than the ones in the nine individuals. Discovered among the beads were finely tipped drill heads.

"The drilling of teeth is very rare in the anthropological record," said Macchiarelli, noting that work similar to that done at Mehrgarh does not recur until much later, among the Anasazi of the southwest United States around A.D. 1100 and in Europe around A.D. 1500.

But that people have been fiddling with their teeth for ages is clear, Frayer said, citing the use of toothpicks by early man in Africa and by Neanderthals in Europe. Channels were rubbed into the enamel of their teeth at the gum line by regular back-and-forth motion of a grass stalk or quill or other utensil. There also have been many cultures in which people shaped their teeth or drilled holes in the front ones for aesthetic reasons.

The 1,500-year-long tradition of drillwork at Mehrgarh appears not to have been passed down to later cultures: There is no evidence that the Chalcolithic, or Copper Age, people who next lived there ever visited the dentist. Why the practice came to a halt is not known.