From the James Bond Wiki:
Most of the background information on Jaws comes from Christopher Wood's novelisation of the film The Spy Who Loved Me...
In Wood's novel, Jaws's real name is Zbigniew Krycsiwiki and he was born in Kraków, Poland.
Krycsiwiki was arrested by the secret police for his part in the "1972 bread riots". While imprisoned the police "beat him with hollow steel clubs encased in thick leather" until they thought he was dead leaving his jaw broken beyond repair.
Krycsiwiki later escaped and stowed aboard one of Stromberg's vessels. Eventually he was caught; however, instead of turning him in Stromberg hired a prestigious doctor to create an artificial jaw.
After 14 operations Krycsiwiki's jaw was restored using steel components that created two rows of terrifying razor-sharp teeth. The result of the artificial jaw left Jaws a mute.
Since none of the above is actually mentioned in either movies ["The Spy Who Loved Me" and "Moonraker"] this is not necessarily considered canon.
While Jaws is a mute in Wood's novelizations, he does speak in the film "Moonraker".
(this contradiction is a bit odd, since Wood also wrote the "Moonraker" and "The Spy Who Loved Me" film scripts)