Zac Efron - NO 911 Call After Jaw Break

Zac Efron broke his jaw and gashed his face in what people say was a violent fall in his house after slipping in a puddle of water ... yet there was NO 911 call.

TMZ checked with law enforcement sources and no one called 911 to report any incident on Sunday -- when the injury occurred. We checked the days prior to and after Sunday as well -- No 911 call.

The mishap is puzzling for sure. Zac has been in rehab twice this year for cocaine abuse. He's also had problems with Molly and we're told staying sober has been a struggle.

It's unclear how Zac made his way to the ER ... but given that the injury was so severe his mouth had to be wired shut ... it's bizarre it didn't warrant a 911 emergency.