'Fantasy Factory' Star -- Mouth in Ruins

"Fantasy Factory" star Scott "Big Cat" Pfaff hasn't been to the dentist in 10 years -- and this week, he's gonna pay for it big time ... with multiple painful procedures.

Pfaff finally ended his decade-long dental sabbatical a few days ago -- and we're told the mouth doc immediately spotted multiple cavities ... and several teeth that need to be pulled.

Sources close to Big Cat tell us, he also has to get a root canal asap -- and the first of several pain-filled visits is scheduled for this week.

Don't forget to floss.