Obstructive sleep apnea is a condition that occurs when physical obstructions block your airway as you sleep. If you suffer from this condition, you also may suffer from daytime fatigue or frequent waking during the night. Your dentist may be one of the first people to suspect that you have sleep apnea. This is because some structural abnormalities that block your airway, such as an oversized tongue, are easily noted during a visual exam at your dental office. Dentists may also note changes in your oral health that occur from this condition such as worn-down teeth caused by tooth grinding.