By Alexis Tereszcuk - Breaking Celebrity News Senior Reporter

Lindsay Lohan’s startling rotten toothed smile on the red carpet Wednesday night was shocking to say the least, and a dental expert has told Breaking Celebrity News that the decay has most likely come from “smoking and drug use.”

Dr. Pankaj Singh, of Arch Dental Associates in New York City, who has not treated the starlet, said: “This type of damage appears to be from a combination of smoking, drug use and a lack of personal care.”

As Breaking Celebrity News previously reported, Lohan’s stained teeth that she flashed on the red carpet are a far cry from the million dollar smile she used to have.

The heavy smoking 25-year-old is often seen puffing on a cigarette, but the Singh said tobacco alone wouldn’t cause the decay on her teeth. 

Lindsay Lohan's Teeth Show Signs Of ‘Definite Neglect,’ Smoking And Red Wine

“Smoking causes yellowing of the teeth, which we definitely see here in this picture. However, at such a young age, smoking wouldn’t cause the decay and browning you see around the gums. Damage like that is something we see in patients who are using or have used drugs.”