“Meth was the main one that we did,” John says in the series. “It was starting to really f--k me up in the head. I mean, I’m still kind of f--ked up in the head from it now.” 

So, does smoking meth really ruin your teeth? Well, as the doctors point out in the show, viewers may have heard the phrase "meth mouth," which is missing or blackened teeth from long term methamphetamine abuse.

According to RecoveryWays.com, meth is bad for peoples' teeth for several reasons. "The first is that it stimulates the sympathetic nervous system, which constricts salivary glands. ... Meth constricts saliva production for long periods of time. The problem is that saliva protects and restores tooth enamel. When your mouth is chronically dry, your teeth are more vulnerable to cavities and decay," the site states.

Additionally, the recovery site notes that abusing meth makes your mouth extremely dry and thirsty, which results in people drinking sugary drinks such as soda. "The sugar feeds bacteria that destroy tooth enamel and in the absence of protective saliva, these bacteria are far more destructive," the site states.

The third reason that meth ruins your teeth is because of simple neglect and personal hygiene.  

While viewers are led to assume that John from Netflix's Tiger King's missing teeth are a result of prolonged meth use, he recently shut that rumor down. Addressing the state of his teeth to TMZ, John explained that his lack of teeth was due to genetic reasons and not from smoking meth.

In July 2019, the viral Netflix star got a pair of new chompers, and revealed that the Netflix producers purposefully did not show his dentures in the documentary.

He even updated fans on the state of his teeth in a recent Facebook post, writing, “Yes, I have my teeth fixed. The producers of the Netflix series had video and pictures of this, but chose not to show it. It's all about the ratings for them, not the people they hurt.” 

Stream Tiger King: Murder, Mayhem and Madness on Netflix.