Yes, lions do sometimes lose some of their teeth as this excellent photograph by Ernest Porter shows. It was taken in the Kgalagadi Transfrontier Park, South Africa. This male has lost his lower incisor teeth bar one and he has broken off one of this canine teeth on his lower jaw. There are three obvious ways that a lion can lose his teeth: hunting and killing, fighting other lions and eating.
I’d expect the most likely way to lose teeth is during hunting and killing which can be dangerous for lions. Although there is a story of a male lion completely losing one of his lower canine teeth when fighting with a lioness. I’d expect the incisors on the lower jaw to be lost eating rapidly and without concern for injury to teeth. Perhaps biting onto bone and gristle and pulling with force. The last remaining incisor in the photograph is broken which to me indicates that his lower incisors were broken off and lost while biting into bone.
The teeth lost by this individual does not leave the lion disabled. They still function. But if the teeth, particularly the large, stabbing canines, are badly damaged it may impair a lion’s ability to kill its normal prey. We often see broken canine teeth. It may turn to killing humans who are very easy to kill.
It is said that all big cat man-eaters are or were infirm or disabled cats who were forced to kill humans to survive. Sometimes people may injure a tiger and ironically force the animal to hunt them in return. It is called the “infirmity theory”.
In 1989 two lions in Kenya (the Lions of Tsavo) hunted and killed more than 130 railway workers. Why did they routinely hunt people: prey that was utterly untypical? They were found to be suffering from massive toothache due to abscesses and severe dental problems according to a Field zoologist, Bruce Patterson, and a Waukegan dentist. The two lions were eventually killed by the railroad’s construction engineer, Lt. Col. John Patterson. He turned their skins into rungs for his home and eventually sold them to the Field Museum for $5,000 in 1926.
A famous big cat hunter turned conservationist, Jim Corbett (an Indian tiger reserve is named after him) said that when he was asked to kill a man-eating big cat (which happened quite often), time and again he discovered that the animal was suffering from old age and injury causing crippling infirmity.