|Online Appearance?||Yes (as Dr. Alcazar)|
Dr. Salazar Kagan (known as Dr. Alcazar in the online version) is a professional oral surgeon and a dentist. In the books, he is referred to as Dr. Kagan. He is a rather new, albeit minor, antagonist in the series, making his debut in The Ugly Truth. He became Greg's new dentist when Greg's dad abruptly changed his dentist for him. Although he is a professional, he is not very considerate and seems to use fear to scare his patients into taking better care of their teeth, as he unnerves his patients by decorating his waiting room with horrific posters of oral disease. He never smiles and is also shown to have poor anger management. In the middle of his first appointment with Greg, Greg accidentally bites down on his finger during some oral x-rays. As a result of his anger from his bit finger, he prescribed a headgear to Greg who probably didn't need it. The next day, Greg couldn't find his headgear. The headgear was later stolen by Manny Heffley, which Greg considers to be a blessing. In Double Down, Dr. Kagan reappears when Greg mentions the Spineticklers book "My Dentist is the Devil". It's possible that Greg thought that the reason for Dr. Kagan's cold attitude and use of fear may have been because he is actually the devil in disguise.
- Dr. Kagan's appearance is quite identical to Chirag Gupta's father. The only difference is the presence of his moustache.
- It has been confirmed that Greg brushes his teeth four times a day due to a scare when he was little. As such, him drinking soda wouldn't really do harm to his teeth.