How to deal with assistant acting unprofessional during the work day

Hello all. Wanted to ask your opinion on something I'm dealing with in regards to an assistant to see if what I'm feeling is valid or if I'm overreacting.

Some background: I'm a 27 year old male 2024 grad and have been at my job since graduation, so right about a year and a half now. The assistant in question is in her 30s and started around a year ago with no prior dental experience. She's had a hard time getting the hang of things and still constantly forgets materials and steps for procedures, which is beside the point, but probably is exacerbating my feelings on the issue.

Anyway, this assistant is consistently, in my opinion anyway, unprofessional during appointments and in front of patients. It's like she just doesn't know when to stop talking. The worst of it was an instance in which, for whatever reason, she was talking about how much she loved getting massages and asked me "do you ever have your girlfriend give you massages?" Mind you, this is mid appointment, we were actively treating a patient. I basically just stopped for a second and stared at her and went back to work. She later apologized, but still pulls stuff like this all the time.

What caused me to make this post, though, is what I feel are belittling comments about my age. I get it, I'm a young dentist and am perfectly capable of taking a little bit of ribbing. But in the past month she has said "he's like a little boy isn't he?" when I told a patient how old I was when asked (I'm 6'2" and have a mustache), she's said multiple times that I remind her of her little brother, and has said I "look like a college boy." Again, this is all in front of patients.

In my mind, patients can say whatever they want about my age and appearance, but I feel like there needs to be a line with a coworker, especially in a dentist-assistant relationship, double especially when she's not even that much older than me. I also feel that it's degrading patient trust. After all, no one wants a "little college boy" as their dentist.

Am I on an egotrip here for being aggravated by this? Do I need to go touch grass and worry about something else? If not, what the hell do I say to her to get her to stop without sounding domineering? Appreciate any and all feedback here.