"the truth as I have seen it." is a really key point.

Buddha (and the awakened ones)taught the doctrine of karma,
among other teachings, which is more complex, subtle and encompassing than (most) people want to/can know.

Understanding karma, one would see that one's experience is entirely predicated on previous actions--and these are "beginningless".

That is, there is not a linear, direct progression to them. This is why a person can lie in a business deal, say, and make money anyway. They might think "well, I made an extra 500 dollars", and think that "karma" is foolish, but what they don't see, is that the lie was not the cause of making that 5oo dollars.

The cause was some altogether other good deed that is probably long forgotten; while the lie will have karmic results down the road. Likely at a time when it seems to make no sense. ("why me?!")

In the same way, one's own experience of a dentist must be related to one's own karma.

How can one person have a good experience?
One have a bad experience?
Is the dentist "bad"? Is there any objective pure "badness"?

Can we know this, for a fact? No, because some have a good experience. Why?

karma is simply "action". And action is imprinted on the conscious mind that stores all the seeds/imprints. Nothing is lost. There is indeed a "stream of consciousness" that strings all those beads together.

That you felt some sort of trepidation about posting a "bad" review", says that you have an intuition about karma and its role here.
In this sense, your own experience can be a form of 'purification'. Let's say you review it, and let go of any anger or bitterness, and consciously dedicate your unpleasant experience to the UNDOING of others' ripening karma, so that others do not suffer the same way--This is much more aligned with what the Buddha taught than posting a "negative" review that "speaks the truth" (subjectively)

When you really reflect on it, I think you will see the profound difference you could make, entirely without a single "post", by changing your own perception of the event. Not even needing to speak of it. You could actually get to a place where you praise the "dear, bad experience" which is really like praising the "dear bad thoughts", as some Lamas teach. And they know they're teaching!

Thoughts are the builders!

Buddha taught *knowing*. Which must be experienced for oneself, and verified--and is very different from perception, or even thinking. Perception is bound up in "my truth", and its umpteen reactive filters, while knowing comes to those who practice and study the teachings. In knowing, all the concepts of "me" and "this one"  (or "that one") are loosened.

I had just this same quandary some years ago, with a "bad" dental experience".  So, I resonate with this question. Ultimately, you are not responsible for others though. (but this is a tough one, since it keeps raising its head in new guises) You can though, and must, (finally) come to a place where you care for *all)others as much as your dearest beloved.

And in that place, you will know for certain, not just taking "my" word, that we create our own realities, and karma is a huge part of it.
This does not mean you won't help someone in need, whenever you see someone in need, and are able to respond, but you will likely give up the sweeping belief that there is any independently originating 'truth'. ( including "mine") Along with that will go any crusading impulse to 'set people straight' with your 'truth'. Big liberation! :-) Everything is connected. That being so, dedicate any suffering to the transmutation of "karma" for all others, so that they will not need to  experience the untold modes of ripening.

And "you" will be putting "good karma" in the bank. (where in sincerely dedicating it, it doubles and triples and so on...Truly.

best, C