Se me ha roto la muela.
Could anyone easily explain what is the purpose of "se" particle here? Can we just say "Me ha roto la muela", the same way we say "Me duele la cabeza"?
We don't say "Se me duele la cabeza", right?
If you were around when Lazarus used to explain to us the multitude of purposes for using pronominal se you would recognize this as his "se rompío la radio" "the radio broke" example. (the indirect object is added just to show who is effected by the action.) Se me rompío la radio. The reasoning behind using se in this situation has been explained by several different methods showing the flexibility of pronominal meanings.
This situation has been explained as a "shifting of guilt" (away from me and the radio), detransitisizing (going from transitive to intransitive usage) going from active to passive voice, used in unforeseen events, to express the nuance of accidentally, et. al.
I broke the radio.
The radio broke.
The above situation was called the "detransitizing se". Notice that this could also be looked at as going from a active voice to a passive voice situation. The pronominal meaning of accidentally or an unforeseen event is obvious from the context.
So in this case if the non-pronominal romper was used, we would expect a transitive meaning. Someone/thing is breaking something. The tooth is breaking something or I am breaking something. Add the se and all of the sudden the tooth just broke (no one is to blame, no one broke anything). It became a passive situation. We add the i.o.p. just to show possession or who is the receiver of the verb's action.
Se me rompió la muela.
Lazarus gave us some amazingly clear reasoning of a very complex subject. I suggest you read some of his threads on the pronominal use of verbs and how it effects their meanings.
Here is a link to the article containing Se me rompío la radio. It is not in his first reply (a listing of some uses for the pronominal verb), but in the 2nd reply by him. Read it several times. Each time you read it you will get a deeper understanding.
I think it is used in that way when the speaker wants to denote an unintentional action and taking some of the blame...
It would translate as: "The tooth has broken on me..."
See this lesson, specifically from 9 minutes onwards. (I already commented on Luz's response but then thought maybe a small comment wouldn't be noticed?)
Somebody clever will be along in a minute, but my reckoning is as follows:
Romperse = Reflexive verb An example in my Dictionary gives - se rompió un brazo - he broke his arm
Therefore your example must use both pronouns to describe the fact that you have broken your tooth- it I have broken my wrist.
Open to corrections please.