Breakdown of Dov'è Maria? Sarà dal dentista.
essere
to be
dove
where
da
from, at (someone's place) / by (oneself), on one's own
Maria
Maria
Questions & Answers about Dov'è Maria? Sarà dal dentista.
Why does the sentence use the future tense sarà if they are asking where Maria is right now?
This is a great example of the epistemic future. In Italian, we often use the future tense to express a guess or an assumption about something happening right now. So in this context, sarà doesn't mean she will be there later; it means she is probably or must be there at this exact moment.
Could sarà dal dentista also mean she will be at the dentist in the future?
Grammatically, yes. However, because the first question (Dov'è Maria?) asks about the present moment, the context makes it clear this is a guess about right now. To clearly talk about a future appointment instead of a guess, you would usually add a time word, like domani sarà dal dentista (tomorrow she will be at the dentist).
Why do we use dal (da + il) instead of an Italian word for at or to?
When you talk about going to or being at a person's home or professional workplace (like a doctor, mechanic, or dentist), you must use the preposition da. Since dentista takes the masculine article il here, da and il combine into the articulated preposition dal.
Dentista ends in -a. Why does it take the masculine article to form dal?
Professions ending in -ista (like dentista, barista, or tassista) can be both masculine and feminine depending on who you are talking about. When talking about a specific female dentist, you use la dentista (which would make it dalla dentista). Since there is no specific gender known here, it defaults to the masculine il dentista, giving us dal.