Learn Hardcore French: Nous nous brossons les dents après le dîner.

The first nous is the subject pronoun (we). The second nous is the reflexive pronoun for the verb se brosser (to brush oneself). Many actions done to one’s own body in French are expressed with a reflexive verb: Je me brosse, Tu te brosses, Il se brosse, etc. Without the reflexive pronoun, Nous brossons would just mean “We brush (something)” with no indication that it’s our own bodies.

Why is it les dents and not nos dents?

With body parts, French normally uses the definite article (le, la, les) together with a reflexive verb to show possession. The reflexive pronoun already tells you whose body part it is. Examples:

Je me lave les mains.
Il se peigne les cheveux. If the body part belongs to someone else, you don’t use the reflexive form: Je brosse les dents de mon fils.

Is Nous brossons nos dents wrong?

It’s understandable but unidiomatic. French overwhelmingly prefers the reflexive pattern: Nous nous brossons les dents. You might use a possessive for strong contrast (e.g., “our teeth, not the dog’s”), but even then French typically keeps the reflexive: Nous nous brossons les dents, pas celles du chien.

How do you conjugate se brosser in the present tense?

Je me brosse
Tu te brosses
Il/Elle se brosse
Nous nous brossons
Vous vous brossez
Ils/Elles se brossent

How do you negate the sentence?

Put ne … pas around the reflexive pronoun + verb:

Nous ne nous brossons pas les dents après le dîner. Other negatives work the same way:
Nous ne nous brossons jamais les dents après le dîner.

Where can après le dîner go in the sentence?

Either at the end or at the beginning:

Nous nous brossons les dents après le dîner.
Après le dîner, nous nous brossons les dents. (add a comma when fronted)

Can I say après dîner or après avoir dîné?

Yes:

Après dîner is an idiomatic, concise alternative to après le dîner.
Après avoir dîné focuses on the action “after having dined” and is a bit more formal/explicit. Colloquially you may also hear après manger.

Why se brosser and not se laver for teeth?

The standard collocation is se brosser les dents. You will hear se laver les dents in casual speech, but it’s less precise; brushing is what you actually do to teeth.

How would I say it with the everyday “we” (on)?

On se brosse les dents après le dîner. In spoken French, on is more common than nous, and it takes third-person singular verb forms.

How do I give a command?

To one person (tu): Brosse-toi les dents après le dîner.
To several people or politely (vous): Brossez-vous les dents après le dîner.
Let’s… (nous): Brossons-nous les dents après le dîner. Negative:
Ne te brosse pas / Ne vous brossez pas les dents après le dîner.

How do I say it in the past or near future? And why is there no agreement on brossé?

Past (passé composé): Après le dîner, nous nous sommes brossé les dents. No agreement on brossé because the direct object (les dents) comes after the verb; here se is indirect. With pronominal verbs, the past participle agrees only with a preceding direct object.
Near future: Nous allons nous brosser les dents après le dîner. Negative: Nous n’allons pas nous brosser les dents après le dîner.

Any quick pronunciation tips?

Nous nous = “noo noo.”
brossons: final -ons is nasal “on” [ɔ̃]; don’t pronounce the -s or -n separately.
les dents: “lé dahn”; the -t and -s of dents are silent; the -s of les is silent here (next word starts with a consonant).
après: “ah-prè”; final -s is silent.
le dîner: “lə dee-nay”; the accent on é gives “ay.”

Does the present tense here mean a habit?

Yes. French present covers both current actions and habits. With a time phrase like après le dîner, it naturally reads as a habitual routine.

Are there regional differences for the word dîner?

Yes. In France today, le dîner is the evening meal. In parts of Belgium, Switzerland, and Canada, the evening meal is often le souper, and dîner may refer to midday. There you could say après le souper.

Why is it après le dîner, not après du dîner?

Because après takes a direct noun phrase with its article: après le/la/les + noun. The form du is a contraction of de + le, but après is not followed by de.

How do I say “before dinner”?

Use avant: Nous nous brossons les dents avant le dîner.

How would I say “after we have dinner” with après que?

Use the indicative after après que:

Habit/general: Après qu’on a dîné, on se brosse les dents.
Future plan: Après que nous aurons dîné, nous nous brosserons les dents. Many learners prefer the simpler Après le dîner or Après avoir dîné.