Learn Hardcore Russian: Гигиена зубов важна для здоровья.

In Russian, when you express “hygiene of something,” the noun гигиена is followed by another noun in the genitive case to show possession or relation. You ask гигиена чего? (“hygiene of what?”) and answer гигиена зубов.

Why is важна used instead of важная?

Here важна is the short form of the adjective важный. In present-tense predicates without a copula, Russian uses short-form adjectives that agree in gender and number with the subject. Since гигиена is feminine singular, you use важна.

Why is there no verb “is” in the sentence?

In Russian, the present-tense form of the verb быть (“to be”) is usually omitted. The adjective in predicate position takes its place. So Гигиена зубов важна literally reads “Dental hygiene important,” meaning “Dental hygiene is important.”

Why does для take the genitive здоровья?

The preposition для always governs the genitive case. Therefore для здоровья means “for health,” with здоровья being the genitive singular of здоровье.

Can I say зубная гигиена instead of гигиена зубов?

Yes. Both are correct and interchangeable: • гигиена зубов (“hygiene of the teeth”)
• зубная гигиена (“tooth/dental hygiene”)

Where is the stress in гигиена and здоровья?

• гигиена [ги-ги-É-на], stress on the third syllable.
• здоровья [здa-РÓ-вья], stress on the second syllable.

Why is гигиена a feminine noun?

Most Russian nouns ending in -а are feminine (first declension). Гигиена is a loanword from Greek but still follows this feminine pattern.

How can I make this sentence more formal, using a copula?

You can insert являться (“to be”) and use the full adjective in the instrumental case: Гигиена зубов является важной для здоровья.
Here является = “is,” and важной is in the instrumental case because являться requires it.