Coroana dentară este nouă.

In Romanian, the definite article is usually attached to the end of the noun instead of being a separate word like English the.

• coroană = crown
• coroana = the crown

So coroana dentară means the dental crown.

The dictionary form is coroană.

Here is the pattern:

• o coroană = a crown
• coroana = the crown

The final -a in coroana is the feminine singular definite article.

Because the adjective has to agree with the noun.

coroană is:

• feminine
• singular

So the adjective must also be feminine singular:

• masculine singular: dentar
• feminine singular: dentară

That is why you get coroană dentară / coroana dentară.

For the same reason: adjective agreement.

Since coroana is feminine singular, new must also be feminine singular:

• masculine singular: nou
• feminine singular: nouă
• masculine plural: noi
• feminine plural: noi

So:

• coroana este nouă = the crown is new
• dintele este nou = the tooth is new

Este means is. It is the 3rd person singular form of the verb a fi (to be).

Some forms of a fi are:

• eu sunt = I am
• tu ești = you are
• el/ea este = he/she is
• noi suntem = we are
• voi sunteți = you are
• ei/ele sunt = they are

So Coroana dentară este nouă literally has the same basic structure as English:
The dental crown is new.

Yes. In everyday Romanian, e is a very common shorter form of este.

So both are correct:

• Coroana dentară este nouă.
• Coroana dentară e nouă.

The version with este may sound slightly more careful or formal, but both are standard.

In Romanian, adjectives often come after the noun.

So:

• coroană dentară = dental crown

This is the normal order. Romanian can sometimes place adjectives before the noun, but that often changes the style or emphasis. For a basic descriptive phrase like this, noun + adjective is the expected pattern.

It is an adjective, but coroană dentară is also a very common medical/dental combination.

Grammatically:

• coroană = noun
• dentară = adjective meaning dental

So the phrase is built normally, even if it functions like a common technical term.

A rough English-friendly guide is:

ko-roA-na den-TA-rə ES-te NO-wuh

A few useful notes:

• ă is a short central vowel, something like the a in sofa
• oa in coroana is pronounced together as a diphthong
• nouă has two vowels at the end: nou-ă, not just nou

If you want it broken down word by word:

• coroana → ko-roA-na
• dentară → den-TA-rə
• este → ES-te
• nouă → NO-wə

They are spelled the same but mean different things depending on context.

In this sentence, nouă is clearly the feminine singular form of the adjective nou (new) because it describes coroana.

Examples:

• Coroana este nouă. = The crown is new.
• Ne-a spus nouă. = He told us.

So context tells you which nouă you are dealing with.

Yes, but the basic order here is the most neutral one:

• Coroana dentară este nouă.

You might also hear:

• Nouă este coroana dentară.

But that sounds marked or poetic and is not the normal way to say it in everyday speech.

For learners, the safest pattern is:

subject + este/e + adjective

If you want to say A dental crown is new or The dental crown is a new one, you would remove the definite article from the noun:

• O coroană dentară este nouă.

Compare:

• coroană = crown
• coroana = the crown

So the sentence changes from definite to indefinite just by changing the noun form.

It is in the nominative, because it is the subject of the sentence.

In:

• Coroana dentară este nouă.

the subject is coroana dentară, and este nouă is what is being said about it.

For a beginner, the most useful point is simply: this is the normal subject form of the noun phrase.