Az őrlőfog érzékeny.

Az is the Hungarian definite article, meaning the.

Hungarian has two forms of the definite article:

• a before a consonant sound
• az before a vowel sound

Since őrlőfog begins with the vowel ő, the correct form is az őrlőfog.

Compare:

• a fog = the tooth
• az őrlőfog = the molar

This is similar to the English pattern a / an, though in Hungarian it applies to the, not the indefinite article.

In Hungarian, the verb to be is usually left out in the present tense when the subject is third person singular or plural.

So:

• Az őrlőfog érzékeny. literally: The molar sensitive.
• natural English: The molar is sensitive.

This is completely normal Hungarian grammar.

Compare:

• Én érzékeny vagyok. = I am sensitive.
• Te érzékeny vagy. = You are sensitive.
• Ő érzékeny. = He/She is sensitive.

Only the third-person present normally omits van/vannak.

Yes, őrlőfog is one word, and it is a compound noun, which is very common in Hungarian.

It is made up of:

• őrlő = grinding
• fog = tooth

So literally it means something like grinding tooth, which corresponds to molar in English.

Hungarian often forms words this way, by combining meaningful parts into a single compound word.

A rough pronunciation guide:

• őrlőfog ≈ ur-luh-fog
• érzékeny ≈ air-zay-keny

A few important points:

• ő is a long front rounded vowel. English does not really have an exact equivalent.
• é sounds roughly like the vowel in say, but without the English glide.
• ny is like the ny in canyon.
• Hungarian stress is always on the first syllable:
  • ŐRlőfog
  • ÉRzékeny

If pronunciation matters a lot to you, the sound ő is one of the trickier Hungarian vowels for English speakers.

No. In Hungarian, adjectives generally do not agree with the noun in gender, number, or case the way they do in many Indo-European languages.

So:

• érzékeny fog = sensitive tooth
• érzékeny fogak = sensitive teeth

The adjective érzékeny stays the same.

This is nice for learners, because you do not have to memorize adjective agreement patterns like in some other languages.

It can absolutely mean physical sensitivity too.

In this sentence, érzékeny means something like:

• sensitive
• tender
• possibly painful when touched, cold, sweet, etc.

So Az őrlőfog érzékeny is a very natural way to say a molar is sensitive, for example after dental work or because of tooth pain.

Yes. Hungarian word order is fairly flexible, and changing it often changes the focus or emphasis.

The neutral sentence is:

• Az őrlőfog érzékeny. = The molar is sensitive.

You could also say:

• Érzékeny az őrlőfog.

This still means The molar is sensitive, but it puts more emphasis on érzékeny—as if that is the important new information.

So the difference is not usually basic meaning, but what is being highlighted.

Normally, az őrlőfog refers to a specific molar or the molar being talked about.

So this sentence sounds like:

• That molar is sensitive
• The molar is sensitive

If you wanted to speak more generally, Hungarian might use a different structure depending on context. But as written, this sentence most naturally refers to a particular molar.

You would usually say:

• Az őrlőfogam érzékeny.

Here:

• őrlőfog = molar
• őrlőfogam = my molar

Hungarian often expresses possession by adding a suffix directly to the noun.

So instead of a separate word like my, Hungarian commonly uses an ending:

• fog = tooth
• fogam = my tooth
• őrlőfogam = my molar

The article az can still appear: Az őrlőfogam érzékeny.

You would say:

• Az őrlőfogak érzékenyek. = The molars are sensitive.

Changes:

• őrlőfog → őrlőfogak = molars
• érzékeny → érzékenyek

When the adjective is used as the predicate in a plural sentence, it commonly takes the plural ending too.

So:

• Az őrlőfog érzékeny. = The molar is sensitive.
• Az őrlőfogak érzékenyek. = The molars are sensitive.