haguki ga haremasita.

It is usually read はぐき.

• 歯 = tooth
• 茎 = stem/stalk in other contexts, but in 歯茎, the whole word means gums

So:

• 歯茎 → はぐき → gums

You will also often see it written as 歯ぐき, with one kanji and one hiragana, because 茎 is a less common kanji for many learners.

が marks 歯茎 as the thing that underwent the change or state described by the verb.

In 歯茎が腫れました, the gums are the thing that swelled.

So the structure is basically:

• 歯茎 = gums
• が = subject marker
• 腫れました = swelled / became swollen

A natural English translation may use my gums as the subject, but Japanese often just states the body part directly.

Both are possible, but they do slightly different jobs.

• 歯茎が腫れました。
  = My gums swelled / My gums are swollen.
  This presents the gums as the thing affected.

• 歯茎は腫れました。
  sounds more like As for my gums, they swelled or may suggest contrast, such as My gums swelled, but something else didn’t.

In a simple neutral statement about a symptom, が is very natural.

腫れました is the polite past form of the verb 腫れる.

• dictionary form: 腫れる = to swell
• polite non-past: 腫れます
• polite past: 腫れました

So 腫れました literally means swelled or became swollen.

This verb is intransitive, which means the gums themselves are swelling; you are not making them swell.

It can feel like either, depending on context.

Literally, 腫れました is past tense: swelled or became swollen.

But in real use, Japanese often uses the past form to describe a condition that started and is still relevant now. So:

• 歯茎が腫れました。
  can mean My gums swelled up
  or, in practical conversation, My gums are swollen

If you want to emphasize the current state more directly, 歯茎が腫れています is also very common.

Good question. The difference is mainly about event vs state.

• 歯茎が腫れました
  focuses on the change: the gums swelled / became swollen

• 歯茎が腫れています
  focuses on the current condition: the gums are swollen

At a dentist or doctor’s office, both can be natural:

• 昨日から歯茎が腫れています。
  = My gums have been swollen since yesterday.

• 今朝、歯茎が腫れました。
  = My gums swelled up this morning.

Japanese often omits possessives like my, your, or his/her when the meaning is obvious from context.

With body parts especially, Japanese commonly just says the body part:

• 歯茎が腫れました。
  literally: Gums swelled.
  naturally: My gums swelled / My gums are swollen

If you really need to specify, you could say:

• 私の歯茎が腫れました。
  = My gums swelled

But in normal conversation, that is often unnecessary.

Japanese nouns usually do not mark singular vs plural the way English does.

So 歯茎 can mean:

• gum
• gums

In this sentence, English will usually say gums, because that sounds more natural in many cases:

• My gums are swollen

But depending on the situation, it could refer to one area of the gum.

Yes, it is natural and understandable.

It sounds like something someone might say when describing a symptom.

A few very natural variations are:

• 歯茎が腫れました。
  = My gums swelled up.

• 歯茎が腫れています。
  = My gums are swollen.

• 歯ぐきが腫れています。
  Same meaning, but with a more common mixed writing style.

If you are talking to a dentist, 腫れています may be especially common when describing what is true right now.

The spaces are usually just for learners.

Normal Japanese is written without spaces:

• 歯茎が腫れました。

Textbooks and beginner materials often add spaces to make it easier to see:

• where one word ends
• where the particle is
• how the sentence is built

So the standard written sentence is 歯茎が腫れました。

Not if you mean gums.

• 歯 = tooth/teeth
• 歯茎 = gums

So:

• 歯茎が腫れました。 = My gums swelled
• 歯が腫れました。 would sound odd, because teeth themselves do not normally swell

If the painful area is around the teeth, 歯茎 is the correct word.

腫れる means to swell, especially from:

• inflammation
• irritation
• injury
• infection

So it is a good verb for physical swelling in a medical or body-related sense.

Examples:

• 目が腫れた。 = My eye got swollen.
• 足が腫れている。 = My leg/foot is swollen.
• 歯茎が腫れた。 = My gums got swollen.

It is not just any kind of becoming bigger; it specifically suggests swelling.

Yes. The plain/casual version is:

• 歯茎が腫れた。

Compare:

• 歯茎が腫れました。 = polite
• 歯茎が腫れた。 = casual/plain

Use 腫れました when speaking politely, such as to a dentist, teacher, stranger, or in formal situations. Use 腫れた with friends or family in casual conversation.