sisyuubyou ga sinpai desu.

It is read ししゅうびょう (shishūbyō).

It is a noun meaning periodontal disease or, in everyday English, gum disease.

The kanji parts are:

• 歯 = tooth
• 周 = around
• 病 = disease/illness

So the literal idea is a disease around the teeth.

In this sentence, が marks the thing that is causing worry.

A very common pattern is:

X が 心配です = I’m worried about X

So:

• 歯周病が心配です = I’m worried about gum disease

This can feel strange to English speakers, because in English we usually say I am worried about X, with I as the subject. In Japanese, the thing of concern is often marked with が.

Because 心配です is not a verb phrase that takes を.

Here, 心配 is being used as a na-adjective / adjectival noun, and the pattern is:

X が 心配です

So を does not fit here.

If you use the verb 心配する instead, then を can appear:

• 歯周病を心配しています = I am worrying about / am concerned about gum disease

So:

• 歯周病が心配です → natural with 心配です
• 歯周病を心配しています → natural with 心配しています

But 歯周病を心配です is not correct.

心配 is a word that can function as:

• a noun meaning worry / concern
• a na-adjective meaning worried / concerning

With です, it becomes a polite statement:

• 心配です = am worried / is worrying / is a concern

In this sentence, the whole pattern X が 心配です means to be worried about X.

So even though English uses an adjective with a subject like I am worried, Japanese often builds it differently.

Japanese very often leaves out the subject when it is obvious from context.

So 歯周病が心配です usually means:

• I’m worried about gum disease
• or possibly We’re worried about gum disease
• or even He/She is worried about gum disease

Context tells you who is worried.

If you want to make I explicit, you can say:

• 私は歯周病が心配です

But in many situations, that sounds less natural than simply leaving 私は out.

Grammatically, Japanese allows a little ambiguity here, but in normal use it is usually understood as:

I am worried about periodontal disease.

That said, the Japanese structure is closer to:

• As for periodontal disease, it is a concern
• or Periodontal disease is something I’m worried about

So the English translation depends on what sounds natural in context. In most everyday situations, I’m worried about gum disease is the best translation.

Both can mean that someone is worried, but the nuance is a little different.

• 心配です = I’m worried / It’s a concern
• 心配しています = I’m worrying about it / I’m concerned about it

心配です sounds like a straightforward description of your state or feeling.

心配しています uses the verb 心配する, so it can sound a bit more like an ongoing act or continuing concern.

In many situations, both are natural. But for a simple statement like this, 歯周病が心配です is very common and natural.

Yes, but the nuance changes.

• 歯周病が心配です = I’m worried about periodontal disease
• 歯周病は心配です = As for periodontal disease, it’s worrying / it concerns me

Using が is the more neutral, standard choice in this pattern.

Using は can sound more contrastive or topical, as if you are setting 歯周病 apart from other things:

• 虫歯は大丈夫ですが、歯周病は心配です。 = Cavities are fine, but gum disease worries me.

So が is usually the best default here.

The polite version is:

• 歯周病が心配です。

Casual versions include:

• 歯周病が心配。
• 歯周病が心配だ。

Nuance:

• 心配です = polite
• 心配だ = plain
• 心配 = very casual, often used in conversation

So if you are speaking to a doctor, dentist, teacher, or someone you do not know well, 心配です is the safest choice.