Dikiş yeri fermuar dişiyle birlikte kontrol edildi.

It is a noun compound.

• dikiş = stitching, sewing, seam
• yer = place
• yeri = its place / place of

In Turkish, this type of compound is very common:

• first noun stays plain: dikiş
• second noun takes a compound marker that looks like the 3rd person possessive: yeri

So dikiş yeri means something like:

• the place of stitching
• the seam area
• the sewn part / stitch area

A native English speaker may expect something more like the place of the stitching, but Turkish usually builds this idea as a compound instead.

Because in Turkish noun compounds, the second noun usually takes a special ending.

So:

• yer = place
• dikiş yeri = stitching place / seam area

This does not necessarily mean possession in the everyday sense. It is just the normal way to form many compound nouns in Turkish.

Compare similar patterns:

• otobüs durağı = bus stop
• kapı kolu = door handle
• yatak odası = bedroom

So dikiş yeri follows a very standard Turkish pattern.

This is fermuar dişi + ile.

Break it down:

• fermuar = zipper
• diş = tooth
• fermuar dişi = zipper tooth

Then Turkish adds ile = with.

When ile attaches to a word ending in a vowel, it usually becomes -yle / -yla with a buffer y.

So:

• dişi + ile
• dişiyle

That is why you get fermuar dişiyle = with the zipper tooth.

You may also see ile written separately in some contexts, but the attached form is very common.

Yes, -yle already means with.
But birlikte adds the sense of:

• together with
• along with
• in combination with

So:

• fermuar dişiyle = with the zipper tooth
• fermuar dişiyle birlikte = together with the zipper tooth / along with the zipper tooth

Using both is very natural in Turkish. It can sound slightly more explicit or formal than using -yle alone.

Because kontrol etmek is a compound verb made with a noun plus etmek.

• kontrol = check, inspection, control
• kontrol etmek = to check / inspect / control

In this sentence, it appears in the passive past:

• kontrol edildi = was checked / was inspected

Many verbs in Turkish work this way, especially with words of foreign origin:

• yardım etmek = to help
• fark etmek = to notice
• kontrol etmek = to check

So even though it functions as one verbal idea, it is written as two words.

Yes, it is passive.

English uses a separate word:

• was checked

Turkish builds that meaning into the verb form itself:

• edildi

Here, edildi carries both:

• the passive idea: was done
• the past idea: happened in the past

So there is no separate word for was. Turkish often packs that information into the verb ending.

A useful contrast:

• kontrol etti = he/she/it checked
• kontrol edildi = it was checked

Because Turkish is typically a verb-final language.

A very common Turkish sentence pattern is:

• topic / subject
• other information
• verb

So here:

• Dikiş yeri = the seam area
• fermuar dişiyle birlikte = together with the zipper tooth
• kontrol edildi = was checked

This verb-final structure is one of the biggest differences from English word order.

Because Turkish does not have a definite article like English the.

So Turkish often leaves definiteness to:

• context
• word order
• shared knowledge
• the overall situation

That means dikiş yeri can be understood as the seam area if the context already makes it specific.

This is very normal in Turkish. English needs the, but Turkish usually does not.

Not necessarily. This is a very important vocabulary point.

In Turkish, kontrol etmek often means:

• to check
• to inspect
• to examine

So in many contexts, it does not mean English to control in the sense of to command or to regulate.

That is why learners often treat kontrol etmek as a false friend.
Even though it looks like English control, in practical use it very often means check.

Literally, diş is singular: tooth. So fermuar dişi is literally zipper tooth.

However, in technical or manufacturing language, a singular compound can sometimes refer to a part or component in a more general way, not just one isolated tooth.

So depending on context, it may mean:

• one zipper tooth specifically
• the zipper tooth part/component
• the zipper teeth area as a technical reference

If Turkish wanted to clearly emphasize plural teeth, it could use fermuar dişleri. But the singular form in a compound is still very normal.