haisha ga okuba no tsumemono to kamiawase o kakuninshimasu.

The dentist checks the molar filling and the bite alignment.

Breakdown of haisha ga okuba no tsumemono to kamiawase o kakuninshimasu.

• を: direct object particle
• と: noun-connector particle
• が: subject particle
• の: possessive case particle

Questions & Answers about haisha ga okuba no tsumemono to kamiawase o kakuninshimasu.

How do you read this sentence?

It is read:

はいしゃ が おくば の つめもの と かみあわせ を かくにんします。

Word by word:

• 歯医者 = はいしゃ = dentist
• が = subject marker
• 奥歯 = おくば = back tooth / molar
• の = linking particle, like of
• 詰め物 = つめもの = filling
• と = and
• 噛み合わせ = かみあわせ = bite / how the teeth meet
• を = object marker
• 確認します = かくにんします = checks / will check / confirms

Also, Japanese is normally written without spaces:

歯医者が奥歯の詰め物と噛み合わせを確認します。

Why is が used after 歯医者?

が marks the grammatical subject of the sentence: the person doing the action.

So here:

• 歯医者が = the dentist is the one who checks

A very literal structure is:

• Dentist
  • subject marker
    • filling and bite
      • object marker
        • checks

In many beginner sentences, が is used to clearly mark who does the action.

Could I use は instead of が here?