An officer has to read you your Miranda Rights once you are under arrest and before any “custodial interrogation.”
Failure to do so will not necessarily get your case dismissed.
If the officer places you under arrest and does not read your Miranda Rights to you, he can not ask you any more questions. If the officer did ask you questions without reading you your proper rights, your answers might not be admissible against you at trial. It depends on what questions the officer asked you.
This would not include questions verifying your identity (name, date of birth, address, etc.), or any breath or blood test results. The officer reads a separate set of statutory warnings to you before asking for your consent or refusal for a breath or blood test.
In summary, if the officer does not read you your Miranda Rights, your case will not automatically be dismissed, but potentially admissions or confessions might be thrown out of evidence.