A score of 75 is the minimum passing score for the NBDHE. If you did not finish certain questions, I would assume they would be marked as incorrect. Whether you pass or not depends on how many questions you got correct on the portion you did finish as opposed to the questions you didn’t answer. However, for a definitive answer, it might be best if you contacted the Joint Commission on National Dental Examinations as they are who administer the exam and set the rules and guidelines.
https://www.ada.org/en/jcnde/contact