I can't help you related to dental application. To answer the question related to medical school applications (recognizing there may be some differences in how dental schools handle these issues), the answer is that it wouldn't be perceived as excuse making. However, what you write can be discussed. Often times, especially if you don't wish to really discuss what happened, it can be best to be vague. Nonetheless, I encourage you to think about whether you are willing to discuss this - because even if you word it vaguely, in the course of the conversation, an interviewer may probe close to details of what happened. Best of luck. Hopefully some dental applicants or moderators will see this and answer.