Which of the following symptoms is indicative of excessive vomiting?

Dental enamel erosion is indeed indicative of excessive vomiting, particularly in the context of disorders such as bulimia nervosa. The frequent exposure of the teeth to gastric acid from vomit leads to the degradation of dental enamel, which can result in sensitivity, cavities, and aesthetic concerns. This symptom is a direct consequence of repeated purging behaviors associated with certain eating disorders, highlighting the physical health impacts that can accompany psychological disorders.

Constipation can occur for various reasons, including dietary habits and certain medications, but it is not specifically linked to excessive vomiting. Low bone mineral density can result from a range of issues, including nutritional deficiencies, but is not solely indicative of vomiting. Amenorrhea, while it can be associated with eating disorders and excessive vomiting, is more specifically related to changes in hormonal levels due to malnutrition or extreme weight loss. Therefore, dental enamel erosion stands out as the strongest indicator of excessive vomiting due to its direct relationship with the physiological effects of frequent exposure to acid from the stomach.