Dysfunction of which anatomical structure is primarily responsible for gastroesophageal reflux disease (GERD) and the resulting dental erosion?

Gastroesophageal reflux disease (GERD) results from incompetence or inappropriate relaxation of the lower esophageal sphincter (LES), allowing acidic gastric contents to reflux into the esophagus and oral cavity. In dentistry, GERD is a significant cause of dental erosion (perimylolysis) — particularly on the palatal surfaces of maxillary teeth, which are bathed in acidic refluxate. GERD-related erosion presents as smooth, glossy, cupped or ditched enamel surfaces, initially affecting maxillary anteriors. Dental management includes: treating the underlying GERD, prescribing fluoride remineralization, advising avoidance of acidic foods and not brushing immediately after acid exposure, and using bicarbonate rinses.