You must absolutely avoid crunching on ice cubes, as their hardness and extreme temperature cause micro-cracks in the enamel, damage existing dental work, and put excessive strain on the jaw joint.

noli's read

This warning is scientifically very sound and validated by professional bodies. The American Dental Association (ADA - expert opinion) formally advises against crunching ice, classifying it among the habits most harmful to enamel due to the combined effect of cold and mechanical pressure. Observational studies conducted on pagophagia (the compulsive need to chew ice) confirm a high rate of dental fractures and deterioration of crowns or fillings. The thermal shock phenomenon mentioned is also real: cold causes a contraction of the enamel which, under the pressure of mastication, promotes the appearance of fatigue micro-cracks. Finally, clinical reports validate that repeated chewing of hard elements fatigues the temporomandibular joint, which can generate muscle tension and headaches. The creator's explanations therefore accurately describe well-documented physical mechanisms.

the sources

No named source held this one up — that absence is part of the verdict.