If a patient has all crowns on their upper and lower teeth, what might be the primary issue if there are complaints?

When a patient has all crowns on their upper and lower teeth and experiences complaints, the primary issue often relates to the impingement on the gums caused by the crown margins. Crowns can sometimes extend too far beyond the gingival margin, irritating the surrounding gum tissue and leading to inflammation or discomfort. This is particularly critical in cases where the crowns are not properly contoured or where they create localized pressure points against the soft tissue.

Inadequate oral hygiene can indeed lead to problems, but if the crowns are fitted correctly, patients can maintain hygiene effectively. Improper alignment of teeth concerns the overall occlusion and how upper and lower teeth fit together; while this can create issues, it is a secondary concern compared to direct impingement on the gums. Excessive crown height might cause functional issues like bite discomfort or articulation problems, but the most immediate concern with complaints typically relates to how the crowns interact with the gums. Thus, impingement on the gums stands out as the primary issue in the context of the given options.