Denture fixative cream and the potential for neuropathy (dent update 2012; 39: 575–577)

Neurological deficits due to copper deficiency are increasingly recognized with excess zinc from denture adhesives1 being one of several common causes.2 We commend Shammaa and Rodgers for highlighting this issue.3

The authors discuss the role of zinc as an enzyme co-factor. Copper is also a co-factor,4 which may explain the haematological and neurological abnormalities.2^,5 Haematological manifestations include anaemia and, less commonly, neutropenia and thrombocytopenia, all of which can affect the safety of dental procedures. Neurological manifestations are best characterized as myeloneuropathy as the term ‘human swayback disease’, alluding to a similar condition in ruminants, is rarely used. They may be mistaken for vitamin B₁₂ deficiency.5

Zinc is used in denture adhesives to improve adhesion and, notably, all reports of copper deficiency are in the context of excessive use with ill-fitting dentures. In May 2012, we surveyed the product literature of denture adhesives available in the UK and wrote to the manufacturers to enquire about whether zinc was ever present (Table 1).

Thus the majority of products available in the UK are now zinc-free. GSK confirmed that this had been the case since February 2010 but Coombe did not confirm whether their products had ever contained zinc. Fixodent (Procter & Gamble) still contains zinc, although the product literature has a detailed warning about overuse. The condition is therefore likely to become less common, although early recognition and treatment remain key, as with treatment the deficit may only stabilize or partially improve.2