Most experts on this topic state that the pain of DH is in reality a normal, physiologic response of the nerves in a healthy, non-inflamed dental pulp in the situation where the insulating layers of gingiva and cementum have been lost; i.e., dentin hypersensitivity is not a true form of allodynia or hyperalgesia. To contradict this view, not all exposed dentin surfaces cause DH. Others suggest that due to the presence of patent dentinal tubules in areas of hypersensitive dentin, there may be increased irritation to the pulp, causing a degree of reversible inflammation.