MRGPRD and infection: We chose to assess the Toll-like Receptor 4 (Tlr4), transient receptor potential channels vanilloid 1 and ankyrin 1 (Trpv1 and Trpa1), and the mas-related G protein coupled receptor D (Mrgprd), because all are found in neurons that innervate the dental pulp7,17–21 and could be involved in the development of either spontaneous or mechanical pain in the context of infection and injury.