Blood groups - blood cells from different people do not always have the same cell surface antigens. A transfusions of blood whose antigens do not match the recipient evokes an immune response and the donor cells are broken down. Two of the common blood groups are the A,B,O group and the Rh group. The blood group antigens are glycoproteins or glycolipids.

Bolus - a piece of food which is being chewed to break it down into small pieces.

Bone membrane - a theoretical membrane separating the fluid surrounding bone crystals from the fluid of the surrounding connective tissue. The membrane would be formed by the endosteum.

Bone morphogenic proteins (BMP) - part of the cytokine family of transforming growth factors. BMP have a powerful ability to cause differentiation of stem cells into osteoblasts and to initiate bone formation.

Bradykinin - one of several substances, all known as kinins, which cause vasodilation and increased capillary permeability, both events associated with inflammation.

Buffers - chemical which are able to keep the pH of a solution within a normal range, neither acid nor alkali. Salivary buffers are important in reducing the progress of caries by neutralising plaque acids.

Buttress- an arch shaped support, used by builders of bridges and churches in the days before steel.