Abstract: To fill a canal, an optical fiber having a low melting point is introduced into the canal and radiation is conducted through the fiber to melt the fiber and form the filling. The fiber may be coated with a material which will be melted by the radiation and will bond to the canal wall. Fillings and coatings are formed on tooth or bone tissue by projecting toward a surface of the tissue two starting components which when combined and exposed to light of a selected wavelength undergo a photochemical reaction to form a calcium containing product, and causing light of the selected wavelength to impinge on the components at least partially before they reach the surface in order to create the reaction and cause the resulting calcium containing product to bond to the tissue.