Microhardness of Class II composite resin restorations with different matrices and light positions.

The degree of polymerization, determined by surface hardness, has been related to the gingival marginal adaptation of posterior composite resin restorations. Poor marginal adaptation results from marginal leakage and failure of the restoration. This study compared the degree of polymerization, measured by microhardness, of a microfilled composite resin placed by use of different matrices.

Biochemical purification and crystallographic characterization of the fiber-forming protein pilin from Neisseria gonorrhoeae.

Pilus fibers are long protein filaments on many pathogenic bacteria that participate in attachment to host cells. Although the self-assembling protein pilin is the major structural component of the Neisseria gonorrhoeae pilus fiber, several other proteins co-purified with pilin through the repeated solubilization-reassociation steps of the biochemical purification. Pilin solubilized in the nondenaturing detergent n-octyl-beta-D-glucopyranoside remained an aggregate of about 100 kDa at pH 9.