In vivo early plaque colonization on smooth titanium surface

Plaque development on pure titanium in a 24-hour period is described in an in vivo human model. Stents with titanium and root cementum specimens were applied to volunteers, who suspended oral hygiene procedures for 24 hours. The specimens were removed at 2, 4 and 24 hours and studied with a scanning electron microscope. A global area of 240 μm × 300 μm, composed of the sum of twelve 20 μm × 25 μm fields randomly selected, was examined for each specimen. The presence of cocci, short rods, long rods and bacterial aggregation, and bacteria density was recorded for each field. The values quoted for the global area were cumulative of those observed in the fields. At 24-hours, significantly less bacteria was recovered from the titanium than from the corresponding root cementum specimens. The early colonizers of titanium were cocci, frequently located in the roughest part of the specimen. Visible salivary pellicle formation was delayed on the titanium compared to the cementum surface. At 24-hours, fewer rods were recovered from the titanium than from cementum surfaces. These results suggest that early plaque formation is reduced on titanium surface and that morphological irregularities are critical for bacterial adhesion and colonization.