RESUMEN
<p><b>OBJECTIVE</b>To investigate the influence of three pontic types on alveolar ridge mucosal microecosystem.</p><p><b>METHODS</b>Sixty patients ready to accept three unit metal ceramic bridges were selected. The bacterial type and the cultivable flora were counted and the proportions of bacteria detected on the top of alveolar ridge mucosal contact area before tooth preparation and three months after bridge insertion.</p><p><b>RESULTS</b>Type and CFU of bacteria on the alveolar ridge mucosa under modified base-type pontics and modified ridge lap pontics increased significantly (P < 0.05); while there was no significant change under the ovata pontics (P > 0.05). Before tooth preparation and 3 months after fixed prosthesis insertion, the percentages of oral Streptococci and Neisseriae changed significantly (P < 0.05).</p><p><b>CONCLUSIONS</b>The ovata pontic had less influence on mucosal microecosystem than the other two pontics and is the appropriate pontic design for clinical dentist.</p>