To evaluate the plaque distribution on the fitting surface of fixed implant prostheses which were supported by multi-unit abutment.

21 patients with maxillary full-arch implant-supported fixed prostheses were collected. Plaque accumulation at the fitting surfaces were evaluated 3 months after restoration, by analyzing the digital photographs recorded by Image J 2.1.4.7.

The average percentage of area covered with plaque was (46.13 ± 7.23)%. Plaque accumulation on the buccal and palatal area were (41.53 ± 3.08) and (53.76 ± 3.07)% respectively, with a significant difference (t = 16.750, P < 0.001). The free area (71.86 ± 2.00) % was significantly higher than the anterior area (48.85 ± 2.09)% (t = 40.445, P < 0.001), andalso the middle area (49.33 ± 0.98)% (t = 47.124, P < 0.001). The plaque percentage was higher when the distance between the implants was shorter.

To Minimize the palatal extension and free area of the prostheses, and to maximize the distances between the implants, were helpful to improve the oral hygiene control. It might be the key to keep a good outcome of the maxillary full-arch implant-supported fixed prostheses.