BACKGROUND : Osseointegrated implants can be prone to occlusal overloading because of the absence of the periodontal ligament and limited tactile sensitivity. However, current scientific evidence of the occlusion variation of implant-supported fixed prostheses is lacking. OBJECTIVE : The purpose of this clinical study was to analyze changes in occlusal force distribution and occlusal contact in single posterior partial fixed implant-supported prostheses over time. METHODS : Partially edentulous patients who had received implant-supported single crowns in the posterior region between December 2012 and December 2013 were enrolled. The participants underwent occlusal examinations by using the T-Scan III system at 0.5, 3, 6, 12, 24, and 36 months after implant prosthesis delivery. The relative occlusal forces (ROFs) of implant prostheses, mesial adjacent teeth, and control natural teeth were recorded, and implant prosthesis occlusion time ratios were calculated. The paired t test was used to compare the implant prosthesis occlusion time ratios and ROFs of implant prostheses at 2 different times as a self-control. The differences in ROFs between implant prostheses and control teeth in the same participant at the same time were also analyzed by using a paired t test. The Pearson correlation coefficient was used to analyze the statistical correlation between implant prosthesis occlusal force and the implant prosthesis occlusion time ratio (α=.05). RESULTS : Thirty-seven posterior partial fixed implant-supported prostheses in 33 participants (18 women and 15 men aged 23.9 to 70 years) were followed up for 3 to 36 months (mean: 31.4 months). The ROFs of implant prostheses increased significantly (P<.05) from 2 weeks (7.46 ±4.21%) to 3 months (9.87 ±6.79%), whereas those of control natural teeth decreased significantly (P<.05) from 13.78 ±6.00% to 11.43 ±5.47%. The ROFs of implant prostheses continued to increase from 6 to 12 months and from 12 to 24 months, with significant differences (P<.05). However, they were statistically similar to those of control natural teeth at 6, 12, 24, and 36 months after restoration. Implant prosthesis occlusion time ratios also increased significantly between 2 weeks and 3 months and between 3 and 6 months (P<.05). No significant differences were found between the other time points (P>.05). CONCLUSIONS : The occlusal force and occlusal contact time of implant prostheses changed significantly with time.