The objective of this study was to evaluate the periodontal health of the abutment teeth in partial dentures made of Injection molded PEEK framework compared with cobalt chromium framework in mandibular kennedy class I free end saddle edentulous cases. Methodology: Two groups of patients representing Kennedy class I with last standing premolar teeth bilaterally. A conventional cobalt chromium RPD was constructed for each patient in the control group, while PEEK RPD (utilizing injection technology) was constructed for each patient in the intervention group. Periotest used to evaluate the periodontal health of the abutment teeth at the time of insertion and after 3 and 6 months. Results: In the control group, there was no significant difference between values measured at different intervals. The highest value was measured after 3 months, followed by 1 month, while the lowest value was measured at baseline. And the same was for the intervention group as there was no significant difference between values measured at different intervals. The highest value was measured after 1 month, followed by 3 months, while the lowest value was measured at baseline. Comparing the two groups together, there was no statistically significant difference between them. Conclusions: There was an increase in abutment teeth mobility for both groups from zero to three months but finally both RPD frameworks offered acceptable degree of periodontal health preservation. The injected PEEK RPD frameworks provided less degree of abutment teeth mobility with better preservation of their periodontal health.