Statement of problems: Partially edentulous patients with distal extension (class I kennedy) show morphological changes in bone height that may be also associated with some difficulties during mastication.Purpose: The present study aim to evaluate the bone height changes around abutments and distal extension area with different denture base materials and to record and compare biting forces associated with it.Materials and methods: Ten partially edentulous patients (kennedy class I) were selected and received two unilateral partial dentures in a split mouth study design in which each patient received one partial denture with conventional metal framework with acrylic resin base and one partial denture with Acetal resin framework and resin denture base. Biting forces was measured using I Load star sensor. Digital radiography was used for bone height assessment at time of prosthesis insertion, 6 and 12 months later.Results: There was a statistically significant difference in bone changes between the conventional and the Acetal RPDs after one year. There was no statistically significant difference in biting forces between the two sides throughout the period of the study.Conclusion: Bone changes were significantly higher with the conventional acrylic partial denture and the Acetal partial denture showed more favorable results. Both types of unilateral partial dentures showed comparable biting forces after one year of clinical use. Keyword: Denture base materials, Removable partial denture, Biting forces, Bone changes.