The aim of this patient-based study was to assess the effect of fixed splinting of mandibular premolars having reduced alveolar support on load distribution in the periodontium. A patient's mandibular second premolar with considerably reduced alveolar bone height was restored using a metal-ceramic restoration splinted with the adjacent first premolar; an acceptable 3-year maintenance period was observed. A patient-based three-dimensional finite element model was constructed using the morphological measurements obtained from the diagnostic cast and radiographs. The model incorporated in vivo occlusal records and was used to analyze stress and strain in the periodontium for splinted and nonsplinted simulations. Modified models were also created to explore the effects of relative bone height on the stress and strain distributions. The maximum principal stress and strain on the periodontium of the second premolar were considerably higher before splinting than after splinting and were close to strain levels indicative of potential bone microdamage. In contrast, the stress and strain in the first premolar increased after splinting. The modified models showed that the increased vertical gap of alveolar height between the splinted teeth was another factor to increase the load in the first premolar. Since the prosthodontic procedure employed is not routinely used, the results cannot be generalized. However, it is suggested that fixed splinting can decrease the periodontal load on premolars with reduced periodontal support, but may increase the load on the splinted tooth.