Preparation of Interpenetrating Phase Composites (IPC) for dental restorations is complex and time consuming, suggesting a preference for alternative materials. The purpose of this study was to investigate the structure and mechanical properties of an IPC used in dentistry (InCeram) as well as a novel alumina-polymer IPC designed to provide a simpler, lower cost alternative material for dental restorations. Porous samples were prepared with variations in sintering temperature and then infiltrated with InCeram glass or with a specifically formulated resin mixture. Four point bending tests were carried out on all samples. The novel IPC displayed lower strength and elastic constant but higher toughness than InCeram IPC. Higher Weibull modulus values were calculated for novel IPCs suggesting better reproducibility of these composites. Degradation experiments demonstrated the sensitivity of both IPCs to moist environments. These results suggest that the novel IPC may be useful for some dental restoration applications.