A new type of porous alumina dental implant has been designed. A biological seal is provided by single-crystal alumina on its cervical portion, and fixation capability in bone is provided by a porous alumina layer with an average interconnecting pore size of approximately 130 μm.
The mandibular premolar and molar extraction sites of 15 male rhesus monkeys (3 to 6 years old) were used in the animal experiments. All the implants and superstructures that were not retained by attachment to proximate teeth participated in functional occlusion at all times except during the first two to four weeks.
After four, six, and eight months, histological examinations, including light microscopy (LM), scanning electron microscopy (SEM), and electron probe microanalysis (EPM), were conducted. The surrounding gingival tissue strongly adhered to the single-crystal alumina on the cervical portion of the implant, and prolific bone ingrowth was observed within the porous network of the root component.
The human clinical evaluations showed a high success rate of 94% in 45 cases. Long-term clinical cases were included, the longest implant having survived for eight years in free-standing form. These cases included 23 free-standing cases and 22 bridge cases; 3 of these failed in the first stage of human clinical trials.