Statement of problem. Treatment of tooth loss in the anterior maxilla can involve difficult functional, esthetic, and psychological problems, especially in young patients with otherwise good dentition. Purpose. The purpose of this study was to provide a comparative evaluation of two different implant system (Biohorizons and Dentium) with zirconia abutment in cemented single-tooth restorations. Material and methods. This prospective study of 45 single-tooth replacements with 22 Biohorizons and 23 Dentium dental implants was performed in 30 patients. The patients were selected from the outpatients' clinic, Faculty of Dental Medicine, Al- Azhar University during the period October 2010 to October 2013. The custom zirconia abutments were fabricated. The restoration was an all ceramic crown for cementation with a framework in zirconia. The first clinical and radiographic follow up was performed one week after crown placement for all patients (baseline examination) then at four, eight and twelve months after crown placement, all patients were recalled and participated in the annual examination. Results. The clinical parameters (plaque and peri-implant
gingival indexes) measured at the baseline and 1-year follow-up examination showed non significant differences in Biohorizons and Dentium and gave a satisfactory results. There is a significant difference in probing depth where the Biohorizons gave better result. The bone loss in Biohorizons was lesser than that in Dentium. The mean marginal bone loss was slightly higher (non significant) in the maxilla for both implant systems. During the 1-year follow up period, the survival rate was 100% in Biohorizons implant system and 95.6% in Dentium implants. The titanium screws that attached the abutment to implant were loosened within a few months of insertion of the permanent crown in two cases of Dentium implant. Subjectively all patients were satisfied with their single-tooth restorations supported by both dental implants. Conclusion. Within the limitation of the present study, favorable results obtained with the application of the Biohorizons implant system that supported cemented single-tooth crowns with custom zirconia abutment especially in the anterior region of the maxilla. Further studies are necessary to evaluate the long-term success.