Purpose

Customized abutments made by CAD/CAM method are widely used in implant dentistry. However, there is not sufficient data about long-term follow-up in patients with implant prosthesis using CAD/CAM abutment. In this study, the retrospective study is executed in patients using customized abutment for 4 years of follow-up

Materials and methods

A. Materials
1. Patient assessment
129 patients had treatment of fixed implant prosthesis with CAD/CAM customized abutment at Chosun University Dental Hospital. The follow-up for 19 patients among 129 patients was not accomplished, so 110 patients had gone through 4 years of follow-ups.

2. Implant evluation
271 implants of five brands (Astra, Biomet 3i, Zimmer, Dentis, Osstem) were evaluated according to splinting and location of implant fixture.
B. Methods
Patients were examined periodically at 3, 6 months, 1, 2, 3, 4 years after the final placement of the implant. Radiological evaluation for bone loss according to splinting and location of implant fixture and clinical evaluation (abutment fracture, screw loosening, screw fracture, porcelain veneer fracture, retention loss of prosthesis, contact point loosening, implant failure) according to splinting and location ofimplant fixture were performed.

C. Statistic Analysis
Statistical analysis was performed with SPSS Ver. 22. 0

Results

A. Radiographic evaluation
1. The amount of bone loss according to splinting
The mean cumulative bone loss in the non-splinting implant group was 0.27 mm, in the splinting implant group was 0.50 mm. There was no statistically significant difference between the groups.
2. The amount of bone loss according to location of implant fixture
The mean cumulative bone loss in the maxillary anterior part was 1.37 mm, maxillary posterior part was 0.39 mm, mandibular anterior part was 0 mm, mandibular posterior part was 0.30mm. There was statistically significant difference.

B. Clinical evaluation
1. The clinical prosthesis evaluation according to splinting
Prosthesis evaluation analyzed by chi-square test. With this result, statistically significant difference was observed in screw loosening.
2. The prosthesis evaluation according to location of implant fixture
Prosthesis evaluation analyzed by chi-square test. With this result, statistically significant difference was observed in porcelain veneer fracture and retention loss of prosthesis.
Conclusion

① The amount of bone loss was greater in the splinting group than the non-splinting group
② The amount of bone loss was greater in the maxillary anterior part than another group
③ Screw loosening was less in the splinting group than the non-splinting group
④ Prosthesis deformation and retention loss of prosthesis were greater in the maxillary anterior part than other group