Replacement of the Condyle and Ascending Ramus by a Modular Endoprosthesis in Macaca fascicularis—Part 2: Microcomputed Tomographic and Histologic Evaluation of the Ramus and Stem
Purpose
The present study presents the microcomputed tomographic and histologic evaluation of the peri-implant tissues of a modular endoprosthesis used to replace the condyle and ascending ramus in Macaca fascicularis.
Materials and Methods
The right condyle and ascending ramus were resected in 8 adult monkeys and replaced by a modular endoprosthesis, fixed with polymethylmethacrylate bone cement (Palacos). Four monkeys were sacrificed at 3 months and 4 at 6 months postoperatively. Microcomputed tomographic scanning was performed to analyze the bone volume at the bone–cement interface. Histologic and histomorphometric assessments were done using a modified hard and soft tissue grading scale and by studying the total bone contact at the interface.
Results
The combined (buccal, lingual, and inferior) mean bone volume percentage of the 6-month group was significantly greater than that of the 3-month group (P < .05). The 6-month specimens showed a reduced inflammatory response and more abundant bone formation around the stem. The total soft tissue histologic score was significantly greater in the 6-month group (P < .05). A total bone contact percentage of 15.4% to 85.2% was achieved in 3 specimens.
Conclusions
Satisfactory bone growth was found at the bone–cement interface at the stem region, although direct bone contact with the cement was not achieved in all cases. Soft tissue contact with the prosthetic ramus, in the form of a fibrous capsule, was present in some areas. At 6 months, minimal interfacial inflammation was found in this monkey model.
⁎Senior Consultant, National Dental Centre, Singapore, Singapore
†Registrar, National Dental Centre, Singapore, Singapore
‡Emeritus Professor, University of Hong Kong, Hong Kong, People's Republic of China; Research Advisor and Visiting Consultant, National Dental Centre, Singapore, Singapore; Professor, Prince of Songkhla University, Hat Yai, Thailand; and Advisor, Tideman Maxillofacial Centre, Hong Kong
§Professor and Chairman, Department of Periodontology and Biomaterials, Radboud University Nijmegen Medical Centre, Nijmegen, The Netherlands
¶Emeritus Professor, Department of Oral and Maxillofacial Surgery, University of Nijmegen, Nijmegen, The Netherlands; and Emeritus Professor, Department of Oral and Maxillofacial Surgery, University of Maastricht, Maastricht, The Netherlands
Address correspondence and reprint requests to Dr Goh: Department of Oral and Maxillofacial Surgery, National Dental Centre, 5 Second Hospital Avenue, Singapore 168938 Singapore
This study was supported by grants from the National Medical Research Council/National Dental Centre (grant NMRC/EG/NDC/2005/06/supplementary) and Singhealth Foundation (grant SHF/SP001/2007).
ABSTRACT