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.
OBJECTIVE
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.


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.
Goh
Bee Tin
BT
National Dental Centre, Singapore, Singapore. gohbee@starhub.net.sg
Lee
Shermin
S
Tideman
Henk
H
Jansen
John A
JA
Stoelinga
Paul J W
PJ
D000818:Animals; D005549:Foreign-Body Reaction / Q000473:pathology; D007249:Inflammation / Q000473:pathology; D008252:Macaca fascicularis; D008297:Male; D008334:Mandible / Q000000981:diagnostic imaging / Q000473:pathology / Q000601:surgery*; D008335:Mandibular Condyle / Q000601:surgery; D008341:Mandibular Prosthesis; D020366:Methylmethacrylate; D010012:Osteogenesis; D011474:Prosthesis Design; D055114:X-Ray Microtomography
D020366:Methylmethacrylate