HISTOLOGICAL INVESTIGATION

 

OF A MANDIBLE WITH 6 BICORTICAL SCREW IMPLANTS

(post-mortem)

 
 

Mandible with 6 bicortical screws and mounted bridge made of metal and isosit 10 years in situ. The mandible was cut in vestibulo oral direction in small slices in the region of the bicortical screws.

Histologically

The oral mucosa has good contact with the metal surface of all implant. There are no vertical bone pockets. The connective tissue between the proliferated epithelium and bone consist of circular running collagen fibres around the implant surface, which are mostly hyalinized.

Outside of this narrow connective tissue zone there are collagen fibres parallel to the implant surface which run from the bone to the mucosa. The compact bone in the margin is in direct contact to the implant surface. There is no connective tissue between bone and implant surface. Only around the implant region 31 is there no direct bone contact to the implant surface. The connective tissue in the bone pocket contains bone sequester surrounded by epithelium. The apical part of the screws of region 31,44 e 45 are embedded in the basal cortical bone. The cortical bone in the margin and base of the screws show remodeling processes with cement lines running differently and inclusion of small bone particles in the newly-formed bone.  Plump spongeous bone has developed on the highest level of the screw. The body of the screw has little bone contact. The bone-free implant surfaces are covered by thin connective tissue containing 3-4 cell layers of fibrocytes.  Between the connective tissue and the implant surface there are small spaces with single and multinuclear macrophages.

Microfractures have developed mostly in the spongeous bone which show resorption an newly-formed bone. The bone marrow consists of fat tissue and contains some bleeding residue. The density if spongeous bone is elevated in the periphery of the implants of region 31,44 and 45. There is no complete bone contact to the surfaces of bicortical screws which can clearly be seen in the cross-sections of the implant of region 41. Bone-free implant surfaces occasionally contain corrosion products which are separated by connective tissue from the bone marrow.

Conclusion

Loaded bicortical screws in the mandible for 10 years with a good epithelial and connective tissue attachment, good bone contact in the margin and basal cortical bone with fluid-filled spaces between bone and implant surfaces, sign of remodeling in the cortical bone, microfractures with signs of repairing in the spongeous bone.

Clinical Evaluation

The Patient, a 75-year-old women was referred by her medical Doctor for examination of the edentulous jaw bone for possible treatment with implants. Her maxilla was supported with a full denture that functioned well. The Patient had major problems with her total denture in the mandible. The anatomy of the alveolar ridge was high an very narrow. (bucco lingual) which led me decide to use 6 bicortical screws on which i mounted a 10-part bridge. The Patient, who came regularly for check-ups, was satisfied with this treatment.

The implants was placed 10.03.1980.

The mandible was dissected from corpus 15.02.1990, good 10 years from insertion day.

Finally, I want to draw your attention to the post-mortem investigation.

region 31
region 41
region 44
region 45