The excessive loss of Branemark fixtures in type IV bone: a 5-year analysis.

The predictability of branemark implants has been well documented. High success rates in the maxilla and mandible in fully and partially edentulous patients can be expected. A host of factors may be attributed to the etiology of fixture loss. However, the quality of bone stands out as the single greatest determinant in fixture loss. Types I, II, and III bone offer good strength. Type IV bone has a thin cortex and poor medullary strength with low trabecular density. Ninety percent of 1,054 implants placed were in Types I, II, and III bone. Only 3% of these fixtures were lost; of the 10% of the fixtures placed in Type IV bone, 35% failed. Presurgical determination of Type IV bone may be one method to decrease implant failure.