Q. Rigid fixation to evaluate osseointegration?
Is a clinical term that means absence of observed mobility. Rigid fixation indicates the absence of clinical mobility of an implant that was tested with vertical or horizontal forces under 500g similar to evaluating teeth. Lack of clinically observable movement does not mean the true absence of any movement. A healthy implant moves less than 75 micro meter hence it has zero clinical mobility. The rigid fixation usually means that at least a portion of the implant is in direct contact with bone although the percentage of bone cannot be specified. A mobile implant indicates the presence of connective tissue between the implant and the bone.
Unlike a tooth where mobility is not a primary factor for longevity mobility is a major determinant factor for implant health. Rigid fixation is also an excellent indicator for health status because it is an easy objective test. The technique to assess rigid fixation involves use of two rigid instruments which apply a labiolingual force of approximately 500g. the amplitude of mobility may be measured from 0 to 4.