Mapping remodeling reversals with the aid of the scanning electron microscope

The histologic research on craniofacial remodeling is briefly summarized. A new methodologic approach using the scanning electron microscope (SEM) and high-resolution replicas of craniofacial bone is evaluated. Two maxillae were chosen for illustrative purposes. The specimens were replicated and prepared for routine SEM examination. In addition, a grid was applied to the replicas so that the bone growth activity states could be mapped on a coordinate system. The topographic ("T") principle is introduced as a precedent for discriminating remodeling bone growth activity states with the SEM. These activity states in vivo specify characteristic microscopic surface topographies. The three distinctive surfaces are resorptive, depository, and resting, which are mapped on a coordinate system. Results obtained are similar to those of histologic studies. The primary advantage of the SEM/replica technique is that it does not damage the specimen. This feature will facilitate more extensive investigations of craniofacial remodeling. The time and financial investments for the SEM/replica technique are significantly less than for the histologic technique in the investigation of similar material. The SEM/replica technique, however, cannot be used to study nonexternal surfaces and evidence of remodeling contained within the bone cortex.