What is typically the cause of a 1-2 mm reduction in probing depth after scaling and root planing?

A reduction in probing depth of 1-2 mm following scaling and root planing is typically indicative of the formation of a long junctional epithelium. After this dental procedure, the most common outcome is the healing of periodontal tissues, which can lead to the establishment of a new attachment that consists primarily of long junctional epithelium.

This process occurs as the tissue reorganizes after the removal of calculus and bacterial plaque, allowing the epithelium to migrate and form a new attachment to the tooth surface. Although true periodontal attachment (with supporting connective tissue fibers) may not be formed immediately, the presence of a long junctional epithelium is a common healing response and is often responsible for the observed decrease in probing depth.

The other options generally correspond to different scenarios or effects in periodontal health and do not specifically explain a typical reduction in probing depth following scaling and root planing. For instance, gingival recession results in increased probing depth rather than a reduction, changes in bone density are more complex and might not directly relate to immediate changes after a cleaning procedure, and gingival tissue shrinkage could imply detrimental changes rather than the observed improvement in probing depth. Thus, the long junctional epithelium is the