What is the primary reason for observing spacing between teeth after scaling and root planing?

After scaling and root planing, observing spacing between teeth is primarily due to the reduction of edema. When periodontal disease is present, the tissues surrounding the teeth can become inflamed and swollen, leading to a condition known as edema. Scaling and root planing involves the removal of plaque and tartar from beneath the gum line, which helps to decrease inflammation and promote healing of the gingival tissues.

As the edema subsides post-treatment, the gum tissue returns to a more normal shape and size, which can create the appearance of increased spacing between the teeth. This is an important aspect of post-treatment assessment, as it not only indicates improved periodontal health but also helps in evaluating the effectiveness of the treatment.

The other options do not directly relate to the primary outcome observed after proper scaling and root planing. While checking for broken teeth or assessing for decay are important dental evaluations, they are not specifically the result of the treatment's effect on soft tissue health. Similarly, determining the need for dentures is a consideration that typically arises in advanced tooth loss scenarios, rather than the immediate outcome of non-surgical periodontal therapy.