ODONT. ‡ THE POSITIONAL CHANGES that may occur in the gingiva following scaling, root planing, and oral hy giene (such as recession, reattachment, and variations in gingival width, pocket depth, and location of the mucogingival junction) have not been studied system atically. However, it is generally assumed that some gingival recession and/or some change in crevice or pocket depth may occur after scaling and root planing and that there is no change in the position of the mucogingival junction. The location of the free gingival margin, the crevice depth, and the position of the mucogingival junction can be determined accurately with the cementoenamel junction as a fixed reference point. 1-5 Thus, it is possible to evaluate clinically any biometric changes in the relationships between these structures before and after scaling, root planing and oral hygiene. Recent reports indicate a tendency for the width of the attached gingiva to increase with age. 6,7 Teeth in labial version and teeth with adjacent muscle attach ment and/or frenum involvement of the attached gin giva, generally have a narrow zone of attached gingiva. 8 With orthodontic hypereruption of teeth, the width of the attached gingiva may be increased with no change in the position of the mucogingival junction. 9,10 Var ious mucogingival surgical procedures, 11-21 may also increase the width of the attached gingiva, changing the position of the mucogingival junction. The effects of other periodontal procedures on the width of at tached gingiva and mucogingival junction are not known. The purpose of the present study was to assess certain clinical changes that will occur in the gingiva after scaling, root planing, and oral hygiene in areas of advanced or severe gingival inflammation. The param eters studied were location of the mucogingival junc tion, crevice depth, attachment level, height of the gingival margin, and width of the keratinized gingiva. MATERIALS AND METHODS * This study was submitted to the Horace H. Rackham School of Graduate Studies, The University of Michigan, by the senior author in partial fulfillment of the requirements for the degree of Master of Science in Periodontics.