Gingivitis is the most prevalent type of periodontal disease and the dental plaque is considered as a major contributory factor. As the poor oral hygiene is firmly related to the occurrence of periodontal disease, pediatric dentist should make every effort to promote the oral health and control the plaque effectively for the high risk patients, especially for those who are under orthodontic treatment. P.M.T.C.(Professional Mechanical Tooth Cleaning), introduced by Dr. P. Axelsson in 1969, is a very effective method of plaque removal and can be performed by specially trained personnel. Two pediatric orthodontic patients were treated by P.M.T.C. for the elimination of gingivitis and gingival swelling. Signi ficant improvements of gingival condition were achieved in both cases but additional preventive programs and home care along with professional office care seem to be necessary for the best result.