Objective: The aim of this study is to investigate whether orthodontic extrusion movements have negative effects on the periodontal tissues, and to detect the relationship between orthodontic tooth extrusion and the width of the keratinized gingiva. Materials and Methods: Fourteen upper canines of seven patients having different Angle classifications were selected for the study. According to the abnormal position of those canines they were subjected to orthodontic extrusion forces in order to bring them back to a normal level within the dental arch and, therefore, to correct the abnormality. Plaque index, probing depth, gingival index, papillary bleeding index and keratinized gingiva width were measured around the examined canines at baseline, one month, 3 months and 6 months after the initiation of the extrusion movements. Results: The values of plaque index and gingival index increased significantly during the whole period of study, whereas the probing depth and papillary bleeding index values did not show any important differences. A very slight increase in the keratinized gingiva width of about 0.14 mm was detected at the examined teeth after 6 months compared to baseline without any statistical significance. Conclusion: No negative effects on the periodontal tissues were noted around the canines during the application of orthodontic tooth extrusion. A very slight increase of the keratinized gingiva width was detected at the examined teeth after 6 months comparing to baseline without any statistical significance. [ABSTRACT FROM AUTHOR]