Biologic width is common term for epithelial and connective tissue attachment. Some authors also include and gingival sulcus in biologic width. As dimensions of biologic width is not the same at all individuals, average value of three mm is used in clinical practice. There is one mm for connective tissue attachment, one mm for epithelial attachment and one mm for gingival sulcus. Those dimensions are very important for the health of dento-gingival complex. The violation of biologic width is, most commonly, result of improper prosthetic therapy. Inadequately prepared gingival margin of the tooth, or irregular seat of prosthetic crown can cause tissue damaging, plaque accumulation and, as a result, chronic inflammation of periodontal tissues. When the gingival margin of the prosthetic crown is placed subgingivaly, there is a big possibility of biologic width violation. The most common consequences are: gingival recession, periodontal pocket, hiperplasion and bleeding of gingiva and bone resorption. Procedures used for regeneration and building adequate dimensions of epithelial and connective tissue attachment can be surgical and orthodontic. Surgical are faster, however, esthetic results are very questionable. Whichever method is chosen, adequate oral hygiene is necessary.