Biologic width describes the combined heights of the connective tissue and epithelial attachments to a tooth. The dimensions of the attachment were described in 1961 by Garguilo, Wentz and Orban in a classic article on cadavers. Their work showed the connective tissue attachment having an average height of 1 mm, and the epithelial attachment also having an average height of 1 mm, leading to the 2 mm dimension often quoted in the literature for biologic width. In addition, they found the average facial sulcus depth to be 1mm, leading to a total average gingival height above bone of 3 mm on the facial. (Figure 1)
The Term Biologic Width
For historic accuracy, it is interesting to note that Garguilo, Wentz and Orban didn’t use the term biologic width in their 1961 article, the actual name, biologic width, came in 1962 from Dr. D Walter Cohen at the University of Pennsylvania.
In 1994, Vacek did further cadaver studies on biologic width that helped give some insight into the clinical findings many of us had seen. He found that biologic width was relatively similar on all the teeth in the same individual from incisors to molars, and also around each tooth. He also found the average biologic width to be 2 mm as the Garguilo group did. What Vacek found that is clinically important was that biologic width varied between individuals, with some having biologic widths as small as .75 mm, and others as tall as 4 mm, but statistically the majority followed the 2 mm average.
The primary significance of biologic width to the clinician is its importance relative to the position of restorative margins, and its impact on post surgical tissue position. We know that if a restorative margin is placed too deep below tissue, so that it invades the biologic width, two possible outcomes may occur. One, there may be bone resorption that recreates space for the biologic width to attach normally, this is the typical response seen in implants to allow the formation of a biologic width, the so-called funnel of bone loss to the first thread.
Around teeth the most common response to a biologic width violation is gingival inflammation, a significant problem on anterior restorations. (Figure 2) The importance of biologic width to surgery relates to its reformation following surgical intervention. Research shows it will reform through coronal migration of the gingiva to recreate not just the biologic width, but also a sulcus of normal depth. This means if the surgery doesn’t consider the dimensions of biologic width when placing the gingiva relative to the underlying bone, the gingival position won’t be stable, but instead will migrate in a coronal direction. In this example, it also has a strong influence on when and where restorative margins should be placed post surgically.
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