"THE IMPORTANCE OF BIOLOGIC WIDTH"
The Term "Biologic Width"
The primary significance of biologic width is its importance in the placement of fillings, crowns or porcelain veneers. If any restoration is placed too deep below the gum and more correctly, too close to the bone, so that it "invades or violates" the biologic width, two possible outcomes may occur. One, there may be loss of bone around a tooth. This is the typical response seen in implants.
Around teeth, the most common response to biologic width violation is gingival (gum) inflammation, a significant problem with crowns and porcelain veneers on the front teeth. This is by far the more common response we see.
Diagnosing a Biologic Width Violation
When we see restorations on the front teeth, particularly crowns that have significant gingival (gums) inflammation or puffiness, there may be series of possible causes:
It could be plaque control, but if the adjacent teeth have healthy gingiva, that is unlikely
it could be a poorly fitting crown, which can be determined easily with an xray and exam
It could be poor contours or a bulky shape, preventing adequate cleaning, again possible to examine
It could be an allergic response to the restorative material, especially if the restoration was done in the '80's or 90's using a nickel-containing alloy and if the patient is female.
But it could be because the crown is placed too far under the gingiva, violating the biologic width.
Ideally, if the existing restoration is removed and a well-fitting temporary crown, for example, is placed for at least three months without the return of any gingival inflammation, you would assume the crown was not too far under the gum.
eciding if the restoration is Violating the Biologic Width may involve either removing the restoration and measuring the depth of the restoration below the gingiva OR by leaving the crown in place and using a periodontal probe.
Since most of us would prefer to know without removing a crown, a number of other options are available to assist in deciding if the crown location is the problem.
First, a periodontal probe placed under the gum alongside the bottom of the crown will elicit soreness if the crown is too far under the gum.
Next, an x-ray may be helpful.
Third, "freezing" the gums around the tooth with the crown in question allows Dr. Friedman to place the periodontal probe well under the gums to measure and thereby determine precisely if a violation of the biologic depth has occurred.
If it is determined that the biologic width has been violated, the only thing that can be done to eliminate the inflammation is to correct the problem.
Surgical & Orthodontic Correction
of a Biologic Width Violation
hen a crown of filling or any restorative material is placed too far under the gum and gingival inflammation occurs, the only solutions to
eliminate the inflammation are to move the edge of the crown under the gum away from the bone called orthodontic extrusion or forced eruption, or move the bone away from the edge of the crown, or filling, etc. called crown lengthening.
The black line represents the edge of the crown under the gum. The green dotted line is the base of the pocket. The crown is placed too far beyond the pocket and too close to the bone which supports the tooth.
Commonly, Dr. Friedman treats teeth visible in the smile by orthodontic extrusion because in crown lengthening where the bone is being reduced and therefore, in essence moved away from the crown, or any other restorative material such as a filling or veneer, there is a loss of the papilla. The papilla is that pink gum, triangular in shape, that separates the teeth and the result can often be unsightly "black triangles."
Rapid Orthodontic EXTRUSION will take approximately four months. And most importantly, the bone between adjacent teeth is preserved so the papilla is preserved.
Crown LENGTHENING is a 60 minute procedure. The gums are fully healed and ready for further treatment in six weeks. However, the teeth adjacent to the treated teeth also see a loss of bone. In both treatments, the amount of tooth root in bone is being reduced. Crown lengthening affects one tooth, but crown lengthening leads to three teeth with reduced bone support.
One last important point to ponder. If a tooth has broken, root canal treatment followed by a post and "build up" may be needed treatment, but the reasoning behind orthodontic extrusion or crown lengthening remains valid and may be necessary to avoid inflammation and ensure a tooth stays strong after it is restored with a crown.