A. Embrasure - The open space between the proximal surfaces of two adjacent teeth in the same arch, where they diverge facially or lingually, and incisally (occlusally) or cervically from the contact area.
B. Embrasures are named according to their location, which depends on the aspect from which the teeth are being viewed. When viewing the teeth from either the facial or lingual aspects, the two embrasures which may be observed are the incisai (occlusal) and cervical (gingival) embrasures. The cervical embrasure corresponds to the interproximal space, and is normally larger in area than the incisai (occlusal) embrasure.
When viewing the teeth from the incisai or occlusal aspect, the two embrasures which are visible are named labial (buccal) and lingual embrasures.
1. Marginal Gingiva
2. Gingival Line
3. Interdental Papilla
4. Gingival Embrasure
5. Contact Area
6. Clinical Crown
7. Incisal/Occlusal Embrasure
8. Anatomical Crown
9. Interproximal Space
10. Cervical Line (CEJ) 1 1. Alveolar Bone
C. Ideally, if an imaginary line is drawn to bisect any embrasure space, the two portions so described should be approximately equal in size and shape, or in other words they should be symmetrical. This is extremely important when planning or performing dental operations, for if one side of the embrasure is contoured differently than the other, it may affect the health of the periodontium. For example, if the dentist finds that the outline of one of the adjacent teeth is slightly convex, the restoration placed on the other tooth should also be slightly convex in this area. In addition, asymmetrical embrasure form in the anterior teeth may compromise esthetics.
Bisected info Symmetrical
Bisected info Symmetrical
D. Proper embrasure form has two main physiological purposes:
1. To serve as a spillway for the food material during mastication.
2. To serve as an integral part of the self-cleaning process of the teeth. These two purposes are interrelated, and tend to complement each other in both the protection and stimulation of the periodontium. Improper embrasure form may result in a lack of protection, with resultant overstimulation of the periodontium, and its potential breakdown. Overprotection, with a resultant lack of stimulation of the periodontium, also may result in its breakdown.
In the anterior part of the mouth, embrasure form is also a factor in the esthetics function of the human dentition.
E. Some general rules regarding normal embrasure form are as follows:
1. From the facial or lingual aspect, incisal (occlusal) embrasures increase in relative size from the anterior teeth toward the posterior.
2. From the facial or lingual aspect, cervical (gingival) embrasures decrease in relative size from anterior to posterior.
3. From the incisal aspect, the labial and lingual embrasures are nearly equal in size in anterior teeth.
4. From the occlusal aspect, the lingual embrasure is normally larger than the buccal embrasure in posterior teeth.
5. When one side of an embrasure (tooth outline) has a certain contour, the other side of the embrasure will normally have a similar contour.
F. It should now be easy to recognize the interrelation between contact areas and embrasure form. For example, as the contact area becomes more cervically located the farther posteriorly in the arch, the relative size of the incisal (occlusal) embrasure increases, while the relative size of the cervical embrasure decreases. And, as the contact area moves farther to the buccal in the posterior teeth, the lingual embrasure becomes relatively larger.
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