MARCH 1998 353 THE JOURNAL OF PROSTHETIC DENTISTRY T he evidence that some persons clench their teeth is not difficult to find. Patients may not be aware of it and may even deny that they do it. Clenching will result in a scalloped design inside the mouth on the cheeks and on the lateral and anterior borders of the tongue, which can be easily detected on oral examination (Fig. 1). The wear facets on the teeth that result from clench- ing are distinctive in that they are very small and should not be confused with bruxing facets, which cover a much larger portion of the involved teeth. The scalloping is caused by making a vacuum with the tongue. It can be easily demonstrated that a vacuum is required to clench the teeth. If one is asked to clench the teeth and hold them very firmly together for a few sec- onds with the lips closed, the tongue will usually be found thrust against the palate and anteriorly and laterally against the lingual surfaces of the teeth and thus a vacuum is made with the tongue. If the tongue is held away from the anterior palate so that a vacuum cannot be achieved, the person’s protective reflexes will usually prevent biting hard for more than a few seconds. For a person to con- tinue to clench the teeth, a vacuum must be maintained. It is difficult to completely understand what causes a person to clench. Among the probable causative factors are “tension” or the temperament of the person, and the anxieties or frustrations faced at that time. An uncom- fortable occlusal relationship may also be a causative fac- tor. Whatever the cause, clenching is destructive. It can cause wear, mobility, and sensitivity of the teeth. Several things can be done to prevent the harmful ef- fects of the habit. If a malocclusion is a causative factor, occlusal adjustment may reduce the degree and inten- sity of the clenching. Biofeedback training can result in some muscular relaxation. Properly designed interocclusal splints may reduce muscular activity or damage to the teeth from clenching when being worn. This article describes a procedure for fabricating an intraoral device that will prevent the formation of a vacuum in the oral cavity. Because a vacuum is neces- sary for the patient to clench the teeth for an extended period, its absence will eliminate the patient’s ability to clench the teeth. a Private practice. A device to prevent jaw clenching James Hart Long, Jr., DDS a Daytona Beach, Fla. This article describes a device that is intended to prevent the clenching of the teeth. The principle involved is that to clench the teeth for an extended period, an intraoral vacuum must be formed and maintained. A tube or drinking straw held between the lips extending out of the mouth will prevent a vacuum. The article explains and illustrates how such a device can be made that will exploit this principle. Disadvantages and advantages are discussed. (J Prosthet Dent 1998;79:353-4.) PROCEDURE 1. Obtain some lengths of 1 /16 inch diameter stainless steel wire from a welding supplier and cut a piece to measure approximately 14 cm long. 2. Bend the piece of wire, beginning in its center, to follow the labial contour of the mandibular teeth. 3. At the distal surface of the second premolar, double each end back forward so that these extensions are roughly parallel to each other (Fig. 2). 4. Cut two pieces of a plastic drinking straw 2.5 cm in Fig. 1. Example of scalloping on border of tongue. Fig. 2. Contoured 1 /16 inch wire overlaying 1 mm graph paper to show its size.