184 Theories and techniques of oral implantology

Fig. 5-96. In a diagrammatic cross section, the button is shown in relation to the denture and various tissues. (From Cranin, N.: The intramucosal insert—review and progress report, J.A.D.A. 62:658-665, 1961. Copyright American Dental Association. Reprinted by permission.)

close condensation around the necks of the buttons help reduce or prevent displacement of the denture

(Fig. 5-96).

A prosthesis with intramucosal inserts is particularly useful for those patients with abnormal maxillary anatomy or resorption of the maxillary tuberosities and alveolar crest. It has also helped patients with cleft palate and hare lip deformities or injured or diseased jaws and those individuals who have a tendency to gag and who cannot retain a conventional denture. It was originally thought that the buttons provided enough security to eliminate the palatal vault of a maxillary denture. However, only in cases of exceptional retention has this been possible.

Intramucosal inserts, also called button implants, were probably first used by Sven Gustav Adolf Dahl of Stockholm, Sweden. In 1945 Dahl applied for a United States patent for the implant procedure he initiated in Sweden in 1942 (Fig. 5-97). Dahl and a fellow worker, Hans Nordgren, made slots in the mucosa, embedded the buttons in the cuts, and left them there until the sites healed. Eight to ten days later, the buttons were pulled out. The healed gums had

formed ball-shaped pockets around the buttons. These pockets, which corresponded to the buttons now inserted in the plate, were to act in consort to secure the denture against the mucosa.

In 1953, Isaiah Lew and Kestenbaum introduced their "implant button technique," and Norman Cranin also has worked along similar lines with his own inserts. Their techniques were modifications of Dahl's original work and are still in current use.

Before the operative procedures begin, the crest must be clear of any roots, residual infections, or foreign bodies. The sites to receive the buttons are selected by exploring the tissue covering the anesthetized ridge with a sharp millimeter probe (Fig. 5-98). The best sites are areas where the tissue is thickest. Areas with very thin tissue, such as below a low-flaring sinus or in the region of the anterior palatine foramen, should be avoided. Once the receptor sites have been determined, they are marked either with indelible pencil or transfer paste, which is white and contains essential oils of eucalyptus, clove, menthol, and a mucilaginous zinc oxide paste. If pencil is to be used, the ridge is first swabbed with tincture of myrrh and benzoin, a compound that will prevent the pencil marks from smearing (Fig. 5-99). Whatever is used, the marks must be exactly the same size as the button heads.

The denture, already processed, fitted, and balanced, is inserted, and the patient bites in centric relation. The marks, either pencil or paste, transfer to the denture and serve as guides for setting the but-tons into the denture (Fig. 5-100). Before inserting the buttons, some operators prefer to first insert indicator styluses in the denture (Fig. 5-101). These punch tiny holes in the soft tissues to accentuate the receptor sites.

The areas of the denture to bear either the indicator styluses or the buttons are prepared with a specially designed bur. This bur is exactly the same diameter as the base of the button or stylus. Once the seats in the denture base have been prepared, the styluses—if this method is to be used—are pushed in and the denture is placed in the patient's mouth. The patient bites in centric relation, and the styluses punch holes in the fibromucosal tissues. The denture is then removed and cleaned. At this point it is advisable to cut sluiceways for the acrylic that will later bind the buttons to the denture. These sluice-ways, which are made with a No. 557 bur, should extend from the seats at right angles. They are necessary to ensure accurate seating of the buttons. If much acrylic is trapped under the buttons, they will