Current implant techniques—an overview 21

implant (Fig. 1-55). Although some operators make an acrylic surgical tray from a soft tissue alginate impression, these trays rarely fit accurately. There-fore it is advisable to fabricate the surgical tray directly in the mouth after the soft tissues have been incised and reflected.

To reveal the bone, an incision is made along the crest of the mandibular ridge from the retromolar pad area on one side to the same area on the other side, making sure that the cut is clean and deep enough to prevent any tissue from tearing during reflection. Then, to facilitate reflection, three incisions are made across the primary incision. One is made across each retromolar pad in a buccolingual direction, and one is made in the area of the mental symphysis in a labiolingual direction. Sometimes it is not necessary to make the anterior cross incision.

With a blunt instrument, such as a periosteal elevator, the soft tissues are reflected toward the cheeks, lips, and floor of the mouth respectively, thus exposing the bone (Fig. 1-56). The lingually reflected tissue should be sutured to keep the tongue in the posterior portion of the mouth, thus preventing it from interfering with the making of impressions. This is accomplished simply by suturing the lingual posterior tissue on one side of the arch with the lingual anterior tissue on the opposite side, and vice versa. The idea is to reveal as much bone as is needed to make a good impression.

On the lingual surface of the mandible in both

Fig. 1-56. The first step is to expose the entire mandible. Note the increased height of bone that exists once the muscular attachments are relieved.

Fig. 1-57. It is important to carefully expose the neurovascular bundles exiting the mental foramina on both sides of the jaw.

posterior halves, the tissues should be separated only down to slightly below the mylohyoid ridges, because the lingual extension of the implant will go no farther than this. Anteriorly, however, the genial tubercles should be exposed at the most inferior lingual surface of the mandible in its anterior aspect.

While reflecting the tissue on both buccal aspects, the operator must be exceptionally careful not to injure or sever the neurovascular bundle of nerves and blood vessels in the area of the mental foramen. The tissues overlying this area should be carefully pushed downward with a blunt instrument until a semicrescent appears. This is the superior wall of the mental foramen. The bundle should then be care-fully separated from the soft tissues to expose more of it and the foramen (Fig. 1-57). This should be

Fig. 1-55. This edentulous lower jaw has had severe bone resorption. Because of insufficient alveolar bone, the patient is not a suitable candidate for an endosseous implant. There-fore a subperiosteal implant is needed.