If the ridge is at least 8 to 10 mm in buccopalatal width and the interarch ridge relationship is appropriate, then an implant can usually be placed adequately in bone. On occasion, some grafting may be required for esthetics or to cover a few exposed threads of the implant. In this scenario, a barrier membrane with titanium reinforcement struts can be considered.8 Clinical experience and the published literature have shown that bone defects in a ridge of this width can be treated effectively without bone graft materials and using only guided bone regeneration (GBR). In fact, the results are so predictable that soft tissue management often becomes the most serious obstacle to successful use of implant-supported prosthetics in the anterior region.⁵¹

Use of barrier membranes for GBR in the maxilla, such as the Gore-Tex titanium-reinforced submerged membrane (W. L. Gore, Flagstaff, AZ), can follow a one- or two-stage approach. Embedded titanium struts allow the membrane to safely envelop the bone defect while effectively keeping the membrane off the bone (provided the titanium struts are bent appropriately and the membrane is tacked into position). If sufficient bone is available for placing the implant and primary stability is not a concern, then the membrane and implant can be placed simultaneously in a one-stage approach to treat any minor dehiscences or fenestrations. The membrane can be removed approximately 6 months later, and prosthetic treatment can commence. When local maxillary bone is insufficient for the placement of the implant because of the patient’s esthetic and functional needs, barrier membranes can be placed first to help regenerate the bone in the area of the defect. The membrane can then be removed approximately 9 months later, and the implant can be placed at a second-stage surgery. Prosthetic treatment can commence approximately 3 months after implant placement.

Fig 9-3 Use of barrier membranes in the maxilla following a one-stage approach.

(a) Bone dehiscence has occurred at the time of implant placement.

(b) Good stability is achieved despite implant exposure.

(c) Autogenous bone is obtained from the newly formed socket during careful drilling and is sufficient to provide good coverage in this patient.

(d) A resorbable collagen membrane is cut to fit the area and placed at the site.

(e) The flap should be placed exactly in its original position with passive closure and sutured to achieve primary closure.

If the ridge is at least 7 to 8 mm bucco-palatally, a membrane with some particulated graft material should be considered. The graft material can consist of autogenous bone, an allograft (such as demineralized or mineralized freeze-dried bone [FDBA]), or an alloplast/xenograft. Autogenous grafts regenerate bone, while alloplasts and xenografts create an osteoconductive scaffolding to facilitate bone regeneration. Allografts with collagen^{54, 55} or other types of resorbable membranes (eg, AlloDerm [LifeCell, Branchburg, NJ]),^{56, 57} including fixed bioabsorbable membranes,⁵⁸ can be used for ridge augmentation (Fig 9-3). However, the literature generally reports more predictable results with nonresorbable membranes, even when placed simultaneously with implants (Fig 9-4).⁵⁹ The best results have been obtained when implant placement is delayed for several weeks and when only a single implant is placed.⁶⁰

Several researchers have demonstrated the effective use of GBR even in cases of more severe bone loss. In one study, human DFDBA was used with submem-branous space creation to augment bone prior to implant placement.⁶¹

Fig 9-4 If the ridge is at least 8 to 12 mm in buccopalatal width, dehiscences can be corrected with the use of GBR membranes with or without bone graft materials.

(a) A single-tooth site in the anterior maxilla also poses a challenge in terms of bone height and width and the need to provide symmetry with the contralateral site.

(b) A single-tooth edentulous site can present the illusion of containing good bone width and height; concavities filled with connective tissue can give the appearance of having a good thickness of bone, even when palpated.

(c) Although it had the appearance of adequate bone, flap reflection reveals a deep concavity that gives way to bone dehiscence during drilling.

(d) In this patient, the placement of allogeneic particulate bone with the membrane was preferred.

(e) A Gore-Tex membrane was chosen for this patient because it provides good adaptation and coverage to the area. This non-resorbable membrane will be removed during the stage 2 procedure.

(f) The use of the Auto-Tac system (BioHorizons, Birmingham, AL) with resorbable or nonresorbable tacks is ideal to help keep the membrane immobilized.

Fig 9-5 Osteotomes can be used to expand and augment the ridge to provide appropriate bone for function. The bone is compacted and relocated rather than removed, increasing the chances of implant survival.

(a) Osteotomes of increasing diameter (0.03 to 0.06 mm) are used to create an osteotomy to accommodate a specific implant system. (From Saadoun AP, Le Gall MG. Implant site preparation with osteotomes: Principles and clinical application. Pract Periodontics Aesthet Dent 1996;8:453–463. Used with permission.)

(b) Preoperative view showing a thin ridge in the anterior maxilla missing four incisors. A flap is reflected in order to gain access and visibility.

(c) The flap is reflected and retracted to expose the ridge.

(d) A surgical template is positioned to determine the appropriate osteotomy sites.

(e) The smallest diameter drill for the particular implant system is used first to reach the correct depth for the implant, which is then selected.

(f) An osteotome of the same diameter as the drilled osteotomy (or slightly larger, eg, 0.03 mm or less) is introduced into the site. Osteotomes of larger diameter are used to reach the appropriate depth based on the size of implant to be placed. The osteotomes are either slowly rotated in by hand or by gentle tapping with a mallet. The final osteotome should approximate the implant shape and diameter.

Using osteotomes to expand a narrow anterior alveolar ridge prior to implant placement offers a particularly versatile approach for the clinician. Key advantages of the osteotome technique include minimal or no drilling, conservation of osseous tissue, improvement of bone density, and implant-to-bone interface with a denser bone. The osteotomy for an endosseous implant is created by removing bone from the site using drills of progressively larger diameter, the last of which is approximately the same diameter and length as the implant. Where dense bone predominates, this traditional drilling approach is generally appropriate. However, when poor-density bone predominates at the proposed implant site—which is most often the case in the maxilla—a more conservative approach should be used. Using osteotomes of progressively larger diameter that can be pushed or malleted into the alveolar ridge actually compacts the bone. The poor-density bone at the implant site is effectively relocated rather than removed, as it is through drilling, thus increasing the chances of an implant’s survival once it is in place (Fig 9-5). Other indications for ridge expansion include the need to improve esthetics, reduce maxillary undercuts, alter emergence angles, and match opposing landmarks.

(g) The implant should have a self-tapping design. Implants of 3.75 × 15 mm are shown.

(h) Postoperative radiograph showing implants in place.

(i) Occlusal view of the ridge shows the increased buccopalatal dimension created with osteotomes.

(j) Fixed abutments are shown on the dental implant in preparation for fixed prosthetics.

If the ridge is at least 5 to 6 mm bucco-palatally, then an allogeneic/FDBA should be considered. Allografts have been used for years as viable alternatives to autogenous bone grafts. They eliminate many of the disadvantages associated with autogenous grafts, including morbidity, limited volume and dimension of bone, and harvesting time. In cases requiring good structural support, such as ridge augmentation, blocks of allogeneic bone can be used predictably to serve as a scaffolding that will eventually resorb and be replaced with host bone (Fig 9-6).

Allogeneic bone materials should contain both the collagen and mineral components of bone. For example, the Puros J-block (Zimmer Dental, Carlsbad, CA) is harvested and processed to eliminate the cells, moisture, fats, and lipids but to maintain the collagen and mineral components. In general, the criteria for using allogeneic block grafts are the same as the criteria for using autogenous block grafts described later in this chapter, with the following exceptions:

1. When an allogeneic bone block is used, both the recipient site and the block graft should be decorticated.
2. Barrier membranes are required with autogenous blocks of bone only if more than 50% of the surface is particulated. However, with the allogeneic block, barrier membranes are recommended in all cases.
3. The autogenous block does not require rehydration; however, the J-block is rehydrated prior to use, preferably in nonactivated platelet-rich plasma (PRP).

If the ridge is at least 4 to 5 mm wide, then an autogenous bone block should be used.9^{, 62, 63, 64, 65, 66} Ridges with a crestal width of less than 6 mm typically require bone grafting prior to implant therapy. On the facial and lingual areas, at least 2 mm of bone must surround the implant. Thus, for the clinician to place a 4-mm-diameter implant, an 8- to 10-mm bone bed is required buccolingually. While alloplastic grafting materials can be used to augment the ridge in the posterior maxilla and in the mandible,⁶⁷ autogenous bone from the anterior mandible or the ramus is highly recommended for augmentation of the anterior maxilla requiring more than 4 to 5 mm of additional ridge width. Corticocancellous block grafts harvested from the chin (see chapter 6) or ramus (see chapter 5) typically will provide adequate bone to overcome width deficiencies in the anterior maxilla extending up to four teeth or to increase both height and width in the areas of one to two teeth.^{68, 69, 70, 71}

For example, a 2003 study concluded that mandibular block onlay grafts offer extremely reliable results for increasing the width of the anterior maxilla before implant placement.⁷² Autogenous block grafts from the chin or ramus revascularize quickly and demonstrate a relatively low rate of resorption.⁷³ A barrier membrane may also be useful if more than 50% of the grafted area is particulate graft material. In another 2003 study reporting the use of symphyseal bone cores for vertical augmentation of the alveolar ridge, sites were additionally grafted with DFDBA in conjunction with a titanium-reinforced expanded polytetrafluoroethylene (e-PTFE) membrane.⁷⁴ Results of this study also indicated an increased ridge width.

Fig 9-6 Particulate autografts, particulate allografts or alloplasts, and autogenous or allogeneic blocks are all valid options in the preplanning stage. Analyzing and evaluating the patient’s healing potential within the boundaries of the bone defect will determine the best option.

(a) Elevating a full-thickness flap with adequate release enables visualization and grafting of the defect area.

(b) The side with the ridge defect and the contralateral side need to match with respect to bony volume and anatomy.

(c) The block is sculpted for the best possible fit in the deficient area.

(d) The block is placed in the defect to check for adaptation and contoured as necessary for good fit and initial stability.

(e) Block grafts of any kind should be stabilized and screwed in place, preferably with more than one screw, to provide as much adaptation as possible to the host bone and to minimize rotation or micromovement.

(f) The retaining screws (shown radiographically) will be removed at the time of implant placement.

(g) Soft tissue dissection can provide a tension-free flap to reduce soft tissue dehiscence from adjacent muscle pull.

(h) The buccal flap is repositioned after careful dissection to permit it to be tension free. It was designed, replaced, and sutured so that both papillae remain intact.