The anterior maxilla is the most challenging region of the dentition to restore due to its prominence and visibility. Bone grafting to support both the implant resto- ration and the soft tissue is key to achieving a long-lasting, esthetic result. The stakes are even higher in cases involving two or more teeth. Osseointegration of dental implants, particularly in the anterior maxilla, depends on adequate trabecular bone density, ridge height and width, and systemic bone health. The clinician must evaluate all of these factors preoperatively to ensure that implants can maintain osseointegration during function. Furthermore, all available clinical, laboratory, and communication technologies will be needed to meet the patient’s functional and esthetic needs.
Bone augmentation is required when the bone resorption that accompanies anterior tooth loss prohibits proper implant positioning. Often the diameter of an implant exceeds that of a natural tooth and leads to challenges associated with the cervical esthetics of the crown. Other problems unique to the anterior maxilla that may limit ideal placement of implants include a resorbed (from periodontal disease) or fractured (from extraction) facial cortical plate over the maxillary roots of the teeth, close proximity of the nasal and maxillary sinus cavities, lateral extension of the incisive canal, facial concavities, and reduced turnover and health of bone caused by aging or metabolic disease (which may not be revealed until after implant placement) (Fig 10-1). Obtaining a healthy and esthetic soft tissue result, including a natural emergence profile, may require soft tissue grafting as well as bone grafting. Consequently, successful restoration of the anterior maxilla requires development of a comprehensive treatment plan that allows the surgeon, the laboratory technician, and the restorative clinician to visualize the anticipated result before treatment begins.
Tissue Evaluation to Determine Grafting Needs
The first step in treatment planning for implant placement in the anterior maxilla is to analyze the topography of the edentulous ridge, paying particular attention to the incisogingival and faciolingual aspects. The amount of available bone must be sufficient to accommodate the number and size of implants needed to support both the planned restoration as well as the soft tissue architecture. Depending on the findings from the clinical and radiographic examination, a CT or spiral tomography scan may be required to obtain a 3D view. This imaging technology is complemented by the use of CAD/CAM technology for 3D placement of abutments to achieve functional and esthetic satisfaction for the patient. Additionally, a wax-up of the ridge and the missing tooth or teeth can be requested from the laboratory.
The planned approach to implant restoration will depend on whether a single tooth or multiple teeth are being restored and whether implant placement is immediate or delayed. If more than two teeth are missing, reducing the number of implants can improve the esthetic outcome by preserving the peri-implant soft tissue architecture at the pontic area. The clinician can then take steps to develop the interimplant papillae. When implants are placed 1:1 for missing teeth, creating the illusion of papillae can be difficult.
Anterior Ridge Augmentation Techniques
Decisions about whether and how to augment the alveolar ridge of the maxilla are based in part on the crown-implant ratio and the position of the incisal edge in relation to the implant body. The morphology of the defect will also dictate which techniques or graft materials to use. Several ridge augmentation techniques have been developed to accommodate implant placement in the anterior maxilla, including nasal floor elevation with grafting (see chapter 11), ridge spreading using osteotomes (see chapter 13), corticocancellous autogenous block bone grafting (see chapter 15), and guided tissue regeneration (see chapter 14). Table 10-1 classifies ridge augmentation techniques according to the severity of the ridge deficiencies. Gener- ally, when 4 to 10 mm of ridge thickness is available, a number of in-office procedures can be considered, whereas severely resorbed or otherwise grossly deficient ridges usually require more extensive treatment (Fig 10-2). Mucogingival reconstruction also may be required in anterior maxillary restoration cases. If the horizontal and vertical dimensions of the ridge deficiency are within 3 mm of their original contour, good results can be achieved using soft tissue augmentation procedures, such as pedicle connective tissue grafts or free onlay/ inlay connective tissue grafts harvested from the palatal mucosa. These grafting procedures can be performed prior to implant placement or during the submerged healing phase
Guided bone regeneration
If the ridge is at least 8 to 10 mm in buccopalatal width and the interarch-ridge relationship is appropriate, 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 can be considered. Clinical experience and the published litera- ture 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 presents the most serious obstacle to achieving successful implant-supported prosthetics in the anterior region.
Use of barrier membranes for GBR in the maxilla can follow a single-stage or two-stage approach. If suffi- cient bone is present for placement of the implant and primary stability is not a concern, the membrane and implant can be placed simultaneously in a single-stage approach to treat any minor dehiscences or fenestrations. The membrane can be removed approximately 6 months later, and prosthetic treatment can commence at that time. When local maxillary bone is insufficient for the placement of the implant and therefore will not satisfy the patient’s esthetic and functional needs, barrier membranes can be placed first to help regenerate the bone in the area of the defect. A titanium-reinforced membrane can safely envelop the bone defect while effectively keeping the membrane off the bone. The membrane can then be removed approximately 9 months later, and the implant can be placed during stage-two surgery. Prosthetic treatment can commence approxi- mately 3 months after implant placement.
Particulate bone grafting and membranes with pin fixation
If the ridge is at least 7 to 8 mm in buccopalatal width, a membrane with some particulated graft material should be considered. The graft material can consist of autoge- nous bone, allogeneic bone (such as demineralized or mineralized freeze-dried bone allograft [FDBA]), or an alloplast/xenograft. As discussed in chapter 2, autografts regenerate bone while alloplasts and xenografts create an osteoconductive scaffolding to facilitate bone regeneration. Allografts with collagen or other types of resorbable membranes, including fixed bioabsorbable membranes, can be used for ridge augmentation64–69 (Fig 10-3). However, the literature reports that more predictable results are generally obtained with nonre- sorbable membranes, even when placed simultaneously with implants70–72 (Fig 10-4). The best results have been obtained when implant placement is delayed for several weeks and when only a single implant is placed. Several researchers have demonstrated the effective use of GBR even in cases of more severe bone loss (Fig 10-5)
Osteotome ridge expansion
If the ridge width is at least 6 to 7 mm buccopalatally, an osteotome approach can be used to expand and augment the ridge to restore function and to provide good esthetics as well.80,81 The use of osteotomes to expand a narrow anterior alveolar ridge prior to implant placement offers a particularly versatile approach for the clinician. Key advantages include minimal or no drilling, conservation of osseous tissue, improvement of bone density, and an implant-bone interface of denser bone. Traditionally, when dense bone predominates in the alveolar ridge, the implant osteotomy is created using drills of progressively larger diameter, the last of which is approximately the same diameter and length as the implant. However, when poor-density bone predomi- nates at the proposed implant site—which is most often the case in the maxilla—a more conservative approach should be used. In such cases, osteotomes of progres- sively larger diameter can be pushed or malleted into the alveolar ridge, actually condensing and compacting the bone. The poor-density bone at the implant site is effectively relocated rather than removed (as it is through drilling), thereby increasing the probability of an implant’s survival once it is in place (Fig 10-6). Other indications for ridge expansion include the need to improve esthetics, reduce maxillary undercuts, alter emergence angles, and match opposing landmarks
Ridge spreading and ridge splitting
Ridge spreading and ridge splitting are additional treatment modalities for augmentation of the deficient ridge that can be performed during routine office visits and involve minimal surgical complexity. Surgeons should determine which of these techniques to use based on the preoperative width of the horizontally deficient ridge. A ridge width of 5 to 6 mm can often be treated successfully with a ridge-splitting proce- dure, whereas ridge spreading requires a minimum of 6 mm of alveolar bone width (Figs 10-7 and 10-8). The presence of at least 10 mm of vertical height is required for both procedures.
Because they can often be completed in one stage and do not require a second surgical site, these procedures result in less morbidity and less expense for the patient than conventional techniques. Osteotomes and bone expanders can be used primarily in the maxilla, where bone is less dense and bone texture is relatively soft. Ridge-splitting instruments, such as chisels, bone saws, and piezoelectric units, can be used in the mandible (and in the maxilla under certain conditions) to achieve “ideal” implant positioning in edentulous or partially edentulous patients. For step-by-step guidance in these procedures, see chapter 13.
Allogeneic block bone grafting If the ridge width is at least 5 to 6 mm buccopalatally, grafting with allogeneic FDBA should be considered. As discussed in chapter 2, allografts have been used for years as viable alternatives to autogenous bone grafts. They avoid many of the disadvantages associated with autogenous grafts, including morbidity, limited quantity of bone, and harvesting time. Whenever good structural support is required, as in ridge augmentation, blocks of allogeneic bone can be used predictably as a scaffolding that will eventually resorb and be replaced with host bone (Fig 10-9)
Allogeneic bone materials containing both the collagen and mineral components of bone are preferred. Puros Allograft Block and Puros Allograft Cancellous Block (RTI Surgical), for example, are both processed to elimi- nate the cells, moisture, fats, and lipids while preserving the collagen and mineral components (Fig 10-10). In general, the criteria for the use of allogeneic block grafts are the same as for autogenous block grafts, with the following exceptions:
• When an allogeneic bone block is used, both the recip- ient site and the block graft should be decorticated.
• Whereas barrier membranes are required with autogenous bone blocks in cases where more than 50% of the surface is particulated, with allogeneic blocks, barrier membranes are recommended in all cases.
• The autogenous block does not require rehydration; however, the allograft block is rehydrated prior to use, preferably in nonactivated platelet-rich plasma (PRP).
Corticocancellous block bone grafting
If the ridge is at least 4 to 5 mm wide, an autogenous bone block should be used. Ridges with a crestal width of less than 6 mm typically require bone grafting prior to implant therapy. On the facial and lingual aspects, at least 2 mm of bone must surround the implant; there- fore, a 4-mm-diameter implant requires an 8- to 10-mm buccolingual bed of bone. While alloplast graft materials can be used to augment the ridge in the posterior maxilla and in the mandible, autogenous bone from the anterior mandible or the ramus is strongly recommended for augmentation of the deficient anterior maxilla requiring more than 4 to 5 mm of additional ridge width (Fig 10-11). Corticocancellous block grafts harvested from the ramus (see chapter 4) or chin (see chapter 5) will typically provide adequate bone to address 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
A 2012 study found that autogenous corticocancellous block grafts can be used safely and effectively to augment the atrophic anterior maxilla, providing adequate bone height and width for implant placement. Although the intraoral donor site provides a smaller volume of graft material compared with iliac crest bone harvest sites, it lies in close proximity to the recipient site, offers more convenient surgical access, requires minimal operative time, and allows the procedure to be performed in the office setting93 (Fig 10-12). A 2015 study reported predictable outcomes for anterior maxillary horizontal ridge augmentation when a block graft (harvested from either the iliac crest or the mandibular ramus) was combined with a particulate xenograft and covered with an absorbable collagen membrane. A 2016 study concluded that both autogenous ramus block bone grafting and GBR augmentation techniques in the horizontally deficient maxilla provide adequate bone graft volume and stability for implants. However, GBR is associated with greater resorption than ramus block bone grafting in the maxilla, which clinicians should consider during treatment planning. Another 2016 study found that block bone from both the symphysis and the ramus could be harvested and used to restore a horizontal bone defect in the anterior maxilla (although ramus harvesting resulted in fewer complications) and that implants placed in the grafted regions exhibited a high success and survival rate within the 1-year follow-up period.
Autogenous Bone Block Harvesting and Grafting Procedure
Clinicians should use their own discretion with regard to prescribing antibiotics and anti-inflammatory medi- cations before and after surgery. Some clinicians instruct patients to take ibuprofen 1 hour prior to surgery and for 3 to 7 days afterward. Amoxicillin can also be pre- scribed to be taken before and after surgery. In the area of the maxillary alveolar defect, 2% lidocaine with 1:100,000 epinephrine (or, alternatively, articaine) may be used as a local anesthetic.
Before any intraoral donor bone is harvested, the recip- ient area is exposed to verify the need for the graft as well as the optimal amount of bone required. An incision is made on the palatal aspect of the maxillary ridge to elevate a split-thickness mucosal flap. The periosteum is then incised over the crest. Divergent releasing incisions are made adjacent to the bordering teeth, and a full- thickness flap is elevated to expose the defect. Proper flap reflection and careful incision are crucial.
The recipient site should be debrided and irrigated to remove any potentially inflammatory tissue or scar tissue. The presence of any fibrous (scar) tissue will delay the processes of osteoinduction and osteocon- duction, while epithelial tissue can lead to fibrous healing instead of bone formation. Once the recipient bed is exposed, a piece of bone wax can be placed into the defect area and molded to approximate the dimensions of the bone graft. The bone wax is then removed and used as a template for harvesting an appropriately sized block graft. (Other sterile materials can be cut to shape and used as a template in place of bone wax if desired.) The host bone should be perforated with a small round bur to increase the availability of osteogenic cells, which can accelerate revascularization and improve union of the graft-host bone.
Immediately upon harvesting, the block graft is contoured to eliminate sharp edges and ensure maximal contact with the bone in the defect, and then it is placed as soon as possible. Typically, 1.0- to 1.6-mm-diameter titanium alloy screws are used to affix the graft to the host bone. Any small discrepancies should be filled with particulate cancellous bone from the harvest site.
Tension-free closure over these grafts is important. Prior to suturing, the buccal periosteum of the mucosal flap should be scored with a scalpel and undermined to allow greater advancement of the soft tissue. The incisions are then closed with 3-0 chromic interrupted mattress sutures. This approach minimizes tension and maintains coverage. The provisional removable partial denture should be adjusted to avoid contact with the grafted area (see Fig 10-13).
Postoperative Considerations and Complications
Amoxicillin or clindamycin can be administered 1 hour before the operation and continued for up to 1 week afterward. Dexamethasone can be prescribed the day of surgery and continued for several days postoper- atively. Complications such as membrane exposure, infection, and plaque accumulation can be addressed in subsequent appointments. Significant exposure of the membrane may require regrafting or membrane removal, whereas minor exposure may require simply applying a topical antimicrobial (for example, chlorhex- idine) as necessary. The final reconstructed recipient ridge should be at least 8 to 10 mm wide to allow for potential graft resorption and remodeling and yet yield an adequate width for placement of standard-diameter implants.
The recipient site should be allowed to heal for 4 to 8 months before the implant is placed. Graft fracture, wound dehiscence (with implant and graft exposure), and a generally higher rate of implant failure are more likely when implants are placed simultaneously with the graft or GBR instead of in a two-stage approach
Performing the surgery in stages enhances prosthetic alignment, obviating the need for remodeling or additional securing of the graft. A two-stage approach also allows the clinician to address any resorption that occurs so that the implant has a more secure base. While some research on immediate loading of single-tooth implants in the anterior maxilla shows positive outcomes, conditions involving augmentation require more study.106,107 Some clinical studies report that graft failures are often related to infection at the recipient site, premature loading of the grafts with transitional prostheses, and mucosal flap dehiscence with subsequent graft exposure to the oral cavity.
Adjunctive Techniques
Severely resorbed ridges and/or ridge-relation discrep- ancies may require the use of a titanium mesh crib or a Le Fort I downfracture of the maxilla and an interpo- sitional bone graft. Additionally, if residual bone stock is available, distraction osteogenesis can provide a viable alternative to these two approaches.
Titanium mesh crib with autogenous bone
Vertical defects often require a technique-sensitive proce- dure using onlay and other autogenous grafts supported by a nonresorbable titanium mesh crib. These defects occur in patients who have had tooth extractions because of significant bone loss from periodontal disease, fractured roots, or pulpal pathology.
Le Fort I downfracture of the maxilla
Research and clinical experience support reconstruction of the severely atrophic maxilla via a Le Fort I downfrac- ture with interpositional bone grafting along with dental implants, either immediate or delayed. In such cases, a Le Fort I osteotomy and downfracture is followed by the harvesting of cancellous marrow from the posterior iliac crest. The marrow bone is grafted to the maxilla between the stable and downfractured maxillary compo- nents. Subsequently, implants are placed in the recon- structed maxilla and restored with an implant-retained overdenture. The long-term stability of Le Fort I maxillary downfractures with interpositional bone grafting has been well documented and should always be a consideration of the dental team.
Stage-One Surgery for Implant Placement
Once the ideal amount of bone has been obtained in the anterior maxilla, a surgical template is fabricated to identify the incisal edge of the definitive prosthesis and to ensure proper implant positioning in relation to adjacent teeth. An incision may be made on the crest of the ridge to permit ideal soft tissue reflection. The implant site should be more than 5 mm wide at this point. The greater the implant diameter, the more esthetically pleasing the cervical portion of the crown will be.
The vertical position of the implant should balance the marginal level of bone around the implant (1 mm of bone is generally lost around the implant neck during the first year of function) and the biologic height of soft tissues (generally 3 to 4 mm). Thus, the implant neck should be placed 2.0 to 2.5 mm apical to the anticipated buccogin- gival margin of the restoration. This approach allows for a proper implant emergence profile as well as preservation of the biologic width and height over long-term function. On the mesiodistal aspect, a minimum space of 1.5 to 2.0 mm should remain between tooth and implant. The distance should be at least 3.0 mm between two adjacent implants. Additional interimplant bone support is also helpful to ensure a full gingival papilla. In the labiopalatal dimension, the implant should be placed as far buccal as possible while still allowing for the placement of restor- ative materials of adequate thickness and an appropriate screw access hole. Care should be taken to maintain or to create a minimum of 2 to 3 mm of bone thickness buccal to the dental implant.
To allow for a proper emergence profile, 2 to 3 mm of bone should be maintained labial to the implant. Placing the implant further in a palatal direction results in an undercontoured restoration with a modified ridge lap design for the definitive restoration. Such conditions can hamper hygiene efforts and compromise esthetics. Placing the implant too far labially also jeopardizes esthetics by creating a bulky, overcontoured crown that cannot be corrected with angulated abutments. If a case calls for placing an implant in a palatal direction because of anatomical or clinical limitations, the implant should be placed 1 mm apically for every 1 mm it is placed palatally.
If cemented abutments are used, the implant should be located exactly in the center of the long axis of the future implant-supported crown. For screw-retained abutments, the implant should be placed slightly palatal to the long axis of the crown to provide access to the connecting screw palatally. Generally, internal-connection implants are recommended in the esthetic zone.
Stage-one indexing technique
Stage-one indexing is a relatively simple procedure recommended for implant placement in the esthetic zone. When the implant is placed, an impression of the head of the implant is taken using sterile methods and materials, and its relation to adjacent teeth is recorded by means of a “pickup” impression coping attached to the implant. Once this index is removed, the surgery is completed and the index, the study casts of the mandible and maxilla, the occlusal registration, and a shade selection are transferred to the laboratory. Based on the altered cast technique, the laboratory technician attaches the impression coping to an implant analog and retrofits it into the study casts to use as a guide for fabrication of an anatomically correct abutment and provisional crown. When the implant is uncovered at stage-two surgery, the clinician can attach the custom abutment and provisional crown to the implant. This method not only helps guide the formation of ideal gingival contours as early as possible but also avoids the use of a healing abutment. It can also eliminate the need for subsequent soft tissue surgery for papilla regen- eration procedures, as the gingival topography conforms to the tooth that was custom-fabricated for the patient. The indexing impression taken at stage-one surgery thus provides orientation for the guided tooth form that facil- itates early soft tissue healing and contouring as soon as stage-two surgery is completed.
Another benefit of the stage-one impression technique is superior soft tissue contour and esthetics when stage-two surgery begins. Upon placement of the provisional restoration at stage-two surgery, the clinician can fashion the soft tissue for optimal esthetic results. The provisional crown was custom-fabricated according to the patient’s oral needs and dimensions, and as the soft tissue heals it adapts to the crown’s surface. Consequently, when the last impression is made, the contours of the soft tissue and the stability of the crown are optimized. The distance between the bone crest and the contact point between the teeth or crowns should not exceed 5 mm. This distance allows the bone to support the gingival margin and the inter- proximal papillae needed for optimal esthetics.42,132–135
Implants ideally should be placed at the same angula- tion as the lingual two-thirds of the natural tooth. The implant should be angled through the incisal edge of the surgical guide for cement-retained prostheses and through the cingulum for screw-retained prostheses.136–139 Provisional restorations are used to further guide the healing soft tissues and to develop the crown emergence profile. During the healing period, any transmucosal loading from the provisional restoration must be avoided. Otherwise, bone regeneration may be limited and membrane exposure more likely. Fixed provisional prostheses are a good choice to deter movement. Any removable provisional restoration should be aggressively recontoured to eliminate implant contact during healing.
Stage-Two Surgery for Abutment Connection
When uncovering the implant, the clinician should use an appropriate gingivoplasty procedure to ensure an esthetically pleasing restoration. A horizontal incision may be made on the palatal aspect of the ridge, extending from the line angles of the two adjacent teeth. The tissue is then reflected toward the labial crest, and the implant head is exposed.
The prefabricated and custom-designed abutments are placed at this time, along with the prefabricated provisional restoration, to allow for ideal maturation of the soft tissues. All periodontal plastic surgery proce- dures should be performed at this time for optimal soft tissue esthetics. The tissues are placed slightly coronal to the gingival margin on the adjacent teeth, and interdental sutures are placed and then removed after 1 week. A period of 6 to 8 weeks is required for maturation of the soft tissues before final abutment selection or final impressions.
After abutment connection, the maturing peri-implant soft tissues tend to recede slightly. The clinician must consider this tendency to ensure that the tissue changes do not compromise the planned emergence profile of the restoration. Thus, following abutment-connection surgery and keratinized soft tissue esthetic procedures around the implant site, a 6- to 8-week provisional phase is recommended before final impressions are taken (Fig 10-13). Implant positioning in the anterior maxilla is based primarily on the prosthesis needed to satisfy the patient’s functional and esthetic needs and not on the availability of local bone. This principle, described in the literature as restoration-driven rather than bone-driven implant placement, is acknowledgment that bone and soft tissue augmentation are generally required to achieve optimal results. When a single tooth is to be replaced, 3D planning of the implant placement is essential. The restoration-driven dental team are described as facilita- tors of esthetics who adhere to the following criteria:
• Reverse planning (designing implant placement and grafting for ultimate function and the esthetics of the definitive prosthesis), surgical templates, and ideal implant positioning
• Esthetically oriented surgical procedures
• Bone augmentation procedures
• Soft tissue management for esthetics
Augmentation and implant placement in the anterior maxilla—the most challenging region of the dentition to restore—require criteria no less demanding than these in order to be successful.
Potential Complications
Preventing early complications involves the use of pressure dressings, topical ice packs, and anti-inflammatory drugs to reduce swelling, along with analgesics for pain control. In addition, the patient must be educated about the impor- tance of meticulous oral hygiene. Edema following surgery is very common, although it varies in intensity. In most cases, swelling decreases rapidly during the first 2 days postsurgery, and complete dissipation occurs within 1 week. Table 10-2 lists other potential complications, common reasons for their occurrence, and techniques for minimizing them.
Bone augmentation is required when the bone resorption that accompanies anterior tooth loss prohibits proper implant positioning. Often the diameter of an implant exceeds that of a natural tooth and leads to challenges associated with the cervical esthetics of the crown. Other problems unique to the anterior maxilla that may limit ideal placement of implants include a resorbed (from periodontal disease) or fractured (from extraction) facial cortical plate over the maxillary roots of the teeth, close proximity of the nasal and maxillary sinus cavities, lateral extension of the incisive canal, facial concavities, and reduced turnover and health of bone caused by aging or metabolic disease (which may not be revealed until after implant placement) (Fig 10-1). Obtaining a healthy and esthetic soft tissue result, including a natural emergence profile, may require soft tissue grafting as well as bone grafting. Consequently, successful restoration of the anterior maxilla requires development of a comprehensive treatment plan that allows the surgeon, the laboratory technician, and the restorative clinician to visualize the anticipated result before treatment begins.
Tissue Evaluation to Determine Grafting Needs
The first step in treatment planning for implant placement in the anterior maxilla is to analyze the topography of the edentulous ridge, paying particular attention to the incisogingival and faciolingual aspects. The amount of available bone must be sufficient to accommodate the number and size of implants needed to support both the planned restoration as well as the soft tissue architecture. Depending on the findings from the clinical and radiographic examination, a CT or spiral tomography scan may be required to obtain a 3D view. This imaging technology is complemented by the use of CAD/CAM technology for 3D placement of abutments to achieve functional and esthetic satisfaction for the patient. Additionally, a wax-up of the ridge and the missing tooth or teeth can be requested from the laboratory.
The planned approach to implant restoration will depend on whether a single tooth or multiple teeth are being restored and whether implant placement is immediate or delayed. If more than two teeth are missing, reducing the number of implants can improve the esthetic outcome by preserving the peri-implant soft tissue architecture at the pontic area. The clinician can then take steps to develop the interimplant papillae. When implants are placed 1:1 for missing teeth, creating the illusion of papillae can be difficult.
Anterior Ridge Augmentation Techniques
Decisions about whether and how to augment the alveolar ridge of the maxilla are based in part on the crown-implant ratio and the position of the incisal edge in relation to the implant body. The morphology of the defect will also dictate which techniques or graft materials to use. Several ridge augmentation techniques have been developed to accommodate implant placement in the anterior maxilla, including nasal floor elevation with grafting (see chapter 11), ridge spreading using osteotomes (see chapter 13), corticocancellous autogenous block bone grafting (see chapter 15), and guided tissue regeneration (see chapter 14). Table 10-1 classifies ridge augmentation techniques according to the severity of the ridge deficiencies. Gener- ally, when 4 to 10 mm of ridge thickness is available, a number of in-office procedures can be considered, whereas severely resorbed or otherwise grossly deficient ridges usually require more extensive treatment (Fig 10-2). Mucogingival reconstruction also may be required in anterior maxillary restoration cases. If the horizontal and vertical dimensions of the ridge deficiency are within 3 mm of their original contour, good results can be achieved using soft tissue augmentation procedures, such as pedicle connective tissue grafts or free onlay/ inlay connective tissue grafts harvested from the palatal mucosa. These grafting procedures can be performed prior to implant placement or during the submerged healing phase
Guided bone regeneration
If the ridge is at least 8 to 10 mm in buccopalatal width and the interarch-ridge relationship is appropriate, 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 can be considered. Clinical experience and the published litera- ture 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 presents the most serious obstacle to achieving successful implant-supported prosthetics in the anterior region.
Use of barrier membranes for GBR in the maxilla can follow a single-stage or two-stage approach. If suffi- cient bone is present for placement of the implant and primary stability is not a concern, the membrane and implant can be placed simultaneously in a single-stage approach to treat any minor dehiscences or fenestrations. The membrane can be removed approximately 6 months later, and prosthetic treatment can commence at that time. When local maxillary bone is insufficient for the placement of the implant and therefore will not satisfy the patient’s esthetic and functional needs, barrier membranes can be placed first to help regenerate the bone in the area of the defect. A titanium-reinforced membrane can safely envelop the bone defect while effectively keeping the membrane off the bone. The membrane can then be removed approximately 9 months later, and the implant can be placed during stage-two surgery. Prosthetic treatment can commence approxi- mately 3 months after implant placement.
Particulate bone grafting and membranes with pin fixation
If the ridge is at least 7 to 8 mm in buccopalatal width, a membrane with some particulated graft material should be considered. The graft material can consist of autoge- nous bone, allogeneic bone (such as demineralized or mineralized freeze-dried bone allograft [FDBA]), or an alloplast/xenograft. As discussed in chapter 2, autografts regenerate bone while alloplasts and xenografts create an osteoconductive scaffolding to facilitate bone regeneration. Allografts with collagen or other types of resorbable membranes, including fixed bioabsorbable membranes, can be used for ridge augmentation64–69 (Fig 10-3). However, the literature reports that more predictable results are generally obtained with nonre- sorbable membranes, even when placed simultaneously with implants70–72 (Fig 10-4). The best results have been obtained when implant placement is delayed for several weeks and when only a single implant is placed. Several researchers have demonstrated the effective use of GBR even in cases of more severe bone loss (Fig 10-5)
Osteotome ridge expansion
If the ridge width is at least 6 to 7 mm buccopalatally, an osteotome approach can be used to expand and augment the ridge to restore function and to provide good esthetics as well.80,81 The use of osteotomes to expand a narrow anterior alveolar ridge prior to implant placement offers a particularly versatile approach for the clinician. Key advantages include minimal or no drilling, conservation of osseous tissue, improvement of bone density, and an implant-bone interface of denser bone. Traditionally, when dense bone predominates in the alveolar ridge, the implant osteotomy is created using drills of progressively larger diameter, the last of which is approximately the same diameter and length as the implant. However, when poor-density bone predomi- nates at the proposed implant site—which is most often the case in the maxilla—a more conservative approach should be used. In such cases, osteotomes of progres- sively larger diameter can be pushed or malleted into the alveolar ridge, actually condensing and compacting the bone. The poor-density bone at the implant site is effectively relocated rather than removed (as it is through drilling), thereby increasing the probability of an implant’s survival once it is in place (Fig 10-6). Other indications for ridge expansion include the need to improve esthetics, reduce maxillary undercuts, alter emergence angles, and match opposing landmarks
Ridge spreading and ridge splitting
Ridge spreading and ridge splitting are additional treatment modalities for augmentation of the deficient ridge that can be performed during routine office visits and involve minimal surgical complexity. Surgeons should determine which of these techniques to use based on the preoperative width of the horizontally deficient ridge. A ridge width of 5 to 6 mm can often be treated successfully with a ridge-splitting proce- dure, whereas ridge spreading requires a minimum of 6 mm of alveolar bone width (Figs 10-7 and 10-8). The presence of at least 10 mm of vertical height is required for both procedures.
Because they can often be completed in one stage and do not require a second surgical site, these procedures result in less morbidity and less expense for the patient than conventional techniques. Osteotomes and bone expanders can be used primarily in the maxilla, where bone is less dense and bone texture is relatively soft. Ridge-splitting instruments, such as chisels, bone saws, and piezoelectric units, can be used in the mandible (and in the maxilla under certain conditions) to achieve “ideal” implant positioning in edentulous or partially edentulous patients. For step-by-step guidance in these procedures, see chapter 13.
Allogeneic block bone grafting If the ridge width is at least 5 to 6 mm buccopalatally, grafting with allogeneic FDBA should be considered. As discussed in chapter 2, allografts have been used for years as viable alternatives to autogenous bone grafts. They avoid many of the disadvantages associated with autogenous grafts, including morbidity, limited quantity of bone, and harvesting time. Whenever good structural support is required, as in ridge augmentation, blocks of allogeneic bone can be used predictably as a scaffolding that will eventually resorb and be replaced with host bone (Fig 10-9)
Allogeneic bone materials containing both the collagen and mineral components of bone are preferred. Puros Allograft Block and Puros Allograft Cancellous Block (RTI Surgical), for example, are both processed to elimi- nate the cells, moisture, fats, and lipids while preserving the collagen and mineral components (Fig 10-10). In general, the criteria for the use of allogeneic block grafts are the same as for autogenous block grafts, with the following exceptions:
• When an allogeneic bone block is used, both the recip- ient site and the block graft should be decorticated.
• Whereas barrier membranes are required with autogenous bone blocks in cases where more than 50% of the surface is particulated, with allogeneic blocks, barrier membranes are recommended in all cases.
• The autogenous block does not require rehydration; however, the allograft block is rehydrated prior to use, preferably in nonactivated platelet-rich plasma (PRP).
Corticocancellous block bone grafting
If the ridge is at least 4 to 5 mm wide, an autogenous bone block should be used. Ridges with a crestal width of less than 6 mm typically require bone grafting prior to implant therapy. On the facial and lingual aspects, at least 2 mm of bone must surround the implant; there- fore, a 4-mm-diameter implant requires an 8- to 10-mm buccolingual bed of bone. While alloplast graft materials can be used to augment the ridge in the posterior maxilla and in the mandible, autogenous bone from the anterior mandible or the ramus is strongly recommended for augmentation of the deficient anterior maxilla requiring more than 4 to 5 mm of additional ridge width (Fig 10-11). Corticocancellous block grafts harvested from the ramus (see chapter 4) or chin (see chapter 5) will typically provide adequate bone to address 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
A 2012 study found that autogenous corticocancellous block grafts can be used safely and effectively to augment the atrophic anterior maxilla, providing adequate bone height and width for implant placement. Although the intraoral donor site provides a smaller volume of graft material compared with iliac crest bone harvest sites, it lies in close proximity to the recipient site, offers more convenient surgical access, requires minimal operative time, and allows the procedure to be performed in the office setting93 (Fig 10-12). A 2015 study reported predictable outcomes for anterior maxillary horizontal ridge augmentation when a block graft (harvested from either the iliac crest or the mandibular ramus) was combined with a particulate xenograft and covered with an absorbable collagen membrane. A 2016 study concluded that both autogenous ramus block bone grafting and GBR augmentation techniques in the horizontally deficient maxilla provide adequate bone graft volume and stability for implants. However, GBR is associated with greater resorption than ramus block bone grafting in the maxilla, which clinicians should consider during treatment planning. Another 2016 study found that block bone from both the symphysis and the ramus could be harvested and used to restore a horizontal bone defect in the anterior maxilla (although ramus harvesting resulted in fewer complications) and that implants placed in the grafted regions exhibited a high success and survival rate within the 1-year follow-up period.
Autogenous Bone Block Harvesting and Grafting Procedure
Clinicians should use their own discretion with regard to prescribing antibiotics and anti-inflammatory medi- cations before and after surgery. Some clinicians instruct patients to take ibuprofen 1 hour prior to surgery and for 3 to 7 days afterward. Amoxicillin can also be pre- scribed to be taken before and after surgery. In the area of the maxillary alveolar defect, 2% lidocaine with 1:100,000 epinephrine (or, alternatively, articaine) may be used as a local anesthetic.
Before any intraoral donor bone is harvested, the recip- ient area is exposed to verify the need for the graft as well as the optimal amount of bone required. An incision is made on the palatal aspect of the maxillary ridge to elevate a split-thickness mucosal flap. The periosteum is then incised over the crest. Divergent releasing incisions are made adjacent to the bordering teeth, and a full- thickness flap is elevated to expose the defect. Proper flap reflection and careful incision are crucial.
The recipient site should be debrided and irrigated to remove any potentially inflammatory tissue or scar tissue. The presence of any fibrous (scar) tissue will delay the processes of osteoinduction and osteocon- duction, while epithelial tissue can lead to fibrous healing instead of bone formation. Once the recipient bed is exposed, a piece of bone wax can be placed into the defect area and molded to approximate the dimensions of the bone graft. The bone wax is then removed and used as a template for harvesting an appropriately sized block graft. (Other sterile materials can be cut to shape and used as a template in place of bone wax if desired.) The host bone should be perforated with a small round bur to increase the availability of osteogenic cells, which can accelerate revascularization and improve union of the graft-host bone.
Immediately upon harvesting, the block graft is contoured to eliminate sharp edges and ensure maximal contact with the bone in the defect, and then it is placed as soon as possible. Typically, 1.0- to 1.6-mm-diameter titanium alloy screws are used to affix the graft to the host bone. Any small discrepancies should be filled with particulate cancellous bone from the harvest site.
Tension-free closure over these grafts is important. Prior to suturing, the buccal periosteum of the mucosal flap should be scored with a scalpel and undermined to allow greater advancement of the soft tissue. The incisions are then closed with 3-0 chromic interrupted mattress sutures. This approach minimizes tension and maintains coverage. The provisional removable partial denture should be adjusted to avoid contact with the grafted area (see Fig 10-13).
Postoperative Considerations and Complications
Amoxicillin or clindamycin can be administered 1 hour before the operation and continued for up to 1 week afterward. Dexamethasone can be prescribed the day of surgery and continued for several days postoper- atively. Complications such as membrane exposure, infection, and plaque accumulation can be addressed in subsequent appointments. Significant exposure of the membrane may require regrafting or membrane removal, whereas minor exposure may require simply applying a topical antimicrobial (for example, chlorhex- idine) as necessary. The final reconstructed recipient ridge should be at least 8 to 10 mm wide to allow for potential graft resorption and remodeling and yet yield an adequate width for placement of standard-diameter implants.
The recipient site should be allowed to heal for 4 to 8 months before the implant is placed. Graft fracture, wound dehiscence (with implant and graft exposure), and a generally higher rate of implant failure are more likely when implants are placed simultaneously with the graft or GBR instead of in a two-stage approach
Performing the surgery in stages enhances prosthetic alignment, obviating the need for remodeling or additional securing of the graft. A two-stage approach also allows the clinician to address any resorption that occurs so that the implant has a more secure base. While some research on immediate loading of single-tooth implants in the anterior maxilla shows positive outcomes, conditions involving augmentation require more study.106,107 Some clinical studies report that graft failures are often related to infection at the recipient site, premature loading of the grafts with transitional prostheses, and mucosal flap dehiscence with subsequent graft exposure to the oral cavity.
Adjunctive Techniques
Severely resorbed ridges and/or ridge-relation discrep- ancies may require the use of a titanium mesh crib or a Le Fort I downfracture of the maxilla and an interpo- sitional bone graft. Additionally, if residual bone stock is available, distraction osteogenesis can provide a viable alternative to these two approaches.
Titanium mesh crib with autogenous bone
Vertical defects often require a technique-sensitive proce- dure using onlay and other autogenous grafts supported by a nonresorbable titanium mesh crib. These defects occur in patients who have had tooth extractions because of significant bone loss from periodontal disease, fractured roots, or pulpal pathology.
Le Fort I downfracture of the maxilla
Research and clinical experience support reconstruction of the severely atrophic maxilla via a Le Fort I downfrac- ture with interpositional bone grafting along with dental implants, either immediate or delayed. In such cases, a Le Fort I osteotomy and downfracture is followed by the harvesting of cancellous marrow from the posterior iliac crest. The marrow bone is grafted to the maxilla between the stable and downfractured maxillary compo- nents. Subsequently, implants are placed in the recon- structed maxilla and restored with an implant-retained overdenture. The long-term stability of Le Fort I maxillary downfractures with interpositional bone grafting has been well documented and should always be a consideration of the dental team.
Stage-One Surgery for Implant Placement
Once the ideal amount of bone has been obtained in the anterior maxilla, a surgical template is fabricated to identify the incisal edge of the definitive prosthesis and to ensure proper implant positioning in relation to adjacent teeth. An incision may be made on the crest of the ridge to permit ideal soft tissue reflection. The implant site should be more than 5 mm wide at this point. The greater the implant diameter, the more esthetically pleasing the cervical portion of the crown will be.
The vertical position of the implant should balance the marginal level of bone around the implant (1 mm of bone is generally lost around the implant neck during the first year of function) and the biologic height of soft tissues (generally 3 to 4 mm). Thus, the implant neck should be placed 2.0 to 2.5 mm apical to the anticipated buccogin- gival margin of the restoration. This approach allows for a proper implant emergence profile as well as preservation of the biologic width and height over long-term function. On the mesiodistal aspect, a minimum space of 1.5 to 2.0 mm should remain between tooth and implant. The distance should be at least 3.0 mm between two adjacent implants. Additional interimplant bone support is also helpful to ensure a full gingival papilla. In the labiopalatal dimension, the implant should be placed as far buccal as possible while still allowing for the placement of restor- ative materials of adequate thickness and an appropriate screw access hole. Care should be taken to maintain or to create a minimum of 2 to 3 mm of bone thickness buccal to the dental implant.
To allow for a proper emergence profile, 2 to 3 mm of bone should be maintained labial to the implant. Placing the implant further in a palatal direction results in an undercontoured restoration with a modified ridge lap design for the definitive restoration. Such conditions can hamper hygiene efforts and compromise esthetics. Placing the implant too far labially also jeopardizes esthetics by creating a bulky, overcontoured crown that cannot be corrected with angulated abutments. If a case calls for placing an implant in a palatal direction because of anatomical or clinical limitations, the implant should be placed 1 mm apically for every 1 mm it is placed palatally.
If cemented abutments are used, the implant should be located exactly in the center of the long axis of the future implant-supported crown. For screw-retained abutments, the implant should be placed slightly palatal to the long axis of the crown to provide access to the connecting screw palatally. Generally, internal-connection implants are recommended in the esthetic zone.
Stage-one indexing technique
Stage-one indexing is a relatively simple procedure recommended for implant placement in the esthetic zone. When the implant is placed, an impression of the head of the implant is taken using sterile methods and materials, and its relation to adjacent teeth is recorded by means of a “pickup” impression coping attached to the implant. Once this index is removed, the surgery is completed and the index, the study casts of the mandible and maxilla, the occlusal registration, and a shade selection are transferred to the laboratory. Based on the altered cast technique, the laboratory technician attaches the impression coping to an implant analog and retrofits it into the study casts to use as a guide for fabrication of an anatomically correct abutment and provisional crown. When the implant is uncovered at stage-two surgery, the clinician can attach the custom abutment and provisional crown to the implant. This method not only helps guide the formation of ideal gingival contours as early as possible but also avoids the use of a healing abutment. It can also eliminate the need for subsequent soft tissue surgery for papilla regen- eration procedures, as the gingival topography conforms to the tooth that was custom-fabricated for the patient. The indexing impression taken at stage-one surgery thus provides orientation for the guided tooth form that facil- itates early soft tissue healing and contouring as soon as stage-two surgery is completed.
Another benefit of the stage-one impression technique is superior soft tissue contour and esthetics when stage-two surgery begins. Upon placement of the provisional restoration at stage-two surgery, the clinician can fashion the soft tissue for optimal esthetic results. The provisional crown was custom-fabricated according to the patient’s oral needs and dimensions, and as the soft tissue heals it adapts to the crown’s surface. Consequently, when the last impression is made, the contours of the soft tissue and the stability of the crown are optimized. The distance between the bone crest and the contact point between the teeth or crowns should not exceed 5 mm. This distance allows the bone to support the gingival margin and the inter- proximal papillae needed for optimal esthetics.42,132–135
Implants ideally should be placed at the same angula- tion as the lingual two-thirds of the natural tooth. The implant should be angled through the incisal edge of the surgical guide for cement-retained prostheses and through the cingulum for screw-retained prostheses.136–139 Provisional restorations are used to further guide the healing soft tissues and to develop the crown emergence profile. During the healing period, any transmucosal loading from the provisional restoration must be avoided. Otherwise, bone regeneration may be limited and membrane exposure more likely. Fixed provisional prostheses are a good choice to deter movement. Any removable provisional restoration should be aggressively recontoured to eliminate implant contact during healing.
Stage-Two Surgery for Abutment Connection
When uncovering the implant, the clinician should use an appropriate gingivoplasty procedure to ensure an esthetically pleasing restoration. A horizontal incision may be made on the palatal aspect of the ridge, extending from the line angles of the two adjacent teeth. The tissue is then reflected toward the labial crest, and the implant head is exposed.
The prefabricated and custom-designed abutments are placed at this time, along with the prefabricated provisional restoration, to allow for ideal maturation of the soft tissues. All periodontal plastic surgery proce- dures should be performed at this time for optimal soft tissue esthetics. The tissues are placed slightly coronal to the gingival margin on the adjacent teeth, and interdental sutures are placed and then removed after 1 week. A period of 6 to 8 weeks is required for maturation of the soft tissues before final abutment selection or final impressions.
After abutment connection, the maturing peri-implant soft tissues tend to recede slightly. The clinician must consider this tendency to ensure that the tissue changes do not compromise the planned emergence profile of the restoration. Thus, following abutment-connection surgery and keratinized soft tissue esthetic procedures around the implant site, a 6- to 8-week provisional phase is recommended before final impressions are taken (Fig 10-13). Implant positioning in the anterior maxilla is based primarily on the prosthesis needed to satisfy the patient’s functional and esthetic needs and not on the availability of local bone. This principle, described in the literature as restoration-driven rather than bone-driven implant placement, is acknowledgment that bone and soft tissue augmentation are generally required to achieve optimal results. When a single tooth is to be replaced, 3D planning of the implant placement is essential. The restoration-driven dental team are described as facilita- tors of esthetics who adhere to the following criteria:
• Reverse planning (designing implant placement and grafting for ultimate function and the esthetics of the definitive prosthesis), surgical templates, and ideal implant positioning
• Esthetically oriented surgical procedures
• Bone augmentation procedures
• Soft tissue management for esthetics
Augmentation and implant placement in the anterior maxilla—the most challenging region of the dentition to restore—require criteria no less demanding than these in order to be successful.
Potential Complications
Preventing early complications involves the use of pressure dressings, topical ice packs, and anti-inflammatory drugs to reduce swelling, along with analgesics for pain control. In addition, the patient must be educated about the impor- tance of meticulous oral hygiene. Edema following surgery is very common, although it varies in intensity. In most cases, swelling decreases rapidly during the first 2 days postsurgery, and complete dissipation occurs within 1 week. Table 10-2 lists other potential complications, common reasons for their occurrence, and techniques for minimizing them.
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