Hemorrhage and Hematoma

Bleeding during surgery is expected and usually easily controlled. However, if a sizable vessel is incised or otherwise injured during surgery, the hemorrhage can be difficult to control. Smaller vessels will naturally constrict or retract to slow the hemorrhage. If bleeding continues, it may be necessary to apply pressure or to suture the hemorrhaging vessel. This can be especially difficult if there is a vascular injury to an artery that is inaccessible such as in the floor of the mouth or posterior maxilla. Serious bleeding from an inaccessible vessel can be life threatening, not by exsanguination but rather as a result of airway obstruction. This is most problematic when the point of bleeding is inaccessible and internal (within the connective tissues and soft tissue spaces).

Postoperative bleeding is an equally important problem to manage (Figure 77-2). Patients should be given postoperative instructions on normal expectations for bleeding and how to prevent and manage minor bleeding. Historically, standard practice has recommended that they should be advised, with their physician’s approval, to discontinue or reduce medications that increase bleeding tendency 7 to 10 days before surgery. However, recent evidence suggests that this may not be necessary and may increase the risk of hematologic or cardiovascular problems^73,74,97,116 (see Chapter 37). Dental health care providers should consult with medical health care providers regarding the best management for each individual patient. Furthermore, dental health care providers and patients should always include the treating medical practitioner in the management decisions if postoperative bleeding is excessive or persistent. Submucosal or subdermal hemorrhage into the connective tissues and soft tissue spaces can result in hematoma formation. Postoperative bruising is a typical example of minor submucosal or subdermal bleeding into the connective tissues (Figure 77-3). Bruising and small hematomas typically resolve without special treatment or consequence. However, larger hematomas or those that occur in medically compromised individuals are susceptible to infection as a result of the noncirculating blood that sits in the space. Thus it is prudent to prescribe antibiotics for patients who develop a noticeably large hematoma.

Figure 77-2 Clinical photograph of postoperative bleeding around healing abutments after second-stage implant exposure surgery.

Figure 77-3 Clinical photograph of postoperative (extraoral) bruising indicative of subdermal bleeding into connective tissues spaces. This is a normal expectation that resolves within 7 to 14 days.

Although the incidence of a life-threatening hemorrhage from implant surgery is extremely low, the seriousness of the problem warrants the attention of everyone who participates in this type of surgery. Potentially fatal complications have been reported for implant surgical procedures in the mandible (especially the anterior region).* Massive internal bleeding in the highly vascular region of the floor of the mouth can result from instrumentation or implants that perforate the lingual cortical plate and sever or injure the arteries running along the lingual surface. Depending on the severity and location of the injury, bleeding may be apparent immediately or only after some delay. In either case, the progressively increasing hematoma dissects and expands to displace the tongue and soft tissues of the floor of the mouth, ultimately leading to upper airway obstruction. Emergency treatment includes airway management (primary importance) and surgical intervention to isolate and stop the bleeding. Clinicians must be aware of this risk and must be prepared to act quickly. It is important to recognize that bleeding, although considered a complication at the time of surgery, may be a serious complication in the hours and days after surgery.³⁸

Neurosensory Disturbances

One of the more problematic surgical complications is an injury to nerves. Neurosensory alterations caused by damage to a nerve may be temporary or permanent. Neuropathy can be caused by a drilling injury (cut, tear, or puncture of the nerve) or by implant compression or damage to the nerve (Figure 77-4; also see Figure 70-16). In either case, the injury produces neuroma formation, and two patterns of clinical neuropathy may follow. Hypoesthesia is a neuropathy defined by impaired sensory function that is sometimes associated with phantom pain. Hyperesthesia is a neuropathy defined by the presence of pain phenomena with minimal or no sensory impairment.⁶¹ Some neuropathies will resolve, whereas other will persist. The type of neuropathy is not indicative of the potential for recovery.

Figure 77-4 A, Cross-sectional image from computed tomography (CT) scan showing implant impinging on inferior alveolar nerve canal. B, Panoramic image of CT scan showing implant in lower left first molar area impinging on inferior alveolar nerve canal. Nerve is marked by tracing with software.

It is likely that neurosensory disturbances occur more frequently after implant surgery than currently reported in the literature for several reasons. First, many of these changes are transient in nature, and most patients recover completely or at least recover to a level that is below a threshold of annoyance or daily perception. Second, wide variation exists in the postoperative evaluation of patients by clinicians. Some clinicians do not examine or inquire about postsurgical neurosensory disturbances at all, thus allowing this complication to go unnoticed. Likewise, some patients may think that the altered sensation is part of the expected “side effect” of surgery and may never acknowledge or comment on its presence, especially if the disturbance is minor. Therefore it is likely that minor neuropathies exist but go unrecognized and unreported.

Neurosensory disturbances reported in the literature are most prevalent and significant when they are more serious and occur more frequently, such as those associated with lateral transposition of the mandibular nerve.^71,78 This relatively uncommon procedure is used to reposition the nerve and allow longer implants to be placed in the atrophic posterior mandible. Lateral nerve transposition procedures are associated with almost 100% incidence of neurosensory dysfunction immediately after surgery. More than 50% of these neurosensory changes are permanent (ranging from 30% to 80%).⁷⁸

Implant Malposition

Many of the aforementioned complications that arise during implant surgery can be attributed to the dental implant being placed in an undesired or unintended position. Malpositioning of dental implants is usually the result of poor treatment planning before the implant surgery, lack of surgical skill by the implant surgeon, and/or poor communication between implant surgeon and restorative dentist. Optimal implant esthetics and the avoidance of positional complications can be achieved by placing the implant in a prosthetically driven manner.^90,102 In other words, the implant should be placed with reference to the three dimensions dictated by the position of the final restoration and not by the availability of bone. The angulation is another important determinant (fourth dimension) of implant position that will affect outcome esthetics. The ideal implant position entails an accurate preparation, insertion, and placement of the implant into the alveolus in a proper three-dimensional geometry according to apicocoronal, mesiodistal, and buccolingual parameters, as well as implant angulation relative to the final prosthetic restoration and gingival margins.^82,117 (see Chapter 71).

Apicocoronally, the implant should be placed so the dental implant platform is 2 to 3 mm apical to the gingival margin of the anticipated restoration.²⁴ The actual implant position varies slightly from one implant system to another, depending on abutment design and space requirements. If the implant platform is placed too coronal, there will not be sufficient room to develop a natural-looking emergence profile and the tooth may have a squarish, unesthetic contour. If the platform is placed at or above the level of the gingival margin, a metal collar or implant exposure can occur yielding an unesthetic result (Figure 77-5). Conversely, if the implant platform is placed too apically, a long transmucosal abutment will be necessary to restore the implant. This can lead to a deep pocket and difficult hygiene access for the patient and clinician.

Figure 77-5 Clinical photograph of gingival recession around a maxillary anterior implant (left central incisor) resulting in exposure of the crown margin, the implant collar, and several threads of the implant.

Mesiodistal implants should be placed at a distance of 1.5 to 2 mm from a natural tooth and 2 to 3 mm from an adjacent implant to maintain an adequate biologic dimension.⁶² Similar to natural teeth, violation of biologic width around an implant can lead to bone loss.⁶⁷ Implants that are placed too close to each other (Figure 77-6) or natural teeth can be difficult to restore. Impression copings and impression-taking techniques must be modified. Improperly spaced implants invariably lead to chronic inflammation and periimplantitis.^47,136 Conversely, implants placed with excessive distance from an adjacent tooth or implant may require prosthetic compensation in the form of mesial or distal cantilevers, which may predispose the implant to biologic (e.g., bone loss) and mechanical (e.g., screw loosening,⁵⁹ screw fracture,¹³³ or implant fracture¹¹¹) complications, as well as difficulties with hygiene.¹³⁶

Figure 77-6 Radiograph of two mandibular anterior implants placed too close together (no proximal space) resulting in implants that will be impossible to restore.

Ideally, implants should be placed, buccolingually so there is at least 2 mm of bone circumferentially around the implant.¹²⁷ Implant exposure through the lingual or buccal cortex can predispose an individual to abscess and/or suppuration.³² Implants that are placed too far palatally/lingually require prosthetic compensation in the form of a buccal ridge lap, which may be difficult for the patient to clean and could lead to tissue inflammation.¹⁸

To obtain ideal esthetics, to avoid potential esthetic complications, and to correct bodily placement of the dental implant, the implant must be correctly angulated on insertion. In most anterior cases, it is desirable to have the implant long axis directed so it is emerging toward the cingulum. In the posterior region, the implant axis should be directed toward the central fossa or the stamp cusp of the opposing tooth. Implants that are placed with mild-to-moderate misangulations can often be corrected prosthetically with implant abutments. Minor misangulations (up to 15 or 20 degrees) can be corrected by with prefabricated stock-angled abutments; moderate misangulations (20 to 35 degrees) can usually be managed with customized UCLA-type abutments; extreme errors in implant angulations (more than 35 degrees) may deem an implant unrestorable and require it to be left submerged (i.e., sleeper) or to be removed (Figure 77-7).

Figure 77-7 Clinical photograph of maxillary anterior implant (left central incisor) placed with an extreme facial angulation resulting in an implant that emerges through the gingiva at a level that is more apical than the adjacent natural tooth gingival margins. A, Surgical exposure of malpositioned implant. B, Surgically removed implant. C, Alveolar defect resulting from surgical removal of malpositioned implant.

The ultimate complication of malposed implant(s) is implant or instrument invasion into vital structures. The most common violation of neighboring anatomy is the placement of the dental implant into the adjacent tooth root. Surgical procedures used to prepare osteotomy sites and place implants adjacent to teeth can injure the teeth either by directly cutting into the tooth structure or by damaging nearby supporting tissues and nerves. Instrumentation (e.g., drills) directed at or near the adjacent tooth may cause injury to the periodontal ligament, tooth structure, and nerve of the tooth. Depending on the extent of the injury, the tooth may require endodontic therapy or extraction. On insertion, dental implants will follow the trajectory of the osteotomy prepared by the surgical drills. Care must be taken when preparing the osteotomy to stay true to the planned path of insertion. Guidepin location radiographs taken during implant surgery can greatly reduce the potential for damaging adjacent teeth (see Figure 70-13). Radiographic analysis before implant surgery should include detection of curved, convergent, and/or dilacerated root structures of adjacent teeth that can limit implant placement.

Particular care must be taken when placing implants in the mandible so as to not encroach on the inferior alveolar canal or the mental foramen (see Chapter 53) for a description of this anatomy. Encroachment on the mandibular canal or mental foramen during osteotomy or implant placement via direct contact or mechanical compression of bone can result in injury to nerves and blood vessels. Paresthesia, hypoesthesia, hyperesthesia, dysesthesia, or anesthesia of the lower lip, skin, mucosa, and teeth may result, as well as arterial or venous bleeding.⁶⁰ The incidence of sensory disturbances after mandibular implant placement has been reported to range from 0% to 17.5%.¹⁵

In the maxilla, care must be taken to avoid dental implant perforation into the maxillary sinus. Displacement of the entire dental implant into the maxillary sinus cavity may require a Caldwell-Luc procedure for retrieval. See online section on sinus augmentation for further information about complications related to the maxillary sinus.

The risks of surgery are always present, but the complications can be minimized with an understanding of the etiologies and with proper diagnosis and treatment planning. Three-dimensional imaging (e.g., computed tomography [CT] and cone-beam CT [CBCT] scans) provides the surgeon with useful presurgical information for proper diagnosis and treatment planning (see Chapter 70). Careful surgical exposure for direct visualization and identification of the mental nerve may be indicated as well. Once identified, it is recommended to establish a “zone of safety” and to keep instrumentation and implants a safe margin away from the nerve (e.g., ≥2 mm).⁶⁰

Inflammation and Proliferation

Inflammation in the periimplant soft tissues has been found to be similar to the inflammatory response in gingival and other periodontal tissues. Not surprisingly, the clinical appearance is similar as well. Inflamed periimplant tissues demonstrate the same erythema, edema, and swelling seen around teeth. Occasionally, however, the reaction of periimplant soft tissues to bacterial accumulation is profound, almost unusual, with a dramatic inflammatory proliferation (Figure 77-8). This type of lesion is somewhat characteristic around implants and is indicative of either a loose-fitting implant to abutment connection or trapped excess cement that remains buried within the soft tissue space or “pocket.” The precipitating local factor ultimately becomes infected with bacterial pathogens, leading to mucosal hypertrophy or proliferation and possible abscess formation (Figure 77-9). Correction of the precipitating factors (e.g., loose connection, retained cement) effectively resolves the lesion. Another type of lesion resulting from a loose abutment connection is the fistula (Figure 77-10). Again, correcting the etiologic factor quickly resolves the fistula.

Figure 77-8 Inflammatory proliferation caused by a loose-fitting connection between the abutment and the implant.

Figure 77-9 A, Clinical photograph of abscess caused by excess cement trapped within the soft tissues. B, Radiograph of implant with cemented crown (same patient as in A). Notice the subgingival depth of the crown-abutment (cement line) junction, which is below the level of the adjacent interproximal bone and therefore impossible to adequately access with explorer to remove excess cement.

Figure 77-10 Fistula caused by loose implant-abutment connection (maxillary left lateral incisor).

Dehiscence and Recession

Dehiscence or recession of the periimplant soft tissues occurs when support for those tissues is lacking or has been lost. Recession is a common finding after implant restoration and should be anticipated especially when soft tissues are thin and not well supported (Figure 77-11). Improper implant positioning also predisposes periimplant tissues to recession. As noted earlier, placement or angulation of the implant too far to the buccal causes the buccal plate to resorb and has been shown to result in greater recession.¹²⁶ Another factor to consider is the thickness of the buccal plate of bone. Spray et al¹²⁷ recommended this thickness to be 2 mm or greater to support the buccal soft tissue. If this thickness is not present presurgical or simultaneous site development using guided bone regeneration is indicated. Recession is a problem that is particularly disconcerting in anterior esthetic areas. Patients with a high smile line or high esthetic demands consider such recession a failure (Figure 77-12).

Figure 77-11 A, Clinical photograph of single-tooth implant crown (maxillary right central) with moderate recession that occurred 1 year after delivery of final restoration. Recession, in this case, most likely occurred because the labial bone around this wide-diameter implant was very thin or nonexistent. B, Radiograph of wide-diameter (6 mm) implant supporting maxillary central incisor crown (same patient as in A).

Figure 77-12 Poor esthetics resulting from gingival recession and exposure of crown margins, implant collars, and threads of several maxillary and mandibular implants supporting full-arch fixed partial dentures (FPDs). Notice the thin labial tissues and erythema (especially around mandibular implant sites).

The anatomy and soft tissue support around implants is different than that around teeth. Specifically, periodontal tissues have the distinct advantage of soft tissue support from circumferential and transeptal connective tissue fibers that insert into the cementum at a level that is more coronal than the supporting bone. In the absence of inflammation, these fibers support periodontal soft tissues far above the level of crestal bone. As a result, gingival margins and interdental papillae are supported and maintained around teeth even when the periodontal tissues are very thin. Periimplant soft tissues, on the other hand, are entirely dependent on the surrounding bone for support. Soft tissue thickness accounts for some soft tissue height, but there are no supracrestal inserting connective tissue fibers to aid in the soft tissue support around an implant. Therefore soft tissue height around implants typically does not exceed about 3 to 4 mm, and bone loss around implants often leads to recession.

Periimplantitis and Bone Loss

Periimplantitis is defined as an inflammatory process affecting the tissues around an osseointegrated implant in function, resulting in loss of supporting bone.⁹⁴ To diagnose a compromised implant site, soft tissue measurements using manual or automated probes have been suggested. Although some reports state that probing is contraindicated, careful monitoring of probing depth over time seems useful in detecting changes of the periimplant tissue.^{35,110,129,130} Standardized radiographic techniques, with or without computerized analysis, have been well documented and found to be useful in evaluating periimplant bone levels.^{3,21,25,76,110} Together with periodic evaluation of tissue appearance, probing depth changes, and radiographic assessment as the best means of detecting changes in bone support. Clinicians should monitor the surrounding tissues for signs of periimplant disease by monitoring changes in probing depth and radiographic evidence of bone destruction, suppuration, calculus buildup, swelling, color changes, and bleeding.^95,99 Periimplantitis may be perpetuated by bacterial infection that has contaminated a rough (e.g., TPS, HA-coated) implant surface and by excessive biomechanical forces.^141,142 A classic trough-type defect is typically associated with periimplantitis (Figure 77-13). In cases with severely reduced bone support extending into the apical half of the implant (Figure 77-14) or in cases demonstrating mobility, implant removal should be considered.^6,98 The number and distribution of implants and the occlusal relationships influence the biomechanical forces applied to implants^109,112 (see Chapter 76). A recent review by Lindhe and Meyle from the Consensus Report of the Sixth European Workshop on Periodontology concluded that risk indicators for periimplantitis included (1) poor oral hygiene, (2) a history of periodontitis, (3) diabetes, (4) cigarette smoking, (5) alcohol consumption, and (6) implant surface.⁸⁷ Most of these risk factors (1 to 4) have been recognized and reported in the literature.⁸¹ The report suggests that although data for the latter two risk factors (5 and 6) are limited, they appear to be relevant to periimplantitis.⁸⁷

Figure 77-13 Moderately advanced bone loss around an implant with the typical circumferential trough type of boney defect.

(From Garg AK: Implant dentistry: a practical approach, ed 2, Mosby, St. Louis, 2010.)

Figure 77-14 Severe horizontal and vertical bone loss around several mandibular implants.

Implant Loss or Failure

Implant loss or failure is generally considered relative to the time of placement or restoration. Early implant failures occur before implant restoration. Late implant failures occur after the implant has been restored. When an implant fails before restoration, it probably did not achieve osseointegration, or the integration was weak or jeopardized by infection, movement, or impaired wound healing (Figure 77-15). Late implant failures occur after prosthesis installation for a variety of reasons, including infection and implant overload (Figure 77-16). In a review of the literature to evaluate biologic causes for implant failure, Esposito et al⁵⁰ found that infections, impaired healing, and overload were the most important contributing factors.

Figure 77-15 A, Radiograph of early failed implant caused by lack of osseointegration. In addition to the crestal bone loss, notice the radiolucency along the sides of the implant. B, Photograph of the failed (nonintegrated) implant (shown in A) that was easily removed along with surrounding connective tissue.

Figure 77-16 Four-unit fixed partial denture (FPD) in the posterior maxilla supported by only two implants. A, Clinical photograph of implant abutments in the posterior maxilla. B, Radiograph taken 30 months after restoration. Note the bone loss around the distal implant. C, Failed distal implant attached to failed prosthesis. The biologic failure of one (posterior) implant resulted in a long-span cantilever extension from the other (anterior) implant that ultimately led to its mechanical failure (i.e., abutment screw fracture).

(Courtesy Dr. John Beumer, UCLA Maxillofacial Prosthetics, Los Angeles, CA.)

Autogenous Bone Harvesting/Grafting

Autogenous bone from a histologic and biologic point of view has been considered the gold standard for osseous reconstruction. Bone block grafts of autogenous bone from extraoral and intraoral sources have been documented as a predictable procedure for reconstruction of defective or atrophic alveolar ridges.⁹³ Complications can occur either at the donor or recipient sites. The most common extraoral donor sites include the ilium and tibia. Complications related to extraoral donor sites are beyond the scope of this chapter. The most common intraoral donor sites include the mandibular symphysis, mandibular ramus, and maxillary tuberosity. Although each donor area has specific associated complications, the most common complications of intraoral autogenous harvesting/grafting concern those from the mandibular symphysis.

The ramus donor site is associated with a much lower incidence of complications compared to the symphysis area.^63,92 Potential complications associated with surgical harvesting of bone from the ramus include damage to the inferior alveolar nerve and trismus after surgery. Damage to the buccal nerve, although rare, has been reported as well. Surgical harvesting of bone from the mandibular symphysis region are associated with a higher incidence of altered neurosensory disturbances to the mandibular anterior teeth and soft tissues of the chin area. The incidence of mental nerve paresthesia after symphysis grafts has been reported to be as high as 43%.¹⁰⁸ Many of these paresthesias are temporary.

In addition, fracture of the mandible has been reported after bone graft harvesting from the symphysis.³⁴ Many of these complications can be avoided by proper surgical technique, good planning, and an experienced operator.

Recipient site complications include wound dehiscence, flap necrosis, graft exposure, graft contamination, infection, and problems with bone graft incorporation and resorption. Proper flap reflection, intimate fixation of the graft, and flap coverage without tension can avoid many of the potential postsurgical complications. Bone graft material including barrier membranes should be immobilized (fixated if possible). Provisional restorations should be adjusted to prevent pressure over grafted areas. Block grafts, as well as other augmentation procedures, require experience in handling hard and soft tissue, as well as a clinician who is prepared to recognize and treat complications should they arise.

Guided Bone Regeneration

Guided bone regeneration (GBR) is a procedure that utilizes a barrier membrane to isolate an area for bone growth. The technique has been well documented for horizontal (and limited vertical) ridge augmentation^23,35,77 (see Chapter 72). The most common complication associated with GBR is premature exposure of the barrier membrane and necrosis of the overlying flap (Figure 77-17). Exposure rates of expandable polytetrafluoroethylene (ePTFE) membranes during various GBR procedures range from 41% when the technique was first introduced in the early 1990s for horizontal ridge augmentation²³ to 12.5% when surgical techniques improved and clinician’s became more familiar with handling the material.¹²⁴ Once exposed to the oral environment, the membrane becomes colonized with bacteria within 3 to 4 weeks and the potential for bone regeneration under the membrane is limited to an area that is at least 2 to 3 mm from the contaminated surface.^17,125 Topical application of chlorhexidine to the exposed membrane has been advocated as a method of reducing the amount of bacteria, but it does not solve the problem and removal of the exposed membrane is necessary.

Figure 77-17 Clinical view of flap necrosis over area treated with guided bone regenerative procedure.

Other complications associated with GBR procedures include soft tissue or bone graft infection, failure to regenerate adequate bone volume and mucogingival problems, including loss of keratinized tissue and decrease in the vestibule.²³ Most of these complications are related to insufficient soft tissue healing after tooth extraction, inadequate flap design, movement of the membrane and/or graft caused by transmucosal loading and improper provisionalization, flap suturing under tension, poor surgical technique, contamination of the membrane or surgical site, compromise of the vascular supply and flap advancement for graft coverage that reduces the keratinized tissue, and vestibular depth. To prevent complications associated with GBR procedures, proper surgical technique should be employed.

Sinus Bone Augmentation

Lateral Window Sinus Lift

The lateral window sinus lift and bone augmentation procedure has been well documented and reviewed in three published systematic reviews.^4,40,139 Although survival rates of implants placed in sinus-grafted areas has been shown to be high (95%), there are intraoperative and postoperative complications associated with this procedure. The most common intraoperative complications include bleeding and perforation of the Schneiderian membrane. Bleeding usually occurs when the vascular supply to the lateral wall of the sinus is severed or damaged.⁴⁵ In most cases, if the patient does not have an underlying bleeding problem and is not taking anticoagulants, the bleeding is usually minor and relatively easy to control with local measures. Perforation of the Schneiderian membrane, as reported in the literature, has an incidence that varies from 11%¹⁴³ to 56%⁸⁰ with most clinicians reporting an incidence of approximately 20% to 30%. Minor membrane perforations can be treated by reflection of the membrane that folds on itself, whereas medium-to-large membrane perforations require the use of an absorbable membrane placed over the perforation to “patch” the opening (Figure 77-18). Very large membrane tears may be too big to repair and require aborting the procedure. Careful surgical technique and the use of newer instruments (e.g., piezoelectric surgery) have been shown to significantly reduce this complication¹⁴⁰ (see Chapter 75).

Figure 77-18 A, Large perforation of the Schneiderian membrane during a sinus elevation procedure. B, Attempts to close or reduce the size of the perforation with resorbable sutures. C, Use of resorbable barrier membranes to cover the perforation.

The most common, although infrequent, postsurgical complication associated with sinus bone augmentation is infection.^14,80,93 The incidence of infection has been reported to vary from 2% to 5.6%. Careful surgical techniques, adherence to sterility, and the judicious use of antibiotics can minimize the risk of postoperative infections. Some infections resolve with antibiotic treatment alone, whereas others require surgical debridement of the infected area. Consultation or referral to a specialist may be indicated for persistent infections.

Immediate Implant Placement

Immediate implant placement (IIP) is a protocol that places an implant in an extraction socket immediately after tooth removal and socket debridement. This procedure was originally described by Schulte et al¹²² and Lazzara⁸⁴ and has been reported to have similar implant survival rates as implants placed into healed ridges^30,88 with long-term survival rates of approximately 94%.¹³⁸ The advantages of this protocol include fewer surgical procedures (and decreased morbidity), decreased time of treatment, decreased cost, and decreased soft tissue healing time by avoiding flap reflection and advancement.¹²³ However, as with any surgical protocol, complications are possible and there are specific complications associated with IIP. These include implant failure, poor implant position, bone loss, recession of the periimplant marginal soft tissues, and compromised esthetic outcomes.

After tooth extraction, there may be a compromised socket as the result of pathology (periodontal, endodontal, or fracture) of the hopeless tooth. Proper implant position may be difficult to establish when the socket walls are missing or deficient. For example, the implant osteotomy for extracted maxillary anterior teeth should be made on the lingual incline of the lingual wall of the socket. Quite often the burs will “slip” buccally causing the osteotomy to be made too far to the buccal or at an undesired angulation. Careful use of a surgical stent, round bur, sharp initial bur, and side cutting burs can avoid slipping and improve the accuracy of implant site preparation (see Chapter 75). Although success rates of implants placed with an IIP are excellent, failure to attain primary stability in native bone apical or lateral to the socket may increase failure rates. Inability or lack of thorough debridement of an infected or compromised (e.g., tooth with an apicoectomy) socket may also increase the risks of failure.⁸⁶ Buccal plate resorption and gingival margin recession postimplant placement may expose the implant surface following integration of the implant (see Figures 77-5 and 77-11). This may, in turn, compromise the esthetic results or necessitate hard and soft tissue augmentation procedures to improve the esthetic outcome.⁸⁰ A recent published case series documented this problem for IIP postextraction without flap elevation.⁵² The risk of the previously mentioned complications may be decreased with proper case selection, proper procedures, and experience in using this protocol. Until the clinician has the knowledge and experience to use an IIP protocol, they should avoid using it in the esthetic zone.

Immediate Loading After Implant Placement

Brånemark established the concept and predictability of the osseointegrated dental implant based on a requirement for an unloaded healing period of 3 to 6 months.²² This original protocol purported that premature loading would cause micromotion of the dental implant leading to fibrous encapsulation and implant failure. However, several studies in the dental literature have shown that immediately loaded dental implants can have success rates similar to that of conventionally loaded dental implants.* Whether restoring a single tooth or a complete dentition, there are many advantages to early or immediate loading. It is critical to recognize that these advantages may come with increased risks for complications and failures. The most significant complications are failure to achieve primary stability and implant failure.

Studies have shown that using longer and wider implants can provide increased success rates when immediately loading the dental implant.^119,120 In addition, the implants should be placed in a fashion that maximizes the anterior to posterior spread leading to a greater distribution of forces over a wider area and a reduction in cantilever forces. Studies have suggested that implants placed around the arch lead to what is known as cross-arch stabilization, which can decrease the individual force and motion experienced by any individual implant.^114,131 For the fully edentulous case a minimum of 4 to 6 implants of adequate size, good stability, and properly spaced throughout the ridge is recommended to improve success with immediate load case.³⁷ Mandibular cases may require fewer implants than maxillary cases because of greater bone density, especially in the interforaminal region. If the opposing arch is restored with a removable prosthesis, fewer implants may be needed to immediately support a restoration because of a decreased opposing occlusal force.

Other contributing factors associated with increased failure rates of immediately loaded implants include implant surface and implant design. Lower success rates with immediately loaded implants have been reported with smooth (i.e., turned/machined) surface implants, especially in cases of single tooth immediately loaded restorations.^69,113,118 Studies have also suggested that the macrodesign features of an implant (e.g., threaded versus cylindrical) can affect initial stability and success rates in immediately loaded cases.^29,79

Complications of immediately loaded implants can also arise from a poorly constructed or inserted restoration despite all things going well with the surgical placement. Extreme care must be taken to achieve a passive fit of restoration and to eliminate nonworking or balancing contacts on the restoration. In addition, in full arch cases that were immediately loaded, the restoration must be designed to withstand direct occlusal force. This can be accomplished via a rigid connection and splinting the implants together in cross-arch fashion. Loosening or unseating of the provisional restoration usually indicates mismanagement of occlusal forces and be an early predictor of failure.

Immediately loading dental implants is a technique that offers many advantages but can also increase the incidence of complications and failure. This technique should only be performed by an experienced operator that is prepared and informed. Controlling micromotion postloading is tantamount to success. Meticulous case selection, which incorporates cross-arch stabilization, controlling occlusal overload, minimizing cantilevers, and increasing the anterior-posterior distribution of implant placement, can significantly increase the success rates of loading dental implants immediately after placement.

Implant Placement using a Flapless Approach

Flapless implant surgery is the placement of a dental implant without the elevation of the epithelium, connective tissue, and periosteum covering the alveolar bone. Flapless surgery is performed by either drilling through soft tissue with the implant twist drills or by removing a small circular section of tissue (“punch” procedure) before the creation of the osteotomy.⁵ Flapless surgery has been shown to be successful and has many advantages because it is minimally invasive.^26,27 The benefits of flapless surgery include a decrease in associated surgical morbidity, including postoperative pain, ecchymosis, and swelling, as well as a reduction in surgical time and intraoperative bleeding.¹⁰⁵ Studies show that when a full-thickness mucoperiosteal flap is raised, there is loss of bone volume⁵⁷ and a flapless approach results in less bone resorption. However, the lack of operator visualization of the alveolus when preparing osteotomies and placing implants may increase the potential for complications. The most common problems associated with flapless surgery are the loss of keratinized tissue when excising the crestal “circle” of soft tissue and improper positioning of the dental implant placed without direct vision. Improper positioning may result in a dehiscence/fenestration defect (Figure 77-19) or damage to adjacent vital structures.

Figure 77-19 A, Preoperative clinical view of missing single tooth #5. There appears to be good alveolar ridge shape with adequate keratinized gingiva. B, Radiograph showing good bone height and mesial-distal space available for single tooth implant. C, Occlusal view of circular “punch” incision used to access bone and prepare implant osteotomy. D, Full flap reflection (after noticing suspicious protrusion in labial vestibule) revealed implant protruding out of alveolar bone on buccal surface.

Although flapless implant surgery has many beneficial features, it is a technique sensitive procedure that requires surgical experience, an accurate surgical guide and a knowledge of the anatomy surrounding the planned implant site.

Screw Loosening and Fracture

Screw loosening has been reported to occur quite frequently in screw-retained FPDs. Screw-retained single crowns attached to externally hexed implants (i.e., those with narrow- or standard-diameter restorative interface connection surfaces) are particularly prone to this type of mechanical complication. Studies have reported screw loosening in 6% to 49% of cases at the first annual check-up.^70,96 Screw loosening was a more prevalent problem with earlier designs. For example, abutment screws were previously made with titanium, which did not offer the clamping forces of current materials. Newer abutment designs and improved abutment screws allow for an increased clamping force to be achieved without excessive torque levels, which has helped to reduce the rate of screw loosening.

Abutment or prosthesis screw loosening is often corrected by retightening the screws. Over time, however, if screws continue to be stretched, they become fatigued and eventually fracture. This problem is evident in the patient with a loose single crown. However, in the patient with a prosthesis retained by multiple implants, the ability to detect a loose screw is greatly diminished and the problem may go unnoticed until additional screws stretch, fatigue, and fracture. In either case, the biomechanical support (and resistance) for the restoration must be evaluated and if possible, changed to prevent recurrence of the problem.

Implant Fracture

The ultimate mechanical failure is implant fracture because it results in loss of the implant and possibly the prosthesis (Figure 77-20). Furthermore, removal of a fractured implant creates a large osseous defect. Factors such as fatigue of implant materials (Figure 77-21) and weakness in prosthetic design or dimension are the usual causes of implant fractures.^3,13 Balshi¹³ listed three categories of causes that may explain implant fractures: (1) design and material, (2) nonpassive fit of the prosthetic framework, and (3) physiologic or biomechanical overload. Patients with bruxism seem to be at higher risk for such events and therefore need to be screened, informed, and managed accordingly.^12,13 These patients should be fitted with occlusal guards in conjunction with placement of the final prostheses.

Figure 77-20 A, Radiograph of fractured implant (standard diameter) used to support a molar-sized single crown in the posterior mandible. B, Crown and coronal portion of implant (same as A) that fractured between the third and fourth threads.

Figure 77-21 Implant fractured at internal connection collar resulting from fatigue. This collar fracture was caused by rotational forces applied to the implant at the time of placement into dense bone. The fracture was likely the result of a combination of material weakness and density of the prepared site.

Fracture of Restorative Materials

Fracture or failure of materials used for implant-retained restorations can be a significant problem. This is particularly true for veneers (acrylic, composite, or ceramic) that are attached to superstructures (Figure 77-22).

Figure 77-22 Fractured porcelain from incisal edges of implant-supported fixed partial denture (FPD).

Esthetic Complications

The challenge of modern implant dentistry is achieving an esthetic, as well as a functional, implant restoration. Harmonious tooth shape, size, and ideal soft tissue contours are key factors for successful esthetic outcomes.⁸²

Esthetic complications arise when patient expectations are not met. Patient satisfaction with the esthetic outcome of the implant prosthesis vary from patient to patient, depending on a number of factors. As mentioned earlier, the risk for esthetic complications is increased for patients with high esthetic expectations and less-than-optimal patient-related factors (e.g., high smile line, thin periodontal soft tissues, or inadequate bone quantity and quality). In addition to the actual appearance of the final restoration, individual perceptions and desires determine the acceptance of the results. Esthetic complications result from poor implant position and deficiencies in the existing anatomy of the edentulous sites that were reconstructed with implants. An important prerequisite for achieving optimal gingival tissue contour is sufficient periimplant bone to support the soft tissues. Hard tissue defects can be treated by a variety of bone augmentation procedures.

Implant placement in the esthetic zone requires precise three-dimensional tissue reconstruction and ideal implant placement.^62,117 This reconstructive procedure enables the restorative dentist to develop a natural emergence profile of the implant crown. If the amount of available bone does not allow for ideal implant placement and if the implant is positioned too apical, buccal, or in the proximal space, an unesthetic prosthetic profile will be developed (Figure 77-23).

Figure 77-23 Poor implant position makes it impossible to restore with an esthetic, “natural appearing” restoration. A, Anterior view with removable partial dentures RPDs inserted. B, Anterior view without removable partial dentures. Notice the high level of implant cover screw/head exposure (maxillary right lateral incisor) that is significantly apical to the level of the adjacent natural tooth (cuspid) gingival margin. C, Occlusal view of same patient. Again, notice the labial projection of same implant (maxillary right lateral incision), as well as the palatal position of the implant in premolar area. Any attempt to restore the anterior implants would not be esthetically acceptable.

If crown contours and dimensions are not ideal or if gingival harmony around the implant restoration is unesthetic, the patient may consider the implants or restorations as complications because the outcome does not represent a natural appearance (Figure 77-24). Gingiva-colored materials utilized to replace lost gingival anatomy can offer an alternative to surgical augmentation in patients undergoing implant therapy (Figure 77-25). These restorations provide numerous advantages over conventional restorations, including improved lip support, masking of interproximal spaces, and restoration of gingival symmetry in selected cases.⁶⁶

Figure 77-24 High gingival margin on single-tooth implant crown in the maxillary lateral incisor position. Notice the discrepancy between gingival margin levels of the implant and the adjacent natural teeth.

Figure 77-25 Pink porcelain used on implant-supported fixed restoration to mask the high gingival margin and long implant crowns resulting from an uncorrected alveolar ridge defect.

If the patient is truly dissatisfied with the esthetic result and there is a problem with the position of the implants that can be corrected (i.e., the patient’s expectations are reasonable), the implants could be removed; the case could be reevaluated and possibly retreated. However, the clinician should consider prosthetic solutions before implant removal. Use of angulated abutments, superstructures, and gingiva-colored materials may result in an acceptable esthetic result, thus avoiding multiple surgeries necessary to rebuild hard and soft tissue if an integrated implant is removed.

Careful patient evaluation and treatment planning along with a solid understanding and appreciation for the predictability and limitations of implant procedures will minimize esthetic complications. Patients with a high smile line, high esthetic demands, thin periodontium, or lack of hard and soft tissue support in the anterior esthetic region are some of the most difficult cases to treat and should only be treated after extensive planning by experienced clinicians.

Phonetic Problems

Implant prostheses that are fabricated with unusual palatal contours (e.g., restricted or narrow palatal space) or that have spaces under and around the superstructure can create phonetic problems for the patient. This is particularly problematic when full-arch, implant-supported, fixed restorations are fabricated for patients who have a severely atrophied maxilla. These patients are probably best served with an implant-assisted maxillary overdenture because the design facilitates replacement of missing alveolar structure and avoids creating spaces that allow air to escape during speech.