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 82-2). 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^{81,82,111,132} (see Chapter 37). Dental healthcare providers should consult with medical healthcare providers regarding the best management for each individual patient. Furthermore, dental healthcare 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 82-3). 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.

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.⁴¹

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 82-4; also see Figure 73-18). 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.⁶⁸ Some neuropathies will resolve, whereas other will persist. The type of neuropathy is not indicative of the potential for recovery.

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.79,86 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%).⁸⁶ Several articles have been written on the treatment of neurosensory disturbances.^7,107,126

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.103,116 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.^91,133 (see Chapter 75).

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.²⁶ 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 82-5). 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.

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.⁷⁰ Similar to natural teeth, violation of biologic width around an implant can lead to bone loss.⁷⁵ Implants that are placed too close to each other (Figure 82-6) 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 peri-implantitis.^51,153 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,⁶⁶ screw fracture,¹⁵⁰ or implant fracture¹²⁵) complications, as well as difficulties with hygiene.¹⁵³

Ideally, implants should be placed, buccolingually so there is at least 2 mm of bone circumferentially around the implant.¹⁴⁴ Implant exposure through the lingual or buccal cortex can predispose an individual to abscess and/or suppuration.³⁵ 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.²⁰

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 82-7).

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 73-15). 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 54) 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.⁶⁷ The incidence of sensory disturbances after mandibular implant placement has been reported to range from 0% to 17.5%.¹⁶

In the maxilla, care must be taken to avoid dental implant perforation into the maxillary sinus or nasal cavity. Displacement of the entire dental implant into the maxillary sinus cavity may require a Caldwell-Luc procedure for retrieval. See the 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 73). 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).⁶⁷

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 82-8). 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 82-9). Correction of the precipitating factors (e.g., loose connection, retained cement) may effectively resolve the lesion. Another type of lesion resulting from a loose abutment connection is the fistula (Figure 82-10). Again, correcting the etiologic factor can quickly resolve the fistula.

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 82-11). 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.¹⁴³ Another factor to consider is the thickness of the buccal plate of bone. Spray et al¹⁴⁴ 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 82-12).

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 transseptal 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, however, 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.¹⁰⁸ The prevalence of periimplantitis has been reported to be controversial depending on the criteria used to define the amount of marginal bone loss necessary to be present, together with evidence of soft-tissue inflammation to determine the existence of the disease.⁸⁹ Reports of prevalence of periimplantitis have varied from approximately 7% to 37% of implants in various studies.^92,131 Recently, a proposed classification for early, moderate, and advanced periimplantitis based on degree of bone loss was presented in an attempt to improve communication when describing prevalence and treatment.⁶⁰ 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.^{38,124,146,147}