Incidence And Management Related To Third Molar Surgery Biology Essay
Complications related to Third Molar Surgery
Incidence and Management related to third molar Surgery
Faisal Hameed Rana*
22/A1 City Villas, University Road, Sector 38-A, KDA Scheme 33, Karachi 75270, Pakistan.
Complications with the surgical management of third molars are inevitably associated. The frequency and severity of unfortunate events associated with surgical procedures are influenced by multiple factors that may be related to the procedure performed, patients, or may be with surgeon. Complications related with the removal of third molars and their management are discussed in this review article.
Any tooth that fails to erupt into the dental arch within the anticipated time frame and is not considered to do so is, by definition, an impacted tooth. Failure of a tooth to erupt into the arch in a timely fashion can be due to numerous factors such as crowding from insufficient arch, delayed maturation of the third molar, malpositioned adjacent teeth, associated pathology (odontogenic cysts and tumors), trauma, previous surgical intervention, dense overlying bone (lateral positioning) or soft tissue and systemic conditions (syndromes). The mandibular and maxillary third molars are the most common impacted teeth, followed by the maxillary canines and mandibular premolars. It is of no surprise that extraction of third molars, usually impacted, is the procedure performed with the highest incidence on daily basis by oral and maxillofacial surgeons.
The indications and timing for removal of impacted third molars are lay down by various organizations such as AAOMS, NHS etc. Complication rates from the removal of impacted third molars range from 4.6% to 30.9% with an average of approximately 10%. 1, 2, 3, 4, 5, 6 The occurrence of these complications varies with surgeon skill, patient age, and depth of impaction. Several factors are known to increase the possibility of complications and these include increased age, female gender, presence of pericoronitis, poor oral cavity hygiene, smoking, depth of impaction, and surgeon immaturity and inexperience. 2, 5, 6
Third molar extraction remains one of the most ubiquitous procedures performed by oral and maxillofacial surgeons, and most third molar surgeries are performed without intra- or postoperative difficulties. In all surgical procedures, proper preoperative planning and the combination of surgical technique with surgical principles is of paramount importance for decreasing the rate of complications. Third molar removal is no different, yet such a common procedure sometimes results in what are relatively rare complications. The possibility of these events should be discussed with patients before the procedure and handled in a timely and corrective manner by the surgeon. Complications related to third molar removal range from 4.6% to 30.9%. 1, 6 They may arise intraoperatively or develop in the postoperative time.
For the sake of convenience Robert D. Marciani 7 divide third molar complications into
Complications related to the patient
Age of patient
Unfavorable anesthetic candidate
Poor perioperative compliance
Limited space to deliver the luxated tooth
Limited jaw opening
Large, thick cheeks
Limited maxillary labial vestibule space
Complications related to the procedure
Poor surgical access and visibility
Malfunctioning surgical drills or wrong anesthetic technique
Timing of surgical procedure
Aberrant tissue consistency
Wrong or unnecessary procedure
Complications related to the surgeon
Errors in patient selection
Errors in choosing procedure
Poor surgical technique
Failure to honor patient’s complaints
Delay in identifying complications and introducing interventions
Unnecessary or imprudent surgery
Failure to thoroughly examine the patient clinically and radiographically
The aim of this article is to provide a comprehensive review of the common as well as rare peri- and postoperative complications associated with impacted third molar surgery and offers a preventive or management strategy.
ALVEOLAR OSTEITIS (AO)
Alveolar osteitis (AO) or "dry socket" is a clinical diagnosis with an incidence of between 1% and 37%. 1, 4, 5, 6, 8 This wide range can best be explained by varied definitions of AO. Some studies define AO as pain or discomfort that requires the patient to return to the Dentist or Oral and Maxillofacial surgeon’s office, while others define it as simply based on a clinical diagnosis of AO. In addition, some studies report only those teeth that required surgical extraction or use varied surgical protocols. 5, 6, 8, 9 The average incidence of AO in a private practice setting based on a survey of AAOMS members was 6.5%. 6 Contributing factors to the development of AO include the use of oral contraceptives, smoking, increasing age, female gender, presence of pericoronitis, surgical time, surgical trauma, and compromised medical status. 6, 8, 9
AO is often described as the loss, lysis, or breakdown of a fully formed blood clot prior to its maturation into granulation tissue. Patients will present with a myriad of symptoms and signs for approximately 3 to 5 days following extraction. The most common complaints are pain, malodor, and foul taste that do not respond well to oral analgesics and often keep a patient up at night. Clinically, a gray-brown clot or the complete absence of an organized clot may be present in the extraction socket. Food debris may or may not be present and the surrounding tissue may be erythematous and edematous. The site is exquisitely tender and often patients will have referred pain to other areas of the head and neck including the ear, eye, or temporal and frontal regions.
The incidence of AO can effectively be decreased through a variety of interventions, all of which focus on decreasing bacterial counts at the surgical site. Chlorhexidine gluconate 0.12% presurgical irrigation either with or without postoperative rinses has shown to be beneficial in decreasing the incidence of AO. 8, 9, 10 Copious irrigation and lavage of the surgical site with normal saline has been reported to decrease AO. In one study, it was as effective as pre- and postoperative rinses with chlorhexidine, and normal saline. Others have demonstrated no significant difference between pulse lavage and hand syringe irrigation. Intra-alveolar antibiotics, specifically tetracycline, lincomycin, or clindamycin may also decrease the incidence of AO. 9 Postoperative antibiotics have not consistently shown an ability to influence the development of AO and the evidence to support preoperative or intraoperative systemic antibiotics is controversial. 3, 8, 9 Most studies do not demonstrate a substantial difference. Overall, good surgical technique with minimal trauma, copious irrigation, and the use of chlorhexidine rinses or topical antibiotics have shown promise in decreasing the incidence of AO.
The objective in treatment of AO is to relieve pain until adequate maturation of the healing socket has occurred. Most treatment regimens focus on gentle irrigation with or without mechanical debridement and placement of obtundant dressings. Interestingly, there is very little evidence to support the use of a certain dressing or medicament over another. Commonly, iodoform gauze and eugenol are used to "pack" the socket and this packing is changed QD or QOD. 4, 9 Eugenol is a member of the phenylpropanoid class of chemical compounds and is beneficial due to its inhibition of neural transmission and neurotoxicity. Iodoform is an organoiodine compound that has antibacterial properties and has been used since the early 20th century as an antiseptic wound dressing. Most commercially available dry socket pastes or dressings include eugenol in combination with various other medicaments such as guaiacol, chlorobutanol, balsam peru, and butamben. The use of gelfoam as a carrier and obtundant dressing has also been reported. Patients should be seen regularly for follow up to ensure elimination of symptoms and if iodoform packing is used, to change or remove the packing. It is important to avoid the use of eugenol and other neurotoxic chemicals in the presence of an exposed inferior alveolar or lingual nerve. The use of systemic antibiotics is not recommended for treatment of AO. 9 Typically, patients will have resolution of symptoms within 3 to 5 days; however, in certain patients it may take up to 14 days for complete resolution.4,8 In summary, AO is one of the more common complications of third molar surgery. Its incidence can be decreased though a combination approach of preoperative rinses, irrigation, and/or local antibiotic application, and its treatment is straightforward.
Surgical wound infection rates as a result of third molar extraction range from 0.8% to 4.2%, and almost exclusively involve the mandibular third molar sites. 1, 2, 3, 4, 5, 6, 11, 12 According to most general surgery and infectious disease literature, any surgical procedure within the oropharynx is considered a clean-contaminated wound, a class II wound, and carries a less than 10% risk of surgical site infection (SSI). If inflammation without purulence is noted, such as that with pericoronitis, the wound is then classified as contaminated, class III, and carries an SSI rate of 20%. The presence of purulence or necrotic tissue at the time of surgery results in a 40% risk of SSI. Class I data are available to support the use of preoperative antibiotic prophylaxis for clean-contaminated wounds; however, there are no data to support continued antibiotic administration beyond the first 24 hours after surgery. 13, 14, 15 In relation to third molar surgery, 50% of infections are localized subperiosteal abscess-type infections occurring approximately 2–4 weeks after surgery. 11 This type of infection is attributed to debris left under the surgically created mucoperiosteal flap and would likely not be prevented with the use of antibiotic prophylaxis. The remainder of third molar SSI cases are rarely severe enough to necessitate further surgery or antibiotics. SSI within the first postoperative week occurs only 0.5–1.0% of the time. 11, 12, 16
The risk of developing an SSI associated with the removal of third molars increases with degree of impaction, need for bone removal or sectioning of the tooth, the presence of gingivitis, periodontal disease and/or pericoronitis, surgeon experience, increasing age, and antibiotic use. The benefit of systemic antibiotic administration on the incidence of SSI in relation to third molar extractions is questionable and is not currently recommended since the incidence of complications from antibiotic administration is higher than the incidence of SSI: 11% and 0.8% to 4.2%, respectively. 11 16 It is also unlikely that perioperative systemic antibiotics are of any benefit in delayed, subperiosteal-type infections due to the nature of these infections as described previously. 11
Signs of SSI can vary from localized swelling and erythema to fluctuance and trismus or systemic manifestations with fevers, dehydration, etc. 11 The treatment of SSI due to third molar surgery involves surgical incision and drainage in addition to the administration of systemic antibiotics. Penicillin is often used, as the vast majority of infections are caused by a mixed flora of micro-organisms with anaerobic and gram positive streptococci being the most common. Amoxicillin has a slightly wider spectrum of activity and metronidazole can be added to cover anaerobic organisms. For the penicillin-allergic patients, clindamycin is a good choice of antibiotic and can also be used when aerobic and anaerobic coverage is desired. Most often, patients will present with a vestibular, body of the mandible, or localized subperiosteal abscess. Arare occurrence is the spread of infection along fascial tissue planes and involvement of multiple potential spaces. This situation requires surgical drainage, IV antibiotics, and close follow-up as progression to parapharyngeal, submandibular, and retropharyngeal spaces can lead to airway embarrassment and even mediastinal abscess formation with potentially fatal result. 11 16
BLEEDING / HEMORRHAGE
The incidence of clinically significant bleeding as a result of third molar surgery ranges from 0.2% to 5.8%. 4, 5, 6 According to the AAOMS Age-Related Third Molar Study, approximately 0.7% occur intraoperatively & 0.1% postoperatively. 1 Significant bleeding or hemorrhage is most often associated with mandibular third molar surgery (80%) when compared with maxillary third molar surgery (20%). 17 Specific risk factors include advanced age, distoangular impactions, and deep impactions.6 Massive intraoperative bleeding is a rare occurrence and is often attributed to the presence of an arteriovenous malformation (AVM). 17 As such, examination of the surgical site for gingival discoloration, palpable thrill, or bruit is necessary. Imaging may demonstrate a multilocular radiolucency in the area of AVM in proximity to the third molar tooth. In these patients, angiography is essential to confirm diagnosis and treatment with embolization is often necessary.
The most common inherited bleeding disorder, von Willebrand disease, affects an estimated 1% of individuals. Hemophilia A or B is present in 1 in 5,000 live births. Depending on patient age and sex, the first surgical procedure a patient undergoes may be third molar extraction as patients with mild to moderate forms of certain coagulopathies may be undiagnosed. Patients with an acquired or congenital coagulopathy will require further workup prior to surgery. Depending on the specific condition, recent laboratory values, factor replacement, hematology consultation, or inpatient surgery may be necessary.
Antithrombotic treatment with medications such as warfarin, thienopyridines, or aspirin is commonly encountered among patients requiring extractions. Warfarin and clopidogrel rank among the top 100 prescribed medications in the United States, an estimated 25% of individuals over age 75 currently take warfarin, and, according to the FDA, over 100 billion aspirins are taken each year. Most current literature does not recommend withholding these medications for tooth extraction. The risk of a thrombotic event outweighs any benefit of holding the medication. In patients taking warfarin, a preoperative INR (international normalized ratio) may be of value. According to Potoski, a value of 4.0 is acceptable for minor surgical procedures, 3.0 if also taking clopidogrel, aspirin, or other antiplatelet medications, and 2.5 for more involved surgery. 17
The treatment of bleeding or hemorrhage begins with local measurements, pressure with gauze, and packing. Intraoperative bleeding from soft tissues can usually be controlled with cautery, taking care to avoid any neurovascular structures. Bone bleeding or bleeding from extraction sockets can be controlled through a variety of measures. Intra-alveolar hemostatic agents such as gelfoam, surgicel, avitene, collaplug, collatape, thrombin, tiseel, or bone wax may be used alone or in various combinations. Over suturing and primary closure of the wound can also assist in hemostasis and containment of the various hemostatic agents. Oral rinsing with an antifibrinolytic such as Amicar® (epsilon-aminocaproic acid) or Cyclokapron® (tranexamic acid) can aid in maintenance of an organized clot. 17
In the case of prolonged postoperative bleeding, the patient should be instructed to remove loose clots and bite firmly and continuously on a moist gauze pack for 30 minutes. If this is unsuccessful, exploration and debridement of the wound should be completed under local anesthesia without vasoconstrictor to allow for diagnosis of the cause of bleeding. Granulation tissue should be debrided, irregular sharp bony edges removed, and hemostatic agents used within the alveolus to assist in bleeding control. As with intraoperative bleeding, over suturing and primary wound closure can assist in hemostasis and maintenance of the various hemostatic agents.
Mandibular fracture following third molar surgery is a rare occurrence and most often associated with deeply impacted third molars in patients over 40 years of age. 18 The reported incidence of mandibular fracture both intraoperative and postoperative ranges from 0.00490% to 0.00003% with a mean time to fracture ranging from 6.6 to 14 days following surgery according to studies by Iizuka and Krimmel respectively. 18,19 Fractures up to 28 days following surgery have been reported and no fractures reported beyond 6 weeks after surgery. 19, 20 This time period correlates with increased masticatory forces due to decreased trismus, pain, and edema. Libersa, in his review of 37 fractures from 750,000 extractions, found that 8 of 10 late fractures occurred in men with 6 occurring during mastication. 18 Risk factors for fracture include age over 40, male, advanced atrophy, associated pathology such as cysts or tumors, osteoporosis, full dentition and
bruxism. 18, 19, 20 The angle region of the mandible is of particular risk for fracture due to its relatively decreased cross-sectional area. The presence of a deeply impacted, fully developed third molar can occupy a significant portion of this cross-sectional area leaving little support following surgical extraction. 19 Intraoperative mandibular fracture is almost exclusively due to the application of excessive force during third molar surgery. Often, it occurs during the use of dental elevators combined with the application of heavy pressure beyond that required to extract the tooth. 4 In patients over 40 years of age presenting with partial bone impactions (loss of external oblique ridge) and risk factors, even light force can cause fracture. 18
Should a fracture occur during or after third molar surgery, it should be treated immediately. Open reduction and internal fixation can be easily accomplished in this region using the Champy technique with tension band plating. Alternatively, closed reduction with intermaxillary fixation may be appropriate in certain cases. Regardless of the technique, the complication should be communicated to the patient and/or guardian and treatment initiated.
The extraction of maxillary molars can lead to a communication between the maxillary sinus and oral cavity. If this communication does not heal, or is treated inappropriately, it can lead to development of an oral-antral fistula (OAF). The incidence of oral-antral communication (OAC) from third molar extraction ranges from 0.08% to 0.25%; however, documented cases may under represent the actual number of cases due to the self-limiting nature of most communications and flap closure following impacted third molar removal. 1, 2, 3, 4, 5, 6 It should be noted that OAC is more common at the first molar site followed by the second molar site and all patients should be alerted to the possibility of OAC and even OAF following removal of maxillary molars. 3, 4
When extracting maxillary molars in close approximation to the sinus, especially when sinus pneumatization and widely divergent roots are noted radiographically, excessive force should be avoided and consideration for sectioning of roots made. Predisposing factors include pneumatization around the tooth roots, periapical infection, acute / chronic sinusitis, adjacent edentulous spaces, and traumatic extraction. 3, 4, 6 The assessment of an OAC should include the etiology, location, and size of the defect. Identification of an OAC can be assisted by having the patient perform the nose-blow test. The patient should pinch the nostrils together preventing air flow out of the nares. Next, have the patient attempt to blow gently though the nose while observing the extraction site. If an OAC exists, air will pass through it and bubbling of blood/fluid in the socket is observed. Another method also uses the nose-blow test but instead of observing the site directly, a mirror is placed near the site and is observed for fogging of the mirror. This test can be of particular use in third molar OAC due to the inability to visualize the depth of the socket in certain patients. Additionally, if upon inspection of the extracted tooth a segment of bone remains attached to the tooth toward the root apices, it is likely a communication exists. However, if no bone is present, this does not rule out the possibility of an OAC. The surgeon must avoid the temptation to probe or explore the extraction site as this can perforate an intact membrane and introduce foreign material, including bacteria, into the sinus cavity.
Once the surgeon has determined an OAC exists, the size of the defect should be appreciated. Defects less than 2 mm in diameter will close spontaneously. If desired, measures can be taken to ensure stability of a quality blood clot in the extraction site. A collagen plug, gelfoam, and/or sutures can be placed to assist in clot formation and maintenance. A moderately sized defect of 2–6 mm in diameter will require additional measures to aid closure of the OAC. A figure-of-eight stitch should be placed over the tooth socket to assist in clot maintenance, and gelfoam or a collagen plug can be placed within the socket to assist in formation of a stable clot. In addition, multiple medications should be prescribed to prevent congestion and development of maxillary sinusitis. Amoxicillin, cephalosporins, augmentin, or clindamycin can be prescribed. Nasal decongestants such as oxymetazoline and pseudoephedrine should be prescribed along with a nasal irrigant (saline nasal spray) to ensure patency of the ostium and normal sinus drainage. Oxymetazoline should only be used for a period of 3 days, as rhinitis medicamentosa can occur. Also, patients should be placed on sinus precautions to avoid increasing or decreasing pressure within the sinus. Specific instructions should be given to the patient to avoid sneezing though the nose, smoking, drinking with a straw, or blowing their nose. Smokers who cannot abstain should be informed of an increased risk of OAF development and smoke in small puffs to avoid changes in sinus pressure. A large defect, 7 mm or more in diameter, will require additional surgical procedures. Buccal or palatal flaps can be rotated to allow for primary closure. Gelfoam or collagen should be placed within the socket and the patient followed closely.
Patients with OAF may present weeks, months, or even years following extractions. Symptoms of unilateral sinus pain and pressure, nasal congestion, intraoral discharge/purulence, bad taste, or fluid communication between the mouth and nose may be noted. On exam, the area may be edematous and erythematous with granulation-like tissue bulging from the fistulous tract. Gentle probing of the area and X-ray examination with a radiopaque material within the tract can confirm the presence of an OAF. Treatment involves an initial period of antibiotic, nasal decongestant, nasal irrigant, and sinus precautions. Following resolution of acute infection and decreased sinus inflammation, surgical repair can be undertaken. Treatment should include excision of the sinus tract with inversion into the sinus to close the sinus side of the communication. The oral side can then be closed with a buccal advancement flap or palatal finger flap, buccal fat pad advancement flap, pedicle tongue flap, cheek mucosal flap, or temporalis myofascial flap. Excellent sources with detailed description of these techniques are available in the published literature. 4, 21 An interpositional material such as bone graft, gold foil, or bioabsorbable material can be used as a third layer of closure. Recently, Watzak described a press fit, autogenous bone graft, technique for closure of OAF with subsequent conventional sinus lift and implant placement. 22 Following surgery thepatient should be placed on sinus precautions for 3 weeks and continued on antibiotics, decongestants, and nasal irrigations.
INJURY TO ADJACENT TEETH / WRONG TOOTH EXTRACTION
The most common injury to an adjacent tooth is loosening or fracture of a large restoration. 3, 4 Other injuries can include tooth loosening due to inappropriate use of elevators, crown fracture due to caries, and inadvertent extraction of an adjacent tooth. 3, 4 The incidence of injury to an adjacent second molar when performing third molar surgery is between 0.3% and 0.4%. 1, 2, 5, 6 Limited data exist regarding inadvertent extraction of an adjacent tooth specifically during third molar surgery; however, the overall incidence of wrong tooth extraction ranges from 0.026% to 0.047%. 3
Adjacent teeth with large restorations, caries, or recurrent decay pose a risk for inadvertent injury. Evaluation of adjacent teeth both clinically and radiographically should be completed prior to beginning a procedure, and patients should be made aware of the possibility of injury. If an adjacent tooth poses a high risk for injury, attempts should be made to avoid luxation with elevators adjacent to the tooth or consideration should be given to not using an elevator at all. To avoid injury to the opposing dentition during extraction, excessive traction forces should be avoided. If a tooth suddenly releases, this can result in instrument damage to opposing cusps. Also, placing a finger or suction tip in between the forceps and opposing dentition can prevent contact with the instrument or absorb some of the blow. Wrong tooth removal should never occur if adequate attention is given to planning and appropriate time out. The tooth to be extracted should be marked on the radiograph and confirmed with both the patient and the assistant in terms the patient can understand. Referrals should be contacted if confusion exists as to the correct procedure. 3
If an injury occurs, it should be promptly treated and all parties involved notified. A fractured tooth or restoration can be temporized and the referring practitioner notified. Loosened or avulsed crowns can be recemented if no recurrent decay exists or temporarily cemented if caries are noted. If an adjacent tooth is loosened it should be repositioned and stabilized. Often, this requires only minimal repositioning, and the tooth can be left alone. If significant loosening has occurred, stabilization for 10–14 days with the least rigid method of stabilization should be used to avoid risk of ankylosis or root resorption. Extraction of the wrong tooth, if immediately noted, can be treated as an avulsion. The tooth should be implanted back into the extraction site and stabilized. If the tooth is being extracted for orthodontic reasons, the remaining teeth should not be extracted and a call should be placed to the referring orthodontist. 3 Occasionally, modification of the treatment plan can be done to utilize the tooth that should have been removed and treatment can proceed with the new plan. If the original tooth planned for extraction needs to be removed, the health and stability of the accidentally extracted tooth should be confirmed prior to proceeding with further extractions. When the error goes unnoticed at the time of extraction, the tooth can obviously no longer be replanted. It is important to document thoroughly any case of wrong tooth extraction and inform all parties involved. According to data from the Oral and Maxillofacial Surgery National Insurance Company (OMSNIC), 46% of all wrong-site tooth extraction claims are settled with an indemnity payment. Thus, documentation and communication with both the patient and referring dentist are important to avoid litigation.
INJURY TO ADJACENT OSSEOUS STRUCTURES
During the process of third molar extraction, and more specifically maxillary third molar extraction, the surrounding bone is at risk for inadvertent fracture. The most likely places for bone to fracture during removal of maxillary third molars are the buccal cortical plate and maxillary tuberosity. The incidence of maxillary tuberosity fracture in association with third molar extraction is approximately 0.6% and is most often caused by excessive force with forceps or elevators. The combination of Type IV bone, no distal support, and often significant space involvement by maxillary sinus contribute to the potential for tuberosity fracture. 3, 23
Maxillary tuberosity fracture or buccal cortical plate fracture can compromise future prosthetic rehabilitation as the maxillary tuberosity is an important anatomical retention point for complete dentures. Buccal plate fracture can lead to soft tissue tearing and irregular remaining alveolar bone. To avoid these complications the surgeon should ensure appropriate force application and remove bone in a controlled fashion when excessive force is necessary for extraction. In addition, placement of a periosteal elevator distal to the third molar to elevate the tooth and separate it from the periodontal ligament and tuberosity can assist the surgeon in avoiding a tuberosity fracture.
When a fracture of the buccal cortical plate occurs, the surgeon should asses the stability, size, and soft tissue attachment of the fractured segment. If the surgeon has been supporting the alveolus with finger pressure during extraction, early cortical plate fracture can be assessed. At this point, the cortical plate should be dissected free from the tooth with an elevator or other sharp instrument while the tooth is stabilized with forceps. Once the bone and soft tissue are dissected free, the tooth is extracted and the tissues approximated and secured with sutures. If a soft tissue flap is reflected from bone, the blood supply to the segment has been compromised, and that segment will become necrotic if not removed. Maxillary tuberosity fractures should be treated in a similar manner. Once recognized, the fractured segment should be dissected free from the tooth. Using a handpiece, the bone segment can be separated from the tooth and the roots sectioned to allow for atraumatic extraction. If adequate soft tissue attachment remains, the tuberosity is stabilized through good soft tissue closure with sutures. In the event that the tuberosity cannot be dissected free from the tooth, the reason for extraction should be revisited. If asymptomatic, the tooth and attached tuberosity segment can be fixated for 6–8 weeks via an arch bar or orthodontic fixation followed by surgical extraction with controlled bone removal and tooth sectioning on a later date. If symptomatic, the tooth must be extracted and in doing so, the tuberosity will be removed. The remaining bone should be smoothened and soft tissues approximated with sutures. The overall goal of treatment in a tuberosity fracture is to maintain the bone in place unless its removal is absolutely necessary. 3, 23
PAIN AND SWELLING
Postoperative pain and swelling following third molar surgery is an expected and inevitable consequence of the inflammatory process of healing. The onset of swelling and pain is directly related to an increase in local levels of prostaglandins, leukotrienes, and thromboxane A2. Pain usually reaches its peak in 3–5 hours following surgery. On the other hand, swelling reaches its peak in 24–48 hours and then generally begins to decline on postoperative day 3 or 4. Contributing factors in the development of pain and swelling include operating time, difficulty in extraction, excessive retraction, and the degree of surgical trauma. 3, 4
"Treatment" of swelling and pain can begin prior to surgery. Preoperative IV steroids have been shown in multiple studies to decrease postoperative swelling, pain, and improve health-related quality of life. 24 During surgery, good surgical technique, copious irrigation, and the use of long-lasting anesthetics such as bupivicaine have been shown to decrease pain and swelling. Postoperative scheduled use of nonsteroidal anti-inflammatory (NSAID) drugs has been shown to be more effective in pain reduction than narcotic medications, and as such, narcotics can be better reserved for breakthrough pain. 3, 4
The occurrence of temporomandibular joint (TMJ) injury as a result of third molar surgery is not supported in the literature. In a study by Threlfall, patients with diagnosed anterior disk displacement were no more likely than the control group to have had prior third molar surgery.24 Also, only 9.5% of patients with anterior disk displacement reported third molar extractions within the past 5 years. Complaints of limited opening are most often due to trauma from injections, inflammation of the muscles of mastication, and/or the body’s own protective mechanism to limit function and further trauma. 25
Injury may occur if excessive force is used, a bite block is not in place when extracting lower third molars, or the patient’s mouth is opened excessively. 4, 25 This transient injury often resolves with soft diet, moist heat, jaw rest, and NSAID use. An acutely "stuck disc" can be treated effectively with arthrocentesis when observed. 25
It is important to evaluate all patients undergoing third molar surgery for preoperative joint disease or myofacial pain and thoroughly document all such history. Clicks, pops, crepitus, opening and excursive movements, and any tenderness of the muscles of mastication should be noted. If prior TMJ dysfunction is present, contemplation for surgical extraction of teeth to avoid trauma to the joint should be made.
DISPLACEMENT OF TEETH
The iatrogenic displacement of maxillary and mandibular third molars into adjacent spaces is a rare complication with an unknown incidence. 26 Maxillary third molars can be displaced into the maxillary sinus, buccal vestibule, or posteriorly through periosteum and into the infratemporal fossa. 3, 4 Contributing factors for the displacement of maxillary third molars include superior-distal impaction, poor visualization and access, inadequate bone removal, lack of a distal stop, and careless elevation. 26 Displacement of mandibular third molars into the submandibular, sublingual, pterygomandibular, and even lateral pharyngeal spaces has been reported along with displacement of roots into the inferior alveolar canal. 3, 4 The lingual cortex becomes progressively thinner in the more posterior regions of the mandible, and this often results in an extremely thin or even dehisced lingual plate. Any apically directed force may easilydisplace root segments or an entire tooth into the aforementioned spaces. 3
The management of a displaced third molar tooth or root varies depending on the space involved. Maxillary third molars displaced into the maxillary sinus should be removed. Root tips less than 3 mm can be left to fibrose into the sinus mucosa if no previous infection of the tooth or sinus is present and initial attempts at retrieval are unsuccessful. 3 The morbidity of additional surgical procedures outweighs the benefits of removal in this case. An attempt to remove the tooth through the socket can be made by placing the suction near the opening into the sinus. Additionally, the sinus can be irrigated through the OAC and suction placed at the opening in an attempt to flush the tooth or root segment out. If the segment is visualized, the opening can be enlarged to allow retrieval. If this is unsuccessful the surgeon should abandon further attempts at removal through the socket and remove the tooth segment via a Caldwell-Luc approachinto the maxillary sinus. This can be completed at the time of initial surgery or in a second procedure. If delayed retrieval isplanned, the patient should be placed on antibiotics, decongestants, and the OAC closed as described previously. 3, 4
The retrieval of a maxillary third molar displaced into the infratemporal fossa can be complicated by bleeding from the pterygoid plexus, poor visualization, or inability to locate and stabilize the tooth. 26 In general, the tooth is located lateral to the lateral pterygoid plate and inferiorly to the lateral pterygoid muscle. Lateral and PA cephalometric films can assist in localizing the tooth. The surgeon should extend the original incision distally to the tonsillar fauces and with blunt dissection, attempt to locate the tooth. If this attempt is unsuccessful, the tooth should be left in place and the patient placed on antibiotics. Never attempt to grab or probe for the tooth as injury to adjacent structures or further displacement of the tooth can occur. If asymptomatic, the tooth can be left in place and the patient followed closely. Pain, infection, limitation of opening, and patient desire are all indications for removal. This is completed in 4–6 weeks to allow for fibrosis to occur, the tooth to stabilize, and appropriate imaging [CT, cone beam CT (CBCT)] to be obtained. Multiple approaches have been described in the literature including CT-guided surgery, needle-guided fluoroscopic retrieval, transoral retrieval, and hemicoronal flaps. 3, 4, 26
Displaced mandibular third molars are most often located in the submandibular space, inferior to the mylohyoid muscle. Attempts at removal should begin with digital pressure against the lingual surface of the mandible to try and force the root segment back into the mouth/extraction site. The opening into the floor of the mouth can be slightly enlarged to assist in retrieval; however, this should be completed cautiously to avoid injury to the lingual nerve. A lingual full thickness flap can be carefully reflected and the mylohyoid muscle incised to gain access to the submandibular space. Due to limited space, hemorrhage, and poor visibility, it may be very difficult to remove the tooth or root segment via this method. Allowing for fibrosis to occur and returning at a later date to remove the tooth or root is acceptable. Often, this is completed via an extraoral approach in the operating room and after CT scanning completed. Yeh has described an intraoral/extraoral approach where a 4-mm skin incision is made to allow for insertion of a hemostats and/or Kelly forceps and stabilization of the tooth while the tooth is located and removed via an intraoral lingual full thickness flap. 4
Displacement of a root into the inferior alveolar canal should be approached with caution. Attempts at retrieval can further damage the nerve or further displace the root. If the root segment was not infected and the patient does not complain of neurologic findings, leaving the root segment is acceptable. If the root is infected or the patient has complaints of neurologic involvement, it must be removed with caution and consideration should be made for referral to a microneurosurgeon if neural repair becomes necessary. 4
The incidence of foreign body aspiration or ingestion is likely underreported in the literature. Approximately 92.5% of objects are ingested while the remaining 7.5% are aspirated. 3, 4 Patients who undergo the surgical removal of third molars are often sedated, which results in their gag and cough reflexes being obtunded. A pharyngeal curtain should be utilized in all patients to prevent aspiration or ingestion during surgery. If the patient is not coughing or in any respiratory distress, it is likely the tooth has been ingested and prompt referral to an emergency room for abdominal and chest radiographs to confirm the location of the object should be made. Coughing that continues or leads to respiratory distress should alert the surgeon to probable aspiration. An attempt to suction the object from the oral pharynx should be made and ACLS protocols activated. The Heimlich maneuver should be used to attempt to dislodge the object. If a patient becomes cyanotic or unconscious, an attempt at retrieval under direct laryngoscopy can be made. If this fails, cricothyrotomy may be necessary to secure the airway. An object that passes through the vocal chords will most likely end up in the right main stem bronchus or right lung, and the patient should be transported to the emergency room and arrangement for bronchoscopy and object retrieval should be made.
The incidence of neurologic complications as a result of third molar surgery ranges from 0.4% to 11%. 1, 2, 5, 6, 27 Injury to the inferior alveolar nerve (IAN) is associated with spontaneous recovery in 96% of cases and spontaneous recovery of lingual nerve injury is approximately 87%. 27 Sensory deficits that last longer than 1 year are likely to be permanent; recovery of sensation should begin within the first 8 weeks following surgery. 27 According to the AAOMS white paper on third molars, the incidence of IAN injury 1 to 7 days postoperatively is 1–5% and persistent alteration in sensation after 6 months ranges from 0.0% to 0.9%. 1 Lingual nerve injury 1 day after surgery was reported in 0.4–1.5% of patients, with persistent sensory alteration at 6 months in 0.0–0.5% of patients. 1 The use of lingual retraction increased the incidence of temporary pa esthesia; however, the incidence of persistent findings remained the same. In a study by Tay et al., 192 inferior alveolar nerves in 170 patients were exposed during third molar surgery. Twenty percent reported paresthesia at the 1 week follow-up, and 6% had persistent paresthesia at 1 year. 28
An increased risk of IAN injury is associated with increased age, complete bony impaction, horizontal angulation, sectioning of the tooth multiple times, bone removal, surgeon’s experience, and duration of surgery. 27 Additionally, Rood et al. has described several radiographic predictors of potential nerve injury. 29 These include diversion of the IAN canal, darkening of the root, and interruption of the white line. One in three patients with canal diversion, and one in four patients with darkening of the root or interruption of the white line, exhibited impairment of sensation. These signs are highly sensitive but not highly specific for risk of injury, and the absence of all signs has a strong negative predictive value. 29 Therefore, patients without any significant indicators of injury are unlikely to have injury, patients with an injury are likely to have at least one of the predictors, and patients without injury commonly have predictors of injury radiographically. Other reported radiographic indicators such as deflected roots, narrowing of the root, dark bifid roots, and narrowing of the canal were statistically unrelated to nerve injury. 29
Lingual nerve injury is associated with distoangular inclination, lingual orientation, and perforation of the lingual cortex. 30, 31 Often, flap reflection, tooth sectioning with extension into the lingual plate, or lingual plate fracture are the cause of injury. 30, 31 Due to the nerve’s variable position, care must be taken when incisions are made and flaps reflected. Miloro et al. reported 10% of lingual nerves positioned superior to the lingual crest and 25% in direct contact with the bone. 32, 33 The mean vertical distance from the crest is 2.75 mm and the mean horizontal distance from the lingual plate is 2.53 mm. 32
Injury to the lingual or inferior alveolar nerve due to local anesthetic injection occurs in approximately 1 in 785,000 cases with 79% affecting the lingual nerve and 21% the IAN. The highest incidence is associated with prilocaine or articaine injection. The majority of cases (85%) resolve within 8 weeks and of the remaining 15%, one-third will eventually resolve. 34 Unfortunately, patients with persistent paresthesia are not candidates for microneurosurgical repair.
All patients who report paresthesia should be followed closely for resolution and appropriate objective testing should be performed. The clinical neurosensory test should be performed to determine the degree of impairment and whether microneurosurgical intervention is necessary. Mechanoceptive testing begins with Level A testing. It comprises brush stroke directional discrimination and two-point discrimination. It is important to test both normal and abnormal areas, map out the area of impaired sensation by marking directly on the patient’s skin, and photograph the markings for future reference. Two-point discrimination can be tested using a Boley gauge or the noncotton end of a cotton tip. Testing should be completed in 2-mm increments until the patient can no longer discern two separate points. Normally, the IAN tests to 4 mm and the lingual nerve to 3 mm. 27 Level B testing involves contact detection and Level C pin-prick and thermal discrimination. The indications for repair are complete anesthesia beyond 1–2 months, profound hypoesthesia with no improvement after 3 months, early dysesthesia, and a clinically observed Sunderland V transe tion. 27, 35 Referral to a surgeon proficient in microneurosurgery should be made if any of the above criteria are met or if unfamiliar with nerve testing and possible treatment protocols. 27
Bony sequestra and lingual plate exposure are potential complications of low significance but require thorough and prompt attention. Small bony sequestra will spontaneously extrude through the soft tissues and usually cause only temporary discomfort. Reassuring the patient or parent that there is no remaining tooth in the area, the usual concern at presentation, and removing the loose bone is all that is required. The injury to the soft tissues is resolved within few days, and the patient is instructed to avoid trauma from chewing in the area until this occurs. Exposure of the lingual plate or a portion of the mylohoid ridge is not uncommon since the overlying mucosa in this area is excitingly thin. The common complaints will be pain upon swallowing and sharp bone detected in the area. Application of topical anesthetic to allow for a bone file or fine rongeurs to gently smooth or remove any sharp bone is all that is required. The patient is instructed to avoid further injury to the area with certain foods such as popcorn or potato chips and is reassured that the area will spontaneously heal. Oral hygiene and rinses with chlorhexidine will facilitate coverage of the area.
The incidence of osteomyelitis as a result of third molar extraction is not reported in the literature however it is a known complication of infection, fracture, and/or extraction in medically compromised patients. Osteomyelitis is an inflammation of the bone marrow and is most common in the mandible due to its dependence on blood supply from the inferior alveolar artery and poorly vascularized thick cortical bone. Because the maxilla has a rich vascular supply from multiple vessels it is less likely to develop osteomyelitis. The presence of bacteria within the marrow space leads to inflammation and edema with subsequent compression of blood vessels and a decrease in blood supply. This decrease in blood flow results in ischemia, bone necrosis, and proliferation of bacteria. Purulence and bacteria can spread within the marrow via Haversian and Volkmann’s canals and extend into cortical bone. Once the cortical bone and periosteum are involved, the blood supply is further compromised and perforation of soft tissues can occur resulting in fistula formation. Predisposing factors in the development of osteomyelitis involve suppression of host defenses in some form. Diabetes, alcoholism, autoimmune disease, radiation therapy, chemotherapy, steroid use, osteopetrosis, myeloproliferative diseases, and malnutrition can contribute to the development of osteomyelitis. 36
The classification of osteomyelitis offered by Hudson is commonly cited in the literature and essentially breaks down into acute and chronic forms based on disease presence greater than 1 month. 37
Patients with osteomyelitis will often present with complaints of a dull and deep pain, swelling and erythema of overlying tissues, paresthesia of the inferior alveolar nerve, trismus, adenopathy, fistula, fever, and malaise. 36, 38 In patients with chronic osteomyelitis, signs of acute infection such as fever are often not present; however, fistulas, both intra- and extraorally, are more common. Radiographs typically demonstrate a "moth-eaten" appearance of bony sequestrum. CT scanning can assist in the demarcation of lesion extent although it should be noted that 30–50% demineralization of bone is necessary before radiographic changes. 36 In chronic osteomyelitis there may be radiopacity due to an osteitis-type reaction and proliferation of bone. A laboratory workup will demonstrate leukocytosis in acute forms, elevated erythrocyte sedimentation rate (ESR) and C-reactive protein (CPR). Further laboratory evaluation of ESR and CRP levels during treatment can assist in assessment of healing. Culture specimens will often reveal bacteria traditionally responsible for odontogenic infections such as Bacteroides, Peptostreptococci, Fusobacterium, and Streptococci. Occasionally, less common odontogenic bacteria are present. These include Lactobacillus, Eubacterium, Klebsiella, Acinetobacter,and Pseudomonas aeruginosa. Osteomyelitis of the jaws is different from osteomyelitis of other bones in that Staphylococci are not the predominant bacteria. 36
The treatment of osteomyelitis is combination of surgical and medical management. Treatment of systemic diseases must be considered along with medical consultation when appropriate. Empiric antibiotics should be administered while awaiting final culture results. Penicillin/metronidazole or clindamycin are excellent first-line antibiotics. In chronic cases, sequestrectomy, decortication, and saucerization are necessary and extend to vital, bleeding bone. Removal of the cortex with placement of periosteum directly on the marrow space assists with blood flow. After aggressive debridement, that may lead to further weakening of the mandible, fixation may need to be employed to prevent fracture or for stabilization of a known fracture. External fixation, rigid internal fixation, or intermaxillary fixation may be used with the fixation type dependent on the surgeon’s preference and degree of success of surgical debridement. 36, 38 Other methods of treatment have been proposed such as local antibiotic administration with both resorbable and nonresorbable carriers and hyperbaric oxygen. Polymethylmethacrylate beads impregnated with gentamycin have been discussed in the orthopedic literature; however, results can be disappointing due to inadequate local release and subinhibitory antibiotic levels. 39, 40 Also, a second surgery is necessary to remove the beads. Hyperbaric oxygen (HBO) has not been demonstrated to have a significant effect on outcomebased on the limited available literature. 41, 42 Esterhai et al. studied the use of HBO on 28 patients with chronic refractory osteomyelitis and this controlled trial concluded that HBO had no effect on length of hospitalization, rate of wound repair, or recurrence of infection. 41