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Permanent sensory nerve impairment following third molar surgery: a prospective study
Permanent sensory nerve impairment following third molar surgery: a prospective study W. Jerjes, BDS, MSc,a B. Swinson, MBBS, BDS, FDS, AFRSC,b D. R. Moles, PhD, BDS, MSc, MSc(Hons), DDPH RCS(Eng), MIHPE ILTM,c M. El-Maaytah, BDS, MSc, PhD, FDS RCPS, LDS RCS,d B. Banu, BDS, DDS, MCPS, MSc, FDS RCS,e T. Upile, FRCS,f M. Kumar, BDS, MBBS, FDS, FRCS,g M. Al Khawalde, DDS, MSc,h M. Vourvachis, DMD, MSc,i H. Hadi, BDS,j S. Kumar, BDS,k and C. Hopper, MBBS, BDS, FDSRCS, FRCSl London and East Grinstead, United Kingdom EASTMAN DENTAL INSTITUTE FOR ORAL HEALTHCARE SCIENCES, UNIVERSITY COLLEGE LONDON HOSPITALS, AND QUEEN VICTORIA HOSPITAL
Objective. This prospective study reports the proportion of permanent sensory impairment of the inferior alveolar and lingual nerves and the factors influencing such prevalence after the removal of mandibular third molars under local anesthesia. Study design. There were 1,087 patients with 1,087 mandibular third molars removed under local anesthesia from 1998 to 2003. Standardized data collection included the patient’s name, age, gender, radiographic position of extracted tooth, grade of surgeon, proximity of the inferior alveolar nerve, and the prevalence of lingual and/or inferior alveolar nerve paresthesia. Results. Inferior alveolar nerve injury was 4.1% 1 week after surgery and decreased to 0.7% after 2 years of followup, and alteration in tongue sensation occurred in 6.5% of patients 1 week after surgery and decreased to 1.0% after 2 years of follow-up. Conclusion. The experience of the operator was found to be a significant factor in determining both permanent lingual nerve (P⫽.022) and permanent inferior alveolar nerve paresthesia (P⫽.026). (Oral Surg Oral Med Oral Pathol Oral Radiol Endod 2006;102:e1-e7)
Injuries to the lingual nerve (LN) and inferior alveolar nerve (IAN) are well recognized complications of third molar surgery. In previous studies, the prevalence of damage to the IAN during lower third molar surgery has been reported as varying from 0.4%1to 8.4%2 and to the LN as varying from 0%3 to 23%.4 The IAN travels within the mandibular bone and is therefore a supported nerve. Following injury, the nerve will remain in position and regenerate in a relatively
short time unless either displaced into the socket or displaced by fragments of bone from the roof of the canal. Thus, after injury to the IAN, good recovery is generally expected.5 The anatomic relationship between the IAN and the roots of the third molar teeth has also been shown to help predict the likelihood of nerve injury radiographically.6-8 After injury, the LN ends tend to retract and become trapped within scar tissue which may require surgical repair, although the success rate of this procedure has so far been modest.5
a
Honorary Lecturer, Department of Oral and Maxillofacial Surgery, Eastman Dental Institute for Oral Healthcare Sciences. b Specialist Registrar, Department of Oral and Maxillofacial Surgery, University College London Hospitals. c Senior Clinical Lecturer in Health Services Research, Eastman Dental Institute for Oral Healthcare Science, University College London. d Specialist Registrar, Department of Oral and Maxillofacial Surgery, University College London Hospitals. e Specialist in Surgical Dentistry, Department of Oral & Maxillofacial Surgery, Eastman Dental Institute for Oral Healthcare Sciences. f Specialist Registrar, Head and Neck Surgery Unit, University College London Hospitals. g Special Registrar, Department of Oral & Maxillofacial Surgery, University College London Hospitals. h Specialist, Department of Oral and Maxillofacial Surgery, Royal Medical Services, Jordan.
i
Senior House Officer, Department of Oral and Maxillofacial Surgery, Eastman Dental Institute for Oral Healthcare Sciences. j Research Fellow, Department of Oral and Maxillofacial Surgery, Eastman Dental Institute for Oral Healthcare Sciences. k Senior House Officer, Department of Oral and Maxillofacial Surgery, The Queen Victoria Hospital NHS Trust. l Senior Lecturer, Consultant Oral and Maxillofacial Surgeon, Head of Academic Surgical Unit, Eastman Dental Institute for Oral Healthcare Sciences. Received for publication Mar 23, 2005; returned for revision Dec 13, 2005; accepted for publication Jan 19, 2006. 1079-2104/$ - see front matter © 2006 Mosby, Inc. All rights reserved. doi:10.1016/j.tripleo.2006.01.016
e1
e2 Jerjes et al. In the majority of the review cases, paresthesia was found to be temporary and tends to subside within the first 6 months.7,9 Some studies have reported a lesser proportion of recovery for the LN compared with the IAN,10,11 though other studies fail to prove this case.12,13 The aim of this study was to determine the proportion of permanent sensory impairment, the related factors following surgical removal of mandibular third molars, and to present some follow-up and treatment modalities. MATERIAL AND METHODS Prospectively recorded data of 1,087 cases who underwent removal of mandibular third molars in the outpatient Department of Oral and Maxillofacial Surgery, Eastman Dental Hospital, from 1998 to 2003 were analyzed for the prevalence of permanent sensory nerve impairment. The demographic data collected from each patient included age, gender, degree of impaction (assessed radiographically as fully erupted, partially impacted, or fully impacted), treating surgeon (specialist or trainee), radiograph proximity to IAN (tooth ⱕ2 mm is considered to be close), duration of surgery and postoperative complications (permanent paresthesia), and requirement for a follow-up appointment 1 week after surgery. No patient in this study failed to attend the follow-up appointment. Data concerning alteration of sensation was collected as originating from the IAN and/or LN. This was mainly volunteered by the patient, or the clinician inquired concerning “paresthesia,” “pins and needles,” or “numbness.” Following the establishment of altered sensation, patients were reviewed at 3 weeks, 6 months, and up to 2 years. Any symptomatic patient beyond this time was considered to have permanent nerve impairment. All surgical procedures were performed in 3 similar clinics, equipped with similar surgical instruments, rotary and irrigation devices, and materials (sutures and hemostatic agents). Before surgery, each patient was informed of possible complications, including the possible risk of nerve damage during the procedure, and provided full informed consent. Local anesthesia was achieved (2% lidocaine with 1:80,000 epinephrine) by local tissue infiltration and IAN block injection, and no more than 5 cartridges were given to any single patient. An envelope mucoperiosteal flap was reflected and bone was removed with a round bur in a straight handpiece. In several cases (43 patients), the tooth had to be sectioned using a fissure bur. The sectioning in all cases was performed from the root bifurcation area to the
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occlusal surface; no other sectioning technique was implemented. These patients were very few, so they were combined with patients who had standard surgical approach with no tooth sectioning. Bone removal and sectioning of the tooth was performed under continuous irrigation with sterile saline solution at room temperature. The wound was carefully irrigated and any bony spicules removed. The flap was then repositioned and sutured with 4-0 Vicryl. No lingual flap was employed in any of the cases. No patient in this study underwent coronectomy. Immediately after surgery all patients were given written instructions about wound care and possible complications in the postoperative period. For all patients, metronidazole (400 mg 3 times daily for 5 days) was prescribed as an antimicrobial agent and ibuprofen (400 mg 3 times daily for 5 days) as an analgesic. All patients in this study were reviewed 7 days after surgery. The cases were distributed among the junior (trainees) and senior (specialists) staff regardless of their age, gender, or level of complexity. All staff in the trainee group were senior house officers, whereas the senior staff were clinicians on the Specialist Register for Surgical Dentistry. The level of supervision and training of the senior house officers was according to the national standards. Patients were required to undergo removal of at least 1 mandibular third molar tooth for inclusion in this study. No surgical exploration was implemented for any of the patients presenting with paresthesia for less than 2 years. Patients who continued to have this symptom over 2 years (permanent) were reviewed to assess their condition and were advised to undergo surgery for exploration of the area that could include undertaking microneurosurgical repair for the appropriate cases. Statistical methods The outcomes of paresthesia affecting the LN and IAN were summarized as frequencies for a series of time intervals after surgery. The chi-squared statistic was used to test for differences in the prevalence of lip and tongue paresthesia (separately) at 2 years after surgery within subgroups of the factors under study. Where only 2 subgroups were being compared, the Fisher’s exact test was used, because the expected numbers of patients with paresthesia within subgroups were small. RESULTS The 1,087 treated patients had a mean age of 23.3 (SD 4.2) years, and 585/1,087 (53.9%) were women. All underwent mandibular third molar removal (Table I). The majority of teeth (857/1,087; 78.8%) were partially impacted and around three quarters (843/1087;
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Jerjes et al. e3
Table I. Profile of treated cases Category Gender Age (yrs)
Degree of impaction of 3rd molar Proximity to inferior alveolar nerve Duration of surgery (min)
Seniority of surgeon
Description
n (%)
Male Female Mean Median SD Range Fully erupted Partially erupted Fully impacted ⬎2 mm ⬍2 mm Mean Median SD Range Trainee Specialist
501 (46.1) 586 (53.9) 23.3 22.0 4.2 17–36 104 (9.6) 857 (78.8) 126 (11.6) 244 (22.4) 843 (77.6) 18.1 18.0 7.3 4–39 518 (47.7) 569 (52.3)
77.6%) had roots that appeared radiographically to be within or less than 2 mm from the IAN canal roof. The mean time to complete surgery was 18 min (SD 7.3; range 4-39 min). After 1 week, 45 patients (4.1%) exhibited paresthesia in the distribution of the IAN and 71 (6.5%) experienced symptoms of LN paresthesia. The majority of these resolved within the first month after surgery. By 2 years, 8 patients (0.7%) still exhibited IAN paresthesia and 11 (1.0%) paresthesia of the LN (Table II). Our study of the predictors of permanent IAN paresthesia after 2 years (Table III) revealed that 0.8% of the male and 0.7% of the female patients sustained permanent nerve impairment. This was more frequent with teeth recorded as fully impacted (2.4%) than with partially impacted teeth (0.6%). The only statistically significant predictor of permanent IAN impairment was the experience of the operator (P⫽.026), with the better long-term results being achieved by the more senior surgeons. There was borderline statistical evidence to suggest that LN paresthesia 2 years after surgery (Table IV) had slightly higher prevalence in men (1.6%) than women (0.5%) (P⫽.069). The experience of the surgeon was the only statistically significant predictor of permanent LN paresthesia, with a lower proportion of permanent paresthesia being achieved by the senior surgeons (0.4% vs. 1.7%; P⫽.022). DISCUSSION This study is representative of the spectrum of third molar surgery undertaken in maxillofacial surgery departments under local anesthesia. The degree of sensory alteration and subsequent re-
Table II. Prevalence of lip and tongue paresthesia at specific time intervals after surgery Time after surgery 1 2 3 1 6 2
week weeks weeks month months years
Lip paresthesia, n (%)
Tongue, n (%)
45 (4.1) 19 (1.7) 19 (1.7) 18 (1.7) 17 (1.6) 8 (0.7)
71 (6.5) 30 (2.8) 23 (2.1) 17 (1.6) 15 (1.4) 11 (1.0)
covery following nerve damage depends on the severity of injury, and this forms the basis of the classification of peripheral nerve injuries proposed by Sunderland14 in 1951. This classification emphasizes the mechanism of injury and importance of each structural component involved. The classification comprises: ● ● ● ● ●
Compression injuries (neuropraxia). Severe compression or crush Injuries (axonotmesis). Stretch Injuries (rupture of endoneurium or perineurium). Complete section of the nerve trunk (neurotmesis). Other injuries (perineural inflammation).
Injuries to the inferior alveolar nerve Injuries to the IAN may be anticipated preoperatively by radiographic examination. Although standard radiographs give only a 2-dimensional view, it is possible to predict risk by assessing the location and morphologic characteristics of the canal in relation to the mandibular third molar.6-8 Alteration of sensation results from either direct or indirect trauma to the nerve during surgical instrumentation.6,15 The use of root elevators may result in blunt trauma to IAN. The nerve can either be compressed by the elevator itself or by the elevated roots. The IAN may be disrupted by rotating instruments16 or following IAN block injections.17 Other factors include full bony impaction, apices extending into or below the level of the neurovascular bundle, clinical observation of the neurovascular bundle during surgery, and excessive hemorrhage into the socket during surgery. As a result, neuropraxia or axonotmesis may occur at any time during surgical removal of third molars. Neurotmesis may also occur if the IAN passes directly through the root of the tooth and can be transected on its elevation. The prevalence of permanent numbness was compared with former publications and found to be consistent with some1,3,18,19 but inconsistent with others.2,13,16,20
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e4 Jerjes et al. Table III. Predictors of permanent lip paresthesia at 2 years after surgery Category Gender Degree of impaction of 3rd molar
Proximity to inferior alveolar nerve Patient age group
Seniority of surgeon
Description
Prevalence, n (%)
Male Female Fully erupted Partially erupted Fully impacted ⬎2 mm ⱕ2 mm 17–20 years 21–25 years 26–30 years 31⫹ years Trainee Specialist
4 (0.8) 4 (0.7) 0 (0) 5 (0.6) 3 (2.4) 2 (0.8) 6 (0.7) 2 (0.7) 2 (0.4) 3 (2.0) 1 (0.9) 7 (1.4) 1 (0.2)
Chi-squared (df)
P value
0.050 (1)
.549*
5.711 (2)
.058
0.30 (1)
.567*
4.179 (3)
.243
5.130 (1)
.026*
P values are from chi-squared tests except where specified by asterisk, which are computed from a Fisher’s exact test. All the chi-squared tests have low expected frequencies (⬍5) for some cells of the tables.
Table IV. Predictors of permanent tongue paresthesia at 2 years after surgery Category Gender Degree of impaction of 3rd molar
Proximity to inferior alveolar nerve Patient age group
Seniority of surgeon
Description
Prevalence, n (%)
Male Female Fully erupted Partially erupted Fully impacted ⬎2 mm ⱕ2 mm 17–20 years 21–25 years 26–30 years 31⫹ years Trainee Specialist
8 (1.6) 3 (0.5) 1 (1.0) 10 (1.2) 0 (0) 0 (0) 11 (1.3) 2 (0.7) 5 (0.9) 3 (2.0) 1 (0.9) 9 (1.7) 2 (0.4)
Chisquared, (df)
P value
3.173
.069*
1.496 (2)
.473
3.216 (1)
.060*
1.768 (3)
.622
5.200 (1)
.022*
P values are from chi-squared tests except where specified by asterisk, which are computed from a Fisher’s exact test. All the chi-squared tests have low expected frequencies (⬍5) for some cells of the tables.
Lingual nerve injury Despite every effort to avoid trauma to the LN during lower third molar surgery, LN anesthesia, paresthesia, or dysesthesia may result. It may be difficult to avoid encountering the nerve during surgery owing to its variable position. A combined anatomic and clinical study by Kiesselbach and Chamberlain21 showed marked variability in the position of the LN in the third molar region. They stated that the surgeon cannot rely on the lingual plate to act as a protective barrier to the nerve during third molar surgery, because the LN may lie above the bone in this area. There is also anatomic variation of the LN as it crosses the retromolar pad area, which increases the possibility of being traumatized during incision, retraction, buccal flap elevation, tooth or follicle removal, and suturing.
It has been documented that LN impairment may occur when raising the mucoperiosteal flap from the lingual aspect of the mandible22 or from from clumsy instrumentation, or it may be due to fracture of the lingual plate. Inserting a periosteal elevator under the lingual periosteum protects the LN from disruption or direct trauma by rotating instruments; however, there is an increased chance of stretching the nerve in the hands of less experienced surgeons.13,15,23,24 Lingual nerve impairment following IAN block injections,25 or following the use of lingual retractors12 is well documented. Hematoma, infection, or even swelling6,7 have also been implicated etiologies, and the risk of permanent damage after the use of rotating instruments has been reported.16 The technique in which bone removal is imple-
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mented was found to have a great effect on the prevalence of LN injury; Rood16 suggested that permanent damage to the inferior alveolar and lingual nerves was significantly related to the bone removal using a surgical drill and that the application of a Howarth periosteal elevator carries no benefit. Absi and Shepherd26 confirmed these findings. A study by Rood13 suggested that even if the Howarth periosteal elevator is carefully positioned, it cannot protect the LN along the full length of the surgical field. He suggested continuous movement of the instrument along the surgical field to provide optimum protection or using other adequate retractors that provide better protection than the Howarth periosteal elevator. Greenwood et al.27 suggested using broad retractors to protect the LN and found that they produce significantly less altered nerve sensation at 1 month than a Howarth periosteal elevator. Other studies suggested that there is no need to apply periosteal elevators for LN protection during third molar surgery.28,29 The prevalence of permanent numbness was compared with former publications and, as would be expected, found to be consistent with some1,30,31,32 and inconsistent with others.13,16,20,27 Our data show that the proportion of recovery of the LN is faster than that of the IAN and suggest that most of the LN injury was due to neuropraxia. This is in line with other authors’ experience.12,13 Degree of impaction and proximity of the tooth to the inferior dental canal Teeth were considered partially erupted if any part of the crown was above the superior border of bone. Permanent nerve dysfunction was slightly higher in teeth classified as fully impacted than in partially erupted teeth, whereas teeth classified as fully erupted showed no reported cases of nerve injury. This suggests that a relationship between prevalence and radiographic position of teeth is possible. These results are consistent with some studies.33,34 The relation of the inferior dental canal to the third molar tooth was also one of the factors that increase the proportion of nerve damage. The proximity of the canal to the tooth was recorded at the first assessment, and we found that in 96% of the temporary paresthesia cases the surgeons recorded the tooth as being “close” to inferior dental canal. However, statistically, this study failed to demonstrate a relationship between IAN paresthesia and the proximity of extracted tooth to the IAN. Patient’s age and gender The present study failed to demonstrate a relationship between the age of the patient and sensory distur-
Jerjes et al. e5
bances following third molar surgery. This was not the case in some studies which showed a higher morbidity in patients over 35 years of age.35 The lack of any statistically significant association suggests that prophylactic surgery may be unjustified and could theoretically cause more complications following intervention. These results are consistent with the guidelines issued by the National Institute for Clinical Excellence, which does not support prophylactic wisdom tooth removal. This is still a controversial issue, with some authorities still recommending prophylactic third molar surgery.31,35 We found no significant difference between male and females patients in relation to lip and tongue paresthesias. Some studies demonstrated a female predominance,17 but other studies failed to confirm any association.23 Surgeon’s experience The prevalence of damage of the lingual and inferior alveolar nerves in our study is in agreement with most of the documented studies with respect to the surgeon’s experience.1,20,23,33,36 Trainees showed higher prevalence of LN paresthesia in their patients than did their senior colleagues during the follow up period. Permanent nerve impairment was considered after 2 years of follow-up and was 4 times more likely to occur in this group. This could be related to experience, improper use of force, and instrument handling. The same group of surgeons (trainees) treated a slightly higher number of patients with third molars that were close to the IAN. This may be one of the reasons for the higher prevalence of permanent IAN damage (7 times more likely to occur). The prevalence of the permanent damage of the IAN and LN is found to be less than the prevalence reported by Bataineh33 for both the senior and junior staff and quite consistent with the results of Sisk et al.1 for the senior staff but less for the junior staff. In our study the number of patients with paresthesia is considered to be relatively small. As such, multiple regression analysis was not implemented to control for multiple factors simultaneously; this might lead to confounding factors being present which might affect the incidence of paresthesia measured in this study. Follow-up and treatment Spontaneous recovery has been reported to occur in 96% of the IAN injuries and 87% of the LN injuries within the first 4-8 weeks after surgery.10 Pogrel37 suggested a follow-up regimen as follows: every 2 weeks for 2 months, every 6 weeks for 6 months, every 6 months for up to 2 years, and then annually for an
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e6 Jerjes et al. Table V. Indications for and contraindications to microneurosurgical repair Indications Complete anesthesia beyond 3 months. Profound hypoesthesia with no improvement beyond 4 months. Dysesthesia beyond 4 months. Clinically observed nerve severance. Contraindications Improving return of sensation. Sensory deficit acceptable to the patient. Central neuropathic pain. Dysesthesia not resolved by a local anaesthesia nerve block. Medical neuropathy. Medically compromised patient. Excessive delay following injury.
indefinite period. In the absence of active treatment, this frequency seems a little excessive. Robinson38 reported that recovery after 9 months from the time of surgery is rare, and it is unlikely that any recovery will occur after 18 months to 2 years of follow-up. However, some authors have reported recovery in a small group of patients after 2 years of treatment.39 Work done by Meyer40 suggests that a recovery of sensation after 4 weeks indicates neuropraxia and carries an excellent prognosis, whereas recovery between 1 to 3 months is usually associated with axonotmesis. Any failure to recover after this time usually hints at neurotmesis being the etiology. This carries a poorer prognosis and may require microneurosurgical intervention to reapproximate the severed ends. Table V shows indications and contraindications for microneurosurgical nerve repair as proposed by Meyer.40 CONCLUSION The findings in this study are similar to other published series, with permanent sensory loss of the lingual and inferior alveolar nerves noted in 1% and 0.7%, respectively. It is a little disappointing that LN damage was noted, because no lingual retraction was used in this series. However, the higher rate of sensory complications in the trainee group suggests that at least some of the complications may be related to surgical experience. This raises a number of important issues related to training. Ideally, third molar removal should only be carried out by experienced practitioners and not by occasional surgeons; however, surgeons are not created by divine right and need training to gain the requisite level of experience. This will unfortunately result in a higher level of complications even when trainees are closely supervised. Patients have the right to know who will be performing their surgery and may
be unhappy with the increased risk of being treated by a trainee. However, overall the risks of sensory change following third molar removal are still small, with an increased risk of 1.3% and 1.2% for the lingual and inferior alveolar nerves respectively, when a trainee rather than a specialist performs the operation. REFERENCES 1. Sisk AL, Hammer WB, Shelton DW, Joy ED Jr. Complications following removal of impacted third molars: the role of the experience of the surgeon. J Oral Maxillofac Surg 1986;44:855-9. 2. Lopes V, Mumenya R, Feinmann C, Harris M. Third molar surgery: an audit of the indications for surgery, post-operative complaints and patient satisfaction. Br J Oral Maxillofac Surg 1995;33:33-5. 3. Chiapasco M, De Cicco L, Marrone G. Side effects and complications associated with third molar surgery. Oral Surg Oral Med Oral Pathol Oral Radiol Endod 1993;76:412-20. 4. Middlehurst RJ, Barker GR, Rood JP. Postoperative morbidity with mandibular third molar surgery: a comparison of two techniques. J Oral Maxillofac Surg 1988;46:474-6. 5. Loescher AR, Smith KG, Robinson PP. Nerve damage and third molar removal. Dent Update 2003;30:375-80, 382. 6. Kipp DP, Goldstein BH, Weiss WW Jr. Dysesthesia after mandibular third molar surgery: a retrospective study and analysis of 1,377 surgical procedures. J Am Dent Assoc 1980;100:185-92. 7. Wofford DT, Miller RI. Prospective study of dysesthesia following odontectomy of impacted mandibular third molars. J Oral Maxillofac Surg 1987;45:15-9. 8. Rood JP, Shehab BA. The radiological prediction of inferior alveolar nerve injury during third molar surgery. Br J Oral Maxillofac Surg 1990;28:20-5. 9. Osborn TP, Frederickson G Jr, Small IA, Torgerson TS. A prospective study of complications related to mandibular third molar surgery. J Oral Maxillofac Surg 1985;43:767-9. 10. Alling CC 3rd. Dysesthesia of the lingual and inferior alveolar nerves following third molar surgery. J Oral Maxillofac Surg 1986;44:454-7. 11. Ewers R, Hoffmeister B. Functional disorders of the mandibular nerve caused by the molars. Complications after surgical molar extraction. Z Stomatol 1986;83:521-35. 12. Carmichael FA, McGowan DA. Incidence of nerve damage following third molar removal: a West of Scotland Oral Surgery Research Group study. Br J Oral Maxillofac Surg 1992;30:78-82. 13. Rood JP. Lingual split technique. Damage to inferior alveolar and lingual nerves during removal of impacted mandibular third molars. Br Dent J 1983;154:402-3. 14. Sunderland S. A classification of peripheral nerve injuries producing loss of function. Brain 1951;74:491-516. 15. Blackburn CW, Bramley PA. Lingual nerve damage associated with the removal of lower third molars. Br Dent J 1989;167:103-7. 16. Rood JP. Permanent damage to inferior alveolar and lingual nerves during the removal of impacted mandibular third molars. Comparison of two methods of bone removal. Br Dent J 1992;172:108-10. 17. Gerlach KL, Hoffmeister B, Walz C. Dysesthesia and anesthesia of the mandibular nerve following dental treatment. Dtsch Zahnarztl Z 1989;44:970-2. 18. Goldberg MH, Nemarich AN, Marco WP 2nd. Complications after mandibular third molar surgery: a statistical analysis of 500 consecutive procedures in private practice. J Am Dent Assoc 1985;111:277-9.
OOOOE Volume 102, Number 4 19. Miura K, Kino K, Shibuya T, Hirata Y, Shibuya T, Sasaki E, et al. Nerve paralysis after third molar extraction. Kokubyo Gakkai Zasshi 1998;65:1-5. 20. Brann CR, Brickley MR, Shepherd JP. Factors influencing nerve damage during lower third molar surgery. Br Dent J 1999;186:514-6. 21. Kiesselbach JE, Chamberlain JG. Clinical and anatomic observations on the relationship of the lingual nerve to the mandibular third molar region. J Oral Maxillofac Surg 1984;42:565-7. 22. Pedersen GW. Oral surgery. Philadelphia: Saunders; 1988. p. 60 – 81. 23. Gulicher D, Gerlach KL. Sensory impairment of the lingual and inferior alveolar nerves following removal of impacted mandibular third molars. Int J Oral Maxillofac Surg 2001;30:306-12. 24. Mason DA. Lingual nerve damage following lower third molar surgery. Int J Oral Maxillofac Surg 1988;17:290-4. 25. Krafft TC, Hickel R. Clinical investigation into the incidence of direct damage to the lingual nerve caused by local anesthesia. J Craniomaxillofac Surg 1994;22:294-6. 26. Absi E.G., Shepherd JP. A comparison of morbidity following the removal of lower third molars by the lingual split and surgical bur methods. Int J Oral Maxillofac Surg 1993;22:149-53. 27. Greenwood M, Langton SG, Rood JP. A comparison of broad and narrow retractors for lingual nerve protection during lower third molar surgery. Br J Oral Maxillofac Surg 1994;32:114-7. 28. Gargallo-Albiol J, Buenechea-Imaz R, Gay-Escoda C. Lingual nerve protection during surgical removal of lower third molars. a prospective randomised study. Int J Oral Maxillofac Surg 2000;29:268-71. 29. Chossegros C, Guyot L, Cheynet F, Belloni D, Blanc JL. Is lingual nerve protection necessary for lower third molar germectomy? A prospective study of 300 procedures. Int J Oral Maxillofac Surg 2002;31:620-4. 30. Rud J. The split-bone technic for removal of impacted mandibular third molars. J Oral Surg 1970;28:416-21. 31. Bruce RA, Frederickson GC, Small GS. Age of patients and morbidity associated with mandibular third molar surgery. J Am Dent Assoc 1980;101:240-5.
Jerjes et al. e7 32. Black CG. Sensory impairment following lower third molar surgery: a prospective study in New Zealand. N Z Dent J 1997;93:68-71. 33. Bataineh AB. Sensory nerve impairment following mandibular third molar surgery. J Oral Maxillofac Surg 2001;59:1012-7; discussion 1017. 34. Valmaseda-Castellon E, Berini-Aytes L, Gay-Escoda C. Inferior alveolar nerve damage after lower third molar surgical extraction: a prospective study of 1117 surgical extractions. Oral Surg Oral Med Oral Pathol Oral Radiol Endod 2001;92:377-83. 35. Gulicher D, Gerlach KL. Incidence, risk factors and follow-up of sensation disorders after surgical wisdom tooth removal. Study of 1,106 cases. Mund Kiefer Gesichtschir 2000;4:99-104. 36. Capuzzi P, Montebugnoli L, Vaccaro MA. Extraction of impacted third molars. A longitudinal prospective study on factors that affect postoperative recovery. Oral Surg Oral Med Oral Pathol Oral Radiol Endod 1994;77:341-3. 37. Pogrel MA. Complications of third molar surgery. In: Kaban LB, Pogrel MA, Perrott DH, editors. Complications in oral and maxillofacial surgery. Philadelphia: Saunders; 1997. p. 59. 38. Robinson PP. Observations on the recovery of sensation following inferior alveolar nerve injuries. Br J Oral Maxillofac Surg 1988;26:177-89. 39. Girard KR. Considerations in the management of damage to the mandibular nerve. J Am Dent Assoc 1979;98:65-71. 40. Meyer RA. Evaluation and management of neurologic complications. In: Kaban LB, Pogrel MA, Perrott DH, editors. Complications in oral and maxillofacial surgery. Philadelphia: Saunders; 1997. p. 69.
Reprint requests: Waseem Jerjes Department of Oral & Maxillofacial Surgery Eastman Dental Institute for Oral Healthcare Sciences 256 Gray’s Inn Road London WC1X 8LD United Kingdom [email protected]
Objective. This prospective study reports the proportion of permanent sensory impairment of the inferior alveolar and lingual nerves and the factors influencing such prevalence after the removal of mandibular third molars under local anesthesia. Study design. There were 1,087 patients with 1,087 mandibular third molars removed under local anesthesia from 1998 to 2003. Standardized data collection included the patient’s name, age, gender, radiographic position of extracted tooth, grade of surgeon, proximity of the inferior alveolar nerve, and the prevalence of lingual and/or inferior alveolar nerve paresthesia. Results. Inferior alveolar nerve injury was 4.1% 1 week after surgery and decreased to 0.7% after 2 years of followup, and alteration in tongue sensation occurred in 6.5% of patients 1 week after surgery and decreased to 1.0% after 2 years of follow-up. Conclusion. The experience of the operator was found to be a significant factor in determining both permanent lingual nerve (P⫽.022) and permanent inferior alveolar nerve paresthesia (P⫽.026). (Oral Surg Oral Med Oral Pathol Oral Radiol Endod 2006;102:e1-e7)
Injuries to the lingual nerve (LN) and inferior alveolar nerve (IAN) are well recognized complications of third molar surgery. In previous studies, the prevalence of damage to the IAN during lower third molar surgery has been reported as varying from 0.4%1to 8.4%2 and to the LN as varying from 0%3 to 23%.4 The IAN travels within the mandibular bone and is therefore a supported nerve. Following injury, the nerve will remain in position and regenerate in a relatively
short time unless either displaced into the socket or displaced by fragments of bone from the roof of the canal. Thus, after injury to the IAN, good recovery is generally expected.5 The anatomic relationship between the IAN and the roots of the third molar teeth has also been shown to help predict the likelihood of nerve injury radiographically.6-8 After injury, the LN ends tend to retract and become trapped within scar tissue which may require surgical repair, although the success rate of this procedure has so far been modest.5
a
Honorary Lecturer, Department of Oral and Maxillofacial Surgery, Eastman Dental Institute for Oral Healthcare Sciences. b Specialist Registrar, Department of Oral and Maxillofacial Surgery, University College London Hospitals. c Senior Clinical Lecturer in Health Services Research, Eastman Dental Institute for Oral Healthcare Science, University College London. d Specialist Registrar, Department of Oral and Maxillofacial Surgery, University College London Hospitals. e Specialist in Surgical Dentistry, Department of Oral & Maxillofacial Surgery, Eastman Dental Institute for Oral Healthcare Sciences. f Specialist Registrar, Head and Neck Surgery Unit, University College London Hospitals. g Special Registrar, Department of Oral & Maxillofacial Surgery, University College London Hospitals. h Specialist, Department of Oral and Maxillofacial Surgery, Royal Medical Services, Jordan.
i
Senior House Officer, Department of Oral and Maxillofacial Surgery, Eastman Dental Institute for Oral Healthcare Sciences. j Research Fellow, Department of Oral and Maxillofacial Surgery, Eastman Dental Institute for Oral Healthcare Sciences. k Senior House Officer, Department of Oral and Maxillofacial Surgery, The Queen Victoria Hospital NHS Trust. l Senior Lecturer, Consultant Oral and Maxillofacial Surgeon, Head of Academic Surgical Unit, Eastman Dental Institute for Oral Healthcare Sciences. Received for publication Mar 23, 2005; returned for revision Dec 13, 2005; accepted for publication Jan 19, 2006. 1079-2104/$ - see front matter © 2006 Mosby, Inc. All rights reserved. doi:10.1016/j.tripleo.2006.01.016
e1
e2 Jerjes et al. In the majority of the review cases, paresthesia was found to be temporary and tends to subside within the first 6 months.7,9 Some studies have reported a lesser proportion of recovery for the LN compared with the IAN,10,11 though other studies fail to prove this case.12,13 The aim of this study was to determine the proportion of permanent sensory impairment, the related factors following surgical removal of mandibular third molars, and to present some follow-up and treatment modalities. MATERIAL AND METHODS Prospectively recorded data of 1,087 cases who underwent removal of mandibular third molars in the outpatient Department of Oral and Maxillofacial Surgery, Eastman Dental Hospital, from 1998 to 2003 were analyzed for the prevalence of permanent sensory nerve impairment. The demographic data collected from each patient included age, gender, degree of impaction (assessed radiographically as fully erupted, partially impacted, or fully impacted), treating surgeon (specialist or trainee), radiograph proximity to IAN (tooth ⱕ2 mm is considered to be close), duration of surgery and postoperative complications (permanent paresthesia), and requirement for a follow-up appointment 1 week after surgery. No patient in this study failed to attend the follow-up appointment. Data concerning alteration of sensation was collected as originating from the IAN and/or LN. This was mainly volunteered by the patient, or the clinician inquired concerning “paresthesia,” “pins and needles,” or “numbness.” Following the establishment of altered sensation, patients were reviewed at 3 weeks, 6 months, and up to 2 years. Any symptomatic patient beyond this time was considered to have permanent nerve impairment. All surgical procedures were performed in 3 similar clinics, equipped with similar surgical instruments, rotary and irrigation devices, and materials (sutures and hemostatic agents). Before surgery, each patient was informed of possible complications, including the possible risk of nerve damage during the procedure, and provided full informed consent. Local anesthesia was achieved (2% lidocaine with 1:80,000 epinephrine) by local tissue infiltration and IAN block injection, and no more than 5 cartridges were given to any single patient. An envelope mucoperiosteal flap was reflected and bone was removed with a round bur in a straight handpiece. In several cases (43 patients), the tooth had to be sectioned using a fissure bur. The sectioning in all cases was performed from the root bifurcation area to the
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occlusal surface; no other sectioning technique was implemented. These patients were very few, so they were combined with patients who had standard surgical approach with no tooth sectioning. Bone removal and sectioning of the tooth was performed under continuous irrigation with sterile saline solution at room temperature. The wound was carefully irrigated and any bony spicules removed. The flap was then repositioned and sutured with 4-0 Vicryl. No lingual flap was employed in any of the cases. No patient in this study underwent coronectomy. Immediately after surgery all patients were given written instructions about wound care and possible complications in the postoperative period. For all patients, metronidazole (400 mg 3 times daily for 5 days) was prescribed as an antimicrobial agent and ibuprofen (400 mg 3 times daily for 5 days) as an analgesic. All patients in this study were reviewed 7 days after surgery. The cases were distributed among the junior (trainees) and senior (specialists) staff regardless of their age, gender, or level of complexity. All staff in the trainee group were senior house officers, whereas the senior staff were clinicians on the Specialist Register for Surgical Dentistry. The level of supervision and training of the senior house officers was according to the national standards. Patients were required to undergo removal of at least 1 mandibular third molar tooth for inclusion in this study. No surgical exploration was implemented for any of the patients presenting with paresthesia for less than 2 years. Patients who continued to have this symptom over 2 years (permanent) were reviewed to assess their condition and were advised to undergo surgery for exploration of the area that could include undertaking microneurosurgical repair for the appropriate cases. Statistical methods The outcomes of paresthesia affecting the LN and IAN were summarized as frequencies for a series of time intervals after surgery. The chi-squared statistic was used to test for differences in the prevalence of lip and tongue paresthesia (separately) at 2 years after surgery within subgroups of the factors under study. Where only 2 subgroups were being compared, the Fisher’s exact test was used, because the expected numbers of patients with paresthesia within subgroups were small. RESULTS The 1,087 treated patients had a mean age of 23.3 (SD 4.2) years, and 585/1,087 (53.9%) were women. All underwent mandibular third molar removal (Table I). The majority of teeth (857/1,087; 78.8%) were partially impacted and around three quarters (843/1087;
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Jerjes et al. e3
Table I. Profile of treated cases Category Gender Age (yrs)
Degree of impaction of 3rd molar Proximity to inferior alveolar nerve Duration of surgery (min)
Seniority of surgeon
Description
n (%)
Male Female Mean Median SD Range Fully erupted Partially erupted Fully impacted ⬎2 mm ⬍2 mm Mean Median SD Range Trainee Specialist
501 (46.1) 586 (53.9) 23.3 22.0 4.2 17–36 104 (9.6) 857 (78.8) 126 (11.6) 244 (22.4) 843 (77.6) 18.1 18.0 7.3 4–39 518 (47.7) 569 (52.3)
77.6%) had roots that appeared radiographically to be within or less than 2 mm from the IAN canal roof. The mean time to complete surgery was 18 min (SD 7.3; range 4-39 min). After 1 week, 45 patients (4.1%) exhibited paresthesia in the distribution of the IAN and 71 (6.5%) experienced symptoms of LN paresthesia. The majority of these resolved within the first month after surgery. By 2 years, 8 patients (0.7%) still exhibited IAN paresthesia and 11 (1.0%) paresthesia of the LN (Table II). Our study of the predictors of permanent IAN paresthesia after 2 years (Table III) revealed that 0.8% of the male and 0.7% of the female patients sustained permanent nerve impairment. This was more frequent with teeth recorded as fully impacted (2.4%) than with partially impacted teeth (0.6%). The only statistically significant predictor of permanent IAN impairment was the experience of the operator (P⫽.026), with the better long-term results being achieved by the more senior surgeons. There was borderline statistical evidence to suggest that LN paresthesia 2 years after surgery (Table IV) had slightly higher prevalence in men (1.6%) than women (0.5%) (P⫽.069). The experience of the surgeon was the only statistically significant predictor of permanent LN paresthesia, with a lower proportion of permanent paresthesia being achieved by the senior surgeons (0.4% vs. 1.7%; P⫽.022). DISCUSSION This study is representative of the spectrum of third molar surgery undertaken in maxillofacial surgery departments under local anesthesia. The degree of sensory alteration and subsequent re-
Table II. Prevalence of lip and tongue paresthesia at specific time intervals after surgery Time after surgery 1 2 3 1 6 2
week weeks weeks month months years
Lip paresthesia, n (%)
Tongue, n (%)
45 (4.1) 19 (1.7) 19 (1.7) 18 (1.7) 17 (1.6) 8 (0.7)
71 (6.5) 30 (2.8) 23 (2.1) 17 (1.6) 15 (1.4) 11 (1.0)
covery following nerve damage depends on the severity of injury, and this forms the basis of the classification of peripheral nerve injuries proposed by Sunderland14 in 1951. This classification emphasizes the mechanism of injury and importance of each structural component involved. The classification comprises: ● ● ● ● ●
Compression injuries (neuropraxia). Severe compression or crush Injuries (axonotmesis). Stretch Injuries (rupture of endoneurium or perineurium). Complete section of the nerve trunk (neurotmesis). Other injuries (perineural inflammation).
Injuries to the inferior alveolar nerve Injuries to the IAN may be anticipated preoperatively by radiographic examination. Although standard radiographs give only a 2-dimensional view, it is possible to predict risk by assessing the location and morphologic characteristics of the canal in relation to the mandibular third molar.6-8 Alteration of sensation results from either direct or indirect trauma to the nerve during surgical instrumentation.6,15 The use of root elevators may result in blunt trauma to IAN. The nerve can either be compressed by the elevator itself or by the elevated roots. The IAN may be disrupted by rotating instruments16 or following IAN block injections.17 Other factors include full bony impaction, apices extending into or below the level of the neurovascular bundle, clinical observation of the neurovascular bundle during surgery, and excessive hemorrhage into the socket during surgery. As a result, neuropraxia or axonotmesis may occur at any time during surgical removal of third molars. Neurotmesis may also occur if the IAN passes directly through the root of the tooth and can be transected on its elevation. The prevalence of permanent numbness was compared with former publications and found to be consistent with some1,3,18,19 but inconsistent with others.2,13,16,20
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e4 Jerjes et al. Table III. Predictors of permanent lip paresthesia at 2 years after surgery Category Gender Degree of impaction of 3rd molar
Proximity to inferior alveolar nerve Patient age group
Seniority of surgeon
Description
Prevalence, n (%)
Male Female Fully erupted Partially erupted Fully impacted ⬎2 mm ⱕ2 mm 17–20 years 21–25 years 26–30 years 31⫹ years Trainee Specialist
4 (0.8) 4 (0.7) 0 (0) 5 (0.6) 3 (2.4) 2 (0.8) 6 (0.7) 2 (0.7) 2 (0.4) 3 (2.0) 1 (0.9) 7 (1.4) 1 (0.2)
Chi-squared (df)
P value
0.050 (1)
.549*
5.711 (2)
.058
0.30 (1)
.567*
4.179 (3)
.243
5.130 (1)
.026*
P values are from chi-squared tests except where specified by asterisk, which are computed from a Fisher’s exact test. All the chi-squared tests have low expected frequencies (⬍5) for some cells of the tables.
Table IV. Predictors of permanent tongue paresthesia at 2 years after surgery Category Gender Degree of impaction of 3rd molar
Proximity to inferior alveolar nerve Patient age group
Seniority of surgeon
Description
Prevalence, n (%)
Male Female Fully erupted Partially erupted Fully impacted ⬎2 mm ⱕ2 mm 17–20 years 21–25 years 26–30 years 31⫹ years Trainee Specialist
8 (1.6) 3 (0.5) 1 (1.0) 10 (1.2) 0 (0) 0 (0) 11 (1.3) 2 (0.7) 5 (0.9) 3 (2.0) 1 (0.9) 9 (1.7) 2 (0.4)
Chisquared, (df)
P value
3.173
.069*
1.496 (2)
.473
3.216 (1)
.060*
1.768 (3)
.622
5.200 (1)
.022*
P values are from chi-squared tests except where specified by asterisk, which are computed from a Fisher’s exact test. All the chi-squared tests have low expected frequencies (⬍5) for some cells of the tables.
Lingual nerve injury Despite every effort to avoid trauma to the LN during lower third molar surgery, LN anesthesia, paresthesia, or dysesthesia may result. It may be difficult to avoid encountering the nerve during surgery owing to its variable position. A combined anatomic and clinical study by Kiesselbach and Chamberlain21 showed marked variability in the position of the LN in the third molar region. They stated that the surgeon cannot rely on the lingual plate to act as a protective barrier to the nerve during third molar surgery, because the LN may lie above the bone in this area. There is also anatomic variation of the LN as it crosses the retromolar pad area, which increases the possibility of being traumatized during incision, retraction, buccal flap elevation, tooth or follicle removal, and suturing.
It has been documented that LN impairment may occur when raising the mucoperiosteal flap from the lingual aspect of the mandible22 or from from clumsy instrumentation, or it may be due to fracture of the lingual plate. Inserting a periosteal elevator under the lingual periosteum protects the LN from disruption or direct trauma by rotating instruments; however, there is an increased chance of stretching the nerve in the hands of less experienced surgeons.13,15,23,24 Lingual nerve impairment following IAN block injections,25 or following the use of lingual retractors12 is well documented. Hematoma, infection, or even swelling6,7 have also been implicated etiologies, and the risk of permanent damage after the use of rotating instruments has been reported.16 The technique in which bone removal is imple-
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mented was found to have a great effect on the prevalence of LN injury; Rood16 suggested that permanent damage to the inferior alveolar and lingual nerves was significantly related to the bone removal using a surgical drill and that the application of a Howarth periosteal elevator carries no benefit. Absi and Shepherd26 confirmed these findings. A study by Rood13 suggested that even if the Howarth periosteal elevator is carefully positioned, it cannot protect the LN along the full length of the surgical field. He suggested continuous movement of the instrument along the surgical field to provide optimum protection or using other adequate retractors that provide better protection than the Howarth periosteal elevator. Greenwood et al.27 suggested using broad retractors to protect the LN and found that they produce significantly less altered nerve sensation at 1 month than a Howarth periosteal elevator. Other studies suggested that there is no need to apply periosteal elevators for LN protection during third molar surgery.28,29 The prevalence of permanent numbness was compared with former publications and, as would be expected, found to be consistent with some1,30,31,32 and inconsistent with others.13,16,20,27 Our data show that the proportion of recovery of the LN is faster than that of the IAN and suggest that most of the LN injury was due to neuropraxia. This is in line with other authors’ experience.12,13 Degree of impaction and proximity of the tooth to the inferior dental canal Teeth were considered partially erupted if any part of the crown was above the superior border of bone. Permanent nerve dysfunction was slightly higher in teeth classified as fully impacted than in partially erupted teeth, whereas teeth classified as fully erupted showed no reported cases of nerve injury. This suggests that a relationship between prevalence and radiographic position of teeth is possible. These results are consistent with some studies.33,34 The relation of the inferior dental canal to the third molar tooth was also one of the factors that increase the proportion of nerve damage. The proximity of the canal to the tooth was recorded at the first assessment, and we found that in 96% of the temporary paresthesia cases the surgeons recorded the tooth as being “close” to inferior dental canal. However, statistically, this study failed to demonstrate a relationship between IAN paresthesia and the proximity of extracted tooth to the IAN. Patient’s age and gender The present study failed to demonstrate a relationship between the age of the patient and sensory distur-
Jerjes et al. e5
bances following third molar surgery. This was not the case in some studies which showed a higher morbidity in patients over 35 years of age.35 The lack of any statistically significant association suggests that prophylactic surgery may be unjustified and could theoretically cause more complications following intervention. These results are consistent with the guidelines issued by the National Institute for Clinical Excellence, which does not support prophylactic wisdom tooth removal. This is still a controversial issue, with some authorities still recommending prophylactic third molar surgery.31,35 We found no significant difference between male and females patients in relation to lip and tongue paresthesias. Some studies demonstrated a female predominance,17 but other studies failed to confirm any association.23 Surgeon’s experience The prevalence of damage of the lingual and inferior alveolar nerves in our study is in agreement with most of the documented studies with respect to the surgeon’s experience.1,20,23,33,36 Trainees showed higher prevalence of LN paresthesia in their patients than did their senior colleagues during the follow up period. Permanent nerve impairment was considered after 2 years of follow-up and was 4 times more likely to occur in this group. This could be related to experience, improper use of force, and instrument handling. The same group of surgeons (trainees) treated a slightly higher number of patients with third molars that were close to the IAN. This may be one of the reasons for the higher prevalence of permanent IAN damage (7 times more likely to occur). The prevalence of the permanent damage of the IAN and LN is found to be less than the prevalence reported by Bataineh33 for both the senior and junior staff and quite consistent with the results of Sisk et al.1 for the senior staff but less for the junior staff. In our study the number of patients with paresthesia is considered to be relatively small. As such, multiple regression analysis was not implemented to control for multiple factors simultaneously; this might lead to confounding factors being present which might affect the incidence of paresthesia measured in this study. Follow-up and treatment Spontaneous recovery has been reported to occur in 96% of the IAN injuries and 87% of the LN injuries within the first 4-8 weeks after surgery.10 Pogrel37 suggested a follow-up regimen as follows: every 2 weeks for 2 months, every 6 weeks for 6 months, every 6 months for up to 2 years, and then annually for an
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e6 Jerjes et al. Table V. Indications for and contraindications to microneurosurgical repair Indications Complete anesthesia beyond 3 months. Profound hypoesthesia with no improvement beyond 4 months. Dysesthesia beyond 4 months. Clinically observed nerve severance. Contraindications Improving return of sensation. Sensory deficit acceptable to the patient. Central neuropathic pain. Dysesthesia not resolved by a local anaesthesia nerve block. Medical neuropathy. Medically compromised patient. Excessive delay following injury.
indefinite period. In the absence of active treatment, this frequency seems a little excessive. Robinson38 reported that recovery after 9 months from the time of surgery is rare, and it is unlikely that any recovery will occur after 18 months to 2 years of follow-up. However, some authors have reported recovery in a small group of patients after 2 years of treatment.39 Work done by Meyer40 suggests that a recovery of sensation after 4 weeks indicates neuropraxia and carries an excellent prognosis, whereas recovery between 1 to 3 months is usually associated with axonotmesis. Any failure to recover after this time usually hints at neurotmesis being the etiology. This carries a poorer prognosis and may require microneurosurgical intervention to reapproximate the severed ends. Table V shows indications and contraindications for microneurosurgical nerve repair as proposed by Meyer.40 CONCLUSION The findings in this study are similar to other published series, with permanent sensory loss of the lingual and inferior alveolar nerves noted in 1% and 0.7%, respectively. It is a little disappointing that LN damage was noted, because no lingual retraction was used in this series. However, the higher rate of sensory complications in the trainee group suggests that at least some of the complications may be related to surgical experience. This raises a number of important issues related to training. Ideally, third molar removal should only be carried out by experienced practitioners and not by occasional surgeons; however, surgeons are not created by divine right and need training to gain the requisite level of experience. This will unfortunately result in a higher level of complications even when trainees are closely supervised. Patients have the right to know who will be performing their surgery and may
be unhappy with the increased risk of being treated by a trainee. However, overall the risks of sensory change following third molar removal are still small, with an increased risk of 1.3% and 1.2% for the lingual and inferior alveolar nerves respectively, when a trainee rather than a specialist performs the operation. REFERENCES 1. Sisk AL, Hammer WB, Shelton DW, Joy ED Jr. Complications following removal of impacted third molars: the role of the experience of the surgeon. J Oral Maxillofac Surg 1986;44:855-9. 2. Lopes V, Mumenya R, Feinmann C, Harris M. Third molar surgery: an audit of the indications for surgery, post-operative complaints and patient satisfaction. Br J Oral Maxillofac Surg 1995;33:33-5. 3. Chiapasco M, De Cicco L, Marrone G. Side effects and complications associated with third molar surgery. Oral Surg Oral Med Oral Pathol Oral Radiol Endod 1993;76:412-20. 4. Middlehurst RJ, Barker GR, Rood JP. Postoperative morbidity with mandibular third molar surgery: a comparison of two techniques. J Oral Maxillofac Surg 1988;46:474-6. 5. Loescher AR, Smith KG, Robinson PP. Nerve damage and third molar removal. Dent Update 2003;30:375-80, 382. 6. Kipp DP, Goldstein BH, Weiss WW Jr. Dysesthesia after mandibular third molar surgery: a retrospective study and analysis of 1,377 surgical procedures. J Am Dent Assoc 1980;100:185-92. 7. Wofford DT, Miller RI. Prospective study of dysesthesia following odontectomy of impacted mandibular third molars. J Oral Maxillofac Surg 1987;45:15-9. 8. Rood JP, Shehab BA. The radiological prediction of inferior alveolar nerve injury during third molar surgery. Br J Oral Maxillofac Surg 1990;28:20-5. 9. Osborn TP, Frederickson G Jr, Small IA, Torgerson TS. A prospective study of complications related to mandibular third molar surgery. J Oral Maxillofac Surg 1985;43:767-9. 10. Alling CC 3rd. Dysesthesia of the lingual and inferior alveolar nerves following third molar surgery. J Oral Maxillofac Surg 1986;44:454-7. 11. Ewers R, Hoffmeister B. Functional disorders of the mandibular nerve caused by the molars. Complications after surgical molar extraction. Z Stomatol 1986;83:521-35. 12. Carmichael FA, McGowan DA. Incidence of nerve damage following third molar removal: a West of Scotland Oral Surgery Research Group study. Br J Oral Maxillofac Surg 1992;30:78-82. 13. Rood JP. Lingual split technique. Damage to inferior alveolar and lingual nerves during removal of impacted mandibular third molars. Br Dent J 1983;154:402-3. 14. Sunderland S. A classification of peripheral nerve injuries producing loss of function. Brain 1951;74:491-516. 15. Blackburn CW, Bramley PA. Lingual nerve damage associated with the removal of lower third molars. Br Dent J 1989;167:103-7. 16. Rood JP. Permanent damage to inferior alveolar and lingual nerves during the removal of impacted mandibular third molars. Comparison of two methods of bone removal. Br Dent J 1992;172:108-10. 17. Gerlach KL, Hoffmeister B, Walz C. Dysesthesia and anesthesia of the mandibular nerve following dental treatment. Dtsch Zahnarztl Z 1989;44:970-2. 18. Goldberg MH, Nemarich AN, Marco WP 2nd. Complications after mandibular third molar surgery: a statistical analysis of 500 consecutive procedures in private practice. J Am Dent Assoc 1985;111:277-9.
OOOOE Volume 102, Number 4 19. Miura K, Kino K, Shibuya T, Hirata Y, Shibuya T, Sasaki E, et al. Nerve paralysis after third molar extraction. Kokubyo Gakkai Zasshi 1998;65:1-5. 20. Brann CR, Brickley MR, Shepherd JP. Factors influencing nerve damage during lower third molar surgery. Br Dent J 1999;186:514-6. 21. Kiesselbach JE, Chamberlain JG. Clinical and anatomic observations on the relationship of the lingual nerve to the mandibular third molar region. J Oral Maxillofac Surg 1984;42:565-7. 22. Pedersen GW. Oral surgery. Philadelphia: Saunders; 1988. p. 60 – 81. 23. Gulicher D, Gerlach KL. Sensory impairment of the lingual and inferior alveolar nerves following removal of impacted mandibular third molars. Int J Oral Maxillofac Surg 2001;30:306-12. 24. Mason DA. Lingual nerve damage following lower third molar surgery. Int J Oral Maxillofac Surg 1988;17:290-4. 25. Krafft TC, Hickel R. Clinical investigation into the incidence of direct damage to the lingual nerve caused by local anesthesia. J Craniomaxillofac Surg 1994;22:294-6. 26. Absi E.G., Shepherd JP. A comparison of morbidity following the removal of lower third molars by the lingual split and surgical bur methods. Int J Oral Maxillofac Surg 1993;22:149-53. 27. Greenwood M, Langton SG, Rood JP. A comparison of broad and narrow retractors for lingual nerve protection during lower third molar surgery. Br J Oral Maxillofac Surg 1994;32:114-7. 28. Gargallo-Albiol J, Buenechea-Imaz R, Gay-Escoda C. Lingual nerve protection during surgical removal of lower third molars. a prospective randomised study. Int J Oral Maxillofac Surg 2000;29:268-71. 29. Chossegros C, Guyot L, Cheynet F, Belloni D, Blanc JL. Is lingual nerve protection necessary for lower third molar germectomy? A prospective study of 300 procedures. Int J Oral Maxillofac Surg 2002;31:620-4. 30. Rud J. The split-bone technic for removal of impacted mandibular third molars. J Oral Surg 1970;28:416-21. 31. Bruce RA, Frederickson GC, Small GS. Age of patients and morbidity associated with mandibular third molar surgery. J Am Dent Assoc 1980;101:240-5.
Jerjes et al. e7 32. Black CG. Sensory impairment following lower third molar surgery: a prospective study in New Zealand. N Z Dent J 1997;93:68-71. 33. Bataineh AB. Sensory nerve impairment following mandibular third molar surgery. J Oral Maxillofac Surg 2001;59:1012-7; discussion 1017. 34. Valmaseda-Castellon E, Berini-Aytes L, Gay-Escoda C. Inferior alveolar nerve damage after lower third molar surgical extraction: a prospective study of 1117 surgical extractions. Oral Surg Oral Med Oral Pathol Oral Radiol Endod 2001;92:377-83. 35. Gulicher D, Gerlach KL. Incidence, risk factors and follow-up of sensation disorders after surgical wisdom tooth removal. Study of 1,106 cases. Mund Kiefer Gesichtschir 2000;4:99-104. 36. Capuzzi P, Montebugnoli L, Vaccaro MA. Extraction of impacted third molars. A longitudinal prospective study on factors that affect postoperative recovery. Oral Surg Oral Med Oral Pathol Oral Radiol Endod 1994;77:341-3. 37. Pogrel MA. Complications of third molar surgery. In: Kaban LB, Pogrel MA, Perrott DH, editors. Complications in oral and maxillofacial surgery. Philadelphia: Saunders; 1997. p. 59. 38. Robinson PP. Observations on the recovery of sensation following inferior alveolar nerve injuries. Br J Oral Maxillofac Surg 1988;26:177-89. 39. Girard KR. Considerations in the management of damage to the mandibular nerve. J Am Dent Assoc 1979;98:65-71. 40. Meyer RA. Evaluation and management of neurologic complications. In: Kaban LB, Pogrel MA, Perrott DH, editors. Complications in oral and maxillofacial surgery. Philadelphia: Saunders; 1997. p. 69.
Reprint requests: Waseem Jerjes Department of Oral & Maxillofacial Surgery Eastman Dental Institute for Oral Healthcare Sciences 256 Gray’s Inn Road London WC1X 8LD United Kingdom [email protected]