NEUROSENSORY DISTURBANCES FOLLOWING
SURGICAL REMOVAL OF MANDIBULAR THIRD
MOLAR
INDIAN DENTAL ACADEMY
Leader in continuing ...
• INTRODUCTION
• NERVE DAMAGE
• ANATOMICAL RELATIONSHIP
• PRE-OPERATIVE ASSESSMENT
• INTRA-OPERATIVE FACTORS
• CLINICAL TE...
INTRODUCTION
• The face, and in particular the oral and peri oral
regions, are among the areas with the highest
density of...
• Mandibular third molars are the most
frequently impacted teeth.
• 91.9% of the extractions are carried out
without any s...
Incidence
The risk of developing inferior dental nerve
(IDN) deficit ranges from 0.26 to 8.4%.
The risk of lingual nerve (...
NERVE DAMAGE
• The definition of neurosensory dysfunction (also known as
dysesthesia) includes
– anesthesia (loss of sensa...
Seddon and Sunderland
Neuropraxia (Seddon)
First degree injury (Sunderland)
Axonotmesis (Seddon)
Second degree (Sunderland...
• Compression injuries -
elevation of a third molar with
roots in close proximity to the
mandibular canal.
• Stretch injur...
ANATOMICAL RELATIONSHIP
• The Lingual nerve courses from
a more lateral to medial
position as it approaches the
mandibular...
• Hölzle and Wolff (2001), the LN lies considerably
closer to the oral mucosa with a mean distance of
4.41 ± 1.44 mm.
• Po...
Joms 2000 58:649-651
www.indiandentalacademy.com
• In 15% it may lie at or above the crest of the lingual plate
of the mandible.
• Kiesselbach and Chamberlain -17.6% of hu...
The inferior alveolar nerve
• In some cases the nerve is very close
to the roots of the mandibular third
molars and even m...
PRE-OPERATIVE ASSESSMENT
• To avoid surgical complications, proper radiographic
assessment is essential to determine the e...
• OPG & IOPA are commonly preferred
• Paralleling technique is the preferred
method for obtaining periapical
radiographs, ...
Limitations
• A fundamental one is that, the three dimensional
anatomy is collapsed into a two-dimensional
surface, which ...
Radiologic criteria indicating need for
CT scan
1. Radiolucent band (23%)
2. Loss of MC border (32%)
3. Change MC directio...
Does computed tomography prevent
inferior alveolar nerve injuries caused
by lower third molar removal?
• Positive radiogra...
Panoramic vs CT
• The panoramic finding of impacted mandibular third
molar root darkening was considered to reflect thinni...
Dentomaxillofacial Radiology (2009) 38, 11–16
’ 2009 The British Institute of Radiologywww.indiandentalacademy.com
PRE-OP ASSESSMENT
INFERIOR ALVEOLAR NERVE
• Incidences of IDN deficit in fully erupted, partially
erupted and unerupted lo...
Radiographic sign
British Journal of Oral and Maxillofacial Surgery (2004) 42, 21—27
www.indiandentalacademy.com
Radiographic sign
• 964 subjects from 2 studies9,93 were included.
• The incidence of IDN deficit was highest in
radiograp...
Adult vs Adoloscence
• The removal of impacted teeth from adult patients
was found to be more difficult and it came along
...
PRE-OP ASSESSMENT
LINGUAL NERVE
• 3 studies22,24,29 with 5875 subjects
• Incidences of LN deficit in fully erupted, partia...
INTRA-OPERATIVE FACTORS
• 5 studies with 2028 subjects
reported,
• 16.2% of the surgery with the IAN
exposed developed pos...
Surgical technique and postoperative
IAN deficit
• 20 studies reported the surgical
technique and postoperative IDN
defici...
• leaving small tips of the roots unremoved
rather than risking injury to the inferior
alveolar nerve.
JADA 1980: 100: 185...
INTRA-OP FACTORS
LINGUAL NERVE
• 16 paperswith 10,893 subjects reported whether the
surgery included raising the lingual f...
• As stated by BLACKBURN ‘The lesson to be learnt is
quite simple, never let the bur enter the tissues on
the lingual side...
INTRA-OP FACTORS
LINGUAL NERVE
• 26 studiesreported the surgical technique and
postoperative LN deficit.
• The incidences ...
Clinical neurosensory testing
Mechanoceptive
• Two-point
discrimination,
• Static light touch
• Brush directional
stroke t...
• Neurosensory testing is designed to determine the
degree of sensory disturbance, to monitor sensory
recovery and to poin...
ASSESSMENT
• All patients were reviewed 1 week after surgery, to
assess wound healing status and the presence of any
neuro...
• In former studies, alterations of sensation persisting
longer than 6 months after injury were commonly
considered to be ...
Time of Recovery
Collateral reinnervation from adjacent nerves
may account for some instances of early
sensory recovery
Al...
THANK YOU
www.indiandentalacademy.com
For more details please visit
www.indiandentalacademy.com
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Neurosensory disturvances following surgucal removal of mandibular third molar

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Neurosensory disturvances following surgucal removal of mandibular third molar

  1. 1. NEUROSENSORY DISTURBANCES FOLLOWING SURGICAL REMOVAL OF MANDIBULAR THIRD MOLAR INDIAN DENTAL ACADEMY Leader in continuing dental education www.indiandentalacademy.com www.indiandentalacademy.com
  2. 2. • INTRODUCTION • NERVE DAMAGE • ANATOMICAL RELATIONSHIP • PRE-OPERATIVE ASSESSMENT • INTRA-OPERATIVE FACTORS • CLINICAL TESTING www.indiandentalacademy.com
  3. 3. INTRODUCTION • The face, and in particular the oral and peri oral regions, are among the areas with the highest density of peripheral receptors, presumably because of their remarkable importance in daily life. • It is difficult to tolerate neurological disturbances in oral and maxillofacial areas compared to other parts of the body www.indiandentalacademy.com
  4. 4. • Mandibular third molars are the most frequently impacted teeth. • 91.9% of the extractions are carried out without any serious complications. • Injury to the lingual, inferior alveolar and sensory branch of the mylohyoid nerves is an infrequent but unpleasant complication. J Maxillofac Surg 2003; 61:1379-89 www.indiandentalacademy.com
  5. 5. Incidence The risk of developing inferior dental nerve (IDN) deficit ranges from 0.26 to 8.4%. The risk of lingual nerve (LN) deficit ranges from 0.1 to 22% Int. J. Oral Maxillofac. Surg. 2011; 40: 1–10www.indiandentalacademy.com
  6. 6. NERVE DAMAGE • The definition of neurosensory dysfunction (also known as dysesthesia) includes – anesthesia (loss of sensation, usually because of damage to a nerve or receptor; also called numbness) and paresthesia (abnormal touch sensation, such as burning, prickling, or formication, often in the absence of an external stimulus). Dorland I, Newman • The consequences and subsequent recovery following nerve damage are dependent upon the severity of the injury, and this is the basis for the classifications of nerve injury proposed by Seddon and Sunderland www.indiandentalacademy.com
  7. 7. Seddon and Sunderland Neuropraxia (Seddon) First degree injury (Sunderland) Axonotmesis (Seddon) Second degree (Sunderland) Neurotmesis (Seddon) Third degree Fourth degree (Sunderland) Fifth degree:(Sunderland) Minor compression, nerve trunk manipulation More severe compression or"crush" injuries Traction or compression injection & chemical injury Laceration, avulsion and chemical injury Int. J. Oral Maxillofac. Surg. 2000; 29:331336 Dent Update 2003; 30: 375–382www.indiandentalacademy.com
  8. 8. • Compression injuries - elevation of a third molar with roots in close proximity to the mandibular canal. • Stretch injuries when raising a lingual mucoperiosteal flap. • Neurotemesis or Complete section of the nerve trunk may occur if the inferior alveolar nerve penetrates the root of a third molar and is severed duringtooth removal. Dent Update 2003; 30: 375–382www.indiandentalacademy.com
  9. 9. ANATOMICAL RELATIONSHIP • The Lingual nerve courses from a more lateral to medial position as it approaches the mandibular third molar. • As the Lingual nerve approaches the third molar, its position with respect to the alveolar bone, is variable. www.indiandentalacademy.com
  10. 10. • Hölzle and Wolff (2001), the LN lies considerably closer to the oral mucosa with a mean distance of 4.41 ± 1.44 mm. • Pogrel (1995) The mean vertical distance from the alveolar crest to the LN reported a distance of 8.3 ± 4.1 mm. • Horizontal Distance of LN to Lingual Plate : 2.1 ± 1.1 mm reported by Behnia et al. (2000). IJOMS. 30: 333-8 , JOMS 1995 53: 1178.JOMS 2000 58: 649-51 www.indiandentalacademy.com
  11. 11. Joms 2000 58:649-651 www.indiandentalacademy.com
  12. 12. • In 15% it may lie at or above the crest of the lingual plate of the mandible. • Kiesselbach and Chamberlain -17.6% of human cadavers the lingual nerve was at or above the alveolar crest and in some cases may lie in the retromolar tissues. J Oral Maxillofac Surg. 1984; 42: 565-67 www.indiandentalacademy.com
  13. 13. The inferior alveolar nerve • In some cases the nerve is very close to the roots of the mandibular third molars and even makes deep impression on the roots or passing through them. • The nerve is at risk in these cases during lower third molar surgery www.indiandentalacademy.com
  14. 14. PRE-OPERATIVE ASSESSMENT • To avoid surgical complications, proper radiographic assessment is essential to determine the exact topographic relationship between the mandibular canal and the lower molars. • OPG • PERIAPICAL RADIOGRAPH • CT CLINICAL DENTISTRY AND RESEARCH 2012; 36(1): 2-7 www.indiandentalacademy.com
  15. 15. • OPG & IOPA are commonly preferred • Paralleling technique is the preferred method for obtaining periapical radiographs, as it minimizes geometric distortion and presents the teeth and supporting bone in their true anatomic relationships. www.indiandentalacademy.com
  16. 16. Limitations • A fundamental one is that, the three dimensional anatomy is collapsed into a two-dimensional surface, which causes image features representing different anatomical structures to be superimposed. • Features of diagnostic interest may, therefore, be obscured and diagnostic accuracy is decreased. CLINICAL DENTISTRY AND RESEARCH 2012; 36(1): 2-7 www.indiandentalacademy.com
  17. 17. Radiologic criteria indicating need for CT scan 1. Radiolucent band (23%) 2. Loss of MC border (32%) 3. Change MC direction (39%) 4. MC narrowing (57%) 5. Root narrrow (36%) 6. Root deviation (32%) 7. Bifid apex (25%) 8. Superimposed (5%) 9. Contact MC (7%) Australian Dental Journal 2006;51:(1):64-68www.indiandentalacademy.com
  18. 18. Does computed tomography prevent inferior alveolar nerve injuries caused by lower third molar removal? • Positive radiographic signs (darkening of the root and narrowing of the inferior alveolar canal) were associated with more requests for CT scanning. • CT does not seem to significantly decrease the risk of producing IAN injury. J Oral Maxillofac Surg. 2012 Jan;70(1):5-1 www.indiandentalacademy.com
  19. 19. Panoramic vs CT • The panoramic finding of impacted mandibular third molar root darkening was considered to reflect thinning or perforation of the cortical plate rather than grooving of the root. Cortical thinning or perforation was found in 80% of the cases with this panoramic finding. • Such information will be important for surgeons to avoid the risk of lingual nerve injury at the time of extraction Dentomaxillofacial Radiology (2009) 38, 11–16 ’ 2009 The British Institute of Radiologywww.indiandentalacademy.com
  20. 20. Dentomaxillofacial Radiology (2009) 38, 11–16 ’ 2009 The British Institute of Radiologywww.indiandentalacademy.com
  21. 21. PRE-OP ASSESSMENT INFERIOR ALVEOLAR NERVE • Incidences of IDN deficit in fully erupted, partially erupted and unerupted lower wisdom teeth were 0.3%, 0.7% and 3.0%, respectively. • The incidence of IDN deficit was highest in horizontally impacted(1.7%), distal impaction (1.4%), mesial impaction (1.3%) and vertical impaction (1.1%). Int. J. Oral Maxillofac. Surg. 2011; 40: 1–10www.indiandentalacademy.com
  22. 22. Radiographic sign British Journal of Oral and Maxillofacial Surgery (2004) 42, 21—27 www.indiandentalacademy.com
  23. 23. Radiographic sign • 964 subjects from 2 studies9,93 were included. • The incidence of IDN deficit was highest in radiographic sign of • diversion of ID canal by its root (30%), • darkening of root (11.6%) and • deflected root by the ID canal (4.6%). • These 3 signs were found to increase the risk of IDN deficit significantly Int. J. Oral Maxillofac. Surg. 2011; 40: 1–10www.indiandentalacademy.com
  24. 24. Adult vs Adoloscence • The removal of impacted teeth from adult patients was found to be more difficult and it came along with sensory loss more often than in the juveniles. • To minimize the risk of numbness • check for the necessity of third molar surgery during adolescence. J Am Dent Assoc 1980: 101: 240–245.www.indiandentalacademy.com
  25. 25. PRE-OP ASSESSMENT LINGUAL NERVE • 3 studies22,24,29 with 5875 subjects • Incidences of LN deficit in fully erupted, partially erupted and unerupted lower wisdom teeth were 0.3%, 2.0% and 5.8%, • LN deficit was highest in distally impacted (4.0%), • horizontal impaction (2.8%), • Mesio angular (2.4%) & • vertical impaction (1.9%). Int. J. Oral Maxillofac. Surg. 2011; 40: 1–10www.indiandentalacademy.com
  26. 26. INTRA-OPERATIVE FACTORS • 5 studies with 2028 subjects reported, • 16.2% of the surgery with the IAN exposed developed postoperative IANdeficit, • only 1.1% of the surgeries without IAN exposure developed IAN deficit; • The risk ratio of IAN deficit from intraoperative IAN exposure is 14.9 times more likely than if the IAN is not exposed Int. J. Oral Maxillofac. Surg. 2011; 40: 1–10www.indiandentalacademy.com
  27. 27. Surgical technique and postoperative IAN deficit • 20 studies reported the surgical technique and postoperative IDN deficit. • The incidences of IDN deficit following the buccal approach, lingual split technique and coronectomy were 2.5%, 5.7% and 0%, respectively. • The risk ratio of IAN deficit is therefore 2.3 times more likely using the lingual split technique than the buccal approach. Int. J. Oral Maxillofac. Surg. 2011; 40: 1–10www.indiandentalacademy.com
  28. 28. • leaving small tips of the roots unremoved rather than risking injury to the inferior alveolar nerve. JADA 1980: 100: 185–192. www.indiandentalacademy.com
  29. 29. INTRA-OP FACTORS LINGUAL NERVE • 16 paperswith 10,893 subjects reported whether the surgery included raising the lingual flap or not. • 3.1% with lingual flap raised showed LN deficit • whereas only 1.5% of LN deficit occurred in surgery in which the lingual flap was not raised. • The risk ratio of LN deficit was 1.94 times more likely to occur if the lingual flap was raised than if it was not. Int. J. Oral Maxillofac. Surg. 2011; 40: 1–10www.indiandentalacademy.com
  30. 30. • As stated by BLACKBURN ‘The lesson to be learnt is quite simple, never let the bur enter the tissues on the lingual side of the mandible, whether there is a lingual flap retractor/guard in position or not’. Br J Oral Maxillofac Surg 1992: 30: 72–77.www.indiandentalacademy.com
  31. 31. INTRA-OP FACTORS LINGUAL NERVE • 26 studiesreported the surgical technique and postoperative LN deficit. • The incidences of LN deficit using the buccal approach, lingual split technique and coronectomy were 2.3%, 9.3% and 0.7%, respectively. • With the increasing depth of impaction,LN deficit could be explained by the probable need to use a lingual retractor during surgery, which itself increased the risk of LN deficit. Br J Oral Maxillofac Surg 1992: 30: 78–82. www.indiandentalacademy.com
  32. 32. Clinical neurosensory testing Mechanoceptive • Two-point discrimination, • Static light touch • Brush directional stroke tests Nociceptive • Pin-prick • Thermal discrimination ( localization, sharp/ blunt discrimination) • Dental vitality test www.indiandentalacademy.com
  33. 33. • Neurosensory testing is designed to determine the degree of sensory disturbance, to monitor sensory recovery and to point out whether or not surgical intervention may be indicated Pin prick Two point discrimination Int. J. Oral Maxillofac. Surg. 2000; 29:331336www.indiandentalacademy.com
  34. 34. ASSESSMENT • All patients were reviewed 1 week after surgery, to assess wound healing status and the presence of any neurosensory deficits related to the lower third molar tooth surgery. • Self-reported subjective sensory changes were recorded and objective assessments done • They were monitored regularly postoperatively to assess the pattern of recovery after 1 month, 3 months, 6 months, 1 year and 2 years and beyond, according to the standardized assessments Int. J. Oral Maxillofac. Surg. 2010; 39: 320–326 www.indiandentalacademy.com
  35. 35. • In former studies, alterations of sensation persisting longer than 6 months after injury were commonly considered to be permanent. • But there are also reports of restitution occurring 7– 9 months after surgery Int. J. Oral Maxillofac. Surg. 2001; 30: 306–312 www.indiandentalacademy.com
  36. 36. Time of Recovery Collateral reinnervation from adjacent nerves may account for some instances of early sensory recovery Altered sensation that recovered within 3 months (57.9%) Sunderland first- and second- degree nerve injuries, Altered sensation at 6 months (34.2%) Sunderland third-degree nerve injuries. The persistence of sensory alteration in 28.9% of sites at 1 yr Sunderland fourth-degree injury J Oral Maxillofac Surg 62:592-600, 2004www.indiandentalacademy.com
  37. 37. THANK YOU www.indiandentalacademy.com For more details please visit www.indiandentalacademy.com

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