Incidence of nerve damage following third molar removal: A West of Scotland Oral Surgery Research Group Study F. A. Carmichael,
I>. A.
McGowan
Department of Oral Surgery, Glasgow G2 3.12
Glasgow Dental Hospital and School,
.378 Sauchiehall
Street,
SUMMARY. A survey was carried out to record both initial and longterm effects on the lingual and inferior alveolar nerves following third molar removal. Light hundred and twenty five patients were included from eight West of Scotland Oral Surgery Units, and had 1339 third molars removed. Changes in sensation were recorded by direct questioning at 6 to 24 h and 7 to 10 days, and by postal questionnaire at 12-18 months. The incidence of lingual nerve damage was found to be 15% of operated sides at 6 to 24 hours, 10.7”10 at 7 to 10 days, and 0.6% after 1 year. The incidence of inferior alveolar nerve damage was 5.5% of operated sides at 6 to 24 h, 3.9% at 7 to 10 days, and 0.9% after 1 year. These results are proposed as an indication of the likely incidence of nerve damage complicating third molar removal in the general circumstances of current United Kingdom practice and are presented as a basis for discussion of patient information and current prudent practice. Since one in four patients suffered at least temporary sensory deficit, we believe the case for effective warning of all patients undergoing impacted third molar removal is overwhelming.
Inferior alveolar nerve. Damage to this nerve has been more widely studied. Again there is a wide range of reported incidenccs ranging from 0.4 to 5.5% (Table 2). These papers are not always clear as to whether patients or teeth are being referred to. An increase in incidence has been related to more deeply impacted teeth (Rud, 1970) and to less expertenced surgeons (Sisk et al., 1986).
INTRODUCTION The removal of mandibular third molars results in many unwanted scquelac like pain, swelling, bruising and trismus. While these are unfortunate for the patient they are perhaps not unexpected following minor oral surgery. The patient may however be dissatisfied if the surgery results in impaired sensation. particulary if no prior warning has been given. Damage to the lingual and inferior alveolar nerves is distressing and is also a source of complaint and. increasingly. of litigation against the surgeon.
Mylohyoid nerve. Mylohyoid nerve damage is rarely mentioned in the literature as it can be confused with inferior alveolar nerve damage. It gives an area of
Lingual nerve. The incidence of nerve damage following mandibular third molar surgery has been widely reported, with quite marked differences in figures between the various studies. It ranges from 0.6 to 22%. Obviously the criteria for inclusion, techniques used, method of testing and time span varies in these studies (Table 1). Schwartz (1973) in a survey of 2500 members of the American Society of Oral Surgeons found 66% of the respondents had experienced the problem of impaired lingual sensation. There were 41X cases of permanent impairment and 2399 of temporary. The reported time span for recovery ranged from 2 days to 10 years. Litigation resulted from 53 cases. Ailing (1986) also sent questionnaires to 103 Fellows of the American Association of Oral and Maxillofacial Surgeons. Of those who replied an incidence of lingual dysesthcsia of @.06% was reported and of those 13% were persistent.
‘Table I - Lingual nerve damage following mandibular
third molar
surgery Author Rlld Bruce Rood
104~1 teeth I I .5x (decreased to 0.6%) 550 patients 22’Y0 (decreased to 0%) 1117 teeth II’X (decrcascd to 0.5% at 36 weeks)
1984
Goldberg
Von
Year .~
1985 1986 1988
Kr Simpson
1989
& Rramley
1989
Incidence
Incidence
Table 2 -
Inferior alveolar molar surgery
third Author
Year
Robinson Frank flowe & Rud
I940 1959
Van
GoI
Poyton
1960
I’)70 er nl.
1077 19x0
Bruce Rood
EI ul.
RUd
Goldhcrg
CI ol.
Sisk P/ ul.
Von Arx 84 Simpson
of ncrvc damage following third molar removal: ,Z West ncrv’c damage
NO.
--------___ 300 patients
300 teeth l3.55 teeth
following
mandibular
Incidence
I (3I!‘” 5 .3‘ %, 5.2% 2.2%
71Y (deep) teeth 162 (not deep) I .2‘Z 932 pts & teeth 1.4% (decreased to 0% at 4 months) 1337 teeth 4.49% (dccrcased to at Icast I’%, at 6 months) 765 patients 7 1‘ %, 990prs & tcetn 4.4% 1400 teeth 5.5% (dccrcased to 0.4% at 6 months) 334 teeth 3% (lingual split removed) 73 teeth 3% (lingual split retained) 500 teeth 0.60/u (decreased to 0% at 6 months) 843 teeth 0.4% (cxpericnccd operators) 3SY teeth 3 ,6% (less expcricnced operators) 550 patients 5% (decreased to 0%)
altered sensation at the point of the chin, if effected and most investigators do not ask specifically about this nerve. The aim of this study was to record the incidence of lingual, inferior alveolar and mylohyoid nerve deficit and to attempt to correlate the results with the type and degree of impaction and method of removal. This would assist in the decision as to how thorough we should be in warning prospective patients about their chances of sustaining nerve damage. The study was dclibcratcly planned to be simple in operation and to record the experience of a substantial group of patients undergoing surgery in the routine circumstancesofcurrenthospital practice. The oral surgeons in the West of Scotland have a wide variety of training backgrounds and there is no tradition of strict adherence to common operating protocols. The results of the survey should therefore be broadly representative of current British experience.
MATERIALS
AND METHODS
Records were completed for 825 consecutive patients who presented for third molar surgery in eight West of Scotland Oral Surgery Units. There was no case selection apart from the fact that the patients required removal of an impacted lower third molar. A total of 1339 teeth were removed during an s-month period. Roth local and general anacsthesia were used. All grades of staff including undergraduate students carried out the surgery. The surgeons were asked to complete a form which recorded the state of eruption. angulation and associated pathology. This was assessed both clinically and radiographically.
ofScotlandOral
Surgery Research
Group Study
7Y
Type of anaesthcsia. method of bone removal (chisel or bur) or simple elevation, use of a lingual flap retractor, division of tooth and suturing were recorded. The surgeons also noted whether the patients were warned preoperatively of possible sensory dcfici t . Assessment of postoperative deficit was carried out by standard questioning, for example: ‘Do you have normal feeling in your lip, tongue and at the point of the chin’?‘. If the tongue was affcctcd the questions were asked: ‘Is it completely affected on one side or just the tip?’ and ‘Is it numb, tingling or painful?‘. If the inferior alveolar nerve was affected the questions were asked: ‘1s it the lip or lip and chin which are affected?’ and ‘1s it numb, tingling or painful?‘. These enquiries took place at between 6 to 24 hours and at 7 to 10 days. The symptoms recorded were purely subjective and although sensory testing may have been carried out this was not required to bc recorded. At approximately 1 year (range 12 to I8 months) only the patients who had given a positive response at 7 to 10 days were sent a postal questionnaire cnquiring as to whether they still had a change in sensation of their lip or tongue. One hundred and thirty five patients of a possible 169 replied (80% response rate). The data were coded and analysed on the Glasgow University Computing Services ICI, 3980 using the SPSSX programme. Chi square tests were used to calculate probabilities for comparisons.
RESULTS Results were obtained from 825 patients (31.5 males and 5 10 females). There was no cast selection and a total of 1339 teeth were removed. Most of the patients were aged between I6 and 30 years. and 4% of teeth were recorded as being erupted. 48% partially erupted and 48% uncruptcd. Those teeth reported as uneruptcd were assessed radiographically and 33.6% were found to have just soft tissue cover. 13% incomplete bone cover and 53.4% complete bone cover. The commonest angulation was mcsioangular (40%), followed by vertical (29%). distoangular and horizontal (15% each). and 1% were transverse or classified as ‘other’. which included other aberrant positions. Most teeth were removed because of a history of pericoronitis (59%) although caries. periapical infection and the presence of a related cyst were also listed. One hundred and sixteen teeth were removed for ‘other’ reasons, presumably for orthodontic indications or as a contralateral symptomless tooth in a patient undcrgoing a general anacsthctic. The majority (82.5%) of the teeth were removed under general anaesthesia, the remainder under local anaesthesia or local anacsthcsia with sedation. Chisels were used to rcmovc bone in 58% of cases, drills in 31% and 1I % did not rcquirc bone removal. Lingual flap retraction was used in 71% of cases. A Howarth’s pcriostcal elevator was usually used. the frequency varying with the depth of impaction: in 23% of erupted
X0
British Journal of Oral and ~axillofacial
Surrerb
teeth, 64% of those partly erupted, 65% of those unerupted with only soft tissue cover. 90% of those unerupted with incomplete bone cover and 98% of those uneruptcd with complete bone cover. Division was required in 218 teeth and 1017 wounds were sutured. Preoperative warnings of possible ncrvc deficit ranged from 82 to 100%. This varied from hospital to hospital, the lowest frequency being at the Dental Ilospital and School. This may be due to the fact that simpler cases were being carried out there and surgeons were reluctant to raise the possibility of nerve damage when they believed it to be unlikely. It may also bc the cast that relatively junior members of staff trcatcd these patients without reference to a more senior colleague. Ihzgual
We found no significant difference between the USC of a chisel or bur (19.6% of those removed with a chisel being affected and 13.5% of those removed with a bur). There was a significant increase in the incidence of deficit if a lingual retractor was inserted (chi square p
I>. A.
McGowan
Department of Oral Surgery, Glasgow G2 3.12
Glasgow Dental Hospital and School,
.378 Sauchiehall
Street,
SUMMARY. A survey was carried out to record both initial and longterm effects on the lingual and inferior alveolar nerves following third molar removal. Light hundred and twenty five patients were included from eight West of Scotland Oral Surgery Units, and had 1339 third molars removed. Changes in sensation were recorded by direct questioning at 6 to 24 h and 7 to 10 days, and by postal questionnaire at 12-18 months. The incidence of lingual nerve damage was found to be 15% of operated sides at 6 to 24 hours, 10.7”10 at 7 to 10 days, and 0.6% after 1 year. The incidence of inferior alveolar nerve damage was 5.5% of operated sides at 6 to 24 h, 3.9% at 7 to 10 days, and 0.9% after 1 year. These results are proposed as an indication of the likely incidence of nerve damage complicating third molar removal in the general circumstances of current United Kingdom practice and are presented as a basis for discussion of patient information and current prudent practice. Since one in four patients suffered at least temporary sensory deficit, we believe the case for effective warning of all patients undergoing impacted third molar removal is overwhelming.
Inferior alveolar nerve. Damage to this nerve has been more widely studied. Again there is a wide range of reported incidenccs ranging from 0.4 to 5.5% (Table 2). These papers are not always clear as to whether patients or teeth are being referred to. An increase in incidence has been related to more deeply impacted teeth (Rud, 1970) and to less expertenced surgeons (Sisk et al., 1986).
INTRODUCTION The removal of mandibular third molars results in many unwanted scquelac like pain, swelling, bruising and trismus. While these are unfortunate for the patient they are perhaps not unexpected following minor oral surgery. The patient may however be dissatisfied if the surgery results in impaired sensation. particulary if no prior warning has been given. Damage to the lingual and inferior alveolar nerves is distressing and is also a source of complaint and. increasingly. of litigation against the surgeon.
Mylohyoid nerve. Mylohyoid nerve damage is rarely mentioned in the literature as it can be confused with inferior alveolar nerve damage. It gives an area of
Lingual nerve. The incidence of nerve damage following mandibular third molar surgery has been widely reported, with quite marked differences in figures between the various studies. It ranges from 0.6 to 22%. Obviously the criteria for inclusion, techniques used, method of testing and time span varies in these studies (Table 1). Schwartz (1973) in a survey of 2500 members of the American Society of Oral Surgeons found 66% of the respondents had experienced the problem of impaired lingual sensation. There were 41X cases of permanent impairment and 2399 of temporary. The reported time span for recovery ranged from 2 days to 10 years. Litigation resulted from 53 cases. Ailing (1986) also sent questionnaires to 103 Fellows of the American Association of Oral and Maxillofacial Surgeons. Of those who replied an incidence of lingual dysesthcsia of @.06% was reported and of those 13% were persistent.
‘Table I - Lingual nerve damage following mandibular
third molar
surgery Author Rlld Bruce Rood
104~1 teeth I I .5x (decreased to 0.6%) 550 patients 22’Y0 (decreased to 0%) 1117 teeth II’X (decrcascd to 0.5% at 36 weeks)
1984
Goldberg
Von
Year .~
1985 1986 1988
Kr Simpson
1989
& Rramley
1989
Incidence
Incidence
Table 2 -
Inferior alveolar molar surgery
third Author
Year
Robinson Frank flowe & Rud
I940 1959
Van
GoI
Poyton
1960
I’)70 er nl.
1077 19x0
Bruce Rood
EI ul.
RUd
Goldhcrg
CI ol.
Sisk P/ ul.
Von Arx 84 Simpson
of ncrvc damage following third molar removal: ,Z West ncrv’c damage
NO.
--------___ 300 patients
300 teeth l3.55 teeth
following
mandibular
Incidence
I (3I!‘” 5 .3‘ %, 5.2% 2.2%
71Y (deep) teeth 162 (not deep) I .2‘Z 932 pts & teeth 1.4% (decreased to 0% at 4 months) 1337 teeth 4.49% (dccrcased to at Icast I’%, at 6 months) 765 patients 7 1‘ %, 990prs & tcetn 4.4% 1400 teeth 5.5% (dccrcased to 0.4% at 6 months) 334 teeth 3% (lingual split removed) 73 teeth 3% (lingual split retained) 500 teeth 0.60/u (decreased to 0% at 6 months) 843 teeth 0.4% (cxpericnccd operators) 3SY teeth 3 ,6% (less expcricnced operators) 550 patients 5% (decreased to 0%)
altered sensation at the point of the chin, if effected and most investigators do not ask specifically about this nerve. The aim of this study was to record the incidence of lingual, inferior alveolar and mylohyoid nerve deficit and to attempt to correlate the results with the type and degree of impaction and method of removal. This would assist in the decision as to how thorough we should be in warning prospective patients about their chances of sustaining nerve damage. The study was dclibcratcly planned to be simple in operation and to record the experience of a substantial group of patients undergoing surgery in the routine circumstancesofcurrenthospital practice. The oral surgeons in the West of Scotland have a wide variety of training backgrounds and there is no tradition of strict adherence to common operating protocols. The results of the survey should therefore be broadly representative of current British experience.
MATERIALS
AND METHODS
Records were completed for 825 consecutive patients who presented for third molar surgery in eight West of Scotland Oral Surgery Units. There was no case selection apart from the fact that the patients required removal of an impacted lower third molar. A total of 1339 teeth were removed during an s-month period. Roth local and general anacsthesia were used. All grades of staff including undergraduate students carried out the surgery. The surgeons were asked to complete a form which recorded the state of eruption. angulation and associated pathology. This was assessed both clinically and radiographically.
ofScotlandOral
Surgery Research
Group Study
7Y
Type of anaesthcsia. method of bone removal (chisel or bur) or simple elevation, use of a lingual flap retractor, division of tooth and suturing were recorded. The surgeons also noted whether the patients were warned preoperatively of possible sensory dcfici t . Assessment of postoperative deficit was carried out by standard questioning, for example: ‘Do you have normal feeling in your lip, tongue and at the point of the chin’?‘. If the tongue was affcctcd the questions were asked: ‘Is it completely affected on one side or just the tip?’ and ‘Is it numb, tingling or painful?‘. If the inferior alveolar nerve was affected the questions were asked: ‘1s it the lip or lip and chin which are affected?’ and ‘1s it numb, tingling or painful?‘. These enquiries took place at between 6 to 24 hours and at 7 to 10 days. The symptoms recorded were purely subjective and although sensory testing may have been carried out this was not required to bc recorded. At approximately 1 year (range 12 to I8 months) only the patients who had given a positive response at 7 to 10 days were sent a postal questionnaire cnquiring as to whether they still had a change in sensation of their lip or tongue. One hundred and thirty five patients of a possible 169 replied (80% response rate). The data were coded and analysed on the Glasgow University Computing Services ICI, 3980 using the SPSSX programme. Chi square tests were used to calculate probabilities for comparisons.
RESULTS Results were obtained from 825 patients (31.5 males and 5 10 females). There was no cast selection and a total of 1339 teeth were removed. Most of the patients were aged between I6 and 30 years. and 4% of teeth were recorded as being erupted. 48% partially erupted and 48% uncruptcd. Those teeth reported as uneruptcd were assessed radiographically and 33.6% were found to have just soft tissue cover. 13% incomplete bone cover and 53.4% complete bone cover. The commonest angulation was mcsioangular (40%), followed by vertical (29%). distoangular and horizontal (15% each). and 1% were transverse or classified as ‘other’. which included other aberrant positions. Most teeth were removed because of a history of pericoronitis (59%) although caries. periapical infection and the presence of a related cyst were also listed. One hundred and sixteen teeth were removed for ‘other’ reasons, presumably for orthodontic indications or as a contralateral symptomless tooth in a patient undcrgoing a general anacsthctic. The majority (82.5%) of the teeth were removed under general anaesthesia, the remainder under local anaesthesia or local anacsthcsia with sedation. Chisels were used to rcmovc bone in 58% of cases, drills in 31% and 1I % did not rcquirc bone removal. Lingual flap retraction was used in 71% of cases. A Howarth’s pcriostcal elevator was usually used. the frequency varying with the depth of impaction: in 23% of erupted
X0
British Journal of Oral and ~axillofacial
Surrerb
teeth, 64% of those partly erupted, 65% of those unerupted with only soft tissue cover. 90% of those unerupted with incomplete bone cover and 98% of those uneruptcd with complete bone cover. Division was required in 218 teeth and 1017 wounds were sutured. Preoperative warnings of possible ncrvc deficit ranged from 82 to 100%. This varied from hospital to hospital, the lowest frequency being at the Dental Ilospital and School. This may be due to the fact that simpler cases were being carried out there and surgeons were reluctant to raise the possibility of nerve damage when they believed it to be unlikely. It may also bc the cast that relatively junior members of staff trcatcd these patients without reference to a more senior colleague. Ihzgual
We found no significant difference between the USC of a chisel or bur (19.6% of those removed with a chisel being affected and 13.5% of those removed with a bur). There was a significant increase in the incidence of deficit if a lingual retractor was inserted (chi square p
