Risk factors of neurosensory deficits in lower third molar surgery: a literature review of prospective studies


This literature review assessed the risk factors linked to inferior dental nerve (IDN) and lingual nerve (LN) deficits following lower wisdom tooth surgery. A computer search of several databases with specified key words was performed. 32 articles were selected; the risk factors for IDN deficit were reported in 4 articles, LN in 9 and both IDN and LN in 19. Data were analysed statistically to evaluate the potential risk factors. Literature review showed specific radiographic signs and intra-operative IDN exposure increased the risk of IDN deficit. Raising the lingual flap significantly increased the risk of LN deficit. Unerupted tooth and lingual split technique increased IDN and LN deficit risks significantly. Age was linked to IDN and LN deficits, and deep impaction was related to IDN deficit, but no statistical tests were performed on these two risk factors owing to the heterogeneity of data from the studies. This literature review found increased age, unerupted tooth, deep impaction, specific radiographic signs, intra-operative IDN exposure and lingual split technique were risk factors for IDN deficit; increased age, unerupted tooth, distal impaction, raising of lingual flap and lingual split technique were risks factors for LN deficit in lower wisdom tooth surgery.

Neurosensory deficit is a complication after lower wisdom tooth surgery and its occurrence is not uncommon. The risk of developing inferior dental nerve (IDN) deficit ranges from 0.26 to 8.4% in the literature , and the risk of lingual nerve (LN) deficit ranges from 0.1 to 22% . Patients with IDN deficit suffer from paraesthesia, anaesthesia or dysaesthesia of the lip, chin or buccal gingivae of the affected side, whilst those with LN deficit have altered sensation of the tongue with or without taste disturbance. A small portion of the affected population do not recover fully in the long term . Researchers have tried to identify the risk factors for neurosensory deficits in lower wisdom tooth surgery to minimize the risk of these morbidities. Many studies have been published but the results vary.

Evidence-based medicine provides better information for patient management. Integrating the best available evidence and the individual patient’s circumstances improves the quality of service delivered to the patient . In oral and maxillofacial surgery, evidence-based research is relatively scarce and there are few systematic reviews and literature review . This study aimed to identify all available relevant prospective studies in the literature relating to the risk factors for IDN and LN deficits in lower wisdom tooth surgery, to provide a literature review.

Materials and methods

Computer databases, including PubMed, Ovid and the Cochrane Library, were searched from the earliest available date to 8 June 2007. No language restrictions were applied. The electronic search was performed using the keywords: 1, third molar; 2, wisdom tooth; 3, inferior alveolar nerve; 4, inferior dental nerve; 5, lingual nerve; 6, trigeminal nerve; 7, nerve damage; 8, sensory disturbance; 9, sensory deficit; 10, sensory impairment; 11, nerve injury; 12, (1 OR 2) AND (3 OR 4 OR 5 OR 6 OR 7 OR 8 OR 9 OR 10 OR 11).

The abstracts were reviewed by two independent judges (LYY and LWK). Articles relevant to the study of wisdom tooth surgery and neurosensory deficit were selected. If there was inadequate information in the abstracts or the abstracts were missing, the articles were included in this round. Full articles were obtained for all those included in the first round. Any disagreements between the two judges were solved by consensus. If an agreement could not be reached, a third party (CLK) was consulted.

Further search were performed from the reference list of all the articles included in the first round. Articles relevant to the study of wisdom tooth surgery and neurosensory deficit were selected. Together with the articles obtained in the first round, all articles were evaluated. Two independent judges (LYY and TI) carried out independent evaluation of the articles entered this round, according to the following criteria: articles must be limited to wisdom tooth surgery; articles must specifically list the neurosensory deficit that the subjects experienced; articles must be randomized clinical trials, controlled clinical trials or prospective clinical studies. Articles had to fulfill all these criteria to enter the third round. Any disagreements between the two judges were solved by consensus. A third party (CLK) was consulted if an agreement could not be reached. Articles meeting the listed criteria were entered into the third round for evaluation.

Articles entering the third round were evaluated by two independent judges (LYY and TI) based on the following criteria. First, the articles must contain one or more of the following pieces of information about all the patients who underwent surgery: basic demographic data (mean age or gender of patients); tooth status (status of eruption, depth of impaction or pattern of impaction of the lower third molar); radiographic signs of the lower wisdom tooth root in relation to the IDN; intra-operative data (exposure of IDN, raising of lingual flap, surgical approach or instrument used); and the surgeons’ experience. Second, the articles must contain one or more pieces of information about whether the subjects covered by the first criterion suffered from postoperative neurosensory deficit.

Articles had to fulfill both criteria to be included in the final review and literature review. Any disagreements between the two judges were solved by consensus. A third party (CLK) was consulted if an agreement could not be reached.

The data were analysed statistically using GraphPad InStat 3.0, using t -tests to compare continuous data and χ 2 tests or Fisher’s exact tests to compare categorical data. A 5% level of significance was applied.


367 potential articles were found in Pubmed, an extra 20 articles in Ovid and an additional 11 articles in the Cochrane Library. The abstracts of these articles were screened and 112 articles were considered to be relevant to wisdom tooth surgery and neurosensory deficit, and were channeled into the second round search and evaluation.

12 articles were selected from the reference search of the 112 articles entering the first round. One submitted article from the authors’ centre was also included . 125 articles were evaluated by the two independent judges based on the three criteria listed in the second round evaluation. One article was not retrievable. 2 articles were found to be a double submission using the same data set. 77 articles did not fulfill one or more of the three criteria. 80 articles were excluded. 45 articles entered the evaluation ( Fig. 1 ).

Fig. 1

Of the 45 articles entering the third round of evaluation, 13 articles not fulfilling the criteria listed in this round were excluded. 32 articles were considered suitable for final review. 4 of these reported IDN deficits, 9 reported LN deficits and 19 reported both IDN and LN deficits. 7 of the 32 selected studies were randomized clinical trials and 25 were prospective clinical studies ( Table 1 ).

Table 1
Articles for the final review and the risk factors presented in these articles (n=32).
Ref. Authors Year Study design Deficit reported Risk factors 1 2 3 4 5 6 7 8 9 10 11
B ruce et al. 1980 Pros Both + + + +
R ood 1983 Pros Both + + +
M ason 1988 Pros LN +
M iddlehurst et al. 1988 RCT Both + + + +
O biechina 1990 Pros Both + + +
R ood and S hehab 1990 Pros IDN +
C armichael and M cGowan 1992 Pros Both + + +
R ood 1992 Pros Both + +
A bsi and S hepherd 1993 RCT Both + +
B londeau 1994 Pros Both + + + + + +
B erge and B øe 1994 Pros Both + +
G reenwood et al. 1994 Pros LN + +
R obinson and S mith 1996 RCT LN + +
B lack 1997 Pros Both + + + +
A ppiah-Anane and A ppiah Anane 1997 Pros LN + +
R obinson et al. 1999 Pros LN + + +
G argallo-Albiol et al. 2000 RCT LN + + +
V almaseda-Castellon et al. 2001 Pros IDN +
B ataineh 2001 Pros Both + + + + + +
G ulicher and G erlach 2001 Pros Both + + + + + + +
C hossegros et al. 2002 RCT LN + + + + + + +
M aegawa et al. 2003 Pros IDN + + +
P ogrel et al. 2004 Pros Both + + + +
P ogrel and G oldman 2004 Pros LN + + + +
T ay and G o 2004 Pros IDN + + + + +
B enediktsdóttir et al. 2004 Pros Both + + + +
B ell et al. 2004 Pros Both + + + + +
G omes et al. 2005 RCT LN + + + +
R enton et al. 2005 RCT Both + + +
J erjes et al. 2006 Pros Both + + +
B londeau and D aniel 2007 Pros Both + + + + + +
C heung et al. 2008 Pros Both + + + + + + + + +
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Feb 7, 2018 | Posted by in Oral and Maxillofacial Surgery | Comments Off on Risk factors of neurosensory deficits in lower third molar surgery: a literature review of prospective studies
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