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 Table of Contents  
ORIGINAL ARTICLE
Year : 2017  |  Volume : 31  |  Issue : 2  |  Page : 94-99

Clinical profile of patients with trigeminal neuralgia visiting a dental hospital: A prospective study


1 Oral Medicine and Radiology, Faculty of Dentistry, Jamia Millia Islamia, New Delhi, India
2 Department of CTVS, RIMS, Ranchi, Jharkhand, India
3 Department of Oral Pathology, Vananchal Dental College, Garhwa, Jharkhand, India
4 Oral Medicine and Radiology, SDM College of Dental Sciences and Hospital, Dharwad, Karnataka, India

Date of Web Publication6-Sep-2017

Correspondence Address:
Arpita Rai
Faculty of Dentistry, Jamia Millia Islamia, New Delhi
India
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Source of Support: None, Conflict of Interest: None


DOI: 10.4103/ijpn.ijpn_44_17

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  Abstract 

Aims: To assess the clinical characteristics and parameters of trigeminal neuralgia (TN) in a group of South Indian population. Study Design: Records of sixty patients with TN were reviewed prospectively for patient demographics, characteristics of the pain, and treatment modalities. Results: Of the sixty patients, 55% were male and 45% were female. The peak incidence was in the age range of 55–64 years. Pain occurred equally on the right and left side of the face. The maxillary division of the trigeminal nerve was the most frequently affected (40%), followed by mandibular division (35%) and the combined maxillary and mandibular division alone (25%). The majority of patients described their attack as a shock like (78.33%) and of spontaneous onset (86.67%). Conclusion: In the present study, TN affected males more than females, and this disorder occurred most frequently in patients aged 55–64 years. Comparison of the pain characteristics between different age groups and gender is useful for the management of these patients.

Keywords: Clinical profile, lancinating pain, orofacial pain, trigeminal neuralgia


How to cite this article:
Rai A, Kumar A, Chandra A, Naikmasur V, Abraham L. Clinical profile of patients with trigeminal neuralgia visiting a dental hospital: A prospective study. Indian J Pain 2017;31:94-9

How to cite this URL:
Rai A, Kumar A, Chandra A, Naikmasur V, Abraham L. Clinical profile of patients with trigeminal neuralgia visiting a dental hospital: A prospective study. Indian J Pain [serial online] 2017 [cited 2017 Sep 26];31:94-9. Available from: http://www.indianjpain.org/text.asp?2017/31/2/94/214125


  Introduction Top


Trigeminal neuralgia (TN) is a paroxysmal shock-like neuropathic pain that results in sudden, usually unilateral, severe, short, stabbing, and recurrent pains in the distribution of one or more branches of the trigeminal nerve, often set off by light stimuli in a trigger zone.[1]

According to the International Headache Society (IHS), classical TN is defined as “a unilateral disorder characterized by brief electric shock-like pains, abrupt in onset and termination, limited to the distribution of one or more divisions of the trigeminal nerve.”[2]

The attacks are initiated by the physical stimulation of specific areas, the so-called trigger points or zones, ipsilateral to the pain, but can be in the same or a different division of the trigeminal nerve.[3],[4] The provoking factors include chewing, speaking, brushing teeth, washing, and touching the face.[1],[4] Wind and cold water may also trigger an attack. In a recent study, most trigger zones were predominantly reported in the perioral and nasal region, and the frequent maneuvers for provocation of paroxysmal pain were gentle touching of the face (79%) and talking (54%).[5] The most common division(s) of the trigeminal nerve involved with pain was/were the maxillary and/or mandibular division(s).[4],[6],[7],[8],[9]

The attacks of pain are usually accompanied by involuntary contractions (tics) of the facial muscles on the affected side. For that reason, the term “tic douloureux” (painful contraction) has also been used for TN.[10] It causes severe compromise of the oral hygiene, habitual tasks, and quality of life, and the patients often get depressed and desperate.[11],[12]

The etiology of TN remains unknown. Several theories have been proposed including traumatic compression of the trigeminal nerve by neoplasms or vascular anomalies, herpetic infection, and demyelinating conditions.[10] Compression of the trigeminal nerve in the root entry zone in the posterior fossa by a blood vessel that results in nerve injury is considered to be a major causative factor.[13],[14],[15],[16],[17] The disorder is more common in women and mostly affects hypertensive patients and patients older than 50 years of age.[18] In most patients, TN affects only one side of the face and the right side is affected more frequently than the left.[3],[10]

There may be no visible neurological deficits in the clinical examination of the patients, and thus, the characteristics of the pain and response to carbamazepine are important in the diagnosis of the illness. TN can be treated both medically and surgically. If carbamazepine, baclofen, and phenytoin are not effective as medicinal treatments, surgical procedures are applied.[19]

Although the clinical profile of TN patients is relatively known, the data regarding South Indian population are not reported previously. Furthermore, very few studies have reported the clinical characteristics of TN among patients reporting to a dental college. The objective of the present study was to analyze the clinical characteristics of TN in a group of South Indian patients based on their age distribution and gender and compare the findings with those of other studies.


  Materials and Methods Top


A prospective study was conducted on the patients reporting to the Department of Oral Medicine and Radiology after taking approval from the ethics committee of the institute. Informed written consent was obtained from each patient.

The inclusion criteria for the study involved the patients who had history and clinical presentation consistent with IHS criteria for TN. All the patients were informed about the study, and the patients who were not willing to participate in the study had been excluded. After convenient sampling, finally, sixty TN patients who were willing to participate and with adequate data for inclusion were selected for the study. The sample size for the present study was decided based on previous study on similar topic.[2] The selected patients were diagnosed with TN for the first time. In case of doubtful clinical presentation, pharmacotherapy with test dose of carbamazepine was given. Patients responsive to the test dose were included from the study.

After obtaining their demographic data (name, age, gender, and address), all selected patients were interviewed for the history of TN, using a structured questionnaire. It included side of the face involved, trigeminal division involved, and radiation of pain – within the division/outside the division/outside face. Severity of pain was recorded on visual analog scale. Quality of pain was assessed by McGill's pain questionnaire.[20] Onset of pain as acute spontaneous onset or correlation with dental treatment or disease was also recorded. Periodicity of pain mainly frequency of episodes, duration of each episode, and duration of refractory period along with provoking, relieving, and associated factors were assessed. A standardized head and neck examination was performed by the trained personnel specialized in oral medicine for assessing the trigger points, and sensory testing in the distribution of trigeminal nerve was done. Necessary radiographic investigations were used to rule out all potential dental and bony pathologies.

The different clinical parameters were assessed in males and females and various age groups (35–44, 45–54, 55–64, 65–74, and ≥75 years) separately under the following headings: side of face involved, division of nerve, radiation of pain, character of pain, and onset of pain.

The data obtained were tabulated and subjected to statistical analysis. The statistical tests used were mean and standard deviation and the intervals of confidence and proportions. The Chi-square test was used to compare the data between the samples, and the level of significance was of 5%. The t-test was used to compare means between the samples.


  Statistics and Results Top


A total of sixty patients were included in the study, including 33 males (55%) and 27 females (45%). The age range of males was between 35 and 84 years with a mean of 58.97 years, and for females, it was between 37 and 85 years with a mean of 59.96 years. The average age of all the patients was 59.41 years [Table 1].
Table 1: Age and sex of patients

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Both right and left sides were equally involved, i.e., in thirty patients, right side of the face was involved, while in thirty patients, left side of the face was affected. Left side was more commonly involved in females (16 patients) while right side was more commonly involved in males (19 patients). However, the difference was not statistically significant (P = 0.194) [Table 2].
Table 2: Correlation between clinical characteristics and gender of the patient

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According to age distribution, it was found that left side was more affected in 55–64 and 65–74 years' age group patients. On the other hand, right side was more commonly affected in 35–44, 65–74, and ≥75 years' age group patients. The results were found to be statistically significant (P = 0.049) [Table 3].
Table 3: Correlation between clinical characteristics and age of the patient

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Regarding the division of trigeminal nerve involved (including both the right and left sides), it was found that maxillary (V2) and mandibular (V3) divisions were involved in 24 (40%) and 21 (35%) patients, respectively, while in remaining 15 (25%) patients, both V2 and V3 nerves were involved [Table 2].

V2 division was more commonly involved in males (16 patients) while V3 was almost equally involved in males and females. The involvement of both V2 and V3 nerves was more common in females (nine patients). However, the difference was not statistically significant (P = 0.260) [Table 2].

According to age distribution, it was found that both V2 and V3 nerves are commonly involved in 55–64 and 65–74 years' age group patients. However, the results were not found to be statistically significant (P = 0.238) [Table 3] and [Figure 1].
Figure 1: Correlation of clinical parameters at different age groups

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The assessment of radiation of pain showed that in 30 cases (50%), it was within the division, and in the rest 30 (50%) cases, it was outside the division [Table 2]. Within the division, it was found to be more common in females (17 patients), while that outside of the division, it was more common in males (20 patients). However, the results were not found to be statistically significant (P = 0.069) [Table 2].

The assessment of radiation of pain in different age groups showed that most of the patients in both within the division and outside the division were in the 55–64 and 65–74 years' age group patients with no statistically significant difference (P = 0.947) [Table 3].

The character or quality of pain analyzed by McGill's pain questionnaire showed that most (47) of the patients (78.33%) experienced shock-like pain while 11 patients (18.33%) felt burning, lancinating type of pain. Only 2 patients (3.33%) felt throbbing type of pain. Almost all the males (30 patients) and most of the females (17 patients) felt shock-like pain. The results showed a highly significant difference among the groups (P = 0.002) [Table 2].

On the basis of age distribution, it was found that all age group patients mostly had shock-like pain and patients in 55–64 and 65–74 years' age group most commonly experienced this. Nevertheless, the results were not found to be statistically significant (P = 0.140) [Table 3].

The onset of pain was evaluated under two categories, i.e., acute spontaneous onset and correlation with dental treatment or disease. It was observed that maximum (52) patients (86.67%) had acute spontaneous onset of pain as compared to only 8 patients (13.33%) whose onset of pain correlated with dental treatment or disease. Both males and females were almost equally involved with no statistically significant difference (P = 0.760) [Table 2].

All age group patients mostly felt acute spontaneous onset of pain and maximum patients were in 55–64, 65–74, and ≥75 years' age group. The results were not statistically significant (P = 0.211) [Table 3].


  Discussion Top


TN is a rare excruciating disease with long-term treatment and frequent neurosurgical indication.[21] The first full account of TN was published in 1773 when John Fothergill presented a paper to the Medical Society of London. He described the typical features of the condition in detail, including paroxysms of unilateral facial pain, evoked by eating, speaking or touch, starting and ending abruptly, and associated with anxiety.[22]

The present study determined the general clinical characteristics and parameters of sixty TN patients in a South Indian population which were finally included for the study after evaluation.

Of total 60 patients, 33 were male (55%) and 27 were female (45%). However, in other studies, it has been found that TN is more frequent in female patients.[3],[4],[5],[6],[7],[18],[21],[23],[24] The difference may be due to the willingness of the patient to participate in the study and to be fit in the inclusion criteria as this was a prospective study.

The average age of all the patients was 59.41 years in the present study, with 58.97 years for males and 59.96 years for females. This is similar to the observations of other studies which also shows that TN is more common in the elderly,[24] with a mean age of 62.5 years,[21] and mostly affects patients between of 50 and 70 years of age.[4],[7],[18],[24],[25]

Regarding the side of the face involved, in most of the studies, it has been observed that the right side of the face was affected more frequently than the left side.[6],[7],[21],[24],[26] However, they have not compared the affected side of the face between the different age groups and among the genders separately.

In the present study, both right and left sides were equally involved, i.e., in 50% (30) patients, each side was affected. Among the females, left side was more commonly involved, i.e., in 59.26% (16) patients, and among the males, right side was more commonly involved, i.e., in 57.57% (19) patients. However, the difference was not statistically significant (P = 0.194).

According to age distribution, it was found that left side was more affected in 55–64 and 65–74 years' age group patients with 40% (12) patients alone in 55–64 years' age group. On the other hand, right side was more commonly affected in 35–44, 65–74, and ≥75 years' age group patients with 30% (9) patients alone in 35–44 years' age group. The results were found to be statistically significant (P = 0.049).

The study shows that younger age group patients are also affected by TN although the numbers are less as compared to older patients. This may be due to the tendency of increase in the number of hypertensive patients in younger age group, these days.

Regarding the division of trigeminal nerve involved (including both the right and left sides), it was found that maxillary (V2) and mandibular (V3) divisions were involved in 24 (40%) and 21 (35%) patients, respectively, while in remaining 15 (25%) patients, both V2 and V3 nerves were involved.

The results are consistent with the studies of Katusic et al.,[6] Barker et al.,[8] and Dia Tine et al.,[9] who reported that the most affected branch was the maxillary division (V2). On the other hand, Loh et al.[7] and Jainkittivong et al.[24] found that the mandibular division (V3) of the trigeminal nerve was the most frequently involved branch. However, all investigators had same observation that the combinations of two or three divisions were less common, similar to the present study.[6],[8],[21]

While comparing the division of nerve involved among the genders and between the different age groups separately, it was observed that V2 division was involved in 48.48% males (16 patients) while V3 was almost equally involved in males and females, i.e., 33.33% and 37.04% patients, respectively. The involvement of both V2 and V3 nerves was more common in females, i.e., 33.33% (9 patients) as compared to males, i.e., 18.18% (6 patients). However, the difference was not statistically significant (P = 0.260).

Similarly, according to age distribution, it was found that both V2 and V3 the nerves are commonly involved in 55–64 and 65–74 years' age group patients, respectively. However, the results were not found to be statistically significant (P = 0.238).

The assessment of radiation of pain showed that in 30 cases (50%), it was within the division, and in the rest 30 (50%) cases, it was outside the division. Within the division, it was found to be more common in females (17 patients) (62.96%), while that outside of the division, it was more common in males (20 patients) (60.61%). However, the results were not found to be statistically significant (P = 0.069).

The assessment of radiation of pain in different age groups showed that most of the patients in both within the division and outside the division were in the 55–64 and 65–74 years' age group patients with no statistically significant difference (P = 0.947), respectively.

TN remains a clinical diagnosis depended on a history of sudden shooting or stabbing pain, coming as solitary sensations or paroxysms and separated by pain-free intervals. Optimally, it is the patient who volunteers this description. However, many patients with facial pain have considerable difficulty in finding precise expressions to convey the characteristics of their symptoms. In such a case, the interviewer may suggest descriptive words with a little prompting as possible.[12] In this regard, the McGill's pain questionnaire has been shown to be useful in differentiating a group of TN patients from those with other facial pains.[20]

In the present study, the character or quality of pain analyzed by McGill's pain questionnaire showed that most of the patients, i.e., 47 patients (78.33%), experienced shock-like pain while 11 patients (18.33%) felt burning, lancinating type of pain. Only 2 patients (3.33%) felt throbbing type of pain. Almost all the males, i.e., 30 patients (90.91%), and most of the females, i.e., 17 patients (62.96%), felt shock-like pain. The results showed a highly significant difference among the groups (P = 0.002).

On the basis of age distribution, it was found that all age group patients mostly had shock-like pain and patients in 55–64 and 65–74 years' age group most commonly experienced this. Nevertheless, the results were not found to be statistically significant (P = 0.140).

However, Jainkittivong et al.[24] in their study found that most patients described their attack as sharp pain (77.6%). The other pain descriptors included electric shock-like (19.1%), stabbing (9.6%), numbness (6.9%), throbbing (6.4%), and burning (4.2%).[22] In the present study McGill's pain questionnaire had been followed and the patient had to select among the only three characteristics of pain, i.e., burning/lancinating, shock-like and throbbing type. There was no category of sharp pain. In the study by Jainkittivong et al., patient voluntarily described their character of pain. Hence, there may be nonuniformity in the terminology of pain description.

The pain of TN is sometimes falsely attributed to a dental origin.[27] Therefore, serious caution should be taken in cases where TN may be perceived initially as an episodic toothache. As odontalgia can be relieved by local anesthesia, dentists can easily rule out pain of odontogenic origin.[24]

In the present study, the onset of pain was evaluated under two categories, i.e., acute spontaneous onset and correlation with dental treatment or disease. It was observed that maximum (52) patients (86.67%) felt acute spontaneous onset of pain as compared to only 8 patients (13.33%) whose onset of pain correlated with dental treatment or disease. Both males (87.88%) and females (85.19%) were almost equally involved in acute spontaneous onset with no statistically significant difference (P = 0.760).

All age group patients mostly felt acute spontaneous onset of pain and maximum patients were in 55–64, 65–74, and ≥75 years' age group. The results were not statistically significant (P = 0.211).

The results are consistent with studies of Zakrzewska [1] and Loeser.[4] These authors reported that majority of the patients in their study observed that their pain was triggered spontaneously by any physical stimuli and not due to dental treatment or disease. As a result, patients may avoid the stimuli and abstain from routine dental hygiene procedures.

Furthermore, Türp and Gobetti [28] and Jainkittivong et al.[24] described that many patients with TN have lost teeth because of unnecessary extractions. Both patients and dentists have been misled into thinking that the pain was odontogenic in origin, and many such symptomatic teeth have been lost because of this common misdiagnosis. Sometimes, the dentists explain that the pain might not be relieved by extraction of the symptomatic teeth, even then several patients insisted on having their teeth removed.[24]


  Conclusion Top


The present study determined the general clinical characteristics and parameters of sixty TN patients in a South Indian population. In the present study, TN affected males more than females, and this disorder occurred most frequently in patients aged 55–64 years. The major limitation of the present study is small sample size. It is recommended that further research based on data collected from multicenter larger sample would help explain the nature of this debilitating condition. As most of the pain symptoms were initiated in the oral cavity, most patients with TN were initially seen by dentists. To avoid maltreatment, dentists should be knowledgeable about the nature and clinical characteristics of TN. In questionable cases, the patient should be referred to specialists in oral medicine or orofacial pain.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.

 
  References Top

1.
Zakrzewska JM. Trigeminal neuralgia and facial pain. Semin Pain Med 2004;2:76-84.  Back to cited text no. 1
    
2.
Teruel A, Ram S, Kumar SK, Hariri S, Clark GT. Prevalence of hypertension in patients with trigeminal neuralgia. J Headache Pain 2009;10:199-201.  Back to cited text no. 2
[PUBMED]    
3.
Türp JC, Gobetti JP. Trigeminal neuralgia versus atypical facial pain. A review of the literature and case report. Oral Surg Oral Med Oral Pathol Oral Radiol Endod 1996;81:424-32.  Back to cited text no. 3
    
4.
Loeser JD. Tic douloureux. Pain Res Manag 2001;6:156-65.  Back to cited text no. 4
[PUBMED]    
5.
Di Stefano G, Maarbjerg S, Nurmikko T, Truini A, Cruccu G. Triggering trigeminal neuralgia. Cephalalgia 2017:333102417721677. doi: 10.1177/0333102417721677.  Back to cited text no. 5
[PUBMED]    
6.
Katusic S, Beard CM, Bergstralh E, Kurland LT. Incidence and clinical features of trigeminal neuralgia, Rochester, Minnesota, 1945-1984. Ann Neurol 1990;27:89-95.  Back to cited text no. 6
[PUBMED]    
7.
Loh HS, Ling SY, Shanmuhasuntharam P, Zain R, Yeo JF, Khoo SP. Trigeminal neuralgia. A retrospective survey of a sample of patients in Singapore and Malaysia. Aust Dent J 1998;43:188-91.  Back to cited text no. 7
[PUBMED]    
8.
Barker FG 2nd, Jannetta PJ, Bissonette DJ, Larkins MV, Jho HD. The long-term outcome of microvascular decompression for trigeminal neuralgia. N Engl J Med 1996;334:1077-83.  Back to cited text no. 8
    
9.
Dia Tine S, Tamba B, Gassama BB, Niang P, Dia L, Kébé Ndèye F, et al. Clinical and therapeutic aspects of trigeminal neuralgia. Apropos of 27 cases treated at the General Hospital of Grand-Yoffin Dakar. Odontostomatol Trop 2009;32:5-12.  Back to cited text no. 9
    
10.
Bagheri SC, Farhidvash F, Perciaccante VJ. Diagnosis and treatment of patients with trigeminal neuralgia. J Am Dent Assoc 2004;135:1713-7.  Back to cited text no. 10
[PUBMED]    
11.
Rothman KJ, Monson RR. Epidemiology of trigeminal neuralgia. J Chronic Dis 1973;26:3-12.  Back to cited text no. 11
[PUBMED]    
12.
Patterson CW, Copeland JS. Trigeminal neuralgia – A dental diagnosis challenge. Northwest Dent 1999;78:19-24.  Back to cited text no. 12
    
13.
Nurmikko TJ, Eldridge PR. Trigeminal neuralgia – Pathophysiology, diagnosis and current treatment. Br J Anaesth 2001;87:117-32.  Back to cited text no. 13
[PUBMED]    
14.
Love S, Coakham HB. Trigeminal neuralgia: Pathology and pathogenesis. Brain 2001;124:2347-60.  Back to cited text no. 14
[PUBMED]    
15.
Devor M, Amir R, Rappaport ZH. Pathophysiology of trigeminal neuralgia: The ignition hypothesis. Clin J Pain 2002;18:4-13.  Back to cited text no. 15
[PUBMED]    
16.
Lewis MA, Sankar V, De Laat A, Benoliel R. Management of neuropathic orofacial pain. Oral Surg Oral Med Oral Pathol Oral Radiol Endod 2007;103 Suppl32.e1-24.  Back to cited text no. 16
    
17.
Alshukry A, Salburgo F, Jaloux L, Lavieille JP, Montava M. Trigeminal neuralgia (TN): A descriptive literature analysis on the diagnosis and management modalities. J Stomatol Oral Maxillofac Surg 2017. pii: S2468-7855(17)30109-X.  Back to cited text no. 17
    
18.
Ecker AD. The cause of trigeminal neuralgia. Med Hypotheses 2004;62:1023.  Back to cited text no. 18
[PUBMED]    
19.
Abdeen K, Kato Y, Kiya N, Yoshida K, Kanno T. Neuroendoscopy in microvascular decompression for trigeminal neuralgia and hemifacial spasm: Technical note. Neurol Res 2000;22:522-6.  Back to cited text no. 19
[PUBMED]    
20.
Melzack R, Terrence C, Fromm G, Amsel R. Trigeminal neuralgia and atypical facial pain: Use of the McGill pain questionnaire for discrimination and diagnosis. Pain 1986;27:297-302.  Back to cited text no. 20
    
21.
Siqueira SR, Teixeira MJ, Siqueira JT. Clinical characteristics of patients with trigeminal neuralgia referred to neurosurgery. Eur J Dent 2009;3:207-12.  Back to cited text no. 21
[PUBMED]    
22.
Rose FC. Trigeminal neuralgia. Arch Neurol 1999;56:1163-4.  Back to cited text no. 22
[PUBMED]    
23.
de Siqueira SR, da Nóbrega JC, Teixeira MJ, de Siqueira JT. Masticatory problems after balloon compression for trigeminal neuralgia: A longitudinal study. J Oral Rehabil 2007;34:88-96.  Back to cited text no. 23
    
24.
Jainkittivong A, Aneksuk V, Langlais RP. Trigeminal neuralgia: A retrospective study of 188 Thai cases. Gerodontology 2012;29:e611-7.  Back to cited text no. 24
[PUBMED]    
25.
Darlow LA, Brooks ML, Quinn PD. Magnetic resonance imaging in the diagnosis of trigeminal neuralgia. J Oral Maxillofac Surg 1992;50:621-6.  Back to cited text no. 25
[PUBMED]    
26.
Neto HS, Camilli JA, Marques MJ. Trigeminal neuralgia is caused by maxillary and mandibular nerve entrapment: Greater incidence of right-sided facial symptoms is due to the foramen rotundum and foramen ovale being narrower on the right side of the cranium. Med Hypotheses 2005;65:1179-82.  Back to cited text no. 26
[PUBMED]    
27.
Law AS, Lilly JP. Trigeminal neuralgia mimicking odontogenic pain. A report of two cases. Oral Surg Oral Med Oral Pathol Oral Radiol Endod 1995;80:96-100.  Back to cited text no. 27
[PUBMED]    
28.
Türp JC, Gobetti JP. Trigeminal neuralgia – An update. Compend Contin Educ Dent 2000;21:279-82, 284, 287.  Back to cited text no. 28
    


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