| |
|
|
| Year : 2009 | Volume
: 20
| Issue : 4 | Page : 458-462 |
|
| Ultrasonographic evaluation of inflammatory swellings of buccal space |
|
|
K Srinivas1, KN Sumanth2, SS Chopra3
1 Department of Oral Medicine and Radiology, Oxford Dental College & Hospital, Bangalore, India
2 Department of Oral Medicine and Radiology, MCODS, KMC LHH Road, Hampankatta, Karnataka, India
3 Department of Oral Medicine and Radiology, Dental College & Hospital, Sriganganagar, India
Click here for correspondence address and email
| Date of Submission | 24-Jul-2007 |
| Date of Decision | 21-Nov-2007 |
| Date of Acceptance | 04-Dec-2007 |
| Date of Web Publication | 29-Jan-2010 |
|
|
 |
|
 Abstract | | |
Objectives : The main objective of the study was a) to differentiate cellulitis and abscess in buccal space region, b) to study the ultrasonographic anatomy of cheek region and c) to investigate the use of ultrasound in the diagnosis of inflammatory swellings of cheek region.
Patients and Methods : The study consisted of 25 patients with unilateral buccal space inflammatory swellings of odontogenic origin. The contra lateral side was used as control. Toshiba ultrasonographic device with a linear array transducer (5-8 MHz) was used. The areas of interest were scanned under both transverse and longitudinal sections and were interpreted by a single observer. The clinical diagnosis of cellulitis or abscess was confirmed by the absence or presence of pus respectively both sonographically and by aspiration. Also various anatomical structures present in buccal space were studied.
Results : Clinically 23(92%) were diagnosed as buccal space abscess and 2 (8%) were cellulitis. Ultrasonographically and therapeutically 24 (96%) were buccal space abscess and 1 (4%) was cellulits. The sensitivity of clinical criteria over ultrasonographic diagnosis was 96% with a specificity of 100%. Also the cheek thickness in males and females varied from 8.2 to 17.1mm with a mean of 11.6mm±2.1 (SD) and 8.2 mm to 14.2 mm with a mean of 11±1.8 (SD). The subcutaneous tissue appeared moderately echogenic, buccinator - highly echogenic, deep adipose tissue - less echogenic and parotid duct was appreciated as a thin hyperechogenic band crossing the buccinator muscle. Buccal space, masticator space and parotid space were appreciated.
Conclusion : This study supports the ultrasonographic method of imaging of orofacial inflammatory swellings with high sensitivity and specificity. This imaging modality can also help in aspiration of pus in different spaces. We have described the ultrasonographic anatomy of the above mentioned spaces which can help a beginner in this field. Keywords: Ultrasonography, imaging, buccal space, cellulitis
How to cite this article:
Srinivas K, Sumanth K N, Chopra S S. Ultrasonographic evaluation of inflammatory swellings of buccal space. Indian J Dent Res 2009;20:458-62 |
How to cite this URL:
Srinivas K, Sumanth K N, Chopra S S. Ultrasonographic evaluation of inflammatory swellings of buccal space. Indian J Dent Res [serial online] 2009 [cited 2023 Mar 30];20:458-62. Available from: https://www.ijdr.in/text.asp?2009/20/4/458/59454 |
For many years, ultrasonography has played a major role as a diagnostic tool in various medical fields. Only recently has it been used for maxillofacial imaging. It has still not found its place as a routine diagnostic aid in this field. [1] When one considers that the majority of structures and associated pathologies in the head and neck region lie only between 1 and 5 cm below the skin surface, it is not surprising that ultrasound is gaining in popularity in the field of head and neck imaging. [2]
Imaging of soft tissue infections has traditionally been a challenging and difficult task. The concept of fascial spaces is based on the knowledge of anatomists that all spaces exist only potentially, until fascia is separated by pus, blood, drain or surgeon's finger. In case of odontogenic infections, fascial spaces may become involved when the infection spreads deeply into the soft tissue rather than exiting superficially through oral and cutaneous routes. [3] In case of acute odontogenic infection, we need to know whether the inflammatory process is in a stage of abscess formation requiring primary evacuation of pus and administration of antibiotics, or a cellulitis that can generally be treated with antibiotics alone. [4] Since the examination of inflammatory facial swellings is largely restricted to clinical techniques of evaluation, such as palpation and the inflammatory processes leading to abscess formation is not defined in space and time, it is difficult to diagnose the stage of infection and to locate its exact anatomic location. CT and MRI can be used to diagnose these conditions. An alternative diagnostic tool that is widely available, relatively inexpensive (in imagiological terms) and non-invasive is ultrasonography. [4]
The buccal space is bordered medially by buccinator muscle, which attaches to the outer cortex of the maxillary alveolar ridge. It is tucked away between the maxillary alveolar ridge medially, the masticator space posteriorly and parotid space laterally. Anteriorly, the buccal space is separated from the subcutaneous tissues of the face by the plane formed by the superficial muscles of facial expression (greater and lesser zygomaticus muscles, risorius) and the investing fascia. The buccal space does not have complete fascial coverings that separate it from adjacent spaces. The lack of defined boundaries allows extensions of clinically overt and occult infections through the buccal space. Inferiorly, the buccal space blends imperceptibly with the submandibular space. The deep fat of buccal space joins into the fat of the postero-lateral portion of the masticator space (suprazygomatic masticator space, infratemporal fossa). This extension passes deep to the zygomatic arch and ascends superiorly and laterally to surround the coronoid process of mandible and the insertion of the temporalis muscles, which are part of the masticator space.
The contents of the buccal space are adipose tissue, buccinator muscle, lymph nodes, parotid duct, minor salivary gland tissue, facial vein, facial and buccal artery and buccal branch of the facial nerve.
The adipose tissue of deep buccal space is distinct from the fat within the anterior buccal space and subcutaneous tissue. The fat of the deep buccal space is a special form of adipose tissue known as 'syssarcoses'. This is likely the remnant of the succatory pad of infants that aids in muscular motion needed to open and close the mouth. [5]
The objectives of this clinical study were
- To study the ultrasonographic anatomy of the cheek region.
- To subject the inflammatory swellings of the buccal space to ultrasonographic examination before medical or surgical management.
- To investigate the use of ultrasound in the diagnosis of inflammatory swellings of cheek region.
| Patients and Methods | |  |
The study was conducted at Department of Oral Medicine and Radiology, P.M.N.M. Dental College and Hospital, Bagalkot and Shirur Maternity Home, Bagalkot. The study consisted of 25 patients suffering from inflammatory swellings of buccal space (unilateral) with normal contralateral buccal space taken as control.
The subjects were selected based on the following criteria:
- No age and sex bar.
- Patients suffering only from buccal space infection (unilateral), with normal contralateral buccal space and clinically diagnosed as either cellulitis or abscess due to odontogenic origin were included in the study.
- The diagnosis of buccal space infection, whether it is cellulitis or abscess was done according to the criteria given by Peterson Larry J. et al. [6] and the diagnosis was radiographically confirmed.
- Those patients who were willing to participate in the study were only included.
- Patients with pathologies other than cellulitis and abscess were excluded from the study.
- The contralateral buccal spaces of the patients with pathologies most likely to show ultrasonographic changes were excluded from the study.
The ECCOCEE diagnostic ultrasound system (Toshiba Corporation, Japan model No. SSA - 340A) and a linear array transducer (Toshiba Corporation, Japan model No. PLF- 805ST), which is a multi-frequency probe (5-8 MHz) was used. In the present study, 8 MHz probe was used for all the scans.
All sonographic examinations were performed in a darkened room and performed by single examiner. Patients positioning for sonographic examination was carried out according to methodology described by Ahuja and Rhodri. [2] The areas of interest were scanned under both transverse and longitudinal sections. For measurement of cheek thickness of the normal side, the transducer was placed transversely on an imaginary line drawn between corners of the mouth to the tragus of the ear for all patients.
The sonographic pictures were interpreted by a single observer according to the guidelines given by various authors. [1],[4],[7],[8],[9] Ultrasonographically, patients diagnosed as cellulitis were given appropriate antibiotic therapy, and for the patients diagnosed as suffering from abscess, pus was aspirated and patients were referred to Department of Oral and Maxillofacial Surgery for incision and drainage and antibiotic therapy. All the patients were called for follow-up after 5 days and the condition of the patients were evaluated.
| Results | | |
The study consisted of a total number of 25 patients with buccal space inflammatory swellings. The condition of the subjects was diagnosed clinically and ultrasonographically. The age of 25 patients who participated in the study ranged from 17 to 46 years and there were 13 males and 12 females in the study.
Clinical findings on the pathological side (buccal space)
On extraoral examination, on inspection, all 25 patients had swelling in the buccal space region. Thirteen (52%) had swelling on the right side and 12 (48%) on the left side of the face.
On intraoral examination, 9 patients had buccal space infection due to carious lesion involving either 16 or 17; 12 patients had buccal space infection due to carious lesion involving either 26 or 27, except one case, which had periodontal abscess in relation to 26 and 27; 1 patient had buccal space infection due to carious lesion involving 36 and 3 patients had buccal space infection due to carious lesion involving either 46 or 47. The diagnosis was confirmed by radiographic examination except for one case in which patient had periodontal abscess, as there is no pathgnomonic radiographic feature for periodontal abscess. Twenty three (92%) patients were diagnosed clinically as buccal space abscess, out of which 13 were males and 10 were females and 2 (8%) patients were diagnosed clinically as suffering from cellulitis and both of them were females.
Ultrasonographic findings of the control side (Buccal space)
The normal anatomical features appreciated ultrasonographically were subcutaneous tissue, buccinator muscle, parotid duct and deep adipose tissue. The subcutaneous tissue appeared as moderately echogenic, uniformly thick band followed by buccinator muscle, which appeared highly echogenic (but not hyperechoic). The buccinator muscle was identified ultrasonographically by asking the patient to blow his cheek and the increase in echogenicity confirmed the position of buccinator. Deep to the buccinator muscle, another band of echogenic area was observed, which was comparatively less echogenic than that of subcutaneous tissue, which was the special type of deep adipose tissue [Figure 1] and [Figure 2].
The thickness of the deep adipose tissue (Syssarcosis) was more in chubby cheeked patients when compared to normal flat cheeked patients [Figure 1] and [Figure 2]. The parotid duct was appreciated as a thin hyperechogenic band crossing the buccinator muscle, which could be appreciated clearly only in four cases. The masticator space which borders buccal space posteriorly was observed sonographically as echogenic area immediately behind the buccal space [Figure 3]. The parotid space that borders the buccal space laterally was observed lateral to buccal space on sonography with clear demarcating hyperechoic parotid capsule [Figure 4]. The zygomatic buttress and arch were observed as a well-defined hyperechoic area superior to buccal space. Skin, minor salivary glands, lymph nodes, facial vessels and nerves were not appreciated in this study.
Ultrasonographic findings of the pathology side (Buccal space)
Ultrasonographically there was increased distance from skin to oral mucosa on the pathology side in all cases. The following ultrasonographic observations were seen:
- Anatomical features namely subcutaneous tissue and buccinator muscle were well defined without any abnormal echo patterns in all cases.
- The integrity of subcutaneous tissue and/or muscle was lost in all cases [Figure 4].
- Except in one case all other 24 cases showed focal lesions with good definition.
- Out of these 24 cases with focal lesions, 1 (4.2%) was roughly oval in shape and rest of 23 (95.8%) were irregular in shape.
- The contents of the focal lesion in buccal space were either hypoechoic or anechoic. Thirteen (54.2%) cases had hypoechoic pattern of the lesion and 11 (45.8%) had anechoic pattern of the lesion [Figure 5]. All the 24 cases had acoustic accentuation indicative of presence of fluid.
- Mass effect was appreciated in 3 (12.5%) of cases and absent in 21 (87.5%) cases [Table 1].
| Discussion | | |
The diagnosis of cellulitis in orofacial region is a clinical one that requires urgent attention, as a fulminating course may occur, resulting in severe tissue destruction or life-threatening bacteremia. [9] Previous reports had indicated that ultrasonography is widely accepted non-invasive technique for imaging cellulitis, fascial space infections and abscess. [8]
The present study aids in confirming the diagnosis of cellulitis and abscess through sonographic imaging and also to study the ultrasonographic anatomy in the buccal space region. Buccal space was chosen because, for a beginner in ultrasound, it is difficult to study the spaces such as suprahyoid spaces where there are too many structures, and there is a difficulty of interpretation of images in such a situation. The discussion is written under three headings:
- Clinical findings of the pathology side.
- Ultrasonographic findings of the control side.
- Ultrasonographic findings of the pathology side.
Clinical findings of the pathology side (buccal space)
Clinically 23 (92%) patients were diagnosed as having buccal space abscess and 2 (8%) patients were diagnosed as having cellulitis involving the buccal space. Though 23 (92%) swellings did not have pointing surface as described clinically for a classical abscess, [10] because of the well-defined borders, soft consistency and presence of fluctuation, these cases were diagnosed as buccal space abscess.
As quoted by Rosenfield et al., [11] Fields and Dunn (1973) stated that collagen is considered major source of echogenicity in tissues. The supporting tissues are characterized by a bulk modulus that is 10,000 times that of surrounding tissues. Since collagen and other similar proteins form the fibrous skeleton of soft tissues, different organs would be expected to display different internal echo patterns based to some extent on their collagenous content.
The echogenicity of the various landmarks in decreasing order are,
- Parotid duct: Thin hyperechogenic band.
- Contracted buccinator: Highly echogenic.
- Relaxed buccinator: Less highly echogenic.
- Subcutaneous tissue: Moderately echogenic.
- Deep adipose tissue: Less echogenic.
The thickness of the deep adipose tissue was more in chubby cheeked individuals when compared to normal flat cheeked individuals. Thus the lessening of echogenicity of the deep adipose tissue indicates the decreased collagen content and may aid in plastic surgeries for reduction of chubbiness.
The location of parotid duct and its echogenicity can help in cases of sialodochitis and sialolithiasis as there will be increase in the echogenicity along the entire course of the duct or localized area, respectively.
The borders of the buccal space were identified anteriorly, medially, posteriorly, laterally and superiorly, which may aid in the definition of any lesion and spread of inflammation and malignancy adjacent to the buccal space.
The frequency used in the present study was 8 MHz and with this frequency, structures like skin, minor salivary glands, lymph nodes, facial vessels, nerves cannot be appreciated.Since we have not applied Doppler, facial vessels were not appreciated. Buccal lymph nodes may be present along with the afferent vessels, which drain the cheek region to submandibular lymph nodes; [12] since the control side was free from inflammation and infection, the lymph nodes were not visualized. Also it is not a regular anatomical feature [12] and hence was not appreciable in any of the cases studied.
Ultrasonographically, there was increased distance from skin to oral mucosa on the affected side, which denoted the third dimension of the swelling and could help in quantification of pus or inflammatory zone. The integrity of the subcutaneous tissue and/or muscle was lost in all the cases; proves the theoretical explanation that the enzymes of the bacteria break down the interstitial tissues which is similar to that of Chao Hsun - Chin et al. [9]
Thirteen (54.2%) of the 24 cases had hypoechoic pattern and 11 (45.8%) had anechoic pattern of the lesion indicative of consistency of pus. None of the cases showed isoechoic pattern. According to Loyer et al. [8] pus can be anechoic, hypoechoic and isoechoic, and if at all isoechoic patterns are seen, then gentle intermittent digital palpation or pressure applied with the transducer over an area of swelling can identify true echogenicity of the pus by inducing motion of the purulent content.
All the 24 cases had acoustic accentuation indicative of presence of fluid. According to various ultrasound experts, [13],[14] acoustic accentuation is a pathognomonic indicator for the presence of fluid.
Mass effect was appreciated in three cases. None of the studies have mentioned or discussed about the mass effect in inflammatory swellings of head and neck region. In abscess formation, pus accumulation tends to put pressure giving the surrounding tissues a curvaceous presentation on the ultrasound, this appearance is called mass effect. Among the three cases, which had mass effect none of them presented with any distinctive ultrasonographic findings to suggest the cause for the presence of mass effect; however, it could be explained by the fact that in these cases probably the quantity of pus was more [Table 1].
| Conclusion | | |
We have described the normal echogenicity of the anatomical structures in cheek region which can facilitate an inexperienced radiologist to identify the pathology by using ultrasound. However, further studies based on large samples with space infection in the maxillofacial region along with usage of color Doppler and high-frequency transducer needs to be undertaken, as they can alter the treatment approach for providing better patient care.
| Acknowledgment | | |
The authors sincerely thank Dr. Herenjal for his help by providing the ultrasonographic equipment for conducting the study. Also we thank our statistician, Mr. Sangam for his help.
| References | | |
| 1. | Siegert R. Ultrasonography of inflammatory soft tissue swellings of the head and neck. J Oral Maxillofac Surg 1987;45:842-6.  [PUBMED] [FULLTEXT] |
| 2. | Ahuja AT, Rhodri E, editors. Practical head and neck ultrasound. Hong Kong: GMM Publications; 1996. p. 1-32. |
| 3. | Struk DW, Munk PL, Lee MJ, Ho SG, Worsley DF. Imaging of soft tissue infections. Radiol Clin North Am 2001;39:277-303. [PUBMED] [FULLTEXT] |
| 4. | Peleg M, Heyman Z, Ardekian L, Taicher S. The use of ultrasonography as a diagnostic tool for superficial facial space infections. J Oral Maxillofac Surg 1998:56:1129-31. |
| 5. | Mukherji SK, Castillo M. A simplified approach to the spaces of the suprahyoid neck. Radiol Clin North Am 1998;36:761-79. [PUBMED] [FULLTEXT] |
| 6. | Peterson LJ, editor. Contemporary oral and maxillofacial surgery. 2 nd ed. Bangalore: Harcourt Brace and Company, Asia Pvt. Ltd; 1997. p. 414-25. |
| 7. | Leopold GR. Ultrasonography of superficially located structures. Radiol Clin North Am 1980;18:161-73. |
| 8. | Loyer EM, Kaur H, David CL, DuBrow R, Eftekhari FM. Importance of dynamic assessment of the soft tissues in the sonographic diagnosis of ecogenic superficial abscesses. J Ultrasound Med 1995;14:669-71. |
| 9. | Chao HC, Lin SJ, Huang YC, Lin TY. Sonographic evaluation of cellulitis in children. J Ultrasound Med 2000;19:743-9. |
| 10. | Cotran RS, Vinaykumar, Tucker C, editors. Robin's pathologic basis of disease. 6 th ed. Noida; W.B. Saunders Company: 2000. p. 75. |
| 11. | Rosenfield AT, Taylor KJ, Jaffe CC. Clinical applications of ultrasound tissue characterization. Radiol Clin North Am 1980;18:31-58. |
| 12. | Williams PL, Bannister LH, Berry MM, Collins P, Dyson M, Dussek JE, et al, editors. Gray's anatomy. 38 th ed., Edinburg: Churchill Livingstone; 2000. p. 75-90 and 1612. |
| 13. | Carol RM, Stephanie IW, Charbineau JW, editors. Diagnostic ultrasound. USA: Mosby Publications: 1991. p. 1-41. |
| 14. | Hagen-Ansert SL, editors. Textbook of diagnostic ultrasound V-I. 5 th ed. Philadelphia: C.V. Mosby Company; 2001. p. 3-15. |
Correspondence Address:
K N Sumanth
Department of Oral Medicine and Radiology, MCODS, KMC LHH Road, Hampankatta, Karnataka
India
 Source of Support: None, Conflict of Interest: None  | Check |
DOI: 10.4103/0970-9290.59454
[Figure 1], [Figure 2], [Figure 3], [Figure 4], [Figure 5]
[Table 1] |
|
| This article has been cited by | | 1 |
Evaluation of Efficacy of Ultrasonography as an Additional Diagnostic Tool for Deciding Management Protocol of Odontogenic Superficial Fascial Space Infections: A Prospective Clinical Study |
|
| Naiya Shah, Shital Patel, Taher Rupawala, Sanjay Makwana, Saloni Mansuri, Kruna Bhimani | | Journal of Maxillofacial and Oral Surgery. 2021; | | [Pubmed] | [DOI] | | | 2 |
Fascial space odontogenic infections: Ultrasonography as an alternative to magnetic resonance imaging |
|
| Sreenivasarao Ghali, Girish Katti, Syed Shahbaz, Parita K Chitroda, Anukriti V, Darshan Devang Divakar, Aftab Ahmed Khan, Sachin Naik, Abdulaziz A Al-Kheraif, Chitra Jhugroo | | World Journal of Clinical Cases. 2021; 9(3): 573 | | [Pubmed] | [DOI] | | | 3 |
Buccal Mucosa Assessed by Ultrasonography in Healthy Adults: Methodology and Determination of Normal Appearance |
|
| Yiqun Liu,Jiaan Zhu,Huijie Guo,Wenxue Li,Jianguo Li,Yehong Wang,Ariun Bilig,Xiuming Wang | | Ultrasound in Medicine & Biology. 2019; 45(5): 1297 | | [Pubmed] | [DOI] | | | 4 |
Buccal Mucosa Assessed by Ultrasonography in Healthy Adults: Methodology and Determination of Normal Appearance |
|
| Yiqun Liu,Jiaan Zhu,Huijie Guo,Wenxue Li,Jianguo Li,Yehong Wang,Ariun Bilig,Xiuming Wang | | Ultrasound in Medicine & Biology. 2019; 45(5): 1297 | | [Pubmed] | [DOI] | | | 5 |
Updated anatomy of the buccal space and its implications for plastic, reconstructive and aesthetic procedures |
|
| Thilo L. Schenck,Konstantin C. Koban,Alexander Schlattau,Konstantin Frank,Anthony P. Sclafani,Riccardo E. Giunta,Malcolm Z. Roth,Alexander Gaggl,Robert H. Gotkin,Sebastian Cotofana | | Journal of Plastic, Reconstructive & Aesthetic Surgery. 2018; 71(2): 162 | | [Pubmed] | [DOI] | | | 6 |
Updated anatomy of the buccal space and its implications for plastic, reconstructive and aesthetic procedures |
|
| Thilo L. Schenck,Konstantin C. Koban,Alexander Schlattau,Konstantin Frank,Anthony P. Sclafani,Riccardo E. Giunta,Malcolm Z. Roth,Alexander Gaggl,Robert H. Gotkin,Sebastian Cotofana | | Journal of Plastic, Reconstructive & Aesthetic Surgery. 2018; 71(2): 162 | | [Pubmed] | [DOI] | | | 7 |
Utility of ultrasonography as an auxiliary method in the diagnosis of lesions in oral soft tissues |
|
| Felipe Leal Martins,Fernanda Gonçalves Salum,Karen Cherubini,Maria Antonia Zancanaro de Figueiredo | | Oral Radiology. 2015; | | [Pubmed] | [DOI] | | | 8 |
Contribution of Ultrasonography to the Diagnosis of Submucosal and Subcutaneous Nodular Lesions of the Oral and Maxillofacial Region: Analysis of Cases |
|
| Felipe Leal Martins,Fernanda Gonçalves Salum,Karen Cherubini,Roberto Oliveira,Maria Antonia Zancanaro de Figueiredo | | Journal of Maxillofacial and Oral Surgery. 2014; | | [Pubmed] | [DOI] | | | 9 |
Ultrasonographic evaluation of oral submucous fibrosis in habitual areca nut chewers |
|
| C Krithika,S Ramanathan,D Koteeswaran,C Sridhar,J Satheesh Krishna,M P Shiva Shankar | | Dentomaxillofacial Radiology. 2013; 42(9): 20120319 | | [Pubmed] | [DOI] | | | 10 |
To evaluate the efficacy of ultrasonography compared to clinical diagnosis, radiography and histopathological findings in the diagnosis of maxillofacial swellings |
|
| Pallagatti, S. and Sheikh, S. and Puri, N. and Mittal, A. and Singh, B. | | European Journal of Radiology. 2012; 81(8): 1821-1827 | | [Pubmed] | | | 11 |
To evaluate the efficacy of ultrasonography compared to clinical diagnosis, radiography and histopathological findings in the diagnosis of maxillofacial swellings |
|
| Shambulingappa Pallagatti,Soheyl Sheikh,Nidhi Puri,Amit Mittal,Balwinder Singh | | European Journal of Radiology. 2012; 81(8): 1821 | | [Pubmed] | [DOI] | | | 12 |
Evaluation of oral submucous fibrosis using ultrasonographic technique: A new diagnostic tool |
|
| Manjunath, K., Rajaram, P.C., Saraswathi, T.R., Sivapathasundharam, B., Sabarinath, B., Koteeswaran, D., Krithika, C. | | Indian Journal of Dental Research. 2011; 22(4): 530-536 | | [Pubmed] | |
|
|
|
|
|
|
|
|
|
|
|
|
| Article Access Statistics | | | Viewed | 10577 | | | Printed | 551 | | | Emailed | 6 | | | PDF Downloaded | 539 | | | Comments | [Add] | | | Cited by others | 12 | | |
|
|
Users online:
