|Year : 2019 | Volume
| Issue : 2 | Page : 98-104
Ultrasonography – A boon in dentistry
Abhijeet Alok1, Shivani Singh2, Mallika Kishore3, Anjani Kumar Shukla4
1 Department of Oral Medicine and Radiology, Sarjug Dental College and Hospital, Darbhanga, Bihar, India
2 Department of Public Health Dentistry, Dr. B. R. Ambedkar Institute of Dental Sciences and Hospital, Patna, Bihar, India
3 Department of Oral Medicine and Radiology, Inderprastha Dental College and Hospital, Ghaziabad, Uttar Pradesh, India
4 Department of Oral Medicine and Radiology, Dental Institute, Rajendra Institute of Medical Sciences, Ranchi, Jharkhand, India
|Date of Web Publication||9-Jul-2019|
Dr. Abhijeet Alok
S/O Dr. I. D.Singh, H/O Mr. R. K. Safi, Road No. 2 East, Ayachigram Colony, Near Bairia Bus Stand, Near Bank of India, P.O-M.I.T, Muzaffarpur - 842 003, Bihar
In modern times, advanced diagnostic imaging techniques in oral and maxillofacial radiology mainly involve computed tomography (CT), cone-beam CT (CBCT), magnetic resonance imaging, nuclear medicine, ultrasonography (USG), xeroradiography, and arthrography to name a few. From the time of its discovery, USG has been used in the field of medicine for the diagnosis of lesions as well as for remedial purpose. USG is a technique based on sound waves that acquire image in real time without the use of ionizing radiation. USG is more diagnostic for soft-tissue lesions than hard-tissue lesions. This article reviews the applications of ultrasound imaging in dentistry.
Keywords: Dentistry, echoes, high frequency, salivary gland disease, ultrasound imaging
|How to cite this article:|
Alok A, Singh S, Kishore M, Shukla AK. Ultrasonography – A boon in dentistry. SRM J Res Dent Sci 2019;10:98-104
| Introduction|| |
Various imaging techniques play an indispensable part in the identification, recognition, and discovery of lesions in the oral and maxillofacial region. Revolution occurred in the field of imaging with the introduction of techniques such as ultrasonography (USG), computed tomography (CT), and magnetic resonance imaging (MRI), which has reduced therapeutic dilemma. Advantages such as utilization of harmless nonionizing radiation, wide availability, ease of use, inexpensive, and nonproduction of artifacts due to metallic restorations make USG score over the other imaging modalities. USG permits echoes to be processed at a sufficiently rapid rate to allow perception of motion; this is referred to as real-time imaging.
USG is a noninvasive investigation that uses very high-frequency pulsed ultrasound beam. USG has seen a lot of changes from two- to three-dimensional visualization in the evaluation and detection of diseases.
The use of contrast medium over the years in USG has helped radiologists or clinicians in the assessment of blood flow and its echogenecity more accurately. Ultrasound imaging has a promising future as a hard- and soft-tissue diagnostic tool in all dental specialties.,
| History of Ultrasonography in Dentistry|| |
In the late 1800s, Jacques and Pierre Curie observed high-frequency sound waves when certain crystals were subjected to an alternating current at their resonant frequency. In the year 1926, Paul Langevin was the first to report the biological effects of ultrasound after observing the violent and fatal reaction of fish to strong ultrasound fields. Initially, majority of researchers concentrated their research more on the diagnostic purpose of ultrasound rather than on its therapeutic application. However, in the late 1940s, the therapeutic use of USG was found. USG was used to treat chronic osteomyelitis, osteoradionecrosis, and a variety of other infectious conditions. In the following year in 1952, various researchers found that USG can enhance callus formation in healing bone. USG does not disturb the structural integrity of the healing bone. Further research work was carried out on the application of USG in dentistry. It was found in the year 1955 that USG can remove plaque and calculus from the human teeth, and it can be further used to treat disorders of the temporomandibular joint (TMJ). With time, more studies took place on USG and its mechanism of action. As clinicians came to know about its physiological and biological effects on tissues, the role of USG in bone repair began to attract more attention in the 1980s.
In the 1990s, many researches were published regarding the potential therapeutic effects of USG on maxillofacial bones. The role of USG has been found in various studies over the years in increasing the likelihood of successful implantation, diagnosis of precancerous lesion and conditions, swellings in the maxillofacial region, lymph node metastases, etc.,,
| Physiological Effect of Ultrasound|| |
In order to fully appreciate the role of USG in dentistry, it is important to understand the biological effects of USG on hard and soft tissues. Ultrasound is an acoustic pressure wave which passes through tissue and may cause changes in the biological system due to heat, acoustic microstreaming, radiation forces, etc., As USG wave passes through the tissues, vibrations occur which in turn give biological signals to cells. In order to fully appreciate the role of USG in dentistry, it is important to understand the biological effects of USG on hard and soft tissues. USG may cause thermal and nonthermal effects. The thermal effects of USG result in increase in tissue extensibility and also increased vascularity to the given region. USG also leads to reduction in muscle spasm due to increased vascularity to the affected site. USG reduces joint stiffness too owing to its thermal effect properties. The nonthermal effect of USG is more important in treating soft-tissue injuries than thermal effect. The nonthermal effect of USG is mediated by cavitation (stable and unstable) and acoustic streaming.
| Method and Instrumentation of Ultrasound|| |
All diagnostic ultrasound applications are based on the detection and display of acoustic energy reflected from interfaces within the body. The unique imaging attributes of ultrasound have made it an important and versatile medical and dental imaging tool. Ultrasound scanners are among the most complex and sophisticated imaging devices currently in use. Despite their complexity, all scanners consist of similar basic components to perform key functions – a transmitter or pulser to energize the transducer, the ultrasound transducer itself, and a receiver and a processor to detect and amplify backscattered energy and manipulate the reflected signals for display. The interaction of ultrasound with tissues can be described by attenuation, reflection, scattering, refraction, and diffraction.
A transducer is a device that converts one form of energy into another. In case of ultrasound, the transducers convert an electric signal into mechanical energy and vice versa. This property of transducer is called the piezoelectric effect. Different transducers have different depth focus. Diagnostic ultrasound utilizes focus beam. It converts the electric energy provided by the transmitter into acoustic pulses directed into the patient. The range of frequency produced by a given transducer is termed its bandwidth.
Similar to X-ray, sound beams from ultrasound imaging are waves transmitting energy. USG signals may be displayed in various modes such as A-mode, M-mode, B-mode and real time. USG imaging technique can be used for the examination of either normal or pathological lesions affecting hard and soft tissues, detection of salivary stones, TMJ imaging, and detection of fractures and vascular lesions.
Depending on the application and ultrasonic intensities, ultrasound can be divided into two types: diagnostic and therapeutic ultrasound. In diagnostic ultrasound, the ultrasonic intensities used are typically in the range of 5–500 mW/cm2 and in therapeutic ultrasound, the ultrasonic intensities used are in the range of 1–3 W/cm2 [Table 1] and [Table 2].
USG echogenecities are described in comparison with adjacent tissues. It may be divided into various types such as hyperechoic (brighter), isoechoic (equal), hypoechoic (darker), anechoic (no internal echoes), and mixed signals. This information is used in staging infections from acute phase to complete abscess formation, which are (a) edematous changes, (b) cellulitis, (c) preabscess stage, and (d) abscess stage.
| Application of Ultrasonography in Dentistry|| |
With each passing day, diseases affecting the oral and maxillofacial regions are also increasing, so are imaging modalities. With continuous advancement in imaging modalities each day, diagnosis of disease has been much easier as it was few years before. USG is one such modality which should be used in the diagnosis of disease in the oral and maxillofacial region. USG has its own advantages [Table 3], but it has its own disadvantages [Table 4] too.
Ultrasonic echography has been used as a diagnostic aid with an advantage that it can be used to examine deeper areas as well as superficial regions.,,
Ultrasonography in salivary gland diseases
Identifying the nature of salivary gland's swelling as benign or malignant is difficult clinically and to rule out any confusion, various imaging modalities are used. Ultrasound is the first imaging modality of choice for salivary gland swellings. The normal echogenicity of all major salivary glands is generally homogeneous and varies from very bright to only slightly hyperechoic in comparison to adjacent muscles which appear as hyperechoic band.
USG helps in differentiating solid and cystic masses. USG in salivary gland diseases has one characteristic feature of diagnosing parenchymal structure. USG helps in diagnosing acute inflammation [Figure 1] and [Figure 2], chronic inflammation, sialolithiasis, sialosis, and Sjögren syndrome [Table 5]. Pleomorphic adenomas are usually hypoechoic, have well-defined and sharp borders with lobulization of contour and posterior acoustic enhancement that may contain calcifications. Warthin's tumors are generally ovoid, hypoechoic mass.
USG is a diagnostic tool for characterizing salivary gland tumor. Nowadays, technical advances in many imaging centers have made USG the investigation of choice for major salivary gland diseases. USG findings of various salivary gland diseases are unique to each and every disease, thus making USG a valuable diagnostic tool.
Ultrasonography in oral submucous fibrosis
USG helps in demonstrating the number, length, and thickness of the fibrotic bands and pattern of overall vascularity in the affected area. USG also helps in the diagnosis of feeble fibrotic bands in clinically normal buccal mucosa. The mucosa overlying the band has less flow velocity compared to the mucosa in between the bands where vascularity was found to be normal. Oral submucous fibrosis (OSMF) shows increased hyperechoic areas representing fibrous bands or diffuse fibrosis with normal/decreased vascularity and peak systolic velocity.
Furthermore, in cases of OSMF, masseter muscle hypertrophy has been found in various studies worldwide. It has been found that USG is a noninvasive, zero radiation tool for assessing the progression of OSMF. USG has also been used in the assessment of systemic sclerosis, localized scleroderma, etc.
Ultrasonography in neck and cervical lymph nodes
Assessment of neck lymph nodes is essential in patients with head-and-neck cancers for predicting prognosis and selecting the appropriate treatment. Normal lymph nodes appear ultrasonographically as somewhat flattened hypoechogenic structures [Figure 3].
USG can differentiate benign lymph nodes from malignant lymph nodes in patients of oral cancer. Malignant lymph nodes appear hypoechoic in comparison to neighboring strap muscles with sharp margins. In malignancy, irregular margins or blurred margins usually indicate frank invasive contour extracapsular and extranodal spread with the absence of hilum. USG can also be used to diagnose systemic diseases such as tuberculosis, eosinophilic granuloma, histiocytic necrotizing lymphadenitis, sinus histiocytosis, lymphoma, lung cancer and thyroid cancer metastases, and syphilis by lymph node examination.
The major roles of USG are to check for nodal metastasis, check the size of lymph nodes, and assess the regional extent of disease. Sensitivity of USG in assessing cervical lymphadenopathy is 96.8% compared to clinical examination. Specificity of USG is 93% when combined with fine-needle aspiration cytology, i.e. 93%.
Like any other noninvasive technique, USG has its own limitations such as changes in the internal architecture of the deeper lymph nodes cannot be recognized.
Ultrasonography in temporomandibular joint disorder
Imaging of TMJ may be necessary to supplement information obtained from clinical examination, particularly when an osseous abnormality or infection is suspected. USG is not a preferred imaging modality for TMJ but still can be used as one of the modalities along with MRI, CT scan, cone-beam CT, and arthrography.
A thorough understanding of TMJ anatomy and morphology of TMJ is essential so that a normal variant is not mistaken for an abnormality. The TMJ regions are unique because they constitute two separate joints anatomically; they function together as a single unit as the mandibular components are part of one bone. On USG examination, articular eminence and mandibular condyle are generally hypoechoic, whereas the margin of the bone is hyperechoic in USG images. However, the surface of the joint capsule, as well as the surface of the muscles, appears hyperechoic, whereas the articular disc appears hyperechoic, hypoechoic, or isoechoic due to different structural, morphological, and positional abnormalities in the patients examined.
USG can be used as a diagnostic instrument in the study of TMJ disc displacement and TMJ effusion. USG has proved to be accurate in the detection of joints with effusion and to study clinically painful joints.
Ultrasonography in the diagnosis of inflammatory swellings
Inflammatory lesions are the most common pathologic condition of the jaws. Inflammatory lesions constitute an important aspect of oral and maxillofacial pathology. The physical examination of jaw swellings lacks the diagnostic accuracy; hence, various investigations have been introduced to evaluate jaw swellings, with USG being one of the recent tools.
USG echogenecity of swellings varies from hyperechoic (brighter), isoechoic (equal), hypoechoic (darker), anechoic (no internal signals), to mixed signals. Most benign neoplasms have clear boundaries and irregular shapes and are hypoechoic. Cysts such as radicular cyst show hypoechoic to totally anechoic lesions [Figure 4]; odontogenic keratocyst shows hypoechoic lesions; and dentigerous cyst shows anechoic to focal hyperechogenecity.
USG of hemangioma has a typical appearance of homogeneous, hyperechoic mass with well-defined margins and posterior acoustic enhancement.
Ultrasonography in detecting muscular pathology
Ultrasound imaging can be an adjunct to evaluate and diagnose diseases involving facial muscles. Constant change in the parts of USG, making it more diagnostically accurate, will thus help in evaluating deeper muscle pathology too. USG helps in the diagnosis of inflammation of muscle with unknown etiology. It further helps in even describing the dimensions of the lesion.
USG also helps in the diagnosis of muscle hypertrophy in patients where all other etiological factors have been ruled out, which leads to muscle hypertrophy, thus helping in reaching to a diagnosis of idiopathic muscle hypertrophy [Figure 5].
Ultrasonography in the treatment of recurrent aphthous stomatitis
Recurrent aphthous stomatitis (RAS) is a common disease which shows multiple recurrent small, round, or ovoid ulcers with circumscribed margins. Clinically, they manifest as minor, major, or herpetiform type of RAS. They are either single or multiple in number with no tissue tags from ruptured vesicles. They are less commonly seen on heavily keratinized palate or gingiva.
Low-intensity ultrasound is most often used for canker sores therapy. USG has a nonthermal effect on tissues. USG acts either by increasing angiogenesis or by inducing granulation tissue formation or altering the oral microflora. Numerous studies have been conducted to show the efficacy of USG on RAS. In a study conducted by Brice on 35 students, it was found that low-intensity ultrasound appears to have a modest beneficial effect on RAS.
Ultrasonography in other fields of dentistry
Ultrasound imaging can be used in the field of endodontics too. It can improve root canal access, monitoring postsurgical healing of periapical lesions of endodontic origin. To access this, a study was conducted by Tikku et al. to evaluate the role of USG in the diagnosis of periapical lesion of endodontic origin in maxilla and mandible. A total of thirty patients were evaluated for periapical lesions to diagnose whether the lesion is cystic or solid in nature. Periapical surgery was done, and the specimen was sent for histopathological examinations. Report of histopathology correlated with USG findings. Results showed that USG can have a role in detecting periapical lesions. Periodontal USG helps in measuring periodontal depth and in the assessment of periodontal health.
Color Doppler in sonography has helped in the diagnosis of oral vascular malformations and vascular tumors.
USG can be used in various aspect of dentistry such as in the detection of either foreign bodies or muscular pathology or fracture or periapical lesions. USG can also be used in promoting healing; sterilization and management of superficial fascial space infections etc. Hence, the use of ultrasound imaging is immense in the field of dentistry with advantages and disadvantages too [Table 3] and [Table 4].
| Future Prospect|| |
Apart from diagnostic process, USG also enhances rapid healing process of various injuries. With time, USG has also undergone lots of advances such as three-dimensional imaging to allow multiplanar reformatting, surface renderings, and color Doppler sonography for the evaluation of blood flow. With the advancement in transducers, USG has resulted in more precision. Most of the researches done nowadays on USG show its diagnostic capability such as diagnosis of inflammatory swellings of maxillofacial and periapical regions. The future of USG in dental field is bright, but proper training of students and radiologists should be imparted in the evaluation of various lesions. Various clinical researches are required with good sample size to check for the efficacy of USG in the maxillofacial region.
| Conclusion|| |
After serving medical field for many years, the role of USG in dental field is a matter of great research, thus helping humankind in knowing its infinite potential in various diseases affecting oral and maxillofacial regions. As a diagnostic and therapeutic tool, USG stands as a noninvasive, widely available, affordable, and repeatable technique. USG technique is extremely operator dependent. The addition of color and power Doppler ultrasound imaging has increased the efficacy of USG. The finding of USG report should be clinically correlated to increase the efficacy of USG.
Financial support and sponsorship
Conflicts of interest
There are no conflicts of interest.
| References|| |
Miller DL, Averkiou MA, Brayman AA, Everbach EC, Holland CK, Wible JH Jr., et al.
Bioeffects considerations for diagnostic ultrasound contrast agents. J Ultrasound Med 2008;27:611-32.
Sample WF. Gray scale ultrasonography. West J Med 1976;124:403-4.
Dijkmans PA, Juffermans LJ, Musters RJ, van Wamel A, ten Cate FJ, van Gilst W, et al.
Microbubbles and ultrasound: From diagnosis to therapy. Eur J Echocardiogr 2004;5:245-56.
Newman PG, Rozycki GS. The history of ultrasound. Surg Clin North Am 1998;78:179-95.
Schortinghuis J, Stegenga B, Raghoebar GM, de Bont LG. Ultrasound stimulation of maxillofacial bone healing. Crit Rev Oral Biol Med 2003;14:63-74.
Rubin C, Bolander M, Ryaby JP, Hadjiargyrou M. The use of low-intensity ultrasound to accelerate the healing of fractures. J Bone Joint Surg Am 2001;83:259-70.
Plotino G, Pameijer CH, Grande NM, Somma F. Ultrasonics in endodontics: A review of the literature. J Endod 2007;33:81-95.
Erdogan O, Esen E, Ustün Y, Kürkçü M, Akova T, Gönlüşen G, et al.
Effects of low-intensity pulsed ultrasound on healing of mandibular fractures: An experimental study in rabbits. J Oral Maxillofac Surg 2006;64:180-8.
Chakarvarty A, Panat SR, Sangamesh NC, Aggarwal A, Jha PC. Evaluation of masseter muscle hypertrophy in oral submucous fibrosis patients -an ultrasonographic study. J Clin Diagn Res 2014;8:ZC45-7.
Srinivas K, Sumanth KN, Chopra SS. Ultrasonographic evaluation of inflammatory swellings of buccal space. Indian J Dent Res 2009;20:458-62.
] [Full text]
Ahuja A, Ying M. An overview of neck node sonography. Invest Radiol 2002;37:333-42.
Scheven BA, Man J, Millard JL, Cooper PR, Lea SC, Walmsley AD, et al.
VEGF and odontoblast-like cells: Stimulation by low frequency ultrasound. Arch Oral Biol 2009;54:185-91.
Hassani S. Principles of ultrasonography. J Natl Med Assoc 1974;66:205-7, 231.
Carovac A, Smajlovic F, Junuzovic D. Application of ultrasound in medicine. Acta Inform Med 2011;19:168-71.
Yoon MJ, Kim E, Lee SJ, Bae YM, Kim S, Park SH, et al.
Pulpal blood flow measurement with ultrasound Doppler imaging. J Endod 2010;36:419-22.
Hirai T, Manders EK, Nagamoto K, Saggers GC. Ultrasonic observation of facial bone fractures: Report of cases. J Oral Maxillofac Surg 1996;54:776-9.
Akizuki H, Yoshida H, Michi K. Ultrasonographic evaluation during reduction of zygomatic arch fractures. J Craniomaxillofac Surg 1990;18:263-6.
Hirai T, Fumiiri M. Ultrasonic observation of the nail matrix. Dermatol Surg 1995;21:158-61.
Gritzmann N, Rettenbacher T, Hollerweger A, Macheiner P, Hübner E. Sonography of the salivary glands. Eur Radiol 2003;13:964-75.
Traxler M, Schurawitzki H, Ulm C, Solar P, Blahout R, Piehslinger E, et al
. Sonography of nonneoplastic disorders of the salivary glands. Int J Oral Maxillofac Surg 1992;21:360-3.
Białek EJ, Jakubowski W, Karpińska G. Role of ultrasonography in diagnosis and differentiation of pleomorphic adenomas: Work in progress. Arch Otolaryngol Head Neck Surg 2003;129:929-33.
Shimizu M, Ussmüller J, Donath K, Yoshiura K, Ban S, Kanda S, et al.
Sonographic analysis of recurrent parotitis in children: A comparative study with sialographic findings. Oral Surg Oral Med Oral Pathol Oral Radiol Endod 1998;86:606-15.
Manjunath K, Rajaram PC, Saraswathi TR, Sivapathasundharam B, Sabarinath B, Koteeswaran D, et al.
Evaluation of oral submucous fibrosis using ultrasonographic technique: A new diagnostic tool. Indian J Dent Res 2011;22:530-6.
] [Full text]
Marchal G, Oyen R, Verschakelen J, Gelin J, Baert AL, Stessens RC, et al.
Sonographic appearance of normal lymph nodes. J Ultrasound Med 1985;4:417-9.
Dudea SM, Lenghel M, Botar-Jid C, Vasilescu D, Duma M. Ultrasonography of superficial lymph nodes: Benign vs. Malignant. Med Ultrason 2012;14:294-306.
Baatenburg de Jong RJ, Rongen RJ, Laméris JS, Harthoorn M, Verwoerd CD, Knegt P. Metastatic neck disease. Palpation vs. ultrasound examination. Arch Otolaryngol Head Neck Surg 1989;115:689-90.
Nabeih YB, Speculand B. Ultrasonography as a diagnostic aid in temporomandibular joint dysfunction. A preliminary investigation. Int J Oral Maxillofac Surg 1991;20:182-6.
Melis M, Secci S, Ceneviz C. Use of ultrasonography for the diagnosis of temporomandibular joint disorders: A review. Am J Dent 2007;20:73-8.
Esen G. Ultrasound of superficial lymph nodes. Eur J Radiol 2006;58:345-59.
Turkington JR, Paterson A, Sweeney LE, Thornbury GD. Neck masses in children. Br J Radiol 2005;78:75-85.
Chandak R, Degwekar S, Bhowte RR, Motwani M, Banode P, Chandak M, et al.
An evaluation of efficacy of ultrasonography in the diagnosis of head and neck swellings. Dentomaxillofac Radiol 2011;40:213-21.
Brice SL. Clinical evaluation of the use of low-intensity ultrasound in the treatment of recurrent aphthous stomatitis. Oral Surg Oral Med Oral Pathol Oral Radiol Endod 1997;83:14-20.
Tikku AP, Bharti R, Sharma N, Chandra A, Kumar A, Kumar S. Role of ultrasound and color Doppler in diagnosis of periapical lesions of endodontic origin at varying bone thickness. J Conserv Dent 2016;19:147-51.
] [Full text]
Bains VK, Mohan R, Bains R. Application of ultrasound in periodontics: Part II. J Indian Soc Periodontol 2008;12:55-61.
] [Full text]
[Figure 1], [Figure 2], [Figure 3], [Figure 4], [Figure 5]
[Table 1], [Table 2], [Table 3], [Table 4], [Table 5]