Applications of ultrasound in dentistry

1. Evirgen S, kamburoglu K.
World J Radiol 2016 January 28; 8(1): 50-58.
REVIEW ON THE APPLICATIONS OF
ULTRASONOGRAPHY IN
DENTOMAXILLOFACIAL REGION
Journal club: 14
Dr Sanjana Ravindra
Dr Sanjana Ravindra
Rajarajeswari Dental College
Bangalore

2. Introduction
Sonography – technique based on sound waves that acquire images in real
time without the use of ionizing radiation.
‘‘Ultra’’ means beyond or in excess
‘‘Sound’’ means audible sound energy
The term ultrasound means the form of sound energy beyond audible range
Ultrasound wave is a form of longitudinal mechanical wave
that needs a medium to transmit from one place to another
Dr Sanjana Ravindra

3. • Human ear can hear only a limited range of sound
frequencies- range between 20Hz - 20,000Hz
• Frequencies below the audible range (i.e. < 20Hz)-
‘infrasonic‘
• Frequencies above the audible range (i.e. >20,000Hz)-
‘ultrasonic’
Ultrasound used for diagnostic purposes has a frequency of 2MHz
– 20MHz
Introduction
Dr Sanjana Ravindra

4. HISTORY
1794  Spallanzani
Demonstrated the existence of Ultrasound in bats
1912  Richardson invented the echo locator based on the idea of
ultrasound used for navigation and detection of objects in water
1942  Dussik K.T & Friederick reported the first successful application of ultrasound to
medical diagnosis
Dr Sanjana Ravindra

5. 1971  Daly and Wheeler carried out ultrasound imaging of dental soft tissues to find out the
use of ultrasonic measurement in clinical evaluation of oral soft tissues
1954  Kallnus developed Doppler ultrasound
1977  Ferguson MM et al demonstrated the use of ultrasonography in the diagnosis of cystic
hygroma of the neck
1976  Nieman demonstrated the use of ultrasonography to detect parotid masses
1978  Pickrell KL was the first to use ultrasonography for localization of parotid gland calculus
HISTORY
Dr Sanjana Ravindra

6. Some of them are partially reflected from the interface
between different tissues and returns to the transducer
Sound waves travel into body and hit the tissues and
organs
Transducer sends high-frequency sound pulses (1 to 5
MHz) into our body
Transducer calculates the distance from it to the tissues and transmits the echoes
electrically onto a monitor.
Dr Sanjana Ravindra

7. All diagnostic ultrasound applications are based on detection and display of
acoustic energy reflected from interfaces with in the body
 These interactions provide information needed to generate high resolution
gray scale images of body and related to blood flow
Dr Sanjana Ravindra

8. INSTRUMENTATION
Transmitter
Transducer
Receiver
Processor
Display
Record and
storing of
image
Dr Sanjana Ravindra

9. TRANSMITTER
 Energize the transducer by application of precisely timed,
high amplitude voltage
 Controls rate of pulses emitted by transducer
 No. of pulsed echoes produced in each sec is PRF
(pulse repetition frequency)
 Doubling PRF causes Better Resolution of the image
Dr Sanjana Ravindra

10. TRANSDUCER
1. Piezoelectric crystals
2. Two electrodes
3. Backing layer
4. Matching layer
5.Acoustic insulator (rubber
)
6. Plastic housing
• Device which converts one form of energy to other
• In US, it converts electrical energy to ultrasonic energy & vice versa
• Transducer is both a transmitter & a receiver
Dr Sanjana Ravindra

11. TRANSDUCER - PIEZOELECTRIC CRYSTALS
Thin piezoelectric crystal (0.5mm) element
located near face of transducer
Front and back surface of crystal is coated
with conducting film to ensure good contact
with electrodes
Outside electrode is grounded to prevent
electric shock to patient & inner electrode
abuts against a thick backing block.
Housing is usually a strong plastic.
• Naturally occurring
piezoelectric material – quartz,
Rochelle salt, topaz, and dry
bone
• Man made piezoelectric
materials are called
“ferroelectric materials”
• Eg: Barium titanate, Lead
zirconate titanate (PZT),
Polyvinylidene difluoride
(PVDF)
Dr Sanjana Ravindra

12. TRANSDUCER - BACKING LAYER
 Made of tungsten with rubber
powder and epoxy resin
 Backing material occupies the
space behind the crystal,
 Dampens the vibrations
 Accepts all waves that it receives
and completely absorb the energy
of waves
Dr Sanjana Ravindra

13. TRANSDUCER - MATCHING LAYER
 Made of aluminum powder and
epoxy resin
 Matching layer optimizes the
transmission of sound energy into
patient by providing a medium that is
intermediate in acoustic properties of
a piezoelectric crystal and tissue of
the patients
Dr Sanjana Ravindra

14. RECEIVER
 Receives , detects and amplifies the weak returning
signals
 Also provides compensatory amplification of the
weaker signals those arising from deeper tissues - time
gain compensation (TGC)
 It compresses and re-maps the wide range of
amplitudes returning to transducer into narrow range
Dr Sanjana Ravindra

15. SIGNAL PROCESSOR
Display screen is divided into a matrix of pixels
Image of all signal reflections are formed and displayed
on monitor
Dr Sanjana Ravindra

16. All ultrasound transducers contain a range of frequencies, termed
bandwidth
- 2.5 - 3.5 MHz for general abdominal imaging
– 5.0 - 7.5 MHz for superficial imaging
Dr Sanjana Ravindra

17. INTERPRETATION OF USG IMAGE
Sonographic images are identified in terms of echoes
Different structures emit different signals on US imaging - termed as echogenicities
Higher the reflection --- higher the echogenicity
Hyperechoic structures- appear white and bright
Isoechoic - same density as surrounding structures and appear grey
Hypoechoic structures- appear dark, black and produce weak signal
Dr Sanjana Ravindra

18. The internal echoes may be either homogeneous or
heterogeneous.
‘Homogeneous’ refers to an even echo pattern or
reflections that are relative and uniform in composition.
If the mass is uniformly hypoechoic or hyperechoic, then
it is described as a homogeneous mass.
‘Heterogeneous’ refers to an uneven echo pattern or
reflections of varying echodensitities.
If a mass lesion contains hyperechoic and hypoechoic
areas, it would be described as a heterogeneous mass
Dr Sanjana Ravindra

19. ADVANTAGES
Sound waves are not ionizing radiation.
There are no known harmful effects on any tissues at energies & doses
currently used in diagnostic ultrasound.
Images show good differentiation between soft tissues.
It performs muscles and soft tissue images very well.
It renders "live" images.
It shows the structure of organs.
Small, easily carried scanners are available.
Technique is widely available & inexpensive.Dr Sanjana Ravindra

20. DISADVANTAGES
If lesion is very deep or surrounding bone is very thick,
ultrasound waves are absorbed by bone.
Ultrasound performs very poorly when there is a gas
between the scan head and the organ of interest.
The deep penetration of ultrasound is limited.
The method is operator-dependent
Real-time imaging means that the radiologist must be
present during the investigation
Dr Sanjana Ravindra

21. INDICATIONS
Evaluation of swellings of the neck, particularly those involving thyroid, cervical
lymph nodes or major salivary glands — ultrasound is now regarded as the
investigation of choice for detecting solid and cystic soft tissue masses
Detection of salivary gland and duct calculi
Determination of the relationship of vascular structures and vascularity of masses
with the addition of colour flow Doppler imaging
Assessment of blood flow in the carotids and carotid body tumours
Ultrasound-guided fine-needle aspiration (FNA) biopsy
Dr Sanjana Ravindra

22. INDICATIONS
Assessment of TMJ disorders
Assessment of the Intraosseous lesions of the jaw
Assessment of cervical lymph node metastasis
Assessment of Maxillofacial space infections Assessment of Soft tissue lesions such as
carcinoma of tongue
Dr Sanjana Ravindra

23. In the assessment of congenital vascular lesions of the maxillofacial region.
To characterize the flow of head and neck vascular anomalies and to differentiate
hemangiomas from other vascular malformations.
In monitoring the healing of periapical lesions after surgery.
To identify factors associated with alterations of mental artery flow.
To assess mental artery flow and mental artery pulse strength.
An effective tool in the definitive diagnosis of nonspecific nodular lesions of the
soft tissues located in the oral and maxillofacial region.
In the diagnosis and differentiation of benign and malignant salivary gland
tumors.
Doppler US Doppler US has found wide spread use in the
assessment
of peripheral vascular disease.
Accuracy of Color doppler US was found to be 95% in determining tumor site
Dr Sanjana Ravindra

24. MIDFACIAL FRACTURES
Authors of a study
used ultrasound in
diagnosing
zygomatico-orbital
complex fractures
and found an
accuracy of 94%
McCann et al found
lower accuracy
(85%) in diagnosing
fractures of the
zygomatico-orbital
complex when
compared to
aforementioned
study.
Another study,
reported accuracy in
diagnosing fractures
of the orbital floor
Gülicher et al
showed that
ultrasonographic
control of fracture
repair led to
excellent results in
almost all patients.
• Orbitozygomatical complex fractures
• Isolated fractures of the zygomatic arch,
orbital floor, nasal bone, frontal sinus,
along with complex Le-Fort fractures
Soft tissue
covering of the
tissues impairs
imaging of
fractures in several
planes.
Therefore, the
application of US
is not a substitute
for accurately
taken X-ray
imaging for
detecting fractures
of the mandibular
ramus and
condyle[
Dr Sanjana Ravindra

25. Dr Sanjana Ravindra

26. TEMPOROMANDIBULAR DISORDERS
US, an alternative technique to magnetic resonance imaging (MRI), was
utilized for assessing TMJ in the beginning of 1990´s.
Transverse
and
longitudinal
scans
Antereriosuperi
or joint
compartment
Axial, coronal,
and oblique
views
Hyperechoic
• Condyle
and
• Glenoid
fossa
Isoechoic
• Connective
• Muscular
tissues
Hypoechoic
• Superior
and inferior
joint
spaces
Dr Sanjana Ravindra

27. TMJ - DISK
DISPLACEMENT
WITH REDUCTION WITHOUT
REDUCTION
Closed mouth
Open mouth
Dr Sanjana Ravindra

28. Emshoff et al concluded that
US was a reliable diagnostic
tool in diagnosing normal disc
position at the various mouth
opening positions.
A meta-analysis of US for the
detection of TMJ anterior disc
displacement revealed that
high resolution US was
superior in the diagnosis of
anterior disc displacement
without reduction.
On the other hand, utilization
of US for detecting lateral
and posterior displacements
was not suggested.
Overall, the diagnostic efficacy of
US in TMJ evaluation is acceptable
and can be used as a rapid
preliminary diagnostic method
Dr Sanjana Ravindra

29. Muscle disorders
Temporalis muscle is seen as a thin
HYPOECHOGENIC BAND lying
adjacent to the medial part of the
temporalis fossa.
The bony landmark is identified as a
HYPERDENSE LINE, whereas the
course of the temporalis muscle is best
visualized by having the patient clench.
The masseter muscle is seen as a
HOMOGENEOUS structure lying
adjacent to the ECHOGENIC BAND of
the mandible.
The anterior digastric muscle
corresponds to round
HYPOECHOGENIC zones located
lateral to the respective mylohyoid
muscles.
The posterior digastric muscle is seen
as a HYPOECHOGENIC band located
under the HOMOGENEOUS
ultrasonographic pattern of the parotid
gland.
Sternocleidomastoid muscle is easily
visualized due to its large size and typical
band shape which shows a solid
HYPOECHOGENIC ultrasonographic pattern.
The medial boundary of the
sternocleidomastoid muscle is identified as a
very DENSE HYPERECHOGENIC LINE.Dr Sanjana Ravindra

30. US was found to be useful for the
measurement of masseter muscle
thickness.
In the inflammatory muscle, the
echogenic bands, which correspond to
the internal fascia or tendon of the
muscle, are frequently diminished or
disappeared.
Muscle with histologically verified edema
shows less echogenity compared to that
of muscle without edema .
Muscle disorders
Dr Sanjana Ravindra

31. MASSETER
MUSCLE
HYPERTROPHY
Normal masseter muscle
Masseter hypertrophy
Dr Sanjana Ravindra

32. ORAL SUBMUCOUS
FIBROSIS
Manjunath K Evaluation of oral submucous
fibrosis using ultrasonographic technique: a
new diagnostic tool.
 Ultrasonographic unit with color Doppler and
9-5 MHz intra - cavitary convex transducer
used with water path
 Glove finger filled with water served as
water path between transducer and oral
mucosa
 Transducer with cellulose dextrose gel was
placed on water path and analyzed
• In normal individuals, ultrasonography
delineates normal mucosa with uniform fine
mottled appearance with interspersed
hypoechoic areas.
• Color Doppler and spectral Doppler depicts
uniform distribution of blood vessels
• Diffuse fibrotic patch (crossing dot
lines) and diminished vascularity in
an oral submucous fibrosis lesion
Dr Sanjana Ravindra

33. Soft tissue masses of the neck
Thyroglossal cysts and branchial cleft cysts are mostly encountered
cervical cysts. Less frequently, cystic hygomas, dysontogenetic cysts,
ranulas and laryngoceles are found.
On US examination, thyroglossal cysts most often appear
anechoic with posterior acoustic enhancement.
Debris in cervical cysts can result in a hypoechoic, pseudosolid
appearance. Although most of branchial cleft cysts are
hypoechoic some of them are anechoic.
Ultrasonographically ranulas are smoothly marginated, anechoic
or homogeneously hypoechoic lesions without internal color or
power Doppler signals.
Palagatti et al found a diagnostic accuracy of 92.2% for US in the
diagnosis of cystic lesions which is in line with the previous literature.
Dr Sanjana Ravindra

34. US is able to show
hyperreflective
microbubbles of gas in
supurative sialadenitis
with adjacent reactive
nodes.
A study, found that most
of the inflammatory
swellings had relatively
clear boundaries,
hypoechoic intensity and
homogeneous
ultrasound architecture
of lesions.
Considering
inflammatory swellings,
us had a sensitivity of
97% and specificity of
100%, whereas; clinical
diagnosis had a
sensitivity and specificity
of 85.7%[57].
Us was found to have
high sensitivity in the
diagnosis of
inflammatory swellings of
the head and neck
region.
Acute inflammation
Dr Sanjana Ravindra

35. Odontogenic tumor is
hyperechogenic because of the
uniformity of the tumor mass.
Odontogenic cystic lesions are
unechogenic, because of their
liquid content.
Keratocystic odontogenic tumors
are hypoechogenic, because of
their dense and thick content[
Bone lesions
Dr Sanjana Ravindra

36. TEETH
Used in
detection
of enamel,
dentin
thickness
Ultrasonic Caries Detector (Novadent)
Dr Sanjana Ravindra

37. PERIAPICAL LESIONS
Cystic lesion: A hypoechoic well-contoured cavity surrounded by reinforced bone walls, filled
with fluid, and with no evidence of internal vascularization on color Doppler examination.
Granuloma: A poorly defined hypoechoic area, showing rich vascular supply on color Doppler
examination.
Dr Sanjana Ravindra

38. SPACE INFECTION
Normal submandibular regionAffected submandibular space
A.Sonogram of the submandibular space showing the spreading infection and the involvement of the
submandibular lymph nodes (arrowheads). The mixed hypoechoic and hyperechoic pattern indicates
the starting of abscess formation.
B, Sonogram of normal submandibular region for comparison with the infected side.
Dr Sanjana Ravindra

39. Salivary gland
SALIVARY GLANDS – PAROTID GLAND
& DUCT
1 parotid gland, 2 Stensen's duct, 4 masseter
muscle, 5 surface of the mandible, 6 buccal muscle,
large arrow retromandibular vein and external carotid
artery.
Axial ultrasound - normal right
submandibular gland showing its
relationship to adjacent structures. S,
submandibular gland; M, mylohyoid
muscle; H, hyoglossus muscle; White
arrow, intraglandular duct; D, posterior
belly of digastric muscle.
SUBMANDIBULAR GLAND
Dr Sanjana Ravindra

40. • SUBLINGUAL
GLAND
ACUTE INFLAMMATION
salivary glands are enlarged and
hypoechoic. There may be
inhomogeneous; multiple small,
oval, hypoechoic areas; and may
have increased blood flow
Dr Sanjana Ravindra

41. CHRONIC INFLAMMATION
SIALOLITHIASIS
US features of
sialolithiasis include
strongly hyperechoic
lines or points with
distal acoustic
shadowing, which
represent stonesDr Sanjana Ravindra

42. US features of advanced Sjogren
syndrome include inhomogeneous
structure of the gland with scattered
multiple small, oval, hypoechoic or
anechoic areas, usually well defined, and
increased parenchymal blood flow
SJOGREN SYNDROME
PLEOMORPHIC ADENOMA
Hypoechoic, well-defined,
lobulated tumors with posterior
acoustic enhancement and
may contain calcifications
WARTHINS TUMOR
well defined, hypoechoic, and
inhomogeneous with multiple irregular
anechoic areas (arrowheads) and
posterior acoustic enhancement.
Dr Sanjana Ravindra

43. Oral cancer tumor thickness
In conclusion, US could be used as the primary imaging modality for the
assessment of tongue tumor thickness as it improved planning for
prophylactic neck dissection in early stage disease.
•Wakasugi-Sato et al developed a method in order to
allow operators to easily assess and confirm the surgical
clearance of tongue carcinomas intraoperatively using
intraoral US. Tumor thickness was reported as an
important prognostic factor in cancers of the oral cavity.
Authors demonstrated that there was a strong correlation
between tumor thickness measured from ultrasonic
images and histological sections.
•Yuen et al evaluated the correlation between ultrasonic
and pathologic tumor thickness. They found a statistically
significant correlation between pathologic and ultrasonic
thickness.
•Shintani et al measured tumor thickness of squamous
cell carcinoma and compared the clinical usefulness of
CT, MRI, and intraoral US to delineate the extent of
tumors. They showed that intraoral US is very accurate
and valuable for mapping these tumors.
•Yesuratnam et al compared preoperative tumor
thickness on high resolution intraoral US and MR
imaging with histologically determined tumor thickness.
They found high correlation between tumor thickness on
preoperative US and histological primary tumor thickness
and good correlation between MRI and histological
primary tumor thickness
Dr Sanjana Ravindra

44. Unsharp borders common
in Tuberculous nodes
sharp borders in malignant
nodes
Calcification within lymph
nodes
LYMPH NODES
Normal, Reactive,
Lymphomatous & Tuberculous
nodes are predominantly
hypoechoic when compared
with the adjacent muscles.
Dr Sanjana Ravindra

45. VASCULAR PATTERN
Dr Sanjana Ravindra

46. New ultrasonic device including a soft
tissue matched transducer with a
customized transreceiver and signal
processing was capable of measuring
soft tissue thickness over bone and
implants placed in porcine models.
This was efficient as a diagnostic tool
for intraoral measurements of the
inferior alveolar canal and floor of the
maxillary sinus before dental implant
placement.
Authors measured the distance from the
bottom of the osteotome to the inferior
canal and maxillary sinus floor using a
novel ultrasonic device and
conventional radiographs.
A significant positive correlation was
observed between the radiographic and
us measurements.
Implantology
US has the potential to be an alternative diagnostic tool for implant dentistry
owing to its nonionizing nature
US may play an important role in locating submerged implants.
Dr Sanjana Ravindra

47. US has emerged as a
noninvasive periodontal
assessment tool that
yields real time
information regarding
level, tissue thickness,
histological change,
calculus and bone
morphology as well as
tooth structure for
fracture cracks.
Because of the small
size of the probe and
its special design,
patients felt that the
oral US was a stress
free, painless and fast
examination tool.
The periodontal width
is directly accessible
and measurable.
Besides, it offeres new
prospects for gum
thickness evaluation,
earlier detection of a
small anatomic change,
and diagnosis of oral
mucosa lesions.
In contrast to the
conventional methods
of transgingival probing
witch is an invasive
method and may give
false measurements
because of the tissue
edema which occur
due to injection of local
anesthesia prior to the
procedure
Periodontal US
Dr Sanjana Ravindra

48. Another possible application of
US studied is the visualization of
foreign bodies in soft tissues.
Among other imaging
modalities, the best
sensitivity and
specificity results
were achieved by
using us
Visualization of the
size and form of well-
shaped materials
such as wood,
composite, amalgam
and glass
Foreign bodies
Dr Sanjana Ravindra

49. US is an innovative and
evolving imaging
technology with plenty of
research continuing to be
done in medical field.
It is safe, rapid, portable
and economic.
Further studies towards
clinical applications of the
US in the dento-
maxillofacial region are
essential in order to obtain
information regarding
accurate and appropriate
clinical usage of the
system in dentistry[
CONCLUSION
Dr Sanjana Ravindra

50. REASON FOR CHOOSING THIS ARTICLE ?
Dr Sanjana Ravindra

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Dr Sanjana Ravindra

53. Dr Sanjana Ravindra