MAXILLARY SINUS part I / oral surgery courses

MAXILLARY SINUS
part I
Seminar
On
INDIAN DENTAL ACADEMY
Leader in continuing Dental Education
www.indiandentalacademy.com

INDEX
 Introduction
 Development
 Anatomy
 Histology
 Blood supply, Venous supply, Lymphatic supply
 Functions
 Examination
 Investigations
 Pathologies of maxillary sinus (developmental
anomalies)

Introduction
 The sinus is also known as the antrum based on the
Greek meaning “cave”.
 The maxillary sinus is a part of series of pneumatic
cavities, which are restricted to the skull in human;
called the paranasal sinuses,
 The maxillary sinus is defined as “the pneumatic
space that is lodged inside the body of maxilla and
that communicates with the environment by way of
middle nasal meatus”.

 They are paired structures located largely in the body of
each maxilla; are mirror images of one another (though
not always symmetrical) and are approximately pyramidal
in shape
 It lies primarily in the maxilla but may extend into the
palatine and zygomatic bones.

DEVELOPEMENT
 The maxillary sinus is the first paranasal sinus to
develop at approximately the third month of fetal life.
 The process begins by slow development of a
mucosal pouching of the ethmoid infudibulum
 The sinus cavity continues to develop as a slit like
invagination of the nasal epithelium into the
cartilagenous nasal capsule.
 This stage of development is called the primaryprimary
pneumatizationpneumatization process which continues until late in
the fourth fetal month.

 The second phase of development of the maxillary
sinus is called secondary pneumatization.secondary pneumatization.
 This process starts at approximately the fifth month
of fetal life, when the shallow primordium of the
maxillary sinus begins to grow into the adjacent
growing bone of maxilla.
 This process proceeds slowly, and by birth sinus
appears as a small ovoid groove on the side of
maxillary bone close to the orbit and measures on
average 7mm in anteroposterior length, 4mm in
length,with an estimated volume of 6 to 8 ml.

 By the fourth or fifth month of age, the sinus can be
seen radiographically on anteroposterior views as a
triangular area medial to the infra orbital foramen
 At 7 years of age, the rapid growth of maxillary sinus
resumes and continuous for the next 4 to 5 years,
corresponding to the eruption of the permanent
teeth.
 The final growth spurts of the maxillary sinus takes
place between 12 and 14 years of age, when it
extends down to the same level as the nasal floor

DIAGRAM SHOWING DEVELOPMENT OF
MAXILLARY SINUS FROM BIRTH TO ADULT SIZE.

With completion of eruption of all the maxillary permanent
teeth, expansion of the maxillary sinus fills the growing
maxillary bone to produce the adult pyramidal shape of
the sinus.
This expansion into alveolar process places the floor
of the sinus approximately 5 to 12.5 mm below the floor
of nose.

 However, in some patients, some degree of expansion or
pneumatization of the sinus continue throughout life.

ANATOMY
 The maxillary sinus has a horizontal pyramidal shape that
consists of a base , an apex and four sides.
 The base comprises the lateral wall of the nasal cavity,
whereas apex is at the junction of the maxillary and
zygomatic bones.

Remaining sides are
 Superior wall or roof of the sinus
 Anterior wall
 Posterior and lateral wall blend together to form
posterolateral wall
 Floor of sinus
 The sinus in divided into compartments by presence
of septae.

 It is approximately 15 to 20 ml in volume, with a
dimensions of :
 Vertical height opposite 1st Molar -3.5 cm
 Transverse breadth - 2.5 cm
 Anteroposterior depth – 3.2 cm

HISTOLOGY
 The maxillary sinus is lined with a respiratory mucosa
that is similar to and continuous with that of the nose
and the other paranasal sinuses.
 Epithelial lining of the maxillary sinus consists of a
single layer of pseudo stratified columnar ciliatedpseudo stratified columnar ciliated
epithelium.
 The maxillary sinus mucosa has a high regenerative
capacity after traumatic or surgical removal or once
the cause of infection is removed

BLOOD SUPPLY
 Blood supply to sinus is rich but less as compared to
nasal mucosa and oral cavity.
 The posterior, middle and anterior superior dental,
greater palatine and sphenopalatine branches.
 Facial, infra-orbital and greater palatine also contribute.

VENOUS DRAINAGE
 Pterygoid venous plexus and facial vein contribute to
venous drainage of sinus.
 Infection from maxillary sinus may spread to involve the
cavernous sinus via draining veins(facial vein and emissary
vein) to cause cavernous sinus thrombosis.

LYMPHATIC DRAINAGE
 Lymphatic drainage is important because infections and
malignant tumors may spread along the lymphatic system.
 Drain into deep cervical either directly or via
submandibular nodes.

NERVE SUPPLY
 Sensory innervation from maxillary nerve.
 Sympathetic from superior cervical ganglion.
 Parasympathetic from sphenopalatine ganglion(greater
palatine and lesser palatine branch- general sensory and
secretomotor to seromucous glands of sinus.)

FUNCTIONS OF MAXILLARY SINUS
 Reduction of weight of facial skeleton :-
Sinus filled with air rather than
cancellous bone lightens face by approx. the weight of
pair of spectacles.
 Phonetic resonance and auditory feedback :-
Sinuses act as a resonating box
and aid in conductance of voice to ones own ear.

 Insulation :-
Temperature of the inspired air can vary from
-50o
c to 50o
c, the rich arterial anastomosis warms the
inspired air and absorbs heat from expired air and
insulate orbit from intranasal temperature variations.
 Air conditioning :-
Sinus contain some serous glands, whose
watery secretions evaporates to humidify the contained
air and also maintain the tempt. Inside.

 Water conservation :-
Heat exchanger role of paranasal sinus
may have important role in water conservation.
 Filtration :-
Particulate matter which escaped
filtration by nose may be trapped by mucous blanket of
sinus.

 Olfaction :-
Pneumatization may have evolved to
increase the area of olfactory mucosa there by improving
the sense of smell. A scent may persist within sinus for
some time and can be used as reference for new odours.
 Dead space :-
Act as a dead space between maxilla
and alveolar process, as they evolved incidentally during
growth of face.

 Gas exchange of the maxillary sinus mucosa :- (hampered if)
v
v
Decreased oxygen pressure in sinus
Increased capillary permeability
Increased transudate and glandular metaplasia
Increased goblet cells and mucous secretion
Mucosa becomes edematous and polypoidal
And thus mucosal thickening seen on radiograph.
antronasal duct is blocked

 Patency of the antronasal duct :-
Sinus ostium leads into 6mm
long(2.5mm in diameter) curving canal, this being termed
as antronasal duct.
Its patency is imp. for efficient aeration
and clearance of secretions to maintain health of sinus.
causes of blockage :- plug of mucous, polyp,
malignancy, in lying down position size is decreased, nasal
septal defect, etc,. all these condition can lead to sinus
barotrauma.

 Mucus production and mucociliary transport :-
Position of ostium is unfavourably for
gravitational drainage when head is erect, therefore sinus
secretion clearance is dependent on mucociliary system.
Presence of mucous secretion on
surface of sinus decreases water loss, provides
mechanical barrier between mucosa and traps particulate
matter.
The mean flow rate of mucociliary transport is 6mm/min.
this is necessary to prevent collection of fluid in sinus and
secondary infection.

 Mucociliary action is reduced in inflammation,injury,
adrenalin, corticosteroids, smoking.
 Temperature above 45o
c and below 10o
c will stop ciliary
action and thus upper respiratory tract infection may
result.

 Flying and diving :-
High and low atmospheric pressure
may result in barotrauma. It is more in case of diving as
pressure is maintained in aeroplanes.
If antronasal duct is blocked and
pressure is decreased, mucosal blood vessels may
rupture and lead to epistaxis, hematoma formation or
hemorrhage.[pressure and volume of given mass of gas are inversely
proportional. So accordingly expansion of air in sinus occurs on ascent and
contraction on descent.]

EXAMINATION AND INVESTIGATIONS OF
THE MAXILLARY SINUS
 Clinical examination of maxillary sinus is preceded by
patient’s presenting complaint, its history and medical
history.
 The middle third of face should be inspected for the
presence of asymmetry, deformity, swelling,
erythema, ecchymosis or hematoma. Epiphora, nasal
obstruction, epistaxis, other discharge or odour from
nostril should be noted.
 Any evidence of tenderness, crepitus and trismus
should also be noted

Investigations
 Rhinoscopy :- Nasal speculum and headlight or
mirror are used. Anterior rhinoscopy is done for
visualization of nasal passages. Posterior rhinoscopy is
done for visualization of the posterior aspects of all
conchae.
 Nasendoscopy :- Narrow fiber optic endoscope is
used under local anesthesia for examination of
superior, middle and inferior meatus.

 Transillumination :-Transillumination of the
maxillary sinuses is performed in a darkened room
by insertion of an electrically safe light into the
mouth (with the lips closed) after removal of any
maxillary prosthesis.
Good transillumination
indicates air in the sinuses, whereas failure of it
indicates the presence of pus, a solid lesion or
mucosal thickening. Transillumination is rarely used
now a days.

 Fibrooptic Antroscopy / Sinus endoscopy-
It is the use of short fiberglass
endoscopes for inspection of nasal cavities and maxillary
sinuses.
Sinuses unresponsive to treatment
or any suspicious areas not seen radiologically can be
examined by direct vision through endoscope. Antroscopy is
the only definitive way to investigate the contents and lining of
maxillary sinus.
The endoscope is inserted through
an inferior meatal puncture, a previously created antral
window ,or the anterior maxillary wall via the buccal sulcus.
It is useful in the diagnosis of
orbital floor fractures. Therapeutic sinus edoscopy is
performed for removal of diseased tissue, lavage and obtaining
specimen for culture .

 Bacteriology & Cytology :-
Puncture of antrum is
performed following topical vasoconstriction with 1:1000
adrenaline and analgesia with 10% cocaine spray through
the inferior meatus with trocar and canula and aspirate is
withdrawn into an empty syringe and bacteriological and
cytological examination is done.

 Nasal mucociliary clearance test :-
It is used to measure mucociliary
function. Particle of saccharine is placed in the anterior
part of the middle meatus and subject is asked to swallow
every 30 seconds and the time between placement and
report of a sweet taste is measured.
It measures the fastest rate of nasal
mucus transport (mean flow rate is 6mm/min).
{The test does not provide specific information
regarding mucociliary transport within antrum but it maybe assumed that
defective nasal transport is likely to be reflected in reduced sinus mucosal
function.}

 Nasal ciliary beat frequency :-
Stripes of ciliated epithelium are
brushed off the lateral aspect of the inferior turbinate and
examined under phase-contrast microscope.
The number of effector strokes of the
cilia per second is counted, the normal range is 12-15Hz,
which is decreased in infections.
This also determines the percentage of
immotile cilia.

 Rhinomanometry :-
It measures the nasal air flow and
pressure at the nostrils during respiration.
The main clinical application is to
determine nasal obstruction.
 Biopsy :-
Any persistent lesion with or without
cause should be biopsied with endoscope for proper
diagnosis and treatment plan.

Radiography
 Periapical Radiographs
 Occlusal radiographs
 Waters view
 Caldwell P-A projection (occipitofrontal view)
 The Lateral skull views
 The submentovertex projection
 Panoramic radiographs
 C T and MRI and
 Other imaging techniques

 Periapical and Occlusal Radiographs :-
Shows floor and relation with upper
posterior teeth.
 Waters view :-
Allows comparison of both maxillary
sinus. If mouth kept open then sphenoid sinus can also
be seen. Usually shows roof, medial and lateral wall.

 Caldwell P-A projection (occipitofrontal view) :-
We get good visualization of frontal sinus,
ethmoidal sinus, nasal cavity and superior portion of
maxillary antrum and posterior aspect of antral floor
which is not seen in waters view.
 The Lateral skull views :-
Examination of sphenoid and maxillary sinus
and specially anterior and posterior walls.

 Submentovertex projection :-
shows posterior wall of maxillary sinus and
sphenoid sinus.
 Panoramic radiographs :-
It is excellent screening radiograph. And
better than waters view for antral floor.

 C T and MRI :-
CT will differentiate well between soft
tissue(mucosal pathologies) and hard tissues.
MRI will not demonstrate bony walls
pathologies but because of surrounding fat the
displacement and destruction of facial muscle is well
demonstrated. Advantage is no ionising radiation used.

 Other imaging techniques includes
 Scintigraphy
 USG
 Angiography.

PATHOLOGIES OF THE
MAXILLARY SINUS
 Developmental anomalies
 Inflammatory diseases
 Cysts of the maxillary sinus
 Traumatic diseases
 Tumors of the maxillary sinus
 Other diseases involving the maxillary sinus

DEVELOPMENTAL ANOMALIES OF THE
MAXILLARY SINUS
 Agenesis / Aplasia
 Hypoplasia - Radiographic images may appear more
radiopaque than normal due to surrounding maxillary
bone.
 Hyperplasia
 Supernumerary maxillary sinus

 Agenesis :- Complete absence of maxillary sinus.
 Aplasia :- It is altered development of maxillary sinus.
 Hypoplasia :- Underdevelopment (9% cases)
unilateral (1.7%)
bilateral (7.2%)
 Hyperplasia :- Excess development of maxillary sinus
e.g. acromegaly

 Supernumerary maxillary sinus :-
Occurrence of two completely
separated sinuses on the same side.
Initiated by out pocketing of nasal
mucosa into the primordium of maxillary body from
two points either in middle nasal meatus or in the
middle and superior or middle and inferior nasal
meatus respectively and thus result in two ostia of
the sinus.

Syndromes affecting maxillary sinus
 Crouzon syndrome :- (Craniofacial dyostosis)
There is early synostosis of the
sutures produce hypoplasia of the maxilla and
therefore maxillary sinus together with high arch
palate resulting in crowding of teeth.
Also shows brachycephaly, hypertelorism and orbital
proptosis.

Crouzon syndrome

 Treacher collins syndrome :- (mandibulofacial
dysostosis)
Features may include
underdeveloped or absence of zygomatic bone,
downward inclination of palpebral fissure
underdeveloped maxillary sinus and mandible,
malformed external ears, high arched or cleft palate

Treacher collins syndrome

 Binder syndrome :- (Maxillonasal dysplasia)
Features include hypoplasia of
middle third of face. There is maxillary sinus
hypoplasia, retrognathic maxilla

Binder syndrome

 Silent sinus syndrome :-
Spontaneous, asymptomatic collapse
of the maxillary sinus and orbital floor associated with
negative sinus pressures. It can cause painless facial
asymmetry , diplopia and enophthalmos. Usually the
diagnosis is suspected clinically, and it can be confirmed
radiologically by characteristic imaging features that
include maxillary sinus outlet obstruction, sinus
opacification, and sinus volume loss caused by inward
retraction of the sinus walls.

enophthalmos of the right eye.

REFERENCES
 B.D. CHAURASIA’S HUMAN ANATOMY, VOL. 3: FOURTH EDITION
 CLINICALLY ORIENTED ANATOMY, MOORE & DALLEY, 5TH
EDITION
 ORBAN’S ORAL HISTOLOY & EMBRYOLOGY, Maxillary sinus. 9TH EDITION
 ORBAN’S ORAL HISTOLOY & EMBRYOLOGY, Maxillary sinus.11TH EDITION
 MAXILLARY SINUS & IT’S DENTAL APPLICATIONS- McGowan .D
 TEXTBOOK OF ORAL MEDICINE: GHOM. Disorders of maxillary sinus
 TEXTBOOK OF ORAL SURGERY- NILIMA MALIK. Pathologies of maxillary sinus.
 GRAY’S ANATOMY, 39TH EDITION. Development of face
 Robin Williamson. Crouzon syndrome, treachers Collin syndrome, Children's
craniofacial association. Dallas: 2005

MAXILLARY SINUS part I / oral surgery courses

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