The Anatomy of the Oral Cavity
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Introduction
Oral cavity extends anteriorly from vermilion
junction of lips to junction of hard and soft
palate above and to line of circumvallate
papillae on dorsal tongue below;
communicates freely with oropharynx
posteriorly
Oral cavity contains buccal mucosa, maxillary
and mandibular arches, retromolar trigone,
anterior 2/3 of tongue, floor of mouth and
hard palate
Dorsal tongue:
villous, normally exposed surface;
contains papillae and specialized taste receptors
Ventral tongue:
nonvillous, undersurface
Anterior 2/3 of tongue (oral tongue):
freely mobile
portion of tongue that extends anteriorly from line of
circumvallate papillae to undersurface of tongue at
junction of floor of mouth; composed of skeletal
muscle, includes 4 areas: tip, lateral borders, dorsum
and undersurface (nonvillous ventral surface of
tongue)
Base of tongue (posterior 1/3 of tongue):
bound
anteriorly by circumvallate papillae, laterally by
glossotonsillar sulci and posteriorly by epiglottis
Buccal mucosa:
all of membrane lining inner surface
of cheeks and lips from line of contact of opposing lips
to line of attachment of mucosa of alveolar ridge
(upper and lower) and pterygomandibular raphe;
contains ostia of main duct of parotid gland (Stenson
duct).
Floor of mouth:
semilunar space of myelohyoid and
hyoglossus muscles, extending from inner surface of
lower alveolar ridge to undersurface of tongue;
posterior boundary is base of anterior pillar of tonsil;
divided into two sides by frenulum of tongue, contains
ostia of submaxillary and sublingual salivary glands
Hard palate:
forms roof of oral cavity;
semilunar surface between upper alveolar
ridge and mucous membrane covering
palatine process of maxillary palatine bones;
extends from inner surface of superior
alveolar ridge to posterior edge of palatine
bone .
Gingiva:
mucosa in area of teeth and palate;
extends from labial sulcus and buccal sulcus
to a cuff of tissue around each tooth.
Lip:
begins at junction of vermilion border
(mucocutaneous junction) with skin, includes
only vermilion surface or that portion of lip that
comes into contact with opposing lip; upper and
lower lip are joined at commissures of mouth;
external surface is skin and mucous membrane;
internally contains orbicularis oris muscle, blood
vessels, nerves, areolar tissue, fat and small
labial glands; inner surface of lip is connected to
gum in midline by frenulum, a mucous
membrane fold.
Lower alveolar ridge:
mucosa overlying alveolar
process of mandible which extends from line of
attachment of mucosa in lower gingivobuccal
sulcus to line of free mucosa of floor of mouth;
posteriorly extends to ascending ramus of
mandible.
Retromolar gingiva (retromolar trigone):
mucosa overlying ascending ramus of mandible
from level of posterior surface of last molar
tooth to apex superiorly, adjacent to tuberosity
of maxilla.
Tonsillar area:
anterior and posterior tonsillar
pillars and tonsillar fossa
Upper alveolar ridge:
mucosa overlying
alveolar process of maxilla which extends
from line of attachment of mucosa in upper
gingivobuccal sulcus to junction of hard
palate; posterior margin is upper end of
pterygopalatine arch
Vermillion border:
mucocutaneous junction
of lip
Epithelium: Stratified squamous epithelium often
with parakeratosis
No hair follicles or sweat glands present
Keratinization in areas most exposed to mastication
(gingiva, hard palate, dorsum of tongue)
Lamina propria contains loose connective tissue,
mucous glands, serous minor salivary type glands
Submucosa has dense collagenous fibrous tissue.
Oral tongue mucosa: modified keratinized squamous
epithelium with small papillae; papillae can be filiform
(majority, conical projections of keratinized epithelium),
fungiform (rounded elevations, nonkeratinized), foliate
(along sides of tongue) or cirucumvallate (at junction of
anterior 2/3 and posterior 1/3 tongue, largest papillae).
Taste buds: barrel shaped, lightly staining, intramucosal
sensory receptors present in large numbers on circumvallate
papillae and in lesser numbers elsewhere .
Intraepithelial nonkeratinocytes: melanocytes (basal),
Merkel cells (basal), Langerhans cells (suprabasal) and
lymphocytes occur in oral mucosa.
Ectopic sebaceous glands (Fordyce spots)
increase with age in adults
Tonsillectomy specimens frequently contain
skeletal muscle.
Oral epithelium expresses
cytokeratin 5
and
14
,
ABO blood group antigens
Taste buds express
low molecular weight
keratins
, such as
CK18
and
CAM5.2
Ectoderm/ ameloblsts/ enamel matrix
Mesoderm/ odentoblast/ dental matrix
Dentin / enamel / cementum
Dental pulp
Dental caries
Periodontal Pathology
Cysts
Odentogenic tumor
Bone diseases
Infectious diseases
Developmental abnormality
Indications:
Alteration from normal
: When it is not possible to
identify the condition clinically, a histopathological
investigation is necessary.
Evaluation of histological nature
: to evaluate the
exact histological nature of any soft tissue or intra-
osseous lesion.
Screening of abnormal tissue
:
Confirmation of diagnosis:
Evaluation of nonneoplastic lesion
: such as
mucosal nodules,papilloma,erosive lichen planus,
erythema multiforme, lupus erythematous
pemphigus, pemphigoid and desquamative gingivitis.
Contraindication :
Inflammatory lesion
: Biopsy is not usually
indicated in acute infalmmatory lesion.
Site near the vital structure
: One should be
very careful while performing biopsy of the
lesion adjacent to vital structure.
Angiomatous lesion
: Unless it is needed you
shouldn’t go for the biopsy of angiomatous
lesion.
Biopsy should not be delayed when following features are
present:
Rapid increase in size
of the lesion that cannot be
explained by inflammation, edema and opening of new
vascular channels.
Absence of any recognized irritant
, particularly when the
lesion is chronically ulcerated or bleeds spontaneously.
Presence of firm regional lymph nodes
, especially when
they seem to be fixed to surrounding tissues.
Destruction of roots and loosening of teeth
with
evidence of rapid expansion of the jaw History of
malignancy elsewhere in the body, previous history of oral
cancer and radiation therapy.
Application of Biopsy in Dentistry
•
Diagnosis of pathologic lesions
•
Determining neoplastic and non-neoplastic
lesions
•
Therapeutic assessment
•
Grading of tumor
•
Diagnosis of metastatic lesions
•
Evaluation of recurrence
Complication of Biopsy
•
Hemorrhage
•
Infection
•
Poor biopsy wound
healing
•
Spread to adjacent organs and reaction to
local
anesthesia.
Ideal Requirement of Biopsy Tissue Less
traumatized:
o
The tissue taken for biopsy should have minimal
trauma.
o
Adequate representative tissue: It must include
the most suitable representative pathologic
region of a lesion for a pathologist to interpret.
o
To facilitate treatment: Biopsy sample should
help to facilitate to prescribed treatment and
assess its efficacy.
Teeth specimen: For the histologic examination of
teeth, the apex of tooth should be clipped with a pair
of pliers or a small hole should be drilled into the
radicular pulp with dental bur to allow penetration of
the fixative. The excellent preservation of cellular
detail required is obtained by following methods: ∙
Cutting the specimen into tiny blocks before fixation. ∙
Use of special fixatives that preserve cellular detail
with minimum disruption from rapid dehydration or
osmotic shock. ∙ Post fixation and processing of
tissues in the laboratory after the initial period of
prefixation. As soon as possible after the surgical
procedure.
Incisional Biopsy
: can be performed by
removing a wedge shaped specimen of the
pathological tissue along with surrounding
normal zone.
Indications:
Large lesion: If the lesion is large and diffuse
and extends deeply into the surrounding
tissue so that total removal cannot be
obtained easily with local anesthesia, an
incisional biopsy is indicated.
Management point of view: Lesions in which
diagnosis will determine whether the
treatment should be conservative or radical.
Excisional Biopsy:
Total excision of a small lesion for microscopic
examination is called as ‘excisional biopsy’.
It is a therapeutic as well as a diagnostic
procedure.
Normal tissue on the margins of the lesion
should be included.
It is indicated when the lesion is relatively small
and less than 1 cm in diameter, sessile or
pedunculated and well circumscribed; Tissues
which are freely movable and located above the
mucosa or just beneath the surface.
It is the preferred treatment if, the size of lesion
is such that it may be removed along with the
margins of normal tissue and wound can be
closed primarily.
Contraindication Larger lesions than 2 to 4 cm—
more cases are to be operated with proper
surgical planning and anesthesia Vascular
lesions—e.g. hemangioma Tumors adherent to
important vital structures or major blood
vessels.
Exfoliative cytology:
is a technique in which exfoliated cells
assessed for pathological change.
The cells examined are either manually
scraped (mechanical exfoliation) or they are
the cells which are spontaneously exfoliated.
Exfoliative cytology is an attractive option for early
diagnosis of oral cancer including atypias and
squamous cell carcinomas.
It is a useful tool for detection, monitoring of initial
alterations and establishment of adequate treatment.
Recent advances in exfoliative cytology such as
development of cytomorphometric method, DNA
content determination, detection of tumor markers
has contributed to renewed interest in this field. In
this, the surface of the lesion is either wiped with
some sponge material or scraped to make a smear.
Oral mucosal brush biopsy:
This technique utilizes a disposable brush to
collect a transepithelial sampling of cells.
This brush has got 2 cutting surfaces i.e. flat end
and circular border.
Specimen obtained
brushing on the site and smeared on clean
labelled glass slide.
The sample is screened by an neurally
networked computer that is programmed to
detect cytologic changes associated with
premalignancy and squamous cell ca.
The oral cavity extends from the lips to the hard and soft palate and houses various structures like the tongue, buccal mucosa, floor of the mouth, hard palate, gingiva, and lips. This detailed overview covers the different regions of the tongue, mucosal linings, salivary glands, and palatal structures, providing valuable insights into oral anatomy.
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Presentation Transcript
Oral cavity extends anteriorlyfrom vermilion junction of lips to junction of hard and soft palate above and to line of circumvallate papillae on dorsal tongue below; communicates freely with oropharynx posteriorly Oral cavity contains buccalmucosa, maxillary and mandibulararches, retromolartrigone, anterior 2/3 of tongue, floor of mouth and hard palate
Dorsal tongue:villous, normally exposed surface; contains papillae and specialized taste receptors Ventral tongue:nonvillous, undersurface Anterior 2/3 of tongue (oral tongue):freely mobile portion of tongue that extends anteriorlyfrom line of circumvallate papillae to undersurface of tongue at junction of floor of mouth; composed of skeletal muscle, includes 4 areas: tip, lateral borders, dorsum and undersurface (nonvillous ventral surface of tongue) Base of tongue (posterior 1/3 of tongue):bound anteriorlyby circumvallate papillae, laterally by glossotonsillarsulci and posteriorly by epiglottis
Buccal mucosa:all of membrane lining inner surface of cheeks and lips from line of contact of opposing lips to line of attachment of mucosa of alveolar ridge (upper and lower) and pterygomandibular raphe; contains ostiaof main duct of parotid gland (Stenson duct). Floor of mouth:semilunar space of myelohyoid and hyoglossusmuscles, extending from inner surface of lower alveolar ridge to undersurface of tongue; posterior boundary is base of anterior pillar of tonsil; divided into two sides by frenulum of tongue, contains ostiaof submaxillary and sublingual salivary glands
Hard palate:forms roof of oral cavity; semilunarsurface between upper alveolar ridge and mucous membrane covering palatine process of maxillary palatine bones; extends from inner surface of superior alveolar ridge to posterior edge of palatine bone . Gingiva: mucosa in area of teeth and palate; extends from labial sulcus and buccalsulcus to a cuff of tissue around each tooth.
Lip: begins at junction of vermilion border (mucocutaneousjunction) with skin, includes only vermilion surface or that portion of lip that comes into contact with opposing lip; upper and lower lip are joined at commissures of mouth; external surface is skin and mucous membrane; internally contains orbicularis orismuscle, blood vessels, nerves, areolar tissue, fat and small labial glands; inner surface of lip is connected to gum in midline by frenulum, a mucous membrane fold.
Lower alveolar ridge:mucosa overlying alveolar process of mandible which extends from line of attachment of mucosa in lower gingivobuccal sulcusto line of free mucosa of floor of mouth; posteriorlyextends to ascending ramus of mandible. Retromolar gingiva (retromolar trigone): mucosa overlying ascending ramus of mandible from level of posterior surface of last molar tooth to apex superiorly, adjacent to tuberosity of maxilla.
Tonsillar area: anterior and posterior tonsillar pillars and tonsillarfossa Upper alveolar ridge:mucosa overlying alveolar process of maxilla which extends from line of attachment of mucosa in upper gingivobuccalsulcus to junction of hard palate; posterior margin is upper end of pterygopalatinearch Vermillion border:mucocutaneous junction of lip
Epithelium: Stratified squamous epithelium often with parakeratosis No hair follicles or sweat glands present Keratinization in areas most exposed to mastication (gingiva, hard palate, dorsum of tongue) Lamina propria contains loose connective tissue, mucous glands, serous minor salivary type glands
Submucosahas dense collagenous fibrous tissue. Oral tongue mucosa: modified keratinized squamous epithelium with small papillae; papillae can be filiform (majority, conical projections of keratinized epithelium), fungiform(rounded elevations, nonkeratinized), foliate (along sides of tongue) or cirucumvallate (at junction of anterior 2/3 and posterior 1/3 tongue, largest papillae). Taste buds: barrel shaped, lightly staining, intramucosal sensory receptors present in large numbers on circumvallate papillae and in lesser numbers elsewhere . Intraepithelial nonkeratinocytes: melanocytes (basal), Merkel cells (basal), Langerhans cells (suprabasal) and lymphocytes occur in oral mucosa.
Ectopic sebaceous glands (Fordyce spots) increase with age in adults Tonsillectomy specimens frequently contain skeletal muscle. Oral epithelium expresses cytokeratin 5and 14, ABO blood group antigens Taste buds express low molecular weight keratins, such as CK18and CAM5.2
Ectoderm/ ameloblsts/ enamel matrix Mesoderm/ odentoblast/ dental matrix Dentin / enamel / cementum Dental pulp
Dental caries Periodontal Pathology Cysts Odentogenictumor Bone diseases Infectious diseases Developmental abnormality
Indications: Alteration from normal: When it is not possible to identify the condition clinically, a histopathological investigation is necessary. Evaluation of histological nature: to evaluate the exact histological nature of any soft tissue or intra- osseous lesion. Screening of abnormal tissue: Confirmation of diagnosis: Evaluation of nonneoplastic lesion: such as mucosal nodules,papilloma,erosive lichen planus, erythemamultiforme, lupus erythematous pemphigus, pemphigoid and desquamativegingivitis.
Contraindication : Inflammatory lesion: Biopsy is not usually indicated in acute infalmmatorylesion. Site near the vital structure: One should be very careful while performing biopsy of the lesion adjacent to vital structure. Angiomatous lesion: Unless it is needed you shouldn t go for the biopsy of angiomatous lesion.
Biopsy should not be delayed when following features are present: Rapid increase in size of the lesion that cannot be explained by inflammation, edema and opening of new vascular channels. Absence of any recognized irritant, particularly when the lesion is chronically ulcerated or bleeds spontaneously. Presence of firm regional lymph nodes, especially when they seem to be fixed to surrounding tissues. Destruction of roots and loosening of teeth with evidence of rapid expansion of the jaw History of malignancy elsewhere in the body, previous history of oral cancer and radiation therapy.
Application of Biopsy in Dentistry Diagnosis of pathologic lesions Determining neoplasticand non-neoplastic lesions Therapeutic assessment Grading of tumor Diagnosis of metastatic lesions Evaluation of recurrence
Complication of Biopsy Hemorrhage Infection Poor biopsy woundhealing Spread to adjacent organs and reaction to local anesthesia.
Ideal Requirement of Biopsy Tissue Less traumatized: o The tissue taken for biopsy should have minimal trauma. o Adequate representative tissue: It must include the most suitable representative pathologic region of a lesion for a pathologist to interpret. o To facilitate treatment: Biopsy sample should help to facilitate to prescribed treatment and assess its efficacy.
Teeth specimen: For the histologicexamination of teeth, the apex of tooth should be clipped with a pair of pliers or a small hole should be drilled into the radicularpulp with dental bur to allow penetration of the fixative. The excellent preservation of cellular detail required is obtained by following methods: Cutting the specimen into tiny blocks before fixation. Use of special fixatives that preserve cellular detail with minimum disruption from rapid dehydration or osmotic shock. Post fixation and processing of tissues in the laboratory after the initial period of prefixation. As soon as possible after the surgical procedure.
Incisional Biopsy: can be performed by removing a wedge shaped specimen of the pathological tissue along with surrounding normal zone.
Indications: Large lesion: If the lesion is large and diffuse and extends deeply into the surrounding tissue so that total removal cannot be obtained easily with local anesthesia, an incisionalbiopsy is indicated. Management point of view: Lesions in which diagnosis will determine whether the treatment should be conservative or radical.
Excisional Biopsy: Total excision of a small lesion for microscopic examination is called as excisional biopsy . It is a therapeutic as well as a diagnostic procedure. Normal tissue on the margins of the lesion should be included. It is indicated when the lesion is relatively small and less than 1 cm in diameter, sessile or pedunculatedand well circumscribed; Tissues which are freely movable and located above the mucosa or just beneath the surface.
It is the preferred treatment if, the size of lesion is such that it may be removed along with the margins of normal tissue and wound can be closed primarily. Contraindication Larger lesions than 2 to 4 cm more cases are to be operated with proper surgical planning and anesthesia Vascular lesions e.g. hemangiomaTumors adherent to important vital structures or major blood vessels.
Exfoliative cytology: is a technique in which exfoliated cells assessed for pathological change. The cells examined are either manually scraped (mechanical exfoliation) or they are the cells which are spontaneously exfoliated.
Exfoliativecytology is an attractive option for early diagnosis of oral cancer including atypias and squamouscell carcinomas. It is a useful tool for detection, monitoring of initial alterations and establishment of adequate treatment. Recent advances in exfoliativecytology such as development of cytomorphometric method, DNA content determination, detection of tumor markers has contributed to renewed interest in this field. In this, the surface of the lesion is either wiped with some sponge material or scraped to make a smear.
Oral mucosal brush biopsy: This technique utilizes a disposable brush to collect a transepithelial sampling of cells. This brush has got 2 cutting surfaces i.e. flat end and circular border. Specimen obtained brushing on the site and smeared on clean labelled glass slide. The sample is screened by an neurally networked computer that is programmed to detect cytologicchanges associated with premalignancyand squamous cell ca.
