The document discusses mandibular invasion by squamous cell carcinoma and its implications for management. It begins by describing the anatomy of the mandible and routes of tumor invasion. Imaging tools like CT, MRI and bone scintigraphy can detect invasion, but often require resection to confirm. Segmental mandibulectomy is indicated for gross invasion, while marginal resection suffices for minimal involvement. Reconstruction with fibula flap allows implant-based dentition. While marginal resection maintains function, segmental resection with microvascular reconstruction achieves similar quality of life. Prognosis depends more on bone involvement than resection extent.

1. Mandibular invasion and its
significance in management
Dr Yash Chaddha
Fellow Head and neck Oncology
BL Kapur Hospital
New Delhi

5. RAMUS OF MANDIBLE
Is quadrilateral
2 surfaces
Lateral
Medial
4 borders
Superior
Inferior
Anterior
Posterior
2 processes
Coronoid
Condylar

6. ON THE LATERAL
SURFACE:
1. From The Oblique line :
Buccinator, and depressor anguli
oris below the mental foramen
2. Incisive fossa:
gives origin to MENTALIS mental
slips of ORBICULARIS ORIS.
3. Whole of lateral surface of
ramus except posterosuperior part
provides insertion to MASSETER.
4.Posterosuperior part : covered
by PAROTID GLAND

7. 1. Digastric fossa: arises
ANTERIOR BELLY OF
DIGASTRIC
2. Genial tubercles: arises
GENIOGLOSSUS and
GENIOHYOID.
3. Mylohyoid line : arises
MYLOHYOID MUSCLE.
4. From an area above the
posterior end of mylohyoid line:
arises SUPERIOR
CONSTRICTOR OF PHARYNX.
5. Pterygomandibular raphe:
Attached immediately behind the
third molar tooth in continuation
with the origin of superior
constrictor
ON THE MEDIAL SURFACE

8. • The mandibular alveolus
represents that part of the
mandible that is ‘intraoral’.
• The osseous alveolar
process of the mandible
supports the dentition and
is covered by a
mucoperiosteum.
• The mandibular alveolus
merges laterally with the
buccal mucosa/lips at the
gingival sulcus and
medially with the floor of
mouth.

9. • The alveolar process
extends to the
retromolar trigones
posteriorly. Sensory
innervation to the
mandibular alveolus
is by the mandibular
division of the
trigeminal nerve

10. • Lymphatic drainage is to the ipsilateral
submandibular and submental nodes to the
deep cervical chain.
• Lymphatic drainage towards the midline may
be bilateral.

11. MANAGEMENT OF THE MANDIBLE
• Tumours of the mandibular alveolus, the floor
of mouth, buccal mucosa or retromolar
trigone may involve the bone of the mandible.
Involvement of the mandible has significant
consequences regarding management of the
patient.
• Several questions need to be answered when
managing a patient with potential mandibular
involvement.

12. • How does squamous cell carcinoma invade
the mandible?
• How do we manage bone involvement?
• How does bone involvement influence
prognosis?
• What are the quality of life implications?

13. How does squamous cell carcinoma
invade the mandible?
• Squamous cell carcinoma (SCC) invades the mandible
either in an invasive or erosive manner.
• Invasive tumours demonstrate fingers or islands of
tumour advancing deeply into bone with no obvious
osteoclastic activity.
• Erosive tumours have a broad advancing front with
osteoclast activity and connective tissue between the
tumour and bone, although as the depth of invasion
increases, they may become more invasive in character.
• Large, deeply invading tumours are more likely to
demonstrate an invasive pattern of spread and involve
the mandible

14. Invasive pattern in which separate islands of tumor
start to invade in front of the main tumor mass, and the
connective tissue barrier is lost
• Carter RL, Tsao SW, Burman JF, Pittam MR, Clifford P, Shaw HJ. Patterns and
mechanisms of bone invasion by squamous carcinomas of the head and neck. Am J
Surg 1983;146:451􏰀455.

15. Erosive pattern of invasion of the mandible showing a connective
tissue band separating the tumor from the bone
• Carter RL, Tsao SW, Burman JF, Pittam MR, Clifford P, Shaw HJ. Patterns and
mechanisms of bone invasion by squamous carcinomas of the head and neck. Am J
Surg 1983;146:451􏰀455.

16. Routes of tumor entry
• Controversy still exists over the favored
pathway of tumor entry into the mandible.
Seven possible routes of tumor entry have
been discussed
• From the oral cavity through the upper
surface of the mandible (occlusal route)
• Through the mental foramen
• Secondary tumors in the neck through the
lower border
• The mandibular foramen
• Cortical bone defects in the edentulous
ridge
• Periodontal membrane in the dentate
mandible
• The attached gingiva
• McGregor AD, MacDonald DG: Routes of entry
of squamous cell carcinoma to the mandible.
Head Neck 1988, 10:294–301.

17. • The tumor does not extend directly through
intact periosteum and cortical bone toward
the cancellous part of the mandible because
the periosteum acts as a significant protective
barrier.

18. • Instead, the tumor
advances from the
attached gingiva
toward the alveolus.
• In patients with
teeth, the tumor
extends through the
dental socket into
the cancellous part
of the bone and
invades the
mandible via that
route.

19. In edentulous patients, the
tumor extends up to the
alveolar process and then
infiltrates the dental pores in
the alveolar ridge and extends
to the cancellous part of the
mandible

20. • Thus in patients with tumors approaching the
mandible without infiltration of the tooth
sockets, a marginal mandibulectomy is
feasible.
• In edentulous patients, however, the
feasibility of marginal mandibulectomy
depends on the vertical height of the body of
the mandible.
• With aging, the alveolar process recedes and
the mandibular canal comes closer to the
surface of the alveolar process

21. • Resorption of the alveolar process eventually
leads to a “pipestem” mandible in elderly
patients. It is almost impossible to perform a
marginal mandibulectomy in such patients
because the probability of iatrogenic fracture
or postsurgical spontaneous fracture of the
remaining portion of the mandible is very
high.

22. • Similarly, in patients who have received
previous radiotherapy, a marginal
mandibulectomy should be performed with
extreme caution. The probability of pathologic
fracture at the site of the marginal
mandibulectomy in such patients is very high.

23. • The concept of the
“commando operation”
has been revised
because no lymphatic
channels pass through
the mandible, and thus
the need for an in-
continuity “composite
resection” of the
uninvolved mandible is
not warranted
– Head and neck surgery
and oncology, Jatin
P.Shah, 5th edition

24. The current indications for a
segmental mandibulectomy include
• (1) gross invasion by oral cancer;
• (2) invasion of inferior alveolar nerve or canal
by the tumor
• (3) massive soft-tissue disease adjacent to the
mandible
• (4) a primary malignant tumor of the
mandible; and
• (5) a tumor that has metastasized to the
mandible.

25. Indications for Marginal
Mandibulectomy
• Primary tumor abutting against the mandible
• Minimal involvement of the alveolar process
• Minimal cortical erosion

26. How do we detect bony invasion?
• Preoperative imaging of the mandible is
necessary to determine if bone resection is
required, and if so the appropriate type of
resection.

27. • At present, there is no single investigation that can reliably
predict bone invasion.
• An OPG radiograph should be requested for all cancer
patients. This plain radiograph is not only useful for
demonstrating bony invasion, but also for assessing
mandibular height, dental anatomy and dental pathology.
• plain radiographs do not detect initial invasion until 30 per
cent demineralization has occurred, giving rise to reduced
sensitivity.
• Clinical examination and OPG alone are probably
inadequate for accurate assessment of mandibular
invasion.

28. • Sensitivity -76%, Specifity -81%

29. A computed tomography scan of the oral cavity. A, Soft tissue
algorithm. B, Bone algorithm showing the extent of mandible
involvement.
• Sensitivity -75%, Specifity -86%

30. • Axial MRI views with T1 and STIR fat suppression
are very sensitive for imaging the primary site of
oral cancer with an adequate specificity.
– Bolzoni A, Cappiello J, Piazza C et al. Diagnostic accuracy of magnetic resonance imaging
in the assessment of mandibular involvement in oral-oropharyngeal squamous cell
carcinoma: a prospective study. Archives of Otolaryngology – Head and Neck Surgery
2004
Bone scintigraphy or single-photon emission
computed tomography (SPECT) may be considered
in equivocal cases.

31. Squamous cell carcinoma of the lower gum (A). Axial (B) and
coronal (C) views of T1-weighted magnetic resonance imaging
shows normal fatty bone marrow (black arrows) and bone
marrow involved by tumor (white arrows).
• Sensitivity -85%, Specifity -72%

33. How do we manage bone
involvement?
• Surgical resection of the mandible becomes
necessary when a primary malignant tumor of
the oral cavity involves the mandible or directly
extends to the gingiva over the alveolar process
or infiltrates into the mandible.
• If the tumor extends directly from the alveolar
process to the cancellous part of the mandible or
if contiguous tumor infiltration to the lingual or
lateral cortex of the mandible is present, a
segmental mandibulectomy becomes necessary .

34. How do we manage bone
involvement?
• A marginal
mandibulectomy can be
performed to resect the
alveolar process, the
lingual cortex of the
mandible, or both for
tumors of the oral
cavity.
• A marginal
mandibulectomy can
also be performed for
lesions adjacent to the
retromolar trigone

35. • A marginal mandibulectomy of the a)symphysis of the mandible b) body of
the mandible c) retromolar trigone and coronoid process of the mandible

36. • A reverse marginal mandibulectomy is
indicated in patients who have soft-tissue
disease such as fixation of prevascular facial
lymph nodes to the lower cortex of the
mandible.

38. • In performing a marginal
mandibulectomy, right-
angled cuts at the site of
the marginal
mandibulectomy should be
avoided, because they lead
to points of excessive
stress, which leads to the
risk of spontaneous
fracture.
• The marginal
mandibulectomy should be
performed in a smooth
curve to evenly distribute
the stress at the site of
resection

39. • The exposed bone following a
marginal mandibulectomy is
covered by
– primary closure between the
mucosa of the tongue or floor of
the mouth to the mucosa of the
cheek
– A split-thickness skin graft, or
– A free flap.
• However, it must be remembered
that
• primary closure will eliminate the
lingual or the buccal sulcus,
rendering fabrication of a
removable denture exceedingly
difficult.

40. A removable denture
• Alternatively, a skin graft
can be applied directly over
the marginally resected
mandible, which would
permit retention of the
sulci and the ability of the
patient to wear a partial
denture that can be clasped
to the remaining teeth.
• Ideally, an implant-based
permanent or removable
denture that provides
better stability and permits
mastication would be
desirable.

41. • Unfortunately, there are limitations in
implant placement after marginal
mandibulectomy because of insufficient
bone height between the alveolar crest
and the mandibular canal.
• A minimum of 10 mm of bone height is
necessary to even consider short implants.
• That much bone height is not available
after marginal mandibulectomy.
• Therefore implant-based dental
rehabilitation is not possible in the lateral
segment (premolar and molar) of the
mandible.
• On the other hand, implant-based denture
can be easily performed in the anterior
segment of the mandible (between the
mental foramina) where sufficient bone
height is available to consider even the
standard 10 mm high implants.

42. Peroral Marginal Mandibulectomy and Primary
Closure

43. Marginal Mandibulectomy and Skin
Graft Reconstruction

45. • Therefore, if optimal dental rehabilitation is
the ultimate goal in patients who are suitable
for marginal mandibulectomy, then
consideration should be given to segmental
mandibulectomy and fibula free flap
reconstruction with immediate placement of
dental implants in the fibula.

46. Segmental Mandibulectomy
• When resection of a segment of the mandible
is indicated for carcinoma of the oral cavity,
immediate reconstruction of the resected
mandible should be considered.
• Resection of the body of the mandible
produces
– significant aesthetic deformities
– functions of speech and mastication are seriously
compromised.

47. • The impact of resection
of the anterior arch is
even more devastating.
• Many patients drool
saliva after resection of
the anterior arch of the
mandible and have
significant swallowing
difficulties.
• The optimal method of
reconstruction of the
resected mandible at the
present time is with a
fibula free flap.

48. • The patient
shown in Fig had
arch resection
without
immediate
reconstruction.

49. Segmental Mandibulectomy and
Reconstruction With a Fibula Free Flap

50. How does bone involvement influence
prognosis?
• If the planned resection of mandible follows
the guidelines set out above, then long-term
prognosis and recurrence does not differ
between marginal resection and segmental
resection.
– Wolff D, Hassfeld S, Hofele C. Influence of marginal and segmental mandibular
resection on the survival rate in patients with squamous cell carcinoma of the
inferior parts of the oral cavity. Journal of Cranio-Maxillo-Facial Surgery 2004
• The presence of bone involvement, rather
than the depth of bone invasion, is the main
determining factor of long-term prognosis.

51. • It has been proposed that only tumours with an
invasive tumour front as opposed to an erosive front
be classified as T4 tumours.
– Shaw RJ, Brown JS, Woolgar JA et al. The influence of the pattern of mandibular invasion
on recurrence and survival in oral squamous cell carcinoma. Head and Neck 2004;
• It is thought that local recurrence following bony
resection is usually as a consequence of soft tissue
margin status rather than the method of mandibular
resection.
– O’Brien CJ, Adams JR, McNeil EB et al. Influence of bone invasion and extent of
mandibular resection on local control of cancers of the oral cavity and oropharynx.
International Journal of Oral and Maxillofacial Surgery 2003

52. What are the quality of life
implications?
• Rim resection of the mandible maintains bony
continuity
• Excellent functional and cosmetic outcome.
• Maintains the structural integrity of the
mandible
• Preserves sensation of the lower lip and
muscular attachments.
• With modern reconstructive techniques, the
Andy Gump deformity should no longer be
encountered.

53. • It is recognized that whenever oncologically sound, a
rim resection should be the resection of choice.
• However, it has been demonstrated that there is little
or no difference in quality of life between a rim
resection and segmental resection with composite
microvascular free tissue transfer, particularly when
the resection is greater than 5 cm.
Rogers SN, Devine J, Lowe D et al. Longitudinal health- related
quality of life after mandibular resection for oral cancer: a
comparison between rim and segment. Head and Neck 2004;

54. Take home points
• Mandible reconstruction is not necessary
following a marginal mandibulectomy, since the
mandibular arch is preserved, and thus its
aesthetic impact is minimal.
• However, satisfactory dental and functional
rehabilitation remains an issue.
• On the other hand, following a segmental
mandibulectomy, immediate mandible
reconstruction must be considered, unless there
are medical contraindications to a long free flap
procedure

55. THANK YOU