Surgical anatomy of Periodontium and related structures

2. Introduction
A sound knowledge of the anatomy of the
periodontium and the surrounding hard and soft
structures is essential to determine the scope and
possibilities of periodontal and implant surgical
procedures and to minimize their risks.
 Bones, muscles, blood vessels, and nerves, as well as
the anatomic spaces located in the vicinity of the
periodontal/implant surgical field, are particularly
important

3. Mandible
The mandible is a horseshoe-shaped bone connected
to the skull by the temporomandibular joints.
 It presents several landmarks of great surgical
importance for both periodontal and implant surgical
procedures.

5. In the premolar area, the mandibular canal divides in
two branches, with one exiting the mandible and the
other continuing anteriorly:
 the incisive canal, which continues horizontally to
the midline,
and the mental canal, which turns upward and opens
in the mental foramen.

6. Mental foramen
The mental foramen, from which the mental nerve
and vessels emerge, is located on the buccal surface
of the mandible below the apices of the premolars,
sometimes closer to the second premolar and usually
halfway between the lower border of the mandible
and the alveolar margin

7. Mental foramen

8. As it emerges, the mental nerve divides into three
branches.
1.One branch of the nerve turns forward and
downward to supply the skin of the chin.
2. The other two branches course anteriorly and
upward to supply the skin and mucous membrane of
the lower lip and the mucosa of the labial alveolar
surface.

9. Clinical implications
1.Surgical trauma (e.g., pressure, manipulation, and
postsurgical swelling) to the mental nerve can
produce paresthesia of the lip, which recovers slowly.
Partial or complete cutting of the nerve can result in
permanent paresthesia .

10. 2.In partially or totally edentulous jaws, the
disappearance of the alveolar portion of the mandible
brings the mandibular canal and mental foramen
closer to the superior border
 This may lead to discomfort for the patient

11. Lingual nerve
The lingual nerve, along with the inferior alveolar
nerve, is a branch of the posterior division of the
mandibular nerve and descends along the mandibular
ramus medial to and in front of the inferior alveolar
nerve.
The lingual nerve lies close to the surface of the oral
mucosa in the third molar area and goes deeper as it
travels forward.

13. Surgical importance
It can be damaged during anesthetic injections and
during oral surgery procedures such as third molar
extractions.
 Less often, the lingual nerve may be injured when a
periodontal partial-thickness flap is raised in the third
molar region or when releasing incisions are made in
the area.

14. Alveolar process
The alveolar process, which provides the supporting
bone to the teeth, has a narrower distal curvature
than the body of the mandible creating a flat surface
in the posterior area between the teeth and the
anterior border of the ramus.
 This results in the formation of the external oblique
ridge, which runs downward and forward to the
region of the second or first molar creating a shelf
like bony area

15. Surgical importance
Resective osseous therapy may be difficult or
impossible in this area because of the amount of bone
that must be removed distally toward the ramus to
achieve resection of a periodontal osseous defect on
the distal aspect of the mandibular second/third
molar.

16. Distal to the third molar, the external oblique ridge
circumscribes the retromolar triangle

17. Surgical importance
This region is occupied by glandular and adipose
tissue and covered by unattached, nonkeratinized
mucosa.
If sufficient space exists distal to the last molar, a
band of attached gingiva may be present; only in such
a case can a distal flap procedure be performed
effectively.

18. Mylohyoid ridge
The medial side of the body of the mandible is
traversed obliquely by the mylohyoid ridge, which
starts close to the alveolar margin in the third molar
area and continues anteriorly in an apical direction,
increasing its distance from the osseous margin as it
travels forward
Attachment of mylohyoid
muscle
Lingual nerve
Inferior alveolar nerve

19. Maxilla
The maxilla is a paired bone that is hollowed out by the
maxillary sinus and nasal cavity.
 The maxilla has the following four processes:
• The alveolar process contains the sockets for and
supports the maxillary teeth.
• The palatine process extends horizontally from the
alveolar process to meet its counterpart from the
opposite maxilla at the midline intermaxillary suture.

20.  The zygomatic process extends laterally from the
area above the first molar and determines the depth
of the vestibular fornix on the lateral aspect of the
maxilla.
 The frontal process extends in an ascending direction
and articulates with the frontal bone at the
frontomaxillary suture

21. The terminal branches of the nasopalatine nerve and
vessels pass through the incisive canal, which opens in
the midline anterior area of the palate

22. Greater palatine foramen
The greater palatine foramen opens 3 to 4 mm
anterior to the posterior border of the hard palate

23. Surgical importance
Palatal flaps and donor sites for gingival grafts should
be carefully performed and selected to avoid invading
these areas because profuse hemorrhage may ensue,
particularly if vessels are damaged at the palatine
foramen.
Vertical incisions in the molar region should be
avoided.

24. Hard palate
The mucous membrane covering the hard palate is
firmly attached to the underlying bone.
The submucous layer of the palate posterior to the
first molars contains the palatal glands, which are
more compact in the soft palate and extend
anteriorly, filling the gap between the mucosal
connective tissue and the periosteum and protecting
the underlying vessels and nerve

25. Maxillary tuberosity
The area distal to the last molar, called the maxillary
tuberosity, consists of the posterior-inferior angle of the
infratemporal surface of the maxilla.
Medially it articulates with the pyramidal process of the
palatine bone.
 It is covered by dense, fibrous connective tissue and
contains the terminal branches of the middle and
posterior palatine nerves.

26. Surgical importance
Excision of the area for distal flap surgery may reach
medially to the tensor palati muscle.
The tensor palati muscle comes from the greater
wing of the sphenoid bone and ends in a tendon that
forms the palatine aponeurosis, which expands,
fanlike, to attach to the posterior border of the hard
palate.

27. Maxillary sinus
The body of the maxilla is occupied by the maxillary
sinus, which is the largest of the paranasal sinuses.
 It is an air-filled cavity located in the posterior
maxilla superior to the teeth.
Boundaries
Base - lower portion of lateral wall of nose
Apex – project into zygomatic process of maxilla
Anterolateral – fascial surface of maxilla
Superior – orbital plate of maxilla
Inferior – alveolar and palatine process of maxilla

29. The maxillary sinus is frequently subdivided
(incompletely) into recesses by one or more septa.
Maxillary sinus septa vary in size and location.
The entire maxillary sinus is lined with a thin mucosal
membrane called the schneiderian membrane
The specialized structure of the respiratory mucous
membrane, with its motile cilia and rich blood supply,
is well adapted to purifying, moistening, and warming
air to protect the lungs.

30. The maxillary sinus drains into the middle meatus of
the nasal cavity through the maxillary duct, which
passes secretions medially to the semilunar hiatus.

31. With increasing age the maxillary sinus expands,
becoming more and more pneumatized down around
the roots of the maxillary teeth, sometimes resulting
in exposure of the roots through the bony floor into
the sinus, with only the thin mucosal membrane
covering the root surface.
The ability to perform periodontal osseous surgery in
the posterior maxilla may be limited when sinuses are
severely pneumatized

32. Blood supply
 from the superior alveolar (anterior, middle, and
posterior) branches of the maxillary artery

33. Surgical importance
Knowledge of the arterial blood supply is particularly
important when considering a lateral window
approach to sinus floor elevation and bone
augmentation
The inferior wall of the maxillary sinus is frequently
separated from the apices and roots of the maxillary
posterior teeth by a thin, bony plate .
 In edentulous posterior areas the maxillary sinus
bony wall may be only a thin plate in intimate contact
with the alveolar mucosa

35. Exostosis
Both the maxilla and the mandible- which are
considered to be within the normal range of anatomic
variation.
 Sometimes these structures may hinder the removal
of plaque by the patient and may have to be removed
to improve the prognosis of neighboring teeth.
 Additional indications for the removal of exostoses
-the inability to comfortably wear removable
prostheses over these areas.

36. The most common location of a mandibular torus is in
the lingual area of canine and premolars, above the
mylohyoid muscle

37. Maxillary tori are usually located in the midline of the
hard palate

38. Smaller tori may be seen over the palatal roots of the
maxillary molars and in the area above the greater
palatine foramen or on the buccal/labial surfaces of
the maxillary teeth

39. Muscles
The muscles are
 mentalis ,
 incisivus labii inferioris,
 depressor labii inferioris,
 depressor anguli oris (triangularis),
 incisivus labii superioris,
 and buccinator muscles.

41. Anatomic Spaces
Several anatomic spaces or compartments are found
close to the operative field of periodontal and implant
surgery sites.
These spaces contain loose connective tissue but can
be easily distended by hemorrhage, inflammatory
fluid, and infection
Surgical invasion of these areas may result in
dangerous hemorrhage (intraoperative) or infections
(postoperative) and should be carefully avoided

42. canine fossa
Contains varying amounts of connective tissue and fat
Boundaries;
 bounded superiorly by the quadratus labii superioris
muscle,
anteriorly by the orbicularis oris, and posteriorly by the
buccinator.
 Infection of this area results in swelling of the upper lip,
obliterating the nasolabial fold, and of the upper and
lower eyelids, closing the eye.

44. buccal space
located between the buccinator and the masseter
muscles.
 Infection of this area results in swelling of the cheek
but may extend to the temporal space or the sub
mandibular space, with which the buccal space
communicates.

46. mental, or mentalis, space
located in the region of the mental symphysis, where
the mental muscle, depressor muscle of the lower lip,
and depressor muscle of the corner of the mouth are
attached.
Infection of this area results in large swelling of the
chin, extending downward

47. masticator
space
contains the masseter muscle, pterygoid muscles,
tendon of insertion of the temporalis muscle, and
mandibular ramus and posterior part of the body of
the mandible.
Infection of this area results in swelling of the face
and severe trismus and pain.
Patients may also have difficulty and discomfort
when moving the tongue and swallowing.

48. sublingual space
located below the oral mucosa in the anterior part of
the floor of the mouth.
It contains the sublingual gland and its excretory
duct, the submandibular or Wharton's duct, and is
traversed by the lingual nerve and vessels and
hypoglossal nerve

49. Its boundaries
 are the geniohyoid and genioglossus muscles
medially and the lingual surface of the mandible and
below by the mylohyoid muscle laterally and
anteriorly
Infection of this area raises the floor of the mouth
and displaces the tongue, resulting in pain and
difficulty in swallowing but little facial swelling.

50. submental space
found between the mylohyoid muscle superiorly and
the platysma inferiorly.
 It is bounded laterally by the mandible and
posteriorly by the hyoid bone.
Infections of this area arise from the region of the
mandibular anterior teeth and result in swelling of the
submental region; infections become more dangerous
as they proceed posteriorly.

52. submandibular space
found external to the sublingual space, below the
mylohyoid and hyoglossus muscles

53. This space contains the submandibular gland,
which extends partially above the mylohyoid
muscle, thus communicating with the sublingual
space, and numerous lymph nodes.

54. Infections of this area originate in the molar or
premolar area and result in swelling that obliterates
the submandibular line and in pain when swallowing.

55. Ludwig's angina
 Severe form of infection of the submandibular space
that may extend to the sublingual and submental
spaces.
It results in hardening of the floor of the mouth and
may lead to asphyxiation from edema of the neck and
glottis
bacteriology -mixed infections with an important
anaerobic component