Download Chapter 4 Periapical diseases

Chapter 4
Periapical diseases
Teaching Outline:
I.
II.
Biological features of the periapical tissues
Etiology ★
1. Infection
2. Trauma
3. Chemical irritation
4. Immune factors / Immunifaction
III. Classification of periapical diseases
IV. Clinical and Pathological features ★
1. Acute periapical periodontitis :
Acute serous periapical periodontits
Acute suppurative periapical periodontitis
2. Chronic suppurative periapical periodontitis
3. Periapical granuloma
4. Radicular cyst
V.
Immune-pathology of the periapical periodontitis
VI. Summery
Discussion:
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Definition:
Periapical inflammation is usually due to spread of infection following death of
the pulp. It characteristically causes tenderness of the tooth in its socket. Local
(periapical) periodontitis must be distinguished from chronic (marginal) periodontitis,
in which infection and destruction of the supporting tissues spread from chronic
infection of the gingival margins. Infection is far the most common cause. The usual
sequence of events is caries, pulpitis, death of the pulp and periodontitis.
I. Biological features of the periapical tissues
1. Blood supply of the periapical tissue
The arterial vessels of the periodontal ligament are derived from three sources:
●Branches from apical vessels that supply the dental pulp.
●Branches from intra-alveolar vessels. These run horizontally, penetrating the
alveolar bone to enter the periodontal ligament.
●Branches from gingival vessels. These enter the periodontal ligament from
the coronal direction.
2. Nerves of periapical tissue
The nerve fibers supplying the periodontal ligament are functionally of two
types; sensory and autonomic. The sensory fibers are associated with the modalities
of pressure and pain. The autonomic fibers are associated mainly with the supply of
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the periodontal blood vessels. Periodontal nerve fibers are both myelinated and
unmyelinated.
3. The periapical ligament has the following functions:
■ It is the tissue of attachment between the tooth and alveolar bone. It is thus
responsible for resisting displacing forces (the tooth support mechanism) and it
protects the dental tissues from damage caused by excessive occlusal loads
(especially at the root apex)
■ It is responsible for the mechanisms whereby a tooth attains, and then maintains,
its functional position. This includes the mechanisms of tooth eruption, tooth
support (particularly the recovery response after loading), and drift.
■ Its cells form, maintain and repair alveolar bone and cementum.
■ Its mechanoreceptors are involved in the neurological control of mastication.
★ II. Etiology
The nature and behavior of lesions that form at the apex of the tooth are a reflection of
the conditions that lead to the destruction of the pulp of the associated tooth．The four
major factors follow：
1．Presence of an open or closed pulpitis
2．Various kinds of the involved microorganisms
3．Extent of sclerosis of the dentinal tubules
4．Competency of the host immune response
When the factors are optimal，such as the presence of an open chronic pulpitis，bacteria
of low virulence，an older tooth with sclerotic dentinal tubules，and a healthy patient，the
changes at the apex of the tooth are mild and chronic．Multiple optimal factors are
sometimes associated with little or no activation of the inflammatory response；instead they
act as stimulants to the fibroblastic and osteoblastic cells and scar tissue and dense bone
produced in the area．When conditions are mostly adverse，such as the presence of a closed
acute pulpitis，large numbers of highly virulent bacteria，and open dentinal tubules of
young teeth，the inflammation at the apex of the tooth will rapidly intensify and large
amounts of bacterial toxins and autolytic enzymes will be produced and
disseminated．Under these circumstances rapid destruction of the periapical tissue and
surrounding bone takes place；the process quickly extends into the adjacent marrow
spaces．
Causes of apical periodontitis
●Infection
●Trauma
●Chemical irritation
●Immune factor/ immunifaction
( I ) Infection:
1. Dental caries：Dental plaque
Dental caries
Pulpitis
Periodontitis
2. Periodontal pocket：The necrotic pulp probably becomes infected by bacteria from the
gingival margins, leading to apical periodontitis.
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3. Systemic infection：（Rare）
( II ) Trauma:
1. The pulp sometimes dies from a blow which damages the apical vessels.
2. During endodontic treatment, instruments may be pushed through the apex or side
of the root, damaging the periodontal membrane and carrying infected debris from
the pulp chamber into the wound.
3. A high filling, or biting suddenly on a hard object, sometimes causes an acute but
usually transient periodontitis.
4. Occlusal trauma and orthodontics lead to trauma：
( III ) Chemical irritation
1. Irritant antiseptics used to sterilize a root canal can escape through the apex and
damage the surrounding tissues.
2. A root-canal filling may also extend beyond the apex with similar effect.
( IV) Immune factors / Immunifaction
Reference:
Foreign Medical Sciences (Stomatology) 2000;27(5):278
Key points:
Periapical inflammation
Irritant
Host defences
▲
nature
severity
duration
Mnemonic for differential diagnosis of pain of pulpal and periapical origin-LOCATE
Location
● Other symptoms
● Character
●Associations
● Timing
● Evaluation of other investigations, (pulp vitality tests)
●
III. Classification of periapical diseases
1. Acute serous periapical periodontitis
2. Acute suppurative periapical periodontitis
3. Chronic suppurative periapical periodontitis
4. Periapical granuloma
5. Radicular cyst
6. Granulating osteitis
7. Condensing osteitis
8. Periapical scar
9. Residual cyst
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10. Cholesteatoma
11. Periapical particular inflammation
12. Periapical lesions of non-pulpal origin
13. Resorption of root
★IV. Clinical and Pathological features
(I) Acute periapical periodontitis :
The factors leading to the development of acute lesions at the apex of a tooth
are usually one or more of the following：
1．Young tooth with open tubules
2．Rampant caries
3．Closed acute pulpitis
4．Presence of highly virulent microorganisms
5．Weakened host defense system
Under most or all of these circumstances the ensuing inflammatory events
happen quickly and cause a great deal of pain．If unchecked．infection and purulent
exudate date rapidly spread throughout the affected jaw into the adjacent structures
and the systemic circulation，where emboli of the infection could lodge in the small
capillaries of a number of distant organs or anatomic locations．
●Clinical features:
The patient may give a history of pain due to previous pulpitis. When
periodontitis develops, escape of exudates into the periodontal membrane causes the
tooth to be extruded by a minute amount and the bite to fall more heavily on it. The
tooth is at first uncomfortable, then increasingly tender, even to mere touch. Hot or
cold substances do not cause pain in the tooth. As inflammation becomes more
severe and pus starts to form, pain becomes intense and throbbing in character. There
is often a large carious cavity or filling in the affected tooth, or it may be discoloured
due to death of the pulp earlier. At this stage the gingival over the root is red and
tender, but there is no swelling while inflammation is confined within the bone.
●Radiographic
features：
Radiographs give little information because bony changes have had too
short a time to develop. Immediately round the apex the lamina dura may appear
slightly hazy and the periodontal space may be slightly widened. When acute
periodontitis is due to exacerbation of a chronic infection, the original lesion can be
seen as an area of radiolucency at the apex. Exudates may penetrate overlying bone
and periosteum a day or so after the onset of pain, allowing relief of the pressure.
Pain quickly abates but exudates, if it cannot escape, distends the soft tissues to form
a swelling.
When an upper canine is affected, the swelling quickly spreads to the face
and eyelid and may close the eye on that side . In spite of the alarming appearance,
the swelling is due only to oedema. It subsides when the tooth is extracted or the
infection is drained. The regional lymph nodes may be enlarged and tender, but
general symptoms are usually slight or absent. Inflammation typically remains
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localized. Further spread of infection can cause inflammation of the surrounding
bone (osteomyelitis) or cellulites , but only exceedingly rarely.
●Pathological features:
Acute apical periodontitis is a typical acute inflammatory reaction with
engorged blood vessels and packing of the tissue with neutrophils. These changes are
initially localized to the immediate vicinity of the apex as a consequence of the rich
blood supply to this area. The immediately adjacent lamina dura becomes resorbed
and an abscess cavity may form if not aborted by treatment.
(II) Periapical abscess
The periapical abscess is the initial lesion that develops when the
circumstances are adverse．It is probably the most painful patient condition that
confronts clinicians and is potentially one of the most dangerous．It is a progression
of an acute pulpitis in which exudate extends into the adjacent soft and hard
tissues ． Because it often contains one or more strains of virulent bacterial
organisms，the exudate usually contains potent exotoxins and lytic enzymes capable
of rapidly breaking down tissue barriers．Often absent is an opening to allow
drainage from the pulp through the crown to the oral cavity, relieving internal
pressure within the periodontal membrane．Such internal pressure causes extrusion
of the tooth from the socket and rapid extension of the exudate throughout the
underlying medullary bone．
●Clinical
features:
Patients with a periapical abscess are in a great deal of pain．Temperature
elevation and malaise are common．In most patients the tooth associated with the
abscess will extrude from the socket sufficiently to cause occlusal interference and
greatly increased pain when it contacts an opposing tooth．In locations where the
root apex is in close proximity to the cortex of the overlying alveolar bone, swelling
and redness of the area will be present．At this stage the percussion test is most
useful in establishing a diagnosis．Although the tooth is relatively insensitive or
unresponsive to hot，cold，and electrical stimulation，gently tapping on it produces
intense pain.
●Radiographic features：
The area around the apex of the tooth initially exhibits a slight widening of the
apical periodontal space，with a gradual loss of the distinctness of the adjacent
alveolar bone (lamina dura)．As the exudate extends into the surrounding medullary
bone，the radiographic appearance will reflect the bone loss by exhibiting a faintness
of the trabecular pattern and an increased radiolucency．Because a periapical abscess
is a rapid lytic process，the radiographic appearance will not exhibit a distinct line of
demarcation between the inflammatory process and the normal bone．
●Pathological
features:
The microscopic features of a periapical abscess are similar to those of an
abscess in other parts of the body．An outer thin capsule of fibrous tissue is
infiltrated with lymphocytes and plasma cells．A wide zone of granulation tissue
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containing a mixture of neutrophils，lymphocytes，plasma cells，and macrophages
surrounds a central core of tissue that has undergone disintegration and liquefaction
and is composed of purulent exudate．In many lesions，bacterial colonies are readily
apparent．
★ Summary： Possible complications of acute periapical periodontitis
●Suppuration
●Regional lymphadenopathy
●Spreading infection
(III) Chronic periapical periodontitis
●Clinical
features
The term chronic apicaf periodontitis is used to denote the earliest
radiographic evidence of extension of the inflammatory process from the pulpal
chamber into the adjacent periodontal membrane around the apical
foramen．Although the outline of the apical alveolar bone is still visible on a
radiograph ， the periodontal membrane in this region will appear to be
widened．Clinically the tooth may still exhibit some faint evidence of vitality when it
is electrically stimulated，and it will usually have a positive reaction to a percussion
test ． The histopathologic findings are variable and will refect the type of
inflammation that existed in the pulp．This condition is merely a transitory phase
between pulpitis and the more distinct forms of periapical lesions．
Chronic periodontitis is a low-grade infection. It may follow an acute infection
that has been inadequately drained and incompletely resolved. The tooth is non-vital
and may be slightly tender to percussion but otherwise symptoms may be minimal.
Frequently, chronic periodontitis is first recognised as a rounded area of radiolucency
at the apex of a tooth (an ‘apical granuloma’) in a routine radiograph. The area is
usually about 5mm in diameter and has well-defined margins. A distinct cortex is
sometimes interpreted as early cyst formation, but this cannot be distinguished
without a biopsy.
●Pathological
features:
Chronic periodontitis is a typical chronic inflammatory reaction
characterized by lymphocytes, macrophages and plasma cells. Infection is confined
by inflammatory cells, and granulation tissue surrounds the area.
（IV）Periapical granuloma
●Clinical
features：
Frequently, chronic periodontitis is first recognised as a rounded area of
radiolucency at the apex of a tooth (an ‘apical granuloma’) in a routine
radiograph. The area is usually about 5mm in diameter and has well-defined
margins. A distinct cortex is sometimes interpreted as early cyst formation, but
this cannot be distinguished without a biopsy. An uncommon complication,
but sometimes the first sign of periapical periodontitis, is the tracking of a
sinus on to the skin surface. This most frequently happens on or near the chin
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as a result of a long-forgotten blow and death of a lower incisor . In such cases
the crown of the damaged tooth is usually discoloured and may be chipped.
●Radiographic
features：
The radiographic appearance of periapical granuloma occurs as an oval or
rounded radiolucency with a well-demarcated outline located at the apex of the
tooth．Rarely the radiolucency will be located away from the apex and centered on
the opening of a lateral canal．A periapical granuloma that periodically under
goes acute exacerbations will have a less distinct line of demarcation between the
bone and the granulomatous tissue than a static，quiescent lesion．Frequent findings
associated with a long-standing periapical granuloma are hypercemen- tosis of the
apical third of the root and resorption resulting in blunting of the root tip．Many
patients fail to associate the sinus with dental infection but competent endodontic
treatment causes the sinus to heal remarkably quickly.
●Pathological
Features:
A periapical granuloma is composed of an outer capsule of dense fibrous
tissue and a central zone of granulation tissue．The central zone will often contain
macrophages with a foamy cytoplasm caused by phagocytized cholesterol．Some
cholesterol crystals may be present ， surrounded by multinucleated giant
cells．Throughout，the soft tissue will be a diffuse infiltrate of lymphocytes and
plasma cells．A frequent finding is the presence of irregular islands and strands of
epithelium，a result of prolonged，mild stimulation of the rests of Malassez．These
rests are the remnants of the Hertwig root sheath，the epithelial membrane that
determines the shape of the roots of developing teeth．
The granulation tissue grows into a rounded mass (a ‘granuloma’), and
steoclasts resorb the bone to accommodate it. Despite absence of symptoms, there
is no spontaneous healing because of the persistent reservoir of infection in the root
canal. Instead, granulation tissue proliferates round the focus of irritation at the
tooth apex, and surrounding bone is resorbed to leave a round area of radiolucency.
Healing only follows extraction, effective endodontic treatment or
apicectomy Variable degrees of proliferation of the epithelial rests of Malassez
in a periapical granuloma at the apex of a dead tooth are common. Epithelial
proliferation may be sufficient to lead ultimately to cyst formation and is the most
common cause of jaw cysts. This epithelium forms irregular strands or loops.
Sometimes a microscopic cyst cavity, with a lining of hyperplastic epithelium,
forms and represents the earliest stage of radicular cyst. In other cases the
epithelium is scanty or destroyed by the inflammation. Periapical granulomas
usually remain localized within the bone. Occasionally, there is abscess formation
and pus may reach the surface by resorption of the bone (usually on the buccal
surface of the gingiva) immediately over the apex of the tooth. A nodule of
granulation tissue forms in response to the irritation by pus and marks the opening
of the sinus .
Discussion:
Origin of the epithelium ?
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★Key points:
Periapical granuloma
● may be symptomless
● chronically inflamed granulation tissue
● obligate anaerobes predominate
● bone resorption of rests of malassez
(V) Radicular cyst
●Clinical
features：
A periapical cyst is a common development of longstanding ， untreated
periapical granuloma．The cyst’s epithelial lining is derived from the rests of
Malassez．The epithelial islands remaining after root formation during odontogenesis
and normally present in the apical periodontal membrane．The rests are stimulated to
proliferate by the low-grade inflammation of the preceding periapical granuloma．The
periapical cyst is by far the most common of the cysts of the jaws．Because its
development is the result of sequential inflammation of the tooth pulp and the adjacent
surrounding apical tissue，the cyst may become inflamed and symptomatic，sometimes
exhibiting acute exacerbations．Once the cyst has formed，it usually follows allow but
continuous course that can result in the destruction of a large portion of the maxilla or
mandible．
●Radiographic
features：
The periapical cyst is well circumscribed，often with a distinct thin line of
cortication separating it from the surrounding bone．It may be associated with
resorption of the apices of the teeth，displacement of the roots，or both．It is distinctly
rounded and unilocular and may become very large，resulting in erosion of the inferior
border and bulging of the buccal and lingual cortical plates．
●Pathological features：
The tissue consists of an outer dense fibrous connective tissue capsule that
surrounds a central lumen containing a thick, proteinaceous fluid and cellular
debris．The lumen is lined by a nonkeratinized，stratified squamous epithelium
containing rete pegs that are generally elongated and branched．Collections of
cholesterol-laden macrophages are commonly present, particularly in the early stages
of cyst development．The capsule and the epithelial lining contain a diffuse infiltration
of plasma cells and lymphocytes．Cholesterol crystals surrounded by foreign-body
giant cells are a common finding．The presence of eosinophilic refractile hyaline
bodies，referred to as Rushton bodies，is sometimes found in the intermediate cell
layer of the epithelium．
A periapical cyst that remains or forms after the of fending tooth has been
extracted is referred to as a residual cyst．It will have the same radiographic，clinical，and histopathologic features as the periapical cyst．
★Summary：Possible complications of chronic apical periodontitis
■ Periapical granuloma formation
■ Radicular cyst formation
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■ Suppuration and sinus formation
Interrelationships of periapical infection:
Pulpitis
Acute
Chronic
Apical periodontitis
Acute
Chronic
Periapical abscess
Acute
Periapical granuloma
Chronic
Periodontal cyst
OSTEOMYELITIS
Acute
Chronic
Focal
Diffuse
PERIOSTITIS
CELLULITIS
ABSCESS
★Discussion:
1 引起根尖周炎的原因有哪些？最常见的根尖周炎类型有哪些？
2 急性根尖周炎的发展过程分几个阶段？各有何临床、病理特点？
3 在临床和病理上如何区别急性化脓性牙髓炎和急性化脓性根尖周炎？
4 试比较根尖脓肿、根尖肉芽肿、根尖囊肿的临床、X线及病理特点，
三者之间有何关系？
5 图解龋病、牙髓病和根尖周炎的发生、发展和相互关系。
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