Young Bui
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HEALTH of the periodontium is important to the proper function of a tooth.
The periodontium includes the gingiva, cementum, periodontal ligament (PDL),
and alveolar bone. Disease that affects the periodontium usually
is a result of the direct extension of pulpal disease or due to apical
progression of periodontal disease.
When the pulp becomes infected, the disease can progress
beyond the apical foramen and inflame the PDL. The inflammatory process
results in replacement of the periodontal ligament by inflammatory tissue.
Without proper treatment, the inflammatory response can cause resorption
of the alveolar bone, cementum, and dentin.
Besides going through the apical foramen, pulpal
disease can progress through lateral canals. Lateral canals are seen
mostly in the apical third of the root and in the furcation area of molars.
Pulp disease may cause an inflammatory response of the PDL at the opening
of lateral canals, resulting in a lateral radiolucency on the root.
The inflammatory response at the lateral canals may extend crestally along
the lateral aspects of the root and ultimately involve the furcation or
crestal area of the attachment apparatus.
The effect of periodontal disease on the pulp is
not as clear-cut as the effect of pulpal disease on the periodontium.
Periodontal inflammation may exert a direct effect on the pulp through
the same lateral canal or apical foramen pathways. The effect of
gingival wounds on the pulp is shown in irregular dentin formation in the
pulp opposite the wound site. This might be transmitted through irritation
of the odontoblastic process. This irregular dentin formation may
be aided by cemental resorption in periodontal inflammation.
There are five types of endo-perio lesion that may
occur at any given time. We have to be able to diagnose the lesion
properly in order to provide the proper treatment.
Primary Endodontic Lesions
A sinus tract originating from the apex or a lateral canal may form
along the root surface and exit through the gingival sulcus. This
is a fistula that drains along the PDL into the sulcus instead of exiting
through the buccal or lingual mucosa. This is not a true periodontal
pocket. You may see drainage in the sulcus area or swelling simulating
a periodontal abscess. The tract can be traced to the source of the
infection, usually the apex or lateral canal. This tract is more
tubular and thinner than an infra-bony periodontal pocket. Because
this lesion is an endodontic problem, complete resolution usually occurs
after routine endodontic treatment.
Primary Endodontic Lesions with
Secondary Periodontal Involvement
If the primary lesion is left untreated, it may progress to involve
periodontal disease. An example would be plaque formation appearing
at the tract opening that was followed by calculus formation resulting
in gingivitis and periodontitis. Once this result has occurred, both
endodontic and periodontic therapy will be needed.
Primary Periodontal Lesions
Periodontal disease may progress and spread along the lateral aspects
of roots and in the furcation areas. In periodontal disease, vitality
testing will reveal a normal pulpal response. Periodontal examination
will reveal pocket depths and accumulation of plaque and calculus.
The bony lesion is usually more widespread and generalized than are lesions
of endodontic origin. Periodontal therapy is needed for this situation.
Primary Periodontal Lesions with
Secondary Endodontic Involvement
Periodontal disease may have an effect on the pulp through dentinal
tubules, lateral canals, or retrograde from the apex. If the tooth
does not respond to periodontal treatment, a necrotic pulp may be the cause.
Once the pulp becomes secondarily inflamed, it can in turn affect the primary
periodontal lesion. Scaling, curettage, and flap procedures may open
lateral canals or dentinal tubules to the oral environment resulting in
pulpal inflammation leading to necrosis. This is likely to be the
case when a patient complains of tooth sensitivity or inflammation after
a routine scaling and root planing. If a root is exposed as a result
of severe periodontal disease, the exposure may allow bacteria to enter
through the apex and cause a retrograde necrosis. In a situation
such as that, both endodontic and periodontal therapy are
required.
True Combined Lesions
Some teeth have both pulpal and periodontal disease occurring independently.
Each of these diseases may progress until the lesions unite to produce
a radiographic and clinical picture similar to that of other lesions with
secondary involvement. Once the endodontic and periodontal lesions
join, they may be indistinguishable from endodontic and periodontal lesions
that are secondarily involved.
WITH ALL THIS IN MIND, always do a complete exam and vitality test on
a tooth. Together with a good radiograph, these are the diagnostic essentials
you’ll need before performing endodontic treatment. An abscess can
be of endodontic or periodontal origin. A root-canal treatment on
a periodontally abscessed tooth will not resolve the problem.
November-December 2002
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FIGURE 1: Endodontic and
periodontal diseases are occurring independently of each other.
FIGURE 2: Endodontic disease
is occurring secondarily to a periodontal condition due to bacterial retrograde
from distal root.
FIGURE 3: Periodontal disease
at the furcation is occurring secondarily to a pinpoint perforation at
the furcation floor.
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