Young Bui, D.D.S.
Endodontic-Periodontal Relations
Young Bui

Young Bui

THE 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 

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
Figure 1

FIGURE 1: Endodontic and periodontal diseases are occurring independently of each other.

Figure 2

FIGURE 2: Endodontic disease is occurring secondarily to a periodontal condition due to bacterial retrograde from distal root.

Figure 3

FIGURE 3: Periodontal disease at the furcation is occurring secondarily to a pinpoint perforation at the furcation floor.

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