Periodontics-endodontics interrelationsPeriodontics-endodontics interrelations

Periodontics-endodontics interrelations

Plan :

1. Introduction
2. Anatomical reminder
3. The endo-periodontal continuum

3-1- the physiological communication pathways between the endodontium and the periodontium

3-2- pathological communication pathways between the endodontium and the periodontium

4. Endo-periodontal lesions

4-1- Definition 

4-2- Etiologies 

      4-2-1- Effect of pulp infections and their treatments on the periodontium

      4-2-2- Effect of periodontal diseases and treatments on the endodontium

4-3- Classification

4-4- The diagnostic approach according to the new Chicago 2017 classification

      4-4-1- Main signs and symptoms

      4-4-2- Diagnostic tools

      4-4-3- Diagnostic criteria

4-5- Therapeutic strategies

5. Conclusion
6. Bibliographic references
7. Introduction :

Periodontal and endodontic tissues are related from an anatomical, functional and embryological point of view. It is therefore not surprising that these two tissues are involved in common pathological processes.

2. Anatomical reminder:

• Odontium  : The odontium is made up of three elements: enamel, dentin and pulp.

• Enamel is a very hard, acellular substance, formed of mineral prisms from an organic matrix.
• Dentin is the main constituent of the odontium. It participates in the constitution of the two anatomical units of the tooth, the crown and the root:

• The crown, intraoral, where the dentin is covered by the enamel;
• The root, intraosseous, where the dentin is covered with cementum.
• The dental pulp , connective tissue lined by odontoblasts, has a terminal type vasculo-nervous axis penetrating through the apical orifices of the tooth.
• Periodontium:  the tooth’s supporting apparatus, the periodontium is formed by four elements: the gum, the desmodontium, the cementum and the alveolar bone.

• The gingiva is a part of the oral mucosa. It surrounds the cervical region of the teeth and covers part of the cortices of the alveolar processes. It consists of two parts: this is the chorion, which in turn is covered with an epithelium.
• The desmodontium (or alveolo-dental ligament or periodontium) is the soft connective tissue that surrounds the roots of the teeth and unites the cementum to the alveolar bone, it is located at a level of approximately 1 mm from the enamel-cementum junction. A true suspensory and shock-absorbing device for the tooth. It is the seat of proprioception.
• Cementum , a calcified tissue that covers the root surfaces of teeth from the cementum-enamel junction to the apex; it covers all of the root dentin, it can sometimes penetrate slightly into the root canal at the apical level.
• Alveolar bone is a calcified connective tissue. It appears as an envelope of dense compact bone surrounding a spongy bone with large medullary spaces ensuring very significant vascularization. It is hollowed out by alveoli which are lined by the lamina dura.

3. The endo-periodontal continuum:

3-1- the physiological communication pathways between the endodontium and the periodontium:

During the embryonic development of the dental organ, the future pulp and periodontal tissues establish intimate relationships. The main communication pathways are: 

•  The dentinal tubules; 
•  Side and accessory channels; 
•  The interadicular space;
•  The apical zone (De Deus 1975). 

The dentinal tubules may be exposed in the gingival sulcus or in the periodontal pocket, in the event of a congenital defect (absence of the enamel-cementum junction, palatal pit of the maxillary incisors), periodontal disease or sequelae of surgical or non-surgical mechanical treatment (iatrogenic surfacing).

Lateral canals exist throughout the roots. De Deus (1975) found 17% of lateral canals in the apical third, 9% in the middle third, and less than 2% in the cervical third. 

The furcation zone is very rich in accessory canals. 

The apical foramen constitutes the privileged means of communication between the endodontium and the periodontium (Dahlén 2002; Pineda and Kuttler, 1972) and in particular for the passage of microorganisms and their by-products.

Periodontics-endodontics interrelations

3-2- pathological and iatrogenic communication pathways between the endodontium and the periodontium:

Iatrogenic lesions include perforations, material overflow, loss of coronal sealing, resorptions induced by chemicals and intracanal medications as well as vertical root fractures.

Internal perforating resorption: it originates at the level of the pulp cavity. The process is still largely unknown, but probably comes from chronic pulp inflammation. This damage is irreversible because the dentinal tissues are destroyed and replaced by granulation tissue. As it progresses, it can lead to endo-periodontal communication.

Internalized external resorption: these resorptions are always of inflammatory origin but can have various etiologies (sequelae of trauma, iatrogenic periodontal therapy, complications of internal bleaching procedure). In all cases, the damage is linked to a localized loss of cementum and inflammation of the alveolo-dental ligament.

Iatrogenic root perforations : they act as an additional exit door for the endodontium. They may affect the pulp floor (excessive deepening of the access cavity), the middle third (perforation by stripping most often, tenon accommodation), or the apical third (creation of a false canal).

Vertical root fracture : If the apical foramen as well as the lateral and secondary canals are communication routes for bacteria between the pulp and the periodontium, fractures are real highways of microbial contamination (Zehnder et al., 2002). The causes can be traumatic or, again, iatrogenic: oversized cast or crushed coronoradicular reconstruction or excess pressure during condensation obturation.

4. Endo-periodontal lesions:

Periodontics-endodontics interrelations

4-1- Definition:

According to the EFP, an endoperiodontal lesion is defined as a pathological communication between the pulp and periodontal tissues at the level of a given tooth which can occur in an acute or chronic form.

4-2- Etiologies:

1. Effect of pulp infections and their treatments on the periodontium:

• Effect of pulp infections on the periodontium

Pulpopathy can lead to destruction of the periapical periodontium (cementum, alveolodental ligament and alveolar bone) in cases of septic necrosis only. These are the classic periapical or interadicular endodontic lesions with or without desmodontal or mucosal fistula. The consequences on the periodontium of inflammation of the pulp (pulpitis) are limited to a widening of the alveolodental ligament in certain cases, but without pronounced destruction of the attachment apparatus.

• Effect of endodontic treatments on the periodontium:

• Incomplete root canal filling causes destruction of periodontal tissues.
• Instrumental overshoot causes periodontal damage.
•  The use of a strong antiseptic for root canal disinfection results in severe necrosis of the desmodont and alveolar bone. 
•  Arsenic rocket or poorly conducted anesthesia results in necrosis of the interdental or interradicular septum. 
• Root fractures and perforations during endodontic treatment cause or aggravate attachment loss.
• Root fractures that can occur in teeth that have undergone endodontic treatment; 
• Improper dental restorations such as an overhanging filling can cause septal damage.

2. Effect of periodontal diseases and treatments on the pulp:

• Periodontal and pulp disease:

Many studies have shown that periodontal disease has little effect on the pulp status of affected teeth over very long follow-up periods (Harrington et al., 2000). Langeland et al. (1974) believe that the pulp only becomes necrotic when the progression of periodontitis is such that it involves the apical foramen. In all other cases (involvement of a lateral canal) only minor changes may occur (Harrington et al., 2000; Solomon et al., 1995; Wood et al., 2003).

• Periodontal and pulp treatment:

Cementum protects the pulp against pathogens from plaque bacteria. The goal of scaling and root planing (SRP) is to remove bacterial deposits and biofilm. If SRP is too aggressive, it can lead to the removal of cementum from the superficial part of the dentin, thus exposing the dentinal tubules to the oral environment. Colonization of the radicular dentin by periodontopathogens becomes possible. Recent ultrasonic debridement techniques, due to their less aggressiveness, allow better preservation of the cementum than manual techniques. 

3. Classifications:

• Classification by Guldener and Langeland (1982):

•  Class I: primary endodontic lesions. 
•  Class II: primary periodontal lesions. 
•  Class III: combined endodontic and periodontal lesions (endo- periodontal lesions ). 
• Classification of endo-periodontal lesions according to the Chicago classification 2017:

The classifications of endo-periodontal lesions were based on etiologies. In 2017, the Chicago classification allowed a more pragmatic and clinical approach to establish the diagnosis, treatment plan and prognosis. Indeed, there are two very distinct etiopathogenesis of endo-periodontal lesions that require different treatments and do not lead to the same results. For this reason, two patient cases were highlighted, depending on whether or not root integrity was affected.

4. The diagnostic approach according to the new 2017 classification:
   1. Main signs and symptoms:

The main signs associated with this lesion are deep periodontal pockets extending to the root apex and/or a negative or altered response to pulp vitality tests .

Other signs and symptoms may include:

(a) radiographic signs of bone loss in the apical region or in the interradicular area, 

(b) spontaneous pain or pain on palpation / percussion, 

(c) purulent exudate or suppuration, 

(d) tooth mobility, 

(e) sinus tract or fistula, 

(f) alterations in the color of the dental crown and/or gum.

Periodontics-endodontics interrelations

2. Diagnostic tools

The periodontal probe provides information on the importance of pocket depth. 

The pulp sensitivity test (a thermal test such as “cryospray” or an electrical test) provides information on the state of the tooth’s pulp. 

An additional radiographic examination such as a retro-alveolar radiograph can then be used to refine the diagnosis.

3. Diagnostic criterion

• Root Integrity

The clinician assesses the presence or absence of fracture, perforation and resorption. When a loss of root integrity is present, the origin is frequently traumatic or iatrogenic. The prognosis then depends on the location, size and age of the lesion. For a location in the middle third of the root, it is generally “hopeless” since the structure of the tooth is affected. Thus, the affected tooth will rather be subject to extraction.

• Presence of periodontitis

This criterion is determined upstream during the clinical examination . When a patient is affected by periodontitis, management involves stabilization.

• Extent of the lesion:

The clinician assesses this criterion by assigning a grade to the lesion according to its depth, morphology and extent: 

– Grade 1: narrow and deep periodontal pocket on a tooth surface; 

– Grade 2: wide and deep periodontal pocket on a tooth surface;

– Grade 3: narrow and deep periodontal pocket on more than one tooth surface. In this clinical situation, the presence of grade 3 bone involvement would indicate a less favorable dental prognosis.

5. Therapeutic strategies

• If root integrity is affected:

In a patient with a fractured, cracked or perforated tooth, the practitioner will more easily opt for extraction or root amputation if only one root is affected on a multi-rooted tooth, unless a root filling material can be placed in a suitable and lasting manner, particularly in the event of perforation (BiodentineTM or MTA for example).

Periodontics-endodontics interrelations

• No damage to root integrity:
• Endodontic treatment:

After the vitality tests, if the answer is negative, the endodontic treatment is carried out, paying particular attention to disinfection and then to the quality of the obturation. Indeed, given the numerous accessory or lateral canals present at the root level, it is absolutely necessary that the tooth is no longer an infectious reservoir in order to be able to set up the periodontal treatment.

Disinfection by mechanical debridement is the solution to eradicate biofilms. In addition to this debridement, rigorous intra-canal irrigations and intra-canal medication treatment steps are recommended. They are based on calcium hydroxide, Ca[OH]2, deposited intra-canal, acting by alkalinization of the environment, and chlorhexidine for its broad-spectrum antimicrobial qualities. 

• Periodontal treatment

Once the endodontic treatment has been completed, root debridement and root planing are performed to eradicate the biofilm from the root surface. These treatments are performed using Gracey, SQBL and SQMD curettes, which are long, narrow, and work in traction on the tip of the curette. This allows adaptation to the shape of the endo-periodontal lesions, which are often narrow and deep. Ultrasonic systems and air polishers can be used for root debridement, with adapted, narrow and long inserts.

• Reassessment:

After 3 months of healing, the practitioner assesses the apical healing. 

If there is no apical healing, we move towards either endodontic retreatment, apical resection, root amputation or extraction depending on the intrinsic value of the tooth. 

If there is mobility greater than physiological mobility, a temporary retainer is put in place to facilitate the patient’s oral hygiene and the practitioner’s treatment capacity. 

During apical healing, periodontal probing allows the periodontal therapeutic methods to be implemented to be assessed. 

For a survey with pockets less than 4 mm, supportive therapy is performed to continue to improve periodontal parameters and maintain restored health.

If the periodontal probe shows pockets greater than or equal to 5 mm and bleeding on probing, surgical therapy is proposed.

5. Conclusion :

Endo-periodontal lesions are complex lesions that require all the expertise of endodontics and periodontology. Endo-canal treatment must be meticulous and focused on effective disinfection in order to perform non-surgical and then surgical periodontal treatment. 

6. Bibliographic references:

[1] Bouchard Philippe, periodontology and implant dentistry volume 1, Lavoisier edition, 2015.

[2] Ranked Helen, the complex relationships between periodontium and endodontium, Rev Odonto stomato, 2007.

[3] Raphael Richert, Kadiatou Sy, how to diagnose an endo-periodontal lesion according to the Chicago 2017 classification?, dental information, n°16, April 24, 2024.

[4] Christian Verner, periodontal treatments for endo-periodontal lesions, dental information, n°21, May 29, 2024.

[5]EFP, Practical guide for clinicians, new classification of periodontal and peri-implant diseases and conditions, 2019.

Periodontics-endodontics interrelations