PERIODONTAL BONE LESIONS: CLASSIFICATION – DIAGNOSIS

PERIODONTAL BONE LESIONS: CLASSIFICATION – DIAGNOSIS

INTRODUCTION :

Loss of bone anchorage is often considered an anatomical sequela of periodontal disease, because “the key to the problem of periodontal disease lies in the changes that occur in the alveolar bone. Changes in other tissues of the periodontium are also important, but when the final analysis is made, it is the destruction of bone that is responsible for tooth loss” GLICKMAN.

In addition, the persistence of these bone defects constitutes a favorable ground for the development of periodontal disease. It is imperative to first classify and evaluate them in order to establish a treatment to guarantee the survival of the dental organ.

CLASSIFICATION OF BONE LESIONS:

There is a great variation in the morphology and contours of alveolar bone induced by periodontal disease. The bone characteristics that modify the pattern of bone destruction in periodontal disease are: the thickness, width, and crestal angulation of the interdental septa; the thickness of the buccal and lingual alveolar cortices; the presence of fenestrations and dehiscences on the root surfaces; thickening of the alveolar bone margins; and furcation involvement.

A bone lesion is defined by a loss of the anchoring system and alveolar bone

Goldman, Cohen, and Prichard and many other authors have proposed classifications of periodontal bone defects. These classifications are generally based on specific morphologic and anatomic criteria and are intended to guide clinicians in making the diagnosis, establishing the treatment plan, and predicting the prognosis.

The interdental bone :

Suprabony defects : the shape of the lysis is horizontal, the bony edge is almost perpendicular to the dental surface. Associated with a suprabony periodontal pocket, the bottom of which is coronal to the top of the residual bony crest.

Radiological image showing horizontal lysis

Infrabony defects : the shape of the lysis is oblique, the bone level is located apically in relation to the bony crest. It can affect one or more faces. Associated with an infrabony periodontal pocket, the bottom of which is apical in relation to the top of the residual bony crest

PERIODONTAL BONE LESIONS: CLASSIFICATION – DIAGNOSIS

Radiological image showing vertical lysis

The classification of infra-osseous lesions is proposed according to their morphology and depends on the location and number of residual bony walls.

Depending on the number of walls affected, the lesion is called: single-wall, 2-wall, 3-wall, 4-wall.

3-walled bony pocket delimited by 1 dental wall and 3 bony walls.
Bony pocket with 2 walls, delimited by 2 bony walls.
Single-walled bony pocket delimited by 1 bony wall, vestibular, lingual or proximal.
Combined bone pocket, The defect surrounds the tooth partially or completely (marginal groove).

PERIODONTAL BONE LESIONS: CLASSIFICATION – DIAGNOSIS

Intraosseous defects : indicates “a presence inside something” and implies tissue loss within the alveolar process in all 3 spatial directions. These bone defects are located in a single tooth.
Crater : This is an infrabony defect, defined as a cup- or bowl-shaped lesion in the interdental area, affecting the roots of two adjacent teeth. Resorption was achieved by leaving the vestibular and lingual walls intact.

In 1964, Ochsenbein and Bshannan classified craters into 4 categories:

Class 1: 2-3 mm concave crater with thick vestibular and lingual walls
Class 2: 4-5 mm concave crater with a large orifice and thinner walls
Class 3: 6-7 mm concave crater
Class 4: Crater of variable depth with thin bony walls.

Interradicular defects : an interradicular lesion corresponds to a partial or total loss of the anchoring system and the alveolar bone within the interradicular zone, this anatomical zone delimited coronally by the furcation and laterally by the root surfaces up to the apex.

. Horizontal classification of furcation lesions: According to Lindhe, Nyman and Hamp, horizontal bone loss is defined in 3 classes :
Class I: horizontal attachment loss up to 3mm.
Class II: horizontal attachment loss greater than 3mm.
Class III: total loss of horizontal attachment allowing the probe to pass through.

diagram representing the horizontal classification of furcation lesions according to Hamp et al 1975. a) grade I b) grade II c) grade III

Vertical classification of furcation lesions: Tarnow and Fletcher described a subdivision assessing the vertical bone loss of interradicular bone from the furcation. Thus three subclasses were defined :

Class A: vertical bone loss less than or equal to 3mm.
Class B: vertical bone loss between 4 and 6 mm.
Class C: vertical bone loss greater than or equal to 7mm.

diagram representing the vertical classification of furcation lesions according to Tarnow and Fletcher. A) class I B) class II C) class III

Other forms of bone defects :

Bulbous contours of the bone : these are bone thickenings caused by exostoses, functional adaptation or buttress formation of the bone.
Hemisepta : The part of the interdental septum that remains after the mesial or distal part has been destroyed by disease is called hemisepta.
Irregular margins : These are angular or U-shaped lesions that are caused by resorption of the vestibular and lingual alveolar cortex or by different height gradients between the vestibular or lingual marginal margins and the height of the interdental septa.
Protrusions : These are plateau-like bony edges that are caused by the resorption of thickened bony tables.

ASSESSMENT OF BONE LESIONS:

As a first step, a complete clinical examination systematically combined with a complementary radiological examination is essential to diagnose bone lesions.

Clinical diagnosis:

This initial clinical examination includes medical questioning, observation of dento-gingival sites, assessment of plaque control, tooth mobility, gingival characteristics, search for malocclusions and periodontal probing which is essential to highlight the presence of periodontal pocket, determine its depth and measure the loss of attachment relative to the depth of the bone lesion.

Periodontal probing is performed with a conventional graduated periodontal probe for periodontal losses and infrabony lesions; and a Nabers probe to measure the horizontal component of interradicular lesions.

Image showing a periodontal probe

Radiological diagnosis :

The use of radiographic imaging is an aid to diagnosis and provides a great deal of information that is essential for developing a periodontal treatment plan. It allows the assessment of the level of the alveolar bone, as well as the extent and type of bone resorption (horizontal and/or vertical alveolysis). Measurements taken from the cemento-enamel junction to the alveolar crest and then to the apices of the teeth indicate the degree of alveolysis. Similarly, measurement from the top of the alveolar crest to the base of the bone defect is used in the assessment of intraosseous lesions.

The role of radiography is at the very beginning of periodontal treatment, then during the maintenance phase in order to assess tissue healing and the absence of recurrence of the disease.

The orthopantomogram or panoramic radiography :

Is an easy examination to implement, it allows an overview, but does not detect in any case all possible bone losses precisely the superposition of the anatomical structures requires more precise additional examinations.

PERIODONTAL BONE LESIONS: CLASSIFICATION – DIAGNOSIS

X-ray image from a panoramic X-ray examination

Retroalveolar radiography :

Is a complementary two-dimensional examination of a three-dimensional structure, it allows to define the vertical bone loss but not the loss in width. Currently it is accepted that vertical defects located in the interdental spaces can generally be seen on the retro-alveolar radiograph taken with an angulation system. However sometimes the thickness and the bony edges can mask them, as well as the anatomical structures. Intra-bony defects can also appear on the vestibular, lingual or palatal surfaces, and in these cases, the lesions are not visible on the radiograph because of the superposition of the structures.

Radiological image showing a retro-alveolar

The combination of radiography and probing is a more sensitive diagnostic approach to detecting bone lesions. But in reality, surgical exposure is the best way to determine the configuration of these lesions.

PERIODONTAL BONE LESIONS: CLASSIFICATION – DIAGNOSIS

PERIODONTAL BONE LESIONS: CLASSIFICATION – DIAGNOSIS

Cone beam computed tomography (CBCT)

A complementary three-dimensional examination, which cuts by cut, allows the bone volume to be assessed. Mainly used in the implant and endodontic fields.

CBCT is of interest in the detection of all periodontal intraosseous lesions, which can go unnoticed during panoramic and retro-alveolar radiographs. In 2014, the results of the study by Braun et al showed that three-dimensional radiography is statistically and significantly a better method of detection compared to two-dimensional imaging.

CONCLUSION :

Periodontitis is a multifactorial infectious disease that results in the progressive destruction of the periodontium and the formation of periodontal pockets with bone defects that can take several forms. It is necessary to classify them and highlight them in order to make a diagnosis and choose a good therapeutic approach that will result in the prognosis.

Good oral hygiene is essential to prevent cavities and gum disease.

Regular scaling at the dentist helps remove plaque and maintain a healthy mouth.

Dental implant placement is a long-term solution to replace a missing tooth.

Dental X-rays help diagnose problems that are invisible to the naked eye, such as tooth decay.

Teeth whitening is an aesthetic procedure that lightens the shade of teeth while respecting their health.

A consultation with the dentist every six months is recommended for preventive and personalized monitoring.

The dentist uses local anesthesia to minimize pain during dental treatment.