1. alveolar bone
2. periodontal ligament
3. cementum
4. gingiva

While many different diseases affect the tooth-supporting structures, plaque-induced inflammatory lesions make up the vast majority of periodontal diseases^[1] and have traditionally been divided into two categories:^[2]

1. gingivitis or
2. periodontitis.

While in some sites or individuals, gingivitis never progresses to periodontitis,^[3] data indicates that gingivitis always precedes periodontitis.^[1]

[edit] Historical methods of disease analysis and classification

Investigation into the causes and characteristics of periodontal diseases began in the 18th century with pure clinical observation, and this remained the primary form of investigation well into the 19th century.^[4] During this time, the signs and symptoms of periodontal diseases were firmly established:^[1]

1. Rather than a single disease entity, periodontal disease is a combination of multiple disease processes that share a common clinical manifestation.
2. The etiology (cause) includes both local and systemic factors.
3. The disease consists of a chronic inflammation associated with loss of alveolar bone.
4. Advanced disease features include pus and exudates.
5. Essential aspects of successful treatment of periodontal disease include initial debridement and maintenance of proper oral hygiene.

The advent of microscopy allowed later studies performed at the turn of the 19th century to report the histological structures and features of periodontal lesions, but most were limited to advanced stages of the disease. Progress in microscopy in the 1960s, such as advances in histopathology and stereology, allowed researchers to focus on earlier stages of inflammatory processes while the innovation of experimentally-induced periodontal disease in both human and animal models allowed for more detailed research into the temporal progression of the pathogenesis of plaque-induced periodontal disease.^[5]

Historically, chronic plaque-induced periodontal diseases were divided into three categories:^[6]

1. subclinical gingivitis
2. clinical gingivitis
3. periodontal breakdown

[edit] Modern methods of disease analysis and classification

In 1976, Page & Schroeder introduced an innovative new analysis of periodontal disease based on histopathologic and ultrastructural features of the diseased gingival tissue. Although this new classification does not correlate with clinical signs and symptoms and is admittedly "somewhat arbitrary," it permits a focus of attention on important pathologic aspects of the disease that were, until recently, not well understood.^[1] This new classification divided plaque-induced periodontal lesions into four stages:

1. initial lesion
2. early lesion
3. established lesion
4. advanced lesion

[edit] Initial lesion

Unlike most regions of the body, the oral cavity is perpetually populated by pathogenic microorganisms; because there is a constant challenge to the mucosa in the form of these microorganisms and their harmful products, it is difficult to truly characterize the boundary between health and disease activity in the periodontal tissues. As such, the initial lesion is said to merely reflect "enhanced levels of activity" of host response mechanisms "normally operative within the gingival tissues."^[1][5][7]

Healthy gingiva are characterized by small numbers of leukocytes migrating towards the gingival sulcus and residing in the junctional epithelium.^[1][7] Sparse lymphocytes, and plasma cells in particular, may exist just after exiting small blood vessels deep within the underlying connective tissue of the soft tissue between teeth.^[1][7] There is, however, no tissue damage, and the presence of such cells is not considered to be an indication of a pathologic change.

On the contrary, the initial lesion shows increased capillary permeability with "very large numbers" of neutrophils migrating from the dilated gingival plexus into the junctional epithlieum and underlying connective tissue (yet remaining within the confines of the region of the sulcus) and macrophages and lymphocytes may also appear. Loss of perivascular collagen occurs; it is thought that this is due to the degradative enzymes released by extravasating leukocytes, such that the collagen and other connective tissue fibers surrounding blood vessels in the area dissolve.^[1][7]

The initial lesion appears within two to four days of gingival tissue being subjected to plaque accumulation. When not generated through clinical experimentation, the initial lesion may not appear at all, and instead, a detectable infiltrate similar to that of the early lesion, explained below, appears.^[8]

Features of the Initial Lesion:^[1]

• Vasculitis of vessels subjacent to junctional epithelium
• Increased migration of leukocytes into junctional epithelium
• Extravascular presence of serum proteins, especially fibrin
• Alteration of the most coronal portion of junctional epithelium
• Loss of perivascular collagen

[edit] Early lesion

While the early lesion is not entirely distinct from the initial lesion, it is said to encompass the inflammatory changes that occur from days four to seven after plaque accumulation has commenced.^[7] It is characterized by a matured leukocytic infiltrate that features mainly lymphocytes. Immunoblasts are quite common in the area of infiltration, while plasma cells, if present, are only at the edges of the area.^[1] The early lesion can occupy up to 15% of the connective tissue of the marginal gingiva and up to 60-70% of collagen may be dissolved.^[9]

Fibroblasts appear altered, exhibiting electron-lucent nuclei, swollen mitochondria, vacuolization of the rough endoplasmic reticulum and rupture of their cell membranes, appearing up to three times the size of normal fibroblasts and found in association with moderately-sized lymphocytes.^[9]

The early lesion displays acute exudative inflammation; exudative components and crevicular lymphocytes reach their maximum levels between days 6-12 after plaque accumulates and gingival inflammation commences^[6] with the quantity of crevicular fluid being proportional to the size of the reaction site within the underlying connective tissue. The junctional epithelium may even become infiltrated with enough leukocytes so that it resembles a microabscess.^[10]

Features of the Early Lesion:^[1]

• Accentuation of features of the initial lesion, such as the considerably greater loss of collagen
• Accumulation of lymphocytes subjacent to junctional epithelium
• Cytopathic alterations in resident fibroblasts
• Preliminary proliferation of basal cells of junctional epithelium

[edit] Established lesion

The hallmark of the established lesion if the overwhelming presence of plasma cells in relation to the prior stages of inflammation. Beginning two to three weeks after first plaque formation, the established lesion is widespread in both human and animals populations^[11] and can be seen commonly associated with the placement of orthodontic bands on molars.^[12]

Similar to the initial and early lesions, the established lesion features an inflammatory reaction confined to the area near the base of the gingival sulcus, but unlike prior stages, displays plasma cells clustered around blood vessels and between collagen fibers outside the immediate area of the reaction site.^[1] While most of the plasma cells produce IgG, a significant number do produce IgA (and rarely, some produce IgM).^[13] The presence of complement and antigen-antibody complexes is evident throughout the connective and epithelial tissue.^[13]

It is in the established lesion that epithelial proliferation and apical migration begin. In health, the junctional epithelium creates the most coronal attachment of the gum tissue to the tooth at or near the cementoenamel junction. In the established lesion of periodontal disease, the connective tissue lying subjacent to the junctional epithelium is nearly destroyed, failing to properly support the epithelium and buttress it against the tooth surface. In response to this, the junctional epithelium proliferates and grows into the vacant underlying spaces, effectively causing the level of its attachment to migrate towards apically, revealing more tooth structure than is normally evident supragingivally (above the level of the gumline) in health.

While many established lesions continue to the advanced lesion (below), most either remain as established lesions for decades or indefinitely; the mechanisms behind this phenomenon are not well understood.

Features of the Established Lesion:^[1]

• Predominance of plasma cells without bone loss
• Presence of extravascular immunoglobulins in the connective tissue and junctional epithelium
• Continuing loss of collagen
• Proliferation, apical migration and lateral extension of the junctional epithelium, with or without pocket formation

[edit] Advanced lesion

Many of the features of the advanced lesion are described clinically rather than histologically:^[4]

• Periodontal pocket formation
• Gingival ulceration and suppuration
• Destruction of the alveolar bone and periodontal ligament
• Tooth mobility, drifting and eventual loss

Because bone loss makes its first appearance in the advanced lesion, it is equated with periodontitis, while the first three lesions are classified as gingivitis in levels of increasing severity.^[1]

The advanced lesion is no longer localized to the area around the gingival sulcus but spreads apically as well as laterally around a tooth and perhaps even deep into the gum tissue papilla. There is a dense infiltrate of plasma cells, other lymphocytes and macrophages. The clusters of perivascular plasma cells still appears from the established lesion. Bone is resorbed, producing scarring and fibrous change.^[1]

Features of the Advanced Lesion:^[1]

• Extension of the lesion into alveolar bone, periodontal ligament with significant bone loss
• Continued loss of collagen
• Cytopathic alterations in plasma cells in the absence of altered fibroblasts
• Formation of periodontal pocketing
• Conversion of bone marrow into fibrous connective tissue

[edit] Treatment of Periodontal Disease

The treatment of periodontal disease begins with the removal of sub-gingival calculus (tartar). This is commonly addressed by the surgical procedures known as root planing and scaling. These procedures debride calculus by mechanically scraping it from tooth surfaces.

Dental calculus, commonly known as tartar, consists almost entirely of calcium phosphate salt, the ionic derivative of calcium phosphate (the primary composition of teeth and bone). Clinically, calculus stuck to teeth appears to be hardened to the point requiring mechanical scraping for removal.

Newer less invasive methods for treatment of periodontal disease involve the use of an orally administered antibiotic, Periostat (Doxycycline). Periostat has been clinically proven to decrease alveolar bone loss and improve the conditions of periodontal disease with minimal side-effects.

[edit] Failure to Treat Periodontal Disease

Plaque, also known as a biofilm, when examined under a microscope, is made of thousands and thousands of bacteria. There are many different types of microbes contained in the biofilm, one of the major ones being porphyromonas. Since a microbe is a living organism, it maintains some of the same properties that we do to survive. Porphyromonas have a life cycle, they have a digestive system, and they reproduce. So if we think about this, bacteria have to eat to survive, plus they also have to eliminate wastes just like we do, and they are constantly reproducing. The average person will eat three meals a day leaving behind plenty of food particles for plaque to feast on. Naturally, as humans, bacteria are always present in the oral cavity. However, when plaque is not removed on a daily basis, and levels kept down to a minimum, that is when the trouble begins. The failure to remove plaque on a daily basis leaves an individual with a mouth full of bacteria, rotten food, fecal matter, bone loss, and eventually, tooth loss. Bacteria are constantly eating, and disposing of fecal matter on, and around teeth which is what causes all of the destruction and foul odors in a person with gum disease. Bone is considered to be the foundation and supporting structure of teeth. Bacteria will make themselves right at home in the spaces between your teeth, constantly devouring what bone is available. As bacteria eat away at the foundation, teeth will become loose and eventually either fall out on their own, or have to be extracted by a Doctor of Medical Dentistry. This process is not something that happens over night, but is a result of long time neglect of one’s personal oral hygiene. Most individuals don’t take dental care seriously and fail to see a dental professional regularly. It is recommended that a dental prophylaxis and thorough examination of the mouth be done every six months, which will prevent plaque buildup on teeth. Plaque or bacteria, if left for a long period of time, eventually die off. Dead plaque hardens and calcifies and is then referred to as tartar, or calculus. Once the calculus builds up around the teeth, in between them, and the gums, it causes the gums to pull away from the teeth. When the gums pull away from the teeth, it creates a pocket which allows food and debris to accumulate inside the pocket, harboring even more bacteria. This action also allows bacteria to enter the bloodstream. Studies have shown that heart disease is almost twice as high in people with gum disease. Studies have also shown that the most common strain of bacteria found in dental plaque may cause blood clots. When blood clots escape into the bloodstream, there is a relation to increased risk of heart attacks, and other heart illnesses.

[edit] References