Periodontal Disease

Introduction

Periodontal disease is essentially an inflammatory response by the supporting structures of the teeth known as the periodontium. These structures include the gingiva, periodontal ligaments, cementum and alveolar bone.

It is the most common dental disease in dogs and cats and the major cause of tooth loss in both species. There are numerous factors that contribute to the formation of the disease but the primary agent is dental plaque. Plaque accumulates at the gingival margin, partly due to insufficient oral hygiene.

Initially, the bacterial flora tend to be non-motile aerobes or facultative anaerobes. However, as the supply of oxygen is reduced by supragingival plaque accumulation and pocket formation, the bacterial flora become more motile and anaerobic. Important bacterial flora responsible include Porphyromonas gingivalis, Bacteroides asaccharolyticus, Fusobacterium nucleatum, Actinomyces viscosus and Actinomyces odontolyticus.

Gingivitis and periodontitis are the two main forms of the disease. Gingivitis is the early form of the disease and often but not always progresses to periodontitis.

Gingival inflammation starts because of dental calculus (tartar) from diets high in minerals and diets consisting of soft rather than hard crunchy food. Dental plaque becomes calcified and whole crown may become covered in brown chalky material. Calculus gives brittle dirty brown covering to tooth which may not affect enamel at all but may produce mild gingivitis round edge and the gum may start to recede. This exposes more of crown, may reach level of dentine and infection may enter the alveolus and loosen ligaments holding tooth in and ultimately the tooth will become loose and fall out.

Gingivitis - Reversible inflammation of the marginal gingival tissues that does not affect the periodontal ligament or the alveolar bone.

Periodontitis - Inflammation and irreversible destruction of the tooth's supporting structures that includes the gingiva, periodontal ligament, alveolar bone and root cementum. It usually occurs after years of plaque accumulation and gingivitis. The epithelial attachments of the tooth regress apically and there is absorption of the associated alveolar bone, resulting in permanent loss of tooth support.

Periodontal pocket - this describes the area of tissue destruction left by periodontitis. It is an attachment loss due to destruction of the fibres and bone that support the tooth which results in a pathological deepening of the gingival sulcus.

Signalment

Pure bred cats are particularly susceptible and include: Burmese, Persian, Siamese and Maine Coon. The disease affects majority of cats over two years of age.

Certain breeds of dogs are thought to be susceptible to an aggressive form of the disease and include: Greyhound and Maltese. Small breed dogs are more prone to tooth crowding, predisposing the animal to the initiation and rapid progression of the disease.

Clinical Signs

Clinical signs include fetid breath odour (halitosis), excessive salivation, blood in saliva, dysphagia, pain on mastication and difficulty eating. There may also be loose teeth. The animal may be lethargic and show signs of weight loss and poor grooming (cats).

Diagnosis

Clinical signs are indicative of oral disease.

An oral examination should be performed. This is the most important part of the diagnostic procedure and should include inspection of extraoral structures (looking for swelling, atrophy or asymmetry), such as face, lips, muscles of mastication, temporomandibular joints, salivary glands, lymph nodes, maxillae and mandibles. Intraoral structures such as the dentition, gingiva, mucosa, tongue, tonsils and dental occlusion should also be thoroughly examined. On visual inspection of the intraoral structures, an animal with periodontitis may demonstrate oral mucosal ulceration, inflammed and bleeding gingiva, loss of normal gingival contour, purulent discharge from the periodontal pocket, gingival recession, loose teeth and presence of variable quantities of plaque and calculus on the tooth surface.

A thorough periodontal examination of dogs should always be performed under general anaesthesia. The examination under general anaesthesia in cats allows a more detailed evaluation of the oral cavity. The periodontal examination is performed using a periodontal probe which is gently run under the gingival margin of each tooth. An evaluation is made of the amount of plaque and calculus present on the tooth surface, the degree of gingivitis and the presence of gingival hyperplasia or recession. The degree of attachment loss and bone resorption at the furcation is also investigated as well as the mobility of individual teeth.

The disease can then be staged:

• Stage 0 - Normal and healthy periodontium
• Stage 1 - Periodontal disease/Gingivitis (0% attachment loss, Pocket depth <0.5mm)
• Stage 2 - Early periodontal disease (<25% attachment loss, Pocket depth <1.0mm)
• Stage 3 - Moderate periodontal disease (25-50% attachment loss, Pocket depth <2.0mm)
• Stage 4 - Severe periodontal disease (>50% attachment loss, Pocket depth >2.0mm)

Oral radiography can be used to assess periodontal disease. Cases of periodontitis will show generalised horizontal and vertical alveolar bone loss in focal areas. Radiographic signs of periodontal disease include resorption/rounding of the alveolar margin, widening of the periodontal space, loss of the lamina dura (cortical bone of the alveolus) and alveolar bone destruction.

Radiography allows to further characterise the type of periodontal pockets present. The two types are defined based on the relationship of the base of the pocket to the crest of the alveolar bone:

Suprabony pocket: this occurs when there is horizontal bone loss and the base of the pocket is located above the crest of the alveolar bone.

Infrabony pocket: this occurs when there is vertical bone loss and the base of the pocket is located below the crest of the alveolar bone within a trench-like area of bone.

Treatment

Gingivitis

Treatment of gingivitis relies heavily on owner compliance. It is important to stress to the owner that the disease is reversible and treatment and control may prevent this disease from becoming peridontitis, which is a lot more severe.

The owner should receive information on good daily dental home care such as tooth brushing and diet.

Treatment involves performing a dental scale and polish and ensuring the owner is aware that regular examinations to assess the condition of the teeth will be required from now on.

Periodontitis

Educate the owner of the disease process and also educate them on good daily dental home care such as tooth brushing and diet.

Perform a dental scale and polish and root surface debridement. Teeth with severe periodontitis will need to be extracted and periodontal surgery may be necessary.

Regular examinations to assess the condition of the teeth are vital and the owner needs to be made aware of this.

Periodontal pockets

With pocket depths below 5mm, dental scaling and polishing should be performed, and then subgingival curettage and the placement of an antibiotic gel in the pocket may help rejuvenate the periodontal tissues and reduce pocket depth.

With pocket depths greater that 5mm, surgery is needed to either expose the root for treatment or extract. Gingival flaps or bony replacement procedures for infrabony pockets can be used to decrease pocket depths in areas of alveolar bone loss.

Periodontal Disease Learning Resources
Flashcards Test your knowledge using flashcard type questions	Veterinary Dentistry Q&A 11

References

Tutt, C., Deeprose, J. and Crossley, D. (2007) BSAVA Manual of Canine and Feline Dentistry (3rd Edition) BSAVA

Merck & Co (2008) The Merck Veterinary Manual Merial

Lobprise, H. (2007) Blackwell's five minute consult clinical companion: small animal dentistry Wiley-Blackwell