Periodontal Disease in Small Animals

II. Etiology and Pathogenesis

• Primary Cause: Accumulation of plaque bacteria on the tooth surface, which elicits a host immune response.

• Plaque Components: Plaque is a soft film composed of food particles, salivary glycoproteins/minerals, and bacteria. It is a biofilm, making microorganisms more resistant to antimicrobials.

    ◦ Plaque continuously forms and is the precursor to calculus (tartar).

    ◦ Gingivitis is caused by bacterial plaque on the crown surface stimulating an inflammatory response in the marginal gingiva.

• Bacterial Population Shifts:

    ◦ Healthy Mouth: Predominantly nonmotile, gram-positive aerobes (Staphylococcus spp, Streptococcus spp) existing in commensal harmony.

    ◦ Pathogenic State: If plaque thickens and oxygen is depleted, the population shifts to a higher percentage of nonmotile, gram-negative anaerobic rods.

• Periodontopathogens (Found in PD): Bacteroides fragilis, Peptostreptococcus, Porphyromonas salivosa, Porphyromonas denticanis, Prevotella intermedia, Treponema spp, and Bacteroides splanchnicus.

• Periodontitis Development: Caused by the host’s response to subgingival plaque. Inflammatory mediators produced by the host, along with bacterial products, contribute directly to bone and tissue damage.

• Calculus (Tartar): The mineralized form of plaque, matured by salivary minerals. It creates a protective barrier for bacteria and causes mechanical irritation, leading to periodontium breakdown.

III. Clinical Findings and Diagnosis

• Key Clinical Signs: Halitosis (bad breath), plaque/calculus, red/swollen/bleeding gums (gingivitis), gingival recession, periodontal pocketing, bone loss, furcation exposure, mobile teeth, and eventual loss of teeth.

• Diagnostic Tools (Under General Anesthesia):

    ◦ Periodontal Probing.

    ◦ Intraoral Dental Radiography (strongly recommended for all dental patients).

    ◦ Advanced imaging (e.g., CT) may be used for treatment planning.

A. Anesthetized Oral Examination

• Allows evaluation of structures supporting the teeth, as well as soft tissues (tongue, tonsils, palates, buccal mucosa).

• Periodontal Probing: Used to measure sulcus depth and assess furcation exposure and mobility.

    ◦ Normal accepted probing depth for the dog is 1–3 mm.

    ◦ Normal accepted probing depth for the cat is 0.5–1 mm.

    ◦ Increased depth suggests advanced disease/attachment loss.

• Furcation Exposure (Multirooted Teeth):

    ◦ Stage 1: Probe extends less than halfway under the crown.

    ◦ Stage 2: Probe extends approximately halfway under the crown but not all the way through.

    ◦ Stage 3: Probe extends completely through the furcation.

• Mobility: Physiologic movement is allowed by the periodontal ligament.

    ◦ Stage 0: Up to 0.2 mm (physiologic).

    ◦ Stage 1: > 0.2 mm up to 0.5 mm.

    ◦ Stage 2: > 0.5 mm up to 1 mm.

    ◦ Stage 3: > 1 mm or any axial movement (depressed into the alveolus).

B. Grading and Staging

• Calculus Grading (0–3): Ranges from 0 (None) to 3 (Heavy supragingival calculus with substantial subgingival deposition).

• Gingivitis Grading (0–3): Ranges from 0 (Normal gingiva) to 3 (Severe swelling and redness, with spontaneous bleeding).

• Stages of Periodontal Disease (0–4):

    ◦ Stage 0: No Gingivitis, No Attachment Loss (healthy).

    ◦ Stage 1: Gingivitis present, No Attachment Loss.

    ◦ Stage 2 (Early Periodontitis): Gingivitis present, < 25% Attachment Loss or Stage 1 furcation involvement.

    ◦ Stage 3 (Moderate Periodontitis): Gingivitis present, 25%–50% Attachment Loss or Stage 2 furcation involvement.

    ◦ Stage 4 (Advanced Periodontitis): Gingivitis present, > 50% Attachment Loss or Stage 3 furcation involvement.

C. Occlusion and Malocclusions

• Occlusion (the animal's bite) should be symmetrical on the right and left sides.

• Five Main Characteristics of Normal Occlusion:

    1. Midline Match: Maxillary and mandibular incisors meet at midline.

    2. Incisor Overlap: Maxillary incisor cusps are just in front of mandibular incisor cusps; mandibular incisors occlude in the cingulum of the maxillary incisors.

    3. Canine Interlock: Mandibular canine is positioned between the maxillary third incisor and the maxillary canine, angled slightly toward the buccal surface.

    4. Premolar Interdigitation: Maxillary premolar cusp tips are positioned in the space created by the mandibular premolar teeth.

    5. Carnassial Overlap: Maxillary fourth premolar and mandibular first molar overlap, with the maxillary tooth overlapping the mandibular tooth on the buccal aspect.

• Malocclusion Classifications (4 Classes):

    ◦ Class 1 (Neutroclusion): Normal jaw relationship, but malposition of one or more teeth.

    ◦ Class 2 (Mandibular Distoclusion/Parrot Mouth): Mandible positioned caudal to the maxilla (mandible appears too short).

    ◦ Class 3 (Mandibular Mesioclusion/Monkey Mouth): Mandible positioned rostral to the maxilla (mandible appears too long).

    ◦ Class 4 (Maxillomandibular Asymmetry): Includes rostrocaudal malalignment, side-to-side malalignment, and dorsoventral malalignment (open bite).

IV. Treatment

• Treatment requires professional dental cleaning and therapy. It depends on the severity of attachment loss.

• Treatment of Gingivitis: Removal of bacterial plaque is essential, typically achieved through professional dental cleaning (scaling and polishing) under general anesthesia. This can reverse gingivitis.

    ◦ Note: Cleaning an awake animal only improves cosmetic appearance and fails to treat subgingival disease.

• Treatment of Periodontitis (Requires Aggressive Treatment):

    ◦ Closed Periodontal Treatment: Root planing and gingival curettage performed without creating a mucoperiosteal flap, typically for shallow pockets.

    ◦ Open Periodontal Treatment: Creation of a mucogingival flap to expose the root surface and alveolar bone for adequate treatment (root scaling, planing, and alveoloplasty). Required for pockets deeper than 5–6 mm.

    ◦ Medications: Local administration of antiseptic and anti-inflammatory drugs, such as a perioceutic agent containing antimicrobials (e.g., doxycycline).

    ◦ Regenerative Procedures: Bone grafts, bone graft substitutes, or barrier membranes can be used to augment lost alveolar bone and achieve guided tissue regeneration.

    ◦ Dental Extraction: Often the best treatment for non-salvageable teeth with poor prognosis, increased mobility, and significant attachment loss. Extraction is definitive, and pets can have an excellent and improved quality of life without the diseased teeth.

    ◦ Complex Cases: Teeth with secondary endodontic disease (due to progression of periodontitis) require both periodontal and endodontic treatment.

V. Prevention

• Prevention focuses on plaque removal and control. Disease recurrence is likely without drastic changes in home oral hygiene.

• Daily Home Care (Most Effective):

    ◦ Toothbrushing: Daily or at least every other day is the most effective way to improve and maintain periodontal health. Biofilms are easily and effectively removed mechanically this way.

    ◦ Only the outside (labial and buccal) surfaces need brushing in most patients, as the tongue helps cleanse the lingual/palatal surfaces.

    ◦ Plaque that remains undisturbed for more than two days mineralizes into calculus, which cannot be removed by brushing.

    ◦ Alternatively, wiping teeth with a gauze pad at least every second day can decrease plaque accumulation.

• Dietary and Product Control:

    ◦ Chews/Toys/Diet: Firm, fibrous items can remove plaque (and occasionally calculus) during chewing. However, hard items (e.g., bones, hooves) should be avoided due to the risk of cracking teeth.

    ◦ Formulated Products: Dental diets; chews, treats, and toys; oral gels, rinses, and sprays; and water/food additives can help stabilize PD. Some diets include ingredients like chlorhexidine (to decrease bacteria) or polyphosphates (to slow mineralization).

    ◦ The Veterinary Oral Health Council (VOHC) website provides information on products that meet requirements for plaque and calculus control.

• Addressing Predisposing Factors:

    ◦ Anatomical: Use selective surgical extractions to relieve severe crowding or supernumerary teeth.

    ◦ Systemic: Diagnose, treat, and control metabolic conditions (e.g., diabetes mellitus, renal failure).

    ◦ Behavioral: Identify and modify inappropriate habits (e.g., cage biting, rock chewing) and toy selection.