For animals predisposed to, or afflicted with, periodontal disease, professional treatment is only part of the plan. What the owner does at home on a daily basis for plaque control has as much or more impact on the long-term prognosis. To understand why homecare is so important, it is important to understand some things about plaque and calculus and the progression of periodontal disease.
Following a professional dental cleaning, the tooth surface is considered clean. Within hours, a film of salivary glycoproteins, known as the acquired pellicle, starts to form on the exposed dental surfaces. In a few more hours, oral bacteria colonize this pellicle. This is the development of dental plaque, a mixture of salivary glycoproteins, sloughed epithelial cells, white blood cells, food particles and bacteria. Immature plaque is a rather disorganized slime on the tooth surface.
If immature plaque is left undisturbed, it becomes more organized and more firmly attached to the tooth surface. It starts to evolve into a highly complex society of co-operative and synergistic bacteria and protozoa. Aerobic bacteria live on the outer surface of this biofilm with anaerobes living closer to the tooth surface. The mixed populations of bacteria produce and secrete substances that act as a matrix, enhance adhesion, and protect the residents of the biofilm from chemical and cellular antimicrobial agents. Mature plaque is 25% bacteria, 75% matrix.
Within as little as two days, undisturbed plaque can start to precipitate salivary minerals to form calculus. Calculus itself does not cause periodontal disease, but it does provide a very safe environment in which the periodontal pathogens can live. Its rough, porous surface provides a foothold for the bacteria that is not easily dislodged. The bacteria in plaque produce toxins that cause inflammation of the gingiva. If left untreated, this gingivitis may progress to periodontitis (inflammation and destruction of the gingiva, periodontal ligament, alveolar bone, and root cementum). To prevent gingivitis and periodontitis from developing and to maintain gingival health, plaque must be removed before it becomes organized and mineralized.
From the above, you can see that if the owners are not doing anything for plaque control at home on a daily basis, noticeable calculus and gingivitis may be back by the two-week recheck appointment. Homecare refers to anything the owners are doing at home on a regular basis to control plaque and maintain periodontal health. In numerous studies, daily brushing of the teeth with a soft-bristled toothbrush has been shown to be the most effective means of plaque control. It is the mechanical action of the bristles against the tooth surface that removes the plaque.
The remainder of this paper will discuss some home-care products and how they work (according to manufacturer’s claims or as confirmed by independent research). Inclusion here does not imply an endorsement and exclusion does not imply an indictment. There are far too many to cover them all in three pages so you will have to apply the principles discussed to critically evaluate the claims of each product to see how it might fit into your dental program.
CHEMICAL PLAQUE CONTROL
Chemical plaque control agents come in many forms, including toothpastes, gels, rinses, water treatments and bioadhesive patches. No chemical agent has been shown to be effective in plaque control by itself. Most will reduce or retard plaque accumulation to a degree but they cannot stop it from forming.
Pastes are meant to be used on the toothbrush and may have a number of functions. Most veterinary pastes are flavoured for the peculiar taste preferences of dogs and cats and so can improve compliance. If the animal likes the taste of the paste, it becomes part of the positive reinforcement so important to establishing this habit. Pastes often have some abrasive material such as ground walnut shells, to improve the brush’s mechanical cleaning action.
VRx Pharmaceuticals produce a line of veterinary toothpastes under the brand C. E. T™. These pastes contain a “dual-enzyme system” consisting of glucose oxidase, lactoperoxidase, and a substrate (not specified). These ingredients combine with water (from saliva) and oxygen to eventually form hypothiocyanite (OSCN). This ion is produced naturally in human and canine saliva (possibly in cat saliva as well), where it has been shown to have an antibacterial effect.
I have never disputed the value of the endogenous salivary lactoperoxidase enzyme system as part of the host defense system. What I have asked on several occasions over the years is: “Is there any research to show that adding more of this enzyme system in a toothpaste or other product has any beneficial effect?” I know that brushing a pet’s teeth with C. E. T. will be beneficial, but would we get the same benefit from brushing with a placebo paste that lacks the enzyme system? To date, I have seen no such research. Therefore, I tell clients that many pets like the taste of C.E.T. and so it can be useful in boosting compliance. If it also does have some antibacterial effect, I look on that as a bonus. For now, I cannot support their antibacterial claims, as they have not shown me the science to back it up.
There are also a variety of gels and rinses available that act as oral antiseptics. The most common active ingredient in these products is chlorhexidine. Chlorhexidine is a non-specific antibacterial agent as well as having some effect on fungus and viruses. There is a large body of research on the efficacy of chlorhexidine as an antimicrobial agent. It acts by causing precipitation of the cytoplasmic contents of the bacterium, a mechanism against which resistance cannot develop. While chlorhexidine has been shown to reduce plaque and gingivitis, it paradoxically can increase the rate of mineralization of plaque (calculus formation). Chlorhexidine also causes a brown staining on the teeth when used as a rinse (can be polished off but looks terrible) and can cause a decrease in the sense of taste. Chlorhexidine is likely best used as a pre-operatative oral rinse and at home for the healing period following professional treatment.
MaxiGard™ is available as a gel and as a rinse. Both contain zinc and ascorbic acid (vitamin C). Zinc is antibacterial and important for healthy epithelium. Vitamin C is important in the production of collagen, which is the main structural protein in gingiva. The gel is tasteless and alcohol free and makes a nice oral anti-septic for the post-operative period. It has also found a use as a plaque retardant in cats that will tolerate no other forms of home-care. The zinc, though relatively tasteless, does increase salivation so some cats will froth and foam a bit with MaxiGard™.
CHEW TOYS
There are a variety of items on the market upon which dogs are meant to chew. Most of them will claim some dental benefit such as “Cleans Dog Teeth.” While many of these toys can legitimately claim to help keep a dog’s teeth clean, they can also a major cause of dental fracture. Examples would include dried cow hooves and all natural bone, whether processed or fresh from the butcher. Hard-pressed rawhide bones and nylon bones are also sufficiently resilient to cause dental fracture.
The criterion I use in practice is as follows. If you do not want me to hit you in the knee with a toy, then you should not give it to your dog to chew. If it is hard enough to hurt your knee, then it is hard enough to be a potential cause of dental fracture.
CHEW AIDS
This category would include consumable items that are not considered to be a significant source of calories such as rawhide strips and bones, pig’s ears, and Dental Ring™. Any item that you give to a dog with the understanding that it is to be chewed into little bits and possibly swallowed bears some risk of gastrointestinal upset or blockage. Consider each item and its relative risk and choose the safest one going.
Dental Ring™ is a ring of densely packed paperboard coated with ground bone, mint flavouring, and colouring. As the dog chews on the ring, teeth are expected to be forced between the layers of paperboard, thereby “brushing” the teeth. The label claims that the ring cleans teeth and strengthens enamel. While use of this device may help remove plaque and tartar, there is nothing in the ingredient panel that could be expected to strengthening enamel. In fact, chewing on the ground bone would be abrasive and would be more likely remove enamel. There is no indication on the label that there has been any research into the safety and efficacy of the product. Paper products are not digestible so if a dog swallows a chunk of the ring, gastro-intestinal blockage is a possibility.
Pig’s ears are available at many pet stores and flea markets. They are basically just pigskin and cartilage, often dried and smoked to prevent decay. The skin-cartilage parfait has a mild abrasive effect on the tooth surfaces without great risk of being too abrasive. The thin and flexible nature of pig’s ears makes them very unlikely to cause dental fractures. Some dogs tolerate these aids very well, while others may experience digestive upset. As the ears are sold from bulk bins generically, there is no assurance of quality control and there have been rumblings that they may harbour bacterial pathogens such as salmonella, so buyer-be-ware. If a large chunk of an ear is swallowed, it will likely be broken down by gastric juices and pass without incident. However, choking and esophageal blockage are possible. To my knowledge, no research has been published to determine the efficacy of pig’s ears in the prevention of dental disease.
Rawhide strips are a consumable that many dogs really love, but as they provide non-digestible protein, they do not add to the caloric intake. Therefore, they are discussed here. Dr. Ballards™ markets rawhide strips under the brand Chew-eez™. Each strip is approximately 3-4 cm wide, 10 cm long and 1-2 millimeter thick. I consider these to be among the safest chew aids you can recommend. There is still a risk of choking, but this is a very rare event. A brand name offers some quality assurance and the thinness of the strips makes it very unlikely that any teeth will be damaged. The abrasive action of chewing the rawhide does help reduce plaque, calculus, and gingivitis.
TREATS
Treats would include any consumable item that adds to the total calorie intake but that is not the main source of calories. No treat has ever been shown to be able to maintain clinically healthy gingiva, no matter how much of it is fed. Treats are only a part of the plaque control program and should be used as well as, not instead of, brushing.
DentaBone™ is a compressed tapioca-based treat that has been shown in numerous short-term studies to reduce plaque, calculus and stain while improving gingival health when given daily. Personally, I have some misgivings about these very hard treats as a potential cause for dental fracture. I know of no confirmed cases of this happening.
C.E.T. Forte Chews™ are designed for cats as a mildly abrasive treat intended to improve oral hygiene. They are available in fish and poultry flavour, though freeze-dried fish is the main ingredient in both. These chews contain the same dual-enzyme system found in other C.E.T. products. Whether it is the course texture of the chew mechanically helping to remove plaque, the enzyme system or a combination, is not clear from the research. In any event, a controlled study in client-owned cats, found a statistically significant reduction in gingivitis when the cats received one chew a day compared to eating the same diet without the daily chew.
DIETS
No diet has ever been shown to be able to maintain clinically healthy gingiva, no matter how much of it is fed. Diets are only a part of the plaque control program and should be used as well as, not instead of, brushing.
It has long been felt that feeding a cat or a dog a dry kibble diet is better for the teeth than feeding them a processed, canned diet. The logic goes that dry food leaves less residue in the mouth for oral bacteria to feed on and so plaque would accumulate at a slower rate. Despite that, many animals fed on commercial dry diets still have heavy plaque and calculus accumulations and periodontal disease. This is because most dry pet foods are hard but brittle so that the kibble shatters without much resistance and so there is little or no abrasive effect from chewing.
There are currently four commercially available pet foods that have received recognition by the Veterinary Oral Health Council as having a significant effect on plaque, calculus, and gingivitis. These are Hill’s Prescription Diet t/d, Hills Prescription Diet t/d small bites, Hill’s Prescription Diet t/d feline, and Friskies Dental Diet (feline).
The mechanism of action for these diets is based on the physical properties of the kibble. Each nugget is quite large and so must be chewed before swallowing. The nuggets are hard but not brittle, so the teeth sink deep into the nugget before it splits. As the tooth is penetrating the nugget, the fibers in the food gently abrade the tooth surface, thereby removing plaque.
These diets are high-fiber maintenance diets for average mature animals but would not be appropriate to support growth, gestation/lactation, or a very athletic life-style. Each of them is intended to be fed as the main calorie source. Research by Hill’s found that the best results were obtained in this manner, but that there was still a measurable (but declining) benefit when the t/d diets were fed as 75%, 50%, and even 25% of the total calorie intake. Using t/d simply as a treat will not meet expectations for the product. It seems reasonable to extrapolate this observation to the Friskies Dental Diet, though I have not seen research examining this issue for this product.
MISCELLANEOUS
ProVSeal™ is a waxy polymer that is applied to the teeth following an oral hygiene procedure. The theory is that the wax adheres tenaciously to the enamel and creates a non-wetable surface, thereby inhibiting bacterial adhesion to the tooth. This product is used in human dentistry under the name OraStar™.
As the patient eats or brushes, the surface layer of wax is removed, exposing a fresh layer. Research indicates that the product may still be on the tooth surface up to eight days post-application. There is also research to back up the claims of safety and efficacy. After the initial treatment has worn off, there is a less viscous wax product that can be applied by the owner on a regular basis to continue inhibiting adhesion of plaque bacteria. The hydrophobic nature of the product allows it to be applied to wet teeth in a conscious patient. This product claims to be tasteless, odourless, invisible, and non-toxic. It does not preclude the use of abrasive diets and chew aids, nor is there any need to reduce or curtail tooth brushing.
ProVSeal™ may be most beneficial as a plaque retardant in the immediate post-operative period, when it is sometimes necessary to have the owners suspend their home-care for a week or so during healing of extraction sites and periodontal surgery site.