Royal Canin Nutritional Information

Royal Canin Nutritional Information

Food is a useful tool for the prevention of periodontal disease, as it helps to slow down the development of dental plaque and calculus. The most efficient approach combines a mechanical effect coupled with active ingredients. (© Renner).

Key Points in the Analysis of:

Ingredients that Play a Role in the Prevention of Periodontal Disease

Kibbles with a dental function have a special form and texture that obliges the dog to chew to obtain a light abrasion of the teeth. However, kibbles are less effective than brushing.

When it comes to oral hygiene, the kibble can support the active agents which are released in the oral cavity during mastication. Upon release, the active agents are incorporated with saliva. Until now, the objective of various solutions has been to limit bacterial proliferation through substances that have a bacteriostatic or even bactericidal effect. The inconvenience of these products is that they disrupt the natural floral equilibrium, because the bacterial action targets all bacteria, even beneficial strains.

New lines of research are focusing on molecules that limit the adhesion of bacteria to the surface of the teeth.

Frequently Asked Questions: about Kibbles with a Dental Function

Kibbles with a dental function.

1. Evaluation of the Logan & Boyce Plaque Index for a Study on the Accumulation of Dental Plaque in the Dog

Many index systems have been developed to evaluate the accumulation of plaque on the dental surfaces. The Silness & Loë index (1964) focuses on the thickness of the plaque that accumulates on the tooth along the gingival line, while most methods evaluate the spread of the plaque on the dental surface after the action of a colorant; e.g., Quigley & Hein (1962), Turesky et al (1970).

• A modification of the Turesky index was introduced into veterinary dentistry by Logan & Boyce (1994). This index has since been used in several studies evaluating the influence of chewing toys, bones or specific foods on the formation of dental plaque (Gorrel, 1999; Logan et al., 2002). Since this new evaluation method differs significantly from the original Turesky index, the name Logan & Boyce index has been proposed (Hennet, 1999). In the original description of this index, a horizontal division of the surface of the crown in two parts (coronary and gingival) was proposed, without this being precisely described (Logan & Boyce, 1994). Other systems used in human dentistry, like the Navy plaque index, use a horizontal division of the surface of the crown, based on anatomical criteria (Fischman, 1986, 1988). In contrast to the Turesky method, the Logan & Boyce index evaluates the surface and the thickness of the plaque on every half of the dental crown. The intensity of coloration (light, medium or intense) is used to evaluate the thickness of the plaque. The Logan & Boyce index has been validated for use in veterinary dentistry (Gorrel, 1999). But to our knowledge, no study has been published to document the reliability of this index in dogs (intraobserver repeatability and inter-observer reproducibility).
• The aim of this study was to follow the repeatability of the scores provided by an experienced observer (intra-observer repeatability) and to compare the scores provided by an experienced or inexperienced observer (inter-observer reproducibility), utilizing the Logan & Boyce index. The authors were also interested in the influence of a modified Logan & Boyce index, in which the anatomical points are used for a horizontal division of the tooth, and an intensity gradient was used to evaluate the intensity of coloration, so as to improve the repeatability of the measures.

Anatomical points for the horizontal division of the teeth. (© Hennet).

Third incisor: Horizontal line to the gingival line at the distal tubercle of the second incisor.
Canine: Horizontal line to the gingival line at the level of the cusp of the first premolar.
Second and third premolars: Horizontal line to the gingival line at the distal tubercle of the first incisor.
Fourth premolar: Horizontal line to the gingival line at the distal talon.
First molar: Horizontal line to the gingival line at the oral tubercle of the tooth.

2. Prevention of Periodontal Disease: Complementing the Mechanical Action with Active Principles

A survey conducted in the United 20.5% and 19.5%), ahead of otitis preservative care. Prevention States on more than 30,000 dogs externa, dermatoses and infesta-continues to be the best approach presented to their veterinarian tion by fleas (Lund, 1999). A specta-in the fight against the develop-shows that calculus and gingivitis cular advance in the field of veteri-ment of this disease, however this are the most common presenting nary dentistry means we can offer is often neglected in comparison complaints (respective prevalence companion animals effective and with other disease conditions.

Figure 11. Comparison of plaque and calculus deposits 28 days after scaling (Sources Royal Canin, 2004).

3. Significance of Specific Phosphates for Oral Health

The use of polyphosphate salts is significant because they chelate salivary calcium. Chelation varies depending on the type of polyphosphate. To facilitate the release and the contact with salivary calcium, the polyphosphates must be incorporated into the external coating of the kibble.

The Various Types of Phosphate

Phosphates constitute a very large family of more than 150 different molecules (including orthophosphate, pyrophosphate, polyphosphate and metaphosphate). Some phosphates present sequestering properties with bivalent cations such as calcium (e.g., Ca2+). These properties depend on the length of the phosphate chain (the longer the chain, the greater their capacity to chelate bivalent cations) and on the local pH. These types of compounds are used in many human toothpastes (Sowinski et al., 1998).

Phosphates: Type of Action

The Ca2+ cations in saliva have a direct role in the calcification of dental plaque (calculus deposition). The phosphates which are able to chelate polyvalent cations will be able to capture the Ca++ cations in the saliva. If polyphosphates are released in the oral cavity they will naturally chelate the salivary calcium in ionic form, thus limiting its integration in the dental calculus matrix. Calcium is then released as normal in the digestive tract and absorbed by the organism in accordance with its needs.

Action of the sodium tripolyphosphate.

Molecule of sodium tripolyphosphate.

Reaction between sodium tripolyphosphate and ca2+ cations.

Scientific Studies

The anti-calcification effect of hexametaphosphate (HMP) on the dental biofilm has been verified in vitro where the formation of calcium hydroxyapatite crystals was shown to be significantly reduced (White et al., 2002).

Beagles fed for one month with kibbles coated with HMP present a significantly reduced calculus deposit (-58%) compared with dogs fed with the same diet when polyphosphates were incorporated into the interior of the kibble (Cox et al., 2002).

The chelating effect varies depending on the type of polyphosphate used, even when the dose is identical. Compared with a control group, the reduction in the calculus deposit after a month among Beagles given kibbles coated with polyphosphates was as follows:
- 36% with hexametaphosphate
- 55% with sodium tripolyphosphate
(Royal Canin Research Centre, 2001 - 2002)

4. Significance of Zinc Salts for Oral Health

Zinc salts have potential beneficial effects in the area of oral health. They can act as oral antiseptics that tend to limit bacterial proliferation in the oral cavity, and can reduce the formation of dental plaque and calculus.

Dental plaque. More than 300 strains of bacteria are present in the oral cavity. Streptococci and Actinomyces, which have adherence properties, are the first to colonize the dental biofilm. The primary supragingival plaque will reach the sub-gingival area, where the development of an anaerobic flora is favored. This transition from a commensal flora to a pathogenic bacterial population is responsible for the development of periodontal disease.

The Various Zinc Salts

There is organic zinc (e.g., zinc citrate) and inorganic zinc (e.g., zinc sulfate, ZnSO42-).

Scientific Studies

Inhibition of Calculus Formation

In vitro the zinc salts can help limit the deposit of dental calculus by inhibiting the formation of calcium hydroxyapatite complex, and by promoting the formation of more soluble calcareous complexes like tricalcium phosphate.

A study conducted on rats has shown that animals whose teeth are brushed with a toothpaste formulated with zinc salts present significantly less calculus deposit than the control group (Putt et al., 2002). This finding has been confirmed in humans (Sowinski et al., 2001; Barrea et al., 2001).

Inhibition of the Production of Sulfonated Volatile Fatty Acids

In vitro the zinc salts help control the production of foul-smelling molecules responsible for halitosis (Weesner, 2003).

A study of humans has also shown that zinc salts inhibit the production of foul-smelling volatile fatty acids from 14C-glucose (Harrap et al., 1984).

Inhibition of Bacterial Growth

The zinc salts present bacteriostatic properties that have been demonstrated in vitro, especially a high anti-microbial activity against Streptococcus mutans (Belcastro et al., 1994).

This anti-microbial activity has been confirmed in cats. A significant reduction in plaque deposition and the burden of anaerobic pathogenic bacteria involved in periodontal disease have been observed in a group of cats treated with a gel containing zinc salts (Clarke, 2001).

5. Significance of Specific Polyphenols for Oral Health

Some polyphenol sources can be incorporated into the food to limit the formation of dental biofilm. Green tea, which is rich in active polyphenols (e.g., epigallocatechin gallate or EGCg), is considered to be beneficial in the prevention of periodontal disease.

The Various Types of Polyphenols

More than 8000 types of polyphenol have been identified. Some have a highly complex chemical structure. This decidedly varied group comprises molecules containing a simple phenolic nucleus and highly polymerized compounds (tannins). Naturally present in all living beings, polyphenols play an essential antioxidant role.

Polyphenols: type of Action

The bacteriostatic action of certain polyphenols is allied to their antioxidant properties, especially to the presence of the hydroxyl group (OH-) in ortho configuration, as well as the presence of the gallate function on the phenolic ring.

Scientific Studies

Inhibition of the Growth of Bacteria in Dental Plaque

In dogs, the flora of the periodontal pockets is marked by the presence of specific bacteria, such as Porphyromonas endodontalis, gingivalis and circumdentaria (Isogai et al., 1999).

• In vitro
  Certain phenolic compounds (particularly those of the catechin family) present an anti-bacterial effect against the bacteria in the dental plaque, such as Porphyromonas gingivalis and Prevotella spp. (Hirasawa et al., 2002), Escherichia coli, Streptococcus salivarius and Streptococcus mutans (Rasheed et al., 1998).
  Among the polyphenols present in green tea, epigallocatechin gallate (EGCg) has the strongest bactericidal activity. Its minimal inhibition concentration is between 250 and 500 µg/mL depending on the various strains of Porphyromonas gingivalis (Sakanaka et al., 1996).
• In vivo
  In dogs, a diet formulated with green tea, which is naturally rich in catechins, has helped inhibit the growth of bacteria and after two months, to significantly reduce the Porphyromonas percentage in the microbial population of dental plaque (Isogai et al; 1995, 1992).

Inhibition of the Capacity of Bacteria to Adhere to the Epithelial Cells in the Mouth

In vitro, the polyphenols contain a gallate function (epigallocatechin gallate or EGCg; gallocatechin gallate or GCg; catechin gallate or Cg), which reduces the capacity of Porphyromonas gingivalis to adhere to the surface of epithelial cells (Sakanaka et al., 1996).

Figure 12. The catechin family.

On average, every epithelial cell can capture 300 P. gingivalis. At 250 µg/mL of pure polyphenols (which possess a gallate function), the inhibition of the adherence is almost complete, but at 7.8 µg/mL the number of P. gingivalis adhering is reduced by 30% (Sakanaka et al., 1996). According to these authors the anti-adhesion capacities of polyphenols will be targeted on the bacteria rather than the epithelial cells.

The adhesion of other bacteria is also limited by polyphenols which possess a gallate function.

At concentrations between 125 and 250 µg/mL the adhesion of Porphyromonas melaninogenicus and Streptococcus sanguis is reduced by 50%. Streptococcus sanguis is one of the first bacteria that leads to the formation of plaque (Sakanaka et al., 1996).

Inhibition of the Production of Acid Metabolites by the Bacteria of Dental Plaque

The bacteria of the plaque (such as Porphyromonas gingivalis) generate acids: n-butyric acid, phenylacetic acid or propionic acid. In vitro, some polyphenols are capable of inhibiting the production of these acid metabolites generated by the bacteria of the plaque (e.g., Porphyromonas gingivalis). This inhibitor effect is due to the presence of the gallate function of certain phenolic compounds, especially EGCg, GCg, and Cg, which are present in green tea (Sakanaka et al., 2004).

Figure 13. Roles of polyphenols. Polyphenols are known among humans for their protective qualities against cardiovascular diseases (hypolipemic effect). In dogs, they are valued for their major antioxidant activity and for their antiseptic role against certain bacteria of dental plaque.

6. Significance of Specific Essential Oils for Oral Health

Some essential oils (e.g., eucalyptus oil) act to reduce bad breath and gingiva inflammation, while curbing bacterial proliferation.

Which Essential Oils?

Manuka oil, tea oil, eucalyptus oil, lavender oil and rosemary oil.

Oils rich in antioxidant molecules have a bacteriostatic or bacteriocidal action.

Scientific Studies

Inhibition of Bad Breath

Some oils, notably eucalyptus or rosemary oil, help to limit bad breath (halitosis). The significance of eucalyptus oil is due to the fact that it not only masks bad smells, but actively participates in reducing the production of sulfonated volatile fatty acids.

In a study evaluating volative sulfonated compounds (VSCs), cookies containing 0.1 % eucalyptus role significantly reduced bad breath in dogs, compared to a control group (Waltham Research Centre, 2001).

Inhibition of Inflammatory Activity

In vitro, 1.8-cineol (or eucalyptol), the main eucalyptus monoterpene, inhibits the metabolism of arachidonic acid which produces molecules that cause inflammation (prostaglandins E2 and B4), and cytokines in human monocytes. This mechanism is promissing for limiting the development of nascent gingivitis (Juergens et al., 2003).

Inhibition of Bacterial Activity

Eucalyptus oil inhibits the growth of certain bacteria involved in periodontal disease such as Porphyromonas gingivalis, Fusobacterium nucleatum, Streptococcus mutans and Streptococcus sobrinus. These periodontogenic bacteria are destroyed by 30 minutes of exposure to a solution containing 0.2% of eucalyptus or rosemary oil. The eucalyptus oil inhibits the adhesion of Streptococcus mutans (Takarada et al., 2004).

Conclusion

Periodontal disease always develops from the bacterial biofilm that makes up the dental plaque. Any factors that can limit the formation of this plaque are potentially significant. Brushing the teeth with toothpaste adapted for dogs remains the best means of preventing the formation of dental plaque. The kibbles can be complementary to brushing due to their mechanical (crunching-friction) and chemical (anti-plaque/calculus actives) actions. Further studies are required to determine how to optimize the liberation of these active substances in the oral cavity (in the coating or in the interior of the kibble).

7. Short- to Medium-term Effect of a Chewing Bar on Dental Deposits in Dogs

Over a Short Period (28 Days)

The combination of traditional kibbles and a chewing bar for daily use was associated with a significant reduction in plaque deposition [-27%; p-value < 0.05] and the formation of calculus [-53%; p-value < 0.05], compared with a diet constituted solely of traditional kibbles.

Over a Short Period (28 Days)

The combination of traditional kibbles and a chewing bar for daily use is more effective than commercially available kibbles that are specially designed for oral hygiene, in terms of both plaque [-12%; p-value < 0.084] and calculus deposit reduction [-37%; p-value < 0.077].

Over a Longer Period (4 Months)

The combination of traditional kibbles and a chewing bar for daily use is associated with a significant reduction in plaque deposit [-17%; p-value < 0.05] and the accumulation of calculus [-45%; p-value < 0.05], compared with a food constituted solely of kibbles.

Figure 14. Overall plaque scores (4 months after scaling).

Figure 15. Overall calculus scores (4 months after scaling).

Cavalier King Charles. A specially conceived chewing bar (formula, texture, shape and size) is an effective means of preventing periodontal disease as it limits dental deposits. This product is recommended as soon as the dog's final dentition has erupted.