Treatment for gingivitis

A glycerine solution of zinc chloride or another pharmaceutically acceptable zinc salt that is soluble in glycerine provides effective therapy for gingivitis when applied to the gingivae and teeth.

TECHNICAL FIELD 
Normal gingivae are pink and firmly attached to the underlying alveolar 
bone. At the enamel-gingival junction, the gingiva forms an 
epithelial-lined ridge around the teeth. The area between the enamel and 
the gingivae is called the gingival crevice. Gingivitis develops when 
large masses of bacteria clog the gingival crevice. 
Bacteria invade the surrounding area and form a sticky matrix, called 
plaque. If plaque is left undisturbed, it calcifies into calculus. 
Bacteria in plaque produce metabolic by-products, enzymes and toxins. 
These products diffuse into the immediate surrounding area, irritate the 
gingivae, and, as a consequence, they trigger a localized inflammatory 
reaction. The gingivae swell, become reddened and extrude crevicular 
fluid. Depending on the severity of the condition, the gingivae become 
sensitive to touch and may spontaneously bleed. As gingivitis advances to 
periodontitis, the supporting collagen fibers and the alveolar bone begin 
to degenerate. As a result, teeth become mobile and eventually fall out. 
BACKGROUND ART 
There are numerous studies that demonstrate that the accumulated plaque at 
the enamel-gingival junction significantly increases the severity of the 
gingival disease, while other studies show that when plaque is removed, 
healthy condition is reestablished. Because of the apparent direct cause 
and effect relationship between plaque and gingival inflammation, it is 
widely believed that plaque accumulation is detrimental to gingival 
health. 
It has been suggested that if the accumulation of plaque at the 
enamel-gingival junction can be prevented or at least retarded, the 
severity of gingivitis and periodontitis can thereby be reduced. 
Compton and Beagrie (Journal of Clinical Periodontology:1975:2:33-43) 
tested the effectiveness of a quaternary ammonium compound, benzethonium 
chloride, and zinc chloride in preventing plaque and gingivitis. The above 
two agents were tested separately and also in combination. According to 
the authors, the results showed no significant differences in the gingival 
scores after a ten day test period during which the results of using 
mouthwashes comprising 1 part glycerine to 20 parts of water and 
containing (a) 0.22% by weight ZnCl.sub.2, (b) 0.075% benzethonium 
chloride, and (c) a combination of the two were compared to the results 
with the placebo treated group. Use of the mouthwash containing the 
benzethonium chloride alone was found to result in about 42% less plaque 
formation after the 10 day period than did use of the placebo, the 
combination, or the ZnCl.sub.2 only mouthwashes. Thus the zinc chloride 
alone was ineffective as a plaque inhibitor, too. In the late forties, the 
combination of zinc chloride with potassium ferro-cyanide was tried for 
the prevention of tooth decay with varying results. (Positive results were 
reported by Gillard et al in The Journal of the Houston District Dental 
Society, Vol. 21, No. 3, pp. 2 and 3, March, 1949. Negative results with 
the same combination were reported by Ast et al in The Journal of the 
American Dental Association 41(4):437-442, October, 1950. No mention was 
made in either article of any effect of zinc chloride or the combination 
on gingivitis.) 
Zinc chloride, in high concentrations, 8 to 40%, has been used as an 
astringent to achieve gingival retraction (Oral Research Abstracts Vol. 4, 
No. 3, p. 262 Abstract No. 1754). Loe and Silness, J. Pros. Dent. 
13:318-328, March-April, 1963, described a procedure in which cotton 
strings were soaked in an 8% zinc chloride solution before application. 
The impregnated strings were forced to the bottom of the gingival pockets, 
by means of a thin steel instrument, and left in place for 10 minutes. 
Histological studies showed that the 8% zinc chloride-impregnated cotton 
strings necrotize the epithelial cuff and the adjacent layer of the 
subepithelial connective tissue. 
Zinc chloride-containing antiseptic preparations have been widely used in 
the past. It is stated in "Accepted Dental Therapeutics" 1971/1972, 34th 
Edition, p. 200 that zinc chloride has antiseptic, astringent and 
escharotic activities. At concentrations of 1:2000 (0.05%) to 1:500, 
(0.2%) a zinc chloride solution has a weak antiseptic action. The authors 
conclude that "daily use of a mouthwash containing zinc chloride for 
so-called oral hygiene cannot be considered rational." 
Schmid et al, in an article entitled "Effect of a Zinc Chloride Mouthrinse 
on Calculous Deposits Formed on Foils", Helvitica Odontologica Acta, Vol. 
18(1):22-24, 1974, reported that a 0.2% zinc chloride-containing 
mouthrinse, when administered twice daily over a one week period, 
significantly inhibited the formation of calculus deposits collected from 
foils attached to lower incisors. 
Gafar et al, Dental and Oral Biology Abstracts, Vol. 54(5)2370, No. 24644, 
reported that, after the mechanical removal of calculus from teeth, 
fluoride should be applied to teeth, and an anti-inflammatory treatment 
with zinc chloride should be applied to the gums. 
In U.S. Pat. No. 4,022,880, issued May 10, 1977 to L. J. Vinson and L. P. 
Cancro, an improved composition for inhibiting dental plaque and calculus 
formation is disclosed, which comprises a combination of zinc ions and a 
non-toxic, organoleptically acceptable antibacterial agent. It is taught 
by the patentees at column 4, lines 1-16, that the use of a zinc compound 
alone, while affording some anticalculus action, would not produce the 
desired effect. They disclose, further, at column 4, lines 20-28, that 
zinc compounds alone or antibacterial agents alone provide only about 
one-half the protection against dental calculus development as do the 
compositions claimed in that patent. 
Hanke, Jour. A.D.A, Vol. 27, No. 9, September, 1940, pp. 1379-1393, in 
Table 1, on pages 1384-5, indicates that various concentrations of zinc 
acetate, lactate and salicylate in 15% glycerol do not have bactericidal 
effectiveness. However, at page 1388, the author indicates that the use of 
a zinc acetate solution as a mouth rinse will cause plaque to disappear 
from even unbrushed teeth, although it is not effective in all cases and 
the solution appears to lose effectiveness on aging. 
DISCLOSURE OF INVENTION 
It has now been discovered that the rate of development of gingivitis, as 
characterized by inflammation, bleeding and swelling, can be substantially 
prevented or retarded by the daily application to the gingivae of zinc 
chloride, in a concentration of about 3% by weight in glycerol. 
Other zinc salts that could be used to replace all or part of the zinc 
chloride are the citrate, acetate, lactate, salicylate, and, in general, 
glycerol soluble, pharmaceutically acceptable zinc salts. 
While it is presently preferred to have glycerol as the sole vehicle, it 
may be diluted with water or another orally acceptable vehicle compatible 
therewith, such as ethanol, propylene glycol or sorbitol, so long as the 
glycerol concentration is at least about 25% by weight, preferably in 
excess of 50% by weight. 
The zinc salt concentration (based on the entire composition) will 
generally vary between about 0.5 and about 8%, preferably between about 1 
and about 5% by weight. While higher concentrations could be used, no 
particular advantage would be afforded thereby, and there are some 
contraindications in the literature, as noted above. 
The compositions of the invention may be in the form of a mouthwash, 
toothpaste, gel, solution or other form suitable for oral application. Any 
pharmaceutically acceptable materials such as those ordinarily used in 
such oral compositions that are compatible with the zinc chloride or other 
salt as well as with the glycerol vehicle may be employed in the 
compositions of this invention. 
In accordance with the present invention, the compositions are applied to 
the gingiva manually, preferably with gentle rubbing of the gingiva. In 
accordance with a preferred method of treatment, the user first brushes 
his teeth with a conventional dentrifice and then applies the composition 
of the present invention to the gums by gently rubbing with the forefinger 
on both the buccal and lingual sides, preferably at least once daily, more 
preferably twice daily.