280
Antibacterial
Activity of Some Triclosan-Containing Toothpastes
Their
and
Ingredients*
William G. Wade and Martin Addy
The antibacterial activity of 4 triclosan-containing toothpastes was compared to a conventional fluoride dentifrice and triclosan and sodium lauryl sulphate (SLS), both singly and in combination. A panel of 17 bacteria was tested by an agar dilution method. At concentrations typical of those found in toothpastes, triclosan and SLS displayed approximately equal antibacterial activity. A paste containing triclosan and zinc citrate appeared more active than the other triclosan pastes which, in general, showed marginal superiority over the conventional paste. SLS, although included in dentifrice formulations for its detergent properties, may significantly contribute to the antibacterial profile of a product. The need for appropriate controls when evaluating experimental toothpastes is emphasized. / Periodontol 1992; 63:280-282.
Keywords: Triclosan/therapeutic use; dentifrices; sodium lauryl sulfate/therapeutic use;
fluorides/therapeutic use.
Toothbrushing with toothpaste is arguably the most widely practiced method of oral hygiene in developed countries.1 However, most individual's toothbrushing technique is suboptimal and, therefore, antimicrobials have been incorporated into dentifrices in attempts to augment the plaque control properties of this method of oral hygiene. Recently, a number of products have become available which incorporate the non-ionic antimicrobial triclosan as the active ingredient. These include products where zinc
citrate is also present to enhance the antimicrobial action of triclosan and another which includes a co-polymer to increase the substantivity of triclosan in the mouth. Results from short- and long-term studies for triclosan toothpastes, including some now commercially available, have been encouraging.2 6 However, not all studies have shown the triclosan formulations tested more effective against plaque regrowth than conventional products.7"9 In part these differences in findings may reflect the nature and level of detergent in the control products. Sodium lauryl sulphate (SLS) is perhaps the most common detergent included in toothpaste formulations. In its own right SLS is a potent antimicrobial and toothpastes containing SLS exhibit antibacterial effects in vitro and in vivo.1012 In fact it is probable that SLS largely accounts for the plaque inhibitory action noted for a number of toothpaste products.13 Also worthy of note was the similar plaque inhibitory properties of a 1% SLS and a 0.2% triclosan
'Department of Periodontology, University of Wales College of Medicine, Cardiff,
UK.
mouthrinse.14 Indeed, the SLS and triclosan rinses exhibited similar substantivity as measured by the magnitude and duration of reductions in salivary bacterial counts.15 Most if not all of the triclosan formulations used in clinical trials have SLS as the detergent component. The similarity in action of both SLS and triclosan, therefore, may explain why triclosan toothpastes in some studies did not exhibit greater plaque or bacterial inhibition than the control products.5'7'9 To date there is little information concerning the antimicrobial profiles of the triclosan products. Furthermore, no attempt has been made to determine what antimicrobial action triclosan confers to conventional products. The aim of this study was to determine the antibacterial properties of four triclosan toothpaste products compared with a conventional fluoride paste and solutions of triclosan and SLS both and in combination. MATERIALS AND METHODS The method used was that recommended for the antimicrobial susceptibility testing of anaerobes16 modified for oral hygiene products as previously described.12 The toothpastes tested and their active ingredients are listed in Table 1. Ten g of each toothpaste was mixed with 10 ml sterile distilled water on a rotary mixer for 30 minutes. The resulting slurries were then centrifuged at 4000 rpm for 15 minutes, the supernatant aspirated and diluted to 1:2048 in doubling dilutions in sterile distilled water. A 2% SLS, and a 0.2% triclosan solution were diluted as for the toothpastes. Two ml of each dilution was then mixed with 18 ml molten Wilkins Chalgren agar and poured into 9 cm Petri dishes.
Volume 63 Number 4 Table 1:
Toothpastes
WADE, ADDY Included in the
Active
Toothpaste Colgate Regular* Macleans
Study
in the
duplicate experiments, are shown in Table 2. The majority of organisms were approximately equally suscep-
Ingredients
Sodium monofluorophosphate 0.76%, sodium fluoride 0.1% Sodium monofluorophosphate 0.8%, calcium glycerophosphate 0.13%, triclosan 0.215% Sodium monofluorophosphate 0.85%, triclosan 0.2%, zinc citrate trihydrate 0.5% Sodium fluoride 0.32%, triclosan 0.3%, pyrophosphate 5% Sodium fluoride 0.24%, triclosan 0.3%
Anti-plaque
Formulât
Mentadent Gum Health Formulât Crest Gum Health§
Colgate Gum Protection Formula*
*Colgate-Palmolive Ltd., Guildford, UK. tSmithKline Beecham Personal Care, Brentford, UK. tElida Gibbs, London, UK. §Procter & Gamble Ltd, Egham, UK. A panel of 17 test bacteria was used including early plaque formers and putative periodontopathogens and both reference strains and strains from the departmental collection (W strain number prefix) isolated from a variety of oral infections. The bacteria were suspended in phosphate buffered saline to a turbidity equal to that of the MacFarland 0.5 standard. The plates plus a control plate containing no test agent were inoculât sd by a multipoint inoculator which delivered 3 µ of each bacterial suspension to the plates. This enabled all 17 bacteria to be tested simultaneously. The plates were incubated for 96 hours under anaerobic conditions. The maximum inhibitory dilution (MID) was taken as the highest dilution affording no growth, a single colony, or a fine visible haze. The control plate was checked for viability of the test organisms. All experiments were performed in duplicate. RESULTS The MID values for the 5 toothpastes, SLS, triclosan, and combined SLS and triclosan solutions, which were identical Table 2: Antibacterial
tible to SLS and triclosan at the concentrations tested. Exceptions were the A. actinomycetemcomitans strains which were markedly more susceptible to triclosan and P. intermedia which was more susceptible to SLS. Both compounds appeared active in the combination solution, in that the MID of the combination was either equal to or one dilution higher than the most active individual component. The profile of Colgate Regular closely resembled that of SLS alone. Mentadent Gum Health Formula displayed the highest antimicrobial activity of the triclosan containing pastes. Colgate Gum Protection Formula also displayed greater activity than Colgate Regular, as did Macleans AntiPlaque Formula whose profile closely resembled that of the SLS/triclosan mixture. Crest Gum Health was, in general, less active than all the other pastes, including Colgate Regular, except against A. actinomycetemcomitans. DISCUSSION This study has provided data which permits a descriptive comparison of the antimicrobial properties of triclosan-containing toothpastes. In the first instance, the results confirm the potent antibacterial activity of triclosan and SLS. However, it must be accepted that, because of chemical and physical interactions between the ingredients in formulations, the available concentrations in the solutions may be greater than in the toothpaste products. Although in MIC terms triclosan is approximately 10 times more active than SLS, solubility and acceptability problems mean that it cannot be incorporated into toothpastes above 0.3%. SLS, on the other hand, is incorporated into toothpastes at a variable concentration range but usually between the extremes of 1.3% to 2.6%. Therefore, at the concentrations at which they can be incorporated into oral hygiene products triclosan and SLS exhibit approximately
Properties of Triclosan-Containing Toothpastes Against Oral
Bacteria
Maximum Macleans
Species A. actinomycetemcomitans A. actinomycetemcomitans A. odontolyticus A. viscosus C. rectus C. ochracea
Capnocytophaga species
E. timidum S. oralis P. anaerobias P. micros P. gingivalis P. intermedia P. intermedia S. constellatus V. párvula Veillonella species
Strain No. Y4 W 1425 NCTC 9935 NCTC 10951 W 1316 NCTC 11654 W287 W933 NCTC 7864 NCTC 11460 W 1414 W 1360 NCTC 9336 W 1436 W362 NCTC 11463 W 1459
281
Colgate Regular 160 160 1280 640 2560 1280 1280 2560 1280 1280 10240 10240 1280 5120 1280 160 40
Anti-plaque Formula 10240 5120 1280 1280 2560 2560 1280 1280 1280 640 10240 10240 1280 2560 640 640 160
Inhibitory Dilution Colgate
Mentadent Gum Health Formula
Crest Gum Health
Gum Protection Formula
10240 5120 2560 2560 5120 5120 2560 5120 2560 5120 >20480 >20480 5120 >20480 2560 320 320
5120 5120 640 320 2560 1280 1280 1280 640 1280 5120 5120 640 5120 1280 160 80
10240 5120 2560 1280 5120 5120 2560 2560 2560 2560 10240 10240 2560 10240 1280 320 160
2% SLS 160 160
320 640 2560 1280 1280 1280 640 640 10240 5120 1280 2560 640 320 320
0.2% Triclosan
2% SLS + 0.2% Triclosan
10240 5120 640 640 1280 2560 1280 640 640 640 10240 2560 640 640 640 320 640
10240 5120 1280 1280 2560 2560 1280 1280 1280 1280 10240 10240 1280 2560 1280 320 320
J Periodontol
282
ANTIBACTERIAL ACTIVITY IN TRICLOSAN-CONTAINING DENTIFRICES
equal antibacterial activity. In addition, they have been shown to exhibit similar substantivity and plaque inhibitory properties.15 The antibacterial properties of the combination of SLS and triclosan were only marginally superior to the compounds singly, but did provide coverage when one component was less effective against a particular organism. In view of this lack of synergism, it is perhaps unsurprising that some studies on plaque regrowth failed to demonstrate greater activity of triclosan-containing toothpastes over conventional SLS-containing toothpastes.5'7'9 Additionally, the antimicrobial actions of triclosan toothpastes in vivo were little different to a conventional fluoride toothpaste.16 Convincing differences in favor of triclosan pastes against plaque regrowth and salivary bacteria tend only to be seen when comparisons are made
with control pastes with low or no SLS content.4'5-17 Mentadent was clearly more effective than the other pastes. This presumably derives from the added benefits of the inclusion of zinc citrate in this formulation. Interestingly, to date, evidence for clinical efficacy in long-term is available,6 with, as yet, little longuse of Mentadent term usage data for the other products. The antimicrobial properties of Crest Gum Health were surprisingly poor and may reflect additional substances present in the formulation which have partially neutralized its activity. In conclusion, it is accepted that in vitro data of antimicrobial properties of toothpastes cannot necessarily be extrapolated to effects in vivo. Nevertheless, this descriptive comparison of the antimicrobial properties of toothpastes has revealed considerable differences in the action of products which contain essentially the same antimicrobial agents, namely SLS and triclosan. It would of course be of considerable interest to the profession were a longterm clinical study to be conceived to compare all the triclosan products together with a conventional fluoride paste for effects on plaque and gingivitis.
Acknowledgments Mrs. P. Bishop and Mrs. L. excellent technical assistance.
Brownsey
are
thanked for
REFERENCES 1. Frandsen A. Mechanical oral hygiene practices. In: Löe H, Kleinman DV, eds. Dental Plaque Control Measures and Oral Hygiene Practices. Washington DC: IRL Press; 1986:93-116.
April
1992
2. Saxton CA. The effects of
a dentifrice containing zinc citrate and 2,4,4-trichloro-2'-hydroxyphenyl ether. / Periodontol 1986; 57:555-
561. 3. Svatun B, Saxton CA, van der Ouderaa F, Rolla G. The influence of a dentifrice containing a zinc salt and a non-ionic antimicrobial agent on the maintenance of gingival health. / Clin Periodontol 1987; 14:457461. 4. Addy M, Jenkins S, Newcombe R. Studies on the effects of toothpaste rinses on plaque regrowth. 1. Influence of surfactants on Chlorhexidine efficacy. / Clin Periodontol 1989; 16:380-384. 5. Jenkins S, Addy M, Newcombe R. Toothpastes containing 0.3% & 0.5% triclosan. 1. Effects on 4 day plaque regrowth. Am J Dent 1989; 2:211-214. 6. Stephen KW, Saxton CA, Jones CL, Ritchie JA, Morrison T. Control of gingivitis and calculus by a dentifrice containing a zinc salt and triclosan. / Periodontol 1990; 61:674-679. 7. Moran J, Addy M, Newcombe R. A comparison of toothpastes containing enzymes or antimicrobial compounds with a conventional fluoride toothpaste on the development of plaque and gingivitis. / Clin Periodontol 1989; 16:295-299. 8. Jenkins S, Addy M, Newcombe R. Studies on the effect of toothpaste rinses on plaque regrowth. (II). Triclosan with and without zinc citrate formulations. / Clin Periodontol 1989; 16:385-387. 9. Addy M, Jenkins S, Newcombe R. The effect of triclosan, stannous fluoride and Chlorhexidine products on: 1. Plaque regrowth over a 4day period. / Clin Periodontol 1990; 17:693-697. 10. Moran J, Addy M. The antibacterial properties of some commercially available toothpastes in vitro. Br Dent J 1984; 156:175-178. 11. Moran J, Addy M, Newcombe R. The antibacterial effect of toothpastes on the salivary flora. / Clin Periodontol 1988; 15:193-199. 12. Moran J, Addy M, Wade WG. Determination of minimum inhibitory concentrations of commercial toothpastes using an agar dilution method. J Dent 1988; 16:27-31. 13. Addy M, Willis L, Moran JM. Effect of toothpaste rinses compared with Chlorhexidine on plaque formation during a four day period. / Clin Periodontol 1983; 10:89-99. 14. Jenkins S, Addy M, Newcombe R. Triclosan and sodium lauryl sulphate mouthrinses. II. Effects on 4-day plaque regrowth. / Clin Periodontol 1991; 18:145-148. 15. Jenkins S, Addy M, Newcombe R. Triclosan and sodium lauryl sulphate mouthwashes. I. Effects on salivary bacterial counts. / Clin Periodontol 1991; 18:140-144. 16. National Committee for Clinical Laboratory Standards. Reference agar dilution procedure for antimicrobial susceptibility testing of anaerobic bacteria. MII- , Vol. 5. Villanova PA: National Committee for Clinical Laboratory Standards, 1985:25-32. 17. Jenkins S, Addy M, Newcombe R. The effects of 0.5% Chlorhexidine and 0.2% triclosan containing toothpastes on salivary bacterial counts. / Clin Periodontol 1990; 17:85-89. Send reprint requests to: Dr. W.G. Wade, Department of Periodontology, University of Wales College of Medicine, Heath Park, Cardiff, CF4 4XY UK. Accepted for publication November 7, 1991.
Antibacterial
Activity of Some Triclosan-Containing Toothpastes
Their
and
Ingredients*
William G. Wade and Martin Addy
The antibacterial activity of 4 triclosan-containing toothpastes was compared to a conventional fluoride dentifrice and triclosan and sodium lauryl sulphate (SLS), both singly and in combination. A panel of 17 bacteria was tested by an agar dilution method. At concentrations typical of those found in toothpastes, triclosan and SLS displayed approximately equal antibacterial activity. A paste containing triclosan and zinc citrate appeared more active than the other triclosan pastes which, in general, showed marginal superiority over the conventional paste. SLS, although included in dentifrice formulations for its detergent properties, may significantly contribute to the antibacterial profile of a product. The need for appropriate controls when evaluating experimental toothpastes is emphasized. / Periodontol 1992; 63:280-282.
Keywords: Triclosan/therapeutic use; dentifrices; sodium lauryl sulfate/therapeutic use;
fluorides/therapeutic use.
Toothbrushing with toothpaste is arguably the most widely practiced method of oral hygiene in developed countries.1 However, most individual's toothbrushing technique is suboptimal and, therefore, antimicrobials have been incorporated into dentifrices in attempts to augment the plaque control properties of this method of oral hygiene. Recently, a number of products have become available which incorporate the non-ionic antimicrobial triclosan as the active ingredient. These include products where zinc
citrate is also present to enhance the antimicrobial action of triclosan and another which includes a co-polymer to increase the substantivity of triclosan in the mouth. Results from short- and long-term studies for triclosan toothpastes, including some now commercially available, have been encouraging.2 6 However, not all studies have shown the triclosan formulations tested more effective against plaque regrowth than conventional products.7"9 In part these differences in findings may reflect the nature and level of detergent in the control products. Sodium lauryl sulphate (SLS) is perhaps the most common detergent included in toothpaste formulations. In its own right SLS is a potent antimicrobial and toothpastes containing SLS exhibit antibacterial effects in vitro and in vivo.1012 In fact it is probable that SLS largely accounts for the plaque inhibitory action noted for a number of toothpaste products.13 Also worthy of note was the similar plaque inhibitory properties of a 1% SLS and a 0.2% triclosan
'Department of Periodontology, University of Wales College of Medicine, Cardiff,
UK.
mouthrinse.14 Indeed, the SLS and triclosan rinses exhibited similar substantivity as measured by the magnitude and duration of reductions in salivary bacterial counts.15 Most if not all of the triclosan formulations used in clinical trials have SLS as the detergent component. The similarity in action of both SLS and triclosan, therefore, may explain why triclosan toothpastes in some studies did not exhibit greater plaque or bacterial inhibition than the control products.5'7'9 To date there is little information concerning the antimicrobial profiles of the triclosan products. Furthermore, no attempt has been made to determine what antimicrobial action triclosan confers to conventional products. The aim of this study was to determine the antibacterial properties of four triclosan toothpaste products compared with a conventional fluoride paste and solutions of triclosan and SLS both and in combination. MATERIALS AND METHODS The method used was that recommended for the antimicrobial susceptibility testing of anaerobes16 modified for oral hygiene products as previously described.12 The toothpastes tested and their active ingredients are listed in Table 1. Ten g of each toothpaste was mixed with 10 ml sterile distilled water on a rotary mixer for 30 minutes. The resulting slurries were then centrifuged at 4000 rpm for 15 minutes, the supernatant aspirated and diluted to 1:2048 in doubling dilutions in sterile distilled water. A 2% SLS, and a 0.2% triclosan solution were diluted as for the toothpastes. Two ml of each dilution was then mixed with 18 ml molten Wilkins Chalgren agar and poured into 9 cm Petri dishes.
Volume 63 Number 4 Table 1:
Toothpastes
WADE, ADDY Included in the
Active
Toothpaste Colgate Regular* Macleans
Study
in the
duplicate experiments, are shown in Table 2. The majority of organisms were approximately equally suscep-
Ingredients
Sodium monofluorophosphate 0.76%, sodium fluoride 0.1% Sodium monofluorophosphate 0.8%, calcium glycerophosphate 0.13%, triclosan 0.215% Sodium monofluorophosphate 0.85%, triclosan 0.2%, zinc citrate trihydrate 0.5% Sodium fluoride 0.32%, triclosan 0.3%, pyrophosphate 5% Sodium fluoride 0.24%, triclosan 0.3%
Anti-plaque
Formulât
Mentadent Gum Health Formulât Crest Gum Health§
Colgate Gum Protection Formula*
*Colgate-Palmolive Ltd., Guildford, UK. tSmithKline Beecham Personal Care, Brentford, UK. tElida Gibbs, London, UK. §Procter & Gamble Ltd, Egham, UK. A panel of 17 test bacteria was used including early plaque formers and putative periodontopathogens and both reference strains and strains from the departmental collection (W strain number prefix) isolated from a variety of oral infections. The bacteria were suspended in phosphate buffered saline to a turbidity equal to that of the MacFarland 0.5 standard. The plates plus a control plate containing no test agent were inoculât sd by a multipoint inoculator which delivered 3 µ of each bacterial suspension to the plates. This enabled all 17 bacteria to be tested simultaneously. The plates were incubated for 96 hours under anaerobic conditions. The maximum inhibitory dilution (MID) was taken as the highest dilution affording no growth, a single colony, or a fine visible haze. The control plate was checked for viability of the test organisms. All experiments were performed in duplicate. RESULTS The MID values for the 5 toothpastes, SLS, triclosan, and combined SLS and triclosan solutions, which were identical Table 2: Antibacterial
tible to SLS and triclosan at the concentrations tested. Exceptions were the A. actinomycetemcomitans strains which were markedly more susceptible to triclosan and P. intermedia which was more susceptible to SLS. Both compounds appeared active in the combination solution, in that the MID of the combination was either equal to or one dilution higher than the most active individual component. The profile of Colgate Regular closely resembled that of SLS alone. Mentadent Gum Health Formula displayed the highest antimicrobial activity of the triclosan containing pastes. Colgate Gum Protection Formula also displayed greater activity than Colgate Regular, as did Macleans AntiPlaque Formula whose profile closely resembled that of the SLS/triclosan mixture. Crest Gum Health was, in general, less active than all the other pastes, including Colgate Regular, except against A. actinomycetemcomitans. DISCUSSION This study has provided data which permits a descriptive comparison of the antimicrobial properties of triclosan-containing toothpastes. In the first instance, the results confirm the potent antibacterial activity of triclosan and SLS. However, it must be accepted that, because of chemical and physical interactions between the ingredients in formulations, the available concentrations in the solutions may be greater than in the toothpaste products. Although in MIC terms triclosan is approximately 10 times more active than SLS, solubility and acceptability problems mean that it cannot be incorporated into toothpastes above 0.3%. SLS, on the other hand, is incorporated into toothpastes at a variable concentration range but usually between the extremes of 1.3% to 2.6%. Therefore, at the concentrations at which they can be incorporated into oral hygiene products triclosan and SLS exhibit approximately
Properties of Triclosan-Containing Toothpastes Against Oral
Bacteria
Maximum Macleans
Species A. actinomycetemcomitans A. actinomycetemcomitans A. odontolyticus A. viscosus C. rectus C. ochracea
Capnocytophaga species
E. timidum S. oralis P. anaerobias P. micros P. gingivalis P. intermedia P. intermedia S. constellatus V. párvula Veillonella species
Strain No. Y4 W 1425 NCTC 9935 NCTC 10951 W 1316 NCTC 11654 W287 W933 NCTC 7864 NCTC 11460 W 1414 W 1360 NCTC 9336 W 1436 W362 NCTC 11463 W 1459
281
Colgate Regular 160 160 1280 640 2560 1280 1280 2560 1280 1280 10240 10240 1280 5120 1280 160 40
Anti-plaque Formula 10240 5120 1280 1280 2560 2560 1280 1280 1280 640 10240 10240 1280 2560 640 640 160
Inhibitory Dilution Colgate
Mentadent Gum Health Formula
Crest Gum Health
Gum Protection Formula
10240 5120 2560 2560 5120 5120 2560 5120 2560 5120 >20480 >20480 5120 >20480 2560 320 320
5120 5120 640 320 2560 1280 1280 1280 640 1280 5120 5120 640 5120 1280 160 80
10240 5120 2560 1280 5120 5120 2560 2560 2560 2560 10240 10240 2560 10240 1280 320 160
2% SLS 160 160
320 640 2560 1280 1280 1280 640 640 10240 5120 1280 2560 640 320 320
0.2% Triclosan
2% SLS + 0.2% Triclosan
10240 5120 640 640 1280 2560 1280 640 640 640 10240 2560 640 640 640 320 640
10240 5120 1280 1280 2560 2560 1280 1280 1280 1280 10240 10240 1280 2560 1280 320 320
J Periodontol
282
ANTIBACTERIAL ACTIVITY IN TRICLOSAN-CONTAINING DENTIFRICES
equal antibacterial activity. In addition, they have been shown to exhibit similar substantivity and plaque inhibitory properties.15 The antibacterial properties of the combination of SLS and triclosan were only marginally superior to the compounds singly, but did provide coverage when one component was less effective against a particular organism. In view of this lack of synergism, it is perhaps unsurprising that some studies on plaque regrowth failed to demonstrate greater activity of triclosan-containing toothpastes over conventional SLS-containing toothpastes.5'7'9 Additionally, the antimicrobial actions of triclosan toothpastes in vivo were little different to a conventional fluoride toothpaste.16 Convincing differences in favor of triclosan pastes against plaque regrowth and salivary bacteria tend only to be seen when comparisons are made
with control pastes with low or no SLS content.4'5-17 Mentadent was clearly more effective than the other pastes. This presumably derives from the added benefits of the inclusion of zinc citrate in this formulation. Interestingly, to date, evidence for clinical efficacy in long-term is available,6 with, as yet, little longuse of Mentadent term usage data for the other products. The antimicrobial properties of Crest Gum Health were surprisingly poor and may reflect additional substances present in the formulation which have partially neutralized its activity. In conclusion, it is accepted that in vitro data of antimicrobial properties of toothpastes cannot necessarily be extrapolated to effects in vivo. Nevertheless, this descriptive comparison of the antimicrobial properties of toothpastes has revealed considerable differences in the action of products which contain essentially the same antimicrobial agents, namely SLS and triclosan. It would of course be of considerable interest to the profession were a longterm clinical study to be conceived to compare all the triclosan products together with a conventional fluoride paste for effects on plaque and gingivitis.
Acknowledgments Mrs. P. Bishop and Mrs. L. excellent technical assistance.
Brownsey
are
thanked for
REFERENCES 1. Frandsen A. Mechanical oral hygiene practices. In: Löe H, Kleinman DV, eds. Dental Plaque Control Measures and Oral Hygiene Practices. Washington DC: IRL Press; 1986:93-116.
April
1992
2. Saxton CA. The effects of
a dentifrice containing zinc citrate and 2,4,4-trichloro-2'-hydroxyphenyl ether. / Periodontol 1986; 57:555-
561. 3. Svatun B, Saxton CA, van der Ouderaa F, Rolla G. The influence of a dentifrice containing a zinc salt and a non-ionic antimicrobial agent on the maintenance of gingival health. / Clin Periodontol 1987; 14:457461. 4. Addy M, Jenkins S, Newcombe R. Studies on the effects of toothpaste rinses on plaque regrowth. 1. Influence of surfactants on Chlorhexidine efficacy. / Clin Periodontol 1989; 16:380-384. 5. Jenkins S, Addy M, Newcombe R. Toothpastes containing 0.3% & 0.5% triclosan. 1. Effects on 4 day plaque regrowth. Am J Dent 1989; 2:211-214. 6. Stephen KW, Saxton CA, Jones CL, Ritchie JA, Morrison T. Control of gingivitis and calculus by a dentifrice containing a zinc salt and triclosan. / Periodontol 1990; 61:674-679. 7. Moran J, Addy M, Newcombe R. A comparison of toothpastes containing enzymes or antimicrobial compounds with a conventional fluoride toothpaste on the development of plaque and gingivitis. / Clin Periodontol 1989; 16:295-299. 8. Jenkins S, Addy M, Newcombe R. Studies on the effect of toothpaste rinses on plaque regrowth. (II). Triclosan with and without zinc citrate formulations. / Clin Periodontol 1989; 16:385-387. 9. Addy M, Jenkins S, Newcombe R. The effect of triclosan, stannous fluoride and Chlorhexidine products on: 1. Plaque regrowth over a 4day period. / Clin Periodontol 1990; 17:693-697. 10. Moran J, Addy M. The antibacterial properties of some commercially available toothpastes in vitro. Br Dent J 1984; 156:175-178. 11. Moran J, Addy M, Newcombe R. The antibacterial effect of toothpastes on the salivary flora. / Clin Periodontol 1988; 15:193-199. 12. Moran J, Addy M, Wade WG. Determination of minimum inhibitory concentrations of commercial toothpastes using an agar dilution method. J Dent 1988; 16:27-31. 13. Addy M, Willis L, Moran JM. Effect of toothpaste rinses compared with Chlorhexidine on plaque formation during a four day period. / Clin Periodontol 1983; 10:89-99. 14. Jenkins S, Addy M, Newcombe R. Triclosan and sodium lauryl sulphate mouthrinses. II. Effects on 4-day plaque regrowth. / Clin Periodontol 1991; 18:145-148. 15. Jenkins S, Addy M, Newcombe R. Triclosan and sodium lauryl sulphate mouthwashes. I. Effects on salivary bacterial counts. / Clin Periodontol 1991; 18:140-144. 16. National Committee for Clinical Laboratory Standards. Reference agar dilution procedure for antimicrobial susceptibility testing of anaerobic bacteria. MII- , Vol. 5. Villanova PA: National Committee for Clinical Laboratory Standards, 1985:25-32. 17. Jenkins S, Addy M, Newcombe R. The effects of 0.5% Chlorhexidine and 0.2% triclosan containing toothpastes on salivary bacterial counts. / Clin Periodontol 1990; 17:85-89. Send reprint requests to: Dr. W.G. Wade, Department of Periodontology, University of Wales College of Medicine, Heath Park, Cardiff, CF4 4XY UK. Accepted for publication November 7, 1991.
