Dental Gum

a report by

E r i c C R ey n o l d s , AO

Professor of Dental Science and Head, School of Dental Science, The University of Melbourne

Casein phosphopeptide-amorphous calciumphosphate (CPP-ACP) nanocomplexes are derivedfrom bovine milk protein, casein and calcium andphosphate. The concept of CPP-ACP as aremineralizing agent was first postulated in 1998.1 Anumber of subsequent studies have demonstratedCPP-ACP to have anticariogenic activity inlaboratory, animal, and human in situ experiments.2-4

This has led to the incorporation of CPP-ACP intofood products and dental products as a new tool in thefight against caries.

CPP - A CP—A N ew Ad j u n c t i ve A g e n t f o rC a r i e s C o n t ro l

Caries initiation is associated with demineralization ofsubsurface tooth enamel. Calcium and phosphate arelost from the subsurface enamel, resulting in theformation of a subsurface lesion.At this early stage, thecaries lesion is reversible via a remineralization processinvolving the diffusion of calcium and phosphate ionsinto the subsurface lesion to restore lost structure. Sinceseveral studies had demonstrated that milk-basedproducts appeared to have anticariogenic properties inanimal models,5-8 attention was focused on identifyingthe specific milk-based agents that were responsible forthe ‘anticaries effect’.

Reynolds and colleagues, using an in situ animal cariesmodel, showed that exposure of enamel plaque tosolutions of tryptic peptides of casein significantlyreduced enamel subsurface demineralization. Caseinpeptides were incorporated into enamel plaque andwere associated with increases in the plaque’s contentof calcium and phosphate.The investigators concludedthat the tryptic peptides responsible for caseinate’santicariogenic activity were the calcium phosphate-stabilizing CPPs (casein phosphopeptides).1 TheseCPPs contain a specific sequence, which markedlyincreases the apparent solubility of calcium phosphateby stabilizing ACP, forming solutions that aresupersaturated with respect to the calcium phosphates.

In an animal caries study, a 0.5% weight per volume(w/v) solution of CPP-ACP nanocomplexes wasdemonstrated to be comparable with a 500ppmfluoride solution in reducing caries activity.10 CPP-ACP solutions, applied twice daily to the teeth ofspecific-pathogen-free rats orally infected withStreptococcus sobrinus, a bacterium that causes tooth decayin humans, significantly reduced caries activity, with0.1% w/v CPP-ACP producing a 14% reduction, and1.0% w/v CPP-ACP producing a 55% reductionrelative to the distilled water control. Theanticariogenicity of CPP-ACP and fluoride was

Case in Phosphopept ide-Amorphous Ca l c ium Phosphate and theReminera l i za t ion o f Enamel

Eric C Reynolds, AO is Professor ofDental Science and Head of theSchool of Dental Science at TheUniversity of Melbourne. ProfessorReynolds is also Associate Dean ofthe Faculty of Medicine, Dentistryand Health Sciences at TheUniversity of Melbourne and ChiefExecutive Officer of the CooperativeResearch Centre for Oral HealthScience. He has been researchingand teaching for over 20 years onthe etiology and prevention of oraldiseases. He has over 200 scientificpublications and 16 patents.Professor Reynolds is on theeditorial board for the AustralianDental Journal and has also been amember of the editorial board forthe Journal of Dental Research. Hehas received numerous awards anddistinctions, with the mostsignificant being the Clunies RossNational Science and TechnologyAward in 2002 , which honoursthose who make importantcontributions to science for theeconomic, social and environmentalbenefit of Australia, and the VictoriaPrize in 2005, which is awarded toan individual whose scientificdiscovery or technologicalinnovation has significantlyadvanced the State of Victoria’sknowledge base and has potentialto lead to a commercial outcome.In 2005, he was appointed anOfficer of the Order of Australia(AO) for service to communitydental health through research anddevelopment of preventive andrestorative products, to dentaleducation through curriculumdevelopment, and as anadministrator and teacher.

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1. Reynolds EC,“Anticariogenic complexes of amorphous calcium phosphate stabilized by casein phosphopeptides:A review”, SpecCare Dentist (1998);8: pp. 8–16.

2. Reynolds EC, et al., “Advances in enamel remineralization: Anticariogenic casein phosphopeptide - amorphous calciumphosphate”, J Clin Dent (1999);10: pp. 86–88.

3. Reynolds EC, et al.,“Retention in plaque and remineralization of enamel lesions by various forms of calcium in a mouthrinse orsugar-free chewing gum”, J Dent Res (2003);82: pp. 206–211.

4. Shen F, et al., “Remineralization of enamel subsurface lesions by sugar-free chewing gum containing casein phosphopeptide-amorphous calcium phosphate”, J Dent Res (2001);80: pp. 2066–2070.

5. Reynolds EC, Black CL,“Confectionery composition and rat caries”, Caries Res (1987);21: pp. 538–545.6. Navia JM, Lopez H,“Rat caries assay of reference foods and sugar-containing snacks”, J Dent Res (1983); 62: pp. 893–898.7. Bowen WH, et al.,“A method to assess cariogenic potential of food-stuffs”, J Am Dent Assoc (1980); 100: pp. 677–681.8. Harper DS, et al., “Cariostatic evaluation of cheeses with diverse physical and compositional characteristics”, Caries Res

(1986);20: pp. 123–130.9. Reynolds EC, et al.,“Anticariogenicity of calcium phosphate complexes of tryptic casein phosphopeptides in the rat”, J Dent Res

(1995)74: pp. 1272–1279.10. Moller IJ, Poulsen S, “The effect of sorbitol containing chewing gum on the incidence of dental caries, plaque and gingivitis in

Danish schoolchildren”, Community Dent Oral Epidemiol (1973);1: pp. 58–67.

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additive, as animals receiving 0.5% CPP-ACP plus500ppm fluoride had significantly lower caries activitythan those animals receiving either CPP-ACP orfluoride alone.10

A human in situ caries model study evaluated the abilityof a 1.0% CPP-ACP solution as a mouthrinse, twicedaily, to prevent enamel demineralization. The enamelplaque that developed in this model wasbacteriologically similar to normal supragingival plaqueon frequent exposure to sucrose solutions. The twice-daily use of the 1.0% CPP-ACP solution resulted in a144% increase in calcium level and a 160% increase ininorganic phosphate level in the interenamel plaquerecovered from the removable intraoral appliance usedin the study. Moreover, CPP-ACP produced a 51 ±19% reduction in enamel mineral loss caused byfrequent sugar-solution exposure.1

The probable anticariogenic mechanism for CPP-ACP is the localization of calcium and phosphate ionsat the tooth surface, which buffers the free calciumand phosphate ion activities, thereby helping tomaintain a state of supersaturation with respect totooth enamel, depressing demineralization, andenhancing remineralization.1-2

CPP - A CP i n C h ew i n g G um

Clinical trials of sugar-free chewing gum have shownthat the gum is non-cariogenic and, in fact, can have ananticariogenic effect through the stimulation of saliva.11-

13 Therefore, it was proposed that sugar-free gum maybe an excellent delivery vehicle for CPP-APP toremineralize enamel subsurface lesions.

The effect of incorporating CPP-ACP into sugar-freegum on enamel remineralization was evaluated inthree randomized, double-blind, crossover studies in30 patients.4 The subjects in the studies woreremovable palatal acrylic appliances with six human-enamel half-slabs inset containing subsurfacedemineralized lesions. The protocols of the threestudies were identical except for the specific sweetener(sorbitol or xylitol), weight, and type (slab or pellet) ofsugar-free gum, CPP-ACP dose, and number oftreatments.The gums were provided as coded productsand were stored at room temperature. All chewinggum treatments were double-blinded and randomized.

For each study, all subjects crossed over to eachrandomly assigned treatment, with at least one weekbetween treatments.

All subjects used standard fluoride dentifrice for theduration of each study and chewed the gums at theirnatural chewing frequency for 20 minutes, four timesdaily for 14 days.The appliances were worn for the 20minutes of gum chewing and for 20 minutesfollowing. In the no-treatment control, the applianceswere worn for 40 minutes. Subjects were instructednot to eat or drink while wearing the appliance and torinse and clean their appliances using the fluoride-freedenture cleanser plate and toothbrush provided. Theywere informed not to brush the area containing theenamel blocks. No alterations were made to thesubjects’ diet and oral hygiene procedures for theduration of each study. After completion of eachtreatment period, the enamel blocks were removedfrom the appliances for processing. Microradiographicanalyses of the enamel lesions were evaluated usingappropriate computerized imaging software. Thechewing of sugar-free gum produced a four- to seven-fold increase in salivary flow rate over the two-minuteperiod in all subjects. No significant difference wasobserved between the sorbitol-based and xylitol-basedgums in their ability to stimulate saliva or remineralizesubsurface enamel lesions. The addition of CPP-ACPto either the sorbitol- or xylitol-based gums at 10.0,18.8, or 56.4mg produced a significant (p>0.001)increase in enamel remineralization, with a 63%, 102%,and 152% average increase, respectively, relative to thesugar-free gum not containing CPP-ACP. Nosignificant correlation was found between individualunstimulated or stimulated salivary flow rates andpercentage enamel remineralization values obtained forany of the treatments. These results indicated that theaddition of CPP-ACP to sugar-free chewing gumsignificantly enhanced remineralization of enamelsubsurface lesions in a dose-related manner,independent of gum weight or type.

The ability of CPP-ACP to be retained insupragingival plaque and remineralize enamelsubsurface lesions in situ when delivered in amouthrinse or sugar-free gum was studied inrandomized, double-blind trials involving 30 adultsubjects.13 The mouthrinse study was a randomized,double-blind, cross-over design involving four coded

Dental Gum

52 U S D E N T I S T RY 2 0 0 6

11. Kandelman D, Gagnon G,“A 24-month clinical study of the incidence and progression of dental caries in relation to consumptionof chewing gum containing xylitol in school preventive programs”, J Dent Res (1990);69: pp. 1771–1775.

12. Beiswanger BB, et al., “The effect of chewing sugar-free gum after meals on clinical caries incidence”, J Am Dent Assoc(1998);129: pp. 1623–1626.

13. Reynolds EC, et al.,“Retention in plaque and remineralization of enamel lesions by various forms of calcium in a mouthrinse orsugar-free chewing gum”, J Dent Res (2003);82(3): pp. 206–211.

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© 2006 Cadbury Adams USA LLC www.tridentgum.comREFERENCES: 1. Data on file. 2. Shen P, Cai F, Nowicki A, Vincent J, Reynolds EC. Remineralization of enamel subsurface lesions by sugar-free chewing gum containing casein phosphopeptide-amorphous calcium phosphate. J Dent Res. 2001; 80: 2066-2070. 3. Reynolds EC, Cai F, Shen P, Walker GD. Retention in plaque and remineralization of enamel lesions byvarious forms of calcium in a mouthrinse or sugar-free chewing gum. J Dent Res. 2003; 82: 206-211. RECALDENT® is milk derived and, therefore, not recommended for your patients with milkallergies. RECALDENT® is digestible by patients with lactose intolerance. RECALDENT is a registered trademark of Recaldent Pty. Ltd.

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U S D E N T I S T RY 2 0 0 654

Dental Gum

mouthrinses.Two of the mouthrinses contained CPP-ACP (2% w/v and 6% w/v, respectively), the thirdmouthrinse contained an unstabilized slurry of 60mMCaCl2 and 40mM sodium phosphate. The fourthmouthrinse was de-ionized water and acted as thecontrol. In the mouthrinse study, only the CPP-ACP-containing mouthrinses significantly increased plaquecalcium and inorganic phosphate levels, and the CPPwere immunolocalized to the surfaces of bacterialcells, as well as to the intercellular plaque matrix.

In the chewing gum studies, two randomized,double-blind cross over remineralization trials wereconducted with three pellet and three slab sugar-freegums containing different forms of calcium, includingCPP-ACP. According to the results, the gumcontaining the CPP-ACP, although not containingthe most calcium per piece of gum, produced thehighest level of enamel remineralization independentof gum-chewing frequency and duration. The CPPcould be detected in plaque extracts three hours aftersubjects chewed the CPP-ACP-containing gum.These results highlight the importance of CPP indelivering ACP to the tooth surface. Moreover, theresults also demonstrate the importance of the CPP instabilizing ACP and producing a highly water-solublecalcium phosphate phase. The CPP-ACP gums weresuperior to the other sugar-free gums inremineralizing enamel subsurface lesions in situ, eventhough the other gums contained from five to 13times the level of total calcium.

In a recent double-blind, randomized, cross-over study,designed to investigate the acid resistance of enamellesions remineralized in situ by a sugar-free chewinggum containing CPP-ACP, the active treatment groupdemonstrated superior resistance to a subsequent acidchallenge.14 The study compared sugar-free gumcontaining 18.8mg of CPP-ACP and sugar-free gumnot containing CPP-ACP. Subjects wore removablepalatal appliances with insets of human enamelcontaining demineralized subsurface lesions, andchewed the gum for 20 minutes four times daily for 14days. After each treatment, the enamel slabs wereremoved and half of each lesion challenged with acid invitro for eight or 16 hours.The level of remineralizationwas determined using microradiography. The gumcontaining CPP-ACP produced approximately twicethe level of remineralization as the control sugar-freegum. The eight- and 16-hour acid challenge of thelesions remineralized with the control gum resulted in

65.4% and 88.0% reductions, respectively, of depositedmineral, while for the CPP-ACP-remineralized lesionsthe corresponding reductions were 30.5% and 41.8%.The acid challenge after in situ remineralization forboth control and CPP-ACP-treated lesions resulted indemineralization underneath the remineralized zone,indicating that the remineralized mineral was moreresistant to subsequent acid challenge.

CPP-ACP gum has also been shown to slow theprogression and enhance the regression of dental cariesin adolescents. 2,720 subjects were randomly assignedto either a test or control group. All subjects receivedaccepted preventive procedures and optimum systemicfluoride exposure.The test group received a sugar-freegum containing 54.4mg CPP-ACP, while the controlgroup received an identical gum without CPP-ACP.Subjects were instructed to chew their assigned gum for10 minutes, three times per day, with one sessionsupervised on school days, over the two-year studyperiod. Standardized digital bitewing radiographs weretaken at the baseline and at the completion of theclinical trial.Analysis of caries progression or regressionwas undertaken using a transition matrix. There was astatistically significant difference in the distributions ofthe transition scores between the two groups(p<0.001). The CPP-ACP gum slowed progression ofcaries compared with the control gum. Nineteenpercent more of the approximal surfaces experiencedcaries progression in the control gum group comparedto the same surfaces in the CPP-ACP gum group.TheCPP-ACP gum also enhanced regression of cariescompared with the control gum. Fifty-six percent moreof the approximal surfaces experienced caries regressionin the CPP-ACP gum group compared to those in thecontrol gum group.15

S umma r y

The enamel remineralizing properties of CPP-ACP havebeen determined from many years of basic and evidence-based clinical research.The incorporation of CPP-ACPinto chewing gum has been shown to increase enamelremineralization.This represents a significant advance intreatment of early carious lesions and prevention in the21st century. Dental practitioners should recommendCPP-ACP-containing products to their patients,particularly children, as well as adults who are at high riskfor caries. Remineralization of early carious lesions maycontinue to emerge in importance as fluoride did in thepast for caries prevention and reduction. ■

14. Iijima Y, et al., “Acid resistance of enamel subsurface lesions remineralized by a sugar-free chewing gum containing caseinphosphopeptide-amorphous calcium phosphate”, Caries Res (2004);38(6): pp. 551–556.

15. Morgan MV, et al.,“CPP-ACP gum slows progression and enhances regression of dental caries”, 84th IADR General Sessionand Exhibition, (2006) June 28 – July 1:Abstract 2445.

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