1) Chitosan microparticles containing sodium fluoride were produced using spray drying for local fluoride delivery in the oral cavity. 2) Increasing the concentration of chitosan and sodium fluoride increased particle size, fluoride loading, and cumulative fluoride release over 360 minutes. 3) The addition of glutaraldehyde as a cross-linker had no significant effect on particle size, fluoride content, or release profiles but decreased the bioadhesive properties of compressed chitosan discs.

1. 5조 송정환

2. 1. Introduction
1) Saliva is supersaturated with calcium and phosphate
- remineralization at normal pH
2) Action of Fluoride in oral cavity
- Reduce the enamel solubility by substitution of hydroxyl
group to form (Ca10(PO4)6F2) or (Ca10(PO4)6(OH)2-xFx)
- Incorporation of fluoride into dental material
i) inhibit the growth of relevant bacteria
-
ii) recharged with F significant cariostatic benefits
-
- High [F ] result in CaF2 like deposit : more acid labile

3. 3) What is Chitosan
- copolyme of glucosamine and N-acetyl glucosamine
Structure of Chitosan
- exhibits moderate to good mucoadhesion
- retained on the oral mucosa for several hours in vivo
- antibacterial activity
4) Use of Chitosan microparticles
- local delivery to oral cavity (ex, tetracycline, chorhexidine. etc)
- by ionotropic gelation, emulsion polymerisatios forms

4. 5) The aim of this work
1) spray drying : method for manufacture and characterise
chitosan microparticles containing NaF at low cost
2) particle size distribution
3) fluoride loading
4) in vitro fluoride release
5) particle morphology
6) in vitro bioadhesion of discs prepared from compressed
chitosan / fluoride microparticles
6) Null hypotheses using in vitro models
1) Conc. of glutaraldehyde and chitosan – no affect on
particle size, fluoride loading and fluoride release
2) Use of glutaraldehyde – no affect on bioadhesive
properties

5. 2. Materials And Methods
1) Microparticle manufacture
a) Chitosan was dissolved in 1.0% acetic acid (40 ml), sealed,
stirred overnight
b) NaF sln. was prepared in DI water (10 ml)
c) b) was added drop wise to a) over period of 60s
d) spray drying the 3 sln. using a bench top mini spray drier

6. 2) Microparticle characterisation
2.1) Particle size distribution – particle sizer
2.2) Enverionmental scanning electron microscypy (ESEM)
2.3) Fluoride analysis – fluoride ion selective electrode
2.4) Determination of total fluoride loading
O
2.5) in vitro fluoride release – at 32 C for 360 min
2.6) texture probe analysis – chitosan disc on porcine oesophagi

7. 3. Result
3.1 Microparticle manufacture
- fixed [chitosan]:[fluoride] = 2:1
- two [chitosan]: 1.0 and 2.0 %
- increasing chitosan conc. to 2.0 % reduced yield
- 2.0 % chitosan only – 19 % yield
- 2.0 % chitosan + 0.4 % NaF – 42 % yield

8. 3.2 Particle size distribution
- Increasing [chitosan] effected predictable increase in VMD
- D[v, 90] shows greater polydispersity in 2.0 % chitosan
- Addition of glutaraldehyde had no significant impact
on size distribution (p>0.05)

9. 3.3 Fluoride loading
- Fluoride content and entrapment efficiency were enhanced
-
when conc. of [chitosan] and [F ] was increased
- Addn. of glutaraldehyde had no significant effect on
fluoride content and entraptment efficiency

10. 3.4 Fluoride release profiles
2
- Sample 2 exhibited the greatest cumulative fluoride release
with 77.4 % total fluoride released after 360 min.

11. - Microparticles without glutaraldehyde swelled relatively
quickly (sample 1 and 4)
- Microparticles with high glutaraldehyde conc. showed
minimal swelling due to the high cross-linking density
(sample 3 and 6)
- For microparticles without or low conc. of glutaraldehyde
(0.0010 %) (sample 1 and 4; 2 and 5, respectively),
summed the cumulative fluoride release at 360 min was
90 %

12. - Eeffect of pH on release of fluoride was not significant
pH 7.0
pH 4.0
pH 5.5

13. 3.5 Microparticle morphology
- Addition of NaF and glutaraldehyde had minimal effect on
the morphology of isolated microparticles

14. 3.6 Bioadhesion to porcine oesophageal mucosa
- Both F max and WOA were dramatically decreased

15. 4. Discussion
1) Employed low cost spray drying technique to
manufacture bioadhesive chitosan/fluoride matrix
microparticles
2) No fluoride incoporated chitosan microparticles
using spray drying method was investigated
3) Chitosan and fluoride conc. were primary
determinant on size distribution
4) Increasing the chitosan conc. resulted in
significant increases in particle size

16. 5) Micro particles could be formulated into an
anhydrous dentifrice from which the release of
fluoride would be initiated by the addn. of water
6) Alternative delivery formats could include
aerosolised chitosan/fluoride microparticles
7) Based on current aerosol systems, 10 mg of
chitosan/fluoride microparticles would introduce
up to 630 ㎍ of fluoride

17. 8) Compressed chitosan/fluoride discs method can
be applied
9) Incoporation of NaF showed unexpected reduction
in bioadhesive ability

18. 9. Conclusion
1) Bioadhesive chitosan/fluoride microparticles using
a low cost spray drying technique was successful
2) Recovered yield were inversely proportional to the
viscosity of the original dispersion
3) Isolated chitosan/fluoride microparticles have
potential utility as vehicles to enhance fluoride
retention and promote controlled fluoride delivery
in the oral cavity