The document summarizes the history and chemistry of dental bleaching methods. It discusses various bleaching agents used over time including oxalic acid, hydrogen peroxide, ultraviolet light, and sodium perborate. Hydrogen peroxide works by producing reactive oxygen radicals that break down stain molecules. Sodium perborate releases hydrogen peroxide when mixed with water. Studies show sodium perborate with fresh hydrogen peroxide is the most effective bleaching agent. Hydrogen peroxide can affect the structure and bonding of teeth, so restorations should be delayed after bleaching.
4. Hydrogen Peroxide - HHydrogen Peroxide - H22OO22
An oxidising agent:An oxidising agent:
Produces perhydroxyl and oxygen “free radicals”Produces perhydroxyl and oxygen “free radicals”
Highly unstable and very reactiveHighly unstable and very reactive
Goldstein & Garber 1995
5. Hydrogen Peroxide - HHydrogen Peroxide - H22OO22
An oxidising agent:An oxidising agent:
Produces perhydroxyl and oxygen “free radicals”Produces perhydroxyl and oxygen “free radicals”
Highly unstable and very reactiveHighly unstable and very reactive
Weakly acidic in pureWeakly acidic in pure
aqueous form:aqueous form:
Produces more freeProduces more free
oxygen radicalsoxygen radicals
Weaker bleachingWeaker bleaching
agent than theagent than the
perhydroxyl radicalperhydroxyl radical Goldstein & Garber 1995
6. BUT at alkaline pH:BUT at alkaline pH:
Greater bleachingGreater bleaching
effect as moreeffect as more
perhydroxyl freeperhydroxyl free
radical is releasedradical is released
Hydrogen Peroxide - HHydrogen Peroxide - H22OO22
pH: 9.5 – 10.8
Goldstein & Garber 1995
7. Sodium PerborateSodium Perborate -- 2NaBo2NaBo22[OH][OH]22[nH[nH22O]O]
When contact with water:When contact with water:
Breaks down to produce HBreaks down to produce H22OO22 - Approx. 10%- Approx. 10%
Attin et al IEJ 2003
8. Sodium PerborateSodium Perborate -- 2NaBo2NaBo22[OH][OH]22[nH[nH22O]O]
When contact with water:When contact with water:
Breaks down to produce HBreaks down to produce H22OO22 - Approx. 10%- Approx. 10%
Has alkaline pH of 10.0Has alkaline pH of 10.0
∴
Increases the effectiveness of bleaching ifIncreases the effectiveness of bleaching if
used with Hused with H22OO22
9. Bleaching - an oxidation-reduction reactionBleaching - an oxidation-reduction reaction
Agent must diffuse through the dentineAgent must diffuse through the dentine
Internal Bleaching - ChemistryInternal Bleaching - Chemistry
10. Bleaching - an oxidation-reduction reactionBleaching - an oxidation-reduction reaction
Agent must diffuse through the dentineAgent must diffuse through the dentine
Free radicals attack organic moleculesFree radicals attack organic molecules
Break unsaturated bonds to createBreak unsaturated bonds to create
simpler moleculessimpler molecules
Internal Bleaching - ChemistryInternal Bleaching - Chemistry
11. Bleaching - an oxidation-reduction reactionBleaching - an oxidation-reduction reaction
Agent must diffuse through the dentineAgent must diffuse through the dentine
Free radicals attack organic moleculesFree radicals attack organic molecules
Break unsaturated bonds to createBreak unsaturated bonds to create
simpler moleculessimpler molecules
Less absorption energyLess absorption energy
∴ Less light reflectedLess light reflected
Produces a whitening effectProduces a whitening effect
Internal Bleaching - ChemistryInternal Bleaching - Chemistry
12. Has a “saturation point”
Lightening effect slows
dramatically
Breaks down proteins &
carbon-containing
molecules
Increases brittleness
and porosity
If continued - converts
dentine & enamel to CO2
and H2O
ESSENTIAL to Know
When to Stop !!!
Internal Bleaching - ChemistryInternal Bleaching - Chemistry
Goldstein & Garber 1995
13. AnAn in vitroin vitro comparison ofcomparison of
different bleaching agents indifferent bleaching agents in
the discoloured tooththe discoloured tooth
Ho S, Goerig AC.Ho S, Goerig AC.
J EndodJ Endod 1989; 15: 1061989; 15: 106
14. Ho & Goerig - 1989Ho & Goerig - 1989
New Na PerborateNew Na Perborate ++ Fresh SuperoxolFresh Superoxol
New Na PerborateNew Na Perborate ++ 1-year old Superoxol1-year old Superoxol
New Na PerborateNew Na Perborate ++ WaterWater
Old Na PerborateOld Na Perborate ++ WaterWater
15. New Na PerborateNew Na Perborate ++ Fresh SuperoxolFresh Superoxol
93% effective93% effective
New Na PerborateNew Na Perborate ++ 1-year old Superoxol1-year old Superoxol
73% effective73% effective
New Na PerborateNew Na Perborate ++ WaterWater
53% effective53% effective
Old Na PerborateOld Na Perborate ++ WaterWater
53% effective53% effective
Ho & Goerig - 1989Ho & Goerig - 1989
16. New Na PerborateNew Na Perborate ++ Fresh SuperoxolFresh Superoxol
93% effective93% effective
New Na PerborateNew Na Perborate + 1-year old Superoxol+ 1-year old Superoxol
73% effective73% effective
New Na PerborateNew Na Perborate + Water+ Water
53% effective53% effective
Old Na Perborate + WaterOld Na Perborate + Water
53% effective53% effective
Ho & Goerig - 1989Ho & Goerig - 1989
17. New Na PerborateNew Na Perborate ++ Fresh SuperoxolFresh Superoxol
93% effective93% effective
Ho & Goerig - 1989Ho & Goerig - 1989
Recommendations:Recommendations:
Na PerborateNa Perborate - avoid moisture contamination- avoid moisture contamination
HH22OO22 - Use a fresh solution- Use a fresh solution
- Replace supply every 6 months: track dates- Replace supply every 6 months: track dates
- Buy a small jar only: 25 mls- Buy a small jar only: 25 mls
- Store in brown glass jar with tight lid/seal- Store in brown glass jar with tight lid/seal
- Store in the fridge: cool and dark- Store in the fridge: cool and dark
19. HH22OO22 - Effects on Tooth Structure- Effects on Tooth Structure
TitleyTitley et alet al -- J EndodJ Endod 1988; 14: 69-741988; 14: 69-74
HH22OO22 produces a precipitate on theproduces a precipitate on the enamelenamel surfacesurface
Acid etch first + then HAcid etch first + then H22OO22
More precipitate and a more porous enamelMore precipitate and a more porous enamel
surfacesurface
20. HH22OO22 - Effects on Tooth Structure- Effects on Tooth Structure
TitleyTitley et alet al -- J EndodJ Endod 1988; 14: 69-741988; 14: 69-74
HH22OO22 produces a precipitate on theproduces a precipitate on the enamelenamel surfacesurface
Acid etch first + then HAcid etch first + then H22OO22
More precipitate and a more porous enamelMore precipitate and a more porous enamel
surfacesurface
TitleyTitley et alet al -- EDTEDT 1988; 4: 32-61988; 4: 32-6
HH22OO22 leaves an amorphous precipitate onleaves an amorphous precipitate on dentinedentine
Acid etch first + then HAcid etch first + then H22OO22
Less precipitate and more tubules openLess precipitate and more tubules open
21. AdibfarAdibfar et alet al -- J EndodJ Endod 1992; 18; 488-911992; 18; 488-91
Peroxide isPeroxide is absorbedabsorbed by both enamel andby both enamel and
dentine during bleachingdentine during bleaching
Leaches out if left in water for a long timeLeaches out if left in water for a long time
Can not remove just by rinsingCan not remove just by rinsing
HH22OO22 - Effects on Tooth Structure- Effects on Tooth Structure
22. HH22OO22 - Effects on Bonding Materials- Effects on Bonding Materials
TitleyTitley et alet al -- EDTEDT 1989; 5: 132-81989; 5: 132-8
Highly significant reduction in bond strengthHighly significant reduction in bond strength
ofof GICGIC toto dentinedentine after treatment with Hafter treatment with H22OO22
23. HH22OO22 - Effects on Bonding Materials- Effects on Bonding Materials
TitleyTitley et alet al -- EDTEDT 1989; 5: 132-81989; 5: 132-8
Highly significant reduction in bond strengthHighly significant reduction in bond strength
ofof GICGIC toto dentinedentine after treatment with Hafter treatment with H22OO22
TitleyTitley et alet al -- J Dent ResJ Dent Res 1988; 67: 1523-81988; 67: 1523-8
Highly significant reduction in bond strengthHighly significant reduction in bond strength
ofof compositecomposite toto enamelenamel treated with Htreated with H22OO22
24. TorneckTorneck et alet al -- EDTEDT 1990; 6: 97-1031990; 6: 97-103
No measurable adhesion ofNo measurable adhesion of compositecomposite toto
dentinedentine treated with Htreated with H22OO22
A highly significant difference in bondA highly significant difference in bond
strength of composite resin to untreatedstrength of composite resin to untreated
dentinedentine
HH22OO22 - Effects on Bonding Materials- Effects on Bonding Materials
25. TorneckTorneck et alet al -- EDTEDT 1990; 6: 97-1031990; 6: 97-103
No measurable adhesion ofNo measurable adhesion of compositecomposite toto
dentinedentine treated with Htreated with H22OO22
A highly significant difference in bondA highly significant difference in bond
strength of composite resin to untreatedstrength of composite resin to untreated
dentinedentine
Bond failure was cohesiveBond failure was cohesive ANDAND adhesiveadhesive
Suggests HSuggests H22OO22 affects setting of bondingaffects setting of bonding
resin AND its adhesion to filled resinresin AND its adhesion to filled resin
HH22OO22 - Effects on Bonding Materials- Effects on Bonding Materials
26. TorneckTorneck et alet al -- J EndodJ Endod 1991; 17: 156-601991; 17: 156-60
Water immersion for 7 daysWater immersion for 7 days
Eliminated the reduction in bond strengthEliminated the reduction in bond strength
for composite to peroxide treated enamelfor composite to peroxide treated enamel
HH22OO22 - Effects on Bonding Materials- Effects on Bonding Materials
27. TorneckTorneck et alet al -- J EndodJ Endod 1991; 17: 156-601991; 17: 156-60
Water immersion for 7 daysWater immersion for 7 days
Eliminated the reduction in bond strengthEliminated the reduction in bond strength
for composite to peroxide treated enamelfor composite to peroxide treated enamel
Significantly higher bond strength forSignificantly higher bond strength for
peroxide-treated enamel compared toperoxide-treated enamel compared to
saline-treated enamelsaline-treated enamel
Possibly due to improved surfacePossibly due to improved surface
conditioning or cleansing action byconditioning or cleansing action by
the peroxidethe peroxide
HH22OO22 - Effects on Bonding Materials- Effects on Bonding Materials
28. TorneckTorneck et alet al -- J EndodJ Endod 1991; 17: 156-601991; 17: 156-60
Water immersion for 7 daysWater immersion for 7 days
Eliminated the reduction in bond strengthEliminated the reduction in bond strength
for composite to peroxide treated enamelfor composite to peroxide treated enamel
Significantly higher bond strength forSignificantly higher bond strength for
peroxide-treated enamel compared toperoxide-treated enamel compared to
saline-treated enamelsaline-treated enamel
Possibly due to improved surfacePossibly due to improved surface
conditioning or cleansing action byconditioning or cleansing action by
the peroxidethe peroxide
Saliva may have similar effect to water, butSaliva may have similar effect to water, but
possibly slowerpossibly slower
HH22OO22 - Effects on Bonding Materials- Effects on Bonding Materials
29. Clinical RecommendationsClinical Recommendations
After internal bleaching:After internal bleaching:
Delay restoration of the access cavityDelay restoration of the access cavity
and replacement of other restorationsand replacement of other restorations
30. Clinical RecommendationsClinical Recommendations
After internal bleaching:After internal bleaching:
Delay restoration of the access cavityDelay restoration of the access cavity
and replacement of other restorationsand replacement of other restorations
For a minimum of 14 daysFor a minimum of 14 days
Fill the entire access cavity with CavitFill the entire access cavity with Cavit
(with NO cotton pellet) for this time(with NO cotton pellet) for this time
31. Clinical RecommendationsClinical Recommendations
After internal bleaching:After internal bleaching:
Delay restoration of the access cavityDelay restoration of the access cavity
and replacement of other restorationsand replacement of other restorations
For a minimum of 14 daysFor a minimum of 14 days
Fill the entire access cavity with CavitFill the entire access cavity with Cavit
(with NO cotton pellet) for this time(with NO cotton pellet) for this time
After external bleaching:After external bleaching:
Delay all restorations for at least 14 daysDelay all restorations for at least 14 days
32. Disadvantages of BleachingDisadvantages of Bleaching
Caustic solutionsCaustic solutions
Can change the structure of tooth substanceCan change the structure of tooth substance
? Not always permanentNot always permanent
? External cervical invasive resorption (ECIR)External cervical invasive resorption (ECIR)
Reports of an associationReports of an association
But not provenBut not proven
34. External Cervical Invasive ResorptionExternal Cervical Invasive Resorption
Harrington & Natkin 1979Harrington & Natkin 1979
Reported 7 cases with ECIRReported 7 cases with ECIR
LadoLado et alet al 19831983 - 1 case- 1 case
Montgomery 1984Montgomery 1984 - 1 case- 1 case
Cvek & Lindvall 1985Cvek & Lindvall 1985 - 11 cases- 11 cases
FriedmanFriedman et alet al 19881988
4 cases out of 584 cases out of 58
7%7%
35. External Cervical Invasive ResorptionExternal Cervical Invasive Resorption
Total 36 cases reported 1979 – 2003Total 36 cases reported 1979 – 2003
But how many teeth have been bleached ??But how many teeth have been bleached ??
36. External Cervical Invasive ResorptionExternal Cervical Invasive Resorption
Total 36 cases reported 1979 – 2003Total 36 cases reported 1979 – 2003
But how many teeth have been bleached ??But how many teeth have been bleached ??
Probably millions!!Probably millions!!
37. External Cervical Invasive ResorptionExternal Cervical Invasive Resorption
Total 36 cases reported 1979 – 2003Total 36 cases reported 1979 – 2003
But how many teeth have been bleached ??But how many teeth have been bleached ??
Probably millions!!Probably millions!!
Clinical studies: Total 701 teethClinical studies: Total 701 teeth
8 cases of ECIR (1.1%)8 cases of ECIR (1.1%)
Slightly higher than theSlightly higher than the
population estimate ofpopulation estimate of
0.02% - Heithersay 19990.02% - Heithersay 1999
38. Possible Factors / MechanismsPossible Factors / Mechanisms
TraumaTrauma
Base over RCFBase over RCF
Level of RCF removedLevel of RCF removed
Heat used in bleachingHeat used in bleaching
Chemical burn from OChemical burn from O22 and Hand H22OO22
Cause coagulation and inflammationCause coagulation and inflammation
May lead to necrosis of p.d.l.May lead to necrosis of p.d.l.
Cementum defectCementum defect
39. External Cervical Invasive ResorptionExternal Cervical Invasive Resorption
Total 36 cases reportedTotal 36 cases reported
10 teeth10 teeth
No details reported of the bleaching processNo details reported of the bleaching process
The other 26:The other 26:
None had cervical seal / base over RCFNone had cervical seal / base over RCF
40. External Cervical Invasive ResorptionExternal Cervical Invasive Resorption
Total 36 cases reportedTotal 36 cases reported
10 teeth10 teeth
No details reported of the bleaching processNo details reported of the bleaching process
The other 26:The other 26:
None had cervical seal / base over RCFNone had cervical seal / base over RCF
All had HAll had H22OO22
24 also had Na Perborate24 also had Na Perborate
41. External Cervical Invasive ResorptionExternal Cervical Invasive Resorption
Total 36 cases reportedTotal 36 cases reported
10 teeth10 teeth
No details reported of the bleaching processNo details reported of the bleaching process
The other 26:The other 26:
None had cervical seal / base over RCFNone had cervical seal / base over RCF
All had HAll had H22OO22
24 also had Na Perborate24 also had Na Perborate
22 used heat22 used heat
42. External Cervical Invasive ResorptionExternal Cervical Invasive Resorption
Total 36 cases reportedTotal 36 cases reported
10 teeth10 teeth
No details reported of the bleaching processNo details reported of the bleaching process
The other 26:The other 26:
None had cervical seal / base over RCFNone had cervical seal / base over RCF
All had HAll had H22OO22
24 also had Na Perborate24 also had Na Perborate
22 used heat22 used heat
10 had history of trauma10 had history of trauma
Others - no detail givenOthers - no detail given
43. Cervical root resorptionCervical root resorption
following bleaching offollowing bleaching of
endodontically treated teethendodontically treated teeth
Madison S, Walton R.Madison S, Walton R.
J EndodJ Endod 1990; 16: 570-41990; 16: 570-4
44. Madison & Walton - 1990Madison & Walton - 1990
45 teeth in dogs45 teeth in dogs
Bleached twice 1 week apartBleached twice 1 week apart
Reviewed histologically after 1 yearReviewed histologically after 1 year
Factors associated with ECIR:Factors associated with ECIR:
30% H30% H22OO22 plus heatplus heat
Dentine thicknessDentine thickness
45. Madison & Walton - 1990Madison & Walton - 1990
NOT associated with ECIR:NOT associated with ECIR:
Walking bleach techniqueWalking bleach technique
Internal etchingInternal etching
HH22OO22 and Na Perborateand Na Perborate
Na Perborate inhibits macrophages
Macrophages stimulate clastic cells
Jiménez-Rubio & Segura - JoE 1998
46. Possible Factors / MechanismsPossible Factors / Mechanisms
TraumaTrauma
Base over RCFBase over RCF
Level of RCF removedLevel of RCF removed
Heat used in bleachingHeat used in bleaching
Chemical burn from OChemical burn from O22 and Hand H22OO22
Cause coagulation and inflammationCause coagulation and inflammation
May lead to necrosis of p.d.l.May lead to necrosis of p.d.l.
Cementum defectCementum defect
47. 5 - 10% of all teeth
30% of upper incisors
30% of teeth 60 - 65% of teeth
49. HeithersayHeithersay et al - ADJet al - ADJ 19941994
204 teeth reviewed for up to 19 years after204 teeth reviewed for up to 19 years after
internal bleachinginternal bleaching
4 teeth (1.9%) had ECIR4 teeth (1.9%) had ECIR
All had luxation injuriesAll had luxation injuries
Concluded:Concluded:
““There is a very low, although positive, risk ofThere is a very low, although positive, risk of
ECIR after bleaching –ECIR after bleaching – especially if there hasespecially if there has
been a history of trauma to the tooth”been a history of trauma to the tooth”
50. HeithersayHeithersay - Quintessence Int- Quintessence Int 19991999
257 teeth with ECIR257 teeth with ECIR
0.02% of the population0.02% of the population
Assessed for “potential predisposingAssessed for “potential predisposing
factors”factors”
Sole factorsSole factors
Multiple factorsMultiple factors
51. HeithersayHeithersay - Quintessence Int- Quintessence Int 19991999
Potential predisposing factorsPotential predisposing factors
Orthodontics: 24.1%Orthodontics: 24.1%
4.3% with other factors4.3% with other factors
No identifiable factor: 16.4%No identifiable factor: 16.4%
Trauma 15.1%Trauma 15.1%
10.6% with other factors10.6% with other factors
Restoration in tooth: 14.1%Restoration in tooth: 14.1%
52. HeithersayHeithersay - Quintessence Int- Quintessence Int 19991999
Potential predisposing factorsPotential predisposing factors
Orthodontics: 24.1%Orthodontics: 24.1%
4.3% with other factors4.3% with other factors
No identifiable factor: 16.4%No identifiable factor: 16.4%
Trauma 15.1%Trauma 15.1%
10.6% with other factors10.6% with other factors
Restoration in tooth: 14.1%Restoration in tooth: 14.1%
Internal bleaching: 3.9%Internal bleaching: 3.9%
9.7% with other factors9.7% with other factors
53. Concluded:Concluded:
““There is a very low, although positive, riskThere is a very low, although positive, risk
of ECIR after bleaching ….of ECIR after bleaching ….
…… especially in association with otherespecially in association with other
potential predisposing factors such aspotential predisposing factors such as
trauma and orthodontic treatment”trauma and orthodontic treatment”
HeithersayHeithersay - Quintessence Int- Quintessence Int 19991999
54.
55. Cervical canal leakageCervical canal leakage
after internalafter internal
bleaching proceduresbleaching procedures
Smith JJ, Cunningham CJ,Smith JJ, Cunningham CJ,
Montgomery S.Montgomery S.
J EndodJ Endod 1992; 18: 476-811992; 18: 476-81
57. Conclusions - SmithConclusions - Smith et alet al 19921992
2mm Cavit base was sufficient to2mm Cavit base was sufficient to
dentinal penetration of the dyedentinal penetration of the dye
Cavit should be placed slightlyCavit should be placed slightly
coronal to labial CEJcoronal to labial CEJ
Cemental defects – greater dyeCemental defects – greater dye
penetration in areas of defectspenetration in areas of defects
58.
59. AnAn in vitroin vitro comparison ofcomparison of
bleaching agents on the crownsbleaching agents on the crowns
and roots of discoloured teethand roots of discoloured teeth
Warren MA, Wong M, Ingram TA.Warren MA, Wong M, Ingram TA.
J EndodJ Endod 1990; 16: 463-71990; 16: 463-7
60. WarrenWarren et alet al - 1990- 1990
IRM base at CEJ or 2mm below CEJIRM base at CEJ or 2mm below CEJ
No difference in bleaching resultNo difference in bleaching result
61. WarrenWarren et alet al - 1990- 1990
IRM base at CEJ or 2mm below CEJIRM base at CEJ or 2mm below CEJ
No difference in bleaching resultNo difference in bleaching result
BUT - also bleached some of the tooth rootBUT - also bleached some of the tooth root
Effectiveness of IRM “seal” against liquidEffectiveness of IRM “seal” against liquid
penetration is very questionablepenetration is very questionable
62. RECOMMENDED to cover rootRECOMMENDED to cover root
canal filling with 2mm Cavitcanal filling with 2mm Cavit
before bleachingbefore bleaching
63. Why not GIC ???Why not GIC ???
Very difficult to place without getting onVery difficult to place without getting on
labial dentine wall of access cavitylabial dentine wall of access cavity
Very difficult to remove if on labial wallVery difficult to remove if on labial wall
64. Why not GIC ???Why not GIC ???
Very difficult to place without getting onVery difficult to place without getting on
labial dentine wall of access cavitylabial dentine wall of access cavity
Very difficult to remove if on labial wallVery difficult to remove if on labial wall
GIC’s not proven to prevent moistureGIC’s not proven to prevent moisture
penetration through dentinepenetration through dentine
65. RECOMMENDED to cover rootRECOMMENDED to cover root
canal filling with 2mm Cavitcanal filling with 2mm Cavit
before bleachingbefore bleaching
