Discoloured Teeth - 1 & 2 W/Prof. Paul V. Abbott AO --- **Internal Bleaching of Discoloured Teeth** **Winthrop Prof. Paul V. Abbott AO** BDSc, MDS, FRACDS(Endo), FPFA, FADI, FICD, FACD, FIADT Specialist Endodontist Winthrop Professor of Clinical Dentistry University of Western Australia --- **Aesthetic Considerations in Endodontics - Internal Bleaching** Abbott PV. *Pract Perio & Aesth Dent 1997; 9: 833-42.* --- 2nd Year DMD - 2020 Page 1 # **Internal Bleaching of Discoloured Teeth** **Winthrop Prof. Paul V. Abbott AO** BDSc, MDS, FRACDS(Endo), FPFA, FADI, FICD, FACD, FIADT Specialist Endodontist Winthrop Professor of Clinical Dentistry University of Western Australia > [!abstract] Lecture Summary > ==This lecture covers the principles of internal bleaching for discoloured, root-filled teeth, including the causes of discolouration, treatment alternatives, the chemistry of bleaching, and key procedural recommendations to ensure safety and effectiveness.== *Aesthetic Considerations in Endodontics - Internal Bleaching* *Abbott PV.* *Pract Perio & Aesth Dent 1997; 9: 833-42.* Discoloured Teeth - 1 & 2 W/Prof. Paul V. Abbott AO **Tooth Bleaching - Terminology** **Internal** → **“Non-vital”**  i.e. Root-filled **External** → **“Vital”**  i.e. Normal pulp 2nd Year DMD - 2020 Page 2 Two book covers titled "Bleaching Teeth" (1987) and "Complete Dental Bleaching" (1995) ## **Tooth Bleaching - Terminology** > [!warning] > ==It is crucial to use correct terminology. The terms *vital bleaching* and *non-vital bleaching* are inappropriate.== - **Internal** - → **“Non-vital”** - i.e. Root-filled - **External** - → **“Vital”** - i.e. Normal pulp - ==This can be done on both root-filled teeth and teeth with normal pulps.== **Discoloured Teeth - 1 & 2** W/Prof. Paul V. Abbott AO --- **Tooth Stains** - **Extrinsic** - **Intrinsic** > **Essential to determine the cause of the discolouration prior to treatment** --- **Extrinsic Tooth Discolourations** - Cigarettes, pipes, cigars, chewing tobacco - *yellowish-brown to black* - Marijuana - *dark brown to black rings* - Coffee, tea, foods - *brown to black* - Poor oral hygiene - *various colours* - Fluorosis - *White, yellow, brown, grey, and/or black* --- 2nd Year DMD - 2020 Page 3 ## **Tooth Stains** - **Extrinsic** - **Intrinsic** > **Essential to determine the cause of the discolouration prior to treatment** ### **Extrinsic Tooth Discolourations** - Cigarettes, pipes, cigars, chewing tobacco - *yellowish-brown to black* - ==Staining is often worse in teeth with infractions (cracks) or exposed dentine.== - Marijuana - *dark brown to black rings* - Coffee, tea, foods - *brown to black* - Poor oral hygiene - *various colours* - Fluorosis - *White, yellow, brown, grey, and/or black* **Discoloured Teeth - 1 & 2** W/Prof. Paul V. Abbott AO --- **Intrinsic Tooth Discolourations** - **Genetic conditions** - *Amelogenesis imperfecta* - **brown, black** - **Systemic Conditions** - *Jaundice* - **blue-green or brown** - *Porphyria* - **purplish-brown** - **Medications during tooth development** - *Tetracyclines, fluoride* - **many colours** - **Body by-products** - *Bilirubin* - **blue-green or brown** - *Haemoglobin* - **grey, black** --- **Intrinsic Tooth Discolourations** - **Pulp changes** - *Pulp canal calcification (PCC)* - Increased dentine thickness - **yellow** - *Pulp necrosis (PN)* - With haemorrhage - **grey, black** - Release of haemoglobin and iron - e.g. trauma - No haemorrhage - **grey-brown** - Protein degradation products --- *2nd Year DMD - 2020* *Page 4* ### **Intrinsic Tooth Discolourations** - **Genetic conditions** - *Amelogenesis imperfecta* - **brown, black** - ==Involves improperly formed enamel, typically affecting all teeth.== - **Systemic Conditions** - *Jaundice* - **blue-green or brown** - *Porphyria* - **purplish-brown** - **Medications during tooth development** - *Tetracyclines, fluoride* - **many colours** - ==If taken during tooth development, tetracyclines can cause distinct grey or black bands of discolouration within the tooth structure.== - **Body by-products** - *Bilirubin* - **blue-green or brown** - *Haemoglobin* - **grey, black** - ==A common cause is internal haemorrhaging of the pulp following trauma.== - **Pulp changes** - *Pulp canal calcification (PCC)* - Increased dentine thickness - **yellow** - ==The increased thickness of dentine determines the tooth's shade.== - *Pulp necrosis (PN)* - With haemorrhage - **grey, black** - Release of haemoglobin and iron - e.g. trauma - No haemorrhage - **grey-brown** - Protein degradation products **Discoloured Teeth - 1 & 2** **W/Prof. Paul V. Abbott AO** **2nd Year DMD - 2020** **Page 5** --- **Intrinsic Tooth Discolourations** > **Iatrogenic causes** > - Trauma during pulp removal > - Pulp tissue remnants in pulp chamber --- **Intrinsic Tooth Discolourations** > **Iatrogenic causes** > - Trauma during pulp removal > - Pulp tissue remnants in pulp chamber > - **Restorative materials** > - Amalgam, composite, gold, pins, etc > - **If marginal breakdown** Intrinsic tooth discolouration caused by iatrogenic factors, showing discoloured extracted teeth and clinical images of teeth with staining from endodontic materials such as medicaments, sealers, and temporary fillings. Discoloured Teeth - 1 & 2 W/Prof. Paul V. Abbott AO **Intrinsic Tooth Discolourations** > Iatrogenic causes > - Trauma during pulp removal > - Pulp tissue remnants in pulp chamber > - Restorative materials > - Amalgam, composite, gold, pins, etc > - *If marginal breakdown* > - Endodontic materials > - Medicaments, sealers, temp. fillings, etc. **All usually brown, grey or black** 2nd Year DMD - 2020 Page 7 - **Iatrogenic causes** - Trauma during pulp removal - Pulp tissue remnants in pulp chamber - **Restorative materials** - Amalgam, composite, gold, pins, etc - **If marginal breakdown** - Endodontic materials - Medicaments, sealers, temp. fillings, etc. - ==**Medicaments:** *Ledermix paste*, containing tetracycline, can cause significant discolouration if left in the coronal portion of the tooth.== - ==**Cements:** Root canal cements (e.g., AH26) can turn black when exposed to moisture over time, leading to severe tooth discolouration.== **All usually brown, grey or black** **Discoloured Teeth - 1 & 2** W/Prof. Paul V. Abbott AO 2nd Year DMD - 2020 Page 8 --- **Extrinsic and Intrinsic Discolouration** - **Fluorosis** - White, yellow, brown, grey, and/or black - Often with mottled enamel - **Ageing** - Yellow - Often with added discolouration effects of tooth wear, cracks, restorations, illness, etc - *40 years later* --- **Management of Discoloured Teeth** Four clinical images showing varying degrees of tooth discolouration and wear, including one labeled "40 years later". ### **Extrinsic and Intrinsic Discolouration** - **Fluorosis** - White, yellow, brown, grey, and/or black - Often with mottled enamel - **Ageing** - Yellow - Often with added discolouration effects of tooth wear, cracks, restorations, illness, etc - *40 years later* Discoloured Teeth - 1 & 2 W/Prof. Paul V. Abbott AO **Management of Discoloured Teeth** - Determine the cause of the discolouration - This will indicate the treatment approach **Management of Discoloured Teeth** - Intrinsic stains - Extrinsic stains 2nd Year DMD - 2020 Page 9 ## **Management of Discoloured Teeth** - Determine the cause of the discolouration - This will indicate the treatment approach **Discoloured Teeth - 1 & 2** W/Prof. Paul V. Abbott AO 2nd Year DMD - 2020 Page 10 --- **Management of Discoloured Teeth** - **Intrinsic stains** *Internal Bleaching - after RCF* - **Extrinsic stains** *Change addictive behaviour / habits* *If applicable* *e.g. Smoking, chewing tobacco, coffee, etc.* --- **Management of Discoloured Teeth** - **Intrinsic stains** *Internal Bleaching - after RCF* - **Extrinsic stains** *Change addictive behaviour / habits* *If applicable* *e.g. Smoking, chewing tobacco, coffee, etc.* --- 19 20 **Discoloured Teeth - 1 & 2** **W/Prof. Paul V. Abbott AO** --- **Management of Discoloured Teeth** - **Intrinsic stains** - Internal Bleaching - after RCF - **Extrinsic stains** - Change addictive behaviour / habits - Prophylaxis - Abrasion - air, ultrasonics, sonics - Enamel microabrasion - External whitening --- **Management of Discoloured Teeth** - **Alternatives to bleaching and whitening** - Labial veneer restorations - Porcelain, composite resin --- *2nd Year DMD - 2020* *Page 11* - **Intrinsic stains** - Internal Bleaching - after RCF - **Extrinsic stains** - Change addictive behaviour / habits - *If applicable* - *e.g. Smoking, chewing tobacco, coffee, etc.* - Prophylaxis - Abrasion - air, ultrasonics, sonics - Enamel microabrasion - External whitening ### **Alternatives to bleaching and whitening** - Labial veneer restorations - Porcelain, composite resin - ==Porcelain is more colour-stable long-term than composite.== - ==A key disadvantage is that adjacent natural teeth may yellow with age, creating a mismatch that requires the veneer to be replaced.== > [!example] Case Example > ==A patient with a yellow tooth due to pulp canal calcification opted for a porcelain veneer because locating and treating the calcified canal for internal bleaching was unpredictable and risked compromising the tooth.== Discoloured Teeth - 1 & 2 W/Prof. Paul V. Abbott AO **Management of Discoloured Teeth** - Alternatives to bleaching and whitening - Labial veneer restorations - Porcelain, composite resin - Crowns - Porcelain, composite resin, acrylic - BUT: these do not remove the underlying discolouration - The aesthetic result may be compromised **Management of Discoloured Teeth** 2nd Year DMD - 2020 Page 12 - Crowns - Porcelain, composite resin, acrylic - BUT: these do not remove the underlying discolouration - The aesthetic result may be compromised > [!tip] > ==Sometimes, internal bleaching is performed *before* placing a veneer or crown to lighten the underlying tooth structure, making it easier to achieve an excellent aesthetic result. In many cases, the result of bleaching is so good that a crown or veneer is no longer necessary.== **Discoloured Teeth - 1 & 2** **W/Prof. Paul V. Abbott AO** **2nd Year DMD - 2020** **Page 13** --- ### **Advantages of Bleaching** - Quick - Cheap - Predictable - Can be re-done - Conservative procedure - No change to the occlusion - Original crown form retained - Restores natural colour and translucence - No effect on the periodontal tissues - Allows stabilisation of gingivae before crowns or veneers – especially in young patients --- ### **Disadvantages of Bleaching** - Caustic solutions - Can change the structure of tooth substance - ? Not always permanent - ? External invasive resorption (EIR) *Reports of an association* *But not proven* --- **25** **26** ## **Advantages of Bleaching** - Quick - Cheap - Predictable - Can be re-done - Conservative procedure - No change to the occlusion - Original crown form retained - Restores natural colour and translucence - No effect on the periodontal tissues - Allows stabilisation of gingivae before crowns or veneers – especially in young patients - ==Ideal for young patients as it avoids placing restorations like crowns whose margins could become exposed as the gingiva matures and recedes to its stable adult position.== ## **Disadvantages of Bleaching** - Caustic solutions - Can change the structure of tooth substance - ? Not always permanent - ? External invasive resorption (EIR) - *Reports of an association* - *But not proven* **Discoloured Teeth - 1 & 2** **W/Prof. Paul V. Abbott AO** **2nd Year DMD - 2020** **Page 14** --- **Effectiveness of Bleaching** - *In Vitro studies* - *In Vivo studies* --- **Effectiveness of Bleaching** - *In Vitro studies - Typical method used* - Stained with blood products - Erythrocyte decomposition - Easier to remove than other causes - Dental material stains are the most difficult to remove - Considered to be easier to bleach recent stains --- 27 28 ## **Effectiveness of Bleaching** ### **In Vitro studies** - *Typical method used* - Stained with blood products - Erythrocyte decomposition - Easier to remove than other causes - Dental material stains are the most difficult to remove - Considered to be easier to bleach recent stains <table> <thead> <tr> <th>Study</th> <th>Year</th> <th>Results</th> </tr> </thead> <tbody> <tr> <td>Freccia et al</td> <td>1982</td> <td>100% lighter than the stained colour</td> </tr> <tr> <td>Stewart and Goerig</td> <td>1989</td> <td>53 - 93% successful (different bl. agents)</td> </tr> <tr> <td>Warren et al</td> <td>1990</td> <td>97% successful</td> </tr> <tr> <td>Rotstein et al</td> <td>1991</td> <td>70% successful</td> </tr> </tbody> </table> <table> <thead> <tr> <th>Study</th> <th>Year</th> <th>Results</th> </tr> </thead> <tbody> <tr> <td>Freccia et al</td> <td>1982</td> <td>100% lighter than the stained colour</td> </tr> <tr> <td>Stewart and Goerig</td> <td>1989</td> <td>53 - 93% successful (different bl. agents)</td> </tr> <tr> <td>Warren et al</td> <td>1990</td> <td>97% successful</td> </tr> <tr> <td>Rotstein et al</td> <td>1991</td> <td>70% successful</td> </tr> </tbody> </table> Discoloured Teeth - 1 & 2 W/Prof. Paul V. Abbott AO 2nd Year DMD - 2020 Page 16 **Range of results** - **“Success”** 45 - 100 % - **“Acceptable”** 2 - 58 % - **“Failures”** 0 - 55 % **Effectiveness of Bleaching** - *In Vivo studies - Some typical examples* - **Brown 1965** 82.5 % “responded” - **Howell 1980** 90.3 % satisfactory 2.4 % no change 7.3 % “considerable improvement” ### **Range of results** > [!info] > ==A review of multiple clinical studies shows a wide range of outcomes, making direct comparisons difficult due to varying methodologies and success criteria.== - **“Success”** - 45 - 100 % - **“Acceptable”** - 2 - 58 % - **“Failures”** - 0 - 55 % **Discoloured Teeth - 1 & 2** **W/Prof. Paul V. Abbott AO** **2nd Year DMD - 2020** **Page 17** --- ### **Effectiveness of Bleaching** *In Vivo studies - Some typical examples* - **Brown 1965** - 82.5 % “responded” - **Howell 1980** - 90.3 % satisfactory - 2.4 % no change - 7.3 % “considerable improvement” - **Holmstrup et al 1988** - 63.2 % good - 26.3 % acceptable - 10.5 % unacceptable - **Friedman et al 1988** - 50 % successful - 29 % acceptable - 21 % failed --- ### **Longevity of Bleaching** *In Vivo studies* - **Brown 1965** - 7.5 % discoloured after 1-5 years - 46.3 % some colour regression - **Howell 1981** - 50 % colour regression by 1 year --- **33** **34** ### **In Vivo studies - Some typical examples** - **Brown 1965** - 82.5 % “responded” - **Howell 1980** - 90.3 % satisfactory - 2.4 % no change - 7.3 % “considerable improvement” - **Holmstrup et al 1988** - 63.2 % good - 26.3 % acceptable - 10.5 % unacceptable - **Friedman et al 1988** - 50 % successful - 29 % acceptable - 21 % failed # Discoloured Teeth - 1 & 2 W/Prof. Paul V. Abbott AO 2nd Year DMD - 2020 Page 18 ## Longevity of Bleaching * **In Vivo studies** * **Brown 1965** * 7.5 % discoloured after 1-5 years * 46.3 % some colour regression * **Howell 1981** * 50 % colour regression by 1 year * **Feiglin 1987** * 55 % discoloured over 6 years * **Holmstrup et al 1988** * 20 % discoloured by 3 years ## Discolouration after Bleaching * Possible reasons (Howell 1981) * Break down of restorations * Bacteria and their by-products * Food, drinks * Permeability of tooth * Saliva or tissue fluid * Food, Drinks * Chemical reduction of oxidation products from the bleaching agent - H₂O₂ * *Unlikely to occur: since bleaching is a one way chemical reaction* ## **Longevity of Bleaching** ### **In Vivo studies** - **Brown 1965** - 7.5 % discoloured after 1-5 years - 46.3 % some colour regression - **Howell 1981** - 50 % colour regression by 1 year - **Feiglin 1987** - 55 % discoloured over 6 years - **Holmstrup et al 1988** - 20 % discoloured by 3 years ## **Discolouration after Bleaching** > [!info] > ==The chemical reaction of bleaching is a one-way oxidation process; it does not reverse. Therefore, any subsequent discolouration is considered a **new stain**. The most likely cause is **microleakage around restorations**, allowing bacteria, their byproducts, and stains from food and drink to penetrate the tooth.== - **Possible reasons (Howell 1981)** - Break down of restorations - Bacteria and their by-products - Food, drinks - Permeability of tooth - Saliva or tissue fluid - Food, Drinks - Chemical reduction of oxidation products from the bleaching agent - H₂O₂ - *Unlikely to occur: since bleaching is a one way chemical reaction* **Discoloured Teeth - 1 & 2** **W/Prof. Paul V. Abbott AO** **2nd Year DMD - 2020** **Page 19** --- **The Chemistry of Bleaching** --- **Bleaching Materials and Methods** - Oxalic acid - 1877 - Hydrogen Peroxide (H₂O₂) - 1884 - Electric current - 1895 - Ultraviolet light - 1911 - Intracoronal heat - 1913 - Superoxol + electric light rays - 1918 - Superoxol + Sodium Perborate - 1924 - Sodium Perborate and Water - 1959 - “Walking bleach” - 1963 --- 37 38 ## **The Chemistry of Bleaching** ### **Bleaching Materials and Methods** - Oxalic acid - 1877 - Hydrogen Peroxide (H₂O₂) - 1884 - Electric current - 1895 - Ultraviolet light - 1911 - Intracoronal heat - 1913 - Superoxol + electric light rays - 1918 - Superoxol + Sodium Perborate - 1924 - Sodium Perborate and Water - 1959 - “Walking bleach” - 1963 - ==This is the modern recommended technique. A paste of **35% hydrogen peroxide (Superoxol)** and **sodium perborate** is sealed inside the pulp chamber for several days.== **Discoloured Teeth - 1 & 2** **W/Prof. Paul V. Abbott AO** **2nd Year DMD - 2020** **Page 20** --- **Internal Bleaching - Chemistry** - **“Walking Bleach” Technique** - **Hydrogen peroxide - H₂O₂** - *Superoxol - 35% H₂O₂* - **Sodium Perborate - 2NaBO₂[OH]₂[nH₂O]** --- **Hydrogen Peroxide - H₂O₂** - **An oxidising agent:** - Produces perhydroxyl and oxygen “free radicals” - *Highly unstable and very reactive* - **Weakly acidic in pure aqueous form:** - Produces more free oxygen radicals - *Weaker bleaching agent than the perhydroxyl radical* *Goldstein & Garber 1995* --- **39** **40** ### **Internal Bleaching - Chemistry** - **“Walking Bleach” Technique** - **Hydrogen peroxide - H₂O₂** - *Superoxol - 35% H₂O₂* - **Sodium Perborate - 2NaBO₂[OH]₂[nH₂O]** ### **Hydrogen Peroxide - H₂O₂** - **An oxidising agent:** - Produces perhydroxyl and oxygen “free radicals” - *Highly unstable and very reactive* - **Weakly acidic in pure aqueous form:** - Produces more free oxygen radicals - *Weaker bleaching agent than the perhydroxyl radical* *Goldstein & Garber 1995* Discoloured Teeth - 1 & 2 W/Prof. Paul V. Abbott AO **Hydrogen Peroxide - H₂O₂** * **BUT at alkaline pH:** * Greater bleaching effect as more perhydroxyl free radical is released * pH: 9.5 – 10.8 * Goldstein & Garber 1995 **Sodium Perborate - 2NaBo₂[OH]₂[nH₂O]** * When contact with water: * Breaks down to produce H₂O₂ - Approx. 10% * Attin et al IEJ 2003 2nd Year DMD - 2020 Page 21 - **BUT at alkaline pH:** - Greater bleaching effect as more perhydroxyl free radical is released - pH: 9.5 – 10.8 - *Goldstein & Garber 1995* ### **Sodium Perborate - 2NaBo₂[OH]₂[nH₂O]** - When contact with water: - Breaks down to produce H₂O₂ - Approx. 10% - *Attin et al IEJ 2003* **Discoloured Teeth - 1 & 2** W/Prof. Paul V. Abbott AO 2nd Year DMD - 2020 Page 22 --- **Sodium Perborate - 2NaBo₂[OH]₂[nH₂O]** × When contact with water:  • Breaks down to produce H₂O₂ - Approx. 10% × Has alkaline pH of 10.0  ∴ Increases the effectiveness of bleaching if used with H₂O₂ --- **Internal Bleaching - Chemistry** × Bleaching - an oxidation-reduction reaction × Agent must diffuse through the dentine × Free radicals attack organic molecules  • Break unsaturated bonds to create simpler molecules   **Less absorption energy**   ∴ **Less light reflected**   ⇒ **Produces a whitening effect** --- 43 44 - Has alkaline pH of 10.0 - ∴ Increases the effectiveness of bleaching if used with H₂O₂ - ==When mixed with H₂O₂, the alkaline pH shifts the reaction to produce more of the highly effective **perhydroxyl free radicals (`•OOH`)**, significantly increasing the bleaching effect. This is why the combination is recommended.== ### **Internal Bleaching - Chemistry** - Bleaching - an oxidation-reduction reaction - Agent must diffuse through the dentine - Free radicals attack organic molecules - ==These free radicals diffuse through the dentine and attack the organic molecules causing the discolouration. They break down complex, pigmented carbon ring structures into simpler, non-pigmented molecules that reflect less light, resulting in a whitening effect.== - Break unsaturated bonds to create simpler molecules - **Less absorption energy** - ∴ **Less light reflected** - ⇒ **Produces a whitening effect** **Discoloured Teeth - 1 & 2** W/Prof. Paul V. Abbott AO 2nd Year DMD - 2020 Page 23 --- **Internal Bleaching - Chemistry** *Goldstein & Garber 1995* - 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 !!!** --- **An *in vitro* comparison of different bleaching agents in the discoloured tooth** *Ho S, Goerig AC.* *J Endod 1989; 15: 106* --- 45 46 *Goldstein & Garber 1995* - Has a “saturation point” - → **Lightening effect slows dramatically** - ==If bleaching continues after the stain is removed, the free radicals will start to break down the tooth's protein matrix. The saturation point is reached when the 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 !!!** --- ***An in vitro comparison of different bleaching agents in the discoloured tooth*** *Ho S, Goerig AC.* *J Endod 1989; 15: 106* --- **Discoloured Teeth - 1 & 2** W/Prof. Paul V. Abbott AO 2nd Year DMD - 2020 Page 24 --- **Ho & Goerig - 1989** - **New Na Perborate + Fresh Superoxol** *93% effective* - **New Na Perborate + 1-year old Superoxol** *73% effective* - **New Na Perborate + Water** *53% effective* - **Old Na Perborate + Water** *53% effective* --- **Ho & Goerig - 1989** **Recommendations:** - **Na Perborate** - avoid moisture contamination - **H₂O₂** - Use a fresh solution - Replace supply every 6 months: track dates - Buy a small jar only: 25 mls - Store in brown glass jar with tight lid/seal - Store in the fridge: cool and dark ### **Ho & Goerig - 1989** - **New Na Perborate + Fresh Superoxol** - *93% effective* - **New Na Perborate + 1-year old Superoxol** - *73% effective* - **New Na Perborate + Water** - *53% effective* - **Old Na Perborate + Water** - *53% effective* - ==The age of the sodium perborate powder did not affect its efficacy, as long as it was kept dry.== #### **Recommendations:** - **Na Perborate** - avoid moisture contamination - **H₂O₂** - Use a fresh solution - Replace supply every 6 months: track dates - Buy a small jar only: 25 mls - Store in brown glass jar with tight lid/seal - Store in the fridge: cool and dark **Discoloured Teeth - 1 & 2** **W/Prof. Paul V. Abbott AO** **2nd Year DMD - 2020** **Page 25** --- **H₂O₂ - Effects on Tooth Structure** *Tittey et al - J Endod 1988; 14: 69-74* - H₂O₂ produces a precipitate on the **enamel** surface - Acid etch first + then H₂O₂ - **More precipitate and a more porous enamel surface** *Tittey et al - EDT 1988; 4: 32-6* - H₂O₂ leaves an amorphous precipitate on **dentine** - Acid etch first + then H₂O₂ - **Less precipitate and more tubules open** --- **H₂O₂ - Effects on Tooth Structure** *Adibfar et al - J Endod 1992; 18: 488-91* - Peroxide is **absorbed** by both enamel and dentine during bleaching - Leaches out if left in water for a long time - Can not remove just by rinsing --- **49** **50** ## **H₂O₂ - Effects on Tooth Structure** - *Tittey et al - J Endod 1988; 14: 69-74* - H₂O₂ produces a precipitate on the **enamel** surface - Acid etch first + then H₂O₂ - **More precipitate and a more porous enamel surface** - *Tittey et al - EDT 1988; 4: 32-6* - H₂O₂ leaves an amorphous precipitate on **dentine** - Acid etch first + then H₂O₂ - **Less precipitate and more tubules open** - *Adibfar et al - J Endod 1992; 18: 488-91* - Peroxide is **absorbed** by both enamel and dentine during bleaching - Leaches out if left in water for a long time - Can not remove just by rinsing **Discoloured Teeth - 1 & 2** **W/Prof. Paul V. Abbott AO** **2nd Year DMD - 2020** **Page 26** --- ### **H₂O₂ - Effects on Bonding Materials** - **Titley et al - EDT 1989; 5: 132-8** - *Highly significant reduction in bond strength of GIC to dentine after treatment with H₂O₂* - **Titley et al - J Dent Res 1988; 67: 1523-8** - *Highly significant reduction in bond strength of composite to enamel treated with H₂O₂* --- ### **H₂O₂ - Effects on Bonding Materials** - **Torneck et al - EDT 1990; 6: 97-103** - **No measurable adhesion of composite to dentine treated with H₂O₂** - **A highly significant difference in bond strength of composite resin to untreated dentine** - **Bond failure was cohesive AND adhesive** - **Suggests H₂O₂ affects setting of bonding resin AND its adhesion to filled resin** --- **51** **52** ## **H₂O₂ - Effects on Bonding Materials** - **Titley et al - EDT 1989; 5: 132-8** - *Highly significant reduction in bond strength of GIC to dentine after treatment with H₂O₂* - **Titley et al - J Dent Res 1988; 67: 1523-8** - *Highly significant reduction in bond strength of composite to enamel treated with H₂O₂* **Discoloured Teeth - 1 & 2** **W/Prof. Paul V. Abbott AO** **2nd Year DMD - 2020** **Page 27** --- ### **H₂O₂ - Effects on Bonding Materials** - **Torneck et al - J Endod 1991; 17: 156-60** - **Water immersion for 7 days** - Eliminated the reduction in bond strength for composite to peroxide treated enamel - Significantly higher bond strength for peroxide-treated enamel compared to saline-treated enamel - Possibly due to improved surface conditioning or cleansing action by the peroxide - Saliva may have similar effect to water, but possibly slower --- ### **Clinical Recommendations** - **After internal bleaching:** - Delay restoration of the access cavity and replacement of other restorations - For a minimum of 14 days - Fill the entire access cavity with Cavit (with NO cotton pellet) for this time - **After external bleaching:** - Delay all restorations for at least 14 days --- **53** **54** - **Torneck et al - EDT 1990; 6: 97-103** - **No measurable adhesion of composite to dentine treated with H₂O₂** - **A highly significant difference in bond strength of composite resin to untreated dentine** - **Bond failure was cohesive AND adhesive** - **Suggests H₂O₂ affects setting of bonding resin AND its adhesion to filled resin** - **Torneck et al - J Endod 1991; 17: 156-60** - **Water immersion for 7 days** - Eliminated the reduction in bond strength for composite to peroxide treated enamel - Significantly higher bond strength for peroxide-treated enamel compared to saline-treated enamel - Possibly due to improved surface conditioning or cleansing action by the peroxide - Saliva may have similar effect to water, but possibly slower ### **Clinical Recommendations** - **After internal bleaching:** - Delay restoration of the access cavity and replacement of other restorations - For a minimum of 14 days - ==The speaker recommends waiting **3-4 weeks** to be safe.== - Fill the entire access cavity with Cavit (with NO cotton pellet) for this time - **After external bleaching:** - Delay all restorations for at least 14 days **Discoloured Teeth - 1 & 2** **W/Prof. Paul V. Abbott AO** **2nd Year DMD - 2020** **Page 28** --- ### **Disadvantages of Bleaching** - Caustic solutions - Can change the structure of tooth substance - ? Not always permanent - ? External invasive resorption (EIR) - Reports of an association - But not proven --- ### **External Invasive Resorption** - Harrington & Natkin 1979 - Reported 7 cases with EIR Radiographic image showing teeth with external invasive resorption ## **Disadvantages of Bleaching** - Caustic solutions - ==Requires careful handling and the use of a dental dam to protect the patient and dental team.== - Can change the structure of tooth substance - ? Not always permanent - ? External invasive resorption (EIR) - Reports of an association - But not proven ## **External Invasive Resorption (EIR)** - Harrington & Natkin 1979 - Reported 7 cases with EIR **Discoloured Teeth - 1 & 2** **W/Prof. Paul V. Abbott AO** **2nd Year DMD - 2020** **Page 29** --- ### **External Invasive Resorption** - Harrington & Natkin 1979 **Reported 7 cases with EIR** - Lado et al 1983 - 1 case - Montgomery 1984 - 1 case - Cvek & Lindvall 1985 - 11 cases - Friedman et al 1988 **4 cases out of 58** **≈ 7%** --- ### **External Invasive Resorption** - **Total 36 cases reported 1979 – 2003** - *But how many teeth have been bleached ??* **Probably millions!!** - **Clinical studies: Total 701 teeth** - **8 cases of EIR (1.1%)** - *Slightly higher than the population estimate of 0.02% - Heithersay 1999* --- Figure showing radiographic images of teeth with external invasive resorption. - Lado et al 1983 - 1 case - Montgomery 1984 - 1 case - Cvek & Lindvall 1985 - 11 cases - Friedman et al 1988 - **4 cases out of 58** - **≈ 7%** ### **Prevalence** - **Total 36 cases reported 1979 – 2003** - *But how many teeth have been bleached ??* - **Probably millions!!** - **Clinical studies: Total 701 teeth** - **8 cases of EIR (1.1%)** - *Slightly higher than the population estimate of 0.02% - Heithersay 1999* **Discoloured Teeth - 1 & 2** **W/Prof. Paul V. Abbott AO** **2nd Year DMD - 2020** **Page 30** --- ### **Possible Factors / Mechanisms** - Trauma - Base over RCF - Level of RCF removed - Heat used in bleaching - Chemical burn from O₂ and H₂O₂ **Cause coagulation and inflammation** **May lead to necrosis of p.d.l.** - Cementum defect --- ### **External Invasive Resorption** - Total 36 cases reported - 10 teeth **No details reported of the bleaching process** - The other 26: **None had cervical seal / base over RCF** **All had H₂O₂** **24 also had Na Perborate** Radiographic images of teeth showing external invasive resorption ### **Possible Factors / Mechanisms** - Trauma - Base over RCF - Level of RCF removed - Heat used in bleaching - Chemical burn from O₂ and H₂O₂ - **Cause coagulation and inflammation** - **May lead to necrosis of p.d.l.** - Cementum defect ### **Analysis of Reported EIR Cases** > [!info] An analysis of 36 reported cases of post-bleaching EIR revealed common factors: > - ==**No protective base** was placed over the gutta-percha in 26 cases.== > - ==All used **hydrogen peroxide**.== > - ==**22 of 26 cases used heat** to accelerate the bleaching.== > - ==10 cases had a history of **trauma** (details were missing for the other 16).== - Total 36 cases reported - 10 teeth - **No details reported of the bleaching process** - The other 26: - **None had cervical seal / base over RCF** - **All had H₂O₂** - **24 also had Na Perborate** **Discoloured Teeth - 1 & 2** **W/Prof. Paul V. Abbott AO** **2nd Year DMD - 2020** **Page 31** --- **External Invasive Resorption** - **Total 36 cases reported** - **10 teeth** - *No details reported of the bleaching process* - **The other 26:** - *None had cervical seal / base over RCF* - *All had H₂O₂* - *24 also had Na Perborate* - *22 used heat* - *10 had history of trauma* - *Others - no detail given* --- **Cervical root resorption following bleaching of endodontically treated teeth** **Madison S, Walton R.** **J Endod 1990; 16: 570-4** --- 61 62 - *22 used heat* - *10 had history of trauma* - *Others - no detail given* --- ***Cervical root resorption following bleaching of endodontically treated teeth*** ***Madison S, Walton R.*** ***J Endod 1990; 16: 570-4*** --- **Discoloured Teeth - 1 & 2** **W/Prof. Paul V. Abbott AO** **2nd Year DMD - 2020** **Page 32** --- **Madison & Walton - 1990** - 45 teeth in dogs - Bleached twice 1 week apart - Reviewed histologically after 1 year **Factors associated with EIR:** - 30% H₂O₂ plus heat - Dentine thickness --- **Madison & Walton - 1990** - **NOT** associated with EIR: - Walking bleach technique - Internal etching - H₂O₂ and Na Perborate > **Na Perborate inhibits macrophages** > **Macrophages stimulate clastic cells** > *Jiménez-Rubio & Segura - JoE 1998* --- ### **Madison & Walton - 1990** - 45 teeth in dogs - Bleached twice 1 week apart - Reviewed histologically after 1 year #### **Factors associated with EIR:** - 30% H₂O₂ plus heat - Dentine thickness #### **Factors NOT associated with EIR:** - Walking bleach technique - Internal etching - H₂O₂ and Na Perborate > **Na Perborate inhibits macrophages** > **Macrophages stimulate clastic cells** > *Jiménez-Rubio & Segura - JoE 1998* > [!tip] Protective Effect of Sodium Perborate > ==Sodium Perborate may have a protective effect, as it has been shown to inhibit macrophages, which are the precursors to resorptive clastic cells.== **Discoloured Teeth - 1 & 2** W/Prof. Paul V. Abbott AO 2nd Year DMD - 2020 Page 33 --- **Possible Factors / Mechanisms** - Trauma - Base over RCF - Level of RCF removed - Heat used in bleaching - Chemical burn from O₂ and H₂O₂ - Cause coagulation and inflammation - May lead to necrosis of p.d.l. - Cementum defect --- **Cemento-Enamel Junction** Diagram showing three tooth cross-sections labeled E (enamel) and C (cementum), with red arrows indicating junction positions and percentages: "30% of teeth", "60 - 65% of teeth", and "5 - 10% of all teeth / 30% of upper incisors". ### **Possible Factors / Mechanisms** - Trauma - Base over RCF - Level of RCF removed - Heat used in bleaching - Chemical burn from O₂ and H₂O₂ - Cause coagulation and inflammation - May lead to necrosis of p.d.l. - Cementum defect ### **Cemento-Enamel Junction** > [!info] The anatomy of the CEJ varies: > - ==**~65%:** Cementum overlaps the enamel.== > - ==**30%:** Cementum and enamel meet edge-to-edge.== > - ==**5-10%:** There is a **gap between the cementum and enamel**, leaving dentine exposed to the oral environment and periodontal tissues. This gap may provide an entry point for resorptive cells to invade the tooth.== **Discoloured Teeth - 1 & 2** W/Prof. Paul V. Abbott AO --- **Heithersay et al - ADJ 1994** - 204 teeth reviewed for up to 19 years after internal bleaching - 4 teeth (1.9%) had EIR - All had luxation injuries - Concluded: > “There is a very low, although positive, risk of EIR after bleaching – especially if there has been a history of trauma to the tooth” --- **Heithersay - Quintessence Int 1999** - 257 teeth with EIR - 0.02% of the population - Assessed for “potential predisposing factors” - Sole factors - Multiple factors --- 2nd Year DMD - 2020 Page 34 ### **Heithersay et al - ADJ 1994** - 204 teeth reviewed for up to 19 years after internal bleaching - 4 teeth (1.9%) had EIR - All had luxation injuries - Concluded: > “There is a very low, although positive, risk of EIR after bleaching – especially if there has been a history of trauma to the tooth” ### **Heithersay - Quintessence Int 1999** - 257 teeth with EIR - 0.02% of the population - Assessed for “potential predisposing factors” - Sole factors - Multiple factors **Discoloured Teeth - 1 & 2** **W/Prof. Paul V. Abbott AO** **2nd Year DMD - 2020** **Page 35** --- **Heithersay - Quintessence Int 1999** - **Potential predisposing factors** - **Orthodontics: 24.1%** - *4.3% with other factors* - **No identifiable factor: 16.4%** - **Trauma: 15.1%** - *10.6% with other factors* - **Restoration in tooth: 14.1%** - **Internal bleaching: 3.9%** - *9.7% with other factors* --- **Heithersay - Quintessence Int 1999** - **Concluded:** - *“There is a very low, although positive, risk of EIR after bleaching ….* - *… especially in association with other potential predisposing factors such as trauma and orthodontic treatment”* --- 69 70 - **Potential predisposing factors** - **Orthodontics: 24.1%** - *4.3% with other factors* - **No identifiable factor: 16.4%** - **Trauma: 15.1%** - *10.6% with other factors* - **Restoration in tooth: 14.1%** - **Internal bleaching: 3.9%** - *9.7% with other factors* - ==Internal bleaching was identified as a sole factor in only **3.9%** of cases.== - **Concluded:** - *“There is a very low, although positive, risk of EIR after bleaching ….* - *… especially in association with other potential predisposing factors such as trauma and orthodontic treatment”* Discoloured Teeth - 1 & 2 W/Prof. Paul V. Abbott AO --- **Cervical canal leakage after internal bleaching procedures** *Smith JJ, Cunningham CJ, Montgomery S.* *J Endod 1992; 18: 476-81* --- 2nd Year DMD - 2020 Page 36 ## **Cervical Canal Leakage** ***Cervical canal leakage after internal bleaching procedures*** ***Smith JJ, Cunningham CJ, Montgomery S.*** ***J Endod 1992; 18: 476-81*** **Discoloured Teeth - 1 & 2** **W/Prof. Paul V. Abbott AO** --- **Cavit base** *Interprox. CEJ* *Labial CEJ* *1mm apical to labial CEJ* **No Cavit** --- **Conclusions - Smith et al 1992** - **2mm Cavit base was sufficient to dentinal penetration of the dye** - **Cavit should be placed slightly coronal to labial CEJ** - **Cemental defects – greater dye penetration in areas of defects** --- *2nd Year DMD - 2020* *Page 37* ### **Study Design** - **Cavit base** - *Interprox. CEJ* - *Labial CEJ* - *1mm apical to labial CEJ* - **No Cavit** ### **Conclusions - Smith et al 1992** > [!info] > ==This study found that significant dye penetration occurred through the cervical dentine, especially on the **proximal surfaces**.== - **2mm Cavit base was sufficient to prevent dentinal penetration of the dye** - **Cavit should be placed slightly coronal to labial CEJ** - **Cemental defects – greater dye penetration in areas of defects** **Discoloured Teeth - 1 & 2** W/Prof. Paul V. Abbott AO --- **An *in vitro* comparison of bleaching agents on the crowns and roots of discoloured teeth** *Warren MA, Wong M, Ingram TA.* *J Endod 1990; 16: 463-7* --- **Warren *et al* - 1990** - IRM base at CEJ or 2mm below CEJ **No difference in bleaching result** - **BUT** - also bleached some of the tooth root **Effectiveness of IRM “seal” against liquid penetration is very questionable** --- *2nd Year DMD - 2020* *Page 38* --- ***An in vitro comparison of bleaching agents on the crowns and roots of discoloured teeth*** ***Warren MA, Wong M, Ingram TA.*** ***J Endod 1990; 16: 463-7*** --- ### **Warren et al - 1990** - IRM base at CEJ or 2mm below CEJ - **No difference in bleaching result** - **BUT** - also bleached some of the tooth root - **Effectiveness of IRM “seal” against liquid penetration is very questionable** - ==IRM is therefore not a suitable base material for this purpose.== **Discoloured Teeth - 1 & 2** **W/Prof. Paul V. Abbott AO** **2nd Year DMD - 2020** **Page 39** --- **RECOMMENDED to cover root canal filling with 2mm Cavit before bleaching** --- **Why not GIC ???** - Very difficult to place without getting on labial dentine wall of access cavity - Very difficult to remove if on labial wall - GIC’s not proven to prevent moisture penetration through dentine --- 77 78 ## **Recommendation for Bleaching Procedure** **RECOMMENDED to cover root canal filling with 2mm Cavit before bleaching** ### **Why not GIC ???** > [!failure] Glass Ionomer Cement (GIC) is **not recommended** as a base material for several reasons: > - ==**Poor Seal:** It does not provide an adequate seal against liquid penetration.== > - ==**Difficult to Place:** It is challenging to place and shape correctly deep within the access cavity.== > - ==**Difficult to Remove:** If any GIC gets on the labial wall, it will block the bleaching agent. Removing it is difficult without also removing tooth structure, as it requires a bur. Cavit, being a soft material, is easy to place, shape, and remove.== - Very difficult to place without getting on labial dentine wall of access cavity - Very difficult to remove if on labial wall - GIC’s not proven to prevent moisture penetration through dentine Discoloured Teeth - 1 & 2 W/Prof. Paul V. Abbott AO **RECOMMENDED to cover root canal filling with 2mm Cavit before bleaching** 79 80 2nd Year DMD - 2020 Page 40 # **Discoloured Teeth - 1 & 2** ## **W/Prof. Paul V. Abbott AO** ### **2nd Year DMD - 2020** - **RECOMMENDED to cover root canal filling with 2mm Cavit before bleaching** > [!success] Recommended Procedure > Based on the evidence, the following procedure is recommended to maximize effectiveness and minimize risks: > 1. ==**Remove Gutta-Percha:** The root filling material should be removed to a level at least **2 mm apical to the labial CEJ**.== > 2. ==**Place a Protective Base:** A **2 mm thick layer of Cavit** should be placed over the remaining gutta-percha.== > 3. ==**Shape the Base:** The Cavit should be shaped into a Discoloured Teeth - 1 & 2 W/Prof. Paul V. Abbott AO 81 82 2nd Year DMD - 2020 Page 41 Figure 6.4a-d showing clinical views of discoloured teeth with isolation and treatment steps. Figure showing a tooth isolated with a rubber dam and clamp during a dental procedure. [[O6AB DiscolouredTeeth.pdf#page=1|O6AB DiscolouredTeeth, p.1]] [[O6AB DiscolouredTeeth.pdf#page=2|O6AB DiscolouredTeeth, p.2]] [[O6AB DiscolouredTeeth.pdf#page=3|O6AB DiscolouredTeeth, p.3]] [[O6AB DiscolouredTeeth.pdf#page=4|O6AB DiscolouredTeeth, p.4]] [[O6AB DiscolouredTeeth.pdf#page=5|O6AB DiscolouredTeeth, p.5]] [[O6AB DiscolouredTeeth.pdf#page=6|O6AB DiscolouredTeeth, p.6]] [[O6AB DiscolouredTeeth.pdf#page=7|O6AB DiscolouredTeeth, p.7]] [[O6AB DiscolouredTeeth.pdf#page=8|O6AB DiscolouredTeeth, p.8]] [[O6AB DiscolouredTeeth.pdf#page=9|O6AB DiscolouredTeeth, p.9]] [[O6AB DiscolouredTeeth.pdf#page=10|O6AB DiscolouredTeeth, p.10]] [[O6AB DiscolouredTeeth.pdf#page=11|O6AB DiscolouredTeeth, p.11]] [[O6AB DiscolouredTeeth.pdf#page=12|O6AB DiscolouredTeeth, p.12]] [[O6AB DiscolouredTeeth.pdf#page=13|O6AB DiscolouredTeeth, p.13]] [[O6AB DiscolouredTeeth.pdf#page=14|O6AB DiscolouredTeeth, p.14]] [[O6AB DiscolouredTeeth.pdf#page=15|O6AB DiscolouredTeeth, p.15]] [[O6AB DiscolouredTeeth.pdf#page=16|O6AB DiscolouredTeeth, p.16]] [[O6AB DiscolouredTeeth.pdf#page=17|O6AB DiscolouredTeeth, p.17]] [[O6AB DiscolouredTeeth.pdf#page=18|O6AB DiscolouredTeeth, p.18]] [[O6AB DiscolouredTeeth.pdf#page=19|O6AB DiscolouredTeeth, p.19]] [[O6AB DiscolouredTeeth.pdf#page=20|O6AB DiscolouredTeeth, p.20]] [[O6AB DiscolouredTeeth.pdf#page=21|O6AB DiscolouredTeeth, p.21]] [[O6AB DiscolouredTeeth.pdf#page=22|O6AB DiscolouredTeeth, p.22]] [[O6AB DiscolouredTeeth.pdf#page=23|O6AB DiscolouredTeeth, p.23]] [[O6AB DiscolouredTeeth.pdf#page=24|O6AB DiscolouredTeeth, p.24]] [[O6AB DiscolouredTeeth.pdf#page=25|O6AB DiscolouredTeeth, p.25]] [[O6AB DiscolouredTeeth.pdf#page=26|O6AB DiscolouredTeeth, p.26]] [[O6AB DiscolouredTeeth.pdf#page=27|O6AB DiscolouredTeeth, p.27]] [[O6AB DiscolouredTeeth.pdf#page=28|O6AB DiscolouredTeeth, p.28]] [[O6AB DiscolouredTeeth.pdf#page=29|O6AB DiscolouredTeeth, p.29]] [[O6AB DiscolouredTeeth.pdf#page=30|O6AB DiscolouredTeeth, p.30]] [[O6AB DiscolouredTeeth.pdf#page=31|O6AB DiscolouredTeeth, p.31]] [[O6AB DiscolouredTeeth.pdf#page=32|O6AB DiscolouredTeeth, p.32]] [[O6AB DiscolouredTeeth.pdf#page=33|O6AB DiscolouredTeeth, p.33]] [[O6AB DiscolouredTeeth.pdf#page=34|O6AB DiscolouredTeeth, p.34]] [[O6AB DiscolouredTeeth.pdf#page=35|O6AB DiscolouredTeeth, p.35]] [[O6AB DiscolouredTeeth.pdf#page=36|O6AB DiscolouredTeeth, p.36]] [[O6AB DiscolouredTeeth.pdf#page=37|O6AB DiscolouredTeeth, p.37]] [[O6AB DiscolouredTeeth.pdf#page=38|O6AB DiscolouredTeeth, p.38]] [[O6AB DiscolouredTeeth.pdf#page=39|O6AB DiscolouredTeeth, p.39]] [[O6AB DiscolouredTeeth.pdf#page=40|O6AB DiscolouredTeeth, p.40]] [[O6AB DiscolouredTeeth.pdf#page=41|O6AB DiscolouredTeeth, p.41]]