Bleaching of Nonvital TeethDR. HAKAN ÇOLAK

DDS, PHD

ISHIK UNIVERSITY SCHOOL OF DENTISTRY

DEPARTMENT OF RESTORATIVE DENTISTRY

Thermocatalytic Technique of Bleaching for Nonvital Teeth

Isolate the tooth to be bleached using rubber dam

Place bleaching agent (superoxol and sodium perborate separately or in combination) in the tooth chamber

Heat the bleaching solution using bleaching stick/light curing unit

Repeat the procedure till the desired tooth color is achieved

Wash the tooth with water and seal the chamber using dry cotton and temporary restorations

Recall the patient after 1 to 3 weeks

Do the permanent restoration of tooth using suitable

composite resins afterwards.

Intracoronal Bleaching/Walking Bleach of Nonvital Teeth

It involves use of chemical agents within the coronal portion of an endodontically treated tooth to remove tooth discoloration.

Indications of Intracoronal Bleaching Discolorations of pulp chamber origin

Moderate to severe tetracycline staining

Dentin discoloration

Discolorations not agreeable to extracoronal bleaching.

Intracoronal Bleaching/Walking Bleach of Nonvital Teeth

Contraindications of Intracoronal Bleaching Superficial enamel discoloration

Defective enamel formation

Presence ofcaries

Unpredictable prognosis of tooth.

Intracoronal Bleaching/Walking Bleach of Nonvital Teeth

Steps Take the radiographs to assess the quality of obturation.

If found unsatisfactory, retreatment should be done

Isolate the tooth with rubber dam

Prepare the access cavity, remove the coronal gutta percha, expose the dentin and refine the cavity

Place mechanical barriers of 2 mm thick, preferably of glass ionomer cement, zinc phosphate, IRM, polycarboxylate cement on

root canal filling material

The coronal height of barrier should protect the dentinal tubules and conform to the external epithelial attachment

Intracoronal Bleaching/Walking Bleach of Nonvital Teeth

Steps (Con’t) Now mix sodium perborate with an inert liquid (localanaesthetic,

saline or water) and place this paste into pulp chamber

After removing the excess bleaching paste, place a temporary restoration over it

Recall the patient after 1 to 2 weeks, repeat the treatment until desired shade is achieved

Restore access cavity with composite after 2 weeks.

Walking bleach, A, Internal staining of dentin caused by remnants of obturating materials (OM) in the chamber as well as by materials and tissue debris in pulp horns (PH). B, Coronal restoration is removed completely. C, A protective cement base (B) is placed over the gutta-pecha. A paste (P) of sodium perborate and hydrogen peroxide is placed. D, A thick mix of temporay cement (Z) seals access. E, At a subsequent appointment when the desired shade reached, a permanent cement is placed (TS) at the pulp chamber and composite resin (C) to seal of the access

Complications of Intracoronal Bleaching

External root resorption Chemical burns if using 30 to 35 percent H2 O2

Decrease bond strength of composite.

Laser Assisted Bleaching Technique

This technique achieves power bleaching process with the helpof efficient energysource with minimum side effects.

Laser whitening gel contains thermally absorbed crystals, fumed silica and 35 percent H2O2

In this, gel is applied and is activated by light source which further activates the crystals present in gel, allowing dissociation of oxygen and therefore better penetration into enamel matrix.

Following laser have been approved by FDA for tooth bleaching: Argon laser

CO2 laser

EFFECTS OF BLEACHING AGENTS ON TOOTH AND ITS SUPPORTING STRUCTURES

Tooth Hypersensitivity

Common side effect of external tooth bleaching. Higher incidences of tooth sensitivity (67% - 78%)

are seen after in office bleaching with hydrogen peroxide in combination with heat.

The mechanism responsible for external tooth bleaching though is not fully established, but it has been shown that peroxide penetrated enamel,

dentin and pulp.

This penetration was more in restored teeth than that of intact teeth.

Effects on Enamel

Studies have shown that 10 percent carbamide peroxide significantly decreased enamel hardness. But application of fluoride showed improved remineralization after bleaching

Effects on Pulp

Penetration of bleaching agent into pulp through enamel and dentin occur resulting in tooth sensitivity.

Studies have shown that 3 percent solution of H2O2 can cause: Transient reduction in pulpal blood flow

Occlusion of pulpal blood vessels.

Effects on Restorative Materials

Increased surface hardness Surface roughening and etching Decrease in tensile strength Increased microleakage No significant color change of composite material

itself other than the removal of extrinsic stains around existing restoration

Toxicity

The acute effects of hydrogen peroxide ingestion are dependent on the amount and the concentration of hydrogen peroxide solution ingested.

The effects are more severe, when higher concentrations are used.

Signs and symptoms usually seen are ulceration of the buccal mucosa, esophagus and stomach, nausea, vomiting, abdominal distention and sore throat.

It is therefore important to keep syringes with bleaching agents out of reach of children to prevent any possible accident.