TREATMENT OF DISCOLORED ANTERIOR TEETH

Introduction

One of the most frequent reasons for seeking dental treatment or care is discolored anterior teeth. Even persons having teeth with normal color often request to have them more whiter. Treatment options include removal of surface stains, bleaching, microabrasion or macroabrasion, veneering and placement of porcelain crowns. Many dentists recommend porcelain crowns as the best solutions for badly discolored teeth. If crowns are properly done with the highly esthetic ceramic materials presently available, they have great potential for being esthetic and long lasting. On the other hand, there are increasing number of patients who do not want their teeth “cut down” for crowns and are electing an alternative, conservative approach such as veneers, that preserves as much of the natural tooth as possible. Their treatment is performed with the understanding that the conservative measures may be less “permanent”.

Discolorations maybe classified as

1) Extrinsic stains: Extrinsic stains are located on the outer surfaces of the teeth.

2) Intrinsic stains: Intrinsic stains are those which are internal or present with in the tooth structures.

Discoloration Cause

- White Fluorosis

- Light yellow Fluorosis, aging, Tetracycline (Type I)

- Dark yellow (moderate stain) Aging, Tetracycline (Type II)

- Brown (dark stain) Fluorosis, Tetracycline (Type I & II) or endodontic therapy

- Bluish gray (severe stain) Tetracycline stain or endodontic therapy

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- Black Caries, fluorosis, or amalgam stain

Extrinsic Discolorations:

Metallic Non-metallic

- Occupational exposure to metallic salts and with a number of medicines containing metal salts.

Characteristics black staining of teeth in people using iron supplements.

Cu causes a green stain in mouth rinses containing Cu salts.

AgNO3 salt used causes a grey colour.

Stannous fluoride causes a golden brown discoloration.

- Are adsorped onto tooth surface deposits such as plaque / acquired pellicle.

- Aetiological agents include

Diet.

Beverages.

Tobacco.

Mouth rinses.

Other medicaments.

- Staining effect due to prolonged rinses with chlorexhidine.

Originally the mechanism was thought to be breakdown of chlorhexidine, the oral cavity to a) form parachloraniline and b) it decreases the bacterial activity such that partly metalised sugars were broken down and degraded over time to produce brown-coloured compounds. Recently 3 mechanisms:

a) Non-enzymatic browning reaction decreased (Maillaro reaction). Chlorhexidine accelerates the formation of the acquired pellicle (the proteins and carbohydrates in the acquired pellicle could undergo a series of condensation and polymerization reaction leading to discoloration of the acquired pellicle).

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b) The formation of pigmented sulphides of iron

tin

this suggests that chlorhexidine denatures the acquired pellicle to expose sulphur radicals

which then react with the metal ions to form metal sulphide.

increased level of iron are found in chlorehexidine.

c) Precipitation of dietary chromogens by chlorhexidine

plaque inhibition is dependent upon absorption of chlorexidine onto the tooth surface.

- Locally adsorped chlorhexidine complexed with ions from the oral environment and bind dietary chromogens to surfaces to produce staining.

Etiology:

In young patients stains of almost any color can be found and are usually more prominent in the cervical areas of the teeth. These stains may be related to remnants of Nasmyth’s membrane, poor oral hygiene, existing restorations, bleeding gums, plaque accumulation, eating habits or the presence of chromogenic bacteria or fungi.

In older patients stains on the surfaces of the teeth are more likely to be brown, black, a gray and occur on areas adjacent to the gingival tissues. Poor oral hygiene is a contributing factor, but coffee, tea and certain types of food or medications can produce stains even on plaque free surfaces. Tobacco stains also are observed frequently. Existing restorations may be discolored for the same reasons.

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Exotic decoration of anterior teeth by etching with citrus fruit juice and applying black pigment In southeast Asia, some women traditionally dye their teeth with beetle nut juice to match their hair and eyes as a sign of beauty. Slices of lemon are held in contact with the teeth before applying, the beetle nut juice, to make the staining process more effective. This example was probably one of the first applications of the acid etch technique. A weak acid such as that found in citrus fruits is known to cause rapid decalcification of the enamel.

Treatment:

- Mostly by routine oral prophylactic procedures.

- Some superficial discolorations on the tooth colored restorations and decalcified areas on the teeth which cannot be removed by prophylactic procedures, may be accomplished by mild microabrasion or by surfacing the thin outer discolored layer with flame – shaped carbide finishing bur or diamond instrument (macroabrasion) followed by polishing with abrasive discs or points to obtain an acceptable result.

Intrinsic discolorations:

Are caused by deeper internal stains. Teeth with vital / non vital pulps can be affected as well as root canal treated teeth.

Etiology:

Vital teeth:

- During crown formation

- Hereditary disorders

- Medications (Tetracycline preparations)

- Excess fluoride injection

- Exanthamatous fever

- Trauma

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Staining may be located in enamel / dentin. Discoloration restricted to dentin may still show through enamel.

Tetracycline stains: (Cohen)

- Teeth are most susceptible to tetracycline discoloration during formation, beginning in the 2nd trimester in utero and continuing to roughly 8 years. Tetracycline particles get incorporated into the dentin during calcification of teeth, three chelation with calcium and forms tetracycline orthophosphate.

- The discoloration itself results from exposure of the teeth to sunlight, which is why the labial surfaces of the incisors tend to darken more quickly and intensely while the protected molars remain yellow longer.

- Tetracycline staining is variable in its extent, color intensity and location, since the severity of stains depends on the time and duration of drug administration.

3 major categories proposed by Jordan and Boksman:

Ist degree – tetracycline staining, a light yellow or light gray stain, uniformly distributed in local areas, highly amenable to bleaching.

IInd degree IIIrd degree

- Triangular but with darker or more extensive yellow or gray stains.

- Require more bleaching or

- A combination of in-office / home matrix.

- Most intense often dark grey or blue in colour.

- Most distinctive aspect is banding.

- Veneering technique with opaquers to provide satisfactory esthetic results.

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IVth degree – Tetracycline stains that are simply too dark to attempt vital bleaching and for which bonding or laminating is a more appropriate place to begin.

Minocycline:

The recent sudden appearance of ring like stains on the teeth of adolescents and adults could be due to a semisynthetic derivative of tetracycline, minocycline, given in routine prescription for acne.

Minocycline is absorbed from the GIT and combines poorly with calcium. Instead, it chelates with iron and forms insoluble complexes.

Minocycline pigment produced in tissues is same or very similar to that produced by ultra-violet radiation.

Tetracycline stains: Is a most distracting generalized type of intrinsic discoloration. The severity depends on the dosage, duration of exposure, the type of tetracycline analog used. Color varies from yellow-orange to dark blue-gray.

Fluorosis : Consuming excess fluoride in drinking water at the time of teeth forming. Because of the high fluoride content in the enamel, fluorosed teeth may be difficult to treat with acid etching and resin bonding.

Hypoplastic defects:

- Due to enamel and dentin malformation.

- Poor oral hygiene following tooth eruption

- Poor oral hygiene during orthodontic treatment

White spots : are the localized areas of demineralisation or failure of enamel to calcify properly resulting in decalcified white spots.

Other causes : of intrinsic discolorations are caries, metallic restorations, corroded pins, and leakage or secondary caries around existing restorations.

Yellower teeth: Aging wear of the enamel thinner enamel underlying dentin becomes transparent. Due to this permeability of the teeth,

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usually organic pigments from foods, drinks, tobacco products etc. can be seen.

Non-vital teeth: infected or degeneration of pulp due to trauma, deep caries, or irritation from the restorative procedures.

Yellowing of teeth – Trauma resulting in calcific metamorphosis – calcification of pulp chamber and / or root canals.

Treatment:

- Justification of treatment – Patient education; Motivation.

- Conservative methods like bleaching / microabrasion / macroabrasion/ veneering techniques can be used.

- Mild discolorations are best left untreated, bleached or treated conservatively with microabrasion or macroabrasion as no restorative material is as good as the natural, healthy tooth structure.

- Correction of intrinsic discoloration caused by failing restorative entails replacement of the faulty position or the entire restoration.

- Correction of discolorations due to carious lesions requires appropriate restorative treatment.

Dental conditions that cause discoloration

- Caries is a primary cause of pigmentation, appearing as opaque, white halo or gray discoloration.

- Bacterial degradation of food debris in areas of tooth decay or decomposing filling can cause even deeper brown to black discolorations.

- Degraded tooth-colored restorations such as acrylics, glass ionomer, or composites can cause teeth to look gray and discolored.

- Restorations with metal amalgams, even silver and gold ones, may reflect shadows through the enamel, even when there has been no

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breakdown in the material. Replacing these restorations with less visible materials such as composite resin often changes the appearance of the tooth enough to satisfy the patients without bleaching.

- The most troublesome staining from dental treatments are those from oils, iodines, nitrates, root canal sealers, pins and other materials that have penetrated the dentinal tubules. The length of the time, the stain has been present determines the residual discoloration and can affect the eventual success of bleaching efforts.

A Rationale For Technique Selection and Material Choice for Anterior Restorations

- Periodontal health

- Caries incidence

- Occlusion

Case selectionAnd

Treatment Planning

- Orthodontics

- Esthetic evaluation

- Economics

Bleaching Non-Bleaching

- In office

Vs- At

home

- Original shade O.K.

- Economics- Other

(Smoker, Pregnancy)

Cosmetic contouring

Bonding – Partial coverage

Full labial coverage

Full coverage Bonded

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- Class III, IV, V- Partial veneer

- Direct resin veneers

- Indirect resin veneers

- Porcelain veneers

- All Porcelain bonded

- Resin to metal- Porcelain to

metal

Bleaching treatment:

The lightening of the color of a tooth through the application of a chemical agent to oxidize the organic pigmentation in the tooth is referred to as bleaching.

Types:

Vital teeth bleaching in office bleaching

Non vital teeth bleacing Home bleaching

(night guard bleaching matrix)

Contraindications of Bleaching:

- Too much sensitivity because of severe erosion of the enamel, extremely large pulps, exposed root surfaces, the transient hyperemia associated with orthodontic tooth movement, or the patient’s report of sensitivity.

- Teeth with white or opaque spots. Furthermore, many patients report the difference between the spots varies during the cource of the day, depending on a host of factors ranging from how dry the mouth is to the use of alcohol. A preferable treatment would be attempting to remove the white spot with microabrasion.

- Extremely dark strains, especially those with banding or with uneven distribution.

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- Teeth that have been bonded, laminated or have extensive restorations.

No, one, bleaching technique is effective in every solution, and success is not equals. Often with vital bleaching, a combination of the in-office technique and the dentist prescribed home applied technique will have better results than either techniques used alone.

Vital bleaching: Bleaching of vital teeth in-office was first reported in 1868. Although, there are reports of a 3% ether-peroxide mouthwash used for bleaching in 1893, the “dentist-prescribed home-applied” (night guard vital bleaching) began around 1968.

Indications:

1) Intrinsically discolored teeth from aging / drug ingestion.

2) Trauma.

3) As an alternative treatment for failed non-vital walking bleach.

4) Before and after restorations to harmonize shades of the restorative materials with natural teeth.

5) Single teeth which have darkened from trauma, but are still vital or have a poor endodontic prognosis due to absence of a relatively visible canal.

Types :

In office technique or “power bleaching” (calcific metamorphosis).

Out side the office technique or “night guard vital bleaching”.

These technique may be used separately or in combination with one another.

Advantages: (in general)

1) Safer.

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2) No effect on existing restorative materials because H2O2 has such a low molecular weight, it easily passes through the enamel and dentin.

3) Mild tooth sensitivity occasionally experienced during treatment. However, this effect is transient, and no long-term harm to the pulp has been noted.

Advantages of the in-office vital bleaching techniques are that:

1) While using very caustic chemicals, it is totally under the dentists control.

2) The soft tissue is generally protected from the process.

3) It has the potential for bleaching teeth more rapidly.

Disadvantages primarily related to the:

1) The cost.

2) The unpredictable outcome.

3) The unknown duration of the treatment. The features that warrant concern and caution include.

4) The potential for soft tissue damage to patient and provider.

5) The discomfort of a rubber dam.

6) The potential for post treatment sensitivity.

Non-vital bleaching procedures:

Bleaching of non-vital teeth was first reported in 1848. The primary indication for non-vital bleaching is to lighten teeth which have undergone root canal therapy. This discoloration may be a result of:

1) Bleeding into the dentin from trauma prior to root canal therapy.

2) Degradation of pulp tissue left in the chamber after such therapy.

3) Staining from restorative materials and cements placed in the tooth as a part of the root canal treatment. Most posterior teeth which have

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received RCT require cast restorations which encompass the tooth to prevent subsequent fracture. However, anterior teeth needing restorative treatment and, which are largely intact may be restored with composite rather than with partial or full coverage restorations without significantly compromising the strength of the tooth. This knowledge has created a resurgence in the utilization of non-vital bleaching techniques.

Technique of non-vital bleaching:

In office thermocatalytic technique.

Out of the office technique (walking bleach).

Combination of these two.

Although non-vital bleaching in quite effective, there is a potential (<1%) for a most deleterious side effect termed cervical resorption. This sequela requires prompt and aggressive treatment. On animal models, cervical resorption has been observed most often when using the thermocatalytic technique. Therefore, the walking bleach technique or an in office technique which does not require the use of heat are preferred for non-vital bleaching. To reduce the possibility of resorption,

1) Immediately after bleaching a paste of calciumhydroxide powder, and sterile water is placed in the operated pulp chamber as described later.

2) Also, sodiumperborate alone, rather than in conjunction with hydrogenperoxide, may be used as the primary bleaching agent. Although sodium perborate may bleach slowly, it is safer and less offensive to the tooth. Periodic radiographs should be made post-bleaching to screen for cervical resorption, which generally has its onset in 1-7 years.

Other treatment options for cervical resorption are:

- Forced orthodontic extrusion

- Surgery

- Extraction

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- Submersion of the root

In office non-vital bleaching technique:

In office non-vital bleaching for non-vital teeth is historically a thermocatalytic technique involving the placement of 30% H2O2 into the debrided pulp chamber and activation of the oxidation process by placement of a heating instrument into the pulp chamber. The diffusion of H2O2, through the patent dentinal tubules into the cervical PDL, may initiate a local inflammatory reaction. A more recent technique utilize a light activated bleaching preparation of 30% H2O2 that requires no heat. This technique in frequently the preferred in-office technique for bleaching non-vital teeth. In both techniques it is imperative that a sealing cement (polycarboxylate) or light cured glass ionomer cement is to be placed over the exposed root canal filling prior to application of the bleaching agent.

Walking bleach technique:

1) Evaluate the potential for occlusal contact on the area of the root canal access opening.

2) Rubber dam isolation of the tooth to be bleached.

3) Remove all materials in the coronal portion of the tooth (access opening).

4) Remove gutta percha to ~2mm apical of the clinical crown.

5) Enlarge the endodontic access opening sufficiently to ensure complete debridement of the pulp chamber.

6) Place a polycarboxylate cement or light cured GIC to seal the exposed gutta percha to prevent the percolation of the bleaching agent into the root canal.

7) Trim the excess material once it sets so as to expose the discolored peripheral dentin.

8) Using a cement spatula with heavy pressure on a glass slab, blend one drop of 30% hydrogenperoxide with enough sodium perborate to form a creamy paste (Superoxal solution).

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9) Use a spoon excavator or similar instrument to fill the pulp chamber to within 2mm of the cavosurface margin with the bleaching mixture, avoiding contact with the enamel cavosurface margin of the access opening.

10) Use a cotton pallet to blot the mixture to place.

11) Now place a temporary sealing material such as IRM or cavit to seal the access opening.

12) The area should remain isolated for 5 minutes after closure to evaluate the adequacy of sealing.

The bleaching mixture is very active for 24 hours, after which little potential for harm to tissue exists. The mixture may be changed every 3 to 5 days and usually 1-3 treatments are required. If sodium perborate is used alone, it should be changed bi-weekly.

Na perborate Na metaborate + H2O2 & release O+

When mixed with superoxol

Na metaborate + H2O + O+ (active O2) This oxidizes and discolors the stain slowly.

To overcome the disadvantage of cervical root resorption associated with the walking bleach technique, Spasser suggested the use of

Recent Advances

a) Sodium perborate and H2O

The procedure for the technique is same

The reaction is

Na perborate + H2O decompose Na Metaborate + H2O2

H2O2 H2O + O2

Active oxygen which starts the bleaching process.

The content of Nascent O+ depends on the type of Na perborate used:

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Na perborate monohydrate release 16% O2

Trihydrate releases 11.8% O2

Tetrahydrate releases 10.04% O2

To diminish the risk of cervical root resorption, use of Na perborate trihydrate or tetrahydrate with water has been recommended.

b) Recently, a modified walking bleach technique using 10% carbamide peroxide has been described. This is known as inside / outside bleaching technique. (It consists of administration by the patient of the bleaching agent within and outside the tooth simultaneously).

Advantages:

Time needed to complete the treatment (3-4 days). The use of catalase to eliminate the residual O2 from the tooth structure, contributes to the rapid treatment.

In-office vital bleaching technique:

Preparing the teeth for Bleaching

1) Place Vaseline or cocoa butter on the lips and gingival tissues prior to the application of the rubber dam.

2) Isolate the anterior teeth and sometimes the first premolars as well, with a heavy rubber dam to provide maximum retraction of tissue and an optimal seal around the teeth.

3) Place a 35% H2O2 soaked gauze or a gel form of H2O2 on the teeth.

Note: the patient is instructed to note any sensation of burning of the lips or gingiva, which would indicate a leaking dam and the need to terminate treatment.

4) The oxidation reaction of the H2O2 can be accelerated by applying heat with either a heating instrument (2 min per tooth) set at the maximum tolerance of the patient, or with an intense light (30 min per arch).

5) Upon completion of the treatment, rinse the teeth, remove the rubber and caution the patient about post operative sensitivity.

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Bleaching treatments are generally rendered weekly for 2-6 treatments with each treatment lasting for 30-45 minutes. Patients may experience transient sensitivity of teeth between appointments, but again, no long term adverse pulpal effects have been reported.

Originally the thermocatalytic technique of vital bleaching was is used 13 inches away from the teeth to be bleached temperature – 115-140°.

A bleaching light is used in this at a temperature less than 100°C so as not to damage the pulp.

The patient and the operator should be protected from the bleaching light.

- The bleaching light could be a photoflood lamp that focuses its rays on the labial surface, providing light as well as heat.

- Or a polymerization light to accelerate the bleaching process.

- Hodosh and colleagues introduced a rheostat controlled solid state heating device with specially designed tips that allow the dentist to provide pin-point bleaching and heating in grooves, depressions and in smaller areas.

Advantages:

- Require less time.

- Illuminator – a state of the art bleaching instrument that combines an activation light and activation want for bleaching procedures on both vital and pulpless teeth.

- Then, came into use, the combination of

(1 part) (5 parts) (5 parts)

ether + HCl + H2O (Old Mc Kein’s solution)

(0.2ml) 36% (1 ml) 30% (1 ml) - pH 4.6

to bleach the teeth According to Grossman

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The disadvantage with this type of technique is that it abrades the enamel surface more readily, resulting in over contouring or flattening of the crown.

To overcome this, HCl was replaced with NaOH to neutralize the acidic environment (as it creates an alkaline environment). This was termed as the New McKein’s solution – pH 9.

Ether Removal of surface debris.

HCl Initial etching / entry.

H2O2 (discovered by Abbot) Oxidizes removes the stains.

NaOH decreases the amount of decalcification produced by H2O2

and creates an alkaline environment at pH of 9 compared to pH of 4.6. Recent studies have demonstrated that this pH / alkalinity enhances the bleaching mechanism.

Controversy exists as to whether to:

Etch before bleaching No to etch

- If your case suggests the need to enhance the penetrability of the bleaching solution, you can etch lightly using 35-37% buffered phosphoric acid for 5 seconds.

- Increased stain reduction has been noted.

- Falkenstein reports that the combination increased penetration on the calcium phosphate tetracycline molecule to reach upto 5-7µ into the surface which

- 10µ of enamel are lost during acid etching in addition to the 25µ of enamel that are etched. Furthermore, if it is etched, it must be polished after every appointments.

- Haywood points out “to not etch” preserves the enamel, retaining the fluoride rich surface layer of enamel, as well as shortening of the appointment time.

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is very high.

- Begin treatment on the most discolored teeth, proceeding to the lesser ones.

- Yellow / yellow brown stains are easier to remove than grey.

- Incisal halves of teeth respond to bleach more quickly than cervical halves, due to thinner dentin.

The advantages of the dentist prescribed – home applied technique (night guard vital bleaching) are:

1) The use of a lower concentration of peroxide (generally 10%-15% carbomide peroxide).

2) The ease of application.

3) Minimal side effects.

4) Lower cost due to the reduced chair time required for treatment.

The disadvantages are:

1) The reliance on patient compliances.

2) The longer treatment time.

3) The (unknown) potential for soft tissue changes with excessively extended use.

This uses an athletic style vacuum formed soft mouthguard and currently available 10% carbamide peroxide – containing materials to bleach the teeth.

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There are 2 basic regimens for the application of the whitening solution.

a) Sleeping with the nightguard filled with the bleaching material each night.

b) Wearing the loaded nightguard during the day while changing the solution every 1½ - 2 hrs.

Treatment time is 4-6 weeks for nighttime bleaching and 1-3 wks for the daytime regimen of multiple applications.

Dentist prescribed-home applied technique: Night guard / Matrix bleaching.

1) An alginate impression of the arch to be treated is made free of bubbles and poured in cast stone.

Note: After appropriate infection control procedures, rinse the impression vigorously, and then pour with cast stone. In complete rinsing of the impression may cause a softened surface on the stone, which may result in a guard which is slightly too small and irritates tissue.

2) Trim the resultant cast around the periphery to eliminate the vestibule and thin the base of the cast.

3) Allow the cast to dry, and block out any significant undercuts.

4) The night guard is formed on the cast using a heat / vacuum forming machine. After the machine has warmed up for 10 mintues, a sheet of 0.2" – 0.35" might guard material is inserted and allowed to soften by heat until it sags by 1". Then close the top position of the machine slowly and gently, and allow the vacuum to form the heat softened material around the cast.

5) Use a no. 11 surgical blade in a bard-parker handle to trim in a smooth straight cut about 3-5 mm from the most apical portion of the gingival crest of the teeth facially and lingually. This excess material is removed first. Then remove the horseshoe shaped night guard from the cast.

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6) Trim the edges of the night guard to a smooth texture using a sharp, curved scissor until only about 2 mm of tissue (apically of gingival crest) is covered, being sure the night guard does not engage tissue undercuts. The night guard is completed and ready for delivery to the patient.

7) Insert the night guard into the patients mouth and evaluate it for adaptation, rough edges or blanching of tissue.

8) Further shortening (trimming) may be indicated in problem areas.

9) Evaluate the occlusion on the night guard with the patient in maximum intercuspation. If the patient is unable to obtain a comfortable occlusion due to premature posterior tooth contact, trim the night guard to exclude coverage of the terminal posterior teeth, as needed to allow optimal tooth contact in maximum intercuspation.

10) A 10% - 15% carbamide peroxide bleaching material is generally recommended for this bleaching technique. 10% carbamide peroxide degrades into 3% H2O2 and 7% urea. Bleaching materials containing carbopol are recommended because it thickens the bleaching solution and extends the oxidation process. To prolong the (carbopel carbamide peroxide), hydroxy gel is now added.

11) Instruct the patient in the application of the bleaching solution into the night guard. 2 or 3 drops of bleaching solution are placed onto the area of each tooth to be bleached in the night guard.

If either of two primary side effects occur is sensitivity of the teeth or irritated gingiva, the patient should reduce or discontinue treatment immediately, and contact the dentist so the cause of the problem can be determined.

It is recommended that only one arch should be bleached at a time, beginning with the maxillary arch. Bleaching the maxillary arch first allows the untreated mandibular arch to serve as a constant standard for comparison. Moreover, restricting the bleaching to one arch at a time reduces the potential for occlusal problems which could potentially occur if the thickness of two mouth guards were interposed simultaneously.

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Due to the difficulty in bleaching tetracycline-stained teeth, some clinicians advocated intentional RCT, with the use of a non-vital bleaching technique in order to overcome this problem. While the esthetic result appears much better than that obtained from external bleaching, this approach involves all the inherent risks otherwise associated with RCT.

Microabrasion and Macroabrasion:

Microabrasion and macroabrasion represent conservative alternatives for the reduction or elimination of superficial disolorations. As the terms imply, the stained areas or defects are abraded away. These techniques do result in the physical removal of tooth structure and therefore are indicated only for stains or enamel defects that do not extend beyond a few tenths of a millimeter in depth. If the defect or discoloration still remains after treatment with microabrasion or macroabrasion, a restorative alternative is indicated.

Microabrasion:

In 1984, McCloskey reported the use of 18% hydrochloric acid on teeth for the removal of superficial fluorosis stains and white spots where bleaching is not effective. Subsequently, in 1986, Croll modified the technique to include the use of pumice with HCl to form a paste applied with a tongue blade. This technique was called “microabrasion” and involved the surface dissolution of the enamel by the acid along with the abrasions of the pumice to remove superficial stains or defects. Since that time, Croll further modified the technique, reducing the concentration of the acid to 11% along with increasing the abrasiveness of the paste by using silicon carbide particles (in a water soluble gel paste) instead of pumice. This product is marketed as “Prema” compound (1990).

- Actually removes 22-27µm of enamel / application.

It should be emphasized that this technique involves the physical removal of tooth structure and does not remove stains or defects through any bleaching phenomenon.

1) Incipient caries is reversible if treated immediately. If however, the carious lesion has progressed to have a slightly roughened surface, microabrasion coupled with a remineralization program is an initial option, which if unsuccessful, can be followed by a restoration.

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2) The developmental discolored (opaque white / light brown) spot- microabrasion is successful if the defect is superficial (or 0.2 – 0.3 mm) if greater restoration is the treatment of choice.

Surface discoloration due to fluorosis also can be removed by microabrasion if the discoloration is within the 0.2 – 0.3 mm removal depth limit.

Procedure:

1) Apply rubber dam, protective glasses should be given to the patient to shield the eyes from any splatter.

2) The Prema paste in applied to the defective area of the tooth with a special rubber cup which has fluted edges.

3) For small localized idiopathic white or light brown areas, a hand application device is also available for use with the Prema compound.

4) Periodically, the paste is rinsed away to assess defect removal.

5) The treatment areas are polished with a fluoride containing prophypaste to restore surface lusture.

6) Immediately following treatment, a topical fluoride is applied to the teeth to enhance remineralization.

Macroabrasion:

An alternative technique for the removal of localized superficial white spots and other surface stains or defects is called “macroabrasion”. It simply utilizes a 12 fluted composite finishing bur or micron finishing diamond in a high-speed handpiece to remove the defect. Care must be taken to use light intermittent pressure and to carefully monitor removal of tooth structure in order to avoid irreversible damage to the tooth.

Following removal of the defect or upon termination of any further removal of tooth structure, a 30 fluted composite finishing bur is used to remove any factor or striations created by the previous instruments. Final polishing is accomplished with an abrasive rubber point.

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Microabrasion Macroabrasion

- Ensures better control of the removal of tooth structure

- Recommended over macroabrasion for the treatment of superficial defects

- High speed instrumentation.

- Is technique – sensitive to operator ability.

- Is faster and does not require the use of a rubber dam

- Defect removal is easier

Cosmetic recontouring (DCNA, 1993)

- Can be used to reshape enamel, smooth incisal edges, round incisal edges, open embrasures, reduce prominent surfaces or change line angles.

- It is easily accomplished by lightly reducing enamel at moderate speed with a small flame – shaped medium diamond followed by an 8 or 12 fluted carbide bur.

Veneers:

A veneer is a layer of tooth colored material that is applied to a tooth for esthetically restoring localized or generalized defects or intrinsic discolorations.

Indications for veneers

- Tetracycline discoloration

- Flurosis discoloration

- Teeth darkened by age

- Irregular tooth positioning in the arch

- Malformed teeth

- Teeth discolored by endodontic procedures

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- Teeth with numerous visible cracks

- Teeth with numerous unsightly restorations

- Teeth denuded of superficial structure by acid demineralization.

Contraindications for veneers

- Heavy occlusion

- Teeth in severe labial version (“buck teeth”)

- Mouth breathers

- Poor oral hygiene

- Denuded dentin

- High fluoridated (fluorosed) teeth

Typically veneers are made of :

- Chairside composite,

- Processed composite

- Porcelain

- Cast ceramic materials.

According to DCNA, 1985, the current generation of materials and concepts for veneers to teeth can be divided into three categories

1) Free hand placed, composite or microfill

2) Laminate pre-formed

3) Laboratory formed, acrylic resin, microfill resin or porcelain

Types:

- Partial

- Complete

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Partial veneers are indicated for the restoration of localized defects areas of intrinsic discolorations.

Full veneers are indicated for the restorations of generalized defects or areas of intensive staining involving the majority of the facial surface of the tooth.

However, several important factors including patient age, teeth position and alignment, occlusion, tissue health, and oral hygiene must be evaluated prior to pursuing full veneers. Furthermore, if full veneers are done, care must be taken to provide proper physiological contours, particularly in the gingival area, to favor good gingival health.

Full veneers

- Direct technique

- Indirect technique

Direct technique: done when a small number of teeth are involved or when the entire facial surface is not faulty (partial veneers). Directly applied composite veneers can be completed for the patient in one appointment with chairside composite. Placing direct composite full veneers is very time consuming and labor intensive. However, for cases involving young children, a single discolored teeth or where economics or patient time are limited precluding a laboratory fabricated veneer, the direct technique is a viable option.

Indirect veneers require two appointment but offer more advantages over directly placed full veneers.

a) First, indirectly placed veneers are much less technique sensitive to operator ability. Considerable artistic expertise and attention to detail are required to consistently achieve esthetic and physiologically sound direct veneers. Indirect veneers are made by lab technician and are typically more esthetic.

b) Second, if multiple teeth are to be veneered, indirect veneers usually can be placed much more expeditiously.

c) Third, indirect veneers typically will last much longer than a direct veneer, especially if made of porcelain or cast ceramic.

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Direct: Some controversy exists regarding the extent of tooth preparation that is necessary and the amount of coverage for veneers. Some operators prefer to etch the existing enamel and apply the veneer over the entire existing facial surface without any tooth preparation. The perceived advantage of this method is that in case of failure or in the event the patient does not like the veneer, it can be removed, thus being reversible. However, several significant problems exist with this approach. In order to achieve an esthetic results the facial surface of such a restoration must be overcontoured, thus appearing and feeling unnatural. An overcontoured veneer frequently results in gingival irritation with accompanying hyperemia and bleeding due to bulbous and impinging gingival contours. The veneers is more likely to be dislodged when no tooth structure is removed before etching and bonding procedures. If the veneer is lost it can be replaced, but the patient may live in constant fear that it will happen again, possibly creating a embarrassing situation. The reversibility of these veneers may seem desirable and appealing to patients from a psychological standpoint, however, few patients who had to have veneers wish to return to the original condition. Also, removing full veneers with no damage to the underlying unprepared teeth is exceedingly difficult if not impossible. To consistently achieve esthetic and physiologically sound results, an intra enamel preparation is almost always indicated. The only exception is in cases where the facial aspect of the tooth is significantly under contoured due to severe abrasion or erosion. In these cases more roughening of the involved enamel and defining of the peripheral margins are indicated.

Intraenamel preparation (or the roughening of the surface in under contoured areas) before placing a veneer is strongly recommended for the following reasons:

1) To provide space for opaque, tinting, bonding and / or veneering materials for maximal esthetics without overcontounting

2) To remove the outer fluoride-rich layer of enamel which may be more resistant to acid etching.

3) To create a rough surface for improved bonding.

4) To establish a definite finish line.

Another controversy involves the location of the gingival margin of the veneer. Should it terminate short of the free gingival crest, at the level of the gingival crest, or apical to the gingival crest?

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The answer depends on the individual situation. If the defect or discoloration does not extend subgingivally, then the margin of the veneer should not extend subgingivally.

The only logical reason for extending the margin subgingivally, is if the area is carious or defective, warranting restoration, or if the area involves significantly dark discoloration that presents a difficult esthetic problem. Recall that no restorative material is as good as normal tooth structure, and the gingival tissue is never as healthy when it is in contact with an artificial material.

Two basic preparation designs exists for full veneers

1) A “Window” preparation and 2) an “incisal overlapping” preparation.

Window preparation is recommended for most direct and indirect composite veneer. This intraenamel preparation design preserves the functional lingual and incisal surfaces of the maxillary anterior teeth, protecting the veneers from significantly occlusal stress.

By using a “window” preparation, the functional surfaces are better preserved in enamel. Their design reduces the potential for accelerated wear of the opposing tooth.

Incisal lapping: preparation is indicated when the tooth being veneered needs lengthening or when an incisal defect warrents restoration. Additionally, the incisal lapping design is frequently used with porcelain veneers, because it not only facilitates accurate seating of the veneer upon cementation, but also allows for improved esthetics along the incisal edge.

Direct veneer techniques:

Partial

Full

1) Direct partial veneers: Small localized intrinsic defects or discolorations are ideally treated with direct partial veneers.

Steps:

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1) Cleaning, shade selection and isolation with cotton rolls or rubber dam.

2) The outline is dictated solely by the extent of the defect and should include all the discolored area.

3) Use a coarse elliptical or round diamond instrument with air water coolant to prepare the cavity generally to a depth of about 0.5 – 0.75 mm.

4) Usually it is not necessary to remove all the discolored enamel in a pulpal direction, however, the preparation must be extended peripherally to sound, unaffected enamel.

5) Use an opaquing agent for masking dark stain.

6) If the entire defect or stain is removal then a microfill composite is recommended for restoring the cavity.

If a residual lightly stained area or white spot remains in enamel, an intensively less translucent composite can be used rather than extending the preparation into dentin to eliminate the defect.

Steps:

The “window” preparation is typically made to a depth roughly equivalent to half the thickness of the facial enamel ranging from ~ 0.5 – 0.75 mm midfacially and tapering down to a depth of about 0.2 – 0.5 mm along the gingival margin, depending on the thickness of enamel.

The preparation for a direct veneer normally is terminated just facial to the proximal contact except in the area of a diastema. To correct the diastema, the preparations are extended from the facial and the mesial surfaces, terminating at the mesiolingual line angles. If the discoloration are not involving the incisal edges, then it is not involved in the preparation. Also, preservation of the incisal edges better protects the veneers from heavy functional forces as noted earlier for “window” preparations.

The teeth should be restored one at a time. After etching rinsing and drying procedures apply and polymerize the resin bonding agent. Place the composite on the tooth in increments, especially along the gingival margin to reduce the effects of polymerization shrinkage. After the first veneer is finished, restore the second tooth in a similar manner. During a second

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appointment the remaining four anterior teeth are restored with direct composite veneers.

In case of dark tetracycline stained teeth with the discoloration extending subgingivally, the finish line is placed subgingivally.

Indirect veneer technique:

Drawbacks of direct veneering

1) Preparation, insertion and finishing of several direct veneers at one time is too difficult, fatiguing and time consuming. Some patients become uncomfortable and restless during long appointments.

2) Veneer shades and contour can be better controlled when made outside (Indirect) of the mouth on a cast than direct technique.

Indirect veneers include those made of:

1) Processed composite

2) Feldspathic porcelain

3) Cast ceramic

Because of superior strength, durability and esthetics, feldspathic porcelain is by far the most popular material for indirect veneering techniques used by dentist. Cast ceramic veneers offer comparable qualities, but require exacting laboratory technique and allow only limited chairside finishing and alteration of contour; however excellent laboratory support and the superb marginal fit of these veneers can minimize or eliminate this disadvantage. Although 2 appointments are required for indirect veneers, chair time is saved because much of the work is done in the laboratory. Excellent result can be obtained when proper clinical evaluation and careful operating procedures are followed. Indirect veneers are attached to the enamel by acid etching and bonding with either a self cured, light cured or dual cured resin bonding material.

1) Processed composite veneers:

Composite veneers are processed in a lab to achieve superior properties, using intense light, heat, vacuum, pressure or a combination of

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these. Cured composite can be produced which possess improved physical and mechanical properties compared to traditional chairside composites. Additionally, indirectly fabricated composite veneers offer superior shading.

Because their composition is similar to chairside composite, indirect composite veneer are capable of being bonded to the tooth with a resin bonding medium.

After acid etching, a bonding agent is applied to the etched enamel as with any composite restoration. A fluid resin bonding medium then is used to bond the veneer in place.

A newly developed processed composite of the hybrid type, filled with barium glass and colloidal silica, offers a significant increase in bond strength. Because barium glass is a relatively soft radiopaque filler, it can be sandblasted and etched in the lab with 9 – 10% of hydrofluoric acid to produce numerous areas of microscopic undercuts, similar to the phenomenon that occurs when enamel is etched.

Etched composite veneers.

Processed composite veneers are easily finished and polished. They also can be replaced and repaired easily with chairside composite. Veneers are often recommended for placement in children and adolescents as interim restorations until the teeth have fully erupted and achieved their complete clinical crown length.

Indirect processed composite veneers are indicated for placement in patient who exhibit significant wear of their anterior teeth due to occlusal stress. There offer esthetic affordable alternative to more costly porcelain or castable ceramic types when economics is the primary consideration.

Etched porcelain veneers:

The most frequently used indirect veneer type is the etched porcelain (feldspathic) veneer. Porcelain veneers etched with hydrofluoric acid are capable of achieving high bond strength to the etched enamel via a resin bonding medium.

Advantages:

The etched porcelain veneers are

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- Highly esthetic

- Stain resistant

- Periodontally compatible

- Appear to significantly outlast composite veneers.

Indication:

Generalized discoloration of the anterior teeth along with facial and incisal hypoplastic defects; a midline diastema will be closed as well when porcelain veneer are replaced.

Incisal lapping preparation design is generally used for porcelain veneers, especially if incisal defects warrant inclusion or the teeth need lengthening.

The only difference in the procedure of bonding is the need to condition the internal surface of each veneer with a silane primer just prior to applying the resin bonding agent. The silane acts as a coupling agent enabling a chemical bond to occur between the porcelain and the resin. It also improves wettability of the porcelain. The primary source of retention still remains the etched porcelain surface. Only a modest increase in bond strength results from silanization of the porcelain but is nonetheless recommended.

Darkly discolored teeth are more difficult to treat with porcelain veneers.

However, several modifications in the veneering technique can be used to enhance the final esthetic result.

a) Opaque porcelain is incorporated in the fabrication of the veneers in order to induce more inherent masking (5-15% opaque porcelain).

b) A slightly deeper cavity preparation can be used to allow greater veneer thickness. However, the preparation should always be restricted to enamel to ensure optimal bonding of the veneer of the tooth.

Castable ceramic veneers:

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Another esthetic alternative for veneering teeth is the use of castable ceramics such as Dicor. Unlike etched porcelain veneers which are fabricated by stacking and firing feldspathic porcelain, castable ceramic veneers are literally cast using a lost wax technique. The castable Dicor veneer material itself is grayish in shade and very translucent.

Low fusing feldspathic shading porcelain fired onto the surface of the veneer provide the final coloration. Excellent esthetics and possible resin castable ceramic materials for most cases involving mild to moderate discoloration. However, due to the limited amount of intrinsic opaquing possible with castable ceramic veneers, dark discoloration are best treated with porcelain veneers.

The margins of castable ceramic veneers cannot be contoured and finished with rotary instrumentation.

Since shading of castable ceramic veneers is accomplished by surface coloration, the use of rotary instrumentation on the veneer surface would result in loss of their coloration revealing an unesthetic grayish appearance.

Veneers for existing metal restorations:

Occasionally the facial portion of an existing metal restoration (amalgam and gold) is judged to be distracting. A careful examination including a radiograph is required to determine that the existing restoration is sound before an esthetic correlation is made. The size of the offensive area determines the extent of the preparation.

A no. 2 carbide bur rotating at high speed with air water coolant is used to remove the metal and starting at a point midway between the gingival and occlusal margins. The preparation is made perpendicular to the surface 1 mm deep at a minimum leaving a butt joint at the cavosurface margins. The 1mm depth and a but joint should be maintained as the preparation is extended occlusally. All the metal along the facial enamel is removed and the preparation is extended into the facial and occlusal embrasures just enough for the veneer to hide the metal. The contact areas on the proximal or occlusal surface must not be included in the preparation. To complete the outline from, the preparation is extended gingivally 1mm past the mark indicating the clinical level of the gingival tissue.

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After it is etched, rinsed and dried, the cavity preparation is complete. New adhesive resin liners containing a chemical called 4-META capable of bonding composite to metal, also may be used but are quite technique sensitive. Manufacturer’s instructions should be followed explicitly to ensure optimal results with these materials. The composite material is inserted and finished in the usual manner.

Repair of Veneers

Failures of esthetic veneers occur because of breakage, discoloration or wear. Consideration should be given to conservative repair of veneers if examination reveals that the remaining tooth and restoration are sound. It is not always necessary to remove all of the old restoration. The material most commonly used for making repairs is light-cured composite.

Veneers on tooth structure

Small chipped areas on veneers can often be corrected by recontouring and polishing. When a sizable area is broken; it can usually be repaired if the remaining portion is sound.

For direct composite veneers repair ideally should be made with the same material that was used originally. The operator should roughen the damaged surface of the veneer and / or tooth to a cavosurface margin. For more positive retention mechanical locks may be placed in the remaining composite material with a small round bur. An etching solution is applied to clean the prepared area which is then rinsed and dried. A resin bonding agent is applied to the preparation and polymerized. Chairside composite material is then added, cured and finished in the usual manner.

Indirect processed composite veneers are repaired in a similar manner. However, in order to repair porcelain veneers, a mild hydrofluoric acid preparation, suitable for intraoral use, must be used to etch the fractured porcelain, acid is applied washed and dried. A slightly frosted appearance, similar to that of etched enamel should be seen if the porcelain has been properly etched. A silane coupling agent may be applied to the etched porcelain surface prior to the application of the resin bonding agent. Chairside composite material is then added, cured, and finished in the usual manner. Large fractures are best treated by replacing the entire porcelain veneers.

Conclusion:

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Many a times, discoloration of the anterior teeth is the prime reason that brings the patient to dental clinic for aesthetic correction. Using the above mentioned techniques, we can do the needful for the patient. But these techniques are not able to achieve the natural tooth esthetic qualities. So patient should be informed about this prior to the treatment itself. Every effort should be made to learn and deliver proper esthetic techniques for discolored anterior teeth cases.

References

- Sturdevant.

- Grossman (Xth and / XIth Edition).

- Cohen (6th Edition).

- Weine.

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TREATMENT OF DISCOLORED TEETH

CONTENTS

Introduction

Types of Stains

- Intrinsic

- Extrinsic

Treatment

- Bleaching

o Vital

o Non vital

- Microabrasion

- Macroabrasion

- Veneers

Partial

Full

- Preparation

- Direct and Indirect techniques

- Etched porcelain veneers

- Castable ceramic veneers

- Veneers for metal restoration

- Repair of veneers

Conclusion

Reference

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