Dental dyschromia and whitening techniques
Introduction :
Discoloration of the anterior teeth can be a serious aesthetic problem. The solution to this problem is tooth whitening, the success of this whitening depends on the nature of the discoloration.
- Dyschromias
- Definition: A tooth is discolored if its color deviates from its original color.
2.2. Coloring mechanisms: teeth have a color palette around a “white-yellowish” base. These chromatic variations are due to many factors:
- Hereditary.
- Exchanges with the oral environment.
- Exchanges with the internal environment “blood”.
2.3. Extrinsic dyschromias: mainly due to staining of dental surfaces.
HATTAB classification
1- Brown colorations: they are mainly due to tannin deposits contained in coffee, tea, wine
2- Tobacco coloring: from brown to dark brown
3- Black colorations: very adherent, located at the necks, they are due to a chromogenic bacteria (Actinomyces)
4- Green colorations: these are thick, adherent deposits located on the vestibular surfaces at the level of the necks of the anterior teeth. They are due to a fluorescent bacteria or fungi
5- Orange colorations: they are due to the action of a chromogenic bacteria (Flavobaterium
lutescens) . They are located at the level of the cervical third of the anterior teeth and particularly on the vestibular faces
6- Metallic colorations: they are due to certain medications, products applied locally or even metal dust. Depending on the metal in question, the coloration may be of color:
-black with silver or iron,
-gray with mercury,
-green with copper.
These metallic colorations are extremely difficult to remove by chemical treatments;
7- Coloring due to antiseptics: (brown): the best known is that due to chlorhexidine, present in many mouthwashes, toothpastes, varnishes, etc.
- Intrinsic dyschromias: due to the passage and transformation of pigments in the dentinal tubules. Can affect the different tissues of the tooth and this, during the different ages of life. They can be classified into three main categories: genetic, prenatal and postnatal.
2.4.1. Discolorations due to hereditary disorders
* Amelogenesis imperfecta
– Colors vary from opaque white to yellow; they tend to darken with age.
* Dentinogenesis imperfecta
– Colors vary from light blue to dark brown.
2-4-1-2- Pre-eruptive intrinsic colorations
* Fluorosis
Dental fluorosis is characterized by hypermineralization of surfaces or enamel porosity induced by chronic ingestion of excessive amounts of fluoride during enamel formation.
* DEAN index
Index I : white, opaque, chalky spots.
Index II : more extensive white spots with some light brown spots.
Index III : more extensive brown spots with a few additional brown spots.
Index IV : brown spots only.
Index V : completely decayed enamel taking on the appearance of true caries without dentin softening.
*FEINMAN Index
- Simple fluorosis
- Opaque Fluorosis
- Fluorescence with porosity
Lightening is indicated for simple and opaque shapes.
*Dyschromias due to tetracyclines
Dyschromias are due to a chelation phenomenon between the antibiotic and the calcium of the hydroxyapatite crystals resulting in the formation of a tetracycline-calcium orthophosphate complex.
- Classification of JORDAN AND BOKSMAN (1984)
*Grade I: slight yellow, brown, or gray coloration, it extends evenly over the entire crown.
*Grade II: darker or gray, and the coloring is more extensive, but uniform and without bands.
*Grade III: this is a dark gray or blue coloration, generally with more pronounced bands.
*Grade IV: coloring too intense.
*Intrinsic colorations due to hemolytic disorders in the newborn
– Erythroblastosis fetalis and neonatal jaundice (yellow-green coloration)
-Congenital erythropoietic porphyria (pink coloration).
2-4-1-3- Post-eruptive intrinsic colorations
* Post-traumatic staining
*Degradation of hemoglobin
| Hemoglobin degradation products | Respective tint |
| Iron (iron sulfide) | Black |
| Methemoglobin | Red brown |
| Hemine | Blue black |
| Hematin | Dark brown |
| Hematoidin | Red |
*Pathological and traumatic colorings
– Pulp mortification can result in discoloration ranging from gray to black.
- Tooth whitening
- Definition
It is a therapy that allows the elimination and/or lightening of the colorations that are deposited on the teeth over time as well as the intrinsic dyschromias while preserving their natural color.
3-2- Principles of action of lightening products and chemical mechanisms of discoloration
Whitening of permanent teeth is done using bleaching agents which are chlorinated or oxygenated substances that will release nascent oxygen.
This nascent oxygen is in the atomic state O and not in the molecular state O2. In this case, its oxidizing properties are considerably more active.
Tooth whitening processes use the principles of a chemical oxidation-reduction reaction between the coloring substance (the reducing agent) and the bleaching molecule (the oxidizing agent).
Nascent oxygen must be able to penetrate into the mineralized dental tissues, without altering them, to release the pigments responsible for the coloring.
There is diffusion in the organic enamel-dentine matrix, reaction with organic molecules, ctd release and dissociation of pigments and modification of the long colored molecular chains, fragmented into small lighter molecules, the insoluble coloring substance transforms into a soluble coloring substance capable of being eliminated subsequently.
Dental dyschromia and whitening techniques
3.3. Different types of products
Currently, the most commonly used lightening agents are:
3-3-1- Hydrogen peroxide or oxygenated water (H 2 O 2 )
– It is the main agent used in teeth whitening.
- Due to its low molecular weight, it diffuses through the enamel organic matrix and dentinal tubules.
- It acts on the organic substance by releasing nascent O2 which diffuses easily and can fragment the colored components.
Hydrogen peroxide decomposes in light and heat, releasing oxygen according to the following reaction:
nH2O2 ——— n H2O + n/2O2
The nascent oxygen transforms the pigment molecule by oxidation reaction and thus modifies the color, or changes it.
3-3-2- Carbamide peroxide or urea peroxide CH 6 N 2 O 3
– Most often comes in the form of a gel;
– In an aqueous solution, 10% carbamide peroxide slowly decomposes into H2O2 and urea which in turn will give carbon dioxide and ammonia;
-A 10% carbamide peroxide decomposes into 3% hydrogen peroxide and 7% urea.
– The active principle remains the release of free oxygen radicals.
– Concentrations of 10-15% are used in outpatient settings while those of 35% are reserved for chairside techniques.
3-3-3- Sodium perborate
Sodium perborate is a powerful oxidant, which gives complete satisfaction.
Moreover, it does not cause any adverse effects if it comes into contact with soft tissues.
However, due to its easy decomposition by water, perborate should be stored in dry, tightly closed containers.
In fact, in the presence of water, it decomposes, forming a metaborate and hydrogen peroxide.
BO3Na + H2O ————BO2Na + H2O2
Spasser used sodium perborate mixed with water as an outpatient technique.
Nutting and Poe later proposed the use of a paste mixture of sodium perborate and 30% hydrogen peroxide (a product sold in the USA under the name superoxol).
This preparation is used for outpatient bleaching using a tray.
3-4- The adjuvants of a lightening product
- Thickening agent (carbopol): keeps the gel in contact with the dental structure for as long as possible.
- Urea: Stabilizes H2O2 and raises the pH of the solution;
- Glycerin: Increases the viscosity of the preparation and facilitates handling;
- Stabilizing Agent: Increases the shelf life of lightening products;
- A coloring; To make the product more enjoyable.
- Desensitizing agent;
- Preservative agent;
- Scented solution:
Activation of lightening products
- Thermal. heat sources devices equipped with an insert heated to the desired temperature, heated rammers or thermocauteries
- bright. 250 W boosted infrared lamp, ultraviolet lamp
- Chemical catalysts which potentiate the reaction by directly affecting its speed.
- Laser: frequency 30Hz, energy 60mj, distance 1 to 1.5mm, duration 3sec.
3-5. INDICATIONS:
- Hereditary dyschromias.
- Discolorations due to aging, lead poisoning.
- Post-traumatic dyschromia.
- Dyschromia due to fluorosis.
- Discolorations due to taking tetracycline.
- Discolorations due to pulp mortifications
3.6. CONTRAINDICATIONS:
- Formal
- Dentin hypersensitivity.
- Coronal and/or root dentin denudation
- Teeth with significant tissue damage, fractures and cracks.
- During orthodontic treatment.
- All dyschromias induced by inorganic pigments.
- Relatives
- Pregnant or breastfeeding women.
- Known sensitivities to the active ingredient used.
- Very young patients.
- Teeth with major restorations.
3.6. Preoperative measures
Regardless of the technique used, preoperative measurements must be taken to avoid possible setbacks.
- Clinical, radiological and prophylactic examinations.
- Detect contraindicated clinical situations.
- Diagnose the etiology of dyschromia.
- Decide on the method and choice of product to use.
- Defining objectives.
3.7. Clarification methods
3.7.1. On living teeth (externally)
-In the armchair
-Ambulatory
-Mixed
3.7.1.1. In-chair whitening (vital teeth)
a) Principle
The technique consists of applying 35% hydrogen peroxide directly to vital teeth after protecting the gum tissues and regular renewal depending on the presence or absence of chemical activators or the use of photopolymerization light.
b) Clinical stage
-Patient preparation and education session
1- Photograph all of the teeth.
2- Evaluate the shade of the teeth.
3- Polish the teeth with pumice powder + water,
4- Installation of a spacer.
5- Apply Vaseline to the inner and outer sides of the lips.
6- Apply the protective gel following the gingival scallop, and polymerize with the photopolymerization lamp,
7- Moisten the teeth.
8- Application of the product in a thick layer on all the teeth to be treated:
9- polymerization
10- Cleaning dental surfaces
11- Reapplication of the gel 2nd and 3rd time
12- Remove the gel and ask the patient to rinse. It is important to stop the procedure if sensitivity appears.
13- Remove the dam
The duration of treatment per session is between 20 and 30 minutes depending on the product. Application of a fluoride agent for 5 minutes to reduce sensitivity
c) Advantages of the technique
- Treatment carried out under the supervision of the practitioner
- Immediate observation of the result obtained
- Good protection of soft tissues
- Minimum product ingestion
- Reduction of processing time
D) Disadvantages
- High cost price
- Dentin hypersensitivity
3.7.1.2. Outpatient whitening of vital teeth or home bleaching.
Dental dyschromia and whitening techniques
a) Principle
This method consists of maintaining the whitening agent “carbamide peroxide at low concentrations (10 to 16%)” in contact with the teeth for a long period of 2 to 3 weeks by means of thermoformed flexible polyvinyl trays.
The patient himself places the splint which he wears either at night only for 8 hours or twice a day, respecting a rest period of 4 to 5 hours.
The wear is done until the desired lightening is obtained, always under the supervision of the dental surgeon.
b) Technique
It is based on the creation of a thermoformed gutter with vestibular reservoirs and adapted to the teeth and on the patient’s training.
*First session
- Clinical
1- Preoperative measures “Scaling and polishing”
2- Taking a fingerprint
- Laboratory
Preparation of the models; the molding is poured without a base and treated to allow maximum suction during thermoforming; the cervical areas are cleaned and lightly marked with a scalpel for better adaptation.
Creation of the spacer reservoirs; they must be kept at a distance under the free edge on the vestibular side, deposit a layer of resin of 0.5 mm, the untreated teeth do not have a reservoir
3- Making gutters 0.7 to 1 mm thick
4- Thermoforming
4- Cutting and adjusting the gutters after complete cooling to avoid deformations
*Second session
5- Trying the gutter in the mouth; maximum adaptation at the marginal level
6- Putting in the mouth after filling it with the whitening product Elimination of excess
7- Application time of 6 to 8 hours per night or 2 times/day with 5 hour intervals and one arch at a time
*3rd session
8- Control and evaluation of the results. After 24 hours to detect any soft tissue lesions, sensitivity or problems related to wearing the splint.
Treatment duration generally 2 to 3 weeks / arch
c) Advantages of the technique
- Ease of implementation
- Low concentration of the product used (carbamide peroxide 10 to 16%), therefore less risk:
- Reduced cost price.
Dental dyschromia and whitening techniques
d) Disadvantages:
- Possible soft tissue irritation
- Discomfort due to excessive ingestion of chemicals
- Possible occlusion disturbance
- The results are not immediate, so there is the possibility of over-treatment.
3.7.1 .3. The combined method
It consists of combining the two to obtain a faster result in the case of marked colorations. The chairside treatment can be carried out to start a lightening that will be continued by the outpatient technique or to accelerate it during each control visit.
3.7.1 .4. Adverse effects of whitening on pulped teeth:
3.7.1.4.1. Local risks.
- Dentin hypersensitivity
characterized by sharp pain to thermal, osmotic (sugar) or tactile stimuli. Generally, this sensitivity disappears when treatment is stopped. Desensitization can be accelerated by application of fluoride products.
- Effect of whitening products on dental tissues
A reduction in the hardness of enamel and dentin following the use of hydrogen peroxide has been observed. This is related to the decalcifying effect of the preparation used which has a pH of 3.
- Effects on the adhesion strength of composite resins to tooth hard tissues
The bonding of filling materials to teeth is reduced after bleaching, probably due to the presence of oxygen bubbles in the enamel.
- Effect of bleaching products on oral soft tissues
Some transient lesions of the gums, linked rather to the poor adaptation of the gutters than to the use of carbamide peroxide have been observed. Other side effects have been recorded: following the modification of the oral flora, hypertrophy of the lingual papillae is sometimes observed as well as superinfections by Candida albicans.
Dental dyschromia and whitening techniques
3.7.1.4.2. General risks:
During the first hour of wearing the splint, approximately 50% of the preparation is ingested by the patient. Nausea, dry mouth sensations, and peeling of the mucous membrane have been reported.
3.7.1.4.3. Mutagenic risks
The mutagenic risk of hydrogen peroxide has been raised based on some in vitro tests. However, based on in vivo tests, there does not appear to be any mutagenic risk when clinically useful concentrations are used.
Dental dyschromia and whitening techniques
3.7.1.5. How to deal with hypersensitivity
Symptomatic treatment is based on the application of desensitizing agents which are
- Caustic chemical agents
The caustic action causes coagulation in the protein component of the odontoblastic extensions and the intratubular dentinal fluid. This coagulation will seal the dentinal tubules (Glutaraldehyde, Formaldehyde).
- Chemical agents with mineralizing action
These products will cause demineralization of the mineral framework of the dentin, releasing calcium ions. These will interact with anions in solution from these products to form salt crystals inside the tubules.
The aim of this therapy is to obtain a reduction or even closure of the canaliculus by dentin sclerosis. Several products with mineralizing action are proposed:
(Fluorinated compounds, oxalate solutions, strontium chloride, sodium citrate).
Dental dyschromia and whitening techniques
- Chemical agents with neutralizing action
1. Potassium nitrate and chloride
The neutralizing action aims to block nerve activation and pain transmission by applying a chemical. Among the neutralizing agents used for the desensitization of nerve fibers, Potassium Nitrate and Potassium Chloride are the most used.
Application of potassium nitrate to dentin results in an increase in the concentration of K + ions inside the dentinal tubules.
This concentration of extracellular potassium ions causes depolarization of the nerve fibers and intense activation of these for a short period of time; subsequently, this phase of overexcitation is followed by a prolonged phase of deactivation of the nerve fibers.
3.8.2. Techniques for whitening devitalized teeth:
Prerequisites
1- Presence of coronal dental structures.
2- Three-dimensional waterproof canal obturation.
3.8.2.1. Walking bleaching technique
-Internally.
Operating mode.
- Ensure good quality of root canal treatment.
- Thorough cleaning of the cavity.
- Preparation of the pulp chamber.
- Remove the restorative materials closing access to the pulp cavity and retouch it.
- -Creation of a coronal-radicular access.
- Create a plug at the cervical level of the canal using glass ionomer in order to maintain the seal of the canal obturation.
- Application of the bleaching agent.
- The cavity is then sealed with zinc phosphate or CVI
- The lightening agent will be left in place for two to three weeks. Repeat the procedure until you achieve a satisfactory result.
- At the end of the lightening, place a dressing (calcium hydroxide + distilled water) for 15 days.
Internal/external bleaching technique
The internal/external bleaching technique combines intracoronal bleaching and extracoronal bleaching that the patient can do at home. This technique is both simple and effective.
Dental dyschromia and whitening techniques
Protocol
- Note the initial color of the devitalized tooth in the patient’s file.
- Clean the access cavity.
- Prepare an intracoronary barrier.
- Make a gutter
- Discharge the patient with the access cavity open with the following instructions:
- Remove the cotton ball from the access cavity.
- Using a syringe, apply the bleaching agent directly into the pulp chamber before inserting the tray.
- or apply the bleaching agent all over the tray and in excess where the devitalized tooth is located.
- After the whitening period, irrigate the devitalized tooth with a water syringe and place a new cotton ball in the cavity.
- Change the bleach solution every two hours, five to eight applications may be enough to achieve the desired color.
- Review the patient after three to seven days.
- Seal the access cavity with temporary restorative material.
38.2.2. Armchair technique
Thermocatalytic technique
It is the use of hydrogen peroxide, at high concentration, either 30 or 35% in the pulp chamber followed by application of heat by an electric heating device or a heated instrument.
Protocol
1- A protective cement barrier of at least 2 mm thickness is applied in the tooth canal.
2 – Then, a cotton ball soaked in hydrogen peroxide is inserted into the pulp chamber.
3 -Activation of the lightening agent with a heated instrument.
4 – Remove the heating instrument then the cotton.
5 – This sequence will be repeated four to six times.
6 – After removing the heat source, let the tooth rest for five minutes, then rinse it with lukewarm water for one minute.
7- The tooth must then be dried and a temporary filling made.
8- The patient will be reviewed and the operation repeated until satisfaction, where the cavity will be definitively closed.
“Photonic” technique
The preparation is identical to that described previously.
– The whitening product is a gel introduced into the cavity and applied to the vestibular surface of the tooth.
– The catalyst is a light.
Risks of whitening on non-vital teeth
1-Friability: Increased tooth friability following bleaching treatment is an important clinical side effect. 30% hydrogen peroxide has negative effects on biomechanical properties of dentin, such as tensile and shear forces. The mixture of sodium perborate and 30% hydrogen peroxide has less significant negative effects on these types of forces than 30% hydrogen peroxide alone.
2- Fracture: When a layer of dentin is removed from a tooth (during internal bleaching treatment), the tooth becomes weaker due to the decrease in the amount of tooth substance. Therefore, an increased risk of fracture can be expected when the tooth is already weakened by such loss of dental tissue.
3- External cervical resorption: External cervical resorption that occurs after an internal bleaching procedure is a serious, but rather rare, complication. Root resorption is usually asymptomatic and is normally detected only by routine X-ray.
4- Reduction of micro hardness.
5- Toxicity of the bleaching agent: hydrogen peroxide would have a potential for local carcinogenic induction, because the free radicals formed from hydrogen peroxide are capable of attacking DNA.
- Micro abrasion
3.1. Principle
-This technique aims to eliminate colorations of extrinsic or intrinsic origin limited to the superficial layers of the enamel.
-It involves the use of hydrochloric acid and pumice.
-By an abrasion phenomenon, the product will act on the teeth by removing a thickness of enamel of approximately 100 microns.
3.2. Implementation
1- Clinical examination and taking of initial photographs.
2- Prophylactic cleaning.
3- Setting up the operating field.
4 – Application of the acid-pumice mixture.
5 – Rinse.
6 – Assessment of the effectiveness of the application.
7 – Removal of the dam.
9- Rinsing.
10 – Fluoridation.
11 – Controls.
Dental dyschromia and whitening techniques
- Laser activated lightening
4.1. Protocol
1- Careful descaling and polishing;
2- Lip protection;
3- Installation of a photopolymerizable dam;
4- Application of a dark colored hydrogen peroxide gel;
5- Activation for 3 seconds;
6- Wait before renewing the gel and repeat 4 to 5 times according to the manufacturer’s recommendations .
Conclusion
Teeth whitening is a very effective therapeutic asset. It constitutes a real alternative to more invasive therapies and it allows to eliminate unsightly discolorations.
It therefore requires a thorough preliminary examination, the establishment of a clear diagnosis, as well as the establishment of a rigorous treatment plan.
Dental dyschromia and whitening techniques
Untreated cavities can damage the pulp.
Orthodontics aligns teeth and jaws.
Implants replace missing teeth permanently.
Dental floss removes debris between teeth.
A visit to the dentist every 6 months is recommended.
Fixed bridges replace one or more missing teeth.