DENTIN HYPERSENSITIVITY

Shweta Nimwal

BDS Intern

• Def: sharp, short pain arising from exposed dentin in response to stimuli typically thermal, chemical, tactile or osmotic and which cannot be ascribed to any other form of dental defect or pathology.(Holland et al,1997).

• It is not associated with actual tissue damage in the acute sense but can involve potential tissue damage with constant erosion of the enamel or cementum along with constant pulpal response.

• Dentin contains many thousands of microscopic tubular structures that radiate outwards from the pulp; these dentinal tubules are typically 0.5-2 microns in diameter.

HYPERSENSITIVITY

Ability to locate the source of pain is very good.Intensity is mild to moderate.Subsides after removal of the stimulus.

PULPAL PAIN

Very poor.

Intensity is severe, intermittent and throbbing.

May persist after the stimulus has been removed.

The Neurophysiology of teeth• The dental pulp is richly innervated.• Both myelinated and unmyelinated axons

innervate the pulp.• According to conduction velocities, the nerve

units can be classified into A group having conduction velocity >2m/s, and C group < 2m/s.

• The sharp better localized pain is mediated by A-delta fibers, whereas C fibers activation seems to be connected with the dull radiating pain sensation.

• MYELINATED A FIBER seems to be responsible for dentin sensitivity.

Two processes need to occur before the patient experiences dentin hypersensitivity: first, dentin must be exposed, and second, the dentin tubule must be patent to the pulp.

FactorsLoss of enamelDenudation of cementumGingival recessionAttritionAbrasionAbfraction

Etiology

Erosion (intrinsic and extrinsic)Tooth malpositionThinning, fenestration, absent buccal alveolar bone platePeriodontal disease and its treatmentPeriodontal surgeryPatient habits like traumatic tooth picking, excessive tooth cleaning.

MECHANISM OF DENTIN SENSITIVITY

THEORIES of dentin sensitivity:

1) Neural theory

2) Odontoblastic Transduction theory

3) Hydrodynamic theory

4) Modulation theory

1) NEURAL THOERYThis theory attributes activation to an initial

excitation of those nerves ending within the dentinal tubules.

These nerve signals are then conducted along the parent primary afferent nerve fibers in the pulp, into the dental nerve branches and then into the brain.

This theory considered that entire length of the tubule contains free nerve endings.

2)Odontoblastic transduction theory Assumed that odontoblast extended to the periphery of

the tubule. The stimuli initially excite the process or body of the

odontoblast. The membrane of odontoblasts may come into close apposition with that of nerve endings in the pulp or in the dentinal tubule, and the odontoblast transmits the excitation of these associated nerve endings.

But in 1984 Thomas indicated that the odontoblastic process is restricted to the inner third of the dentinal tubules. Accordingly it seems that the outer part of the tubule does not contain any cellular elements but is only filled with dentinal fluid.

3) The Hydrodynamic theory This is the most widely accepted theory, initially

proposed by Gysi in 1900 and subsequently validated scientifically by Brännström in 1966.

This theory proposes that a stimulus causes displacement of the fluid that exists in the dentinal tubules.

The displacement occurs in either an outward or inward direction, and this mechanical disturbance activates the nerve endings present in the dentin or pulp.

The sensations of hot and cold, for example, cause fluid to move in opposite directions.

• Heat causes expansion of the dentin tubule, evoking a relatively slow inward movement of fluid and is therefore not commonly identified as a significant pain stimulus.

• Cold causes contraction of the tubules resulting in a rapid outward flow, and is generally reported as the most problematic for sufferers.

• This movement distorts nerve fibers at the pulp-dentin border or within the dentin tubule, and is perceived as acute, immediate pain by the patient.

• The dehydration of dentin by air blasts or absorbent paper causes outward fluid movement and stimulates the mechanoreceptors of the odontoblasts, causing pain.

• Prolonged air blast causes formation of protein plug into the dentinal tubules, reducing the fluid movement and thus decreasing pain.

• The pain produced when sugar or salt solutions are placed in contact with exposed dentin is also due to dentinal fluid movement.

• Dentinal fluid is of relatively low osmolarity, which has a tendency to flow towards solution of higher osmolarity i.e., salt or sugar solution.

4) Modulation Theory

• Given by Kroeger in 1968.

• He implicated a number of polypeptides as regulators of neural transmission such as plasma kinins.

• These substances may selectively alter the permeability of the odontoblastic cell membrane, so that pulp neurons are more prone to discharge upon receipt of subsequent stimuli.

• Kroeger believed that plasma kinins were formed in the pulp when kallikinins were released as a result of nerve stimulation.

• Under normal circumstances, pulp tissue contains enzymes capable of inactivating plasma kinins.

Incidence and distribution of DH• Majority of sufferers aged 20–40.• Females more commonly affected than

males.• Buccal cervical zones are the most involved.• Canines and premolars are the most

frequently involved teeth.• In right handed tooth brushers DH is greater

on the left sided teeth and vice-versa.

Two main principle treatment options are-

1.Plug the dentin tubules preventing the fluid flow.

2.Desensitize the nerve, making it less responsive to stimulation.

TREATMENT

Treatment can be divided into-

1.Home care

2.In-office treament

3.Patient education

1) Home Care• Desensitizing dentifrice—This is

appropriate for mild to moderate hypersensitivity.

• The action of potassium nitrate (5%) is thought to penetrate through the dentinal tubules towards the pulp, depolarizing the nerve and preventing repolarization, thereby blocking pain transmission.

• Several desensitizing dentifrices contain both potassium nitrate alone or with fluoride which promotes tooth remineralization.

• 10% Strontium Chloride is commonly used in toothpastes such as Sensodyne and Thermodent.

• Sodium mono-fluorophosphates dentifrices are also effective in relieving the pain.

• The mode of action is linked to their ability to form mineralised deposits within the tubule lumen and on the surface of the exposed dentine that help prevent transmission of the applied stimulus.

• Desensitizing dentifrices generally require two to four weeks before sensitivity is reduced and discontinuation frequently results in a return of the sensitivity. Continued use is recommend to maintain desensitization benefits.

Mouthrinses

Some mouthrinses have an acidic pH and can dissolve the smear layer. Consequently, use of these products could present a risk factor for hypersensitivity, particularly for those with gingival recession and loss of tooth structure.It has been suggested that mouthwash use followed by brushing would enhance dissolution of the smear layer, exposing dentinal tubules.

Mouthrinses have been suggested as a vehicle for applying a desensitizing agent. A reduction in sensitivity has been demonstrated using a combined sequential rinse of chlorhexidine (0.12%) followed by a sodium fluoride (0.2%) rinse. Additionally, a 3% potassium nitrate/0.2% sodium fluoride mouthrinse appears to have a therapeutic effectiveness in alleviating dentin hypersensitivity.

2)In-Office treament

CAVITY VARNISHES- Open tubules can be covered with a thin film of varnish to provide relief. Eg. Copalite, duraflor.

• A 5% sodium fluoride varnish is an effective, convenient, and noninvasive method for desensitization.

• An advantage of this method is that teeth do not need to be dried prior to application and use of the air syringe, which can be painful, is not necessary.

• The varnish can be applied directly to the tooth with a brush or cotton pellet and sets on contact with the moisture of the oral cavity.

• CORTICOSTEROIDS- 1%prednisolone+ 25% para chloro phenol+ 25% + 50% gum camphor.

• BURNISHING OF DENTIN- Burnishing of dentin with a toothpick or orange wood stick results in the formation of a smear layer which, partially occludes the dentinal tubules and thus resulting in reduction in hypersensitivity.

IONTOPHORESIS-

• A term applied to the use of an electrical potential to transfer ions into the body for therapeutic purposes.

• Iontophoresis typically employs a low voltage charged electric current to drive a 2% sodium fluoride ion into the affected dentin.

• 40% FORMALIN can be topically applied by means of cotton pellets or orangewood sticks on teeth which helps in reducing DH.

• FLUORIDES—These are believed to act by precipitating fluoride ions at low concentrations to be available simultaneously with calcium and phosphate to produce fluorapatite or fluoridate hydroxyapatite.

• Fluoride actively enhances remineralization while fluoride precipitates are thought to occlude the dentin tubules.

• Topical applications of stannous fluoride applied in a tray or burnished into the tooth surface have been shown to control dentin hypersensitivity. It can also be prescribed for home use utilizing a brush-on or tray technique.

• OXALATE- Oxalate products reduce dentin permeability and occlude tubules.

• Potassium oxalate and ferric oxalate solution make available oxalate ions that can react with calcium ions in the dentinal fluid to form insoluble calcium oxalate crystals that are deposited in the tubules.

• CALCIUM COMPOUNDS- Calcium phosphate and calcium hydroxide are effective in treating DH.

DENTAL RESINS AND ADHESIVES-

• The objective is to seal the dentinal tubules to prevent pain producing stimuli to reach the pulp.

• GLUMA- a dentin bonding agent having gluteraldehyde primer and 35% HEMA provides attachment to dentin that is immediate and strong.

• GIC

LOW LEVEL LASERS:

• Low Level Lasers (LLL) have found to be very effective in treating hypersensitivity as it reduces pain and maintains the pain free status for prolonged time. Mechanism of action- it causes Biomodualtion producing two major effects:

1. Analgesic effect: produced by Direct radiation effect on the nerve fibers within in the pulp causing depression of impulse transmission by blockage of depolarization of afferent A delta and C fibers.

2. Physical effect: Modification of the tubular structure of dentine by melting and fusing of the hard tissue or smear layer causing narrowing or obliteration of the exposed tubular openings. Formation of secondary dentin by stimulation of odontoblasts and recrystallisation of the dentin exposed to laser is also evidently proved. •LLL group which includes CO2, Nd:YAG and Diode lasers namely HeliumNeon Diode and GalliumAluminumArsenide Diode and found to produce these effects efficiently.

Patient educationToothbrushing

Manual toothbrush— Use of a soft or ultra soft toothbrush with soft end rounded bristles lowers the risk of gingival recession and abrasion of exposed cementum and dentin.Power toothbrush— Less force or pressure on the teeth is needed when brushing with a powered toothbrush, since they require a light grasp and a minimal amount of pressure to remove plaque.

Brushing technique and sequence—The brushing sequence is best started in a nonsensitive. quadrant and ended within the most sensitive quadrant. Brushing strokes that are focused on one to two teeth should be used instead of long horizontal strokes reaching across several teeth.Use of nondominant hand—Use of the nondominant hand by an aggressive brusher forces attention to the toothbrushing task and increases awareness of the need to reduce the amount of pressure employed.Change grasp—It takes a conscious effort for a client to change from using a palm grasp when using the toothbrush. By increasing the awareness of brushing technique the individual can focus on brushing thoroughly but gently.

Dietary Modifications The consumption of acidic foods and drinks, such as

citrus fruits and juices, pickled foods, wine, ciders, fruit yogurt, and carbonated beverages should be controlled, since they can contribute to erosion of the enamel or cementum and expose underlying dentin.

Brushing immediately after ingesting acidic foods should also be avoided as it may accelerate the combined effects of abrasion and erosion.

Additionally, acidic food and drink, especially fruits and fruit drinks, dissolve the smear layer in a few minutes.

Erosion also causes dissolution of the smear layer increasing the patency of the tubules.

Additional recommendations can include sipping acidic beverages through a straw, reducing the quantity and frequency of acid intake, drinking something neutral or alkaline—such as milk or water—after consuming dietary acids, and avoiding foods that have sharp flavors, spices, or are extremely hot or cold.

Suggestions for professionals

✔ Avoid overinstrumenting the root surfaces during calculusremoval and scaling/root planing.✔ Avoid over-polishing exposed roots during stain removal.✔ Avoid violating the biologic width when placing crownmargins.✔ Consider use of trays to deliver anti-sensitivity agentsduring bleaching procedures or in chronic sensitivity.✔ Avoid placing subgingival restorative margins that mayretain plaque.✔ Review patient regularly for signs of erosion, abrasionand abfraction.

Advice for patients

✔ Practice good oral hygiene techniques.✔ Use only pea-sized amount of toothpaste.✔ Avoid hard-bristled toothbrushes.✔ Avoid brushing teeth immediately after consuming acidicfoods or drinks.✔ Avoid excessive flossing or incorrect use of otherinterproximal cleaning devices.✔ Avoid brushing with excessive pressure for prolonged periodsof time.✔ Avoid picking at the gums or using toothpicksinappropriately.

Thank you