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Dentin hypersesitivity
 

Dentin hypersesitivity

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    Dentin hypersesitivity Dentin hypersesitivity Presentation Transcript

    • DENTIN HYPERSENSITIVITY
    • INTODUCTIONDEFINITIONPREVALENCE AND DISTRIBUTIONAETIOLOGYPATHO-PHYIOLOGY THEORIES MECHANISMDIAGNOSIS AND EVALUATION OF PAINASSOICTED WITH DENTIN HYPERSENSITIVITYCLINICAL MANIFESTATIONS MANAGEMENTCERVICAL DENTIN HYPERSENSITIVITYBLEACHING AND HYPERSENSITIVITYCONCLUSION 2
    • INTRODUCTION•Tooth hypersensitivity is one of the oldest recordedcomplaints of discomfort to the patient. It is one of themost common painful dental conditions.•Dentin hypersensitivity is a common condition oftransient tooth pain caused by a variety of exogenousstimuli.• The exogenous stimuli include thermal (cold), tactile(touch), or osmotic changes (sweets or drying thesurface). 3
    • •The response to a stimulus varies from person toperson due to differences in pain tolerance,environmental factors, and emotional state.•The primary underlying clinical cause for dentinhypersensitivity is exposed dentinal tubules.•The only hypersensitivity not associated with thisetiology is the transient spontaneously resolvinghypersensitivity associated with the dentalbleaching process. 4
    • DEFINITION―Dentin Hypersensitivity is a condition characterized byshort , sharp pain arising from exposed dentin in responseto stimuli typically thermal , evaporative,tactile, osmoticor chemical and which cannot be ascribed to any otherform of dental defect or pathology‖. Holland et al 1997 5
    • Many other conditions exits where dentin is exposed and sensitivity ,identical to that experience with DH occurs• Chipped or fractured teeth• Caries• Marginal leakage of restorations• Cracked cusps of teeth• Palato-gingival groove. 6
    • PREVALENCE AND DISTRIBUTIONAgeis broad , spanning from early teenage to more than 70years. (Fischer et al 1992)however peak incidence is between 20-40 years. 7
    • Numerical gender differences have been reported inmales and females.Females tend to have more sensitivity than males. Thishas been attributed to their practicing better oral hygiene.Interestingly, the prevalence of cervical dentinesensitivity, another term used to describe dentinehypersensitivity, was found to be much higher inperiodontal patients, ranging between 72.5–98%. 8
    • Regarding the intra-oral distribution, dentinehypersensitivity is most commonly reported from thebuccal cervical zones of permanent teeth.Sites of predilection in descending order are canines andfirst premolars, incisors and second premolars and molars 9
    • ETIOLOGICAL ANDPREDISPOSING FACTORSThere are potentially numerous and varied etiological andpredisposing factors to dentine hypersensitivity.Certainly, no prime cause can be identified.By definition, dentine hypersensitivity may arise as aresult of loss of enamel and or root surface denudationdue to gingival recession with exposure of underlyingdentine. Enamel loss as a part of tooth wear may result fromattrition, abrasion,abfraction or erosion. 10
    • Attrition describes the wear of teeth due to direct contactbetween teeth. Attrition is associated with occlusal function and may beexaggerated by habits or parafunctional activitysuch as bruxism. 11
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    • Abrasion describes the wear of teeth caused by objectsother than another tooth, examples includetoothbrush/toothpaste abrasion and the variety of facetswhich can be caused by pipe smoking or other similarhabits.Typical toothbrush abrasion lesions are side dependent,for example being greater on the left-side in right-handed people.The buccal cervical area of the teeth are the sites ofpredilection. Furthermore, canines and premolars aremost affected because of their position within the dentalarch where they receive the most attention during tooth 13cleaning.
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    • Erosion is defined as the loss of hard dental tissue, due tochemical means which are non-bacterial.Erosion may be by either extrinsic or intrinsic acids. Extrinsic erosion can be subdivided into dietary andenvironmental, while intrinsic erosion is the result ofexposure of teeth to gastric juice.Dietary erosion may result from foods or drinkscontaining acids such as citrus fruits, pickled food, fruitjuices, carbonated drinks, wines and ciders. 17
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    • AbfractionAbfraction or cervical stress lesions has beenhypothesized as an etiological factor in tooth wear.The process is thought to involve eccentric occlusalloading leading to cusp flexure.This in turn leads to compressive and tensile stresses atthe cervical fulcrum area of the tooth with the resultantweakening of the cervical tooth structure .There is progressive disruption of the hydroxyapatitecrystals leading to dentin exposure. 20
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    • Gingival recessionGingival recession and subsequent root surface exposureallow more rapid and extensive exposure of dentinaltubules because the cementum layer overlying the rootsurface is thin and easily removed.Gingival recession, as with dentine hypersensitivity, hasbeen described as enigma, having what appears to be amultifactorial etiology. 23
    • Tooth brushing has long been implicated in gingivalrecession on buccal surfaces and is a frequent finding insubjects with a high standard of oral hygiene,or with ahistory of hard toothbrush use.Gingival recession is frequently cited to result fromperiodontal treatment particularly surgery as is dentinehypersensitivity. 24
    • Common Reasons for Gingival Recession1. Inadequate attached gingiva2. Prominent roots3. Toothbrush abrasion4. Pocket reduction periodontal surgery5. Oral habits resulting in gingival laceration, i.e.,traumatic tooth picking eating hard foods6. Excessive tooth cleaning7. Excessive flossing8. Gingival loss secondary to specific diseases, i.e., NUG,periodontitis, herpetic gingivo stomatitis9. Crown preparation 2510.Ageing
    • 26
    • Other related factors• Diet sensitivity. Generally associated with a low pH material, such as fresh tomatoes, orange juice, cola drinks.• Genetic sensitivity. Patients reporting history of sensitive teeth. It is not known whether sensitivity correlates to the 10 per cent of teeth that do not have cementum covering all the dentine at the DEJ, or is a factor of lower overall patient pain threshold values. 27
    • Restorative sensitivity Triggered following placement of a restoration for several possible reasons:• during setting; contamination of composites during placement or improper etching of the tooth, which results in micro-leakage• incorrect preparation of glass ionomer or zinc phosphate cements;• general pulpal insult from cavity preparation technique;• thermal or occlusal causes; galvanic reaction to dissimilar metals that creates a sudden shock or ‗tin foil‘ taste in the mouth. 28
    • Medication sensitivity• Due to medications that dry the mouth (e.g. antihistamines, high blood pressure medication),• thereby compromising the protective effects of saliva and aggravating diet-related trauma or proliferating plaque.• Even a reduction in salivary flow due to aging or medications can lower the pH of the saliva below the level at which caries occurs (6.0–6.8 for Dentine caries; < 5.5 for enamel caries) and increase erosive lesions to exposed dentine. 29
    • Bleaching sensitivity• Commonly associated with carbamide peroxide vital tooth bleaching and thought to be due to the by- products of 10 per cent carbamide peroxide (3 per cent hydrogen peroxide and 7 per cent urea) readily passing through the enamel and dentine into the pulp in a matter of minutes.• Sensitivity takes the form of a reversible pulpitis caused from the dentine fluid flow and pulpal contact of the material, which changes osmolarity, without apparent harm to the pulp. 30
    • • Sensitivity is caused by all other forms of bleaching (in-office, with or without light activation, and new, over-the-counter) and depends on peroxide concentration. 31
    • MECHANISM OF DENTINHYPERSENSITIVITY 32
    • INNERVATION OF DENTIN• Dentinal tubules contain numerous nerve endings in the predentin and inner dentin no further than 100 to 150 micrometer from the pulp.• Although most of the nerve bundles terminate in the sub-odontoblastic plexus as free unmyelinated nerve endings, a small number of axons pass between the odontoblast cell bodies to enter the dentinal tubules in close approximation to the odontoblast process. 33
    • 34
    • • No organized junction or synaptic relationship has been noted between axons and the odontoblast process. Intra tubular nerves characteristically contain neurofilaments, neurotubules, numerous mitochondria and many small vesicular structures.• Most of these small vesiculated endings are located in tubules in the coronal zone, specifically in the pulp horns. It is believed that most of these are terminal processes of the myelinated nerve fibers of the dental pulp. 35
    • The mechanism underlying dentin hypersensitivity havebeen the subject of keen interest in recent years.Converging evidence indicates that movement of fluid inthe dentinal tubules is the basic event in the arousal ofpain. It now appears that pain producing stimuli such as heat,cold, air blasts and probing with the tip of an explorerhave in common the ability to displace fluid in thetubules. 36
    • The thermal diffusibility of dentin is relatively low, yetthe response of the tooth to thermal stimulation is rapidoften less than a second. Evidence suggests that thermal stimulation of the toothresults in a rapid movement of fluid in the dentinaltubules that results in the deformation of the sensorynerve terminals in the underlying pulps . 37
    • Heat would expand the fluid within the tubules,causing it to flow towards the pulp whereas coldwould cause the fluid to contract producing anoutward flow.Presumably the rapid movement of fluid acrossthe cell membrane of the sensory receptor activatethe receptor. 38
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    • The dentinal tubule is a capillary tube having anexceedingly small diameter.Therefore the effects of capillarity are significant, as thenarrower the bore of a capillary tube, the greater the effectof capillarity.Thus if fluid is removed from the outer end of exposeddentinal tubules by dehydrating the dentinal surface withan air blast or absorbent paper, capillary force willproduce a rapid outward movement of fluid in the tubule. 41
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    • According to Braunstrom desiccation of dentin cantheoretically cause dentinal fluid to flow outward at a rateof 2 to 3 mm per second.In addition to air blasts, dehydrating solutionscontaining hyper osmotic concentrations and sucrose orcalcium chloride can produce pain if applied to exposeddentin. 43
    • Investigators have shown that it is the A fibresrather than the C fibres that are activated by stimuli suchas heat, cold and air blasts applied to exposed dentin.However if heat is applied long enough to increase thetemperature of the pulp-dentin border by several degreesCelsius the C-fibres may respond.It seems that the A fibres are only activated by a veryrapid displacement of the tubular contents.Slow heating of the tooth produced no response until thetemperature reached 43 C, at which time C fibres wereactivated presumably because of heat-induced injury tothe pulp. 44
    • The most different phenomenon to explain is painassociated with light probing of dentin.Even light pressure of an explorer tip can produce strongforces.These forces mechanically compress the openings of thetubules and cause sufficient displacement of fluid to excitethe sensory receptors in the indulging pulp. 45
    • THEORIES OF DENTINHYPERSENSITIVITY 46
    • Many theories explain dentinal hypersensitivityProposed theories are: Direct neural theory Odontoblasts receptor theory Transducer theoryGate control theory Fluid or Hydrodynamic theory 47
    • 1)DIRECT NEURAL THEORYThe dentin contains nerve endings that respond when it isstimulated.The pulp is well innervated, especially below theodontoblasts (the plexus of rack show)and that somenerves penetrate a short distance in to some tubules.Whether these intratubular nerves are involved in dentinsensitivity is not known.No evidence has been found for nerves in the outerdentin, which is most sensitive . 48
    • 2)ODONTOBLAST RECEPTOR THEORYThis mechanism explains dentin sensitivity considersthe odontoblasts to be a receptor cell. This attractiveconcept has been considered, abandoned andreconsidered for many reasons.It was once argued because the odontoblasts is of neuralcrest origin it retains an ability to transducer andpropagate an impulse what was missing was thedemonstration of a synaptic relation between theodontoblasts and the pulpal nerves. 49
    • 3)TRANSDUCER THEORYThis theory of dentinal sensation takes into considerationthe synaptic –like relationship between the terminal,sensory nerve endings and odontoblastic process.If a true synapse were present between these twoelements to facilitate the transmission of dentinalsensations,then a neural transmitting substance such asacetylcholine could be expected,but there no directevidence of its presence. 50
    • 4)GATE CONTROL THEORY ANDVIBRATIONWhen the dentin is irritated, for example, by cavitypreparation, all of the pulpal nerves become activated fromthe vibrations.The larger myelinated fibers may accommodate to thesensations. The smaller C- fibers may tend to bemaintained and not adjust to the stimulus.Thus, as the low-intensity pain gates from the larger fibersare closed, the high-intensity "pain gates" from the smallerfibers are enhanced. 51
    • "Pain gates" may be opened by some stimuli, such asanxiety, and may be closed by distracting stimuli such as"audio-analgesia" or gingival stimulation.However, the gate theory does little to explain how painresponses from the dentin are transmitted and perceivedby the nerve endings of the pulp-only how they may becentrally interpreted. 52
    • 6.)FLUID OR HYDRODYNAMIC THEORY:By BrannstromThis mechanism proposed to explain dentin sensitivityinvolves movement of fluid through the dentinal tubules. This "hydrodynamic theory" which fits much of theexperimental and morphological data proposes that fluidmovement through the dentinal tubule distorts the localpulpal environment and is sensed by the free nerveendings in the plexus of Raschkow. 53
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    • Thus, when dentin is first exposed, small blebs of fluidcan be seen on the cavity floor. When the cavity is driedwith the air or cotton wool, a greater loss of fluid isinduced, leading to more movement and a further painfulexperience.The increased sensitivity is at the dentino-enamel junctionis explained by profuse branching of tubules in thisregion.Interestingly stimuli, such as cold, which cause fluid flowaway from the pulp produce more rapid and greater pulpnerve responses than those, such as heat, which cause an 55inward flow.
    • This certainly would explain the rapid and severe responseto cold stimuli compared to the slow dull response to heat.The hydro dynamic hypothesis explains why pain isproduced by thermal change, mechanical probing,hypotonic solutions and dehydration. 56
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    • The pain producing stimuli can be thermal, tactile,osmotic, chemical or evaporative, but the cold stimulusappears to be the strongest and causes the greatest problemto those troubled by dentine hypersensitivity.WHY ALL EXPOSED DENTINE IS NOTSENSITIVE???Evidence from a scanning electron microscopicinvestigation of extracted teeth would suggest that thereare differences between ‗hypersensitive‘ and ‗non-sensitive‘ dentine in that there are more and wider opendentinal tubules in sensitive dentine. 58
    • Additionally, another scanning electron micro-scopestudy, based on replica models of hypersensitive and non-sensitive dentine, showed that, in hypersensitive dentine,the smear layer was thinner, different in structure andthan in non sensitive dentine. These findings appear consistent with the hydrodynamictheory.The greater number of open and wider tubules at thedentine surface would enhance fluid permeability throughdentine and as such increase the possibility for stimulustransmission and subsequent pain response. 59
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    • CLINICAL FEATURES.• Pain is only consistent symptom of dentin hypersensitivity.• However it is not known whether hypersensitive teeth lie at one extreme of a normal distribution of dentin sensitivity or they represent a separate population of teeth that are abnormally sensitive.• Not all areas of exposed dentin are sensitive and hypersensitive surfaces can vary in their sensitivity to different stimuli. 62
    • PRESENT AND FUTURE METHODSFOR ASSESSMENT AND EVALUATIONOF PAIN ASSOCIATED WITH DENTIN SENSITIVITY 63
    • Traditionally dentin hypersensitivity mainly evaluated onthe individual patients response to the stimulus.According to recent recommendations by Holland et al(1997), dentin hypersensitivity may be evaluated either interms of the stimulus intensity to evoke pain or responsebased methods.Stimulus based methods usually involve the measurementof a pain threshold; response based methods involve theestimation of pain severity . 64
    • The presenting stimuli can be grouped into fivecategories:•mechanical•chemical•electrical•evaporative•thermal. 65
    • OBJECTIVE EVALUATION:Mechanical (tactile) stimuli - explorer, constant pressure probe, Mechanical pressure stimulators, scaling Procedures. .Chemical (osmotic) stimuli - hypertonic solutions. e.g. sodium Chloride, glucose, sucrose, and calcium Chloride. 66
    • Electrical stimulation - electrical pulp testersEvaporative stimuli - cold air blast, air thermal system, air Jet stimulator,Thermal stimuli - electronic threshold measurement device, cold water testing, heat, Ethyl chloride, ice stick, thermo- electric Devices (e.g.: bio mat thermal probe). 67
    • SUBJECTIVE EVALUATION:VERBAL RATING SCALES:Keele 1948 described four point scale grading pain asslight, moderate, severe and agonizing.Verbal rating scales (VRS) offer a choice of words thatmay not represent pain experience with significantprecession for all patients. 68
    • SUBJECT EVALUATION TACTILE AND ORTHERMAL STIMULATION:a) simple binary pain scale pain -before treatment pain/nopain after treatment(Hansen 1992)b)0 - no discomfort .1 - Mild discomfort .2 - Marked discomfort3 - Marked discomfort that lasted 10 sec. (Gilliam andNewman1993) 69
    • VISUAL ANALOGUE SCALES:A visual analogue scale (V AS) is a line 10 cm in length,the extreme of the line representing the limits of pain apatient might experience from external stimulus.No pain at one end and most severe pain at the other end.Patients are asked to place a mark on the 10 cm linewhich indicates the intensity of their current level ofsensitivity or discomfort following application of stimuli.V AS can give only a one -dimensional assessment of painand as such cannot distinguish between the sensory,intensity and affective aspects of pain. 70
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    • AIR INDEXING METHODAn ―air indexing method‖ was developed in the late1970‘s to detect and quantify CDH. (In 2000, anintroduction of the technique was published byColeman et al.)The method was developed to diagnose CDH in amanner that minimizes thermal or evaporative stimulito sensitive teeth. 72
    • A minor puff of air from a standard air/water syringewas directed to the CEJ region at a 45-degree angle tothe long axis of a test tooth at a distance ofapproximately one-half centimeter for a duration of one-half to one second. A ―threshold patient response‖ was recorded as none(0), slight (1), moderate (2), or severe (3) for testzones of teethAn ―air index mapping‖ was obtained by patientresponses to the air stimulus beginning on the mostdistal upper right tooth, going toward the upper left,then mandibular left and so on for both buccal andlingual CEJ regions . 73
    • MANAGEMENT OF DENTINHYPERSENSITIVITY 74
    • When a patient presents with what appears to besensitive dentin, the initial diagnosis should eliminateany possible reasons such as decay, cracked tooth, orirreversible pulpitis that may mimic dentinhypersensitivity.The next appropriate step, once the problem has beenidentified as dentin hypersensitivity, is to identify thereason for the exposed dentinal tubules and to see if theetiology process causing the hypersensitivity can beeliminated. 75
    • The greatest clinical implication of dentinehypersensitivity is how the condition may be preventedeither from occurring or recurring, and this can only bedebated by considering the probable etiologic factors.Grossman has stated, ―The best treatment forhypersensitivity lies in its prevention.‖. 76
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    • Patient communicationFinally successful patient management relies heavily ongood communication skills which are of vital importancein dentistry because it improves the quality and amount ofinformation obtained from the patient, increases thelikelihood of patient compliance, decreases the patientanxiety and improves the probable outcome of treatment. 78
    • Clinical management:Often dentin hypersensitivity abates without treatment., This is probably related to the fact that dentin permeability can decrease spontaneously. This may be probably due to the natural process contributing by;• formation of reparative dentin by pulp.• obturation of the tubules by the formation of mineral deposits (Dentinal sclerosis)• Calculus formation on the surface of the dentin 79
    • There are essentially two basic approaches to thetreatment of dentin hypersensitivity1) Direct inhibition of sensory nerve activity2) Tubule occlusion 80
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    • •Criteria for the selection of desensitizing procedures•Provides immediate and lasting relief of pain•Easy to apply•It should be well tolerated by patients•It should not be injurious to the pulp.•It should not discolour the tooth.•It should be relatively inexpensive. 83
    • Two types of procedure for desensitizationI. IN OFFICE TREATMENT PROCEDURES: Evidence indicates that areas of hypersensitive dentin have significantly more open dentinal tubules compared with non-sensitive dentin and that these open tubules are patent throughout their length.This enables fluid to move freely between the oral environment and the pulp.It has also been established that exposed but sensitive areas of dentin have tubules that have become occluded.A rapid movement of fluid in the tubules is capable of activating intradental sensory nerves, therefore treatment should be directed toward reducing the functional diameter of the tubules to limit fluid movement. 84
    • Specific treatment modalitiesSome of the materials used for in-office treatment are•cavity varnishes•anti-inflammatory agents•treatments that partially obturate dentinal tubules. Burnishing of dentin silver nitrates zinc chloride-potassium Ferro cyanide Formalin 85
    • Calcium compound - Calcium hydroxide - Dibasic calcium phosphateFluoride compounds - -Sodium silica fluoride - Sodium fluoride - Stannous fluoride - Fluoride iontophoresis 86
    • –Strontium chloride–potassium oxalates Treatment agents that undergo setting or polymerization reactions•Glass ionomer cement•Dentin bonding agents•Restorative resinsand LasersPrior to treating sensitive tooth surfaces, hard or softdeposits should be removed from the teeth. The teethshould be isolated and dried with warm air. Most of the in-office treatment procedures are aimed atobturating the tubules. 87
    • 1.)Cavity varnishes:The varnish does temporarily occlude dentinal tubules butthe material is readily lost over time.Dentin often becomes insensitive when open tubules arecovered with a thin film of varnish.WyCoff advocated the use of cavity varnish such ascopalite.For more sustained relief, a fluoride containing varnish,Duraflor can be applied.The use of 5% sodium fluoride (NaF) in a thick varnishas a dentine desensitizer has been reported by Clark et al. 88(1985).
    • Duraphat 5% sodium fluoride varnish quick and easy application natural resin base pleasant taste adheres to dry or moist teeth sets in contact with saliva ask patient not to brush or floss for 3-4 hours. Candrink or eat a soft meal immediately. calcium fluoride can persist for weeks or months onthe tooth surface . 89
    • 2.)Corticosteroids:Mosteller reported that when a liner consisting of 1 %prednisalone in combination with 25 para-chlorophenol25% M-cresyl acetate and 50% gum camphor wasapplied to the walls of cavities, it was completelyeffective in preventing post-operative thermalsensitivity.Many studies have given reports of prompt relief fromhypersensitivity with similar preparations. 90
    • 3.)Treatments that partially obturate dentinal tubules Effects of burnishing dentin:Burnishing of dentin with a tooth pick or orange woodstick results in the formation of a smear layer thatpartially occludes the dentinal tubules.Pashley et al employed an in vitro method to study theeffects of burnishing NaF, Kaolin and Glycerin aloneor in various combinations on dentin permeability. It was observed that burnishing created a partialsmear layer that reduced fluid movement across 91dentin by 50-80%
    • Formation of insoluble precipitants to blocktubulesCertain soluble salts react with ions in tooth structures toform crystals on the surface of the dentin.In order to be effective, crystallization should occurwithin 1 to 2 minutes and the crystals should be smallenough to enter the tubules.The crystals must also be large enough to partiallyobturate the tubules although relatively large crystals suchas calcium oxalate dihydrate are very effective in reducingpermeability.Smaller crystals such as calcium fluoride are less apt to beeffective. 92
    •  Silver nitrate is a time honored desensitizing agent The effectiveness of silver nitrate has been attributed to its ability to precipitate protein constituents of odontoblastic process, thereby partially blocking the tubules. Calcium hydroxide For many years calcium hydroxide has been a popular agent for the treatment of dentin hypersensitivity. The exact mechanism of action is unknown. But evidence suggests that it may block dentinal tubules or promote peritubular dentin formation. 93
    • FLUORIDE COMPOUNDSLukoinsky was the first to propose sodium fluoride as adesensitizng agent.Because dentinal fluid is saturated with respect tocalcium and phosphate ions, application of Fluoride todentin leads to precipitation of CaF2 crystals, thusreducing the functional radius of the dentinal tubules.The crystal size of CaF2 is very small and therefore asingle application of Fluoride has less effect on dentinpermeability than agents such as potassium oxalates thatgive rise to large crystals. 94
    • Acidulated sodium fluorideThe concentration of fluoride in dentin treated withacidulated NaF was significantly higher than dentintreated with NaF.Sodium silicofluorideApplication of a saturated solution of sodiumsilicofluoride for 5 minutes was much more potent thana 2% solution of NaF in desensitizing painful cervicalareas of teeth 95
    • Stannous fluoride:Blank and charbeneon advocate burnishing a 10%solution of stannous fluoride into sensitive root areas.It has also been reported that topical application of0.717% aqueous SnF2 provided immediate relief fromsensitivity.The ADA has recognized the desensitizing properties ofstannous fluoride gel by granting the ADA Seal ofAcceptance to a nonaqueous stannous fluoride gelformulation (Gel-Kam) for the therapeutic prevention ofsensitivity and caries. 96
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    • Fluoride iontophoresis :Iontophoresis is a term applied to the use of an electricalpotential to transfer ions into the body for therapeuticpurposes.The objective of fluoride ionotophoresis is to drivefluoride ions more deeply into the dentinal tubulesthan can be achieved with topical application of fluoridealone.Iontophoresis is not a simple procedure.It involves the placement of a negative electrode to dentinand a positive electrode to the patients face or arm. 98
    • If the negative electrode makes contact with saliva, gingival tissue or a metallic restoration the flow of current will follow the path of least resistance and stream around the dentin rather than through it.For this reason, it is recommended that teeth be isolatedwith plastic strips and cotton rolls rather than arubber dam.To use these battery-powered devices, the patient holds the positive electrode in his hand and the dentist, using the negative electrode, applies a 2% solution of sodium fluoride to the sensitive areas of the teeth. 99
    • Although a number of authors have reported asignificant reduction in sensitivity with the use ofiontophoresis with 2% NaF others found no strikingdifference between topical application of NaF with orwithout iontophoresis.The authors concluded that ―iontophoresis with 1%sodium fluoride is the method of choice for the treatmentof hypersensitive dentin, as it meets all the requirementsof an ideal desensitizing agent except permanency ofeffect, which requires further investigation‖ . 100
    • Iontophoretic application of fluoride by tray techniques:This new technique offers three improvements1) A safer, more powerful voltage source providing upto40 volts.2) Insulation of gingival tissues and metal restorations.3) A flexible electrode system adaptable to all areas ofthe mouth. 101
    • OXALATESThese are relatively inexpensive, easy to apply and welltolerated by patients.Potassium oxalate and Ferric oxalate solutions makeavailable oxalate ions that can react with calcium ions inthe dentinal fluid to form insoluble calcium oxalatecrystals that are deposited in the aperture of the dentinaltubulesBISBLOCKDentin Desensitizer, Oxalate 102
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    • • Potassium oxalate as a desensitizing agent was developed by Greenhill and Pashley.• It is sold commercially as PROTECT (John O. Butler Co., Chicago, Ill.).• Applying potassium oxalate to the dentin surface, which, in turn, produces ―calcium oxalate crystals‖ of different particle sizes within the dentinal tubules, is a means of obstructing the tubules apertures. 104
    • • ―Calcium oxalate is poorly soluble and is formed when the potassium oxalate contacts the calcium ions in the dentinal fluid.‖• A single-dose applicator permits pinpoint delivery, to the sensitive area, of monopotassium- monohydrogen oxalate.• Although the degree and duration of relief will vary from patient to patient, the effectiveness of a single application by the dentist can last up to 6 months.• It has been found that application of potassium oxalate to the etched dentin reduced sensory nerve excitability to the level of unetched dentin. 105
    • 4.)Treatment agents that undergo setting or polymerization reactionsA. Conventional glass Ionomer cements• One of the first clinical evaluations of the use of glass ionomers for the treatment of hypersensitive dentine in cervical abrasion lesions was reported by Low (1981).• The cervical lesions were etched with 50% citric acid for 30- 45 s, then rinsed and dried prior to placement of the glass ionomer cement.• Although the method of evaluating sensitivity was not described and no controls were used, the author reported complete loss of hypersensitivity in 89.7% of all patients. 106
    • B. Resins and Adhesives:The objective in employing resins and adhesives is to sealthe dentinal tubules to prevent pain producing stimulifrom reaching the pulp. 107
    • Javid et al during a 6 week study compared the effectsof a single application of isobutyl cyanoacrylate withweekly applications of 33% NaF paste.The cyanoacrylate was applied to sensitive rootsurfaces with a small cotton pellet and allowed to dry,this procedure provided immediate desensitization andproved to be significantly more effective than the NaFtreatments. However during a 6 week interval,sensitivity slowly returned.This suggests that the material is gradually lost, sorepeated application of cyanoacrylate becomes 108necessary.
    • GLUMA is a dentin bonding system includes a 5% gluteraldehydeprimer and 35% HEMA.It provides an attachment to dentin that is strong andimmediate.It has been reported that GLUMA seems to preventbacterial growth in tooth/restoration interfaces.This could have a beneficial effect in inhibitingplaque accumulation on sensitive root surfaces. 109
    • Indications :–As a normal part of resin bonding with a Gluma 3-step.–Under any indirect resin-bonded inlay, onlay, crown orveneer.–Under amalgam fillings.–Under crowns cemented with zinc phosphate cements.–In conjunction with other dentin bonding systemswhich may not provide a desensitization effect. 110
    • • Pulpdent Dentin Desensitizer contains 5% glutaraldehyde in water. It can be applied to all dentin surfaces, including cavity, crown and inlay preparations and cervical areas, as a desensitizing agent. 111
    • • In summary, the effectiveness of Adhesive resins in reducing dentine sensitivity has improved as bonding techniques and formulations have improved (Nakabayashi and Pashley, 1998).• These materials are somewhat technique sensitive and care must be taken to avoid creating a rough ledge of resin in the gingival crevice 112
    • 5.)LasersThe NdYAG Laser has been used experimentally indentistry since 1970s.Recently systems have become available which aretailored specifically for dental surgery using fiber opticdelivery to a hand pieces. 113
    • The tool was effective in reducing dentinhypersensitivity to cold stimuli, although themechanism of laser action has yet to be confirmed, itwould appear that obturation of the dentinal tubulesmay be the most logical hypothesis.It has been found to produce quick response with fewside effects, it is also simple and fast to administer,results are consistent, statistically significant andreproducible, high success rate, the patient find thetreatment procedure less traumatic 114
    • The presumed mechanism of action is the coagulation and precipitation of plasma proteins in dentinal fluid. It is also possible for the thermal energy to alter intradental nerve activity. Periodontal surgery—A tissue grafting procedure can be used to cover thesensitive surface and protect the dentinal tubules fromthe oral environment.The outcomes of this procedure to relieve sensitivity isunpredictable. 115
    • II. Home and desensitizing agents :During the years, a wide variety of professionally applied and home care products have been advocated for treatment of the hypersensitivity condition.Most of the dentifrices used as home remedies are in dentifrice form.Pashley et al found that dentifrice components could occlude tubules and the products differed in their ability to produce this effect. 116
    • Strontium chlorideStrontium chloride is contained in two toothpastes onthe market, Sensodyne and Thermadent . Strontium combines ―with phosphate in the dentinal fluidand exchanging for calcium in the hydroxyapatite of thedentinal tubule walls may produce strontium phosphatecrystals and dentinal tubules closure.‖Goodman believes that the strontium ion alters neuraltransmission, which may account for the immediateimprovement in relieving sensitivity. 117
    • • Strontium may also stimulate the formation of irritation dentin, and it has been reported ―as well to bind to the matrix of the tubule, thus reducing its radius.‖• Kun found that topical application of concentrated strontium chloride on an abraded dentin surface produced a deposit of strontium that penetrated dentin to a depth of approximately 20~ and extended into the dentinal tubules• Strontium deposits are produced by an exchange with calcium in the dentin resulting in recrystallisation in the form of a strontium apatite complexes 118
    • It was found that the radiodensity of dentin samplesimmersed in strontium chloride was significantlyincreased as compared with control specimenssuggesting that strontium is incorporated into toothstructure. 119
    • Potassium nitrateas a desensitizing agent was developed by Hodash, whoreported the use of saturated solutions and pastes to beused for home care that contain up to 5% potassiumnitrate.These pastes are sold over the counter as Promise andSensodyne Fresh Mint and Denquel . 120
    • Goodman has shown some impressive clinical resultsusing dentifrices containing potassium nitrate.He suggested that desensitization may occur either by theoxidizing nature of potassium nitrate or by crystallization,which blocks the tubules, or both.Goodman also believes that the ―potassium iondepolarizes the nerve fiber membrane…in which few orno action potentials can be evoked.‖ 121
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    • Dibasic sodium citrate:Another type of dentifrice for home therapy ofsensitivity was introduced by Jenner, Dnany and Tutz inthe year 1977 which was based on mixture of sodiumcitrate and pluronic a surface active agents.The citrate pluroxia dentifrice was some what moreeffective than 10% strontium chloride and 0.4%stannous fluoride in axhydrons glycerol.The substance has been recognised by Americandentinal association as been safe and effective fortreatment 124
    • Remineralization --Tooth mouse, Recaldent• casein phosphopeptide-amorphous calcium phosphate. 125
    • Future therapies for dentine hypersensitivityGene therapy in the future may include treatment of sensorynerves to dental restorative procedures as well as surgical andnon surgical debridement that elicits its dentinhypersensitivity.One such method may include blocking the increasedproduction of nerve growth factor(NGF)by pulpal fibroblastsnear the lesion thought to contribute to tooth hypersensitivityafter restorative procedures. 126
    • TREATMENT CONSIDERATIONS FORCERVICAL DENTIN SENSITIVITY INASSOCIATION WITH LOST TOOTHSTRUCTURE 127
    • • If, the patient has lost tooth structure at the cervical area and presents with dentin sensitivity, the best treatment is the use of restorative materials.• Restorative treatment of cervical dentinal sensitivity can be successfully accomplished using any currently marketed third generation dentin bonding agent or glass ionomer cement.• The newer light cured glass ionomer cements are easy to work with and have been used to successfully treat dentin sensitivity. 128
    • • The use of restorative materials to treat dentin sensitivity requires more time and is more expensive, but it is also more long lasting and predictable.• If patients have moderate to severe sensitivity in multiple teeth with minimal loss of tooth structure, clinicians should consider the use of topical agents such as oxalates or fluorides.• If one or two teeth remain sensitive after such treatment, they can then be treated with restorative resin materials. 129
    • TREATMENT CONSIDERATIONSFOR BLEACHING ASSOCIATEDSENSITIVITY 130
    • • If the patient has previously bleached their teeth with the night guard vital bleaching technique, then the custom-fitted tray can be used as the carrier for the anti sensitivity toothpaste.• If the patient is not a candidate for bleaching but has a history of chronic sensitivity, then non-scalloped, no reservoir designed tray can be fabricated. 131
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    • • Since tooth sensitivity during bleaching is common, yet unpredictable, it must be addressed clinically when it occurs.• Often the sensitivity experienced is ‗mild‘ and required no alteration in the treatment protocol.• In cases where it cannot be ignored, the dentist may have to instruct the patient to decrease the frequency (typically, to every other day) and duration of treatments.• When this protocol fails, some practitioners advocate the use of topical fluorides in conjunction with the beaching treatments. 133
    • • Others recommend using desensitizing toothpaste for 2-3 weeks prior to initiating as well as during bleaching.• Persons experiencing nighttime sensitivity may switch to daytime wear and reduce contact time of the peroxide to 2-4 hours.• In severe cases patients may have to stop bleaching for a few weeks or even altogether.• Use of calcium and fluoride added to bleaching agents• eg.calcium peroxide. 134
    • CONCLUSIONDentinal hypersensitivity is a problem that plaguesmany dental patients. When a patient presents withdentinal hypersensitivity symptoms, they should beexamined and informed of the multiple treatmentoptions that may be necessary to eliminate the problem.•The patient should be responsible for the decisionmaking process since some of their daily habits may becontributing to the problem and if not changed thecondition will persist. 135
    • •Up to 90% of patients suffering from DentinHypersensitivity claim that in particular a cold stimuluscauses the painful condition, whereas a tactile stimulusaffects up to10 per cent of patients 136
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