International Dental Journal (2002) 52, 7–10

Dentine hypersensitivity: bleaching and restorative considerations for successful management

Van B. Haywood Augusta, USA

The presenting symptoms of sensitive teeth are multi-factorial, and from the Historically, probably the most perspective of restorative , making a differential diagnosis of true common concern that brings people dentine hypersensitivity is a challenge. This paper discusses the common to the dental practice is a tooth that causes of tooth sensitivity, focusing on restorative (operative) aspects and hurts. A diagnosis of the cause of (bleaching). Restorative strategies for managing the condi- tooth sensitivity can range from an tion and recommended dental materials are reviewed. abscessed or cracked tooth, to dental decay or some form of Key words: Sensitive, hypersensitive, restorative dentistry, tooth bleaching hypersensitivity. Symptoms of one condition can often be confused with another, and pain level can be directly or indirectly related to severity of the cause. This paper will discuss the causes of sensitive or hypersensitive teeth that the may encounter, and possi- ble treatments from a restorative perspective. The focus will be on sensitivity problems with no obvi- ous pathology. A differential diagnosis of sensi- tivity must take into consideration a number of variables (Table 1), such as problems with the tooth, problems with the surrounding periodontium, insults to the tooth and predisposing conditions. When the patient presents with sensitivity, the first step in manage- ment is to take a complete history of the condition. Essential infor- mation to be assessed includes: • The history and nature of the pain (sharp, dull, or throbbing) • The number and location of sensitive teeth, and whether the same teeth are always involved • The area of the tooth from which the sensitivity originates • The intensity of the pain (on a Correspondence to: Van B. Haywood. E-mail: [email protected] 1–10 scale, where 1 = mild, and

© 2002 FDI/World Dental Press 0020-6539/02/05000-06 8

Table 1

1. Abscessed or non-vital tooth. With periapical radiolucency or draining fistula; necrotic with sensitivity to occlusion; partially necrotic in one canal, with vital tissue elsewhere (in which case tooth tests vital to stimuli). Pain typically occurs spontaneously or upon occlusion or tapping. 2. Cracked tooth. Vertical fracture or single cusp partial fracture. Pain typically occurs on release of biting or tapping of a single cusp. 3. Dental caries. Greatest degree of sensitivity experienced when dental decay passes the dentine-enamel junction. As caries penetrates further into the tooth, sensitivity lessens until pulp becomes involved. 4. Gingival recession. Often occurs post-periodontal surgery, when a large portion of the root is exposed, or due to ageing, mechanical trauma, fraenum attachment pull or occlusal trauma. 5. Toothbrush abrasion. Caused by use of a hard toothbrush or a soft toothbrush with abrasive toothpaste or by aggressive brushing, and generally located on the side opposite the dominant hand. Abrasion may either instigate gingival recession or stem from greater accessibility to softer root surfaces from recession. 6. Abfraction lesions. Generally associated with occlusal trauma where the anatomic crown of the tooth has flexure. Although non-carious, these lesions can become very sensitive and even progress into the pulp. They may be multi- factorial where abrasion and erosive forces combine to produce tooth surface loss. 7. Erosive lesions. Associated with acid reflux, hiatus hernia, purging, bulimia (intrinsic causes), and diet (extrinsic causes). Intrinsic acid lesions typically occur on the palatal surfaces, while extrinsic acid lesions tend to occur on the buccal surfaces. Consuming large quantities of carbonated cola drinks and fruit drinks, which have a very low pH, causes tooth surface loss1-3, as does toothbrushing following an acidic assault, which removes the acid-softened enamel or dentine. 8. Diet sensitivity. Generally associated with a low pH material, such as fresh tomatoes, orange juice, cola drinks4-6. Areas with exposed dentine are etched, causing sudden sensitivity. Diet choices may aggravate sensitivity from erosion. 9. 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 DEJ7, or is a factor of lower overall patient pain threshold values. 10. Restorative sensitivity. Triggered following placement of a restoration for several possible reasons: certain amalgams (such as Tytin) having a history of 24–48 hours sensitivity due to shrinkage, rather than the usual expansion, during setting; contamination of composites during placement or improper etching of the tooth on composites, which results in micro-leakage; improper tooth-drying technique; 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. 11. 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 ageing 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 dentine8. 12. Bleaching sensitivity. Commonly associated with carbamide peroxide vital tooth bleaching9 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 minutes11. 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. Sensitivity caused by all other forms of bleaching (in-office, with or without light activation, and new, over- the-counter) is depends on peroxide concentration.

10 = intolerable) and any include an objective evaluation of reveal caries or periapical pathol- changes – an increase, decrease the following factors: ogy? or no change – in intensity of • Does tactile examination with a • Is dentine exposed (gingival the pain dental explorer elicit pain, and recession, loss of attachment, • The trigger or stimulus which can the pain be localised to one loss of enamel, or abfraction) initiates the sensitivity area or one tooth? • Is there evidence of cracked • The frequency and duration of • Is the area or tooth sensitive to cusps, fractured or leaking res- each episode gentle flow of air from the air- torations, or occlusal interfer- • Other related events, such as water syringe? ence and hyperfunction, or brux- recent restorative or periodon- • Is the tooth sensitive to percus- ism? tal and hygiene treatments, sion? Once the cause is determined, change in diet or • Is there sensitivity to biting pres- treatment options can be consid- aids or regimen, or home sure or upon release? ered. Options can be non-reversible bleaching. • What is the duration of pain or reversible (Table 2) or a combi- A thorough clinical examination after stimuli? nation of both depending upon should follow the interview, and • Does radiographic examination severity and extent of the condition.

International Dental Journal (2002) Vol. 52/No.5 (Supplement 1) 9

Table 2 List of potential agents, restorative materials or procedures for use in the management of dentine hypersensitivity

Reversible Non-reversible

Desensitising toothpastes Glass ionomer cements Fluoride gels, rinses, and varnishes Resins, filled or unfilled Oxalates of ferric, aluminium and potassium Periodontal flaps or grafts Protein precipitants Pulp extirpation and root canal filling

Treatment options In the case of abscessed teeth, cracked teeth or dental caries, removing the cause can involve: endodontic therapy, oral surgery (extraction, root resection or apical surgery), or replacing the restora- tion and broken cusp. When a restoration is indicated, preventing sensitivity can take the form of base placement (such as Vitrabond for thermal sensitivity) or sealing dentine tubules with a prime and bond system (as found with any composite bonding system). Sensitivity can be reduced by cleans- ing the cavity preparation with a chlorhexidine solution to reduce bacterial insult, sealing tubules with a HEMA and glutaraldehyde mate- rial (e.g. Gluma) or selecting materi- als that have no history of inducing this condition (e.g. composite resin Figure 1. Cracked tooth. Upon removal of a large amalgam restoration for which the patient instead of amalgam). complained of sensitivity to biting, a fracture was noted from mesial to distal Techniques for cementation of crowns, which preclude over-dry- surfaces to unbound surfaces, can by placement of a microfilled ing of the tooth where glass help determine the potential for composite, which offers some flex- ionomer cements are employed, sensitivity and suggest a possible ibility with the tooth movement. may be helpful in avoiding sensi- change in placement techniques A higher failure rate has been tivity. Depending on the cement to minimise the effects of poly- reported in Class V composite used, dentine tubules can be sealed merisation shrinkage. A Class I or bonding of non-carious cervical under crowns with prime and Class V preparation has the high- lesions when the composite is bond, HEMA/gluteraldehyde or est C factor (5) and the greatest placed in an untreated abfraction simple copal varnish. If occlusal chance for post-operative sensi- lesion, emphasising the need to trauma is suspected, adjusting the tivity but is also often used through modify the occlusion and reduce occlusion or inserting a splint may aesthetic necessity to treat existing the abfraction forces. be beneficial. Cervical lesions from sensitivity. Techniques that can mini- Root surfaces that have been abrasion or abfraction may require mise the chance of exchanging exposed from erosion and/or restorations for thermal protection, one type of sensitivity for another abrasion, (sometimes described as as opposed to application of a then include avoiding bulk filling, toothbrush trauma) can often be desensitising material alone (see placement of a stress breaker liner recovered by periodontal flap or Figure 1 for abfraction lesion). Some such as Optibond II or Vitrabond, graft surgery, but only in cases sensitivity associated with new and soft-start curing lights12. where resins have not been applied composite restorations is due to Abfraction lesions may require previously to the root surface. placement techniques and bulk cure adjustment of the occlusion Consideration must be given to the of high polymerisation-shrinkage (usually elimination of the function future need for muco-gingival materials. contacts other than those in maxi- grafting to the application of any The ‘C-factor’, or ratio of bound mum inter-cuspation), followed restorative material as an uncontami-

Haywood: Dentine hypersensitivity: bleaching and restorative considerations 10 nated dentine surface is necessary treating sensitive teeth is the use of sium nitrate dentifrice. In 2001, for re-attachment. desensitising toothpastes14, which Haywood et al published a paper contain potassium salts (nitrate or describing the use of 5 per cent chloride). Potassium ions pass easily potassium nitrate in bleaching trays Sensitivity management through the enamel and dentine to to reduce the sensitivity that is trig- The challenge for sensitivity manage- the pulp in a matter of minutes15,16. gered during bleaching19. They ment is greatest when the sensitive Potassium is believed to act by determined that 10–30 minutes of tooth does not have or require a interfering with the transmission of wear time generally alleviates restoration. Then, the number of the stimuli by depolarising the sensitivity. teeth involved and the location and nerve surrounding the odontoblast The current recommendation in frequency of the sensitivity dictate process. Most potassium-based the USA is to use a desensitising the best type treatment. desensitising toothpastes also contain toothpaste containing 5 per cent Among the reversible treatment fluoride for cavity protection, and potassium nitrate and fluoride, but options are materials that interfere some offer an array of flavours without sodium lauryl sulphate with the transmission of the pain and the whitening, tartar-control, (SLS) if available. SLS is the ingre- stimulus at the level of the A-delta and baking soda benefits found in dient primarily responsible for the fibres around the odontoblast most regular toothpastes (e.g. the foaming action. One possible side (potassium salts), or exert a block- Sensodyne® range, GlaxoSmithKline, effect of using a large volume of ing effect on the open dentine Crest Sensitivity Protection, Proctor toothpaste may be occasional tissue tubules (strontium, oxalates or fluo- & Gamble, or Colgate Sensitive®, irritation, possibly from the one of ride agents). Some protein preci- Colgate Palmolive). Strontium salts the toothpaste ingredients. If irrita- pitants may act in a dual capacity. (chloride and acetate), that are tion occurs, the patient should try a A number of topical agents have thought to act by blocking the open different flavour and composition. been used to reduce tooth sensitivity. dentine tubule, can also still If the gingival problem persists, the The most common for professional be found in desensitising tooth- dental professional can switch the application are fluorides. Fluoride pastes (Sensodyne® Original, patient to a professionally supplied may decrease sensitivity peripher- GlaxoSmithKline). potassium nitrate and fluoride ally by occluding the dentine In clinical trials, the desensitising products specifically designed for tubules through crystallisation and effect of toothpaste generally takes at-home, tray delivery application. reducing the fluid flow to the pulp13. about two weeks of application The cost of these products is Patients may use a prescription twice per day to show reductions considerably more than toothpaste, toothpaste with higher concentra- in sensitivity, and greater effect and the patient must visit the tions of fluoride (5,000ppm), or develops with continued use17. The dentist for re-supply. Therefore, if the dentist may apply a topical fluo- patient should be advised in the patient can use toothpaste with- ride either as a gel in a tray to treat accordance with the manufactur- out untoward problems, then the many teeth, or as a varnish to treat er’s instructions, typically to be patient has a lifetime approach to specific, accessible areas of a single applied by brushing twice daily as controlling sensitivity. The patient tooth. part of the regular oral hygiene regi- should be advised to experiment Another group of materials is men. Recommending desensitising with a variety of toothpastes before the oxalate salts, include potassium toothpaste that is similar in prop- committing to the professionally oxalate and ferric oxalate. These erties to the patient’s regular paste supplied materials. materials, which are generally will enhance compliance and One of the primary motivations applied in a rubbing or burnishing increase effectiveness. for people coming to the dental motion, act by occluding the However, desensitising tooth- practice is to have their teeth tubules and reducing tubule fluid pastes have been applied in a variety cleaned, so that their smile will be flow in either direction. Other of formats. In 1995, Jerome white. However, some people with agents applied by the dental profes- published a case study describing a sensitive teeth avoid hygiene appoint- sional are the dentin-bonding technique for treating tooth sensi- ments because of the discomfort derivatives or agents and the tivity in post-periodontal surgery the procedure elicits. Such sensitiv- HEMA/gluteraldehyde products, patients18. Instead of having the ity can be a pre-existing condition which either occlude the tubules or patient brush with a dentifrice or a result of the cleaning proce- precipitate the protein in the tubule. containing potassium nitrate, he dure. The tray delivery system may placed the desensitising toothpaste be beneficial to this routine dental in a custom-made soft tray. By hygiene patient with a history of Desensitising toothpastes increasing medicament-tooth contact sensitive teeth: applying the desen- The most common, professionally time, the tray delivery system sitising toothpaste in a tray for endorsed, self-applied approach to increased the efficacy of the potas- 10–30 minutes prior to the prophy-

International Dental Journal (2002) Vol. 52/No.5 (Supplement 1) laxis appointment has been of sensitivity is to try to predict ments for tooth sensitivity. The reported to reduce discomfort which patients will become sensi- dentist must explore all possibili- during and after the procedure. tive. However, the only significant ties, form a definitive diagnosis or Should discomfort occur after the predictors determined thus far35 are diagnoses, then implement manage- procedure, the material can be a previous history of sensitive teeth ment strategies that address all re-applied as needed until it is and a regimen of more than one causes and predisposing factors to lessened or gone. application of the bleaching solu- reduce or eliminate the sensitivity. tion per day. Moreover, the 2–6 Treatments may range from simple month treatment time for the topically applied medicaments at The effect of bleaching complete management of tetracy- home by the patient to restorations, If the patient has previously cline-stained teeth has demonstrated pulp removal or muco-gingival bleached their teeth with the just how sporadic the sensitivity is surgery. The severity and extent of nightguard vital bleaching technique in some patients36. the sensitivity will dictate variations (see below), then the custom-fitted Since tooth sensitivity during in treatment options. Chronic tray can be used as the carrier for bleaching is common, yet unpredict- problems with teeth not having the toothpaste. If the patient is not able, it must be addressed clinically restorations or obvious pathology a candidate for bleaching but has a when it occurs. Often the sensitiv- are most disconcerting. The use of history of chronic sensitivity, then a ity experienced is ‘mild’, and requires a desensitising agent such as 5 per non-scalloped, no-reservoir designed no alteration in the treatment cent potassium nitrate-fluoride gel tray can be fabricated. If it is protocol. In cases where it cannot (toothpaste) applied in the bleaching unclear whether this approach will be ignored, the dentist may have to tray as needed for tooth sensitivity benefit the patient, a less involved instruct the patient to decrease the can be effective and gives the technique may be tried that uses a frequency (typically, to every other patient more control over the direct thermoplastic tray made day) and duration of treatments37. condition. This tray delivery tech- directly in the patient’s mouth with- When this protocol fails, some nique reduces tooth sensitivity from out an alginate impression, stone practitioners advocate the use of nightguard bleaching in a majority cast and laboratory exercise20,21. topical fluorides in conjunction of patients, which allows most While this tray is more rigid, it is a with the bleaching treatments. patients (including those under- quick means for determining the Others recommend using a desen- going long-term treatment for efficacy of a tray-applied medica- sitising toothpaste for 2–3 weeks tetracycline staining) to continue ment such as toothpaste or fluoride prior to initiating as well as during whitening to successful completion. gels22. bleaching. Persons experiencing Much has been learned about night time sensitivity may switch to tooth sensitivity with the advent of daytime wear and reduce contact References at-home bleaching. Nightguard time of the peroxide to 2–4 hours. 1. Meurman J H, Harkonen M, Naveri vital bleaching applies a 10 per cent In severe cases patients may have H, et al. Experimental sports drinks carbamide peroxide material in a to stop bleaching for a few weeks with minimal dental erosion effect. custom-fitted tray overnight for 2– or even altogether. Scand J Dent Res 1990 98: 120–128. The advent of tray delivered 2. Harrison J L, Roeder L B. Dental ero- 6 weeks. Although some claims sion caused by cola beverages. Gen Dent have been made for nightguard desensitising agents containing 1991 39: 23–24. bleaching products that do not potassium has greatly aided the 3. Grobler S R, Jenkins G N, Kotze D. induce sensitivity, double-blind dentist in taking a more active The effects of the composition and clinical studies have shown that approach to managing sensitivity method of drinking of soft drinks on sensitivity occurs in 55 per cent to and affords patients a simple, plaque pH. Br Dent J 1985 158: 293– 75 per cent of treatment groups23–34, effective means to control their 296. treatment. The bleaching study 4. Rytomaa I, Meurman J H, Koskinen J, with placebo groups experiencing et al. In vitro erosion of bovine enamel sensitivity in 20 to 30 per cent of demonstrates the efficacy of 10– caused by acidic drinks and other subject. One study even reported 30 minute applications of the foodstuffs. Scand J Dent Res 1988 96: tooth sensitivity of about 15 per desensitising material, used as 324–333. cent in subjects wearing only the needed (one time only, once a 5. Grenby T H, Phillips A, Desai T, et al. bleaching tray. Therefore, it appears week, continuous before each Laboratory studies of the dental prop- that this kind of sensitivity is a bleaching treatment, or alternated erties of soft drinks. Br J Nutr 1989 multi-factorial event that cannot be with bleaching treatments). 62: 451–464. 6. 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