cosmetic dentistry - beauty & science

24 I I research _ hypersensitivity become plugged owing to the formation of organic biofilm. When this occurs, the bidirectional flow of fluidsstopsandsodoesthepain.Duringbleaching,the organicplugsmaybedissolved,reopeningtheenamel channelsandcausingsensitivity.17 _Treatment The first line of treatment for dentine hypersensi- tivity is of course prevention. All of the predisposing factors must be dealt with first. This may not be an easy task. Periodontal disease, recession, occlusal forces and diet present many challenges. The treat- mentofsensitivityismuchsimplerincomparison. If we review the mechanism of action of dentine hypersensitivity, it is easy to understand the wide rangeofproductsavailablefortreatment.Theproduct musteitherblockthemovementoffluidinthetubules or stop the transmission of the pain response to the pulp. For added simplification, it is important to focus on the active ingredient, and not on the multitude of products(TableI). Products are available for in-office or at-home application. Treatment should not be restricted to oneoptiononly.Thisisnotaone-size-fits-allsolution. Differenttreatmentsmaybetriedandmodifiedbased onthepatient’sresponse. The first group of products works by occluding the open tubules and decreasing pulpal fluid flow. This group includes fluorides, fluoride varnishes, tissue fixatives, oxalates, remineralising agents and Pro- ArginTechnology.Thesecondgroupofproductsworks bydepolarisingthenervesothatitcannottransmitthe painresponse. _Occlusion of dentinal tubules Fluorides Fluoride application is believed to work through a reactionbetweenthefluorideionandionisedcalcium in the tubular fluid. This reaction forms an insoluble calcium fluoride precipitate in the tubule.18 Different fluorides show differing efficacies. Stannous fluoride is more effective than sodium fluoride in the concen- trationsusedfortoothpasteformulations(Fig.3a&b). Fluoridevarnishes Fluoridevarnishesmaybeusedforsensitivityrelief but are chiefly indicated for caries control and re- mineralisation. The desensitisation effect is transient, since the material is abraded soon after placement. Many applications may be necessary for increased efficacy. It is thought that the benefit comes from the physical blockage of the tubules by the varnish base ratherthanthefluorideitself.18 Tissuefixatives Tissue-fixative desensitising products contain agentssuchasglutaraldehydeorHEMA.Theseagents bind to tissue fluid proteins in the dentinal tubules and the superficial cells of the subadjacent pulp and denature (coagulate) these proteins. These products cannot be placed near the gingival epithelium, since they may cause necrosis of the gingiva, as well as loss ofthebiologicalattachment.17 Oxalates Desensitisers containing metallic salts, predomi- nantly oxalates, form insoluble chemical precipitates intheperi-tubulardentine.Noacidetchorlightcuring isneeded.Theycausenoirritationofthegingivaltissue. OneexampleisSuperSeal(PhoenixDental).SuperSeal formsacomplexwiththecalcium-richzoneoftheperi- tubulardentinetocreateacrystalplug.Thiseffectively shutsdowndentinesensitivityalmostentirely(Fig.4).19 Remineralisingpastes Remineralising pastes are used in the office or at hometorestorethemineralsthathaveleachedoutof patients’ teeth owing to caries, diet, etc. These pastes have the added advantage of reducing sensitivity throughtubuleocclusion.Twoactiveingredientshave beenshowntobethemosteffectiveforthispurpose: 1.Novamin (calcium sodium phosphosilicate bio- active glass) and amorphous calcium phosphate: Novamin-containingtoothpasteshavebeenshown to reduce dentine hypersensitivity significantly, with continued home use.20,21 The effect is cumula- tiveuptoaboutsixweeksandthenstabilises. 2.ACP: ACP forms a protective mineral barrier of hydroxyapatite that occludes the exposed dentinal tubules (Fig. 5a & b).22 ACP is most effective in the form called Recaldent (casein phosphopeptide- amorphouscalciumphosphate)inwhichthecasein portion (derived from milk) binds the ACP to the tooth surface, where it can do its job. Recaldent- containing pastes are placed on the affected areas afterregularbrushing. Pro-ArginTechnology Inhealthypatients,salivaisnormallyveryeffective in reducing dentine hypersensitivity. Saliva provides calcium and phosphate, which over time occlude open dentine tubules. Pro-Argin Technology was de- velopedbasedonthisrolethatsalivaplaysinnaturally reducinghypersensitivity.23,24 cosmeticdentistry 2_2012 Fig. 3a & b_In the concentrations used for toothpastes, stannous fluoride is more effective than sodium fluoride in occluding dentinal tubules. (Courtesy of Procter & Gamble) Fig. 4_Super Seal forms a complex with the calcium of the peri-tubular dentine to create a crystal plug across the dentine tubules. (Courtesy of Tammy Bonstein) Fig. 4 Fig. 3b Fig. 3a