Dentine hypersensitivity: New perspectives on an old problem

Clinical Evaluation of Three Desensitizing Agents in Relieving Dentin Hypersensitivity

Three desensitizing agents with different active ingredients exhibited similar effects in the treatment of dentin hypersensitivity by mechanical blockage.

Cytotoxic effects of dental desensitizers on human gingival fibroblasts

The purpose of this study was to evaluate the effects of three different desensitizers on the cell viability and morphology of human gingival fibroblasts (HGF). Human gingival tissues were obtained from individuals who have clinically, healthy periodontium. HGF were grown at 37 degrees C in humidified atmosphere of 5% CO2 in Dulbecco's modified eagle's medium, supplemented with glutamine, penicillin, streptomycin, and 10% fetal bovine serum. The cells were treated with different concentrations (0.1, 0.3, and 0.5 microL/mL) of desensitizers (Gluma Desensitizer, Seal&Protect, and MicroPrime). After 24- and 48-h exposure to the desensitizer solutions, the viable cells were examined using a hemocytometer. To monitor HGF viability, 3-(4,5-dimethyl-2-thiazolyl)-2,5-diphenyl tetrazolium bromide (MTT) colorimetric assay was used and cell morphology was also observed at 48 h. Following exposure to concentrations of 0.1 microL/mL of test materials for 24 h, cell survival rates for Gluma Desensitizer (106%) and Micro Prime (62%) were not significantly different from the control, while it was significant for Seal&Protect (50%). Growing cells were significantly inhibited by all tested materials for 48 h (p < 0.05) in survival rates of 51, 47, and 31%, respectively. On the basis of the MTT assay, the cytotoxic effect of MicroPrime was more prominent, especially at high concentrations, than does Gluma Desensitizer and Seal&Protect. After exposure to Seal&Protect and MicroPrime, HGF became retracted, rounded in appearance and had loss of normal organization, leading to enlargement of intercellular space when compared with Gluma Desensitizer. As a conclusion, taking the limitations of an in vitro experiment into consideration, the cytotoxic effects were varied, depending on the chemical composition and exposure periods of the tested desensitizers.

Tooth brushing, tooth wear and dentine hypersensitivity — are they associated?

Evidence suggests that patients suffer the painful symptoms of dentine hypersensitivity when dentine is exposed and the dentinal tubule system is opened to the oral cavity to allow stimuli to trigger a neural response in the pulp via a hydrodynamic mechanism. The processes needed to localise lesions of dentine hypersensitivity include loss of enamel and/or gingival recession. Whilst tooth brushing with or without toothpaste appears to cause minimal wear to enamel (in the absence of acids), circumstantial evidence implicates tooth brushing with gingival recession and exposure of dentine. Other tooth wear processes notably attrition and acid erosion cause loss of enamel and can expose dentine. Therefore sensitivity may result. How lesions of dentine hypersensitivity are initiated is a matter of conjecture and based on extrapolating data from studies, mainly in vitro, to affect in vivo. Again this circumstantial type of evidence suggests that abrasion by some toothpastes and erosion by dietary acid could open the tubule system. Little is known about the actual effect of desensitising toothpastes on lesions of dentine hypersensitivity even though they are formulated to either occlude dentinal tubules or block the neural response in the pulp. Clinical studies have produced contradictory findings for the efficacy of products and there have been extremely few evidence based reviews. In conclusion, available evidence supports a probable link of tooth brushing, with or without toothpaste and an acidic diet to both tooth wear and dentine hypersensitivity, and suggests also that dentine hypersensitivity is a tooth wear phenomenon. Although there is a need for more direct clinical and scientific evidence for these associations, it is recommended that they be taken into consideration when planning management strategies for the dentine hypersensitivity sufferer.

Erosion — chemical and biological factors of importance to the dental practitioner

The intrinsic and extrinsic aetiology factors responsible for dental erosion are well understood as are the chemical events leading the initial mineral dissolution, softening and eventual loss of the dental surface. Of greatest importance are the pH, titratable acidity, phosphate and calcium concentration, fluoride content of the erosive challenge which determines the degree of saturation with respect to the tooth mineral, and thus the driving force for its dissolution. Of the biological modifying factors affecting the erosion process, the protective properties of saliva and its contribution to pellicle formation are considered of greatest importance. Unstimulated salivary flow rate and buffering capacity have been directly associated with dental erosion. The acquired pellicle has been shown to have a protective effect against acid erosion by acting as a diffusion barrier. There is considerable overlap between the aetiology of dental erosion and that of dentinal hypersensitivity. Patient education on the causes and prevention of dental erosion are essential to prevent progression. In addition to reducing or eliminating exposure to acidic soft drinks and juices, modified acid beverages with reduced potential to cause erosion can be recommended to patients. Frequent application of high concentration topical fluoride may be of some benefit in preventing further demineralisation and increase the abrasion resistance of erosion lesions.

The efficacy of three desensitizing agents in treatment of dentine hypersensitivity

PURPOSE

The purpose of this study was to evaluate the efficacy of three desensitizing agents vs. placebo.

MATERIALS AND METHODS

One hundred and six hypersensitive teeth of 26 patients were included in this study, and the baseline hypersensitivity level of all teeth was established as 'moderate' by using Visual Analogue Scale (VAS). The teeth were divided into four groups: to the first group 5% potassium nitrate bio-adhesive gel, to the second 2% sodium fluoride bio-adhesive gel and to the third one step adhesive system Prompt L-Pop were applied as desensitizing agents. Group 4 was the control group in which a desensitizer-free bio-adhesive gel was used as placebo. Post treatment and eighth week control measurements were recorded on VAS.

RESULTS

It was observed that the efficacy of three desensitizing agents did not differ from each other (P >0.05) and except for placebo all reduced moderate dentin hypersensitivity effectively (P <0.05).

CLINICAL RELEVANCE

Five per cent potassium nitrate, 2% sodium fluoride bio-adhesive gels and one-step bonding agent Prompt L-Pop were effective in reducing moderate dentine hypersensitivity.

A comparison of a reformulated potassium citrate desensitising toothpaste with the original proprietary product

OBJECTIVES

The recent tendency for toothpaste manufacturers to combine active ingredients for benefits to a number of oral problems requires that such combinations do not vitiate the action of any one agent. The aim of this study was to compare the desensitising effects of a modified formulation with the established product.

MATERIALS AND METHODS

The study was a randomised, double blind, two treatment parallel design comparing an existing potassium citrate toothpaste product (Positive Control) with the same formulation to which triclosan and zinc citrate had been added (Test). A total of 56 subjects with dentine hypersensitivity (DH) completed the 8 week study period. At baseline, days 14 and 56 visual analogue scale scores were recorded by the subjects in response to air evaporative and cold water stimuli.

RESULTS

Both groups showed improvements, mostly statistically significant, from baseline to day 14 and through to day 56. Most data favoured the Test paste but differences were, for the most part, not significant.

CONCLUSIONS

It is concluded that the addition of known anti-plaque agents to an established potassium salt based desensitising toothpaste did not adversely affect the activity of the product in the treatment of DH.

Dentine hypersensitivity: a randomised, double-blind placebo-controlled study of the efficacy of a fluoride-sensitive teeth mouthrinse

OBJECTIVES

Potassium and fluoride salts have been used in the treatment of dentine hypersensitivity (DH). The primary aim of this study was to compare a fluoride-containing mouthrinse product with a placebo rinse for the treatment of DH. A secondary aim was to compare effects on plaque index (PI) and gingivitis index (GI).

MATERIAL AND METHODS

The study was a double-blind, randomised, two-treatment parallel design involving 91 subjects with DH. At screening, an air evaporative stimulus (AES) was used for selection. Approximately 4 weeks later, at the baseline visit, DH was recorded, using a response-based visual analogue scale (VAS) from upper and lower incisors, canines, premolars and first molars in response to AES and from two to six teeth in response to a cold water stimulus (CWS). PI and GI were also recorded. Subjects were then allocated the test or placebo rinse. On days 28 and 56, VAS scores were again recorded for AES and CWS, with PI and GI recorded at day 56.

RESULTS

Both groups improved symptoms to day 28 and again to day 56. The majority of the data favoured the test rinse as more effective but there was no clear evidence for a statistically significant difference between test and placebo. PI at lingual sites approached significance for the test rinse.

CONCLUSIONS

The placebo response has again been shown to play a significant role in DH clinical trials and narrows the range over which to detect treatment differences. Study designs to minimise or prevent the placebo response in DH seem worthy of consideration.

Dentine hypersensitivity: development and evaluation ofamodel in situ to study tubulepatency

BACKGROUND AND AIMS

Lesions of dentine hypersensitivity have numerous tubules open at the dentine surface as opposed to non-sensitive dentine where tubules are mostly covered by a smear layer. The present two studies were designed to model both states in situ and evaluate the effects of agents on the model.

METHOD

Etched (sensitive) and smeared (non-sensitive) dentine specimens prepared from human third molar teeth were retained in lower buccal acrylic appliances. The results of Study 1 led to the development of a method to ensure tubules were sectioned at right angles. Study 1 was a 5-day period, seven treatment regimens randomised, part blind cross over design involving five subjects. Treatments were 2x day application of a desensitising (SA) or non-desensitising toothpastes (F) or chlorhexidine (CHX) mouthwash with or without drinking orange juice (OJ)(1 l/day). A no treatment group (P) allowed plaque to accumulate. The evaluation of effects was observational by scanning electron microscopy (SEM). Study 2 involved 1 subject, 4 treatments applied once and studied after 0, 6, and 12 h by SEM with image analysis. The 12 h groups were studied with and without imbibing water or OJ. Treatments were two desensitising (SA & SC) and one non-desensitising (F) toothpastes and an in office product (DS).

RESULTS

Study 1: Treatment SA resulted in occlusion of tubules an outcome little changed by OJ. Treatment P produced a bio-film, which covered the dentine surface. CHX produced some tubule occlusion in three of the five subjects. F+/-OJ and CHX+OJ had little effect and tubules remained open. For smeared specimens toothpastes and OJ removed the smear layer but SA+/-OJ blocked tubules. P and CHX had no effect on the smear layer. Study 2: At 0 h, tubule occlusion was in order of magnitude DS>or=SA>SC>F. After 6 and 12 h with SA, SC and F some loss of occlusion occurred but not DS. Water and OJ by 12 h decreased occlusion for SA, SC and particularly F. Water and OJ removed virtually all of DS.

CONCLUSIONS

The aims of Study 1 were achieved and effect of treatments was not inconsistent with data in vitro. The need for more standardisation of specimens was appreciated and applied in Study 2 to allow image analysis to quantitatively record data. Further use of the model in randomised controlled clinical trials is envisaged.

Can tooth brushing damage your health? Effects on oral and dental tissues

Circumstantial evidence based on anecdote, case reports, epidemiological data and studies in vitro and in situ implicate tooth brushing with toothpaste with tooth wear, gingival recession and dentine hypersensitivity. This review attempts to assess the clinical significance of the potential harm produced by this most common oral hygiene habit. The toothbrush alone appears to have no effect on enamel and very little on dentine. Most toothpaste also has very little effect on enamel and in normal use would not cause significant wear of dentine in a lifetime of use. Wear of enamel and dentine can be dramatically increased if tooth brushing follows an erosive challenge. Gingival recession has a multi-factorial aetiology and certain individuals and specific teeth may be predisposed to trauma from tooth brushing. Tooth brushing is known to cause gingival abrasions but how these relate to gingival recession is not known. The role of toothpaste in gingival abrasion and recession surprisingly has received little if any attention. Gingival recession most commonly exposes dentine and localises sites for dentine hypersensitivity. Some toothpaste products can expose dentinal tubules but erosion is probably the more dominant factor in dentine hypersensitivity. There is no evidence to indicate that electric and manual toothbrushes differ in effects on soft and hard tissues. It is only under, over or abusive use or when combined with erosion that significant harm may be thus caused. In normal use it must be concluded that the benefits of tooth brushing far out-way the potential harm.