A new desensitizing dentifrice: preliminary report

Patient-applied treatment of dentinal hypersensitivity

This article reviews the evidence regarding the effectiveness of various patient-applied interventions for dentinal hypersensitivity. Self-applied treatments are popular because they are both economical and easy to use. The disadvantages include compliance, difficulty to deliver to specific sites, slow onset of action, and the requirement for continuous use. Conflicting research findings make it difficult for the practitioner to determine which self-applied product to advise patients to use. There are a number of issues that have plagued research in this area, including the lack of standardization of stimulus testing and inadequate sample size. The evidence is insufficient to permit the development of evidence-based guidelines for the treatment of dentinal hypersensitivity.

Formulation of an antispasmodic drug as a topical local anesthetic

Mebeverine hydrochloride, a spasmolytic agent on GIT smooth muscles, was reported to have a local anesthetic effect. Thus, it was desired in this study to formulate mebeverine HCl into a gel that could be used locally in the treatment of different oral painful conditions. Poloxamer 407 (P-407) was used as the base for this gel. Different additives were used to enhance drug release from the preparation while others were used to enhance the residence time for the preparation. Different formulae were characterized in terms of drug release and mucoadhesion. The formula which has shown the best compromise between the aforementioned parameters was selected for clinical evaluation in comparison to Lidocaine HCl gel and rheologically examined. The best drug release enhancer was cetrimide (0.005%, w/w), while hydroxypropylcellulose (0.5%, w/w) as a mucoadhesive additive has shown the best compromise between fast drug release and mucoadhesion. The gel formula (G) has shown a better pain reduction efficiency (p=0.0078) and longer duration (p=0.0313) than Lidocaine HCl gel. Histopathological examination has shown no change in the inflammatory cells count of rat oral mucosa. Therefore, it could be concluded that (G) is very promising as a local anesthetic preparation for the treatment of different oral painful conditions.

A split-mouth placebo-controlled study to determine the effect of amorphous calcium phosphate in the treatment of dentine hypersensitivity

Many treatments for dentine hypersensitivity are formulated to directly or indirectly occlude the open dentinal tubules associated with the condition. Combining solutions of calcium chloride and potassium phosphate can result in the precipitation of amorphous calcium phosphate. Such a system applied to exposed dentine could occlude dentinal tubules and reduce sensitivity. The aims of this study using a placebo control were to assess the therapeutic value of amorphous calcium phosphate in dentine hypersensitivity and provide further information on the apparently natural improvement in the condition frequently observed in clinical trials. 38 subjects with dentine hypersensitivity affecting 1 tooth in each left and right sides of the jaws were recruited into this split mouth, randomised, double-blind study. At baseline, sensitivity was scored by the subjects on a 0-10 visual apologue scale after tactile, cool and cold water and evaporative stimulation of the test teeth. Active and control, water, solutions were then applied by a 2nd clinician. After 24 h, subjects returned for rescoring. On days 7 and 14, subjects were again rescored and the treatments reapplied. Further follow-up appointments for rescoring were on days 21, 28, 56 and 84. Plaque scores also were recorded from test teeth at each visit. Overall sensitivity decreased considerably and to a similar degree in test and control teeth with no consistent significant treatment difference. Plaque scores also decreased through the study period. It is concluded that either the amorphous calcium phosphate was without therapeutic effect or the activity was masked by the placebo response in the control teeth.

In vitro evaluation of pluronic F127-based controlled-release ocular delivery systems for pilocarpine

The overall objective of this study was to develop pluronic F127 (PF127)-containing formulations of pilocarpine hydrochloride (PHCL) suitable for controlled-release ocular delivery of PHCL. Various aqueous formulations were evaluated containing 1% w/v PHCL and 25% w/v PF127 alone or with one of the following additives present: poly(ethylene glycol) 4600 (PEG), poly(vinylpyrrolidone) 10,000 (PVP), poly(vinyl alcohol) 10,000 (PVA), methylcellulose 15 cP (MC), and hydroxypropyl methylcellulose 80-120 cP (HPMC). The in vitro dissolution of the PF127 formulations and the pilocarpine release profiles from them were obtained simultaneously at 34 degrees C and room temperature using a membraneless in vitro model. It was observed that the PEG- and PVP-containing PF127 formulations of PHCL dissolved the quickest and released the drug at a significantly faster rate than the control PF127 formulation, which had no additive present. The PF127 formulations of PHCL containing MC or HPMC exhibited the slowest dissolution rates and released the drug the slowest. The same rank order was observed at each temperature for the dissolution and PHCL release profiles of each formulation. On the basis of the in vitro results, the PF127 formulations of PHCL containing MC or HPMC as an additive showed potential for use as controlled-release ocular delivery systems for PHCL.

Dentine hypersensitivity and the placebo response. A comparison of the effect of strontium acetate, potassium nitrate and fluoride toothpastes

A considerable number of varied agents are apparently effective in the treatment of dentine hypersensitivity. In particular, the literature supports the efficacy of strontium, potassium and fluoride containing toothpastes. This study was a double-blind, randomised, parallel group comparison of three products, namely strontium- and potassium-based desensitising toothpastes both containing fluoride, and a conventional fluoride toothpaste. A total of 131 subjects entered a 4-week wash-in phase using the conventional fluoride toothpaste, of whom 120 entered a 6-week treatment phase. Sensitive teeth were evaluated at wash-in baseline, treatment baseline and after 2 and 6 weeks use of the treatment pastes. Dentine hypersensitivity was assessed with tactile and cold air stimuli together with an overall subjective assessment. Analysis of the findings was performed using non-parametric statistical methods. Of the original 120 subjects, 112 completed the trial. All 3 toothpaste groups showed reductions in sensitivity over the 6 weeks; however, no significant differences were found between the three products at any given time. Interestingly, there was no significant change in sensitivity between wash-in baseline and treatment baseline for the cold air stimulus with the fluoride-only-based paste. However, for the group using the same fluoride toothpaste, there was significant improvement between wash-in baseline and week 6, and treatment baseline and week 6 for this stimulus, suggesting a substantial placebo effect occurred. There is a need for further investigation of a wash-in period and examination of the placebo effect when evaluating dentine hypersensitivity trials.

Self-applied treatments in the management of dentine hypersensitivity

A summary of the research on the different self-applied treatments for hypersensitive dentine provides some support for several agents but invalidates others. This is true for toothpastes, mouthwashes and gels. Direct comparison of studies is difficult because the materials and methods used are different. In addition, the size of patient groups, and methods of stimulation and assessment of the evoked pain reaction are different. Therefore our concept of the efficacy of self-applied treatment is not so much based on a homogeneous pool of data, but rather on a collection of individual studies. If we subtract from these data sets those based on obviously older ways of evaluating efficacy, we are left with surprisingly few studies that properly assess the efficacy of compounds suited to self-applied treatment. Therefore, guidelines should be established for testing such compounds, and publication of the data sets should depend on proper use of such designs. Stimuli, design and pain assessment should be standardized. In addition, patient recruitment could be defined better in relation to criteria for inclusion. Another area of concern is the pretreatment history of the hypersensitive teeth, because some teeth will become hypersensitive during the observation period, whilst others, which were hypersensitive, will spontaneously become insensitive. Therefore one should know the rate of spontaneous change in tooth sensitivity levels in each patient, in order not to assign treatment effects to teeth that would have lost their sensitivity anyway.

Assessment of pain in cervical dentinal sensitivity studies. A review

Traditionally cervical dentinal sensitivity (CDS) has been evaluated mainly subjectively on the basis of the individual patient's subjective response, e.g., in the form of verbal rating and visual analogue scales and questionnaires. The stimuli used for evaluating this response can be grouped into 4 main categories: mechanical, chemical, electrical and thermal. This review of the literature, however, indicates that there are problems in evaluating patient subjective response to these various test stimuli used in the assessment and treatment of CDS. Opinions also vary as to the reliability of some of these methods of assessment, although recently, efforts have been made to develop controlled reproducible stimuli more suited to the evaluation of CDS. Currently no single method of eliciting and assessing CDS may be considered ideal. Further research is required to evaluate suitable methodology for the quantification of realistic test stimuli under controlled clinical conditions, whereby the subjective response may be objectively measured by the investigator.

The effect of strontium chloride hexahydrate dentifrices on plaque accumulation and gingival inflammation

2 strontium chloride hexahydrate-containing dentifrices (SCH), similar except for their respective abrasive systems, diatomaceous earth or silica-based, were compared for their effects on plaque accumulation and gingival inflammation as part of a 2-month randomised double-blind parallel clinical study. No attempt was made to change the patients' oral hygiene prior to participation in the study. Plaque was assessed using the Silness & Löe index and the gingival condition by the Löe & Silness index GI. There was a slight and non-significant increase in plaque accumulation at 2 weeks from baseline, but relatively negligible change thereafter, the effect being identical in both groups. Similarly, the gingival condition showed a slight index change from baseline, although it tended to be slightly higher in the diatomaceous earth group. The results do not support the conclusions of previous studies which indicated that SCH dentifrices increased plaque accumulation. Neither plaque accumulation nor gingival condition significantly changed from baseline levels during the course of the study.

Dentine hypersensitivity: a review

Dentine hypersensitivity is a relatively common pain condition. Local pulpal inflammation, traumatic oral hygiene and dietary habits have been considered in the etiology of dentine hypersensitivity. Dentine hypersensitivity is probably caused by a change in fluid flow in the dentinal tubules, which in turn excites the nerve endings located at the pulp-dentine border. Consequently, treatment success would depend on the prevention of fluid flow across the dentinal tubules (sodium fluoride, stannous fluoride, sodium monofluorophosphate, strontium chloride, sodium citrate, potassium oxalate, and resins/adhesives), or on the desensitization of the nerve endings located at the pulp-dentine border (potassium nitrate). Although a wide variety of treatment methods have been available, clinical data is characterized with ambiguity, warranting further research of the factors which could possibly be implicated in the occurrence of dentine hypersensitivity.

The effectiveness of a patient-applied tooth desensitizing gel. A pilot study

Potassium nitrate has been found to be an effective ingredient for reducing dentinal hypersensitivity. The purpose of this study was to evaluate the effectiveness of a patient-applied 10% potassium nitrate glycerine-based gel in decreasing dentinal sensitivity on cold on teeth with exposed dentin apical to the cemento-enamel junction, 12 patients, each having 3 hypersensitive teeth, were tested. The patients were divided into 3 treatment groups: group 1 was treated with a glycerine-based 10% potassium nitrate gel: group 2 was treated with a glycerine gel without potassium nitrate; and group 3 received no gel and no treatment (control). Following brushing and flossing, groups 1 and 2 applied the gel to the test teeth using custom-made soft acrylic trays, for a period of 5 min/day for 4 weeks. Patient responses to cold water stimuli of 20 degrees C, 10 degrees C and 0 degrees C, were measured at baseline (week 0), then at 1-, 2-, 3- and 4-week intervals. Group 1 patients showed a significant decrease in sensitivity to cold at week 2 only. The group 2 patients showed a significant decrease in sensitivity to cold after 3 and 4 weeks. A statistically significant decrease in sensitivity was noted between group 2 and group 3 patients at week 3. The most sustained decrease in sensitivity to cold was found on teeth treated with plain glycerine.

Effect of a desensitizing dentifrice on dentinal hypersensitivity

The objective of this study was to assess the effectiveness of a dentifrice with 2% dibasic sodium citrate in poloxamer 407 in decreasing dentinal hypersensitivity. The test toothpaste was compared with a control toothpaste containing 0.76% sodium monofluorophosphate in a 6-week double-blind clinical trial. A total of 75 hypersensitive teeth were examined in the test group, while 100 hypersensitive teeth were in the control group. Changes in hypersensitivity levels were monitored after 6 weeks, using thermal, chemical and mechanical stimuli. At the end of 6 weeks, the test dentifrice was not significantly more effective than the control in decreasing dentinal hypersensitivity. Of the stimuli used, cold was the most effective in eliciting a hypersensitive response, followed by chemical stimulation and air. Heat and toothbrushing caused the least discomfort.

Clinical effectiveness of a dentifrice containing fluoride and a citrate buffer system for treatment of dentinal sensitivity

Four test dentifrices were evaluated in a double-blind investigation to determine their effect on dentinal sensitivity in 87 adult human participants. Baseline data were obtained by patient questionnaire, dental examination and by soliciting subjective responses to controlled osmotic, thermal and tactile stimuli. The four dentifrices were: (1) a placebo dentifrice, (2) a fluoride dentifrice containing 0.1% fluoride, (3) a 2% citrate buffered dentifrice in a pluronic gel and (4) a dentifrice containing 0.1% fluoride and 2% citrate buffer in a pluronic gel. Precipitated silica provided the abrasive for all dentifrices. Dentifrices were supplied to participants on a random basis, and participants were instructed to brush twice daily for 8 weeks. Responses to the three stimuli as accomplished at baseline were obtained at 2, 4 and 8 weeks on 81 participants. A statistically significant stimulus reduction was found between treatment groups to thermal stimulus at the 2-month interval (P = 0.048) and to the tactile stimulus at 2 weeks (P = 0.019). Both the citrate dentifrice and the citrate/fluoride dentifrices demonstrated significant efficiency in reducing sensitivity.

Hypersensitive teeth. Part II: Treatment

If the hydrodynamic theory for pain transmission were accepted, occlusion of the patent dentinal tubules would appear to be essential for treatment efficacy. There are many compounds with seemingly varied chemical forms that have been shown to be effective. Their exact mode of action however, is not clearly defined because well-designed, nonbiased, and controlled comparison studies between agents are lacking. The various toothpastes may have ingredients that actually occlude patent tubules or they may cause secondary desensitization by irrational or abrasive action. In any pain study, the nature of the placebo effect and other psychogenic factors play a significant role. Fluoride preparation with and without iontophoresis has been shown to alter tubule structure and form microprecipitates. The natural desensitization process, although slow, is nature's protection, allowing dentinal sclerosis of secondary dentin formation. Although the resin-adhesive systems, especially the new light-cured dentin bonding agents, appear immediately to be effective, the effect on the pulp remains unknown. Perhaps a combination of iontophoresis with sodium fluoride and light-cured dentin bonding material may yield protection and desensitization at a high level of predictability. With the population trends toward a more geriatric society, further research, knowledge, and understanding of dentinal hypersensitivity is of paramount importance. The expected increase in longevity of the dentition suggests that dentin exposure and sensitivity will increase as a clinical problem. There is a clear time-age relationship involved in gingival recession, erosion and attrition of the teeth, and the need for periodontal surgical therapy. For total comprehensive care, patient comfort is important and should be provided along with sound periodontal health and ideal restorative function.

Dentin permeability. Effects of desensitizing dentifrices in vitro

Patients using placebo dentifrices in clinical trials usually show a significant decrease in dentin sensitivity over a 2- to 4-week period. If their sensitivity were due to hydrodynamic fluid movement, then the results suggest that there was a decrease in their dentin permeability. This hypothesis was tested in vitro by measuring the ease with which fluid could flow (i.e., hydraulic conductance) across dentin discs before and after brushing the discs with a variety of dentifrices, including most of the marketed densensitizing dentifrices. All dentifrices decreased the hydraulic conductance of dentin. An experimental dentifrice containing oxalate as the active ingredient was far more effective than any of the marketed dentifrices. The results tend to support the hypothesis that, at least part of the reduction in clinical sensitivity in patients with hypersensitive dentin is due to the abrasive action of the dentifrice.

Effectiveness of sodium fluoride on tooth hypersensitivity with and without iontophoresis

Effectiveness of iontophoresis with and without electric current and sodium fluoride on tooth hypersensitivity was evaluated. In eleven volunteers, teeth received a 2% neutral sodium fluoride solution applied using an electrode phoresor. Test teeth received the solution with current and control teeth received the solution without current. The subjects were tested at Day 0 and 7 by means of a mechanical stimulating device and a temperature probe. The data were then analyzed using X2 analysis. Statistically, the test teeth demonstrated more improvement than the control teeth.

Dentine hypersensitivity--a review. Clinical and in vitro evaluation of treatment agents

A large number of compounds have been employed in the management of dentine hypersensitivity. The symptomatic nature of the condition and its variability poses many problems to any evaluation of effect. Several semi-quantitative methods of response have been used; however, at this time it is uncertain what advantages they hold over the patients' subjective assessment of improvement. A review of the clinical studies reveals that a positive result for every agent tested to date may be found. Nevertheless considerable placebo responses have been obtained and equivocal results are occasionally reported. The fluorides and metal salts, particularly of strontium, have been most studied when used either in solution or delivered in toothpaste formulations. For these compounds the literature contains considerable information concerning the reaction with dental hard tissues which can be extrapolated into hypotheses for the modes of action in relieving dentine hypersensitivity. Moreover, some in vitro studies provide useful information concerning the effects of certain compounds on dentine, and are consistent with the clinical data. Unfortunately, contradictory findings and anomalies between clinical and in vitro effects still prevent the development of a sound clinical basis for the treatment of the condition. Moreover, there is a need to recognise those factors which predispose to dentine exposure, if the prevention of the occurrence or re-occurrence of hypersensitivity is to be achieved.

The effectiveness of an electro-ionizing toothbrush in the control of dentinal hypersensitivity

The object of the investigation was to test the value of the 3M Brand Electro-Ionizing Toothbrush in the treatment of dentinal hypersensitivity. Eighty-eight volunteers were divided into three groups, each using different methods: (I) stannous fluoride dentifrice and 3M brush without a battery; (II) stannous fluoride dentifrice and 3M brush with a 1 1/2 volt battery; and (III) strontium chloride dentifrice and 3M brush without a battery. The volunteers brushed their teeth for 3 minutes twice a day for 12 weeks using one of the three test agents. The subjects were tested at weeks 0, 2, 4, 8 and 12 by means of a cold water spray quantitated by a temperature probe. All three groups experienced improvement and by week 12 Groups II and III displayed much less sensitivity than did Group I. At the end of the 12 weeks the subjects were questioned as to benefit of treatment. The questionnaire revealed that stannous fluoride with the ionizing brush provided significantly greater relief than did the stannous fluoride alone.