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Biomedical subjects

D G Gillam

Publications and source records attributed to D G Gillam.

32 records · Page 2Linked to original sources
PubMed1997

The Dentin Disc surface: a plausible model for dentin physiology and dentin sensitivity evaluation.

Dentin sensitivity (DS) is a painful clinical condition which may affect 8-35% of the population. Various treatment modalities have claimed success in relieving DS, although at present there does not appear to be a universally accepted desensitizing agent. Current opinion based on Brännström's Hydrodynamic Theory would suggest that following exposure of the dentin surface (through attrition, abrasion, or erosion), the presence of open dentinal tubules, patent to the pulp, may be a prerequisite for DS. The concept of tubule occlusion as a method of dentin desensitization, therefore, is a logical conclusion from the hydrodynamic theory. The fact that many of the agents used clinically to desensitize dentin are also effective in reducing dentin permeability tends to support the hydrodynamic theory. This paper reviews the in vitro evaluation of desensitizing agents, the techniques used to characterize their effects on the prepared dentin surface, and the ability of these agents to reduce permeability through tubule occlusion, and presents recent findings from ongoing research based on the Pashley Dentin Disc model. It can be concluded that the use of this model to determine surface characteristics, and reductions in dentin permeability through tubule narrowing or occlusion, provides a useful screening method for evaluating potential desensitizing agents. Interpreting changes observed in vitro is difficult, and extrapolation to the clinical situation must be tempered with caution.

Animals↗
PubMed1997

An investigation of potential desensitizing agents in the dentine disc model: a scanning electron microscopy study.

Cervical dentine sensitivity (CDS) may be defined as pain arising from exposed dentine. The prefix cervical indicates the location of the sensitivity and/or its subsequent treatment. Currently the most accepted mechanism of intradental nerve activation associated with dentine sensitivity appears to be hydrodynamic in nature. The concept of tubule occlusion as a method of dentine desensitization is a logical conclusion of the hydrodynamic theory. The authors employed the dentine disc model, qualitative scanning electron microscopy (SEM) and X-ray microanalysis to investigate whether selected desensitizing agents occlude dentinal tubule orifices. Strict control procedures have been used together with various methods of application to apply these agents to human dentine discs. SEM was used to examine the degree of deposit left by the various agents on disc surfaces and X-ray microanalysis was employed to characterize the elemental composition of the deposit. Analysis of selected agents, both prior to and after application on dentine discs was performed for comparative purposes. The degree of retention of the surface deposit upon rotation with saliva supernatant for 6 h was also studied. The results of this study indicated that ferric oxalate, the active ingredient of Sensodyne Sealant, which produced initial crystal-like structures, occluding almost all the tubule orifices was superior to potassium oxalate (Butler Protect). Of the over-the-counter (OTC) desensitizing products tested, both silica- and calcium-based abrasive components were observed both on the surface and within the tubules, indicating a certain degree of therapeutic potential for these two components. These findings suggest that certain desensitizing agents have tubule occluding properties as observed in this in vitro system which, in turn, may indicate a therapeutic potential in vivo.

Calcium↗
PubMed1997

A pilot assessment of alternative methods of quantifying dental pain with particular reference to dentine hypersensitivity.

OBJECTIVE: The overall aim of this pilot study was to establish the usefulness and comparability of selected verbal and non-verbal methods in the quantification of sensory and affective aspects of dental pain associated with dentine hypersensitivity (DH). DESIGN: The assessment of dental pain was conducted during an eight week clinical study. Patients were asked to rate their perception of dental pain using selected methods of quantification following tactile (Yeaple Probe-an electronic pressure-sensitive probe) and evaporative (cold air from a dental air syringe) stimulation; together with an overall assessment of perception to daily stimuli (e.g., cold air/water, toothbrushing, sweet and sour foods). The assessment methods used to quantify pain arising from DH were a continuous visual analogue scale (VAS), a 0-10 numerical rating VAS scale (NRS), and a separate intensity verbal descriptor (IVD) and unpleasantness verbal descriptor (UVD) word scales. SETTING: A specialist department at a postgraduate dental institute and hospital in London, UK. SUBJECTS: Twenty-five adult patients (8M + 17F) with a mean age of 42.6 years (95 per cent C.I. 38.8 to 46.4 years) attending the department for a clinical study evaluating the efficacy of a desensitising toothpaste agreed to participate. OUTCOME MEASURES: The study compared a continuous visual analogue scale (VAS), a 0-10 numerical rating visual analogue scale (NRS), and a separate intensity (IVD) and unpleasantness verbal descriptor (UVD) scales to quantify sensory and affective aspects of pain. An unweighted moving average technique was used to construct graphs of the relative frequency of reported severity gradings over a range of 0-10. RESULTS: The results of the study indicated that cold air appeared to cause greater discomfort to the patient than tactile sensitivity, with the air intensity curve for both IVD and 0-10 VAS peaking at a severity score of 5 while continuous VAS peaked at a score of 3-4. All methods peaked at score 2 for tactile sensitivity. The UVD scale peaked at score 2-3 and again at 6 for air sensitivity, but conformed to the other scales by peaking at score 2 for tactile sensitivity. NRS and IVD scales therefore appeared to provide acceptable alternatives to continuous VAS, but the UVD scale, probably because of the imprecise nature of the words used in the scale, did not. CONCLUSIONS: This study partially confirms previous conclusions that both verbal and non-verbal techniques quantify sensory and affective aspects of pain. However, the imprecise nature of UVD words provided misleading information in terms of both accuracy and sensitivity (except at very low levels of discomfort), when assessing pain arising from dentine hypersensitivity. In view of the highly subjective data arising from studies of this nature, the use of a moving average technique may be considered a more pragmatic method of analysis.

Adult↗
PubMed1997

Clinical trial designs for testing of products for dentine hypersensitivity--a review.

Dentine hypersensitivity (DH) is a perplexing clinical entity. There is no doubt that patients self-report discomfort arising from various stimuli, but the highly subjective nature of the condition makes it extremely difficult to evaluate DH objectively. This is particularly true when evaluating the efficacy of desensitizing agents in the clinical trial setting. This paper attempts to provide an overview on clinical trial management to evaluate both in-office and over-the-counter (OTC) desensitizing agents. The importance of correct clinical trial design (type, allocation, blinding) with emphasis on patient selection, sample size, statistical power, duration, choice of positive/negative controls, treatment outcomes, and data collection, will be discussed.

Clinical Trials as Topic↗
PubMed1996

Prevalence of cervical dentine sensitivity in a population of patients referred to a specialist Periodontology Department.

The reported prevalence of cervical dentine sensitivity (CDS) ranges from 8 to 35%. Detailed epidemiology of the condition, particularly with regard to possible causal factors, is lacking. In particular, no published data appear to exist on its prevalence in periodontal patients. The aim of the present study was therefore to determine the prevalence, distribution and severity of CDS in a population of patients referred to a Periodontology Department of a specialist postgraduate hospital. 507 patients (181 M; 326F, mean age 44.2 (SD 10.31) years) attending a periodontal clinic were assessed for CDS by a questionnaire. The results demonstrated a prevalence of CDS of 84% with no significant gender difference. 71.1% of patients perceived cold as the most common cause of discomfort. A higher prevalence of self-reported discomfort was observed between 40 and 49 years. Of the patients with a reported history of periodontal surgery (34.7%), those treated within 6 months prior to assessment appeared to be more at risk to CDS. Of the patients who received hygienist treatment (88.2%), only 10.5% reported discomfort persisting > or = 3 days after treatment. Generally, patients who complained of varying degrees of discomfort over time (84.5%) did not perceive the condition as severe and consequently did not seek treatment. The prevalence of CDS in these referred patients was very high, suggesting that periodontal diseases and/or treatment effects play a rôle in its aetiology.

Adult↗
PubMed1996

Efficacy of a potassium nitrate mouthwash in alleviating cervical dentine sensitivity (CDS).

Potassium nitrate (KNO3) has been used previously in a dentifrice or gel to alleviate cervical dentine sensitivity (CDS). The aim of this study was to compare a 3% KNO3 Silica/NaF mouthwash with a NaF/silica mouthwash in a 6-week multi-centre double-blind study. 47 subjects (12M; 35F, mean age 36.2 (SD 11.46) years) participated in the study. Subjects were evaluated for tactile (Yeaple probe) and air sensitivity (dental air syringe) together with subjective perception of pain (0-10 scale) at 0, 2 and 6 weeks. Results for Yeaple probe (gm wt) (Wilcoxon paired rank test) between 6 weeks and baseline, were highly significant for both groups. Differences between groups at 6 weeks were statistically significant. Subjective Yeaple probe scores (paired t-tests) between 6 weeks and baseline were significant for both groups. There were no significant differences (unpaired t-tests) between groups over 6 weeks for subjective Yeaple probe scores. Subjective air scores (paired t-tests) between 6 weeks and baseline were significant for both groups. There were significant differences (unpaired t-tests) between groups in favour of the 3% KNO3/Silica/NaF group at 6 weeks. The 2 weeks and baseline results for both groups were the same as reported for 6 weeks and baseline. The results demonstrated that a 3% KNO3/Silica/NaF mouthwash compared to a Silica/NaF control significantly reduced CDS when evaluated by tactile and thermal stimuli. A 3% KNO3/silica/NaF mouthwash would, therefore appear to have therapeutic potential to alleviate CDS.

Adolescent↗
PubMed1996

Comparison of 2 desensitizing dentifrices with a commercially available fluoride dentifrice in alleviating cervical dentine sensitivity.

Previous studies have demonstrated efficacy of desensitizing dentifrices containing strontium acetate/sodium fluoride (SrAc2F) and potassium chloride/sodium monofluorophosphate (KCl/MFP) in alleviating discomfort arising from cervical dentine sensitivity (CDS). The aim of this investigation, therefore, was to determine efficacy of a SrAc2F dentifrice compared with KCl/MFP and a commercially available fluoride dentifrice containing sodium fluoride/sodium monofluorophosphate (NaMFP). Fifty-six patients participated in a 2-center double-blind, 3-way comparative parallel 6-week clinical study. Patients were evaluated at 0, 2, and 6 weeks for tactile (Yeaple probe), air sensitivity (dental air syringe), and subjective perception of pain (VAS scores). Results for Yeaple probe scores (Wilcoxon tests) between 2 weeks and baseline were highly significant for KCl/MFP, significant for NaMFP and nonsignificant for SrAc2F; scores between 6 weeks and baseline were, however, highly significant for all groups. Subjective Yeaple probe VAS scores (paired t-tests) between 6 weeks and baseline were significant for all groups; significance was demonstrated in the KCl/MFP group between 2 weeks and baseline. Subjective air visual analogue scores (paired t-tests) between 2 weeks and baseline were highly significant for all groups. There were no significant differences between groups at any time point. The results of the study demonstrated that the commercially available fluoride-containing dentifrice was as effective as the 2 desensitizing dentifrices in alleviating CDS over time.

Acetates↗
PubMed1996

The effectiveness of desensitizing agents for the treatment of cervical dentine sensitivity (CDS)--a review.

The treatment of dentine sensitivity or cervical dentine sensitivity (CDS) has been in the form of dentifrices, mouth rinses, sealants, and other therapeutic techniques. Claims of efficacy of the "so-called" active ingredients of these desensitizing agents have been made on the basis of the proposed mode of action generally extrapolated from in vitro or animal studies. Evidence from published, well-controlled clinical studies, however, generally has failed to substantiate such claims, although there has been a reported significant reduction in discomfort by subjects participating in these studies. Currently, the most accepted mechanism of intradental nerve activity associated with dentine sensitivity appears to be hydrodynamic in nature, although other mechanisms cannot be eliminated. The concept of tubule occlusion as a method of dentine desensitization is a logical conclusion from the hydrodynamic hypothesis. This paper reviews the present position with regard to the treatment of dentine sensitivity by various desensitizing agents and evaluates their claims of efficacy in the context of available scientific evidence.

Animals↗
PubMed1995

Mechanisms of stimulus transmission across dentin--a review.

Several investigators have demonstrated that intradental A-type (A beta and A delta) nerve fibers are responsible for the sensitivity of dentin and that the endings of the responding fibers are located in the pulp-dentin area of the tooth. The exact mode of transmission of stimuli (e.g., thermal, chemical, mechanical, etc.) across dentin, however, is still unclear, although several hypotheses have been proposed. These include direct nerve stimulation, dentinal receptor (transducer/modulation), hydrodynamic, and direct ionic diffusion hypotheses. Currently, the most accepted mechanism of intradental nerve activation associated with dentin sensitivity appears to be hydrodynamic in nature, although alternative mechanisms of transmission (e.g., direct ionic diffusion) cannot be ruled out. Recent investigations (in the cat), however, appear to provide evidence substantiating the hydrodynamic hypothesis.

Animals↗
PubMed1993

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.

Air Pressure↗
PubMed1992

Clinical efficacy of a low abrasive dentifrice for the relief of cervical dentinal hypersensitivity.

2 strontium chloride hexahydrate-containing dentifrices (SCH), similar except for their respective abrasive systems, were compared in a 2-month randomised double-blind parallel clinical study to evaluate their comparative effectiveness in terms of cervical dentinal hypersensitivity. 2 groups of 20 subjects, each with cervical dentinal hypersensitivity, were evaluated for tactile sensitivity by Yeaple probe, air sensitivity using a dental air syringe and subjective perception of pain by means of a visual analogue scale. There was no difference between the dentifrices as regards reduction of cervical dentinal hypersensitivity at each time point. The response to both dentifrices was evident within 4 weeks of use and the degree of improvement increased throughout the 8-week study period. The results support the conclusion that changing the abrasive component of SCH dentifrices did not significantly increase or decrease the (desensitizing) activity of the original product.

Adult↗
PubMed1992

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.

Adult↗
PubMed1992

Dentifrice abrasivity and cervical dentinal hypersensitivity. Results 12 weeks following cessation of 8 weeks' supervised use.

Following an 8-week controlled investigation of 2 strontium chloride hexahydrate dentifrices (SCH) of differing abrasivity, 2 groups of 20 subjects each, with cervical dentinal hypersensitivity, were re-examined at 20 weeks; that is, 12 weeks after the active period. The examination procedures were conducted in the same manner as in the main clinical trial. Sensitivity levels were assessed by 2 instrument methods: tactile (Yeaple probe), and cold air (dental air syringe), and by subjective perception of pain by means of a Visual Analogue Scale. The results from these methods of assessment demonstrated that 12 weeks following the cessation of 8 weeks' controlled use of standard and low abrasive SCH dentifrices, sensitivity levels reversed on slightly in both groups and, overall, sensitivity remained significantly lower than at baseline. The abrasivity of the dentifrice did not affect the desensitivity activity.

Adult↗