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Biomedical subjects

J M Thomason

Publications and source records attributed to J M Thomason.

At least 55 records · Page 3Linked to original sources
PubMed1996

Automated gas chromatographic assay for amlodipine in plasma and gingival crevicular fluid.

This paper describes an automated capillary gas chromatographic method for the determination of amlodipine in plasma, and in sub-microlitre volumes of gingival crevicular fluid (GCF), in order to assess if amlodipine is present in GCF under conditions of gingival overgrowth, as has been shown for nifedipine, another dihydropyridine drug. Liquid-liquid extraction followed by derivatisation was employed to isolate amlodipine and render it suitable for gas chromatography. Amlodipine was analysed in plasma and GCF of four patients undergoing amlodipine therapy for cardiovascular disorders, three of whom had significant gingival overgrowth. Amlodipine was detected in the plasma of all patients and in massive concentrations in the GCF of those patients with overgrowth, 23- to 290-fold greater than in their plasma. Like nifedipine, amlodipine sequestration into GCF appears to be linked with gingival overgrowth.

Amlodipine↗
PubMed1996

The distribution of gingival overgrowth in organ transplant patients.

The distribution of gingival overgrowth was investigated in a cohort of organ transplant patients, who were medicated with cyclosporin or the combination of cyclosporin and a calcium channel blocking drug. Gingival overgrowth scores were significantly higher at buccal sites than lingual-palatally (p < 0.0001). There was no significant difference between upper and lower overgrowth scores (p = 0.88). The most severe overgrowth was seen in the canine region. Overgrowth between the central incisors was significantly less than in the canine region (p > or = 0.044) and was similar to that in the molar and premolar region. Although raised overgrowth scores were associated with increased levels of plaque and gingival inflammation, the distribution could not be explained by this observation.

Analysis of Variance↗
PubMed1996

Determinants of gingival overgrowth severity in organ transplant patients. An examination of the rôle of HLA phenotype.

The role of HLA phenotype as a risk factor for drug-induced gingival overgrowth was investigated in a cohort of 172 transplant recipients. Clinically significant overgrowth warranting surgical correction was observed in 72 patients (42%). Using stepwise regression modelling, 6 clinical parameters were identified as significant risk factors for the severity of gingival overgrowth. These were; age, sex, creatinine plasma level, duration of therapy, papilla bleeding index and concomitant medication with a calcium channel blocking drug. 3 HLA alleles were also identified as risk factors when adjusted for other clinically significant risk factors (HLA -DR2, A24, B37). However, when the p-values for the HLA variables were corrected to compensate for the use of multiple significance testing, only HLA-B37 remained statistically significant at the 5% level. Organ transplant patients are at risk of developing gingival overgrowth, with approximately 25% medicated with cyclosporin alone requiring corrective gingival surgery. This figure more than doubles in patients concomitantly medicated with a calcium blocking drug. The data at present available would suggest that the severity of gingival overgrowth is also significantly associated with the HLA-B37 phenotype.

Adolescent↗
PubMed1996

The pathogenesis of drug-induced gingival overgrowth.

Gingival overgrowth is a well-documented unwanted effect, associated with phenytoin, cyclosporin, and the calcium channel blockers. The pathogenesis of drug-induced gingival overgrowth is uncertain, and there appears to be no unifying hypothesis that links together the 3 commonly implicated drugs. In this review, we consider a multifactorial model which expands on the interaction between drug and/or metabolite, with the gingival fibroblasts. Factors which impact upon this model include age, genetic predisposition, pharmacokinetic variables, plaque-induced inflammatory and immunological changes and activation of growth factors. Of these, genetic factors which give rise to fibroblast heterogeneity, gingival inflammation, and pharmacokinetic variables appear to be significant in the expression of gingival overgrowth. A more thorough understanding of the pathogenesis of this unwanted effect will hopefully elucidate appropriate mechanisms for its control.

Adult↗
PubMed1995

The influence of denture design on patient acceptance of partial dentures.

A study was designed to investigate the influence of denture design on patient acceptance of partial dentures. A total of 317 patients provided with partial dentures by the Department of Prosthodontics, Newcastle Dental School 2-3 years previously, were asked to complete a postal questionnaire about their use of these dentures. Denture status and partial denture design for these patients was established using hospital records. Design variables included material, the number and distribution of replaced teeth, denture support and connector design. In all, 86% of patients (273) returned the questionnaire. A total of 393 partial dentures (210 upper, 183 lower) had been constructed for these patients; 99 (25%) dentures were never worn and a further 57 (15%) dentures were only worn occasionally. Non-wearers were more likely to have no replacement anterior teeth, fewer replacement teeth and, in the lower, a lingual bar. When a multivariate model including all recorded variables was constructed using multiple logistic regression analysis, the presence of anterior replacement teeth for all dentures and the number of replacement teeth for upper dentures were found to be the only significant positive influences on denture wearing. Use of a lingual bar did not influence denture wearing habits.

Adult↗
PubMed1995

Periodontal variables affecting nifedipine sequestration in gingival crevicular fluid.

We previously demonstrated the sequestration of nifedipine in gingival crevicular fluid (GCF), especially in patients exhibiting significant gingival overgrowth. The aim of the present study is to determine the role of site specific periodontal factors in this phenomenon. 10 adult patients exhibiting nifedipine induced gingival overgrowth were studied. In each patient GCF was harvested from two sites that demonstrated inflammation and increased probing depth as well as from two clinically healthy sites. The concentration of nifedipine was determined using gas chromatography. Drug concentrations were significantly increased in the presence of inflammation (p = 0.004) and plaque (p = 0.029) whilst increased probing depths and gingival overgrowth were not significantly related to drug sequestration. We can conclude that inflammatory changes in gingival tissues appear to be a significant determinant for the sequestration of nifedipine in the GCF.

Adult↗
PubMed1995

Iatrogenic gingival overgrowth in cardiac transplantation.

It is well established that both cyclosporin and nifedipine are associated with gingival overgrowth. Although both drugs are widely used in the management of organ transplant patients, there is little information on the prevalence and severity of this unwanted effect in cardiac transplant patients. This study evaluated the gingival health of 94 dentate cardiac transplant patients, all of whom were medicated with cyclosporin as a component of their immunosuppressive therapy. Sixty-three (63) of the patients were also medicated with nifedipine. Significantly higher gingival overgrowth scores (P < 0.0001) and periodontal probing depths (P = 0.001) were observed in patients medicated with the combination of cyclosporin and nifedipine than those medicated with cyclosporin alone. Likewise, there was a significantly greater need to carry out gingival surgery on patients taking the combination (62%), than those medicated with cyclosporin alone (25.8%) (P = 0.001). Patient's age, sex, duration of therapy, gingival bleeding index, and nifedipine therapy were important determinants for both the expression of gingival overgrowth and the need for surgery. Significant sequestration of nifedipine in the gingival crevicular fluid (GCF) was observed. The concentration of nifedipine in GCF did not relate to either the gingival changes or plasma concentration of the drug. Cardiac transplant patients are at risk of developing gingival overgrowth and approximately 50% require surgical intervention. This risk increases significantly when patients are medicated concomitantly with nifedipine.

Adolescent↗
PubMed1995

The use of cantilever bridges.

Replacement of missing teeth with fixed bridgework often involves producing full crown retainers on teeth on both sides of an edentulous space. Unfortunately, this approach can result in the destruction of much healthy tooth tissue, and the clinician must balance the benefits of replacing missing teeth with the amount of tooth preparation required. Current thinking in restorative dentistry places the preservation of tooth tissue at a premium, and most practitioners are happy to use techniques that embrace this philosophy. Because of this, cantilever bridges have an increasing role in dental practice, where the replacement for a missing tooth or teeth has one or more abutments on only one side of the edentulous space, being unsupported at the other. Cantilever bridges fall into several types, depending on the number of abutments and types of retainers. This article describes the various cantilever bridge designs, considers the biomechanics of these restorations, and provides guidelines for their clinical use.

Biomechanical Phenomena↗
PubMed1994

The provision of prostheses for patients with severe limitation in opening of the mouth.

The problem of providing prostheses for patients with restricted mandibular opening is not well reported, either in current texts on prosthodontics or in the literature. This report features two patients who suffer from severe and chronic forms of the disorder. The aim of the article is to provide some useful hints with respect to the prosthetic management of such patients.

Dental Impression Technique↗
PubMed1994

Amlodipine-induced gingival overgrowth.

Amlodipine is a calcium channel blocker used in the management of angina and hypertension. We report 3 cases of gingival overgrowth in adult dentate patients associated with chronic usage of this drug. Gingival changes occurred within 3 months of dosage and appeared to be compounded by the patient's existing periodontal condition. In all 3 patients, there was sequestration of amlodipine in their crevicular fluid. The significance of this finding in relation to the pathogenesis of this unwanted effect remains to be elucidated.

Adult↗
PubMed1994

The periodontal problems and management of the renal transplant patient.

This review considers the periodontal problems of renal transplant patients with particular reference to their drug therapy and the pretransplant uremia. It would appear that either disease- or drug-induced immunosuppression affords the renal transplant patient a degree of "protection" against periodontal breakdown. However, of more significance to the periodontologist is the problem of drug-induced gingival overgrowth with reference to both cyclosporin and nifedipine. Approximately 30% of dentate renal transplant patients medicated with cyclosporin alone experience significant gingival overgrowth which requires surgical excision. This figure increases to 40% when patients are medicated with both drugs. The pathogenesis of this unwanted effect is uncertain and the relationship between the expression of gingival overgrowth and various periodontal or pharmacokinetic variables remains a contentious issue. Clinical measures to prevent the occurrence of either cyclosporin- or nifedipine-induced gingival overgrowth are unsatisfactory.

Chronic Disease↗
PubMed1994

Oral and dental problems in the organ transplant patient.

The number of people receiving organ transplants has dramatically increased over the last decade. It is now likely that a dental surgeon will come across patients who have undergone transplantation. This paper considers the particular problems that these patients are likely to present their general dental practitioners.

Anti-Bacterial Agents↗
PubMed1993

The prevalence and severity of cyclosporin and nifedipine-induced gingival overgrowth.

The gingival health of 32 renal transplant patients who were medicated with cyclosporin was compared with a similar cohort of 23 renal transplant patients medicated with both cyclosporin and nifedipine. Both groups of patients had been taking the above medication for at least 3 months. Plaque scores, gingival inflammation and probing depths were similar for both groups. Patients medicated with the combination of nifedipine and cyclosporin had a significantly higher gingival overgrowth score (p = 0.046) when compared with the group receiving cyclosporin alone. The incidence of clinically significant overgrowth (i.e., overgrowth > 30% which would require surgical intervention) was similar in both groups. Gingival overgrowth was not related to cyclosporin dosage. It is concluded that patients taking cyclosporin or cyclosporin and nifedipine experience gingival overgrowth and that the severity of the overgrowth is greater in patients taking the combined therapy. The levels of plaque and gingival inflammation appear to be associated with this phenomenon.

Adult↗
PubMed1993

Drug-induced gingival overgrowth and its management.

Gingival overgrowth is associated with the chronic usage of phenytoin, cyclosporin and the dihydropyridines. The pathogenesis of this unwanted effect is uncertain but appears to be enhanced by plaque-induced gingival inflammation. Certain patients appear to be more susceptible to gingival overgrowth and this may be related to gingival fibroblast phenotypes. In most cases, treatment involves surgical excision, followed by a concentrated oral hygiene programme. Recurrence of gingival overgrowth is a persistent problem particularly in the 'responder' patients. If an alternative, suitable medication is available, it may be worth while considering such a change through consultation with the patient's physician. Since patients are retaining their teeth into old age, the prevalence of this unwanted effect is likely to increase.

Calcium Channel Blockers↗
PubMed1992

The incidence and severity of nifedipine-induced gingival overgrowth.

The gingival health of 19 patients with cardiovascular problems who were medicated with nifedipine was compared with a similar cohort treated with atenolol and a control group of healthy patients. In the nifedipine and atenolol groups, patients had been taking their respective medication for a minimum period of 6 months. Plaque scores were similar for all three groups. However, patients medicated with nifedipine had a significantly higher gingival index (P less than 0.005), gingival overgrowth scores (P less than 0.02) and probing sites greater than 3 mm (P less than 0.005) when compared with the atenolol and control groups. 4 patients in the nifedipine group experienced clinically significant gingival overgrowth which required surgical excision. Gingival changes in the nifedipine patients were not related to drug dosage or plaque scores. It is concluded that nifedipine therapy results in significant gingival changes, an effect which may be mediated by the drug's action on calcium transport.

Atenolol↗