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Biomedical subjects

R G Newcombe

Publications and source records attributed to R G Newcombe.

At least 55 records · Page 3Linked to original sources
PubMed2002

Adjunctive effects to non-surgical periodontal therapy of systemic metronidazole and amoxycillin alone and combined. A placebo controlled study.

BACKGROUND AND AIM: Several studies have reported adjunctive benefits to scaling and root planing (SRP) of systemic amoxycillin and metronidazole in the treatment of periodontal diseases. To date no comparisons have been made of these antimicrobials alone or in combination. The aim of this study was to compare the adjunctive benefits to SRP of amoxycillin and metronidazole alone and combined. METHODS: 66 subjects <46 years of age with advanced chronic periodontal disease participated in this randomised, double blind, 4 parallel treatment group designed study. All subjects received quadrant SRP and then were prescribed amoxycillin capsules (250 mg) and metronidazole tablets (200 mg) (AM) or lactate capsules and metronidazole (PM) or amoxycillin and calcium lactate tablets (AP) or lactate and calcium lactate (PP). All medication was 3 of each per day for 7 days. Subgingival plaque samples were obtained and probing depth (PD), loss of attachment (LOA), bleeding on probing (BOP), suppuration (SUPP) and plaque (DEP) were recorded pre-treatment, 1, 3 and 6 months post-treatment. RESULTS: Final group sizes were: AM=15, PM=16, AP=16 and PP=15. PD improved in all groups. Treatment effects were highly significantly different and always greatest in the AM and least in the PP groups. Benefits of PM and AP over PP were also noted. LOA improved in all groups and showed the same highly significant treatment differences, again favouring AM. BOP improved in all groups, particularly in AM compared to the other groups. SUPP improved in all groups and was virtually eradicated in AM with differences among treatments highly significant. DEP changed little in any group and there were no significant differences among groups. Microbiological data showed significant differences in favour of AM compared to PP and PM for total aerobes and anaerobes at 1 month. P. intermedia counts were always lower in active groups compared to PP and reached significance for AM and AP at 1 month and AM and PM at 3 months. CONCLUSION: The significant differences among treatment groups and the overall trend in the data, in line with other studies, support the considerable adjunctive benefits to SRP of amoxycillin and metronidazole combined in the treatment of advanced chronic periodontal disease.

Adult↗
PubMed2002

A comparison of the plaque-inhibitory properties of stannous fluoride and low-concentration chlorhexidine mouthrinses.

BACKGROUND: Plaque inhibition by chlorhexidine (CHX) rinses is dose related with a relatively flat dose-response curve above 5-6 mg twice daily. Low dose regimens could therefore reduce local side effects but maintain reasonable efficacy. AIMS: To compare the plaque inhibitory properties of two low-dose CHX rinse products with more conventional levels delivered from proprietary rinses. A secondary outcome was a comparison with a stannous fluoride/amine fluoride (SFAF) rinse product. METHODS: The study was a five-treatments, negative controlled, randomised, single blind crossover design balanced for residual effects, involving 20 healthy subjects in a 24-h plaque re-growth model. On day 1 of each study period, subjects were rendered plaque free, suspended tooth cleaning and followed the appropriate rinse regimen. On day 2, subjects were scored for plaque by index and area. The rinse codes and rinsing regimens were: (A) 15 mg CHX 2 x daily for 30 s (0.1% CHX), (B) 9 mg CHX 2 x daily for 60 s (0.06% CHX), (C) 10 ml SFAF rinse 1 x daily for 30 s, (D) 15 ml placebo 2 x daily for 60 s, and (E) 6 mg CHX 2 x daily for 30 s (0.06% CHX). RESULTS: Average mouth plaque indices and areas were highly significantly different between rinsing regimens. All test rinses were significantly more effective than the placebo rinse. There was a mean dose-response pattern for the CHX rinses, but there were no statistically significant differences between any of the test rinses. CONCLUSIONS: Lower doses of chlorhexidine in rinses can be used to exert plaque inhibition comparable with products used at higher doses and equivalent to benchmark products such as the SFAF rinse. However, the availability of chlorhexidine from formulations has to be considered as in part explaining the results.

Adult↗
PubMed2002

Evaluation of axillary lymph nodes using touch imprint cytology and immunohistochemistry.

BACKGROUND: The success of sentinel node biopsy in determining axillary lymph node status necessitates an accurate and rapid method for intraoperative examination of the nodes. The aim was to determine the feasibility and accuracy of immunohistochemistry (IHC) of touch imprints in detecting axillary nodal metastases intraoperatively. METHODS: Some 344 axillary nodes from 30 patients with early breast cancer were bisected, imprinted and subjected to IHC. Results were compared with those of routine haematoxylin and eosin examination of the same nodes. RESULTS: Using IHC, 29 nodes from nine patients were positive for metastases. Using haematoxylin and eosin, 28 nodes from eight patients were positive. On a patient basis, the sensitivities of IHC and haematoxylin and eosin were 100 and 88.9 per cent, and negative predictive values (NPVs) were 100 and 95.5 per cent, respectively. On a node basis, the sensitivities were 96.7 and 93.3 per cent, and NPVs were 99.7 and 99.3 per cent, respectively. There were no false positives. The results were obtained within 30-45 min, depending on the number of nodes examined. CONCLUSION: IHC of touch imprints can provide a fast and sensitive method for detecting metastases in axillary nodes during breast cancer surgery.

Adult↗
PubMed2002

Unexplained extra visits to general practitioners before the diagnosis of first urinary tract infection: a case-control study.

AIMS: To determine: (1) whether children diagnosed with a urinary tract infection (UTI) visited their general practitioner (GP) more frequently before the diagnosis of UTI was established compared to children never diagnosed with a UTI; and (2) whether those children with evidence of renal scarring at their first diagnosed UTI visited their GPs more frequently before diagnosis compared to children who did not have evidence of renal scarring when their first UTI was investigated. METHODS: Case-control study of 77 children with a UTI identified from a hospital radiology database (37 with and 40 without renal scarring), and 77 age, sex, and general practice matched controls. Main outcome measures were entries in general practice clinical records for types of illness, antibiotic prescriptions, and urine samples requested prior to the diagnosis of first UTI (cases) or equivalent time periods for controls. RESULTS: Cases had a mean 2.94 additional visits or 21% more visits (95% CI 1% to 41%) in the period (mean 2.4 years) prior to the visit at which their first UTI was diagnosed, including a mean 2.5 additional visits or 23% more visits for infectious illness (95% CI 1% to 45%). The cases had 114% (95% CI 41% to 184%) more visits for symptoms relating to the genitourinary tract, though the actual number of these visits was small. They were febrile at 49% more visits (95% CI 1% to 99%) and received significantly more courses of antibiotics than controls (5.2 v 4.1). They had more urine samples requested (37 v 3). Both the cases with and without renal scarring had similar excess GP visits. CONCLUSION: Compared to controls, children diagnosed with a first UTI had more visits at which symptoms of infection were recorded and more antibiotics prescribed prior to the visit at which the first UTI was diagnosed. These excess visits may have included undiagnosed UTIs. Both those with and without renal scarring had a similar degree of excess visits; additional aetiological factors must have played a role in scar formation.

Anti-Bacterial Agents↗
PubMed2001

Estimating the difference between differences: measurement of additive scale interaction for proportions.

A simple, effective closed-form method to calculate a confidence interval for the difference between two differences of proportions is proposed. The method is based on the Wilson score interval for the single proportion, and may be used to compare either unpaired or paired differences. It is equally applicable whether cell frequencies are large or small; and coverage properties are favourable. It is easily adapted to give a confidence interval for the treatment effect for a binary outcome in a two-period cross-over trial.

Adult↗
PubMed2001

Simultaneous comparison of sensitivity and specificity of two tests in the paired design: a straightforward graphical approach.

Often the performances of two binary diagnostic or screening tests are compared by applying them to the same set of subjects, some of whom are affected, some unaffected. The McNemar test, and corresponding interval estimation methods, may be used to compare the sensitivity of the two tests, but this disregards both any observed difference in specificity and its imprecision due to sampling variation. The suggested approach is to display point and interval estimates for a weighted mean f of the differences in sensitivity and specificity between the two tests. The mixing parameter lambda, which is allowed to range from 0 to 1, represents the prevalence in the population to which application is envisaged, together with the relative seriousness of false positives and false negatives. The confidence interval for f is obtained by a simple extension of a closed-form method for the paired difference of proportions, which has favourable coverage properties and is based on the Wilson single proportion score method. A plot of f against lambda is readily obtained using a Minitab macro.

Colorectal Neoplasms↗
PubMed2001

Optimization of dietary folate or low-dose folic acid supplements lower homocysteine but do not enhance endothelial function in healthy adults, irrespective of the methylenetetrahydrofolate reductase (C677T) genotype.

OBJECTIVES: We sought to study the effect of low-dose folic acid supplementation or optimization of dietary folate intake on plasma homocysteine and endothelial function in healthy adults. BACKGROUND: Elevated homocysteine is associated with cardiovascular disease, but it is not known whether this relationship is causal. Individuals homozygous (TT) for the C677T mutation in the methylenetetrahydrofolate reductase (MTHFR) gene ( approximately 12% of the population) have increased homocysteine levels, particularly in association with suboptimal folate intake. METHODS: Healthy subjects (n = 126; 42 of each MTHFR genotype) were included in this cross-over study of three interventions of four months each: 1) placebo plus natural diet; 2) daily 400-microg folic acid supplement plus natural diet; and 3) increased dietary folate intake to 400 microg/day. RESULTS: At baseline, homocysteine was inversely related to plasma folate and was higher in TT homozygotes. For the whole group, plasma folate increased by 46% after dietary folate and by 79% after supplementation, with reductions of homocysteine of 14% and 16%, respectively. Within the genotype, TT homozygotes exhibited the most marked changes in these variables. Brachial artery endothelial function, as determined by a change in end-diastolic diameter in response to increased flow, was not changed by increased folate intake (98 +/- 73 microm at baseline, 110 +/- 69 microm after a high-folate diet, 114 +/- 59 microm after supplementation and 118 +/- 68 microm after placebo). Plasma von Willebrand factor antigen was unaltered. CONCLUSIONS: Optimization of dietary folate or low-dose folic acid supplementation reduces plasma homocysteine but does not enhance endothelial function, irrespective of the MTHFR (C667T) genotype.

Adolescent↗
PubMed2001

Abrasion and stain removal by different manual toothbrushes and brush actions: studies in vitro.

BACKGROUND AND AIMS: A limited amount of data using flat trim multitufted toothbrushes shows that abrasion of substrate surfaces by a standard toothpaste varies dependent on filament stiffness and configuration; soft brushes producing the most abrasion. The aims of these studies in vitro were to assess toothpaste abrasion of acrylic and stain removal by 5 proprietary medium toothbrushes with different head filament arrangements, and a prototype brush with rectangular filaments. The prototype brush had a medium texture in the long axis and soft texture at right angles to the long axis. MATERIAL AND METHOD: Optically clear acrylic was used as the substrate for abrasion by a standard toothpaste. Loss of substrate was determined by profilometry after 5000, 10000, 15000 and 20000 linear or rotary brushing actions. Stain removal was determined spectrophotometrically from optically clear acrylic specimens stained by chlorhexidine tea soaking sequences. Stained specimens were brushed with water using linear or rotary actions and measurements taken every 10 s to 60 s. RESULTS: Abrasion was progressive with increasing strokes and the pattern for each brush and brush action was to a first approximation linear. Overall, abrasion was significantly greater with linear compared to rotary action. Also overall brushes differed in the abrasion produced with both actions and particularly at greater exposure times. Within brush differences for the two motions were all significant by 20000 strokes except for the prototype brush. Stain removal was progressive over time with each brush but the pattern was non-linear. For the proprietary brushes the rotary motion removed less stain. For the prototype brush more stain was removed with the rotary action. Overall brushes differed significantly in stain removal within each motion and for each motion most differences between the proprietary and prototype brushes reached significance. CONCLUSIONS: The differences between brushes for both abrasion and stain removal must in large part relate to the filament contact area with the substrate surface. Whilst the model may not be predictive of clinical differences, it could find use to establish minimum criteria for toothbrush action.

Acrylic Resins↗
PubMed2001

A study to assess the plaque inhibitory action of a new zinc citrate toothpaste formulation.

BACKGROUND, AIMS: Zinc-citrate-containing toothpastes have previously been suggested to be of value at inhibiting plaque and gingival inflammation. Present formulations have included triclosan which is thought to contribute major antibacterial/antiplaque effects. Alternative antimicrobial agents and other ingredients such as oils could help to produce equally effective formulations. The aim of this study was to determine whether zinc citrate toothpastes containing bromochlorophene and a triglyceride oil (1% and 8%) could inhibit de novo plaque formation. METHODS: Toothpaste slurry rinses were used over a 96-h period by 24 volunteers, whilst omitting all other oral hygiene procedures. For comparative purposes, a conventional commercial fluoride control toothpaste was also used in this triple cross-over double blind study. RESULTS: After 24 and 48 h, there were no statistically significant differences in plaque between the 2 test pastes and the control paste, whether assessed using a plaque index or plaque area. After 96 h, however, a significant reduction in plaque score of 10.6% and 24.2%) in plaque area (both p < 0.001) was found for the zinc citrate/1% oil toothpaste compared to the control paste. In addition, at 96 h, the 8% oil toothpaste significantly reduced plaque score compared to the control paste by 4.3% (p = 0.029). CONCLUSIONS: These findings would appear to warrant further investigation into the potential value of the zinc citrate/bromochlorophene/triglyceride formulation at inhibiting both plaque and gingival inflammation.

Adult↗
PubMed2001

The erosive effects of some mouthrinses on enamel. A study in situ.

BACKGROUND: There are both anecdotal clinical and laboratory experimental data suggesting that low pH mouthrinses cause dental erosion. This evidence is particularly relevant to acidified sodium chlorite (ASC) formulations since they have plaque inhibitory properties comparable to chlorhexidine but without the well known local side effects. AIM: Studies in situ and in vitro were planned to measure enamel erosion by low pH mouthrinses. The study in situ measured enamel erosion by ASC, essential oil and hexetidine mouthrinses over 15-day study periods. The study was a 5 treatment, single blind cross over design involving 15 healthy subjects using orange juice, as a drink, and water, as a rinse, as positive and negative controls respectively. 2 enamel specimens from unerupted human third molar teeth were placed in the palatal area of upper removable acrylic appliances which were worn from 9 a.m. to 5 p.m., Monday to Friday for 3 weeks. Rinses were used 2x daily and 250 ml volumes of orange juice were imbibed 4x daily. Enamel loss was determined by profilometry on days 5, 10 and 15. The study in vitro involved immersing specimens in the 4 test solutions together with a reduced acid ASC formulation for a period of 4 h under constant stirring; Enamel loss was measured by profilometry every hour. RESULTS: Enamel loss was in situ progressive over time with the 3 rinses and orange juice but negligible with water. ASC produced similar erosion to orange juice and significantly more than the two proprietary rinses and water. The essential oil and hexetidine rinses produced similar erosion and significantly more than water. Enamel loss in vitro was progressive over time, and the order from low to high erosion was reduced acid ASC, ASC, Essential oil, and hexetidine mouthrinses and orange juice. CONCLUSION: Based on the study in situ, it is recommended that low pH mouthrinses should not be considered for long term or continuous use and never as pre-brushing rinses. In view of the plaque inhibitory efficacy of ASC, short- to medium-term applications similar to those of chlorhexidine would be envisaged.

Adult↗
PubMed2001

Plaque removal with the uninstructed use of electric toothbrushes: comparison with a manual brush and toothpaste slurry.

BACKGROUND: Individuals purchasing electric toothbrushes for the 1st time will mostly only have the manufacturer's instructional leaflet for information of usage. AIMS: This study was designed to simulate the 1st-time purchase and early use of an electric toothbrush with the aim of comparing plaque removal with a manual toothbrush. Secondary aims were to assess chemical plaque removal effects of a toothpaste slurry and to compare between 2 electric brushes which differed only in head speed. METHODS: A group of 16 dentate subjects participated in this single-examiner blind, randomised, crossover design balanced for residual effects. Subjects had "average" oral hygiene and had never used an electric toothbrush previously. 7 days prior to the study, all subjects received the slower oscillating rotating toothbrush under test to use at home as they wished. The test treatments were brushing with 2 oscillating rotating electric toothbrushes, a manual toothbrush and a rinse with a toothpaste slurry (3 g/10 ml water). On day 1 of each study period, subjects were rendered plaque-free, suspended oral hygiene and returned on day 5. Plaque was scored at baseline by index and area and after 30 s, 30 s (total 60 s) and 60 s (total 120 s) of the cleaning treatments. Washout periods were at least 2 1/2 days. RESULTS: Highly significant treatment differences were found between the 4 treatments because the toothpaste slurry was totally without effect. Analyses between the 3 brush treatments overall revealed no consistent significant differences. The data suggest that in the early days of electric toothbrush use, subjects perform no better than using a manual brush. CONCLUSIONS: The present study, taken with results from others showing greater benefits from the use of electric brushes, supports the idea that dental professionals should, where possible, provide advice and instruction in the use of such devices.

Analysis of Variance↗
PubMed2001

Studies on the effect of polyvinyl pyrrolidone on the activity of chlorhexidine mouthrinses: plaque and stain.

BACKGROUND, AIMS: Polyvinyl pyrrolidone (PVP) was shown in vitro to reduce chlorhexidine induced, dietary staining without affecting the uptake of the antiseptic to the test substrate. The aim of these studies in vivo was to determine whether PVP affected plaque and dietary staining by a low concentration chlorhexidine rinse. METHODS: The plaque and stain studies used a double blind, randomised 6, treatment crossover design involving healthy subjects with a high standard of oral hygiene and gingival health. The rinse formulations under test were: (A) aqueous alcohol (placebo control), (B) 0.03% chlorhexidine, (C) 0.06% chlorhexidine, (D) 0.06% chlorhexidine+1.2% PVP, (E) 0.06% chlorhexidine+5% PVP, (F) 0.06% chlorhexidine+10% PVP. In the plaque study, on day 1 of each period, subjects were rendered plaque free and then rinsed with 15 ml of the test rinse for 60 s. No further tooth cleaning was performed and subjects returned 24 h later for plaque scoring by area. In the stain study, on day 1 of each period, the tongue and teeth of each subject were rendered stain free. Subjects then rinsed under supervision for 60 s with 15 ml of the allocated rinse 8 x a day between 09:00 h and 17:00 h for 3 days. Immediately after each rinse with the test formulation, subjects rinsed for 120 s with 15 ml of warm black tea. Subjects were requested to also drink at least 5 cups of tea or coffee per day. On day 4, stain was scored by area and intensity from designated teeth and dorsum of the tongue. Washout periods were at least 7 days in both studies. RESULTS: Plaque areas were greatest with placebo and least with 0.06% chlorhexidine. Plaque scores increased with increasing concentrations of PVP in the 0.06% chlorhexidine rinse and were significantly higher than 0.06% chlorhexidine without PVP rinse. Tooth stain areas were comparable for placebo, 0.03% and 0.06% chlorhexidine rinses, but significantly reduced with the PVP/chlorhexidine rinses compared to the 0.06% chlorhexidine rinse. Tooth stain intensity was significantly increased with 0.06% chlorhexidine rinses compared to placebo and chlorhexidine/PVP rinses. Tongue stain area and intensity were significantly reduced with 5% and 10% PVP/chlorhexidine rinses compared to 0.06% chlorhexidine rinse. CONCLUSION: PVP, at the concentrations tested, reduced the stain propensity of a 0.06% chlorhexidine rinse but at the expense of some loss of plaque inhibition.

Adolescent↗
PubMed2001

Cyclosporin A-induced gingival overgrowth is unrelated to allograft function in renal transplant recipients.

BACKGROUND: Severe gingival hyperplasia (GH) is one of the most frequent side-effects associated with the prescription of Cyclosporine-A (CsA). AIM: This study statistically modeled the medical and dental risk factors for the development of GH following CsA administration to determine whether renal function post-transplantation was related to the incidence or extent of GH in 236 consecutive renal transplant patients. METHOD: All patients were at least 6 months post-transplant and medicated with both traditional oral CsA (n=220 individuals) and the new microemulsion form CsA-Me (n=229 individuals). Patients had either received CsA alone (n=45 individuals) or cyclosporine and nifedipine (n=191 individuals). Gingival overgrowth was assessed and computerized data, available for all patients included; pre- and post-transplant medical history and post-transplant renal function, i.e., serum creatinine levels, documented rejection episodes and glomerular filtration rates (GFR). These data together with CsA serum levels and last-recorded dose of CsA, CsA-Me, nifedipine, azathioprine and prednisolone, were analysed by multivariate regression analysis using SPSS. RESULTS: The extent and severity of hyperplasia was significantly correlated with the dosage and serum level of CsA at 3, 6 and 12 months post-transplantation; last recorded dosage, however (p<0.0001), was the most accurate predictor of hyperplasia. Gingivitis (p<0.0001) and plaque (p<0.002), were associated with hyperplasia. Duration of renal replacement therapy, age at transplantation, post-transplant interval serum creatinine levels and documented rejection episodes were unrelated with the extent and severity of GH. Of all the renal variables only the correlation of GFR with last recorded doses of CsA and CsA-Me, approached significance; this was then considered for inclusion in the model. CONCLUSION: In a multiple regression analysis including GFR, however, only last CsA (and CsA-Me) doses and gingivitis score were selected for inclusion in the final model. These data demonstrate that inter-patient variation in the extent and severity of GH and renal function post-transplantation are unrelated and are mediated independently.

Adolescent↗
PubMed2001

Video instruction to establish a panel of experts to compare tooth cleaning by 4 electric toothbrushes.

BACKGROUND AND AIMS: Laboratory robots can reveal differences in the cleaning of artificial tooth surfaces by different electric toothbrushes. The primary aim of this study was to establish, through video instruction, a panel of experts in tooth cleaning with an oscillating rotating electric toothbrush in an attempt to mimic the highly reproducible laboratory robot. A secondary aim was to use the "expert" panel, in an attempt to distinguish between tooth cleaning efficacy of 4 head/model combinations of the oscillating rotating electric brush. METHOD: A 24-subject panel, after video training and home habituation for up to 12 weeks with the basic model of electric brush, participated in a single examiner blind, 4-cell, randomised, cross-over study balanced for residual effects. In each period, subjects suspended tooth cleaning for 4 days. Plaque was then scored by area before and after tooth brushing for 2 min in tandem with the instructional video with the allocated brush head/model combination. RESULTS: Differences between subjects was significant, but overall plaque removal with all brushes was of the order of 85% with one subject achieving >97% plaque removal. There were significant differences between the brushes with the oscillating rotating brush with the faster head movement, in most analyses, significantly more effective than the slower oscillating rotating brush with 2 head combinations. The faster oscillating rotating brush was also significantly more effective than the most recently introduced oscillating rotating reciprocating model. CONCLUSIONS: Previous studies have shown that single uses of watch-and-follow video instruction significantly improve toothcleaning with electric toothbrushes. The present study shows that extended training using these videos results in almost complete plaque removal even when prebrushing plaque levels have been enhanced by a 4-day period of no oral hygiene. Furthermore, the establishment of an "expert" panel can distinguish between brushes of different cleaning efficiencies. However, given the level of achievement of all panel members with all brushes, the absolute differences observed are of doubtful clinical significance for gingival health. Finally, the slightly-reduced plaque removal by the 3 directional head action brush can be explained by the inability within the present protocol to habituate the subjects in its use.

Adolescent↗
PubMed2001

A study to assess the plaque inhibitory action of a newly formulated triclosan toothpaste.

BACKGROUND/AIMS: Triclosan containing toothpastes have been noted for their potential to inhibit plaque and gingival inflammation. The aim of this study was to determine whether a toothpaste containing triclosan and an enhanced fluoride system would inhibit de novo plaque formation beyond that of a non-triclosan, conventional fluoride toothpaste. METHODS: This study used a 4-day plaque regrowth model in which 24 volunteers used toothpaste rinses as the only form of oral hygiene. Following a prophylaxis and a single brushing with the toothpastes, 2x daily rinsing with toothpaste slurries was used over the following 96 h. RESULTS: After 24 h, there was no difference in plaque area between the triclosan paste and its control paste. After 96 h, a reduction in plaque score of 5% was noted for the test toothpaste compared to the control paste which was statistically significant (p=0.028). For plaque area this reduction was increased to 16%, which was also significant (p=0.006). CONCLUSIONS: These findings would appear to warrant further investigation into the potential value of the paste in inhibiting both plaque and gingivitis.

Adult↗