Biomedical subjects

G S Griffiths

Publications and source records attributed to G S Griffiths.

At least 19 recordsLinked to original sources

PubMed2006

Periodontal status among relatives of aggressive periodontitis patients and reliability of family history report.

OBJECTIVES: To assess the periodontal status of relatives of Aggressive Periodontitis (AgP) patients, and to evaluate the reliability of the family history report as provided by the proband. MATERIAL AND METHODS: Data from 54 AgP patients were gathered along with a family history report for each of their relatives. Only 27 patients (probands) had relatives willing to be examined. This yielded a total of 61 relatives from whom the periodontal status was obtained. The family history report for each examined relative was compared with the periodontal diagnosis made at examination to assess reliability. RESULTS: Eight percentage of the examined relatives, aged between 12-76, were diagnosed with AgP, while chronic periodontitis was present in 39%, gingivitis in 38% and 15% were healthy. If the report provided by the proband was positive, the likelihood of finding any type of periodontitis in that relative was 85.7%, whereas if the report was negative the likelihood of the absence of periodontitis was 70.6%. CONCLUSION: The percentage of examined relatives who were affected with AgP (8%), although lower than percentages reported in other AgP family studies, was still higher than the prevalence of the condition in random populations. Reliability of periodontal family history was considered good and more reliable when it was positive.

Adolescent↗

PubMed2006

NADPH oxidase (CYBA) and FcgammaR polymorphisms as risk factors for aggressive periodontitis: a case-control association study.

INTRODUCTION: Neutrophils (PMN) in aggressive periodontitis (AgP) patients have been reported to be hyperactive especially with regards to superoxide production. Polymorphisms in genes influencing PMN function have been proposed as candidate risk factors for AgP. The aim of this study was to test the association of specific gene polymorphisms affecting PMN functions with AgP. MATERIALS AND METHODS: Two hundred and twenty-four patients with confirmed diagnosis of AgP and 231 subjects with healthy periodontium took part in the study. A blood sample was collected from subjects and genotypes for p22phox (CYBA) NADPH oxidase, FP, Fcalpha and Fcgamma receptors were analysed in a blind fashion. RESULTS: The C242T p22phox NADPH oxidase T allele was significantly associated with AgP in a multiple logistic regression model adjusting for confounders, and this was observed for all subjects [p = 0.002, odds ratio (OR) = 1.87, 95% confidence interval (CI) = 1.27-2.83] and Caucasians (p = 0.009, OR=2.07, 95% CI = 1.20-3.59). Concomitant presence of C242T p22phox NADPH oxidase T allele and FcgammaRIIIb NA1 homozygosity was associated with the generalized AgP phenotype in Caucasians (p = 0.001, OR = 30.35, 95% CI = 3.81-241.97). CONCLUSIONS: C242T p22phox NADPH oxidase and FcgammaR polymorphisms may predispose to AgP through a modulation of neutrophil superoxide production.

Adult↗

PubMed2005

Functional gene polymorphisms in aggressive and chronic periodontitis.

There is strong evidence that genetic as well as environmental factors affect the development of periodontitis, and some suggestion that aggressive and chronic forms of the disease share the same genetic predisposition. This study addresses the hypothesis that there are both shared and unique genetic associations in these forms of periodontitis. A sample of 51 patients with aggressive disease, 57 patients with chronic disease, and 100 healthy controls was recruited for this study. Ten functional polymorphisms in 7 candidate genes were genotyped. The results show statistically significant (p <or= 0.05) differences between genotype frequencies in aggressive and controls (IL-1B +3954 & IL-6 -174); chronic and controls (IL-6 -174 & VDR -1056); chronic and aggressive periodontitis (IL-1A -889); and periodontitis as a whole and controls (VDR -1056, TLR-4 399 & IL-6 -174). These results suggest that there are in fact both shared and unique genetic associations in aggressive and chronic periodontitis.

Alleles↗

PubMed2004

Changes in transforming growth factor-beta1 in gingival crevicular fluid following periodontal surgery.

OBJECTIVES: Growth factors play a major part in wound healing, including in the periodontium. However, the presence of growth factors in gingival crevicular fluid (GCF) in humans during periodontal wound healing has not yet been determined. Our hypothesis is that such factors are present in GCF and that changes in their levels might be of value as a prognostic marker of wound-healing activity and therapeutic progress following periodontal surgery. The aim of this study was therefore to measure transforming growth factor-beta1 (TGF-beta1) in GCF collected from sites that have undergone guided tissue regeneration (GTR) and conventional flap (CF) surgery and to compare these with GCF collected from unaffected healthy sites. MATERIALS AND METHODS: GCF samples were collected, using filter paper strips, at baseline (pre-surgical) and then at intervals up to 26 weeks from 16 patients undergoing GTR and from 11 patients undergoing CF surgery. After elution and acid treatment, TGF-beta1 levels were measured by ELISA. RESULTS: Treatment of periodontal defect sites significantly reduced the mean probing pocket depth (PPD) and improved the mean lifetime cumulative attachment loss (LCAL). Average GCF volumes also significantly increased at all sites at 2 weeks post-surgery and thereafter declined to baseline levels, except at the GTR test sites that were still elevated at 7 weeks. TGF-beta1 could be detected in almost all GCF samples, and 2 weeks after surgery, the average levels increased two-fold at the surgically treated but not at the control sites, which remained unchanged. CONCLUSION: TGF-beta1 is readily detectable in GCF and increases transiently following periodontal surgery. This suggests that changes in the levels of this growth factor in GCF might be useful for monitoring the progress of periodontal repair and regeneration.

Adult↗

PubMed2003

Unification of the "burst" and "linear" theories of periodontal disease progression: a multilevel manifestation of the same phenomenon.

Previously, burst and linear theories for periodontal disease progression were proposed based on different but limited statistical methods of analysis. Multilevel modeling provides a new approach, yielding a more comprehensive model. Random coefficient models were used to analyze longitudinal periodontal data consisting of repeated measures (level 1), sites (level 2), teeth (level 3), and subjects (level 4). Large negative and highly significant correlations between random linear and quadratic time coefficients indicated that subjects and teeth with greater-than-average linear change experienced decelerated variation. Conversely, subjects and teeth with less-than-average linear change experienced accelerated variation. Change therefore exhibited a dynamic regression to the mean at the tooth and subject levels. Since no equilibrium was attained throughout the study, changes were cyclical. When considered as a multilevel system, the "linear" and "burst" theories of periodontal disease progression are a manifestation of the same phenomenon: Some sites improve while others progress, in a cyclical manner.

Adolescent↗

PubMed2002

Is reduction of pocket probing depth correlated with the baseline value or is it "mathematical coupling"?

Previous studies using correlation or regression analysis have showed that treatment effects measured by the change in clinical parameters are often associated with baseline values of the same parameters. These studies, however, have a methodological weakness. Correlation/regression between baseline measures and the derived change variable invalidates the statistical procedures of testing the null hypothesis: that the coefficient of correlation/regression is zero. This is due to the phenomenon of mathematical coupling. To investigate the impact that this has on the observed correlation/regression coefficient when in reality this is zero, we used random simulations of hypothetical data to model the treatment of periodontal pockets. Results showed a strong probability of obtaining statistically significant correlation/regression coefficients. To separate this artificial effect of mathematical coupling from the true underlying biological relationship, one must apply appropriate analytical strategies to re-evaluate previous evidence within the periodontal literature.

Algorithms↗

PubMed2001

Prevalence and extent of lifetime cumulative attachment loss (LCAL) at different thresholds and associations with clinical variables: changes in a population of young male military recruits over 3 years.

AIM: The aims of this study were to monitor the prevalence and progression of lifetime cumulative attachment loss (LCAL) in a group of young British male military recruits over a 3-year period, and to determine the relationship between signs of LCAL and selected periodontal variables. METHODS: 100 subjects, aged 16-20 years (mean 17 years) at baseline, were examined at 0 (baseline), 12 and 30 months. LCAL, probing depth, plaque, bleeding on probing, gingival colour and supra- and subgingival calculus were assessed on the mesio-buccal, disto-buccal, mesio-lingual and disto-lingual surfaces of all teeth present, excluding third molars. Data were analysed cross-sectionally at each examination. RESULTS: Over the period of the study, the prevalence of LCAL > or =1 and 2 mm ranged from 95-100%, whereas LCAL > or =3 mm ranged from 40-47%. The extent of LCAL > or =1 mm ranged from 76-86%. However, the extent of LCAL > or =2 mm was dramatically lower (10.5-12.7%), and LCAL > or =3 mm was uncommon (0.5-0.9%). Examining the number of subjects according to the number of sites affected above a threshold, showed that a small number of subjects have a large number of sites above threshold. Using Pearson's rank correlation coefficient a significant correlation (p<0.05) was found between LCAL and the periodontal variables of gingival bleeding and supra- and subgingival calculus. CONCLUSIONS: These data suggest that the onset and progression of chronic periodontitis can be seen in young adults, and in this group gingival bleeding and supra- and subgingival calculus are the variables most strongly associated with early periodontitis.

Actuarial Analysis↗

PubMed2001

Utilisation of locally delivered doxycycline in non-surgical treatment of chronic periodontitis. A comparative multi-centre trial of 2 treatment approaches.

AIM: In the present 6-month multicentre trial, the outcome of 2 different approaches to non-surgical treatment of chronic periodontitis, both involving the use of a locally delivered controlled-release doxycycline, was evaluated. MATERIAL AND METHODS: 105 adult patients with moderately advanced chronic periodontitis from 3 centres participated in the trial. Each patient had to present with at least 8 periodontal sites in 2 jaw quadrants with a probing pocket depth (PPD) of > or =5 mm and bleeding following pocket probing (BoP), out of which at least 2 sites had to be > or =7 mm and a further 2 sites > or =6 mm. Following a baseline examination, including assessments of plaque, PPD, clinical attachment level (CAL) and BoP, careful instruction in oral hygiene was given. The patients were then randomly assigned to one of two treatment groups: scaling/root planing (SRP) with local analgesia or debridement (supra- and subgingival ultrasonic instrumentation without analgesia). The "SRP" group received a single episode of full-mouth supra-/subgingival scaling and root planing under local analgesia. In addition, at a 3-month recall visit, a full-mouth supra-/subgingival debridement using ultrasonic instrumentation was provided. This was followed by subgingival application of an 8.5% w/w doxycycline polymer at sites with a remaining PPD of > or =5 mm. The patients of the "debridement" group were initially subjected to a 45-minute full-mouth debridement with the use of an ultrasonic instrument and without administration of local analgesia, and followed by application of doxycycline in sites with a PPD of > or =5 mm. At month 3, sites with a remaining PPD of > or =5 mm were subjected to scaling and root planing. Clinical re-examinations were performed at 3 and 6 months. RESULTS: At 3 months, the proportion of sites showing PPD of < or =4 mm was significantly higher in the "debridement" group than in the "SRP" group (58% versus 50%; p<0.05). The CAL gain at 3 months amounted to 0.8 mm in the "debridement" group and 0.5 mm in the "SRP" group (p=0.064). The proportion of sites demonstrating a clinically significant CAL gain (> or =2 mm) was higher in the "debridement" group than in the "SRP" group (38% versus 30%; p<0.05). At the 6-month examination, no statistically significant differences in PPD or CAL were found between the two treatment groups. BoP was significantly lower for the "debridement" group than for the "SRP" group (p<0.001) both at 3- and 6 months. The mean total treatment time (baseline and 3-month) for the "SRP" patients was 3:11 h, compared to 2:00 h for the patients in the "debridement" group (p<0.001). CONCLUSION: The results indicate that simplified subgingival instrumentation combined with local application of doxycycline in deep periodontal sites can be considered as a justified approach for non-surgical treatment of chronic periodontitis.

Adult↗

PubMed2001

The influence of partial and full-mouth recordings on estimates of prevalence and extent of lifetime cumulative attachment loss: a study in a population of young male military recruits.

BACKGROUND: Previous studies have shown that the use of index teeth may underestimate the prevalence of chronic periodontitis in adults. However, there is little information on the effect of using index teeth to estimate the prevalence of early periodontitis in younger adults and the effect this may have on planning treatment needs and health care resources. The aim of this study was to compare full mouth examination with partial examination using index teeth in a group of young British males. METHODS: One hundred subjects aged between 16 and 20 years (mean 17 years) on entry to the study were examined at baseline, 12 months later, and 30 months later. Lifetime cumulative attachment loss (LCAL) > or =1 mm was measured on the mesio-buccal, disto-buccal, mesio-lingual, and disto-lingual surfaces of all teeth, excluding third molars. All data were entered into a database. The indices used to express LCAL were prevalence, defined as the percentage of subjects with LCAL > or =1 mm, 2 mm, or 3 mm, and extent, defined as the percentage of sites with LCAL > or =1 mm, 2 mm, or 3 mm. Two sets of index teeth were chosen to compare with full mouth recordings, Ramfjord index teeth and the Periodontal Index for Treatment (PIT) teeth. RESULTS: The prevalence of LCAL > or =1 mm was similar (approaching 100%) for the full mouth and both partial mouth recordings. However, as LCAL increased from a minimum of 1 to 3 mm, partial mouth recording resulted in an underestimation of the prevalence of disease. LCAL > or =2 mm was underestimated by up to 22% and LCAL > or =3 mm by up to 36%. The extent of LCAL was less affected by partial mouth recording, in that the percentage of sites with no sign of early attachment loss was underestimated by up to 11%. However, the percentage of sites with LCAL > or =1 mm and 2 mm were overestimated by 11% and, 7% respectively. CONCLUSIONS: These data indicate that the use of index teeth in epidemiological studies which include young adults may result in an underestimation of the prevalence of early periodontitis and an overestimation of the extent.

Adolescent↗

PubMed2001

Flow cytometry analysis of guided tissue regeneration-associated human periodontal cells.

BACKGROUND: Expanded polytetrafluoroethylene (ePTFE) barrier membranes have been widely used for guided tissue regeneration (GTR) of the human periodontal ligament (PL). However, the precise cellular and molecular events involved in the re-growth of the new tissue are still unclear. METHODS: Retrieved membranes and the newly-regenerated soft tissue (RT) underlying the membranes were used to examine the cells associated with GTR compared with normal human PL and gingival cells. Flow cytometry (FCM) was used, for the first time, to analyze the spindle-shaped fibroblast-like cells which were adherent to these membranes and the cells which grew out of the RT. RESULTS: The results showed that the membrane-associated (M) cells had the lowest rate of proliferation and appeared to be larger and more granular than the other types of cell. Moreover, both the M- and RT-derived cells were found to express higher levels of the extracellular matrix (ECM) proteins collagen type 1, fibronectin, tenascin, and decorin. In addition, evidence based on FCM profiles identified distinct sub-populations of GTR cells in which fibronectin expression was markedly up-regulated compared with normal PL cells and which also differed in size and granularity. CONCLUSIONS: The results of this study show that cells associated with GTR barrier membranes and with the underlying tissue appear to have distinct phenotypic and functional activities consistent with the production of new periodontal connective tissue and periodontal regeneration.

Adult↗

PubMed2001

An application of multilevel modelling to longitudinal periodontal research data.

OBJECTIVE: To introduce the concepts of random coefficient multilevel models through an application to periodontal research data. BASIC RESEARCH DESIGN: Multilevel models with random coefficients are illustrated using periodontal data that comprise four levels: repeated measurements at level-1, sites at level-2, teeth at level-3, and subjects at level-4. The study explores random coefficient models--where random variation occurs about explanatory variable coefficients. Outcomes considered are lifetime cumulative attachment loss and pocket probing depth. PARTICIPANTS: The study data were taken from a survey of periodontal disease involving 100 white male trainee engineers aged between 16 and 20 entering the apprentice training school at the Royal Air Force-Halton, UK. RESULTS: The application of multilevel modelling to longitudinal data provides a new way of exploring old problems. The multilevel random coefficient models provide an opportunity to examine the 'linear' and 'burst' theories of periodontal disease progression, leading to the postulation that both can be unified within the multilevel framework. CONCLUSIONS: The multilevel methodology illustrates how advances in the understanding of oral health can be achieved with the advent of new statistical methods

Adolescent↗

PubMed2000

Comparison of clinical outcomes following treatment of chronic adult periodontitis with subgingival scaling or subgingival scaling plus metronidazole gel.

BACKGROUND, AIMS: Conventional treatment of chronic periodontitis involves mechanical debridement of periodontal pockets. Recently, subgingival antimicrobials have been used adjunctively following such debridement. This 2-centre study compared the clinical effects of subgingival scaling (SRP) with SRP plus subgingival application of 25% metronidazole gel, Elyzol (SRP+gel), in patients with chronic adult periodontitis. METHOD: Voluntary informed written consent was obtained from 45 subjects at the Eastman (mean age 46, range 34-63) and 43 subjects at RAF Halton (mean age 47, range 34-71) who participated in this blind, randomised split-mouth design study. All had at least 2 sites in each quadrant with probing pocket depth (PPD) > or = 5 mm. PPD, bleeding on probing (BOP), and clinical probing attachment levels (CAL) measured using a stent, were recorded at baseline and at 1, 3, 6 and 9 months post-therapy. After subgingival scaling of all quadrants, 2 quadrants were randomly selected to be treated with metronidazole gel. RESULTS: A paired t-test on baseline values showed no bias between groups. Both treatments effectively reduced the signs of periodontitis. At each follow-up visit, reduction in PPD, CAL and BOP after the combined treatment was greater than for SRP alone. Paired t-tests showed that the improvement in the SRP+gel group was statistically significantly better (p<0.001) than for SRP alone (mean 0.5 +/- 0.6 mm. 95% CI 0.4-0.6 mm.) Similarly, the % of sites which improved to a final pocket depth of < or = 3 mm and the % of sites which improved over the 9 months of the study by as much as > or = 2 mm were greater for SRP+gel than for SRP alone. CONCLUSIONS: At the end of the study, the mean reductions for PPD were 1.0 mm (SRP) compared to 1.5 mm (SRP+gel), and for CAL they were 0.4 mm (SRP) compared to 0.8 mm (SRP+gel), with mean difference for CAL between treatments of 0.4 +/- 0.6 mm (95% confidence intervals of 0.3-0.6 mm). The combination therapy of SRP+gel was superior to the conventional treatment of SRP alone, and these differences were maintained for 9 months.

Adult↗

PubMed2000

The application of multilevel modelling to periodontal research data.

OBJECTIVE: To explain the theory of multilevel modelling and demonstrate its application in the analysis of dental research data. BASIC RESEARCH DESIGN: Multilevel modelling was introduced using dental data comprising four levels: repeated measurements at level-1, sites at level-2, teeth at level-3, and subjects at level-4. Variance components models (which have no explanatory variables) were evaluated for all outcome measures. Explanatory variables were added to the models with outcomes for both lifetime cumulative attachment loss and pocket probing depth. Salient features of the multilevel models were discussed. PARTICIPANTS: Research data were obtained from a longitudinal survey of periodontal disease conducted on 100 white male trainee engineers aged between 16 and 20 years entering the apprentice training school at Royal Air Force Halton, England. RESULTS: The statistical methods revealed that periodontal measures demonstrate considerable variation at all levels of the multilevel structure. Models for lifetime cumulative attachment loss and pocket probing depth illustrated that risk factors operated at more than one level. Supragingival calculus was a risk factor at the subject-level (subjects experiencing more sites with the condition had greater attachment loss and greater pocketing) whilst there was apparently a protective effect occurring at the site (sites with the condition had less attachment loss and less pocketing). CONCLUSIONS: This study demonstrates that multilevel modelling is a more powerful research tool than single-level techniques for the analysis of hierarchical dental data. Researchers using these techniques are well equipped to analyse complex hierarchical data structures, such as those often found within dentistry.

Adolescent↗

PubMed1999

Calibration of the Periotron 8000 and 6000 by polynomial regression.

This paper reports the detailed calibration of the new Periotron 8000 with different fluids and uses the method of least squares to derive polynomial regression equations up to the 6th order, to investigate the most accurate descriptor of the resulting calibration lines. The use of a 4th order polynomial regression equation (recommended by the manufacturer) provided better coefficients of determination (R2: 0.999) and root mean square errors (RMSE = 1.6) than either linear regression (R2: 0.986, RMSE = 10.9) or quadratic models (R2: 0.998, RMSE = 3.2). Data derived using the manufacturer's MLCONVERT software program lacked accuracy and incurred large errors for volumes > 0.5 microliter. Calibrations performed on one day could be used with accuracy to derive volumes > 0.1 microliter collected on subsequent days, when using the same machine (s.d. for residuals plot = 2.49 Periotron units), but this was not the case for different machines (s.d. = 9.57 Periotron units). Varying serum protein concentration by up to 500% had a negligible effect on calculated volumes above 0.1 microliter. We conclude that the Periotron 8000 is at least as reliable a machine as the Periotron 6000, and that the calibration lines for both machines are best described using 4th order polynomial regression equations and "look-up" tables, rather than quadratic (Periotron 6000) or the manufacturer's software (Periotron 8000). Serum seems to be an acceptable GCF substitute for calibrations, which can be performed 1 day, and used on subsequent days for a given machine and for volumes above 0.1 microliter.

Calibration↗

PubMed1999

Alkaline phosphatase activity is upregulated in regenerating human periodontal cells.

The activity of alkaline phosphatase (ALP) is considered to indicate the presence of osteoblast cells and the formation of new bone. In the present study this enzyme was investigated in cells obtained from retrieved polytetrafluoroethylene membranes (M cells) of periodontal disease patients treated by guided tissue regeneration (GTR) and from the regenerated tissue underlying the membrane (RT cells). Normal periodontal ligament (PL) and gingival cells were also grown from the corresponding healthy tissues of human subjects. ALP activity was measured colourimetrically, using paranitrophenyl phosphate as the substrate, after 4 and 7 d of culture in the absence and presence of dexamethasone (DEX), a synthetic glucocorticoid which induces osteoblast differentiation. The results showed that basal levels of ALP activity were expressed by all the cells and that DEX upregulated ALP levels in the M, RT and PL cells but not in the gingival cells. Moreover, both the basal and DEX-induced ALP activities were statistically significantly higher in the RT cells than in any of the other cells. Our results suggest that both the GTR-associated and normal PL cells express osteoblast-like characteristics and, furthermore, that the RT cultures in particular contain a high proportion of osteoprogenitor cells.

Adolescent↗

PubMed1998

Evaluation of osteocalcin and pyridinium crosslinks of bone collagen as markers of bone turnover in gingival crevicular fluid during different stages of orthodontic treatment.

Osteocalcin (Oc) and the collagen cross-links pyridinoline (Pyr) and deoxypyridinoline (dPyr) are used as markers of bone turnover in metabolic bone diseases. The aims of this study were: 1) to establish if Oc, Pyr and dPyr can be detected in GCF and 2) using the orthodontic tooth movement model of alveolar bone resorption to evaluate GCF levels of osteocalcin and these collagen cross-links as markers of bone breakdown. Plaque, colour and bleeding indices, probing measurements and GCF samples were collected at two sites in each of 20 adolescents, during 4 stages of fixed appliance therapy: (1) prior to appliance fit, (2) post appliance fit, (3) during active retraction of the maxillary canines, (4) during retention. GCF was collected onto filter paper strips and the volume determined by weighing. An ELISA kit was used for the detection of osteocalcin, whereas Pyr and dPyr were assayed using high performance liquid chromotography (HPLC). Wilcoxon signed ranks test and Bonferroni correction revealed statistically significant increases in plaque (p= 0.012), GCF volume (p=0.024) and osteocalcin concentration (p=0.012), between stages 1 and 2. There were no statistically significant differences between the other variables at this stage or between any of the variables at stages 2 and 3, or between stages 3 and 4. All but 3 of the GCF samples yielded detectable osteocalcin, with large site and subject variation. The median values of osteocalcin and osteocalcin concentration of all the samples were 87.5 pg and 66 pg/microl, with a range of 0-1,248 pg, 0-1,572 pg/microl. The detection of osteocalcin in GCF during every stage, the wide variation between subjects, and the lack of a consistent pattern related to stages of orthodontic treatment, suggests that osteocalcin may merely be a constituent of GCF associated with the developing dentition, which would reduce its potential as a marker of bone turnover in this group. None of the 16 GCF samples analysed for Pyr and dPyr gave a positive result. This study confirms that fitting an orthodontic appliance results in plaque accumulation and increased gingival inflammation, and that GCF volume is the most sensitive indicator of that inflammation. Osteocalcin was detected in GCF collected from adolescents, whereas Pyr and dPyr could not be detected. Further work is required to establish whether GCF osteocalcin levels can be used as a marker of bone turnover, and whether improvements in the sensitivity of detecting Pyr & dPyr make further study of these promising bone markers worthwhile.

Adolescent↗

PubMed1998

Flow cytometry analysis of gingival and periodontal ligament cells.

Gingival and periodontal ligament (PDL) fibroblasts are the major cellular components of periodontal soft connective tissues, but the precise differences between these cells are not yet known. In the present study, we have therefore examined the phenotypic and functional features of the cells obtained from gingival and PDL biopsy samples. Spindle-shaped cells characteristic of fibroblasts were the main cell type observed in vitro, although epithelial cells were also present in primary gingival cell cultures. Flow cytometry was used to measure the size and granularity of the cultured cells, and showed that the gingival fibroblasts were smaller and less granular compared with the PDL cells. The expression of certain key extracellular matrix (ECM) proteins, fibronectin, collagen type I, and tenascin was measured by flow cytometry. Analysis of the fluorescence profiles of these cultures showed that the majority of cells expressed fibronectin and that the average fluorescence intensity of this antigen in the PDL cells was higher than that in the gingival fibroblasts. Moreover, the fibronectin-positive PDL cells apparently comprised two subpopulations which expressed fibronectin at different levels, suggesting that the cells in the PDL cultures were functionally heterogeneous. The level of collagen type I was also found to be up-regulated in the PDL compared with the gingival cells and, as with fibronectin, was expressed at two different levels by subsets of the PDL cells. In contrast, tenascin was expressed at very similar levels by both the gingival fibroblasts and PDL cells. In addition, measurement of alkaline phosphatase, a marker enzyme for mineralized tissue-forming cells, showed that the PDL cells had higher activity than the gingival fibroblasts and that the alkaline phosphatase activity in the PDL cells was far more markedly up-regulated by dexamethasone. Our findings demonstrate that, despite their similar spindle-shaped appearance, fibroblasts derived from gingival and PDL tissues appear to display distinct functional activities which are likely to play a vital part in the maintenance of tissue integrity and regenerative processes.

Adolescent↗

PubMed1997

Permeability of the gingival tissues to IgM during an experimental gingivitis study in man.

Changes in the permeability of the underlying vasculature of the gingival crevice region may occur either as part of an inflammatory response during gingivitis or as a response to trauma during collection of gingival crevicular fluid IgM was selected as a marker of permeability and the concentration in gingival crevicular fluid was determined immunochemically by dot blotting, using rabbit antihuman IgM specific for mu chain. Gingival crevicular fluid samples were derived from experimental (non-cleaning) and control (cleaning) sites in six individuals participating in a 28-day experimental gingivitis study using a split-mouth protocol. The fluid was collected by a filter-paper method. At each site, four gingival crevicular fluid samples were collected for 5 s each over a 3-min period and a fifth sample was collected after a further 6 min. IgM was detected in 7/30 experimental strips at baseline (after intensive professional prophylaxis) and this increased to 21/30 by 24 days: control values were 13/30 and 12/30, respectively. The data indicate that IgM was detected with greater frequency as gingivitis becomes evident, suggesting increased permeability in response to plaque accumulation. IgM was detected in 17/120 of the first strip samples, collected over the 66-day study period, whereas in the fifth strip samples IgM was detected in 68/120, and the concentration of IgM in gingival crevicular fluid also increased, indicating that sequential collection induced permeability. It is concluded that the permeability of the gingiva changes in response to both an inflammatory stimulus and trauma due to collection.

Adult↗