bluuebunny/crossref_metadata_2025 huggingface dataset:
Residual effect of chlorhexidine gluconate in 4‐day plaque regrowth crossover trials, and its implications for study design
Authors: Newcombe R.G. , Addy M. , McKeown S.
Published: July 2006

The efficacy of oral hygiene agents in preventing the accumulation of plaque from a zero baseline is conveniently evaluated in the 4‐day plaque regrowth model. In many studies a panel of volunteers has been used to compare several agents according to a highly efficient Latin square based crossover design. Often chlorhexidine gluconate is included as a positive control; there is concern that the effect of this potent agent might persist for longer than the 3‐day washout period often employed. To test this hypothesis of residual effect, we put together the evidence relating to possible carryover from 12 studies. The residual effect of chlorhexidine differs from that of an inert rinse such as saline or water. Consequently, a longer washout period, such as 10 days, is preferable. Studies omitting chlorhexidine are worth considering. Designs should be balanced for residual effects, at least from the preceding treatment period; several useful designs with this property are presented.
Periodontitis in the baboon: a potential model for human disease
Authors: Miller D.R. , Aufdemorte T. B. , Fox W.C. , Waldrop T.C. , Mealey B.L. , Brunsvold M.A.
Published: July 2006

Advances in periodontics with respect to disease activity, microbiology and immunology have demonstrated the multifactorial nature of periodontal diseases. This serves to underscore the need for an ideal animal model for periodontal research. Non‐human primates are most similar to man in comparison to other animal models. The baboon is an Old World monkey that has infrequently been used in periodontal research. Periodontal exams were accomplished on 116 baboons (Papio anubis, P. cynocephalus) ages 5 to 30 years with one baboon year being roughly equivalent to 3 to 4 human years. The study population consisted of 29 males and 87 females. Clinical parameters including probing depth, attachment level, mobility, plaque index and gingival index were collected. Radiographs were taken on 25 animals and correlated to clinical findings. Results showed a significant increase in mean probing depth and mean attachment level with age (p=0.0001). Disease prevalence and severity were not significantly different between genders. Mobility was uncommon; however, the prevalence and severity of furcation involvement increased with age. Radiographs suggested horizontal and isolated vertical bone loss. Plaque and gingival indices were at sustained high levels for all age groups and showed a statistically significant increase with age. Some baboons were found to develop a naturally‐occurring periodontitis that increased in severity with age. This primate may be a suitable model for studies in human periodontal disease.
Assessment of alveolar bone loss with high resolution computed tomography
Authors: Fuhrmann R.A.W. , Bücker A. , Diedrich P. R.
Published: July 2006

In this in vitro study we compared high resolution computed tomography (HR‐CT) with dental radiographs regarding the interpretation of horizontal and vertical alveolar bone loss. After removal of the soft tissue and metallic restorations of 20 dentate upper and lower jaw segments 40 infra‐alveolar bony defects of different dimensions were experimentally produced. The specimens were examined radiographically with standardized dental radiographs and 1.0 mm thick contiguous axial CT‐scans. On the specimens, radiographs and CT‐scans the bone loss was measured between the cemento‐enamel junction and the adjacent alveolar bone level of 472 mesial and distal tooth surfaces; the identification, classification and vertical depth of the infra‐alveolar bony defects were also compared. An average underestimation of 0.6 mm of horizontal alveolar bone loss in the dental radiographs and an overestimation of 0.2 mm in CT‐scanning was shown. No significant differences between the imaging accuracy of horizontal alveolar bone loss between dental radiographs and CT‐scanning could be evaluated. In the dental radiographs 24 (60%) of the infra‐alveolar bony defects could be identified and the vertical depth was underestimated by a mean of 2.2 mm. In comparison, all 40 (100%) infra‐alveolar defects could be identified in the CT‐scans and the vertical depth was underestimated by an average of 0.2 mm. The HR‐CT‐technique offers a three‐dimensional interpretation of the alveolar morpholoy without overlying structures. This permits a high identification rate and classification of infra‐alveolar bone loss according to the number of surrounding bone walls into one‐, two or three‐walled bony pockets.
Effect of whole oral bacteria and extracted lipopolysaccharides on peripheral blood leukocyte interleukin‐2 receptor expression
Authors: Lindemann R.A. , Kjeldsen Mette , Cabret Michelle
Published: July 2006

Expression of the interleukin‐2 receptor (IL‐2R) on T cells is the molecular mechanism that initiates the Go to G1 transition and is the critical first step for T cell proliferation in response to antigen. The effect of whole periodontal bacteria and lipopolysaccharides (LPS) on peripheral blood mononuclear cell (PBMC) IL‐2R expression was examined in vitro. LPS induced a modest but significant increase in high affinity lL‐2Rα/β (p55/p75 positive) expression on PBMC over untreated cells after 48 h culture. Addition of LPS to PBMC cultures depleted of monocytes had no effect on 1L‐2R expression compared to untreated cultures. Interleukin‐1 (IL‐1) caused a similar effect to LPS in 48 h PBMC cultures but IL‐1 also increased high affinity IL‐2R expression in cultures depleted of adherent mononuclear cells. When antibody to IL‐1 was simultaneously added with LPS to PBMC cultures, the high affinity IL‐2R inductive effect was reversed at 48 h, suggesting that the LPS effect on PBMC IL‐2R was indirect, via monocytes. Whole pathogenic oral bacteria cultured with PBMC at high (100:1), but not low (10:1) bacteria:PBMC ratios had a similar effect to LPS, inducing high affinity IL‐2R expression at 48 h. Increases in soluble IL‐2Rα were also measured in supernatants of PBMC incubated with periodontal bacteria compared to untreated controls. In this system, a critical threshold of bacteria was required to activate PBMC perhaps related to the quantity of cell‐surface LPS presented to adherent mononuclear cells.
Analysis in gingival crevicular fluid of two oligopeptides derived from human hemoglobin β‐chain
Authors: Mäkinen K.K. , Sewón L. , Mäkinen P.‐L.
Published: July 2006

HPLC on a reversed phase column, amino acid sequencing and mass spectrometry were used to determine the structure of two human gingival crevicular exudate oligopeptides (Leu‐Thr‐Pro‐Glu‐Glu‐Lys‐Ser‐Ala‐Val‐Thr‐Ala‐Leu and Leu‐Val‐Val‐Tyr‐Pro‐Trp‐Thr‐Gln‐Arg‐Phe) which were shown to have been derived from the β‐chain of hemoglobin. These sequences may simply represent two degradation products of the β‐chain. However, their preservation in an exudate characterized by active peptidolysis may also prompt the question about their possible more specific role.
Loss of attachment in the marginal periodontium of the rat incisor under non‐inflammatory conditions
Authors: Groeneveld M. C. , Everts V. , Beertsen W.
Published: July 2006

Alkaline phosphatase (ALP) has been suggested to play a role in acellular cementum formation and maintenance of periodontal attachment. In an attempt to determine whether changes in attachment level are associated with altered expression of ALP‐activity in the periodontium we induced natural loss of attachment in rats by pinning the lower incisor to the jaw bone. Previous studies have shown that this procedure results in regressive changes in the marginal periodontium without any inflammatory response. Six months after blockage of eruption the attachment level on the experimental (right) side had shifted about 700 μ in the apical direction. On the control (left) side the apical termination of the junctional epithelium had remained stationary with respect to the alveolar crest. Our observations have shown that during the first few weeks of the experiment loss of attachment is accompanied by considerable reduction of ALP‐activity in the supracrestal part of the periodontium. At later time intervals, however, no distinct relation was found between apical migration of junctional epithelium and loss of ALP‐activity in the supracrestal region, indicating that the two phenomena are not directly related to each other. The domain of the ALP‐positive fibroblasts in the supracrestal extension of the periodontal ligament decreased in size and was replaced by ALP‐negative connective tissue cells probably coming from the outer gingival domain. Since at all time intervals a distinct demarcation could be observed between the ALP‐positive and ALP‐negative areas, we interpret our data as indicating that ligament and gingival cells do not mix.
Histamine H1 receptor‐stimulated Ca2+ signaling pathway in human periodontal ligament cells
Authors: Niisato N. , Ogata Y. , Furuyama S. , Sugiya H.
Published: July 2006

We studied histamine‐induced Ca2+ mobilization in human periodontal ligament (HPDL) cells. Histamine induced a transient rise in intracellular Ca2+ ([Ca2+]i) and maintained a sustained phase in the presence of extracellular Ca2+. In the absence of extracellular Ca2+, the transient peak was slightly reduced and the sustained phase was decreased to the basal level. The initial rise in [Ca2+]i was attributed to two components: intracellular Ca2+ release and Ca2+ influx, whereas the sustained phase was due to Ca2+ influx. After depletion of intracellular Ca2+ stores with thapsigargin, a known Ca2+‐ATPase inhibitor, histamine‐induced increase in [Ca2+]i was significantly reduced, suggesting histamine induces Ca2+ release from inositol 1,4,5‐trisphosphate [Ins(l,4,5)P3]‐ and thapsigargin‐sensitive Ca2+ stores. Histamine‐induced peak in [Ca2+]i was increased dose‐dependently in the presence and absence of extracellular Ca2+. The histamine‐mediated response in [Ca2+]i was specifically attenuated by chlorpheniramine (H1 antagonist) but not by cimetidine (H2 antagonist), clearly indicating that activation of H1 receptor mediates histamine‐induced Ca2+ mobilization. We next examined the effect of histamine on inositol phosphates formation. Histamine stimulated the formation of inositol phosphates which changed time‐dependently. In particular, the formation of Ins(1,4,5)P3 was increased significantly for 10 s. The histamine‐induced Ca2+ mobilization caused an increase of prostaglandin E2 (PGE2) release which was reduced in excluding extracellular Ca2+. These results indicate that activation of histamine H1 receptor induces the accumulation of Ins(l,4,5)P3 and the following transient increase in [Ca2+]i, and elicits the release of PGE2 which may be coupled with Ca2+ influx.
Evidence that cyclosporine inhibits periodontal prostaglandin I2 synthesis
Authors: Nell A. , Matejka M. , Solar P. , Ulm C. , Sinzinger H. , Sinzinger H.
Published: July 2006

Cyclosporine (CsA) is a selective immunosuppressant widely used in clinical therapy. Like phenytoin and nifedipine, the drug is associated with gingival overgrowth. This study considers the interaction of CsA and prostaglandin I2 (PGI2), in particular the action of the drug on gingival tissue in vitro and in vivo. The PGI2‐synthesis of rat, rabbit and human gingival tissue was examined by bioassay. In vivo CsA‐therapy reduces gingival PGI2‐synthesis. The results furthermore show a dose‐dependent inhibition of PGI2‐synthesis by CsA (1–100 μg/ml) in vitro. PGI2‐synthesis from in vivo CsA‐pretreated probes was further dose‐dependently diminished by in vitro addition of CsA. As PGI2 exerts an antiproliferative activity via cAMP‐elevation, the drug‐induced inhibition of PGI2 production is claimed to be responsible for gingival hyperplasia in CsA‐treated patients.
Antigen‐presenting‐cell function of interferon γ‐treated human gingival fibroblasts
Authors: Shimabukuro Yoshio , Murakami Shinya , Okada Hiroshi
Published: July 2006

The present study was carried out to examine the antigen‐presenting cell (APC) functions of human gingival fibroblasts (HGF) elicited with IFNy. Stimulation of HGF with IFNy clearly induced HLA‐DR expression and enhanced expression of intercellular adhesion molecule‐1 (ICAM‐1) on HGF. Despite the phenotypical resemblance of IFNγ‐treated HGF to so‐called APC, HLA‐DR positive HGF were unable to induce proliferation of allo‐reactive peripheral blood T cells (PBT) isolated from different donors. The failure of IFNγ‐treated HGF to stimulate unprimed allo‐reactive PBT was not due to the lack of production of IL‐1 or the immunosuppressive effect of PGE2 from HGF. On the other hand, the fact that detectable expression of CD80, ligand for CD28, was not found on IFNy‐treated HGF may at least in part explain the ineffective function of HGF as APC. Interestingly, IFNγ‐treated HGF induced proliferation of primed allo‐reactive CD4+ T cells in a HLA‐DR dependent manner, suggesting that IFNγ‐treated HGF may have the ability to stimulate pre‐activated T cells. We then confirmed that high levels of IFNγ mRNA were detectable in inflamed gingival tissue. Although it cannot be concluded from this study that HGF are incapable of effectively presenting antigenic peptides to autologous T cells bearing appropriate T cell receptors, present results suggest that HGF may be affected by locally‐secreted IFNy and that the IFNγ‐stimulated HGF may play a role in regulating immune responsiveness in inflammatory periodontal lesions.
Immunolocalization growth factor (bFGF) in human periodontal ligament (PDL) tissue
Authors: Gao J. , Jordan T. W. , Cutress T. W.
Published: July 2006

The distribution of basic fibroblast growth factor (bFGF) in periodontal ligament (PDL) tissue was investigated in samples which were obtained from freshly extracted human teeth. The PDL tissue was collected by scraping, and bFGF was identified and localized by immunohistochemistry. Fibroblasts. endothelial cells, some fibrocytes and extracellular matrix (ECM) stained positively for bFGF It was observed that cells from healthy PDL stained more intensely than those from PDL of teeth associated with chronic periodontitis; histological cell counts revealed that the numbers of fibroblasts was greater (p<0.0005) in healthy PDL than in diseased PDL tissue. The results of this study show that bFGF is produced primarily by PDL fibroblasts and endothelial cells in the PDL and that bFGF levels may be decreased in tissue associated with chronic periodontal lesions.
Relationship of clonogenic capacity to plating efficiency and vital dye staining of human periodontal ligament cells: implications for tooth replantation
Authors: Lekic P. , Kenny D. , Moe H. K. , Barrettt E. , McCulloch C. A. G.
Published: July 2006

The survival rate of avulsed permanent teeth following replantation is affected primarily by the duration of the extra‐alveolar period and the nature of the storage conditions. These factors are believed to strongly affect the viability of periodontal ligament (PL) cells but in vitro assays of cell viability based on vital dye assays are only weakly correlated with the tooth survival rate after replantation. The aim of the present study was to examine the relative dependence of cell membrane integrity, attachment and clonogenic capacity of human PL cells on the temperature and duration of the extra‐alveolar period and the type of storage medium. Twenty‐four premolar teeth were extracted for orthodontic reasons from 9 patients 11–18 years of age. Teeth were maintained at 4°C or 23°C for 15, 30, 60 or 120 min in either milk or dry conditions. Cell membrane integrity was determined by BCECF/AM dye inclusion. Plating efficiency was determined by measurement of cell attachment at 3 and 6 h. The clonogenic capacity of progenitor cells was estimated by limiting dilution and colony counts. For all assays teeth stored in milk at 4°C showed the highest percentages of BCECF positive, attached cells with clonogenic capacity. Increased storage time (15–120 min) was associated with a 50% relative reduction of BCECF staining and a 5‐fold relative reduction of cell attachment regardless of storage conditions. However, the clonogenic capacity of progenitor cells decreased 25‐fold over the same duration of storage. These data demonstrate that in vitro assays of clonogenic capacity are much more sensitive to extra‐oral storage time and storage conditions than dye inclusion or cell attachment. We suggest that in comparison with in vitro measures of cell membrane integrity, the clonogenic capacity of PL cells is more closely linked to tooth survival rate, probably reflecting the capacity of PL progenitor cells to recolonize the root surface after replantation.
Digital image ratio: a new radiographic method for quantifying changes in alveolar bone. Part II: Clinical application
Authors: Jean A. , Soyer A. , Epelboin Y. , Ouhayoun J. P.
Published: July 2006

As reported in a previous paper (1) we have developed a new technique, Digital Image Ratio (DIR), which theoretically avoids some of the drawbacks of quantitative digital substraction radiography. DIR allows the direct computation and visualization of bone‐mass‐ratio changes. This second paper describes the use of DIR analysis to examine 20 sites in 8 patients undergoing regenerative periodontal therapy. Standardized reproducible radiographs of these 20 sites were taken before and 12 months after surgery. Ten experimental sites were treated with bone graft substitutes (natural coral or natural coral+collagen), and 10 control sites by debridement alone. None of the experimental sites had a density ratio below 1, where I indicates no change. The error was ±0.07 (0.93–1.07). The experimental sites showed an 18% mean increase in bone density (1.18), which increased to 23% (1.23) for sites filled with natural coral alone. All the control sites had values close to 1.00 (1.00±0.07) except for 3 sites, which showed a 9–15% loss of bone density. It is thus possible to compare and quantify the changes in experimental and control sites in the same patient using the percentage gain or loss of bone density. This demonstrates that DIR is suitable for clinical applications, and can be used in clinical analysis when bone changes are expected.
lnterleukin‐1β and phenytoin reduce α1 (1) procollagen mRNA expression in human gingival fibroblasts
Authors: Modéer T. , Andurén I. , Bengtsson A. , Andersson G.
Published: July 2006

Effects of and interactions between interleukin‐1β (IL‐1 β) and phenytoin (PHT) on α1 (I) procollagen gene and protein expression in human gingival fibroblasts and its relation to prostaglandin E2 (PGE2) formation were studied. IL‐1β (300 pg/ ml) reduced the steady‐state level of αl(I) procollagen mRNA by 50% and decreased the amount of procollagen I by 35%. PHT (10 μg/ml) reduced the level of α1(I) procollagen mRNA by 40% but the amount of procollagen I in the medium was unchanged. In combination with IL‐1β, PHT potentiated the inhibitory effect of IL‐1β on αl(I) procollagen mRNA level that was accompanied by an increased PGE2 formation. Preincubation with indomethacin (10‐6m) partially reduced the inhibitory effect of IL‐1β as well as of IL‐1β in combination with PHT on the mRNA level of αl(I) procollagen. The inhibitory effect of PHT was unaffected by indomethacin treatment. Addition of exogenous PGE2 (≥10 nm) dose‐dependently reduced steady‐state level of α1(I) procollagen mRNA as well as the amount of procollagen 1. The study indicates that IL‐1 reduces the expression of αl(I) procollagen mRNA in human gingival fibroblasts partly by a prostaglandin endoperoxide (PGH) synthase‐mediated pathway and partly by a PGH‐synthase independent pathway, whereas PHT reduces α1(I) procollagen gene expression by a PGH‐synthase independent pathway. The potentiation of the inhibitory effect of IL‐1 induced by PHT was mediated mainly by a PGH‐synthase dependent pathway.
Glucose modulates growth of gingival fibroblasts and periodontal ligament cells: correlation with expression of basic fibroblast growth factor
Authors: Ohgi S. , Johnson P. W.
Published: July 2006

Diabetes mellitus is a systemic disease with profound effects on oral health and periodontal wound healing. Uncontrolled diabetes adversely affects surgical wound healing and is often associated with abnormal proliferation of fibroblasts, excessive angiogenesis and poor bone regeneration. Human gingival fibroblasts and periodontal ligament cells from both diabetics and non‐diabetics were evaluated for growth responses following culture in 20 mM glucose, a concentration compatible with blood glucose levels in uncontrolled diabetics. Gingival fibroblasts derived from 9 non‐diabetic patients and 3 insulin‐dependent diabetics either proliferated or showed little change of growth in elevated glucose. Enhanced proliferation was observed following 1 wk of culture in glucose. Growth of periodontal ligament cells from 5 non‐diabetic patients was inhibited by 20 mM glucose. Fibroblasts that were markedly growth stimulated were probed for expression of basic fibroblast growth factor (bFGF) using a reverse‐transcribed polymerase chain reaction (RT‐PCR). Results indicate that fibroblasts exhibiting the greatest increase in growth in response to high glucose also exhibited increased expression of bFGF. No changes were observed in mRNA expression for platelet‐derived growth factor‐AA, platelet‐derived growth factor‐BB, insulin‐like growth factor and transforming growth factor‐β1. Mitogenic effects induced by the cytosol of fibroblasts exhibiting increases of growth in 20 mM glucose were abrogated by neutralizing antibodies to bFGF. In addition, some periodontal ligament cells that were growth inhibited by high glucose had reduced expression of bFGF. These data suggest that bFGF may play a role in the abnormal wound healing associated with periodontal surgery of uncontrolled diabetics.
Comparison of polymerase chain reaction and culture methods for detection of Actinobacillus actinomycetemcomitans and Porphyromonas gingivalis in subgingival plaque samples
Authors: Riggio M. P. , Macfarlane T. W. , Mackenzie D. , Lennon A. , Smith A. J. , Kinane D.
Published: July 2006

In this study, the major periodontal pathogens Actinobacillus actinomycetemcomitans and Porphyromonas gingivalis were detected in subgingival plaque samples from patients with periodontal disease by polymerase chain reaction (PCR) and conventional culture methods. 170 plaque samples from 43 patients were analysed; A. actinomycetemcomitans and P. gingivalis were each detected in 40 (24%) of samples by PCR. whereas conventional culture methods detected A. actinomycetemcomitans and P. gingivalis in 25 (15%) and 18 (11%) of samples, respectively. The proportion of patients carrying A. actinomycetemcomitans in at least 1 sampled periodontal site was 17/43 (40%) by PCR and 13/43 (30%) by culture; for P. gingivalis this was 2/43 (28%) by PCR and 9/43 (21%) by culture. Only 5 samples, from 3 patients, harboured both A. actinomycetemcomitans and P. gingivalis. It is concluded that PCR is more accurate than conventional culture methods for identification of these periodontal pathogens in subgingival plaque samples and has a higher frequency of detection.
Cytokine production by cells adherent to regenerative membranes
Authors: Wakabayashi R. C. , Iha D. K. , Niu J.‐J. , Johnson P. W.
Published: July 2006

Since cytokines play a critical role in tissue regeneration, we have assayed cytokine production by cells from tissue adherent to regenerative membranes. Cells were recovered from Gore‐tex® membranes used in guided tissue regeneration (GTR) procedures to regenerate the attachment apparatus around teeth and from Gore‐tex augmentation membranes (GTAM™) used for guided bone regeneration (GBR) procedures in edentulous ridge augmentation with or without implant placement. Cells were screened for mineralized nodule formation in vitro prior to mRNA analysis to demonstrate that they could form mineralized tissue. Production of interleukin‐1α (IL‐1α), interleukin‐1β (IL‐1β), interferon‐γ (IFN‐γ) and interleukin‐4 (IL‐4) was evaluated by reverse transcribed‐polymerase chain reaction (RT‐PCR) of mRNA from rescued regenerative cells, human gingival fibroblasts and periodontal ligament (PDL) cells. Both the gingival fibroblast and PDL cell isolates produced all 4 cytokines. However, the cell isolates from the regenerative membranes had various profiles of cytokine expression. Most GTR cell isolates were positive for all 4 cytokines. IL‐1β was produced by all 6 GTR cell isolates but was not detected at the same number of cycles of RT‐PCR amplification in any of the 6 GBR cell isolates. IL‐1β transcripts were also not observed in cells derived from a direct biopsy of GBR tissue. Cells recovered from unexposed GBR membranes did not produce detectable amounts of IFN‐γ, whereas cells recovered from exposed GBR and all GTR membranes produced IFN‐γ. These findings indicate that cells from regenerative tissue express different cytokines and that exposure of the tissue to the oral cavity during healing may modulate this expression.
Evaluation of a dental subtraction radiography system
Authors: Ellwood R. P. , Davies R. M. , Worthington H. V.
Published: July 2006

The aim of this in vitro study was to evaluate the ability of a dental subtraction radiography system to quantitatively detect differences in density between radiographic image pairs. Four periapical radiographs were taken of the upper first permanent molars on 5 human skulls using the Digora radiographic imaging system. The 4 images were a “baseline” image and 3 containing test objects consisting of either 0.5, 1 or 2 mm thick aluminium cylinders, 2.5 mm in diameter. Semi‐automated image processing software was used to “warp” the 3 images with test objects into the same geometric/density registration as the corresponding baseline image using a process called patch minimization. “Difference” images were then produced and their contrast stretched. For regions of interest, with and without test objects present, the difference in density between the baseline and “test object” images was calculated using a reference aluminium step wedge. The test objects were clearly visible in all the “difference” images. The mean difference between the actual and estimated volume of the test object was 0.31 (95% CI [−0.55, 1.17]) mm3 Al. There was a strong association (r=0.83) between the actual and estimated aluminium volumes. It is concluded that this system provides adequate precision for clinical evaluation.
Effective group behavioral intervention for older periodontal patients
Authors: Little S. J. , Hollis J. F. , Stevens V. J. , Mount K. , Mullooly J. P. , Johnson B. D.
Published: July 2006

A randomized clinical trial assessed the effect of a group‐based behavior modification intervention on oral hygiene skills, adherence and clinical outcomes for older periodontal patients. Subjects (n=107) were aged 50–70 yr with moderate periodontal disease. They were randomly assigned to usual care or intervention. Intervention consisted of 5 weekly, 90‐min sessions that included skill training, self‐monitoring, weekly feedback about bleeding points and group support focused on long‐term habit change. Four‐month follow‐up indicated significant improvements in the intervention versus the usual periodontal maintenance group for oral hygiene skills and self‐reported flossing (p<0.00l), plaque, gingival bleeding, bleeding upon probing throughout the mouth, and pocket depth for sulcus depths that measured between 3 and 6 mm at baseline (p<0.009). Group oral health intervention provides an effective and relatively inexpensive means of helping patients improve their self‐care skills and achieve high levels of adherence to an effective self‐care regimen.
Effects of sanguinarium, chlorhexidine and tetracycline on neutrophil viability and functions in vitro
Authors: Agarwal S. , Piesco N. P. , Peterson D. E. , Charon J. , Suzuki J. B. , Godowski K. C. , Southard G. L.
Published: July 2006

The effectiveness of an ideal antimicrobial agent depends on its ability to kill microbes with minimal toxicity to host cells. Depending on the treatment regimen, antimicrobial agents come into contact with host cells for various intervals of time. Sanguinarium (SANG), chlorhexidine (CHX) and tetracycline (TET) are 3 antimicrobial agents frequently used in the management of periodontal infections. However, their effects on host immune cells during different treatment regimens are not known. Due to their ability to serve as the first line of host defense against microbial infections, we have compared the effects of these antimicrobial agents on human neutrophil functions and viability. The results show that SANG is not lytic to neutrophils from peripheral blood or crevicular fluid, at all concentrations tested. However, exposures of neutrophils to very low concentrations of SANG (0.001%) inhibits neutrophil chemotaxis, oxidative metabolism and degranulation within 5 min. Increasing the exposure time results in a similar inhibition of neutrophil functions, albeit at 50–100 fold lower concentrations of SANG. CHX rapidly disrupts the cell membrane of both crevicular and peripheral blood neutrophils at concentrations above 0.005% within 5 min, and inhibition of all neutrophil functions is due to its lytic properties. While TET is least toxic to neutrophils, a dose dependent inhibition of neutrophil functions is dependent on the calcium concentrations of the cellular environment, and is observed only above 0.04% or higher concentrations in the absence of calcium. The data suggest that a critical cumulative concentration of these drugs is essential for their toxicity and inhibition of neutrophil functions. Therefore, both the length of exposure and the dose of the drug both are critical while considering the effectiveness of SANG, CHX or TET in the treatment of infections. Furthermore, due to differences in their mechanisms of action, the consequences of their effects on neutrophils may have significant bearing on tissue pathology as well as on their therapeutic efficacy.
Collagen implants do not preserve periodontal ligament homeostasis in periodontal wounds
Authors: Nguyen L. , Lekic P. , McCulloch C. A. G.
Published: July 2006

An improved understanding of the differentiation of periodontal ligament cells could facilitate the development of new treatment approaches for overcoming the loss of specialized cell types caused by periodontitis. To study healing of wounded periodontal tissues and the differentiation of mineralizing connective tissue cells in periodontal ligament, we have examined the influence of wound size and collagen implantation on the regeneration of periodontium and on immunohistochemical staining for osteopontin and bone sialoprotein. Four groups of Wistar rats were wounded by drilling through the alveolar bone and by extirpation of the periodontal ligament. Wounds were 0.6 or 1.8 mm in diameter and defects were either implanted with collagen gels or were treated without implants. Rats were killed at 1 wk or 2 months after wounding and tissue sections were stained with monoclonal antibodies against rat osteopontin and bone sialoprotein. Collagen implants strongly increased staining for osteopontin and bone sialoprotein in defects at 1 wk. By 2 months alveolar bone healed completely regardless of the wound size but in large defects, periodontal ligament width was significantly reduced with or without implants. In large wounds at 2 months, collagen implants inhibited bone regeneration and there was stronger staining for osteopontin and bone sialoprotein in the bone replacing the implant, indicating that collagen prolonged bone remodelling. We conclude that implantation of exogenous collagen affects alveolar bone healing but does not preserve the width of the regenerated periodontal ligament. Therefore collagen does not appear to contribute to homeostasis in the periodontium following wounding.
Effects of metronidazole on Porphyromonas gingivalis biofilms
Authors: Wright T. L. , Ellen R. P. , Lacroix J.‐M. , Sinnadurai S. , Mittelman M. W.
Published: July 2006

Subgingival bacteria exist within a biofilm consisting of cells and extracellular matrix which may afford organisms protection from both antibiotics and components of the host immune system. MIC values for planktonic Porphyromonas gingivalis treated with metronidazole were compared with those obtained for the same strain in biofilms associated with hydroxyapatite (HA) surfaces. The treated biofilms were examined for growth and studied by scanning electron microscopy. A broth assay resulted in an MIC of 0.125 μg/ml for metronidazole against P. gingivalis. P. gingivalis biofilms exhibited growth after treatment with 20μg/ml metronidazole, which was 160 times the MIC for planktonic organisms. The results of this study indicate that biofilm‐associated P. gingivalis may be resistant to metronidazole at concentrations which are usually attained by systemic administration.
A 5‐year study of attachment loss in community‐dwelling older adults: incidence density
Authors: Beck James D. , Cusmano Lisa , Greene‐Helms Wendy , Koch Gary G. , Offenbacher Steven
Published: July 2006

This is the second of three papers that present trends in attachment loss and tooth loss over a 5‐yr period in a population of community‐dwelling elderly blacks and whites. The first paper in this series showed that in addition to subject attrition during the 5 yr of the study, teeth also were lost. This loss of subjects and teeth resulted in trends that were not always consistent over time, because people were lost from the study and teeth with more active and advanced periodontal disease were more likely to be lost. In these instances, the incidence density (time‐to‐event) analytic strategy is useful. Incidence density is the average rate of occurrence for a fixed follow‐up period. In 1988, the University of North Carolina School of Dentistry initiated the Piedmont 65 + Dental Study, which was designed to elicit 800 dentate respondents in the 5‐county area who were examined again at 18, 36 and 60 months. Our findings indicated that for every 1000 sites followed for 1 yr in this population, 20.6 sites will experience attachment loss of 3+ mm. Incidence densities varied greatly by subgroup, indicating that certain characteristics predispose sites for attachment loss. A multivariate logistic regression model indicated that people who are smokers, Porphyromonas gingivalis positive, have 5 or more missing teeth, are not high school graduates, and have not had a dental visit in the last 5 yr are at higher risk of attachment loss. Posterior teeth and mesiobuccal sites are at higher risk. We conclude that incidence density analyses are useful for longitudinal periodontal data and we illustrate the use of incidence density rates to plan clinical trials.
A 5‐year study of attachment loss and tooth loss in community‐dwelling older adults
Authors: Beck James D. , Sharp Tonya , Koch Gary G. , Offenbacher Steven
Published: July 2006

Tooth loss is a widely recognized endpoint measure for the effects of periodontal diseases and the impact of periodontal therapy. In fact, traditional clinical measures of periodontal status often are considered to be surrogate endpoints in that they are assumed to be related to tooth loss. However, the strength of the relationship between attachment loss and tooth loss in a representative population of untreated subjects has not been studied extensively. The purpose of this paper is to present the trends in attachment loss over a 5‐yr period in a population of community‐dwelling elderly blacks and whites. Specifically, this paper presents attachment loss trends both at the person and tooth level to address the following issues; 1) whether teeth that experience attachment loss during 1 time period are more likely to be lost at the next time period; and 2) given similar levels of attachment loss, why are some people more likely to lose teeth? In 1988, the University of North Carolina School of Dentistry initiated the Piedmont 65 + Dental Study, which was designed to elicit 800 dentate respondents in the 5‐county area who were examined again at 18, 36 and 60 months. Our findings indicated that teeth with poorer attachment level at baseline had a higher probability of being lost during the next 5 yr and teeth that experienced attachment loss during a time period were more likely to be lost during the next time period than teeth without additional attachment loss. In addition, it appears that there are person‐level characteristics associated with increasing tendency towards tooth loss in people with similar periodontal status, a finding that may clarify the relationship between attachment loss and tooth loss.
Periodontal conditions in 35–44‐yr‐old adults in France, 1993
Authors: Bourgeois D. , Hescot P. , Doury J.
Published: July 2006

A national study was carried out in France in 1993 to assess the periodontal status of the population aged 35–44 yr. The study took part in the Second International Collaborative Study of Oral Health Outcomes developed and coordinated by the World Health Organization. The representative sample was composed of 1000 subjects. The Community Periodontal Index of Treatment Needs (CPITN) index was used. Gingivitis prevalence was high (80.4%) while 26.6% of dentate subjects had shallow pockets (4–5 mm). Deep pockets (> 6 mm) were rare (1.6%) concerning on average 0.1 sextant per subject; 87.5% of the 994 dentate adults needed periodontal treatment. Oral health education and scaling should reduce periodontal pathology in this population group.
Net‐shaped hydroxyapatite implants for release of agents modulating periodontal‐like tissues
Authors: Denissen H. , Beek E. van , Martinetti R. , Klein C. , Zee E. van der , Ravaglioli A.
Published: July 2006

Periodontal‐like tissues and, in particular, alveolar bone‐ and root cementum‐like material can theoretically be modulated by release of biochemical agents such as bisphosphonate (PCP), growth hormone (GH) and alkaline phosphatase (ALP) from the implant surface. The present research focused on porous ceramic hydroxyapatite (PCHA) implants. In the past the PCHA implants were machined on a lathe out of simple blocks of PCHA ceramic. This was a tedious and cumbersome method, often resulting in implants with undesirable characteristics: different porosities, cracks and fractures. Therefore a moulding technique was developed to sinter near‐net‐shaped PCHA implants at 2 different sintering temperatures: 1170°C and 1280°C, resulting in PCHA implants with porosities of 62. 06% (PCHA type 1) and 40.74% (PCHA type 2), respectively. After 1 h incubation in a 10‐2 M Solution of PCP, the total amounts adsorbed onto PCHA type 1 and type 2 were 114. 9·2. 1 ± 2. 1 gUg and 46. 1 1. 5 μg, respectively. This was approximately 5 times higher than after incubation for 1 wk in a 10‐4 M solution of PCP. The total amounts of PCP released after the observation period of '75 d from PCHA type 1 and type 2 after incubation in the 10‐2 M solution were 103. 1 ± 1. 8 μg and 42. 8 ±1. 5 μg, respectively. The total amounts released from type 1 and 2 after incubation in the 10‐4 M solution were 7. 4±0.4 jig and 4. 1 ±0.1 μg and 4. 1 ± 0.1 μg, fig, respectively. After 2 wk of incubation in a liver/bone/kidney ALP solution the total amount of ALP adsorbed onto PCHA type 1 implants was 5039±412 mU/ml. The total amounts of ALP released were 4674±438 mu/ml and 53 ± 20 mu/ml after 1 and 2 wk, respectively. The release of ALP was high at the beginning but slowed down thereafter. It was evident that despite the well‐known high bonding affinity of PCP to HA the release of PCP occurred steadily, over a long period of time in vitro .
On the interpretation of microbial clusters in periodontal disease
Authors: Cohen M. E.
Published: July 2006

Cluster analysis is sometimes used in periodontal research to describe patterns of microbial identifications observed among cases (subjects or sites). These patterns are assumed to define subsets of cases that are meaningful, in the sense of defining periodontal subgroups that have reliable differences in some aspect of their disease. However, cluster analysis is an exploratory, first‐stage technique that does not incorporate the machinery that allows one to evaluate the statistical significance and reliability of the patterns observed. Problems inherent in drawing inferences from cluster analysis are discussed and, as one methodological example of how the statistical significance of clustering might be determined, a randomization‐based test for binary scaled microbial identifications is described. The introduction of cluster analysis to the study of periodontal microbiology was important and innovative, but future work needs to incorporate validation by either statistical means or independent replication. The present rarity of such confirmatory methods in the literature suggests caution in accepting specific cluster‐based hypotheses about patient‐microbial patterns.
Characterization of the Porphyromonas gingivalis antigen recognized by a monoclonal antibody which prevents colonization by the organism
Authors: Booth V. , Lehner T.
Published: July 2006

Monoclonal antibody (MAb) 61BG1.3 prevented recolonization of deep pockets by Porphyromonas gingivalis in patients with periodontitis. The aim of this work was to identify the antigen recognized by the MAb. This was carried out by dose‐dependent inhibition with materials extracted from P. gingivalis and assessed by a radioimmunoassay. A protease preparation and a capsular extract inhibited about 95% of the binding activity, whereas LPS or fimbriae had no efrect. However, about 125 times greater concentration of the capsular than the protease material was needed to inhibit 50′% of the antibody activity, suggesting that the MAb recognizes the protease preparation and that the capsular extract contained some protease. Western blotting of MAb 61BGI.3 with recombinant prpR1 protein expressed in Escherichia coli confirmed that MAb 61BGI.3 recognizes the haemagglutinating protease and mapped its epitope to residues 748‐1130 of the β component of the polyprotein. Three major bands of Mr 45,000, 38,300 and 31,400 were detected in native whole cells of the virulent P. gingivalis strain W50 by Western blotting with MAb 61BG1.3. The MAb inhibited haemagglutination of human red blood cells by P. gingivalis or by a native protease extract. Blocking adhesion of P. gingivalis to the receptors on erythrocytes might be a mechanism by which the MAb inhibits recolonization by the microorganism.
The potential role of α2‐macroglobulin in the control of cysteine proteinases (gingipains) from Porphyromonas gingivalis
Authors: Gron H. , Pike R. , Potempa J. , Travis J. , Thøgersen I. B. , Enghild J. J. , Pizzo' S. V.
Published: July 2006

Porphyromonas gingivalis is closely associated with the development of some forms of periodontitis. The major cysteine proteinases released by this bacterium hydrolyze peptide bonds only after arginyl (gingipain R) or lysyl residues (gingipain K). No target protein inhibitors have been identified for either enzyme, leading us to investigate their inhibition by human plasma α2‐macroglobulin (α2M). Both 50‐ and 95 kDa gingipain R were efficiently inhibited by α2M, whereas the catalytic activity of gingipain K could not be eliminated. All 3 enzymes were, however, inhibited by a homologous macroglobulin from rat plasma, α1‐inhibitor‐3 a‐Macroglobulins must be cleaved in the so‐called “bait region“ in order to inhibit proteinases by a mechanism involving physical entrapment of the enzyme. A comparison of the aminio acid sequences of the 2 macroglobulins indicates that the lack of lysyl residues within the bait region of α2M protects Lys‐specific proteinases from being trapped. On this basis, other highly specific proteinases might also not be inhibited by α2M, possibly explaining the inability of the inhibitor to control proteolytic activity in some bacterially induced inflammatory states, despite its abundance (2‐5 mg/ml) in vascular fluids.
The reversal line may be a key modulator of osteoblast function: observations from an alveolar bone wound‐healing model
Authors: Romano P. R. , Caton J. G. , Puzas J. E.
Published: July 2006

The reversal line demarcates the cessation of osteoblast activity from the commencement of osteoblast activity at a remodeling site in bone. It is a seam between segments of bone that are formed at different times. We believe that the reversal line contains regulatory signals that, in part, control osteoblast activity. We have conducted a pilot study to examine the fate of reversal lines during abnormal bone remodeling in alveolar bone. A surgical periodontal defect was created in a Cynomolgus monkey (Macaca fascicularis), allowed to heal in the presence of plaque, and evaluated histologically. In this model, there is an acute inflammatory reaction followed by compromised bone formation. Woven bone rather than lamellar bone was deposited in the defect. A striking finding in this wound‐healing model was the disruption of the carbohydrate material along the reversal line. This supports our theory that disruption of the signaling molecules in the reversal line may be responsible for uneven woven bone formation.
Fibroblast heterogeneity in the periodontium and other tissues
Authors: Phipps R. P. , Borrello M. A. , Blieden T. M.
Published: July 2006

Fibroblasts are the major resident cells which inhabit the periodontal tissues. As such, they are crucial for maintaining the connective tissues which support and anchor the tooth. Little is known of their origins, synthesis of regulatory cytokines and growth factors in health and disease, and importance in soft tissue regeneration. An emerging concept is that fibroblasts are not homogeneous, but instead consist of subsets of cells which can regulate bone marrow‐derived cells such as T lymphocytes. Fibroblasts can be separated into subsets on the basis of morphology, size and expression of intermediate filaments as well as collagen subtypes. Differential surface marker expression has also been a key feature to distinguish fibroblast subsets from many tissues. Antigens such as Thy‐1, class 11 MHC, and Clq are among those surface proteins which have been employed successfully to separate fibroblasts. Importantly. these fibroblast subsets are not only antigenically diverse, but also possess distinct functions. Thy 1‐ pulmonary fibroblasts can display class 11 MHC antigens, synthesize IL‐1 and can activate T lymphocytes, whereas the Thy 1+ subset is devoid of these functions. Recently, fibroblasts from the human orbit have also been shown to be separable on the basis of Thy 1 surface marker expression. Fibroblasts derived from human gingiva and periodontal ligament also appear to be composed of subsets with a heritable pattern of surface markers which will permit their separation into functional subpopulations. This paper will review findings of fibroblast heterogeneity in periodontal and other tissues. Evidence will be presented for the use of surface markers to delineate functional subsets. The ability to discriminate subsets of fibroblasts will aid in studies of periodontal disease pathogenesis and wound healing.