bluuebunny/crossref_metadata_2025 huggingface dataset:
Inhibitory effect of a bisphosphonate (risedronate) on experimental periodontities in rats
Authors: Shoji K. , Horiuchi H. , Shinoda H.
Published: July 2006

The present study was designed to examine whether systemic administration of a bisphosphonate, risedronate, could prevent alveolar bone resorption in rats with experimental periodontitis. On Day 1, an elastic ring was placed around the neck of the right mandibular 1st molar to induce inflammatory periodontitis. The animals were given daily injections of either 0.9% NaCl (control group), or 0.8, 1.6 or 3.2 Öoles/kg (s.c.) of risedronate (experimental groups) from Days 1 to 7, and were killed on Day 8. Histological examinations and determination of bone mineral density in the interdental area between the 1st and 2nd molars with an image analyzer revealed that the presence of the elastic ring induced a loss of attachment and bone resorption in the control group. Vigorous bone resorption, with appearance of a large number of osteoclasts, was observed in the interdental and bifurcation areas. In the experimental groups, however, the resorption of alveolar bone and the loss of bone mineral content in these areas were prevented in a dose‐dependent fashion, especially at doses of 1.6 and 3.2 Ömoles/kg. Many osteoclasts were detached from the surface of the alveolar bone and had degenerated appearances, such as rounded shapes, loss of polarity and pyknosis. These results suggest that administration of risedronate is effective in preventing bone resorption in periodontitis.
Time and position‐specific expression of glycosaminoglycans in rat molar cementum related to physiological tooth movement
Authors: Kagayama M. , Sasano Y. , Akita H.
Published: July 2006

The role of glycosaminoglycans (GAGs) and proteoglycans during cementogenesis is not known. In this study, we have analysed the temporal and spacial expression of GAGs in the cellular cementum of 10–30 weeks old rats, immunohistochemically using monoclonal antibodies 2B6 and 3B3, specific for chondroitin 4‐sulfate/dermatan sulfate and chondroitin 6‐sulfate, respectively. Both 2B6‐and 3B3‐epitopes were expressed at similar position and time in the rat cellular cementum. Two types of cellular cementum were identified; GAG‐positve and GAG‐negative cementum. The former corresponded to the lightly stained and the latter to the darkly stained cementum in sections stained with haematoxylin and eosin. The GAG‐positive cementum was seen at the distal side of dentine surface and appeared most thick at middle of the apical half roots, whereas the other parts of the cementum were the GAG‐negative. Distribution of GAG‐positive cementum showed changes with age of animals. In 10–15 week old rats, the GAG‐positive cementum occupied most of the cementum layer, covering a thin layer of the GAG‐negative cementum. The cellular cementum of 20–30 week old rats consisted of three layers; GAG‐negative, GAG‐positive and GAG‐negative cementum from dentine to cementum surface, reducing the GAG‐positive area. Because our previous study has demonstrated that the lightly stained cementum is uncalcified, the present result suggests a correlation between calcification and contents of GAGs in the cellular cementum. Further, time‐ and position‐specific expression of GAGs indicates their relation to the physiological tooth movement, which has been known in the rat molars.
Detection of stable and active periodontitis sites by clinical assessment and gingival crevicular acute‐phase protein levels
Authors: Adonogianaki E. , Mooney J. , Kinane D. F.
Published: July 2006

The aim of the present study was to investigate whether incipient periodontal disease breakdown could be associated with changes in gingival crevicular fluid (GCF) acute‐phase protein levels. In addition, the potential of clinical indices to act as predictors of significant attachment level (AL) change was investigated. AL measurements were taken at baseline and 3 months using the Florida Probe stent handpiece from a total of 384 sites in 38 patients. The average standard deviation of duplicate AL measurements was 0.423. When the tolerance method was used to detect significant AL change, 3.9% of the sites lost attachment. When a less stringent criterion of AL change of ≥1 mm was used 9.9% of the sites lost attachment during the 3‐month period. With the exception of probing depth, baseline clinical parameters failed to predict AL change. Fourteen active periodontitis sites that demonstrated significant attachment loss were paired to stable periodontitis sites within the same patient. The levels of four acute‐phase proteins, namely α2‐macroglobulin (α2‐M), α1‐antitrypsin (α1‐AT), transferrin (TF) and lactoferrin (LF), and also albumin (Alb) were assessed in the same gingival crevicular fluid sample using sandwich ELISAs. Results were expressed either as ng/30 s and ng/μg Alb. Acute‐phase protein levels in GCF failed to differentiate between active and stable periodontitis sites at baseline. In conclusion, the degree of gingival inflammation of the tissues adjacent to the crevice/pocket seems to influence the levels of protease inhibitors and iron‐binding proteins in GCF to a greater extent than probing attachment loss.
Variations in the clinical sulcus depth of healthy human gingiva: a longitudinal study
Authors: Smith R. G. , Çakici Seval , Newcombe R. G.
Published: July 2006

Evidence is currently lacking that sulcus depths of fully erupted teeth remain unchanged in the presence of excellent oral hygiene and absence of overt gingival inflammation. In 44 healthy volunteers (age range 16–34 yr) exhibiting the above criteria, sulcus probing depths (PD) were measured with a flexible measuring strip at 6 mesio‐buccal (MB) and 6 bucco‐cervical (BC) sites on 6 occasions spanning a total period of 20 weeks. Analysis of the data obtained showed that PD had a total range of 0.5–4.5 mm, varying greatly between subjects, although each had a personally characteristic distribution of PD across different sites. Mean depths of MB sites and variations were greater than at BC sites. Fluctuations at BC sites may, however, be no more than measurement error whereas those at MB sites may be real, or may reflect the greater difficulty of access to MB sites than to BC ones.
Clinical, microbiological and immunological profile of healthy, gingivitis and putative active periodontal subjects
Authors: Tanner A. , Kent R. , Maiden M. F. J. , Taubman M. A.
Published: July 2006

Thirteen periodontally healthy subjects were monitored clinically for 6–12 months. Clinical measurements at 6‐weekly intervals included duplicate PD measurements, presence of plaque, redness, and bleeding on probing. Baseline measurements consisted of 2 visits I wk apart. Microbial samples were taken from 11 of the subjects who had completed at least 8 months of monitoring. Levels of serum antibodies to 12 periodontal species were determined from 10 subjects. Standard deviations of replicate PD measurements, computed for each subject, ranged from 0.2–0.3 mm over the monitoring period. Plaque and redness increased during monitoring, and showed a weak association with PD change. Baseline and follow‐up distributions of PD changes indicated that changes of > 1.5 mm could reasonably be considered to represent active sites. Five subjects demonstrated at least 1 site deepening by 1.5 mm over the period monitored, and these were considered putative active subjects. Sites from 2 subjects showed PD increases in the 6 wk just before sampling, and these were considered to represent active sites. Species associated with putative active subjects included Actinomyces naeslundii, Veillonella parvula, Selenomonas noxia and Prevotella nigrescens. Streptococcus sanguis, S. gordonii and Peptostreptococcus micros were associated with inactive subjects. S. gordonii and S. oralis were associated with health, whereas P. nigrescens was associated with gingivitis. Elevated serum antibodies were detected to A. actinomycetemcomitans in 4 subjects. The predominant microbiota of putative active subjects included some species previously associated with gingivitis, and some species previously associated with progressing periodontitis.
Growth factor modulation of fibroblasts in simulated wound healing
Authors: Bartold P. Mark , Raben A.
Published: July 2006

Growth factors are potent bioactive molecules responsible for the co‐ordination of many cell functions and interactions. Of these agents PDGF and IGF have shown particular promise as agents which may be used to stimulate periodontal regeneration. In order to further understand the mechanisms by which growth factors may work, a simple model of in vitro wound healing has been utilized to assess the effects of PDGF on human periodontal ligament fibroblasts and its potential to stimulate wound healing. Human periodontal ligament fibroblasts were plated into 24‐well plates and upon reaching confluence were wounded by creating uniform discoid lesions stripped of cells. The influence of various concentrations of PDGF on cell proliferation, cell migration and extracellular matrix synthesis was monitored. The results of this study indicated that in the presence of 10 ng/ml PDGF and 0.2% fetal calf serum, both cell proliferation and cell migration were significantly stimulated. In the wounded cultures, PDGF appeared to cause a moderate stimulation of proteoglycan synthesis compared to unwounded cultures. In conclusion, the model system tested appears to be useful for studying fundamental cellular and biochemical events associated with wound healing. The effects of PDGF in this system confirm that it is capable of modulating fibroblasts in a manner compatible with the events associated with wound repair.
Effects of streptozotocin‐induced diabetes on neurogenic inflammation of gingivmucosal tissue in rat
Authors: Györfi A. , Fazekas Á. , Fehér E. , Ender F. , Rosivall L.
Published: July 2006

It has been suggested that the unmyelinated small diameter afferent nociceptive Cfibres are impaired in diabetes mellitus. We have recently demonstrated that these fibres are the prerequisite for neurogenic inflammation induced by mechanical or chemical irritations. These experiments were designed to characterize the neurogenic inflammatory responses of gingivomucosal tissue in the early phase of experimental induced diabetes mellitus in rat. Effect of dental ligature on the gingivomucosal (GM) vascular permeability was studied in control rats and in rats pretreated with streptozotocin at d 7 and 14 following streptozotocin administration. In separate groups of control and streptozotocin diabetic rats studies were also performed to investigate the effect of local capsaicin application on GM vascular permeability on d 14. Vascular permeability was assessed by means of Evans blue extravasation. The ligature placed around the mandibular left first molar caused a significant increase vascular permeability of GM tissue on the ipsilateral side on both d 7 and 14 after the ligation in control rats. In streptozotocin diabetic rats on d 7, there was also a significant elevation of Evans blue extravasation in the tissue tested on the ligature side. However, on d 14 the ligation failed to produce any changes in Evans blue extravasation on the ipsilateral side, i.e. no difference in GM vascular permeability could be recorded between the two sides in streptozotocin diabetic rats. Topical capsaicin administration produced significant Evans blue extravasation in GM tissue of control rats compared to that observed in diabetic rats on d 14 after streptozotocin treatment. Electron microscopic and light microscopic studies demonstrated fibre degeneration of the C neurones and less inflammatory cells in streptozotocin‐induced diabetes in the gingivomucosal tissue. These findings appear to indicate that the inflammatory responses induced by mechanical (dental ligature) and/or chemical irritants (topical application of capsaicin) in the gingivomucosal tissue are altered in streptozotocin diabetic rats and this alteration is due to the diabetes‐induced damage to the unmyelinated C fibres.
Dual X‐ray absorptiometry for alveolar bone: precision of periimplant mineral measurements ex vivo
Authors: Denissen Harry , Verhey Hans , de Blieck Jolanda , Corten Frans , Klein Christel , van Linger Arthur
Published: July 2006

The precision of measurements of minor mineral changes in alveolar bone mineral content (ABMC) and alveolar bone mineral density (ABMD) on implant surfaces was determined in small regions (0.03±0.005 cm2 using dual X‐ray absorptiometry (DXA). Dog hemimandibles with alveolar processes containing 17 implants were studied ex vivo. The precision was expressed as the coefficient of variation in percent (c.v. %) The ultra‐high resolution protocol was applied to the mesial, distal and apical subregions of each implant. The line spacing was 0.0254 cm and the point resolution was 0.0127 cm. The mean c.v. (%)±s.d. for the ABMC in the mesial, distal and apical regions were 0.42±0.I7,0.47±0.21 and 0.48±0.18, respectively. For the ABMD these values were 0.42±0.16,0.47±0.19 0.47±0.19 and 0.48±0.16. For each region approximately 68% of the 17 c.v. values were distributed within 1 s.d. from the mean c.v. These results indicate that measurements are highly reproducible (better than 0.48%) and that there are no differences in precision between several peri‐implant regions. Changes as small as 0.85% in ABMC and ABMD in small areas adjacent to implant surfaces are measurable with a confidence level of 95%. Therefore the DXA technique will be expedient for our research evaluating the efficacy of the ceramic hydroxyapatite implant releasing agents affecting or inducing alveolar bone‐ and root cementum‐like materials on its surface.
The synthesis of 5α ‐ dihydrotestosterone from androgens by human gingival tissues and fibroblasts in culture in response to TGIF‐β and PDGF
Authors: Kasasa S. C. , Soory M.
Published: July 2006

The effects of TGF‐β and PDGF on the metabolic conversion of 14C‐testosterone by human gingival tissue (HGT) from 5 subjects was investigated. The metabolic conversions in response to TGF‐β and PDGF were also studied in 4‐6 cell‐lines of cultured gingival fibroblasts, using 14C‐testosterone and 14C‐4‐androstenedi one as substrates. Duplicate incubations of HGT were performed in Eagle's MEM + 10% FCS and optimal stimulatory concentrations of TGF‐β/PDGF for 24 h. Similar incubations were performed in duplicate with cell‐lines of cultured gingival fibroblasts, TGF‐β PDGF, 14C‐testosterone/14C‐4‐androstenedione in Eagle's MEM + 10% FCS. The radioactive metabolites were extracted, separated and quantified. With HGT, TGF‐β and PDGF caused 2.5/12‐fold increases in DHT synthesis (p< 0.1; Wilcoxon signed rank test) and 3.4/12‐fold increases in 4‐androstenedione formation (p<0.1) from 14C‐testosterone. PDGF increased DHT and testosterone synthesis from 14C‐4‐androstenedione by 3‐fold in gingivae (p<0.1). With cell‐lines, average values of duplicate incubations showed 2.8/2‐fold increases in DHT synthesis from 14C‐testosterone in response to TGF‐β/PDGF (p<0.1; p<0.2) and 2.4/2‐fold increases in 4‐androstenedione synthesis (p<0.1; p<0.2). With 14C‐4‐androstenedione as substrate, TGF‐β/PDGF caused 1.611.9fold increases in DHT synthesis compared with controls (p<0.05; p<0.1) and 1.711.5‐fold increases in testosterone formation from this substrate (p<0.05; p<0.1). Due to the strong implications of TGF‐β/PDGF and anabolic androgens on matrix repair, significant increases in DHT synthesis from 2 androgenic substrates in response to TGF‐β and PDGF are of particular relevance to inflammatory repair processes.
Interleukin‐1α produced in human gingival fibroblasts induces several activities related to the progression of periodontitis by direct contact
Authors: Okamatsu Y. , Kobayashi M. , Nishihara T. , Hasegawa K.
Published: July 2006

Previous observations suggest that interleukin‐1 (IL‐1) may play an important role in the progression of periodontitis. In the present study, we investigated whether a cell‐associated IL‐1α (CAIL‐lα) produced in human gingival fibroblasts (HGF) induces biological activities related to the progression of periodontitis. HGF were treated with recombinant human IL‐1β (rhIL‐1β) for 12 h. After that, the cell layers of HGF were washed 3 times with fresh medium and were then fixed with 1% paraformaldehyde. The fixed cell layers of HGF were used for assays for bone resorbing activity, prostaglandin E2 (PGE2) production and collagenase activity. Fixed cell layers of HGF treated with rhIL‐1β enhanced not only calcium release from BALB/c mouse calvaria but also PGE2 production and collagenase activity in HGF and human periodontal ligament fibroblasts (HPLF) cultured on the fixed cell layers. These activities were neutralized by treatment with monoclonal mouse anti‐human IL‐1α antibody, but monoclonal mouse antihuman IL‐1β antibody showed no effects on these activities. The induction of these activities by fixed cell layers of HGF required direct contact between the fixed cell layers and the calvaria, HGF, or HPLF. These results suggest that CAIL‐1α produced in HGF treated with rhIL‐1β induces bone resorbing activity, PGE2 production and collagenase activity in the target cells by direct contact; CAIL‐lα may play an important role in the progression of periodontitis.
Natural distribution of oral Actinobacillus actinomycetemcomitans in young men with minimal periodontal disease
Authors: Müller H.‐P. , Zöller L. , Eger T. , Hoffmann S. , Lobinsky D.
Published: July 2006

A total of 1005 subgingival and extracrevicular samples from 201 male recruits, 18–25 yr old, were selectively cultivated for Actinobacillus actinomycetemcomitans. The organism was isolated in 55 subjects (27%); 9.5% of pooled subgingival plaque samples from first molars, 14% cheek mucosa, 20% dorsum of tongue and 20% saliva samples were culture‐positive. In order to divide the study population into distinct clinical categories, cluster analysis was performed, based on previous caries experience, probing pocket depth categories, bleeding scores, visible plaque and calculus. Two clusters (n=86 and n=92, respectively) were identified with no or minimal periodontal disease (mean±standard deviation % of periodontal probing depth 1–2 mm 78.7±10.4% and 57.4±12.6%, respectively; virtually no periodontal probing/depth in excess of 4 mm) and a relatively low DMF‐S (22±13). A third cluster (n=22) had, in contrast, a high DMF‐S (47.7±173) and a relatively high % of periodontal pockets of ≥5 mm (5.9 ±5.2%). Prevalence of A. actinomycetemcomitans in this cluster was 41%, while the organism was found in 23% and 27% in the minimally diseased populations (p<0.15). Whereas no heterogeneity of associations between subgingival and extracrevicular occurrence of the organism could be ascertained in different clusters, the organism was significantly more often identified in extracrevicular material, especially dorsum of tongue samples, compared with subgingival plaque (McNemar's X2=12.45, p<0.001). Multiple linear regression analysis revealed the number of A. actino‐mycetemcomitans positive samples as well as the % of sites bleeding on probing being positively associated with the % of sites with a probing pocket depth of ≥5 mm (R2=0.345, p≤0.0001). The present large‐scale investigation points to the wide distribution of this putative periodontopathogen in young individuals with minimal periodontal disease.
Effects of a rhubarb (Rhei rhizoma) solution and its fractions on the formation on of calcium phosphate precipitates
Authors: Hidaka Saburo , Nishimura Hiroaki , Nakajima Kaoru , Liu Sheng Yan
Published: July 2006

Inhibitory effects of a rhubarb (Rhei rhizoma) solution and its fractions on the formation of calcium phosphate precipitates were studied. The rhubarb solution inhibited both the amorphous calcium phosphate (ACP) formation and the rate of hydroxyapatite (HAP) transformation, and extended the induction time. When the solution was fractionated using membrane filters, a filtrate with the molecular weight between 3 and 10 kDa (with 2/3 recovery of polyphenols) was found to be responsible for both the ACP formation and the extension of the induction time. Another filtrate with the molecular weight below 3 kDa (with 1/3 recovery of polyphenols) may be responsible for the inhibition of both the ACP formation and the rate of HAP transformation, and the extension of the induction time. When the extract of rhubarb was fractionated using a Sephadex LH‐20 column chromatography, fraction IV greatly inhibited the formation of calcium phosphate precipitates, while fractions I, II, and III slightly inhibited that reaction. Our finding suggests that fraction IV may contain useful substance(s) for the prevention of oral calcium phosphate precipitation (calculus formation). However, strong calcium chelating properties would limit the concentration that could be safely employed.
The effect of ketoprofen creams on periodontal disease in rhesus monkeys
Authors: Li K. L. , Vogel R. , Jeffcoat M. K. , Alfano M. C. , Smith M. A. , Collins J. G. , Offenbacher S.
Published: July 2006

Ketoprofen creams were evaluated for the treatment of periodontal disease in a placebo‐controlled, double‐blind study in the rhesus monkeys, Macaca mulatta. Two formulations containing ketoprofen (1%), with or without vitamin E, were evaluated against appropriate controls (8 monkeys per group). Two weeks prior to treatment, the animals received prophylaxis on only the left side of the mouth (spontaneous model). Selected teeth on the right side of the mouth were ligated (ligature model). The creams were administered to the gingiva once daily at a standard dose of 1.8 ml per monkey for 6 months. Clinical assessments were made 2 wk before initiation, at baseline and 1, 2, 3 and 6 months post‐treatment. The clinical parameters included plaque formation, gingival redness, edema, bleeding on probing and Ramfjord Attachment Level measurements (RAL). Radiographs were taken at 2 wk before initiation, baseline and at 3 and 6 months post‐treatment. Digital subtraction radiography was used to measure vertical linear bone loss along the interproximal root surfaces of the left and right mandibular first molars. Gingival crevicular fluid (GCF) was collected for biochemical assays on PGE2, TxB2, LTB4, IL‐1β and TNFα. There were no significant differences among groups with respect to gingival indices. Radiographic data demonstrated significant positive effects on bone activity in both groups treated with ketoprofen formulations with improvement over time in the ligature model (0.01 ≤p≤ 0.04). The placebo group exhibited bone loss of 1.96±0.48 and 1.40±0.56 mm per site at 3 and 6 months, respectively. The group treated with ketoprofen cream showed an apparent bone gain of 0.28±0.41 and 0.78±0.47 mm per site at 3 and 6 months, respectively. The group treated with ketoprofen cream containing vitamin E showed a mean bone loss of 0.41–0.48 mm per site at 3 months with improvement to an apparent bone gain of 0.31±0.44 mm per site at 6 months. The biochemical data demonstrated early and significant suppression of GCF‐LTB4 by both ketoprofen formulations at 1 month, which preceded the significant suppression of GCF‐PGE2 at 2 and 3 months in the ligature model (p≤0.003) and at 2 to 6 months in the spontaneous model (p≤0.02). We conclude that ketoprofen at 1% level in suitable topical vehicles can effectively inhibit GCF‐LTB4 and GCF‐PGE2 and positively alter alveolar bone activity in the ligature‐induced model of periodontitis in the monkey.
Direct evidence of parasympathetic vasodilatation in cat periodontal ligament
Authors: Sasano T. , Shoji N. , Kuriwada S. , Sanjo D. , Izumi H. , Karita K.
Published: July 2006

Sympathetic regulation of periodontal ligament blood flow (PLBF) is well‐attested; however, vasodilator responses mediated by parasympathetic nerve fibers have yet to be conclusively demonstrated in the periodontal ligament (PL). The present study was designed to determine whether parasympathetic vasodilator mechanisms do or do not exist in the cat PL. In our cats, the cervical sympathetic trunks were sectioned bilaterally prior to any stimulation in order to eliminate sympathetic effects on the vascular beds under study. Dynamic changes in PLBF, with mandibular lip blood flow (LBF) recorded for comparison, were investigated in cat mandibular canine teeth using laser Doppler flowmetry. The peripheral cut ends of the facial and glossopharyngeal nerve roots, which have been reported to contain parasympathetic nerve fibers to the oral tissues, were electrically stimulated intracranially. Such stimulation caused blood flow to increase in the ipsilateral PL and lip, without an increase in systemic blood pressure. These vasodilator responses in the PL and lip were sensitive to ganglion blockade (with hexamethoni‐um), indicating vasodilatation via activation of parasympathetic vasodilator fibers. In contrast, although intracranial stimulation of the trigeminal nerve root also induced increases in both PLBF and LBF, these were unaffected by hexamethonium, but reduced by tripelennamine, indicating antidromic vasodilatation via the trigeminal sensory nerve. These results suggest that parasympathetic vasodilator mechanisms do exist in feline PL.
The effects of CO2 laser and Nd:YAG with and without water/air surface cooling on tooth root structure: correlation between FTIR spectroscopy and histology
Authors: Spencer P. , Cobb C. M. , McCollum M. H. , Wieliczka D. M.
Published: July 2006

Morphologic and chemical characterization of root surfaces treated with either the CO2, laser, Nd:YAG, or Nd:YAG with water/air surface cooling (Nd:YAG‐C) was completed using scanning electron microscopy (SEM) and FTIR photoacoustic spectroscopy (FTIR/PAS). Specimens for morphologic analysis consisted of 20 extracted single rooted teeth unaffected by periodontal disease. The specimens were exposed at varying energy densities to a single pass of the laser. SEM examination revealed, for all lasers, a direct correlation between increasing energy densities and depth of tissue ablation and width of tissue damage. The Nd:YAG‐C required higher energy densities than either the CO2 or Nd:YAG lasers to achieve the same relative depth of tissue ablation. Regardless of energy density, and in contrast with other laser types, areas treated with the Nd:YAG‐C did not exhibit collateral zones of heat damage. Specimens for spectroscopic examination consisted of 12 disks, 6x2 mm, cut from debrided root surfaces of extracted, unerupted human molars. The spectral results indicate a substantial reduction in the absorption bands attributable to protein and an additional band at 2015 cm‐1 in specimens exposed to the Nd:YAG without water. In the presence of water/air coolant, the band at 2015 cm‐1 appears only at a substanially higher energy density. The spectra of the CO2 treated specimens, with the char layer present, show a significant reduction in the protein bands and additional bands at 2015 and 2200 cm‐1, that are tentatively assigned to the cyanamide and cyanate ions, respectively. These results suggest a reaction of the organic matrix and mineral with laser exposure.
Strong cytotoxicity to human gingival fibroblasts by Porphyromonas gingivalis ATCC 33277
Authors: Johansson Anders , Bergenholtz Axel , Holm Stig E.
Published: July 2006

The aim of the present study was to analyze the cytotoxicity of some bacterial species associated with periodontal diseases. The specificity of cytotoxicity was estimated against cells of various origin and from different individuals. The reference bacteria were Actinobacillus actinomycetemcoinitans, Porphyromonas gingivalis and Fusobacterium nucleatum. These bacteria were cultured for 24 h in liquid media and the supernatants were used in cytotoxicity assays. The target cells used were human gingival fibroblasts (GF). dermal fibroblasts (K4), gingival epithelial cells (E) and HeLa‐cells (HeLa). These cells were exposed at 4 h or 24 h, respectively, to various concentrations of culture supernatants from the selected bacteria. The influence on the viability and metabolism of the cells were estimated quantitatively as increase in neutral red uptake and lactic acid production. Growth medium supernatants of P. gingivalis 33277 were strongly cytotoxic to gingival fibroblasts after 24 h incubation, compared to supernatants of P. gingivalis 381 or W 50, A. actinomycetemcoinitans or F. nucleatum cultures. The toxic effect of P. gingivalis 33277 decreased drastically after heat inactivation, which indicates effects of proteins. By adding anti‐sera the cytotoxicity of P. gingivalis 33277 could be dose dependently neutralized, which was not the case when supernatants of A. actinomycetemcoinitans was tested. Target cells of epithelial origin did not show increased cytotoxicity to P. gingivalis 33277. The results of the present study strengthen the hypothesis that P. gingivalis remains as a suspect causative key component in periodontal diseases.
Cytokine‐induced endogenous procollagenase stored in the extracellular matrix of soft connective tissue results in a burst of collagen breakdown following its activation
Authors: van der Zee Erwin , Everts Vincent , Beertsen Wouter
Published: July 2006

Numerous data strongly suggest the involvement of cytokines and the matrix metalloproteinase collagenase (MMP‐1) in the pathogenesis of periodontitis. Recently, we have demonstrated that, upon culturing under the influence of IL‐ lα+EGF, a large amount of inactive procollagenase (MMP‐1) is stored in the extracellular matrix of periosteal tissue. We now show that this endogenous reservoir of proenzyme can be operative after activation with plasmin and is able to induce a rapid and almost complete breakdown of the collagenous extracellular matrix. The level of collagen degradation following activation showed a strong correlation with the amount of proenzyme that was incorporated in the tissue. The highest levei of degradation (70% of the total amount of collagenous proteins) was found with the IL‐lα+EGF‐treated explants, followed by those treated with IL‐1α alone (35%). Explants cultured with EGF or in the absence of cytokines, containing only small amounts of procollagenase, showed little collagen breakdown following plasmin activation (7%). Inhibition of metalloproteinases by EDTA, or blockage of plasmin by PMSF, prevented the degradation in all explants irrespective of the amount of proenzyme present in the tissue. Our findings demonstrate that endogenous proenzyme stored in a native connective tissue matrix can be activated at a later time interval which results in a massive breakdown of the tissue. This study shows a possible pathway of collagenase‐induced breakdown without recent de novo synthesis of the enzyme. Such a sequence may be operative in chronic inflammatory diseases, such as periodontitis, where production of procollagenase under the influence of cytokines spans a longer time period, whereas breakdown is often characterized by a cyclic behaviour.
Serum rheumatoid factor induced by intraperitoneal administration of periodontopathic bacterial lipopolysaccharide in mice
Authors: Hara Yoshitaka , Kaneko Takashi , Yoshimura Atsutoshi , Kato Ihachi
Published: July 2006

Serum rheumatoid factor (RF) level and peritoneal and splenic CD5+B (B‐1) cells in mice were examined after intraperitoneal administration of purified lipopolysaccharides (LPS) from oral periodontopathic bacteria; Porphyromonas gingivalis, Actinobacillus actinomycetemcomitans, Fusobacterium nucleatum and Capnocytophaga ochracea. F. nucleatum and C. ochracea LPS induced higher levels of serum IgM‐ and IgG‐RF, while P. gingivalis LPS showed the least induction. In addition, wet weights of spleen and serum IgM and IgG concentration were markedly increased in F. nucleatum LPS injected group. On the other hand, the proportion of CD5+ B cells to lymphocytes in the peritoneal cavity and spleen did not increase. The reason for this was not clear but conventional B cells (CD5+ B cells) might increase more rapidly with splenic enlargement than CD5+ B cells. These results suggested that RF induced by bacterial LPS may modulate immune responses against bacteria and plays an important role for defence and destruction of periodontal tissue.
Effects of recombinant interleukin‐1β on decorin gene expression in human periodontal ligament fibroblast and its possible transcriptional regulation
Authors: Lin J. M. , Yamauchi M. , Sato S.
Published: July 2006

Interleukin‐1 β (IL‐1β) is a potent regulator of osteoprogenitor cells and fibroblasts, and is believed to be responsible for the bone loss and connective tissue breakdown that occurs in periodontitis. Decorin, a major small proteoglycan in the periodontium, has been shown as an important mediator of the organization of the pericellular and extracellular matrix. Since the HPLF play a significant role in the regulation of extracellular matrix metabolism, it was important to clarify the causal relationship between cytokines, HPLF and proteoglycans. We investigated the effect of IL‐1β on decorin gene expression and its functional regulation to elucidate the intracellular mechanism mediating the action of IL‐1β. Quiescently confluent HPLF cultures were incubated for different treatment periods with various concentrations of IL‐1β and/or 10‐4 M cycloheximide (Cx) in culture medium supplemented with 1% charcoal‐stripped serum for different treatment periods. Northern hybridization analyses, using decorin cDNA probe, showed that IL‐1β increased the abundance of decorin mRNA in both a dose‐ and time‐dependent manner. Most of the stimulation was blocked by Cx, indicating that the regulation of decorin gene expression by IL‐1β may be via an indirect pathway, requiring new protein synthesis which regulates the promoter. Gel mobility shift analyses detected the specific DNA binding activity of a nuclear extract of AP‐1, but not NF‐κB, that could bind to the recognition site of decorin gene promoter fragments with the increased abundance in IL‐1β treatment groups. These results suggest that the increased transcription of decorin gene by HPLF in the presence of IL‐1β is mediated at least in part through the interaction of AP‐1 with the decorin gene promoter.
Evaluating the merits of option‐3 methods in relative attachment level measurement in a healthy population
Authors: Johnson P. , Yang M. C. K. , Magnusson I. , Kang T. , Ramirez J. , Hefti A. F.
Published: July 2006

Attachment loss is the principal clinical indicator for periodontal disease progression. However, the attachment measurement can be inaccurate due to outliers. A remedial scheme, the option‐3 scheme, has been suggested in the literature. This scheme involves first measuring the relative attachment twice at any given site. A third measurement is required if there is a large disagreement between the first two probings. When the third measurement is taken, there are several possible ways to make the final assessment of the true attachment level. Among them are the average of the 3 measurements, the average of the closest 2, and the median of the 3. This report evaluates the merits of the option‐3 scheme by comparing it with other schemes to reduce measurement variance and outliers. Since true attachment levels are unknown, we chose to check accuracy through measurement consistency between visits in healthy subjects using the fact that such subjects should have little real change in attachment levels. 12 healthy subjects participated in the study. They visited the clinic 4 times in 4 months. Two types of the Florida stent probe were used by 2 calibrated examiners. It was found that option‐3 schemes were more accurate than a single probing or duplicate probings in estimating the relative attachment level. The 3 final assessment schemes performed almost equally well from a practical standpoint, but the median was the best among them in a statistical sense.
Secretion of IL‐1β, TNF‐α, IL‐8 and IL‐1ra by human polymorphonuclear leukocytes in response to lipopolysaccharides from periodontopathic bacteria
Authors: Yoshimura A. , Hara Y. , Kaneko T. , Kato I.
Published: July 2006

Polymorphonuclear leukocytes (PMN) are the first cells that migrate into periodontal tissues and gingival crevices in response to invading pathogens. It was recently demonstrated that PMN have the ability to synthesize and release cytokines following appropriate stimulation, while it is not clear whether these capacities are directly related to periodontal destructive processes. We therefore investigated the amounts of the cytokines interleukin‐1β (IL‐lβ), tumor necrosis factor α (TNF‐α), IL‐8 and IL‐1 receptor antagonist (IL‐lra) secreted by PMN from healthy donors following stimulation with lipopolysaccharide (LPS) from 4 periodontopathic bacteria, Porphyromonas gingivalis, Actinobacillus actinomycetemcomitans, Capnocytophaga ochracea and Fusobacterium nucleatum, and the non‐oral bacterium Escherichia coli. A. actinomycetemcomitans, F. nucleatum and E. coli LPS stimulated the release of significantly greater amounts of IL‐lβ, TNF‐α and IL‐8 than the control unstimulated PMN (p<0.01). The levels of IL‐lβ, TNF‐α and IL‐8 released from cells stimulated with P. gingivalis or C. ochracea LPS were significantly lower than those of cells stimulated with A. actinomycetemcomitans or E. coli LPS (p<0.05). On the other hand, substantially greater amounts of IL‐lra were released from PMN stimulated with each LPS and from control unstimulated PMN during the first 6 h, and then significantly greater amounts of IL‐lra were secreted by PMN stimulated with A. actinomycetemcomitans and E.coli LPS during the following 12 h (p<0.01). The inhibitory effects of IL‐lra on the biological activity of IL‐1 in the supernatants of PMN were examined by the thymocyte comitogen proliferation assay. The supernatants of PMN stimulated with each LPS showed less biological IL‐1 activity as compared with the same doses of recombinant human IL‐lβ detected by enzyme‐linked immunosorbent assay. Furthermore, no activity was detected in the supernatants of PMN stimulated with P. gingivalis or C. ochracea LPS. These findings demonstrated that LPS from periodontopathic bacteria were capable of stimulating PMN to release not only pro‐inflammatory cytokines but also their inhibitors such as IL‐lra. Different secretion levels of these cytokines and their biological activities induced by the various LPS might be important in the onset and progression of periodontal diseases.
The modulatory role of cementum matrix on osteoblastic cells in vitro
Authors: Tenorio D. , Foyle D. M. , Hughes F. J.
Published: July 2006

The formation of new cementum is an important issue in clinical periodontology, as cementum is required to provide attachment for newly formed periodontal tissues to the root surface. In this study a model of cementogenesis in vitro was used in order to test the effects of root surface demineralization on the migration, attachment and formation of a cementum‐like tissue by osteoblastic cells cultured on cementum and to test the specificity of cementum matrix in modulating those effects by comparison of root co‐cultures with bone co‐cultures. It was demonstrated that root surface demineralization did not significantly alter the orientation, number and attachment of cells to the root co‐cultures. The results also demonstrated that cementum and bone matrix appear to behave differently in culture, as seen by their distinct action on the morphological profile of the attached cells and the extracellular matrix deposited by these cells. These results demonstrate that although cementum matrix appears to stimulate the production of cementum‐like tissue, this action is not confined to cementum matrix alone, since a similar material was also deposited on dentine and bone surfaces. Thus, these results do not support a specific action of cementum matrix on the modulation of the cementoblast phenotype. The use of co‐cultures of neonatal rat calvaria cells with root slices represents a promising model of cementogenesis in vitro; however, studies should be undertaken towards the indentification of markers to distinguish between cementoblast and osteoblast phenotypes in order to further validate this model.
Absence of adult dental anomalies in familial hypophosphatasia
Authors: Lepe X. , Roth well B. R. , Banich S. , Page R. C.
Published: July 2006

This paper is a supplemental report on 3 previous publications about a family in which 3 male children manifested gingival recession, alveolar bone resorption and premature exfoliation of their deciduous teeth without apical root resorption and without clinical signs of inflammation. Laboratory blood and urine studies in conjunction with an analysis of periodontal microflora and family pedigrees established a diagnosis of hypophosphatasia in these 3 children, as well as their father, the paternal grandmother and paternal great‐uncle. Clinical data also revealed that a son of the paternal great‐uncle and his daughter were similarly affected. The family pedigree is consistent with an autosomal dominant mode of transmission. The 3 brothers are now between the ages of 18 and 22 yr and all have complete permanent dentitions. Aside from some periodontal manifestations of prior dentoalveolar trauma, most of the findings of the periodontal assessment are within normal limits. All 3 exhibit moderate to severe caries and some degree of gingival inflammation, but minimal periodontal pathosis.
The effect of race, smoking and immunoglobulin allotypes on IgG subclass concentrations
Authors: Gunsolley J. C. , Pandey J. P. , Quinn S. M. , Tew J. , Schenkein H. A.
Published: July 2006

In previous studies we have demonstrated that serum IgG subclass concentrations are influenced by both race and periodontal disease diagnosis. Furthermore, we have shown that smoking habits modify the concentrations of some IgG subclasses in specific racial and diagnostic groups. In view of a large amount of data showing strong associations between immunoglobulin allotypes and IgG subclass concentrations we have investigated the effects of race, smoking and IgG allotype on IgG subclass concentration in a population of subjects with or without various forms of periodontitis. The results indicated that there are complex relationships between these factors in their effects on individual IgG subclass levels, and that effects unique to black or white subject groups, or to specific periodontal diagnostic groups and racial subgroups, were evident. In blacks with chronic adult periodontitis IgG1 was lower in smokers, while in generalized early‐onset periodontitis patients IgG2 was lower in smokers. IgG4 was independently affected by gender (males higher), smoking (smokers lower) and GM23 (GM23 positive subjects higher), in black subjects only. In white subjects, complex relationships between smoking and allotypic markers were noted but no influence of periodontal diagnosis was found. White GM23 negative subjects who smoked had lower levels of IgG1 than GM23 positive subjects. White GM2 negative subjects who smoked had lower levels of IgG2, than did those who did not smoke. In contrast, smoking had no effect on IgG2 levels in GM2 positive subjects. Thus, in addition to immunoglobulin allotype, smoking is associated with IgG subclass concentrations; furthermore, in black subjects, periodontal diagnosis, gender and smoking all influence IgG subclass concentrations. These results demonstrate that genetic and environmental factors can interact to influence levels of individual subclasses.
Evidence of an association between functional abnormalities and defective diacylglycerol kinase activity in peripheral blood neutrophils from patients with localized juvenile periodontitis
Authors: Hurttia H. M. , Pelto L. M. , Leino L.
Published: July 2006

Peripheral neutrophils from patients with localized juvenile periodontitis (LJP) show functional abnormalities, such as impaired locomotion and enhanced respiratory burst activity. A defect in intracellular signalling mechanism has been proposed to be responsible for some changes, but direct evidence is lacking. In this study we have determined the activity of diacylglycerol (DAG) kinase, an enzyme controlling the DAG/protein kinase C (PKC)‐pathway, in crude cytosolic and membrane fractions of neutrophils from 5 LJP patients and age and gender‐matched normal individuals. No difference was observed in the DAG kinase activity in subcellular fractions from unstimulated cells between the 2 groups. When normal neutrophils were stimulated with N–formyl–methionyl‐leucyl‐phenylalanine (FMLP), the enzyme activity was markedly increased in both subcellular fractions. In contrast, neutrophils from 3 of the 5 LJP patients tested completely failed to rise the DAG kinase activity upon chemoattractant stimulation. These data indicate that in some LJP patients the neutrophil DAG kinase may be defective. To examine whether a decrease in DAG kinase activity could account for some neutrophil abnormalities seen in LJP, normal neutrophils were treated with R59O22, a DAG kinase inhibitor, that has been shown to reduce DAG kinase activity in human neutrophils. Upon stimulation with FMLP, R59O22‐treated normal neutrophils showed significantly reduced chemotactic response and enhanced respiratory burst activity, two typical functional abnormalities featured by LJP cells. It is concluded that a defect in DAG kinase may cause, through an abnormal accumulation of the endogenous PKC activator DAG, some of the functional changes observed in neutrophils from LJP patients.
Loss of Fcγ receptor and impaired phagocytosis of polymorphonuclear leukocytes in gingival crevicular fluid
Authors: Miyazaki Akira , Kobayashi Tetsuo , Suzuki Takashi , Yoshie Hiromasa , Hara Kohji
Published: July 2006

Immunoglobulin G type II and III receptors (FcγRII and FcγRIII) are essential for polymorphonuclear leukocytic (PMNs) phagocytosis. Our previous study demonstrated a downregulation of FcγRIII on PMNs in gingival crevicular fluid (GCF). To determine whether this receptor downregulation may contribute to the periodontal host defence borne by PMNs, we examined the correlation between FcγRII and FcγRIII expressions and the phagocytic capacity of GCF‐PMNs. In order to verify at which level of cellular events the loss of FcγR occurs, we quantified mRNA levels to assess a de novo synthesis of these receptors. GCF was collected from 21 patients with adult periodontitis by gingival crevicular washing. Autologous peripheral blood (PB) PMNs served as control. Surface expressions of FcγRs and phagocytic capacity via FcγRs were analysed by flow cytometry. The difference in FcγR mRNA levels between GCF‐ and PB‐PMNs was assessed by reverse transcription‐polymerase chain reaction (RT‐PCR). The amplified products were visualized by agarose gel electrophoresis and the endproduct yields were quantified by computerized image‐analysis. Both FcγRII and FcγRIII expressions and phagocytic capacity on GCF‐PMNs were significantly lower than those on PB‐PMNs (p < 0.001). The downregulation of FcγRs on GCF‐PMNs significantly correlated with the phagocytic capacity (r = 0.66 for FcγRIII, p < 0.01; r = 0.50 for FcγRII, p < 0.05). The mRNA level of FcγRIII of GCF‐PMNs was significantly lower than that of PB‐PMNs (p < 0.05). Thus, GCF‐PMNs are characterized by the decreased surface expressions and mRNA levels of FcγRs, and the impaired phagocytosis.