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Considerable evidence has demonstrated the importance of PGE2 synthesis in the pathogenesis of periodontal disease. Although various cyclooxygenase inhibitors have been known to block periodontal PGE2 synthesis and prevent disease progression in animal models, there are few reports comparing relative efficacies of various inhibitors of arachidonic acid (ARA) metabolism. We have developed a sensitive in vitro assay to measure PGE2 synthesis in periodontal tissues. The apparent IC50 values (i.e. the concentration of drug which causes 50% inhibition of maximum PGE2 synthesis) have been determined for a series of arachidonic acid analogues as well as competitive and non-competitive cyclooxygenase inhibitors. Periodontal tissue homogenates were incubated in the presence of 3H-arachidonic acid for 45 min at 37 degrees C. Inhibitors were tested at 10(-10)-10(-4) M and at zero concentration to measure conversion of 3H-arachidonate to 3H-PGE2. Log or half log dilutions of inhibitors were tested in triplicate for each assay. Radiolabeled PGE2 was extracted from homogenates, purified by reverse phase chromatography and quantitated by double antibody capture. RIA was performed on each homogenate to determine the amount of endogenous unlabeled PGE2 present in the sample to correct for antibody capture recovery. The apparent IC50 values were determined for each drug by averaging two or more replicate assays. Specific total enzymatic activity of periodontal tissue homogenates was typically 5-11 pg PGE2/min/mg tissue.(ABSTRACT TRUNCATED AT 250 WORDS)

Periodontal plaque is a complex bacterial ecosystem that carries an innate history of colonization, selection and maturation. Detailed examination of this balanced environment can reveal developmental sequences and certain interrelationships, much like an archeological record, that can provide insight in the understanding of plaque formation and maturation. For the present investigation, methods are employed which enable the retrospective elucidation of the historical data of plaque development and the nature of bacterial interactions. Nonparametric statistical methods are used to analyze risk, agreement and interdependence, following analytical techniques which are well established in medical epidemiology, but not generally employed in dentistry. The fundamental concept is that many organisms which are present in plaque prefer or require a pre-existing bacterial miliue for colonization and growth to steady-state level. Plaque samples and Ramfjord attachment level measurements were obtained from 60 adult periodontitis patients. Loosely adherent plaque was sampled and different morphotypes were enumerated by darkfield microscopy. The colonization of small spirochetes (S-SP) within the loosely adherent plaque was essential for the colonization of medium spirochetes (M-SP), odds ratio = 15.7 and filaments (FIL), odds ratio = 22.2. Thus, a temporal colonization sequence is inferred for FIL and M-SP, both requiring S-SP as a prerequisite morphotype. Medium spirochetes, in turn, are required for fusiform (FUS) colonization. M-SP also enhance the colonization of FIL and large motile rods (L-MO-R) within the loosely adherent plaque. These morphotypes were inferred to be sequentially interdependent, each preferring or requiring the presence of the preceding morphotype.(ABSTRACT TRUNCATED AT 250 WORDS)

The four principal metabolites of cyclooxygenase (CO) were examined during the progression of experimental periodontitis in the rhesus monkey Macaca mulatta. Thirty-two monkeys were divided in four disease-matched groups. Three groups were treated with flurbiprofen, a potent CO inhibitor, at either 0.027, 0.27 or 7.1 mg/kg/day delivered systemically by a subcutaneously-implanted osmotic mini-pump. We have previously described the findings indicating that flurbiprofen treatment significantly retarded clinical attachment loss (ALOSS), redness and radiographic bone loss (BLOSS). This investigation focuses on the changes in CO metabolites which occur during disease progression of ligature-induced periodontitis and on the dose-response relationship of flurbiprofen, as it relates to disease inhibition and the suppression of ARA metabolites within the crevicular fluid (CF). In untreated animals there was a statistically significant 3-fold increase in CF levels of prostaglandin E2 (PGE2) and thromboxane B2 (TxB2) at 3 months, as compared to baseline, which positively correlated with increases in redness, bleeding, ALOSS and BLOSS. CF-PGE2 and TxB2 levels reached a 6-fold peak at 6 months and returned to baseline by 12 months. Flurbiprofen (Fb) prevented the 3-month rise in TxB2, but did not affect the increase in PGE2. At 6 months, Fb administration caused a dose-dependent inhibition of both PGE2 and TxB2. Probit analysis of the dose-response data revealed that the concentration of Fb which caused a 50% inhibition of CF-TxB2 level (the IC50 value for TxB2 synthesis) was approximately two logs lower than the IC50 value for PGE2 synthesis, i.e. TxA2-IC50 = 0.013 vs. PGE2-IC50 = 1.35 mg flurbiprofen/kg/d. The slopes of the PGE2 and TxB2 inhibition curves were identical, consistent with a similar mechanism or singular enzyme for the site of action of Fb inhibition of CO activity. However, the kinetics and sensitivity of Fb inhibition were significantly different for the CO activity responsible for TxB2 and PGE2 synthesis, perhaps due to different compartmentalization of CO within different cell types.

Subgingival plaque samples were obtained from 162 sites in 27 adult periodontitis patients and 162 sites in 27 healthy patients using a standardized lavage technique. The distribution of 10 different microbial morphotypes was determined by darkfield microscopy. The lavage technique selectively samples the loosely adherent plaque at the base of the periodontal pocket and not the tooth-associated, adherent plaque. This standardized technique permits quantitative comparisons of numerical density of morphotype composition at different sites, in addition to qualitative comparisons or relative proportions. There was a significant positive association between the numerical density of each morphotype within the non-adherent plaque and the number of sites at which the organism was detected in both healthy and diseased subjects. A previously undescribed darkfield morphotype, has been detected with this method. This morphotype, a small motile coccobacillus (S-MO-CB) has been found to be the numerically dominant species in both health and disease. This morphotype has been recovered in pure culture following passage through a 0.4 mu filter and includes organisms of the Wollinella and Campylobacter genus. Non-motile organisms comprised less than 1-2% of the sample from healthy and diseased sites. Motile forms, such as spirochetes, had a high frequency of detection in healthy individuals. Analysis of pooled plaque samples revealed that the prevalence of cocci and fusiforms was significantly elevated in patients with healthy periodontium, as compared to patients with adult periodontitis. In adult periodontitis patients, the frequency of occurrence of medium spirochetes, filaments and small nonmotile rods was significantly elevated in pooled plaque. Analysis of individual sites indicated that the proportion and numerical density of most morphotypes within the non-adherent plaque were not significantly different in disease as compared to health. Disease is characterized by an increased % of small spirochetes and fusiforms at each site. At diseased sites which harbor small spirochetes, the numerical density is elevated four-fold, as compared to healthy sites which have small spirochetes. The numerical density of other morphotypes is not significantly different comparing healthy sites to diseased sites. Thus, the increase in the % of small spirochetes in disease in due to a site-localized four-fold increase in numerical density within the non-adherent plaque.

The four principal metabolites of cyclooxygenase (CO) were examined during the progression of experimental periodontitis in the rhesus monkey Macaca mulatta. Thirty-two monkeys were divided in four disease-matched groups. Three groups were treated with flurbiprofen. a potent CO inhibitor, at either 0.027, 0.27 or 7.1 mg/kg/day delivered systemically by a subcutaneously-implanted osmotic mini-pump. We have previously described the findings indicating that flurbiprofen treatment significantly retarded clinical attachment loss (ALOSS), redness and radiographic bone loss (BLOSS). This investigation focuses on the changes in CO metabolites which occur during disease progression of ligature-induced periodontitis and on the dose-response relationship of flurbiprofen, as it relates to disease inhibition and the suppression of ARA metabolites within the crevicular fluid (CF). In untreated animals there was a statistically significant 3-fold increase in CF levels of prostaglandin E2 (PGE2) and thromboxane B2 (TxB2) at 3 months, as compared to baseline, which positively correlated with increases in redness, bleeding, ALOSS and BLOSS. CF-PGE2 and TxB2 levels reached a 6-fold peak at 6 months and returned to baseline by 12 months. Flurbiprofen (Fb) prevented the 3-month rise in TxB2, but did not affect the increase in PGE2. At 6 months, Fb administration caused a dose- dependent inhibition of both PGE2 and TxB2. Probit analysis of the dose- response data revealed that the concentration of Fb which caused a 50% inhibition of CF-TxB2, level (the IC50 value for TxB2, synthesis) was approximately two logs lower than the IC50 value for PGE2 synthesis, i.e. TxA2-IC50 = 0.013 vs. PGE2-IC50= 1.35 mg flurbiprofen/kg/d. The slopes of the PGE2 and TxB2 inhibition curves were identical, consistent with a similar mechanism or singular enzyme for the site of action of Fb inhibition of CO activity. However, the kinetics and sensitivity of Fb inhibition were significantly different for the CO activity responsible for TxB2 and PGE2 synthesis, perhaps due to different compartmentalization of CO within different cell types. [ABSTRACT FROM AUTHOR]

The effect of the nonsteroidal anti-inflammatory drug flurbiprofen has been studied in the ligature-induced and spontaneous peridontitis model in the rehsus monkey, Macaca mulatta. Twenty -four adult monkeys with incipient peridontits were divided into three disease-matched groups. Two groups received flurbioprofen at dosages of either 0.27 mg/kg/d or 7.1 mg/kg/d delivered systimatically via osmotci minipump. A split-mouth approach was used, placing lignatures on one side and monitoring the progression of periodontitis at regular interval for 6 months. Clinical measurements included standardized radiographs, Ramfjord attachment level determination and assessments of redness, edema and bleeding on probing. There was a statistically significant inhibition of attachment loss (p<0.05), gingival redness (p<0.05) and bleeding on probing (p<0.05) in ligature-induced and spontaneous peridontits in the flurbiprofen-treated animals at 6 months. Eight of 8 ligated control monkeys losts attachment (mean loss of 1.06 mm/site). Only 3 of 15 flurbiprofen-treated ligated monkeys lost any significant attachment with an overall mean loss of 0.34 mm/site, which was significantly less than the control loss of 1.06 mm/site at p=4.46 × 10-3. The odds of a control ligated monkey undergoing attachment loss in 6 months are elevated 29.3-fold as compared to the flurbiprofen-treated cohort monkey group. Flurbiprofen treatment also significantly inhibited spontaneous attachment loss for 6 months as compared to control monkeys at p<0.005 . These data provide further evidence for the central role of cylcooxygenase product in the progression of periodontal disease. The ability of flurbiprofen to inhibit periodontal attachment loss, even in the presence of loss plaque accumulation, has significant implications for the potential use of flurbiprofen as an adjunctive periodontal therapeutic modality. [ABSTRACT FROM AUTHOR]

Longitudinal data were collected over a period of at least 18 months and up to 3 years on 41 adult periodontitis patients (AAP Type III and IV). Rainfjord attachment level measurements and sampling of crevicular fluid (CP) at each tooth were repeated every 3 months. A mean full mouth CF prostaglandin E2 (MCF-PGE) value was determined for each patient at each visit. The three-mouth monitoring was continued until a single site demonstrated a statistically and clinically significant attachment loss (ALOSS) episode. Results indicated that in ALOSS patients the MCF-PGE was significantly elevated at the ALOSS visit as compared to previous levels. Furthermore, the sites which had the ALOSS had elevated levels as compared to the contralateral no ALOSS control sites (305.6±56.5 vs. 65.7 ± 6.89 ng/ml, mean±SEM). One month following treatment the CF-PGE level dropped to 16.9± 3.4 ng/ml at the ALOSS sites. Since the MCF-PGE level increases preceding the attachment loss episode, reaches a maximum at the sites which actually undergo ALOSS, and subsides following treatment, the possibility of using the MCF-PGE level to predict an oncoming future ALOSS episode was examined. The ALOSS patients had a MCF-PGE level of 113.4±9.0 ng/ml 6 months prior to the ALOSS episode, which was significantly higher than the no ALOSS patients' MCF-PGE level of 50.1±7.1. Analysis of MCF-PGE levels as a screening test indicate that this measurement has a high degree of sensitivity, specificity, and a predictive value of 0.92 0.95. Thus, this method has significant merit as a diagnostic tool to determine if a patient is in a state of remission or about to undergo an attachment loss episode. [ABSTRACT FROM AUTHOR]