Changes in inflammatory mediators in experimental periodontitis in the rhesus monkey

Ligature-induced periodontitis was monitored for 6 months in eight Macaca mulatta monkeys to examine clinical status, radiographic bone level, and crevicular fluid (CF) levels of prostaglandin E2 (PGE2), thromboxane B2 (TxB2), interleukin-1 beta (IL-1 beta), tumor necrosis factor alpha, and leukotriene B4 (LTB4). A split-mouth design was used, with eight ligated teeth and eight contralateral nonligated teeth which develop soft-chow-promoted (spontaneous) disease. Ligated sites experienced an average attachment loss of 0.94 mm per site and linear bone loss of 0.88 mm per site, with spontaneous-periodontitis sites experiencing approximately half the loss of ligated sites. The CF mediator levels showed increased levels of PGE2 and TxB2 at the ligated sites, as compared with the spontaneous sites, with no significant contralateral differences in the IL-1 beta or LTB4 responses. The concentrations of LTB4 in CF reached an early threefold peak over the baseline level at 1 month. By 2 months there was a statistically significant threefold elevation in CF-PGE2 in the ligated sites and a twofold elevation in the spontaneous sites as compared to the baseline level (P = 0.041 and 0.008, respectively). The monocyte product IL-1 beta increased sharply at 2 months and returned to the baseline level by 6 months at both ligated and nonligated sites. Tumor necrosis factor alpha in CF was below the limit of detection at all sites throughout the experiment (i.e., < 2 ng/ml). The selective elevation of both PGE2 and TxB2 in ligated sites, compared with levels in spontaneous sites, in the presence of similar levels of LTB4 and IL-1 beta provides further evidence that these molecules regulate the magnitude of the tissue-destructive response in progressive periodontitis.

Principles and pitfalls of clinical trials design

Periodontitis and gingivitis trials can involve many complex experimental designs. The selection of a specific design and the details of the protocol can influence the magnitude of any effect observed, the generalizability of the results, and the clinical significance of the findings. The purpose of this paper is to review selected aspects of clinical trials including the overall clinical experimental design, controls, outcomes, sample size, and patient selection. Particular emphasis will be placed on periodontitis trials.

Digital radiology for implant treatment planning and evaluation

Digital radiology has provided the clinician with the ability to store and manipulate radiographic information. The purpose of this paper is to present two applications of digital imaging to implantology. The first application is a personal computer-based imaging technique which can be used to plan the placement of endosseous dental implants using three-dimensional computed tomography images obtained with commercial software. The second application uses digital subtraction radiography to assess longitudinal bony change around dental implants.

Digital subtraction radiography for the assessment of bone changes in rheumatoid arthritis

A digital subtraction radiography (DSR) method was developed to assess changes of bony erosions in the hands of patients with rheumatoid arthritis (RA). The method initially was validated in vitro using simulated lesions in cadaver hands. The sensitivity, specificity and accuracy in detecting simulated lesions were 84.6, 100, and 92.3%, respectively. This technique was then pilot tested clinically using 17 patients with RA and 5 controls with no arthritis. All subjects received the nonsteroidal antiinflammatory drug, flurbiprofen, during the 6-month study period. No progressive changes in bone were observed in the control group; however, 18% of the target joints studied in the group with RA showed significant erosive changes (positive or negative) which correlated with the clinical assessment. The results indicate that DSR may be useful in detecting small changes in erosions on hand/wrist radiographs of patients with RA.

Effects of NSAIDs on beagle crevicular cyclooxygenase metabolites and periodontal bone loss

This investigation focuses on the changes in the concentrations of cyclooxygenase (CO) products present within the crevicular fluid in naturally-progressing periodontitis in the beagle and the effects of various non-steroidal anti-inflammatory drugs (NSAIDs) on these metabolite levels and disease progression. Six groups of 5-6 beagles with periodontitis were followed for 6 months to determine the pretreatment rate of radiographic bone loss. At baseline, groups of animals were placed on soft chow to promote disease progression. Groups were treated with either placebo, three different formulations of systemic ibuprofen, systemic naproxen or topical flurbiprofen. During the 6-month treatment phase, crevicular fluid (CF) samples and radiographs were taken at regular intervals. Radioimmunoassay of CF samples from untreated animals demonstrated a steady increase in prostaglandin E2 (PGE2) over baseline values. At 1 month, CF-PGE2 levels increased 2-fold over baseline and, by 6 months, had reached a 5- to 6-fold elevation. Crevicular fluid thromboxane B2 (CF-TxB2) levels rapidly reached a 4- to 5-fold peak over baseline at 1 month and subsequently dropped to a 2-fold elevation for the remainder of the study. The rate of bone loss (BLOSS) in untreated animals increased 38% during the 6-month period, as compared to baseline pretreatment BLOSS rates. Overall, there was a significant depression in the CF levels of both PGE2 and TxB2 in all NSAID-treated groups. All NSAID treatments significantly retarded BLOSS, ranging from 21.0-36.9% of the control BLOSS rate. Furthermore, CO activation represents a major regulatory step in bone destruction and may thereby serve as an important site for pharmacological modulation.

Elastase as an indicator of periodontal disease progression

THIS STUDY SOUGHT TO EVALUATE the ability of gingival crevicular fluid (GCF) elastase to predict attachment and bone loss in human periodontitis. Thirty subjects who were medically healthy and had a history of progressive periodontitis were studied with an automated probe. Five sites in each patient were monitored bi-monthly for a 6-month period for attachment loss. Subtraction radiography was utilized at the beginning and end of the study to monitor bone loss. GCF elastase was measured at 0 month and then bi-monthly by collecting GCF on paper strips impregnated with PMN leukocyte elastase substrate inserted into the gingival crevice for 15 seconds. After 8 minutes of reaction time, the strips were scored relative to fluorescent standards in an ultraviolet view box. Strips were then eluted in methanol and total elastase measured by spectrofluorometry. Total elastase was significantly higher in sites demonstrating progressive attachment loss than in inactive sites (2.81 +/- .29 versus 2.03 +/- .07, P less than 0.0005) and sites demonstrating bone loss (2.32 +/- .17 versus 2.01 +/- .08 P less than 0.05). When considering the joint presence of bone loss and attachment loss of 1.0 mm or greater in the 6-month period following a visual elastase kit score of 2 or greater, the test kit shows a sensitivity and specificity of 82% and 66%, respectively. This study demonstrated that GCF elastase levels are significantly higher in sites demonstrating progressive periodontal attachment and bone loss assessed 6 months later and may serve as a predictor of future bone and attachment loss.

Radiographic methods for the detection of progressive alveolar bone loss

Intraoral transmission radiographs have been the primary diagnostic method for the assessment of bone support as well as for the detection and measurement of osseous changes due to periodontitis. The purpose of the present paper is three-fold. The first is to review radiographic techniques for the assessment of periodontal disease progression, presenting the strengths and weaknesses of each method while placing special emphasis on digital subtraction radiography. The second purpose is to present data from a recent study that compared the ability of digital subtraction radiography and automated attachment level probing to detect the same active sites. Thirty periodontitis patients and eight control patients were studied over a 6-month period. The results indicate that when these two sensitive methods for the assessment of progressive periodontitis were used there was concordance between the presence or absence of probing attachment loss and bone loss in 82.1% of the sites. The final goal of this paper is to present future directions for the quantitative analysis of digital radiographic images.

Quantitative digital subtraction radiography for the assessment of peri-implant bone change

The purpose of this study was to develop a digital subtraction technique to assess peri-implant bone change. The method uses subtraction radiography to enhance visualization of the area of change that has occurred between radiographic examinations, and superimposes the area of change on the original radiographs. Furthermore, a reference wedge allows calculation of the mass of the lesion. The method was validated using 21 small bony chips placed on 3 different skulls prior to the first radiograph. The chips were removed, a second radiograph taken, and the images subtracted. A morphologic method was used to isolate the lesion and the change in bone mass calculated. Overall, there was excellent correlation between the calculated lesion mass (mg) and actual lesion mass (r2 > 0.90). The utility of the method was demonstrated using a case that experienced implant failure. These data indicate that quantitative digital subtraction radiography may be of value in measuring peri-implant bone change in root form implants.

A semi-automated computer-assisted method for measuring bone loss adjacent to dental implants

The purpose of this study was to develop a repeatable method for measurement of bone support around root form and blade implants suitable for use in high-quality but unstandardized radiographs. 10 phantoms were fabricated to simulate progressive osseous defects around implants. Radiographs were taken in triplicate and digitized. Specialized software was written which placed a grid of known dimensions over the implant so that the top and the bottom of the grid were at the neck and the base of the implant, respectively. The investigators selected the edge of the bone at each point where the grid intersected the implant and the software automatically detected the implant edge. The software also outlined and displayed the defect on the computer monitor. Measurements were performed 5 times and the standard deviation was taken as a measure of the repeatability of the method. Repeatability for blades and root forms was 0.19 +/- 0.07 mm and 0.08 +/- 0.03 mm, respectively. There was no significant difference in the ability to measure bone loss in the blade versus the root form (p = 0.17, NS). These results indicate that this semi-automated computer-assisted method for measuring bone loss around implants is repeatable and may be of value for clinical trials using either root form or blade implants.

Inhibition of alveolar bone loss in beagles with the NSAID naproxen

The non-steroidal anti-inflammatory drug(NSAID) naproxen was studied in 11 beagle dogs over a 13-month period to determine its effect on the progression of periodontitis. Following a 6-month pretreatment period, 5 dogs received naproxen daily at a dosage of 2.0 mg/kg for 1 month, then 0.2 mg/kg for 6 months. Six control dogs received a gelatin capsule daily as placebo. Standardized radiographs were used to measure the rate of bone loss during the pretreatment and treatment periods. In the control dogs, the rate of bone loss was seen to increase during the treatment period although the increase was not statistically significant. In dogs treated daily with naproxen, the rate of bone loss in the treatment period was significantly less at 4 months of treatment; however, at 7 months the difference, though lower than pretreatment rate, was not significant. When the percent change in rate of bone loss during the overall 7-month treatment period was compared with pretreatment rate, the control dogs demonstrated a 38% increase in rate of bone loss during the treatment period contrasting with a 61% decrease in bone loss rate in naproxen-treated dogs. The data indicate that the non-steroidal anti-inflammatory drug naproxen can significantly inhibit alveolar bone loss in beagles. At 4 months of treatment the rate of bone loss in the naproxen-treated dogs was significantly less than pretreatment, but at 7 months of treatment the rate was no longer statistically significantly less than baseline. This probably reflects a dose response to naproxen treatment for, after 30 days of the treatment period, the naproxen dosage was reduced 10-fold due to tolerance by the beagle.

Use of digital radiography to demonstrate the potential of naproxen as an adjunct in the treatment of rapidly progressive periodontitis

The effect of the non-steroidal anti-inflammatory drug, naproxen, in reducing periodontal disease activity was assessed in 15 patients with rapidly progressive periodontitis. All patients in this double-blind study were treated with scaling and root planing. Thereafter, 7 patients receiving 500 mg naproxen b.i.d. for 3 months, and 8 patients received placebo. Disease activity was assessed in three ways. First, alveolar bone height was determined using standardized radiography. Second, alterations in alveolar bone metabolism were assessed using 99m-Tc-methylene diphosphonate uptake prior to dosing and 3 months later. Finally, bone loss or gain was detected using digital subtraction radiography. In this study, conventional subtraction images were processed to isolate the area of change and superimpose the change on the original radiograph. This allowed determination of both the direction and location of osseous changes. There was significantly less bone loss as determined by analysis of bone height during the 3-month study in the naproxen-treated patients when compared to the placebo-treated patients (p less than 0.001). Radiopharmaceutical uptake was significantly reduced in the alveolar bone in patients receiving naproxen (p less than 0.03), whereas no significant change was observed in the placebo-treated patients. Furthermore, the subtraction radiographs showed a significant increase in the proportion of teeth demonstrating bone gain in the naproxen-treated group. These findings indicate that naproxen may be a useful adjunct to scaling and root planing in patients with rapidly progressive periodontitis.

Contrast enhancement as an aid to interpretation in digital subtraction radiography

An initial study was performed to demonstrate the feasibility of pseudocolor contrast enhancement technique in digital subtraction radiography (DSR). DSR is an electronic image processing technique that has been shown to be of greater diagnostic value in the detection of small periodontal bone lesions than conventional radiography. Pseudocolor enhancement involves selectively assigning a unique color to each shade of gray present in a black-and-white subtracted image. Two image enhancement techniques were developed and tested in a phantom system consisting of extracted teeth set in blocks of plaster mixed with sawdust to simulate trabecular bone. It was found that experimentally induced periodontal lesions were more readily detected by the average clinician in both types of enhanced subtraction images than unenhanced subtractions. Furthermore, both enhancement techniques were of significantly greater diagnostic value for lesions smaller than 1.0 mm (p less than 0.001). The technique that colored an isolated area of interest was significantly more diagnostic at all depths tested (p less than 0.001 at 0.5 and 1.0 mm, and p less than 0.05 at 0.5 mm). Contrast enhancement may be a significant aid to the average clinician for the interpretation of DSR and the detection of small periodontal defects.

A periodontal probe with automated cemento--enamel junction detection-design and clinical trials

An automated periodontal probe has been developed to measure pocket depth and attachment loss in a single measurement under controlled force conditions. A natural anatomic landmark, the cemento-enamel junction (CEJ), is used as a reference for attachment level measurements. The CEJ is detected automatically by immediate digital postprocessing of simultaneous measurements of probe tip acceleration and displacement during probing. Clinical trials in the beagle dog model for naturally occurring periodontitis have shown that the automated probe, when used with 35 g probing force, has a repeatability of 0.16 mm and a bias of 0.09 mm. These results indicate that the automated periodontal probe is capable of attachment level measurements with a high degree of repeatability and validity.

Progression of probing attachment loss in adult periodontitis

Thirty patients with adult periodontitis were monitored using an automated periodontal probe for 6 months in order to determine the prevalence of active sites and the overall pattern of disease progression in active sites. The automated probe is capable of measuring probing attachment levels relative to the cemento-enamel junction with better than 0.2 mm of accuracy. The prevalence of disease activity was dependent on the threshold for probing attachment loss used. When the smallest threshold (0.4 mm) was used the prevalence of active disease was 29%, whereas a large threshold (2.4 mm) detected only 2% active sites. Regression analysis of the active sites revealed that 76% of the sites lost probing attachment consistent with a continuous model for disease progression. A small subset of sites demonstrated either bursts of activity or exacerbations and remissions of disease activity.

A comparison of probing and radiographic methods for detection of periodontal disease progression

Over the last decade new technology has increasingly been applied to periodontal probing and radiography to result in diagnostic methods with greater resolution, repeatability, and accuracy. The goal of this paper is to discuss these methods with special emphasis on data published within the past year. Moreover, this paper summarizes the state of our current understanding of the usefulness of these methods in patient care and research.

Detection of periodontal disease activity with a scintillation camera

The goal of this study was to assess the ability of a scintillation camera method to detect areas of active bone loss due to periodontitis. Technetium 99m methylene diphosphonate was used as the bone-seeking radiopharmaceutical. Bone-seeking radiopharmaceutical uptake (BSRU) was imaged and quantified in alveolar bone regions of interest with a scintillation camera and a computer. Analysis of the sequential radiographs over six months constituted the basis for determination of sites of active disease. The study was composed of two parts. First, 18 subjects, nine with adult periodontitis and nine controls, were enrolled in a cross-sectional study to determine whether the quantitative scintillation amera methodology detected differences in BSRU in periodontitis vs. periodontally healthy patients. Second, the nine patients with periodontitis were studied longitudinally in order to determine whether the BSRU examination was indicative of bone loss subsequently measured radiographically. In the cross-sectional study, the mean uptake ratio for the periodontitis group was significantly higher than that for the control group (1.63 +/- 0.06 and 1.42 +/- 0.04, respectively, p less than 0.01, t test). From the longitudinal study, the mean patient scintillation image uptake ratios were highly correlated with the mean bone loss determined from serial radiographs (p less than 0.01). The accuracy, sensitivity, and specificity of the quantitative gamma camera method for detecting site(s) of active bone loss within the region of interest were assessed relative to the longitudinal radiographic data. The accuracy, sensitivity, and specificity were 85%, 90%, and 79%, respectively. Alveolar bone scintigraphy with a gamma camera and computer may provide a simple and valid technique for the immediate indication of areas of periodontal disease activity.

Altering the progression of human alveolar bone loss with the non-steroidal anti-inflammatory drug flurbiprofen

The treatment of human periodontal diseases relies on mechanical and antimicrobial suppression of the etiologic bacteria. The ability to alter the progression of periodontitis by additionally blocking host pathways involved in the destructive process is an area of current research. Prostaglandins and other metabolites of arachidonic acid are believed to be important host mediators of the bone resorption of diseases such as periodontitis. We have previously examined the effect of inhibitors of prostaglandin production, non-steroidal anti-inflammatory drugs (NSAIDs), on inhibiting alveolar bone loss in beagles. The present study was designed to examine the effect of the NSAID, flurbiprofen, on slowing the radiographic loss of alveolar bone in the human. Fifty-six individuals with radiographic evidence of alveolar bone loss were recruited for study. Forty-four patients remained in the study for the data analysis of loss of alveolar bone. Following a 6 month baseline pretreatment period to measure the radiographic progression of bone loss, half of the patients were administered flurbiprofen, 50 mg. b.i.d., while half were administered a placebo. All patients received a subgingival scaling and pumice by a hygienist every 6 months. The rate of alveolar bone loss in a 2 year treatment period was compared to the baseline 6 month pretreatment period within and between patient groups. Throughout the study, teeth exhibiting obvious loss of bone were exited from study and treated with conventional mechanical therapy. At the end of the pretreatment period both patient groups had a similar mean rate of alveolar bone loss.(ABSTRACT TRUNCATED AT 250 WORDS)

Autoradiographic localization of technetium-99 methylene diphosphonate in growth sites of young mice

Conflicting reports about the localization of 99mTc-MDP in bone and cartilage are found in the literature. Possible binding sites include hydroxyapatite and non-osteoid matrix such as immature collagen. The present study used autoradiographs of demineralized and non-demineralized growth sites in young mice to demonstrate localization of 99Tc-MDP, and consequently 99mTc-MDP, in mineralizing cartilage and bone. Uptake of the isotope was seen in mineralizing bone and cartilage, associated with the mineral in contrast to the organic phase. The results indicate that bone seeking radiopharmaceutical uptake (BSRU) may detect alterations in the rate of mineralized phase in growth sites and thus has the potential to disclose skeletal growth disorders.

Nuclear medicine techniques for the detection of active alveolar bone loss

The use of bone-seeking radiopharmaceutical uptake (BSRU) as an indicator of periodontal disease activity was assessed in untreated beagles with naturally occurring periodontal disease, and in beagles treated with the non-steroidal anti-inflammatory drug, flurbiprofen. In untreated beagles, a single uptake measurement was indicative of the rate of bone loss subsequently determined by sequential radiographs. Beagles treated with flurbiprofen demonstrated a significant decrease in rate of bone loss and a corresponding decrease in BSRU. Transfer of this technology to untreated human subjects with moderate to severe periodontal disease also showed a positive correlation between a single measurement of BSRU and the rate of bone loss determined from sequential radiographs. Analysis of these data shows that a single BSRU examination may be indicative of periodontal disease activity.

MR demonstration of the nasal cycle in the beagle dog

Magnetic resonance (MR) imaging of periodic engorgement of the erectile tissue surrounding the turbinates in the beagle dog yields remarkably quiet data that are well fitted by a single sinusoidal wave form. This observation holds in spite of right-left asymmetries in the distribution of the MR signal. The nasal cycle also occurs normally in humans. Judging from the clarity of its MR representation in the dog, it is possible that this phenomenon could be confused in human MR with upper respiratory congestion associated with pathological processes.