Rediscovering Sig Socransky, the genius and his legacy.

Some individuals make contributions so vital to their field of knowledge that their names become almost synonymous with that field. This is the case of Sig Socransky and the field of periodontal microbiology. Sig Socransky, or simply Sig, was born in Toronto, Canada and received his DDS degree from the University of Toronto in 1957. He studied microbiology and periodontology at Harvard, receiving a certificate in 1961. That same year he was recruited to work as a Research Associate at the Forsyth Dental Center. In 1968, he was nominated Senior Member of the Staff and Head of the Department of Periodontology. During his 50-year career at Forsyth, Sig published over 300 manuscripts, keeping an average of 7 publications per year. His work had an indelible impact in the fields of periodontology and oral microbiology. All these accomplishments pale in comparison with the impact that Sig had on a personal level. We have collected testimonials from some of his former students, closest collaborators, and friends in an attempt to give readers an insight into Sig's personality. We hope we can offer those who knew him through his work a glimpse of how it felt to interact with this remarkable individual.

Actinobacillus actinomycetemcomitans and Porphyromonas gingivalis subgingival presence, species-specific serum immunoglobulin G antibody levels, and periodontitis disease recurrence.

BACKGROUND AND OBJECTIVE: The biological and clinical effects of antibody against periodontal pathogenic bacteria are incompletely understood. This study evaluated the inter-relationships among periodontal levels of cultivable Actinobacillus actinomycetemcomitans and Porphyromonas gingivalis, species-specific serum immunoglobulin G (IgG) antibody levels, and periodontitis disease activity. MATERIAL AND METHODS: Forty-three adults who had previously been treated for periodontitis and who also harbored cultivable A. actinomycetemcomitans or P. gingivalis were evaluated semiannually for clinical disease recurrence over a 36-month period. Each patient provided subgingival microbial samples, for the recovery of A. actinomycetemcomitans and P. gingivalis, from the two deepest pockets in each dentition sextant. A. actinomycetemcomitans and P. gingivalis serum IgG antibody levels were assessed using enzyme-linked immunosorbent assay (ELISA), together with whole-cell sonicate extracts from A. actinomycetemcomitans serotypes a-c and P. gingivalis ATCC 33277. Data were analyzed using the Mantel-Haenszel chi-square and Fisher exact two-tailed tests. RESULTS: Eighteen (60.0%) of 30 A. actinomycetemcomitans-positive subjects, and 10 (76.9%) of 13 P. gingivalis-positive subjects, exhibited recurrent periodontal breakdown within 36 months of periodontal therapy. Nineteen (67.9%) of the 28 patients with active periodontitis had A. actinomycetemcomitans or P. gingivalis serum antibody levels below designated threshold values. In comparison, 10 (66.7%) of 15 culture-positive clinically stable subjects showed A. actinomycetemcomitans or P. gingivalis serum antibody levels above threshold values. The difference between specific antibody levels in periodontitis-active and periodontitis-stable patients was statistically significant (p = 0.032). CONCLUSIONS: Serum levels of IgG antibodies against A. actinomycetemcomitans or P. gingivalis in periodontitis-stable patients were higher than those in patients with active periodontitis. The results suggest that elevated levels of IgG antibody against A. actinomycetemcomitans and P. gingivalis have a detectable protective effect against periodontal infections with these microorganisms.

The dentogingival epithelial surface area revisited.

Recent studies implicating periodontitis as a cause of systemic diseases have reported that the surface area of periodontal pockets exposed to bacterial biofilm ranges from 50 cm2 to 200 cm2. Since the root surface area of the typical human dentition (excluding 3rd molars) is 75 cm2, these estimates appear too large. The goal of this study was to relate linear periodontal probing measurements to the dentogingival surface area (DGES). The DGES comprises both the sulcular and junctional epithelium, present in health, as well as any intervening pocket epithelium present in periodontitis. Formulas to estimate the DGES from clinical measures were derived from a meta-analysis of root surface areas, published values of root length, and a study that related the percent remaining root surface area to the percent remaining root length. These formulas were applied to a survey of the adult US population, the Veterans Affairs (VA) Dental Longitudinal Study, and a population of individuals visiting a periodontist. Individuals without periodontitis had a typical DGES of 5 cm2. Among individuals with periodontitis, the mean DGES in the three samples ranged from 8 cm2 (ranging from 1 cm2 to 29 cm2) to 20 cm2 (ranging from 2 cm2 to 44 cm2). It was concluded that the mean DGES among individuals with periodontitis ranges from 8 cm2 to 20 cm2, considerably smaller than the range of 50 cm2 to 200 cm2 currently assumed.

A multidisciplinary approach to the diagnosis and treatment of early-onset periodontitis: a case report.

BACKGROUND: The diagnosis and treatment of early-onset forms of periodontitis (EOP) represent a major challenge to periodontists. In this case report, we describe a multidisciplinary approach for the treatment of a patient with severe generalized juvenile periodontitis (GJP). Our approach incorporates clinical laboratory evaluation with conventional concepts of periodontal pathogenesis and therapeutics to diagnose and effectively treat EOP. METHODS: The 17-year-old female patient presented with clinical and radiographic evidence of severe attachment loss. Microbiological testing showed the presence of known periodontal pathogens including Actinobacillus actinomycetemcomitans, Prevotella intermedia, and Porphyromonas gingivalis. Routine immunological tests did not reveal any of the functional defects thought to play a role in the pathogenesis of EOP After initiation of therapy, which consisted of scaling and root planing, supplemented with administration of systemic antibiotics, a reduction in probing depth and gain in clinical attachment could be demonstrated. Microbiological testing was used to monitor the composition of the periodontal microbiota and to adjust antimicrobial therapy accordingly. RESULTS: Using a non-surgical approach to treatment, except for 2 root amputations performed without flap reflection, we have been able to stabilize this patient's periodontal condition over the course of a 2-year follow-up period. CONCLUSIONS: This treatment strategy provides an efficacious alternative to more aggressive forms of therapy and should therefore be considered for the treatment of patients with severe EOP.

Comparative microbiological characteristics of failing implants and periodontally diseased teeth.

BACKGROUND: The purpose of this report was to compare the distribution of periodontal pathogens recovered from failing implants and teeth with adult and recurrent forms of periodontitis. METHODS: A total of 41 consecutive microbial samples from patients with failing implants (IMP) were received at the Microbiology Testing Laboratory (MTL) of the University of Pennsylvania over a 2-year period. Paired control samples were selected from samples received concurrently by MTL from 41 patients with a diagnosis of adult periodontitis (AP) and 41 with a diagnosis of recurrent or refractory periodontitis (RP). Patients' mean ages for the 3 categories were 59, 47, and 53 years, respectively. Samples were collected with paper points or scalers and shipped in prereduced medium by express mail to the laboratory where they were processed within 48 hours from the time of collection. Culture was used for detection of A. actinomycetemcomitans, C. rectus, P. intermedia/nigrescens, E. corrodens, P. micros, Capnocytophaga and Fusobacterium sp., enteric Gram-negative rods, Enterococcus and Staphylococcus sp., and yeast. P. gingivalis and B. forsythus were detected by indirect immunofluorescence. Morphotypes were enumerated by dark-field microscopy. RESULTS: The most frequently detected microorganisms from IMP were B. forsythus (59%), spirochetes (54%), Fusobacterium (41%), P. micros (39%), and P. gingivalis (27%). Recovery levels (mean +/- SD) were 1+/-1, 4+/-5, 4+/-5, 9+/-11, 1+/-2, respectively. The most frequently detected organisms for AP were B. forsythus (83%), Fusobacterium (80%), spirochetes (79%), P. gingivalis (59%), P. micros (51%), and E. corrodens (37%), at levels 2+/-2, 5+/-4, 9+/-6, 4+/-5, and 6+/-7, respectively. Corresponding data for RP were B. forsythus (85%), Fusobacterium (83%), P. gingivalis (60%), spirochetes (59%), C. rectus (56%), and P. micros (56%), at levels of 3+/-2, 8+/-8, 4+/-4, 2+/-2, 1+/-1, and 9+/-10, respectively. CONCLUSIONS: These results indicate that the detection frequency and levels of recovery of some periodontal pathogens in failing implants are significantly different from that of teeth with periodontitis; however, the detection frequency and levels of recovery are similar in teeth affected by adult and refractory (recurrent) forms of periodontitis.

Porphyromonas gingivalis, Prevotella intermedia and Bacteroides forsythus in plaque subjacent to bridge pontics.

This study examined the distribution of P. gingivalis, P. intermedia and B. forsythus in plaque on metallic and porcelain pontics adjacent to healthy and inflamed mucosa. Subpontic plaque was collected from 33 inflamed and 31 healthy sites. Plaque suspension was incubated with specific rabbit antisera to P. gingivalis (FDC 381), P. intermedia (ATCC 25261) and B. forsythus (FDC 335), and the labelled cells disclosed with fluorescein-labelled goat-anti-rabbit IgG by indirect immunofluorescence microscopy. Mean proportions of P. gingivalis, P. intermedia, and B. forsythus at inflamed sites were 0.60+/-0.75, 2.48+/-2.28, and 0.44+/-0.64% respectively, and at healthy sites 0.21+/-0.43, 1.27+/-1.05, and 0.15+/-0.18% respectively. These differences were statistically significant. Almost all sites were positive for P. intermedia, whereas only 12/31 healthy and 21/33 inflamed sites were positive for P. gingivalis. 18/31 healthy and 28/33 inflamed sites were positive for B. forsythus. P. intermedia was recovered in higher proportions from metallic pontics adjacent to inflamed sites (MI) than healthy sites (MH) or porcelain pontics next to inflamed (PI) or healthy sites (PH). P. gingivalis is was recovered in higher proportions from MI than PH. We conclude that both the nature of the pontic material and the health status of the mucosa affect the composition of the associated microbiota.

Treatment considerations in rapidly progressive periodontitis: a case report.

This article presents a concept for the control of periodontal pathogens in early-onset periodontitis and demonstrates the reparative potential of periodontal tissue when the infection is under control. The patient discussed here was diagnosed with rapidly progressive periodontitis. We were able to reduce the bacterial mass with scaling and root planing and, in conjunction with systemic antibiotics, return the microbial profile to the normal range. Microbiological testing was used to monitor the microbiota and to adjust antimicrobial treatment. Improvements in probing depths and attachment levels were monitored for more than 1 year. Tissue response to this treatment made surgical intervention unnecessary. Although not essential, orthodontic treatment enhanced cleansability and improved esthetics.

Clinical trials of endosseous implants: issues in analysis and interpretation.

The majority of contemporary endosseous dental implant systems are based on designs and materials that, over the last three decades, have proved to be predictably reliable. With proper surgical and prosthetic protocols, rates of implant loss have been held to 15% or less over a 5-year period. This information was obtained largely through longitudinal descriptive studies, primarily aimed at obtaining implant survival rates under ideal clinical conditions, with strict inclusion and exclusion criteria for admitting patients into the studies. It is important to emphasize that under conditions of routine clinical practice, where patient selection may be more relaxed than in clinical trials and clinicians attempt to stretch the limits of current technology, the survival rates may not necessarily match those reported in the literature. Since "surviving" implants may exhibit characteristics likely to lead to eventual loss of the implant, for example severe osseous defects, such implants may not necessarily be considered successful. Successful implants should fulfill a list of other criteria considered essential for long-term survival. Differences in implant design preclude some of these criteria from being uniformly applied to all systems. There is a need to identify criteria for success that can be applied to the majority of implant systems. Implants that fail to meet these criteria should be considered failures. Since failure rates may include "failed" as well as "failing" ("ailing") implants, the two categories should be listed separately. From a practical standpoint, implant failures can be grouped into "early" failures, primarily the result of surgical and/or postoperative complications, and "late" failures that arise during and following the restorative phase. The ability of individual systems to achieve excellent success rates, despite some major differences in their design from other systems, suggests that some requirements, initially considered essential for success, may not be as critical as originally believed. Examples include the need for submerging implants during initial wound healing or the need for stress breaking devices. On the other hand, a basic requirement for implant success, such as primary stability at the time of insertion and following loading of the implant, may be the unifying principle behind the need for adequate bone volume and density, longer or wider implants, and the 3 to 6-month delay recommended before implants are placed in function. With relatively low failure rates, a large number of patients may have to be included in long-term clinical trials before a statistically significant association can be established between failure rates and potential contributing factors. For the same reasons, and to avoid type 2 errors, large populations may be needed to show that two systems have comparable success rates. Proving the superiority of one system over another may require fewer subjects. Given the overall low failure rate and the tendency of failures to cluster in individual subjects, failure rates could be markedly affected by the attrition of a few critical subjects. Additional research is needed to validate methods in current use for the clinical determination of osseointegration, and the diagnosis and treatment of occlusal trauma and microbial infections around implants. Also, more reliable methods are needed for the identification of the primary cause(s) of implant morbidity; i.e., infection or occlusal factors.

Outcome failures of endosseous implants from a clinical training center.

In an effort to provide realistic clinical information from a "real-world" environment, the present retrospective study was undertaken to assess outcome failures after implant placement in a dental school clinical training center. A database was kept of the clinical information and was analyzed according to established parameters for implant outcomes. The demographics showed that over a period of 6 years, 80 different operators with a wide range of clinical experience had inserted 1,263 implants in a diverse patient pool of 380 individuals. Analysis of the outcomes showed a cumulative survival rate of 91.3%. The time of explantation, the type, size, and location of implants lost, and failure rates in smoking patients were also analyzed. The results indicated that the use of implants by operators with different levels of experience did not affect favorable outcomes.

Soft and hard tissue response to endosseous dental implants.

The last two decades have seen a remarkable growth in the development of dental implants and their incorporation into the practice of dentistry. This turn of events was made possible by an improved understanding of biological response of living tissues to implants as well as clinical trials that validated the long-term success of these implants. Despite major structural differences between teeth and implants, such as the absence of a periodontal ligament around implants, the latter appear to provide a reliable functional replacement for their natural counterparts. This review briefly summarizes the major structural differences of the interfacial region of teeth and dental implants and their supporting tissues. It focuses on our current understanding of the soft and hard tissue responses to submerged and nonsubmerged root-form dental implants. The influence of a number of factors that affect the tissue response is reviewed, including biomaterials, implant design, surgical technique, and the local microbiota. Our recently acquired ability to modulate wound healing with guided tissue regeneration and growth factors will undoubtedly play an important role in the future utilization and success rates of dental implants.

Utility of 5 major putative periodontal pathogens and selected clinical parameters to predict periodontal breakdown in patients on maintenance care.

The predictive utility of 5 major putative periodontopathic microbial species, "superinfecting" organisms, and several clinical periodontal parameters were assessed relative to periodontitis recurrence over a 12-month period in 78 treated adult patients participating in a 3-month maintenance care program. At baseline, pooled subgingival microbial samples were collected from each patient, and whole-mouth evaluations of probing depth, relative periodontal attachment level, furcation involvement, and indices of plaque and gingival inflammation were carried out. 67 (85.9%) subjects were culture-positive at baseline for presence of either Actinobacillus actinomycetemcomitans, Porphyromonas gingivalis, Prevotella intermedia, Campylobacter rectus or Peptostreptococcus micros, with 48 (61.5%) subjects yielding one or more of these species at or above designated threshold proportions of > or = 0.01% for A. actinomycetemcomitans, > or = 0.1% for P. gingivalis, > or = 2.5% for P. intermedia, > or = 2.0% for C. rectus, and > or = 3.0% for P. micros. Subgingival yeasts were recovered from 12 subjects, staphylococci from 7, and enteric rods/pseudomonads from 6; however, no subjects revealed > or = 1.0% baseline proportions of these "superinfecting" organisms in subgingival specimens. Periodontitis recurrence in subjects was defined as any periodontal site exhibiting either a probing depth increase of > or = 3 mm from baseline, or a probing depth increase of > or = 2 mm from baseline together with a loss in relative periodontal attachment of > or = 2 mm from baseline. 15 (19.2%) study subjects showed periodontitis recurrence within 6 months of baseline, and 25 (32.1%) within 12 months. The mere baseline presence of the 5 major test species and "superinfecting" organisms were not significant predictors of periodontitis recurrence over 12 months. However, a 2.5 relative risk for periodontitis recurrence over 12 months was found for subjects yielding one or more of the 5 major test species at or above the designated baseline threshold proportions (p = 0.022, Mantel-Haenszel chi 2 test). The positive predictive value for periodontitis recurrence of a microbiologic analysis encompassing the 5 major test species at or above the designated threshold proportions improved with increasing time from baseline, up to approximately 42% at 12 months. Baseline variables jointly providing in multiple regression analysis the best predictive capability for periodontitis recurrence in subjects over a 12-month period were recovery of one or more of the 5 major test species at or above designated threshold proportions, the proportion of sites per subject with > or = 5 mm probing depth, and the mean whole-mouth probing depth. These findings indicate that one or more of 5 major putative periodontal pathogens in elevated subgingival proportions together with increased probing depth predispose adults on maintenance care to recurrent periodontitis.

Efficacy of CPITN sextant scores for detection of periodontitis disease activity.

The relationship between CPITN sextant scores and periodontitis recurrence at individual tooth sites was evaluated in a longitudinal study in 83 treated adult periodontitis patients receiving systematic 3-month maintenance care. At baseline and semi-annual examinations over 36 months, CPITN scores were assigned to each dentition sextant using probing depths and gingival index scores, and relative periodontal attachment level was assessed at individual tooth sites using an occlusal reference stent. Periodontitis recurrence was defined as any periodontal site exhibiting either a probing depth increase of > or = 3 mm from baseline, or a probing depth increase of > or = 1 mm from baseline together with a loss of relative periodontal attachment of > or = 2 mm from baseline. 49 (59.0%) subjects developed periodontitis recurrence in 147 (29.8%) sextants at 181 (2.2%) individual periodontal sites during the 36-month study period. Baseline CPITN scores of 4 were more common in disease-active subjects than clinically-stable subjects (p = 0.003, t-test), and were associated with a statistically significant 1.66 relative risk of periodontitis recurrence within 36 months. CPITN sextant scores of 3 or 4 showed low specificity and low positive predictive values as indicators of periodontitis recurrence at > or = 1 individual sites within the affected sextant. In comparison, low CPITN sextant scores (0-2) provided high specificity (96.2-100%), high positive predictive values (99.5-100%), and a summary odds ratio of 24.2 as an indicator of clinical stability at all periodontal sites within a given dentition sextant. Changes in sextant scores for CPITN over 6-month periods showed no relationship with periodontitis recurrence at individual periodontal sites. This study suggests that while CPITN is inadequate for detection of periodontitis recurrence, low CPITN scores provide rapid presumptive identification of clinically-stable sextants in adult periodontitis patients on maintenance care.

Comparison of randomly cloned and whole genomic DNA probes for the detection of Porphyromonas gingivalis and Bacteroides forsythus.

Whole genomic and randomly-cloned DNA probes for two fastidious periodontal pathogens, Porphyromonas gingivalis and Bacteroides forsythus were labeled with digoxigenin and detected by a colorimetric method. The specificity and sensitivity of the whole genomic and cloned probes were compared. The cloned probes were highly specific compared to the whole genomic probes. A significant degree of cross-reactivity with Bacteroides species, Capnocytophaga sp. and Prevotella sp. was observed with the whole genomic probes. The cloned probes were less sensitive than the whole genomic probes and required at least 10(6) target cells or a minimum of 10 ng of target DNA to be detected during hybridization. Although a ten-fold increase in sensitivity was obtained with the whole genomic probes, cross-hybridization to closely related species limits their reliability in identifying target bacteria in subgingival plaque samples.

Detection of Actinobacillus actinomycetemcomitans, Porphyromonas gingivalis, and Bacteroides forsythus in an A. actinomycetemcomitans-positive patient population.

A population of 33 subjects were selected on the basis that all had tested positive for A, actinomycetemcomitans at some time during the prior 7 years. Most subjects (31/33) belonged to families with a proband with confirmed localized juvenile periodontitis (JP); however, most subjects had no evidence of the typical lesions associated with JP. Two additional subjects with rapidly progressive periodontitis, known to be positive for A. actinomycetemcomitans, were also recruited. The patients with a history of JP had been treated, but were no longer enrolled in a regular maintenance program. With 3 exceptions, the subjects had not received any dental treatment or antibiotics in the past 3 months. One aim of the study was to determine the prevalence of A. actinomycetemcomitans, P. gingivalis, and B. forsythus in this population. The main purpose was to compare the relative sensitivity of various methods for detecting these periodontal pathogens. Pooled subgingival plaque samples were collected from all the mesial surfaces and aliquots of the suspension processed for the detection of A. actinomycetemcomitans by culture and indirect immunofluorescence (IF) to serotypes a, b, and c. P. gingivalis and B. forsythus were monitored with a DNA probe and IF. With culture, A. actinomycetemcomitans was detected in 39.4% of the samples, at a mean level of 0.64% of the cultivable counts. With IF, A. actinomycetemcomitans was detected in 81.8% of the samples, at levels of 0.40, 0.79, and 0.17% of the total counts for serotypes a, b and c respectively. Overall, IF was more likely to detect A. actinomycetemcomitans, P. gingivalis, and B. forsythus than any of the other methods.(ABSTRACT TRUNCATED AT 250 WORDS)

Utility of radiographic crestal lamina dura for predicting periodontitis disease-activity.

The relationship between radiographic crestal lamina dura and periodontitis disease-activity was studied longitudinally in 51 treated adult patients on a systematic 3-month maintenance program. The presence or absence of crestal lamina dura at 1809 interproximal sites was scored from periapical and bitewing radiographs taken at baseline of a 36-month maintenance care period. Semi-annual clinical evaluations by 2 independent examiners were carried out on each patient, with disease recurrence defined as sites revealing a > or = 3 mm increase in probing depth from baseline, or a > or = 2 mm increase in probing depth together with a > or = 2 mm loss of relative attachment level from an occlusal reference stent. Over the 36-month study period, 23 (45%) patients exhibited disease recurrence at 55 (3%) interproximal tooth sites scored for baseline crestal lamina dura. Absence of detectable baseline crestal lamina dura yielded high sensitivity (87-100%), but low specificity (17%) and low positive predictive values (0.8-3.2%), for localized periodontitis recurrence. In contrast, no sites exhibiting an intact baseline crestal lamina dura demonstrated periodontitis recurrence up to 24 months from baseline (100% positive predictive values). Presence of radiographic crestal lamina dura was positively associated with clinical periodontal stability (summary odds ratio for sites = 2.6, P = 0.0004), and negatively associated with periodontitis recurrence (summary odds ratio for sites = 0.4, P = 0.0004), for the 36-month study period. Evaluation of radiographic crestal lamina dura status appears valuable for assessing the risk of periodontitis disease-activity at inter-proximal tooth sites in patients on maintenance care programs.

Short-term healing of autogenous and allogeneic bone grafts after sinus augmentation: a report of 2 cases.

Sinus augmentation to facilitate the placement of cylindrical endosseous implants in the posterior maxilla has become more commonplace, and many different materials have been used for the sinus graft. The results of two sinus augmentation procedures, one grafted with demineralized freeze-dried bone (DFDB) and the other with autogenous iliac bone, are presented. Bone cores were obtained with a trephine drill from the grafted regions at the time of implant placement. Eight implants were placed into the grafted areas in each subject. The sample from the sinus grafted with autogenous bone was obtained 8 months postoperatively and the bone core from the sinus grafted with DFDB was taken 16 months postoperatively. The bone specimens were subsequently examined under light microscopy. The autogenous specimens demonstrated new bone formation with increased quantity and improved quality when compared to the specimens obtained from the sites grafted with allogeneic bone. All 8 implants placed into the autogenous grafts were clinically osseointegrated at stage 2. At 16-months postsurgery, the bone core taken from the site grafted with DFDB demonstrated poor bone quality and still contained remnants of the graft material in the region approximating the sinus membrane. Two of the 8 implants placed into the allogeneic grafts failed at stage 2. These findings suggest that autogenous sinus grafts produce bone of adequate quantity and quality for implant placement, whereas DFDB sinus grafts are not completely remodeled by the host and may produce bone of insufficient quality and quantity for predictable implant placement.

Proposed guidelines for American Dental Association acceptance of products for professional, non-surgical treatment of adult periodontitis. Task Force on Design and Analysis in Dental and Oral Research.

Guidelines are suggested for determining efficacy of products to supplement scaling and root planing in professional, non-surgical treatment of adult periodontitis. They result from an extended process including a conference on clinical trials in gingivitis and periodontitis, a subsequent workshop, and commentary from industrial, academic, professional and governmental members of the periodontal research community on two drafts. Recommendations are made in the broad areas of basic study design, subject and periodontal site selection, clinical management, choice of outcome variables, statistical summarization and analysis, and criteria for acceptance. Prominent dissenting views, with justifications for positions taken here, are also provided. Groundwork is laid for possible future guidelines addressing products for primary prevention or over-the-counter uses, or for determining superiority or equivalence of competing products. However, issues are identified which require further exploration before responsible and widely acceptable recommendations can be made in these areas. The guidelines suggested here are meant to form the basis of an evolving document rather than a static standard. It is suggested that they be reviewed frequently in the light of improvement in the technology available for periodontal research, and the emergence of products representing new approaches to periodontal therapy.