A brief history of periodontics in the United States of America: Pioneers and thought-leaders of the past, and current challenges.

This paper summarizes historical events in periodontology in the United States over the past 200 years. The contributions of some of the key thought-leaders of the past are highlighted. Throughout the 20th century, the evolution of thought, leading to the views currently held regarding the pathogenesis and treatment of periodontal diseases, was significantly influenced by: (1) major changes in health-care education; (2) the emergence of periodontics as a specialty of dentistry; (3) the publication of peer-reviewed journals with an emphasis on periodontology; (4) formation of the National Institute of Dental and Craniofacial Research (NIDCR); and (5) expansion of periodontal research programs by the NIDCR. The two major future challenges facing periodontal research are development of a better understanding of the ecological complexities of host-microbial interactions in periodontal health and disease, and identification of the relevant mechanisms involved in the predictable regeneration of damaged periodontal tissues.

Microbial biogeography and ecology of the mouth and implications for periodontal diseases.

In humans, the composition of microbial communities differs among body sites and between habitats within a single site. Patterns of variation in the distribution of organisms across time and space are referred to as "biogeography." The human oral cavity is a critical observatory for exploring microbial biogeography because it is spatially structured, easily accessible, and its microbiota has been linked to the promotion of both health and disease. The biogeographic features of microbial communities residing in spatially distinct, but ecologically similar, environments on the human body, including the subgingival crevice, have not yet been adequately explored. The purpose of this paper is twofold. First, we seek to provide the dental community with a primer on biogeographic theory, highlighting its relevance to the study of the human oral cavity. We summarize what is known about the biogeographic variation of dental caries and periodontitis and postulate that disease occurrence reflects spatial patterning in the composition and structure of oral microbial communities. Second, we present a number of methods that investigators can use to test specific hypotheses using biogeographic theory. To anchor our discussion, we apply each method to a case study and examine the spatial variation of the human subgingival microbiota in 2 individuals. Our case study suggests that the composition of subgingival communities may conform to an anterior-to-posterior gradient within the oral cavity. The gradient appears to be structured by both deterministic and nondeterministic processes, although additional work is needed to confirm these findings. A better understanding of biogeographic patterns and processes will lead to improved efficacy of dental interventions targeting the oral microbiota.

Minimally invasive periodontal therapy for general practitioners.

There remains a high prevalence of mild-to-moderate forms of periodontal diseases in both developed and developing countries. Although many periodontal specialty practices currently place strong emphasis on implant surgery, periodontal plastic surgery and esthetics, general dentists and hygienists have often assumed more responsibility than periodontal specialty practices for the diagnosis, treatment, assessment and maintenance, and possible referral, of their patients. To address these current trends and challenges, this volume of Periodontology 2000 presents a series of topics on the basic biological principles of periodontal disease, as well as on approaches to diagnosis, treatment planning and treatment, in what is called 'conservative' or 'noninvasive' periodontal therapy. These topics include risk assessment of the periodontal condition; reduction, elimination and/or control of etiologies and risk factors, including mechanical, antimicrobial and host-modulation approaches; considerations for evaluation of clinical outcomes based on treatment approaches; and selected topics in laser therapy, halitosis and gingival recession.

Post-treatment supportive care for the natural dentition and dental implants.

Long-term successful treatment of chronic periodontitis requires placement of patients on post-treatment recall programs known as either periodontal maintenance therapy or supportive periodontal therapy. Selection of the recall intervals must be based on the specific needs of individual patients. A single recall interval (e.g. 6 months) is not suitable for all patients. The main purpose of these programs is to prevent the recurrence of periodontitis. The components of every periodontal maintenance therapy program include: review of medical/dental histories; complete oral examination with an emphasis on the detection of gingival inflammation; establishing whether the maintenance program is working by monitoring clinical attachment levels; evaluation of oral hygiene; and full-mouth supragingival and subgingival debridement (i.e. biofilm removal). Long-term post-insertion care for dental implants also requires a similar patient-specific recall program of supportive implant therapy. The main purposes of a supportive implant therapy program are to maintain a healthy peri-implant mucosa and thereby prevent the development of peri-implantitis. In cases in which plaque-induced peri-implant mucositis has occurred, a well-designed supportive implant therapy program can help return the mucosa to a healthy state. At the current time there is no consensus on the optimal interventions for the treatment of peri-implant mucositis. However, all effective supportive implant therapy programs emphasize meticulous oral hygiene practices, careful peri-implant examination, thoughtful analysis of risk factors and periodic removal of microbial deposits from the implants.

Analysis of streptococcal CRISPRs from human saliva reveals substantial sequence diversity within and between subjects over time.

Viruses may play an important role in the evolution of human microbial communities. Clustered regularly interspaced short palindromic repeats (CRISPRs) provide bacteria and archaea with adaptive immunity to previously encountered viruses. Little is known about CRISPR composition in members of human microbial communities, the relative rate of CRISPR locus change, or how CRISPR loci differ between the microbiota of different individuals. We collected saliva from four periodontally healthy human subjects over an 11- to 17-mo time period and analyzed CRISPR sequences with corresponding streptococcal repeats in order to improve our understanding of the predominant features of oral streptococcal adaptive immune repertoires. We analyzed a total of 6859 CRISPR bearing reads and 427,917 bacterial 16S rRNA gene sequences. We found a core (ranging from 7% to 22%) of shared CRISPR spacers that remained stable over time within each subject, but nearly a third of CRISPR spacers varied between time points. We document high spacer diversity within each subject, suggesting constant addition of new CRISPR spacers. No greater than 2% of CRISPR spacers were shared between subjects, suggesting that each individual was exposed to different virus populations. We detect changes in CRISPR spacer sequence diversity over time that may be attributable to locus diversification or to changes in streptococcal population structure, yet the composition of the populations within subjects remained relatively stable. The individual-specific and traceable character of CRISPR spacer complements could potentially open the way for expansion of the domain of personalized medicine to the oral microbiome, where lineages may be tracked as a function of health and other factors.

Bi-directional relationship between pregnancy and periodontal disease.

During pregnancy profound perturbations in innate and adaptive immunity impact the clinical course of a number of infectious diseases, including those affecting periodontal tissues. Conversely, it has been suggested that periodontal infections may increase the risk of adverse pregnancy outcomes. In this review, a summary of the literature associated with the bidirectional relationship between pregnancy and periodontal disease as well as the possible mechanisms behind this interaction were examined.

Learned and unlearned concepts in periodontal diagnostics: a 50-year perspective.

In the past 50 years, conceptual changes in the field of periodontal diagnostics have paralleled those associated with a better scientific understanding of the full spectrum of processes that affect periodontal health and disease. Fifty years ago, concepts regarding the diagnosis of periodontal diseases followed the classical pathology paradigm. It was believed that the two basic forms of destructive periodontal disease were chronic inflammatory periodontitis and 'periodontosis'- a degenerative condition. In the subsequent 25 years it was shown that periodontosis was an infection. By 1987, major new concepts regarding the diagnosis and pathogenesis of periodontitis included: (i) all cases of untreated gingivitis do not inevitably progress to periodontitis; (ii) progression of untreated periodontitis is often episodic; (iii) some sites with untreated periodontitis do not progress; (iv) a rather small population of specific bacteria ('periodontal pathogens') appear to be the main etiologic agents of chronic inflammatory periodontitis; and (v) tissue damage in periodontitis is primarily caused by inflammatory and immunologic host responses to infecting agents. The concepts that were in place by 1987 are still largely intact in 2012. However, in the decades to come, it is likely that new information on the human microbiome will change our current concepts concerning the prevention, diagnosis and treatment of periodontal diseases.

Comparison of the clinical features of chronic and aggressive periodontitis.

Overall, while most clinicians would agree that aggressive forms of periodontitis exist as clinical entities, the clinical distinction between chronic and aggressive periodontitis (especially generalized) is not clear cut. This may not be all that significant from a treatment perspective, in so far as individualized anti-infective therapies are effective for both forms of the disease. However, from a research perspective, it is essential that these diseases be clearly distinguished in order to gain a complete understanding of their etiology and pathogenesis. The relative lack of clinical inflammation often associated with the localized molar-and-incisor form of aggressive periodontitis has been commented on for almost 100 years, and it is generally accepted that this form of the disease is associated with a thin biofilm, at least in its early stages. In contrast, the presence of clinical inflammation in generalized aggressive periodontitis appears to be similar to that observed in chronic periodontitis, and in this situation age of onset and family history are important additional criteria for either diagnosis or classification. It is also generally recognized that chronic periodontitis may subsequently be superimposed on both localized and generalized forms of aggressive periodontitis. While this may have little bearing on the treatment of such cases, it could have an enormous impact on both the design and interpretation of research studies, whether basic science or clinical. This highlights the essential difference between a diagnosis and a classification, whereby a diagnosis is the clinician's best guess, leading on to a treatment plan, whereas a classification does not allow such flexibility, requiring non-overlapping case definitions for research purposes if the underlying etiology of these diseases is ever to be fully elucidated.

Antibiotic prescribing practices in periodontal surgeries with and without bone grafting.

BACKGROUND: The prevention of postoperative infection is often the basis for antibiotic prescription; however, the risks of unwarranted antibiotics and lack of guidelines for procedures involving bone grafts creates additional difficulty in decision making for practitioners. This study aims to evaluate practices in antibiotics prescribed for periodontal surgeries with and without bone grafting and acceptability of guidelines. METHODS: An anonymous survey was distributed to periodontists via the California Society of Periodontists e-mail listserv. The survey questioned prescribing practices for periodontal procedures, prescribing rationale, demographic and dental practice information, and acceptability of guidelines. Results were analyzed using McNemar tests and logistic regression. RESULTS: Practitioners were significantly less likely to prescribe antibiotics for traditional periodontal surgeries without bone grafting compared with socket preservation, guided tissue regeneration, guided bone regeneration, and sinus augmentation (P < 0.0001). Practitioners were significantly more likely to prescribe antibiotics with more complex bone grafting such as guided bone regeneration and sinus augmentation compared with socket preservation (P < 0.0001). The most common rationale for prescribing antibiotics with bone grafting was to decrease the chances of developing an infection. Seventy-five percent of practitioners reported they would follow guidelines for antibiotic prescription if they were developed by the American Academy of Periodontology. CONCLUSIONS: Practitioners are more likely to prescribe antibiotics with bone grafting and as complexity of the bone grafting procedure increases. Based on these results, the low incidence of infection in periodontal surgery cited in the literature, and willingness of practitioners to adopt guidelines, the establishment of evidence-based guidelines would be of benefit to the periodontal practicing community.

Unique etiologic, demographic, and pathologic characteristics of localized aggressive periodontitis support classification as a distinct subcategory of periodontitis.

BACKGROUND: Localized aggressive periodontitis (LAgP) occurs in 2% of African-American adolescents but only 0.15% of white adolescents. First molars and incisors are affected by rapid onset and progression. METHODS: This nonsystematic critical review evaluated published data for LAgP and chronic periodontitis (CP), focusing on potential differences in epidemiology, microbiology, immunology, genetics, and response to therapy. RESULTS: LAgP differs from CP by localization to incisors and first molars, early onset and rapid progression in adolescents and young adults, and a 10-fold higher prevalence in populations of African or Middle Eastern origin, often with strong familial aggregation. The bacterium Aggregatibacter actinomycetemcomitans and hyperresponsive neutrophils are frequently observed. Antibiotic and nonsurgical therapies are highly effective. CONCLUSIONS: LAgP differs in many ways from the far more common CP that affects older adults. The substantial evidence of dissimilarities summarized in this review strongly supports the classification of LAgP as a distinct form of periodontitis. PRACTICAL IMPLICATIONS: Classifying LAgP as a distinct subcategory of periodontitis will encourage future research and does not conflict with the newly proposed "staging and grading" system. The silent onset and rapid progression of LAgP make early diagnosis and frequent follow-up with patients essential for effective treatment.

Gingival enlargement among renal transplant recipients in the era of new-generation immunosuppressants.

BACKGROUND: Tacrolimus is a new-generation immunosuppressant as successful as cyclosporin in suppressing organ transplant rejection. Although cyclosporin is known to cause gingival enlargement (GE), tacrolimus has not been associated with this condition. We sought to explore the prevalence of GE among renal transplant recipients (RTRs) in relation to cyclosporin and tacrolimus while controlling for the effect of calcium channel blockers (CCBs) and supragingival plaque. METHODS: RTRs were recruited from our institution's Kidney Transplant Unit. Participants completed a standardized questionnaire and received a complete oral examination, including a soft tissue examination and a periodontal examination measuring probing depth, recession, bleeding on probing, plaque index (PI), and GE. RESULTS: Among 115 RTRs, 39 (34%) presented with GE, with the highest prevalence among those taking cyclosporin and CCBs (76%) and the lowest among tacrolimus users not on a CCB (15%). Tacrolimus was not found to be associated with GE. Cyclosporin was found to be associated with GE in a univariate analysis stratified by the use of CCBs, but multivariate analysis revealed that the only significant risk factors for GE were the use of CCBs and the widespread presence of abundant supragingival plaque (PI > or =2 on >40% of tooth surfaces). CONCLUSIONS: This study confirmed that tacrolimus is not associated with GE. Cyclosporin taken at the currently recommended low dosage and not in combination with a CCB may not be associated with a significant risk for GE in individuals with good oral hygiene. CCBs should be avoided among patients taking cyclosporin and those with poor oral hygiene.

A spatial gradient of bacterial diversity in the human oral cavity shaped by salivary flow.

Spatial and temporal patterns in microbial communities provide insights into the forces that shape them, their functions and roles in health and disease. Here, we used spatial and ecological statistics to analyze the role that saliva plays in structuring bacterial communities of the human mouth using >9000 dental and mucosal samples. We show that regardless of tissue type (teeth, alveolar mucosa, keratinized gingiva, or buccal mucosa), surface-associated bacterial communities vary along an ecological gradient from the front to the back of the mouth, and that on exposed tooth surfaces, the gradient is pronounced on lingual compared to buccal surfaces. Furthermore, our data suggest that this gradient is attenuated in individuals with low salivary flow due to Sjögren's syndrome. Taken together, our findings imply that salivary flow influences the spatial organization of microbial communities and that biogeographical patterns may be useful for understanding host physiological processes and for predicting disease.

Periodontal Diagnosis and Treatment in the Coming Decades.

The purpose of this article is to review the dominant paradigms and thinking behind periodontal diagnosis and treatment over the last 150 years, including the clinical characteristics paradigm, the classical pathology paradigm, and the infection/ host response paradigm, and to predict what changes may occur in the next 50 years, such as the molecular ecology paradigm.

Bisphosphonate therapy improves the outcome of conventional periodontal treatment: results of a 12-month, randomized, placebo-controlled study.

BACKGROUND: Bone loss in periodontitis results from inflammatory reactions that stimulate osteoclastic bone resorption. Bisphosphonates inhibit bone resorption and increase bone mass. This study evaluated the effect of bisphosphonate therapy as an adjunct to non-surgical periodontal treatment in patients with moderate to severe chronic periodontitis. METHODS: Patients were randomized (2:1) to one of two bisphosphonate therapies or placebo for 1 year. All patients received non-surgical periodontal treatment (scaling, root planing) and periodontal maintenance therapy every 3 months. Clinical assessments at baseline and 6 and 12 months included clinical attachment level (CAL), probing depth (PD), and bleeding on probing (BOP). Periodontal bone mass was assessed by dental radiographs at baseline and 12 months using fractal analysis and digital subtraction radiography (DSR). RESULTS: Seventy patients were randomized, 43 to the bisphosphonate group and 27 to the placebo group. Bisphosphonate therapy significantly improved CAL, PD, and BOP relative to the placebo group during the 6- to 12-month period (CAL, P = 0.0002; PD, P = 0.0156; BOP, P = 0.0079). There was no difference in the change in periodontal bone mass between the bisphosphonate and placebo groups as measured by fractal analysis and DSR. CONCLUSION: These data suggest that bisphosphonate treatment improves the clinical outcome of non-surgical periodontal therapy and may be an appropriate adjunctive treatment to preserve periodontal bone mass.

Value of the evidence-based consensus conference.

The purpose of this paper is to describe how the inherent strengths of an evidence-based (EB) workshop can be combined with the conventional wisdom generated by a group of experts participating in a consensus conference. A traditional consensus conference is an appropriate way to arrive at the best current way to do something if the knowledge base is insufficient to make a scientifically rigorous EB analysis of the clinical problem. The result is the best opinion of experts in the field. The EB approach is the application of a repeatable review process to an existing knowledge base that is relevant to a focused question of clinical importance. It is a powerful tool that can help dentists in clinical decision-making processes. A combination of the EB approach with a consensus conference provides the highest level of evaluation and the strongest level of evidence upon which to make clinical decisions. Application of any of these sources of information can be used in the development of healthcare standards. However, standards are complicated statements that blend current scientific knowledge and clinical judgment with cultural, societal, and economic issues. When healthcare standards are being developed or revised, it is important that all sources of information be considered and the target population and purposes of the standards be identified.

Diagnosis of periodontal diseases.

At the present time, the diagnosis and classification of periodontal diseases are almost entirely based on traditional clinical assessments. Supplemental quantitative and qualitative assessments of the gingival crevicular fluid and subgingival microflora can potentially provide useful information about the patient's periodontal disease. In certain situations, these supplemental risk-assessment tests may be particularly valuable in establishing the endpoint of therapy prior to placing patients on a periodontal maintenance program. Although the clinical utility of none of these tests has been validated, their further development is warranted. A genetic test for susceptibility to periodontitis has become commercially available. How best to use this and future host-based tests in clinical practice remains to be determined. Probing depth and clinical attachment loss measurements obtained with periodontal probes are practical and valid methods for assessing periodontal status. Computer-linked, controlled-force electronic periodontal probes are commercially available and are currently in use by some practitioners. Many of the logistical problems associated with subtraction radiography are being overcome and this powerful diagnostic tool may soon come into widespread use. Future developments in this and other imaging techniques are likely to have a profound effect on our approach to the diagnosis of periodontal diseases.

Specific fibronectin fragments as markers of periodontal disease status.

BACKGROUND: The diagnosis of progressing periodontal disease typically relies on retrospective methods that detect changes in the amount of periodontal breakdown. Fibronectin (FN) fragments are found in vivo in association with periodontal disease, and specific FN fragments compromise periodontal ligament cell functions in vitro. The overall goal of this cross-sectional study was to determine whether specific FN fragments are present in gingival crevicular fluid (GCF) and can be used as markers for periodontal disease status. The eventual goal is to test these FN fragments in a longitudinal study as potential markers of disease activity. METHODS: GCF was collected from 94 subjects with untreated periodontitis from clinically healthy, mild/moderate periodontitis, and severe periodontitis sites. Sites were defined on the basis of clinical criteria, including gingival bleeding index, probing depth, and clinical attachment level. Western immunoblotting was used to detect FN fragments in GCF using antibodies to specific FN domains, including the collagen/gelatin-, central cell-, and carboxyl terminal heparin-binding domains, plus the CS-1 site on the alternatively spliced V region and the EIIIA region. FN fragments identified by immunoblotting and analyzed by NIH image software were scored based on pixel intensity and an ordinal grade scale. RESULTS: We identified several fragments highly associated with severe periodontitis sites, including 40-kDa, 120-kDa, and 68-kDa fragments. CONCLUSIONS: This study demonstrates that specific FN fragments are markers for periodontal disease status and supports the role of FN fragments as potential components in the pathogenesis of periodontal disease.