Treating periodontal diseases by blocking tissue-destructive enzymes

Pharmacological Therapies for the Management of Inflammatory Bone Resorption in Periodontal Disease: A Review of Preclinical Studies

Periodontitis, a highly prevalent multicausal chronic inflammatory and destructive disease, develops as a result of complex host-parasite interactions. Dysbiotic bacterial biofilm in contact with the gingival tissues initiates a cascade of inflammatory events, mediated and modulated by the host's immune response, which is characterized by increased expression of several inflammatory mediators such as cytokines and chemokines in the connective tissue. If periodontal disease (PD) is left untreated, it results in the destruction of the supporting tissues around the teeth, including periodontal ligament, cementum, and alveolar bone, which lead to a wide range of disabilities and poor quality of life, thus imposing significant burdens. This process depends on the differentiation and activity of osteoclasts, the cells responsible for reabsorbing the bone tissue. Therefore, the inhibition of differentiation or activity of these cells is a promising strategy for controlling bone resorption. Several pharmacological drugs that target osteoclasts and inflammatory cells with immunomodulatory and anti-inflammatory effects, such as bisphosphonates, anti-RANK-L antibody, strontium ranelate, cathepsin inhibitors, curcumin, flavonoids, specialized proresolving mediators, and probiotics, were already described to manage inflammatory bone resorption during experimental PD progression in preclinical studies. Meantime, a growing number of studies have described the beneficial effects of herbal products in inhibiting bone resorption in experimental PD. Therefore, this review summarizes the role of several pharmacological drugs used for PD prevention and treatment and highlights the targeted action of all those drugs with antiresorptive properties. In addition, our review provides a timely and critical appraisal for the scientific rationale use of the antiresorptive and immunomodulatory medications in preclinical studies, which will help to understand the basis for its clinical application.

Local administration of anti-hepatocyte growth factor-neutralizing antibody reverts naturally occurring periodontitis

OBJECTIVES

Periodontitis is a chronic inflammatory process associated with the loss of tooth-supporting tissue. The imbalance of epithelial-mesenchymal signaling is considered to drive disease progression, and hepatocyte growth factor (HGF) is one of the main mediators of this interaction. The aim of this study was to validate the role of HGF in the pathogenesis of periodontitis and to evaluate the effects of anti-HGF neutralizing antibodies.

METHODS

Gingival tissues from cynomolgus monkeys, which naturally develop severe periodontitis, were isolated to establish an in vitro periodontitis model. Periodontitis-affected monkeys were treated by gingival injection of anti-HGF neutralizing antibodies. The therapeutic effects were documented by clinical examination (probing depth and bleeding on probing), histological examination of tissue, and reevaluation of gingival fibroblasts in the in vitro model.

RESULTS

Periodontitis-affected monkeys contain periodontitis-associated fibroblasts (PAFs) with a pro-inflammatory phenotype that induced pronounced collagen degradation in vitro. This degradation was effectively inhibited by anti-HGF-neutralizing antibodies. Locally administered anti-HGF antibody to monkey gingiva clinically improved the severity of periodontitis. This was also reflected in the tissue histology with lower inflammatory cell infiltrates in treated gingiva than in non-treated gingiva. Moreover, fibroblasts isolated from anti-HGF-treated gingiva demonstrated reduced collagen degradation capacity.

CONCLUSIONS

Our study confirmed the central role of HGF in the pathogenesis of severe periodontitis in relevant in vitro and in vivo models. The positive effect of anti-HGF treatment provides a strong rationale for the use of anti-HGF-neutralizing antibodies for the treatment of human periodontitis.

Comparing periodontitis biomarkers in saliva, oral rinse and gingival crevicular fluid: A pilot study

AIM

To explore the feasibility of screening for periodontitis by measuring biomarkers, namely total proteolytic activity (TPA), matrix metalloproteinase (MMP)-8, chitinase, lysozyme or their combination, in saliva, oral rinse and gingival crevicular fluid (GCF).

MATERIAL AND METHODS

Subjects were recruited among healthy/gingivitis individuals and untreated periodontitis patients in Academic Centre for Dentistry Amsterdam (ACTA). All participants donated samples of unstimulated whole saliva, oral rinse and GCF. The protein concentrations and MMP-8 levels were determined by ELISA. Enzymatic activities were measured using appropriate fluorogenic substrates.

RESULTS

In oral rinse samples, periodontitis patients (n = 19) exhibited significantly higher concentrations of MMP-8 and TPA than controls (n = 20). MMP-8 in combination with chitinase explained 88% of the variance and assigned a subject to control or periodontitis group, with best accuracy (87.2%) in oral rinse.

CONCLUSIONS

The combination of MMP-8 and chitinase in the current oral rinse procedure has the potential to discriminate periodontitis from periodontal health/gingivitis.

The Advent of COVID-19; Periodontal Research Has Identified Therapeutic Targets for Severe Respiratory Disease; an Example of Parallel Biomedical Research Agendas

The pathophysiology of SARS-CoV-2 infection is characterized by rapid virus replication and aggressive inflammatory responses that can lead to acute respiratory distress syndrome (ARDS) only a few days after the onset of symptoms. It is suspected that a dysfunctional immune response is the main cause of SARS-CoV-2 infection-induced lung destruction and mortality due to massive infiltration of hyperfunctional neutrophils in these organs. Similarly, neutrophils are recruited constantly to the oral cavity to combat microorganisms in the dental biofilm and hyperfunctional neutrophil phenotypes cause destruction of periodontal tissues when periodontitis develops. Both disease models arise because of elevated host defenses against invading organisms, while concurrently causing host damage/disease when the immune cells become hyperfunctional. This represents a clear nexus between periodontal and medical research. As researchers begin to understand the link between oral and systemic diseases and their potential synergistic impact on general health, we argue that translational research from studies in periodontology must be recognized as an important source of information that might lead to different therapeutic options which can be effective for the management of both oral and non-oral diseases. In this article we connect concepts from periodontal research on oral inflammation while exploring host modulation therapy used for periodontitis as a potential strategy for the prevention of ARDS a deadly outcome of COVID-19. We suggest that host modulation therapy, although developed initially for management of periodontitis, and which inhibits proteases, cytokines, and the oxidative stress that underlie ARDS, will provide an effective and safe treatment for COVID-19.

Selective toxicity of antibacterial agents-still a valid concept or do we miss chances and ignore risks?

BACKGROUND

Selective toxicity antibacteribiotics is considered to be due to interactions with targets either being unique to bacteria or being characterized by a dichotomy between pro- and eukaryotic pathways with high affinities of agents to bacterial- rather than eukaryotic targets. However, the theory of selective toxicity oversimplifies the complex modes of action of antibiotics in pro- and eukaryotes.

METHODS AND OBJECTIVE

This review summarizes data describing multiple modes of action of antibiotics in eukaryotes.

RESULTS

Aminoglycosides, macrolides, oxazolidinones, chloramphenicol, clindamycin, tetracyclines, glycylcyclines, fluoroquinolones, rifampicin, bedaquillin, ß-lactams inhibited mitochondrial translation either due to binding to mitosomes, inhibition of mitochondrial RNA-polymerase-, topoisomerase 2ß-, ATP-synthesis, transporter activities. Oxazolidinones, tetracyclines, vancomycin, ß-lactams, bacitracin, isoniazid, nitroxoline inhibited matrix-metalloproteinases (MMP) due to chelation with zinc and calcium, whereas fluoroquinols fluoroquinolones and chloramphenicol chelated with these cations, too, but increased MMP activities. MMP-inhibition supported clinical efficacies of ß-lactams and daptomycin in skin-infections, and of macrolides, tetracyclines in respiratory-diseases. Chelation may have contributed to neuroprotection by ß-lactams and fluoroquinolones. Aminoglycosides, macrolides, chloramphenicol, oxazolidins oxazolidinones, tetracyclines caused read-through of premature stop codons. Several additional targets for antibiotics in human cells have been identified like interaction of fluoroquinolones with DNA damage repair in eukaryotes, or inhibition of mucin overproduction by oxazolidinones.

CONCLUSION

The effects of antibiotics on eukaryotes are due to identical mechanisms as their antibacterial activities because of structural and functional homologies of pro- and eukaryotic targets, so that the effects of antibiotics on mammals are integral parts of their overall mechanisms of action.

Chemically-Modified Curcumin 2.24: A Novel Systemic Therapy for Natural Periodontitis in Dogs

Purpose

To determine the effect of a pleiotropic MMP-inhibitor, a novel chemically-modified curcumin 2.24 (CMC2.24), on the clinical and biological measures of naturally-occurring periodontitis in the beagle dog.

Methods

Eight adult female dogs with generalized periodontitis were distributed into two groups: Placebo and Treatment (n=4/group). After a 1-hr full-mouth scaling and root planing (SRP) at time 0, placebo or CMC2.24 (10mg/kg) capsules were orally administered once/day for 3 months. Various clinical periodontal parameters (e.g., pocket depth, gingival index) were measured at different time periods (0, 1, 2 and 3 months), and gingival crevicular fluid (GCF) samples and gingival tissue biopsies (3-month) were analyzed for cytokines, MMPs and cell-signaling molecules. Standardized radiographs were taken at 0 and 3-month; in addition, peripheral blood monocytes/macrophages from these dogs at 3-month were cultured and analyzed for the pro-, activated-, and total-forms of both MMP-2 and MMP-9.

Results

CMC2.24 treatment significantly reduced gingival inflammation (gingival index, GCF flow), pocket depth (PD), and the numbers of pockets (PD≥4mm), compared to placebo. CMC2.24 also significantly reduced MMP-9 and MMP-2 (primarily in the activated-form) in gingival tissue, alveolar bone loss, and reduced GCF IL-1β. Cell-signaling molecules, TLR-2 (but not TLR-4) and p38 MAPK, responded to CMC2.24 in a pattern consistent with reductions in inflammation and collagenolysis. In culture, CMC2.24 had no effect on pro-MMP-9 but essentially completely blocked the conversion of pro- to activated-MMP-9 in systemic blood-derived monocytes/macrophages from these dogs.

Conclusion

In the beagle dog model of natural periodontitis, orally administered CMC2.24 (a novel triketonic phenylaminocarbonyl-curcumin) significantly decreased clinical measures of periodontitis as well as pro-inflammatory cytokines, MMPs, and cell-signaling molecules. These and previous studies, using other in vitro and in vivo models, support the clinical potential of CMC2.24 as a novel adjunct to SRP in the treatment of chronic periodontitis.

Periodontal therapeutics: Current host-modulation agents and future directions

With the recognition in the 1960s and 1970s of the periodontopathic importance of the microbial biofilm and its specific anaerobic microorganisms, periodontitis was treated as an infectious disease (more recently, as a dysbiosis). Subsequently, in the 1980s, host-response mechanisms were identified as the mediators of the destruction of the collagen-rich periodontal tissues (gingiva, periodontal ligament, alveolar bone), and the periodontopathogens were now regarded as the "trigger" of the inflammatory/collagenolytic response that characterizes actively destructive periodontitis. Also at this time a new pharmacologic strategy emerged, entitled "host-modulation therapy", based on 2 major findings: (1) that the ability of tetracycline antibiotics to inhibit periodontal breakdown was due (in large part) to their previously unrecognized ability to inhibit the host-derived matrix metalloproteinases (notably, the collagenases, gelatinases, macrophage metalloelastase), and by mechanisms unrelated to the antimicrobial properties of these medications; and (2) that nonsteroidal anti-inflammatory drugs, such as flurbiprofen, again by nonantimicrobial mechanisms, could reduce the severity of periodontitis (however, the adverse effects of long-term therapy precluded their development as safe and effective host-modulatory agents). Additional mechanistic studies resulted in the development of novel nonantimicrobial formulations (Periostat® [now generic] and Oracea®) and compositions of tetracyclines (notably chemically modified tetracycline-3) as host-modulator drugs for periodontitis, arthritis, cardiovascular and pulmonary diseases, cancer, and, more recently, for local and systemic bone loss in postmenopausal women. Identification of the cation-binding active site in the tetraphenolic chemically modified tetracycline molecules drove the development of a new category of matrix metalloproteinase-inhibitor compounds, with a similar active site, the biphenolic chemically modified curcumins. A lead compound, chemically modified curcumin 2.24, has demonstrated safety and efficacy in vitro, in cell culture, and in vivo in mouse, rat, rabbit, and dog models of disease. In conclusion, novel host-modulation compounds have shown significant promise as adjuncts to traditional local therapy in the clinical management of periodontal disease; appear to reduce systemic complications of this all-too-common "inflammatory/collagenolytic" disease; and Oracea® is now commonly prescribed for inflammatory dermatologic diseases.

Adjunctive subantimicrobial dose doxycycline in the treatment of chronic periodontitis in type 2 diabetic patients: A unique combination therapy

Background/Aim: To evaluate the effectiveness of combination therapy including subantimicrobial dose doxycycline (SDD) and locally delivered doxycycline (LD) as adjuncts to scaling and root planing (SRP) in the treatment of chronic periodontitis in patients with type 2 diabetes mellitus (T2DM). Material and Methods: Forty patients with controlled T2DM (HbA1c ≤7%) and chronic periodontitis were selected. They were randomly divided into two groups, twenty patients each: Test group (TG, n=20) patients was treated with combination therapy of full mouth SRP, LD gel 10% and SDD 20 mg twice daily for 6 months. Control group (CG, n=20) patients was treated with full mouth SRP only. The periodontal parameters were recorded at baseline, 3, 6 and 9 months and included periodontal probing depth (PD), clinical attachment level (CAL), and bleeding on probing (BOP). Gingival crevicular fluid (GCF) samples were collected and a quantitative measurement of matrix metalloproteinase-8 (MMP-8) was carried out by using Enzyme-Linked Immunosorbent Assay (ELIZA) at baseline, 3, 6 and 9 months. Results: Statistically significant reduction in all clinical parameters (PPD, CAL, and BOP) was observed at TG over CG at 3, 6, and 9 months (p<0.05). Moreover, combination therapy provided significant reductions in the amount of GCF MMP-8 for the TG compared to CG at 3, 6, and 9 months evaluation period (p<0.05). Conclusions: Combination therapy including SRP, SDD, and LD, provided significantly greater clinical benefits than SRP alone in the treatment of chronic periodontitis in patients with controlled T2DM.

Combined effect of photobiomodulation with a matrix metalloproteinase inhibitor on the rate of relapse in rats

OBJECTIVE

To investigate combined effect of photobiomodulation with a matrix metalloproteinase (MMP) inhibitor on the relapse rate in relation to MMP expression in rats.

MATERIALS AND METHODS

Fifty-two rats were divided into four groups according to the treatment modality: control group, irradiation group, doxycycline group, and irradiation with doxycycline group. During a relapse period of 5 days after orthodontic movement, maxillary central incisors were treated by low-level laser therapy (LLLT) as a photobiomodulation and/or doxycycline as a synthetic MMP inhibitor. Relapse rate was evaluated in association with MMP expression at the gene and protein levels.

RESULTS

Relapse rates were increased by LLLT (1.57-fold) and decreased by doxycycline (0.83-fold) compared with the control, showing positive correlation with the levels of expression for all MMPs in the periodontal ligament (PDL). LLLT concomitant with doxycycline administration resulted in no significant differences of relapse rate and MMP expression from the control.

CONCLUSIONS

The combined effect of photobiomodulation with an MMP inhibitor around the relapsing teeth proved to be antagonistic to PDL remodeling activity during relapse. This study suggests a basis for developing a novel biologic procedure targeting the MMP-dependent PDL remodeling to control the relapse rate.

Triclosan blocks MMP-13 expression in hormone-stimulated osteoblasts

BACKGROUND

Matrix metalloproteinase-13 (MMP-13) is an important enzyme for the modulation of bone turnover and gingival recession. Elevated levels of MMP-13 are associated with alveolar bone resorption, periodontal ligament breakdown, and gingival attachment loss, which are the clinical symptoms of periodontal disease. Evidence continues to suggest that periodontal disease contributes to oral tissue breakdown and is linked to numerous systemic conditions. Triclosan (TCN) is a long-standing, proven antibacterial and anti-inflammatory agent found in the only Food and Drug Administration-approved dentifrice for the treatment of plaque and gingivitis.

METHODS

This study examines the inhibitory effects of TCN on lipopolysaccharide-, parathyroid hormone (PTH)-, and prostaglandin E2 (PGE2)-induced expression of MMP-13 in UMR 106-01 cells, an osteoblastic osteosarcoma cell line. The cells were stimulated with PTH or PGE2 to induce MMP-13 mRNA expression, and real-time reverse transcription-polymerase chain reaction was performed to determine gene expression levels. Western blot analysis assessed the presence or absence of protein degradation or inhibition of protein synthesis. MMP-13 promoter reporter assay was used to explore possible direct effects of TCN on the MMP-13 promoter.

RESULTS

TCN significantly reduced PTH or PGE2 elevated expression of MMP-13 in osteoblastic cells without affecting basal levels of the mRNA. Surprisingly, TCN enhanced the expression of c-fos and amphiregulin mRNA. A promoter assay indicated that TCN directly inhibits the activation of the PTH-responsive minimal promoter of MMP-13.

CONCLUSION

The present study appears to have identified a nuclear mechanism of action of TCN that accounts for the ability of TCN to inhibit PTH- or PGE2-induced MMP-13 expression in osteoblastic cells.

Multilevel analysis of clinical parameters in chronic periodontitis after root planing/scaling, surgery, and systemic and local antibiotics: 2-year results

AIM

Find the periodontal treatment that best maintained clinical results over time evaluated by changes in pocket depth (PD) and clinical attachment level (CAL).

METHODS

229 patients with chronic periodontitis from USA (n=134) and Sweden (n=95) were randomly assigned to eight groups receiving (1) scaling+root planing (SRP) alone or combined with (2) surgery (SURG)+systemic amoxicillin (AMOX)+systemic metronidazole (MET); (3) SURG+local tetracycline (TET); (4) SURG; (5) AMOX+MET+TET; (6) AMOX+MET; (7) TET; and (8) SURG+AMOX+MET+TET. Antibiotics were given immediately after SRP. Plaque, gingival redness, bleeding on probing, suppuration, PD, and CAL were recorded at baseline and after 3, 6, 12, 18, and 24 months. Treatment effects were evaluated by linear multilevel regression and logistic multilevel regression models. We considered only data from sites with a baseline PD of at least 5 mm of 187 patients completing the study.

RESULTS

Surgically treated patients experienced most CAL loss. Adjunctive therapy including SURG was most effective in reducing PD. Combining SURG with AMOX, MET, and TET gave significant clinical benefits. Past and current smoking habits were significant predictors of deeper PD. Only current smoking was a significant predictor of CAL loss. Bleeding, accumulation of plaque, gingival redness, and suppuration were significant predictors of further CAL loss and deeper PD.

CONCLUSIONS

Both surgical and non-surgical therapies can be used to arrest chronic periodontitis. SURG+AMOX+MET+TET gave best maintenance of clinical results.

Non-antibacterial tetracyclines modulate mediators of periodontitis and atherosclerotic cardiovascular disease: a mechanistic link between local and systemic inflammation

Periodontitis, one of the most common chronic inflammatory diseases afflicting man, is increasingly being recognized as a risk factor for atherosclerotic cardiovascular disease (ASCVD). Non-antimicrobial tetracyclines are known to have inhibitory effects on inflammatory mediators and effector molecules, including cytokines and matrix metalloproteinases (MMPs), associated with both diseases. In this paper, we discuss the evidence that doxycycline and related non-antibiotic chemically modified tetracyclines (e.g., CMT-3) can effectively reduce cytokine (TNF-α, IL-6, and MCP-1) production by human mononuclear inflammatory cells when stimulated either by endotoxin (LPS) or by a complex of C-reactive protein/oxidized LDL cholesterol relevant to the pathogenesis of periodontal disease and ASCVD, respectively. This inhibition by tetracycline compounds appears to be mediated at least in part by a suppression of the phosphorylation/activation of the NFκB cell signaling pathway. We are currently conducting clinical trials on patients who exhibit both diseases, and our preliminary data suggest that virtually all acute coronary syndrome (ACS) patients exhibit moderate-to-severe periodontitis, a higher incidence of this oral inflammatory disease than that seen in the population at large. In other studies, a non-antimicrobial formulation of doxycycline (SDD) has been found to dramatically reduce hsCRP, IL-6 and MMP-9 levels in plasma of ACS patients, and SDD has also been found to significantly increase serum levels of both cardio-protective HDL cholesterol and its core molecule apolipoprotein A-I in ASCVD-vulnerable patients with periodontitis. Our current research suggests that one mechanism involved may be the ability of SDD to inhibit MMP-mediated HDL loss by protecting apolipoprotein A-I from proteinase attack. These pleiotropic mechanisms of non-antimicrobial tetracyclines provide significant therapeutic potential to treat chronic inflammatory diseases including both periodontitis and ASCVD.

Clinical and biochemical efficacy of minocycline in nonsurgical periodontal therapy: a randomized controlled pilot study

The present study evaluated the effects of systemic minocycline on clinical and biochemical parameters of chronic periodontitis, which is a common inflammatory disorder of the periodontium initiated by the presence of bacteria in the gingival sulcus. Besides nonsurgical periodontal therapy, 20 individuals received minocycline systemically while another 20 subjects received placebo capsules for 2 weeks. Plaque index (PI), sulcus bleeding index (SBI), probing depth (PD), and relative attachment level (RAL) were measured and gingival crevicular fluid (GCF) samples were obtained at baseline and first, third, and sixth months. Matrix metalloproteinase-8 (MMP-8) and prostaglandin E₂ (PGE₂) levels were analyzed by enzyme immunoassay method. Significant improvements in all parameters in both groups were recorded. In the minocycline group, changes in PI and SBI were significantly greater only at first month, whereas reductions in PD, RAL, MMP-8, and PGE₂ levels were greater at all times. MMP-8 and PGE₂ exhibited positive correlations with SBI, PD, and each other. Minocycline demonstrated clinical benefit for periodontal therapy and provided further improvements on inflammatory mediators promising a host-modulating capacity.

Doxycycline causes regression of endometriotic implants: a rat model

BACKGROUND

Doxycycline (Dox) has a number of non-antibiotic properties. One of them is the inhibition of matrix metalloproteinase (MMP) activity. The aim of this study was to assess the effects of Dox in a rat endometriosis model.

METHODS

Endometriosis was surgically induced in 40 rats by transplanting of endometrial tissue. After 3 weeks, repeat laparotomies were performed to check the implants and the animals were randomized into four groups: Group I, low-dose Dox (5 mg/kg/day); Group II, high-dose Dox (40 mg/kg/day); Group III, leuprolide acetate 1 mg/kg single dose, s.c.; and Group VI (controls), no medication. The treatment, initiated on the day of surgery and continuing for 3 weeks, was administered to the study groups. Three weeks later, the rats were euthanized and the implants were evaluated morphologically and histologically for immunoreactivity of MMP-2 and -9, and interleukin-6 (IL-6) concentration in the peritoneal fluid was assayed.

RESULTS

Treatment with leuprolide acetate, or high-dose or low-dose Dox caused significant decreases in the implant areas compared with the controls (P = 0.03, P = 0.006, and P = 0.001, respectively). IL-6 levels in peritoneal fluid decreased in Group I (P = 0.02) and Group III (P < 0.05). MMP H scores were significantly lower in the group that received low-dose Dox in both epithelial and stromal MMP-2 and -9 immunostaining when compared with the control group [P = 0.048, P = 0.002, P = 0.007 and P = 0.002, respectively, MMP-2 (epithelia), MMP-2 (stroma), MMP-9 (epithelia) and MMP-9 (stroma)].

CONCLUSIONS

Low-dose Dox caused regression of endometriosis in this experimental rat model.

The effect of adjunctive subantimicrobial dose doxycycline therapy on GCF EMMPRIN levels in chronic periodontitis

BACKGROUND

The aim of the present randomized, double-masked, placebo-controlled, parallel-arm study was to examine the effectiveness of a 3-month regimen of subantimicrobial dose doxycycline (SDD) in combination with scaling and root planing compared to scaling and root planing alone on levels of gingival crevicular fluid (GCF) extracellular matrix metalloproteinase inducer (EMMPRIN) in patients with chronic periodontitis.

METHODS

GCF samples were collected, and clinical parameters, including probing depth (PD), clinical attachment level, gingival index (GI), and plaque index, were recorded. Thirty chronic periodontitis subjects were randomized to receive SDD or placebo. The SDD group received SDD (20 mg, twice a day) for 3 months plus scaling and root planing, whereas the placebo group took placebo capsules twice a day for 3 months and received scaling and root planing. The subjects were reevaluated at 3 and 6 months. At each visit, all clinical parameters were measured and GCF was sampled. GCF EMMPRIN levels were determined by Western immunoblotting assay. Intragroup comparisons were tested by the Friedman test followed by the Wilcoxon signed-rank test to analyze the significance of changes over time. The Mann-Whitney test was used to determine differences between the SDD and placebo groups.

RESULTS

Significant improvements were observed in all clinical parameters in the SDD group over the 6-month study period (P <0.025). The SDD group showed a significantly greater reduction in mean PD scores at 6 months and in mean GI scores at 3 and 6 months than the placebo group (P <0.05). From baseline to 6 months, the GCF EMMPRIN levels were reduced significantly in the SDD group (P <0.025). The GCF EMMPRIN level in the SDD group was significantly lower than that of the placebo group at 3 and 6 months (P <0.05).

CONCLUSIONS

SDD therapy in combination with scaling and root planing reduced GCF EMMPRIN levels and improved clinical periodontal parameters in subjects with chronic periodontitis. The ability of SDD to downregulate, in vivo, the GCF levels of EMMPRIN, a unique upregulator of matrix metalloproteinase expression, is one of its beneficial host-modulatory properties. These results expand the usefulness of SDD therapy as an adjunct to scaling and root planing in the long-term management of periodontal disease.

Oral fluid-based biomarkers of alveolar bone loss in periodontitis

Periodontal disease is a bacteria-induced chronic inflammatory disease affecting the soft and hard supporting structures encompassing the teeth. When left untreated, the ultimate outcome is alveolar bone loss and exfoliation of the involved teeth. Traditional periodontal diagnostic methods include assessment of clinical parameters and radiographs. Though efficient, these conventional techniques are inherently limited in that only a historical perspective, not current appraisal, of disease status can be determined. Advances in the use of oral fluids as possible biological samples for objective measures of current disease state, treatment monitoring, and prognostic indicators have boosted saliva and other oral-based fluids to the forefront of technology. Oral fluids contain locally and systemically derived mediators of periodontal disease, including microbial, host-response, and bone-specific resorptive markers. Although most biomarkers in oral fluids represent inflammatory mediators, several specific collagen degradation and bone turnover-related molecules have emerged as possible measures of periodontal disease activity. Pyridinoline cross-linked carboxyterminal telopeptide (ICTP), for example, has been highly correlated with clinical features of the disease and decreases in response to intervention therapies, and has been shown to possess predictive properties for possible future disease activity. One foreseeable benefit of an oral fluid-based periodontal diagnostic would be identification of highly susceptible individuals prior to overt disease. Timely detection and diagnosis of disease may significantly affect the clinical management of periodontal patients by offering earlier, less invasive, and more cost-effective treatment therapies.

Clinical changes following four different periodontal therapies for the treatment of chronic periodontitis: 1-year results

OBJECTIVE

To compare clinical changes occurring in chronic periodontitis subjects receiving SRP alone or with systemically administered azithromycin, metronidazole or a sub-antimicrobial dose of doxycycline.

MATERIAL AND METHODS

92 chronic periodontitis subjects were randomly assigned to receive SRP alone (N=23) or combined with 500 mg azithromycin per day for 3 days (N=25), 250 mg metronidazole tid for 14 days (N=24) or 20 mg doxycycline bid for 3 months (N=20). Gingival redness, bleeding on probing, suppuration, pocket depth and attachment level were measured at baseline and 3, 6 and 12 months post therapy. The significance of changes in clinical parameters within groups over time was sought using the Friedman test and among groups using ANCOVA or the Kruskal Wallis test.

RESULTS

All groups showed clinical improvements at 12 months, with subjects receiving adjunctive agents showing a somewhat better response. Sites with initial pocket depth > 6 mm showed significantly greater pocket depth reduction and greater attachment gain in subjects receiving metronidazole or azithromycin than subjects in the other groups. Some subjects showed attachment loss at 12 months in each group ranging from 15% to 39% of subjects in the SDD and SRP only groups respectively.

CONCLUSION

This study, demonstrated that periodontal therapy provides clinical benefits and that antibiotics provide a clinical benefit over SRP alone, particularly at initially deeper periodontal pockets.

Locally Delivered Doxycycline as an Adjunctive Therapy to Scaling and Root Planing in the Treatment of Smokers: A 2-Year Follow-Up

BACKGROUND

The aim of this clinical study was to evaluate the association of locally delivered doxycycline 10% with scaling and root planing in the periodontal treatment of smokers during a 2-year period.

METHODS

Forty-eight chronic periodontitis patients, presenting a minimum of four pockets (>or=5 mm) that bled on probing on anterior teeth were included. Patients were randomly assigned to receive one of the following treatments: scaling and root planing (SRP) and scaling and root planing followed by local application of doxycycline (SRP-D). Assigned treatments were performed at baseline and at 12 months. Clinical parameters, including probing depth (PD) and relative attachment level (RAL), were recorded at baseline; 45 days; 3, 6, and 12 months (retreatment); 45 days following retreatment; and at 15, 18, and 24 months.

RESULTS

In initially deep pockets (>or=7 mm), SRP-D showed greater PD reduction than SRP at 6 and 18 months (mean difference between groups of 1.18 and 1.73 mm, respectively; P <0.05) and greater RAL gain in all periods after 3 months (mean difference between groups of 1.16, 1.99, and 1.78 mm, at 6, 18, and 24 months, respectively; P <0.05). Also, the proportion of sites showing >or=2 mm PD reduction was greater for SRP-D at 6 months (81.2% x 50.8%; P <0.001) and at 24 months (65.5% x 46.5%; P = 0.01). As for RAL gain, this proportion was 34.4% and 18.1% for SRP-D and SRP at 24 months, respectively (P = 0.008).

CONCLUSION

The use of locally delivered doxycycline may constitute an important adjunct for the active and supportive treatments of severe periodontal disease in smokers.

Matrix metalloproteinases: contribution to pathogenesis, diagnosis and treatment of periodontal inflammation

Matrix metalloproteinases (MMPs) form a family of enzymes that mediate multiple functions both in the tissue destruction and immune responses related to periodontal inflammation. The expression and activity of MMPs in non-inflamed periodontium is low but is drastically enhanced to pathologically elevated levels due to the dental plaque and infection-induced periodontal inflammation. Soft and hard tissue destruction during periodontitis and peri-implantitis are thought to reflect a cascade of events involving bacterial virulence factors/enzymes, pro-inflammatory cytokines, reactive oxygen species and MMPs. However, recent studies suggest that MMPs can also exert anti-inflammatory effects in defence of the host by processing anti-inflammatory cytokines and chemokines, as well as by regulating apoptotic and immune responses. MMP-inhibitor (MMPI)-drugs, such as doxycycline, can be used as adjunctive medication to augment both the scaling and root planing-treatment of periodontitis locally and to reduce inflammation systematically. Furthermore, MMPs present in oral fluids (gingival crevicular fluid (GCF), peri-implant sulcular fluid (PISF), mouth-rinses and saliva) can be utilized to develop new non-invasive, chair/bed-side, point-of-care diagnostics for periodontitis and dental peri-implantitis.

Host response modulation in the management of periodontal diseases

OBJECTIVE

To review the biological mechanisms and clinical utility of therapeutic modulation of the host response in the management of periodontal diseases.

MATERIAL AND METHODS

A search of MEDLINE-PubMed was performed up to and including December 2004. The search was limited to in vitro, experimental animal and clinical studies published in English. The selection criteria included all levels of available evidence: systematic reviews, randomised-controlled clinical trials, controlled clinical trials, prospective and retrospective cohort studies and case reports of human and experimental animal studies.

RESULTS

Six targets for non-microbial chemotherapeutic intervention were identified. Clinical trials have demonstrated the ability of non-steroidal anti-inflammatory drugs to slow periodontal disease progression. However, recently reported serious adverse effects preclude the use of cyclooxygenase-2 inhibitors as an adjunct to periodontal therapy. Adjunctive use of subantimicrobial dose doxycycline to non-surgical periodontal therapy is beneficial in the management of chronic periodontitis over 12 months. Controversial data exist on the effects of bisphosphonate administration as an adjunct to periodontal therapy. Evidence on modulation of other host mediators including lipoxins, cytokines and nitric oxide synthase is limited to animal research.

CONCLUSION

After validation in long-term clinical trials, adjunctive host modulation therapy may prove advantageous in the management of periodontal diseases.

Adjunctive subantimicrobial dose doxycycline: effect on clinical parameters and gingival crevicular fluid transforming growth factor-beta levels in severe, generalized chronic periodontitis

BACKGROUND

At present there is limited data concerning the efficacy of non-surgical periodontal therapy supplemented with subantimicrobial dose doxycycline (SDD) in the treatment of severe, generalized periodontitis. The purpose of the present study was to evaluate the effect of adjunctive SDD therapy on clinical periodontal parameters and gingival crevicular fluid (GCF) transforming growth factor-beta1 (TGF-beta1) levels in patients with severe, generalized chronic periodontitis over a 6-month period.

METHODS

Thirty-five patients with severe, generalized periodontitis and 11 periodontally healthy subjects were included in the present study. Patients received full-mouth supragingival debridment at baseline and randomized to take either SDD b.i.d. or placebo b.i.d. for 3 months. Patients received root planing and oral hygiene instruction once a week for four consecutive weeks. Clinical measurements including probing depth (PD), clinical attachment level, papilla bleeding index and plaque index and GCF sampling were performed at baseline, 3 and 6 months. The GCF TGF-beta1 levels were analysed by enzyme-linked immunosorbent assay.

RESULTS

Thirteen patients in both study groups completed the 6-month trial. Following scaling and root planing (SRP) plus SDD and SRP plus placebo therapy significant improvements in clinical periodontal parameters of both groups were observed (p<0.025). In the SDD group a significantly higher percentage (%73.4) of deep pockets resolved (PD reduction > or =3 mm from baseline) when compared with placebo group (%49.7) at 6 months (p<0.05). At baseline there were no significant differences in GCF TGF-beta1 levels between three groups. Both total amount and concentration of GCF TGF-beta1 in SDD and placebo groups increased when compared with baseline at 3 months. However, only GCF TGF-beta1 levels of SDD group was significantly higher than baseline (p<0.025) and placebo group (p<0.017) at 3 months. At 6 months GCF TGF-beta1 levels of both groups were similar to baseline levels (p<0.025).

CONCLUSIONS

These data indicate that combination of SDD with non-surgical therapy improves clinical parameters of periodontal disease and increases GCF TGF-beta1 levels together with a decrease in prevalence of residual pockets in patients with severe, generalized chronic periodontitis. Increased GCF TGF-beta1 levels following SDD therapy might suggest a novell pleiotrophic mechanism for tetracyclines to inhibit connective tissue breakdown.

Subantimicrobial dose doxycycline as adjunctive treatment for periodontitis. A review

BACKGROUND

Subantimicrobial dose doxycycline (SDD--20 mg doxycycline twice daily) is indicated as an adjunctive treatment for periodontitis. Doxycycline downregulates the activity of matrix metalloproteinases (MMPs), key destructive enzymes in periodontal disease. Current understanding of periodontal pathogenesis suggests that MMPs play a major role in the destruction of periodontal tissues, leading to the clinical signs of periodontitis. Research supports that downregulation of MMPs by SDD confers benefit to patients with periodontitis.

METHOD

We review the clinical, microbiological and safety data relating to the use of SDD in patients with periodontitis, and consider the historical events that led to the development of adjunctive SDD as a treatment for periodontitis.

RESULTS

Studies have shown that SDD, when prescribed as an adjunct to scaling and root planing (SRP), results in statistically and clinically significant gains in clinical attachment levels and reductions in probing depths over and above those that are achieved by SRP alone. SRP must be thorough and performed to the highest standard to maximise the benefits of adjunctive SDD. SDD does not result in antibacterial effects, or lead to the development of resistant strains or the acquisition of multiantibiotic resistance. The frequency of adverse events is low, and does not differ significantly from placebo.

CONCLUSIONS

Adjunctive SDD confers clinical benefit to patients with periodontitis. A comprehensive treatment strategy is suggested, involving patient education and motivation, reduction of the bacterial burden by SRP, host response modulation with SDD, and periodontal risk factor modification.

Effectiveness of Adjunctive Low-Dose Doxycycline Therapy on Clinical Parameters and Gingival Crevicular Fluid Laminin-5 γ2 Chain Levels in Chronic Periodontitis

BACKGROUND

Laminin-5 (Ln-5) is involved in the apical migration of epithelial cells during the development of periodontal pockets. Low-dose doxycycline (LDD) can therapeutically modulate the host response with its non-antimicrobial properties. In the present randomized, double-blind, placebo-controlled, parallel arm study, the effectiveness of LDD in combination with non-surgical periodontal therapy on gingival crevicular fluid (GCF) Ln-5 gamma2 chain fragment levels and clinical parameters in patients with chronic periodontitis was examined over a 12-month period.

METHODS

GCF samples were collected and clinical parameters including probing depth (PD), clinical attachment level, gingival index (GI), and plaque index were recorded. Thirty chronic periodontitis patients were randomized either to low-dose doxcycline or placebo groups. LDD group received doxycycline (20 mg, b.i.d.) for 3 months plus scaling and root planing (SRP), while placebo group was given placebo capsules b.i.d. for 3 months plus SRP. The patients were evaluated every 3 months during the 12-month study period. All clinical parameters and GCF sampling were repeated at each visit. GCF Ln-5 gamma2 chain fragment levels were determined by Western immunoblotting using specific antibody and quantitated by computerized image analysis. Friedman test was used for intragroup comparisons followed by Wilcoxon signed rank test to analyze significance of changes over time. The Mann-Whitney test was used to determine differences between both LDD and placebo groups.

RESULTS

Both groups revealed significant improvements in all clinical parameters over the 12-month period (P < 0.0125). LDD group showed a significantly greater reduction in the mean PD scores at 9 and 12 months and in the mean GI scores at all time points than the placebo group (P < 0.05). In the LDD group, GCF Ln-5 gamma2 chain fragment levels were significantly reduced at 3 months (P < 0.0125) and then slightly increased during the rest of the study period. In the placebo group, GCF 45 and 70 kDa Ln-5 gamma2 chain fragments tended to decrease at 3 months compared to baseline, but did not reach significance; these levels continued to increase throughout the remainder of the study period. GCF Ln-5 gamma2 chain fragment levels in LDD group were significantly lower than those of the placebo group during the study period (P < 0.05).

CONCLUSIONS

The present data indicate that LDD therapy in combination with SRP therapy can reduce GCF Ln-5 gamma2 chain fragment levels and improve clinical periodontal parameters in patients with chronic periodontitis. Since matrix metalloproteinases (MMP)-mediated fragmentation of laminin-5 can contribute to pocket formation by stimulating epithelial cell migration, the reduction of Ln-5 gamma2 chain fragment levels could provide a new mechanism by which LDD, adjunctive to SRP, inhibits periodontal disease more effectively than SRP alone. Thus, these results provide extended and additional information about the effectiveness of the LDD therapy as an adjunct to non-surgical periodontal therapy in the long-term management of periodontal disease.

The effect of adjunctive low-dose doxycycline therapy on clinical parameters and gingival crevicular fluid matrix metalloproteinase-8 levels in chronic periodontitis

BACKGROUND

Low-dose doxycycline (LDD) is recognized to have non-antimicrobial properties that can therapeutically modulate the host response. The aim of the present randomized, double-blind, placebo-controlled, parallel-arm study was to examine the effectiveness of LDD in combination with non-surgical periodontal therapy, compared to non-surgical periodontal therapy alone, on gingival crevicular fluid (GCF) matrix metalloproteinase-8 (MMP-8) levels and clinical parameters over a 12-month period in patients with chronic periodontitis.

METHODS

GCF samples were collected, and clinical parameters including probing depth (PD), clinical attachment level, gingival index (GI), and plaque index were recorded. Thirty chronic periodontitis patients were randomized either to a low-dose doxycycline (LDD) or placebo group. The LDD group received low-dose doxycycline (20 mg) b.i.d. for 3 months plus scaling and root planing (SRP), while the placebo group was given placebo capsules b.i.d. for 3 months plus SRP. The patients were evaluated every 3 months during the 12-month study period. At each visit, all clinical measurements and GCF sampling were repeated. GCF MMP-8 levels were determined by a time-resolved immunofluorescence assay. Intragroup comparisons were tested by the Friedman test followed by Wilcoxon signed-rank test to analyze significance of changes over time. The Mann-Whitney test was used to determine differences between the LDD and placebo groups.

RESULTS

Significant improvements were observed in all clinical parameters in both groups over the 12-month period (P < 0.0125). The LDD group showed a significantly greater reduction in mean PD scores at 9 and 12 months and in mean GI scores at all time points than the placebo group (P < 0.05). From baseline to 12 months, GCF MMP-8 levels were significantly reduced in both groups (P < 0.0125). The GCF MMP-8 level in the LDD group was significantly lower than that of the placebo group at 6 months (P < 0.05).

CONCLUSIONS

The present results indicate that low-dose doxycycline therapy in combination with scaling and root planing can reduce GCF MMP-8 levels and improve clinical periodontal parameters in patients with chronic periodontitis. These results provide additional information about the usefulness of low-dose doxycycline therapy as an adjunct to non-surgical periodontal therapy in the long-term management of periodontal disease. The effectiveness and course of low-dose doxycycline therapy can be monitored conveniently by assessing GCF MMP-8 levels.

Locally Delivered Doxycycline as an Adjunctive Therapy to Scaling and Root Planing in the Treatment of Smokers: A Clinical Study

BACKGROUND

The aim of this clinical study was to evaluate the association of locally delivered doxycycline (10%) with scaling and root planing in the periodontal treatment of smokers.

METHODS

Forty-three patients with chronic periodontitis and a minimum of four pockets (> or = 5 mm) on anterior teeth that bled on probing were selected. Patients were randomly assigned to scaling and root planing (SRP) or scaling and root planing followed by local application of doxycycline (SRP-D). Plaque, bleeding on probing, gingival recession, relative attachment level (RAL), and probing depth (PD) were recorded at baseline, 45 days, and 3 and 6 months. Differences between baseline and each period were considered for analysis.

RESULTS

At 6 months, no difference was found between groups regarding plaque, bleeding reduction, gingival recession or PD (P > 0.05). However, RAL gain was greater for SRP-D (1.63 +/- 0.93 mm) than for SRP (1.04 +/- 0.71 mm) (P = 0.025). In addition, deep pockets (> or = 7 mm) showed a significant reduction (3.78 +/- 1.41 versus 2.60 +/- 1.28 mm, P = 0.039) and RAL gain (2.54 +/- 1.27 mm versus 1.29 +/- 0.95 mm, P = 0.01) when doxycycline was applied. The proportion of sites showing RAL gain of 1 to 2 mm was 36.8% versus 21.7% for SRP-D and SRP, respectively (P = 0.01).

CONCLUSION

The use of locally delivered doxycycline may constitute an important adjunct for the treatment of severe periodontal disease in smokers.

Subantimicrobial Dose Doxycycline Efficacy as a Matrix Metalloproteinase Inhibitor in Chronic Periodontitis Patients Is Enhanced When Combined With a Non-Steroidal Anti-Inflammatory Drug

BACKGROUND

Administration of subantimicrobial dose doxycycline (SDD) to chronic periodontitis (CP) patients has repeatedly been found to reduce mammalian collagenase and other matrix metalloproteinase (MMP) activity in gingival tissues and crevicular fluid, in association with clinical efficacy, without the emergence of antibiotic-resistant bacteria either orally or extra-orally. More recently, SDD adjunctive to repeated mechanical debridement resulted in dramatic clinical improvement in patients (>50% smokers) with generalized aggressive periodontitis. As an additional pharmacologic approach, non-steroidal anti-inflammatory drugs (NSAIDs) can reduce gingival inflammation and alveolar bone resorption, at least under experimental conditions. In the current study, we determined the effect of administering a combination (combination) of these two host-modulating drugs (SDD plus low-dose NSAID) to CP patients, on selected neutral proteinases in gingiva, enzymes believed to mediate periodontal breakdown. Earlier preliminary studies in humans with bullous pemphigoid, which is also associated with excessive levels of host-derived proteinases including MMPs, indicated improved clinical efficacy of combination therapy.

METHODS

Nineteen CP patients, scheduled for mucoperiosteal flap surgery bilaterally in the maxillary arch, were randomly distributed into three experimental groups administered either 1) low-dose flurbiprofen (LDF) alone, 50 mg q.d.; 2) SDD (20 mg b.i.d.) alone; or 3) a combination of SDD plus LDF (combination). The gingival tissues were biopsied during surgery from right and left maxillary posterior sextants, before and after a 3-week regimen of medication, respectively. The tissues were then extracted, the extracts partially purified, then analyzed for the endogenous proteinase inhibitor, alpha1-PI, and its breakdown product, and for host-derived matrix metalloproteinases (i.e., collagenases, gelatinases) and neutrophil elastase activities.

RESULTS

Short-term therapy with SDD alone produced a significant reduction and LDF alone produced no reduction in host-derived neutral proteinases. However, the combination therapy produced a statistically significant synergistic reduction of collagenase, gelatinase, and serpinolytic (alpha1-PI degrading) activities (69%, 69%, and 75% reductions, respectively) and a lesser reduction of the serine proteinase, elastase (46%).

CONCLUSIONS

Consistent with previous studies on animal models of chronic destructive disease (e.g., rheumatoid arthritis), the SDD and NSAID combination therapy synergistically suppressed MMP and other neutral proteinases in the gingiva of CP patients. A mechanism, suggested by earlier animal studies, involves the NSAID, in the combination regimen, increasing the uptake of the tetracycline-based MMP inhibitor in the inflammatory lesion, thus synergistically enhancing the efficacy of this medication.

Modulation of the host response in periodontal therapy

This paper was prepared by the Research, Science, and Therapy Committee of the American Academy of Periodontology to provide the dental profession an overview of current and potential methods to modulate the host response in the treatment of periodontal diseases. Specifically, it discusses components of periodontal disease pathogenesis (i.e., immune and inflammatory responses, excessive production of matrix metalloproteinases and arachidonic acid metabolites, and regulation of bone metabolism) and their modulation.

Inhibition of trypsin-like cysteine proteinases (gingipains) from Porphyromonas gingivalis by tetracycline and its analogues

Extracellular cysteine proteinases, referred to as gingipains, are considered important virulence factors for Porphyromonas gingivalis, a bacterium recognized as a major etiologic agent of chronic periodontitis. We investigated the effect of tetracycline and its analogues, doxycycline and minocycline, on the enzymatic activities of gingipains. Tetracyclines at 100 microM totally inhibited the amidolytic activity of arginine-specific gingipains (HRgpA and RgpB). In contrast, inhibition of Kgp was less efficient and required a somewhat higher concentration of the antibiotic to achieve the same effect. Among tetracycline derivatives, the most potent gingipain inhibitor was doxycycline, followed by tetracycline and minocycline. RgpB was inhibited by doxycycline in an uncompetitive and reversible manner with a 50% inhibitory concentration of 3 microM. Significantly, inhibition was unaffected by calcium, excluding the chelating activity of tetracyclines as the mechanism of gingipain inactivation. In contrast, the inhibitory activities of the tetracyclines were reduced by cysteine, a reducing agent, suggesting an interference of the drug at the oxidative region with the catalytic system of the enzyme. Doxycycline, at 10 microM, significantly inhibited the RgpB-mediated production of vascular permeability-enhancing activity from human plasma, thus proving an effective inhibition of gingipain in vivo. These results indicate a new activity of tetracyclines as cysteine proteinase inhibitors and may explain the therapeutic efficiency of these antibiotics in the treatment of periodontitis.

Opportunities and obstacles in veterinary dental drug delivery

Dentistry is a relatively new field in veterinary medicine, despite the fact that dental disease is common in dogs and cats. Obstacles to the development of dental treatments in animals include the diversity of the dentition among the species, the difficulty in administration of oral treatments, the different presentations of oral disease, and the cost of regulatory approval for each species. Mechanical removal of plaque and calculus has been the mainstay of periodontal disease treatment in animals and humans. New adjunctive therapies, as well as new applications for older drugs, are being introduced for periodontal therapy.

Subantimicrobial dose doxycycline as an adjunct to scaling and root planing: post-treatment effects

BACKGROUND/OBJECTIVE

Subantimicrobial dose doxycycline (SDD 20 mg bid) plus scaling and root planing (SRP) significantly improved clinical attachment level (CAL) and reduced probing depth (PD) compared with placebo plus SRP in a double-blind, placebo-controlled, multicenter study of patients with adult periodontitis (AP). In a study conducted as a follow-up, the post-treatment effects of SDD were assessed in patients who completed the SRP study.

METHODS

The SRP study was a 9-month, active-treatment study and the follow-up was a 3-month, no-treatment study. In the SRP study, tooth sites in qualifying quadrants were scaled and root planed and patients were randomized to receive twice daily SDD 20 mg or placebo. In the follow-up, patients received no study drug; investigators and patients remained blinded to the previous treatment group assignments. Efficacy measures included the change in CAL and PD from baseline values determined at the start of the SRP study in tooth sites stratified by baseline PD (i.e., 0-3 mm, 4-6 mm, > or =7 mm). Safety was evaluated using adverse event data and the results of clinical laboratory tests, oral pathology examinations, and microbiological assessments.

RESULTS

Within each disease stratum, the incremental improvements in PD and CAL demonstrated in the SDD group over 9 months of active treatment were maintained through 3 additional months of no treatment. Treatment cessation did not result in an accelerated regression of periodontal health. No differences in the incidence of adverse events (including those related to infection) or laboratory or microbiological parameters were noted between the SDD group and the placebo group.

CONCLUSIONS

The administration of SDD 20 mg bid for a period of up to 9 months is not associated with rebound effects or delayed or negative after-effects for a 3-month period after cessation of therapy.

Adjunctive treatment with subantimicrobial doses of doxycycline: effects on gingival fluid collagenase activity and attachment loss in adult periodontitis

OBJECTIVES

The therapeutic effects of doxycycline and other tetracyclines in the treatment of periodontitis involve, at least in part, mechanisms that are unrelated to their antimicrobial activity. Previous clinical studies have shown that doxycycline administered orally, at doses below those needed for antimicrobial efficacy, to human subjects with adult periodontitis resulted in significantly reduced collagenase activity in gingival crevicular fluid (GCF) and in extracts of inflamed gingival tissues. The purpose of the present study was to identify clinically effective dosing regimens using subantimicrobial dose doxycycline (SDD) as an adjunctive therapy in patients with adult periodontitis.

MATERIAL AND METHODS

A total of 75 adult men and women qualified for enrollment into the three-part, placebo-controlled, double-blind, parallel-group study. Patients were stratified based on repeatedly exhibiting pathologic levels of periodontal attachment (ALv) and GCF collagenase activity at several appointments prior to baseline. Patients were administered a scaling and prophylaxis, then 1 of 5 treatment schedules for 12 weeks (part I), followed by a 12-week period of no drug therapy (part II), a second scaling and prophylaxis, and 12 additional weeks of treatment (part III). Primary determinants of efficacy included reductions in GCF collagenase activity and changes in relative ALv.

RESULTS

66 patients completed the 1st 12 weeks (part I) of the 3-part, 36-week study; 51 patients completed the entire 36-week study. From baseline to week 12 (part I), treatment with specially formulated SDD capsules (20 mg) 2x daily (1 x every 12 h) for up to 12 weeks was shown to significantly reduce GCF collagenase activity and to improve ALv, effects not seen in patients treated with placebo. Continuous drug therapy over the 12-week treatment period was needed to maintain and maximize the reduction in GCF collagenase and the improvement in ALv. Improvements in periodontal disease parameters occurred without the emergence of doxycycline-resistant micro-organisms. In patients administered an "on-off-on" regimen of SDD over 36 weeks (parts I-III), essentially no attachment loss occurred in patients receiving the highest of these SDD regimens (20 mg 2x daily during part I and 20 mg 1 x daily in part III), whereas patients administered placebo capsules experienced a mean attachment loss of approximately 0.8 mm at the 24- and 36-week time periods.

CONCLUSIONS

Doxycycline administered at subantimicrobial doses led to improvements in disease parameters, with no apparent side effects, and appears to have significant potential as an oral adjunctive therapy in the long-term management of adult periodontitis.

Treatment with subantimicrobial dose doxycycline improves the efficacy of scaling and root planing in patients with adult periodontitis

BACKGROUND

In a previous study, subantimicrobial dose doxycycline (SDD) significantly improved clinical parameters associated with periodontal health in patients with adult periodontitis (AP) when used as an adjunct to a maintenance schedule of supragingival scaling and dental prophylaxis. In this double-blind, placebo-controlled, parallel-group, multicenter study, the efficacy and safety of SDD were evaluated in conjunction with scaling and root planing (SRP) in patients with AP.

METHODS

Patients (n = 190) received SRP at the baseline visit and were randomized to receive either SDD 20 mg bid or placebo bid for 9 months. Efficacy parameters included the per-patient mean changes in clinical attachment level (CAL) and probing depth (PD) from baseline, the per-patient percentages of tooth sites with attachment loss (AL) > or = 2 mm and > or = 3 mm from baseline, and the per-patient percentage of tooth sites with bleeding on probing. Prior to analysis, tooth sites were stratified by the degree of disease severity evident at baseline

RESULTS

In tooth sites with mild to moderate disease and severe disease (n = 183, intent-to-treat population), improvements in CAL and PD were significantly greater with adjunctive SDD than with adjunctive placebo at 3, 6, and 9 months (all P <0.05). In tooth sites with severe disease, the per-patient percentage of sites with AL > or = 2 mm from baseline to month 9 was significantly lower with adjunctive SDD than with adjunctive placebo (P<0.05). Improvements in clinical outcomes occurred without detrimental shifts in the normal periodontal flora or the acquisition of doxycycline resistance or multiantibiotic resistance. SDD was well tolerated, with a low incidence of discontinuations due to adverse events.

CONCLUSIONS

The adjunctive use of SDD with SRP is more effective than SRP alone and may represent a new approach in the long-term management of AP.

Iron-chelating activity of tetracyclines and its impact on the susceptibility of Actinobacillus actinomycetemcomitans to these antibiotics

Three tetracyclines (tetracycline, doxycycline, and minocycline) were found to possess iron-chelating activity in a colorimetric siderophore assay. Determination of MICs indicated that the activity of doxycycline against the periodontopathogen Actinobacillus actinomycetemcomitans was only slightly influenced by the presence of an excess of iron that likely saturates the antibiotic. On the other hand, the MICs of doxycycline and minocycline were significantly lower for A. actinomycetemcomitans cultivated under iron-poor conditions than under iron-rich conditions.

A chemically modified nonantimicrobial tetracycline (CMT-8) inhibits gingival matrix metalloproteinases, periodontal breakdown, and extra-oral bone loss in ovariectomized rats

Estrogen deficiency in the postmenopausal (PM) female is the major cause of osteoporosis and may contribute to increased periodontal disease, including alveolar bone loss, seen in these women. In the current study, an animal model of PM osteoporosis, the OVX adult female rat, was studied to determine: (i) the relationship between periodontal breakdown and skeletal bone loss, and (ii) the effect of CMT-8 on gingival collagenase and bone loss. OVX rats were daily gavaged with CMT-8 (1, 2, or 5 mg/rat) for 28 or 90 days; non-OVX rats and those gavaged with vehicle alone served as controls. Elevated collagenase activity, assessed using [3H-methyl] collagen as substrate in the presence or absence of APMA, was seen in the gingiva of the OVX rats, and CMT-8 therapy suppressed this effect. Western blot revealed a similar pattern for MMP-8 and MMP-13 concentrations. The changes in the gingival collagenase activity paralleled changes in periodontal bone loss, which, in turn, reflected trabecular bone density changes. Preliminary studies on PM humans administered sub-antimicrobial tetracycline as a matrix metalloproteinase inhibitor are under way.

Tetracyclines inhibit connective tissue breakdown by multiple non-antimicrobial mechanisms

A seminal experiment involving a germ-free rat model of connective tissue breakdown (followed soon thereafter by a series of in vitro studies) identified an unexpected non-antimicrobial property of tetracyclines (TCs). This ability of TCs to inhibit matrix metalloproteinases (MMPs) such as collagenase was found to reflect multiple direct and indirect mechanisms of action, and to be therapeutically useful in a variety of dental (e.g., adult periodontitis) and medical (e.g., arthritis, osteoporosis, cancer) diseases. The site on the TC molecule responsible for its MMP-inhibitory activity was identified which led to the development of a series of chemically modified non-antimicrobial analogs, called CMTs, which also have therapeutic potential but do not appear to induce antibiotic side-effects. Longitudinal double-blind studies on humans with adult periodontitis have demonstrated that a sub-antimicrobial dose of doxycycline (previously reported to suppress collagenase activity in the periodontal pocket) is safe and effective and has recently been approved by the FDA as an adjunct to scaling and root planing.

Oral and periodontal tissue. Maintenance, augmentation, rejuvenation, and regeneration

This article discusses the controversies, usefulness, and limitations of oral and periodontal tissue maintenance, augmentation, rejuvenation, and regeneration in the dog and cat. It details many of the specialized materials and techniques used in these procedures in attempts to re-establish healthy conditions within the periodontium. Bone loss following tooth extraction is discussed with consideration as to which teeth should have alveolar ridge maintenance procedures and the important reasons as to why. Radiographs show the degree of improvement demonstrated in treatment of various cases involving bone loss from periodontal disease, treatment of bone injuries with oral fractures and their prevention.

Tetracycline and its analogues: a therapeutic paradigm in periodontal diseases

This article discusses the use of tetracyclines in the clinical management of periodontal infections. A review of the drugs pharmacology, pharmacokinetics, and potential adverse effects shows that they are relatively safe if used in appropriate dosages and under controlled conditions. Current data suggest that the routine use of tetracyclines in conjunction with the treatment of periodontitis is unnecessary. However, their distinctive characteristics can be utilized in different delivery systems as an adjunctive aid to conventional treatment of juvenile and refractory forms of periodontitis.

Removal of intracanal smear by doxycycline in vitro

Cleansing and shaping result in a smear layer on the instrumented canal wall surfaces. The smear layer may inhibit close contact between sealers and dentin, and inhibits diffusion of medicaments.

OBJECTIVE

This study assessed the effect of doxycycline hydrochloride (DH) on smear layer on intracanal walls.

STUDY DESIGN

Scanning electron microscopy was used to evaluate the remaining smear layer using different concentrations of DH. Single-canal palatal roots of extracted maxillary molars were irrigated with saline-15% EDTA; saline-25 mg/ml DH; saline-50 mg/ml DH; saline-100 mg/ml DH; NaOCl-15% EDTA; NaOCl-25 mg/ml DH; NaOCl-50 mg/ml DH; and NaOCl-100 mg/ml DH. The roots were fractured into halves and the amount of smear layer assessed in the middle and apical third.

RESULTS

Doxycycline-HCl of 100 mg/ml was the most effective in removing smear layer. In the saline group, 100 mg/ml of DH was more effective than EDTA. In the hypochlorite group, 50 mg/ml and 100 mg/ml of DH were more effective than EDTA (p < 0.05).

CONCLUSION

Doxycycline solution may be an effective irrigant.