Richard A. Reinhardt

Antibody responses to Porphyromonas gingivalis (P. gingivalis) in subjects with rheumatoid arthritis and periodontitis

UNLABELLED Antibody titers to P. gingivalis are increased in patients with rheumatoid arthritis and are associated with disease-specific autoimmunity. BACKGROUND Periodontitis (PD) has been implicated as a risk factor for rheumatoid arthritis (RA). We sought to characterize antibody titers to P. gingivalis (a pathogen in PD) in subjects with RA, PD, and in healthy controls and to examine their relationship with disease autoantibodies. METHODS P. gingivalis antibody was measured in subjects with RA (n=78), PD (n=39), and in controls (n=40). Group frequencies of bacterial titer elevations were compared using the Chi-square test and antibody titers were compared using non-parametric tests. Correlations of P. gingivalis titer with C-reactive protein (CRP), antibody to cyclic citrullinated peptide (anti-CCP), and rheumatoid factor (RF) were examined in those with RA while CRP and autoantibody concentrations were compared based on seropositivity to P. gingivalis. RESULTS Antibody titers to P. gingivalis were highest in PD, lowest in controls, and intermediate in RA (p=0.0003). Elevations in P. gingivalis (titer> or =800) were more common in RA and PD (67% and 77%, respectively) than in controls (40%) (p=0.002). In RA, there were significant correlations with P. gingivalis titer with CRP, anti-CCP-IgM, and -IgG-2. CRP (p=0.006), anti-CCP-IgM (p=0.01) and -IgG2 (p=0.04) concentrations were higher in RA cases with P. gingivalis titers > or =800 compared to cases with titers <800. CONCLUSION Antibodies to P. gingivalis are more common in RA subjects than controls, although lower than that in PD. Associations of P. gingivalis titers with RA-related autoantibody and CRP concentrations suggests that infection with this organism plays a role in disease risk and progression in RA.

Prostaglandin E (PGE) and interleukin-1β (IL-1β) levels in gingival crevicular fluid during human orthodontic tooth movement

The purpose of this study was to examine gingival crevicular fluid (GCF) levels of two potent bone resorbing mediators, prostaglandin E (PGE) and interleukin-1β (IL-1β), during human orthodontic tooth movement. The study included 10 patients, each having one treatment tooth undergoing orthodontic movement and a contralateral control tooth. The GCF was sampled at control sites and treatment (compression) sites before activation and at 1, 24, 48, and 168 hours. Prevention of plaque-induced inflammation allowed this study to focus on the dynamics of mechanically stimulated PGE and IL-1β GCF levels. The PGE and IL-1β levels were determined with radioimmunoassay. At 1 and 24 hours, mean GCF IL-1β levels were significantly elevated at treatment teeth (8.9±2.0 and 19.2±6.0 pg, respectively) compared with control teeth (2.0±1.1 pg, p=0.0049, and 2.9±1.0 pg, p=0.0209, respectively). The GCF levels of PGE for the treatment teeth were significantly higher at 24 and 48 hours (108.9±11.9 and 97.9±7.3 pg) than the control teeth (61.8±7.2 pg, p=0.0071, and 70.8±7.4 pg, p=0.0021, respectively). The GCF levels of PGE and IL-1β remained at baseline levels throughout the study for the control teeth, whereas significant elevations from baseline in GCF IL-1β (24 hours) and PGE levels (24 and 48 hours) were observed over time in the treatment teeth (p≤0.05). These results demonstrate that bone-reorbing PGE and IL-1β produced within the periodontium are detectable in GCF during the early phases of tooth movement and return to baseline within 7 days.

Nickel release from orthodontic arch wires and cellular immune response to various nickel concentrations

AIMS Results from two previous clinical studies suggested that exposure to high nickel-containing orthodontic arch wires may induce hypersensitivity in certain individuals. The purpose of this study was to measure the amount of nickel released from three types of nickel-containing arch wires into a synthetic saliva in vitro, and determine if the concentrations were sufficient to elicit either cytotoxic (trypan blue exclusion test) or stimulatory (MTT test) responses in human peripheral blood mononuclear cells (PBMCs) derived from nickel-sensitive and nickel-nonsensitive individuals. PBMCs were exposed to five concentrations of nickel sulfate solutions ranging from 0-29 ppm, and results were compared, particularly at concentrations obtained from nickel release experiments. FINDINGS The amount of nickel released into synthetic saliva ranged from 0.4-4.1 ppb. Wires subjected to a combination of soaking and cyclic straining released significantly more nickel than those that were soaked only (p </= 0.05), and NiTi wires released significantly more nickel than did stainless steel or nitrogen-implanted NiTi wires (p </= 0.05). For PBMCs, significant increased cell proliferation was not observed for any nickel concentration. PBMC cell death rates were highest at nickel concentrations of 29 ppm when the cells were cultured without a cell growth promoter (p </= 0.05), and MTT test values were significantly reduced at both 2.9 and 29 ppm when a growth promoter was included (p </= 0.05). CONCLUSION The maximum amount of nickel released from all tested arch wires was 700 times lower than the concentrations necessary to elicit cytotoxic reactions in human PBMCs.

Dentin Stresses in Post-reconstructed Teeth with Diminishing Bone Support

Dentin stresses from simulated functional loads to post-reinforced tooth models with four levels of periodontal support were calculated using finite element analysis. As bone levels diminished, stresses were found to increase dramatically and to concentrate in the small amount of dentin remaining near the post apex.

The Effect of Local Simvastatin Delivery Strategies on Mandibular Bone Formation In Vivo

Systemic simvastatin is known to reduce cholesterol and stimulate modest bone formation, but local surgical placement in polylactic acid domes causes robust bone formation and local swelling. A less invasive and more flexible injection protocol was studied to evaluate the bone-inducing effects compared to surgical implantation. Bone formation rate, short- and long-term bone augmentation histology, and mechanical properties were evaluated to characterize the new bone in a rat bilateral mandible model (test and control sides in same animal). Results demonstrated that multiple (3) injections of 0.5 mg simvastatin effectively reduced soft tissue swelling while preserving bone growth (60% increase of bone width at 24 days) compared to simvastatin dome placement (43% increase at 24 days). Compared to controls, bone formation rate was significantly higher on the simvastatin side, especially in the dome. Three-point bending tests revealed higher maximum force to fracture and stiffness at 24 days with simvastatin injections. Long-term evaluation showed that 55% of maximum new bone formed 24 days post-injection was retained at 90 days.

Association of Gingival Crevicular Fluid Biomarkers During Periodontal Maintenance With Subsequent Progressive Periodontitis

BACKGROUND The analysis of biomarkers in gingival crevicular fluid (GCF) may be helpful in forecasting patient vulnerability to future attachment loss. The purpose of this study is to correlate GCF biomarkers of inflammation and bone resorption with subsequent periodontal attachment and bone loss in a longitudinal trial of a matrix metalloproteinase (MMP) inhibitor. METHODS GCF was collected from two periodontal pockets (mean +/- SD: 5.1 +/- 1.0 mm) at baseline and annually in postmenopausal females with moderate to advanced periodontitis undergoing periodontal maintenance every 3 to 4 months during a 2-year double-masked, placebo-controlled, randomized clinical trial of subantimicrobial dose doxycycline (SDD; 20 mg two times a day). Subjects were randomized to SDD (n = 64) or a placebo (n = 64). GCF was analyzed for the inflammation markers interleukin (IL)-1beta (using enzyme-linked immunosorbent assay), total collagenase activity (using hydrolysis of a synthetic octapeptide), and MMP-8 (using a Western blot) and the bone-resorption marker carboxyterminal telopeptide cross-link fragment of type I collagen (ICTP) (using a radioimmunoassay). Generalized estimating equations were used to associate these biomarkers, categorized into tertiles, with subsequent clinical attachment (using an automated disk probe) or interproximal bone loss (using radiography). Odds ratio (OR) values compared highest to lowest tertile groups. RESULTS Increases in GCF IL-1beta and MMP-8 during the first year of periodontal maintenance were associated with increased odds of subsequent (year 2) periodontal attachment loss (OR = 1.67; P = 0.01 and OR = 1.50; P = 0.02, respectively) driven by the placebo group. Elevated baseline ICTP was also associated with increased odds of 1- and 2-year loss of alveolar bone density (OR = 1.98; P = 0.0001) in the placebo group, not the SDD group, and a loss of bone height (OR = 1.38; P = 0.06), again driven by the placebo group. CONCLUSION These data support the hypothesis that elevated GCF biomarkers of inflammation and bone resorption from a small number of moderate/deep sites have the potential to identify patients who are vulnerable to progressive periodontitis, and SDD may modify that risk.

Development and characterization of tetracycline-poly(lactide/glycolide) films for the treatment of periodontitis

Abstract Local delivery of antibiotics has been shown to be effective in reducing periodontopathic micro-organisms. The objective of this research was to develop a biodegradable, poly( d , l -lactide/glycolide), 85:15, (PLGA) film that was capable of delivering therapeutic concentrations of tetracycline HCl for a duration of two weeks into the intra-crevicular fluid within the inflamed periodontal pocket. Films (10 × 2 × 0.5 mm) containing varying amounts (10 to 25% w/w) of tetracycline HCl were prepared by film casting a dispersion of the drug in a solution of PLGA dissolved in methylene chloride. Differential dissolution studies were performed in buffer, pH 7.3, at 37°C. Both the rate and percent of drug released increased as drug loading and dissolution media pH increased. However, complete release of drug from the films was not obtained as 83.1 ± 7.0 μg of tetracycline HCl per mg of PLGA was retained for all drug loadings. Linear relationships obtained for graphs of the percent released versus both the square root of time ( r 2 ≥ 0.96) and drug loading ( r 2 ≥ 0.99) indicated a matrix-controlled release from a porous, granular, monolithic system. Preliminary results from a clinical study with 8 periodontal, maintenance patients indicate that films containing 25% w/w tetracycline HCl were effective in decreasing the bacterial count in the intra-crevicular fluid and demonstrated a significant ( p ⩽ 0.01) microbial inhibition for two weeks over the control placebo film. The decrease in tetracycline HCl concentration in the gingival fluid was approximated by a first order relationship with the tetracycline HCl disappearance rate constant of 0.19 days −1 .

Statins, bone metabolism and treatment of bone catabolic diseases

The discovery that statins had bone anabolic properties initiated many investigations into their use for treatment of bone catabolic diseases, such as osteoporosis. This paper reviews the molecular basis of statins role in bone metabolism, and animal and human studies on the impact of systemic statins on osteoporosis-induced bone fracture incidence and healing, and on bone density. Limitations of systemic statins are described along with alternative dosing strategies, including local applications and bone-targeting systemic preparations. The principal findings of this review are: (1) traditional oral dosing with statins results in minimal efficacy in the treatment of osteoporosis; (2) local applications of statins show promise in the treatment of accessible bony defects, such as periodontitis; and (3) systemically administered statins which can target bone or inflammation near bone may be the safest and most effective strategy in the treatment of osseous deficiencies.

Osteotropic β-cyclodextrin for local bone regeneration

An osteotropic alendronate-beta-cyclodextrin conjugate (ALN-beta-CD) was developed as a bone-targeting delivery system for improved treatment of skeletal diseases. The conjugate shows very strong binding to hydroxyapatite (HA, main component of the skeleton). Its ability in forming molecular inclusion complex with prostaglandin E(1) (PGE(1), a potent bone anabolic agent) was confirmed by phase solubility experiments and differential scanning calorimetry (DSC). In a bilateral rat mandible model, ALN-beta-CD/PGE(1) molecular complex was shown to stimulate strong local bone anabolic reaction. In the control study, ALN-beta-CD itself was also found to be bone anabolic. To investigate this finding, other control groups were studied. The histomorphometry data suggest that ALN-beta-CD itself could generate more new bone at the injection site than its complex with PGE(1). Alendronate (ALN) injection could also cause new bone formation, which locates peripheral to the site of injection. PGE(1), saline or ethanol injections do not have anabolic effect. These findings were also confirmed by micro-CT evaluation of mandibular bones. It is clear that the bone anabolic effect of ALN-beta-CD is independent of mechanical stimuli of the periosteum or ALN injection alone. Further studies are warranted to understand the working mechanism of ALN-beta-CD as a bone anabolic agent.

Triclosan-loaded tooth-binding micelles for prevention and treatment of dental biofilm.

ABSTRACTPurposeTo develop tooth-binding micelle formulations of triclosan for the prevention and treatment of dental caries.MethodsAlendronate (ALN) was conjugated to the chain termini of different Pluronic copolymers to confer tooth-binding ability to the micelles. Using 3 different formulation methods, Pluronics and ALN-modified Pluronics were used to prepare triclosan-loaded tooth-binding micelles. The formulation parameters were optimized for triclosan solubility, particle size, hydroxyapatite (HA) binding capability and in vitro drug release profile. The optimized formulation was tested on an in vitro biofilm model.ResultsDirect dissolution was selected as the best formulation method. Triclosan-loaded tooth-binding micelles were able to inhibit initial biofilm growth of Streptococcus mutans UA159 by 6-log CFU/HA disc compared to the untreated control. These tooth-binding micelles were also able to reduce the viability of preformed biofilm by 4-log CFU/HA disc compared to the untreated control.ConclusionsTriclosan-loaded tooth-binding micelle formulations have been successfully developed and optimized in this study. These micelle formulations demonstrated promising anti-cariogenic bacteria capabilities and may find applications in the prevention and treatment of dental caries.