Enhanced repair and regeneration of periodontal lesions in tetracycline-treated patients. Case reports

Hybrid system with stable structure of hard/soft tissue substitutes induces re-osseointegration in a rat model of biofilm-mediated peri-implantitis

Re-osseointegration of an infected/contaminated dental implant poses major clinical challenges. We tested the hypothesis that the application of an antibiotic-releasing construct, combined with hard/soft tissue replacement, increases the efficacy of reconstructive therapy. We initially fabricated semi-flexible hybrid constructs of β-TCP/PHBHHx, with tetracycline (TC) (TC amounts: 5%, 10%, and 15%). Thereafter, using in vitro assays, TC release profile, attachment to rat bone marrow-derived stem cells (rBMSCs) and their viability as well as anti-bacterial activity were determined. Thereafter, regenerative efficacies of the three hybrid constructs were assessed in a rat model of peri-implantitis induced by Aggregatibacter actinomycetemcomitans biofilm; control animals received β-TCP/Bio-Gide and TC injection. Eight weeks later, maxillae were obtained for radiological, histological, and histomorphometric analyses of peri-implant tissues. Sulcus bleeding index was chronologically recorded. Serum cytokines levels of IL-6 and IL-1β were also evaluated by enzyme-linked immunosorbent assay. Substantial amounts of tetracycline, from hybrid constructs, were released for 2 weeks. The medium containing the released tetracycline did not affect the adhesion or viability of rBMSCs; however, it inhibited the proliferation of A. actinomycetemcomitans. Osteogenesis and osseointegration were more marked for the 15% hybrid construct group than the other two groups. The height of attachment and infiltration of inflammatory cells within fibrous tissue was significantly reduced in the experimental groups than the control group. Our protocol resulted in re-osseointegration on a biofilm-contaminated implant. Thus, an antibiotic releasing inorganic/organic construct may offer a therapeutic option to suppress infection and promote guided tissue regeneration thereby serving as an integrated multi-layer substitute for both hard/soft tissues.

EVA copolymer matrix for intra-oral delivery of antimicrobial and antiviral agents

Biocompatible ethylene vinyl acetate copolymer (EVA) was utilized to study the release of an antiviral drug (acyclovir (ACY)) and an antimicrobial drug (doxycycline hyclate (DOH)). Release of both drugs from EVA was measured individually and in combination. The effect of drug combination of DOH and ACY is presented. Additionally, the release rate of DOH after coating of the matrix with a different copolymer, in drug-loading with increasing loads of DOH, and with increases in temperature are also presented. The drugs incorporated in EVA films were prepared from the dry sheet obtained by solvent evaporation of polymer casting solutions with drugs. Drug release from the films was examined for about 12 days in distilled water at 37 degrees C. Changes in optical density were followed spectrophotometrically. The combination of ACY and DOH resulted in an increased release of ACY by about three times (P < 0.001) while DOH showed a decrease in rate of about two times compared to the individual release rates (P = 0.008). Increases in drug levels of DOH resulted in increases in drug release rates (P = 0.001). The release rate of DOH increased with temperature (P = .001; 27, 32, 37 and 42 degrees C were studied) and the energy of activation (DeltaE ( not equal) = 56.69 kJ/mol) was calculated using the Arrhenius equation for the diffusion of DOH molecules. Thus, the release rates of drugs were influenced by many factors: drug combination, coating the device, drug-loading, and temperature variation. Therefore it is proposed that controlling these variables should make it possible to obtain therapeutic levels of drugs released from drug loaded polymer, which may be beneficial in treating oral infections.

Periodontal host modulation with antiproteinase, anti-inflammatory, and bone-sparing agents. A systematic review

BACKGROUND

The use of modulating agents, including inhibition of matrix metalloproteinases (MMPs) with antiproteinases, blocking production of proinflammatory cytokines and prostaglandins with anti-inflammatory drugs, and inhibiting activation of osteoclasts with bone-sparing agents, has been postulated to be of therapeutic value as an adjunctive therapy to the management of chronic periodontitis.

RATIONALE

The objective of this systematic review of the literature was to assess the adjunctive efficacy of antiproteinase, anti-inflammatory, and bone-sparing host-modulating agents in the treatment of gingivitis, aggressive periodontitis, and chronic periodontitis. FOCUSED QUESTIONS: 1. In patients with periodontal diseases, what is the effect of host-modulation agents, alone or combined with conventional therapy, compared to conventional therapy alone as assessed by clinical, radiographic, adverse, and patient-centered outcomes? 2. In patients with dental implants, what is the effect of host-modulation agents on implant success assessed by clinical, radiographic, adverse, and patient-centered outcomes?

SEARCH PROTOCOL

MEDLINE, Embase, and the Cochrane Library databases were searched without language restrictions through April 1, 2002 for studies that used tetracycline (TET)-related matrix metalloproteinase (MMP) inhibitors, or non-steroidal anti-inflammatory drugs (NSAIDs) and bisphosphonate anti-osteolytic agents. The investigation also included hand searching of journals and contacting authors and industry experts.

SELECTION CRITERIA

INCLUSION CRITERIA

Only human studies (randomized controlled clinical trials, cohort studies, case-control studies, cross-sectional studies, and case series) were selected. Studies were on subjects with gingivitis, aggressive or chronic periodontitis, or dental implants. Interventions included TET-related MMP inhibitors, NSAIDs, or bisphosphonate anti-osteolytic agents.

EXCLUSION CRITERIA

Studies that used MMP tissue inhibitors as diagnostic or prognostic indicators of periodontal disease or that evaluated short-term systemic antibodies or locally delivered levels of drugs with antiproteinase activity were excluded.

DATA COLLECTION AND ANALYSIS

The primary outcomes for assessment were changes in bone or clinical attachment levels (CAL); secondary outcomes included clinical measures of plaque, gingival inflammation, probing depth (PD), and mobility. Summary data appropriate for meta-analysis were pooled using a weighted average and analyzed using a standardized difference; the results were checked with both fixed-effects and random-effects models.

MAIN RESULTS

1. A meta-analysis done on the studies reporting changes in CAL and PD following administration of sub-antimicrobial doses of doxycycline (SDD) in conjunction with scaling and root planing (SRP) in patients with periodontitis showed a statistically significant beneficial adjunctive effect. 2. There were insufficient data to provide meta-analyses on periodontal patients treated with other host-modulating agents; descriptive tables are included. 3. NSAIDS show promise in their ability to slow periodontal disease. 4. Preliminary data on bisphosphonate agents indicate there is a potential role for these agents in periodontitis management. 5. There are a very limited number of studies on host-modulating agents and dental implants and no analyses were possible. 6. Because the treatment methodologies and clinical variables differed considerably among the studies, it is difficult to summarize the information and identify a reliable total patient population.

REVIEWERS' CONCLUSIONS

1. Large multi-center trials are needed to evaluate the role of host-modulating agents in the treatment of periodontitis. 2. NSAIDS and bisphosphonate drugs may have a potential adjunctive role in periodontal therapy. 3. The adjunctive use of SDD with SRP is statistically more effective than SRP alone in reducing PD and in achieving CAL gain.

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.

The effects of different tetracyclines on the dentin root surface of instrumented, periodontally involved human teeth: a comparative scanning electron microscope study

This in vitro study compares, by scanning electron microscope (SEM) examination, the surface effects of various topical applications of tetracycline on the instrumented dentin root surface of human teeth. Eighty-two (82) dentin samples were prepared from periodontally-compromised teeth planned for extraction. Solutions of tetracycline HCl, doxycycline, minocycline, sumycin, and a saline control were prepared and applied to the dentin samples for 0.5, 1, 3, 5, and 10 minutes. Each solution pH was measured: tetracycline HCI (pH 1.6), doxycycline (pH 2.2), minocycline (pH 3.8), sumycin (pH 4.4), and saline (pH 5.1). A tetracycline periodontal fiber was also evaluated at 1, 4, 7, and 10 days of exposure for dentin surface effects. Tetracycline HCI removed the dentin smear layer leaving clean and open tubules significantly better than other solutions tested in as little as 30 seconds. Doxycycline and minocycline produced similar results to each other, which were significantly better than sumycin and saline, but not as effective as tetracycline HCl. Smear layer removal was attained by doxycycline and minocycline in five to ten minutes; however, sumycin and the saline control ineffectively removed the surface smear layer and dentinal tubules remained partially to totally occluded by debris. The periodontal fiber did not significantly alter the surface smear layer. Results of this study suggest that tetracycline HCl is the best current tetracycline form for root surface conditioning as measured by its ability to affect both dentin smear layer removal and dentin tubule exposure.

The gelatinase inhibitory activity of tetracyclines and chemically modified tetracycline analogues as measured by a novel microtiter assay for inhibitors

A quantitative nonisotopic solution assay for gelatinases and inhibitors was developed using biotinylated gelatin as enzyme substrate. In this assay, residual biotinylated substrate is sandwiched between avidin-coated plates and streptavidin-peroxidase and is quantified by the peroxidase reaction. This assay was useful for measuring gelatinase activities and defining the activities of gelatinase inhibitors. When 23 tetracycline analogues were compared, significant differences in gelatinase B inhibition were found between various compounds. 4-epioxytetracycline base, 4-epichlortetracycline, meclocyclinesulfosalicylate, and unmodified metacycline and minocycline proved to be the most potent gelatinase B (EC 3.4.24.35) inhibitors. The gelatinase B inhibitory activity of tetracyclines was clearly dissociated from their antimicrobial activity. The effect of high-molecular-weight inhibitors, such as monoclonal antibodies, was also demonstrable in the microtiter plate assay. In view of the pathophysiological function of gelatinases, the definition of gelatinase inhibitors with known efficacy, safety, and side effects is crucial for the treatment of diseases such as rheumatoid arthritis and multiple sclerosis. Particular tetracyclines fulfil these criteria and the described assay is useful for defining other gelatinase-inhibiting lead compounds.

Microbiological monitoring

If periodontal disease is due to a limited number of bacterial species, then continuous maximal plaque suppression is not the only possibility for prevention and therapy. Specific elimination or reduction of pathogenic bacteria from plaque becomes a valid alternative. Recent studies indicate that the elimination of certain putative pathogens is particularly difficult. New diagnostic methods should allow the choice of better suited procedures, make chosen procedures more effective (through better timing, dosage, selection of devices or drugs, increase of specificity, etc.) or lead to the elimination of unnecessary work (e.g., the treatment of non-susceptible sites or patients). The benefit of newly proposed tests depends on the possible impact of the obtained information on clinical decisions and on the consequences these decisions have for treatment. Thus, diagnostic methods and therapeutical options have to be evaluated together.

Tetracyclines in the management of periodontal diseases. A review

Periodontal diseases essentially comprise a group of oral infections whose primary aetiological factor is dental plaque. Removal of the cause (and its effects) is the primary aim of both non-surgical and surgical treatment regimens, although the infective nature of the diseases has led to the widespread use of antimicrobials as an adjunct to mechanical debridement. The tetracyclines are primarily bacteriostatic agents that are effective against many Gram-negative species including putative periodontopathogens such as Actinobacillus actinomycetemcomitans (A.a.). The proven efficacy of this group of drugs in the management of periodontal diseases may be related not only to their antibacterial actions, but to a number of additional properties that have been recently identified. These include collagenase inhibition, anti-inflammatory actions, inhibition of bone resorption and their ability to promote the attachment of fibroblasts to root surfaces. Consequently, tetracyclines have also been used as an adjunct to bone grafting in periodontal defects, and as agents for 'conditioning' root surfaces to enhance the regeneration of periodontal tissues. When tetracyclines are taken orally, consideration must be given both to the potential unwanted effects and to interactions with other drugs that are taken concurrently. Such problems are minimised however, when the drugs are incorporated into controlled, slow-release formulations which are currently being researched and marketed for intra-oral use.

Microbial identification and antibiotic sensitivity testing, an aid for patients refractory to periodontal therapy. A report of 3 cases

The importance of microbial surveillance is illustrated in 3 clinical cases. Each case demonstrated a continued lack of response to conventional periodontal treatment. Repeated bouts of periodontal abscess formation and bone loss occurred over a 3- to 4-year period, despite numerous surgeries supplemented with antibiotics. As a result, patients were termed refractory to treatment and extensive microbiological analysis and sensitivity testing was performed. Following institution of the appropriate antibiotic and conservative therapy consisting of several sessions of scaling and root planning, each of these cases demonstrated a dramatic remission of disease progression. No further breakdown has been seen for a minimum of 2 1/2 years. While anecdotal in nature, these cases support the usefulness of microbial identification coupled with antibiotic sensitivity as an adjunct to conventional conservative periodontal therapy.

Report of the Committee on Scientific Investigation of the American Academy of Restorative Dentistry

The committee screened several hundred articles, citing 518 published papers. Some are present quality in research, others provide clinical interest, and some are identified as misleading. New techniques in pulp physiology and pathology are reported. Laser use and techniques in prevention, restorative dentistry, and materials use are reported. Epidemiology of selected diseases and the results of various formulations for treatment are cited. Diagnosis of craniomandibular dysfunction is well represented as well as references to literature reviews and other sophisticated scientific investigation. Research on adhesives is presented in respect to bonding agents for dentin and enamel. Several clinical studies are included, along with customary laboratory reports on several materials.