Topical chemotherapy in human periodontitis using a new controlled-release insert containing ofloxacin. I. Microbiological observation

Current Drug Delivery Strategies for Buccal Cavity Ailments using Mouth Dissolving Wafer Technology: A Comprehensive Review on the Present State of the Art

BACKGROUND

Mouth-dissolving wafer is polymer-based matrice that incorporates various pharmaceutical agents for oral drug delivery. This polymeric wafer is ingenious in the way that it needs not be administered with water, like in conventional tablet dosage form. It has better compliance among the pediatric and geriatric groups owing to its ease of administration.

OBJECTIVE

The polymeric wafer dissolves quickly in the oral cavity and is highly effective for a targeted local effect in buccal-specific ailments. It is a safe, effective, and versatile drug delivery carrier for a range of drugs used to treat a plethora of oral cavity-specific ailments that inflict common people, like thrush, canker sores, periodontal disease, benign oral cavity tumors, buccal neoplasm, and malignancies. This review paper focuses thoroughly on the present state of the art in mouth-dissolving wafer technology for buccal drug delivery and targeting. Moreover, we have also addressed present-time limitations associated with wafer technology to aid researchers in future developments in the arena of buccal drug delivery.

CONCLUSION

This dynamic novel formulation has tremendous future implications for designing drug delivery systems to target pernicious ailments and diseases specific to the buccal mucosa. In a nutshell, this review paper aims to summarize the present state of the art in buccal targeted drug delivery.

Supra and subgingival application of antiseptics or antibiotics during periodontal therapy

Periodontal diseases (gingivitis and periodontitis) are characterized by inflammatory processes which arise as a result of disruption of the balance in the oral ecosystem. According to the current S3 level clinical practice guidelines, therapy of patients with periodontitis involves a stepwise approach that includes the control of the patient's risk factors and the debridement of supra and subgingival biofilm. This debridement can be performed with or without the use of some adjuvant therapies, including physical or chemical agents, host modulating agents, subgingivally locally delivered antimicrobials, or systemic antimicrobials. Therefore, the main aim of this article is to review in a narrative manner the existing literature regarding the adjuvant application of local agents, either subgingivally delivered antibiotics and antiseptics or supragingivally applied rinses and dentifrices, during the different steps in periodontal therapy performed in Europe.

Drug-Coated Floss to Treat Gum Diseases: In Vitro and In Vivo Characterization

Treatment of gum disease often requires antibiotic treatment. In this study, our objective was to advance the practicality of drug-coated floss as an intra gum pocket drug delivery system. The initial design of this delivery system has been previously reported by us. Here, we advance the concept further through in vitro and in vivo evaluation. A floss piece was dip coated in the middle section with model molecules leaving free ends for holding. Porcine gum tissues were used ex vivo and in vivo to evaluate the coated floss, including effect of coating thickness on delivery efficiency, ability to deliver more than one type of molecule (one hydrophilic and one hydrophobic), mechanical properties using a scratch test, and finally retention of delivered material in vivo in the porcine model. After reaching a certain coating thickness, the delivery efficiency of the coated floss decreased, indicating the presence of an optimal coating thickness. Hydrophobic and hydrophilic molecules were successfully coated and delivered with high efficiency into gum pockets. The scratch test indicated that the coatings were resilient. Lastly, the in vivo analysis showed that the drug coating was delivered into the porcine gum pocket with about 65% efficiency, and the coatings could maintain extended residency within the gum pocket despite the native adverse environment of the oral cavity. Overall, this data shows that drug-coated floss can act as a drug delivery vehicle and has potential to provide a minimally invasive and practical method for the delivery of drugs into the gum pockets.

Controlled release of iodine from cross-linked cyclodextrin metal-organic frameworks for prolonged periodontal pocket therapy

Effective therapeutic system to periodontitis was designed using cross-linked cyclodextrin metal-organic framework (COF) as carrier for iodine and further suspended in hydroxyethyl cellulose gel as I2@COF-HEC hydrogel. Inclusion of iodine within the COF was demonstrated by SR-FTIR spectral and characteristic DSC and TGA changes. Molecular modelling identified the interaction of iodine with both COF central cavity and individual cyclodextrin moieties of COF. In vitro results of study demonstrated that iodine release in artificial saliva from I2@COF-HEC hydrogel could be extended up to 5 days, which was slower than I2@COF particles. Using an in vivo rat model of periodontitis, micro-computed tomography of alveolar bone morphology demonstrated that I2@COF-HEC hydrogel showed similar effects in decreasing periodontal pocket depth and alveolar bone resorption to minocycline ointment, a periodontitis antibiotic. The I2@COF-HEC hydrogel is a novel local delivery device of iodine as a broad spectrum antimicrobial use for treatment of periodontitis.

Sustained-release delivery of antimicrobial drugs for the treatment of periodontal diseases: Fantasy or already reality?

Periodontal diseases are prevalent in humans. Conventional means of combating these diseases involve basic oral hygiene, mostly toothbrushing, use of mouthwashes, and flossing. Supplementary means of treatment, either clinical or pharmaceutical, are often necessary. The use of sustained-release delivery systems, applied locally to the periodontal pocket, seems to be one feasible approach: local sustained-release delivery of antibacterial agents to treat periodontal diseases is conceivable. The use of local (intrapocket) sustained-release delivery systems has numerous clinical, pharmacologic, and toxicologic advantages over conventional treatments for periodontal diseases. Sustained-release technology has been proven to be effective over the last few decades. Films, gels, and fibers are the three main classical intrapocket pharmaceutical delivery systems. Research today is more focused on improving drug delivery, and less on introducing new drugs. New approaches, eg, those making use of nanotechnology, are emerging for local drug-delivery systems. The local sustained-release delivery system concept is innovative and a few products are already commercially available.

Emerging Applications of Drug Delivery Systems in Oral Infectious Diseases Prevention and Treatment

The oral cavity is a unique complex ecosystem colonized with huge numbers of microorganism species. Oral cavities are closely associated with oral health and sequentially with systemic health. Many factors might cause the shift of composition of oral microbiota, thus leading to the dysbiosis of oral micro-environment and oral infectious diseases. Local therapies and dental hygiene procedures are the main kinds of treatment. Currently, oral drug delivery systems (DDS) have drawn great attention, and are considered as important adjuvant therapy for oral infectious diseases. DDS are devices that could transport and release the therapeutic drugs or bioactive agents to a certain site and a certain rate in vivo. They could significantly increase the therapeutic effect and reduce the side effect compared with traditional medicine. In the review, emerging recent applications of DDS in the treatment for oral infectious diseases have been summarized, including dental caries, periodontitis, peri-implantitis and oral candidiasis. Furthermore, oral stimuli-responsive DDS, also known as "smart" DDS, have been reported recently, which could react to oral environment and provide more accurate drug delivery or release. In this article, oral smart DDS have also been reviewed. The limits have been discussed, and the research potential demonstrates good prospects.

Potential of chitosan-based carrier for periodontal drug delivery

Periodontal diseases are chronic infectious diseases and are a major oral health burden. With the progress in the understanding of etiology, epidemiology and pathogenesis of periodontal diseases coupled with the understanding of the polymicrobial synergy in the dysbiotic oral microbial flora, several new therapeutic targets have been identified. The strategies to curb bacterial growth and production of factors that gradually destroy the tissue surrounding and supporting the teeth have been the cornerstone for inhibiting periodontitis. Systemic administration of antibiotics for the treatment of periodontitis have shown several drawbacks including: inadequate antibiotic concentration at the site of the periodontal pocket, a rapid decline of the plasma antibiotic concentration to sub-therapeutic levels, the development of microbial resistance due to sub-therapeutic drug levels and peak-plasma antibiotic concentrations which may be associated with various side effects. These obvious disadvantages have evoked an interest in the development of localized drug delivery systems that can provide an effective concentration of antibiotic at the periodontal site for the duration of the treatment with minimal side effects. A targeted sustained release device which could be inserted in the periodontal pocket and prolong the therapeutic levels at the site of action at a much lower dose is the need of the hour. Chitosan, a deacetylated derivative of chitin has attracted considerable attention owing to its special properties including antimicrobial efficacy, biodegradability, biocompatibility and non-toxicity. It also has the propensity to act as hydrating agent and display tissue healing and osteoinducting effect. The aim of this review is to shine a spotlight on the chitosan based devices developed for drug delivery application in the effective treatment of various periodontal disorders. The chitosan based carriers like fibers, films, sponge, microparticles, nanoparticles, gels that have been designed for sustained release of drug into the periodontal pocket are highlighted.

Induced osteoclastogenesis by fluoroquinolones in unstimulated and stimulated human osteoclast precursor cells

Fluoroquinolones (FQs) are a class of antibiotics with a broad spectrum of activity, known to disturb bone metabolism. The aim of this work was to characterize the cellular and molecular effects of five FQs (ofloxacin, norfloxacin, ciprofloxacin, levofloxacin and moxifloxacin) in unstimulated and stimulated human osteoclast precursors. Peripheral blood mononuclear cells (PBMC) were cultured in the absence (unstimulated) or in the presence of osteoclastogenic factors (M-CSF and RANKL, stimulated), and were treated with FQs (0.3×10(-9)-10(-3) M), for 21 days. In unstimulated PBMC cultures, FQs (excepting moxifloxacin) exhibited a high osteoclastogenic potential, as shown by a significant increase in the expression of osteoclastic genes, TRAP activity and, specially, number of TRAP-positive multinucleated cells and calcium phosphate resorbing ability, suggesting the presence of mature and functional osteoclasts. Norfloxacin and levofloxacin induced the higher effect, followed by ciprofloxacin and ofloxacin. A decrease on apoptosis and an increase on M-CSF expression might have a possible contribution in the observed cellular behavior. In stimulated PBMC cultures, FQs further increase the osteoclastogenic response induced by M-CSF and RANKL (except ofloxacin). However, the osteoclastogenic response was much lower than that observed in unstimulated PBMC cultures. Both in unstimulated and stimulated PBMC cultures, for most of the FQs, the osteoclastogenic effects were observed in a wide range of concentrations, representative of plasmatic and tissue levels attained in several clinical settings. The various FQs differed on the stimulatory concentration range, the extent of the induced osteoclastogenic response and, also, on the dose- and time-dependent profile. Nevertheless, at high concentrations all the FQs seemed to elicit an increase on apoptosis. Additionally, some differences were noted in the intracellular signaling pathways tested, namely NFkB, MEK and PGE2 production. Results suggest that, considering the inter-individual variability of the FQs pharmacokinetics, the detailed biological profile of each FQ on bone cells is of utmost importance to clarify the effects of these compounds on bone metabolism.

Recent approaches for the treatment of periodontitis

Periodontal disease is a localised inflammatory response caused by the infection of a periodontal pocket arising from the accumulation of subgingival plaque. Periodontal disease has been considered as a possible risk factor for other systemic diseases such as cardiovascular diseases and pre-term low birth weight infants. Advances in understanding the aetiology, epidemiology and microbiology of periodontal pocket flora have revolutionised the therapeutic strategies for the management of periodontal disease progression. This review summarises the recent developments in the field of intra-pocket drug delivery systems and identifies areas where further research may lead to a clinically effective intra-pocket delivery system.

The effects of tetracycline, minocycline, doxycycline and ofloxacin on Prevotella intermedia biofilm

Prevotella intermedia, a black-pigmented, anaerobic, gram-negative bacterium, is associated with various type of periodontitis. Antibiotic treatments via a systemic or local route have been reported as being useful for treating periodontal disease. The purpose of this study was to examine the effects of four antibiotics, tetracycline (TET), minocycline (MINO), doxycycline (DOXY) and ofloxacin (OFLX) on P. intermedia biofilms at minimum inhibitory concentrations (MIC) from one-fold to 100-fold. MICs were determined for planktonic cells. Biofilm formation was determined with the crystal violet stain method and the bioactivities in the biofilms were determined with the adenosine triphosphate (ATP) -bioluminescent assay using a 96-well culture plate. At one-fold MIC, DOXY inhibited biofilm formation by P. intermedia ATCC 25611. Other antibiotics at one-fold MIC had no effects on the biofilm formation of tested bacterial strains. In P. intermedia ATCC 25611 biofilms, all the antibiotics tested showed inhibitory activities at five- to 100-fold MICs. In the biofilms of P. intermedia strains, except ATCC 25611, treated with three tetracycline antibiotics, the bioactivities were significantly increased, indicating the difficulties involved in designing antibiotic therapy for periodontal disease.

Impact of local adjuncts to scaling and root planing in periodontal disease therapy: a systematic review

BACKGROUND

Chronic periodontitis affects many adults in the United States, some severely enough to threaten tooth loss. Of particular clinical importance is whether scaling and root planing (SRP) accompanied by a local adjunctive therapeutic agent improves outcomes over time compared to SRP alone. The adjunctive therapeutic agents investigated include: tetracycline, minocycline, metronidazole, a group of other antibiotics, chlorhexidine, and a group of antimicrobials. Primary outcomes considered are reductions in probing depth (PD) and gains in clinical attachment level (CAL).

METHODS

RTI-UNC Evidence-Based Practice Center staff searched MEDLINE (1966 through December 2002) and EMBASE (through February 2002) to identify clinical trials published in English that 1) involved adults with chronic periodontitis but no serious comorbidities; 2) tested one or more chemical antimicrobial agents as an adjunct to SRP alone or with a placebo; 3) had a concurrent control group that received the same SRP as the treatment group; 4) reported outcomes for specified, fixed time periods; and 5) if multiple antimicrobials were tested, reported outcomes for each agent separately. We performed qualitative analyses and meta-analyses of PD and CAL effect sizes when the necessary data were available from at least three studies at 6-month follow-up.

RESULTS

Among the locally administered adjunctive antimicrobials, the most positive results occurred for tetracycline, minocycline, metronidazole, and chlorhexidine. Adjunctive local therapy generally reduced PD levels. Differences between treatment and SRP-only groups in the baseline-to-follow-up period typically favored treatment groups but usually only modestly (e.g., from about 0.1 mm to nearly 0.5 mm) even when the differences were statistically significant. Effects for CAL gains were smaller and statistical significance less common. The marginal improvements in PD and CAL were a fraction of the improvement from SRP alone.

CONCLUSIONS

Whether such improvements, even if statistically significant, are clinically meaningful remains a question. A substantial agenda of future research to address this and other issues (e.g., costs, patient-oriented outcomes) is suggested.

An in vitro model of ciprofloxacin and minocycline transport by oral epithelial cells

BACKGROUND

Fluoroquinolones and tetracyclines can penetrate epithelial cells, but the mechanism by which they cross the plasma membrane is unclear. In this study, a cell line derived from oral epithelium was used as a model to demonstrate a role for active transport.

METHODS

Transport of ciprofloxacin and minocycline by confluent cell monolayers was assayed by measuring the increase in cell-associated fluorescence.

RESULTS

Uptake of both agents was saturable and was inhibited at low temperatures. At 37 degrees C, the cells transported ciprofloxacin and minocycline with Km values of 351 and 133 microg/ml, respectively, and maximum velocities of 5.11 and 13.4 ng/min/microg cell protein, respectively. When ciprofloxacin and minocycline were removed from the extracellular medium, the intracellular levels of both agents decreased. Ciprofloxacin efflux from loaded cells occurred more rapidly than with minocycline. Cells accumulated intracellular drug levels that were at least 8-fold higher than extracellular levels for ciprofloxacin and at least 40-fold higher for minocycline. Transport of ciprofloxacin and minocycline was significantly influenced by pH and was most favorable at pH 7.7 and 7.2, respectively. While ciprofloxacin transport was Na+ independent, minocycline transport was strongly inhibited when sodium in the medium was replaced with choline. Transport of both agents was inhibited by a variety of organic cations, but the pattern of inhibition was different. Papaverine, phenylephrine, and doxycycline competitively inhibited minocycline transport, but inhibited ciprofloxacin transport by a non-competitive mechanism.

CONCLUSIONS

Epithelial cells take up ciprofloxacin and minocycline via different active transport systems. These transporters may play an important role in enhancing the effectiveness of these agents against invasive pathogens.

Induction of experimental periodontitis in mice with Porphyromonas gingivalis-adhered ligatures

BACKGROUND

Little information is available on the colonization of periodontopathic bacteria and alveolar bone loss in a mouse system, because of the difficulty in establishing bacteria in the oral cavity. The aim of this study was to establish experimental periodontitis in mice by applying a Porphyromonas gingivalis-adhered ligature onto the molars.

METHODS

Specific pathogen-free C3H/HeN mice were divided into 3 groups: 80 infected, 80 sham-infected, and 48 non-treated control mice. Sterile silk ligatures were preincubated with and without P. gingivalis 381 in vitro and then physically tied on the right maxillary first molar of infected and sham-infected mice, respectively. Ten mice from the infected and sham-infected groups and 6 from the control group were sacrificed at 2-week intervals for up to 15 weeks after infection.

RESULTS

Plaque samples were collected at the time of sacrifice and alveolar bone loss was examined. The results indicated that P. gingivalis was recovered from the plaque samples in 95% of the infected mice after 1 week and then gradually dropped to 58% after 15 weeks of infection, whereas P. gingivalis was not isolated in either sham-infected or control mice throughout the experimental period. The infected mice showed significant P. gingivalis-induced bone loss at the sites where the ligature was tied weeks 13 to 15. A linear regression analysis revealed a significant positive correlation between the number of P. gingivalis recovered and alveolar bone loss at 15 weeks after infection (P <0.01).

CONCLUSIONS

The use of a P. gingivalis-adhered ligature supported a long-lasting infection of P. gingivalis in mice, resulting in P. gingivalis-induced alveolar bone breakdown.

Merits of soft nitriding scalers

BACKGROUND

It has been demonstrated that nitriding modifies the physical characteristics of metals. The purpose of this study was to evaluate the changes induced by 3 levels of inexpensive soft nitriding treatments on commercial sickle scalers.

METHODS

Taglite scalers (NT) were soft nitrided for 30 (SN30), 60 (SN60), or 90 (SN90) minutes. The cumulated scaled material was weighed every 10 strokes x 10 and thereafter every 1,000 to 8,000 strokes by an automatic scaling apparatus against epoxy resin. Weight differences were used to indicate abrasion resistance; the relative efficiency (RE) was calculated as the ratio of scaled amount at a given number of strokes (SN/NT). The hardness and the tensile strengths were determined for each soft nitriding treatment level. The nitrided layer thickness of representative SN scalers was observed by electron probe x-ray microanalysis.

RESULTS

The SN60 was not significantly different from SN30 or SN90, but the SN90 was more efficient than SN30 for the first 100 strokes (P<0.01). The RE of all SN scalers was significantly greater (2.3 to 2.7 times) than the NT scalers from the beginning of the study and throughout all time periods (SN90 > SN60 > SN30); it increased further during the first 100 strokes (9.7 to 15.5 times), indicating the NT scalers wore out faster than SN scalers. The untreated scalers' performance decreased to 10% of baseline after 100 strokes; but even after 1,000 strokes, the SN60 and SN90 performed better than new untreated scalers. Thereafter, all scalers' performance, including SN scalers, decreased. While the NT blades ceased to cut measurable amounts after 7,000 to 8,000 strokes, all SN scalers continued to cut. Although SN90 scalers had the thickest soft layer and were the hardest (P<0.01), the SN60 had the highest tensile strength (P <0.01), suggesting that it might be the safest in practice.

CONCLUSIONS

Sixty minutes of soft nitriding treatment of commercially available taglite scalers seem to be the optimal treatment duration to increase their durability, on the order of 100 to 1,000 times, without jeopardizing safety for clinical use.

Subgingival controlled release of antimicrobial agents in the treatment of periodontal disease

Local drug delivery of antimicrobics by sustained release delivery systems can be used to treat periodontal disease. Advantages of these systems may include biodegradation of the system, maintaining high levels of antibiotic in the gingival crevicular fluid (GCF) for a sustained period of time and ease of use with high patient acceptance. This review will identify human in vivo clinical and microbiological studies. Sustained release formulations, application methods, clinical results and microbiological effects are discussed.

Clinical and microbiological effects of minocycline-loaded microcapsules in adult periodontitis

Clinical and microbiological effects of subgingival delivery of 10% minocycline-loaded (MC), bioabsorbable microcapsules were examined in 15 adult periodontitis patients. Patients received oral hygiene instruction 2 weeks prior to the study. At baseline (day 0) all teeth received supragingival scaling (SC); 2 quadrants received no further treatment and 1 quadrant received subgingival scaling and root planning (SRP). In the fourth quadrant, the tooth with the deepest probing sites (at least 1 site > or = 5 mm) was treated with minocycline microcapsules. The sites were evaluated at baseline and weeks 1, 2, 4, and 6. Clinical indices included bleeding on probing (BOP), probing depths (PD), and attachment loss (AL). Microbiological evaluations included percent morphotypes by phase-contrast microscopy; cultivable anaerobic, aerobic, and black-pigmented Bacteroides (BPB); and percent Porphyromonas gingivalis, Prevotella intermedia, Eikenella corrodens, and Actinomyces viscosus by indirect immunofluorescence. In the SC + MC group, BOP, PD, and AL were significantly reduced from baseline for weeks 1 to 6. BOP in the SC + MC group was significantly reduced compared to the SRP group from weeks 2 to 6. In the SC + MC group the percent of spirochetes and motile rods decreased and the percent of cocci increased after 1 week. The increased cocci and decreased motile rods were statistically greater at weeks 4 and 6 in the SC + MC group compared to the SRP group. This study demonstrates that local subgingival delivery of 10% minocycline-loaded microcapsules as an adjunct to scaling results in reduction in the percent sites bleeding on probing greater than scaling and root planning alone and induces a microbial response more favorable for periodontal health than scaling and root planing.

Subgingival delivery of therapeutic agents in the treatment of periodontal diseases

This article reviews the current status of controlled local delivery of antibacterial agents in the treatment of periodontitis. The principle of local intrapocket delivery of antibacterial agents and their delivery are discussed. The dosage forms include fibers, film/slabs, and injectable systems, some of which are degradable, while others are not and need to be removed at the termination of the treatment. The antibacterial agents used cover a range of antibiotics as well as antiseptics, and the composition of the delivery systems, their reported use, and the clinical results are summarized. The use of these systems in clinical practice is relatively recent, and therefore their application and integration into the dental office are not yet clearly defined. Clinical applications that have been tested are critically reviewed, and clinical situations in which controlled delivery of antibacterial agents may prove to be clinically useful are suggested for scientific evaluation.

Effects of a combination of an antibacterial agent (ofloxacin) and a collagenase inhibitor (FN-439) on the healing of rat periapical lesions

To investigate the effects of a combination of an antibacterial agent (ofloxacin) and a collagenase inhibitor (FN-439) in the root canal treatment of apical periodontitis, we studied the healing process of experimentally induced periapical lesions in rats by using immunohistochemical methods. With a topical application of a combination of ofloxacin and FN-439 following experimentally induced periapical lesions, both neutrophils and macrophages became significantly decreased in number, while active cementogenesis and extensive bone formation were seen in the periapical region. However, the use of ofloxacin alone also demonstrated a beneficial effect on periapical inflammation and healing. Therefore, it is suggested that ofloxacin is powerful against bacterial infection whether FN-439 is added. The only observed effect of a combination of ofloxacin and FN-439 is that it may more effectively inhibit osteoclastic bone resorption and activate the remodeling of the apical periodontal tissue if this combined medicament is used in a stage of active bone destruction characterized by high production of tissue collagenase.

Microbial flora in the acute phase of periodontitis and the effect of local administration of minocycline

Periodontitis, similar to other infectious diseases, is known to progress as chronic inflammation with recurrent acute phases. The purpose of this study was to clarify the microbiological composition of the acute phase and to compare the bacterial flora with that of comparable chronic periodontal pockets. We also evaluated the effect of application of minocycline gel locally on the change in the microflora in the acute pockets. Microbial flora from the subgingival pockets of 28 patients in the acute phase of periodontitis and of 12 patients in a comparable chronic phase as the control were investigated by various bacterial culture methods including TS blood agar and TSBV plates. Minocycline gel was applied to the acute periodontal pockets. Changes in the microbiological proportion and clinical parameters at one week after baseline examination were followed by dark-field analysis, culture method, and indirect immunofluorescence technique. Characteristic features of bacterial proportions in the acute site were observed as an increase in Bacteroides forsythus. The number of Porphyromonas gingivalis and black pigmented anaerobic rods also increased. Application of minocycline gel in the acute pocket without any debridement produced improvement in clinical symptoms at one week. Black-pigmented anaerobic rods, P. gingivalis, and B. forsythus decreased significantly at one week after the application. Results indicate that periodontopathic bacteria including B. forsythus and P. gingivalis were predominant in the acute phase of periodontitis and a locally delivered antibiotic may be effective as an alternative modality of treating the acute inflammation.

A newly-developed electrodeposited diamond scaler with high abrasive resistance

A diamond scaler on which blade diamond particles were coated by electrodeposition was developed to improve the abrasive resistance of scaler blades. The electrodeposited coating was tested with diamond particles of four different sizes, designated D-4000 with 2 to 4 microns diameter of the particles; D-800 with 12 to 25 microns; D-600 with 20 to 30 microns; and D-400 with 30 to 40 microns. The abrasive resistance of the scalers was examined quantitatively using a recently-developed automatic scaling apparatus that simulated the scaling process of hand instrumentation, as well as SEM observation of the blades. A series of abrasion tests suggested that all the diamond scalers except D-4000 showed better abrasive resistance than the control (D-0), and that D-600 showed the highest abrasive resistance and cutting quality. The SEM observation also suggested that D-600 and D-400 might have higher abrasive resistance. Furthermore, the profilometric evaluation of the surface roughness of the scaled natural dentin after hand instrumentation indicated that the average surface roughness increased in the order of D-4000, D-800, D-600, and D-400, although no marked differences were observed among D-4000, D-800, D-600 and D-0, but not D-400. These results suggested that the electrodeposited diamond scaler with 20 to 30 microns diamond particles (D-600) might have marked abrasive resistance as well as cutting quality without remarkable damage to the tooth surface after conventional scaling procedure.

Whole mouth microbiota effects following subgingival delivery of sanguinarium

An increased incidence of antibiotic-resistant bacteria and yeast overgrowth has been reported following various periodontal treatments. The objective of this study was to detect possible overgrowth of opportunistic bacteria and fungi as well as changes in normal microbiota after application of a biodegradable delivery system containing 5% sanguinarium (ABDS-S) to one quadrant in a split-mouth study. An oral hygiene quadrant served as a control. The ABDS-S treated and control periodontal sites as well as the saliva of 17 subjects were sampled prior to treatment, immediately after ABDS-S removal at 7 days, and again at 30 and 60 days. At Day 7 sanguinarium-resistant bacteria increased in both control and ABDS-S periodontal sites as well as in the saliva. Enteric Gram-negative bacilli in both control and ABDS-S periodontal sites were 2.2 to 3.4 log colony forming units higher at Day 7 compared to baseline. This overgrowth was transient in that levels became undetectable at Days 30 and 60. No such overgrowth was observed for C. albicans or other fungi, or for S. aureus or other staphylococci in any periodontal sites. Levels of Actinomyces increased at Days 30 and 60 in both control and ABDS-S sites as well as saliva. These changes strongly suggest that a 7 day ABDS-S treatment in one quadrant of the mouth led to significant microbiota changes in the treated and control quadrants as well as in the saliva. Future microbial studies involving antimicrobials delivered by local delivery systems must consider the crossover effects of treatment inherent in the split-mouth design.

Controlled-release local delivery antimicrobials in periodontics: prospects for the future

New knowledge about the microbial etiology of periodontal diseases emerged in the 1970s and 1980s and led to widespread interest in the use of antimicrobial agents to treat periodontitis. The controlled-release delivery of antimicrobials directly into the periodontal pocket has received great interest and appears to hold some promise in periodontal therapy. Some techniques for applying antimicrobials subgingivally, such as subgingival irrigation, involve local delivery but not controlled-release. Controlled-release local delivery systems, in which the antimicrobial is available at therapeutic levels for several days, have been evaluated in several forms and using different antimicrobials. Although most studies with such systems have focused on drug delivery kinetics and "proof of principle" evaluations, some controlled clinical trials have recently been reported. The most widely tested system, monolithic tetracycline-containing fibers, has shown significant clinical benefit when used alone as compared to no subgingival therapy. Similarly, controlled trials involving chlorhexidine strips used subgingivally every 3 months in place of routine supportive periodontal therapy have shown significant clinical benefit for up to 2 years. Although these data are now emerging, many questions concerning the optimal use and role of this therapy in clinical practice remain. This review attempts to summarize and interpret current data and to outline key remaining questions that must be addressed as this technology is transferred into clinical practice.

Concentration of metronidazole in periodontal pockets after application of a metronidazole 25% dental gel

The metronidazole concentration was monitored in gingival crevicular fluid (GCF) of inflamed periodontal pockets after 1 application of a 25% gel. 12 patients with periodontal disease were included in the study. Metronidazole gel was applied with a syringe into the pockets of 10 teeth with probing depths > or = 5 mm. Samples of GCF were taken with Periopaper before application and 4, 8, 12, 24 and 36 h after application. At each time, samples from 2 teeth were pooled in order to obtain a sufficient amount of fluid for analysis. By means of a calibrated Periotron, the collected volume of GCF was measured. High-performance liquid chromatography was used to determine the amount of metronidazole. MIC50 for anaerobic periopathogens susceptible to metronidazole is below 1 microgram/ml. In this study, the concentration obtained was higher than 1 microgram/ml in all samples after 4 and 8 h, in 92% after 12 h, in 50% after 24 h and in 8% after 36 h. Thus, metronidazole concentrations in the pockets were generally above MIC50 for susceptible periopathogens 24 h after 1 application of a 25% metronidazole gel.

The effect of topical metronidazole therapy on experimentally-induced periodontitis in the beagle dog

The present study was performed to assess the effect of topical metronidazole therapy on ligature-induced periodontitis in beagle dogs. 6 beagle dogs with experimentally-induced periodontitis on the mandibular 2nd, 3rd and 4th premolars were treated with metronidazole 10% dental paste 2 x daily for 4 weeks in an open placebo-controlled study using a split-mouth design. Recordings of probing pocket depth, bleeding on probing and gingival index were performed before commencement of treatment and repeated weekly during the 4-weeks treatment period. Concurrently, samples for microbiological analysis were collected from 2 of the dogs. The results demonstrated that probing pocket depth, bleeding on probing and gingival index had improved significantly in the metronidazole-treated side compared with the placebo-treated side. Black pigmented Bacteroides spp. and Spirochetes, present in all samples before treatment, were eliminated from the metronidazole-treated side after the 1st week of treatment and throughout the treatment period, whereas they were present in all samples from the placebo-treated side. The result of the present study demonstrates that topical application of metronidazole in a dental paste, improves the clinical features of the experimentally-induced periodontitis and eliminates some of the micro-organisms associated with the disease.

Systemic absorption of metronidazole after application of a metronidazole 25% dental gel

Systemic absorption of metronidazole was studied after one application of a metronidazole 25% dental gel into inflamed periodontal pockets. 14 patients with periodontal disease participated. Metronidazole gel was applied into the pockets of all teeth with probing depth > or = 5 mm, minimum 10 teeth/patient. Excess gel was carefully collected in order to calculate the amount of metronidazole applied into the pockets. Blood samples for analysis of metronidazole in plasma were taken before and up to 72 h after application. To determine the bioavailability of metronidazole administered as gel, the patients were later given an i.v. dose of 100 mg metronidazole. Metronidazole was quantified by HPLC. The mean actual dose of metronidazole in gel was 55 mg (SD: 24 mg, range: 29-103 mg). Allowing for the fact that excess gel corresponding to about 60% of the applied amount of metronidazole under normal clinical conditions may be swallowed, the systemic load after one application of metronidazole 25% dental gel will still be less than after one metronidazole 250 mg tablet. Peak plasma concentrations varied between 223 and 1303 ng/ml (mean: 581 ng/mk, SD: 320 ng/ml) and were reached within 2 to 8 h (mean: 4.4 h). The mean bioavailability of metronidazole dental gel was 71%.

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.

Impaired autologous mixed-lymphocyte reaction of peripheral blood lymphocytes in adult periodontitis

The autologous mixed-lymphocyte reactions (AMLR) of peripheral blood lymphocytes from 80 patients with adult periodontitis were examined. Some but not all patients showed clearly low AMLR responses; 31 of 80 subjects (39%) showing consistently low responses in AMLR (less than the mean--2 standard deviations of the healthy control group values) were designated low-AMLR patients, whereas the 42 patients (53%) who showed normal AMLR responses were designated normal-AMLR patients. However, there were no significant differences in the clinical parameters between these two groups of patients. The phenotypic analysis of T-cell fractions revealed a lower percentage of CD45RA-positive cells in CD4-positive cells (CD4+ CD45RA+ T cells) in the low-AMLR patients than those in normal-AMLR patients and healthy control subjects. No significant differences were demonstrated between the two groups in terms of the proportion of CD4-positive and CD8-positive cells in the T-cell fractions or in the expression of human leukocyte antigen DR of the monocytes and B cells in the non-T-cell fractions. In the low-AMLR patients, the allogeneic MLR was found to be normal, but the interleukin 2 production in the AMLR was found to be significantly depressed. The depressed AMLR responses and the lower percentage of CD4+ CD45RA+ T cells in the low-AMLR patients were found to be normalized following the periodontal therapy. These results might reflect changes in regulatory T-cell function induced by development of periodontal diseases.

Ofloxacin. A reappraisal of its antimicrobial activity, pharmacology and therapeutic use

Ofloxacin is a fluoroquinolone whose primary mechanism of action is inhibition of bacterial DNA gyrase. In vitro it has a broad spectrum of activity against aerobic Gram-negative and Gram-positive bacteria, although it is poorly active against anaerobes. Ofloxacin, unlike most other broad spectrum antibacterial drugs, can be administered orally as well as intravenously. Penetration into body tissues and fluids is highly efficient. Clinical trials with orally and intravenously administered ofloxacin have confirmed its potential for use in a wide range of infections, where it has generally proved as effective as standard treatments. Ofloxacin in well tolerated, and in comparison with other available fluoroquinolones is less likely to cause clinically relevant drug interactions. Ofloxacin thus offers a valuable oral treatment (with an option for intravenous administration if necessary) for use in a wide range of clinical infections, but with a particular advantage in more severe or chronic infections when recourse to parenteral broad spectrum agents would normally be required, thereby providing cost savings and additionally allowing outpatient treatment.