Monolithic tetracycline-containing fibers for controlled delivery to periodontal pockets

Insights into Intra Periodontal Pocket Pathogenesis, Treatment, In Vitro-In Vivo Models, Products and Patents, Challenges and Opportunity

Periodontal disease is a multifactorial pathogenic condition involving microbial infection, inflammation, and various systemic complications. Here, a systematic and comprehensive review discussing key-points such as the pros and cons of conventional methods, new advancements, challenges, patents and products, and future prospects is presented. A systematic review process was adopted here by using the following keywords: periodontal diseases, pathogenesis, models, patents, challenges, recent developments, and 3-D printing scaffolds. Search engines used were "google scholar", "web of science", "scopus", and "pubmed", along with textbooks published over the last few decades. A thorough study of the published data rendered an accurate and deep understanding of periodontal diseases, the gap of research so far, and future opportunities. Formulation scientists and doctors need to be interconnected for a better understanding of the disease to prescribe a quality product. Moreover, prime challenges (such as a lack of a vital testing model, scarcity of clinical and preclinical data, products allowing for high drug access to deeper tissue regions for prolonged residence, lack of an international monitoring body, lack of 4D or time controlled scaffolds, and lack of successful AI based tools) exist that must be addressed for designing new quality products. Generally, several products have been commercialized to treat periodontal diseases with certain limitations. Various strategic approaches have been attempted to target certain delivery regions, maximize residence time, improve efficacy, and reduce toxicity. Conclusively, the current review summarizes valuable information for researchers and healthcare professional to treat a wide range of periodontal diseases.

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.

Non-Isothermal Crystallization Kinetics of Poly (ɛ-Caprolactone) (PCL) and MgO Incorporated PCL Nanofibers

The study delves into the kinetics of non-isothermal crystallization of Poly (ɛ-caprolactone) (PCL) and MgO-incorporated PCL nanofibers with varying cooling rates. Differential Scanning Calorimetry (DSC-3) was used to acquire crystallization information and investigate the kinetics behavior of the two types of nanofibers under different cooling rates ranging from 0.5-5 K/min. The results show that the crystallization rate decreases at higher crystallization temperatures. Furthermore, the parameters of non-isothermal crystallization kinetics were investigated via several mathematical models, including Jeziorny and Mo's models. Mo's approach was suitable to describe the nanofibers' overall non-isothermal crystallization process. In addition, the Kissinger and Friedman methods were used to calculate the activation energy of bulk-PCL, PCL, and MgO-PCL nanofibers. The result showed that the activation energy of bulk-PCL was comparatively lower than that of nanofibers. The investigation of the kinetics of crystallization plays a crucial role in optimizing manufacturing processes and enhancing the overall performance of nanofibers.

Recent Biomedical Applications of Coupling Nanocomposite Polymeric Materials Reinforced with Variable Carbon Nanofillers

The hybridization between polymers and carbon materials is one of the most recent and crucial study areas which abstracted more concern from scientists in the past few years. Polymers could be classified into two classes according to the source materials synthetic and natural. Synthetic polymeric materials have been applied over a floppy zone of industrial fields including the field of biomedicine. Carbon nanomaterials including (fullerene, carbon nanotubes, and graphene) classified as one of the most significant sources of hybrid materials. Nanocarbons are improving significantly mechanical properties of polymers in nanocomposites in addition to physical and chemical properties of the new materials. In all varieties of proposed bio-nanocomposites, a considerable improvement in the microbiological performance of the materials has been explored. Various polymeric materials and carbon-course nanofillers were present, along with antibacterial, antifungal, and anticancer products. This review spots the light on the types of synthetic polymers-based carbon materials and presented state-of-art examples on their application in the area of biomedicine.

A Placebo-Controlled Trial to Evaluate Two Locally Delivered Antibiotic Gels (Piperacillin Plus Tazobactam vs. Doxycycline) in Stage III-IV Periodontitis Patients

Background and objectives: this study aims to evaluate the clinical and microbiological effects of a single subgingival administration of a locally delivered antibiotic gel containing piperacillin plus tazobactam and compare it with a slow-release doxycycline (14%) gel and a placebo gel, following subgingival instrumentation (SI) in patients with severe periodontitis. Materials and methods: sixty-four patients diagnosed with stage III-IV periodontitis were enrolled, were randomly assigned into three groups, and were treated additionally with a single subgingival administration of piperacillin plus tazobactam gel (group A); doxycycline gel (group B); and placebo gel (group C). The primary outcome variable was the change in mean probing pocket depth (PPD) 6 months after the intervention. Secondary outcome variables were changes in mean full-mouth bleeding score (FMBS); full-mouth plaque score (FMPS); overall bleeding index (BOP); pocket closure; and clinical attachment level (CAL), along with changes in the numbers of five keystone bacteria: Aggregatibacter actinomycetemcomitans (A.a.), Porphyromonas gingivalis (P.g.), Prevotella intermedia (P.i.), Tannerella forsythia (T.f.), and Treponema denticola (T.d.). Intergroup and intragroup differences were evaluated at 3 and 6 months. Results: at baseline, the three groups were comparable. An improvement in clinical parameters such as PPD, CAL, and BOP between groups was observed at 3 and 6 months, but without statistical significance (p > 0.05). At 6 months, the intragroup analysis showed a significant reduction in clinical parameters. Even though the piperacillin plus tazobactam group showed slightly higher PPD reduction, this was not statistically significant when compared to both control groups. Conclusions: The groups had similar results, and subgingival instrumentation can be executed without adjunctive antimicrobials, reducing the costs for the patient and the working time/load of the professional.

The effect of (-)-epigallocatechin gallate as an adjunct to non-surgical periodontal treatment: a randomized clinical trial

Background

EGCG is proven to be of good effect to relieve periodontal inflammation, but it has not been applied as a local delivery medicine in patients with periodontitis widely. The aim of this clinical trial was to evaluate the adjunctive effect of (-)-epigallocatechin gallate (EGCG) aqueous solution as a coolant during scaling and root planing in the management of chronic periodontitis.

Methods

A double-blind, randomized controlled study was performed on 15 patients with moderate to severe chronic periodontitis. The bilateral maxillary teeth were randomly divided into the test side and the control side on every individual. On the control side, the periodontal therapy was routinely performed. And on the test side, in the process of periodontal therapy, the distilled water in the ultrasonic scaler was replaced with a 5-mg/mL EGCG solution. The probing depth (PPD), clinical attachment level (CAL), bleeding index (BI), gingival index (GI), and plaque index (PI) were recorded at baseline and 6 and 12 weeks after the treatment.

Results

PPD, CAL, BI, GI, and PI generally improved after treatment in both groups. At the sixth week and the twelfth week of review, PPD, CAL, GI, and PI had no statistical difference (p >0.05) between the two groups. At the review of the twelfth week, BI on the test side decreased significantly (p <0.05).

Conclusions

Using EGCG solution as the irrigant instead of water has an additional benefit on the bleeding index at the 12-week review. However, the rest clinical parameters had no additional benefit.

Trial registration

ClinicalTrials.gov ChiCTR2000029831, date of registration: Feb 15, 2020.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13063-022-06298-6.

In vitro assessment of the antimicrobial activity of tetracycline hydrochloride diluted in three different vehicles against Porphyromonas gingivalis, Prevotella intermedia, and Fusobacterium nucleatum

Background:

The development and progression of periodontal diseases is a result of the dynamic interaction of microorganisms within their habitat, and changes in this habitat generate a dysbiotic state. Fusobacterium nucleatum and Prevotella intermedia are bridging microorganisms between the pioneer communities and other microorganisms responsible for periodontitis such as Porphyromonas gingivalis. Tetracycline hydrochloride (TTC-HCl) is commonly used as a coadjutant in periodontal treatment in the form of an antiseptic. However, there are no clear dilution or concentration protocols.

Objective:

This study aimed to evaluate the in vitro antimicrobial activity of TTC-HCl diluted in sterile water, saline solution, and 2% lidocaine with epinephrine 1:80,000 at concentration of 125, 250, and 500 mg, at three time points– 30, 60, and 120 s – on P. intermedia, F. nucleatum, and P. gingivalis using the Kelsey–Maurer technique.

Materials and Methods:

The antimicrobial activity of TTC-HCl was evaluated at the proposed concentrations and times, dissolved in the different vehicles at pH 1.9 and 7.0, on F. nucleatum, P. intermedia, and P. gingivalis. The Kelsey–Maurer test was used to verify the presence or absence of colony-forming units. Each test was performed in triplicates with its respective viability controls.

Results:

Inhibition of F. nucleatum, P. intermedia, and P. gingivalis was achieved with TTC-HCl at all concentrations, dissolved in distilled water, saline solution, and 2% lidocaine with epinephrine 1:80,000 for all times.

Conclusions:

The results show that TTC-HCl is a good antimicrobial alternative against F. nucleatum, P. intermedia, and P. gingivalis regardless of the vehicle in which it was dissolved, concentration, pH, or time used in this investigation.

Polysaccharide-Based Micro- and Nanosized Drug Delivery Systems for Potential Application in the Pediatric Dentistry

The intensive development of micro- and nanotechnologies in recent years has offered a wide horizon of new possibilities for drug delivery in dentistry. The use of polymeric drug carriers turned out to be a very successful technique for formulating micro- and nanoparticles with controlled or targeted drug release in the oral cavity. Such innovative strategies have the potential to provide an improved therapeutic approach to prevention and treatment of various oral diseases not only for adults, but also in the pediatric dental practice. Due to their biocompatibility, biotolerance and biodegradability, naturally occurring polysaccharides like chitosan, alginate, pectin, dextran, starch, etc., are among the most preferred materials for preparation of micro- and nano-devices for drug delivery, offering simple particle-forming characteristics and easily tunable properties of the formulated structures. Their low immunogenicity and low toxicity provide an advantage over most synthetic polymers for the development of pediatric formulations. This review is focused on micro- and nanoscale polysaccharide biomaterials as dental drug carriers, with an emphasis on their potential application in pediatric dentistry.

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.

Polymeric Carriers for Delivery Systems in the Treatment of Chronic Periodontal Disease

Periodontitis (PD) is a chronic inflammatory disease of periodontal tissues caused by pathogenic microorganisms and characterized by disruption of the tooth-supporting structures. Conventional drug administration pathways in periodontal disease treatment have many drawbacks such as poor biodistribution, low selectivity of the therapeutic effect, burst release of the drug, and damage to healthy cells. To overcome this limitation, controlled drug delivery systems have been developed as a potential method to address oral infectious disease ailments. The use of drug delivery devices proves to be an excellent auxiliary method in improving the quality and effectiveness in periodontitis treatment, which includes inaccessible periodontal pockets. This review explores the current state of knowledge regarding the applications of various polymer-based delivery systems such as hydrogels, liposomes, micro-, and nanoparticles in the treatment of chronic periodontal disease. Furthermore, to present a more comprehensive understanding of the difficulties concerning the treatment of PD, a brief description of the mechanism and development of the disease is outlined.

Development of in situ gel containing asiaticoside/cyclodextrin complexes. Evaluation in culture human periodontal ligament cells (HPLDCs)

Asiaticoside (AS), an active herbal compound isolated from Centella asiatica, has the potential benefit in promoting type I collagen (COL I) synthesis and osteogenic differentiation in human periodontal ligament cells (HPDLCs). However, it has low aqueous solubility which may hamper the bioavailability. Thus, the aim of this study was to develop thermoresponsive in situ gel containing AS/cyclodextrin (CD) complexes. The non-encapsulated formulations consisted of AS/hydroxypropyl β-CD (HPβCD) complexes and encapsulated formulations containing AS loaded sulfobutylether β-CD/chitosan nanoparticles (SBEβCD/CS NPs) were prepared. The appearance, pH and viscosity of all formulations were within the acceptable range. All formulations formed relatively rapid sol-to-gel transition when contacted with simulated salivary fluid at body temperature. Compared to non-encapsulated formulations, in vitro gelation and rheological studies of encapsulated formulations displayed gel formation that remained longer with high mechanical strength. In vitro mucoadhesion and in vitro release studies revealed that nanoencapsulated in situ gel had excellent mucoadhesive property and could release AS in a sustained manner. These formulations exhibited no cytotoxic effects to HPDCLs. The SBEβCD/CS NPs containing low AS content could express the COL I synthesis. Thus, nanoencapsulated platform could serve as a promising carrier to deliver AS for periodontal tissue regeneration.

Clinicomicrobiological evaluation of the efficacy of local delivery of moxifloxacin and ibuprofen gel as an adjunct to scaling and root planing in chronic periodontitis patients

Aims:

To evaluate the clinical and microbiological effects of local drug delivery of moxifloxacin and ibuprofen gel as an adjunct to conventional periodontal therapy in chronic periodontitis patients.

Subjects and Methods:

Twenty patients with moderate-to-severe chronic generalized periodontitis with probing pocket depth (PPD) of ≥5 mm and <8 mm were randomly assigned to one of the following two treatment modalities: scaling and root planing (SRP) group and moxifloxacin and ibuprofen combination gel as an adjunct to SRP group. Clinical parameters include plaque index (PI), gingival index (GI), probing depths and clinical attachment level (CAL) that were recorded at baseline and 1 and 3 months after the treatment, and microbiologic assessment was done using dark-field microscopy.

Results:

A statistically significant difference in mean PI and GI scores and reduction in PPD and gain in CAL were observed at different study intervals with greater difference in the test group. On microbiological examination, the percentage of cocci increased, while a statistically significant decrease in the mean percentage of bacilli and spirochetes was observed in both groups at given intervals. In-vitro dissolution showed controlled release of both the drugs.

Conclusions:

Among the two treatment modalities, treatment with moxifloxacin and ibuprofen local delivery as an adjunct to SRP gave superior results in clinical and microbiological parameters compared to SRP group.

Application of some nanoparticles in the field of veterinary medicine

Nanotechnology is a fast-growing technology that plays an important great impact on various fields of therapeutic applications. It is capable for solving several problems related to animal health and production. There are different nano-systems such as liposomes, metallic nanoparticles, polymeric micelles, polymeric nanospheres, functionalized fullerenes, carbon nanotubes, dendrimers, polymer-coated nanocrystals and nanoshells. In this review, we mentioned different methods for the preparation and characterization of nanoparticles. This review is concerned mainly on nanoparticle systems for antibiotic delivery which suffer from poor bioavailability and many side effects. Nanoparticles are characterized by many features include their minimal size, colossal surface zone to mass extent. The development of antimicrobials in nanoparticle systems is considered an excellent alternative delivery system for antimicrobials for the treatment of microbial diseases by increasing therapeutic effect and overcoming the side effects. In this paper, we reviewed some antimicrobial nanoparticle preparations and we focused on florfenicol and neomycin nanoparticle preparations as well as chitosan and silver nanoparticles preparations to prepare, characterize and compare their different pharmacological effects.

Local Drug Delivery Based Treatment Approaches for Effective Management of Periodontitis

Background:

Periodontal disease is an immuno-inflammatory condition of tissues that surround and hold the teeth. It is the disease which succeeds in all races, groups and both genders. Almost 10 to15% of the global population gets suffered from severe periodontitis as per WHO reports. Periodontal disease may likely cause other systemic diseases such as cardiovascular disease and pre-term low birth weight infants. Mechanical removal of plaques and calculus deposits from supra and subgingival environment is the backbone of periodontal treatment till date whereas complete elimination of these deleterious agents is quite unrealistic as the pocket depth increases.

Recent Approaches:

Recently controlled local drug delivery application is more encouraging in comparison to systemic approach as it mainly targets to enhance the therapeutic efficacy by maintaining site-specificity, avoiding first pass metabolism, reduction in gastrointestinal (GI) side effects and decreasing the dose. Several drugs such as antiseptics and antibiotics alongwith various carriers are being formulated as local drug delivery systems for effective management of the disease. Various local delivery systems reported are fibers, films, strips, compacts, injectables, microparticles, vesicular carriers, gels and nanoparticles. These local carriers provide effective prolonged treatment at the site of infection at reduced doses. This review enlightens detailed pathophysiology and various phases of periodontitis, challenges in treatment of disease and various antimicrobial agents (along with their marketed formulations) used. The main emphasis of the review is to cover all carrier systems developed so far for local delivery application in the effective management of periodontitis, as a patient compliant drug therapy.

Glutathione from recovered glucose as ingredient in antioxidant nanocapsules for triggered flavor delivery

Glucose recovered via enzymatic hydrolysis of rayon fibers was used for glutathione production by S. cerevisiae. Glutathione was used in combination with HSA and silk fibroin for ultrasound assisted nanocapsules production. Triggered release of flavor substances and antioxidant properties of the nanocapsules was demonstrated.

The effect of green tea as an adjunct to scaling and root planing in non-surgical periodontitis therapy: a systematic review

OBJECTIVE

To provide a systematic overview on the efficacy of green tea catechin as an adjunct to scaling and root planing (SRP) in terms of probing pocket depth (PPD).

MATERIALS AND METHODS

A systematic literature search was performed using electronic databases in PubMed, Scopus, Medline, Cochrane, CINAHL, and Web of Science on randomized clinical trials up to January 2017. The research question was posed in accordance with PRISMA guidelines.

RESULTS

The search provided 234 studies. After analyzing the full texts, five studies were included, with four studies qualifying for meta-analysis. Mean PPD reduction was significantly higher (α = 0.05) when green tea catechin was used as an adjunct to SRP (test group) than with SRP alone (control group). The difference in the reduction was 0.74 mm [0.35-1.13; 95% CI].

CONCLUSION

The local application of green tea catechin as an adjunct to SRP may result in a beneficial reduction in PPD. Due to the highly heterogeneous data and some risk of bias, however, this data still needs to be interpreted with caution.

CLINICAL RELEVANCE

The finding suggests that green tea catechin may be a topical adjunct to SRP without negative side effects.

Antimicrobial activity of NO-releasing compounds against periodontal pathogens

This study describes the successful synthesis of nitric oxide (NO)-releasing compounds with biodegradable and injectable properties and demonstrates that the kinetics of NO release vary according to the type of NO donor. The antimicrobial activity of NO-releasing compounds against three common periodontal pathogens, i.e., Aggregatibacter actinomycetemcomitans, Porphyromonas gingivalis, and Actinomyces israelii, was investigated using a susceptibility assay. Human gingival fibroblasts were treated with NO-releasing compounds at the minimum concentrations required for bacterial growth and cytotoxicity was evaluated using the MTT cell proliferation assay. Our results suggest that NO-releasing compounds can be used topically to treat both gram-negative and gram-positive periodontal pathogens. Comparison of the antimicrobial activity and cytotoxicity assay results between the NO-releasing compounds revealed that an NO donor comprising a macromolecule without surface charge, a lower instantaneous NO concentration, and an adequate supply of NO were associated with a strong bactericidal effect and low cytotoxicity. NO-releasing compounds with these properties may be suitable for treatment of periodontitis.

Tinidazole functionalized homogeneous electrospun chitosan/poly (ε-caprolactone) hybrid nanofiber membrane: Development, optimization and its clinical implications

We have prepared tinidazole (TNZ) functionalized biodegradable chitosan (CH)/poly (ε-caprolactone) (PCL) mucoadhesive hybrid nanofiber membrane (TNZ-PCHNF) to alleviate existing shortcomings in treatment of periodontitis. Box-Behnken design was employed for evaluating influence of formulation and processing variables on quality of final formulation. Optimized nanofiber membrane was subjected to solid-state and surface characterization studies using FTIR, DSC, XRD, SEM and AFM, which revealed that TNZ was entrapped in an amorphous form inside smooth and uniform cylindrical nanofibers without any physicochemical interaction with excipients. The optimized TNZ-PCHNF membrane had a diameter of 143.55±8.5nm and entrapment efficiency of 83.25±1.8%. In vitro drug release and antibacterial study demonstrated capability of the developed nanofiber membranes for efficiently delivering TNZ in a sustained manner up to 18days, and its ability to inhibit bacterial growth, respectively. Further, reduction of contact angle (from 123.4±2.5 to 27.4±2.3) revealed that blending of CH with PCL increases hydrophilicity of the nanofiber membrane. MTT assay and CLSM study suggested that nanofiber membrane was devoid of cytotoxicity on mouse fibroblasts. Moreover, preliminary clinical trials on patients proved therapeutic efficacy of the nanofiber membrane by eliciting a significant (p<0.05) decrease in clinical markers of periodontitis.

Periodontal Application of Manuka Honey: Antimicrobial and Demineralising Effects In Vitro

Background. Topical application of manuka honey is effective in the treatment of burns and soft-tissue infections. The aim of this study was to assess the antibacterial activity of manuka honey against plaque-associated bacteria in vitro in order to evaluate the potential application as an adjunct to periodontal treatment. Materials and Methods. The minimum bacteriostatic and bactericidal concentrations (MIC and MBC) of manuka honey were compared to those of white clover honey against a variety of plaque-associated bacteria, at the natural and neutral pH. Dissolved calcium was measured following incubation of honeys with hydroxyapatite (HA) beads to assess their potential to demineralise oral hard tissues. Results. Both honeys inhibited most tested oral bacteria at similar MIC/MBC, but Streptococcus mutans was comparatively resistant. The honeys at pH neutral had little effect on antimicrobial activity. Incubation of HA beads in honey solutions resulted in pH-dependent calcium dissolution, and inoculation with S. mutans promoted further demineralisation by both types of honey. Conclusion. Manuka honey is antimicrobial towards representative oral bacteria. However, the relative resistance of S. mutans in association with the high concentrations of fermentable carbohydrates in honey and the direct demineralising effect at natural pH mitigate against the application of honey as an adjunct in the treatment of periodontal disease.

Comparative evaluation of efficacy of three treatment modalities - tetracycline fibers, scaling and root planing, and combination therapy: A clinical study

Background

Tetracycline is one of the primary antibiotics prescribed for antimicrobial therapy in periodontics. It has a broad spectrum of activity being effective against most bacteria as well as spirochetes. Due to limitations of systemic drug therapy, recent formulations of the drug for local administration in the subgingival area have been introduced, including collagen fibers impregnated with tetracycline.

Aims and Objective

To compare the effectiveness of tetracycline fibers alone or in combination with scaling and root planing (SRP) on clinical parameters in chronic periodontitis patients.

Materials and Methods

A total of twenty patients comprising of both sexes in the age group of 35-60 years with chronic periodontitis were selected. Split-mouth design was used, and three teeth from each patient with periodontal pocket measuring > 5 mm were selected which were treated with different treatment modality. They were randomly divided into site A (SRP), site B (tetracycline fibers only), and site C (combination therapy). Clinical parameters of plaque index (PI), gingival index (GI), pocket probing depth, and clinical attachment level (CAL) were recorded at 0, 30, and 45 days. The data obtained was compiled and put to statistical analysis.

Results

All the three groups showed improvement in PI, GI, probing pocket depth, and CAL. Results of the study showed greater improvements in clinical parameters in Group C compared to Group A and Group B.

Conclusion

The results indicate that the adjunctive use of tetracycline fibers with SRP is a clinically effective and simple nonsurgical treatment method to improve periodontal health.

Non-surgical periodontal therapy: An update on current evidence

Periodontal disease is an inflammatory condition that involves a complex interaction between pathogenic bacteria, environmental and acquired factors and host related factors. Till recently periodontal treatment was directed primarily towards reduction of bacterial load by subgingival debridement of root surfaces and modification of environmental risk factors. The current paradigm of periodontal disease stresses greater role of host-mediated inflammatory response in tissue destruction characteristic of periodontal disease. Various therapeutic modalities have been developed adjuvant to mechanical periodontal therapy. The use of laser and photodynamic therapy show great promise but their effectiveness has still not been conclusively proven. Chemotherapeutic agents, either systemic and local antimicrobials or host modulating drugs, played pivotal role in better and more predictable management of periodontal disease. The present review focuses on the best available evidence, for the current management of the chronic periodontal patients, gathered from systematic reviews and meta-analysis of mechanical non surgical periodontal therapy (NSPT) (subgingival debridement, laser therapy and photodynamic therapy) and the adjunctive chemotherapeutic approaches such as systematic and local antibiotics and antiseptics, subgingival pocket irrigation and host modulation therapies. The review also attempts to briefly introduce future developments in some of these modalities. At the end, the review summarizes the analysis of the current evidence that suggests that thorough subgingival debridement remains the mainstay of NSPT and that adjunct use of chemotherapeutic agents may offer better management of clinical parameters in periodontitis patients.

Nanofibrous scaffolds in biomedical applications

Nanofibrous scaffolds are artificial extracellular matrices which provide natural environment for tissue formation. In comparison to other forms of scaffolds, the nanofibrous scaffolds promote cell adhesion, proliferation and differentiation more efficiently due to having high surface to volume ratio. Although scaffolds for tissue engineering have been fabricated by various techniques but electrospun nanofibrous scaffolds have shown great potential in the fields of tissue engineering and regeneration. This review highlights the applications and importance of electrospun nanofibrous scaffolds in various fields of biomedical applications ranging from drug delivery to wound healing. Attempts have also been made to highlights the advantages and disadvantages of nanofirbous scaffolds fabricated for biomedical applications using technique of electrospinning. The role of various factors controlling drug distribution in electrospun nanofibrous scaffolds is also discussed to increase the therapeutic efficiency of nanofibrous scaffolds in wound healing and drug delivery applications.

In situ forming implants for periodontitis treatment with improved adhesive properties

Novel in situ forming implants are presented showing a promising potential to overcome one of the major practical hurdles associated with local periodontitis treatment: limited adhesion to the surrounding tissue, resulting in accidental expulsion of at least parts of the implants from the patients' pockets. This leads to high uncertainties in the systems' residence times at the site of action and in the resulting drug exposure. In the present study, the addition of different types and amounts of plasticizers (acetyltributyl citrate and dibutyl sebacate) as well as of adhesive polymers (e.g., cellulose derivatives such as hydroxypropyl methylcellulose) is shown to allow for a significant increase in the stickiness of poly(lactic-co-glycolic acid)-based implants. The systems are formed in situ from N-methyl pyrrolidone-based liquid formulations. Importantly, at the same time, good plastic deformability of the implants can be provided and desired drug release patterns can be fine-tuned using several formulation tools. The antimicrobial activity of this new type of in situ forming implants, loaded with doxycycline hyclate, was demonstrated using the agar well diffusion method and multiple Streptococcus strains isolated from the oral microflora of patients suffering from periodontitis.

Prolonged delivery of ciprofloxacin and diclofenac sodium from a polymeric fibre device for the treatment of periodontal disease

In vitro analysis of drug release and antimicrobial activity of the coblended crosslinked polymeric fibre device (PFD) were investigated. The fibre loaded with ciprofloxacin and diclofenac sodium was comprised of alginate and glycerol crosslinked with barium cations. The pH dependent drug release was evident with ciprofloxacin and diclofenac sodium diffusing from the fibre at pH 4.0 compared to pH 6.8, where the fibre swelled and eroded resulting in zero-order drug release. Agar diffusion studies followed by minimum inhibitory assays were conducted to determine the antimicrobial activity of the device against Escherichia coli, Enterococcus faecalis, and Streptococcus mutans. The antimicrobial activity of the PFD was confirmed in both test assays against all test pathogens. The MIC ranges at pH 4.0 for E. coli, E. faecalis, and S. mutans were 0.5-0.8, 0.4-1.1, and 0.7-2.1 μg/mL, respectively. At pH 6.8, similar efficacies (0.3-0.5 μg/mL for E. coli and E. faecalis and 0.6-1.0 μg/mL for S. mutans) were observed. The effect of varying the plasticizer and crosslinking ion concentration on drug release profile of the fibers was further elucidated and conceptualized using molecular mechanics energy relationships (MMER) and by exploring the spatial disposition of geometrically minimized molecular conformations.

Kinetics of drug release from a biodegradable local drug delivery system and its effect on Porphyromonas gingivalis isolates: An in vitro study

BACKGROUND

Conventional anti-microbial therapy largely consisted of systemic administration of various drugs effective against periodontal pathogens, but fraught with several problems. Based on the concept of local drug delivery a bioresorbable device made of pure fibrillar collagen has been developed. The aim of this study was to study the release of Tetracycline from this collagen fiber (Type I collagen) impregnated with Tetracycline and its antibacterial activity against Porphyromonas gingivalis.

MATERIALS AND METHODS

Porphyromonas gingivalis was isolated from plaque samples of chronic periodontitis patients by using a CO2 incubator. DNA isolation was done followed by polymerase chain reaction (PCR) amplification to confirm the presence of bacteria. The release pattern of Tetracycline was assessed for a period of 10 days in water (group I) and Serum inoculated with Porphyromonas gingivalis (group II).

RESULTS

A significant presence of Tetracycline on all days in Group I and group II and the zone of inhibition was also present in both groups with a steady decline from day 1 to day 10.

CONCLUSION

Since the results were well within the therapeutic concentration of drug required to inhibit the growth of gram -ve bacteria (Porphyromonas gingivalis), this bioresorbable Tetracycline fiber has the potential for clinical application.

Modulation of the nano-tensile mechanical properties of co-blended amphiphilic alginate fibers as oradurable biomaterials for specialized biomedical application

The modulation of the mechanical properties of monolithic fibers by plasticizing and crosslinking enables the dynamic control of the nano-tensile forces, thereby obtaining optimized Young's modulus and ultimate strain for specialized application in the treatment of periodontal disease. In this work, drug-loaded crosslinked and plasticized alginate fibers (cl-PAFs) were prepared by extrusion-gelification with the aim of designing oradurable biomaterials for placement within the periodontal pocket and provide prolonged drug delivery. Mechanical properties of drug-free cl-PAFs were determined using a nanoTensile™ 5000 instrument and subsequently optimized versus the quantity of plasticizer and crosslinker as formulation variables employing a Box-Behnken experimental design strategy. Mechanically optimized fibers obtained (Young's Modulus=314.04 MPa, yield stress=5.80 MPa, ultimate strength=10.05 MPa, ultimate strain=0.29 MPa and toughness=2.39 J cm(-3)) were loaded with the model drugs ciprofloxacin and diclofenac both individually and simultaneously. The Young's modulus of cl-PAFs loaded with either drug individually exhibited a steep decline. However, in the case of cl-PAFs loaded with both drugs simultaneously, Young's modulus regained the original value which may be attributed to the cohesive energy density, porosity and space filling. The effect of various formulation variables on the drug entrapment and release characteristics of the alginate fibers was elucidated at pH 4.0 and pH 6.8. Furthermore, a previously established atomistic computational model based on energy refinements was employed to mechanistically describe the fiber performance. The effect of varying the plasticizer and crosslinking ion concentration on Young's modulus and ultimate strain of the linear elastic polymer matrix and the performance of the ciprofloxacin and/or diclofenac loaded optimized fiber was elucidated and conceptualized using molecular mechanics energy relationships (MMER) via the geometrical conformation and positioning of the molecular architectures.

Preparation of mucoadhesive oral patches containing tetracycline hydrochloride and carvacrol for treatment of local mouth bacterial infections and candidiasis

The specific aim of this work was to prepare mucoadhesive patches containing tetracycline hydrochloride and carvacrol in an attempt to develop a novel oral drug delivery system for the treatment of mouth infections. The bilayered patches were prepared using ethyl cellulose as a backing layer and carbopol 934 as a matrix mucoadhesive layer. Patches were prepared with different loading amounts of tetracycline hydrochloride and carvacrol. The antimicrobial activity was assessed for the prepared patches using the disc-diffusion method against the yeast Candida albicans and five bacterial strains, including Pseudomonas aeruginosa, Escherichia coli, Bacillus cereus, Staphylococcus aureus, and Bacillus bronchispti. In this work, we highlighted the possibility of occurrence of a synergistic action between carvacrol and tetracycline. The best formulation was selected based on microbiological tests, drug release, ex-vivo mucoadhesive performance, and swelling index. Physical characteristics of the selected formulations were determined. These included pH, patch thickness, weight uniformity, content uniformity, folding endurance, and patch stability.

Novel antibacterial nanofibrous PLLA scaffolds

In order to achieve high local bioactivity and low systemic side effects of antibiotics in the treatment of dental, periodontal and bone infections, a localized and temporally controlled delivery system is crucial. In this study, a three-dimensional (3-D) porous tissue engineering scaffold was developed with the ability to release antibiotics in a controlled fashion for long-term inhibition of bacterial growth. The highly soluble antibiotic drug, doxycycline (DOXY), was successfully incorporated into PLGA nanospheres using a modified water-in-oil-in-oil (w/o/o) emulsion method. The PLGA nanospheres (NS) were then incorporated into prefabricated nanofibrous PLLA scaffolds with a well interconnected macro-porous structure. The release kinetics of DOXY from four different PLGA NS formulations on a PLLA scaffold was investigated. DOXY could be released from the NS-scaffolds in a locally and temporally controlled manner. The DOXY release is controlled by DOXY diffusion out of the NS and is strongly dependent upon the physical and chemical properties of the PLGA. While PLGA50-6.5K, PLGA50-64K, and PLGA75-113K NS-scaffolds discharge DOXY rapidly with a high initial burst release, PLGA85-142K NS-scaffold can extend the release of DOXY to longer than 6weeks with a low initial burst release. Compared to NS alone, the NS incorporated on a 3-D scaffold had significantly reduced the initial burst release. In vitro antibacterial tests of PLGA85 NS-scaffold demonstrated its ability to inhibit common bacterial growth (S. aureus and E. coli) for a prolonged duration. The successful incorporation of DOXY onto 3-D scaffolds and its controlled release from scaffolds extends the usage of nano-fibrous scaffolds from the delivery of large molecules such as growth factors to the delivery of small hydrophilic drugs, allowing for a broader application and a more complex tissue engineering strategy.

Systemic detection of doxycycline after local administration

OBJECTIVES

Controlled release delivery (CRD) systems are used to extend the half-life of topical antibiotics in gingival crevicular fluid (GCF), while avoiding systemic contamination with antibiotics. When multiple periodontitis sites are treated by subgingival application of a one-component copolymer gel containing 14% doxycycline, it is likely that low levels of the antibiotic can be detected in blood by high performance liquid chromatography (HPLC).

METHODS

Twelve patients with severe periodontitis and one single defect per patient were treated with one single subgingival application of a new one-component doxycycline gel (14%) in each defect (the UNISITE group). Furthermore, 12 patients with between 3 and 9 periodontal defects were treated with a single application of the same doxycycline gel in each defect, resulting in 3-9 applications per patient (the MULTISITE group). Doxycycline was separated and quantitatively measured with HPLC using a UV detector.

RESULTS

In saliva, the maximum doxycycline concentration of the MULTISITE patients was nearly 10-fold higher than in the UNISITE group. In GCF specimens, maximum doxycycline concentrations were the same magnitude in both the MULTISITE and UNISITE groups. Only one UNISITE patient showed detectable levels of doxycycline in blood serum (maximum application: 0.18 µg/ml). Six MULTISITE patients exhibited measurable concentrations of doxycycline in their serum samples (maximum values: 0.12-0.76 µg/ml). The mean systemic concentration following application of the doxycycline-containing gel to multiple sites was as high as 160 ng/ml within minutes following application. Within approximately 1 h, this fell to levels below the limit of detection by HPLC (<50 ng/ml).

CONCLUSIONS

Systemic contamination with doxycycline after topical administration may occur even after unisite application if no periodontal dressing is used. Locally administered doxycycline can be identified in the systemic circulation at levels far below those expected to have antibacterial effects. Systemic concentration following application to a single site was always below levels capable of detection by HPLC.

Sustained antibacterial activity of doxycycline-loaded poly(D,L-lactide-co-glycolide) and poly(epsilon-caprolactone) nanoparticles

AIM

To increase the entrapment efficiency of doxycycline (DXY)-loaded poly(D,L-lactide-co-glycolide) (PLGA):poly(epsilon-caprolactone) (PCL) nanoparticles by up to 70% by varying the different formulation parameters such as polymer ratio, amount of drug loading (w/w), solvent selection, electrolyte addition and pH in the formulation.

METHOD

Biodegradable polymers PLGA and PCL are used in various ratios for nanoparticle preparation using the water-in-oil-in-water double emulsion technique for water-soluble DXY. The physicochemical characterization of nanoparticles included size and surface charge measurement, study of surface morphology using scanning-electron microscopy, Fourier transform infrared spectroscopy study, differential scanning calorimetry analysis and in vitro release kinetics study.

RESULTS

The mean particle size ranged from 230 to 360 nm, as measured by dynamic laser light scattering, and scanning-electron microscopy confirmed the spherical nature and smooth surface of the nanoparticles. Fourier transform infrared spectroscopy analysis of void nanoparticles, drug-loaded nanoparticles and native DXY indicated no interaction between the drug and polymer in the nanoparticle. Differential scanning calorimetry analysis of drug-loaded nanoparticles indicated a molecular level dispersion of DXY in the formulation. The antibacterial activity of native DXY and DXY-loaded nanoparticles were tested using a strain of Escherichia coli (DH5alpha) through growth inhibition and colony-counting method. The results indicated that DXY-loaded nanoparticles are more effective than native DXY due to the sustained release of DXY from nanoparticles in the E. coli strain.

Local Drug Delivery with Tetracycline Fiber : An Alternative to Surgical Periodontal Therapy

BACKGROUND

Scaling and root planing is the basic treatment modality for periodontal disease. Mechanical treatment is limited by physical impediments and biochemical considerations. Antimicrobial agents may be used as an adjunct to overcome limitations of mechanical therapy.

METHODS

A case-control study was carried out on 30 patients suffering from chronic periodontitis. In Group A only scaling and root planing was carried out whereas in Group B tetracycline fibers were used along with scaling and root planing.

RESULT

Tetracycline fibers as an adjunct to scaling and root planing was found to be more effective in reducing inflammation. The number of sites with bleeding on probing were 12 in Group A as compared to four in Group B after 30 days. The mean decrease in probing depth was more in Group B than Group A after 30 and 90 days. General linear model showed that decrease in probing depth was statistically significant with both mechanical therapy as well as adjunctive use of tetracycline fibers.

CONCLUSION

Local drug delivery with tetracycline fiber is an effective and simple non surgical method to improve periodontal health which can be practiced even by a general dental practitioner.

Metronidazole-loaded bioabsorbable films as local antibacterial treatment of infected periodontal pockets

BACKGROUND

Periodontal disease is infectious in nature and leads to an inflammatory response. It arises from the accumulation of subgingival bacterial plaque and leads to the loss of attachment, increased probing depth, and bone loss. It is one of the world's most prevalent chronic diseases. In this study we developed and studied metronidazole-loaded 50/50 poly(DL-lactide-co-glycolide) (PDLGA), 75/25 PDLGA, and poly(DL-lactic acid) (PDLLA) films. These films are designed to be inserted into the periodontal pocket and treat infections with controlled-release metronidazole for >or=1 month.

METHODS

The structured films were prepared using the solution-casting technique. Concentrated solutions and high solvent-evaporation rates were used to get most of the drug located in the bulk, i.e., in whole film's volume. The effects of copolymer composition and drug content on the release profile, cell growth, and bacterial inhibition were investigated.

RESULTS

The PDLLA and 75/25 PDLGA films generally exhibited a low- or medium-burst release followed by a moderate release at an approximately constant rate, whereas the 50/50 PDLGA films exhibited a biphasic release profile. The drug released from films loaded with 10% weight/weight metronidazole resulted in a significant decrease in bacterial viability within several days. When exposed to human gingival fibroblasts in cell culture conditions, these films maintained their normal fibroblastic features.

CONCLUSIONS

This study enabled the understanding of metronidazole-release kinetics from bioabsorbable polymeric films. The developed systems demonstrated good biocompatibility and the ability to inhibit Bacteroides fragilis growth; therefore, they may be useful in the treatment of periodontal diseases.

Biomaterial and antibiotic strategies for peri-implantitis: a review

Dental implants have 89% plus survival rates at 10-15 years, but peri-implantitis or dental implant infections may be as high as 14%. Peri-implantitis can limit clinical success and impose health and financial burdens to patients and health providers. The pathogenic species associated with periodontitis (e.g., Fusobacterium ssp, A. actinomycetemcomitans, P. gingivalis) are also associated with peri-implantitis. Incidence of peri-implantitis is highest within the first 12 months after implantation, and is higher in patients who smoke or have poor oral health as well as with calcium-phosphate-coated or surface-roughened implants. Biomaterial therapies using fibers, gels, and beads to deliver antibiotics have been used in the treatment of Peri-implantitis though clinical efficacy is not well documented. Guided tissue regeneration membranes (e.g., collagen, poly-lactic/glycolic acid, chitosan, ePTFE) loaded with antimicrobials have shown success in reosseointegrating infected implants in animal models but have not been proven in humans. Experimental approaches include the development of anti-bioadhesion coatings, coating surfaces with antimicrobial agents (e.g., vancomycin, Ag, Zn) or antimicrobial releasing coatings (e.g., calcium phosphate, polylactic acid, chitosan). Future strategies include the development of surfaces that become antibacterial in response to infection, and improvements in the permucosal seal. Research is still needed to identify strategies to prevent bacterial attachment and enhance normal cell/tissue attachment to implant surfaces.

Effects of alginate coated on PLGA microspheres for delivery tetracycline hydrochloride to periodontal pockets

The effects of alginate coated on tetracycline (Tc) loaded poly (D, L-lactic-co-glycolic acid) (PLGA) microspheres fabricated by double emulsion solvent evaporation technique for local delivery to periodontal pocket were investigated. Alginate coated PLGA microspheres showed smoother surface but enlarged their particle sizes compared with those of uncoated ones. In addition, alginate coated microspheres enhanced Tc encapsulation efficiency (E.E.) from 11.5 +/- 0.5% of uncoated ones to 17.9 +/- 0.5%. Moreover, all of the coated PLGA microspheres even fabricated at different conditions could prolong Tc release from 9-12 days with 50% or higher in cumulative release of Tc compared with those of uncoated ones. The swelling ratios of PLGA microspheres for alginate coated or uncoated ones, one of the possible mechanisms for enhancing Tc release for the coated ones, were measured. The results showed that 20% or higher in swelling ratio for the coated microspheres at the earlier stage of hydration (e.g. < or = 24 h) could be an important factor to result in high Tc release compared to the uncoated ones. In conclusion, alginate coated Tc loaded PLGA microspheres could enhance Tc delivery to periodontal pocket by enhancing drug encapsulated efficiency, released quantities and sustained release period compared with uncoated ones.

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.

Controlled release of an antibiotic, gentamicin sulphate, from gravity spun polycaprolactone fibers

The antibiotic, gentamicin sulphate (GS), was incorporated in gravity-spun polycaprolactone (PCL) fibers by spinning from particulate suspensions of the drug in PCL solution to produce a controlled delivery system. The production rate of GS-loaded PCL fibers was confined to the range 1-1.5 m/min and the fiber diameter to 170-220 microm. The kinetics of drug release could be adjusted by varying the GS loading of the fibers and the suspension preparation conditions. Gradual release of approximately 80% of the initial GS content was measured in phosphate buffered saline at 37 degrees C over 50 days from fibers spun from nonhomogenized suspensions, whereas loss of this amount of antibiotic occurred in less than 10 days from fibers spun from homogenized suspensions. Studies of growth inhibition of Stapyhlococcus epidermidis in culture indicated that GS released after 2 weeks from PCL fibers retained antibacterial activity. This behavior recommends further investigation of PCL fibers for local delivery of antibiotics to combat infection associated with periodontal disease, musculoskeletal injuries, and implantation of fiber-based tissue substitutes such as vascular prostheses.

Development and evaluation of novel biodegradable microspheres based on poly(d,l-lactide-co-glycolide) and poly(ε-caprolactone) for controlled delivery of doxycycline in the treatment of human periodontal pocket: In vitro and in vivo studies

This study reports on the development of novel biodegradable microspheres prepared by water-in-oil-water (W/O/W) double emulsion technique using the blends of poly(d,l-lactide-co-glycolide) (PLGA) and poly(epsilon-caprolactone) (PCL) in different ratios for the controlled delivery of doxycycline (DXY). Doxycycline encapsulation of up to 24% was achieved within the polymeric microspheres. Blend placebo microspheres, drug-loaded microspheres and pristine DXY were analyzed by Fourier transform infrared spectroscopy (FT-IR), which indicated no interaction between drug and polymers. Differential scanning calorimetry (DSC) on drug-loaded microspheres confirmed the polymorphism of DXY and indicated a molecular level dispersion of DXY in the microspheres. Scanning electron microscopy (SEM) confirmed the spherical nature and smooth surfaces of the microspheres produced. Mean particle size of the microspheres as measured by dynamic laser light scattering method ranged between 90 and 200 mum. In vitro release studies performed in 7.4 pH media indicated the release of DXY from 7 to 11 days, depending upon the blend ratio of the matrix. Up to 11 days, DXY concentrations in the gingival crevicular fluid were higher than the minimum inhibitory concentration of DXY against most of the periodontal pathogens. One of the developed formulations was subjected to in vivo efficacy studies in thirty sites of human periodontal pockets. Significant results were obtained with respect to both microbiological and clinical parameters up to 3 months even as compared to commercial DXY gel. Statistical analyses of the release data and in vivo results were performed using the analysis of variance (ANOVA) method.

Development of tetracycline-serratiopeptidase-containing periodontal gel: formulation and preliminary clinical study

The purpose of this research was to reduce the polymer concentration and to obtain reasonable viscosity at a lower concentration of pluronic by the addition of a viscosity modifier. A 20% wt/wt pluronic gel was prepared on a weight basis using the cold method. The effect of the amount of tetracycline and Aerosil on gel properties was studied. The gel was evaluated using different parameters: polarizing microscopy, gelation, gel melting, bioadhesivity, viscosity, drug release, and stability of enzyme. An in vivo study was performed to evaluate the clinical efficiency of the liquid crystalline gel. Addition of Aerosil to the gel favored hexagonal phase formation. Viscosity and bioadhesivity increased with an increase in the concentration of Aerosil. Release of tetracycline was sustained as the concentration of Aerosil increased. Various clinical parameters confirmed the acceptability and efficiency of this gel system.

Nonsurgical approaches for the treatment of periodontal diseases

This article reviews nonsurgical approaches for the management of periodontal diseases. A brief review of the pathogenesis of periodontitis allows the reader to identify the potential points of intervention. Assessment of risk factors for periodontitis and the potential for risk reduction are introduced as the first part of a three-pronged approach to therapy. Antimicrobial approaches, including the use of mechanical therapy, antiseptics, and antibiotics,are described next. Host modulatory therapy is addressed as the fi-nal component of the nonsurgical approach to periodontal therapy. Clinical applications of these nonsurgical options are presented as part of the treatment strategy.

Development of a system to adsorb drugs onto calcium phosphate materials

Several studies were carried out in order to reduce the systemic use of antibiotics due to the high concentration required to provide the minimum inhibitory concentration (MIC) at infected sites. The aim of this study was to develop a system of drug adsorption onto commercial hydroxyapatite (HA, Ca10(PO4)6(OH)2) and glass reinforced hydroxyapatite (GR-HA) granules. The drug will then be released for the local treatment of periodontitis. The antibiotics used in this study were metronidazole, a specific antibiotic indicated for the systemic treatment of periodontitis, and ampicillin, a wide spectrum antibiotic. UV spectroscopy was used to measure the amount of drug adsorbed onto HA and GR-HA granules. Results showed that metronidazole was unable to adsorb on the material's surface, as opposed to ampicillin which adsorbed both onto HA and GR-HA. Preliminary release kinetics studies were carried out using a flow through dissolution system. Results are discussed in terms of the influence of the different surface characteristics of the materials on the adsorption processes.

Tetracycline at Subcytotoxic Levels Inhibits Matrix Metalloproteinase-2 and -9 But Does Not Remove the Smear Layer

BACKGROUND

The antibacterial and anticollagenolytic properties of tetracycline (TCN) are valuable in periodontal therapy, and TCN treatment can remove the smear layer following root instrumentation. However, recent reports pointing to cytotoxic effects of several acids prompted this study to define TCN concentrations that are anticollagenolytic and remove the smear layer, but have low cytotoxicity.

METHODS

Human gingival (hGF) and periodontal ligament (hPDL) cells were treated short- (3 minutes) or long-term (24 hours) with TCN to determine concentrations yielding 50% (TD(50)) and 90% (TD(10)) cell survival. Activity assays measured TCN concentrations with half-maximal inhibition (IC(50)) of matrix metalloproteinase- 2 and -9 (MMP-2 and -9). Finally, we analyzed the effects of TCN with high (75 mg/ml) or low (1 mg/ml) cytotoxicity on the smear layer by scanning electron microscopy (SEM).

RESULTS

The TD(50) for TCN after short-term treatment was 4 mg/ml for both hGF and hPDL. Ninety percent of the cells survived 0.2 mg/ml. With long-term treatment, the TD(50) for hGF and hPDL was 70 and 30 microg/ml, respectively, and the TD(10) was 20 and 5 microg/ml. HGF and hPDL recovered from the 3-minute treatment with 1 mg/ml, but not from concentrations exceeding 3 and 9 mg/ml, respectively. The IC(50) was 25 microg/ml for both MMP-2 and MMP-9. Whereas 75 mg/ml TCN removed the smear layer, 1 mg/ml TCN had no effects.

CONCLUSIONS

Tetracycline has significant cytotoxicity on periodontal cells. Since non-cytotoxic concentrations of TCN inhibited MMP-2 and -9 but had no effects on the smear layer, TCN is not recommended for root surface treatment.