A comparative clinical study: the use of human type I collagen with and without the addition of metronidazole in the GTR method of treatment of periodontal disease

Antibiotic-Loaded Polymeric Barrier Membranes for Guided Bone/Tissue Regeneration: A Mini-Review

Polymeric membranes are frequently used for bone regeneration in oral and periodontal surgery. Polymers provide adequate mechanical properties (i.e., Young’s modulus) to support oral function and also pose some porosity with interconnectivity to permit for cell proliferation and migration. Bacterial contamination of the membrane is an event that may lead to infection at the bone site, hindering the clinical outcomes of the regeneration procedure. Therefore, polymeric membranes have been proposed as carriers for local antibiotic therapy. A literature search was performed for papers, including peer-reviewed publications. Among the different membranes, collagen is the most employed biomaterial. Collagen membranes and expanded polytetrafluoroethylene loaded with tetracyclines, and polycaprolactone with metronidazole are the combinations that have been assayed the most. Antibiotic liberation is produced in two phases. A first burst release is sometimes followed by a sustained liberation lasting from 7 to 28 days. All tested combinations of membranes and antibiotics provoke an antibacterial effect, but most of the time, they were measured against single bacteria cultures and usually non-specific pathogenic bacteria were employed, limiting the clinical relevance of the attained results. The majority of the studies on animal models state a beneficial effect of these antibiotic functionalized membranes, but human clinical assays are scarce and controversial.

Effect of locally delivered adjunctive antibiotics during surgical periodontal therapy: a systematic review and meta-analysis

Aim

The present study aimed to systematically assess current evidence on effects of locally delivered antibiotics during periodontal surgery compared to periodontal surgery alone on clinical attachment level (CAL) gain, probing pocket depth (PPD) reduction, recession depth (RD) changes, gingival index (GI), bleeding on probing (BOP), and plaque index (PI).

Methodology

MEDLINE-PubMed, Cochrane-CENTRAL and Scopus databases were searched up to April 2021 for randomized clinical trials (RCT), evaluating effects of locally delivered antibiotics during periodontal surgery. CAL gain served as primary, while PPD reduction, RD changes, GI and PI as secondary outcomes. The Cochrane Risk of Bias Tool was used to assess possible bias. Data were extracted, and meta-analysis was performed where appropriate.

Result

Screening of 2314 papers resulted in nine eligible studies. No adverse events were reported. Data on outcome variables were pooled and analyzed using generic inverse variance model and presented as weighted mean difference (WMD) and 95% confidence interval (95% CI). Statistically significant improvements in favor of antibiotics’ delivery were observed in studies with follow-up of ≤6 months for CAL gain (WMD = 0.61 mm (95% CI [0.07, 1.14]; p = 0.03), PPD reduction (WMD = 0.41 mm (95% CI [0.02, 0.80]; p = 0.04)) and BOP (WMD = −28.47% (95% CI [−33.00, −23.94]); p < 0.001), while for GI improvements were notable for >6 to 12 months (WMD = −0.27 (95% CI [−0.49, −0.06]; p = 0.01)).

Conclusion

Within the current review’s limitations, locally delivered antibiotics during surgical periodontal therapy results in post-surgical improvements for CAL, PPD, and BOP (≤6 months) with a longer-lasting GI improvement. Further randomized controlled trials are needed with true periodontal end-points to assess the ideal antibiotic agent, dosage, and delivery methods.

Clinical relevance

Local delivery of antibiotics during periodontal surgery improved clinical parameters for up to 6-month follow-up, with beneficial longer effects on gingival inflammation. Within the current study’s limitation, the presented evidence could support the elective usage of locally delivered antibiotics during surgical periodontal therapy.

Supplementary Information

The online version contains supplementary material available at 10.1007/s00784-021-04056-7.

In-vitro antibiofilm activity of chlorhexidine digluconate on polylactide-based and collagen-based membranes

Background

In Guided Tissue Regeneration (GTR), barrier membranes are used to allow selective cell populations to multiply and to promote periodontal regeneration. A frequent complication is membrane exposure to the oral cavity followed by bacterial colonization. The purpose of this in-vitro-study was to elucidate, if rinsing with a chlorhexidine digluconate solution (CHX) prevents bacterial adhesion, and whether it interferes with attachment of periodontal ligament (PDL) fibroblasts and epithelial cells to membrane surfaces.

Methods

Firstly, two bioresorbable membranes (polylactide-based and collagen-based) were dipped into 0.06% CHX and 0.12% CHX, before biofilms (2-species representing periodontal health, 6-species representing a periodontitis) were formed for 2 h and 8 h. Subsequently, colony forming units (cfu) were counted. Secondly, the membranes were treated with CHX and inoculated in bacteria suspension two-time per day for 3 d before cfu were determined. In additional series, the influence of CHX and bacterial lysates on attachment of epithelial cells and PDL fibroblasts was determined. Parameter-free tests were applied for statistical analysis.

Results

Cfu in “healthy” biofilms did not differ between the two membranes, more cfu were counted in “periodontitis” biofilm on collagen than on polylactide membranes. One-time dipping of membranes into CHX solutions did not markedly influence the cfu counts of both biofilms on polylactide membrane; those on collagen-based membrane were significantly reduced with being 0.12% CHX more active than 0.06% CHX. More-fold CHX dipping of membranes reduced concentration-dependent the cfu counts of both biofilms on both membranes. In general, the number of attached gingival epithelial cells and PDL fibroblasts was higher on collagen than on polylactide membrane. Lysates of the periodontopathogenic bacteria inhibited attachment of PDL fibroblasts to membranes. CHX decreased in a concentration-dependend manner the number of attached gingival epithelial cells and PDL fibroblasts.

Conclusions

The present in-vitro results appear to indicate that membranes in GTR should only be used when bacteria being associated with periodontal disease have been eliminated. An exposure of the membrane should be avoided. Rinsing with CHX may prevent or at least retard bacterial colonization on membrane exposed to the oral activity. However, a certain negative effect on wound healing cannot be excluded.

Antimicrobial Efficacy Assessment of Human Derived Composite Amnion-Chorion Membrane

Human derived composite amnion-chorion membrane (ACM) has been used to facilitate wound healing due to reported anti-inflammatory properties and promotion of cell proliferation. This study aimed to assess the antimicrobial properties of the ACM using novel methods to visualize the antimicrobial efficacy of membranes in situ at different time points. Porcine Pericardium Collagen Membranes (PPCM) served as membrane controls. Circular pieces of the membranes were used in three different assays: insert, agar contact and glass-bottom well assays. Streptococcus gordonii were spotted onto the membranes and the plates were subsequently centrifuged to ensure direct bacterial contact with the membranes in the insert and agar contact assays, thus better mimicking bacterial adherence in the oral cavity. After incubation at 37 °C for 8, 24, and 48 hours, the membranes were dyed with the Live/Dead BacLight Bacterial Viability fluorescence stain and analyzed via confocal microscopy. The results demonstrated that the ACM completely inhibited bacterial growth at all time points, whereas the PPCM did not demonstrate any antimicrobial properties. Within the limits of this study, the ACM showed extremely high antimicrobial efficacy against oral streptococci. In addition, our methods may be useful in assessing antimicrobial properties for biomaterials with minimum diffusion ability, when traditional assessment methods are not applicable.

Efficacy of Natural and Allopathic Antimicrobial Agents Incorporated onto Guided Tissue Regeneration Membrane Against Periodontal Pathogens: An in vitro Study

INTRODUCTION

Periodontal disease is one of the most prevalent afflictions worldwide. It is an infection of the periodontium as a result of subgingival colonization of the specific microbiota, leading to loss of attachment, which requires optimal care for regeneration to its pre-disease state. Guided Tissue Regeneration (GTR) is one of the successful treatment modalities in Periodontal Regenerative Therapy, but is vulnerable to bacterial colonization. The conflict between usage of classical antibiotics and plant origin antimicrobial agents has recently been in the limelight.

AIM

The aim of this study was to assess the in vitro antimicrobial activity of amoxicillin, metronidazole and green coffee extract loaded onto GTR membrane against periodonto-pathogens.

MATERIALS AND METHODS

Pure form of amoxicillin, metronidazole and green coffee extract were obtained. One percent concentration of each antimicrobial agent was prepared by appropriate dilution with distilled water. GTR membrane was cut into a size of 1x0.5 cm under sterile conditions and was coated with the antimicrobial agents respectively and with distilled water as the negative control. Antimicrobial activity was checked against Aggregatibacter actinomycetemcomitans (A. actinomycetemcomitans) and Porphyromonas gingivalis (P. gingivalis) using agar disc diffusion method. The statistical analysis was done using Kruskal Wallis ANOVA and Mann-Whitney U test.

RESULTS

One percent amoxicillin showed level of significance (p>0.05) against both A. actinomycetemcomitans and P. gingivalis. Green coffee extract showed no zone of inhibition against both the bacterial species.

CONCLUSION

Loading of commercially available antimicrobial agents onto GTR membrane can prevent its bacterial colonization leading to better treatment outcomes for periodontal regeneration.

Potential of Electrospun Nanofibers for Biomedical and Dental Applications

Electrospinning is a versatile technique that has gained popularity for various biomedical applications in recent years. Electrospinning is being used for fabricating nanofibers for various biomedical and dental applications such as tooth regeneration, wound healing and prevention of dental caries. Electrospun materials have the benefits of unique properties for instance, high surface area to volume ratio, enhanced cellular interactions, protein absorption to facilitate binding sites for cell receptors. Extensive research has been conducted to explore the potential of electrospun nanofibers for repair and regeneration of various dental and oral tissues including dental pulp, dentin, periodontal tissues, oral mucosa and skeletal tissues. However, there are a few limitations of electrospinning hindering the progress of these materials to practical or clinical applications. In terms of biomaterials aspects, the better understanding of controlled fabrication, properties and functioning of electrospun materials is required to overcome the limitations. More in vivo studies are definitely required to evaluate the biocompatibility of electrospun scaffolds. Furthermore, mechanical properties of such scaffolds should be enhanced so that they resist mechanical stresses during tissue regeneration applications. The objective of this article is to review the current progress of electrospun nanofibers for biomedical and dental applications. In addition, various aspects of electrospun materials in relation to potential dental applications have been discussed.

Comparison of the penetration and passage of Streptococcus mutans and Aggregatibacter actinomycetemcomitans through membranes loaded with tetracycline, amoxicillin, and chlorhexidine: an in vitro study

BACKGROUND

This study aimed at comparing the colonization and passage of Streptococcus mutans and Aggregatibacter actinomycetemcomitans (Aa) through polytetrafluoroethylene (PTFE) and acellular dermal matrix (ADM) membranes loaded with tetracycline, amoxicillin, and chlorhexidine.

METHODS

In this in vitro study, PTFE and ADM membranes were loaded with tetracycline, amoxicillin, and chlorhexidine. The colonization and crossing of S. mutans and Aa through these membranes were evaluated using vials containing culture medium. Three-way analysis of variance and Tukey's honestly significant difference test were used for the statistical analyses (p<0.05).

RESULTS

The membranes loaded with antimicrobial agents significantly decreased bacterial passage compared with the control membranes (not loaded with antimicrobial agents). Significant differences were also detected between membranes in their inhibitory properties (p=0.011). PTFE membrane had higher barrier effect than ADM. Tetracycline had greater antibacterial activity against both species compared with amoxicillin (p=0.021) but had no significant difference with chlorhexidine in this respect (p=0.068). The antimicrobial efficacy of chlorhexidine was in between those of tetracycline and amoxicillin, but the difference between amoxicillin and chlorhexidine in this respect was not statistically significant (p=0.992). Aa had better penetration into the membranes compared with S. mutans.

CONCLUSIONS

The study results demonstrated that the penetration of S. mutans and Aa decreased into the membranes loaded with tetracycline, amoxicillin, and chlorhexidine and PTFE membrane had a greater barrier effect than ADM. Loading membranes with antimicrobial agents can effectively reduce membrane-associated infections during regenerative procedures.

Bacterial adhesion to antibiotic-loaded guided tissue regeneration membranes - a scanning electron microscopy study

BACKGROUND/PURPOSE

Bacterial contamination of sites undergoing guided tissue regeneration (GTR) therapy may reduce the efficiency of periodontal regeneration. This study compared bacterial adhesion onto various GTR membranes incorporated with antibiotics.

METHODS

Three barrier membranes, including expanded polytetrafluoroethylene (ePTFE) membrane, collagen membrane, and glycolide fiber membrane, were loaded with tetracycline or amoxicillin. The adhesion of Streptococcus mutans and Aggregatibacter actinomycetemcomitans onto the GTR membranes with or without antibiotics was analyzed using the scanning electron microscopy (SEM) analysis.

RESULTS

The SEM analysis showed no apparent alteration in the physical structure of the membranes loaded with antibiotics. Both S. mutans and A. actinomycetemcomitans attached best on the collagen membranes, followed by the ePTFE membranes, and then the glycolide fiber membranes without antibiotics. Moreover, higher numbers of bacteria were observed on the fibril areas than on the laminar areas of the ePTFE membranes. The amounts of attached bacteria on the GTR membranes increased after longer incubation. Incorporation of tetracycline or amoxicillin greatly reduced the adhesion of S. mutans and A. actinomycetemcomitans onto all of the GTR membranes examined.

CONCLUSION

Incorporation of tetracycline or amoxicillin greatly reduced adhesion of S. mutans or A. actinomycetemcomitans on the ePTFE, glycolide fiber, or collagen membranes. This finding indicates that it is valuable and effective to use the antibiotic-loaded GTR membranes for periodontal regeneration therapy.

Bacterial penetration through antibiotic-loaded guided tissue regeneration membranes

BACKGROUND

This study compared bacterial penetration through guided tissue regeneration (GTR) membranes impregnated with antibiotics.

METHODS

Three barrier membranes, expanded polytetrafluoroethylene (ePTFE) membrane, collagen membrane, and glycolide fiber composite membrane, were loaded with amoxicillin or tetracycline. The penetration of Streptococcus mutans and Aggregatibacter actinomycetemcomitans (previously Actinobacillus actinomycetemcomitans) through the GTR membranes was achieved using a device consisting of an inner tube and an outer bottle filled with culture media.

RESULTS

The penetration of S. mutans or A. actinomycetemcomitans into the inner tubes significantly decreased with all of the antibiotic-loaded membranes compared to membranes without antibiotics. However, differences were found in the behavior of the three membranes. The antibiotic-loaded ePTFE membranes showed the best barrier effect. Moreover, the inhibitory effect of tetracycline on S. mutans was greater than that of amoxicillin for all GTR membranes. Furthermore, the inhibitory effect of tetracycline on A. actinomycetemcomitans was lower than that of amoxicillin with the glycolide fiber membrane.

CONCLUSIONS

The results showed that penetration of S. mutans and A. actinomycetemcomitans through amoxicillin- or tetracycline-loaded ePTFE membrane, glycolide fiber membrane, and collagen membrane was delayed and/or reduced. Thus, incorporation of an antibiotic into the membrane may be of value when controlling membrane-associated infection during GTR therapy.

Improved drug delivery properties of PVDF membranes functionalized with β-cyclodextrin—Application to guided tissue regeneration in periodontology

The purpose of this study was to develop a membrane for guided tissue regeneration applicable in periodontology that could release antimicrobial agent during the healing period. Our strategy consisted to graft beta-cyclodextrin (beta-CD), a molecule that is known to form inclusion complexes with a large variety of drugs, onto PVDF membranes. Grafting occurred by using citric acid that provoked a crosslinking reaction of beta-CD, and the resulting polymer was imprisoned into the porous structure of the PVDF membrane. The reaction produced a weight increase of the membrane, the range of which depended on the temperature and on the time of curing applied in the process. The biological behavior of the membranes evaluated by proliferation and vitality tests showed good proliferation and improved activity of L132 epithelial cells on the raw and on the grafted membranes. Doxycyclin (DOX) and chlorhexidine (CHX) were used as antimicrobial agents. Their inclusion into the beta-CD cavity in aqueous solutions was confirmed by NMR spectroscopy. After the impregnation of the membranes with DOX and CHX, their release was studied in vitro in batch type experiments and measured by UV spectrophotometry. Low amounts of DOX and CHX were delivered from the raw membranes within the first few hours of tests. Grafted membranes, however, delivered DOX and CHX in larger quantities within 24 h and 10 days respectively.

A collagen-phosphophoryn sponge as a scaffold for bone tissue engineering

Non-collagenous phosphoproteins that interact with a type-I collagen are thought to nucleate bone mineral into collagen networks of mineralized tissues. Previously, phosphophoryn cross-linked to type-I collagen was reported to be an effective nucleator of appatite. However, free phosphophoryn molecules inhibit the formation of apatite in vitro. On the basis of the above study, we expected a collagen-phosphophoryn sponge to be a good scaffold for bone-tissue engineering and examined the formation of bone in orthotopically transplanted composites of the sponge and bone marrow osteoblasts in vivo in Fischer rats. Osteoblastic primary cells were obtained from the bone shaft of femorae of Fisher rats, according to the method of Maniatopoulous et al. A suspension of marrow cells was distributed through a flask with standard culture medium and incubated at 37 degrees C. When cultures were nearly confluent after 10 days, they were concentrated by centrifugation to 10(6) cells/ml and subcultured onto the synthesized collagen-phosphophoryn sponge and a collagen sponge (control). After 14 days, the composites of collagen-phosphophoryn and osteoblastic cells as well as control composites were transplanted into bone-defect sites of Fisher rats (holes 2 mm in diameter) and then the wounds were sutured. The composites were harvested at 1-8 weeks after implantation, and stained with hematoxylin and eosin. It was found that more bone was formed in the composites of collagen-phosphophoryn sponge and osteoblasts than control composites from 1 week to 8 weeks, suggesting that the collagen-phosphophoryn sponge is a good candidate as a scaffold for bone-tissue engineering.

Guided Tissue Regeneration for the Treatment of Periodontal Intrabony and Furcation Defects.A Systematic Review

BACKGROUND

Many clinical studies have demonstrated that guided tissue regeneration (GTR) is a successful treatment modality of periodontal reconstructive surgery and it has become an accepted procedure in most periodontal practices.

RATIONALE

The purpose of this structured review was to assess the efficacy of guided tissue regeneration (GTR) procedures in patients with periodontal osseous defects compared with surgical controls on clinical, radiographic, adverse, and patient-centered outcomes. It extends the scope of previous GTR systematic reviews, which were limited to randomized controlled studies, by the scope of outcome measures examined, and the duration of the study.

FOCUSED QUESTION

In patients with periodontal osseous defects, what is the effect of physical barriers compared with surgical controls on clinical, radiographic, adverse, and patient-centered outcomes?

SEARCH PROTOCOL

An electronic search of the Cochrane Oral Health Group Trials Register and MEDLINE databases was performed. Manual searching of journals included Journal of Clinical Periodontology, Journal of Periodontology, and Journal of Periodontal Research up to January 2002. This manual search also included review of relevant bibliographies. Two manufacturers of GTR devices were contacted regarding unpublished data.

SELECTION CRITERIA

INCLUSION CRITERIA

Studies were selected for review if the evidence level was 3B (cohort) or above, at least 6 months duration, and compared a test GTR intervention with a surgical control.

EXCLUSION CRITERIA

Studies with experimental design problems; histologic or microbiological investigations; or those with outcome measurements, study populations, or study duration not consistent with the inclusion criteria were excluded. Primary outcome measures for intrabony defects were: clinical attachment level (CAL) gain, probing depth reduction (PD), gingival recession (REC) reduction; for furcation defects: vertical probing attachment level (VPAL) gain, vertical probing depth reduction (VPD), horizontal probing depth reduction (HPD), horizontal open probing attachment level gain (HOPA), and vertical open probing attachment level gain (VOPA). Meta-analysis was performed to compare GTR procedures to other surgical treatments and to examine the resulting clinical outcomes.

MAIN RESULTS

1. For the primary outcome variables, in both intrabony-defect and furcation-defect studies, GTR was favored over open flap debridement (OFD) therapies (P < 0.0001). 2. No differences were detected among barrier types, but barrier types could explain some heterogeneity in the results. 3. Augmentation of the GTR barrier with a particulate graft enhanced VPD (P < 0.05), VPAL, and HOPA, but none of the intrabony outcomes.

REVIEWER'S CONCLUSIONS

Overall, GTR is consistently more effective than OFD in the gain of clinical attachment and probing depth reduction in the treatment of intrabony and furcation defects.

Attachment of Periodontal Ligament Cells to Chlorhexidine-Loaded Guided Tissue Regeneration Membranes

BACKGROUND

Early exposure of a guided tissue regeneration (GTR) membrane in the oral cavity results in bacterial contamination, which may lead to failure or incomplete regeneration. Incorporation of antimicrobial agents in GTR membranes may be valuable to control membrane-associated infection during GTR therapy. The purpose of this study was to evaluate whether the incorporation of chlorhexidine into various GTR membranes improves the attachment of periodontal ligament cells in the presence of Actinobacillus actinomycetemcomitans.

METHODS

The possible effects of chlorhexidine on the viability of primary human periodontal ligament (PDL) cells were determined using 3-[4,5-dimethylthiazol-2-yl]-2,5 diphenyltetrazolium bromide (MTT), which measures cellular metabolic activity. An expanded polytetrafluoroethylene (ePTFE) membrane, glycolide fiber membrane, and collagen membrane were loaded with chlorhexidine and characterized. Attachment of PDL cells to the chlorhexidine-loaded membranes with or without A. actinomycetemcomitans was examined using scanning electron microscopy (SEM) analysis.

RESULTS

Relative cellular viability of PDL cells was reduced to approximately 50% when 15 microg/ml (0.0015%) of chlorhexidine was used. Chlorhexidine released from the coated GTR membranes inhibited the growth of A. actinomycetemcomitans. At the concentration used in this study, chlorhexidine incorporated into the GTR membranes did not interfere with the attachment of PDL cells. The inhibitory effects of A. actinomycetemcomitans on cellular attachment were reduced using chlorhexidine-loaded membranes, including ePTFE, glycolide fiber, and collagen membranes.

CONCLUSIONS

These results suggest that incorporation of chlorhexidine into GTR membranes is beneficial in reducing bacterial effects on cellular attachment. The future application of chlorhexidine-loaded membranes during GTR therapy may be of value.

Guided tissue regeneration in smokers: effect of aggressive anti-infective therapy in Class II furcation defects

BACKGROUND

Guided tissue regeneration (GTR) using membrane barriers is still the reconstructive treatment of choice for a variety of periodontal defects. Smokers, however, present a reduced regenerative response to GTR. The purpose of the present study was to design and examine a new protocol with emphasis on anti-infective therapy for patients who are cigarette smokers and who require GTR procedures for the treatment of Class II furcation defects.

METHODS

Chronic periodontitis patients who were smokers and who exhibited mandibular Class II furcations were initially pooled for further assessment. Patients were randomly assigned to either the experimental group (EG) or a control group (CG). Clinical measurements and indices were recorded at baseline and at 6, 9, and 12 months, and included: plaque assessment index; gingival assessment index; probing depth; and probing attachment level (vertical [PAL-V] and horizontal [PAL-H]) using a prefabricated acrylic stent as a reproducible reference point. All patients underwent hygienic phase periodontal therapy. Next, GTR was performed, and the furcation dimensions (height, width, and depth) were measured. A membrane was placed, and a 25% metronidazole gel was then applied over the outer surface of the membrane (EG only) and the flaps repositioned so that the membrane was completely submerged. Instructions included twice daily rinses with chlorhexidine gluconate 0.2% for 1 week (CG) or as long as the membrane was in place (EG), doxycycline 100 mg x 1/day for 1 week (CG) or 6 to 8 weeks (EG), and ibuprofen 3 x 400 mg/day for 7 days. Patients were initially seen for prophylaxis weekly (EG) or biweekly (CG). Metronidazole was applied to the free gingival margins and/or over the exposed membrane at every prophylactic visit (EG). Six to 8 weeks after surgery, the membrane was removed surgically, and the amount of new tissue growth (NTG) from the cemento-enamel junction (CEJ) to the most coronal extension of the new tissue was recorded. Following membrane retrieval, patients were seen for prophylaxis and oral hygiene reinforcement every month (EG) or quarterly (CG). At 12 months postoperatively, the area was surgically reentered and the surgical measurements repeated.

RESULTS

Thirty-eight subjects, 21 females and 17 males, aged 35 to 61 were accepted in this study. Baseline clinical parameters were similar for both groups. One year postoperatively, there was no statistically significant difference in probing depth reduction or in horizontal PAL between EG and CG, but vertical PAL gain was significantly greater in EG. As for alveolar parameters 1 year postoperatively, the mid CEJ-crest distance and furcation width decreased in EG but increased in CG. A similar trend was observed for furcation height. Furcation depth reduction in both groups was similar. A comparison between new tissue growth at retrieval and eventual bone formation 1 year postoperatively demonstrated a smaller change in EG patients compared to CG patients, which was statistically significant for both the distal and the mid-tooth area, as well as for the tooth mean.

CONCLUSIONS

While smoking prevented tissue maturation and mineralization, the anti-infective protocol enhanced these processes, resulting in a more favorable outcome. It is therefore suggested that when GTR is performed for Class II furcation defects in smokers, anti-infective therapy should be incorporated into the treatment protocol to enhance the regenerative outcome in these patients.

Effect of polylactide/glycolide (PLGA) membranes loaded with metronidazole on periodontal regeneration following guided tissue regeneration in dogs

BACKGROUND

Bioabsorbable membranes have been successfully used for guided tissue regeneration (GTR) and local delivery systems because they are biocompatible and do not require second surgery for removal. Several studies have demonstrated that metronidazole, when applied topically, produced immediate effects on microbiological and clinical parameters, most notably a reduction in probing depth and loss of attachment. The purpose of this study was to evaluate the regenerative potential of a metronidazole-loaded biodegradable (polylactide/glycolide) (PLGA) GTR membrane in dogs.

METHODS

Six male adult dogs with 36 created osseous defects were enrolled. Bilateral dehiscence type defects in 5 mm diameter were created at buccal aspect of the alveolar bone in maxillary premolar teeth. After full thickness flap elevation, exposed root surfaces were thoroughly planed. In the experimental sites, PLGA membranes with or without metronidazole were fitted and placed over the defects. On the control defects only root planing was performed. Gingival flaps were replaced slightly coronal to the cemento-enamel junction. Animals were sacrificed at 60 days. The histometric analysis was evaluated with the following parameters: defect height (DH), apical extension of junctional epithelium (AEJE), new cementum height (NCH), new bone height (NBH), and new gingival connective tissue height (NCTH).

RESULTS

Postoperative clinical healing was similar in the 3 groups. There were no statistically significant differences between the 2 experimental groups in any parameters. Statistically significant differences were observed for AEJE, NCH, NBH, and NCTH in experimental groups when compared with the controls. Statistically significantly greater NCH, NBH, and NCTH were seen in the experimental groups than the controls and control defects showed longer AEJE than the experimental defects.

CONCLUSIONS

These results suggest that PLGA membranes with and without metronidazole may have a beneficial effect on periodontal regeneration.

Effect of repeated local minocycline administration on periodontal healing following guided tissue regeneration

BACKGROUND

Infection after a periodontal surgical site has been prepared for guided tissue regeneration (GTR) is one of the common complications that can compromise healing. The purpose of this study was to assess the effect of repeated local antimicrobial therapy following GTR for improving clinical attachment gains, and to histologically evaluate the various cell populations and bacterial contamination of the retrieved expanded polytetrafluoroethylene membrane (ePTFE).

METHODS

Forty periodontal intrabony defects in 40 patients were treated by a flap procedure that included the use of ePTFE membranes to allow GTR. Patients were randomly assigned to 2 treatment groups: 20 patients were treated with the ePTFE alone (control group), and the other 20 were treated with the ePTFE combined with the administration of a weekly repeated local application of minocycline ointment for 8 weeks after membrane placement (test group). The membranes were retrieved 6 weeks after the initial surgery and sectioned serially in a coronal-apical plane. The sections were then divided into 9 fields and examined by light microscopy for the presence of inflammatory cells and oral bacteria. Clinical measurements were taken at the time of baseline examination and at a 6-month follow-up examination after removal of the ePTFE.

RESULTS

At the 6-month follow-up examination, control and test groups showed significant improvement; i.e., reduction in the probing depth and increased clinical attachment gain compared with the values at the baseline examination. However, the mean clinical attachment gain of the test group (3.0+/-0.3 mm) was significantly (P = 0.03) greater than that of the control group (2.0+/-0.5 mm). Histologically, the total number of the cells of both groups was similar. In both groups, mononuclear cells were dominant and fibroblasts, neutrophils, and plasma cells were rarely encountered. There was a tendency for the number of macrophages to be somewhat higher in the control group. The total number of bacteria in the test group was significantly less than that in the control group. The number of bacteria in both control and test groups decreased toward the apical portion.

CONCLUSIONS

In the present study, clinical attachment gain of intrabony defects following GTR was favorable with repeated local administration of minocycline ointment. However, a complete microbial eradication was not achieved.

Collagen membranes: a review

Collagen materials have been utilized in medicine and dentistry because of their proven biocompatability and capability of promoting wound healing. For guided tissue regeneration (GTR) procedures, collagen membranes have been shown to be comparable to non-absorbable membranes with regard to probing depth reduction, clinical attachment gain, and percent of bone fill. Although these membranes are absorbable, collagen membranes have been demonstrated to prevent epithelial down-growth along the root surfaces during the early phase of wound healing. The use of grafting material in combination with collagen membranes seems to improve clinical outcomes for furcation, but not intrabony, defects when compared to the use of membranes alone. Recently, collagen materials have also been applied in guided bone regeneration (GBR) and root coverage procedures with comparable success rates to non-absorbable expanded polytetrafluoroethylene (ePTFE) membranes and conventional subepithelial connective tissue grafts, respectively. Long-term clinical trials are still needed to further evaluate the benefits of collagen membranes in periodontal and peri-implant defects. This article will review the rationale for each indication and its related literature, both in vitro and in vivo studies. The properties that make collagen membranes attractive for use in regenerative therapy will be addressed. In addition, varieties of cross-linking techniques utilized to retard the degradation rate of collagen membranes will be discussed.