Effect of local metronidazole application on periodontal healing following guided tissue regeneration. Clinical findings

Does Topical Metronidazole-Chlorhexidine Combination Gel Improve Healing of Intraoral Incisions ? A Split-Mouth Comparative Study

Background

The oral cavity is a unique environment where wound healing needs to occur in the presence of heavily contaminated oral fluid often leading to infections at the suture site. Topical antimicrobial agents have proven to be effective in controlling intraoral infections. One such antimicrobial combination is Metronidazole-Chlorhexidine which has commonly been used to treat oral ulcers and gingival inflammation; however, there are no studies of its use in the healing of oral incisions.

Methodology

This split-mouth study comprised of 15 participants who received 30 intraoral incisions. Incisions were placed either simultaneously (Group 1) or at spaced intervals (Group 2) for various minor and major surgical procedures. Metronidazole -Chlorhexidine gel was applied to the study sites while the control sites were allowed to heal naturally. Pain, inflammation, and healing were assessed using visual analogue scale and healing index by Landry et al.

Results

The study sites showed better wound healing and decreased postoperative inflammation. There was a statistically significant decrease in post-operative pain in the study site in Group 1 but not in Group 2.

Conclusion

Metronidazole-Chlorhexidine combination gel is a cost-effective, readily available, and safe medicament to improve healing of intraoral incisions and reduce post-operative inflammation and pain.

An innovative application of pre-medicated collagen sponges with regenerative biomaterials for management of an infected extraction socket: A case report

Localized infection of the extraction socket can compromise bone quality and quantity within the socket and bone support for the adjacent dentition. These events can preclude immediate rehabilitative interventions, such as implant placement, and increase the technical sensitivity of guided bone regeneration procedures for successful tissue and bone gain. The use of local scaffolds containing effective antimicrobial agents may suppress local infection and facilitate the regenerative process related to the introduced bone graft particles and barrier collagen membrane. In this case report, pre-medicated collagen sponges containing chlorhexidine and metronidazole were used in conjunction with a bone graft and collagen membrane for guided tissue and bone regeneration, which was followed by delayed implant placement with 2 years of follow-up evaluations.

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.

Current status and future of delivery systems for prevention and treatment of infections in the oral cavity

Oral health reflects the general health, and it is fundamental to well-being and quality of life. An infection in the oral cavity can be associated with serious complications in human health. Local therapy of these infections offers many advantages over systemic drug administration, targeting directly to the diseased area while minimizing systemic side effects. Specialized drug delivery systems into the oral cavity have to be designed in such a fashion that they resist to the aqueous environment that is constantly bathed in saliva and subject to mechanical forces. Additionally, a prolonged release of drug should also be provided, which would enhance the efficacy and also decrease the repeated dosing. This review is aimed to summarize the current most relevant findings related to local drug delivery of various drug groups for prevention and treatment of infections (viral, bacterial, fungal) and infection-related manifestations in the oral cavity. Current therapeutic challenges in regard to effective local drug delivery systems will be discussed, and the recent approaches to overcome these obstacles will be reviewed. Finally, future prospects will be overviewed to promote novel strategies that can be implemented in clinical management for prevention and treatment of oral infections.

Antibacterial effects of polymeric PolymP-n Active nanoparticles. An in vitro biofilm study

OBJECTIVE

to study the antibacterial effect of polymeric PolymP-n Active nanoparticles using an in vitro subgingival biofilm model.

METHODS

Hydroxyapatite discs coated with five modalities of nanoparticles (NPs): NPs, NPs doped with zinc, calcium, silver and doxycycline, PBS as control, and Streptococcus oralis, Actinomyces naeslundii, Veillonella parvula, Fusobacterium nucleatum, Porphyromonas gingivalis and Aggregatibacter actinomycetemcomitans were studied in a static in vitro biofilm model (12, 24, 48, and 72h). Nano-roughness of the different disc surfaces (SRa, in nm) and morphological characteristic of the biofilms (thickness (μm) and bacterial viability) were studied by different microscopy modalities. Quantitative Polymerase Chain Reaction was used to assess the effect of the nanoparticles on the bacterial load (colony forming unit per milliliter) (CFUmL^-1). Analysis of variance and post-hoc testing with T3 Dunnett́s, and Student Newman Keuls correction was used. Results were considered statistically significant at p<0.05.

RESULTS

Surfaces containing the different nanoparticles showed significant increments in roughness when compared to controls (p<0.05). A similar biofilm formation and dynamics was observed, although reductions in bacterial viability were detected in biofilms in contact with the different nanoparticles, more pronounced with silver and doxycycline NPs. Doxycycline-NPs biofilms resulted in unstructured biofilm formation and significantly lower number of the six species when compared with the other nanoparticles specimens and controls (p<0.001 in all cases).

SIGNIFICANCE

Polymeric PolymP-n Active nanoparticles when combined with silver and doxycycline showed a significant antibacterial effect when tested in an in vitro subgingival biofilm model.

Efficacy of doxycycline release collagen membrane on surgically created and contaminated defects in rat tibiae: A histopathological and microbiological study

BACKGROUND

The effects of systemic antibiotics on controlling infective pathogens after guided bone regeneration(GBR) procedures especially in membrane exposures are limited. However, local administrations of antibiotics are rare in GBR techniques.

AIM

The aim of this study was to investigate the osteogenesis potential and the antibacterial effect of a doxycycline releasing collagen membrane in surgically created and contaminated defects in rat tibiae.

MATERIAL AND METHODS

Defects were created in 20 rats that were randomly divided in to two groups: control group (defect contaminated by Porphyromonas gingivalis, filled with bone graft and covered by collagen membrane); test group (defect contaminated by P. gingivalis filled with bone graft and covered by collagen membrane containing 1mg/cm(2) doxycycline. Animals were sacrificed post surgically on the 14th day for microbiologic evaluation and on the 28th day for histopathological evaluation.

RESULTS

The degree of osteogenesis in the test group was seen to be significantly higher than control group (p: 0.011; p<0.05). Furthermore in test group, no bacterial growth was observed. The bacteria counts were determined between 1×104 and 268×104CFU/g with a median of 1.32×104 for control group.

CONCLUSIONS

Within the limitations of this study, the results of the present study suggests that the use of a doxycycline releasing membrane has a positive effect on contaminated GBR procedures for limiting P. gingivalis infections leading to bone formation following GBR procedures in a rat model.

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.

Doxycycline counteracts bone morphogenic protein 2-induced osteogenic mediators

BACKGROUND

Microbial colonization during wound healing may exaggerate the inflammatory response and could adversely affect the outcome of periodontal regeneration. Bone morphogenic proteins (BMPs) directly augment bone regeneration. Interestingly, inhibitors of tissue collagenases, such as sub-antimicrobial-dose doxycycline, also indirectly promote hard-tissue regeneration. In this study, it is hypothesized that BMP2-mediated bone regeneration would be positively affected by simultaneous treatment of sub-antimicrobial-dose doxycycline.

METHODS

Human periodontal ligament (PDL) cells were stimulated with: 1) 10 ng/mL BMP2; 2) 1 μg/mL doxycycline; or 3) a combination of the two. The expressions of alkaline phosphatase, osteocalcin, osteonectin, and osteopontin were analyzed along with in vitro mineralized nodule formation and calcium accumulation.

RESULTS

BMP2 was a potent inducer of osteocalcin/osteopontin (statistically significant at P <0.01) and osteonectin in PDL cells relative to stimulation with doxycycline. However, doxycycline relative to BMP2 (statistically significant at P <0.001) upregulated the expression of alkaline phosphatase and in vitro mineralized nodule formation. Contrary to expected results, combined BMP2 and doxycycline induced a statistically significant (P <0.001) downregulation of alkaline phosphatase, osteocalcin, osteonectin/osteopontin, and in vitro mineralized nodule formation compared to stimulation with either BMP2 or doxycycline alone.

CONCLUSIONS

Combined treatment of BMP2 and doxycycline in PDL cells counteracts the osteogenic mediators. Molecular interaction of growth factors should be explored before using a combination of these biologic molecules. It is important and clinically relevant to determine whether tetracycline and its other derivatives also counteract BMP functions. Animal models should be used to confirm these in vitro results.

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.

Bio-degradation of a resorbable collagen membrane (Bio-Gide) applied in a double-layer technique in rats

OBJECTIVE

The aim of this study was to evaluate histologically the bio-degradation of two layers of Bio-Gide((R)) (BG) membrane, as compared with that of a single layer.

MATERIAL AND METHODS

Two circular calvarial bony defects, 5 mm in diameter, were made in 24 Wistar rats. BG membrane, labeled with biotin, was cut into 5-mm-diameter disks, and placed in defects either as a mono-layer membrane (MLM) or as a double-layer membrane (DLM). Rats were sacrificed after 4 or 9 weeks and histology was performed. Membranes were stained with horseradish peroxidase-conjugated streptavidin and aminoethyl carbazole as a substrate for detection of biotinylated collagen. The area of collagen and thickness of the residual membranes were measured by image analysis software. Statistical analysis was performed using the non-parametric Wilcoxon's signed-ranks test.

RESULTS

At 4-week collagen area per measurement window within the DLM sites (0.09+/-0.05 mm(2)) was significantly greater (P<0.01) than that in the MLM sites (0.047+/-0.034 mm(2)). At 9 weeks, the collagen area was also greater in the DLM sites (0.037+/-0.026 mm(2)) compared with that of the MLM sites (0.025+/-0.016 mm(2)); however, this difference did not reach statistical significance. The rate of membrane degradation, calculated as percent membrane lost compared with baseline, was similar for the DLM and MLM at both time points ( approximately 60% at 4 weeks and approximately 80% at 9 weeks). In addition, the residual DLM thickness at 4 weeks (475.5+/-73.77 mum) was significantly (P<0.01) greater than that of MLM (262.38+/-48.01 mum). At 9 weeks, membrane thickness was also greater in the DLM sites (318.22+/-70.45 mum) compared with that of the MLM sites (183.32+/-26.72 mum); however, this difference did not reach statistical significance. The reduction in thickness between 4 and 9 weeks was 30% for MLM and 33% for DLM.

DISCUSSION

The use of a double layer of BG membrane results in a barrier of increased collagen area and thickness, compared with application of a single layer.

The inhibitory effects of naringin on the growth of periodontal pathogens in vitro

Naringin is a flavonoid that is commonly found in grapefruits. The objective of this study was to evaluate the effects of naringin on the growth of periodontal pathogens such as A. actinomycetemcomitans and P. gingivalis in vitro. For comparison, the effects of naringin on several oral microbes were also studied. Different concentrations of naringin solution were added to calibrated suspensions of A. actinomycetemcomitans and P. gingivalis. All the suspensions were incubated for 3, 6 and 24 h in an anaerobic chamber at 37 degrees C. At each time point, selected dilutions from each culture broth were plated on blood agar plates. Colonies recovered on blood agar were visually counted on days 3 and 5, respectively. A. actinomycetemcomitans showed a significant decrease (p < 0.05) in viable counts after 3 h when naringin was added at baseline. P. gingivalis also showed a marked growth reduction in the presence of naringin, and no colony forming units could be observed after 24 h. Naringin also had an inhibitory effect against all bacteria and yeasts tested. The results suggest that naringin possesses significant antimicrobial properties on periodontal pathogens in vitro. It also has an inhibitory effect on some common oral microorganisms in low concentrations.

Microbial colonization patterns predict the outcomes of surgical treatment of intrabony defects

AIM

To explore the impact of bacterial load and microbial colonization patterns on the clinical outcomes of periodontal surgery at deep intrabony defects.

MATERIALS AND METHODS

One hundred and twenty-two patients with advanced chronic periodontitis and at least one intrabony defect of >3 mm were recruited in 10 centres. Before recruitment, the infection control phase of periodontal therapy was completed. After surgical access and debridement, the regenerative material was applied in the test subjects, and omitted in the controls. At baseline and 1 year following the interventions, clinical attachment levels (CAL), pocket probing depths (PPD), recession (REC), full-mouth plaque scores and full-mouth bleeding scores were assessed. Microbial colonization of the defect-associated pocket was assessed using a DNA-DNA checkerboard analysis.

RESULTS

Total bacterial load and counts of red complex bacteria were negatively associated with CAL gains 1 year following treatment. The probability of achieving above median CAL gains (>3 mm) was significantly decreased by higher total bacterial counts, higher red complex and T. forsythensis counts immediately before surgery.

CONCLUSIONS

Presence of high bacterial load and specific periodontal pathogen complexes in deep periodontal pockets associated with intrabony defects had a significant negative impact on the 1 year outcome of surgical/regenerative treatment.

Effect of Early Membrane Removal on Regeneration of Class II Furcation Defects in Dogs

BACKGROUND

This study evaluated the influence of early removal of an expanded polytetrafluoroethylene (ePTFE) membrane on periodontal regeneration.

METHODS

The third and fourth mandibular bicuspids of six healthy mongrel dogs were used. Class II furcation lesions were surgically created making lesions chronic for 21 days. Full flaps were elevated, and ePTFE membranes were adapted over the defects. The membranes were removed at 2 weeks on the experimental sides (test group [TGr]) and at 4 weeks on the control side (control group [CGr]). The dogs were sacrificed 12 weeks following placement of the membranes, and the teeth were histologically processed. Area measurements of new tissue (NT), epithelium (EP), connective tissue (CT), and new bone (NB) and linear measurements of bone height (BH) and new cementum (NC) were made. Wilcoxon signed rank test (P <0.05; N = 6) was carried out to determine differences between groups.

RESULTS

The area measurements (in mm2) for TGr and CGr, respectively, were as follows: 14.32 +/- 4.01 and 12.46 +/- 3.54 (NT); 0.04 +/- 0.09 and 0.01 +/- 0.04 (EP); 2.31 +/- 2.60 and 1.91 +/- 2.96 (CT); and 9.56 +/- 3.77 and 8.79 +/- 2.99 (NB). The results of the linear measurements (in mm) for TGr and CGr, respectively, were as follows: 3.85 +/- 1.21 and 4.03 +/- 0.94 (BH) and 10.91 +/- 1.72 and 10.59 +/- 1.80 (NC). There were no statistically significant differences between TGr and CGr for any measurement.

CONCLUSION

The early removal of ePTFE membranes in Class II furcation defects in dogs did not affect periodontal regeneration.

Changes in transforming growth factor-beta1 in gingival crevicular fluid following periodontal surgery

OBJECTIVES

Growth factors play a major part in wound healing, including in the periodontium. However, the presence of growth factors in gingival crevicular fluid (GCF) in humans during periodontal wound healing has not yet been determined. Our hypothesis is that such factors are present in GCF and that changes in their levels might be of value as a prognostic marker of wound-healing activity and therapeutic progress following periodontal surgery. The aim of this study was therefore to measure transforming growth factor-beta1 (TGF-beta1) in GCF collected from sites that have undergone guided tissue regeneration (GTR) and conventional flap (CF) surgery and to compare these with GCF collected from unaffected healthy sites.

MATERIALS AND METHODS

GCF samples were collected, using filter paper strips, at baseline (pre-surgical) and then at intervals up to 26 weeks from 16 patients undergoing GTR and from 11 patients undergoing CF surgery. After elution and acid treatment, TGF-beta1 levels were measured by ELISA.

RESULTS

Treatment of periodontal defect sites significantly reduced the mean probing pocket depth (PPD) and improved the mean lifetime cumulative attachment loss (LCAL). Average GCF volumes also significantly increased at all sites at 2 weeks post-surgery and thereafter declined to baseline levels, except at the GTR test sites that were still elevated at 7 weeks. TGF-beta1 could be detected in almost all GCF samples, and 2 weeks after surgery, the average levels increased two-fold at the surgically treated but not at the control sites, which remained unchanged.

CONCLUSION

TGF-beta1 is readily detectable in GCF and increases transiently following periodontal surgery. This suggests that changes in the levels of this growth factor in GCF might be useful for monitoring the progress of periodontal repair and regeneration.

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.

Efficacy of controlled-release subgingival chlorhexidine to enhance periodontal regeneration

BACKGROUND

Periodontal regeneration success may be limited by placing bone grafts and membranes in infected sites. The objective of this study was to test the hypothesis that adjunctive subgingival administration of chlorhexidine gelatin bioresorbable chips enhances bone gain when used in conjunction with guided tissue regeneration.

METHODS

This was a single center, blinded, 2-arm parallel design study of 44 subjects with one or more sites with probing depth and clinical attachment loss > or = 5 mm following initial therapy and radiographic evidence of bone loss. The patients were randomly assigned to receive either chlorhexidine (CHX) chip or sham chip placement one week prior to regenerative therapy that included graft placement and site coverage with guided tissue membranes. Patients also received CHX or sham chip placement, per their randomization, adjunctively to scaling and root planing or maintenance procedures. Periodontal examinations were completed at baseline (8 weeks prior to surgery); 1 week prior to surgery; and at 3, 6, and 9 months postsurgery. The major outcomes for the study were changes in bone height and bone mass as measured from standardized radiographs used for quantitative digital subtraction radiography over the 11-month study period.

RESULTS

Subjects receiving sham chip placement gained a mean bone height of 1.49 +/- 0.22 mm, while patients receiving the CHX chips gained significantly more bone height (3.54 +/- 0.45 mm; P<0.001). Similarly, subjects receiving CHX chips as an adjunct gained significantly more bone mass (5.57 +/- 0.69 mg; P<0.001) than the standard therapy (2.59 +/- 0.34 mg).

CONCLUSIONS

These pilot results indicate that locally delivered, controlled-release antimicrobial treatment may improve the amount of bone gain during guided tissue regeneration procedures. These data support the evidence that infection control is an important variable in successful regeneration.

Periodontal therapy using local delivery of antimicrobial agents

Antimicrobial agents, systemic and/or local, are thought by some to be effective agents for treating periodontal infections. Here the authors determine the costs and benefits of local delivery agents for treating periodontal disease. Applying this cost-benefit analysis to patient care, however, will depend upon a clinician's expertise and a patient's value system.

Guided tissue regeneration in intrabony defects using an experimental bioresorbable polydioxanon (PDS) membrane. A 24-month split-mouth study

AIM

The comparison of the clinical, radiographic, and microbiological healing results in deep intrabony defects following GTR therapy with two different bioresorbable membranes in a prospective split-mouth design.

MATERIAL AND METHODS

31 pairs of contralateral intrabony defects were randomly treated with either an experimental Polydioxanon (PDS) membrane or a Polylactic acid (PLA) matrix barrier. After 6, 12 and 24 months, healing results were assessed using clinical examinations (REC, PPD, CAL, vertical relative attachment gain V-rAG), quantitative digital subtraction radiography (amount and area of bone density changes), and microbiological analysis.

RESULTS

Postoperative membrane exposures occurred in 14 PDS and 2 PLA treated sites. 6, 12 and 24 months p.o., both membranes provided a significant gain in CAL [median values: 6 months (PDS vs. PLA: 3.0 vs. 3.0 mm); 12 and 24 months (PDS vs. PLA: 4.0 vs. 4.0 mm)], which corresponded to a V-rAG of 57.1% (PDS) vs. 62.5% (PLA) after 24 months. PDS and PLA treated sites revealed significant bone density gain 6, 12 and 24 months after surgery. 38.8% (PDS) vs. 41.8% (PLA) of the initial defect areas showed bone density gain. While the gain in bone density was significantly greater in PDS than in PLA sites, neither CAL gain nor the area of bone density changes revealed significant differences. Microbiological culture revealed similar bacterial loads in PDS and PLA sites during the first 12 months.

CONCLUSION

This 24-month study indicates that the PDS and PLA membranes can provide similar favorable regeneration results in deep intrabony periodontal defects, although considerably more postoperative membrane exposures have to be expected in PDS treated sites.

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.

Histological evaluation of different biodegradable and non-biodegradable membranes implanted subcutaneously in rats

Different types of biodegradable membranes have become available for guided tissue regeneration. The purpose of this study was to evaluate histologically three different biodegradable membranes (Bio-Gide, Resolut and Vicryl) and one non-biodegradable membrane (expanded polytetrafluoroethylene/e-PTFE) implanted subcutaneously in rats. Five subcutaneous pouches were created in each of 24 rats. One of the four test membranes was randomly placed in each of the four pouches and one pouch was left empty to serve as a control. Histological evaluation was performed after 4, 10 and 21 days which demonstrated that e-PTFE was well tolerated and encapsulated by a fibrous connective tissue capsule. There was capsule formation around Resolut and Vicryl and around Bio-Gide in the early phase there was a wide inflammatory zone already. e-PTFE and Vicryl were stable materials while Resolut and Bio-Gide fragmented in the early phase. In the late phase Vicryl was surrounded by an increasing amount of multinucleated macrophages and a thin capsule, whilst around Resolut and Bio-Gide a strong foreign body reaction was observed. Also granuloma formation was noted around the fragmented Resolut material in its capsule and a mild inflammatory reaction surrounding Bio-Gide within its thin capsule.

Tetracycline-coated polytetrafluoroethylene barrier membranes in the treatment of intraosseous periodontal lesions

BACKGROUND

Periodontal pathogens are detrimental to periodontal healing in barrier membrane-assisted periodontal therapy. Tetracycline-coating of barrier membranes may reduce levels of infecting pathogens. This study evaluated the clinical and microbiological effects of tetracycline-coated expanded polytetrafluoroethylene (T-ePTFE) barrier membranes in the treatment of 2- to 3-wall intraosseous periodontal lesions around mandibular molars.

METHODS

Eleven patients received non-coated barrier membranes (ePTFE) and 11 patients received T-ePTFE barrier membranes. Tetracycline coating was performed by placing ePTFE membranes first in a 5% tridodecylmethylammonium chloride solution and then in a basic 3% tetracycline solution. Microbiological examination included conventional culture and DNA probe analyses. Barrier membranes were removed 6 weeks after insertion.

RESULTS

At baseline, the periodontal lesion depth averaged 8.0 mm in the ePTFE treated group and 7.4 mm in the T-ePTFE group. At 1 year post-treatment, the mean gain of probing attachment was 1.9 mm in the ePTFE group and 3.3 mm in the T-ePTFE group (P = 0.02). At 3 minutes after membrane placement, suspected periodontal pathogens were detected in several ePTFE membranes but only in one T-ePTFE membrane. At 6 weeks, all membranes showed periodontal pathogens, including Porphyromonas gingivalis, Fusobacterium species, Peptostreptococcus micros, Bacteroides forsythus, and motile rods.

CONCLUSIONS

This study suggests that the use of tetracycline-coated ePTFE barrier membranes can result in additional gain of clinical periodontal attachment, most likely due to the antimicrobial properties of tetracycline during initial healing.

The effect of postsurgical antibiotics and a bioabsorbable membrane on regenerative healing in Class II furcation defects

BACKGROUND

The purpose of this randomized, controlled, blinded, clinical investigation was to determine the effect of postsurgical antibiotics on osseous healing in Class II furcation defects.

METHODS

Twenty-four Class II furcation defects in 24 patients were treated with either a polylactide bioabsorbable membrane, demineralized freeze-dried bone allograft (DFDBA) plus antibiotics (GBA or test group) or with a polylactide membrane and DFDBA alone (GB or control group). Twelve patients were included in each group. The antibiotic regimen consisted of ciprofloxacin 250 mg twice daily and metronidazole 250 mg tid for 1 week followed by a 7-week regimen of doxycycline hyclate 50 mg daily. Treatment was performed on either mandibular buccal or lingual, or maxillary buccal Class II furcation defects. Defects were randomly selected by a coin toss for treatment and all open and closed measurements were performed by a blinded examiner. Final open and closed measures from a stent were repeated at the 9-month second stage surgery. Power analysis to determine superiority of antibiotic treatment showed that a 12 per group sample size would yield 93% power to detect a 1.5 mm difference and 64% power to detect a 1 mm difference.

RESULTS

Mean open horizontal probing depth reductions at 9 months were greater for the GBA group than for the GB group (2.92+/-1.78 versus 2.50+/-1.62 mm); however, these differences were not statistically significant. Seven of 12 furcations (58%) in the GBA group demonstrated >50% vertical defect fill at 9 months compared to 8 of 12 furcations (67%) in the GB group. There were no significant differences in mean open horizontal probing depth reduction between smokers and non-smokers in either the GBA or GB groups. Membrane exposure did not appear to affect regenerative healing in either the GBA or GB groups.

CONCLUSIONS

The administration of postsurgical antibiotics did not produce statistically superior osseous healing of Class II furcation defects. This result may be attributable to membrane design which facilitates connective tissue ingrowth, thereby preventing bacterial downgrowth and contamination of the newly regenerated tissues.

Topical and systemic antimicrobial therapy in guided tissue regeneration

BACKGROUND

Bacterial contamination of membrane material negatively affects healing after guided tissue regeneration (GTR) procedures; conversely, flap connective tissue integration on barrier material improves the clinical outcomes. The objective of this study was to evaluate the effect of topical application of antibiotics on: 1) clinical outcomes of GTR surgical procedures using titanium reinforced expanded polytetrafluoroethylene (ePTFE) periodontal membrane; 2) bacterial colonization of membrane material; and 3) flap connective tissue-membrane integration.

METHODS

Fifty-six deep interproximal bony defects were treated with GTR surgical procedures using titanium reinforced ePTFE periodontal membranes. Patients were randomly assigned to 1 of the 2 antimicrobial treatment groups: the test group received weekly topical application of 25% metronidazole gel and the control group received systemic antibiotics (amoxicillin plus clavulanic acid 1 g/day for 14 days). Clinical outcomes were assessed at 1 year; the amount of bacterial contamination and connective tissue integration on membrane material was evaluated at time of membrane removal by means of a morphological (SEM) method.

RESULTS

No statistically significant difference was found between test and control groups in terms of clinical attachment (CAL) gain (baseline CAL - 12 months CAL; P = 0.2) and probing depth (PD) reduction (baseline PD - 12 months PD; P = 0.6). A greater increase in gingival recession (REC) (12 months REC - baseline REC) was found in the test group compared to the control group (P = 0.003). The SEM analysis revealed no statistically significant (t test) difference between test and control groups in the number of fields positive to integrated connective tissue (P = 0.82), while the number of fields positive to bacteria was statistically higher (P < 0.001) in the control group.

CONCLUSIONS

Local antibiotic administration is more effective than systemic use in preventing membrane contamination, but it does not improve clinical outcomes due to an interference of the vehicle (gel) with gingival tissues which may reduce the potential benefits derived from better control of the bacterial load.

The use of locally delivered metronidazole in the treatment of periodontitis. Clinical results

Local delivery of antimicrobials has been investigated as a possible method for controlling and treating periodontal disease. A number of antimicrobial agents have been studied both as adjunctive therapies with scaling and root planing and as stand-alone chemotherapies. More recent investigations have focussed on the delivery of antimicrobials in sustained-release formulations designed to maintain effective concentrations of drug within the periodontal pocket. This article provides an overview of the development of the use of locally-delivered metronidazole in periodontal therapy and the current state-of-the-art of the technique. It is concluded that treatment with local delivery of metronidazole seems to be as effective as scaling and root planing in untreated as well as in recall subjects. However, there are reasons to suggest that local delivery of metronidazole should not be used as a substitute for conventional treatment of periodontal disease, since side-effects of long-term use and repeated use are not known. The antibiotic regimen should preferably be used as an adjunct to surgical and non-surgical therapy.

Oral and periodontal tissue. Maintenance, augmentation, rejuvenation, and regeneration

This article discusses the controversies, usefulness, and limitations of oral and periodontal tissue maintenance, augmentation, rejuvenation, and regeneration in the dog and cat. It details many of the specialized materials and techniques used in these procedures in attempts to re-establish healthy conditions within the periodontium. Bone loss following tooth extraction is discussed with consideration as to which teeth should have alveolar ridge maintenance procedures and the important reasons as to why. Radiographs show the degree of improvement demonstrated in treatment of various cases involving bone loss from periodontal disease, treatment of bone injuries with oral fractures and their prevention.

GTR therapy of intrabony defects using 2 different bioresorbable membranes: 12-month results

This prospective split-mouth study was designed to compare the clinical and radiographic healing results in intrabony periodontal defects 12 months after GTR therapy with 2 different bioresorbable barriers. The study comprised 25 healthy patients with one pair of contralaterally located intrabony defects with a probing pocket depth of > or = 6 mm and radiographic evidence of angular bone loss of > or = 4 mm. The 2 defects of each patient were randomized for treatment either with polylactic acid (PLA) membranes or with polyglactin-910 (PG-910) membranes. The patients received systemic doxycycline (100 mg/d) for 11 days postoperatively. One blinded examiner recorded the following clinical parameters using a pressure calibrated probe at baseline and after 12 months: papillary bleeding index (PBI), gingival recession (REC), probing pocket depth (PPD), and probing attachment level (PAL). The vertical relative attachment gain (V-rAG) was calculated as a % of the PAL gain related to the maximum possible attachment gain (expressed by the intraoperatively measured depth of the osseous defect). Geometrically standardized intraoral radiographs were quantitatively evaluated for bone changes (density, area) in the defect region using digital subtraction radiography (DSR). Clinical and radiographic data were statistically analyzed using the Wilcoxon-signed-rank test (alpha=0.05). Postoperative membrane exposures occurred in 9 PLA and 13 PG-910 treated sites. After 12 months of healing, both barrier types provided significant PPD reductions and PAL gain [median (25/75 percentile)]: deltaPPD [PLA: 3.0 (2.0/4.0) mm; PG-910: 3.0 (2.0/4.5) mm]; deltaPAL [PLA: 3.0 (2.5/4.0) mm; PG-910: 2.0 (1.0/4.0) mm]. V-rAG amounted to 60% in PLA sites and 54% in PG-910 sites. DSR revealed significant bone density gain after 12 months. 58.3% of the initial defect area in PLA sites and 54.0% of the initial defect area in PG-910 sites showed bone density gain. Neither clinical nor radiographic data revealed any significant difference between the 2 barrier types after 12 months. In conclusion, this 12-month study demonstrated that PLA and PG-910 membranes provided similar favorable regeneration results in deep intrabony periodontal defects.

The role of local drug delivery in the management of periodontal diseases: a comprehensive review

This review article evaluates the role of local drug delivery systems in the management of periodontal diseases. The efficacy of several local delivery devices (i.e., tetracycline fibers, metronidazole and minocycline gels, chlorhexidine chips, and doxycycline polymer) which are either commercially available in the United States or abroad, or are currently under consideration for Food and Drug Administration (FDA) approval are discussed. The drug delivery systems are assessed with regard to their functional characteristics, effectiveness as a monotherapy, as compared to scaling and root planing, and ability to enhance conventional therapy. Furthermore, controversies associated with local delivery are addressed (e.g., induction of bacterial resistant strains, the efficacy of systemic versus local drug delivery, and whether local drug delivery should function as an alternative or as an adjunct to conventional treatment).

Specific issues in clinical trials on the use of barrier membranes in periodontal regeneration

There are presently a number of different barriers available for use clinically in guided tissue regeneration (GTR) procedures. A number of trials using these techniques and comparing different types of barrier membranes are being published in the scientific literature. This review discusses issues related to clinical trials on the use of barrier membranes in periodontal regeneration. Outcome measures, both clinical and histological, are discussed in relation to results following GTR procedures. The difference between regeneration and repair is reviewed as well as methods of clinical and histologic assessment of both these outcomes. Data regarding the impact of patient variables and tooth or defect variables on outcomes are presented and suggestions for study designs are made based on these variables. Aspects of assessing for an appropriate sample size in superiority and equivalency trials using GTR techniques are presented as well as interpretation of results following these trials and their clinical significance.

The use of biologic response modifiers in human clinical trials

To optimize regeneration of the periodontium, new cementum, periodontal ligament, and bone must be formed. Conventional periodontal surgery decreases the likelihood of continued progressive periodontal disease however, it does not lead to significant periodontal regeneration. In vitro studies have identified a class of biologic response modifiers loosely referred to as growth factors, which stimulate the cellular events of tissue regeneration. The most promising are mitogenic and differentiation factors. Based on promising results from animal studies, the application of growth factors to predictably stimulate periodontal regeneration is entering human clinical trials. This manuscript deals with several important considerations in testing biologic response modifiers in humans. Suggestions are made regarding the following parameters: 1) selection of the unit of measurement; 2) patient and lesion selection; 3) identification of controls; 4) selection of outcome parameters; 5) statistical approach; and 6) considerations in treatment regimens.

Periodontal healing following reconstructive surgery: effect of guided tissue regeneration

Clinical healing following guided tissue regeneration (GTR) in deep intrabony pockets was compared to healing following gingival flap surgery alone (GFS). 15 patients received the GTR treatment including an expanded polytetrafluoroethylene membrane. 13 other patients received the control treatment GFS. A postsurgery protocol emphasizing wound stability and infection control was used. Treatment effects were evaluated 6 months postsurgery. Mean pre-surgery probing depth for the GTR and control treatments was 7.5 +/- 1.0 and 7.7 +/- 1.5 mm, respectively. Significant probing depth reduction (3.8 +/- 1.2 and 2.9 +/- 1.1 mm), attachment level improvement (2.4 +/- 2.1 and 2.2 +/- 1.2 mm) and bone fill (2.0 +/- 2.0 and 2.4 +/- 0.9 mm) followed the GTR and control protocols, respectively (p < 0.01). Significant differences between GTR and control treatments were observed in probing depth reduction (p < 0.01) and in gingival recession increase (1.7 +/- 1.5 and 0.7 +/- 0.9 mm, respectively; p < 0.05). The results suggest that GTR procedures compared to GFS have similar clinical potential in intrabony pockets, under the present protocol.

Bacterial colonization of barrier material and periodontal regeneration

The objective of this study was to evaluate the relationship between the presence of bacteria on the tooth-facing surface of ePTFE barriers and the clinical outcome of membrane supported reconstructive periodontal surgery. 20 systemically healthy subjects affected by chronic periodontitis were enrolled. One tooth site per patient, associated with an angular bony defect and a probing attachment loss of > 4 mm, was selected to be treated by means of a guided tissue regeneration procedure using an ePTFE barrier membrane. Antibiotics (Augmentin 1 g/day) for 2 weeks were prescribed. In addition to the use of chlorhexidine for post-surgical plaque control, all patients were recalled once a week for professional tooth cleaning. The barrier material was harvested for SEM analysis after 4-6 weeks. Professional tooth cleaning and reinforcement of sel-performed oral hygiene measures were given at 1 mouth intervals after membrane removal. For each treated site, the difference in probing attachment loss between baseline examination and a follow-up examination after 6 months of healing was calculated. The results of the SEM-analysis revealed that bacterial colonization was evident in the collar area of all the retrieved membranes. In the mid part of the membranes 30 out of 60 microscopic fields (50%) demonstrated microbial colonization, and in the most apical part 9 out of 60 fields (15%). Regression analysis indicated that gain in probing attachment level was positively correlated to initial attachement loss and negatively correlated to microbial colonization of the mid part of the membranes. It was concluded that bacterial colonization in the mid part of the ePTFE membrane reduced the potential gain in probing attachment following GTR-therapy with almost 50%.

Periodontal regeneration around natural teeth

1. Evidence is conclusive (Table 2) that periodontal regeneration in humans is possible following the use of bone grafts, guided tissue regeneration procedures, both without and in combination with bone grafts, and root demineralization procedures. 2. Clinically guided tissue regeneration procedures have demonstrated significant positive clinical change beyond that achieved with debridement alone in treating mandibular and maxillary (buccal only) Class II furcations. Similar data exist for intraosseous defects. Evidence suggests that the use of bone grafts or GTR procedures produce equal clinical benefit in treating intraosseous defects. Further research is necessary to evaluate GTR procedures compared to, or combined with, bone grafts in treating intraosseous defects. 3. Although there are some data suggesting hopeful results in Class II furcations, the clinical advantage of procedures combining present regenerative techniques remains to be demonstrated. Additional randomized controlled trials with sufficient power are needed to demonstrate the potential usefulness of these techniques. 4. Outcomes following regenerative attempts remain somewhat variable with differences in results between studies and individual subjects. Some of this variability is likely patient related in terms of compliance with plaque control and maintenance procedures, as well as personal habits; e.g., smoking. Variations in the defects selected for study may also affect predictability of outcomes along with other factors. 5. There is evidence to suggest that present regenerative techniques lead to significant amounts of regeneration at localized sites on specific teeth. However, if complete regeneration is to become a reality, additional stimuli to enhance the regenerative process are likely needed. Perhaps this will be accomplished in the future, with combined procedures that include appropriate polypeptide growth factors or tissue factors to provide additional stimulus.

Periodontitis vs. peri-implantitis: the same disease? The same treatment?

The microbial flora in the natural dentition sulcus/pocket and the implant crevice/pocket is very similar in both health and disease. In health, coccal forms predominate, and in disease, large numbers of Gram-negative pathogens are associated with both tooth and implant. It has also been demonstrated that the bacteria in the partially edentulous implant case may be more pathogenic (especially Gram-negative rods and spirochetes) than in the fully edentulous case, indicating a possible seeding mechanism from tooth pocket to implant crevice. Detoxification procedures involving the use of tetracycline and citric acid prior to regenerative procedures with the use of barrier membranes and grafting materials are necessary, and the same problems attendant to premature exposure of the barrier membrane(s) in the natural dentition situation apply to the implant case. It is apparent that periodontitis = peri-implantitis in etiology and therapy.

Systemic antimicrobial treatment and guided tissue regeneration. Clinical and microbiological effects in furcation defects

The purpose of this investigation was to study the microbiota associated with furcation-involved teeth before and after treatment by the guided tissue regeneration procedure (GTR) with non-resorbable ePTFE membranes, and to evaluate the benefit of additional systemic antimicrobial therapy (ornidazole). Each of 10 patients contributed 1 pair of bilateral mandibular molars with comparable furcation defects. 5 defects were treated with a membrane and the active drug, 5 were treated without a membrane but with the active drug, 5 were treated with a membrane and a placebo, and 5 were treated with neither a membrane nor the active drug. Considerable differences were found in the healing response of furcation defects treated with or without the antimicrobial agent. More horizontal attachment gain and increase in bone density was obtained in patients receiving the active drug than in patients receiving the placebo. With 1 exception, all sites with increasing horizontal probing depth were found in patients of the placebo group. Treatment with membrane plus ornidazole resulted in 0.7 mm mean recession and -1.2 mm mean decrease in horizontal probing depth. Sites treated with membranes generally tended to be positive for 15 target micro-organisms more often than sites treated without a membrane. This was particularly evident for Fusobacterium, Prevotella intermedia and Actinomyces odontolyticus. Whereas GTR-treated sites were often already positive upon removal of the membrane, re-emergence of target organisms seemed to be more delayed in the conventionally-treated sites.

The effect of flap management and bioresorbable occlusive devices in GTR treatment of degree III furcation defects. An experimental study in dogs

The present experiment on guided tissue regeneration had 2 objectives namely: (i) to study if an improved anchorage of the soft tissue flaps during the initial healing period after membrane placement would reduce the tendency for soft tissue recession and allow for healing of also large furcation defects; (ii) to determine if the use of biodegradable membranes in GTR procedures may promote new attachment formation in degree III furcation defects. 2 experiments were performed which included 5 and 8 dogs each. In each animal, the 3rd premolar of the left or right side of the mandible was selected as test site using the contralateral tooth as control. 2 months prior to the start of the experiment, the 2nd and 4th premolars in each side of the mandible were extracted. The extractions were performed to create a large edentulous space mesial and distal to the 3rd premolar. During GTR therapy the incisions prepared in this edentulous region were used to allow proper suture retention and flap stability during the initial phase of healing. In study 1, furcation defects (degree III) were prepared and subsequently treated according to GTR using e-PTFE membranes in the test and no membrane in the control site. In study 2, a bioresorbable membrane (Resolut) was installed in the test and an e-PTFE membrane in the control sites. The non-resorbable membranes were removed after 30 days. The animals were sacrificed 5 months after reconstructive surgery, biopsies were harvested, sectioned and analyzed histologically for new connective tissue attachment and bone.(ABSTRACT TRUNCATED AT 250 WORDS)

Effect of local metronidazole application on periodontal healing following guided tissue regeneration. Microbiological findings

The bacteriological colonization of healing periodontal defects was investigated after treatment with guided tissue regeneration using expanded polytetrafluoroethylene membranes together with local metronidazole gel (25%, 250 mg/g). Twelve patients, each with one pair of comparable defects, had the test defect treated with the membrane plus metronidazole gel and the control defect treated with the membrane alone. Thirty weeks after removal of the membrane, the median gain in probing attachment level as a percentage of the initial defect depth was 92% for the test defects and 50% for the control defects (P = 0.001). The median number of cultivable bacteria decreased from 1.2 x 10(6) at the presurgical examination to 3.0 x 10(5) at the one week examination in the test group (P = 0.02), whereas an increase was observed in the control group. Similarly, a lower median proportion of black-pigmented Gram-negative anaerobic rods was observed one week postsurgically in the test group (0.004%) compared to the control group (3.5%) (P = 0.02). Two weeks after membrane insertion, and at all following examinations, no microbiological differences between test and control group were observed. Consequently, the influence of the metronidazole gel on the treatment result appears to have been confined to the initial regeneration phase. Despite the good clinical results in the test group, all membranes from both test and control pockets were heavily colonized with bacteria at the time of removal. To ensure maximal periodontal regeneration with formation of bone, future research in this area should concentrate on reducing the microbial colonization of the wound area.