Evaluation of anionic collagen membranes in the treatment of class II furcation lesions: an histometric analysis in dogs

Experimental and clinical studies on regenerative periodontal therapy

The recognition of a periodontal therapy as a regenerative procedure requires the demonstration of new cementum, periodontal ligament, and bone coronal to the base of the defect. A diversity of regenerative strategies has been evaluated, including root surface conditioning, bone grafts and bone substitute materials, guided tissue regeneration, enamel matrix proteins, growth/differentiation factors, combined therapies and, more recently, tissue-engineering approaches. The aim of this chapter of Periodontology 2000 is to review the research carried out in Latin America in the field of periodontal regeneration, focusing mainly on studies using preclinical models (animal models) and randomized controlled clinical trials. This review may help clinicians and researchers to evaluate the current status of the therapies available and to discuss the challenges that must be faced in order to achieve predictable periodontal regeneration in clinical practice.

Treatment of periodontal disease with guided tissue regeneration technique using a hydroxyapatite and polycaprolactone membrane

ABSTRACT The aim of this study was to evaluate the use of a malleable membrane composed of hydroxyapatite (60%) and polycaprolactone (40%) as treatment of periodontal disease experimentally induced in dogs. A bone defect of standardized dimensions was created between the roots of the third and fourth premolar of 12 dogs for periodontal disease induction. Six dogs had the defect covered by the membrane and six dogs received only standard treatment for periodontal disease, also applied to dogs in the treated group. The animals were clinically monitored during the experiment. Radiographs were taken after surgery and at 60 days after treatment initiation. Clinical attachment level was also assessed in those moments. On the 60th day, dental sample of all animals, containing tooth, defect and periodontal tissues, were harvested, fixed in formalin and analyzed by microtomography and histology. During the experimental period, the animals showed no pain and purulent discharge, however, there was dehiscence in 50% of animals and membrane exposure in five out of six animals in the treated group. Clinical attachment level showed no difference between groups. Radiographs showed radiopacity equal to the alveolar bone in both groups. The microtomography revealed that the control group had higher bone volume in the defect compared to the treated group; however, the furcation was not filled by new alveolar bone in any animal. Histological analysis revealed that junctional epithelium invasion was lighter in the control group. New bone was only observed in the apical edge of the defect in both groups. Although the composite is biocompatible and able to keep the space of the defect, it did not promote periodontal tissue regeneration within 60 days of observation.

Combination of Bioactive Polymeric Membranes and Stem Cells for Periodontal Regeneration: In Vitro and In Vivo Analyses

Regeneration of periodontal tissues requires a concerted effort to obtain consistent and predictable results in vivo. The aim of the present study was to test a new family of bioactive polymeric membranes in combination with stem cell therapy for periodontal regeneration. In particular, the novel polyester poly(isosorbide succinate-co-L-lactide) (PisPLLA) was compared with poly(L-lactide) (PLLA). Both polymers were combined with collagen (COL), hydroxyapatite (HA) and the growth factor bone morphogenetic protein-7 (BMP7), and their osteoinductive capacity was evaluated via in vitro and in vivo experiments. Membranes composed of PLLA/COL/HA or PisPLLA/COL/HA were able to promote periodontal regeneration and new bone formation in fenestration defects in rat jaws. According to quantitative real-time polymerase chain reaction (qRT-PCR) and Alizarin Red assays, better osteoconductive capacity and increased extracellular mineralization were observed for PLLA/COL/HA, whereas better osteoinductive properties were associated with PisPLLA/COL/HA. We concluded that membranes composed of either PisPLLA/COL/HA or PLLA/COL/HA present promising results in vitro as well as in vivo and that these materials could be potentially applied in periodontal regeneration.

Guided tissue regeneration using rigid absorbable membranes in the dog model of chronic furcation defect

OBJECTIVE

Absorbable membranes are used to promote the regeneration of periodontal defects by Guided Tissue Regeneration (GTR). However, their collapse into the defect is commonly reported, impairing regeneration. Therefore, absorbable but rigid membranes aiming at preventing such collapse were developed and analyzed in periodontal regeneration.

MATERIALS AND METHODS

Membranes were analyzed in class II furcation defects in dogs; procedures included periodontal disease induction, prophylaxis and GTR (treated groups) or open flap debridement alone (control group). For GTR, the membranes were made of either 25% hydroxyapatite (HA) in polyhydroxybutyrate matrix (PHB) or 35% HA in PHB. Animals were clinically evaluated for gingival recession, clinical attachment level (CAL) and biopsies were collected at 60 and 120 days. Bone volume, trabeculae number, trabecular thickness and trabecular separation were quantified by micro-computed tomography, followed by histology.

RESULTS

Membrane exposure was observed in both treated groups (25 and 35% HAP) from the 8(th) day after surgery, continuously progressing until 120 days. Mean CAL for all groups remained above normal values for dogs. Bone volumetric values were not significantly different. Partial formation of bone, cementum and periodontal ligament was observed in treated groups. An inflammatory infiltrate was observed in the dense connective tissue that partially filled the center of the treated defects with active osteoclasts on bone surface.

CONCLUSION

Although partial regeneration of the defect was observed, it was limited by wound contamination. Consequently, rigid absorbable membranes made of HA and PHB failed to improve the regeneration of class II furcation defects in dogs.

Magnetic bioactive glass ceramic in the system CaO-P2O5-SiO2-MgO-CaF2-MnO2-Fe2O3 for hyperthermia treatment of bone tumor

Magnetic bioactive glass ceramic (MG) in the system CaO-SiO(2)-P(2)O(5)-MgO-CaF(2)-MnO(2)-Fe(2)O(3) for hyperthermia treatment of bone tumor was synthesized. The phase composition was investigated by XRD. The magnetic property was measured by VSM. The in vitro bioactivity was investigated by simulated body fluid (SBF) soaking experiment. Cell growth on the surface of the material was evaluated by co-culturing osteoblast-like ROS17/2.8 cells with materials for 7 days. The results showed that MG contained CaSiO(3) and Ca(5)(PO(4))(3)F as the main phases, and MnFe(2)O(4) and Fe(3)O(4) as the magnetic phases. Under a magnetic field of 10,000 Oe, the saturation magnetization and coercive force of MG were 6.4 emu/g and 198 Oe, respectively. After soaking in SBF for 14 days, hydroxyapatite containing CO(3)(2-) was observed on the surface of MG. The experiment of co-culturing cells with material showed that cells could successfully attach and well proliferate on MG.

Periodontal regeneration using a bilayered PLGA/calcium phosphate construct

The regeneration of tissues affected by periodontal disease is a complex process; it encompasses the formation of bone, cementum and periodontal ligament. We developed a semi-rigid PLGA (polylactide-co-glycolide acid)/CaP (calcium phosphate) bilayered biomaterial construct to promote periodontal regeneration, which has a continuous outer barrier membrane and an inner topographically complex component. Our experimental model compared periodontal prophylaxis alone with prophylaxis and biomaterial implantation in the treatment of class II furcation defects in dogs. Clinical evaluation, micro-computed tomography, histology and backscattered electron imaging were used for data analysis. Healing occurred uneventfully and bone volumetric values, trabecular number and trabecular thickness were all significantly greater in the treated group; while trabecular separation was significantly greater in the control group. New cementum, bone, and periodontal ligament with Sharpey fibre insertions were only seen in the treated group. Although periodontal regeneration has been reported elsewhere, the advantages of employing our bilayered PLGA + CaP construct are twofold: 1)it did not collapse into the defect; and, 2) its inner side was able to retain the blood clot throughout the buccal defect. The result was greater periodontal regeneration than has previously been reported with traditional flexible membranes.

Different Molecular Weight Chitosan-Based Membranes for Tissue Regeneration

Natural polymers, such as chitosan, obtained from chitin, are been widely studied for use in the tissue regeneration field. This study established a protocol to attain membranes made from this biopolymer, consisting of high or low molecular weight chitosan. The biocompatibility of these membranes was histologically evaluated, comparing them to collagen membrane surgically implanted in rat subcutaneous tissue. Fifteen Holtzmann rats were divided in three experimental groups: High and Low Molecular Weight Chitosan membranes (HMWC and LMWC) and Collagen membranes (C-control group); each of them with three experimental periods: 7, 15 and 30 days. As a result, after the seven days evaluation, the membranes were present and associated with a variable degree of inflammation, and after the 15 and 30 days evaluations, the membranes were absent in all groups. It is concluded that the chitosan-based membranes were successfully attained and presented comparable resorption times to collagen membranes.

Treatment of gingival recession with collagen membrane and DFDBA: a histometric study in dogs

In a previous study, we evaluated the findings related to the use of resorbable collagen membranes in humans along with DFDBA (demineralized freeze-dried bone allograft). The aim of this subsequent study was to histometrically evaluate in dogs, the healing response of gingival recessions treated with collagen membrane + DFDBA (Guided Tissue Regeneration, GTR) compared to a coronally positioned flap (CPF). Two types of treatment were randomly carried out in a split-mouth study. Group 1 was considered as test (GTR: collagen membrane + DFDBA), whereas Group 2 stood for the control (only CPF). The dogs were given chemical bacterial plaque control with 0.2% chlorhexidine digluconate during a 90-day repair period. Afterwards, the animals were killed to obtain biopsies and histometric evaluation of the process of cementum and bone formation, epithelial migration and gingival level. A statistically significant difference was found between groups with a larger extension of neoformed cementum (GTR = 32.72%; CPF = 18.82%; p = 0.0004), new bone (GTR = 23.20%; CPF = 09.90%; p = 0.0401) and with a smaller area of residual gingival recession in the test group (GTR = 50.69%; CPF = 59.73%; p = 0.0055) compared to the control group. The only item assessed that showed no statistical difference was epithelial proliferation on the root surface, with means of 15.14% for the GTR group and 20.34% for the CPF group (p = 0.0890). Within the limits of this study we concluded that the treatment of gingival recession defects with GTR, associating collagen membrane with DFDBA, showed better outcomes in terms of a larger extension of neoformed cementum and bone, as well as in terms of a smaller proportion of residual recessions.

Apatite coating on anionic and native collagen films by an alternate soaking process

The present study focuses on apatite coating on collagen films, with various different densities of carboxyl groups, using an alternate soaking process. Anionic collagen (AC), which has different densities of carboxylic groups compared to native collagen (NC), was obtained by hydrolysis of carboxyamides of asparagine and glutamine residues. From X-ray diffraction analysis, apatite was found to be coated on AC and NC films. Peaks ascribed to apatite were observed at 26 degrees and 32 degrees in the diffraction patterns of hydroxyapatite crystals. The amount of apatite coated on both AC and NC collagen films continued to increase up to 100 reaction cycles. However, there is a significant difference in apatite coating between the two films. The amount of apatite formed on the surface of AC film increased 1.24 times faster than on NC film. The scanning electron photomicrograph images of the mineralized NC and the AC film coatings formed after 100cycles show that regular porous apatite coating had formed within the collagen fibrils. These results suggest that the higher content of carboxyl groups in AC plays an effective role in the heterogeneous nucleation of apatite in the body environment.

Biomineralization of polyanionic collagen–elastin matrices during cavarial bone repair

The polyanionic collagen-elastin matrices (PCEMs) are osteoconductive scaffolds that present high biocompatibility and efficacy in the regeneration of bone defects. In this study, the objective was to determine if these matrices are directly mineralized during the osteogenesis process and their influence in the organization of the new bone extracellular matrix. Samples of three PCEMs, differing in their charge density, were implanted into critical-sized calvarial bone defects created in rats and evaluated from 3 days up to 1 year after implantation. The implanted PCEMs were directly biomineralized by osteoblasts as shown by ultrastructural, histoenzymologic, and morphologic analysis. The removal of the implants occurred during the bone remodeling process. The organization of the new bone matrix was evaluated by image texture analysis determining the Shannon's entropy and the fractal dimension of digital images. The bone matrix complexity decreased as the osteogenesis progressed approaching the values obtained for the original bone structure. These results show that the PCEMs allow faster formation of new bone by direct biomineralization of its structure and skipping the biomaterial resorption phase.

Growth factor delivery for oral and periodontal tissue engineering

The treatment of oral and periodontal diseases and associated anomalies accounts for a significant proportion of the healthcare burden, with the manifestations of these conditions being functionally and psychologically debilitating. Growth factors are critical to the development, maturation, maintenance and repair of craniofacial tissues, as they establish an extracellular environment that is conducive to cell and tissue growth. Tissue-engineering principles aim to exploit these properties in the development of biomimetic materials that can provide an appropriate microenvironment for tissue development. These materials have been constructed into devices that can be used as vehicles for delivery of cells, growth factors and DNA. In this review, different mechanisms of drug delivery are addressed in the context of novel approaches to reconstruct and engineer oral- and tooth-supporting structures, namely the periodontium and alveolar bone.

Orthodontic movement after periodontal regeneration of class II furcation: a pilot study in dogs

PURPOSE

The effect of orthodontic movement on the periodontal tissues of maxillary second pre-molars, after regenerative treatment for class II furcations, was evaluated in four mongrel dogs.

MATERIAL AND METHODS

Class II furcation lesions were created. After 75 days they were treated with bovine bone mineral matrix and guided tissue regeneration with absorbable membrane. After 2 months of daily plaque control, each of the dog's furcation pre-molars was randomly assigned to a test or control group. Orthodontic appliances were placed on both sides of the maxilla using third pre-molars and canines as anchorages. In the test group, bodily orthodontic movement of the second pre-molars was performed in the mesial direction for 3 months while control pre-molars remained unmoved. The dogs were sacrificed for histometric and histologic analyses.

RESULTS

There were no statistically significant differences between the two groups in total bone and biomaterial areas or linear extension of periodontal regeneration on the radicular surfaces. In the test group, however, there was a tendency to a greater quantity of bone and a lesser quantity of biomaterial.

CONCLUSION

The orthodontic movement was not pre-judicial to the results obtained with the regenerative periodontal treatment.

Autogenous Bone Graft With or Without a Calcium Sulfate Barrier in the Treatment of Class II Furcation Defects: A Histologic and Histometric Study in Dogs

BACKGROUND

The purpose of this study was to histologically evaluate the healing of surgically created Class II furcation defects treated using an autogenous bone (AB) graft with or without a calcium sulfate (CS) barrier.

METHODS

The second, third, and fourth mandibular premolars (P2, P3, and P4) of six mongrel dogs were used in this study. Class II furcation defects (5 mm in height x 2 mm in depth) were surgically created and immediately treated. Teeth were randomly divided into three groups: group C (control), in which the defect was filled with blood clot; group AB, in which the defect was filled with AB graft; and group AB/CS, in which the defect was filled with AB graft and covered by a CS barrier. Flaps were repositioned to cover all defects. The animals were euthanized 90 days post-surgery. Mesio-distal serial sections were obtained and stained with either hematoxylin and eosin or Masson's trichrome. Histometric, using image-analysis software, and histologic analyses were performed. Linear and area measurements of periodontal healing were evaluated and calculated as a percentage of the original defect. Percentage data were transformed into arccosine for statistical analysis (analysis of variance; P <0.05).

RESULTS

Periodontal regeneration in the three groups was similar. Regeneration of bone and connective tissue in the furcation defects was incomplete in most of the specimens. Statistically significant differences were not found in any of the evaluated parameters among the groups.

CONCLUSION

Periodontal healing was similar using surgical debridement alone, AB graft, or AB graft with a CS barrier in the treatment of Class II furcation defects.

Histomorphometric evaluation of human sinus floor augmentation healing responses to placement of calcium phosphate or Ricinus communis polymer associated with autogenous bone

BACKGROUND

Prosthetic rehabilitation of the posterior maxilla with dental implants is often difficult because of proximity to the maxillary sinus and insufficient bone height. Maxillary sinus floor augmentation procedures aim to obtain enough bone with an association between biomaterials and autogenous bone.

PURPOSE

The purpose of this study was to evaluate histomorphometrically two grafting materials (calcium phosphate and Ricinus communis polymer) used in maxillary sinus floor augmentation associated with autogenous bone.

MATERIALS AND METHODS

Biopsies were taken from 10 consecutive subjects (mean age 45 years) 10 months after maxillary sinus floor augmentation. The sinus lift was performed with a mixture of autogenous bone and R. communis polymer or calcium phosphate in a 1:2 proportion. Routine histologic processing and staining with hematoxylin and eosin were performed.

RESULTS

The histomorphometric analysis indicated satisfactory regenerative results in both groups for a mean of bone tissue in the grafted area (44.24 +/- 13.79% for the calcium phosphate group and 38.77 +/- 12.85% for the polymer group). Histologic evaluation revealed the presence of an inflammatory infiltrate of mononuclear prevalence that, on average, was nonsignificant. The histologic sections depicted mature bone with compact and cancellous areas in both groups.

CONCLUSION

The results indicated that both graft materials associated with the autogenous bone were biocompatible, although both were still present after 10 months.

A resin-modified glass ionomer cement barrier for treating degree II furcation defects: a pilot study in dogs

OBJECTIVE

The aim of this study was to evaluate in an animal model the healing of degree II furcation defects treated with: an experimental barrier of resin-modified glass-ionomer cement (GIC), a polylactic acid barrier (GUI), and flap surgery (CTR).

MATERIAL AND METHODS

In 3 beagles, 18 class II furcation defects were surgically produced in mandibular and maxillary premolars and exposed to plaque accumulation for 21 days. Following a full flap, notches were made at the base to the bone defect. GIC barriers were prepared immediately before use from a commercial product and fit to place with the same product. The GIC barriers were removed after 30 days and the dogs euthanized after 120 days. Histologic sections were analyzed in a computer-assisted microscope. Epithelium, new cementum with inserting fibers, and connective tissue lining the root surface in-between notches were measured and medians of percentage values calculated.

RESULTS

In the GIC, epithelium constituted 3.5% (median values) of the notch-to-notch root area; new cementum was 83.6% and connective tissue 12.9%. These values were 0%, 73.6%, and 26.4% for the GUI group and 35.6%, 43.2%, and 0% for the CTR group. Bone fill median values were 54.3% for GIC, 20.6% for GUI, and 24.6% for CTR.

CONCLUSION

GIC and GUI prevented epithelial migration and promoted the formation of new periodontal tissues in experimentally induced class II furcation defects in dogs.

Mistura de proteínas morfogenéticas ósseas, hidroxiapatita, osso inorgânico e colágeno envolta por membrana de pericárdio no preenchimento de defeito ósseo segmentar em coelhos

Avaliou-se o uso de biomaterial de origem bovina na regeneração de defeitos ósseos segmentares empregando-se 12 coelhos, fêmeas, da raça Norfolk, com idade de seis meses e pesos entre 3 e 4,5kg. Realizou-se falha segmentar bilateral de um centímetro de comprimento na diáfise do rádio, com inclusão do periósteo. No membro direito, o defeito foi delimitado por membrana de pericárdio liofilizada, contendo em seu interior mistura de proteínas morfogenéticas ósseas adsorvidas a hidroxiapatita, colágeno liofilizado e osso inorgânico. No membro esquerdo, o defeito não recebeu tratamento. Radiografias foram obtidas ao término do procedimento cirúrgico e aos sete, 30, 60, 90, 120 e 150 dias de pós-operatório. Após eutanásia de seis coelhos aos 60 dias e seis aos 150 dias de pós-cirúrgico, os resultados radiográficos e histológicos mostraram que a regeneração óssea foi inibida nos defeitos segmentares tratados com o biomaterial.

Enamel matrix proteins associated with GTR and bioactive glass in the treatment of class III furcation in dogs

This study investigated, both histologically and histometrically, the efficacy of enamel matrix derived proteins (EMD) associated with bioactive glass (BG) and an absorbable membrane in the treatment of class III furcation defects in mongrel dogs. After surgical defect creation and chronification, the lesions were randomly divided into three groups according to the treatment employed: Test Group 1 - EMD + BG + membrane, Test Group 2 - EMD + membrane and Control Group - BG + membrane. After a 90-day healing period, the dogs were sacrificed. The descriptive analysis and the histometric data showed similar results for the experimental groups in all studied parameters (MANOVA, p > 0.05). The association of Emdogain® with bioglass and GTR, or with GTR only, showed similar results when compared with the ones obtained with bioglass associated with membrane in the treatment of class III furcation defects in dogs. The three modalities of treatment showed partial filling of the furcations, with bone and cementum regeneration limited to the apical portion of the defects.

Histomorphometrical analysis of bone formed after maxillary sinus floor augmentation by grafting with a combination of autogenous bone and demineralized freeze-dried bone allograft or hydroxyapatite

BACKGROUND

Maxillary sinus floor augmentation procedures are currently the treatment of choice when the alveolar crest of the posterior maxilla is insufficient for dental implant anchorage. This procedure aims to obtain enough bone with biomaterial association with the autogenous bone graft to create volume and allow osteoconduction. The objective of this study was to histologically and histometrically evaluate the bone formed after maxillary sinus floor augmentation by grafting with a combination of autogenous bone, from the symphyseal area mixed with DFDBA or hydroxyapatite.

METHODS

Ten biopsies were taken from 10 patients 10 months after sinus floor augmentation using a combination of 50% autogenous bone plus 50% demineralized freeze-dried bone allograft (DFDBA group) or 50% autogenous bone plus 50% hydroxyapatite (HA group). Routine histological processing and staining with hematoxylin and eosin and Masson's trichrome were performed.

RESULTS

The histomorphometrical analysis indicated good regenerative results in both groups for the bone tissue mean in the grafted area (50.46+/-16.29% for the DFDBA group and 46.79+/-8.56% for the HA group). Histological evaluation revealed the presence of mature bone with compact and cancellous areas in both groups. The inflammatory infiltrate was on average nonsignificant and of mononuclear prevalence. Some biopsies showed blocks of the biomaterial in the medullary spaces close to the bone wall, with absence of osteogenic activity.

CONCLUSIONS

The results indicated that both DFDBA and HA associated with an autogenous bone graft were biocompatible and promoted osteoconduction, acting as a matrix for bone formation. However, both materials were still present after 10 months.

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.

Treatment of gingival recession: comparative study between subepithelial connective tissue graft and guided tissue regeneration

BACKGROUND

Various procedures have been proposed to treat gingival recession, but few studies compare these procedures to each other. The purpose of this study was to evaluate a clinical comparison of subepithelial connective tissue graft (SCTG) and guided tissue regeneration (GTR) with a collagen membrane in the treatment of gingival recessions in humans.

METHODS

Twenty-four defects were treated in 12 patients who presented canine or pre-molar Miller Class I and/or II bilateral gingival recessions. Both treatments were performed in all patients, and clinical measurements were obtained at baseline and 18 months after surgery. These clinical measurements included gingival recession height (GR), root coverage (RC), probing depth (PD), keratinized tissue width (KT), and final esthetic result.

RESULTS

Both SCTG and GTR with a bioabsorbable membrane and bone graft demonstrated significant clinical and esthetic improvement for gingival recession coverage. The SCTG group was statistically significantly better than GTR for height of GR (SCTG = 0.2 mm, GTR = 1.12 mm, P= 0.02) and KT (SCTG = 4.58 mm, GTR = 2.5 mm, P<0.0001). However, PD was statistically significantly better for GTR than SCTG treatment (GTR = 1.66 mm, SCTG = 1.00, P= 0.01). The 2 procedures were statistically similar in root coverage (SCTG = 95.6%, GTR = 84.2%, P= 0.073). The esthetic condition after both treatments was satisfactory (P= 0.024).

CONCLUSIONS

It was concluded that the gingival recessions treated with the SCTG group were superior for GR, RC, and KT clinical parameters, while GTR demonstrated better PD reduction. The final esthetic results were similar using both techniques.

Regeneration of Class III furcation defects with basic fibroblast growth factor (b-FGF) associated with GTR. A descriptive and histometric study in dogs

BACKGROUND

The poor predictability of periodontal regenerative treatment of Class III furcation defects stimulates the study of alternatives to improve its results, such as the use of polypeptide growth factors. The objective of this study was to evaluate, both histologically and histometrically, the effects of topical application of basic fibroblast growth factor (b-FGF) associated with guided tissue regeneration (GTR) in the treatment of Class III defects surgically induced in dogs.

METHODS

All second and fourth premolars of 5 mongrel dogs were used and randomly assigned to one of three treatment groups: group 1 (control), treated with scaling and root planing, tetracycline hydrochloride (125 mg/ml) conditioning, and GTR with a collagen membrane; group 2, same treatment as group 1 plus 0.5 mg of b-FGF; group 3, same treatment as group 1 plus 1.0 mg of b-FGF. After a 90-day healing period, routine histologic processing and staining with hematoxylin and eosin and Masson trichrome were performed.

RESULTS

The descriptive analysis indicated better regenerative results in both groups treated with b-FGF while the histometric data, analyzed by means of analysis of variance (ANOVA), showed greater filling of the defects in group 2 in comparison to the defects in groups 3 and 1, respectively, which was represented by a smaller area of plaque-occupied space (P = 0.004) as well as a greater amount of newly formed cementum (P = 0.002).

CONCLUSIONS

These results indicate that b-FGF, especially in smaller doses, may enhance the regenerative results in Class III furcation lesions, leading to greater filling of these defects with both mineralized and non-mineralized tissues.

Preparation and characterization of collagen-elastin matrices from blood vessels intended as small diameter vascular grafts

This study describes the selective removal of cell and cell residues from small and large diameter blood vessels for the preparation of tubular collagen:elastin matrices intended for small diameter vascular prosthesis. The results showed that total or partially devitalized collagen:elastin matrices may be conveniently prepared without denaturation of the collagen:elastin matrix with a high degree of preservation of the proteins. The efficiency of cell removal and the extent collagen and elastic fiber preservation were dependent on the segment and the type of blood vessel under study, with arteries characterized by a higher susceptibility of cell removal and better preservation of the collagen-elastin matrix.

Evaluation of porous collagen membrane in guided tissue regeneration

Porous collagen membrane was prepared with collagen protein, which was extracted from bovine tendon by enzyme digestion, by freeze-drying method. The animal, clinical experiments of the membrane used in artificial dental implant system were studied. In the animal experiments, pure titanium spiral implants, which were prepared according to Adell etc. method, were implanted in the mandibular dental alveus of adult hybrid dog and covered with collagen membrane. Then the animals were killed after 4, 18 weeks individually. In the clinical research, the implants (phi 3.3 mm) were used in 33 patients of different age groups. The implant was put on the buccal lateral deficiency of implantation cavity wall, and covered with collagen membrane on the buccal lateral, then observed after 3, 6 months individually. The results of animal experiments proved the collagen membrane could guide osseous tissue regeneration around the bone integral implant which was implanted in the fresh tooth extraction fossa, be helpful to repair the fissural bone deficiency produced when implanted the implant, increase the bone content around the implant significantly, and improve the structure of new bone to a certain extent. The results of clinical research proved that collagen membrane was used in the patients with density deficiency, irregularity of alveolar ridge, or artificial dental of shorter tooth extraction, could significantly improved the bone density of artificial implant's shoulder.

Anionic collagen: polymer composites with improved dielectric and rheological properties

This work describes the preparation and characterization of anionic collagen composites with rhamsan and vinylidene fluoride-trifluorethylene with improved rheological and dielectric properties without loss of collagen secondary structure with an interaction occurring between both macromolecules of the composites. On a comparative basis, the force needed for the extrusion of anionic collagen:rhamsan composites was in the range from 0.088 to 0.080 J compared to that for collagen of 0.189 J. Anionic collagen:vinylidene fluoride-trifluorethylene composites were characterized, in the case of the 1:1 composite, by a pyroelectric coefficient of 1.89 x 10(-4) cm(-2) K(-1), which was significantly higher than those determined under the same conditions for native anionic collagen and vinylidene fluoride-trifluorethylene.