Interspecies Comparison of Alveolar Bone Biology, Part I: Morphology and Physiology of Pristine Bone.

INTRODUCTION: Few interspecies comparisons of alveolar bone have been documented, and this knowledge gap raises questions about which animal models most accurately represent human dental conditions or responses to surgical interventions. OBJECTIVES: The objective of this study was to employ state-of-the-art quantitative metrics to directly assess and compare the structural and functional characteristics of alveolar bone among humans, mini pigs, rats, and mice. METHODS: The same anatomic location (i.e., the posterior maxillae) was analyzed in all species via micro-computed tomographic imaging, followed by quantitative analyses, coupled with histology and immunohistochemistry. Bone remodeling was evaluated with alkaline phosphatase activity and tartrate-resistant acid phosphatase staining to identify osteoblast and osteoclast activities. In vivo fluorochrome labeling was used as a means to assess mineral apposition rates. RESULTS: Collectively, these analyses demonstrated that bone volume differed among the species, while bone mineral density was equal. All species showed a similar density of alveolar osteocytes, with a highly conserved pattern of collagen organization. Collagen maturation was equal among mouse, rat, and mini pig. Bone remodeling was a shared feature among the species, with morphologically indistinguishable hemiosteonal appearances, osteocytic perilacunar remodeling, and similar mineral apposition rates in alveolar bone. CONCLUSIONS: Our analyses demonstrated equivalencies among the 4 species in a plurality of the biological features of alveolar bone. Despite contradictory results from older studies, we found no evidence for the superiority of pig models over rodent models in representing human bone biology. KNOWLEDGE TRANSFER STATEMENT: Animal models are extensively used to evaluate bone tissue engineering strategies, yet there are few state-of-the-art studies that rigorously compare and quantify the factors influencing selection of a given animal model. Consequently, there is an urgent need to assess preclinical animal models for their predictive value to dental research. Our article addresses this knowledge gap and, in doing so, provides a foundation for more effective standardization among animal models commonly used in dentistry.

Treatment of full thickness focal cartilage lesions with a metallic resurfacing implant in a sheep animal model, 1 year evaluation.

BACKGROUND: Full depth focal cartilage lesions do not heal spontaneously and while some of these lesions are asymptomatic they might progress to osteoarthritis. Treatment for these lesions is warranted and the gold standard treatment at younger age remains biological healing by cell stimulation. In the middle-age patient the success rate of biologic treatment varies, hence the surge of non-biological alternatives. Our objective was to evaluate the efficacy and safety of a metallic implant for treatment of these lesions with respect to the long-term panarticular cartilage homeostasis. METHODS: The medial femoral condyle of 16 sheep was operated unilaterally. A metallic implant was inserted in the weight-bearing surface at an aimed height of 0.5 mm recessed. Euthanasia was performed at 6 or 12 months. Implant height and tilt was analyzed using a laser-scanning device. Damage to cartilage surfaces was evaluated macroscopically and microscopically according to the Osteoarthritis Research Society International (OARSI) recommendations. RESULTS: Thirteen sheep were available for evaluation and showed a varying degree of cartilage damage linearly increasing with age. Cartilage damage of the medial tibial plateau opposing the implant was increased compared to the non-operated knee by 1.77 units (p = 0.041; 95% CI: 0.08, 3.45) on a 0-27 unit scale. Remaining joint compartments were unaffected. Implant position averaged 0.54 recessed (95% CI: 0.41, 0.67). CONCLUSIONS: Our results showed a consistent and accurate placement of these implants at a defined zone. At this position cartilage wear of opposing and surrounding joint cartilage is limited. Thus expanded animal and human studies are motivated.

Fixation of a double-coated titanium-hydroxyapatite focal knee resurfacing implant: a 12-month study in sheep.

OBJECTIVE: Focal cartilage lesions according to International Cartilage Repair Society (ICRS) grade 3-4 in the medial femoral condyle may progress to osteoarthritis. When treating such focal lesions with metallic implants a sound fixation to the underlying bone is mandatory. We developed a monobloc unipolar cobalt-chrome (Co-Cr) implant with a double coating; first a layer of commercially pure titanium (c.p.Ti) on top of which a layer of hydroxyapatite (HA) was applied. We hypothesised that such a double coating would provide long-lasting and adequate osseointegration. DESIGN (MATERIALS AND METHODS): Unilateral medial femoral condyles of 10 sheep were operated. The implants were inserted in the weight-bearing surface and immediate weight-bearing was allowed. Euthanasia was performed at 6 (three animals) or 12 months (six animals). Osseointegration was analysed with micro-computer tomography (CT), light microscopy and histomorphometric analyses using backscatter scanning electron microscopy (B-SEM) technique. RESULTS: At 6 months one specimen out of three showed small osteolytic areas at the hat and at 12 months two specimens out of six showed small osteolytic areas at the hat, no osteolytical areas were seen around the peg at any time point. At both time points, a high total bone-to-implant contact was measured with a mean (95% confidence interval - CI) of 90.6 (79-102) at 6 months and 92.3 (89-95) at 12 months, respectively. CONCLUSIONS: A double coating (Ti + HA) of a focal knee resurfacing Co-Cr implant was presented in a sheep animal model. A firm and consistent bond to bone under weight-bearing conditions was shown up to 1 year.

Bone quality at the implant site after reconstruction of a local defect of the maxillary anterior ridge with chin bone or deproteinised cancellous bovine bone.

The purpose of this study was to investigate the quality of bone at grafted implant sites in the anterior maxilla. Grafting of these sites was necessary because of insufficient bone volume in a buccopalatinal direction (width at the top of the crest 1-3mm). Reconstruction was performed with chin bone (N=5), chin bone and a resorbable Bio-Gide GBR membrane (N=5) or Bio-Oss spongiosa granules in combination with a Bio-Gide GBR membrane (N=5). Biopsies were taken prior to implantation, i.e. 3 months after grafting with chin bone, and 6 months after grafting with Bio-Oss. Evaluation was done by assessing the histological and histomorphometric characteristics of full-length biopsies taken from the actual implant site. Both areas with non-vital bone and areas with apposition of bone and remodelling phenomena were observed in the chin bone group at the time of placement of the implants. Similar results were observed at implant sites reconstructed with a chin bone graft covered by a membrane. In the chin bone group without and with a GBR membrane, the mean total bone volume (TBV) was 55.2+/-6.8% and 57.7+/-11.5%, respectively; the marrow connective tissue volume (MCTV) was 44.8+/-6.8% and 42.3+/-11.5%, respectively. Remnants of the resorbable GBR membrane were not detected. In the Bio-Oss((R)) group, at implant placement some newly formed bone was observed in the connective tissue surrounding the Bio-Oss((R)) particles (mean TBV (newly formed bone) 17.6+/-14.5%), but most particles were surrounded by connective tissue. No convincing signs of remodelling were observed (mean remaining Bio-Oss volume 40.5+/-9.3%; mean MCTV 41.9+/-13.1%). No implants were lost during follow up (12 months). At the time of placement of the implants the grafting material (either chin bone or Bio-Oss is still not fully replaced by new vital bone. In case of Bio-Oss, most of the grafting material is even still present. Despite these differences, the 1-year clinical results were very good and comparable between the various grafting techniques applied.

Treponema putidum sp. nov., a medium-sized proteolytic spirochaete isolated from lesions of human periodontitis and acute necrotizing ulcerative gingivitis.

So far, little phenotypic heterogeneity has been detected in cultured oral treponemes with trypsin-like proteolytic activity, and all have been assigned to the species Treponema denticola. However, comparisons of protein patterns and antigen expression in our collection of proteolytic oral treponemes occasionally identified isolates with a unique phenotype; e.g. strain OMZ 830 (=ATCC 700768), which qualified as a 'pathogen-related oral spirochaete' due to the presence of a approximately 37 kDa protein reactive with the Treponema pallidum FlaA-specific mAb H9-2. In addition to such single isolates, a homogeneous group of seven independent strains is described that were highly motile, medium-sized, proteolytic but asaccharolytic spirochaetes and were cultured from human gingivitis, periodontitis and acute necrotizing ulcerative gingivitis in medium OMIZ-Pat supplemented with 1% human serum and antibiotics. Growth of these spirochaetes in OMIZ-Pat was not dependent on, but was stimulated by, human or bovine serum. Carbohydrates were neither required nor stimulatory for growth. The protein and antigen patterns of total cell extracts of these organisms separated by SDS-PAGE were distinct from those of all previously cultured spirochaetes, with highest similarity to T. denticola. The novel spirochaete has a 2 : 4 : 2 arrangement of the periplasmic flagella, similar to T. denticola. However, the flagellin pattern as detected by immunostaining or glycan staining of Western blots readily distinguished the novel group from T. denticola. Also, distinct from reference strains of T. denticola, none of the novel isolates displayed sialidase or dentilisin activities, both of which are expressed by most strains of T. denticola. Trypsin-like activity and other enzymes as detected by API ZYM test were similar to those of T. denticola. The status of a novel species is supported by the 16S rRNA gene sequence, with 98.5% similarity to its closest cultured relative, T. denticola. The name Treponema putidum sp. nov. is proposed (type strain OMZ 758T=ATCC 700334T=CIP 108088T).

Fissure sealing: optimization of sealant penetration and sealing properties.

PURPOSE: This in vitro study determined the penetration depth of a fissure sealant into an empty fissure system and into a conditioned enamel surface, using different sealing procedures. MATERIALS AND METHODS: 48 extracted, non-carious human molars were sealed with the unfilled sealant (Heliobond) using the enamel adhesive technique (35% phosphoric acid gel, 120 s etching time, bond application, light-curing for 60 s). The following factors were tested in comparison to the control group (1): influence of a precuring time lapse of 20 s after sealant application (2); ultrasound application with a plastic tip during the etching procedure (3); a wetting agent in an acid vehicle (4); enamel drying with acetone after the etching procedure (5); and finally, the combination of ultrasound during etching; a drying procedure with acetone; and a 20 s precuring time lapse (all applied to the same sample). The sealed teeth were sectioned and evaluated by conventional light microscopy to determine the penetration depth into the fissure, and by confocal laser microscopy to investigate the quality of the adhesion zone. RESULTS: Strict adherence to a specified penetration time, an intensified etching procedure with ultrasound, and the use of a drying procedure with acetone each showed a positive effect on the fissure penetration depth of the sealant and on the adhesion zone. The combination of these measures improved significantly the quality of the fissure sealing. Penetration depth increased to 92% of the fissure depth. From 95-100% of the total length of the analyzed adhesion zone shows excellent tags of sealant in the conditioned enamel surface. CLINICAL SIGNIFICANCE: Simple changes in the application technique of fissure sealants, such as ultrasonic treatment during etching procedure and drying the etched fissure system by acetone, improved the quality of the fissure sealing, which is a noninvasive preventive measure.

Alveolar ridge augmentation with Bio-Oss: a histologic study in humans.

The aim of the present study was to investigate the healing of alveolar ridge defects augmented with cancellous bovine bone mineral. In six partially edentulous patients, bone augmentation was necessary prior to implant placement because of severe alveolar ridge resorption. The defect sites, all located in the maxilla, were filled with Bio-Oss and covered with the resorbable collagen membrane Bio-Gide. Biopsies were obtained from the defect sites 6 to 7 months following grafting and were processed for ground sectioning. The histologic analysis revealed that the Bio-Oss particles occupied 31% of the total biopsy area. An intimate contact between woven bone and Bio-Oss was detected along 37% of the particle surfaces. A mixed type of bone was found; it contained woven bone and parallel-fibered bone, which demonstrates features of remodeling activity. Signs of resorption of the grafting material were observed in the histologic sections, which indicates that the material takes part in the remodeling process. It is suggested that Bio-Oss may be a very suitable material for staged localized ridge augmentation in humans.

Treponema parvum sp. nov., a small, glucoronic or galacturonic acid-dependent oral spirochaete from lesions of human periodontitis and acute necrotizing ulcerative gingivitis.

Small oral spirochaetes with a strict dependence on either glucuronic acid (GluA) or galacturonic acid (GalA) were isolated from European patients with periodontitis and from Chinese patients with either gingivitis or acute necrotizing ulcerative gingivitis (ANUG). Thirteen such isolates were similar phenotypically to Treponema pectinovorum ATCC 33768T and this classification was confirmed by 16S rRNA sequencing. However, four isolates differed from T. pectinovorum by their small cell size, by a prominent beta-glucuronidase activity, by a distinct protein and antigen profile, by an inability to grow on pectin as sole source of carbohydrate and by a markedly enhanced growth rate when supplied with a second carbohydrate (L-arabinose, D-galactose, D-glucose, D-fructose, D-mannitol, D-mannose, pectin, D-ribose or D-xylose) in addition to the essential GluA/GalA. By 16S rRNA sequencing these four isolates clustered in the recently described phylotype 'Smibert-2'. T. pectinovorum (14 strains) and 'Smibert-2' (four isolates with beta-glucuronidase activity) could each be subdivided into two serotypes based on immunoblot reactivity with two mAbs. Representatives of the two groups, including T. pectinovorum ATCC 33768T, showed a 1:2:1-type periplasmic flagellar arrangement. 'Smibert-2' is described as a novel species, Treponema parvum sp. nov., with isolate OMZ 833T (= ATCC 700770T) proposed as the type strain and OMZ 842 (= ATCC 700773) as reference strain for a second serotype.

Electron-microscopic demonstration of proline-rich proteins, statherin, and histatins in acquired enamel pellicles in vitro.

Proline-rich proteins (PRPs), histatins, and statherin are salivary proteins that exhibit high affinities for hydroxyapatite surfaces. In vitro experiments with parotid submandibular/sublingual or whole saliva have shown these proteins to adsorb selectively to tooth surfaces. This investigation focuses on the histo-morphological identification of PRPs, histatins, and statherin in acquired enamel pellicles. Synthetic hydroxyapatite or bovine enamel were exposed to glandular secretions, and whole saliva and pellicle precursor proteins were identified immunohistologically by electron microscopy. Results obtained by back-scattered scanning electron microscopy showed these proteins to be present in pellicles. Pellicles displayed a distinct structure consisting of a sponge-like meshwork of microglobules. Interconnections between structural elements were identified in submandibular/sublingual and whole saliva pellicles only. Transmission electron microscopy of pellicles formed on bovine enamel surfaces revealed a tendency for preferential localization of precursor proteins within the protein film. Since the data showed the presence of pellicle precursors in pellicles derived both from glandular secretions and from whole saliva, it is likely that PRPs, histatins, and statherin are integral components of acquired enamel pellicles in vivo.

Validation of an in vitro biofilm model of supragingival plaque.

The study of biofilm structure and function mandates the use of model systems for which a host of environmental variables can be rigorously controlled. We describe a model of supragingival plaque containing Actinomyces naeslundii, Veillonella dispar, Fusobacterium nucleatum, Streptococcus sobrinus, and Streptococcus oralis wherein cells are cultivated anaerobically in a saliva-based medium on hydroxyapatite discs coated with a salivary pellicle, with material and pieces of apparatus common to all microbiology laboratories. After 0.5 hr, 16.5 hrs, 40.5 hrs, and 64.5 hrs, the composition of adherent biofilms was analyzed by culture techniques, live/dead fluorescence staining, and confocal laser scanning microscopy. Repeated independent trials demonstrated the repeatability of biofilm formation after 40.5 hrs and 64.5 hrs. Brief exposures of biofilms to chlorhexidine or Triclosan produced losses in viability similar to those observed in vivo. This biofilm model should prove very useful for pre-clinical testing of prospective anti-plaque agents at clinically relevant concentrations.

Thoracoabdominal aortic repair in a 190-kg patient: optimized perfusion with two oxygenators.

A 190-kg patient was referred because of an acute type B aortic dissection. Conservative management was initially performed but the 34-year-old patient was shown to have an increasing aortic diameter 2 months later and was scheduled for elective repair of the thoracoabdominal aorta. To anticipate potential difficulties with perfusion and oxygenation the cardiopulmonary bypass circuit was constructed with two parallel oxygenators, which allowed an adequate oxygen supply through all phases of the intervention and accelerated the estimated rewarming time.

Treponema lecithinolyticum sp. nov., a small saccharolytic spirochaete with phospholipase A and C activities associated with periodontal diseases.

Strong phospholipase A (PLA) and phospholipase C (PLC) activities as potential virulence factors are the outstanding characteristics of eight strains of small oral spirochaetes isolated from deep periodontal lesions. By qualitative dot-blot DNA-DNA hybridization and 16S rDNA sequence comparison, these spirochaetes form a distinct phylogenetic group, with Treponema maltophilum as its closest cultivable relative. Growth of these treponemes, cells of which contain two endoflagella, one at each pole, was autoinhibited by the PLA-mediated production of lysolecithin unless medium OMIZ-Pat was prepared without lecithin. N-Acetylglucosamine was essential and D-ribose was stimulatory for growth. All isolates were growth-inhibited when 1% foetal calf serum was added to the medium. Growth on agar plates supplemented with human erythrocytes produced haemolysis. In addition to PLA and PLC, the new isolates displayed strong activities of alkaline and acid phosphatases, beta-galactosidase, beta-glucuronidase, N-acetyl-beta-glucosaminidase and sialidase, intermediate activities of C4- and C8-esterases, naphthol phosphohydrolase and alpha-fucosidase and a distinctive 30 kDa antigen detectable on Western blots. This phenotypically and genotypically homogeneous group is proposed as a novel species, Treponema lecithinolyticum sp. nov., with isolate OMZ 684T designated as the type strain. A molecular epidemiological analysis using a T. lecithinolyticum-specific probe showed this organism to be associated with affected sites when compared with unaffected sites of periodontitis patients. This association was more pronounced in patients with rapidly progressive periodontitis than in those with adult periodontitis.

The ultrastructure of a compomer adhesive interface in enamel and dentin, and its marginal adaptation under dentinal fluid as compared to that of a composite.

OBJECTIVES: To visualise the ultrastructure of the interface of SCA compomer adhesive and of Optibond composite adhesive in enamel and dentin, and to relate the findings to the marginal adaptation of these two products in mixed class V restorations. METHODS: The ultrastructure was investigated using a scanning electron microscope (SEM) with and without prior argon ion etching, an environmental SEM, a field emission SEM, a confocal laser scanning microscope, and a transmission electron microscope. The marginal adaptation was quantified in mixed class V restorations by using the replica technique and a SEM under simulated dentinal fluid before and after simultaneous mechanical and thermal loading. RESULTS: The ultrastructure of the compomer adhesive interface differed from those of the composite. However, no significant difference was discerned as regards the percentage of "continuous margin" in the enamel marginal area before loading, and in the dentin area before and after loading (p < 0.05; unpaired t-test). Only after loading, the percentage of "continuous margin" in enamel was significantly (p < 0.05; unpaired t-test) better than that of the compomer. SIGNIFICANCE: The results indicated that the ultrastructure of the adhesive interface allowed no clear conclusions to be drawn as to the quality of marginal adaptation.

Closing of dentinal tubules by Gluma desensitizer.

Gluma Dentin Bond is an adhesive system, where the primer contains 5% glutaraldehyde and 35% hydroxyethyl methacrylate. Practitioners have reported a strong desensitizing effect of the Gluma system on dentin. This study, thus, sought to evaluate the effect of this system on dentin using various microscopic techniques. 12 non-restored human molars extracted for prosthodontic reasons were used. Prior to extraction the buccal cusps were removed such that a 2 mm x 2 mm wide dentin surface was exposed. The surfaces were treated in 6 ways: (1) application of Gluma 2 cleanser, Gluma 3 primer to which 0.1% w/v fluorescein was added, and Gluma 4 sealer; (2) as in (1) but treatment with H2O/0.1% w/v fluorescein instead of the Gluma 3; (3) as in (1) but without Gluma 2; (4) as in (1) but with application of 5% glutaraldehyde instead of Gluma 3; (5) as in (1) but without Gluma 4; (6) as in (1) but with application of 35% HEMA/0.1% w/v fluorescein instead of Gluma 3. Following extraction, 1 tooth per procedure was prepared for confocal laser scanning microscopy. The remaining teeth were fixed and prepared for SEM and TEM evaluation. In specimens of procedures (1) and (5), tubular occlusions could be seen to a depth of 200 microm. In specimens of procedure (4) tubular occlusions were found only to a depth of 50 microm. Such occlusions were not seen in control specimens (2), in specimens where the smear-layer had not been removed (3), or following application of HEMA alone (6). It is concluded that glutaraldehyde can intrinsically block dentinal tubules. The septa in the tubules may counteract the hydrodynamic mechanism for dentinal sensitivity.

Distraction osteogenesis for lengthening of the hard palate: Part II. Histological study of the hard and soft palate after distraction.

To correct velopharyngeal incompetence, a new treatment concept was proposed in Distraction Osteogenesis for Lengthening of the Hard Palate: Part I (using lengthening of the hard and soft palate by distraction osteogenesis). Cephalometry and computed tomography showed successful elongation of the posterior hard palate with gradual calcification. Here the sequential use of fluorochrome markers (oxytetracycline, xylenol orange, DCAF [2,4-bis-N-N'-dicarboxymethyl aminomethyl fluorescein], and alizarin complexone) during the distraction and retention period is reported together with the histologic investigations using light and laser scan microscopy without prior demineralization. The experimental gap showed de novo osteogenesis in all dogs. The new bone was always in continuity with the original anterior and posterior palatal bone margins. It either bridged the experimental gap fully or left a small central zone of fibrous tissue, in which eventual ossification occurred. Several distinct zones could be distinguished: A small central zone was found with parallel strains of collagen fibers, oriented longitudinally in the direction of the distraction. Next to this zone a layer of undifferentiated mesenchymal precursor cells was seen in direct contact to newly formed bone. The next zone was coarse woven bone, showing a transition to mature lamellar bone through remodeling. No evidence of endochondral bone formation was found, i.e., all dogs showed exclusively intramembranous bone formation. The soft tissues showed no signs of alteration: in particular, there was no necrosis or scar formation. The soft tissues were not thinned but appeared to have followed the longitudinal displacement. In conclusion, gradual distraction osteogenesis of the hard palate could be a possible method for lengthening the palate to treat velopharyngeal incompetence.

Dentin bonding: effect of tubule orientation on hybrid-layer formation.

In an attempt to compare the morphology of the resin-dentin interface in areas where the dentinal tubules run perpendicularly or at an angle to the cavity surface with that of areas where they run parallel to it, we studied a dentin adhesive system using transmission electron microscopy and fluorescence confocal laser scanning microscopy. The design of the study included the simulation of the normal hydrostatic pressure within the pulp and the dentinal tubules. Following acid etching of the dentinal surface with maleic acid/HEMA, the smear layer was removed, and a superficial zone was demineralized in such a way that the exposed collagenous dentin matrix retained its integrity. Confocal laser scanning microscopal investigations using primer labeled with rhodamine B showed that the penetration of the primer occurred not only vertically via surface porosities, but mainly laterally, via the dentinal tubules. The adhesive resin labeled with fluorescein completely infiltrated the demineralized layer, thereby forming a hybrid layer. The orientation of the dentinal tubules had a profound effect on the formation of the hybrid layer. In areas with perpendicular tubule orientation, the layer was 3.2 +/- 0.8 microns thick, showing solid 27.2 +/- 0.8 microns long resin tags in the dentinal tubules, and a network of tiny tags in their side-branches. In areas with parallel tubule orientation the layer was significantly thinner (1.3 +/- 0.6 microns) and resin tags were absent.

Guided bone regeneration around dental implants in the atrophic alveolar ridge using a bioresorbable barrier. An experimental study in the monkey.

The aim of this study was to evaluate guided bone regeneration (GBR) around dental implants placed in atrophic alveolar ridges using an experimental, nonporous bioresorbable barrier. In 8 Rhesus monkeys, the maxillary canines and lateral incisors were extracted bilaterally and the remaining alveoli were reduced to create atrophic ridges. After a healing period of 3 months, soft tissue expansion was performed using a subperiosteal tissue expander. After 1 month of tissue expansion, and IMZ implant was placed in the atrophic ridge on each side in such a way that its coronal 4 mm to 5 mm remained circumferentially exposed above the bone level. The test implants were covered with a bioresorbable barrier made of poly (D,L-lactid-co-trimethylencarbonate) in a 70/30 ratio, whereas the control implants were covered with a nonresorbable expanded polytetrafluoroethylene (e-PTFE) barrier. The e-PTFE barriers were stabilized with titanium minipins while the bioresorbable barriers were analogously fixed using bioresorbable minipins made of poly (L-lactid-co-D,L-lactid) 70/30. Clinical healing progressed uneventfully in both groups and no soft tissue dehiscences occurred. Histometric and histomorphometric analyses were performed 5 months post surgery. Both test and control implants exhibited direct bone-to-implant contact to variable extents. The mean direct mineralized bone-to-implant contact length fraction was 32% of the total implant length in the test sites and 58% in the control sites. Control sites exhibited significantly greater bone fill compared to the experimental sites (P < 0.001). Histologic observations of test specimens demonstrated a moderate inflammatory reaction related to the degradation and resorption products of the barrier. In conclusion, the nonresorbable e-PTFE GBR barrier was found to be superior to the bioresorbable barriers tested in the present investigation.

Treponema amylovorum sp. nov., a saccharolytic spirochete of medium size isolated from an advanced human periodontal lesion.

A highly motile, medium-size, saccharolytic spirochete was isolated from an advanced human periodontal lesion in medium OMIZ-Pat supplemented with 1% human serum. The growth of this organism is dependent on either glucose, maltose, starch, or glycogen. The cells contain six endoflagella, three per pole, which overlap in the central region of the cell body. On the basis of its cell morphology and enzyme activities, as well as its sodium dodecyl sulfate-polyacrylamide gel electrophoresis protein and antigen profiles, this organism is clearly distinct from all previously cultured spirochetes. The presence of a novel species is supported by the 16S rRNA sequence of this organism, which places it in phylotype 19 of Choi et al. (B. K. Choi, B. J. Paster, F. E. Dewhirst, and U. B. Göbel, Infect. Immun. 62:1889-1895, 1994). The only isolate, strain HA2P, is designated the type strain of a novel species, for which we propose the name Treponema amylovorum.

Guided periodontal tissue regeneration in interproximal intrabony defects following treatment with a synthetic bioabsorbable barrier.

This study evaluated guided periodontal tissue regeneration (GPTR) wound healing in interproximal intrabony periodontal defects following surgical treatment with a synthetic bioabsorbable barrier made from a copolymer of glycolide and lactide. Periodontal lesions were induced around the mandibular central incisor teeth of 10 adult male rhesus monkeys using orthodontic elastics. Once similar contralateral interproximal defects had been created, the elastics were removed and an oral hygiene program was initiated and maintained until completion of the study. Three weeks after commencing oral hygiene, flap surgery was performed in the mandibular incisor region and the root surfaces were thoroughly scaled and root planed to the apical portion of the defects. On the test sites, a bioabsorbable barrier was placed over the entire interproximal periodontal defect. Control sites did not receive a barrier. Five months after surgery, the animals were sacrificed and the teeth with their supporting periodontium were processed for light microscopic evaluation. Postoperative clinical healing progressed uneventfully and was similar in both control and test sites. Histologic observations from control specimens indicated reparative healing characterized by a long junctional epithelium with limited cementum and bone formation. Test specimens exhibited significantly more new connective tissue attachment, cementum deposition, and bone formation than the control sites (P < 0.001). The barriers had been completely resorbed with no apparent adverse effect on periodontal wound healing. It was concluded that this bioabsorbable barrier facilitated GPTR wound healing in interproximal intrabony periodontal defects.