Fretibacterium fastidiosum gen. nov., sp. nov., isolated from the human oral cavity.

SGP1(T), a strain belonging to a lineage of the phylum Synergistetes with no previously cultivated representatives was subjected to a comprehensive range of phenotypic and genotypic tests. For good growth the strain was dependent on co-culture with, or extracts from, selected other oral bacteria. Cells of strain SGP1(T) were asaccharolytic and major amounts of acetic acid and moderate amounts of propionic acid were produced as end products of metabolism in peptone-yeast extract-glucose broth supplemented with a filtered cell sonicate of Fusobacterium nucleatum subsp. nucleatum ATCC 25586(T) (25 %, v/v). Hydrogen sulphide was produced and gelatin was weakly hydrolysed. The major cellular fatty acids were C(14 : 0), C(18 : 0) and C(16 : 0). The DNA G+C content of strain SGP1(T) was 63 mol%. Phylogenetic analysis of the full-length 16S rRNA gene showed that strain SGP1(T) represented a novel group within the phylum Synergistetes. A novel species in a new genus, Fretibacterium fastidiosum gen. nov., sp. nov., is proposed. The type strain of Fretibacterium fastidiosum is SGP1(T) ( = DSM 25557(T) = JCM 16858(T)).

A prospective clinical trial of single Astra Tech 4.0 or 5.0 diameter implants used to support two-unit cantilever bridges: results after 3 years.

OBJECTIVE: To evaluate the use of a single Astra Tech implant to support a two-unit cantilever fixed dental prosthesis. MATERIALS AND METHOD: Twenty-nine subjects with an edentulous space (at least equivalent to two bicuspid units) in the premolar/molar segments of the maxilla or mandible with opposing natural teeth or a fixed/removable prosthesis were treated. They were provided with either a 4 or 5.0 mm diameter fixture MT OsseoSpeed. Prostheses were constructed using a cast-to abutment as a one-piece unit with porcelain fused to precious metal to allow direct screw retention. RESULTS: Subjects expressed a high satisfaction with treatment, including appearance and function. The most important complication was abutment screw loosening. It occurred as a single episode in four subjects and in another six subjects the loosening was recurrent. Bone levels were stable and there were no significant differences in radiographic bone height between cantilever and non-cantilever sides of the implant at any time point. CONCLUSION: Single implants can be successfully used to support two-unit cantilever FDPs in the premolar region. A common factor could not be identified in relation to abutment screw loosening.

Effect of rinsing with ethanol-containing mouthrinses on the production of salivary acetaldehyde.

It has been suggested that the use of alcohol-containing mouthrinses could lead to the presence of acetaldehyde in saliva. In this cross-over study, salivary acetaldehyde levels and microbial profiles were determined before and after rinsing with ethanol-containing mouthrinses with essential oils (EO) and cetyl pyridinium chloride (CPC) as the active ingredients, and with 21.6% ethanol and water controls. After rinsing with all ethanol-containing rinses, acetaldehyde was detected in saliva after 30 s but declined to low levels after 5 min. The highest peak levels were seen with the ethanol control (median = 82.9 µM at 2 min) and were significantly higher than those seen at the same time after rinsing with the EO rinse (43.1 µM). There was no correlation between microbial counts or plaque scores and acetaldehyde levels, although dividing the subjects on the basis of a peak acetaldehyde salivary concentration of > 90.8 µM after the ethanol rinse revealed that the high responders were highly significantly more likely to harbour salivary yeasts than were the low responders. Rinsing with ethanol-containing mouthrinses causes a rapid, but transient, increase in salivary acetaldehyde levels.

Modification of thiol functionalized aptamers by conjugation of synthetic polymers.

Aptamers are known for their short in vivo circulating half-life and rapid renal clearance. Their conjugation to poly(ethylene glycol) (PEG) is a way to improve their residence in the body. Two aptamers (AptD and AptF), having a disulfide protected thiol modification on the 3' end, have been conjugated to maleimide activated PEGs of various molecular weights and structures (linear PEG20; branched PEG20 and 40; PolyPEG17, 40, and 60 kDa). The high yield coupling (70-80% in most of the cases) could be achieved using immobilized tris[2-carboxyethyl]phosphine hydrochloride (TCEP) as reducing agent at pH 4. The affinity of PEGylated AptD for its target was reduced by conjugation to linear PEG20 and branched PEG40, but not to branched PEG20 and PolyPEGs. This work demonstrates an alternative approach to PEGylation of aptamers, and that the effect of PEG on the affinity for the target varies according to the structure and conformation of the synthetic polymer.

Accuracy of measuring the cortical bone thickness adjacent to dental implants using cone beam computed tomography.

OBJECTIVE: To assess the accuracy of measuring the cortical bone thickness adjacent to dental implants using two cone beam computed tomography (CBCT) systems. MATERIAL AND METHODS: Ten 4 x 11 mm Astra Tech implants were placed at varying distances from the cortical bone in two prepared bovine ribs. Both ribs were scanned in a reproducible position using two different CBCT scanners. Ten examiners each carried out four measurements on all 10 implants using the two CBCT systems: vertical distance between the top of the implant and the alveolar crest (IT-AC), and thickness of the cortical bone from the outer surface of the implant threads at 3, 6 and 9 mm from the top of the implant. Ground sections were prepared and bone thickness was measured using a light microscope and a graticule to give a gold standard (GS) measurement. RESULTS: The examiner's measurements were significantly different between CBCT systems for the vertical and thickness dimensions (P<0.001) while measuring the cortical bone thickness between 0.3 and 3.7 mm. Within that range, i-CAT NG measurements were consistently underestimated in comparison with the GS. Accuitomo 3D60 FPD measurements closely approximated the GS, except when cortical bone thickness was <0.8 mm. The mean percentage errors from the GS at 3, 6 and 9 mm measurement levels were 68%, 28% and 18%, respectively, for i-CAT NG and 23%, 5% and 6%, respectively, for Accuitomo 3D60 FPD. CONCLUSIONS: Within the limitations of this study, it was concluded that i-CAT NG (voxel size 0.3) may not produce sufficient resolution of the thin cortical bone adjacent to dental implants and, therefore, the measurements may not be accurate; whereas, Accuitomo 3D60 FPD (voxel size 0.125) may produce better resolution and more accurate measurement of the thin bone.

The decision to extract or retain compromised teeth is not helped by the application of a scoring system.

ARTICLE TITLE AND BIBLIOGRAPHIC INFORMATION: A Novel Decision-Making Process for Tooth Retention or Extraction J Periodontol 2009;80:476-491. Avila G, Galindo-Moreno P, Soehren S, Misch CE, Morelli T, Wang H-L. REVIEWER: Richard M. Palmer, PhD, BDS, FDS RCS PURPOSE/QUESTION: Is it possible to devise a system to help in the decision-making process of tooth extraction/retention based on a critical evaluation of the literature? SOURCE OF FUNDING: University of Michigan Periodontal Graduate Student Research Fund TYPE OF STUDY/DESIGN: Comprehensive literature review LEVEL OF EVIDENCE: Level 3: Other evidence STRENGTH OF RECOMMENDATION GRADE: Not applicable.

The influence of nicotine on granulocytic differentiation - inhibition of the oxidative burst and bacterial killing and increased matrix metalloproteinase-9 release.

BACKGROUND: Neutrophils leave the bone marrow as terminally differentiated cells, yet little is known of the influence of nicotine or other tobacco smoke components on neutrophil differentiation. Therefore, promyelocytic HL-60 cells were differentiated into neutrophils using dimethylsulfoxide in the presence and absence of nicotine (3-(1-methyl-2-pyrrolidinyl) pyridine). Differentiation was evaluated over 5 days by monitoring terminal differentiation markers (CD11b expression and formazan deposition); cell viability, growth phase, kinetics, and apoptosis; assessing cellular morphology and ultrastructure; and conformational changes to major cellular components. Key neutrophil effector functions (oxidative burst, bacterial killing, matrix metalloproteinase release) were also examined. RESULTS: Nicotine increased the percentage of cells in late differentiation phases (metamyelocytes, banded neutrophils and segmented neutrophils) compared to DMSO alone (p < 0.05), but did not affect any other marker of neutrophil differentiation examined. However, nicotine exposure during differentiation suppressed the oxidative burst in HL-60 cells (p < 0.001); inhibited bacterial killing (p < 0.01); and increased the LPS-induced release of MMP-9, but not MMP-2 (p < 0.05). These phenomena may be alpha-7-acetylcholine nicotinic receptor-dependent. Furthermore, smokers exhibited an increased MMP-9 burden compared to non-smokers in vivo (p < 0.05). CONCLUSION: These findings may partially explain the known increase in susceptibility to bacterial infection and neutrophil-associated destructive inflammatory diseases in individuals chronically exposed to nicotine.

Smoking behaviour and attitudes to periodontal health and quit smoking in patients with periodontal disease.

OBJECTIVE: The aim of this study was to assess oral health-related beliefs and attitudes, health behaviour of smokers in relation to the Transtheoretical Model (TTM) of behaviour change, willingness to have smoking cessation provided together with periodontal treatment. MATERIAL AND METHODS: Postal questionnaire was sent to 500 referred patients. Part 1 looked at attitudes and beliefs about periodontal disease, Part 2 aimed at current smokers focused on the TTM and smoking cessation. RESULTS: Response rate was 56% (n=277); 67% females, 33% males. Mean age was 44.9 years (SD 12.45); 24.5% current smokers, 30.3% past smokers, 45.5% never smokers. Fewer smokers reported "bleeding gums" (p=0.027), but more smokers reported "having loose teeth" (p=0.016). The TTM stages of change indicated that 31% of current smokers were in pre-contemplation of quitting smoking, 46% were in contemplation and 23% were in preparation. Twenty-three percent of the past smokers were in action and 77% in maintenance. Smokers showed differences in the "self-re-evaluation" (p=0.001) and "self-liberation" (p=0.015) processes of change depending on their stage of change (pre-contemplation or preparation). Nearly half (49%) of the current smokers who wanted to quit requested smoking cessation to be provided alongside their periodontal treatment. CONCLUSION: A large proportion of periodontal patient smokers may be considering quitting, and nearly half requested provision of smoking cessation intervention in conjunction with the periodontal treatment.

Maintenance of osseointegrated implant prostheses.

UNLABELLED: Implant-retained prostheses need to be re-evaluated on a regular basis. This should include review of the effectiveness of oral hygiene procedures to maintain soft tissue health, evaluation of the integrity and function of the prosthetic superstructure and comparison of radiographic bone levels at appropriate intervals. CLINICAL RELEVANCE: All dental care professionals need to be aware of the maintenance care requirements of patients treated with dental implants. With the increase in numbers of patients treated there will be greater demands to provide this care in general practices.

Immediate and early replacement implants and restorations.

UNLABELLED: There have been rapid developments in dental implant treatment protocols to reduce the time between implant placement and restoration. Implants may be placed immediately following tooth extraction or following a period of healing to allow resolution of residual infection or sufficient bone and soft tissue healing. Early restoration and loading of implants has to be carefully controlled to avoid increased failure and complications. Advantages and disadvantages of the various techniques are described. CLINICAL RELEVANCE: The clinician should adopt a treatment protocol that ensures a high success rate and a long-term functional and aesthetic implant restoration. Rapid treatment protocols can be considered when they do not compromise these goals, and the clinician is sufficiently experienced in their application.

Bone healing after tooth extraction with or without an intervention: a systematic review of randomized controlled trials.

OBJECTIVES: To assess whether the use of a graft and/or membrane post-tooth extraction improves healing of the site dimensionally, radiographically, and/or histologically. MATERIALS AND METHODS: MEDLINE and EMBASE and the Cochrane Central register of controlled trials (CENTRAL) were searched up until August 2011. Randomized controlled trials that included and compared healing post-tooth extraction between a control (no intervention) and a graft and/or membrane (test) were selected. RESULTS: Titles and abstracts of 2,861 papers were screened. A total of 42 papers were selected for full text reading. Nine papers met the eligibility criteria and were selected for further analysis. Because of the varying graft materials used and the different methods of investigation, as well as the variation in follow-up times, a meta-analysis was not possible. The present review found that clinically, there was a range in loss of width in the control sites of 2.46 mm (SD 0.4 mm) to 4.56 mm (SD 0.33 mm) compared to 1.14 mm (SD 0.87 mm) to 2.5 mm (SD 1.2 mm) in the test sites. The range in loss of height in control sites was 0.9 mm (SD 1.6 mm) to 3.6 mm (SD 1.5 mm) compared to a gain of 1.3 mm (SD 2 mm) to a loss of 0.62 mm (SD 0.51 mm) in test sites. Radiographically a range of change in bone height of between 0.51 mm (No SD) to 1.17 mm (SD 1.23 mm) was noted in control sites compared to a change of between 0.02 mm (SD 1.2 mm) and 1 mm (SD 1.4 mm) in test sites. CONCLUSION: There is limited data regarding the effectiveness of alveolar ridge preservation therapies when compared to the control. Overall the socket intervention therapies did reduce alveolar ridge dimensional changes post-extraction, but were unable to prevent resorption. Histology did demonstrate a large proportion of residual graft material that may account for some of the difference in alveolar ridge dimensions at follow up.

Evaluation of a ß-calcium metaphosphate bone Graft containing bone morphogenetic protein-7 in rabbit maxillary defects.

BACKGROUND: Calcium phosphate-based materials have been widely used as bone substitutes and more recently are being exploited together with growth factors as bone tissue engineering scaffolds regulating cell behavior. The aim of this study is to evaluate the in vitro and in vivo response to a newly developed calcium metaphosphate (CMP) bone graft, with and without bone-stimulating growth factor. METHODS: Porous scaffolds of CMP were developed and extensively tested in vitro. Subsequently, CMP grafts with osteogenic protein-1 (OP-1) (test) and without OP-1 (control) were implanted into experimental rabbit maxillary bone defects. Animals were sacrificed at 2, 4, and 8 weeks, and samples were examined with microcomputed tomography (micro-CT) and processed for histomorphometric analysis. RESULTS: At 8 weeks, the scaffolds containing OP-1 induced greater bone formation (P = 0.018) than CMP alone, based on histomorphometric evaluation (percentage bone area: test: 57.1 ± 5.6; control: 49.4 ± 7.7) and micro-CT analysis (percentage bone volume density: test: 63.46 ± 5.61; control: 51.20 ± 6.71). Thus, these data indicated that both test and control CMP grafts showed a good degree of bone formation. Furthermore, the CMP materials showed signs of resorption from 4 weeks, and no graft materials were observed at 8 weeks. CONCLUSIONS: In vitro, the OP-1 loaded graft demonstrated a release profile and bioactivity over a 28-day period. In vivo testing confirmed enhanced bone formation of the OP-1 loaded graft after 8 weeks of healing.

The effects of simulated bone loss on the implant-abutment assembly and likelihood of fracture: an in vitro study.

PURPOSE: The crestal bone level around a dental implant may influence its strength characteristics by offering protection against mechanical failures. Therefore, the present study investigated the effect of simulated bone loss on modes, loads, and cycles to failure in an in vitro model. MATERIALS AND METHODS: Different amounts of bone loss were simulated: 0, 1.5, 3.0, and 4.5 mm from the implant head. Forty narrow-diameter (3.0-mm) implant-abutment assemblies were tested using compressive bending and cyclic fatigue testing. Weibull and accelerated life testing analysis were used to assess reliability and functional life. Statistical analyses were performed using the Fisher-Exact test and the Spearman ranked correlation. RESULTS: Compressive bending tests showed that the level of bone loss influenced the load-bearing capacity of implant-abutment assemblies. Fatigue testing showed that the modes, loads, and cycles to failure had a statistically significant relationship with the level of bone loss. All 16 samples with bone loss of 3.0 mm or more experienced horizontal implant body fractures. In contrast, 14 of 16 samples with 0 and 1.5 mm of bone loss showed abutment and screw fractures. Weibull and accelerated life testing analysis indicated a two-group distribution: the 0- and 1.5-mm bone loss samples had better functional life and reliability than the 3.0- and 4.5-mm samples. CONCLUSION: Progressive bone loss had a significant effect on modes, loads, and cycles to failure. In addition, bone loss influenced the functional life and reliability of the implant-abutment assemblies. Maintaining crestal bone levels is important in ensuring biomechanical sustainability and predictable long-term function of dental implant assemblies.

The effect of smoking on periodontal bone regeneration: a systematic review and meta-analysis.

BACKGROUND: The effect of smoking on soft tissues after periodontal treatment has been extensively studied. However, little focus has been placed on the impact of smoking on bone regeneration after treatment. The aim of this review is to systematically assess the effect of smoking on bone regeneration after periodontal treatment. METHODS: A protocol was established and studies were sourced from five electronic databases. Screening, data abstraction, and quality assessment was conducted by two review authors. Prospective and retrospective clinical studies assessing bone regeneration in smokers and non-smokers after periodontal therapy were selected. In addition, arms of clinical trials comparing different interventions that reported results separately for smokers and non-smokers were also included. Primary outcome measures were based on clinical and/or radiographic indicators of bone regeneration after periodontal therapy. The review and meta-analysis followed many of the recommendations outlined in the preferred reporting items for systematic reviews and meta-analyses statement. RESULTS: Six of 10 studies included in this review concluded that smoking negatively influenced bone regeneration. A meta-analysis of a subgroup of three studies demonstrated that smoking resulted in significantly less bone gain (P = 0.03) as measured by a change in the probing bone level after the treatment of intrabony defects with guided tissue regeneration. The meta-analysis showed a standardized mean difference of -2.05 (95% confidence interval: -2.64 to -1.47) using the random-effects model. CONCLUSIONS: Smoking has a negative effect on bone regeneration after periodontal treatment. Patients should be advised that their smoking habit may result in poorer bone regeneration after periodontal treatment.

Factors affecting survival and usefulness of implants placed in vascularized free composite grafts used in post-head and neck cancer reconstruction.

BACKGROUND: Bone-containing vascularized grafts have been used successfully to reconstruct post-cancer surgical defects. Dental implants can be placed in these bone-containing grafts to allow implant-supported prosthodontic reconstruction of these patients. PURPOSE: The aim of this study was to evaluate the survival of dental implants used in the rehabilitation of subjects treated with bone-containing vascularized grafts to compare usability of implants placed at the time of reconstruction and after healing. MATERIALS AND METHODS: A cross-sectional study was undertaken to examine survival rates of implants placed in vascularized bone-containing grafts either immediately at the time of surgical reconstruction or after 3 months healing. Other factors such as graft type, whether radiation therapy was given, and implant type were recorded. RESULTS: A total of 41 patients had 145 implants placed in 47 vascularized bone-containing flaps. Increased failure rate of implants was seen in immediately placed implants. There was also a significant increase in the number of osseointegrated implants that were prosthodontically unusable or sub-optimally placed in the immediate placement group. Radiation therapy was associated with a significant increase in failure rate. Modern implant surfaces appeared to perform better than machined/turned surfaces. Graft donor site did not influence implant survival. CONCLUSION: This study demonstrated the difficulties encountered with immediate placement of dental implants at the time of post-cancer reconstructive surgery.

Effect of maxillary sinus floor augmentation on sinus membrane thickness in computed tomography.

BACKGROUND: Little is known about maxillary sinus compliance, i.e., the intrinsic potential of the sinus membrane to resume its homeostatic status after the surgical trauma caused by sinus floor elevation. The aim of the present study is to investigate the effect of maxillary sinus floor augmentation on sinus membrane thickness. METHODS: Within-patient comparison of computed tomographic scans before bone grafting versus 4 to 6 months after bone grafting was performed. Changes in membrane thickness were evaluated in 65 maxillary sinus floor augmentation procedures via a lateral approach in 35 patients without clinical signs of sinus pathology at any time. RESULTS: Sinus membrane thickness differed significantly before (0.8 ± 1.2 mm) versus after (1.5 ± 1.3 mm) augmentation surgery (P <0.001), with a mean increase of 0.8 ± 1.6 mm (maximum: 4.4 mm). Only 28% of augmented sinuses did not show membrane thickening. In non-augmented control sinuses, there was no evidence of membrane thickness increase. CONCLUSIONS: The results indicate that the maxillary sinus membrane, even in healthy clinical conditions, undergoes morphologic modifications after sinus floor elevation, yet membrane reactions demonstrate significant variability. Future research on the effect of augmentation surgery on maxillary sinus physiology is recommended.

Risk of implant failure and marginal bone loss in subjects with a history of periodontitis: a systematic review and meta-analysis.

BACKGROUND: A number of studies have suggested that implant failure and associated bone loss is greater in subjects with a history of periodontitis. PURPOSE: To evaluate the risk for marginal bone loss around implants and implant failure in subjects with a history of periodontitis compared with periodontally healthy subjects in studies with a minimum 3-year follow-up. DATA SOURCES: The MEDLINE, EMBASE, and PubMed databases and relevant journals were searched up to July 1, 2008, with restriction to English language. REVIEW METHODS: Prospective and retrospective longitudinal observational clinical studies comparing periodontal/peri-implant variables among subjects with periodontitis and subjects who were periodontally healthy were included. Screening of studies, quality assessment, and data extraction were conducted independently and in duplicate. Clarification of missing and unclear information was not sought. Outcome measures were: implant survival/failure, peri-implant parameters, changes in radiographic marginal bone level, probing pocket depth, and gingival index. RESULTS: Seventeen potential studies were identified and six studies were accepted comparing patients with periodontitis and periodontally healthy patients treated with implants. Five studies were eligible for meta-analysis of implant survival and four studies were eligible for meta-analysis of bone loss around implants. The odds ratio for implant survival was significantly in favor of periodontally healthy patients (3.02, 95% confidence intervals 1.12-8.15). A random effects model showed more marginal bone loss in periodontitis subjects compared with periodontally healthy subjects (standard mean difference 0.61, 95% confidence interval 0.14-1.09). CONCLUSIONS: Within the limitations of the heterogenous studies available, a moderate level of evidence indicates that periodontitis subjects were at significantly higher risk for implant failure and greater marginal bone loss as compared with periodontally healthy subjects. Prospective observational studies with subject-based designs are recommended.

Strategies for culture of 'unculturable' bacteria.

Molecular ecology methods are now well established for the culture-independent characterization of complex bacterial communities associated with various environmental and animal habitats and are revealing the extent of their diversity. By comparison, it has become clear that only a small minority of microorganisms are readily cultivated in vitro, with the majority of all bacteria remaining 'unculturable' using standard methods. Yet, it is only through the isolation of bacterial species in pure culture that they may be fully characterized, both for their physiological and pathological properties. Hence, the endeavour to devise novel cultivation methods for microorganisms that appear to be inherently resistant to artificial culture is a most important one. This minireview discusses the possible reasons for 'unculturability' and evaluates advances in the cultivation of previously unculturable bacteria from complex bacterial communities. Methods include the use of dilute nutrient media particularly suited for the growth of bacteria adapted to oligotrophic conditions, and the provision of simulated natural environmental conditions for bacterial culture. This has led to the recovery of 'unculturables' from soil and aquatic environments, likely to be due to the inclusion of essential nutrients and/or signalling molecules from the native environment.

The division "Synergistes".

The "Synergistes" group of organisms are a phylogenetic cluster of Gram-negative anaerobes related to Synergistes jonesii, sufficiently distinct from all other phyla to be considered a distinct phylum or Division. They are widely distributed in nature although normally only a minor constituent of the bacterial community in each habitat. They have evolved to adapt to each habitat, and therefore exhibit a wide range of physiological and biochemical characteristics, although all cultivable taxa so far studied have the ability to degrade amino acids. They are found in the human mouth where they appear to be more numerous in tooth and gum disease than health. They have also been found in the human gut and soft tissue infections. Their role in human disease has yet to be established but improved knowledge of the characteristics that enable their identification should increase the likelihood of their recognition when present at diseased sites.