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Biomedical subjects

A Mombelli

Publications and source records attributed to A Mombelli.

At least 37 records · Page 2Linked to original sources
PubMed1999

Actinobacillus actinomycetemcomitans in Chinese adults. Serotype distribution and analysis of the leukotoxin gene promoter locus.

The aim of the present study was to examine the Actinobacillus actinomycetemcomitans carrier rate in Chinese subjects, and to determine serotype distribution, presence of the leukotoxin gene lktA and the structure of the lktA-promoter region. Subgingival microbiological samples were obtained from 31 Chinese subjects with moderate to advanced adult periodontitis, 73 young factory workers, and 81 adult residents of a rural area. Bacterial isolates phenotypically identified as A. actinomycetemcomitans were found in 116 of the 185 subjects (detection frequency over-all: 63%). Presence of the leukotoxin gene lktA was demonstrated for all 115 isolates that could be subcultured. The PCR analysis of the lktA-promoter region showed that none of these strains had the deletion in the promoter region known to enhance expression of lktA. No significant difference in the frequency of A. actinomycetemcomitans could be observed between the subjects of the 3 study groups. Analysis by logistic multiple regression indicated a homogeneous distribution of A. actinomycetemcomitans in the 3 cohorts and a lack of significant influence of subject gender or age. Serotype a was found in 21 subjects, serotype b was found in 9, serotype c in 67 and serotype e in 11 individuals. Serotype d was not detected in any subject. Nontypeable isolates, lacking serotype a, b, c, d, or e antigens, were found in 9 individuals. A high prevalence irrespective of gender, age, and cohort suggests that A. actinomycetemcomitans is a common constituent of the normal flora in the Chinese subjects of this study and suggests differences in the microbiological composition of subgingival plaque may exist for this population group as compared to north American and European populations.

Adolescent↗
PubMed1999

In vitro models of biological responses to implant microbiological models.

To study the etiology and explore possibilities for the therapy of implant-associated infections, investigators have developed and utilized various in vitro models. Major contributions have come from the non-oral medical field, where device-related infections can create life-threatening situations. Microbiological models may include (i) models to study the reaction of micro-organisms to the presence of implants, (ii) models to study the reaction of implant-associated micro-organisms to antimicrobial agents, and (iii) models to study the reaction of the host tissues to the presence of implants contaminated with micro-organisms. In evaluating the potential usefulness of these models for research in oral implantology, one must consider common features as well as important differences between implanted medical devices and oral implants. Although infections associated with implantable medical devices and oral peri-implant infections share a remarkable number of common features, there are also important differences that need attention when findings from in vitro experiments are extrapolated to clinical relevance.

Anti-Bacterial Agents↗
PubMed1999

Early-onset periodontitis.

In 1993, the 1st European Workshop on Periodontology explicitly recognized that there was insufficient knowledge to differentiate truly different forms of periodontal disease from differences in the presentation/severity of the same disease. In spite of recent progress in our understanding of periodontal diseases, the issue is far from having been resolved. Classification of periodontal diseases, therefore, remains based upon the definition of specific clinical syndromes. Early-onset periodontitis (EOP) is one such syndrome and comprises a group of pathological conditions leading to loss of periodontal tissues early in life. The notion that classifies periodontitis syndromes as "early-onset" or "adult" is primarily epidemiological in nature and is based on the observation that periodontitis is rather infrequent in children and young adults. Nevertheless, considerable epidemiological evidence indicates that periodontitis does affect children and young adults to a level of severity that may lead to premature exfoliation of primary and/or permanent teeth. Clinical presentation of periodontitis early in the life of an individual is thought to indicate that the etiologic agents have been able to cause considerable tissue damage over a relatively short period of time. It also implies either infection with highly virulent bacteria and/or a highly susceptible subject. The purpose of this review is to discuss the criteria generally utilized to classify EOP, provide the rationale to designate EOP as a distinct disease entity, and to review the evidence justifying a subclassification into particular subgroups of EOP.

Adolescent↗
PubMed1998

Peri-implant microflora of implants with cemented and screw retained suprastructures.

The aims of this study were to compare clinical and microbiological features in the peri-implant area of implants carrying either screw retained or cemented suprastructures, and to investigate the relationship between the peri-implant microflora, the microbiota on the inner surface of removable suprastructures, and the periodontal microflora within the same subject. In 15 partially edentulous patients with ITI implants used as abutments for crown and bridge reconstructions, microbial samples were taken i) from the deepest periodontal pocket of each quadrant, ii) from the sulcus of the implants and iii) from the internal surface of the screw retained suprastructures. The samples were cultured using continuous anaerobic techniques. Five patients were found with both screw retained (S) and cemented (C) suprastructures. In these subjects the mean total cultivable counts were significantly higher in peri-implant samples from group C than in samples from group S. Furthermore, peri-implant samples of group S yielded a higher proportion of coccoid cells in the darkfield microscope and demonstrated absence of large spirochetes. From the 15 patients, Porphyromas gingivalis was detected in 10% of the periodontal samples and in only one peri-implant sample. Prevotella intermedia was detected in 33% of the periodontal and in 30% of the peri-implant samples. Fusobacterium spp. had a prevalence of 58% in the periodontal samples and was recovered from 50% of the peri-implant samples. Actinobacillus actinomycetemcomitans was not detected in any dental or peri-implant sample. In 1 case, however, the organism was recovered from the internal surface of the suprastructure. Linear regression analysis showed a significant relationship between the frequency of micro-organisms in peri-implant samples of group S and in samples from the inner surface of the suprastructure. Furthermore, there was a significant correlation between the incidence of micro-organisms in dental samples and i) in peri-implant samples of group S and ii) in samples from the internal suprastructure surface. These findings indicate, that the microbial leakage through the gap between the suprastructure and the abutment plays an important role in the bacterial colonization of the internal part of screw retained crowns and bridges. The study furthermore confirms the impact of the dental microflora on the microbial colonization of implants. This factor appears to be more important than the mode of fixation of the suprastructure.

Adult↗
PubMed1998

Actinobacillus actinomycetemcomitans and Porphyromonas gingivalis in young Chinese adults.

The aim of this study was to determine the presence or absence of Actinobacillus actinomycetemcomitans and Porphyromonas gingivalis in young Chinese adults and to examine the A. actinomycetemcomitans isolates from positive subjects with regard to the serotype distribution, presence of the leukotoxin gene lktA and the promoter for the leukotoxin operon as well as the incidence of phage Aa phi 23. Sixty subjects, working in a knitting factory in the Province of Guangzhou, People's Republic of China, were investigated. Subgingival microbial samples were taken from both upper first molars. They were cultured both anaerobically and in 5% CO2. P. gingivalis was found in 33 subjects. On average, it constituted 7% of the total anaerobic cultivable counts. A. actinomycetemcomitans was detected in 37 subjects of which seven yielded counts > 10(5). Twenty-one subjects were positive for both organisms. A. actinomycetemcomitans serotype a was found in 9 subjects, serotype c was found in 23 and serotype e in 5. A. actinomycetemcomitans serotypes b and d were not detected in any subjects. Presence of the leukotoxin gene lktA was demonstrated for all A. actinomycetemcomitans isolates; however, none of the A. actinomycetemcomitans strains from the present study had a deletion in the promoter region of the leukotoxin operon. The results of this investigation show a high frequency of the putative periodontal pathogens P. gingivalis and A. actinomycetemcomitans and corroborate the concept that there is variation in virulence and pathogenic potential among isolates from different subjects.

Adolescent↗
PubMed1998

Evaluation of tetracycline fiber therapy with digital image analysis.

The aims of the present study were to assess radiographically the effects of scaling/root planing combined with antibiotic therapy using tetracycline fibers (TCF): (I) on alveolar bone density and linear descriptors and (II) on supracrestal soft tissue density. 19 subjects with generalized adult periodontitis (with at least 20 teeth present, at least 4 teeth with pockets >4 mm and bleeding upon controlled force probing) and high cultural counts of Porphyromonas gingivalis were recruited from a pool of 57 patients. The full mouth treatment group (FT) consisted of 10 patients, who underwent a full mouth supra-gingival scaling and prophylaxis treatment and were instructed to rinse 2x daily with a 0.1% chlorhexidine solution. 1 week later, tetracycline-hydrochloride-containing fibers (Actisite periodontal fiber) were applied around all teeth. After 7-12 days, the fibers were removed and all teeth were scaled and root planed under local anaesthesia. The chlorhexidine rinsing continued for another 2 months. In 9 subjects (local treatment group LT), 2 teeth with periodontal lesions with pocket probing pepth (PPD) > or =5 mm were treated by placement of tetracycline fibers, which remained in place for 7 to 12 days. Upon removal of the fibers, scaling and root planing was performed on these 2 teeth, while the rest of the dentition remained untreated, and no chlorhexidine rinse was applied. 2 of the untreated teeth revealing similar periodontal lesions were chosen to represent sites affected by untreated periodontitis (NT). In this group, a limited local treatment was performed (2 teeth) with the inherent potential for recolonization from the untreated pocket sites. Standardized periapical radiographs were obtained from the 4 monitored sites within each patient at baseline (before treatment) and 2 and 6 months thereafter. One radiograph was exposed in a standard way for bone assessment. The second radiograph was underexposed, at about a 1/5 of the original exposure time to allow the evaluation of soft tissue. Mean changes in the linear parameters and changes in density (CADIA) observed at multiple sites within each patient and treatment group were used as the best estimate of treatment outcome. Over the observation period of 6 months, a significant difference in bone height changes was found between the untreated sites (median loss -0.29 mm) and the sites from full-mouth treated patients (median gain 0.24 mm, p=0.008). When comparing the baseline to the 6 months radiographs, a loss in bone density was observed for the untreated group (median=-2.13 CADIA). Both treatment groups revealed a gain in density (median=1.58 and 2.43 CADIA for the locally and the full-mouth treated groups, respectively). Differences in density were significant, both between the nontreated and locally treated sites (p=0.026) and between the nontreated sites and the sites from the full mouth treated patients (p=0.002). The analysis of the soft tissues showed a similar pattern of changes in density to those seen in the bone defect. At 2 months, there was a tendency for loss in density for the nontreated group (median=-0.17 CADIA) that continued over the 6 month period (median=-0.31 CADIA). A significant increase in density was observed for the full-mouth treated sites (median=1.57 and 0.64 CADIA for the 2 and 6 months radiographs, respectively). A significant increase was also observed for the locally treated group when compared to the untreated sites (median=0.13 and 0.10 CADIA for the 2 and 6 months radiographs, respectively). Comparing untreated sites with full-mouth treated sites, a significant difference was observed for CADIA measurements (p<0.001). No significant difference was observed comparing locally treated and untreated sites (p=0.24). It was concluded that scaling and root planing combined with TCF therapy can result in increased bone density and alveolar bone height. Full-mouth treatment seemed to result in more pronounced gains compared to local tre

Adult↗
PubMed1997

Comparison of periodontal and peri-implant probing by depth-force pattern analysis.

The purpose of this study was to compare the tissue resistance to probing and the accuracy of depth determination at different force levels around implants and teeth. In 11 subjects 1 implant and 1 tooth at a comparable location and with comparable probing depth were investigated. The sites were located on either the mesial or distal aspect of the tooth and the implant. A probing device was used which allowed simultaneous monitoring of probing force and probe penetration and which standardized the insertion pathway for repeated measurements. The probing instrument was fitted with an attachment for an aiming device to take a radiograph with the probe tip in the sulcus, using a standardized projection geometry. Probing depth values were determined at 0.25, 0.50, 0.75, 1.00 and 1.25 N probing force. The standard error of the individual measurement (Si), evaluated by comparison of repeated measurements in the same session, was 0.2 mm on implants and 0.1 mm on teeth. For implants there was a trend for slightly better reproducibility at higher force levels. Curve analysis of depth force patterns showed that a change in probing force had more impact on the depth reading in the peri-implant than in the periodontal situation. The mean distance between the probe tip and the peri-implant bone crest amounted to 0.75 +/- 0.60 mm at 0.25 N probing force. It is concluded that peri-implant probing depth measurements are more sensitive to force variation than periodontal pocket probing.

Dental Implantation, Endosseous↗
PubMed1997

Clinical response to local delivery of tetracycline in relation to overall and local periodontal conditions.

The purpose of this study was to determine the clinical response to local delivery of tetracycline in relation to clinical and microbiological conditions of the other teeth. 4 deep pockets were monitored in 19 subjects with multiple deep periodontal lesions and high counts of P. gingivalis. In 9 patients (LT) only 2 of the selected lesions were treated by placement of tetracycline fibers (Actisite), while the rest of the dentition was left untreated. In the other 10 patients, all teeth were supragingivally scaled and then treated by application of polymeric tetracycline HCl containing fibers, the whole dentition was subject to full mouth scaling and root planing, and the patients rinsed with 0.2% chlorhexidine (FT). A significant reduction in mean PPD was observed in all treated sites after two months. This reduction was maintained over the following 4 months. The magnitude of the effect was significantly greater in the FT group (1.74 mm) than in the LT group (0.88 mm). The mean attachment level changes were similar after 2 months in locally and fully treated subjects. A tendency of relapse was noted for treated sites in LT patients from month 2 to 6. A level of statistical significance was not reached for this effect. Data from measurements recorded at 6 sites around all teeth in the full mouth treated patients were analyzed using multiple linear regression. This analysis showed local changes in PPD and AL were significantly and strongly correlated with the baseline value of the respective parameter at the same site. In addition, more pocket depth reduction was noted if a site was not bleeding on probing at 6 months, if the location of a site was not approximal and if the tooth was not a second molar. Sites located on second molars showed also less AL gain than sites located on other teeth. Smokers showed significantly less reduction in PPD and significantly less AL gain. Furthermore, if subjects had a high % of pockets deeper than 4 mm at baseline they showed significantly less attachment gain.

Adult↗
PubMed1997

Effect of the NSAID flurbiprofen on remodelling after periodontal surgery.

The aim of the present experiment was to assess the effect of the administration of the NSAID flurbiprofen (Froben) on tissue healing after periodontal surgery. Sites from patients with the same treatment modality (modified Widman flap) but receiving a placebo drug and sites within each patient not exposed to surgery served as controls. Nineteen patients suffering from moderate to severe periodontal disease were recruited and they signed informed consent forms. These patients required periodontal surgery as assessed at the periodontal re-evaluation. The sites chosen for the study were all diagnosed with PPD > or = 5 mm and were bleeding on probing. During the healing phase 10 patients received 50 mg Froben 3 times per day for 30 d whereas 9 patients received a placebo drug. Two sites with PPD > or = 5 mm after initial therapy and bleeding on probing served as surgical sites, whereas 2 similar sites were not exposed to surgery. The study design was set up double-blind. The radiographic examination consisted of 2-4 standardized vertical bitewings obtained at the periodontal re-evaluation (BL) at 1, 3 and 6 months post-surgically for digital subtraction and computer assisted densitometric image analysis (CADIA). The regions of interest analysed were mesial or distal crestal sites. Minimal remodelling activity was observed radiographically after periodontal surgery in both patient groups. There were no statistically significant differences between the four groups of sites regarding the mean changes in density when analysing the pairs of radiographs 0-1, 0-3, 0-6 months. A frequency analysis was performed to list the number of sites with different ranges of density change. No differences in the distributions of the numbers of sites were observed when comparing the 4 site groups (Kolmogorov-Smirnov, p > 0.05). A significant reduction of the probing pocket depth and a significant amount of clinical attachment gain was noted at the surgically treated sites irrespective of whether the patients had used flurbiprofen or placebo. Whereas the pathways leading to bone resorption in periodontally diseased sites have been shown, in other studies, to be influenced by NSAID, the results of the present study could not justify general administration of Froben for the purpose of reduction of bone resorption after periodontal surgical procedures in patients with adult periodontitis.

Absorptiometry, Photon↗
PubMed1997

Clinical trials on therapies for peri-implant infections.

Peri-implant infections are pathological conditions which are normally localized in the soft tissues surrounding an oral implant. They may range from a rather localized mucositis lesion reflecting the host response to a bacterial challenge to a more advanced lesion "termed peri-implantitis" when previously osseointegrated oral implants have been partially disintegrated; i.e. have lost alveolar bone around the implant. Usually these lesions start as a result of plaque accumulation and show similar progression as observed around teeth. Muscositis seems to be a prerequisite for the following peri-implantitis. However, the factors involving the transition to a more advanced lesion are still not known. Logically, the therapy for peri-implant infection has to be related to antibacterial treatment prior to the attempt to surgically regenerate peri-implant alveolar bone lost as a result of the infection. In order to diagnose these lesions at an early stage frequent assessments of clinical parameters are needed during maintenance therapy. The anti-infective treatment may intercept the development of the lesion. Following mechanical debridement of plaque deposits the application of efficacious antiseptics (chlorhexidine) is a necessity. Following this, antibiotics may cumulatively be applied to control the infection. Only a few longitudinal studies have documented the efficacy of such treatment regimens, and controls have generally not been available for ethical reasons. In regenerating the lost jaw bone only case reports are available today. Controlled animal studies will have to be performed to document the possibility of re-osseointegration and the factors influencing predictability.

Animals↗
PubMed1997

Etiology, diagnosis, and treatment considerations in peri-implantitis.

Peri-implantitis is an inflammatory process affecting the tissues around an osseointegrated implant in function, resulting in loss of supporting bone. A review of the literature currently available leads to the conclusion that microorganisms play a major role in this disease. Gram-negative anaerobic bacteria, particularly fusobacteria, spirochetes, and black-pigmenting organisms such as Prevotella intermedia are often found in diseased sites. Several treatment modalities are presently being evaluated. Treatment aimed at a reduction of the anaerobic bacteria improves clinical conditions. Furthermore, case reports indicate a possibility for successful treatment with guided tissue regeneration procedures. However, to date histologic evidence of true reosseointegration has not been obtained. Incomplete surface decontamination seems to be the major obstacle for regrowth of bone onto previously exposed implants. It appears reasonable to attempt interception of destructive peri-implantitis as early as possible and to stop progression by removal of the bacterial deposits.

Dental Implants↗
PubMed1996

Topographic distribution of black-pigmenting anaerobes before and after periodontal treatment by local delivery of tetracycline.

The purpose of this study was to determine the distribution of black-pigmenting Gram-negative bacteria in the dentition of 10 adult periodontitis patients before and after treatment by local delivery of tetracycline. The subjects were selected based on a screening for high counts of Porphyromonas gingivalis and multiple deep pockets. Subgingival microbial samples were taken from the mesial and distal aspect of every tooth (44 to 56 sites per patient) before treatment, and after one and two months. Therapy included full mouth scaling and root planing, chlorhexidine mouth rinsing and placement of tetracycline HCl fibers (Actisite) on all teeth. 63.4% of 524 baseline samples yielded total anaerobic viable counts > or = 10(6) CFU/ml; P. gingivalis was found in 59.2% and Prevotella intermedia in 56.9%. One month after treatment, the % of samples with > or = 10(6) CFU/ml was reduced to 9.4%, 5.3% were P. gingivalis- and 5.1% P. intermedia- positive. After 2 months, 9.6% samples yielded > or = 10(6) CFU/ml, 5.2% were P. gingivalis- and 9.4% P. intermedia- positive. 20 of the 39 sites with a persistence of P. gingivalis were located on second molars. Logistic regression models were utilized to explain the persistence of P. gingivalis, using site location and other clinical parameters as independent variables. These analyses indicated a strong association of site location, pocket depth and bleeding on sampling with persistence of P. gingivalis. The study shows that local delivery of tetracycline is highly effective in reducing the prevalence and proportions of black-pigmenting anaerobes within a dentition. Bleeding deep pockets of second molars have an increased risk for persistence of these anaerobes.

Administration, Topical↗
PubMed1996

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

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

Adult↗
PubMed1996

The effect of a single mechanical treatment on the subgingival microflora in patients with HIV-associated gingivitis.

The purpose of the present study was to investigate the effect of a single episode of scaling and root planing on clinical periodontal parameters and on the subgingival microflora in human immunodeficiency virus (HIV)-positive and HIV-negative subjects. 13 subjects participated and were clinically scored at days -7, 7, 30 and 90. 7 subjects were infected with HIV and presented an HIV-associated gingivitis. 6 subjects were HIV-negative with at least 12 teeth affected by conventional gingivitis. No significant differences were seen between both groups regarding the presence of P. gingivalis, P. intermedia and A. actinomycetemcomitans. The mean plaque index (PlI) was 1.79 in the HIV-negative and 1.29 in the HIV-positive group. The mean gingival index (GI) was higher in the HIV-positive group (HIV-positive: 1.55; HIV-negative: 1.47). Whereas, the PlI decreased significantly in the HIV-negative group during the course of the study, no change was observed in the HIV-positive group. GI as well as bleeding upon sampling decreased significantly in both patient groups during the same period. The bacterial counts decreased from day -7 to day 7 and generally remained on a lower level until day 90. Small differences were seen in the microbiological flora of the HIV-positive and the HIV-negative subjects following mechanical treatment.

AIDS-Related Opportunistic Infections↗