Biomedical subjects

Jörg Eberhard

Publications and source records attributed to Jörg Eberhard.

13 recordsLinked to original sources

PubMed2006

Evaluation of selective calculus removal by a fluorescence feedback-controlled Er:YAG laser in vitro.

OBJECTIVES: To evaluate the removal of subgingival calculus and dental hard tissues depending on the threshold level of a fluorescence feedback-controlled Er:YAG laser. MATERIAL AND METHODS: Twenty teeth with calculus on the root surface were treated with an Er:YAG laser. Laser settings were 140 mJ and 10 Hz. The initial fluorescence threshold level of 5 [U] was reduced at intervals of 1 [U] for every laser treatment. Areas of residual calculus (RC) were evaluated using a surface analysis software. Loss of dental hard tissues was assessed by histomorphometric analysis of undecalcified ground sections. RESULTS: Using a threshold value of 5 [U], the median amount of RC was 11% (0-78%). By lowering the threshold levels, the amount of RC decreased [level 1 [U]: 0% (0-26%)]. The laser-treated root surfaces revealed a statistically significant reduction of the cementum thickness [median: 80 microm (0-250)] compared with the non-treated opposite side [median: 90 microm (30-250)] (p<0.05). CONCLUSION: The amount of RC following laser irradiation depends on the fluorescence threshold level for a feedback-controlled Er:YAG laser. It might be suggested that this laser system may be used with a threshold level even lower than 5 [U] without removing a clinically relevant amount of root cementum.

Aluminum Silicates↗

PubMed2006

Periodontal parameters and platelet-activating factor levels in serum and gingival crevicular fluid in a Chinese population.

AIM: Platelet-activating factor (PAF) is a potent proinflammatory mediator and has been implicated in cardiovascular pathophysiology. The present clinical study assessed the relation between the severity of periodontal disease and PAF levels in gingival crevicular fluid (GCF) and serum. METHODS: A total of 60 non-smoking subjects (21 periodontitis, 19 gingivitis patients and 20 healthy individuals) were included. Probing depth, attachment level, bleeding on probing, plaque index and sulphide levels were recorded at six sites of each tooth. GCF and blood samples were collected from all individuals, and PAF levels were investigated by enzyme-linked immunoabsorbent assay. RESULTS: The periodontitis group showed significantly higher PAF levels in the serum (329.3+/-287.3 pg/ml) and GCF (21.8+/-7.0 pg/sample) compared with the gingivitis group (138.0+/-77.9 pg/ml, 13.8+/-3.6 pg/sample) and with healthy controls (68.9+/-42.8 pg/ml, 2.4+/-2.7 pg/sample). The differences between patients and controls were statistically significant (p<or=0.05). Positive correlations were observed between PAF levels in GCF and serum and for PAF levels and clinical parameters. CONCLUSION: The present findings suggest a role of PAF in the pathogenesis of periodontitis. Based on the observed close correlation of GCF and serum PAF levels, future studies are warranted to test the hypothesis of a possible link between periodontitis and adverse systemic events mediated by PAF.

Adult↗

PubMed2006

Immunolocalization of lactoferrin in healthy and inflamed gingival tissues.

BACKGROUND: It has been reported that lactoferrin prevents biofilm formation and exerts antimicrobial activity. The aim of the present study was to evaluate the cellular source of lactoferrin in healthy and inflamed gingiva. METHODS: Lactoferrin synthesis was examined in relation to disease manifestation in biopsies of the marginal gingiva by immunohistochemistry. The expression of lactoferrin in cell cultures was studied by immunocytochemistry and reverse transcription-polymerase chain reaction (RT-PCR). RESULTS: Healthy gingiva demonstrated no immunoreactivity to lactoferrin in epithelial and connective tissue cells. In inflamed specimens, lactoferrin staining was related to inflammatory cells. These results were confirmed by cell cultures of keratinocytes that did not show any immunoreactivity against lactoferrin. No mRNA message for lactoferrin was detected by RT-PCR in keratinocytes. CONCLUSIONS: These data provide evidence that lactoferrin is not synthesized in healthy gingival tissues. Therefore, elevated lactoferrin levels in the crevicular fluid of inflamed tissues originate from invading cells of the inflammatory reaction.

Adult↗

PubMed2005

Flowable materials as an intermediate layer could improve the marginal and internal adaptation of composite restorations in Class-V-cavities.

OBJECTIVES: The purpose of this in vitro study was to evaluate the marginal and internal adaptation of restorative systems in combination with flowable materials as an intermediate layer in Class-V-cavities. METHODS: Thirty Class-V-cavities with occlusal margins in enamel and gingival margins in dentin/cementum were prepared and randomly assigned to five groups. The following five restorative systems were used: compomer, composite E, flowable compomer/composite E, composite RF and flowable composite/composite RF. The flowable materials were added between the restorative composites and the cervical margins of the cavities. Marginal and internal adaptation were quantitatively evaluated before and after thermal (2,500 times between 5 and 55 degrees C) and mechanical load cycling (25,000 times 100 N) using standard SEM procedures. Statistical analysis was performed using the Kruskal-Wallis and Mann-Whitney U-Test. The morphology of the internal restorative interfaces was also evaluated. RESULTS: The present study revealed that the best marginal adaptation in dentin was attained with the compomer restoration (95.8% perfect margin). The marginal adaptation of composite restorative systems was improved by the use of a flowable compomer (45.5% vs. 68.2% perfect margin in dentin) or a flowable composite (46.7% vs. 80.7% perfect margin in dentin, p<0.05) as an intermediate layer. No differences were observed between the used materials for the parameter internal adaptation. SIGNIFICANCE: In Class-V-cavities compomers showed the best marginal adaptation and the marginal adaptation of composite fillings could be improved by the use of flowable materials as an intermediate layer.

Compomers↗

PubMed2005

The effect of the topical administration of bioactive glass on inflammatory markers of human experimental gingivitis.

Recent studies demonstrated that bioactive glass attenuated inflammatory reactions and bacterial growth in vitro. The aim of the present clinical study was to evaluate the effects of local bioactive glass-administration in vivo in subjects with experimental gingivitis. In each individual, contralateral teeth served as test and control over a 21-day non-hygiene (preventive phase) and a 7-day therapeutic phase. A 45S5 bioactive glass (10% solution) was applied daily (2 x 1 h) on the test teeth during the preventive and therapeutic phase of the study. Inflammation assessment was based on the plaque index record (PI), on the bleeding frequency (BOP) and the gingival crevicular fluid volume (GCF). Interleukin-1beta levels (IL-1beta) in the GCF were measured by ELISA. Bacterial deposits on teeth increased during the 21-days non-brushing period, with no difference in plaque accumulation between test and control sides. BOP levels were significantly reduced during the therapeutic phase by the application of bioactive glass. GCF-values showed a significant reduction on the test compared to control side during the preventive and therapeutic phase. IL-1beta counts decreased during the last 7 days of the study on the test side, but no significance was given. The topical application of 45S5 bioactive glass in humans with experimental gingivitis attenuated the clinical signs of inflammation, although the bacterial accumulation was not inhibited in this clinical trial.

Administration, Topical↗

PubMed2004

Significant influence of scaler tip design on root substance loss resulting from ultrasonic scaling: a laserprofilometric in vitro study.

OBJECTIVES: Ultrasonic scalers have become increasingly popular for subgingival debridement. The aim of the present study was to investigate the influence of different working tip designs (narrow versus wide) on root substance loss caused by either magnetostrictive or piezoelectric ultrasonic devices. METHODS: In this in vitro study, a magnetostrictive ultrasonic system with either Slimline or TFI-10 inserts and a piezoelectric ultrasonic system with either Perioprobe or Type-A inserts were compared at different application forces. Loss of root dentin was determined by defect width, defect depth and defect volume resulting from standardized instrumentation using laser profilometry. RESULTS: There were consistent and statistically significant differences between all groups. The mean observed dentin alterations for the magnetostrictive ultrasonic device operating a Slimline insert at a lateral force of 0.3 N were 254.4 microm, 6.3 microm and 22.5 microm3 and for the TFI-10 tip 759.0 microm, 23.5 microm and 160.2 microm3 for the parameters defect width, depth and volume, respectively. For the piezoelectric ultrasonic system operating a Perioprobe insert, the corresponding mean values were 352.0 microm/12.1 microm/56.4 microm3 and for the universal Type-A insert they were 402.4 microm/14.0 microm/133.4 microm3. With application forces of 0.7 N, root substance removal increased up to twofold. CONCLUSION: The present investigation could demonstrate that the aggressiveness of magnetostrictive and piezoelectric ultrasonic devices to root substance was significantly influenced by the scaler tip designs, increasing for wider scaler tips as compared with narrow, probe-shaped inserts.

Dental Instruments↗

PubMed2004

Plaque removing capacity of a novel high pressure water irrigator.

PURPOSE: To evaluate the capacity of a novel oral water irrigator to remove established plaque deposits. METHODS: The study was designed as a randomized two-treatment, crossover, examiner-blinded clinical trial. The plaque removing capability of a prototype oral irrigator was compared to a conventional electric toothbrush. After 48 hours of plaque accumulation the 35 subjects were randomly assigned to professional plaque removal by either oral irrigation or by electric toothbrushing for a timed 2-minute total cleaning. Pre- and post cleaning plaque was disclosed and gingival abrasions were identified. Plaque was assessed on gingival and approximal surfaces of the oral and buccal sites according to the Rustogi et al modification of the Modified Navy Plaque Index. The assessment of gingival abrasions was performed according to the method introduced by Danser et al. RESULTS: The overall plaque removing capacity of the oral irrigator reached approximately 40.7 +/- 16.7% as compared to 71.6 +/- 11.5% by the electric toothbrush. Similar effects were observed for the gingival and approximal areas. The electric toothbrush caused significantly more gingival abrasions than the oral irrigator.

Adult↗

PubMed2003

Efficacy of subgingival calculus removal with Er:YAG laser compared to mechanical debridement: an in situ study.

OBJECTIVES: The aim of the present study was to compare the effectiveness of subgingival calculus removal from periodontally involved root surfaces with an Er:YAG laser compared to hand instrumentation in situ. METHODS: The mesial and distal surfaces of 30 single-rooted teeth with untreated periodontitis were treated either by hand instrumentation (scaling and root planing (SRP)) or by Er:YAG laser irradiation with the aim of achieving a calculus-free root surface. Subgingival plaque samples were obtained before and immediately after treatment for microbiological evaluation by culture and DNA probe analysis. The teeth were extracted and the residual calculus was measured by means of digitized planimetry. The morphology of the root surface was evaluated by scanning electron microscopy, and undecalcified sections were analyzed to determine residual calculus and the extent of cementum removal following both treatments. RESULTS: Following laser irradiation, 68.4+/-14.4% of the root surface was calculus free in contrast to 93.9+/-3.7% after SRP when both treatments were performed for the same time (2:15+/-1:00 min). If laser irradiation was allowed twice the time used for hand instrumentation, 83.3+/-5.7% of the root surface was devoid of calculus. The effectiveness of both treatments was not related to initial probing depth. The histologic evaluation showed that after SRP 73.2% of root dentin was completely denuded from cementum, while only a minimal cementum reduction was apparent after laser irradiation. Both treatment modalities resulted in a similar reduction of periodontopathogens. DISCUSSION: The present investigation could demonstrate the in vivo capability of the Er:YAG laser to remove calculus from periodontally involved root surfaces, although the effectiveness did not reach that achieved by hand instrumentation. The lack of cementum removal in contrast to SRP may qualify the laser as an alternative approach during supportive periodontal therapy.

Adult↗

PubMed2003

Interleukin-1 gene polymorphisms and experimental gingivitis.

BACKGROUND: Recently, an association between the severity of periodontitis and specific variations in the interleukin-1 (IL1) alpha and beta genes has been demonstrated. AIM: : The purpose of this study was to evaluate the relationship of the IL1 genotype to the development of experimental gingivitis. MATERIALS AND METHODS: Twenty young adult subjects presenting with healthy gingival conditions participated after giving their informed consent. The group included 10 risk genotype positive (P+) and 10 risk genotype negative (P-) individuals. The IL1 genotypes were determined on DNA samples from peripheral blood using PCR-RFLP analyses for the IL1alpha and IL1beta polymorphisms. Experimental gingivitis was allowed to develop in two posterior sextants per subject. Bleeding on probing (BOP%) and gingival crevicular fluid volume (GCF) were assessed at baseline and days 2, 7, 9, 14, 16 and 21. The day 21 results for BOP and GCF as well as the rate of increase of these parameters - mean area under the curve (AUC) and mean increase per day (slope) - were evaluated using risk analyses for IL1 genotype, smoking status and gender. RESULTS: Experimental gingivitis developed with a gradual increase in BOP scores and GCF values (expressed as Periotron units=PU) from baseline to day 21 (BOP, P+: 0.5 to 26.0%; P-: 1.0 to 28.1%; GCF, P+: 36.8 to 138.5 PU, P-: 43.1 to 143.4 PU). No significant risk was associated with P+ and P- for day 21 results, AUC or slope. CONCLUSION: The results of this study failed to provide evidence that the IL1 risk genotype was associated with higher GCF volume and percentage BOP during the development of experimental gingivitis.

Adult↗

PubMed2002

Leukotriene A(4)-hydrolase expression and leukotriene B(4) levels in chronic inflammation of bacterial origin: immunohistochemistry and reverse-phase high-performance liquid chromatography analysis of oral mucosal epithelium.

Chronic inflammation of the oral epithelium of bacterial origin is associated with elevated leukotriene B(4) (LTB(4)) levels. We investigated leukotriene A(4) (LTA(4))-hydrolase expression and LTB(4) levels in oral epithelium in relation to the clinical disease manifestation and immunohistopathology and LTA(4)-hydrolase expression in cultured oral keratinocytes. In 11 patients, three different types of biopsy specimens of the oral mucosa tissues were examined. Each sample was divided, and one-half was analysed using immunohistochemistry with antibodies to LTA(4)-hydrolase, CD1a, CD3, CD19, macrophages/monocytes and granulocytes. The other half of the sample was homogenised and analysed using reverse-phase high-performance liquid chromatography to determine LTB(4) levels. We found strong LTA(4)-hydrolase expression in basal cells of the oral epithelium from tissue samples that appeared clinically healthy; however, histologically a mild chronic inflammation was observed. In contrast, patients with symptoms of an inflammation of the oral mucosa showed only weak LTA(4)-hydrolase staining of the epithelial cell layers, but strong immunoreactivity in endothelial and invading inflammatory cells. LTB(4) levels were elevated in inflamed tissues compared with non-inflamed controls. Most significantly, there was a strong association between the immunohistochemical detection of the enzyme, LTB(4) levels, cellular infiltration and the clinical disease manifestations. In vitro experiments indicated that LTA(4)-hydrolase expression may be induced by bacterial contamination. This study suggests that LTA(4)-hydrolase expression and elevated LTB(4) levels in oral mucosal epithelium are integral parts of the induction and progression of chronic inflammatory reactions. Epithelial cells may participate in early stages of inflammation as a source of LTB(4).

Adult↗

PubMed2002

Local application of n-3 or n-6 polyunsaturated fatty acids in the treatment of human experimental gingivitis.

BACKGROUND: Polyunsaturated fatty acids have the potential to attenuate inflammation by the synthesis of mediators of the 15-lipoxygenase pathways, which show opposite effects to the pro-inflammatory arachidonic acid metabolites such as leukotriene B4 (LTB4). AIMS: The aim of this clinical study was to evaluate the effects of topical application of n-6 or n-6 polyunsaturated fatty acids in patients with experimental gingivitis. METHODS: In each subject, similar teeth served as experimental and control over a 21-day non-hygiene phase and a 9-day resolving phase. Efficacy assessment was based on the bleeding on probing frequency (BOP) and the gingivocrevicular fluid volume (GCF). GCF was determined by inserting a filter paper strip for 30 s and measurements were performed on a Periotron 8000. The LTB4 concentration was analyzed by reversed-phase high-pressure liquid chromatography. RESULTS: After 21 days of plaque growth, the BOP, GCF and LTB4 levels were significantly increased in all groups, with no differences between the control and experimental side. Rinsing of an area with established gingivitis for a 9-day period significantly reduced the GCF in the n-6 group (71.9 (18.7) versus 47.4 (11.4) Periotron Units, median (inter quartile range)). CONCLUSION: The topical application of n-6 or n-6 fatty acids failed to inhibit the development of experimental gingivitis. Rinsing with n-6 fatty acids could reduce the level of GCF in established experimental gingivitis.

Administration, Topical↗

PubMed2002

A systematic review of guided tissue regeneration for periodontal furcation defects. What is the effect of guided tissue regeneration compared with surgical debridement in the treatment of furcation defects?

OBJECTIVES: To systematically review the evidence of effectiveness of guided tissue regeneration (GTR) for furcation defects. BACKGROUND: The evidence for the effectiveness of GTR in furcation defects has not yet been systematically appraised. METHODS: We searched for randomized controlled trials with at least 6 months' follow-up comparing GTR with surgical debridement (open flap debridement, OFD). Data sources included electronic databases, hand-searched journals and contact with experts. Screening, data abstraction and quality assessment were conducted independently by multiple reviewers. The primary outcome measure was reduction in open horizontal furcation depth, secondary outcomes were frequency of furcation closure, gain in horizontal and vertical probing attachment and reduction of vertical probing depth. RESULTS: For the primary outcome, reduction in horizontal furcation depth assessed during re-entry, the weighted mean difference between GTR and control was 1.51 mm (95% CI [0.39-2.62], chi-square for heterogeneity 67.6 (df = 3), P < 0.001) in mandibular class II furcations, 1.05 mm (95% CI [0.46-1.64, chi-square for heterogeneity 34.9 (df = 3), P < 0.001) in maxillary class II furcations, and 0.87 mm (95% CI [-0.08-1.82], chi-square for heterogeneity 0.1 (df = 4), P = 0.991) in studies that had combined mandibular and maxillary class II furcations. For the secondary outcomes, GTR treatment led to significantly better results than open flap debridement. No meta-analysis could be performed for frequency of furcation closure because of sparse data. CONCLUSIONS: Overall, GTR was consistently more effective than OFD in reducing open horizontal furcation depths, horizontal and vertical attachment levels and pocket depths for mandibular or maxillary class II furcation defects. However, these improvements were modest, variable and there was only a limited number of studies available to appraise the effects, thus limiting general conclusions about the clinical benefit of GTR. Future studies should aim to identify factors associated with achieving consistent and more pronounced benefits over open flap debridement.

Furcation Defects↗

PubMed2002

Bacterial challenge stimulates formation of arachidonic acid metabolites by human keratinocytes and neutrophils in vitro.

Although the interactions of bacteria with keratinocytes induce the synthesis of various mediators, the capability of epithelial cells to form arachidonic acid mediators has not been studied, and therefore the first part of this study was initiated. The complex mixture of epithelium-derived mediators suggests that chemoattraction is not their only effect on neutrophils and that they may also affect neutrophil mediator synthesis. The effect of epithelium-derived mediators on neutrophil eicosanoide synthesis was evaluated in the second part of this study. We incubated human keratinocytes with human-pathogenic bacteria for 2 h and harvested the supernatants after 4, 6, 10, and 18 h of culture. Subsequently, the supernatants were coincubated for 5 min with human neutrophils with or without arachidonic acid. The formation of the arachidonic acid metabolites prostaglandin E(2) (PGE(2)), leukotriene B(4) (LTB(4)), 12-hydroxyeicosatetraenoic acid (12-HETE), and 15-HETE in keratinocytes and neutrophils was measured by reverse-phase high-pressure liquid chromatography. We demonstrated for the first time that keratinocytes produced significant amounts of LTB(4) and 12-HETE 4 to 6 h after bacterial challenge. Upon stimulation with epithelial supernatants, neutrophils produced significant amounts of PGE(2), LTB(4), 12-HETE, and 15-HETE throughout the observation period of 18 h, with a maximum synthesis by supernatants harvested 4 to 10 h after bacterial infection. The results of the study suggest that arachidonic acid mediator formation by epithelial cells following bacterial challenge may act as an early inflammatory signal for the initiation of the immune response. The epithelial supernatants were capable of inducing the formation of arachidonic acid mediators by neutrophils, which may have further regulatory effects on the immune response.

Aggregatibacter actinomycetemcomitans↗