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.

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.

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).

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.

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.

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.

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.