Comparison of two interdental cleaning aids: A randomized clinical trial.

AIM: The aim of this study was a comparison of the handling and acceptance of two kinds of interdental brushes (interdental brush with a handle [HB] and a newly invented interdental cleaning device [NB]). METHODS AND MATERIALS: In a randomized crossover trial, 40 test subjects with an average number of 23.5 interdental areas were examined. At two appointments with a "washout" period of one week, the volunteers tried out both cleaning tools (HB and NB). They were asked to clean as many interdental spaces as possible. The percentage of spaces, which could be reached, is the IRI (Interdental Reachability Index). Furthermore, subjective impressions were determined. RESULTS: The average IRI using HB was 64% compared to 80% using of NB (P<.001); 62.5% of the volunteers found the cleaning with HB painful and 15% the cleaning with NB. The subjective feeling after cleaning was 1.75 with NB compared to 2.2 with HB (P=.015), grading the feeling, from 1 for "very good" to 5 for "poor." The acceptance of regular interdental hygiene was rated 1.95 in the case of the NB and 2.85 in the case of the HB. After both appointments, the test subjects declared that they would use the NB 3.05 times and the HB 1.78 times a week. CONCLUSION: This study shows that the test subjects reached more interdental spaces with NB than with the HB. NB can improve the usage of interdental brushes. Regarding subjective comfort, participants also favoured NB over HB.

Oral pathogens change proliferation properties of oral tumor cells by affecting gene expression of human defensins.

The impact of oral pathogens onto the generation and variability of oral tumors has only recently been investigated. To get further insights, oral cancer cells were treated with pathogens and additionally, as a result of this bacterial cellular infection, with human defensins, which are as anti-microbial peptide members of the innate immune system. After cell stimulation, proliferation behavior, expression analysis of oncogenic relevant defensin genes, and effects on EGFR signaling were investigated. The expression of oncogenic relevant anti-microbial peptides was analyzed with real-time PCR and immunohistochemistry. Cell culture experiments were performed to examine cellular impacts caused by stimulation, i.e., altered gene expression, proliferation rate, and EGF receptor-dependent signaling. Incubation of oral tumor cells with an oral pathogen (Porphyromonas gingivalis) and human α-defensins led to an increase in cell proliferation. In contrast, another oral bacterium used, Aggregatibacter actinomycetemcomitans, enhanced cell death. The bacteria and anti-microbial peptides exhibited diverse effects on the transcript levels of oncogenic relevant defensin genes and epidermal growth factor receptor signaling. These two oral pathogens exhibited opposite primary effects on the proliferation behavior of oral tumor cells. Nevertheless, both microbe species led to similar secondary impacts on the proliferation rate by modifying expression levels of oncogenic relevant α-defensin genes. In this respect, oral pathogens exerted multiplying effects on tumor cell proliferation. Additionally, human defensins were shown to differently influence epidermal growth factor receptor signaling, supporting the hypothesis that these anti-microbial peptides serve as ligands of EGFR, thus modifying the proliferation behavior of oral tumor cells.

Diagnostic accuracy of CBCT for periodontal lesions.

OBJECTIVES: The present study compares the diagnostic value of periodontal bone defect images using conventional two-dimensional single-tooth radiographs and three-dimensional cone beam computed tomography (CBCT) images. MATERIALS AND METHODS: Classified periodontal bone defects were prepared on pig mandibles and presented radiographically. Fifteen dentists were instructed to make a diagnosis based on these x-rays, regarding the type and the extent of the bone defects. Subsequently, the results were evaluated and compared to the morphology of the surgically prepared defects as the gold standard. RESULTS: On average, the diagnosis of infrabony defects were 21 %, dehiscence 25 %, and fenestration 33 % more accurate using the three-dimensional projection than with the single-tooth radiograph. Furthermore, the CBCT allows grade II furcation to be captured more accurately. CONCLUSIONS: The results of this study indicate that a considerably more precise analysis of periodontal defects is possible due to the third dimension. Particularly, in the oro-vestibular orientation, defects could be detected significantly more accurate. CLINICAL RELEVANCE: CBCT images offer an advantageous alternative to the conventional single-tooth radiograph while taking the higher exposure of radiation into account.

3D analyses of interface voids in root canals filled with different sealer materials in combination with warm gutta-percha technique.

OBJECTIVES: The aim of the present study was to analyze the formation of voids and gaps in root canals obturated with different sealer materials in combination with warm gutta-percha vertical compaction technique by using BeeFill® 2in1. MATERIALS AND METHODS: Twenty-four single-rooted teeth were collected, and root canals were prepared by using rotary files. All teeth were randomly allocated into three groups. Each group was obturated by using the BeeFill® 2in1 system in combination with Sealapex (non-eugenol, calcium hydroxide polymeric root canal sealer; Kerr Sybron, USA), RoekoSeal (polydimethylsiloxane-based sealer; Roeko, Germany), or 2Seal (epoxy-amine resin-based sealer; VDW, Germany). Following preparation, all teeth were scanned with a micro-computed tomography (CT) scanner, and a three-dimensional reconstruction of the obturated root canals was performed to analyze the volume of interface voids and gaps in the obturated teeth. RESULTS: Statistical analysis demonstrated that the silicon-based sealer RoekoSeal induced significantly less voids and gaps than other tested materials. The amount of voids and gaps significantly was higher in the apical region. CONCLUSIONS: These data indicate that none of the root canal-filled teeth were free of gaps. Teeth obturated with RoekoSeal demonstrated to have the highest quality in terms of voids and gaps formation in combination with the BeeFill® 2in1 obturation system. CLINICAL RELEVANCE: These findings point to the potential benefit of micro-CT analyses for in vitro evaluation of root canal obturation systems and provide further information about sealer materials used in combination with a warm gutta-percha vertical compaction technique.

Defective complex I assembly due to C20orf7 mutations as a new cause of Leigh syndrome.

BACKGROUND: Leigh syndrome is an early onset, progressive, neurodegenerative disorder with developmental and motor skills regression. Characteristic magnetic resonance imaging abnormalities consist of focal bilateral lesions in the basal ganglia and/or the brainstem. The main cause is a deficiency in oxidative phosphorylation due to mutations in an mtDNA or nuclear oxidative phosphorylation gene. METHODS AND RESULTS: A consanguineous Moroccan family with Leigh syndrome comprise 11 children, three of which are affected. Marker analysis revealed a homozygous region of 11.5 Mb on chromosome 20, containing 111 genes. Eight possible mitochondrial candidate genes were sequenced. Patients were homozygous for an unclassified variant (p.P193L) in the cardiolipin synthase gene (CRLS1). As this variant was present in 20% of a Moroccan control population and enzyme activity was only reduced to 50%, this could not explain the rare clinical phenotype in our family. Patients were also homozygous for an amino acid substitution (p.L159F) in C20orf7, a new complex I assembly factor. Parents were heterozygous and unaffected sibs heterozygous or homozygous wild type. The mutation affects the predicted S-adenosylmethionine (SAM) dependent methyltransferase domain of C20orf7, possibly involved in methylation of NDUFB3 during the assembly process. Blue native gel electrophoresis showed an altered complex I assembly with only 30-40% of mature complex I present in patients and 70-90% in carriers. CONCLUSIONS: A new cause of Leigh syndrome can be a defect in early complex I assembly due to C20orf7 mutations.

Investigation of active matrix- metaloproteinase-8 (aMMP-8) as a reference parameter for path control in antimicrobial photothermal therapy (aPTT) using a split-mouth design.

OBJECTIVES: This retrospective data-collection study aims to explain how the active matrix-metalloproteinase-8-titer (aMMP-titer) influences the immune response of the subject. This is done through monotherapy scaling and root planing (SRP) which is then compared to SRP combined with antimicrobial photothermal therapy (aPTT, Emundo®). METHODS: Data collection was monocentric, randomized and split-mouth based. A study group of twenty patients with chronic periodontal disease with a periodontal pocket depth (PPD) 4 mm ≤ PPD ≤8 mm, a periodontal screening index (PSI: > 3), and a gingival recession ≤2 mm were selected.A diode laser, manufactured by A.R.C. Laser GmbH, with 810 nm wavelength was used. This device implemented three different light transmission systems for transgingival and intra-gingival irradiation. Power settings between 200 and 300 mW were deployed for 10 s during all treatment steps. The photothermic dye of EmunDo® system (A.R.C. Laser GmbH) was infracyaningreen.The adjuvant effect of the antimicrobial photothermal therapy (aPTT) with EmunDo® in combination with conventional SRP on the teeth 15 and 35 was compared with the results of monotherapy SRP on teeth 25 and 45. RESULTS: A reduction of the aMMP-8-titer in gingival crevicular fluid (GCF) was observed in both groups (follow up group and control group) after one month. However; the decrease in the follow up group under SRP in combination with aPTT was significantly more pronounced. The periodontal pocket depths was reduced in both treatment groups. The periodontal probing depth (in mm) shows a larger decrease of the periodontal pocket depth within the follow up group (SPR with aPTT) compared with the control group (SRP). CONCLUSION: The aMMP-8-titer showed differences in both groups prior to and after treatment. Active matrix-metalloproteinase-8 (aMMP-8) as a reference parameter for path control in antimicrobial photothermal therapy (aPTT) seems acceptable.

Response of MG63 osteoblasts on bacterial challenge is dependent on the state of differentiation.

The present in vitro study examines molecular processes that are relevant during bone homeostasis after Aggregatibacter actinomycetemcomitans and Porphyromonas gingivalis infection with a focus on the differentiation level of osteoblasts. Regenerative processes are often hindered by the recurrence of bacterial infections, which can ultimately provoke a severe destruction of bone tissue. To obtain more detailed insights into such a complex scenario, we have used undifferentiated MG63 osteoblast-like cells as an experimental paradigm to examine the impact of two oral pathogens, A. actinomycetemcomitans and P. gingivalis, on proliferation, cytotoxicity and osteogenic differentiation. Cell culture experiments were performed to analyze cellular behavior. The level of genes interfering with bone tissue integrity (matrix metalloproteinases and their tissue inhibitors) and osteogenic markers (alkaline phosphatase, Runx2, human ß-defensin-2) was compared in undifferentiated versus differentiated MG63 cells using real-time polymerase chain reaction. Functional activity of matrix metalloproteinases was quantified by zymography. Western blot analysis was used to verify the phosphorylation state of mitogen-activated protein kinases p38 and extracellular-signal-regulated kinases 1/2. When co-cultured with undifferentiated MG63 cells, oral pathogens provoked distinct cellular effects. Only A. actinomycetemcomitans reduced cell proliferation, increased cell death, and induced osteogenic differentiation. A comparison of matrix metalloproteinase network stability in the presence of oral pathogens revealed a partial sensitivity towards P. gingivalis but not A. actinomycetemcomitans. So, beside the proof of concept that MG63 cells co-cultured with oral pathogens can serve as an in vitro model for mimicking destructive and regenerative events after bacterial infections, our data indicate that double infections might counterbalance otherwise positive effects.

Biosynthesis of Phosphatidylglycerol in Isolated Mitochondria of Etiolated Mung Bean (Vigna radiata L.) Seedlings.

Phosphatidylglycerophosphate synthase (sn-glycerol-3-phosphate:CDP-diacylglycerol phosphatidyltransferase) and phosphatidylglycerophosphate phosphatase were characterized in mung bean (Vigna radiata L.) mitochondria. The synthase has a rather broad pH optimum between 7 and 9, whereas the phosphatase has one of about 7. Both enzymic activities are stimulated by Triton X-100 and require divalent cations but differ in their cation specificities. The synthase shows apparent Km values of 9 and 3 [mu]M for sn-glycerol-3-phosphate and CDP-diacylglycerol, respectively. Phosphatidylglycerophosphate, in contrast to lysophosphatidic and phosphatidic acid, is effectively dephosphorylated by the phosphatase, which exhibits an apparent Km value of 12 [mu]M for its substrate. Each enzyme shows higher activities with the dipalmitoyl species of its substrate than with the dioleoyl species. These substrate specificities of both enzymes are predominantly based on differences in apparent Vmax values.

Biosynthesis of Cardiolipin in Plant Mitochondria.

The properties of cardiolipin synthase were investigated in mitochondria and submitochondrial fractions from etiolated mung bean (Vigna radiata L.) seedlings. Direct evidence is presented that the enzyme utilizes CDP-diacylglycerol in addition to phosphatidylglycerol for the synthesis of cardiolipin. Cardiolipin synthase had an alkaline pH optimum of about 9 and required divalent cations for activity. Maximal activity was obtained in the presence of 16 mM MnCl2. The apparent Km values for CDP-diacylglycerol and phosphatidylglycerol were 0.8 and 50 [mu]M, respectively. Cardiolipin synthase was localized predominantly in the inner membrane of mung bean mitochondria and displayed a substrate species specificity. Highest activities were measured with the dioleoyl species of both CDP-diacylglycerol and phosphatidylglycerol, and somewhat lower activities were measured with mixed species of the two substrates containing a palmitoyl and an oleoyl group. On the other hand, the cardiolipin synthase hardly used the dipalmitoyl species and strongly discriminated against CDP-dipalmitoylglycerol from a mixture with CDP-dioleoylglycerol.

Specificities of the Acyl-Acyl Carrier Protein (ACP) Thioesterase and Glycerol-3-Phosphate Acyltransferase for Octadecenoyl-ACP Isomers (Identification of a Petroselinoyl-ACP Thioesterase in Umbelliferae).

This study was designed to address the question: How specific for double bond position and conformation are plant enzymes that act on oleoyl-acyl carrier protein (ACP)? Octadecenoyl-ACPs with cis double bonds at positions [delta]6, [delta]7, [delta]8, [delta]9, [delta]10, [delta]11, or [delta]12 and elaidyl (18:1[delta]9trans)-ACP were synthesized and used to characterize the substrate specificity of the acyl-ACP thioesterase and acyl-ACP:sn-glycerol-3-phosphate acyltransferase. The two enzymes were found to be specific for the [delta]9 position of the double bond. The thioesterase was highly specific for the [delta]9 cis conformation, but the transferase was almost equally active with the cis and the trans isomer of 18:1[delta]9-ACP. In plants such as the Umbelliferae species coriander (Coriandrum sativum L.) that accumulate petroselinic acid (18:1[delta]6cis) in their seed triacylglycerols, a high petroselinoyl-ACP thioesterase activity was found in addition to the oleoyl-ACP thioesterase. The two activities could be separated by anion-exchange chromatography, indicating that the petroselinoyl-ACP thioesterase is represented by a distinct polypeptide.

Phosphatidylglycerophosphate synthases from Arabidopsis thaliana.

Two Arabidopsis thaliana genes were shown to encode phosphatidylglycerophosphate synthases (PGPS) of 25.4 and 32.2 kDa, respectively. Apart from their N-terminal regions, the two proteins exhibit high sequence similarity. Functional expression studies in yeast provided evidence that the 25.4 kDa protein is a microsomal PGPS while the 32.2 kDa protein represents a preprotein which can be imported into yeast mitochondria and processed to a mature PGPS. The two isozymes were solubilized and purified as fusion proteins carrying a His tag at their C-terminus. Enzyme assays with both membrane fractions and purified enzyme fractions revealed that the two A. thaliana isozymes have similar properties but differ in their CDP-diacylglycerol species specificity.

Er:YAG laser scaling of diseased root surfaces.

BACKGROUND: The removal of calculus and plaque is an essential component of a therapeutic approach to control periodontal disease. Er:YAG laser scaling was recently introduced as an alternative to conventional scaling procedures. In this histological study, the effects of laser instrumentation of diseased root surfaces are compared to mechanical removal of plaque and calculus with ultrasonic instruments and scalers. METHODS: Areas of subgingival calculus were identified on 40 freshly extracted human teeth. Each of these areas was randomly divided into 2 equal parts. The control site was treated either with scaling and root planing or with an ultrasonic instrument. The test site was cleaned using an Er:YAG laser according to the manufacturer's instructions. The end point of debridement was the inability to mechanically or visibly detect any remaining calculus. After pre- and postsurgical photographs and impressions for scanning electronic microscopic investigation, a plastic embedding technique was used to cut the undecalcified roots into 15 microm thick sections. RESULTS: Clinically and histologically, scaling resulted in complete debridement at all samples, producing a smooth root surface. At the test sites, laser scaling was accompanied by an increased removal of tissue and roughened surfaces. CONCLUSIONS: Laser scaling results in an increased loss of cementum and dentin, which should be taken into account in clinical situations.

Clinical and microbiological effects of topical subgingival application of hyaluronic acid gel adjunctive to scaling and root planing in the treatment of chronic periodontitis.

BACKGROUND: Hyaluronic acid (HA) has shown anti-inflammatory effects in gingivitis therapy. The potential benefits of local subgingival application of HA adjunctive to scaling and root planing (SRP) were evaluated in this study. METHODS: Twenty patients with chronic periodontitis were included in this split-mouth study. Sulcus fluid flow rate (SFFR) and sulcus bleeding index were monitored at baseline and after 1, 2, 3, 4, 5, 6, and 12 weeks; probing depth and clinical attachment level were monitored at baseline and 6 and 12 weeks. Subgingival plaque samples were also taken at these same three appointments to determine the presence of Actinobacillus actinomycetemcomitans, Porphyromonas gingivalis, Prevotella intermedia, Tannerella forsythensis, and Treponema denticola. All patients were treated with full-mouth scaling and root planing (SRP); in addition, an HA gel was administered subgingivally in the test sites every week for 6 weeks. RESULTS: An improvement of all clinical variables was observed (P < 0.05) in both groups. Clinically, no difference between test and control sites could be found. No difference between test and control sites was seen in the tested microorganisms. CONCLUSIONS: No clinical or microbiological improvement was achieved by the adjunctive use of HA gel compared to SRP alone. Only SFFR was affected by the use of HA in terms of a more rapid reduction of SFFR in the test sites.

[The value of high resolution computed tomography (HRCT) in the diagnosis of deep forms of parodontitis]. / Zur Wertigkeit der hochauflösenden Computertomographie (HRCT) bei der Diagnostik profunder Parodontitisformen.

It is difficult to demonstrate the extent of parodontal bone erosions with conventional radiographic techniques. HRCT makes it possible to demonstrate the alveolar structures without superimposition. 10 patients with parodontitis marginalis profunda were examined by conventional methods and HRCT. Comparison showed considerable superiority of HRCT in respect of demonstrating bone destruction. The absence of superimposition produces excellent demonstration of the roots and shows the bifurcation and trifurcation of teeth; consequently, mapping the position and shape of the root canals is possible and this is an important aid in the planning of parodontal surgical treatment.

In vitro analysis of the effects of acid or laser etching on microleakage around composite resin restorations.

OBJECTIVES: The aim of the present study was to determine the effect of two conditioning methods, phosphoric acid and XeCl laser application on microleakage at composite resin restorations. METHODS: Class II MOD (mesio-occluso-distal) cavities were prepared on 90 extracted human wisdom teeth with one proximogingival margin on enamel and the other on dentin. Phosphoric acid (37%) and a XeCl excimer laser system were used for the etching procedure. The prepared teeth were randomly assigned to six groups: In group 1, acid-etching of the enamel margins was followed by application of enamel bonding, in group 2 additionally a dentin bonding system was used. In group 3, acid-etching of the enamel and dentin (total etch) was followed by the application of dentin bonding. In group 4, laser-etching of enamel margins was followed by the application of enamel bonding, in group 5 dentin bonding was used additionally. In group 6, laser-etching of enamel and dentin margins was followed by the application of dentin bonding. All restorations were placed incrementally and polymerized with a halogen light source. After restoration, all samples were thermocycled and stained in 0.5% basic fuchsin and sectioned longitudinally in a mesio-distal plane. Microleakage was scored by means of a stereomicroscope. The margins of the restorations at tooth-resin interface were examined with a scanning electron microscope. RESULTS: In all groups, marginal leakage was more extensive at the gingival margin that was in dentin than at the gingival margin in enamel. Microleakage scores and the gap at the tooth-resin interface were significantly lower in all acid-etched groups than in laser-etched groups. CONCLUSION: Acid-etch technique is more effective than the investigated laser-etch technique at 308nm concerning the reduction of marginal leakage in composite restorations.

Correlation between caries prevalence (DMFS) and periodontal condition (CPITN) in more than 2000 patients.

The CPITN (Community Periodontal Index of Treatment Needs) and DMFS (Decayed-Missing-Filled Surfaces) index were evaluated simultaneously to provide information on the mutual influences of periodontal disease and caries. With the aid of an electronic database system the data of the caries index and periodontal index of more than 2000 patients aged between 18 and 80 years were stored and calculated. As expected, the CPITN and DMFS values increased with age. When the CPITN was selected as a reference the DMFS was found to change with increasing CPITN. With the examination method used in this study no correlation could be established between the prevalence of caries and periodontal condition, although both conditions have a common aetiological factor: microbial plaque.

Lasers in dentistry: new possibilities with advancing laser technology?

Although there are a considerable number of published papers on the role of laser treatment in dentistry, a critical review shows that laser technology is used only by specialists in a small therapeutic field. Most lasers are heat-producing devices converting electromagnetic energy into thermal energy. These lasers find uses in oral surgery for cutting or coagulating soft tissues or in the welding of dental prostheses. More recently, new types of lasers have offered non-thermal modes of tissue interaction, called photoablation, photodisruption and photochemical effects. Basic and clinical research is being carried out into the application of these devices in dentistry. However, much development will be required before lasers can replace conventional surgical methods for treating oral cancer or indeed replace the conventional bur for excavating carious lesions.

Clinical and microbiological effects of local chlorhexidine applications.

AIM: To study the effects of an application of chlorhexidine varnish (40%) on dental plaque. DESIGN: Randomised controlled clinical trial. SUBJECTS: 40 patients (50% females), aged 25-34 years after undergoing any necessary restorative treatment. Exactly one half of these individuals practiced good oral hygiene, the efforts of the others were poor. METHOD: Test groups received a chlorhexidine varnish application, the control group received a placebo varnish. Initially and after 2 and 6 weeks, a modified Dentocult SM-test, bleeding on probing, and a plaque index (Quigley-Hein) were recorded. RESULTS: In contrast to the control group, improvements in plaque index and bleeding on probing scores were found in patients with poor oral hygiene. The results of the Dentocult SM-tests showed a considerable reduction of streptococcus colonisation. The test group with good oral hygiene showed only slight improvement of the examined indices after chlorhexidine application. The index parameters of all patients of the placebo groups remained unchanged over the examination time period. CONCLUSION: The application of a chlorhexidine varnish reduced the quantity of the Streptococcus mutans colonies significantly and improved clinical parameters in patients with elevated plaque accumulation.

Excimer lasers in dentistry: future possibilities with advanced technology.

The thermal side effects of carbon dioxide and neodymium:yttrium-aluminum-garnet lasers limit their clinical applications. These high-powered, infrared lasers result in zones of charring and carbonization even in soft tissues and the bone. In contrast, the pulsed, ultraviolet radiation emitted by excimer lasers causes limited thermal, denaturative damage to surrounding tissues. Therefore, treatment of dental tissues with the nonthermal process of photoablation with excimer lasers may present alternatives to traditional dental practice. Possible future applications of the excimer laser include selective caries removal, the conditioning of tooth surfaces, and cleaning of root surfaces; the zones of necrosis are small, so that there is no residual debris.

The effects of pulsed ultraviolet and infra-red lasers on dental enamel.

To evaluate micromorphological changes seen in enamel following irradiation with pulsed lasers, extracted human teeth were treated with a TEA-CO2, an Er:YAG and an ArF laser systems. Light and scanning electron microscopic studies demonstrate that the Er:YAG laser produces a zone of microcracks in the subsurface area. While TEA-CO2 laser irradiation results mostly in surface melting, the Er:YAG laser produces a roughened enamel surface. After ArF laser irradiation a retentive surface appears, accompanied by some melting effects and an increased porosity. The observed results of all the employed laboratory type lasers varied over a wide range due to the widespread biologic differences in tooth structures.