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Biomedical subjects

B Haller

Publications and source records attributed to B Haller.

At least 19 recordsLinked to original sources
PubMed2002

Expression of amelin and trauma-induced dentin formation.

According to recent studies, amelin (ameloblastin, sheathlin) is expressed in young odontoblasts at the initiation of dentin formation during odontogenesis. The purpose of the present investigation was to study whether amelin is also expressed at the onset of trauma-induced reparative dentin formation. The mandibular developing first molars of 5-day-old rats were surgically taken out, and their pulp tissue briefly separated from the inner dentin surface and immediately repositioned. Then the teeth were re-implanted in their alveoli. At 0, 2, 4, 6, 8, 12 or 14 days after surgery, the animals were sacrificed and the experimental teeth evaluated by histology and immunohistochemistry for amelin. At 2, 4, 6 and 8 days after surgery, the detached and traumatized odontoblasts in the experimental teeth exhibited increasing signs of degeneration and loss of intracellular structures. At days 6 and 8 after surgery, immunohistochemistry revealed a strong staining for amelin in the traumatized odontoblastic layer. Twelve and 14 days after replantation, only necrotic cell remnants of the traumatized odontoblasts were discernible. At this stage, no amelin could be detected by immunostaining. A wide zone of an unorganized mineralized tissue surrounded the odontoblastic cell remnants. On the pulpal side of the unorganized tissue, a new, highly organized tubular reparative dentin layer was observed, bordered by columnar odontoblast-like cells abutting on newly formed predentin. The results indicate that the initiation of trauma-induced reparative dentin formation mimics that of primary dentin formation and that amelin seems to be involved in both processes, possibly as a signaling molecule.

Animals↗
PubMed2002

Infiltration and inflow in combined sewer systems: long-term analysis.

A study was conducted on 34 German combined sewer systems including combined sewer overflow (CSO) tanks and treatment plant to show up actual hidden reserves and bottlenecks in stormwater treatment. The study gave also a general insight into the water pathways in urban hydrology. A special focus was given to undesired non-polluted water infiltrating into the sewer, labelled infiltration and inflow (I/I) or infiltration inflows, which is widely underestimated. It leads to a bad performance of the drainage system although the parasite waters are themselves non-polluted. In existing combined systems, pollution control can be considerably improved by reducing I/I. It is equivalent to the reduction of surface runoff e.g. by a separate drainage as frequently proposed alternative. Artificial infiltration of surface runoff may even increase infiltration inflows.

Cities↗
PubMed2000

Effect of intrinsic and extrinsic moisture on bond strength to dentine.

OBJECTIVES: The aim of this in vitro study was to investigate the effects of simulated pulpal pressure (PP) and moist bonding (MB) on the shear bond strength of three different dentine bonding systems (DBSs). METHODS: Dentine surfaces were exposed on 120 extracted human molars and bonded with one out of three restorative systems (A. R.T. Bond/Brilliant, OptiBond FL/Herculite XRV, Scotchbond 1/Z100). In one-half of the specimens, the DBSs were applied under hydrostatic pulpal pressure of 30 cm H2O (PP). Forty specimens were prepared for each DBS according to the following experimental groups (each n=10): no PP/no MB; with PP/no MB; no PP/with MB; with PP/with MB. Shear bond strengths after 24 h were measured in a universal testing machine (Zwicki 1120) and statistically analysed by 2-way ANOVA. Fractured surfaces were investigated for the type of failure under an optical stereomicroscope and by SEM. RESULTS: In all DBSs, pulpal pressure resulted in a decrease of dentinal bond strength. This effect was significant in A.R.T. Bond and OptiBond FL (P<0.001), but not in Scotchbond 1 (P=0.060). Moist bonding significantly increased the bond strength of Scotchbond 1 (P<0.001), significantly decreased the bond strength of A.R.T. Bond (P=0.032), but had no effect in the case of OptiBond FL (P=0.691). In A.R.T. Bond, the combination of hydrostatic pulpal pressure and moist bonding resulted in complete failure of most of the specimens prior to the debonding tests. The fracture patterns as detected by SEM fracture analyses were typical for each DBS and specific bonding condition and consistent with the results of the bond strength measurements. SIGNIFICANCE: The results indicate that continuous intrinsic moisture in the form of hydrostatic pulpal pressure adversely affects the efficacy of DBSs, while limited extrinsic moisture by moist bonding is acceptable or even essential. The effect of moist bonding on the efficacy of DBSs seems to depend not only on the monomers used and the solvents per se, but also on the water content of the dentine primer and the self-priming adhesive, respectively.

Adhesives↗
PubMed2000

Growth inhibitory activity of gutta-percha points containing root canal medications on common endodontic bacterial pathogens as determined by an optimized quantitative in vitro assay.

Gutta-percha points containing calcium hydroxide, zinc oxide (ZnO), a mixture of ZnO and chlorhexidine (ZnO/CHX), iodine-polyvinylpyrrolidone (ZnO/J-PVP), or a mixture of CHX and J-PVP and ZnO (ZnO/CHX/J-PVP) were tested for their ability to inhibit growth of pure cultures of bacterial species commonly involved in endodontic infections (Peptostreptococcus micros, Streptococcus intermedius, Enterococcus faecalis, and Porphyromonas gingivalis). To quantitate growth inhibition, an in vitro assay was established that controlled for important parameters of root canal infection. Approximately 10(7) bacteria per assay were suspended in diluted human serum and co-incubated with the gutta-percha points in an anaerobic atmosphere for up to 2 wk. Aliquots used for determination of colony counts were taken on days 0, 1, 2, 4, 7, and 14 of incubation. As judged by colony-forming unit reduction kinetics and final counts, calcium hydroxide had better growth inhibitory activity than ZnO/CHX, ZnO/J-PVP, and ZnO alone for all bacteria tested except Peptostreptococcus micros. The combination of CHX and J-PVP with ZnO did not render results different from those of ZnO/CHX or ZnO/J-PVP. The results of this study support the introduction of standardized assays for testing antibacterial properties of root canal medications under conditions that more closely resemble those encountered in endodontal infections.

Anti-Infective Agents, Local↗
PubMed2000

Quantitation of Helicobacter pylori in dental plaque samples by competitive polymerase chain reaction.

AIM: To establish a competitive PCR (cPCR) assay for quantitation of H pylori organisms in dental plaque samples. METHODS: The cPCR co-amplified target H pylori DNA and a known amount of internal standard template in the same tube with the same primers directed to 0.86 kb DNA of H pylori. The internal standard was a synthesised DNA bearing the same primer recognition sites at two ends and a non-homologous core sequence as the target DNA fragment. Quantitation was based on determination of the relative, not absolute, amounts of the differently sized and [32P]-dCTP labelled products derived from H pylori DNA and the competitive internal standard after gel electrophoresis separation. RESULTS: A significant correlation between known amounts of H pylori added to dental plaque samples and the results of the cPCR was found, and a standard line was developed which allowed quantitation of H pylori in the plaque samples. cPCR was performed on supragingival plaque samples from 10 adult patients with H pylori infection in the stomach, and from five adults and six children without H pylori infection in the stomach. The ranges of H pylori numbers were 1-213 (median 25), 6-76 (10), and 4-94 (14) cells/mg of dental plaque in the three groups, respectively. CONCLUSIONS: cPCR is useful for quantitation of H pylori in supragingival dental plaque samples; however, the number of the organisms in dental plaque samples seems very low.

Adolescent↗
PubMed2000

Recent developments in dentin bonding.

Hybridization of the dentin with resin by monomer interdiffusion has been identified as the basic bonding mechanism resulting in an intimate interlocking of the cured resin with the dentin. Today, growing efforts are made to simplify and shorten the bonding procedures, e.g. by combining the functions of primer and adhesive. Ultrastructural investigations using high-resolution optical technology provided exciting insight into the interactions of bonding systems and dentin. It became clear, that the maintenance or recovery of microporosities in the dentin is most important for optimal hybridization. This can be achieved by the moist bonding technique, which is mandatory in acetone-based systems. The observation that certain bonding systems are able to bond to dentin depleted from the demineralized collagen network raised the question of whether the collagen-resin interdiffusion zone really represents a prerequisite for successful bonding to dentin. The use of strongly acidic primer monomers introduced the concept of "self-etching" primers not only to dentin but also to enamel, which eliminates the necessity of a separate conditioning step. Clinical investigations are necessary to evaluate the potential of recently developed all-in-one products which combine the functions of conditioner, primer, and adhesive. With improvements in dentin bonding and the development of new resins that exhibit little or no shrinkage upon polymerization, even greater applications for adhesive technology will be found in dentistry.

Acetone↗
PubMed2000

Effect of gingival fluid on marginal adaptation of Class II resin-based composite restorations.

PURPOSE: To evaluate in vitro the marginal quality of Class II composite restorations at the gingival enamel margins as affected by contamination of the cavities with gingival fluid (GF) during different steps of resin bonding procedures. MATERIALS AND METHODS: 70 Class II cavities were prepared in extracted human molars and restored with composite using a multi-component bonding system (OptiBond FL/Herculite XRV; OPTI) or a single-bottle adhesive (Syntac Sprint/Tetric Ceram; SYN). The cavities were contaminated with human GF: C1 after acid etching, C2 after application of the primer (OPTI) or light-curing of the primer-adhesive (SYN), and C3 after light-curing of the resin adhesive (OPTI). Uncontaminated cavities were used as the control (C0). The restored teeth were subjected to thermocycling (TC) and replicated for SEM analysis of marginal gap formation. Microleakage at the gingival margins was determined by dye penetration with basic fuchsin. STATISTICS: non-parametric tests (Kruskal-Wallis test, Mann-Whitney test with Bonferroni correction). RESULTS: In both bonding systems, contamination with GF after acid etching (C1) did not impair the marginal quality; the mean percentages of continuous margin/mean depths of dye penetration were: OPTI: C0: 88.5%/0.10 mm, C1: 95.6%/0.04 mm; SYN: C0: 90.9%/0.08 mm, C1: 97.0%/0.05 mm. Marginal adaptation was adversely affected when GF contamination was performed after

Acid Etching, Dental↗
PubMed1999

Helicobacter pylori in dental plaque: a comparison of different PCR primer sets.

This study was designed to compare different primer sets for PCR analysis of H. pylori in the same series of 40 dental plaque samples. Three pairs of primers, HPU1/HPU2, HP1/HP2, and EHC-U/EHC-L, directed to the urease A gene, 16S rRNA gene, or 860-bp DNA of H. pylori, respectively, were used. Our results demonstrate that EHC-L/EHC-U were more specific and sensitive for H. pylori added to saliva or dental plaque than HPU1/HPU2 and HP1/HP2. The detection rates for H. pylori DNA in dental plaque samples from randomly selected adult patients from the Dental Clinic of the University of Ulm were 26.5% (9/34) for HPU1/HPU2, 78.9% (30/38) for HP1/HP2, and 100% (40/40) for EHC-U/EHC-L (P < 0.001). Nested PCR using primers directed to the 860-bp DNA of H. pylori further confirmed the presence of H. pylori DNA (40/40) in all these samples. Our results indicate that primers EHC-U/EHC-L are to be recommended for PCR detection of H. pylori in the oral cavity.

Adult↗
PubMed1998

Effect of multi-step dentin bonding systems and resin-modified glass ionomer cement liner on marginal quality of dentin-bonded resin composite Class II restorations.

The use of resin composites in the restoration of Class II cavities with gingival margins located in dentin is still controversial. The purpose of this in vitro study was to evaluate the effect of four state-of-the-art multi-step dentin-bonding systems (A. R. T. Bond, Syntac, OptiBond DC, Scotchbond Multipurpose) on marginal adaptation and microleakage of dentin-bonded composite Class II restorations. A total of 72 Class II cavities with gingival margins in dentin were prepared in extracted molars and filled with fine-hybrid composites using a three-sited light curing technique. In one half of the cavities the pulpal wall was lined with a resin-modified glass ionomer cement liner (RM-GIC), in the other half a total bonding technique was applied. A. R. T. Bond and Syntac were tested with selective enamel etching (SE) and total etching (TE). Marginal adaptation was evaluated in a scanning electron microscope before and after thermocycling (TC). Microleakage was determined by dye penetration. After TC the proportions of continuous margin in dentin ranged from 37% (Syntac/SE) to 91.2% (A. R. T. Bond/TE). Scotchbond Multipurpose exhibited the lowest degree of microleakage (0.22 mm). Marginal enamel fracture was the most prevalent marginal defect at the enamel margins (8.3-22.2%). The use of the RM-GIC had no beneficial effect on any of the marginal parameters, either in dentin or in enamel. It is concluded that low degrees of marginal gap formation and microleakage can be achieved in totally bonded composite Class II restorations when using state-of-the-art multi-step bonding systems in combination with a meticulous incremental filling technique.

Composite Resins↗
PubMed1996

Effect of disodium monofluorophosphate, calcium and vitamin D supplementation on bone mineral density in patients chronically treated with glucocorticosteroids: a prospective, randomized, double-blind study.

To study the effect of fluoride on bone mineral density (BMD) in patients treated chronically with glucocorticosteroids, 15 subjects (renal grafted, n = 12; skin disease, n = 1; broncho pulmonary disorder, n = 1; Crohn's disease, n = 1) were prospectively studied in a double-blinded manner and randomly allocated either to group 1 (n = 8) receiving 13.2 mg/day fluoride given as disodium monofluorophosphate (MFP) supplemented with calcium (1,000 mg/day) and 25-hydroxyvitamin D (calcifediol) (50 micrograms/day), or to group 2 (n = 7) receiving Cas+ calcifediol alone. An additional group of 14 renal transplant patients treated chronically with glucocorticosteroids but exempt of specific therapeutic intervention for bone disease was set up as historical controls. BMD was measured by dual-energy X-ray absorptiometry (DXA, Hologic QDR 1000) performed at months 0, 6 and 12 for groups 1 and 2 (lumbar spine, total upper femur, diaphysis and epiphysis of distal tibia), or 11-31 months apart with calculation of linear yearly changes for the historical cohort. Lumbar BMD tended to rise in groups 1 and 2, and to fall in group 3, the change reaching statistical significance (p < 0.05) in group 1, thus leading to a significant difference between groups 1 and 3 (p < 0.05). At upper femur, tibial diaphysis and tibial epiphysis, no significant change in BMD occurred in any of the groups. In conclusion, lumbar BMD rises more after a mild dosis of fluoride given as MFP and combined to calcium and calcifediol than on Ca+ calcifediol alone, without changes in BMD at the upper femur or distal tibia.

Absorptiometry, Photon↗
PubMed1993

Effect of storage media on microleakage of five dentin bonding agents.

The objective of this study was to investigate the effect of different storage media on microleakage at the gingival margin of mixed Class V composite restorations. Human molars were either used immediately after extraction (control group) or after a 3-4 wk storage period in 1% chloramine, 70% ethanol, 10% formalin, or 0.1% thymol. Class V cavities with cervical margins in cementum or dentin were prepared and restored with a microfill composite using five different dentin bonding agents. After thermocycling (1440 x from 5 degrees C to 55 degrees C) and basic fuchsin staining, the depth of dye penetration at the gingival margins was determined and ranked on a scale of 0 to 4. Class V restorations in teeth stored in formalin showed significantly less microleakage (mean leakage score, MLS = 1.7) than restorations in freshly extracted teeth (control group; MLS = 3.1). Microleakage scores in teeth stored in chloramine (MLS = 2.7), ethanol (MLS = 3.0) or thymol (MLS = 3.2) were not significantly different from the microleakage scores in the control group. The improvement of in vitro efficacy of dentin bonding agents when using extracted teeth stored in formalin is probably a result of collagen cross-linking by formaldehyde. Since such an alteration of the dentin does not reflect the condition of the substrate in vivo, extracted teeth assigned for in vitro evaluation of dentin bonding agents should not be stored in formalin. In teeth stored in 1% chloramine, the sums of ranks and the rank orders of the dentin bonding agents were comparable to those in freshly extracted teeth.(ABSTRACT TRUNCATED AT 250 WORDS)

Analysis of Variance↗
PubMed1993

[The surface conditioning of pressed ceramics and its effect on the bond strength to composites].

After removal of the investment material, unpolished surfaces of pressed glass ceramics (Empress) are covered by a layer containing magnesium and phosphorus. This layer most likely results from the contact with the investment material during pressing. Following short-time conditioning with 5% HF-gel the superficial layer stays amorphous. After etching for 120 s most of the surface layer is removed revealing the fine grained etching pattern characteristic for this type of ceramics. Shear strength of composite luted to unetched pressed ceramic samples was rather low. After etching for 60 s bond strength was considerably higher, but only following 120 s of etching shear strength reached a level comparable to that of ground pressed samples and ground ingots after 60 s of etching. Since mechanical removal of the surface layer by grinding is not recommended, pressed glass ceramics should be etched for 120 s or longer to achieve an optimal bond strength to the luting composite.

Acid Etching, Dental↗
PubMed1991

Shear bond strength to dentin by simulation of three-dimensional Class V cavity configuration.

The purpose of this study was to investigate the effect of composite polymerization contraction on early shear bond strength of conventional and new dentin adhesives to dentin. The dentin adhesives selected for this study, i.e., Bondlite, Gluma, Prisma Universalbond, Scotchbond LC, Scotchbond 2, and XR Bonding, were tested in combination with Silux and in combination with their respective composites. The composite was applied to the treated dentin surface in cylindrical brass moulds of 4 mm diameter and 3 mm length. The configuration of cylindrical butt-joint Class V cavities was simulated by the coating of the insides of the brass moulds with silane in order that a chemical bond to the composite could be established. The results showed that shear bond strength to dentin was higher for XR Bonding and Scotchbond 2 compared with conventional phosphate ester-based dentin adhesives and Gluma. When XR Bonding or Scotchbond 2 was used, the obstruction of polymerization contraction had no effect on the bond strength to dentin. In contrast, the dentin adhesion of Scotchbond LC/Silux, Prisma Universalbond/Prisma Microfine, Bondlite/Herculite, and Gluma/Lumifor was adversely affected by the reduction of the unbonded composite surfaces. However, this effect was not observed when Prisma Universalbond, Bondlite, and Gluma were tested in combination with Silux. It can therefore be concluded that the effect of polymerization contraction on the bond strength to dentin depends not only on the dentin adhesive but also on the type of composite used.

Adhesives↗
PubMed1991

Parapulpal pins and their effects on the fracture resistance of pin-retained cores.

The bending characteristics of various parapulpal pins, the retention of a parapulpal pin in different core buildup materials, and the fracture resistance of pin-retained cores were investigated in an in-vitro study. In amalgam and composite cores, the use of parapulpal pins produced an increase in fracture resistance. The highest fracture resistance values were observed in amalgam cores, and the lowest fracture strength was exhibited by cores of glass ionomer cements (GICs) containing metallic particles. The different parapulpal pins and their flexural rigidity had little effect on the fracture resistance of the pin-retained cores. For extensive pin-retained cores it appears advisable to use GICs with restraint and, particularly in the case of large-scale bridge reconstructions, only after critical examination of the loading conditions.

Alloys↗
PubMed1991

[The effect of cavity finishing on the initial sealing capacity of amalgam fillings in vitro].

The effect of different cavity finishing methods on in-vitro microleakage of two amalgams (Amalcap non gamma 2 SAS, Tytin) was investigated by the dye penetration method. Amalcap non gamma 2 SAS demonstrated better sealing properties than Tytin. The highest degree of microleakage was observed when the cavities prepared with a diamond coated bur (mean particle size 80 microns) were left unfinished. The degree of marginal leakage in Class-I cavities was reduced by finishing their walls with tungsten carbide or diamond coated finishing burs. Cervical Class-II cavity walls finished with a tungsten carbide or a diamond coated finishing bur demonstrated lower marginal leakage than cervical walls finished with a gingival margin trimmer. Finishing of proximal Class-II cavity walls with tungsten carbide or diamond coated finishing burs followed by removal of the remaining enamel overhangs with a diamond coated file (Cavishape) resulted in a lower degree of dye penetration than finishing proximal walls with a proximal margin trimmer. The results indicate that Class-II cavities with minimal extension of the proximal walls can be effectively finished without using hand instruments.

Dental Amalgam↗
PubMed1990

[Ridge stabilization with adhesive inlays in MOD cavities].

The flexural rigidity of the buccal cusps of upper premolars was determined under a vertical load of 100 N by use of displacement transducers. The stiffness of the cusps was higher when the cavities were restored with cast gold onlays or with composite or ceramic inlays luted with composite resin. In most cases a decrease in cusp stiffness was observed after thermocycling of the teeth restored with composite or ceramic inlays. With amalgam restorations or cast gold inlays, the flexural rigidity of the cusps was not higher than that of the unrestored cavities.

Bicuspid↗