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Biomedical subjects

H Schilder

Publications and source records attributed to H Schilder.

At least 19 recordsLinked to original sources
PubMed2002

Survival rate and fracture strength of incisors restored with different post and core systems and endodontically treated incisors without coronoradicular reinforcement.

This in vitro study evaluated the survival rate and fracture resistance of maxillary central incisors restored with different post and core systems. The post and core systems investigated were a prefabricated high precious metal post with cast core (group A), zirconia post with a prefabricated bonded ceramic core (group B), and a resin-ceramic interpenetrating phase composite post (experimental) with a prefabricated bonded ceramic core (group C). The all-ceramic copings were cemented using Panavia 21 TC. In the group without coronoradicular reinforcement, the access cavity was closed with a light-cured composite in combination with a dentine-bonding agent (group D). Each specimen was intermittently loaded and thermocycled before final stress tests in a Zwick machine. The survival rates after 1,200,000 cycles in the artificial mouth were 90% (group A), 80% (group B), 60% (group C), and 100% (group D). Statistically significant differences were found between all groups with the exception of A and B, when failure during cyclic loading was included (Kruskal-Wallis multiple comparisons test). Samples restored with a cast post and core demonstrated more vertical root fractures. It was concluded that the preservation of both internal and external tooth structure is of utmost importance when restoring endodontically treated teeth.

Cementation↗
PubMed1998

Endodontic pathogens stimulate monocyte chemoattractant protein-1 and interleukin-8 in mononuclear cells.

Microbial infection of the dental pulp leads to the recruitment of leukocytes and the formation of lesions of endodontic origin. The chemokines interleukin-8 (IL-8) and monocyte chemoattractant protein-1 (MCP-1) are relatively specific chemoattractants for neutrophils and monocytes, respectively. In the present studies, peripheral blood mononuclear cells were stimulated by Streptococcus mutants, Porphyromonas endodontalis, and Peptostreptococcus anaerobius, which are associated with lesions of endodontic origin. Each of these bacteria induced a dose-dependent increase in IL-8 and MCP-1, determined by ELISA. The levels induced are physiologically relevant. However, low doses of P. endodontalis were less effective in inducing IL-8 or MCP-1 expression, compared with S. mutants or P. anaerobius. Thus, these bacteria can induce significant levels of the chemokines IL-8 and MCP-1, which could contribute to the recruitment of neutrophils or monocytes in vivo. The expression of these mediators may contribute to the development of endodontic infections, particularly with regard to inflammatory leukocyte recruitment.

Animals↗
PubMed1994

Effectiveness of various medications on postoperative pain following complete instrumentation.

The root canals of 588 consecutive nonsurgical patients with varying levels of pain were completely instrumented in 10 endodontic practices and 4 endodontic graduate programs. The participants were sequentially assigned to one of nine medications and a placebo. The severity of pain was assessed by the visual analog scale for 72 h following instrumentation. Among all of the parameters studied, three factors (preoperative pain, apprehension, and types of medication) were found to be significant in determining postinstrumentation pain. An association was found between the intensity of pre-and postoperative pain. As the intensity of preoperative pain increased, the chances for more severe postoperative pain increased (p < 0.0001). In addition, an association between the presence of apprehension before any treatment and postoperative pain was also noted (between 0.012 < p < 0.047). Examination of the time-effect curves for various medications in patients with no mild pain showed no statistical significant difference between the effectiveness of different medications and placebo. However, a multiple comparison of the effectiveness of various medications and placebo on patients in moderate and severe preoperative pain showed that ibuprofen, ketoprofen, erythromycin base, penicillin, and methylprednisolone plus penicillin were more effective than placebo within the first 48 h following complete instrumentation.

Acetaminophen↗
PubMed1993

Biochemical and histochemical analysis of the enzyme arylsulfatase in human lesions of endodontic origin.

Lesions of endodontic origin are areas of inflammatory response which occur as a result of untreated disease process within the root canal system. Lysosomal hydrolytic arylsulfatase A and B have been identified as major enzymes initiating and propagating bone loss by degrading chondroitin-4-sulfate. The purpose of this investigation was to examine human lesions of endodontic origin for the presence of arylsulfatase A and B. Fifteen periapical lesions were obtained at the time of periapical surgery. The lesions were analyzed for the presence of arylsulfatases using the spectrophotometer by monitoring the liberated 4-nitrocatechol at 515-nm wavelength. The same lesions were examined histochemically using the electron microscope. Five control samples from healthy periodontal ligament were evaluated in a similar manner. The results showed higher levels of arylsulfatase A in lesions than in control tissues, and marked activity of arylsulfatase B in lesions, whereas no activity of this enzyme was detected in the control specimen. Histochemically, all lesions showed positive staining for enzyme activity, whereas the controls were negative. These findings indicate that arylsulfatase A and B play a role in the pathogenesis of human lesions of endodontic origin.

Alveolar Bone Loss↗
PubMed1992

Effects of moisture content and endodontic treatment on some mechanical properties of human dentin.

The objective of this study was to determine whether significant differences exist between the mechanical properties of human dentin from treated pulpless teeth and dentin from normal vital teeth. Dentin specimens (n = 262) were obtained from 54 freshly extracted normal vital human teeth and 24 treated human pulpless teeth. These specimens were subjected to different experimental conditions (wet, air dried, desiccated, and rehydrated). Compression, indirect tensile, and impact tests were conducted to measure the mechanical properties of those specimens. All data obtained were analyzed with t tests. The results showed that the dehydration of dentin increases the Young's modulus, proportional limit (in compression), and especially the ultimate strength (in both compression and tension). Substantial dehydration changes the fracture characteristics of dentin specimens under static compressive and indirect tensile loadings. The measurements of impact-breaking energies of desiccated dentin were not found to be significantly decreased. The compressive and tensile strengths of dentin from treated pulpless teeth obtained in this study do not appear to be significantly different from those of normal dentin (p > 0.05), while the mean values of Young's modulus and proportional limit in compression tests appear to be lower. Fifty percent of the dentin specimens from treated pulpless teeth exhibit greater plastic deformation than normal dentin in compression. The results of this study do not support the theory that dehydration after endodontic treatment per se weakens dentin structure in terms of compressive and tensile strengths. Other mechanical properties of treated pulpless teeth, however, may not be the same as those of normal vital teeth.

Dental Pulp Devitalization↗
PubMed1985

The thermomechanical properties of gutta-percha. Part V. Volume changes in bulk gutta-percha as a function of temperature and its relationship to molecular phase transformation.

A variety of gutta-percha materials was subjected to dilatometric analysis to measure volume changes which take place with heating and cooling. The volume changes were found to be related directly to the molecular transformation kinetics of the polymer material and to the temperature ranges within which they take place. If the gutta-percha in the apical segment is not elevated above 45 degrees C, molecular transformation is avoided and the ultimate volume changes which accompany temperature cycling are small, predictable, and controllable.

Chemical Phenomena↗
PubMed1984

The basement membrane of the enamel organ in human odontogenesis.

This study was designed to record findings of a basement membrane in human fetal jaws relative to the oral epithelium, dental lamina, and developing teeth. With the use of Lillie's allochrome stain, this could be followed from the oral epithelium and dental lamina to the tooth jaws. The basement membrane was easily traced along the inner enamel epithelium, but only after elimination of the counterstaining phases was it visible adjacent to the outer enamel epithelium.

Basement Membrane↗
PubMed1981

The thermomechanical properties of gutta-percha. Part IV. A thermal profile of the warm gutta-percha packing procedure.

A thermal profile of the warm gutta-percha technique was produced by the thermocouple instrumentation of natural teeth and the subsequent monitoring of intraradicular temperature changes during the packing procedure. Although variations in thermal patterns resulted from individual differences in timing and instrumentation, certain clinically accepted patterns of activity produced consistent, representative temperature ranges to which the gutta-percha in the body of the canal was 80 degrees C., while the over-all peak temperature recorded in the apical region was 45 degrees C. Thermal penetration of the gutta-percha was expectedly limited, with significant thermal effects rarely exhibited more than 4 to 6 mm. into the material.

Gutta-Percha↗