Summary
To evaluate the in vitro fracture load of extensively damaged vital teeth after either direct or indirect restauration, severe tooth substance loss was simulated for 96 molars. Subsequently, ...two cavities were prepared with little (design 1) or more substantial (design 2) residual tooth support. All molars were provided with a 2‐mm ferrule design and then divided into 12 test groups based on their occlusal surface size. They were restored with composite or with either of two types of single crown (cast metal or milled zirconia). After thermal ageing (10 000 cycles at 6·5 and 60 °C), 1·2 million cycles of chewing simulation were applied (64 N). Maximum fracture load was determined with a loading angle of 45°. Statistical analysis was performed by use of Kaplan–Meier modelling, Student's t‐tests, one‐way anova, post hoc Tukey's HSD tests and linear regression analysis. Regarding mean fracture load without ageing, the indirect restorations outperformed composite (design 1: direct: 508 ± 123 N, indirect: 741 ± 248 N; design 2: direct: 554 ± 167 N, indirect: 903 ± 221 N). After artificial ageing, however, these differences were no longer significant (design 1: direct: 328 ± 189 N, indirect: 506 ± 352 N; design 2: direct 399 ± 208 N, indirect 577 ± 292 N). Instead, the fracture load of the aged composite restorations was comparable with that for zirconia (design 1) and cast metal (design 2) crowns. Fracture loads of direct composite restorations after artificial ageing might fulfil clinical requirements.
The 17th century author François Poulain de la Barre was both an important contributor to the history of feminist thought and a thoroughgoing Cartesian. Poulain borrows from many of Descartes's ...doctrines, including his dualism, distrust of epistemic authority, accounts of imagination, and passion, and at least some aspects of his doxastic voluntarism; here, I examine how he uses a Cartesian notion of prejudice for an anti‐essentializing philosophy of women's education and the formation of the tastes, talents, and interests of individuals. “Prejudice” remains Descartes's notion of an entrenched, yet self‐imposed doxastic commitment, but also takes on the sense of social‐political group bias, founded on custom, transmitted through education, serving interests, and forming social expectations. Poulain also expands on the Cartesian notion and themes by emphasizing widespread yet unjustified social opinions in favor of the status quo in both epistemic practices and epistemic authorities, while considering how biased beliefs about sexual difference and gender identity can be internalized even by those who suffer most from them. At the same time, he shows how powerful Cartesian concepts can be for feminist methodology.
Many contemporary social epistemologists take themselves to be combatting an individualist approach to knowledge typified by Descartes. Although I agree that Descartes presents an individualist ...picture of scientific knowledge, he does allow some practical roles for reliance on the testimony and beliefs of others. More importantly, however, his reasons for committing to individualism raise important issues for social epistemology, particularly about how reliance on mere testimony can propagate prejudices and inhibit genuine understanding. The implications of his views are worked out more fully by some of his immediate successors; I examine how François Poulain de la Barre, and (briefly) Mary Astell analyze the social conditions for epistemic agency in a Cartesian vein.
In a significant fraction of the Escherichia coli cytosolic proteins, the N-terminal methionine residue incorporated during the translation initiation step is excised. The N-terminal methionine ...excision is catalyzed by methionylaminopeptidase (MAP). Previous studies have suggested that the action of this enzyme could depend mainly on the nature of the second amino acid residue in the polypeptide chain. In this study, to achieve a systematic analysis of the specificity of MAP action, each of the 20 amino acids was introduced at the penultimate position of methionyl-tRNA synthetase of E. coli and the extent of in vivo methionine excision was measured. To facilitate variant protein purification and N-terminal sequence determination, an expression shuttle vector based on protein fusion with β -galactosidase was used. From our results, methionine excision catalyzed by MAP is shown to obey the following rule: the catalytic efficiency of MAP, and therefore the extent of cleavage, decreases in parallel with the increasing of the maximal side-chain length of the amino acid in the penultimate position. This molecular model accounts for the rate of N-terminal methionine excision in E. coli, as deduced from the analysis of 100 protein N-terminal sequences.
Zusammenfassung
Studien konnten zeigen, dass Verbindungen des N. trigeminus zu haltungsregulierenden Systemen, wie z. B. zum Nucleus vestibularis bestehen. Ebenso können somatosensorische ...Informationen aus den Regionen von Kopf und Gesicht in weit gestreute und funktionell heterogene Areale des ZNS fortgeleitet werden, woraus auch eine wichtige Funktion dieser Verbindungen für die Stabilisation und Koordination der Kopfhaltung und der Augenbewegungen abgeleitet werden. Des Weiteren sind motorisch relevante Phänomene wie z.B. erhöhte Amplituden des Soleus H-Reflexe und eine generell erhöhte Erregbarkeit des motorischen Systems unter dem Einfluss von Beißaktivitäten beschrieben worden. Vor dem Hintergrund. Ergebnisse aus Studien der Autoren geben einen Hinweis darauf, dass kontrollierte motorische Aktivität des CMS Einfluss auf die statische und dynamische Stabilität des menschlichen Körpers nehmen können. Mögliche pathophysiologische Zusammenhänge zwischen Bruxismus, Nackenmuskulatur und Körperhaltung werden ebenfalls in diesem Artikel dargestellt.
Schmitter M, Lippenberger S, Rues S, Gilde H, Rammelsberg P. Fracture resistance of incisor teeth restored using fibre‐reinforced posts and threaded metal posts: effect of post length, location, ...pretreatment and cementation of the final restoration. International Endodontic Journal, 43, 436–442, 2010.
Objective The hypothesis of this study was that the fracture load of incisor teeth restored using short, threaded, parallel‐sided posts (TMP) is, under special conditions, not inferior to that of teeth restored using long TMPs or fibre‐reinforced posts (FRP).
Methodology Seventy‐two maxillary incisors and 72 mandibular incisors were collected. Sixty‐four in each group were root filled; in half of these FRPs were cemented, and in the other half TMPs were used. Half of the FRPs were pretreated; the others were not pretreated. In the TMP‐group, half of the teeth received a long post (10 mm), the other half a short post (3 mm). Crowns were fabricated and cemented with Ketac‐cem or Panavia. Eight maxillary incisors and eight mandibular incisors with intact natural crowns were used as control groups. All specimens were loaded until fracture.
Results Fracture loads were higher for pretreated FRPs than for untreated FRPs. If the FRPs were not pretreated, fracture loads for maxillary incisors after use of short metal posts were significantly higher (248 N compared with 133 N, P = 0.027). Fracture loads for teeth restored using long TMPs were not higher than for teeth restored using short TMPs (277 N compared with 266 N). Fracture loads for mandibular incisors restored using long (10 mm) pretreated FRP were higher than for mandibular incisors restored using short (3 mm) metal posts (436 N compared with 285 N). Cementation of the crowns using an adhesive resin cement did not increase the fracture load for mandibular incisors, whereas for maxillary incisors, this cementation technique tended to increase fracture loads in teeth restored with FRP, although this increase was not significant at the P < 0.05 level (P = 0.06). In both groups, fracture loads were higher for mandibular incisors.
Conclusions Short, threaded, parallel‐sided metal posts might be an alternative to fibre‐ reinforced posts for maxillary incisors, for teeth with short roots or when FRP cannot be pretreated.
Summary Temporary or persisting dysesthesia of the nervus alveolaris inferior has often been described as a complication of implant surgery of the lower mandible. In most cases, lesion of the nerve ...results in anaesthesia of the innervated region, a symptom clearly indicative of correct diagnosis. In our case report, however, a minor perforation of the roof of the mandibular canal during implant placement apparently provoked discrete irritation of the nerve, resulting in persistent neuropathic pain without concomitant hypesthesia or dysesthesia. Because the canal could not be detected in conventional dental radiographs, this uncharacteristic situation made correct diagnosis difficult and led to unnecessary surgical procedures including extraction of adjacent teeth. Medical imaging computed tomography (CT) finally revealed the close proximity of the apex of the implant and the bony structure of the mandibular canal. The effect on the nervus alveolaris inferior was also demonstrated using an innovative high‐resolution dental magnetic‐resonance‐imaging technique reflecting vascular reactions of the neurovascular bundle after potentially damaging surgical intervention. After removal of the causative implant, the pain gradually faded over a period of a year.
Objectives
A key aspect of complex restorative therapy is reconstruction of a new three-dimensional jaw relation. The objective of this study was to test the hypotheses that the initially recorded ...jaw relation would deviate substantially from the jaw position of the prosthetic reconstruction and that activity ratios of the jaw muscles would be significantly different for each of these jaw positions.
Materials and methods
In 41 healthy subjects, 41 examiners incorporated intraoral occlusal devices fabricated with all the technical details and procedures commonly used during prosthetic reconstructions. The jaw positions in centric relation with the incorporated occlusal devices were telemetrically measured in the condylar, first molar and incisal regions, relative to intercuspation. Electromyographic (EMG) activity of the temporalis and masseter muscles was recorded, and activity ratios were calculated for homonymous and heteronymous muscles.
Results
The recorded jaw relation differed significantly (
p
< 0.001) from the jaw position reconstructed with the intraoral occlusal devices. The initially recorded jaw relation was reproduced with the intraoral occlusal device with spatial accuracy of approximately 0.3 mm in the condylar, molar and incisal regions. The EMG ratios between centric relations and the reconstructed positions were significantly different (
p
< 0.05) for the temporal muscle and the temporalis/masseter ratio.
Conclusions
The findings revealed that three-dimensional jaw-relation recording may be reproduced in a simulated prosthetic reconstruction within the accuracy reported for replicate intraoral bite recordings.
Clinical relevance
Centric relation recordings may be reproduced in a prosthetic reconstruction with the spatial accuracy of 0.3 mm.
Purpose: To develop a validation process for a software application to be used for digital RT data review in industry sponsored trials. Method and Materials: FDA guidance documents were used to ...formulate a validation process, which was applied to a customized version of the software application CERR (Computational Environment for Radiotherapy Research, http://radium.wustl.edu/CERR). The validation approach classified CERR as a 3rd party software application. As such, sufficient testing was required to establish that the software met “user needs and intended uses.” User requirements were specified and divided into six broad categories: (1) import functionality (both RTOG and DICOM RT), (2) viewer functionality, (3) plan tools (renaming, summing, beam data display), (4) structure tools (contouring, expanding, combining structures), (5) DVH tools, (6) study tools (anonymization, import log display). Eight data sets were identified for testing the functionality. Three data sets were in RTOG format; five were DICOM RT. Planning systems represented included Eclipse, Pinnacle and XiO. Studies were chosen that contained features relevant to the tests to be performed. For some of the studies planning system output in electronic format was available for comparison with CERR. 72 tests were performed, covering each area of the required functionality. Each test was assigned criteria for acceptability. Results: The results of eight tests, all related to DVH tools, did not meet the specified criteria. Discrepancies were noted for structures with small volumes and for structures receiving very low doses. Two tests had discrepancies because one structure was partially outside the dose grid. Conclusion: A validation process compliant with FDA guidelines has been developed and implemented to validate a digital RT review application. The validation test procedures will be made available to other review centers using similar software applications. This work was supported by NIH/NCI U10 Grant CA29511.
A posttranslational modification was detected in the carboxyl-terminal region of axonemal tubulin from Paramecium. Tubulin carboxyl-terminal peptides were isolated and analyzed by Edman degradation ...sequencing, mass spectrometry, and amino acid analysis. All of the peptides, derived from both α and β tubulin subunits, were modified by polyglycylation, containing up to 34 glycyl units covalently bound to the γ carboxyl group of glutamyl residues. This modification, present in one of the most stable microtubular systems, may influence microtubule stability or axoneme function, or both.
PDF
