Glass fiber-reinforced endodontic posts are considered to have favorable mechanical properties for the reconstruction of endodontically treated teeth. The aim of the present investigation was to evaluate the survival of two tapered and one parallel-sided glass fiber-reinforced endodontic post systems in teeth with different stages of hard tissue loss and to identify risk factors for restoration failure. One-hundred and forty-nine glass fiber-reinforced endodontic posts in 122 patients were followed-up for 5-56 months [mean +/- standard deviation (SD): 39 +/- 11 months]. Glass fiber-reinforced endodontic posts were adhesively luted and the core was built with a composite resin. Cox proportional hazards models were used to evaluate the association of clinical variables and failure rate. Higher failure rates were found for restorations of anterior teeth compared with posterior teeth [Hazard-Ratios (HR): 3.1; 95% confidence interval (CI): 1.3-7.4], for restorations in teeth with no proximal contacts compared with at least one proximal contact (HR: 3.0; 95% CI: 1.0-9.0), and for teeth restored with single crowns compared with fixed bridges (HR: 4.3; 95% CI: 1.1-16.2). Tooth type, type of final restoration and the presence of adjacent teeth were found to be significant predictors of failure rates in endodontically treated teeth restored with glass fiber-reinforced endodontic posts.

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Artifact size cannot be predicted merely from the designation "steel". Nor did the crystalline structure of the baseline material from which a steel device had been produced have major implications for artifact size. Relevant, however, was the magnetic permeability (or susceptibility) of the final products, which is not disclosed by the manufacturers, and it cannot be measured on fixed intraoral appliances. Furthermore, the present investigation reveals that some steel devices can remain in situ without triggering adverse consequences.

Objectives: We investigated artefacts caused from orthodontic appliances at 1.5-T MRI of the head and neck region and whether the image quality can be improved utilizing the artefact-minimizing sequence WARP. Methods: In vitro tests were performed by phantom measurements of different orthodontic devices applying different types of MR sequences [echoplanar imaging (EPI), turbo spin echo (TSE) and TSE-WARP, gradient echo (GRE)]. Two independent readers determined after calibration the level of artefacts. Subsequently, the interobserver agreement was calculated. The measurement of artefacts was based on the American Society for Testing Materials Standard F 2119-07. For in vivo imaging, one test person was scanned with an inserted multibracket appliance. The level of artefacts for 27 target regions was evaluated. Results: In vitro: ceramic brackets and ferromagnetic steel brackets produced artefact radii up to 1.12 and 7.40 cm, respectively. WARP reduced these artefacts by an average of 32.7%. The Bland-Altman-Plot indicated that maximum measurement differences of 3 mm have to be expected with two calibrated observers. In vivo: the EPI sequence for brain imaging was not analysable. The TSE sequence of the brain did not demonstrate artefacts except for the nasal cavity. Conversely, the TSE sequence of the cervical spine revealed severe artefacts in the midface region. The GRE sequence appeared to be more susceptible to artefacts than did the TSE sequence. Conclusions: In vitro measurements allow an estimation of the in vivo artefact size. Orthodontic appliances may often remain intraorally when performing MRI. WARP showed a more significant effect in vitro than in vivo. Dentomaxillofacial Radiology (2015Radiology ( ) 44, 20140416. doi: 10.1259 Cite this article as: Zachriat C, Asbach P, Blankenstein KI, Peroz I, Blankenstein FH. MRI with intraoral orthodontic appliance-a comparative in vitro and in vivo study of image artefacts at 1.5 T. Dentomaxillofac Radiol 2015; 44: 20140416.

This study clarifies whether an orthodontic appliance must be removed before taking an MRI.

From the patient's perspective, remounting of CDs will be positively perceived, irrespective of the use of a face-bow.

Further research is necessary to determine the effects of different arbitrary face-bows on the fabrication and adaptation of removable dentures.

For endodontically treated teeth, there are no standardized measures available to define the extent of loss in tooth substance prior to final restoration. In this study, defect size was classified and the applicability of the classification was tested related to the inter- and intra-examiner reliability. For classification, three parameters were investigated: (i) remaining tooth substance in the vertical dimension (level A-D, aspect I), (ii) remaining tooth substance as regarded horizontally (mm; bucco-lingual and mesio-distal, aspect II), and (iii) size of the orifice (mm; aspect III). Four non-calibrated or (pre-trained) examiners were asked to gauge and classify 20 casts of clinically broken down teeth. The measurements were repeated twice every alternative week giving three separate readings. Inter-examiner reliability was determined at weeks 1, 3 and 5. The intra-examiner reliability was compared between readings 1 and 2, 1 and 3, and 2 and 3. As statistical tests, intra-class correlation (ICC) and Cohen's kappa (weighted) were used at a significance level of P < 0.05. Inter- and intra-examiner reliability for ordinal data (aspect I) revealed, with one exception, 'moderate' to 'very good' evaluations. Inter- and intra-examiner reliability (ICC) of metric data of aspect II and III was primarily 'excellent'. It may be concluded that the newly developed classification could be applied as an appropriate and reproducible method to define defect extension in endodontically treated teeth.