Fracture resistance and 2-body wear of 3-dimensional–printed occlusal devices

Statement of problem

Polymeric material for 3-dimensional printing can be used to fabricate occlusal devices. However, information about fracture resistance and wear is scarce.

Measuring the polymerization stress of self-adhesive resin composite cements by crack propagation

Clinical Oral Investigations - To test the polymerization stress of nine self-adhesive resin composite cements (G-CEM, iCEM, Bifix SE, Maxcem Elite, PANAVIA SA, SoloCem, SmartCem 2, SpeedCEM, RelyX...     

Heat distribution and heat transport in bone during radiofrequency catheter ablation

BACKGROUND: To assess the feasibility of percutaneous radiofrequency ablation in large bone tumours, the heat distribution in cortical bone and marrow around inserted electrodes was measured. METHODS: Fresh bovine cadaver tibial bones were locally heated through drill holes for a maximum of half an hour using water-cooled single radiofrequency electrodes (Radionics Instruments Inc) by pulsed energy. Temperatures were measured in the marrow canal as well as in cortical bone by thermocouples at various distances from the inserted probes. RESULTS: Perpendicular to the probe, hyperthermia of more than 50 degrees C could be created in bone marrow in a sphere of approximately 3 cm, and of approximately 1 cm in cortical bone. CONCLUSION: As irreversible cellular damage can be expected when increasing the temperature to 50 degrees C for a duration of 6 min, this method may be effective for the minimal invasive ablation of neoplasms within human bone in cigar-shaped regions of approximately 3-cm diameter.     

Intravenous mirtazapine is safe and effective in the treatment of depressed inpatients

Mirtazapine is a third-generation antidepressant with a dual mode of action. The oral administration has been shown to be effective and safe in the treatment of depressed patients. In this multicenter naturalistic study, we assessed the safety, tolerability, and therapeutic efficacy of intravenously administered mirtazapine in 80 moderately to severely depressed inpatients during a treatment period of 14 days. We found a significant decrease of the Hamilton Depression Rating Scale total score compared to baseline. Side effects were mild and transient. Our data indicate that intravenous mirtazapine is an effective, safe and well-tolerated treatment for depressed inpatients.     

High-strength CAD/CAM-fabricated veneering material sintered to zirconia copings — A new fabrication mode for all-ceramic restorations

ObjectivesWith this in vitro study the fracture strength of zirconia-based crown copings being veneered with a CAD/CAM generated high-strength ceramic cap by sintering is compared with anatomically identical zirconia-based crowns, which were either overpressed or veneered by the layering technique for completion.MethodsA 1.2 mm, 360° chamfer preparation was performed on a second maxillary molar and was dublicated 15 times in a cobalt–chromium-alloy. A sample of 45 zirconia copings was produced and divided into three groups. In the first group (VT) zirconia copings received conventional veneering in layering technique, in the second group the veneering porcelain was pressed over the zirconia coping (PT), and for the third group (ST) a CAD/CAM-fabricated high-strength anatomically shaped veneering cap was sintered onto the zirconia coping. All crowns were cemented conventionally onto their dies and tested in the universal testing machine until clinical failure. The fracture load data were compared by a one-way analysis of variance and a multiple comparison posthoc test (α < 0.05).ResultsSpecimens from group VT showed a mean (S.D.) fracture load of 3700.39 (1238.72) N, group OT 3523.73 (1181.11) N and group ST 6262.67 (2257.42) N. The difference between groups VT/OT and ST were statistically significant (P < 0.001).SignificanceThe new CAD/CAM-fabricated bilayered restorations (ST) were superior to the present techniques (VT and OT) in terms of fracture load and offer the possibility to produce cost-effective crowns and fixed partial dentures with a potential lower risk of chippings.     

Influence of different surface treatments on two-body wear and fracture load of monolithic CAD/CAM ceramics

Clinical Oral Investigations - To investigate two-body wear (2BW) and fracture load (FL) of monolithic ceramics after different surface pretreatments. Zirconia (MOZ), lithium-disilicate (LIT), and...     

3D-Navigation in der interstitiellen stereotaktischen Brachytherapie

Aim

The aim of this paper is to describe the adaption of 3D-navigation for interstitial brachytherapy. The new method leads to prospective and therefore improved planning of the therapy (position of the needle and dose distribution) and to the possibility of a virtual simulation (control if vessels or nerves are on the pathway of the needle).

Material and Methods

The EasyGuide Neuro^® navigation system (Philips) was adapted in the way, that needles for interstitial brachytherapy were made connectable to the pointer and correctly displayed on the screen. To determine the positioning accuracy, several attempts were performed to hit defined targets onphantoms. Two methods were used: “free navigation”, where the needle was under control of the navigation system, and the “guided navigation” where an algined template was used additonally to lead the needle to the target. In addition a mask system was tested, whether it met the requirements of stable and reproducible positioning. The potenitial of applying this method in clinical practice was tested with an anatomical specimen.

Results

About 91% of all attempts lied within 5 mm. There were even better results on the more rigid table (94% <4 mm). No difference could be seen between both application methods (“free navigation” and “navigation with template”), they showed the same accuracy.

Conclusions

The accuracy of the phantom experiments and the confirmation by the experiment with the anatomical specimen showed that excellent results can be expected in clinical practice using rigid tables and patient supporting systems.