26 research outputs found
Reliable release testing for nanoparticles with the NanoDis System, an innovative sample and separate technique
One of the critical quality attributes of nanoparticle formulations is drug release. Their release properties should therefore be well characterized with predictive and discriminative methods. However, there is presently still no standard method for the release testing of extended release nanoformulations. Dialysis techniques are widely used in the literature but suffer from severe drawbacks. Burst release of formulations can be masked by slow permeation kinetics of the free drug through the dialysis membrane, saturation in the membrane, and absence of agitation in the membrane. In this study, the release profile of poly(lactic co-glycolic) (PLGA) nanocapsules loaded with all-trans retinoic acid was characterized using an innovative sample and separate set-up, the NanoDis System, and compared to the release profile measured with a dialysis technique. The NanoDis System showed clear superiority over the dialysis method and was able to accurately characterize the burst release from the capsules and furthermore discriminate between different all-trans retinoic acid nanoparticle formulations
Assessment of canal walls after biomechanical preparation of root canals instrumented with protaper universalTM rotary system
OBJECTIVE: The aim of this study was to examine the instrumented walls of root canals prepared with the ProTaper UniversalTM rotary system. MATERIAL AND METHODS: Twenty mesiobuccal canals of human first mandibular molars were divided into 2 groups of 10 specimens each and embedded in a muffle system. The root canals were transversely sectioned 3 mm short of the apex before preparation and remounted in their molds. All root canals were prepared with ProTaper UniversalTM rotary system or with NitiflexTM files. The pre and postoperative images of the apical thirds viewed with a stereoscopic magnifier (X45) were captured digitally for further analysis. Data were analyzed statistically by Fisher's exact test and Chi-square test at 5% significance level. RESULTS: The differences observed between the instrumented and the noninstrumented walls were not statistically significant (p<0.05). CONCLUSIONS: The NitiflexTM files and the ProTaper UniversalTM rotary system failed to instrument all the root canal walls
The effect of various mixing and placement techniques on the compressive strength of mineral trioxide aggregate
Introduction: The aim of this study was to evaluate the
effect of various mixing techniques including mechanical
and manual mixing as well as the effect of ultrasonic
agitation during placement on the compressive strength
of mineral trioxide aggregate (MTA). Methods: Toothcolored
ProRoot MTA (Dentsply Maillefer, Ballaigues,
Switzerland) and white MTA Angelus (Angelus Soluc¸~oes
Odontologicas, Londrina, Brazil) were used. One gram of
each powder was mixed with a 0.34-g aliquot of distilled
water. Specimens were mixed either by mechanical mixing
of capsules for 30 seconds at 4,500 rpm or by a saturation
technique and the application of a condensation
pressure of 3.22 MPa for 1 minute. Half of the specimens
were placed in stainless steel molds and agitated using
indirect ultrasonic activation. All specimens were subjected
to compressive strength testing after 4 days.
Results: The compressive strength values of ProRoot
MTA were significantly greater than those of MTA
Angelus (P < .05). The highest compressive strength
values were recorded from ProRoot MTA samples that
were mixed mechanically and placed using ultrasonic
activation (mean = 101.71 MPa), whereas the lowest
values were recorded for MTA Angelus samples that
were mixed manually and placed without ultrasonic
activation (mean = 53.47 MPa). Ultrasonically agitated
groups had higher compressive strength values
(P < .001). The specimens mixed mechanically had
higher compressive strength values than those mixed
manually (P < .05). Conclusions: The compressive
strength values of ProRoot MTA were significantly
greater than those of MTA Angelus. Mechanical mixing
enhanced the compressive strength of the material.
Regardless of the mixing techniques applied, ultrasonic
agitation improved the compressive strength of the
material