No abstract

Saline solutions of manganese ions (Mn2+) were used as articular contrast agents in magnetic resonance microscopy (9.4 T) of cartilage of chicken femoral condyles and pig temporomandibular joints. The diffusion of Mn2+ from the articular surface into the cartilage matrix led to a strong contrast enhancement in the cartilage. The combination of the high spatial resolution and the contrast enhancement allowed the visualization of fine structures (tissue types) in the cartilage, which correlate with the tissue zones in histological sections stained with cationic dyes. We assume that the electrostatic interactions between the negatively charged groups of the proteoglycans and Mn2+ are most important for the mechanism of contrast enhancement. Hence, the different signal intensities of the various zones of cartilage indicate differences in density of proteoglycans. The intraarticular injection of the cationic contrast agent could improve the possibility of an early diagnosis of cartilage dysfunction and degeneration.

The results show that 3D representation with superimposition of the individual results offers the clinician clear, continuous monitoring of the treatment progress. In comparison with the control group, the cleft patients showed significantly greater vertical deviations in nasal direction in the region of the incisor and canine points at each observation timepoint. A significant reduction in vertical divergences was recorded only in the region of the cleft pole point of the larger segment during the study period. The results furthermore suggest that investigation of absolute changes in segment positions alone in comparison with relative growth changes may lead to misinterpretations.

To minimize relapse rates in cases of severe crowding, we recommend that the canines and second molars be included in the appliance.

Our results suggest that the timing of hard-palate closure is not a decisive factor for upper-jaw development. Intrinsic factors (initial cleft width, presence of tooth buds) and the surgeon's skills appear to have a much more defining role.