[Effect of the vacuum-formed retainer on preventing the proximal contact loss between implant supported crown and adjacent natural teeth]

OBJECTIVE

To evaluate the effect of the vacuum-formed retainer on preventing the proximal contact loss between the implant supported crown and its adjacent natural teeth.

METHODS

Forty-six posterior implant crowns in the mandible including 92 interproximal contacts in 46 patients (19 men, 27 women) aged from 25 to 66 years were included. The participants in experimental group (22 cases) were vacuum-formed retainers at night, while participants in control group (24 cases) only received routine examination. The two groups were not different in age, gender, the time interval of the tooth loss and tooth position at baseline. Mesial and distal proximal contact tightness was measured using the orthodontic dynamometer and metallic articulating film immediately after crown delivery, and 1-month, 3-month, 6-month, and 1-year follow-up respectively. The articulating film was inserted interdentally from the occlusal direction, and then it was slowly removed in the buccallingual direction by the dynamometer. Increasing the number of films (N) piece by piece until the frictional force (F) was great than 0, and the number of films (N) was recorded. At each follow-up, proximal contact between implant crown and its adjacent teeth was considered to be loss if the number of films (N) used at immediate crown delivery passed without frictional force (F=0). Besides, the periodontal conditions [scored according to the probing depth (PD), bleeding index (BI), mobility (M)] and complaint of food impaction were recorded. The mesial and distal proximal contact loss rates were compared between the two groups at different times. Chi-square test or Fisher's exact test was used for statistical analysis.

RESULTS

The proximal contact loss rate on the mesial surface of the implant supported crown continuously increased over the follow-up periods. At the end of the 1-, 3-, and 6-month follow ups, 18.2%, 22.7% and 27.3% were identified for the contact loss rates on the mesial surface of the implant supported crown in the experimental group, respectively. Meanwhile in control group, the rates were 20.8%, 37.5% and 45.8%. No significant differences were observed at the end of the 1-, 3-, and 6-month follow ups(1-month: χ²=0.000, P=1.000; 3-month: χ²=1.183, P=0.277; 6-month: χ²=1.697, P=0.193). The proximal contact loss rate on the mesial surface in control group (62.5%) was significantly higher than that in the experimental group (31.8%, χ²=4.330, P=0.037) at the end of the 1-year follow-up. However, no statistical difference was found on the distal surfaces between the two groups during the whole follow-up periods. The first open contact was noted 1 month after crown insertion.

CONCLUSION

By wearing vacuum-formed retainer for one year, the incidence of open contacts between the posterior implant prostheses and mesial adjacent teeth in the mandible has been reduced.

Expression of ram-5 in the structural cell is required for sensory ray morphogenesis in Caenorhabditis elegans male tail

Tissue morphogenesis requires complex cellular interaction and communication. The sensory ray in the Caenorhabditis elegans male tail has a simple cellular make-up and a non-essential function, thus providing an ideal model for studying the mechanisms guiding morphogenesis. We present here the analysis of a novel gene, ram-5, mutations of which are characterized by abnormal lumpy rays in the male tail. Microscopic analysis and behavioral studies revealed that lumpy rays contain operational sensory neurons. However, abnormalities were observed in the hypodermis and structural cells as well as in appositions between these two cell types. Molecular cloning and expression studies revealed that the ram-5 gene encodes a transmembrane protein localized in sensory ray support cells, the structural cells. Expression of ram-5 in these cells is required for normal ray morphogenesis. ram-5-dependent cell-cell communication is implicated in organizing the structural cell and the hypodermis, potentially through adhesion at the structural cell-hypodermal cell border.

[Enhancement of GAP-43 mRNA expression in the rat medial vestibular nucleus by labyrinthectomy]

Vestibular compensation is the most extensively investigated model for neuroplasticity. Growth-associated protein (GAP-43) mRNA plays a significant role in nerve regeneration and synaptic remodeling. Using in situ hybridization with DIG (digoxigenin)-labeled GAP-43 cDNA probe, changes of GAP-43 mRNA expression in the medial vestibular nucleus in the labyrinthectomized rats at 5, 12, 20 and 30th day after operation were investigated. The results clearly demonstrated that labyrinthectomy increased GAP-43 mRNA expression to different extents and amplitudes in bilateral medial vestibular nuclei. This finding suggests that upregulation of GAP-43 mRNA expression is related to regenerative sprouting, synaptic remodeling and neuroplasticity in vestibular compensation.

Cutaneous cryptococcosis

A fatal case of cutaneous cryptococcosis in a Chinese patient suffering from non-Hodgkin's lymphoma is reported.

Renal failure during intermittent rifampicin therapy

Two patients who developed reversible renal failure during intermittent rifampicin therapy are described. Both had febrile reactions to rifampicin. The first was also found to have uraemia associated with swelling of the glomerular endothelial cells. The second developed tubular necrosis unassociated with haemolysis or shock. The pathogenesis of the renal lesion in these two patients, as revealed by light microscopy, immunofluorescence studies and electron microscopy, is discussed.