[Photoelastic stress analysis of root dentin with different composite resin post and core systems and crowns].

Much research has been reported about post and core systems with composite resin, but the influence of the different types of prefabricated posts on the distribution of stress in the root has not yet been elucidated. It is necessary to clarify the influence of the relationship between core and crown materials to obtain combined restorations. The aim of this study is to analyze the influence of the combination of various post and core systems and different kinds of crown material on the stress distribution in the root. Six 2-dimensional photoelastic premolar models were designed. Three types of post and core systems (composite resin post and core, composite resin core with the fiber post, and composite resin core with a prefabricated stainless steel post) and two kinds of crown materials (metal and hybrid-type hard composite resin) were fabricated and cemented to each model. In these models, we applied a load of 200 N at an angle of 45 degrees to the tooth axis and analyzed the fringe order using a transmission polariscope. As a result, it has been clarified that the combination of the post and core and the crown plays an important role in preventing stress concentration within root Stress concentration can be prevented using a crown fabricated with a high-elastic modulus for the post and core with a high-elastic modulus, and a crown fabricated with a low-elastic modulus for the post and core with a low-elastic modulus.

[Benign intracranial hypertension resulting from corticosteroid withdrawal: case report].

We report a case of benign intracranial hypertension (BIH) resulting from corticosteroid withdrawal. A 36-year-old woman was admitted to hospital because of an intractable headache. A neurological examination on admission showed no abnormalities other than a headache and nausea. CT, MRI, and angiogram examinations showed no abnormalities. Hematological and laboratory data were also normal. Continuous monitoring of her cerebrospinal fluid (CSF) pressure showed a value of over 25 mmHg during sleep, but papilledema was not observed. A diagnosis of BIH was made, with corticosteroid withdrawal considered to be the most probable cause. The patient was given isosorbide solution for 3 months. However, her clinical condition continued to deteriorate; she eventually began to develop visual loss, photopsia, and memory disturbances. She underwent lumboperitoneal shunt surgery, which immediately eliminated the headache, photopsia, and memory disturbances. She regained her vision over a five-month period. BIH should be considered as a differential diagnosis when an intractable headache develops after corticosteroid withdrawal, especially in young women.