Optimization of materials for a user-formed mouthguard
A mouthguard that can be custom formed by the user at the time of need to achieve optimum fit and protection is required for sports and clinical applications. This study has evaluated two silicone-based polymer systems found sufficiently workable to be molded to the user's mouth. Compositions were optimized for setting time and mechanical properties by varying the proportions of catalyst, cross-linking agent, and filler. Mechanical tests showed the optimized silicones to have lower tensile and tear strengths and higher penetration and rebound than most present mouthguard materials. Detailed measurements of compressive stress-strain, coupled with a stress analysis of conditions in actual mouthguard use, indicate that the optimized silicone polymers possess more than adequate strength and durability for a user-formed mouthguard.
Maximum opening and closing forces exerted by diverse skeletal types.
OZET Toplam 44 olan iskeletsel hypodivergent ve hyperdiverg&nt kisilerde maksimum isirma gucunu bulmak icin gnathadinametreden ve maksimum agiz acma kuvvetini tespit etmek icin de ozel bir aygittan yararlanildi. Elde edilen sonuclar, elektronik beyinle cozumlendi. Bu suretle cinsiyet goz onune alinmadan agiz acma gucunde, sag ve sol isirma guclerinin ortalamasi ve standard deviasyonlari saptandi. Ayni islem cinsiyet dikkate alinarak tekrarlandi. Bundan sonra bahsedilen bu degiskenler arasinda bir farkm bulunup bulunmadigini saptamak icin de manalilik testi «test of significance«  uygulandi. Son olarak yas ve olculen degerler arasinda bir iliskinin bulunup bulunmadigi «dogrusal korelasyon» analizi ile tespit edildi. Arastirmada elde edilen sonuclar: 1 â€” Her iki iskeletsel tipte maksimum sag ve sol isirma gucu arasinda bir fark yoktur. 2 â€” Her iki iskeletsel grupta maksimum agiz acma ve kapama kuvvetleri arasinda pozitif bir oranti vardir. 3 â€” skeletsel divergent tipli kisilerin agiz acma ve kapama gucleri arasinda belirli farklar mevcuttur. 4 â€” Erkekler, kadinlara nazaran, agiz acma ve kapamada 0,05 <P <0,10 sinirlari icinde [Borderline significance) bir fark gostermektedirler. Summary and Conclusions An appliance was constructed to measure the maximum opening force, whereas, a gnathodynamometier was utilized to record maximum closing force of 44 subjects. The collected data was analyzed by computer regardless of sex, to determine both the mean and the standard deviation of the opening forces, and the average right and left side closing forces. The data was also computed for the above mentioned variables to find out the mean and the standard deviation for both sexes. The student's t test was utilized to determine if there were any significant differences in the before mentioned variables. A linear correlation analysis was made using data of age and measured forces to see if a relationship existed. The following conclusions were obtained from this investigation. 1) Right side and left side for each skeletal type did not show any important difference. 2) Each skeletal type exhibited significant positive correlation between maximum opening and closing forces. 3) Skeletal open and closed bite subjects did present significant diffrences in measuring the maximum opening and closing forces. 4) Maximum biting and opening forces tend to greater in males than females, but the results ware only of bordeline significance.
Hinge axis registration: Experiments on the articulator
Abstract Registrations of the hinge opening axis were carried out with the aid of a kinematic face-bow mounted on a modified Hanau articulator. Three experimental series were carried out, both with 10 degree and with 15 degree openings, with the following results. The axis of the hinge movement as carried out on the articulator could not be recorded without error at the above degrees of opening. The ranges of variation correspond to areas with diameters of 1.0 to 1.5 mm., slightly less with 15 degrees than with 10 degrees of opening. On the whole, the findings corroborate those obtained by Kurth and Feinstein.