[Comparison of the effect of different locations of occlusal contact on the porcelain fracture in base metal-ceramic crown]

Introduction: the base metal ceramic restorations are one of the most popular restorations in the world. No research has been done about the porcelain metal junction on the occlusal surface yet. The main purpose of this study was to find the best location for porcelain metal junction with regard to occlusal contact in base metal- ceramic crown

Materials and Methods: 75 Porcelain Fused to Metal [P.F.M] crowns were made for metal dies. C were cemented on the respective die with zinc phosphate cement and were divided into three groups of 25 samples. Occlusal contact in each group was as follows: First group [A]: On the porcelain metal junction. Second group [B]: 2mm away from the porcelain metal junction on the Data were analyzed with one way ANOVA and Duncan tests

Results: 1] The average force was different in each of the 3 groups significantly. 2] Group B had the lowest amount of force [290kgF] and group C had the greatest amount [7 13kgF]. 3] Group A developed a force between Band C [529kgF]

Conclusions: 1- The best location for occlusal contact in the porcelain metal junction restorations is on the metal. 2- When the occlusal contact is on the porcelain metal junction, It needs more force for porcelain fracture than when it is on the porcelain

[ effect of helicobacter pylori on oral mucous in rats]

Background: helicobacter pylori is one of the most prevalent infectious disease in the world. It causes gastric ulcers and stomach cancer, and normal microbial flora of oral cavity

Objective: this study was conducted to determine the pathogenic effect of helicobacter pylori on mucous in rats

Methods: 40 rats randomly were divided into 4 groups as followed: Control 1: The lips, cheeks, tongue and palate of rats were conducted with swab contained physiologic serum. Case 1: The lips, cheeks, tongue and palate of rats were conducted with swab contained helicobacter pylori. Control 2: Incised cheek were conducted with swab contained physiologic serum. Then cheek was sutured. Case2: Incised cheeks were conducted with swab contained helicobacter pylori. Then cheek was sutured. After 15 days specimens were collected from lips, cheeks, tongue and palate. The slides were provided using H and E and Gimsa stain

Findings: there was neither helicobacter pylori nor pathogenic change of mucous comparing case 1 and case 2 with control 1 and control 2 respectively

Conclusion: helicobacter pylori is unable to produce either colony or pathogenic change on oral mucous in rats