Helical bevel gears have inclined or twisted teeth on a conical surface and the common types are skew, spiral, zerol, hypoid gears. However, this study does not include Due to geometric complexities of gears, commonly used methods in their design based concept equivalent virtual spur gear. The approach paper is following assumptions, a) helix angle helical equal mean spiral angle, b) pitch diam...

AIMS The dural and arachnoid hole caused by lumbar puncture needles is a determining factor in triggering headaches. The aim of this study is to assess the dimensions and morphological features of the dura mater and arachnoids when they are punctured by a 22 gauge Quincke needle having its bevel either in the parallel or in the transverse position. METHODS Fifty punctures were made with 22 ga...

AIM A porcelain-fused-to-metal (PFM) veneer crown restoration is considered successful when biological, mechanical, and esthetical concerns are satisfied. Restorations with poor marginal integrity may contribute to the cause of severe caries and periodontal defects. The most important factor in achieving successful marginal integrity is preparation design. Although a sloping shoulder preparatio...

To evaluate stress distribution when applying vertical and tangential forces to 1mm thick occlusal veneers with different finish lines preparations, using the finite element method. One extracted third molar was prepared for veneers, firstly without any bevel. It scanned in order design two groups of lithium disilicate (G1A, G2A) composite resin (G1B, G2B) veneers. Then, preparation modified, b...

this investigation was performed according to the widespread application of base metal alloys and few articles published about the marginal integrity of restorations fabricated by these metals.three standard dies of a maxillary first premolar were prepared with a flat shoulder finish line in buccal aspect and chamfer in palatal. one of them left with no change. on the buccal aspect of the secon...

background and aims. anterior esthetic restoration is challenging in pediatric dentistry, due to limited durability and poor retention of the restoration.this study assessed the effect of air abrasion on tensile failure load of composite class iii restorations using different preparation techniques. materials and methods. 100 extracted human anterior primary teeth were divided, based on the pre...