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Visual Chart V Crack _TOP_ Pull

Microscopes permit accurate visual estimation of the steepness of cuspal inclines, and allow precise observation of where a pointy lingual plunger cusp occludes into an opposing tooth, and observation if a microscopic crack line is developing around this contact area. Microscopic amounts of chalky white or beige discoloration underneath a cusp can be indicative of caries under the cusp, which sometimes can be overlying a fracture plane. Microscopes facilitate observing microscopic gaps or elevations of restoration margins, which may indicate cracks. Microscopes improve the ability to understand the dimensions of foreshortened surfaces. This facilitates observing a marginal ridge crack from an occlusal viewing vantage point, to assess how closely to the gingiva the crack has propagated.

visual chart v crack pull

But instead of memorizing all spoke tension readings, you can make use of so called radar chart or a wheel building chart. It is a visual representation of spoke tension readings on circle shaped (radar) diagram across the wheel, for both sides shown separately.

Many metals used in code fabrication are very sensitive to rapid quenching including many of the basic P-No. l metals. Very hard, brittle, crack sensitive micro structures, such as martinsite and upper bainite, are formed in many metals when rapidly quenched from an elevated temperature. The brittle micro structures are likely to crack during the solidification of the weld metal or when highly stressed during operation of the pressure vessel. The cracks are usually an underbead crack not detectable by visual or dye penetrant examination and difficult to detect by radiographic or magnetic particle examination. Yet these small cracks may lead to the product failure, if not at hydro test, at some future time due to cyclic fatigue of the pressure vessel. There are many preventive measures to circumvent this problem such as preheat, high heat input processes, subsequent Post Weld Heat Treated (PWHT), etc.

A high heat input process may be selected for the welding, but the tack is applied by the shielded metal arc welding process. The tack is a very rapid quench application and a brittle, crack sensitive micro structure results usually at the root of the weld. The tack may be subsequently pulled and stressed during the fitup operation with a resultant underbead crack in the pressure retaining material at the root of the weld. Subsequent weld passes with the high heat input process do not, generally, remove the cracks. In fact, the cracks may propagate further into the base metal and/or weld metal during the subsequent welding operations.

Other incidents that can crack or chip a tooth are not as easily identified. Grinding teeth at night, called bruxism, can create fractures in teeth. Having a very large filling can affect the structure of a tooth and make it weak and brittle and possibly snap off. Old fillings and restorations can cause cracking as they start to pull away from the tooth and come loose. Aging, in general, can make teeth more fragile and easy to break.

Split Tooth. If a crack is deep enough, it could break the tooth into two pieces, resulting in a split tooth. A tooth can split immediately with a strong impact or may happen if a cracked tooth is left untreated. This is a dental emergency, and, unfortunately, the dentist will most likely have to pull the tooth.


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