الفهرس 
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Abstract
It takes a lot of work to make the fake repair look like the real thing.
The aesthetic qualities, biocompatibility, minimal plaque surface adherence, high flexural strength, and lack of mucosal discoloration of zirconia and its alloys are contributing to its rising popularity.
To better understand how artificially induced ageing, either mechanical or chemical, affects the translucency and surface roughness of two types of translucent zirconia, namely Super translucent zirconia and Ultra translucent zirconia, in comparison to traditional Y TZP and IPS e.max, this study was carried out.
Eighty disc shaped specimens (=12mm, thickness=1.2 0.2mm) were constructed for the experiment.
Finally, a high speed diamond saw was used to separate discs from their respective pre sintered cylinders (Isomet 4000 precision cut, Buehler, USA).
It was spinning at 2500 rpm while being cooled by a system.
Twenty samples were divided into four categories according to the ceramic material they were made from.
Katana STML(S)group and Katana UTML(U)group multi layered ceramics, on the other hand, have a much smaller sample size (n=20).
IPS e.max CAD HT (E) and BruxZir Full Strength Shaded (Z) group.
The deterioration process, whether mechanical or chemical, was used to categorise the groupings into one of eight distinct categories.
Acetic acid at 4% (at 80 degrees Celsius for 16 hours) promoted chemical ageing.
Hydrolytic resistance of dental ceramics is measured against ISO 6872.
The ROBOTA chewing simulator, with its four separate chambers imitating different thermodynamic conditions, was used to mechanically age the specimens.
The bottom sample container contained the dental samples that were embedded in Teflon.
The average force exerted during a single chewing cycle is 49 N, hence a force of 5 kg was used to represent the typical range of 49 N to 150 N during normal chewing.
The clinically relevant chewing condition of 1 month was mimicked by repeating the test 12,500 times.
Specimens from each class were evaluated for translucency using a reflecting spectrophotometer (Model RM200QC, X Rite, Neu Isenburg, Germany), and then their surface roughness was measured using an optical prolifometer.
The information was then entered into a database and subjected to statistical analysis.
The results showed that, prior to age, E.max had the greatest translucency value, whereas Bruxzir had the lowest.
The surface roughness of Emax was the greatest, whereas there was no noticeable difference between Bruxzir, ST, and UT before age.
When subjected to mechanical ageing, the transparency of Bruxzir, ST, and UT all improved, whereas Emax’s transparency decreased.
Chemical ageing altered the degree to which certain materials translucence.
Chemically aged Bruxzir became more translucent, whereas E. max, ST, and UT became less so.
Both mechanical and chemical ageing caused a reduction in E max’s transparency, although the chemical ageing resulted in a greater loss of transparency than the mechanical ageing.
As a result, the decline in translucency of Emax is thought to be caused more by mechanical ageing than by chemical ageing.
Compared to chemical ageing, mechanical ageing reduced the translucency of ST and UT, but chemical ageing enhanced it.
Both mechanical and chemical ageing resulted in a rise in Bruxzir’s transparency, with no discernible difference between the two.
Mechanical and chemical ageing each reduced the surface roughness of the four materials (Bruxzir, ST, UT, and Emax).
In all four cases, chemical ageing resulted in a rougher surface than mechanical ageing had.
Therefore, it is believed that mechanical ageing is more effective than chemical ageing in smoothing out surfaces.
Conclusion
Katana STML and UTML both evolved as a result of chemical and mechanical ageing.
in terms of both transparency and surface roughness, it is inferior to emax and superior to BruxZir.