الفهرس 
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Abstract
This study aimed to determine if there was a correlation between the type of finish line used in the fabrication of all ceramic CAD/CAM restorations and the rate of microbial colonisation in these restorations, as well as the effect that finish line preparation had on marginal gap and internal adaptation (in vitro).
(in vivo research).
For this in vitro investigation, two complete human premolars were prepared in the same way, with the exception of a (1.00 mm) on one of the margins.
Forty premolar tooth epoxy replicas were made for sample standardisation
Samples were divided into two groups based on whether or not their final edges had a deep chamfer (DC group, n = 20) or a knife edge (KE group, n = 20).
According to the kind of construction material used, we split each set into two subsets of 10 samples each.
Ceramic lithium disilicate (n=10) is in subgroup 1, whereas lithium silicate reinforced with zirconia (n=10) is in subgroup 2.
All dental caps were manufactured using computer aided design and computer aided manufacturing technology.
After being attached to a tooth, each sample was aged by thermal cycling to simulate the passage of time.
The stereomicroscope was used to evaluate marginal gap and internal adaption.
Ten individuals were chosen for this in vivo research in order to assess the gingival index and quantitatively analyse microbial colonisation in the gingival sulci in relation to the two distinct all ceramic crown margin designs used in this investigation.
After the mouths were properly prepped, one set of samples was given a deep chamfer, while the other set was given a knife edge finish.
Controls were provided by the estimated values of gingival index and microbial colonisation.
After cementation, patients were followed up with weekly, monthly, and bimonthly to have subgingival microbial samples cultured and measure the extent of microbial colonisation and gingival inflammation.
The following are the results of the data collection, tabulation, and statistical analysis:
A different option to the conventional horizontal arrangement of finish lines was provided by placing them vertically.
Since the tooth structure is preserved during the vertical preparation for permanent abutments, this method is preferable to the more invasive horizontal one.
Margin adaptation of restorations was not substantially impacted by any of the preparation schemes utilised in this investigation, and all designs provided satisfactory results.
The deep chamfer finish line layout resulted in the thinnest cement thickness (internal adaptation) results.
Fifth, comparing E max with Celtra Due, there was no discernible change.
Total bacterial count in deep chamfer method varied significantly over time, with a rise at 1 week and an even larger increase at 1 month, followed by a considerable decline at 2 months that did not bring the count back to pre operative levels.
More clinical and biological research is required to properly confirm these suggestions.
We will conduct a prospective study to see if clinicians can use the vertical tooth preparation procedure with predictable results, in addition to in vitro and in vivo studies to evaluate the clinical performance (Marginal and internal Adaptation) of newly developed CAD/CAM materials like Celtra Duo.