الفهرس 
1.History of posts
Fabrication Techniques of custom-made postsOnly 14 pages are availabe for public view
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Abstract
This in-vitro study was conducted to compare the adaptation of the
glass fiber posts fabricated by the chairside versus in lab CAD/CAM
technology. A freshly extracted human maxillary central incisor was
included in the study as a model for specimen replicas. The tooth was
cleaned of debris and calculus using a periodontal scaler and stored in
distilled water with 0.1% thymol disinfectant at room temperature.
The crown of the selected tooth was sectioned perpendicular to the
long axis 2 ± 1 mm coronal to the cementoenamel junction using a lowspeed diamond disc, in order to achieve a standardized length of 14 mm. Root canals were prepared by a crown-down technique. Obturated with
gutta-percha cones and resin sealer (ADSEAL) using the lateral
condensation technique.
The gutta-percha was removed with Peso reamers, leaving 5 mm of the
gutta-percha intact at the apical third of the root and creating a standard post space length of 9 mm. Final post space preparation was made with EXACTO bur #3 to gain adequate length and diameter for the post. The root canal was enlarged with a diamond stone (no.4137, MICRODONT) in a low-speed handpiece limited to a 9-mm vertical length to obtain a simulated wide flared canal with approximately a 1.5 mm width of the coronal root dentin wall. A fan CT scanner was used to scan the prepared root and generate
three-dimensional (3D) images of the root, including the prepared post space. STL file was created from the DICOM file of the prepared root and imported in exocad DentalCAD software to make a small notch in the coronal portion of the root canal to serve as an anti-rotational element. The STL file was used by a 3D dental printer (Dent2) to generate thirty standard and identically prepared resin root models. Prepared resin root models were randomly distributed into three groups (n=10 per group) according to the impression technique:
ALS: Acrylic pattern lab scanning group. VLS: vinyl polysiloxane lab scanning group. CS: Chair-side scanning group. STL files of the scanned patterns of all previous groups were opened in
exocad DentalCAD software for designing the post and core restorations. The cores were made 2 mm in height and had flat occlusal tables with a central sectioning orientation groove extending labio-palatally to a depth of
0.5 mm. A fiber-reinforced composite disc (Trilor) was milled using 5-Axis
milling machine (ARUM 5X-400) to fabricate 30 glass fiber post and core
restorations. Prepared resin root models were embedded in methacrylate resin molds. Self-etch, self-adhesive dual-cure resin cement (TheraCem®) was
used for post and core cementation. Models were sectioned longitudinally to their long axis after cementation of the posts, guided by the post sectioning orientation groove. The sectioned models were examined with a scanning electron microscope (SEM). The gap width was measured at three locating marks from the post-core interface toward the apex in coronal, middle, and apical areas. Data were collected, tabulated and statistically analyzed using one-way analysis of variance (ANOVA) to find the interaction between the different variables.