The assembly of molecular Borromean Rings from constitutionally independent rings in a stepwise manner depends on the preparation of robust “ring-in-ring” complexes. The π-electron rich macrocycle bis-1,5-dinaphtho[50]crown-14 (1) is shown to form a donor-acceptor ring-in-ring complex with the π-electron poor cyclophane cyclobis(paraquat-4,4'-biphenylene) (24+) in solution. In the crystal super...

introduction: the purpose of this study was to evaluate external root surface temperature rise during post space preparation using la axxess bur, beefill pack system, and peeso reamer drill. materials & methods: the distal canals of forty-five extracted human permanent mandibular first molars were instrumented in crown-apical manner and obturated with lateral condensation technique. teeth were ...

The ultimate goal for an esthetic rehabilitation is the restoration of health, beauty, and function to the patient. This article illustrates a predictable system to guide the clinician with tooth preparations for porcelain veneer restorations based upon the additive diagnostic wax-up. This system promotes a preparation technique using a series of guides that direct the clinician to reduce only ...

It is difficult to visualize the lingual surfaces of the all tooth, in order to assess the exact Facial axis of the clinical crown (FACC point) . So no matter how accurately brackets are positioned on set-up models, it would be meaningless if these positions were lost during intraoral bracket placement. It is no exaggeration to say that incorrect bracket positioning leads to treatment failure. ...

The effectiveness of Architect, SE growth regulator (mepiquat chloride, 150 g/l + pyraclostrobin, 100 prohexadione-calcium, 25 g/l) in winter rapeseed var. Vitovt and Mazari Mercedes hybrids is shown. application the preparation phase 4–5 leaves at rate 1,5 l/ha reduces height growing point by 47,7–55,2 %, increases diameter root crown on average 13,5–22,8 crop overwinter survival 3,7–12,3 % oi...

An efficient procedure for preparing enantiopure polycyclic ethers is reported. The protocol is based on the photo-oxidation/conjugate addition sequence over a chiral functionalized furan, which was prepared from commercially available tri-O-acetyl-D-glucal. The Michael addition step afforded two products with the same absolute configuration from a mixture of diastereomers.

This paper shows the clinical steps for preparing a screw-retained crown for the restoration of a single implant. Impression-taking using open-tray technique and delivery of the crown is presented in a step-by-step manner elucidated by detailed photographs. Furthermore, the advantages and disadvantages of screw-retained crowns are discussed in comparison with the cemented restorations.

This research develops an innovative free-form surface scanning system using laser triangulation for 3D dental data required for crown reconstruction. This novel design employs double laser diodes to produce two 45° structured-light lines projecting onto the plaster tooth models and three CCD cameras to capture deformed fringes to achieve fast and accurate 3D surface measurement of plaster toot...

The use of bi-layered all-ceramic crowns has continuously grown since the introduction of computer-aided design/computer-aided manufacturing (CAD/CAM) zirconia cores. Unfortunately, despite the outstanding mechanical properties of zirconia, problems related to porcelain cracking or chipping remain. One of the reasons for this is that ceramic copings are usually milled to uniform thicknesses of ...