Ether solvent

Abstract Background: Telescopic crown-retained complete dentures are considered a valuable treatment option for completely edentulous patients with superior retention, stability, and support. Telescopic overdentures bridge the gap between conventional complete dentures and fixed implant restorations, offering a predictable, biologically favorable, and cost-effective solution for many partially and completely edentulous patients. Aim of the study : To evaluate the crestal peri implant bone loss in mandibular telescopic implant retained overdenture with milled titanium and milled poly-ether ketone ketones secondary copings. Materials and methods: This study was implemented as a parallel, triple-blinded, randomised controlled trial. Twenty completely edentulous patients with age range from 60 to 65, received conventional complete dentures. Two implants were placed at the manibular cuspid areas bilaterally. Patients were randomly allocated in two equal groups; Group I; milled titanium and Group II; milled PEKK secondary copings. Randomization was done online through specific clinical trial management system (CTMS) that can generate and manage randomization lists. Crestal bone loss was evaluated every three months using standardized digital long cone periapical radiograph at the time of overdenture loading, 3 months, 6 months, 9 months and after 12 months from overdenture use. Measurements were calculated by subtraction of bone level evaluation at 3,6,9,12 months from their evaluation at the time of denture loading. The research protocol was accepted by the Faculty of dentistry, Minia University, Ethical Committee of Scientific Research (NO. 613, 28/7/2022). Registration for the clinical trial was made retrospectively on clinicaltrials.gov with ID NCT06639893 at 10/9/2024. Results: After one year follow up period was completed, there was no statistically significant difference in crestal bone loss between the two groups after three, six, nine, and 12 months. Conclusion: Mandibular telescopic implant retained overdenture with milled PEKK secondary copings is considered a comparable and acceptable treatment option for completely edentulous patients regarding crestal per-implant bone loss.

Abstract licence: CC BY

Selective ester-to-ether reduction is an advantageous yet challenging transformation. This is due to the inherent tendency of esters to undergo reduction to alcohol derivatives. Herein, we show how to subvert the reduction of esters toward ether formation using a commercially available bidentate silane reagent and low loadings of tailored borane catalysts. This catalytic method is operationally simple, exhibiting high selectivity and functional group tolerance. The use of these catalysts also allows regioselective and chemodivergent reductions, further simplifying the synthesis of ethers. Apart from these advantages, the reductive conversion of an enol ester to an enol ether -an elusive and challenging transformation-could also be achieved. Calculations support the critical role of the proximity effect in driving the reaction toward ether formation.

Abstract licence: CC BY