Effect of peri-implant mucosal thickness on esthetic outcomes and the efficacy of soft tissue augmentation procedures: Consensus report of group 2 of the SEPA/DGI/OF workshop

OBJECTIVES: The aim of this study was to comprehensively assess the literature in terms of the effect of peri‐implant mucosal thickness on esthetic outcomes and the efficacy of soft tissue augmentation procedures to increase the mucosal thickness with autogenous grafts or soft tissue substitutes. MATERIAL AND METHODS: Two systematic reviews (SR) were performed prior to the consensus meeting to assess the following questions. Review 1, focused question: In systemically healthy patients with an implant‐supported fixed prosthesis, what is the influence of thin as compared to thick peri‐implant mucosa on esthetic outcomes? Review 2, focused question 1: In systemically healthy humans with at least one dental implant (immediate or staged implant), what is the efficacy of connective tissue graft (CTG), as compared to absence of a soft tissue grafting procedure, in terms of gain in peri‐implant soft tissue thickness (STT) reported by randomized controlled clinical trials (RCTs) or controlled clinical trials (CCTs)? Review 2, focused question 2: In systemically healthy humans with at least one dental implant (immediate or staged implant), what is the efficacy of CTG, as compared to soft tissue substitutes, in terms of gain in peri‐implant STT reported by RCTs or CCTs? The outcomes of the two SRs, the consensus statements, the clinical implications, and the research recommendations were discussed and subsequently approved at the consensus meeting during the group and plenary sessions. CONCLUSIONS: There was a tendency of superior esthetic outcomes in the presence of a thick mucosa. The connective tissue graft remains the standard of care in terms of increasing mucosa thickness

An experimental and computational IR and hybrid DFT-D3 study of the conformations of L-lactic and acrylic acid: new insight to the dehydration mechanism of lactic acid to acrylic acid

We have studied with hybrid Density Functional Theory (DFT) with an aug-cc-pVTZ basis set and D3 dispersion corrections the intra-molecular hydrogen bond of L-lactic acid and L-lactic-acid analogs with the hydroxyl group on the alpha carbon atom substituted by α -XH (where X = S, Se, Te) as well as the conformations of acrylic acid. The results show there are three types of intramolecular hydrogen bonds that can form only when α-OH is present, whereas other less electronegative functional groups such as -SH, -SeH and -TeH do not exhibit the formation of an intramolecular H-bond. We show that the intra-molecular H-bond formed between the alpha-OH hydrogen and the COOH carbonyl oxygen would enhance the rate of the nucleophilic subsitution of alpha-OH to the K+ sites for the previously suggested dehydration mechanism of L-lactic to acrylic acids. We find that a temperature range between 190-210 °C would be optimum to maximise the rate of the nuleophilic substitution of the alpha-OH group onto the potassium sites during the dehydration mechanism of L-lactic acid to acrylic acid. Additionally, our hybrid-DFT simulation of the infrared spectrum of the various conformers shows that the lowest energy conformer can be identified by a single vibrational band at 3734 cm-1 whereas the other conformers this vibrational band is split with Δν that ranges between 6 cm-1 - 176 cm-1. We also find that the various conformers of acrylic acid can be identified by a double peak for the C=O and O-H vibrations which have Δν' of Δν'' 24 and 42 cm-1, respectively. This computational study is useful for spectroscopic experimental efforts that try to identify the various conformers of L-lactic acid and acrylic acid and to gain mechanistic insight into the dehydration mechanism over K substituted NaY Zeolites

Acylsilanes et Bis(acyl)silanes : nouvelles méthodologies de synthèse et nouvelles réactivités

Les acylsilanes sont les composés acyl-métal présentant la chimie la plus diversifiée. Cette thèse porte d'une part sur de nouvelles synthèses (méthodes et produits) d'acylsilanes, d'autre part sur l'étude de leur réactivité. Plus particulièrement, des allyl- et vinyl(acyl)silanes et des bis(acylsilanes) à silicium internes étaient ciblés. Une synthèse basée sur l'hydrolyse d'éthers d'énol ou d'ènethiol C-silylés s'est révélée peu performante pour des bis(acylsilanes), mais apporte une contribution originale à la panoplie des méthodes de synthèse d'acylsilanes. Deux méthodes ont été étudiées pour la synthèse d'allyl- et vinyl(acyl)silanes. Une séquence silylation/déthiocétalisation du 2-phényl-[1,3]-dithiane a permis de préparer les allyl- et vinyl(benzoyl)silanes, et la méthode à été étendue à d'autres allyl(acyl)silanes. Une séquence silylation/alkylation du 1-phénoxyméthyl-1H-benzotriazole a conduit efficacement aux allyl- et vinyl(acyl)silanes à longue chaîne alkyle. Les allyl- et vinyl(acyl)silanes se sont révélés peu réactifs en métathèse. Cependant la métathèse cyclisante appliquée aux dérivés bis(insaturés) du benzotriazole a donné des intermédiaires cycliques avec de très bons rendements. La métathèse croisée appliquée à un allylsilane dérivé du benzotriazole a permis d'obtenir, après hydrolyse, le bis(acylsilane) correspondant. Les allyl(diméthyl)(acyl)silanes présentent une réactivité photochimique inédite comparée à celle des acyl(trialkyl)silanes. Les allyl(acyl)silanes donnent, par réaction de Paternò-Büchi intramoléculaire totalement régiosélective, des 1-alkyl-2,2-diméthyl-6-oxa-2- sila-bicyclo[2.2.0]hexanes, un nouveau type de structure bicycliqueAcylsilanes are acyl-metal compounds having the most varied chemistry. This PhD concerns, on the one hand, new synthesis (methods and products) of acylsilanes, on the other hand the study of their reactivity. A method of synthesis based on the hydrolysis of C-silyl enol or enethiol ethers proved to be inappropriate for the preparation of bis(acylsilanes), but provided an original contribution to the array of the acylsilanes synthetic methods. The synthesis of allyl- and vinyl(acyl)silanes and allyl- and vinyl(aroyl)silanes was performed from two types of precusors. Allyl- and vinyl(benzoyl)silanes were prepared by a sequence of silylation/dithioketalisation of 2-phenyl-[1,3]-dithiane and the methodology was extended to aliphatic allyl(acyl)silanes. A sequence silylation/alkylation applied to 1-phenoxyméthyl-1Hbenzotriazole led to allyl- and vinyl(acyl)silanes bearing a long alkyl chain in satisfactory yields. Allyl- and vinyl(acyl)silanes proved to have a poor reactivity in metathesis whatever the Grubbs catalyst used. However ring closing metathesis applied to bis(unsaturated) benzotriazole derivatives led to cyclic intermediates in very good yields. Cross-metathesis applied to an allysilane derived from benzotriazole led, after deprotection, to the expected bis(acylsilane). Allyl(dimethyl)(acyl)silanes exhibited an unexpected reactivity compared with the usual reactivity of acyl(trialkyl)silanes. UV irradiation of allyl(acyl)silanes gave 1-alkyl-2,2-diméthyl-6-oxa-2-sila-bicyclo[2.2.0]hexanes, a new type of bicyclic structure, by a totally regioselective intramolecular Paternò-Büchi reactionREIMS-BU Sciences (514542101) / SudocSudocFranceF

Density functional theory study of lactic acid adsorption and dehydration reaction on monoclinic 011, , and zirconia surfaces

International audienc

Towards bis(acylsilanes) and cyclic unsaturated acylsilanes via metathesis: an exploratory study

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A theoretical study of H- and I-abstraction reactions from CH3I molecule by I (2P3/2) atom and IO radical

International audienc

A theoretical study of H- and I-abstraction reactions from CH3I molecule by I (2P3/2) atom and IO radical

International audienc