Hans-Wolfram Lerner

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This lab study tested a new scan-gauge system against four conventional scan-body systems for digitally recording the positions of four implants across a full arch. The new Nexus IOS system was most accurate, while the Elos system showed the most variability. Calibrated scan gauges appear to improve consistency in full-arch digital implant impressions compared to standard scan bodies.

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Researchers compared six digital scanning methods for capturing the positions of six dental implants across a full arch, measuring how closely each matched a precision reference. Extraoral photogrammetry was most accurate (5 micrometers average error), while one intraoral scanner was nearly 45 times less accurate. Newer intraoral scanners are closing the gap with photogrammetry, but photogrammetry remains the gold standard for full-arch implant work.

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This review examines the emerging field of One Health ethics, which addresses moral questions arising when research simultaneously concerns human, animal, and ecosystem health. The literature so far has focused on a few core themes — including the ethical value of ecosystems and how to weigh competing interests — but the field remains underdeveloped. The authors argue that dedicated ethical decision models and broader scholarly engagement are needed to handle complex challenges like climate change and biodiversity loss.

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Researchers built boron-oxygen and boron-nitrogen doped ring systems — molecules valued in electronics — using gold or amine catalysts to guide the same starting material toward two different products. The boron-nitrogen version achieved an exceptionally high light-emission efficiency of 93%. Controlling which product forms without changing the starting material gives chemists a useful shortcut to two distinct families of luminescent compounds.

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A retrospective study of 103 patients followed for one year assessed a new type of healing cap that also serves as a coded scan reference for digital dental impressions. Restorations achieved high marginal fit (96.8%) and excellent tissue stability, with an overall success rate above 92%. The coded healing abutment simplifies the digital workflow by eliminating a separate scan-body step while also preparing the surrounding gum tissue for scanning.

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The first unprotected aluminum-containing fluorene-type molecules were synthesized and characterized, filling a gap left by decades of study on the better-known boron versions. These aluminum compounds dimerize on their own but can be split into monomers by adding donor molecules or converted into other derivatives by simple reagent exchange. They open a new avenue for aluminum-doped organic semiconductors and Lewis acid chemistry.

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Fruit fly smell receptors were found to excite each other through a previously unknown mechanism involving a receptor protein that normally causes inhibition. This self-excitation only kicks in when the neurons are firing rapidly, creating a nonlinear amplification that helps the brain distinguish between similar odors. Blocking this mechanism caused flies to confuse odors they could previously tell apart, confirming its role in smell discrimination.

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A family of double-boron ring compounds was designed so that each boron atom forms a weak, reversible bond to a nearby sulfur atom, which can break in response to heat, solvent changes, or light. When the sulfur bond breaks under light, the molecule switches from one emitting species to another, producing large apparent color shifts. These stimuli-responsive materials could be useful as sensors or switchable light emitters.

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A rigid, doubly electron-reduced boron compound was found to react with fluorinated benzenes through two distinct mechanisms depending on how many fluorine atoms the benzene carries. With fewer fluorines, it acts as a nucleophile attacking the ring directly; with more fluorines, it donates a single electron and then abstracts a hydrogen atom. Understanding this reactivity switch helps chemists design metal-free reagents for breaking strong carbon-fluorine bonds, which are notoriously difficult to cleave.

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Researchers synthesized two highly reactive silicon-boron compounds containing only halogen atoms, which can add boron and silicon simultaneously across a carbon-carbon double bond without needing a metal catalyst. Depending on the compound used, the addition occurred at either the 1,2 or the 1,1 position of the bond — two fundamentally different outcomes from the same type of reaction. This catalyst-free approach expands the toolkit for attaching useful functional groups to organic molecules.

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Scientists identified specific bacteria — Thermobifida species — as the microbes responsible for breaking down a new class of biodegradable plastics designed to mimic polyethylene during industrial composting. One bacterial enzyme, Tcur1278, was confirmed to actively degrade these plastics by releasing soluble breakdown products. This is the first evidence linking specific bacteria and a named enzyme to the degradation of this promising plastic alternative.

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A new class of biodegradable plastics was developed by combining amino acid polymers with calcium and iron ions instead of relying on petroleum-based chemistry. The materials can be reshaped with water, dissolved in mild acid and reformed, and were confirmed to biodegrade readily. These bio-based mineral plastics could replace conventional non-degradable plastics in applications requiring toughness and recyclability.

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Three manufacturing workflows for single dental crowns — chairside 3D printing, chairside milling, and lab-based milling — were compared for dimensional accuracy, fit quality, speed, and cost. Printed and lab-milled crowns were significantly more dimensionally accurate at the margin than chairside-milled crowns, yet all three produced clinically acceptable fits. Chairside 3D printing offered the best combination of accuracy, speed, and cost.

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A multicenter study assessed the accuracy of computer-guided dental implant surgery across three private practices using the same system, software, and protocol on 21 patients with 61 implants. Average angular deviation was 2.94 degrees and average shoulder deviation was 0.73 mm — results considered clinically acceptable. Standardizing every step of the digital workflow across different surgeons produced consistent accuracy.

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A detailed study examined how a halide ion trapped inside a silicon cage interacts with the surrounding silicon atoms, treating the system as a new type of Lewis acid-base pair called a confined Lewis pair. The strength of this interaction depends predictably on both the trapped ion and the outer substituents, and chlorine NMR provided a reliable experimental measure of it. Three new cage compounds were also synthesized to validate the theoretical predictions.

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Brain recordings from patients with PSP and CBD — two rare degenerative diseases involving tau protein — showed elevated alpha-wave activity compared to healthy people, but this increase was reversed in patients who also had Alzheimer's disease pathology. The pattern reflects which brain cells controlling wakefulness are preserved in PSP but lost in Alzheimer's. These electrophysiological signatures could help distinguish these overlapping diseases and inform targeted treatments.

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A nine-ring boron-nitrogen doped molecule was synthesized and found to meet the structural requirements for multiple-resonance thermally activated delayed fluorescence. It emits green light with 85% efficiency and a narrow emission band, properties sought for high-quality OLED displays. The synthesis demonstrates a practical route to air-stable large boron-nitrogen PAHs with OLED-relevant emission.

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Two mirror-image boron-nitrogen doped molecules — one electron-donating (NBN) and one electron-accepting (BNB) — were prepared and their light emission was shown to depend on which excited state is accessed, controlled by solvent polarity and molecular geometry. When the two molecules are mixed, they form a new complex that emits at a different color due to charge transfer between them. This framework provides a systematic way to tune emission across a range of colors.

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Two large ring molecules containing alternating boron-nitrogen or boron-oxygen units were built from smaller aromatic fragments and shown to switch their aromatic character when electrons are added or removed. The nitrogen-containing ring also acts as a Lewis acid capable of binding up to four donor molecules, and the assembly process unexpectedly generated a nanoscale cage compound. These molecules demonstrate how electron injection can toggle aromaticity in large-ring systems.

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Two complementary ring molecules were synthesized — one electron-rich (NBN-phenalenyl) and one electron-poor (BNB-phenalenyl) — that have almost identical structures but opposite electronic properties. Mixed together, the two molecules form a complex that emits at a longer wavelength than either alone, due to charge transfer between them. This pairing strategy offers a simple route to tunable emitters for organic electronics.

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An in vitro study compared dental implant placement accuracy using mixed reality navigation, conventional surgical guides, and freehand technique across 135 model surgeries. Mixed reality navigation was more accurate than freehand for all measured deviations and outperformed surgical guides in depth and angle control. These results position mixed reality navigation as a promising complement or alternative to static guided surgery.

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Heating a boron-nitrogen precursor with boron tribromide triggered a cascade of chemical rearrangements that produced a large, helically twisted molecule with a specific pattern of boron and nitrogen atoms. This arrangement creates an efficient blue-green light emitter (84% quantum yield) that also shows thermally activated delayed fluorescence, a property useful for energy-efficient OLEDs. The reaction sequence unexpectedly builds complexity in a single step.

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Eighty-five patients received implant-supported crowns and bridges made from a hybrid composite material using a 3D-printing method called tilting stereolithography, and were followed for one year. All restorations survived the year, with a 95.8% success rate and only minor complications. The results support this fully digital, 3D-printed approach as a viable option for definitive single and short-span implant restorations.

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A new protocol was tested that combines AI-based 3D model processing with mixed reality holographic visualization to plan and guide dental implant surgery. The AI automatically aligns patient scans, which the surgeon then views as holograms to plan implant positions, and a 3D-printed surgical guide executes the plan. Initial results showed clinically acceptable implant placement accuracy, suggesting AI and mixed reality could replace conventional planning software for straightforward cases.

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A cycloaddition reaction was used to install two trichlorosilyl groups side-by-side on a benzene ring, giving a versatile starting material for making organosilicon compounds. The number of reactive chlorine groups could then be selectively reduced from six to four or two by adding specific molecules that bridge or chelate the silicon atoms. This controlled approach to partially functionalized silicon compounds is valuable for building specialty silicone materials.

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Three intraoral scanners were compared for accuracy in capturing six implant positions across a full arch, and the effect of adjusting the implant library file size was also tested. The scanners produced significantly different accuracy levels, but correcting for scan-body mesh size did not improve results when purely cylindrical scan bodies were used. Scanner choice matters more than library correction for achieving accurate full-arch implant scans.

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The first aluminum double-ring compounds analogous to well-known boron compounds were synthesized and shown to act as Lewis acids that can bind two donor molecules simultaneously. These compounds dimerize spontaneously but react cleanly with bases to form defined adducts or cage-like structures. As cooperative Lewis acids, they could find use in catalysis and small-molecule activation.

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A bacterial consortium from the gut was found to break down a plant sugar called sulfoquinovose through a newly described two-branch pathway, producing sulfur-containing compounds that a second bacterial partner then converts to hydrogen sulfide. The key organism responsible for the first steps belongs to the Lachnospiraceae family, and a separate species was shown to carry out a similar bifurcated pathway on its own. This expands understanding of how gut bacteria process dietary sulfur, a process relevant to gut health and certain diseases.

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A panel discussion at an international sustainability conference examined where ethics fits within One Health research, which addresses health across humans, animals, and ecosystems. Four priorities emerged: using ethics to tackle complex, hard-to-solve problems; accounting for multi-disciplinary tensions; addressing risk and resilience; and developing practical ethical decision models. The participants concluded that ethics must become a core component of One Health work rather than an afterthought.

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A boron-silicon compound containing a bridging hydrogen atom was synthesized and found to react differently depending on the solvent and reagent used — either forming a stable donor-stabilized adduct or undergoing a hydrogen migration to give a silicon chloride derivative. In the latter case, further reaction with a carbene produced a silicon species that formally has only two bonds, a rare compound class. The reactivity map laid out here guides the synthesis of reactive silicon intermediates.

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A helical molecule incorporating two boron-oxygen units into a sulfur-containing seven-ring system was synthesized and separated into its two mirror-image forms, which are stable at room temperature. The compound emits blue light with 6% efficiency and has a lower barrier to racemization than the all-carbon parent helicene. Boron-oxygen doping provides a handle for tuning both the optical properties and the conformational stability of helicene-type emitters.

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A ten-atom ring containing both silicon and germanium atoms was synthesized in a single step and isolated cleanly, along with methods to release it from its protective chloride complex. The synthesis used germanium and silicon chloride starting materials directly, with no multistep protection chemistry. Access to this mixed ring compound opens new possibilities for group-IV heterocycle chemistry.

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Mixed-element cage molecules containing both silicon and either germanium or tin were synthesized, and selective chemical modification of the silicon sites was achieved while leaving the germanium sites intact. Two structural isomers formed in the silicon-tin case but not with silicon-germanium. Site-selective functionalization of these mixed group-IV cages is a step toward semiconductors with precisely controlled composition.

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A doubly reduced boron compound was found to activate boron-hydrogen bonds at room temperature and then catalyze the addition of borane reagents across a range of unsaturated molecules including imines, ketones, alkenes, and isocyanates. The catalyst operates through two different mechanisms depending on the size of the substrate. This versatile metal-free catalyst expands the toolkit for adding boron groups to organic molecules without transition metals.

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A proof-of-concept study combined AI-automated segmentation of CT scans with augmented reality holographic visualization to plan dental implant placement in three dimensions without conventional planning software. The protocol was applied to partially edentulous patients and produced clinically acceptable implant positions. The combination of AI and augmented reality could replace traditional implant planning tools in straightforward cases.

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Brain recordings from 88 Alzheimer's patients and 88 matched healthy controls were analyzed using a mathematical model to identify which neural circuit parameters differed most. The strongest distinguishing feature was an elevated time constant governing how long-range brain connections excite local neurons, and this parameter also correlated with worse cognitive performance. A single measurable circuit property thus captures both the spatial and cognitive abnormalities of Alzheimer's disease.

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The crystal structure of a Grignard reagent complex was determined, revealing an open-cube arrangement of four magnesium atoms bridged by chloride ions. Two of the magnesium atoms are four-coordinate and two are six-coordinate, with different bond lengths reflecting these coordination differences. The structure adds to the small number of characterized Grignard cluster compounds in the literature.

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Two boron-containing molecules related to fluorene were found to add across carbon-carbon double and triple bonds spontaneously, without any metal catalyst, by using their high Lewis acidity and low steric bulk to coordinate and activate the substrate. The reactions worked on ethylene, a challenging non-activated substrate, and could be extended to other alkenes and alkynes. Removing the need for a metal catalyst simplifies the synthesis of boron-functionalized organic molecules.

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A large silicon cage with a chloride ion trapped inside was selectively modified at different surface positions by controlling solvent and reagent conditions, replacing chlorine atoms with hydrogen or methyl groups in predictable patterns. The fully hydrogenated cage became the largest structurally confirmed hydridosilane on record. These regioselective reactions provide a roadmap for building silicon cage compounds with defined surface chemistry for semiconductor applications.

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When people with Alzheimer's disease speak, their brains show a reduced ability to suppress the sound of their own voice compared to healthy controls — a deficit measured by brain imaging. This suppression normally reflects the brain accurately predicting the sensory result of speaking; its reduction in Alzheimer's indicates that the predictive machinery for speech is impaired. The finding links the well-known memory and cognitive decline in Alzheimer's to a specific breakdown in how the brain models its own actions.

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New double-boron cage molecules called diboratatriptycenes were made by trapping a reactive boron species with benzyne and were shown to undergo controlled reactions at their bridgehead positions. Shining UV light on one of these compounds triggered a rearrangement that converted it into a boron-doped polycyclic compound not easily made any other way. This photochemical route provides access to a poorly explored family of boron-containing aromatics.

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Starting from a silicon cage compound with a chloride ion trapped inside, researchers replaced hydrogen atoms on the surface with bromine atoms to varying degrees, achieving either partial or complete bromination. Partial bromination under mild conditions was regioselective, touching only specific sites on the cage. Controlled surface functionalization of these silicon clusters opens routes to tailored cage derivatives for materials applications.

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Boron-doped acene compounds were equipped with four vinyl groups using a palladium-catalyzed coupling reaction, producing two new fluorescent molecules that emit green or blue light. The process required developing new halogenated starting materials as intermediates. These tetravinyl-substituted compounds expand the range of boron-doped acenes available for organic electronics.

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A retrospective multicenter study evaluated 37 full-arch implant restorations in 29 completely edentulous patients made using a direct intraoral scanning system over three years. All restorations were clinically acceptable at delivery, all implants survived one year, and complications were minimal. These results support the feasibility of a fully digital, model-free workflow for full-arch implant-supported prostheses.

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A boron-nitrogen molecule built around a heptacene framework was synthesized and found to be an unusually strong electron acceptor, with a low-lying electron-accepting orbital at -3.9 eV. It can be reversibly switched between multiple oxidation states and forms a stable radical anion, and exhibits deep blue and purple colors through charge transfer. This compound advances the design of organic semiconductors that can both donate and accept electrons.

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Custom-shaped synthetic bone graft blocks, designed by computer and machined from a calcium phosphate ceramic, were used to rebuild deficient jaw bone in 26 patients before dental implant placement, with three years of follow-up. Average bone gain was about 2-3 mm vertically and horizontally, all implants survived three years, and the crown success rate was 92%. CAD/CAM-fabricated synthetic bone grafts offer a predictable, off-the-shelf alternative to harvested bone for small jaw defects.

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New silicon-germanium precursor molecules with pre-formed silicon-germanium bonds were synthesized and used to deposit silicon-germanium alloy thin films by chemical vapor deposition. Adjusting the molecular structure controlled how much carbon ended up in the deposited material. Partial crystallization was also achieved, demonstrating that these precursors can produce crystalline group-IV alloy films relevant to semiconductor manufacturing.

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A multicenter study evaluated a guided implant surgery system that uses no metal sleeve or key mechanism in 60 patients receiving 124 implants, with one year of follow-up. Implant survival was 100% and overall prosthetic success was 88.7%, with low rates of biological and mechanical complications. The sleeveless, keyless guide design performed reliably across centers, offering a simpler surgical option.

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A randomized controlled trial protocol was designed to test whether a mindfulness program tailored specifically to dementia caregivers can improve their psychological and relational wellbeing. Participants will be assessed at three time points over three months using questionnaires, task-based measures, and qualitative interviews. The study aims to generate evidence for a structured caregiver support intervention as demand for dementia care grows.