Effectiveness in Prosthodontics with Mechanically Strong, Paltform Switched Implant Systems

Presudno obilježje današnjeg dvodijelnog implantacijskog sustava je mehanički čvrsta, pouzdana površina usatka koja će biti u dodiru s kosti. Tom se zahtjevu može na optimalan način udovoljiti precizno izrađenim spojem s nosačem konusnog oblika (Morseov konus). Taj je spoj s nosačem konusnog oblika vrlo otporan na savijanje i torziju pri obavljanju kliničke funkcije, čime se znatno smanjuje mogućnost kidanja vijaka ili njihova labavljenja. Uz to, spoj s nosačem konusnog oblika omogućava i izradu oblika platforme na koronalnom dijelu usatka. Time se omogućava stvaranje debelog sloja gustog, mekog tkiva oko vrata nosača i prekrivanje preostalog, horizontalnog dijela platforme. Tim se debelim slojem tkiva prikriva boja titana na cervikalnom dijelu fiksne proteze i omogućava da taj dio poprimi boju normalnog tkiva. Takav oblik usatka s platformom također omogućava da se mjesto kontakta implantat-nosač s vanjskog gornjeg ruba pomakne prema središtu ramena implantata, čime se dobiva biološka širina u smjeru okomitom na uzdužnu os implantata. Tako se održava visina rubnog koštanog grebena (grebenska kost) na koronalnom vrhu ramena implantata - što ima presudnu ulogu u stvaranju i dugoročnom održavanju papila. Uz to, oblik implantata s platformom olakšava postavljanje nosača u submukozu i sprječava utiskivanje mekog tkiva u područje kontakta između usatka i nosača. Velika čvrstoća i inicijalno mali promjer nosača omogućavaju postizanje: (1) izvrsne estetike i (2) suprastruktura koje su klinički vrlo slične zubu koji je u mostu.A decisive feature of the two-piece implant system of today is a mechanically strong, reliable implant abutment interface. This demand can be optimally achived by a precisely machined, tapered cone abutment (Morse taper) connection. This tapered abutment connection provides high resistance to bending and rotational torque during clinical function which significantly reduces the possibilities of screw fracture of loosening. Additionally, tapered abutement connection causes a platform switched design at the coronal portion of the implant. It enables a thick layer of dense soft tissue to form around the neck of the abutment an dcover the remaining horizontal area of the platform. This thick tissue masks the colour of the titanium that is cervical to the fixed prosthesis and is responsible for normal tissue colour. This platform switched implant design also moves the site of the implant-abutment interface from the outer top margin to the center of the implant shoulder, enabling the establishment of a bilogical width that is perpendicular to the long axis of the implant. The height of the marginal osseous crest (crestal bone) is maintained at the coronal top of the implant shoulder- it plays a decisive role in the formation and long term maintenance of papillas. Additionally, the platform switched design facilitates the mounting of submucosal placed abutments, preventing imapction of soft tissue between the implant-abutment interface. Both the high strength and initial small diameter of the abutment make it possible to obtain: (1) excellent aesthetics and (2) suprastructures that are clinically very similar to tooth borne prostheses

Surgical Considerations for Aesthetic Problems with Implants and Crowns for Single Missing Front Teeth - the Influence of the Implant Diameter on the Red - White Aesthetics

Estetski rezultati nadomještanja prednjih zuba, napose u gornjoj čeljusti, jedno su od najtežih implantoloških pitanja. Postoje, međutim, brojni preimplantacijski pokazatelji koje treba dijagnosticirati prije izvođenja kirurškog zahvata, tako da se rezultat lako može predvidjeti. Među njih se ubrajaju vrsta gingive, količina horizontalne i vertikalne kosti itd. Kliničko nam je iskustvo pokazalo da implantaciju bez augmentacije u mladih osoba, koja se izvodi samo zbog estetike, ne i zbog funkcije, ne treba više izvoditi. Cilj nam je prikazati nekoliko različitih vrsta augmentacije, više u tvrdim (širenje kosti, autologno i alogensko) negoli u mekim tkivima (FTG) i pokazati da se rezultati, na zadovoljstvo pacijenata, mogu predvidjeti. Prednosti nekih sustava omogućavaju postavljanje usatka malog promjera i postizanje izgleda kao da je izrastao iz kosti, te bez problema s gubitkom vestibularne kosti. Izazov implantologiji predstavlja nadomještanje sjekutića i očnjaka na način da se postigne predvidiv estetski rezultat koji će dugo trajati. Osim o multidisciplinarnoj suradnji između oralnih kirurga, protetičara i zubotehničara, rezultat ovisi i o dobrom izgledu krunica na implantatu, s dobrim spojem s tkivom, koji treba izgledati kao da je izrastao iz kosti. Jasno je da za nadomještanje gornjih središnjih sjekutića i očnjaka treba odabrati platformu usatka većeg promjera. Međutim, pregledom podataka objavljenih u literaturi i teoretskih razmatranja koja se odnose na jajolik oblik tijela konvencionalnih mostova, kao i mnogih slučajeva, dolazi se do zaključka da izgled kao da je izrastao iz kosti ne ovisi o promjeru postavljenog usatka. Taj je izgled zadan isključivo oblikom krunice na usatku. Stoga se usadci malog promjera mogu koristiti ako postoji manja količina kosti, no to onemogućava da se brojnim suvremenim kirurškim postupcima poveća količina kosti u vestibularno-oralnoj dimenziji.The aesthetic result in anterior areas, especially in the upper jaw, is one of the most difficult implantological questions. However there are many preimplantological parameters, which can be diagnosed before surgery, so that it is easily possible to get a predictable result. Some of them are the type of gingiva, horizontal and vertical bone quantity etc. Our clinical experience has demonstrated that implantation in younger people without augmentation, when necessary only for aesthetics and not for function, should no longer be tolerated. Our aim is to present different types of augmentation in hard (bone spreading, autologous and allogenic) and in soft tissue (FTG) and to show the predictable results with satisfied patients. Some system advantages allow us to insert low diameter implants with very good emergence profile and no problem with vestibular bone loss. A challenge in implantology is the predictable, long-term aesthetics result, replacing incisors and canines of the upper jaw. Besides multidisciplinary cooperation between oral surgeons, prosthodontists and dental technicians the results depends on the correct emergence profile of impant borne crowns. A wide diameter implant platform should be chosen in case of replacing upper central incisors or canines. However, an analysis of the literature, theoretical considerations regarding ovate shaped pontics of conventional bridges, and many cases, lead to the conclusion that the emergence profile is indipendent of the used implant diameter. The profile is exclusively defined by the shape of the implant borne crown. Therefore, small implant diameters can be used if there is less bone amount, preventing many advanced surgical procedures to improve the bone amount in the oral-vestibular dimension

Is resistance to ischaemia of motor axons in diabetic subjects due to membrane depolarization?

The reasons for the resistance to ischaemia of peripheral nerves in diabetics are not well understood. We have now explored whether axonal depolarization underlies this phenomenon, as has previously been proposed. Resistance to ischaemia was determined by the new method of “threshold tracking”. This method revealed an increase in excitability of the peroneal nerve at the popliteal fossa during ischaemia, and a decrease in excitability in the post-ischaemic period. The extent of these alterations in 28 type 1 diabetics without peripheral neuropathy showed a strong correlation with the mean blood glucose concentrations during the last 24 h before examination. To test whether the ischaemic resistance was related to membrane potential, we also measured axonal superexcitability in 11 selected diabetics, since it has been shown that post-spike changes in excitability depend on membrane potential. Changes in excitability of the peroneal nerve were measured in the period between 10 and 30 msec following a conditioning supramaximal compound action potential. Under resting conditions, no differences in the post-spike superexcitability were found between controls and diabetics, despite striking differences in their responses to a 10-min pressure cuff. These observations indicate that membrane depolarization is not involved in the resistance to ischaemia of motor axons in diabetic subjects

Evidence of re-osseointegration after electrolytic cleaning and regenerative therapy of peri-implantitis in humans: a case report with four implants.

OBJECTIVE To evaluate re-osseointegration after electrolytic cleaning and regenerative therapy of dental implants with peri-implantitis in humans. MATERIAL AND METHODS Four dental implants that developed peri-implantitis underwent electrolytic cleaning followed by regenerative therapy with guided bone regeneration. All four implants developed recurrent peri-implantitis and were therefore explanted 6 to 13 months later. Radiographic bone level, probing depth, and bleeding on probing were determined at the time of surgery, 6 months later, and before implant retrieval. The peri-implant tissues were histologically and histomorphometrically analyzed. RESULTS All four implants demonstrated radiographic and histological bone gain, reduced probing depth, and bleeding on probing. Radiographic bone gain was 5.8 mm mesially and 4.8 mm distally for implant #1, 3.3 mm and 2.3 mm for implant #2, 3.1 mm and 0.5 mm for implant #3, and 3.5 mm and 2.8 mm for implant #4. The histometric mean and maximum vertical bone gain for implant #1 to #4 was 1.65 mm and 2.54 mm, 3.04 mm and 3.47 mm, 0.43 mm and 1.27 mm, and 4.16 mm and 5.22 mm, respectively. The percentage of re-osseointegration for implant #1 to #4 was 21.0%, 36.9%, 5.7%, and 39.0%, respectively. In one implant, the newly formed bone was deposited directly onto calculus on the implant surface. CONCLUSIONS We found that (1) re-osseointegration is possible on a formerly contaminated implant surface and (2) the electrolytic cleaning process seems to be effective enough at sites with calculus residues. CLINICAL RELEVANCE Since re-osseointegration can be achieved by electrolytic cleaning, this decontamination technique may be considered as a future treatment concept

A versatile biomaterial ink platform for the melt electrowriting of chemically-crosslinked hydrogels

In this study, we designed a novel biomaterial ink platform based on hydrophilic poly(2-ethyl-2-oxazine) (PEtOzi) specifically for melt electrowriting (MEW). This material crosslinks spontaneously after processing via dynamic Diels–Alder click chemistry. These direct-written microperiodic structures rapidly swell in water to yield thermoreversible hydrogels. These hydrogels are robust enough for repeated aspiration and ejection through a cannula without structural damage, despite their high water content of 84%. Moreover, the scaffolds retain functional groups for modification using click chemistry and therefore can be readily functionalized as demonstrated using fluorophores and peptides to facilitate visualization and cell attachment. The PEtOzi hydrogel developed here is compatible with confocal imaging and staining protocols for cells. In summary, an advanced material platform based on PEtOzi is reported that is compatible with MEW and results in functionalizable chemically crosslinked microperiodic hydrogels.Peer reviewe

"Ain schone kunstliche underweisung": Modelling German lute tablature in MEI

Abstract: https://teimec2023.uni-paderborn.de/contributions/188.htm

Suitability of soil carbon certificates for climate change mitigation

There is growing awareness of the role that agricultural soils can play for climate change mitigation. Agricultural management that increases soil organic carbon (SOC) stocks constitutes a nature-based solution for carbon dioxide removal. As soils store about twice the amount of carbon found in the atmosphere, even small relative increases could significantly reduce global warming. However, increasing SOC requires management changes that come with costs to the farmers. In this regard, soil carbon certificates could provide a much-needed financial incentive: Farmers register their fields with commercial providers who certify any SOC increase achieved during a set period of time. The certificates are then sold on the voluntary carbon-offset market. We analysed the suitability of soil carbon certificates for climate change mitigation from the perspectives of soil sciences, agricultural management, and governance. In particular, we addressed questions of quantification, additionality, permanence, changes in emissions, leakage effects, transparency, legitimacy and accountability, as well as synergies and trade-offs with other societal targets. Soil properties and the mechanisms by which carbon is stored in soils have strong implications for the assessment. Soils have a limited storage capacity, and SOC is not sequestered but its SOC stocks are the dynamic result of plant derived inputs and losses mainly in the form of microbial respiration. The higher the SOC stock, the higher the annual carbon inputs that is needed to maintain it. If carbon friendly management is discontinued, elevated SOC levels will therefore revert to their original level. We found that while changes in agricultural management that increase SOC are highly desirable and offer multiple-co benefits with climate change adaptation, soil carbon certificates are unsuitable as a tool. They are unlikely to deliver the climate change mitigation they promise as certificate providers cannot guarantee permanence and additionality of SOC storage over climate relevant time-frames. Where the certified carbon storage is non-permanent or fails to meet criteria of additionality, the use of such certificates to advertise products as “carbon-neutral” may be construed as false advertising

Carbon farming: Are soil carbon certificates a suitable tool for climate change mitigation?

Increasing soil organic carbon (SOC) stocks in agricultural soils removes carbon dioxide from the atmosphere and contributes towards achieving carbon neutrality. For farmers, higher SOC levels have multiple benefits, including increased soil fertility and resilience against drought-related yield losses. However, increasing SOC levels requires agricultural management changes that are associated with costs. Private soil carbon certificates could compensate for these costs. In these schemes, farmers register their fields with commercial certificate providers who certify SOC increases. Certificates are then sold as voluntary emission offsets on the carbon market. In this paper, we assess the suitability of these certificates as an instrument for climate change mitigation. From a soils' perspective, we address processes of SOC enrichment, their potentials and limits, and options for cost-effective measurement and monitoring. From a farmers’ perspective, we assess management options likely to increase SOC, and discuss their synergies and trade-offs with economic, environmental and social targets. From a governance perspective, we address requirements to guarantee additionality and permanence while preventing leakage effects. Furthermore, we address questions of legitimacy and accountability. While increasing SOC is a cornerstone for more sustainable cropping systems, private carbon certificates fall short of expectations for climate change mitigation as permanence of SOC sequestration cannot be guaranteed. Governance challenges include lack of long-term monitoring, problems to ensure additionality, problems to safeguard against leakage effects, and lack of long-term accountability if stored SOC is re-emitted. We conclude that soil-based private carbon certificates are unlikely to deliver the emission offset attributed to them and that their benefit for climate change mitigation is uncertain. Additional research is needed to develop standards for SOC change metrics and monitoring, and to better understand the impact of short term, non-permanent carbon removals on peaks in atmospheric greenhouse gas concentrations and on the probability of exceeding climatic tipping points