Retrospective analysis of augmentation procedures with umbrella screws, a novel tenting technique: a consecutive case series in 279 patients

OBJECTIVES

The consecutive case series accesses the results and experiences of ridge augmentation using an umbrella screw tenting technique.

METHOD AND MATERIALS

In total, 279 patients were treated between 26 May 2015 and 16 June 2021, including horizontal and vertical ridge defects. Sex, age, smoking behavior, jaw, graft material, soft tissue thickness, extent of horizontal/vertical augmentation, resorption rate, and occurrence of early/late exposure were evaluated. Bone gain was determined by resorption at the screw head. Only cases without premature screw removal were evaluated metrically (n = 201). All other augmentations were evaluated according to whether implantation was possible with or without further augmentation (n = 27). A target performance index was calculated, which should enable evidence-based comparability of different augmentation methods in future.

RESULTS

In total, 54 wound dehiscences (39 early, 15 late exposures) occurred, which corresponds to 24.08% of the augmented sites; 42 umbrella screws were removed prematurely. In all cases an implantation was possible at the desired position afterwards. Cases with a vertical augmentation component showed a higher prevalence of exposure (early, P = .000; late, P = .024). The extent of the vertical augmentation was only relevant for early exposure (P = .048). Mean bone gain of 4.23 ± 1.69 mm horizontally and 4.11 ± 1.99 mm vertically could be achieved. Regression analysis showed that there was no limit in horizontal/vertical direction. Mean percentage target performance index was 75.90 ± 20.54 for vertical and 82.25 ± 16.67 for horizontal portions.

CONCLUSION

The umbrella technique is an effective augmentation method, which can be applied to any defect morphology.

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.

Effects of surface roughness and mineralogy on the sorption of Cm(III) on crystalline rock

Crystalline rock is one of the host rocks considered for a future deep geological repository for highly active radiotoxic nuclear waste. The safety assessment requires reliable information on the retention behavior of minor actinides. In this work, we applied various spatially resolved techniques to investigate the sorption of Curium onto crystalline rock (granite, gneiss) thin sections from Eibenstock, Germany and Bukov, Czech Republic. We combined Raman-microscopy, calibrated autoradiography and µTRLFS (micro-focus time-resolved fluorescence spectroscopy) with vertical scanning interferometry to study in situ the impact of mineralogy and surface roughness on Cm(III) uptake and molecular speciation on the surface. Heterogeneous sorption of Cm(III) on the surface depends primarily on the mineralogy. However, for the same mineral class sorption uptake and strength of Cm(III) increases with growing surface roughness around surface holes or grain boundaries. When competitive sorption between multiple mineral phases occurs, surface roughness becomes the major retention parameter on low sorption uptake minerals. In high surface roughness areas primarily Cm(III) inner-sphere sorption complexation and surface incorporation are prominent and in selected sites formation of stable Cm(III) ternary complexes is observed. Our molecular findings confirm that predictive radionuclide modelling should implement surface roughness as a key parameter in simulations.

New insights into U(VI) sorption onto montmorillonite from batch sorption and spectroscopic studies at increased ionic strength

The influence of ionic strength up to 3 mol kg^-1 (background electrolytes NaCl or CaCl₂) on U(VI) sorption onto montmorillonite was investigated as function of pH_c in absence and presence of CO₂. A multi-method approach combined batch sorption experiments with spectroscopic methods (time-resolved laser-induced fluorescence spectroscopy (TRLFS) and in situ attenuated total reflection Fourier-transform infrared spectroscopy (ATR FT-IR)). In the absence of atmospheric carbonate, U(VI) sorption was nearly 99% above pH_c 6 in both NaCl and CaCl₂ and no significant effect of ionic strength was found. At lower pH, cation exchange was strongly reduced with increasing ionic strength. In the presence of carbonate, U(VI) sorption was reduced above pH_c 7.5 in NaCl and pH_c 6 in CaCl₂ system due to formation of aqueous UO₂(CO₃)_x^(2-2x) and Ca₂UO₂(CO₃)₃ complexes, respectively, as verified by TRLFS. A significant ionic strength effect was observed due to the formation of Ca₂UO₂(CO₃)_3(aq), which strongly decreases U(VI) sorption with increasing ionic strength. The joint analysis of determined sorption data together with literature data (giving a total of 213 experimental data points) allowed to derive a consistent set of surface complexation reactions and constants based on the 2SPNE SC/CE approach, yielding log K°_{≡S^SOUO2⁺} = 2.42 ± 0.04, log K°_≡S^SOUO2OH = -4.49 ± 0.7, and log K°_{≡S^SOUO2(OH)3^2-} = -20.5 ± 0.4. Ternary uranyl carbonate surface complexes were not required to describe the data. With this reduced set of surface complexes, an improved robust sorption model was obtained covering a broad variety of geochemical settings over wide ranges of ionic strengths and groundwater compositions, which subsequently was validated by an independent original dataset. This model improves the understanding of U(VI) retention by clay minerals and enables now predictive modeling of U(VI) sorption processes in complex clay rich natural environments.

Treatment of Periimplantitis with Electrolytic Cleaning versus Mechanical and Electrolytic Cleaning: 18-Month Results from a Randomized Controlled Clinical Trial

Aim of the study: This RCT assesses patients’ 18-month clinical outcomes after the regenerative therapy of periimplantitis lesions using either an electrolytic method (EC) to remove biofilms or a combination of powder spray and an electrolytic method (PEC). Materials and Methods: Twenty-four patients (24 implants) suffering from periimplantitis were randomly treated by EC or PEC followed by augmentation and submerged healing. Probing pocket depth (PPD), Bleeding on Probing (BoP), suppuration, and standardized radiographs were assessed before surgery (T0), 6 months after augmentation (T1), and 6 (T2) and 12 (T3) months after the replacement of the restoration. Results: The mean PPD changed from 5.8 ± 1.6 mm (T0) to 3.1 ± 1.4 mm (T3). While BoP and suppuration at T0 were 100%, BoP decreased at T2 to 36.8% and at T3 to 35.3%. Suppuration was found to be at a level of 10.6% at T2 and 11.8% at T3. The radiologic bone level measured from the implant shoulder to the first visible bone to the implant contact was 4.9 ± 1.9 mm at mesial sites and 4.4 ± 2.2 mm at distal sites at T0 and 1.7 ± 1.7 mm and 1.5 ± 17 mm at T3. Conclusions: Significant radiographic bone fill and the improvement of clinical parameters were demonstrated 18 months after therapy.

An integrated approach combining soil profile, records and tree ring analysis to identify the origin of environmental contamination in a former uranium mine (Rophin, France)

Uranium mining and milling activities raise environmental concerns due to the release of radioactive and other toxic elements. Their long-term management thus requires a knowledge of past events coupled with a good understanding of the geochemical mechanisms regulating the mobility of residual radionuclides. This article presents the results on the traces of anthropic activity linked to previous uranium (U) mining activities in the vicinity of the Rophin tailings storage site (Puy de Dôme, France). Several complementary approaches were developed based on a study of the site's history and records, as well as on a radiological and chemical characterization of soil cores and a dendrochronology. Gamma survey measurements of the wetland downstream of the Rophin site revealed a level of 1050 nSv.h^-1. Soil cores extracted in the wetland showed U concentrations of up to 1855 mg.kg^-1, which appears to be associated with the presence of a whitish silt loam (WSL) soil layer located below an organic topsoil layer. Records, corroborated by prior aerial photographs and analyses of ¹³⁷Cs and ¹⁴C activities, suggest the discharge of U mineral particles while the site was being operated. Moreover, lead isotope ratios indicate that contamination in the WSL layer can be discriminated by a larger contribution of radiogenic lead to total lead. The dendroanalysis correlate U emissions from Rophin with the site's history. Oak tree rings located downstream of the site contain uranium concentrations ten times higher than values measured on unaffected trees. Moreover, the highest U concentrations were recorded not only for the operating period, but more surprisingly for the recent site renovations as well. This integrated approach corroborates that U mineral particles were initially transported as mineral particles in Rophin's watershed and that a majority of the deposited uranium appears to have been trapped in the topsoil layer, with high organic matter content.

A comprehensive study of the sorption mechanism and thermodynamics of f-element sorption onto K-feldspar

The mobility of heavy metal contaminants and radionuclides in the environment is directly controlled by their interactions with charged mineral surfaces, hence an assessment of their potential toxicity, e.g. in the context of radioactive waste disposal sites, requires understanding of sorption processes on the molecular level. Here, we investigate the sorption of a variety of rare earth elements (REE) and trivalent actinides (Am, Cm) on K-feldspar using batch sorption, time-resolved laser-induced fluorescence spectroscopy (TRLFS), and a surface complexation model. Initially, a reliable pK_a for K-feldspar's surface deprotonation reaction was determined as 2.5 ± 0.02 by column titration experiments, in excellent agreement with a measured pH_IEP of 2.8. Batch sorption experiments over a broad range of experimental conditions in terms of mineral grain size, pH, [M³⁺], ionic radius, solid/liquid ratio, ionic strength, and equilibration procedures were carried out to quantify macroscopic retention. The trivalent d-block element Y, early, mid, and late lanthanides (La, Eu, Nd, Lu), as well as two minor actinides (Am, Cm) were used for batch sorption experiments and showed similar pH dependent uptake behavior, underlining their chemical analogy. In parallel, spectroscopic investigations provided insight into surface speciation. Cm TRLFS spectra indicate the formation of three inner-sphere sorption complexes with increasing hydrolysis. Additionally, a ternary K-feldspar/Cm/silicate complex was found for pH > 10, and batch and spectroscopic data at low pH (<4) point to small amounts of outer sphere sorption complexes. Based on TRLFS data, batch sorption, and titration data, a generic geochemical sorption model was developed, that describes sorption edges for all investigated M³⁺/K-feldspar systems satisfactorily. The derived stability constants for the binary sorption complexes (logK_1-4 = -3.6, -7.7, -11.5, and -17.4, respectively) could successfully be used to reproduce literature data. The stability constants obtained for the surface complexes were included into the database for the Smart K_d-concept, which will further improve the safety assessment of potential repositories for radioactive waste.

Temperature-dependent luminescence spectroscopic investigations of uranyl(vi) complexation with the halides F− and Cl−

Uranyl(vi) complexation with fluoride and chloride was investigated with luminescence spectroscopy, and the strong quenching by chloride was overcome by freezing.

Spectroscopic identification of ternary Cm-carbonate surface complexes

The influence of dissolved CO(2) on the sorption of trivalent curium (Cm) on alumina (gamma-Al(2)O(3)) and kaolinite was investigated by time resolved laser fluorescence spectroscopy (TRLFS) using the optical properties of Cm as a local luminescent probe. Measurements were performed at T < 20 K on Cm loaded gamma-Al(2)O(3) and kaolinite wet pastes prepared in the absence and presence of carbonate in order to pictorially illustrate any changes through a direct comparison of spectra from both systems. The red-shift of excitation and emission spectra, as well as the increase of fluorescence lifetimes observed in the samples with carbonate, clearly showed the influence of carbonate and was fully consistent with the formation of Cm(III) surface species involving carbonate complexes. In addition, the biexponential decay behavior of the fluorescence lifetime indicated that at least two different Cm(III)-carbonate species exist at the mineral-water interface. These results provide the first spectroscopic evidence for the formation of ternary Cm(III)-carbonate surface complexes.

Incorporation of Eu(III) into hydrotalcite: a TRLFS and EXAFS study

The behavior of radionuclides in the environment (geo-, hydro-, and biosphere) is determined by interface reactions like adsorption, ion exchange, and incorporation processes. Presently, operational gross parameters for the distribution between solution and minerals are available. For predictive modeling of the radionuclide mobility in such systems, however, individual reactions and processes need to be localized, characterized, and quantified. A prerequisite for localization and clarification of the concerned processes is the use of modern advanced analytical and speciation methods, especially spectroscopy. In this study, Eu(III) was chosen as an analogue for trivalent actinides to identify the different species that occur by the Ln(III)/hydrotalcite interaction. Therefore, Eu(III) doped Mg-Al-Cl-hydrotalcite was synthesized and investigated by TRLFS, EXAFS, and XRD measurements. Two different Eu/hydrotalcite species were obtained. The minor part of the lanthanide is found to be inner-sphere sorbed onto the mineral surface, while the dominating Eu/hydrotalcite species consists of Eu(III) that is incorporated into the hydrotalcite lattice. Both Eu/hydrotalcite species have been characterized by their fluorescence emission spectra and lifetimes. Structural parameters of the incorporated Eu(III) species determined by EXAFS indicate a coordination number of 6.6 +/- 1.3 and distances of 2.41 +/- 0.02 A for the first Eu-OH shell.

Systemic tacrolimus in the treatment of severe atopic keratoconjunctivitis

PURPOSE

Severe atopic keratoconjunctivitis (AKC) forms part of the spectrum of allergic eye disease and is often refractory to conventional topical treatment. Topical cyclosporin A and tacrolimus have been shown to reduce immunologic activation, symptoms, and signs of patients suffering from AKC, but there are no reports on safety and efficacy of systemic tacrolimus for this condition.

METHODS

We report on a retrospective study of 3 patients with severe AKC, where the disease did not respond to conventional therapy, and they were therefore treated with low-dose systemic tacrolimus for at least 1 year as an adjunct to their existing treatment.

RESULTS

There was a good clinical response in all patients to low-dose systemic tacrolimus, with a low incidence of side effects and no relapse of symptoms after discontinuation of treatment.

CONCLUSION

Low-dose systemic tacrolimus is a safe and effective treatment of some patients with severe AKC, which is refractory to conventional treatment. Such patients need careful monitoring for side effects, and the long-term benefits need to be assessed as part of a clinical trial.

Structural characterization of Am incorporated into calcite: A TRLFS and EXAFS study

Calcite homogeneously doped with Am(III) and Cm(III) was synthesized in a mixed-flow reactor. The mechanism of incorporation of these actinides (An) into calcite was investigated by time-resolved laser fluorescence spectroscopy. Two different An(III)/calcite species were found. One has been identified as ions bonded onto the calcite surface. The second An(III) species has lost its complete hydration sphere and is incorporated into the calcite bulk structure. Both Cm(III)/calcite and Am(III)/calcite complexes have been characterized by their fluorescence emission spectra and lifetimes. Structural parameters of the incorporated Am(III) species determined by EXAFS indicate a coordination number of 6.3+/-0.6 and distances of 2.40+/-0.01 A for the first AmO shell.

The effect of cholecystectomy on plasma cholecystokinin

OBJECTIVE

Gallbladder removal is associated with an increased incidence of gastroesophageal reflux, but the mechanism is unclear. Cholecystokinin (CCK) release, which causes gallbladder contraction, is inhibited by bile in the duodenum. This study investigates the effect of cholecystectomy on meal-stimulated CCK secretion.

METHODS

Three groups of patients were studied. Group 1 (n = 15) were normal controls. Group 2 (n = 27) were patients with symptomatic gallstones. Group 3 (n = 25) were patients who had undergone cholecystectomy. Meal-stimulated CCK levels were measured by radioimmunoassay at defined time points for 60 min after a standard corn oil-based meal.

RESULTS

Fasting CCK levels were similar in all three groups. In postcholecystectomy patients, meal-stimulated plasma CCK levels were significantly elevated compared with controls: median (range) integrated CCK values for 60 min were 116 (28-209) in controls, 123 (20-501) in gallstone patients, and 176 (63-502) after cholecystectomy.

CONCLUSIONS

This study suggests that cholecystectomy causes an exaggerated meal-stimulated CCK response. Because CCK is known to relax the lower esophageal sphincter. these findings may help explain the increased incidence of gastroesophageal reflux seen after cholecystectomy.

Time-resolved laser fluorescence spectroscopy study of the sorption of Cm(III) onto smectite and kaolinite

For long-term performance assessment of nuclear waste repositories knowledge concerning interactions of actinides with mineral surfaces is imperative. The mobility and bioavailability of released radionuclides is strongly dependent on sorption/desorption processes onto mineral surfaces. Therefore it is necessary to characterize the surface species formed and to elucidate the reaction mechanisms involved. The high fluorescence spectroscopic sensitivity of Cm(III) has attracted our interest regarding the complexation process of Cm(III) onto smectite and kaolinite as a model system for the sorption of trivalent actinides in the trace concentration range. We conclude that at low pH Cm(III) is sorbed onto kaolinite and smectite as an outer-sphere complex and retains its complete primary hydration sphere. With increasing pH inner-sphere adsorption onto kaolinite and smectite occurs via the aluminol edge sites. The same evolution of the Cm(III)-clay surface species as a function of pH was observed for both minerals. Starting at a pH > or = 5 we observe the formation of a [triple bond]Al-O-Cm2+(H2O)5 surface complex, which is replaced by a second species at higher pH. The second surface complex may be a monodentate [triple bond]Al-O-Cm+(OH)(H2O)4 species or bidentate [triple bond](Al-O)2-Cm+(H2O)5 species. The Cm(III)/clay surface complexes are characterized bytheir emission spectra (peak maxima at 598.8 and 603.3 nm) and their fluorescence lifetime (both 110 +/- 7 micros). An important result in view of the mobility and bioavailability of radionuclides is that no incorporation of Cm(III) into the bulk clay structure was observed.

[Time perception and time estimation in depressive patients]

Subjective time-experience and objective time-estimation were examined in 20 endogenous, 20 neurotic depressives, and 15 healthy volunteers. Subjective experience of past and anticipated future time was more extended in both depressive groups than in healthy controls. Objective time estimation differed between depressives and controls concerning relatively long time spans whereas very short time spans were correctly estimated also by depressives. There were no significant differences between endogenous and neurotic depressives. The perception of extended time normalized during treatment. The depressives' time perception, differences correlated with the extent of depressive psychopathological symptoms and--to a lesser degree--with retardation. The findings support the hypotheses of anthropological phenomenology concerning disturbed time perception and estimation in depressives. Amelioration of experienced time-extension in intentionally structured time spans compared to empty time spans suggests psychotherapeutic consequences in the sense of Lewinsohn.

Computer-based ST/HR slope calculation on Marquette CASE 12: development and technical considerations

Computer-based implementation of the ST/HR slope on Marquette CASE 12 is described. ST-segment measurement is performed with improved software for QRS detection and incremental signal updating, and on-line test calculation results from automated linear regression, leading to graphic display of the maximum ST/HR slope at the end of exercise.

Luteinizing hormone and progesterone concentrations in serum of heifers administered a short half-life prostaglandin (PGF2α) or long half-life prostaglandin analogue (fenprostalene) on days six or eleven of the estrous cycle

Two trials were conducted to measure the progesterone (P(4)) decline and luteinizing hormone (LH) surge in serum subsequent to administration of a short half-life (short t (1 2 )) prostaglandin (PGF(2alpha)) or a long half-life (long t (1 2 )) prostaglandin analogue (fenprostalene) on Days 6 or 11 of the estrous cycle. Twenty-five crossbred Shorthorn and five Hereford heifers with a mean weight of 331.4 +/- 29.8 kg were used in both trials. The heifers were randomly allotted to receive either a short t (1 2 ) or long t (1 2 ) prostaglandin treatment on Day 6 or 11 of the estrous cycle. A crossover design for the main effect, treatment (type of prostaglandin), was conducted. Heifers that received PGF(2alpha) in Trial I were given fenprostalene in Trial II and vice versa. Stage of the estrous cycle (day) was the same for each heifer in both trials. Stage of estrous cycle was standardized to either Day 6 or 11 by administering Syncro-Mate B (SMB). Blood was collected every hour for 80 h post injection to quantify LH and P(4) concentrations. There were no significant differences (P > 0.05) between the short t (1 2 ) or long t (1 2 ) for either P(4) or LH profiles. In addition, no differences were detected between stages of the estrous cycle for the timing of the preovulatory surge of LH after prostaglandin administration.