Vertical bone augmentation and regular implants versus short implants in the vertically deficient posterior mandible:a systematic review and meta-analysis of randomized studies

Item does not contain fulltextThe aim of this study was to perform a systematic review and meta-analysis of randomized controlled trials (RCTs) comparing the outcomes of short dental implants (≤7mm) versus vertical bone augmentation followed by regular dental implants (>7mm) in the deficient posterior mandible. In total, eight RCTs (six using interpositional sandwich grafting and two using a guided bone regeneration technique) were reported in 17 articles at different time points. In the meta-analysis of the sandwich group, the relative risk (RR) for implant loss at 1year was in favour of short implants (RR 0.41, P=0.02), while no significant difference was found at 3 years (RR 0.65, P=0.43), 5 years (RR 1.08, P=0.86), or 8 years (RR 1.53, P=0.52). The risk of complications was in favour of short implants (RR 0.34, P=0.0002), as was the mean difference in marginal bone resorption after 1 year (-0.09mm, P=0.17), 3 years (-0.32mm, P<0.00001), 5 years (-0.65mm, P<0.00001), and 8 years (-0.88, P<0.00001). The mean residual osseointegration length of the implants was between 2.94mm and 4.44mm in the short implants group and between 7.97mm and 8.62mm in the regular implants group after 5 years. In conclusion, in the deficient atrophic posterior mandible, short implants and regular implants demonstrate comparable outcomes within the first 5 years. Patients who are fit for surgery should be informed about the risks and benefits of both options

Slowing heavy, ground-state molecules using an alternating gradient decelerator

Cold supersonic beams of molecules can be slowed down using a switched sequence of electrostatic field gradients. The energy to be removed is proportional to the mass of the molecules. Here we report deceleration of YbF, which is 7 times heavier than any molecule previously decelerated. We use an alternating gradient structure to decelerate and focus the molecules in their ground state. We show that the decelerator exhibits the axial and transverse stability required to bring these molecules to rest. Our work significantly extends the range of molecules amenable to this powerful method of cooling and trapping.Comment: 4 pages, 5 figure

Spectroscopic characterization of singlet-triplet doorway states of aluminum monofluoride

Aluminum monofluoride (AlF) possesses highly favorable properties for laser cooling, both via the A1Π and a3Π states. Determining efficient pathways between the singlet and the triplet manifold of electronic states will be advantageous for future experiments at ultralow temperatures. The lowest rotational levels of the A1Π, v = 6 and b3Σ+, v = 5 states of AlF are nearly iso-energetic and interact via spin–orbit coupling. These levels thus have a strongly mixed spin-character and provide a singlet–triplet doorway. We here present a hyperfine resolved spectroscopic study of the A1Π , v = 6//b3Σ+, v = 5 perturbed system in a jet-cooled, pulsed molecular beam. From a fit to the observed energies of the hyperfine levels, the fine and hyperfine structure parameters of the coupled states and their relative energies as well as the spin–orbit interaction parameter are determined. The standard deviation of the fit is about 15 MHz. We experimentally determine the radiative lifetimes of selected hyperfine levels by time-delayed ionization, Lamb dip spectroscopy, and accurate measurements of the transition lineshapes. The measured lifetimes range between 2 and 200 ns, determined by the degree of singlet–triplet mixing for each level

Is the time in therapeutic range on coumarins predicted by previous time in therapeutic range?

Background The benefit of vitamin K antagonists depends on the time within the therapeutic range (TTR). A patient's previous TTR could be a factor in the decision to change the anticoagulation regimen. However, the predictive value of a previous TTR for a future TTR is not well established, nor is it clear which TTR should prompt action. Objectives To investigate the predictive performance of a TTR and identify a threshold below which no recovery of TTR should be expected. Patients/Methods From 18 031 patients who used acenocoumarol in a first-line anticoagulation clinic, a TTR was calculated over multiple periods of 90, 180, and 365 days each. We assessed the correlation between baseline and later TTR and the separation between groups by quintile of baseline TTR. We describe the proportion of patients who obtain a TTR >= 70% conditional on baseline TTR. Results The correlation between baseline and later TTR was 0.25 (95% confidence interval [CI], 0.24-0.26), 0.27 (95% CI, 0.26-0.28) and 0.34 (95% CI, 0.32-0.35) for analyses over 90, 180, and 365 days. Corresponding c statistics for discrimination by baseline group were 0.60, 0.61, and 0.63. The probability to obtain a TTR >= 70% increased with baseline TTR: from 42% with a baseline TTR of 50%-65% when TTR was 100% (TTR calculated over 180 days). Conclusions We conclude that a current TTR hardly predicts a future TTR. Physicians and patients should deliberate together which probabilities to accept, take measures to improve TTR, and consider potential alternatives

Risks and liability in complications with respect to implant-supported suprastructures

Despite high survival percentages of oral implants and suprastructures, various risks threaten the success of oral implant treatments. Four risk categories can be distinguished: complications during surgical treatment, loss or impending loss of the implant, fracture or wearing out of (parts of) the suprastructure, and patient dissatisfaction with the treatment outcome. The question is when a complication can be expected on the basis of present-day knowledge in a certain percentage of cases and when one can speak of negligence. In cases where treatment is carried out in accordance with the most recent protocols, guidelines and recommendations, there can be no question of liability. It is proposed that retreatment is carried out without any costs if an implant or a superstructure is lost within one year post-treatment.</p

Planned dose of intensity modulated proton beam therapy versus volumetric modulated arch therapy to tooth-bearing regions

Background: Intensity modulated proton beam therapy (IMPT) for head and neck cancer offers dosimetric benefits for the organs at risk when compared to photon-based volumetric modulated arch therapy (VMAT). However, limited data exists about the potential benefits of IMPT for tooth-bearing regions. The aim of this study was to compare the IMPT and VMAT radiation dosimetrics of the tooth-bearing regions in head and neck cancer patients. Also, we aimed to identify prognostic factors for a cumulative radiation dose of ≥40 Gy on the tooth-bearing areas, which is considered the threshold dose for prophylactic dental extractions. Methods: A total of 121 head and neck cancer patients were included in this retrospective analysis of prospectively collected data. We compared the average Dmean values of IMPT versus VMAT of multiple tooth-bearing regions in the same patients. Multivariate logistic regression analysis was performed for receiving a cumulative radiation dose of ≥40 Gy to the tooth-bearing regions (primary endpoint) in both VMAT and IMPT. Results: A lower Dmean was seen after applying IMPT to the tooth-bearing tumour regions (p &lt; 0.001). Regarding VMAT, oral cavity tumours, T3-T4 tumours, molar regions in the mandible, and regions ipsilateral to the tumour were risk factors for receiving a cumulative radiation dose of ≥40 Gy. Conclusions: IMPT significantly reduces the radiation dose to the tooth-bearing regions.</p