Role of anatomical sites and correlated risk factors on the survival of orthodontic miniscrew implants:a systematic review and meta-analysis

Abstract Objectives The aim of this review was to systematically evaluate the failure rates of miniscrews related to their specific insertion site and explore the insertion site dependent risk factors contributing to their failure. Search methods An electronic search was conducted in the Cochrane Central Register of Controlled Trials (CENTRAL), Web of Knowledge, Scopus, MEDLINE and PubMed up to October 2017. A comprehensive manual search was also performed. Eligibility criteria Randomised clinical trials and prospective non-randomised studies, reporting a minimum of 20 inserted miniscrews in a specific insertion site and reporting the miniscrews’ failure rate in that insertion site, were included. Data collection and analysis Study selection, data extraction and quality assessment were performed independently by two reviewers. Studies were sub-grouped according to the insertion site, and the failure rates for every individual insertion site were analysed using a random-effects model with corresponding 95% confidence interval. Sensitivity analyses were performed in order to test the robustness of the reported results. Results Overall, 61 studies were included in the quantitative synthesis. Palatal sites had failure rates of 1.3% (95% CI 0.3–6), 4.8% (95% CI 1.6–13.4) and 5.5% (95% CI 2.8–10.7) for the midpalatal, paramedian and parapalatal insertion sites, respectively. The failure rates for the maxillary buccal sites were 9.2% (95% CI 7.4–11.4), 9.7% (95% CI 5.1–17.6) and 16.4% (95% CI 4.9–42.5) for the interradicular miniscrews inserted between maxillary first molars and second premolars and between maxillary canines and lateral incisors, and those inserted in the zygomatic buttress respectively. The failure rates for the mandibular buccal insertion sites were 13.5% (95% CI 7.3–23.6) and 9.9% (95% CI 4.9–19.1) for the interradicular miniscrews inserted between mandibular first molars and second premolars and between mandibular canines and first premolars, respectively. The risk of failure increased when the miniscrews contacted the roots, with a risk ratio of 8.7 (95% CI 5.1–14.7). Conclusions Orthodontic miniscrew implants provide acceptable success rates that vary among the explored insertion sites. Very low to low quality of evidence suggests that miniscrews inserted in midpalatal locations have a failure rate of 1.3% and those inserted in the zygomatic buttress have a failure rate of 16.4%. Moderate quality of evidence indicates that root contact significantly contributes to the failure of interradicular miniscrews placed between the first molars and second premolars. Results should be interpreted with caution due to methodological drawbacks in some of the included studies

A palaeoenvironmental reconstruction of the Middle Jurassic of Sardinia (Italy) based on integrated palaeobotanical, palynological and lithofacies data assessment

During the Jurassic, Sardinia was close to continental Europe. Emerged lands started from a single island forming in time a progressively sinking archipelago. This complex palaeogeographic situation gave origin to a diverse landscape with a variety of habitats. Collection- and literature-based palaeobotanical, palynological and lithofacies studies were carried out on the Genna Selole Formation for palaeoenvironmental interpretations. They evidence a generally warm and humid climate, affected occasionally by drier periods. Several distinct ecosystems can be discerned in this climate, including alluvial fans with braided streams (Laconi-Gadoni lithofacies), paralic swamps and coasts (Nurri-Escalaplano lithofacies), and lagoons and shallow marine environments (Ussassai-Perdasdefogu lithofacies). The non-marine environments were covered by extensive lowland and a reduced coastal and tidally influenced environment. Both the river and the upland/hinterland environments are of limited impact for the reconstruction. The difference between the composition of the palynological and palaeobotanical associations evidence the discrepancies obtained using only one of those proxies. The macroremains reflect the local palaeoenvironments better, although subjected to a transport bias (e.g. missing upland elements and delicate organs), whereas the palynomorphs permit to reconstruct the regional palaeoclimate. Considering that the flora of Sardinia is the southernmost of all Middle Jurassic European floras, this multidisciplinary study increases our understanding of the terrestrial environments during that period of time

Palynological, Palynofacies, Paleoenvironmental and Organic Geochemical Studies on the Upper Cretaceous Succession of the GPTSW-7 Well, North Western Desert, Egypt

The present study of the Abu Roash and Bahariya formations in well GPTSW-7 refines our understanding of the subsurface Cretaceous of the north Western Desert of Egypt. Our investigations are based on the palynological analyses of 71 cuttings samples, of which 24 have also been analyzed for geochemistry, in addition to 3 sidewall cores analyzed for vitrinite reflectance (Ro). Four palynological zones and three subzones in addition to a poorly fossiliferous interval ranging in age from Coniacian-Santonian to early Cenomanian are proposed. These include a poorly fossiliferous interval (Coniacian-Santonian), Dinogymnium vozzhennikovae Interval Zone (late to middle Turonian), Ephedripites ambiguus-Ephedripites multicostatus-Foveotricolpites giganteus-Foveotricolpites gigantoreticultus Assemblage Zone (early Turonian), Classopollis brasiliensis Interval Zone (late to middle Cenomanian), and Afropollis jardinus Interval Zone (early Cenomanian). The succeeding subzones are; Afropollis kahramanensis Interval Subzone, Elaterosporites klaszii Interval Subzone and Cretacaeiporites densimurus Interval Subzone, all of early Cenomanian age. Total organic carbon (TOC) and Rock-Eval pyrolysis and palynofacies analyses indicate that the Bahariya Formation and the Abu Roash G Member are primarily of kerogen III type and hence gas prone, suggesting a strong influence of hydrogen-enriched organic matter. The Abu Roash A, C-E Members may also be gas prone (type III kerogen) and appear to contain highly oxidized terrestrial organic matter. In contrast, the Abu Roash F Member has very high TOC and HI values and contains a very high proportion of amorphous organic matter (AOM) indicating a highly oil-prone facies. While this finding is not unexpected for anoxic black shale, it contrasts with earlier studies that suggest a gas prone nature. Ro measurements show that the Bahariya Formation represents an immature-early genesis dry gas phase. This is also true for all investigated samples from the Abu Roash and Bahariya formations, based on their low thermal alteration index (TAI). Quantitative and qualitative analyses of both the palynoflora and palynofacies show that the Abu Roash A and C Members (B is missing), both of Coniacian-Santonian age, represent oxic proximal and distal shelf environment. The Abu Roash D and E Members, dated as Turonian, represent oxic (proximal) shelf, whereas the Cenomanian Abu Roash F Member was deposited in a distal suboxic-anoxic basin. The Cenomanian Abu Roash G Member and the Bahariya Formation were deposited in a shallow marine and shallow marine to fluvio-deltaic setting, respectively. The Senonian Palmae Province is recognized in the palynoflora by the presence of Proteacidites, Auriculiidites reticulatus, Ariadnaesporites, Gabonisporis vigourouxii. On the other hand the Albian-Cenomanian Elaterates Province is characterized by the presence of Steevesipollenites, Gnetaceaepollenites, Elaterocolpites, Elaterosporites, Elateroplicites, Senegalosporites, Sofrepites, Afropollis and Cretacaeiporites

Organic Geochemistry of the Lower Silurian Tanezzuft Formation and Biomarker Characteristics of Crude Oils from the Ghadames Basin, Libya

The Ghadames Basin of NW Libya contains more than 10 B brls oil-equivalent in Palaeozoic siliciclastic reservoirs which are charged by organic-rich ?hot shales? in the Lower Silurian (Rhuddanian) Tanezzuft Formation. Geochemical analysis of 85 shale samples and ten oils from three fields (NC2, NC4 and NC7) in the central and northern part of the basin provides a robust description of the Tanezzuft ? Mamuniyat/Acacus petroleum system in this region, and of the associated source facies and oil families. The shale samples underwent total organic carbon (TOC) analysis and Rock-Eval pyrolysis, and the ten crude oil samples were analysed by gas chromatography ? flame ionization detection (GC-FID) and GC-mass spectrometry (GC-MS) of the saturated and aromatic hydrocarbon fractions, accompanied by stable carbon isotopic analysis. Organic matter ranges from Type II to mixed Type II/III kerogen with varying oil and gas generation potential in the early to main stages of the oil generation window. The analysed oils are characterised by low sulphur, nickel and vanadium contents, and relatively high API gravity (34.9?46.8oAPI). Biomarkers suggest that they were generated from marine shales containing abundant Type II to mixed Type II/III kerogen deposited in mildly anoxic ? suboxic conditions with a dominance of C29 over C27 or C28 steranes, indicative of a source rich in brown algae and cyanobacteria. Their close stratigraphic association and biomarker characteristics support a Tanezzuft ?hot shales? source for the Mamuniyat and Acacus oils in the three fields. Maturity-related parameters based on terpanes, steranes, aromatic hydrocarbons and low molecular-weight hydrocarbons, suggest generation from marine shales in the early to peak oil-generation window. The ZE3-NC7, A19-NC7 and A20 NC7 oils from the NC7 oil field are significantly more mature than those from the NC2 and NC4 fields. This indicates a difference in expulsion timing and may be related to the presence of two ?hot shales? or to fault-triggered vertical migration preceding and during the NeogenePeer reviewe