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

Canine retraction rate and angulation with 0.017”X0.025” versus 0.016”X0.022” stainless steel arch wire with a power arm

Background: The dimensions of the arch wire affect its stiffness and the play between the wire and bracket. Canine retraction over stiffer arch wires limits the degree of canine tipping. However, the greater the wire dimensions, the greater the resistance to sliding. Frictional resistance is known to delay tooth movement. Aim: The aim of this controlled clinical trial was to compare canine retraction rate and angulation with 0.017”X0.025” versus 0.016”X0.022” stainless steel arch wire with a power arm. Materials and Methods: Twenty-four Class II malocclusion patients (age 13.8± 2.6 years) participated in this study. The teeth were leveled and aligned. Bilateral maxillary first premolars were extracted. In group A, the canines were retracted over 0.017”X0.025” wires. In group B, they were retracted using 0.016”X0.022” wires with a vertical power arm. The retraction force was 150g generated by elastomeric chains. The canine retraction rate and angulation were measured at the end of six months. The rates in the two groups were compared with the t-test and the angulation with the Mann Whitney test. Results: canine retraction rate was 4.64±1.5 in group A and 5.24±1.45 in group B. The canine angulation was 6.41±5.14 and 6.73±6.0 for group A and B, respectively. Conclusion: No difference was observed in the canine retraction rate or angulation with 0.017”X0.025” versus 0.016”X0.022” stainless steel arch wire with a power arm