David J. Lewis

Effectiveness of early orthodontic treatment with the Twin-block appliance: a multicenter, randomized, controlled trial. Part 1: Dental and skeletal effects.

This study evaluated the effectiveness of early orthodontic treatment with the Twin-block appliance for the developing Class II Division 1 malocclusion. This multicenter trial was carried out in the United Kingdom. A total of 174 children, aged 8 to 10 years old, with Class II Division 1 malocclusion were randomly allocated to receive treatment with a Twin-block appliance or to an untreated, control group. Data were collected at the start of the study and 15 months later. Results showed that early treatment with Twin-block appliances resulted in reduction of overjet, correction of molar relationships, and reduction in severity of malocclusion. Most of this correction was due to dentoalveolar change, but some was due to favorable skeletal change. Early treatment with the Twin-block appliance is effective in reducing overjet and severity of malocclusion. The small change in the skeletal relationship might not be considered clinically significant.

Effectiveness of treatment for Class II malocclusion with the Herbst or twin-block appliances: a randomized, controlled trial.

The aim of this study was to evaluate the effectiveness of Herbst and Twin-block appliances for established Class II Division I malocclusion. The study was a multicenter, randomized clinical trial carried out in orthodontic departments in the United Kingdom. A total of 215 patients (aged 11-14 years) were randomized to receive treatment with either the Herbst or the Twin-block appliance. Treatment with the Herbst appliance resulted in a lower failure-to-complete rate for the functional appliance phase of treatment (12.9%) than did treatment with Twin-block (33.6%). There were no differences in treatment time between appliances, but significantly more appointments (3) were needed for repair of the Herbst appliance than for the Twin-block. There were no differences in skeletal and dental changes between the appliances; however, the final occlusal result and skeletal discrepancy were better for girls than for boys. Because of the high cooperation rates of patients using it, the Herbst appliance could be the appliance of choice for treating adolescents with Class II Division 1 malocclusion. The trade-off for use of the Herbst is more appointments for appliance repair.

Early treatment for Class II Division 1 malocclusion with the Twin-block appliance: a multi-center, randomized, controlled trial.

INTRODUCTION The aim of this study was to evaluate the effectiveness of early orthodontic treatment with the Twin-block appliance for the treatment of Class II Division 1 malocclusion. This was a multi-center, randomized, controlled trial with subjects from 14 orthodontic clinics in the United Kingdom. METHODS The study included 174 children aged 8 to 10 years with Class II Division 1 malocclusion; they were randomly allocated to receive treatment with a Twin-block appliance or to an initially untreated control group. The subjects were then followed until all orthodontic treatment was completed. Final skeletal pattern, number of attendances, duration of orthodontic treatment, extraction rate, cost of treatment, and the childs self-concept were considered. RESULTS At the end of the 10-year study, 141 patients either completed treatment or accepted their occlusion. Data analysis showed that there was no differences between those who received early Twin-block treatment and those who had 1 course of treatment in adolescence with respect to skeletal pattern, extraction rate, and self-esteem. Those who had early treatment had more attendances, received treatment for longer times, and incurred more costs than the adolescent treatment group. They also had significantly poorer final dental occlusion. CONCLUSIONS Twin-block treatment when a child is 8 to 9 years old has no advantages over treatment started at an average age of 12.4 years. However, the cost of early treatment to the patient in terms of attendances and length of appliance wear is increased.

Tin(II) Sulfide (SnS) Nanosheets by Liquid-Phase Exfoliation of Herzenbergite: IV–VI Main Group Two-Dimensional Atomic Crystals

The liquid-phase exfoliation of tin(II) sulfide to produce SnS nanosheets in N-methyl-2-pyrrolidone is reported. The material is characterized by Raman spectroscopy, atomic force microscopy, lattice-resolution scanning transmission electron microscope imaging, and energy dispersive X-ray spectrum imaging. Quantum chemical calculations on the optoelectronic characteristics of bulk and 10-layer down to monolayer SnS have been performed using a quantum chemical density functional tight-binding approach. The optical properties of the SnS and centrifugally fractionated SnS nanosheet dispersions were compared to that predicted by theory. Through centrifugation, bilayer SnS nanosheets can be produced size-selectively. The scalable solution processing of semiconductor SnS nanosheets is the key to their commercial exploitation and is potentially an important step toward the realization of a future electronics industry based on two-dimensional materials.

Ambient pressure aerosol-assisted chemical vapour deposition of (CH3NH3)PbBr3, an inorganic–organic perovskite important in photovoltaics

The inorganic-organic perovskite (CH3NH3)PbBr3, which is potentially important in photovoltaics, has been deposited using aerosol-assisted chemical vapour deposition (AACVD).

Routes to tin chalcogenide materials as thin films or nanoparticles: a potentially important class of semiconductor for sustainable solar energy conversion

Thin films of tin chalcogenides may find use in photovoltaic devices, and nanocrystals of such materials are attractive due to their tuneable band gaps and potential in photovoltaic, photonic and optoelectronic applications. Tin(II) sulfide (SnS) is of particular interest due to its band gap of 1.4 eV, which is similar to that of silicon (1.1 eV). This review seeks to provide an overview of the chemical routes currently known for the synthesis of tin chalcogenides as thin films or in nanocrystalline form, as well as exploring routes to copper zinc tin sulfide (CZTS) and mesoporous tin chalcogenides.

Luminescent nanobeads: attachment of surface reactive Eu(III) complexes to gold nanoparticles.

Gold nanoparticles were used as a scaffold to assemble multiple tailor-made europium(III) complexes yielding water-soluble gold nanoparticles that display red, Eu(III), luminescence.

Intracellular synchrotron nanoimaging and DNA damage/genotoxicity screening of novel lanthanide-coated nanovectors

AIMS In cancer therapy, research has focused on the development of nanocarriers that can aid diagnosis, deliver therapeutic agents and monitor treatment progress. This study introduces high-resolution synchrotron x-ray fluorescence microscopy (SR-XFM) to investigate intracellular localization of novel lanthanide-coated nanoparticles in human cells and their genotoxicity screening after internalization. MATERIALS & METHODS Noble metal nanoparticles coated with cerium and luminescent europium complexes have been developed as platforms for bioimaging and potential biodelivery applications. The intracellular distribution after internalization has been analyzed by ultrasensitive SR-XFM and genotoxicity evaluated using γ-H2AX DNA damage foci phosphorylation assay. RESULTS We demonstrate the unprecedented capability of SR-XFM for extremely sensitive nanoimaging and intracellular elemental distribution analysis of noble metal nanoparticles in cells. Furthermore, we show that, depending on the charge of the coating complex and the presence of the DNA cargo, the internalization of functionalized nanoparticles by human fibroblasts can cause elevated levels of DNA damage detected by histone H2AX phosphorylation. CONCLUSION The variable genotoxic impact of newly designed nanovectors emphasizes the need for careful and comprehensive testing of biological responses of all new nanoconstructs intended for future clinical applications. This can be greatly facilitated by SR-XFM nanoimaging of nanoparticles in cells at very low concentrations.

Prospective, multi-center study of the effectiveness of orthodontic/orthognathic surgery care in the United Kingdom

INTRODUCTION The aim of this study was to evaluate the effectiveness of orthodontic/orthognathic surgical care provided in the North West region of England. It was an observational, prospective cohort study at 13 maxillofacial clinics in the United Kingdom. METHODS The 131 patients comprised 47 males (35.9%) and 84 females (64.1%), with an average age of 22.6 years. They received orthodontic/orthognathic treatment according to the normal protocols of the operators. They were then followed until all orthodontic treatment was completed. Final skeletal pattern, final peer assessment rating score, number of attendances, and duration of treatment were recorded. RESULTS At the end of the 5-year study, 94 patients had completed treatment, and 71 had complete data. Data analysis showed that, overall, the treatments provided were effective in terms of skeletal and dental occlusal outcomes; the final mean peer assessment rating score was 10.58. However, treatment duration was longer than commonly expected, with a mean length of 32.8 months (SD,11.3). The outcome of treatment was influenced by only pretreatment skeletal discrepancy. CONCLUSIONS This prospective investigation showed that orthodontic/orthognathic surgical care was effective. The outcome of treatment was influenced only by the severity of the pretreatment skeletal discrepancy.

Early treatment for Class II malocclusion and perceived improvements in facial profile

INTRODUCTION The aims of this study were to assess whether early Twin-block appliance treatment improves the attractiveness of Class II profiles and to determine the orofacial features of a profile that most influence the perception of attractiveness. METHODS Silhouetted profiles of 20 treated patients and 20 untreated controls randomly selected from 174 subjects (ages, 8-10 years) of a randomized, controlled trial into the effectiveness of early Class II treatment were assessed by 30 children (ages, 10-11 years) and 24 teaching staff using a 5-point Likert scale. Independent samples t tests were used to compare attractiveness ratings between the treated and untreated groups. Linear regression was used to determine the features defining attractiveness. RESULTS Early orthodontic treatment resulted in improved perceptions of facial profile attractiveness. Profiles were likely to be rated as attractive if the overjet was smaller (P = 0.001) and no teeth showed (P <0.05). CONCLUSIONS Profile silhouettes of children who had received early orthodontic treatment for Class II malocclusion were perceived to be more attractive by peers than those of children who did not receive treatment.