Dental Factors Influencing Treatment Choice For Maxillary Lateral Incisor Agenesis: A Retrospective Study

OBJECTIVES

Maxillary Lateral Incisor Agenesis (MLIA) pose significant orthodontic and restorative challenges. The aim of this study was to evaluate dental factors and their effect on decision making for MLIA.

METHODS

This is a retrospective study of patients who attended the Edinburgh Dental Institute between 2007 and 2016. Patients with unilateral or bilateral MLIA were included. Excusion criteria: inadequate pre-treatment records, hypodontia of additional teeth as well as MLIA, a craniofacial syndrome, previous orthodontic treatment. Archived records were used to record relevant dental features and treatment decisions. The independent variables were age, gender, overjet, molar relationship, space availability for lateral incisors, and canine aesthetics. The dependent variable was treatment outcome (orthodontic space opening or closing). Multiple regression models were used to identify predictors of treatment outcome.

RESULTS

44 patients were included in the study (30 female and 14 male). Mean age was 13.7 (SD 2.3) years. Fifteen patients (34.1%) had space closure and 29 patients (65.9%) received space opening. Space availability was the only significant predictor of treatment outcome within the regression model (p=0.02).

CONCLUSIONS

Presence of adequate space in the maxillary arch is associated with orthodontic space opening for MLIA.

Measurement of the spin temperature of optically cooled nuclei and GaAs hyperfine constants in GaAs/AlGaAs quantum dots

Deep cooling of electron and nuclear spins is equivalent to achieving polarization degrees close to 100% and is a key requirement in solid-state quantum information technologies. While polarization of individual nuclear spins in diamond and SiC (ref. ) reaches 99% and beyond, it has been limited to 50-65% for the nuclei in quantum dots. Theoretical models have attributed this limit to formation of coherent 'dark' nuclear spin states but experimental verification is lacking, especially due to the poor accuracy of polarization degree measurements. Here we measure the nuclear polarization in GaAs/AlGaAs quantum dots with high accuracy using a new approach enabled by manipulation of the nuclear spin states with radiofrequency pulses. Polarizations up to 80% are observed-the highest reported so far for optical cooling in quantum dots. This value is still not limited by nuclear coherence effects. Instead we find that optically cooled nuclei are well described within a classical spin temperature framework. Our findings unlock a route for further progress towards quantum dot electron spin qubits where deep cooling of the mesoscopic nuclear spin ensemble is used to achieve long qubit coherence. Moreover, GaAs hyperfine material constants are measured here experimentally for the first time.

A multicentre audit of GDPs knowledge of orthodontic retention

OBJECTIVE

To determine GDP knowledge and willingness to supervise orthodontic retention and provide replacements retainers.

DESIGN

An audit sampling GDPs from six centres within England (Bradford, Cambridge, Burton-Upon-Trent, Croyden, Norwich and Plymouth). A gold standard of 100% of GDPs should be aware of commonly used retainers and be able to provide replacements was selected.

METHOD

Overall, 1,053 postal questionnaires were sent to local GDPs. The questions covered knowledge and provision of various retainers, practitioner background and education. GDP satisfaction with the information provided by the orthodontist at discharge was also explored.

RESULTS

Five hundred and two questionnaires were received (response rate of 48%). The majority of GDPs (64%) were trained in the UK. Awareness of vacuum-formed, Hawley and fixed retainers was generally high. A significantly smaller number of GDPs were willing to prescribe, fit or review the retainers. The most common reasons for reluctance in provision were insufficient knowledge, financial and time constraints. Over two thirds (72%) of GDPs would like further training on retention.

CONCLUSION

This audit highlights a need for increased training at undergraduate and postgraduate levels to update practitioners about contemporary retention practice. Better communication is required from orthodontists to GDPs to ensure that on discharge the dentist is aware of the retainer type and retention regime.

Mollow quintuplets from coherently excited quantum dots

Charge-neutral excitons in semiconductor quantum dots (QDs) have a small finite energy separation caused by the anisotropic exchange splitting. Coherent excitation of neutral excitons will generally excite both exciton components, unless the excitation is parallel to one of the dipole axes. We present a polaron master equation model to describe two-exciton pumping using a coherent continuous wave pump field in the presence of a realistic anisotropic exchange splitting. We predict a five-peak incoherent spectrum, namely a Mollow quintuplet under general excitation conditions. We experimentally confirm such spectral quintuplets for In(Ga)As QDs and obtain very good agreement with theory.

Venous air embolism during the use of a Nd YAG laser

We report a case of a 47-year-old female who suffered a cardiac arrest during sub-mucosal diathermy of the inferior turbinate using a Nd YAG laser. The possible causes of the cardiac arrest are discussed. Venous air embolism due to Nd YAG laser was thought to be the most likely cause in this case. Although venous air embolism has previously been reported during nasal sinus surgery and choanal atresia when using a Nd YAG laser, the occurrence of this complication during a relatively minor surgical procedure has not previously been reported. It is important, therefore, to raise the awareness of this life threatening complication during use of a Nd YAG laser regardless of the duration of surgery. We recommend the use of appropriate methods and techniques to avoid this life threatening complication during the use of Nd YAG laser even for relatively short procedures.

Atypical migraine presenting with meningeal signs

A case of atypical or complicated migraine is presented with signs and symptoms of meningeal irritation, projectile emesis NS obtundation, and unresponsiveness. The patient is a 19-year-old diabetic on insulin who had a mild episode of upper respiratory tract symptoms with severe headache and was found unresponsive and brought to the emergency department. After a work-up for meningitis was negative (as well as computerized tomography and magnetic resonance imaging) he recovered totally in 3 days with no residual signs or symptoms and was discharged from the hospital.