Simultaneous contrast improvement and temporal compression using divided-pulse nonlinear compression.

We experimentally demonstrate how divided-pulse nonlinear compression can be used to improve the temporal contrast of a laser pulse train while simultaneously temporally compressing the pulses. We measure a contrast improvement of almost four orders of magnitude on a nanosecond time scale and temporally compress the pulses from 1.2 ps to 187 fs. The efficiency of our method is also competitive with other contrast improvement methods, with 72% efficiency measured for the main pulse. We expect the method will be useful in the continuing development of high-power, Yb regenerative amplifiers, which suffer from both significant prepulses and relatively long pulse durations.

Energy scaling beyond the gas ionization threshold with divided-pulse nonlinear compression.

We demonstrate how pulse energy in hollow-core fiber can be scaled beyond gas-ionization limitations using divided-pulse nonlinear compression. With one pulse, ionization limits our fiber's output pulse energy to 2.7 mJ at an input of 4 mJ. By dividing the pulse to four low-energy pulses before the fiber, we eliminated the ionization and scaled the pulse energy 2.5× to 6.6 mJ at an input energy of 10 mJ. Larger energy scaling is possible, as our maximum pulse energy has not reached the new gas ionization threshold. Our results motivate applying the method to state-of-the-art systems for large pulse energy scaling without prohibitive system size increases.

The role of adjuvant radiotherapy in locally advanced T4 mandible squamous cell carcinoma in the N0 patient: a single centre experience.

In locally advanced oral squamous cell carcinoma (OSCC), namely that showing invasion of the mandible, demonstrating no high-risk (e.g. extranodal extension, positive margin) or intermediate-risk histopathological features (e.g. perineural invasion, lymphovascular invasion), the additional benefit of postoperative radiotherapy (PORT) currently remains uncertain. A retrospective review covering the period between January 1, 2010 and December 31, 2019 was conducted to identify patients from a single UK centre with locally advanced invasive mandibular OSCC defined as pT4a, with no nodal or distant metastasis (N0 M0). The primary outcome was to determine the disease-free survival and overall survival rates in the surgery + PORT group, in comparison to the surgery only group. Twenty-eight eligible patients were identified, with 13 patients in the surgery + PORT group and 15 patients in the surgery only group. A single patient in the surgery + PORT group developed disease recurrence and subsequently died (1/13) (median follow-up 5.24 years, range 2.13-10.71 years). No patient in the surgery only group developed disease recurrence or died (0/15) (median follow-up 5.13 years, range 1.37-10.93 years). It may be reasonable to consider omitting PORT in pT4a pN0 M0 OSCC of the mandible in patients who demonstrate no high- or intermediate-risk histopathological features, following multidisciplinary team discussion.

Overcoming gas ionization limitations with divided-pulse nonlinear compression.

We simulate Kerr and plasma nonlinearities in a hollow-core fiber to show how plasma effects degrade the output pulse. Our simulations predict the plasma effects can be avoided entirely by implementing divided-pulse nonlinear compression. In divided-pulse nonlinear compression, a high-energy pulse is divided into multiple low-energy pulses, which are spectrally broadened in the hollow-core fiber and then recombined into a high-energy, spectrally broadened pulse. With the plasma effects overcome, spectral broadening can be scaled to larger broadening factors and higher pulse energies. We anticipate this method will also be useful to scale spectral broadening in gas-filled multipass cells.

Comparison of the piezoelectric cutter with a conventional cutting technique in orthognathic surgery.

The use of a piezoelectric cutter has been reported to improve outcomes in orthognathic surgery, particularly with regards to neurosensory disturbance of the inferior alveolar nerve. The aims of this retrospective longitudinal cohort study were to compare outcomes regarding neurosensory disturbance, and operating time. During two 15-month periods a single surgeon treated 24 consecutive patients with a conventional cutting technique and a further 24 consecutive patients with a piezoelectric cutter. In both groups the duration of operation was noted, and neurosensory disturbance graded at 12-month follow up. Neurosensory recovery was better in the piezoelectric group than in the conventional group (p=0.01), and the duration of operation nearly identical. We conclude that the piezoelectric cutter offers advantages with regards to neurosensory deficit over a more conventional technique without the previously-reported disadvantage of a longer operating time.

What is the role of the oral and maxillofacial department in the preoperative management of patients awaiting cardiac operations?

There is limited evidence and guidance on best practice regarding preoperative dental assessments of patients awaiting cardiac operations. To analyse current practice in oral and maxillofacial units across the United Kingdom, we did a telephone survey to find out how these patients are managed. All maxillofacial departments in the United Kingdom were contacted, with a response rate of 77%. Those attached to dental schools were excluded. Most departments did extractions only, and in many, patients were assessed and treated within 7 days of being referred, although this varied. Most units did not offer antibiotic prophylaxis to patients at high risk of infective endocarditis, but some did after advice had been sought from a cardiologist. Respondents in 76% thought that preoperative dental assessments for cardiac patients were an appropriate use of resources. We propose a more integrated pathway for the management of these patients (particularly considering the pressure on time for treatment) that focuses primary and secondary resources accordingly.

Reliability and validity of a new method of nurse-led assessment of trismus.

Our aim was to develop a way of measuring trismus and evaluating it in terms of reliability and validity for use by nurses who care for patients with head and neck cancer. We developed a method from existing resources and tested it for interoperator reliability and validity against a "gold standard". We showed that within the variables outlined, nursing staff could use it after minimal training to identify patients broadly as being "at risk", "low risk", or having "normal mouth opening". Interexaminer reliability was poor. There was a trend towards a group of people having reasonable interexaminer reliability, and this same group showed consistency towards the gold standard. Nurses' accuracy and consistency in using a simple method of assessing trismus depends on more than the method used, and neither validity nor reliability can be assumed. The accurate assessment of trismus for comparison across studies is complex, and future research must define exactly what method was used.

Changes in pain and mouth opening at 1 year following temporomandibular joint replacement--a prospective study.

We describe the outcome of 46 patients 12 months after partial or total replacement of the temporomandibular joint (TMJ) using the Christensen implant system (TMJ Implants Inc, Golden, CO, USA). The study group comprised 35 women and 11 men; the women were slightly older than the men at the time of operation. We studied three diagnostic groups in detail: patients who had ankylosis, internal derangement, and osteoarthritis. Those with ankylosis were slightly older than the others. Pain decreased over time in all three groups. There was a significant reduction between preoperative pain and that recorded 1 month postoperatively. After this point the pain decreased slowly, and by year 1 it had decreased significantly with respect to preoperative scores. Women reported worse preoperative pain than men, but not significantly so.

Lugol's iodine identifies synchronous invasive carcinoma--time for a clinical trial.

Lugol's iodine is currently under investigation as a technique to detect dysplasia, carcinoma in situ and invasive carcinoma at resection margins, plus further afield. Lugol's iodine is inexpensive and easy to use. We present two cases where the technique revealed abnormal mucosa (one carcinoma, one squamous cell carcinoma in situ) at distant sites from the tumour being treated within oral cavity and oropharynx.