Revitalisation endodontic treatment of traumatised immature teeth: a prospective long-term clinical study

Purpose Continuation of root development following revitalisation endodontics (RET) has been shown to be unpredictable with lower success rates in traumatised teeth. This study reports the outcomes for RET in traumatised teeth over a review period of 4 years. Methods A prospective uncontrolled study, where RET was performed on traumatised upper immature anterior teeth with necrotic pulps in 15 children (mean age = 8.3 years), was conducted. Patients were reviewed at 3, 9, 12, 24, and 48 months, where clinical and radiographic assessments were performed. At the last review appointment, patients and parents answered questions assessing their perception and acceptance of tooth colour change over time. McNemar’s Exact test and linear mixed model assessment were used to assess changes in pulpal electrical response and radiographic evidence of continuation of root development over time, respectively. Results There was 83.3% healing with no significant changes in EPT responses, and no significant changes in root lengths, while significant changes in root widths (p < 0.05) and root apex widths (p < 0.001) were found over time. Twenty-five percent of patients and 33% of parents felt that there were changes in tooth colour following RET over time. Conclusion Within the limitations of this study, traumatised teeth treated using RET showed no significant root lengthening, however, acceptable periapical healing, slow thickening of root dentinal walls, and rapid development of apical closure were evident over a period of 43 months. Using Portland cement and omitting minocycline, did not eliminate crown colour change following RET

Conformal Ricci collineations of static spherically symmetric spacetimes

Conformal Ricci collineations of static spherically symmetric spacetimes are studied. The general form of the vector fields generating conformal Ricci collineations is found when the Ricci tensor is non-degenerate, in which case the number of independent conformal Ricci collineations is \emph{fifteen}; the maximum number for 4-dimensional manifolds. In the degenerate case it is found that the static spherically symmetric spacetimes always have an infinite number of conformal Ricci collineations. Some examples are provided which admit non-trivial conformal Ricci collineations, and perfect fluid source of the matter

Spacelike Ricci Inheritance Vectors in a Model of String Cloud and String Fluid Stress Tensor

We study the consequences of the existence of spacelike Ricci inheritance vectors (SpRIVs) parallel to $x^a$ for model of string cloud and string fluid stress tensor in the context of general relativity. Necessary and sufficient conditions are derived for a spacetime with a model of string cloud and string fluid stress tensor to admit a SpRIV and a SpRIV which is also a spacelike conformal Killing vector (SpCKV). Also, some results are obtained.Comment: 11 page

Competing mechanisms and scaling laws for carbon nanotube scission by ultrasonication

Dispersion of carbon nanotubes (CNTs) into liquids typically requires ultrasonication to exfoliate individuals CNTs from bundles. Experiments show that CNT length drops with sonication time (or energy) as a power law t?m. Yet the breakage mechanism is not well understood, and the experimentally reported power law exponent m ranges from approximately 0.2 to 0.5. Here we simulate the motion of CNTs around cavitating bubbles by coupling Brownian dynamics with the Rayleigh-Plesset equation. We observe that, during bubble growth, CNTs align tangentially to the bubble surface. Surprisingly, we find two dynamical regimes during the collapse: shorter CNTs align radially, longer ones buckle.We compute the phase diagram for CNT collapse dynamics as a function of CNT length, stiffness, and initial distance from the bubble nuclei and determine the transition from aligning to buckling. We conclude that, depending on their length, CNTs can break due to either buckling or stretching. These two mechanisms yield different power laws for the length decay (0.25 and 0.5, respectively), reconciling the apparent discrepancy in the experimental data

On global models for isolated rotating axisymmetric charged bodies; uniqueness of the exterior field

A relatively recent study by Mars and Senovilla provided us with a uniqueness result for the exterior vacuum gravitational field generated by an isolated distribution of matter in axial rotation in equilibrium in General Relativity. The generalisation to exterior electrovacuum gravitational fields, to include charged rotating objects, is presented here.Comment: LaTeX, 21 pages, uses iopart styl

Effectiveness, Costs and Patient Acceptance of a Conventional and a Biological Treatment Approach for Carious Primary Teeth in Children

BACKGROUND: Over the last years, conventional restorations for the treatment of active carious lesions (CL) in primary teeth have been challenged and a more biological approach has been suggested. This approach involves less invasive techniques that alter the environment of the CL isolating it from the cariogenic biofilm and substrate. AIM: To investigate the cost-effectiveness and patient acceptance of 2 treatment approaches for the treatment of deep CLs in primary teeth in children. METHODS: This was a retrospective/prospective cohort study carried out in 2 UK specialist hospital settings. Data on cost-effectiveness was extracted retrospectively from clinical dental records of 246 patients aged 4-9 years. A prospective study design was used to explore patient acceptance of the 2 treatment approaches. One hundred and ten patients aged 4-9 years and their carers completed 2 questionnaires on treatment acceptance. RESULTS: In total, 836 primary teeth that had received treatment with either approach were included. More than 2 thirds (75.7%) of the restorations in the conventional approach were of non-selective removal to hard dentine followed by pulpotomy (24.3%). In the biological approach, most of the restorations were stainless steel crowns placed with the Hall Technique (95%) followed by selective removal to firm dentine (5%). The majority of the primary teeth remained asymptomatic after a follow-up period of up to 77 months; 95.3% in the conventional and 95.8% in the biological arm. When the treatment costs were analysed, a statistically significant difference was found between the mean costs of the 2 approaches with a mean difference of GBP 45.20 (Pound Sterling; p < 0.001), in favour of the biological approach. The majority of the children and carers were happy with the conventional or biological restorations. CONCLUSION: Although both approaches had similar successful outcomes, the biological approach consisting mainly of Hall Technique was associated with reduced treatment costs. Both approaches were accepted favourably by the children and carers