Ultrasound stimulation of mandibular bone defect healing

The conclusions of the experimental work presented in this thesis are: 1. Low intensity pulsed ultrasound is not effective in stimulating bone growth into a rat mandibular defect, either with or without the use of osteoconductive membranes. 2. Low intensity pulsed ultrasound does not seem to have an effect on the early bone formation in the vertically distracted, severely resorbed mandible. This thesis focused on a small area in the field of ultrasound and bone healing that had not been explored before. The animal experimental work indicates that ultrasound does not stimulate mandibular bone defect healing with or without the use of osteoconductive membranes in healthy animals. This may be related to the ultrasound field variables used, to an optimal healing tendency of the head and neck region, or to limitations of the animal model. To reveal which of these possibilities is the most plausible, additional research is needed. For now, it is not recommendable to apply ultrasound in maxillofacial surgery to stimulate bone defect healing. In situations where mechanical loading or blood perfusion is limited, as for example in the case of mandibular fractures or osteoradionecrosis, ultrasound might have an effect. More importantly, unravelling the mechanism of action as to how ultrasound stimulates bone healing in certain cases may eventually predict if, and if so, when, ultrasound may be of value in maxillofacial surgery.

Randomized Trial on the Effectiveness of Dexamethasone in TMJ Arthrocentesis

The aim of this study was to compare the effectiveness of dexamethasone administration following arthrocentesis of the temporomandibular joint (TMJ) with a placebo (saline). Twenty-eight participants with TMJ arthralgia were randomly assigned to two groups of a parallel double-blind RCT. In both groups, an arthrocentesis procedure was carried out. In one group, the procedure was followed by the administration of a single-dose intra-articular dexamethasone. In the other group, saline was administered as a control. Follow-up visits were scheduled after 1, 3, and 24 weeks. During each visit, TMJ pain (on a 100-mm VAS) and jaw stiffness (mouth opening in mm) were scored. In the statistical analysis, generalized estimating equation (GEE) models showed no differences between the two study groups, although pain and jaw stiffness were both reduced over 24 weeks. In conclusion, intra-articular dexamethasone following arthrocentesis did not improve the procedure's effect in patients presenting with TMJ arthralgia (ClinicalTrials.gov number CT01275014)

Counterexamples to the discrete and continuous weighted Weiss conjectures

Counterexamples are presented to weighted forms of the Weiss conjecture in discrete and continuous time. In particular, for certain ranges of $\alpha$, operators are constructed that satisfy a given resolvent estimate, but fail to be $\alpha$-admissible. For $\alpha \in (-1,0)$ the operators constructed are normal, while for $\alpha \in (0,1)$ the operator is the unilateral shift on the Hardy space $H^2(\mathbb{D})$.Comment: 16 page