The mechanical stimuli generated by orthodontic forces cause deformation of extracellular matrices and cells, vascular changes, inflammation, and the release of active biological agents generating a complex multifactorial sequence of biological events culminating in bone remodelling enabling orthodontic tooth movement. Orthodontic forces on the teeth generate stresses in periodontal tissues according to a number of variables including the type (continuous, interrupted, or intermittent), magnitude, direction, and frequency of the applied load. Whether the strain is compressive or tensile determines whether bone deposition or bone resorption will occur. The mechanically induced strains mediate structural changes in extracellular matrices and in cells, consequently affecting cellular gene expression and function. In the extracellular matrix, mechanosensing molecules integrated into the structure of various proteins can be activated upon load-induced protein unfolding. These specialized molecules have the capacity to sense and then to convert microenvironmental biomechanical stimuli into intracellular biochemical signals that interact to generate a coordinated tissue response. It is also possible that the applied force may directly cause nuclear deformation with configurational changes in chromatin, thus influencing gene expression. In this review article we summarize the current general concepts of mechanotransduction influencing the remodelling of periodontal tissues thus enabling tooth movement in response to applied orthodontic loads.

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Background:Autonomic dysfunction, commonly seen in patients with cervical myelopathy, may lead to a decrease in blood pressure intraoperatively.Objective:The aim of our study is to determine if changes in Heart rate variability (HRV) could predict hypotension after induction of anesthesia in patients with cervical myelopathy undergoing spine surgery.Methods and Material:In this prospective observational study, 47 patients with cervical myelopathy were included. Five-minute resting ECG (5 lead) was recorded preoperatively and HRV of very low frequency (VLF), low frequency (LF), and high frequency (HF) spectra were calculated using frequency domain analysis. Incidence of hypotension (MAP <80 mmHg, lasting >5 min) and the number of interventions (40 mcg of phenylephrine or 5 mg of ephedrine) required to treat the hypotension during the period from induction to surgical incision were recorded. HRV indices were compared between the hypotension group and the stable group.Results:The incidence of hypotension after induction was 74.4% (35/47) and the median (IQR) interventions needed to treat hypotension was 2 (0.5–6). Patients who experienced hypotension had lower HF power and higher LF–HF ratios. A LF/HF >2.5 indicated postinduction hypotension likely. There was a correlation between increasing LF–HF ratio and the number of interventions that needs to maintain the MAP above 80 mmHg.Conclusion:HF power was lower and LF-HF ratio was higher in patients with cervical myelopathy who developed postinduction hypotension. Hence, preoperative HRV analysis can be useful to identify patients with cervical myelopathy who are at risk of post-induction hypotension.

Dandy-Walker Syndrome (DWS) is a rare congenital brain anomaly affecting the cerebellum and the fourth ventricle. The chief components of the syndrome include cystic dilatation of the fourth ventricle and agenesis or hypoplasia of the cerebellar vermis. These abnormalities are typically associated with hydrocephalus. Patients often present in infancy for cerebrospinal fluid shunt procedures. Anaesthetic concerns include those related to other frequently associated congenital abnormalities. Airway management requires particular attention. The limited literature on this subject suggests that these patients require postoperative intensive care admission. This is not always possible in the resource-limited environment. This case report describes the successful anaesthetic management of an infant with Dandy-Walker Syndrome without postoperative intensive care admission.