Ion Release and Surface Changes of Nickel-Titanium Archwires Induced by Changes in the pH Value of the Saliva-Significance for Human Health Risk Assessment.

The aim of this study was to explore whether changes in the salivary pH influence mechanical properties, surface roughness, and ion release from NiTi archwires with various surface coatings, and discuss the clinical significance of the findings. The uncoated, rhodium-coated, and nitrified NiTi wires were immersed into artificial saliva of different pH values (4.8, 5.1, 5.5, and 6.6). Released nickel and titanium ions were measured with inductively coupled plasma-optical emission spectroscopy at the end of 28 days. Atomic force microscopy was used to measure the arithmetic average surface roughness Ra, the root-mean-square roughness Rq, and the maximum height of the asperities RZ. The nanoindentation hardness (HIT) and Young's modulus (EIT) measurements were performed. The change in the pH of artificial saliva is inversely proportional to the release of titanium from both coated and uncoated wires, and the release of nickel from uncoated wires. The surface roughness parameters of both coated and uncoated wires are unaffected by the change in the pH of artificial saliva. The change in the pH of saliva has minor influence on the hardness and Young's modulus of elasticity of both coated and uncoated wires. The concentration of released metal ions measured was below the recommended upper limit for daily intake; nevertheless, hypersensitivity effects cannot be excluded, even at lower concentrations and at low pH.

Cluster headache: Is age of onset important for clinical presentation?

BACKGROUND: The age of onset of cluster headache (CH) attacks most commonly is between 20 and 40 years old, although CH has been reported in all age groups. There is increasing evidence of CH with early or late onset and a different course of the disorder. The aim of the study was to analyze the influence of the age of onset on clinical features, disorder course, and therapy effectiveness in CH patients. METHODS: A retrospective and cross-sectional analysis was performed on 182 CH patients divided into three groups according to the age of onset. The first group consisted of patients with the first CH attack before 20 years of age, the second group was patients with age of onset between 20 and 40 years of age, and the third group was patients with age of onset after 40 years of age. Demographic data, features of CH periods and attacks, and the response to standardized treatment were compared among the groups. RESULTS: Patients with CH onset after 40 years of age reported a lower number of autonomic features and less frequently had conjunctival injection and nasal congestion/rhinorrhea phenomena during their attacks. Diagnostic delay was the longest in the patients with CH onset before 20 years of age. CONCLUSION: The influence of the age of onset of CH is intriguing for further studies and could possibly extend the knowledge about CH pathophysiology. From a clinical point of view, the differences in CH presentation are insufficient to preclude a correct diagnosis and treatment because the same criteria could be applied regardless of patient age.