whitlockite and octacalcium-phosphate

The purpose of this study was to evaluate the microtensile bond strength (microTBS) to human dentin of an experimental bonding agent containing calcium phosphates experimentally developed for direct pulp capping. Different concentrations of four types of calcium phosphates were added to an experimental bonding monomer, and six experimental bonding agents were thus prepared. Clearfil SE Bond/Bond was used as the control. Flat dentin surfaces of human molars were assigned to the experimental adhesive systems and the control. After Clearfil SE Bond/Primer was applied to the dentin surface, each experimental bonding agent was applied and photopolymerized, and then a resin composite paste was placed and photopolymerized. The specimens were subjected to microTBS testing. Results revealed that there were no significant differences among the microTBS values of the experimental bonding agents and the control. In other words, the calcium phosphate-containing experimental adhesives did not adversely affect the microTBS to dentin.

Topics: Adhesiveness; Calcium Phosphates; Composite Resins; Dental Bonding; Dental Pulp Capping; Dentin; Dentin-Bonding Agents; Durapatite; Humans; Materials Testing; Methacrylates; Microscopy, Electron, Scanning; Polymethacrylic Acids; Resin Cements; Stress, Mechanical; Surface Properties; Tensile Strength

The purpose of this paper was to describe the characteristics of salivary calculi and their relationship to epidemiological factors, through a cross-sectional study. We analysed 100 calculi obtained in 2017-2021. Patient data including age, time since onset of symptoms, gland involved, and site of location in the salivary system were studied. The calculi were studied to determine their morphological features using scanning electron microscopy and energy dispersive plain radiographic analysis. Most of the calculi had formed in the submandibular gland (SG) (82%). The mean age of patients at onset was 45.83 years; patients presenting parotid gland (PG) stones were somewhat older (p = 0.031). The mean time since the onset of symptoms was longer in PG calculi (p = 0.038). The most common lithiasis site was the main duct (74%), followed by the hilum (22%). Hilar stones were the largest (p < 0.05) and heaviest (p = 0.028). Octacalcium phosphate (OCP) was the most common crystalline phase (Cp) founded, followed by hydroxyapatite (HA) and whitlockite (WH). Specifically, OCP had a higher presence in PG calculi (p = 0.029) and WH was the most common phase in SG calculi (p = 0.017). The most prevalent site of lithiasis was the main duct, and the largest and heaviest calculi were found in the SG. PG stones were associated with a longer history of symptoms and older age. OCP was the most frequent Cp of the calculi studied, and the main Cp in PG stones. WH was the predominant Cp in SG stones. The Cp of the calculi was not influenced by location, patient age, or time of symptoms.

Topics: Cross-Sectional Studies; Endoscopy; Humans; Lithiasis; Middle Aged; Retrospective Studies; Salivary Duct Calculi; Salivary Gland Calculi

Through a correlative analytical approach encompassing backscattered electron scanning electron microscopy (BSE-SEM), energy dispersive X-ray spectroscopy (EDX), and micro-Raman spectroscopy, the composition of the mineralized biofilm around a dental implant, retrieved due to peri-implantitis, was investigated. The mineralized biofilm contains two morphologically distinct regions: (i) bacteria-containing zones (Bact+), characterized by aggregations of unmineralized and mineralized bacteria, and intermicrobial mineralization, and (ii) bacteria-free zones (Bact-), comprised mainly of randomly oriented mineral platelets. Intramicrobial mineralization, within Bact+, appears as smooth, solid mineral deposits resembling the morphologies of dental plaque bacteria. Bact- is associated with micrometer-sized Mg-rich mineral nodules. The Ca/P ratio of Bact+ is higher than Bact-. The inorganic phase of Bact+ is carbonated apatite (CHAp), while that of Bact- is predominantly octacalcium phosphate (OCP) and whitlockite (WL) inclusions. Compared with native bone, the inorganic phase of Bact+ (i.e., CHAp) exhibits higher mineral crystallinity, lower carbonate content, and lower Ca/P, C/Ca, Mg/Ca, and Mg/P ratios. The various CaPs found within the mineralized dental biofilm (CHAp, OCP, and WL) are related to the local presence/absence of bacteria. In combination with BSE-SEM and EDX, micro-Raman spectroscopy is a valuable analytical tool for nondestructive investigation of mineralized dental biofilm composition and development.

Topics: Aged; Apatites; Bacteria; Biofilms; Calcium Phosphates; Crystallization; Dental Calculus; Dental Implants; Dental Plaque; Female; Humans; Microscopy, Electron, Scanning; Minerals; Peri-Implantitis; Spectrometry, X-Ray Emission; Spectrum Analysis, Raman

Five samples of powered enamel were each sequentially equilibrated 5 times at 37 degrees C with either 4 or 17 mmol/l H3PO4, in contact with air, and the ionic activity product for hydroxyapatite (IHA) estimated. There was evidence for preferential release of Mg and Na, especially in the first equilibrations. In two experiments, raised values of IHA were observed in the first equilibration but otherwise IHA was reasonable constant within experimental error and was much closer to the solubility product of hydroxyapatite than many previous estimates, mainly at 25 degrees C, suggest. The mean value of IHA for the majority fraction, averaged over all samples, was 1.7 (+/- 0.7) x 10(-58). Non-apatitic solids formed in all systems but solubility appeared nevertheless to be controlled by an apatitic phase: either the enamel mineral itself or apatite reprecipitated during the course of equilibration. High values of IHA reported previously may be due to use of conditions favouring dissolution only of more soluble factions or to metastability artifacts associated with control of solubility by non-apatitic phases.

Topics: Calcium; Calcium Phosphates; Carbonates; Dental Enamel; Dental Enamel Solubility; Durapatite; Fluorides; Humans; Magnesium; Particle Size; Phosphoric Acids; Phosphorus; Sodium; Temperature

All biological calcium phosphates form in various neutral aqueous solutions containing [CaCl2] = 1 or 3 mM, [MgCl2] = 0-9 mM, [Na2HPO4] = 0.1-90 mM and NaCl (total 300 mosM) kept quiescently at 37 degrees C for 21 days. In all solutions containing 1 mM Ca and in solutions with [Ca] = 3 mM and [PO4] less than 10 mM, heterogeneous nucleation of octa-calcium phosphate (for Mg/Ca less than or equal to 1) or brushite (for Mg/Ca greater than 1) was observed; the former transforming to apatite with time. In contrast, homogeneous nucleation of an unstable amorphous calcium magnesium phosphate occurred in solutions with [Ca] = 3 mM and [PO4] greater than or equal to 10 mM, transforming to apatite, to brushite, and to whitlockite (and newberyite) depending on Mg/Ca and [PO4] values.

Topics: Apatites; Calcium Phosphates; Chemical Precipitation; Crystallization; Durapatite; Hydrogen-Ion Concentration; Hydroxyapatites; Magnesium; Magnesium Compounds; Phosphates; Solutions; X-Ray Diffraction

Selected area electron diffraction of sections and individual crystal fragments of human dental calculus has demonstrated that octacalcium phosphate, hydroxyapatite and whitlockite form the inorganic part of both supragingival and subgingival dental calculus. However, the major constituents in supragingival calculus are platelet-shaped crystals of octacalcium phosphate and needle-shaped crystals of hydroxyapatite, while bulk crystals of whitlockite is the predominant component in subgingival calculus. The subgingival samples seemed to be better crystallized than the supragingival ones. The results obtained by the electron optical and X-ray powder investigations are in good agreement.

Topics: Calcium Phosphates; Crystallization; Crystallography; Dental Calculus; Durapatite; Gingiva; Humans; Hydroxyapatites; Microscopy, Electron; X-Ray Diffraction

Topics: Animals; Apatites; Calcium Phosphates; Chemical Phenomena; Chemistry, Physical; Dental Calculus; Dental Plaque; Humans; Mammals; Saliva