Apatite formation on dental ceramics modified by a bioactive glass

Abstract

Restorative dental materials are considered biocompatible without exhibiting any bioactive behaviour. The aim of this study was the investigation of surface structure changes on conventional dental ceramics used in metal-ceramic restorations modified by a bioactive glass, after immersion in SBF for various time periods. Bioactive glass powder was mixed with porcelain powder with three different weight ratios: 1:1, 1:2, and 2:1. The two powders were mixed with porcelain modelling liquid and the mixture was transferred and spread on the surface of pre-fabricated ceramic disks. Coated ceramic specimens after being exposed to a specific thermal cycle as it is recommended for dental ceramics were soaked in Simulated Body Fluid (SBF) at 37 degrees C for various periods of time. After soaking, specimens were studied using Fourier Transform Infrared Spectroscopy (FTIR), Scanning Electron Microscopy (SEM) and Energy Dispersive Spectroscopy (EDS). Results revealed the development of a non-stoichiometric, biological apatite layer on their surface after exposure in SBF for several time periods. The onset of apatite-layer formation is directly dependent on the amount of bioglass in the coating and its thickness reduces within the specimens of the same bioactive glass-porcelain proportion with time, reaching an average thickness of 15 microm at the longest immersion time, for all the specimens.

<title>Study of hydroxyl carbonate apatite formation on bioactive glass coated dental ceramics by confocal laser scanning microscopy (CLSM)</title>

“…For this reasons, the dental restorations and the prosthesis implants used bioactive materials such as glasses and glass-ceramics which proved their powerful implication in soft tissue attachment [2]. Investigations on the bonding mechanism demonstrated its association with the development, in short time after insertion into biological environment [3][4][5] of a carbonatecontaining hydroxyapatite layer. Hydroxyapatite (HA) is a naturally occurring mineral and the predominant mineral component of vertebrate bone and tooth enamel.…”

“…Naturally-occurring bone mineral is made of nanometer sized, poorly-crystalline calcium phosphate with hydroxyapatite structure. However, speaking of the ideal stoichiometric crystalline hydroxyapatite Ca 10 (PO 4 ) 6 (OH) 2 with atomic Ca/P ratio 1.67 [6], the composition of bone mineral is significantly different and may be represented by the following formula: Ca 8.3 (PO 4 ) 4.3 (HPO 4 , CO 3 ) 1.7 (OH, CO 3 ) 0.3 Bone mineral non-stoichiometry is primarily due to the presence of divalent ions, such as CO 3 2-and HPO 4 2-which are substituted for the trivalent PO 4 3-ions. Substitution by CO 3 2-and HPO 4 2-ions produce a change of the Ca/P ratio, resulting in the Ca/P ratio which may vary between 1.50 and 1.70 depending of the age and bone site.…”

“…If the bioactive ceramic is immersed in SBF, immediately begins a partial dissolution of the surface followed by releasing of Ca 2+ , HPO 4 2-and PO 4 3-, increasing the supersaturation of SBF regarding to apatite. The layer of hydroxy-carbonate apatite (HCAp) begins to grow up by the calcium and phosphate ions uptake from SBF and by the incorporation of other electrolytes such as CO 3 2-and Mg 2+ [9,10]. The aim of this study was the investigation of the surface structure changes of ceramic -porcelain mixture used in material-ceramic restorations, coated with commercially available bioactive glass, after exposure in a simulated body fluid for a different number of days, in order to evaluate any possible differences which could lead to stable bioactive layer on these conventional ceramics.…”

Bioactivity of leucite containing glass - ceramics using natural raw materials

“…Studies have been made to evaluate bioactive glass-ceramics composites containing leucite for dental application 9,10 . In this work, it was able to produce glass-ceramics containing sodium calcium silicate and leucite as mayor phases, but not by mixing two glasses that have different composition, as it is the case of glass-ceramics composites.…”

Studying morphological characteristics of thermally treated bioactive glass ceramic using image analysis

“…Tuominen et al 12 observed the formation of hemidesmosomes of oral epithelial and connective tissues in contact to bioactive glass, while Kontonasaki et al 13 reported that even with a considerable retardation, bioactive glass can still elicit bioactive behavior when coated on dental porcelain used in metal-ceramic restorations.…”