Abstract
This study investigated the potential of adhesive coating for hindering the reactivity of ion-releasing dental restorative materials. Experimental composites were prepared by replacing 10 or ...20 wt% of reinforcing fillers with two types of bioactive glass. A glass ionomer, a giomer, and an alkasite were used as representatives of commercial ion-releasing materials. Restorative material specimens were coated with an etch-and-rinse adhesive, 1-step self-etch adhesive, 2-step self-etch adhesive, or left uncoated. The specimens were immersed in a lactic acid solution and ion concentrations were measured in 4 days intervals for 32 days (atomic absorption spectrometry for calcium, UV–Vis spectrometry for phosphate, ion-selective electrode for fluoride, and pH-meter for pH values). The adhesive coating reduced ion release between 0.3 and 307 times, in a significantly material- and adhesive-dependent manner. Fluoride release was most highly impaired, with the reduction of up to 307 times, followed by phosphate and calcium release, which were reduced up to 90 and 45 times, respectively. The effect of different adhesive systems was most pronounced for phosphate release, with the following rankings: uncoated ≥ 2-step self-etch adhesive ≥ 1-step self-etch adhesive ≥ etch-and-rinse adhesive. The differences among adhesives were less pronounced for calcium and fluoride. It was concluded that the resinous adhesive layer can act as a barrier for ion release and diminish the beneficial effects of remineralizing restorative materials.
The purpose of this in vitro study was to investigate whether different types of experimental and commercial restorative dental materials can protect dentin against acid-induced softening. ...Experimental composites were prepared with a photocurable mixture of methacrylates and two types of bioactive glass (45S5 and a customized low-Na F-containing formulation). Human dentin samples were prepared from mid-coronal tooth slices and immersed in lactic acid solution (pH = 4.0) at 5 mm from set specimens of restorative material. After 4, 8, 12, 16, 20, 24, 28, and 32 days, surface microhardness of dentin samples and pH of the immersion solution were measured, followed by replenishing of the immersion medium. Microstructural analysis was performed using scanning electron microscopy. The protective effect of restorative materials was determined as dentin microhardness remaining statistically similar to initial values for a certain number of acid additions. Scanning electron microscopy showed a gradual widening of dentinal tubules and proved less discriminatory than microhardness measurements. To produce a protective effect on dentin, 20 wt% of low-Na F-containing bioactive glass was needed, whereas 10 wt% of bioactive glass 45S5 was sufficient to protect dentin against acid-induced demineralization. The anti-demineralizing protective effect of experimental and commercial restoratives on dentin was of shorter duration than measured for enamel in a previous study using the same experimental approach.
Radiotherapy is used to treat neo plasmatic lesions and the common side effects of this process are pain, swelling and sensitivity of mucous membranes in domain of radiation, reduced salivation, ...caries, and periodontal disease and, in total, low life quality. The purpose of this research was to estimate the outcome of direct irradiation on physical and surface characteristics of hard dental tissues.
Twenty, caries free third molars were involved in the research. Prior to different submission protocols, tooth halves were randomly assigned to subject and control groups by using a draw method. The first group (n=20) was submitted to conventional irradiation protocol (2 Gy for 35 days), second group (n=20) was submitted to one powerful, exploratory dose of 70 Gy. Each sample served as its own control. Radiation was performed with a linear accelerator radiotherapy unit. The surface microhardness and roughness were measured at the beginning (initially), and upon completion of irradiation procedure. The average change in microhardness and roughness after different treatments was compared by t-test for independent samples. Normality was tested by the Shapiro-Wilk test.
Significant differences were found after the standard radiation protocol and the exploratory dose of 70 Gy, with decreased mean microhardness and increased mean roughness (p<0.001) of both hard dental tissues. Enamel and dentin surface microhardness and roughness did not vary notably with regards to different irradiation protocols.
Head and neck conventional irradiation protocol leads to possible breakdown of enamel and dentin with reduced microhardness and increased surface roughness regardless of used irradiation protocol.
Introduction:
The aim of this study was to evaluate the effects of radiation and tooth bleaching on the physical and morphological properties of enamel and dentin on permanent teeth.
Materials and ...Methods:
Eighty fresh, non-carious third molars were used in this study. Before cutting the crown in half, the teeth samples were randomly allocated to treatment and control groups by using a lottery method. The first group (
n
= 20) underwent standard radiation protocol (2 Gy/fraction/day, 5 days/week) with bleaching treatment afterward using 16% carbamide peroxide gel, the second group (
n
= 20) underwent standard radiation protocol with afterward bleaching treatment using 38% hydrogen peroxide, the third group (
n
= 20) underwent a short, one strong, experimental dose of 70 Gy with afterward bleaching treatment using 16% carbamide peroxide gel, and the fourth group (
n
= 20) underwent one strong, experimental dose of 70 Gy with afterward bleaching treatment using 38% hydrogen peroxide gel. Groups 5–8 (
n
= 20) served as control as they underwent only bleaching treatment. Vickers microhardness and surface roughness were performed before (initial) and after irradiation and before bleaching or after only bleaching. The effects of irradiation and bleaching on microhardness (or roughness) of enamel and dentin were analyzed in the repeated-measures ANOVA model.
Results:
Enamel microhardness after experimental single 70-Gy irradiation or after standard radiation protocol and bleaching with 16 or 38% gel was not statistically significant from microhardness in the control group (
p
> 0.05). There was a statistically significantly greater reduction in the average microhardness of enamel and dentin during bleaching with 38% gel compared to 16% for both radiation protocols (
p
< 0.001). After experimental 70-Gy irradiation and bleaching, a 16% statistically significant increase in surface roughness was found for enamel (
p
= 0.006) and dentin (
p
= 0.018), while this was not recorded for 38% gel. There was a statistically significantly greater increase in the average roughness of enamel and dentin during bleaching with 38% gel compared to 16% (
p
< 0.001) for both radiation protocols.
Conclusions:
Directly induced radiation leads to potential damage of hard dental tissues, which can be further damaged by additional bleaching. If teeth whitening is necessary after irradiation, it is suggested to use lower concentrations of whitening gels.
To prepare experimental composites with bioactive glass (BG) and investigate their release of calcium (Ca), phosphate (PO4), and fluoride (F), as well as pH changes and apatite precipitation after ...immersion.
Experimental composites were prepared with 0, 10, or 20 wt% of either BG 45S5 or a customized low-Na F-containing BG. Three commercial ion-releasing materials were used for reference. Material specimens were immersed in lactic acid (pH = 4.0) and artificial saliva (pH = 6.4). Ion concentrations (atomic absorption spectrometry for Ca, UV–vis spectrometry for PO4, and ion-selective electrode for F) and pH were measured after 4, 8, 12, 16, 20, 24, 28, and 32 days. After immersion, composite specimens were analyzed using scanning electron microscopy (SEM) and Fourier-transform infrared (FTIR) spectroscopy.
Material-dependent concentrations of Ca, PO4, and F were measured in the lactic acid solution, while a decrease of Ca and PO4 concentrations was observed in artificial saliva. The uptake of ions from artificial saliva indicates their precipitation on specimen surfaces, which was supported by the results of SEM and FTIR investigations. In experimental composites functionalized with both bioactive glass types and a commercial “alkasite” material, apatite was precipitated not only in artificial saliva but also in the lactic acid solution.
Experimental BG-containing composites and selected commercial restorative materials demonstrated the potential for releasing multiple ion types and increasing pH.
The observed effects can be beneficial for preventing demineralization and promoting remineralization of dental hard tissues, while apatite precipitation can additionally help in sealing marginal discontinuities.
The aim was to evaluate the effects of Er,Cr:YSGG and/or bioactive glass 45S5 (BG) on the chemical and physical properties of enamel after radiotherapy. Third molar crowns were cut in half ...(buccal-lingually), and the mid part of the labial/oral surface was subjected to different protocols. All samples were treated with standard 70 Gy. After radiotherapy, enamel was treated with either Er,Cr:YSGG (2780 nm; pulse 60 μs) and BG or only BG, and control samples were kept in deionized water. Vickers microhardness, scanning electron microscopy (SEM), and characteristic X-ray spectroscopy (EDS) were performed before, after radiotherapy, and after treatment. Analysis of variance (ANOVA) was used. A significant drop in enamel microhardness was observed after radiotherapy (
p
< 0.001). After Er,Cr:YSGG and BG or BG alone, there was a significant increase in microhardness (
p
< 0.001), which was on average significantly higher compared to the initial measurements for Er,Cr:YSGG with BG (
p
< 0.001), but not observed in BG alone (
p
= 0.331). After radiotherapy, SEM showed increased surface roughness with eroded prisms. Er,Cr:YSGG and BG or BG alone both showed disorderly packed glass particles on the enamel surface. Radiotherapy noticeably reduced the concentrations of calcium and phosphorus. Er,Cr:YSGG and BG treatment increased the concentrations of calcium, sodium, phosphorus, and silicate. BG treatment alone increased the concetration of calcium and phosphorus. Directly induced radiotherapy led to potential damage of enamel, but afterwards treatment with Er,Cr:YSGG laser and BG resulted in a higher increase of enamel microhardness compared to BG alone, reflecting in a possible better remineralization effect.
Umjetna pužnica je neurosenzorička proteza, koja je suvremeni tehnički i tehnološki medicinski terapijski izbor liječenja osoba s teškom nagluhošću ili s gluhoćom. Postupak otokirurške ugradnje ...umjetne pužnice zove se kohlearna implantacija. Telemetrija je sastavni dio tog postupka. Predstavlja metodu mjerenja neuralnog odgovora slušnog živca na električnu stimulaciju. Telemetrijom se određuju pragovi čujnosti, pragovi neugode podražaja i dinamički raspon. Objektivnim parametrima telemetrije procjenjujemo i psihoakustičke parametre, koji su temelj simulacijskih mapa za buduću rehabilitaciju oštećenog sluha.
Artificial cochlea or cochlear implant is the name for neurosensory prosthesis, which is a current surgical treatment for severe hearing loss or deafness.The surgical procedure is cochlear ...implantation During the cochlear implantation one of the methods of neural response measuring of the auditory nerve to electrical stimulation is telemetry. It is an integral part of the cochlear implantation procedure. Telemetry determines audibility thresholds, stimulus discomfort thresholds, and dynamic range. With objective parameters, in telemetry we also estimate psychoacoustic parameters, which are the basis of simulation maps for the future hearing rehabilitation.
Introduction: Radiotherapy is used to treat neo plasmatic lesions and the common side effects of this process are pain, swelling and sensitivity of mucous membranes in domain of radiation, reduced ...salivation, caries, and periodontal disease and, in total, low life quality. The purpose of this research was to estimate the outcome of direct irradiation on physical and surface characteristics of hard dental tissues. Material and methods: Twenty, caries free third molars were involved in the research. Prior to different submission protocols, tooth halves were randomly assigned to subject and control groups by using a draw method. The first group (n=20) was submitted to conventional irradiation protocol (2 Gy for 35 days), second group (n=20) was submitted to one powerful, exploratory dose of 70 Gy. Each sample served as its own control. Radiation was performed with a linear accelerator radiotherapy unit. The surface microhardness and roughness were measured at the beginning (initially), and upon completion of irradiation procedure. The average change in microhardness and roughness after different treatments was compared by t-test for independent samples. Normality was tested by the Shapiro-Wilk test. Results: Significant differences were found after the standard radiation protocol and the exploratory dose of 70 Gy, with decreased mean microhardness and increased mean roughness (p<0.001) of both hard dental tissues. Enamel and dentin surface microhardness and roughness did not vary notably with regards to different irradiation protocols. Conclusion: Head and neck conventional irradiation protocol leads to possible breakdown of enamel and dentin with reduced microhardness and increased surface roughness regardless of used irradiation protocol. Uvod: Radioterapija se primjenjuje u lijecenju neoplazmatskih lezija, a uobicajene nuspojave u tom procesu obicno su bol, oteklina i osjetljivost sluznice u podrucju zracenja, smanjeno izlucivanje sline, karijes, parodontna bolest i smanjena kvaliteta zivota. Svrha ovog istrazivanja bila je procijeniti ucinak izravnoga zracenja na fizicke i povrSinske karakteristike tvrdih zubnih tkiva. Materijali i me-tode: Istrazivanje je provedeno na 20 trecih kutnjaka bez karijesa. Prije primjene razlicitih protokola zracenja, polovine zuba rasporedene su u ispitnu i kontrolnu skupinu metodom nasumicnog izvlacenja. Prva skupina (n = 20) podvrgnuta je konvencionalnom protokolu zracenja (2 Gy tijekom 35 dana), druga skupina (n = 20) bila je izlozena jednoj snaznoj, eksperimentalnoj dozi od 70 greja (Gy). Svaki uzorak sluzio je kao vlastita kontrola. Zracenje je provedeno radioterapijskom jedinicom line-arnog akceleratora. Mikrotvrdoca i hrapavost povrSine mjerene su na pocetku (pocetna) i na kraju postupka zracenja. Prosjecna promjena mikrotvrdoce i hrapavosti nakon razlicitih tretmana uspo-redena je t-testom za nezavisne uzorke. Normalnost je testirana Shapiro-Wilkovim testom. Rezultati: Uocene su znacajne razlike nakon standardnoga protokola zracenja i eksperimentalne doze od 70 greja, uz smanjenu prosjecnu mikrotvrdocu i povecanu prosjecnu hrapavost (p < 0,001) obaju tvrdih zubnih tkiva. Mikrotvrdoca i hrapavost povrSine cakline i dentina nisu se znacajno razlikovale s obzirom na razlicite protokole zracenja. ZakljuCak: Standardni protokol zracenja glave i vrata moze oStetiti caklinu i dentin, uz smanjenu mikrotvrdocu i povecanu hrapavost povrSine bez obzira na koriSteni protokol zracenja.
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