The coating of a NiTi alloy has a greater impact on the mechanical properties than the acidity of Saliva

The aim of this study was to evaluate the influence of the acidity of saliva on changes to the surface roughness, friction and microhardness of NiTi alloys with various coatings. Three types of commercially available NiTi archwires: uncoated, rhodium coated and nitrified (dimension 0.508 70.508 mm, 10 cm long) were immersed in 10 mL of artificial saliva with the pH ranging from 4.8 to 6.6 for a period of 28 d. Surface roughness, friction and microhardness were analyzed and compared to the unexposed as-received wires. These mechanical properties were influenced by the wire coating with a moderate-to-high effect size (p\ua30.005; h=0.132-0.309). The uncoated wire had a lower maximum roughness depth after exposure to pH 6.6 and 5.5 than the unexposed wire (p=0.026; h=0.346). The friction was significantly increased only in the rhodium-coated NiTi at pH 4.8 compared to the lower acidities and the unexposed wire (p=0.005; h=0.437). No correlation was found between pH, surface roughness, friction and microhardness, respectively. The coating of a NiTi alloy has a greater impact on the mechanical proper- ties than the acidity does. A rhodium coating makes the alloy harder, induces a rougher surface and more friction. Nitrification does not alter the alloy as much. The relation between acidity and mechanical properties is not linear. A high acidity of 4.8 induces a high friction, but only in rhodium-coated NiTi. A lower acidity does not change the friction significantly

Child Perceptions Questionnaire in Croatia: Two Domains for Measuring Oral Health

Cilj: Provesti međukulturnu prilagodbu i testiranje psihometrijskih svojstava Upitnika o dječjoj percepciji (engl. Child Perceptions Questionnaire – CPQ), kratke inačice od osam čestica za dob od 11 do 14 godina: regresijske (engl. Regression Short Form – RSF:8) i čestične (engl. Item Short Form–ISF:8). Materijali i metode: Uzorak je obuhvatio 237 ortodontskih pacijenata u dobi od 11 do 14 godina na dvjema sveučilišnim stomatološkim klinikama u Hrvatskoj. Procijenjena je strukturna i konstruktna valjanost, pouzdanost i prikladnost. Intraoralni pregled uključivao je procjenu intenziteta karijesa i malokluzije. Rezultati: Dvije dimenzije, umjesto prvotno predloženih četiriju, prikladnije su za procjenu kvalitete života povezane s oralnim zdravljem (engl. Oral Health-Related Quality of Life – OHRQoL) s oba instrumenta – ISF:8 i RSF:8 (60,05 % i 52,24 % varijance; α = 0,56 – 0,85). Oralni simptomi i funkcionalna ograničenja originalnog instrumenta grupirani su u jednu dimenziju koja definira oralnu funkciju, a emocionalno i društveno blagostanje dimenzija je psihosocijalnog blagostanja. Instrumenti mogu otkriti razlike između osoba s niskim i visokim intenzitetom karijesa te malokluzije. Stabilni su kada nema promjena oralnih uvjeta, a u stanju su detektirati razlike uzrokovane korekcijom malokluzije ortodontskom terapijom (p < 0,05). Zaključak: CPQ od osam čestica ima dobra psihometrijska svojstva, no u Hrvatskoj su prikladnije dvije umjesto četiri dimenzije za procjenu OHRQoL-a u dobi između 11 i 14 godina.Objective: To perform cross-cultural adaptation and to test psychometric properties of the 8-item CPQ in 11-14 year-olds: stepwise-regression (RSF:8) and item-impact (ISF:8) short-forms. Materials and Methods: The sample included 237 orthodontic patients aged 11-14 at two University Dental Clinics in Croatia. Structural and construct validity, reliability and responsiveness were assessed. Intraoral examination included an assessment of dental caries and malocclusion severity. Results: Two domains instead of originally suggested four are more appropriate for the assessment of oral healthrelated quality of life (OHRQoL) in both ISF:8 and RSF:8 (60.05% and 52.24% variance; α=0.56-0.85). Oral symptoms and functional limitations from the original instrument were grouped in one dimension that defines oral function, while emotional and social well-being were grouped in a dimension of psychosocial well-being. Instruments are able to detect differences between subjects with low and high caries and malocclusion severity. They were stable when there were no changes in oral conditions, while it was possible to detect differences induced by correction of malocclusion following orthodontic treatment (p<0.05). Conclusion: Both 8-item CPQ demonstrated good psychometric properties but pointed to the fact that two domains instead of four are more appropriate for the assessment of OHRQoL in 11-14 year-olds

Prevalence of Hypodontia in the Permanent Dentition of Macedonian Population

Hypodontia or tooth agenesis is a condition at which the patient is missing one or more teeth due to a failure of those teeth to develop. This is not only an aesthetic, but also a functional deficiency. The incidence of congenitally missing teeth depends on etiological factors that affect tooth development, as well as which dentition is concerned, sex or race and geographic distribution. The tooth agenesis is mostly seen in teeth that are formed last in a given class (lateral incisors, second premolars and third molars). The aim of this study was to calculate the prevalence of congenitally missing teeth in population of FYROM and, through a review of the literature, to compare these results to other populations in the world

The coating of a NiTi alloy has a greater impact on the mechanical properties than the acidity of saliva

The aim of this study was to evaluate the influence of the acidity of saliva on changes to the surface roughness, friction and microhardness of NiTi alloys with various coatings. Three types of commercially available NiTi archwires: uncoated, rhodium coated and nitrified (dimension 0.508×0.508 mm, 10 cm long) were immersed in 10 mL of artificial saliva with the pH ranging from 4.8 to 6.6 for a period of 28 d. Surface roughness, friction and microhardness were analyzed and compared to the unexposed as-received wires. These mechanical properties were influenced by the wire coating with a moderate-to-high effect size (p<=0.005 ; n2=0.132-0.309). The uncoated wire had a lower maximum roughness depth after exposure to pH 6.6 and 5.5 than the unexposed wire (p=0.026 ; n2=0.346). The friction was significantly increased only in the rhodium- coated NiTi at pH 4.8 compared to the lower acidities and the unexposed wire (p=0.005 ; n2 =0.437). No correlation was found between pH, surface roughness, friction and microhardness, respectively. The coating of a NiTi alloy has a greater impact on the mechanical properties than the acidity does. A rhodium coating makes the alloy harder, induces a rougher surface and more friction. Nitrification does not alter the alloy as much. The relation between acidity and mechanical properties is not linear. A high acidity of 4.8 induces a high friction, but only in rhodium-coated NiTi. A lower acidity does not change the friction significantly

Effects of the presence of probiotic bacteria in the aging medium on the surface roughness and chemical composition of two dental alloys

The aims of this study were: (a) to determine if the presence of probiotic bacteria in an aging medium, that is, artificial saliva in this study, has relevant effects on the surface roughness and the chemical composition of two main alloys used in dentistry (NiTi and stainless steel [SS]) and (b) in the case of NiTi, if these effects are influenced by the coating of the alloy (rhodium and titanium nitride). Atomic force microscopy and Raman spectroscopy were used to study the surface morphology and identify metal oxides formed on the surface of the alloys. Experiments demonstrated that the probiotic bacteria Lactobacillus reuteri can induce processes that alter some features of the surface such as roughness and chemical composition. The effect is dependent on the type of alloy and coating. The bacteria increased roughness in the case of uncoated NiTi more than saliva alone (pH = 4.8). Probiotic bacteria tend to decrease the corrosive influence of saliva on NiTi when the alloy is coated with rhodium or titanium nitride and this effect was also evidenced on SS. Raman spectroscopy confirmed that only SS samples are prone to oxidation processes, predominantly associated with exposure to saliva rather than probiotic bacteria

Oral antiseptics and nickel–titanium alloys: mechanical and chemical effects of interaction

The effect of oral antiseptics on the corrosion of nickel-titanium (NiTi) alloys with various coating was investigated. Uncoated, titanium nitride-coated and rhodium-coated NiTi archwires (0.020 × 0.020″) were tested in interaction with artificial saliva pH 4.8 and oral antiseptics based on hyaluronic acid (Gengigel), chlorhexidine (Curasept) and essential oils in alcohol base (Listerine). The dynamics of nickel and titanium ions release were recorded during 28 days. Springback ratio and modulus of resilience were assessed by three-point bending test. The results showed that corrosion of NiTi is related to type of antiseptic mouth rinse and coating formulations. Exposure to an artificial saliva and antiseptics tend to reduce flexibility and resilience of NiTi archwires. The influence of the media is more significant than the influence of the type of the alloys coating. The largest release of nickel ions is in the first 3 days. Antiseptics do not cause further deterioration of the elastic properties in uncoated NiTi compared to saliva. As a result of exposure of nitrified NiTi wires in Listerine, there is bigger release of nickel ions, decrease in elastic properties and lower force delivery in unload. Listerine tends to reduce elastic properties of rhodium- coated wires also. In conclusion, except for Listerine, changes of mechanical characteristics induced by antiseptics are small and would not have a clinically important impact. Generally, Curasept would be the most suitable option

Effects of the presence of probiotic bacteria in the aging medium on the surface roughness and chemical composition of two dental alloys

The aims of this study were: (a) to determine if the presence of probiotic bacteria in an aging medium, that is, artificial saliva in this study, has relevant effects on the surface roughness and the chemical composition of two main alloys used in dentistry (NiTi and stainless steel [SS]) and (b) in the case of NiTi, if these effects are influenced by the coating of the alloy (rhodium and titanium nitride). Atomic force microscopy and Raman spectroscopy were used to study the surface morphology and identify metal oxides formed on the surface of the alloys. Experiments demonstrated that the probiotic bacteria Lactobacillus reuteri can induce processes that alter some features of the surface such as roughness and chemical composition. The effect is dependent on the type of alloy and coating. The bacteria increased roughness in the case of uncoated NiTi more than saliva alone (pH = 4.8). Probiotic bacteria tend to decrease the corrosive influence of saliva on NiTi when the alloy is coated with rhodium or titanium nitride and this effect was also evidenced on SS. Raman spectroscopy confirmed that only SS samples are prone to oxidation processes, predominantly associated with exposure to saliva rather than probiotic bacteria

Corrosion of Dental Alloys Used for Mini Implants in Simulated Oral Environment

The aim of this study was to explore the resistance to general and pitting corrosion of stainless steel and titanium-based orthodontic mini implants in an oral environment. Studies were performed in artificial saliva and in the presence of two oral hygiene products (one containing chlorhexidine digluconate with sodium fluoride and another containing probiotic bacteria) that are usually recommended to orthodontic patients. The results showed that mini implants made from stainless steel have lower resistance to corrosion than titanium implants. General corrosion was increased in both steel and titanium implants when antiseptic agents containing fluoride ions were used, while the tendency towards pitting corrosion was not noticeably altered. Probiotics, on the other hand, had a beneficial effect on general corrosion resistance but were associated with an increased tendency towards pitting corrosion for both implant materials