BackgroundThe purpose of this study was to assess the surface characterization and frictional resistance between stainless steel brackets and two types of orthodontic wires made of stainless steel and nickel-titanium alloys after immersion in a chlorhexidine-containing prophylactic agent.MethodsStainless steel orthodontic brackets with either stainless steel (SS) or heat-activated nickel-titanium (Ni-Ti) wires were immersed in a 0.2% chlorhexidine and an artificial saliva environment for 1.5 h. The frictional force was measured on a universal testing machine with a crosshead speed of 10 mm/min over a 5-mm of archwire. The surface morphology of bracket slots and surface roughness of archwires after immersion in chlorhexidine were also characterized using a scanning electron microscope (SEM) and an atomic force microscope (AFM), respectively.ResultsThere was no significant difference in the frictional resistance values between SS and Ni-Ti wires immersed in either chlorhexidine or artificial saliva. The frictional resistance values for the SS and Ni-Ti wires immersed in 0.2% chlorhexidine solution were not significantly different from that inartificial saliva. No significant difference in the average surface roughness for both wires before (as-received) and after immersion in either chlorhexidine or artificial saliva was observed.ConclusionsOne-and-half-hour immersion in 0.2% chlorhexidine mouthrinse did not have significant influence on the archwires surface roughness or the frictional resistance between stainless steel orthodontic brackets and archwires made of SS and Ni-Ti. Based on these results, chlorhexidine-containing mouthrinses may be prescribed as non-destructive prophylactic agents on materials evaluated in the present study for orthodontic patients.

Background: The aim of this study was to compare the effect of chlorhexidine- and Persica-containing mouthrinses on the surface characterization of orthodontic appliance and friction between the orthodontic stainless steel wires and brackets. Materials and Methods: In this randomized controlled trial, 75 orthodontic patients (aged 13–30) were allocated (n = 25) into two experimental groups (prescribed by Persica- or chlorhexidine-containing mouthrinse) and one control group (no prescription). The ovoid stainless steel archwires were placed, and the maxillary first premolar stainless steel edgewise brackets were ligated to wires by elastomeric rings. The patients were recalled after 2 weeks, and then, the archwires were removed and replaced. The surface analysis of archwires and brackets was evaluated using scanning electron microscopy and atomic force microscopy. The frictional forces between the archwires and brackets were measured using a universal testing machine. The data for surface roughness were analyzed by the nonparametric Kruskal–Wallis and Mann–Whitney tests. The frictional forces data were analyzed using a two-way analysis of variance and Tukey's post hoc test using SPSS software. The level of significance was P < 0.05. Results: The retrieved brackets showed minor changes in their surface topography. The surface roughness of archwires after the intervention was significantly greater for the chlorhexidine than that of Persica (P < 0.05). The friction force between the archwires and brackets was also significantly higher for the chlorhexidine than that of Persica (P < 0.05). Conclusion: The Persica-containing mouthrinse from the biomechanical and biochemical standpoints may be a better option for oral hygiene in orthodontic patients compared with the chlorhexidine.

"Background: The change in taste is common for pregnant women. This study aimed to assess the sense of taste in pregnant women in comparison with non-pregnant women. Methods: A cohort study was conducted on 120 healthy women. The test group (n=60) included pregnant women presenting to a hospital for pregnancy care in their first, second and third trimesters. Control group (n=60) included healthy non-pregnant women presenting to the same center. The groups were matched in terms of age, marital status and oral hygiene. Assessment of sense of taste was done for two groups using sucrose, sodium chloride and citric acid solutions for perception of sweetness, saltiness and sourness. Serial dilutions of sucrose and sodium chloride solutions were prepared in 1.0, 0.1 and 0.01mM concentrations. Serial dilutions of citric acid were prepared in 3.2, 0.32 and 0.032M concentrations. Data were analyzed using SPSS version 17 and chi square test. Results: Forty-four non-pregnant (73.3%) and 26 pregnant (43.3%) women gave wrong answer to 0.01mM sucrose solution and this difference wasn’t statistically significant (p=0.07). One individual in each group (1.7%) gave wrong answer to 0.1 and 1mM concentration of sucrose. This difference wasn’t statistically significant (P=0.9). Wrong answers in the two groups and among the three trimesters weren’t significantly different for sodium chloride and citric acid (P=0.9). The difference among pregnant women in the three trimesters wasn’t significant for any concentration or tested solution (P=0.9). Conclusion: The sweet taste threshold decreases during pregnancy but the perception threshold for saltiness and sourness remains unchanged. "