Ali Khavanin, Mohsen Soleimani, Mehdi Akbari, Ramazan Mirzaie, Masoud Motallebi, Hasan Asiliyan, Ardalan Soleimanian,
Volume 14, Issue 2 (5-2011)
Abstract
Background: Trauma noise is one of the major physical pollutants in modern societies. Sound conditioning, on the other hand, is known as one of the mechanisms for protecting the hearing system.
Materials and Methods: In this experimental study, 15 three month-old male white New Zealand rabbits were divided into three groups. The equipments used in this study included a sound generator, a loudspeaker, an exposure box, a sound level meter, and a distortion product otoacoustic emission (DPOAE) device. The rabbits were assigned to trauma noise exposure, conditioning noise exposure, and control groups. The conditioning and traumatic sound levels were respectively 80 and 105dB within the 500-3000 Hz frequency.
Results: Conditioning noise at the level of 80 in combination with trauma noise enhanced the rabbits hearing system tolerance up to 13-17 dB so that in all frequencies there were significant differences between the trauma noise exposure group and the sound conditioning and trauma noise conditioning group (P<0.05).
Conclusion: Sound conditioning can act as an effective factor in protecting the hearing system against trauma noise.
Rahil Mirzaei, Mehdi Javad Chavosh, Mehdi Rajabnia, Valiollah Arash, Ali Bijiani, Maysam Mirzaie, Mohamad Mehdi Naghibi Sistani,
Volume 24, Issue 1 (April & May 2021)
Abstract
Background and Aim: There exists increased demineralization risk of enamel adjacent to fixed orthodontic attachments by cariogenic bacterias (e.g., Streptpcoccus mutans, Streptpcoccus sobrinus) and inadequate data about commonly used orthodontic cements. Thus, we evaluated the antibacterial effects of three common domestic and foreign orthodontic cements (Glass ionomer, Zinc phosphate, & polycarboxylate) on two cariogenic pathogens (S. mutans & S. sobrinus).
Methods & Materials: In this laboratory study, after culturing two standard strains of Streptococcus mutans and Subrinus bacteria and concentrating and diluting them, a direct contact test was used to evaluate the antibacterial properties of types of cement. The study groups (n=5) included the following: three types of glass ionomer resilience cement, Hoffman’s zinc phosphate and Hoffman’s polycarboxylate, and three glass ionomer cement, zinc phosphate, and carboxylate from Aria Dent factory in Iran. The acquired data were analyzed using SPSS v. 17.
Ethical Considerations: The present study was approved by Babol University of Medical Sciences (Code: MUBABOL.REC.1391.7).Results: In both types of culture media, containing Streptococcus mutans and Streptococcus subrinus bacteria, there was a significant difference between culture media containing 3 groups of cements respecting bacterial growth inhibition zone (P<0.001). In general, The mean diameter of the inhibition zone was greater in Iranian polycarboxylate, compared to its foreign counterpart (P<0.001).
Results: Regarding to zone of inhibition, there was statistically significant difference between three tested cements in both S.mutans and S.sobrinus culturing media (P<0.001). The mean diameter of inhibition zone was greater for Iranian polycarboxylate compared to its foreign counterpart (P<0.001).
Conclusion: Glass ionomer cement demonstrated better antibacterial effect compared to zinc phosphate and polycarboxylate cements. There was also greater antibacterial effect of three tested cements on S.sobrinus than S.mutans. Iranian polycarboxylate showed stronger inhibition on both mentioned bacterias compared to the foreign one.
