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Evaluation of shear bond strength of bioactive glass ionomer containing titanium and conventional glass ionomer particles to dentin treated with Er-YAG laser and conventional methods
Abdolrahim Davari, Farnaz Farahat, Mahnaz Mehranfar,
Volume 35, Issue 0 (5-2022)
Abstract
Background and Aims: Recently, the addition of nanoparticles into the restorative materials and tooth preparation by laser for improving the bond strength have been concidered by researchers. The aim of this study was to investigate the shear bond strength of the bioactive glass ionomer containing titanium particles and a conventional glass ionomer with two surface treatments by Er-YAG laser and conventional methods.
Materials and Methods: In this in-vitro study, 64 sound extracted premolars were collected. For conventional method, the specimens were prepared in such a way that dentin surfaces with a depth of 0.5 millimeter created at distance of 2 mm from the joint of CEJ at the root or crown.  In the laser group, after preparing the teeth, the surface area was prepared by Er-YAG laser. Then, in the middle part of the buccal surface, a cylindrical mold with dimensions of 3.5 mm in diameter and 4 mm in height was placed and for each group was filled with its own glass ionomers. The  specimens  were divided into 8 groups by simple random sampling (n=8): A (laser, conventional glass ionomer, coronal dentin)/ B (laser, glass ionomer containing titanium nanoparticle, coronal dentin)/C (conventional, conventional glass ionomer, coronal dentin)/ D (conventional, glass ionomer containing titanium nanoparticle, coronal dentin)/ E (laser, conventional glass ionomer, root dentin)/ F (laser, glass ionomer containing titanium nanoparticle, root dentin)/ G (conventional, conventional glass ionomer, root dentin)/ H (conventional, glass ionomer containing titanium nanoparticle, coronal dentin). Finally, the shear bong strength by a universal testing machine was measured at a cross-head speed of 1 mm/min. For data analysis, Two-way ANOVA test was used to evaluate the effect of each variable and their interaction on the shear bond strength and Tukey test was used to compare the two groups.
Results: There was significant difference only between groups B with C (P=0.002), E (P=0.007), G (P=0.001) and H (P=0.01). The highest bond strength was found for group B (laser, glass ionomer containing titanium nanoparticle, coronal dentin) and the lowest bond strength for group G (conventional, conventional glass ionomer, root dentin).
Conclusion: All three factors of Er-YAG laser, glass ionomer containing titanium nanoparticle and coronal dentin had a positive effect on the improvement of the bond strength.

Comparision between laser and sandblasting surface treatments on push-out bond strength of fiber posts to root canals
Abdolrahim Davari, Farnaz Farahat, Haleh Davoudi,
Volume 36, Issue 0 (5-2023)
Abstract
Background and Aims: Insufficient adhesion between fiber post and root canal is the main reason for the failure of the restoration and the fiber post surface treatment can imprive the bond strength. Additionally, there is disagreement about the ideal method of preparation to achieve the desired bond. The aim of this study was to compare the effect of two surface treatment methods on push-out bond strength of fiber posts to root canals.
Materials and Methods: In this study, 45 healthy incisor teeth underwent root canal treatment. After preparing the post space, they were divided into 3 groups of 15, based on the surface treatment methods of the fiber post. In the first group as control group, no surface treatment was done on the fiber post. In the second and third groups, sandblasting with Cojet sand particles and 810 nm diode laser were used for surface treatment, respectively. Then, fiber posts were placed in all root channels by a self-adhesive resin cement. Then, the roots were cut in such a way that from each, 3 pieces with a thickness of 1.5 mm were obtained. Finally, the push-out bond strengths were measured using a universal testing machine. Data were analyzed by ANOVA using SPSS software. The level of significance was considered at P<0.05.
Results: The average bond strengths in three groups were as follows: control group, 2.877 ±1.430, sandblast group 6.318±3.444, and laser 4.224 ±1.890 MPa ± SD. The difference in the bond strength between the sandblast group and the control group was significant (P=0.001). However, the average of the bond strength of laser group was not significantly different from the control group. (P=0.03).
Conclusion: The findings of this study showed that unlike diode laser radiation, the use of Cojet sand particles for sandblasting the fiber post surfaces significanlty improved the bond strength.

Deciphering the ecophysiological interactions of oral bacterial pathogens with host glycome causing pulp/periapical and periodontal infections: A systematic review
Neda Yousefi Nojookambari, Malihe Naderi, Razie Askari, Somayeh Talebi, Mana Mohammadhosseini, Sahar Shabani, Sajjad Yazdansetad,
Volume 37, Issue 0 (3-2024)
Abstract
Background and Aims: Oral bacteria play an important role in oral diseases, due to their high adaptability to different environmental areas of the mouth. In this article, an attempt was made to describe the molecular mechanisms involved in the physiological relationships of oral and dental environment bacteria and their pathogenic significance with molecular approaches.
Materials and Methods: The present systematic review was written based on the advanced and standard search of keywords including Oral bacteria, Biofilm, and Dental diseases in PubMed, Springer, Scopus, Medline, Google Scholar, Science Direct, and Web of Science databases. For this purpose, an advanced and systematic search of articles published from 1993 to 2023 was conducted to compile the present article.
Results: Bacteria in the oral cavity have nutritional adaptations that are important for living in pathogen-host relationships, including adapting to proteolytic living conditions, using the host's glycome as a nutritional interface. This includes the use of host-derived sialic acid and other glycosidases in oral bacteria. Some of these bacteria adhere to surfaces such as salivary, epithelial proteins, and glycans, which ultimately lead to biofilm formation. Bacteria living in the oral environment are constantly exposed to a wide range of stress-causing factors and oxidative stress in the biofilm.
Conclusion: Dental caries, pulp, periapical, and periodontitis diseases (including gingivitis) are among the most common bacterial diseases. Among them, tooth decay caused by the presence of Streptococcus mutans is the most common dental disease due to the production of acids from carbohydrate fermentation which is characterized by the demineralization of tooth structure.
The effect of aging on shear bond strength of ceramic brackets to zirconia after surface treatment by sandblasting or Nd: YAG laser
Elahe Soltanmohamadi Borujeni, Ali Bavi, Mohammad Aghaali, Ali Saleh, Aida Mehdipour,
Volume 37, Issue 0 (3-2024)
Abstract
Background and Aims: Strong bond between the ceramic brackets and ceramic veneers has an important role in cosmetic treatment. The purpose of this study was to investigate the effect of aging on the shear bond strength (SBS) of ceramic brackets bonded to zirconia after surface preparation by Neodymium-doped Yttrium Aluminum Garnet (Nd: YAG) laser or sandblasting with alumina.
Materials and Methods: This experimental study was conducted on 24 zirconia blocks and these blocks were randomly divided into two groups for surface preparation and each was sub-divided into three time intervals. Surface preparation was done by sandblasting with alumina: in SG1 (Immediately after sandblasting), SG2 (2 weeks after sandblasting), and SG3 (3 months after sandblasting) groups. For the Nd: YAG laser (1/5W, 20Hz, 10s) with non-contact mode: in LG4 (Immediately after laser), LG5 (2 weeks after laser), and LG6 (3 months after laser) groups. The ceramic brackets were bonded to the zirconia blocks. The SBS and adhesive remnant index (ARI) were evaluated and compared among test groups. Dara were analyzed using Mann Whitney test.
Results: There was no significant difference between the SBS of SG1 and LG4 (P=0.430), SG2 and LG5 (P=0.382) and SG3 and LG6 (P=0.326) groups. LG4 group showed the highest shear bond strength. After aging (2 weeks and 3 months), the laser groups showed higher SBS. There was no significant difference in the ARI between SG1 and LG4 (P=0.220), SG2 and LG5 (P=0.154), SG3 and LG6 (P=0.527) groups.
Conclusion: No significant difference was observed between the Nd: YAG laser and sandblasted groups in terms of SBS and ARI over time. Therefore, Nd: YAG laser could be used as a surface treamnet method in Zirconia crowns for bonding to ceramic brackets.
 
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