Surface treatment by different parameters of erbiumryttrium-aluminum-garnet [ENYAG] laser: scanning electron microscope [SEM] evaluation

Introduction: This study aimed to assess the Scanning Electron Microscope [SEM] analysis of tooth surface irradiated by erbium:yttrium-aluminum-garnet [EnYAG] laser with various parameters

Methods: Number of 25 extracted human third molars free of caries were used in this study.

The teeth were put into 5 groups for laser irradiation as follows: group 1 [power: 0.5 W, Energy: 50 mj]; group 2 [power: 1 W, Energy: 100 mj]; group 3 [power: 1.5 W, Energy: 150 mj]; group 4 [power: 2 W, Energy: 200 mj]; group 5 [power: 2.5 W, Energy: 250 mj]. All samples were prepared by repetition rate of 10 Hz and duration of 230 us, using a non-contact handpiece at a distance of 4 mm. Then, the samples were prepared for SEM examination

Results: SEM evaluation of every 25 samples, treated by EnYAG, showed that all groups had exposed dentinal tubules without any melted area or cracks

Conclusion: In this study we used SEM to investigate ablated dentine with different parameters of EnYAG laser energy. Our findings support these conclusions. All powers of laser below 3 W are proper for ablation, and make no cracks

[Comparison of fracture resistance and failure mode of different zirconia abutments with titanium abutment]

One of the decisive factors on the final esthetic results of implant treatment is the abutment material. Ceramic abutments are nowadays very popular in this regard. The purpose of this study was to compare the fracture resistance of three zirconia abutments with titanium abutment. Four groups of abutments [five specimens in each] were prepared. The abutments were prefabricated titanium, prefabricated zirconia, zirconia-metal, and copy-milled zirconia abutment. After securing the abutments to the implant using a torque of 24 Ncm, they were mounted into a mounting jig using the 30[degree sign] tilt. The force was applied on the assembly till the failure occurred. Facture resistance and mode of failure were recorded for each specimen. The data were analyzed using One-way ANOVA. The mean values recorded for fracture resistance of different zirconia abutments varied between 426 to 688 N; however, there was no significant differences among the groups [P=0.14]. Body fracture was observed only in prefabricated zirconia abutments. Screw fracture and screw bending were the common failures observed in other groups. Zirconia abutments of any type could be successfully used in regular plateform implants

effect of porcelain veneer and liner usage on microtensile bond strength of cercon zirconia ceramics

Bond strength between veneers ceramic any zirconia framework is the weakest component in the layered structure. This bond was sensitive to the liner application and type of veneer ceramic. This study examined the core-veneer microtensile bond strength of a CAD/CAM [computer aided design/computer assisted manufactured] zirconia ceramic by comparing two ceramic veneers with and without liners. Disc-shaped [19.4x3.5mm] specimens were fabricated using CAD/CAM zirconia core materials [Cercon]. Half of the discs were left white and the others were colored with an A2 liner. The specimens were veneered with Ceram Kiss or Zirkonzahn ICE veneering ceramics [3.5 mm]. The discs were then cut into microbars [CC, ZC, CW, ZW] and the microtensile strength of the core-veneer bond was calculated. The specimens were analyzed by SEM and the data were compared using one-way ANOVA and Post hoc tests. The type of veneering ceramic [Ceram Kiss] and liner application [coloring] significantly affected the core-veneer microtensile bond strength [P<0.0001]. The Zirkonzahn layer [ZC, ZW] did not show significant differences [P=0.08]. Careful selection of veneering ceramics and liner applications can be recommended as they have significant roles in microtensile bond strength of core veneered restorations

Scanning electron microscope [SEM] evaluation of tooth surface irradiated by different parameters of Erbium: Yttrium Aluminium Garnet [Er:YAG] laser

The aim of this study was to investigate the Scanning Electron Microscope [SEM] analysis of tooth surface irradiated by different parameters of Er:YAG laser. 15 caries-free extracted human third molars were used in this study. The teeth were put into 5 groups for laser irradiation as follows: Group 1 [power: 2.5 W, Energy: 250 mJ]; Group 2[power: 3 W, Energy: 300 mJ]; Group 3 [power: 3.5 W, Energy: 350 mJ]; Group 4 [power: 4 W, Energy: 400 mJ]; Group 5 [power: 4.5 W, Energy: 450 mJ]. All samples were prepared by repetition rate of 10 Hz. Then, the samples were prepared for SEM examination. The SEM images showed cleaned ablated surface and exposed dentinal tubules, without production of smear layer. It can be concluded that Er:YAG laser can be an alternative technique for surface treatment and can be considered as safe as the conventional methods, like turbine and bur

[Accuracy of implant transfer with open-tray and closed-tray impression techniques and surface detail reproduction of the tooth during impression]

Accurate recording of implant location is required to achieve passive fit and have the implants without stress concentration. The aim of this in-vitro study was to evaluate the dimensional and angular accuracy of open-tray and closed-tray impression techniques using polyether impression material and also to assess the surface detail reproduction of the tooth while impression making. One reference metal model with 2 implants [Implantium] on the position of the maxillary second premolar and first molar and one molar tooth for evaluation of surface details was prepared. 27 polyether impressions of these models were made [9 using open-tray, 9 using closed-tray techniques and 9 were made just of the surface of the teeth without any implants]. Impressions were poured with ADA type IV stone. Coordinate Measuring Machine was used for measuring the dimensional accuracy and video measuring machine for surface detail reproduction. All of these measurements were compared with the measurements on the reference model. Data were analyzed by and compared by T-test and One-way ANOVA. There was a significant statistical difference between open-tray and closed-tray techniques [P<0.001]. There was no significant difference in the surface detail reproduction of open-tray and Closed-tray techniques and impression making with or without the implants [P>0.05]. The accuracy of open-tray impression technique was more than closed-tray technique. The surface detail reproduction of the tooth was not affected by impression technique