Clinical performance of light-cured orthodontic adhesives for bonding brackets – an in-vitro study. [version 1; peer review: 1 approved, 2 approved with reservations]

Background The dental profession is seeing a constant influx of new adhesive systems from manufacturers, each claiming to be more dependable than the last. This study assessed the bond strength and adhesive remnants of different light-cured adhesives used for bonding metal brackets to teeth. Methods 80 extracted maxillary premolars with the sound crown structure were acid etched and bonded with brackets on their buccal surfaces utilizing primer and light-cured adhesives into four equal groups, which are Transbond XT, Heliosit, Enlight, and Bracepaste. Shear bond strength (SBS) for de-bonding the brackets were evaluated with Instron- testing machine after 48 hours. The de-bonded samples’ adhesive remnant index (ARI) scores were also measured. Results The maximum mean SBS was found for Transbond XT (12.91 ± 2.0 MPa), followed by Bracepaste (12.87 ± 1.59 MPa), Enlight (11.77 ± 1.87 MPa), and lowest for Heliosit (10.93 ± 1.71 MPa). According to the four point scale, adhesive remnant index (ARI), Transbond XT has the least adhesive residue left on the tooth, followed by Heliosit. Enlight and Bracepaste have a similar distribution of adhesive, with both having a maximum amount left. Conclusion It can be inferred that all groups involved demonstrated a satisfactory level of bond strength from a clinical perspective. Transbond XT is the preferred orthodontic adhesive over the other three adhesives due to its superior SBS and ARI properties

A comparative evaluation of micro shear bond strength and microleakage between the resin-modified glass ionomer cement and residual dentin following excavation of carious dentin using Carie CareTM and conventional caries removal in primary teeth: an in vitro study [version 1; peer review: 2 approved]

Background: The bond between the dentin and restorative material contributes to the success of the restoration. Structural changes associated with prepared dentin may influence the bonding of restorative materials. The present study evaluates the bond between the resin-modified glass ionomer cement (RMGIC) and residual dentin following excavation of carious dentin using Carie CareTM and conventional caries removal in primary teeth. Methods: 52 primary teeth with dentinal caries were randomly grouped into group I, where caries removal was done using the conventional method, and group II which used Carie CareTM. All the teeth were restored using RMGIC. Micro shear bond strength between the residual dentin and the cement was tested using universal testing machine and the dye penetration method was used for microleakage testing. Independent t-test was performed for intergroup comparison. Pearson chi-square test was carried out to evaluate the microleakage patterns in the enamel and dentin. Results: The mean micro-shear bond strength of group I was 6.03±1.6 and that of group II was 8.54±2.92; this difference was statistically significant with a p-value of 0.012. Microleakage was higher in the test group (1.38±0.51) than the control group (0.77±0.6) and was significant with a p-value of .036. Conclusions: Papain-based chemomechanical agent Carie CareTM can be used as an alternative method to conventional caries removal. However, further studies need to explore methods to improve the marginal sealing capacity of RMGIC to the residual dentin after chemomechanical caries removal

Evaluation of mechanical properties of recasted dental base metal alloys for considering their reusability in dentistry and engineering field

Background: Base metal casting alloys are extensively used in dentistry to fabricate many oral appliances and a huge amount is wasted in the form of sprues and buttons during the casting procedure. Recycling and reusing these alloys by clean technologies may save our natural resources from being depleted and as well reduce the cost of the treatment of the patients. Objectives: To study the mechanical properties of recasted dental base metal alloys, and explore possible ways to recycle and reuse in dentistry and other fields of science and technology. Materials and Methods: Two beryllium-free Cobalt-Chromium (Co-Cr) dental casting alloys, Wironit and Wirobond-C, were used for this study. Six groups of specimen (melted once, twice, five, ten, fifteen and twenty times) per each alloy were casted. The tensile strength and hardness of these samples were measured by using universal testing machine and Vickers hardness number (VHN) tester. Results: Tensile strength decreased from 850 MPa to 777 MPa after 5 th recasting and to 674 MPa at the end of 20 th recasting procedure for the Wironit samples. For Wirobond-C samples, tensile strength decreased from 720 MPa to 678 MPa after 5 th recasting and further reduced to 534 MPa at the end of 20 th recasting procedure. Hardness decreased from 380VHN to 335VHN at the end of 20 th recasting for Wironit samples and 328VHN to 247VHN for Wirobond-C samples after 20 th recasting procedure. The slight decrease in their mechanical properties will not have any impact on the clinical performance for dental applications. Conclusion: There is no major degradation in the mechanical properties after recycling, and hence, the left over alloys after casting procedures can be reused in dentistry with a condition to satisfy cytotoxicity tests