ABSTRACT
Introduction The evolution of computer-aided design/computer-aided manufacturing (CAD/CAM) systems has heightened the significance of digital models in dentistry, particularly for fabricating prostheses like inlays, crowns, and bridges. While digital dentistry offers enhanced speed and precision, the initial investment in intraoral scanners may pose a barrier for some clinicians. Extraoral or lab scanners, however, offer a viable alternative, reducing laboratory time and providing accurate prostheses fit, though challenges such as reflective surfaces and availability of scanning sprays persist, impacting scanning quality and operator technique. Optical scanning using laboratory scanners is a routine practice in today's age of digital dentistry. Often these require powder opacification to record fine details. There are numbered studies on the accuracy of scanning sprays. Materials and methods Ten casts, poured with type 4 dental stone (Elite Rock, Zhermack, Italy) with single implants, were used for the purpose of this study. Each cast was scanned by two different operators, using both mediums. It was scanned using an extraoral scanner (E4, 3Shape, Copenhagen, Denmark). Operator A used easy scan (Alphadent, Korea), followed by zirconia dust (Upcera, Guangdong, China), whereas operator B used zirconia dust first. Digital models within each group were superimposed individually to measure precision. Results Easy scan operator 1 and zirconia dust operator 1 differ by 0.16000 (p = 0.0802). In scenario 2, easy scan operator 2 and zirconia dust operator 2 differ by 0.21900 (p = 0.0212) . Operator type significantly affects performance, emphasizing the need to account for operator variability in relevant contexts. The trueness values obtained for zirconia dust and easy scan among both operators were statistically insignificant. Conclusion Zirconia dust can be reliably used for extraoral scanning of abutments in place of optical scanning sprays.
ABSTRACT
AIM: To evaluate the effect of salivary contamination on the bond strength of one-bottle adhesive systems - (the V generation) at various stages during the bonding procedure and to investigate the effect of the contaminant removing treatments on the recovery of bond strengths. MATERIALS AND METHODS: In this study the V generation one-bottle system - (Adper Single Bond) was tested. Fifty caries-free human molars with flat dentin surfaces were randomly divided into five groups of ten teeth each: Group I had 15 second etching with 35% Ortho Phosphoric acid, 15 second rinse and blot dried (Uncontaminated); Group II contaminated and blot dried; Group III contaminated and completely dried; Group IV contaminated, washed, blot dried; Group V contaminated, retched washed, and blot dried. The bonding agent was applied and resin composite (Z-100 3M ESPE) was bonded to the treated surfaces using the Teflon mold. The specimens in each group were then subjected to shear bond strength testing in an Instron Universal testing machine at a crosshead speed of 1 mm / minute and the data were subjected to one way ANOVA for comparison among the groups (P<0.05). RESULTS: There was a significant difference between the group that was dried with strong oil-free air after contamination (Group III) and the other groups. When the etched surface was contaminated by saliva, there was no statistical difference between the just blot dry, wash, or the re-etching groups (Groups II, IV, V) if the dentin surface was kept wet before priming. When the etched dentin surface was dried (Group III) the shear bond strength decreased considerably. CONCLUSION: The bond strengths to the tooth structure of the recent dentin bonding agents are less sensitive to common forms of contamination than assumed. Re-etching without additional mechanical preparation is sufficient to provide or achieve the expected bond strength.
