ABSTRACT
BACKGROUND: The purpose of this study was to evaluate nanohardness and viscoelastic behavior of dentin surfaces treated with two canal sealer cements for dentin remineralization. MATERIAL AND METHODS: Dentin surfaces were subjected to: I) 37% phosphoric acid (PA) or II) 0.5 M ethylenediaminetetraacetic acid (EDTA) conditioning prior to the application of two experimental hydroxyapatite-based cements, containing sodium hydroxide (calcypatite) or zinc oxide (oxipatite), respectively. Samples were stored in simulated body fluid during 24 h or 21 d. The intertubular and peritubular dentin were evaluated using a nanoindenter to assess nanohardness (Hi). The load/displacement responses were used for the nano-dynamic mechanical analysis to estimate complex modulus (E*) and tan delta (δ). The modulus mapping was obtained by imposing a quasistatic force setpoint to which a sinusoidal force was superimposed. AFM imaging and FESEM analysis were performed. RESULTS: After 21 d of storage, dentin surfaces treated with EDTA+calcypatite, PA+calcypatite and EDTA+oxipatite showed viscoelastic discrepancies between peritubular and intertubular dentin, meaning a risk for cracking and breakdown of the surface. At both 24 h and 21 d, tan δ values at intertubular dentin treated with the four treatments performed similar. At 21 d time point, intertubular dentin treated with PA+oxipatite achieved the highest complex modulus and nanohardness, i.e., highest resistance to deformation and functional mineralization, among groups. CONCLUSIONS: Intertubular and peritubular dentin treated with PA+oxipatite showed similar values of tan δ after 21 d of storage. This produced a favorable dissipation of energy with minimal energy concentration, preserving the structural integrity at the dentin surface
Subject(s)
Humans , Dental Cementum/physiology , Calcification, Physiologic , Dentin/metabolism , Bone Cements/chemistry , Zinc Phosphate Cement/administration & dosage , Biomechanical Phenomena , Materials TestingSubject(s)
Cementation/methods , Crowns/standards , Space Maintenance, Orthodontic/methods , Dental Cements/classification , Dental Materials , Prosthesis Design/methods , Glass Ionomer Cements , Metal Ceramic Alloys , Dental Prosthesis/methods , Silicone Elastomers , Zinc Phosphate Cement/administration & dosageABSTRACT
The design of the preparations is the main factor of a long lasting retention of crowns and bridges. Unfortunately, cementation is not a gluing but a luting procedure. Among the new permanent cements, glass ionomer which has a low solubility is the most interesting one. The cement exposed at the marginal gap is less prone to be lost. Nevertheless, zinc phosphate, which has a longer working time, remains very popular. Cementation using zinc phosphate is described step by step.
Subject(s)
Denture Retention , Denture, Partial, Fixed , Zinc Phosphate Cement/administration & dosage , Glass Ionomer Cements/administration & dosage , HumansSubject(s)
Calcium Hydroxide/administration & dosage , Dental Cavity Lining , Pulpotomy/methods , Tooth, Deciduous/anatomy & histology , Zinc Oxide-Eugenol Cement/administration & dosage , Animals , Child , Child, Preschool , Dogs , Humans , Tooth, Deciduous/drug effects , Zinc Oxide-Eugenol Cement/pharmacology , Zinc Phosphate Cement/administration & dosage , Zinc Phosphate Cement/pharmacologyABSTRACT
In the study, cast gold crowns were cemented similar to methods used for patients. Conclusions were that: 1. Fresh cement painted with a camel brush in the part of the crown to be cemented promotes a better fit than when the crown is completely filled with cement. 2. Mechanical vibration of the crown at cementation promotes a better fit. 3. Venting the crown, an internal relief by acid etching, or a combination of both these procedures improve the seating of the crown during cementation. 4. The association of one or numerous variables used in this study considerably improves the fit of the cemented crown.
