Characteristics of Dental Resin-Based Composites in Leukemia Saliva: An In Vitro Analysis

Structural Changes in Resin-Based Composites in Saliva of Patients with Leukemia before Starting Chemotherapeutic Regimen

Background: The aim of this in vitro study was to assess the morphological characteristics and stability of dental composites immersed in saliva collected from patients with leukemia. Material and Methods: A total number of five patients without systemic disease and 20 patients with leukemia (acute lymphoblastic leukemia (ALL), acute myeloid leukemia (AML), chronic lymphocytic leukemia (CLL), and chronic myeloid leukemia (CML)) were included for saliva sampling. Composite disks were immersed in the leukemia, control, and artificial environments for 7 days. At the end of the experiment, atomic force microscopy (AFM), color stability (ΔE), and saliva elements analysis were performed. Statistical significance was considered for a p-value under 0.05. Results: The most changed surface resulted for ALL with a roughness that was almost double that of the untreated sample and was significantly increased compared to the healthy saliva. The effect of CLL was not as intense as observed for acute leukemia, but was significantly over the control. ALL seemed to modify structural components of the saliva, which were able to deteriorate the surface of the composite. ALL saliva promoted a significant dissolution of the initial feature of the samples and promoted nano-particle clusterization. All dental composites showed clinically acceptable color change values (ΔE < 3.3) in all four-leukemia salivas; CLL and CML showed large color differences for all composites. The total concentrations of P, Na, and K showed wide ranges of variations, while the coefficient of variation in Fe, Cu, and Mg showed narrow variations between the salvias’ investigated. The salivary concentration of zinc decreased considerably in the CLL and CML environments compared to the ALL and AML environments. Fe and Cu were significantly increased in the CML environment. Conclusions: Control and artificial salivas have a mild erosive effect on the surface of dental composites. The acute stage of the disease seems to deteriorate the surface roughness rather than its morphology, however, in the chronic stage, it is the surface morphology that mostly deteriorates.

Photodynamic Therapy (PDT) in Prosthodontics: Disinfection of Human Teeth Exposed to Streptococcus mutans and the Effect on the Adhesion of Full Ceramic Veneers, Crowns, and Inlays: An In Vitro Study

The use of PDT in prosthodontics as a disinfection protocol can eradicate bacteria from tooth surfaces by causing the death of the microorganisms to which the photosensitizer binds, absorbing the energy of laser light during irradiation. The aim of the study was to investigate the capacity of PDT to increase the bond strength of full ceramic restorations. In this study, 45 extracted human teeth were prepared for veneers, crowns, and inlays and contaminated with Streptococcus mutans. Tooth surfaces decontamination was performed using a diode laser and methylene blue as a photosensitizer. The disinfection effect and the impact on tensile bond strength were evaluated by scanning electron microscopy (SEM) and pull-out tests of the cemented ceramic prosthesis. Results show that the number of bacteria was reduced from colonized prepared tooth surfaces, and the bond strength was increased when PDT was used. In conclusion, the present study indicates that using PDT as a protocol before the final adhesive cementation of ceramic restorations could be a promising approach, with outstanding advantages over conventional methods.