The Incorporation of Zinc into Hydroxyapatite and Its Influence on the Cellular Response to Biomaterials: A Systematic Review.

Zinc is known for its role in enhancing bone metabolism, cell proliferation, and tissue regeneration. Several studies proposed the incorporation of zinc into hydroxyapatite (HA) to produce biomaterials (ZnHA) that stimulate and accelerate bone healing. This systematic review aimed to understand the physicochemical characteristics of zinc-doped HA-based biomaterials and the evidence of their biological effects on osteoblastic cells. A comprehensive literature search was conducted from 2022 to 2024, covering all years of publications, in three databases (Web of Science, PUBMED, Scopus), retrieving 609 entries, with 36 articles included in the analysis according to the selection criteria. The selected studies provided data on the material's physicochemical properties, the methods of zinc incorporation, and the biological effects of ZnHA on bone cells. The production of ZnHA typically involves the wet chemical synthesis of HA and ZnHA precursors, followed by deposition on substrates using processes such as liquid precursor plasma spraying (LPPS). Characterization techniques confirmed the successful incorporation of zinc into the HA lattice. The findings indicated that zinc incorporation into HA at low concentrations is non-cytotoxic and beneficial for bone cells. ZnHA was found to stimulate cell proliferation, adhesion, and the production of osteogenic factors, thereby promoting in vitro mineralization. However, the optimal zinc concentration for the desired effects varied across studies, making it challenging to establish a standardized concentration. ZnHA materials are biocompatible and enhance osteoblast proliferation and differentiation. However, the mechanisms of zinc release and the ideal concentrations for optimal tissue regeneration require further investigation. Standardizing these parameters is essential for the effective clinical application of ZnHA.

Assessment of the remineralisation induced by contemporary ion-releasing materials in mineral-depleted dentine.

OBJECTIVES: Evaluate the ability of current ion-releasing materials to remineralise bacteria-driven artificial caries lesions. MATERIALS AND METHODS: Standardised class I cavities were obtained in 60 extracted human molars. Specimens underwent a microbiological cariogenic protocol (28 days) to generate artificial caries lesions and then were randomly divided into four restorative groups: adhesive + composite (negative control); glass ionomer cement (GIC); calcium silicate cement (MTA); and resin-modified calcium silicate cement (RMTA). Microhardness analysis (ΔKHN) was performed on 40 specimens (10/group, t = 30 days, 45 days, 60 days in artificial saliva, AS). Micro-CT scans were acquired (3/group, t = 0 days, 30 days, and 90 days in AS). Confocal microscopy was employed for interfacial ultra-morphology analysis (2/group, t = 0 days and 60 days in AS). Additional specimens were prepared and processed for scanning electron microscopy (SEM) and FTIR (n = 3/group + control) to analyse the ability of the tested materials to induce apatite formation on totally demineralised dentine discs (60 days in AS). Statistical analyses were performed with a significance level of 5%. RESULTS: Adhesive + composite specimens showed the lowest ΔKHN values and the presence of gaps at the interface when assessed through micro-CT even after storage in AS. Conversely, all the tested ion-releasing materials presented an increase in ΔKHN after storage (p < 0.05), while MTA best reduced the demineralised artificial carious lesions gap at the interface. MTA and RMTA also showed apatite deposition on totally demineralised dentine surfaces (SEM and FTIR). CONCLUSIONS: All tested ion-releasing materials expressed mineral precipitation in demineralised dentine. Additionally, calcium silicate-based materials induced apatite precipitation and hardness recovery of artificial carious dentine lesions over time. CLINICAL RELEVANCE: Current ion-releasing materials can induce remineralisation of carious dentine. MTA shows enhanced ability of nucleation/precipitation of hydroxyapatite compared to RMTA and GIC, which may be more appropriate to recover severe mineral-depleted dentine.

Utilización de propóleos en odontología / The use of propolis in dentistry

El propóleos es un producto natural elaborado por las abejas a partir de la secreción que recogen de ciertas especies vegetales y que, luego de modificarlas con sus secreciones salivares, lo transportan al interior de la colmena. Así, el propóleos es responsable directo de garantizar la asepsia de la colmena. Múltiples investigaciones científicas atribuyeronal propóleos propiedades antioxidantes, antibacterianas, antivirales, fungicidas, cicatrizantes, antiinflamatorias, anestésicas, inmunomoduladoras antitumorales. Asimismo, en bastas investigaciones se comprobó que el propóleos actúa inhibiendo la actividad de los Streptococo mutans, principal microorganismo productor de caries dental. Esto motivó la realización de la presente revisión bibliográfica sobre las propiedades y utilización del propóleos en odontología.

Propolis is a natural product made by bees fromcollecting secretion of certain plant speciesand, after modifying their salivary secretions,transported into the hive. So propolis is directlyresponsible for ensuring the cleanliness of the hive.Multiple scientific research attributed to propolisantioxidant, antibacterial, antiviral, fungicide, healing,anti-inflammatory, anesthetic,immunomodulatory and antitumor properties.Also in rough investigations it was foundthat propolis acts by inhibiting the activityof Streptococcus mutans, the main producingmicroorganism tooth decay. This led to therealization of this literature review on theproperties and use of propolis in dentistry.

In vitro evaluation of a passive radio frequency identification microchip implanted in human molars subjected to compression forces, for forensic purposes of human identification.

OBJECTIVE: To evaluate the in vitro behavior of a passive Radio Frequency Identification (RFID) microchip implanted in human molars subjected to compression forces to determine its technical and clinical viability. MATERIALS AND METHODS: In vitro experimental study to evaluate the physical behavior of a passive RFID microchip (VeriChip™) implanted in human molars through resin restoration (Filtek P90™ Silorane 3M-ESPE(®)) to determine the clinical and technical possibilities of the implant and the viability to withstand compression forces exerted by the stomatognathic system during mastication. RESULTS: Through the ANOVA test, it was found that the teeth on which a microchip was implanted show great resistance to compressive forces. It was also evident that teeth with microchips implanted in Class V cavities are more resistant than those implanted in Class I cavities. CONCLUSIONS: Although microchip dimensions are big, requiring a sufficiently large cavity, from the biomechanical point of view it is plausible to implant a microchip in a Class V cavity employing restoration material based on resin for forensic purposes of human identification.