Studies on a novel combination polymer system: in vitro erosion prevention and promotion of fluoride uptake in human enamel

Enamel Fluoride Uptake Determined Using the Microbiopsy Technique and Time-of-Flight Secondary Ion Mass Spectrometry: A Pilot Study

This study evaluated the suitability of time-of-flight secondary ion mass spectrometry (ToF-SIMS) to assess enamel fluoride uptake (EFU) in comparison with the microbiopsy technique. Enamel specimens were exposed to equimolar solutions of fluoride prepared from sodium fluoride (NaF), stannous fluoride (SnF2), or amine fluoride (AmF). EFU was quantified by both techniques on the same specimens. EFU was found to be highest for samples treated with AmF, followed by SnF2 and NaF. Both methods yielded clearly interpretable, highly correlating (r = 0.95) data. ToF-SIMS can be considered a promising alternative to the microbiopsy technique for near-surface EFU assessment.

Film-Forming Polymers for Tooth Erosion Prevention

Different agents have been proposed to prevent the progression of acid induced dental substance losses, which are called erosive tooth wear (ETW), such as fluorides, calcium, and phosphate-based products; however, there is a need for a further increase in efficacy. Recently, the ability of polymers to interact with the tooth surface, forming acid resistant films, has come into the focus of research; nevertheless, there is still the need for a better understanding of their mode of action. Thus, this article provides an overview of the chemical structure of polymers, their mode of action, as well as the effect of their incorporation into oral care products, acid beverages, and antacid formulations, targeting the prevention of ETW. Recent evidence indicates that this may be a promising approach, however, additional studies are needed to confirm their efficacy under more relevant clinical conditions that consider salivary parameters such as flow rate, composition, and clearance. The standardization of methodological procedures such as acid challenge, treatment duration, and combination with fluorides is necessary to allow further comparisons between studies. In conclusion, film-forming polymers may be a promising cost-effective approach to prevent and control erosive demineralization of the dental hard tissue.

Polymer-Based Carriers in Dental Local Healing-Review and Future Challenges

Polymers in drug formulation technology and the engineering of biomaterials for the treatment of oral diseases constitute a group of excipients that often possess additional properties in addition to their primary function, i.e., biological activity, sensitivity to stimuli, mucoadhesive properties, improved penetration of the active pharmaceutical ingredient (API) across biological barriers, and effects on wound healing or gingival and bone tissue regeneration. Through the use of multifunctional polymers, it has become possible to design carriers and materials tailored to the specific conditions and site of application, to deliver the active substance directly to the affected tissue, including intra-periodontal pocket delivery, and to release the active substance in a timed manner, allowing for the improvement of the form of application and further development of therapeutic strategies. The scope of this review is polymeric drug carriers and materials developed from selected multifunctional groups of natural, semi-synthetic, and synthetic polymers for topical therapeutic applications. Moreover, the characteristics of the topical application and the needs for the properties of carriers for topical administration of an active substance in the treatment of oral diseases are presented to more understand the difficulties associated with the design of optimal active substance carriers and materials for the treatment of lesions located in the oral cavity.

Protective Effect of Solutions Containing Polymers Associated with Fluoride and Stannous Chloride on Hydroxyapatite Dissolution

This study investigated the protective effect of experimental solutions containing 4 polymers (polyoxirane, hydroxypropylmethylcellulose [HPMC], pectin, and an amino methacrylate copolymer [AMC]) in 2 concentrations (low and high) associated or not with sodium fluoride (F; 225 ppm F-) or sodium fluoride plus stannous chloride (FS; 800 ppm Sn2+) on the dissolution of hydroxyapatite crystals (HA). Deionized water was the control. The pretreated HA was added to a 0.3% citric acid solution (pH 3.8). An automatic titrant machine added aliquots of 0.1 N HCl at a rate of 28 μL/min, in a total reaction time of 5 min. Groups were compared with 2-way ANOVA and Tukey's test, and concentrations with Student t test (5%). The zeta potential of the HA treated with the solutions was measured. Significant differences were found for both factors and interaction (p < 0.0001). The treatments with F and FS solutions resulted in a lower amount of dissolved HA than the control. Among the polymers' solutions, only AMC was able to reduce the amount of dissolved HA, changing the surface charge of HA to positive. AMC improved the protective effect of F, but it did not affect FS. Polyoxirane and HPMC reduced the protective potential of the FS solution. No differences were found between the concentrations of the polymers. It was concluded that F and FS reduced the amount of dissolved HA. The protective effect of the experimental solutions against HA dissolution was polymer dependent. The F effect was enhanced by its combination with AMC, but the protection of FS was impaired by polyoxirane and HPMC.

Polymeric materials and films in dentistry: An overview

The use of polymeric materials (PMs) and polymeric films (PMFs) has increased in medicine and dentistry. This increasing interest is attributed to not only the excellent surfaces of PMs and PMFs but also their desired mechanical and biological properties, low production cost, and ease in processing, allowing them to be tailored for a wide range of applications. Specifically, PMs and PMFs are used in dentistry for their antimicrobial, drug delivery properties; in preventive, restorative and regenerative therapies; and for corrosion and friction reduction. PMFs such as acrylic acid copolymers are used as a dental adhesive; polylactic acids are used for dental pulp and dentin regeneration, and bioactive polymers are used as advanced drug delivery systems. The objective of this article was to review the literatures on the latest advancements in the use of PMs and PMFs in medicine and dentistry. Published literature (1990–2017) on PMs and PMFs for use in medicine and dentistry was reviewed using MEDLINE/PubMed and ScienceDirect resources. Furthermore, this review also explores the diversity of latest PMs and PMFs that have been utilized in dental applications, and analyzes the benefits and limitations of PMs and PMFs. Most of the PMs and PMFs have shown to improve the biomechanical properties of dental materials, but in future, more clinical studies are needed to create better treatment guidelines for patients.

Comparative evaluation of surface properties of enamel and different esthetic restorative materials under erosive and abrasive challenges: An in vitro study

Introduction:

Noncarious tooth surface loss is a normal physiological process occurring throughout the life, but it can often become a problem affecting function, esthetics or cause pain.

Aim:

The purpose of this study was to assess the effect of erosive and abrasive challenges on the surface microhardness and surface wear of enamel and three different restorative materials, that is, nanofilled composite, microfilled composite and resin-modified glass ionomer cement (RMGIC) by using Vickers microhardness tester and profilometer respectively.

Subjects and Methods:

Nanofilled composite (Filtek^™ Z350 × T), microfilled composite (Heliomolar^®) and RMGIC (Fuji II LC) were used in the study.

Results:

Nanofilled composite resin has the best resistance to erosion and/or abrasion among all the materials tested, followed by microfilled composite and RMGIC respectively.

Conclusion:

Toothbrush abrasion has a synergistic effect with erosion on substance loss of human enamel, composites, and RMGIC. The susceptibility to acid and/or toothbrush abrasion of human enamel was higher compared to restorative materials.

Effect of Acidic Solution Viscosity on Enamel Erosion

The objective of this in vitro study was to investigate the effects of viscosity changes of different acidic solutions on dental erosion. Bovine enamel samples (n = 240, Ø = 3 mm) were embedded in acrylic resin and were allocated to 30 groups (n = 8). Citric acid (CA) and phosphoric acid (PA) solutions at pH 2.5, 3, and 3.5 were prepared in de-ionized water (titratable acidity to pH 5.5: 31 ± 0.6 mmol OH-/l). The kinetic viscosities of the acidic solutions were adjusted to 1.5, 3, 6, 12, and 24 mm2/sec by the addition of hydroxypropyl cellulose (HPC) at different concentrations. Solutions were pumped over the enamel surface from a reservoir with a drop rate of 1 mL/min. Each specimen was eroded for 10 min at 20°C. Erosion of enamel surfaces was measured by profilometry. Data were analyzed by analyses of variance and logarithmic regression analyses ( p < 0.05). Enamel loss was dependent on viscosity, pH, and the kind of acid. The regression analyses showed that higher viscosity caused lower enamel erosion for both acids and all pH levels. Dental erosion is dependent not only on chemical factors of the acid, like pH and acid type, but also on acid viscosity.

Chitosan adsorption on hydroxyapatite and its role in preventing acid erosion

Polymer adsorption onto an artificial saliva (AS) layer is investigated using quartz-crystal microbalance with dissipation (QCM-D) and chitosan as the model polymer. QCM-D is utilized in an innovative manner to monitor in situ adsorption of chitosan (CH) onto a hydroxyapatite (HA) coated crystal and to examine the ability of the adsorbed layer to "protect" the HA upon sequential exposure to acidic solutions. After deposition of a thin AS layer (16 nm), the total thickness on the HA substrate increases to 37 nm upon exposure to CH at pH 5.5 for 10 min. Correspondingly, the surface charge changes from negative (i.e., AS) to positive, consistent with the adsorption the polycationic CH onto or into the AS layer. Upon exposure to an oxidizing agent, the chitosan cross-links and collapses as noted by a decrease in thickness to 10 nm and an increase in the shear modulus by an order of magnitude. Atomic force microscopy (AFM) is used to determine the surface morphology and RMS roughness of the coated and HA surfaces after citric acid challenges. Both physisorbed and cross-linked chitosan are demonstrated to limit and prevent the erosion of HA, respectively.