ABSTRACT
BACKGROUND: Hydrofluoric acid is a commonly used chemical in many industrial branches, but it can also be found as an ingredient in household products such as cleaning agents. Possessing high corrosive potential, HF acid causes burns and tissue necrosis, while when absorbed and distributed through the bloodstream, its extremely high toxic potential is expressed. Acute symptoms are often followed by pain, particularly in the case of skin burns, which intensiveness does not often correlate with the expressiveness of the clinical findings. Even exposure to low-concentrated solutions or gasses, or low-doses of high-concentrated acid, may provoke delayed systemic disorder which may eventually have a lethal outcome. AIM: Therefore, having information regarding the possible hazardous effects of hydrofluoric acid usage, a variety of symptoms, as well as a treatment approach, is of great importance in the case of HF exposure. METHODS: Available scientific articles published in literature databases, scientific reports and governmental recommendations from the internet websites, written in English, using the following search terms "Hydrofluoric acid, skin burns, eye injury, ingestion, inhalation, systemic toxicity, decontamination, antidote, medical treatment" have been reviewed. RESULTS: This review is useful not only for physicians but for everyone who may come in contact with a person exposed to HF acid. CONCLUSION: It highlights the mechanism of action, presents the acute and chronic symptoms, personal and general protective measures and devices that should be used, as well as decontamination procedures, immediate, antidote and hospital medical treatment.
ABSTRACT
BACKGROUND: The high esthetic expectations from the prosthodontic restorations have directed the qualitative development of the materials towards the all-ceramic materials that are capable of replacing porcelain-fused-to-metal systems. AIM: This article reviews the literature covering the contemporary all-ceramic materials and systems with a focus on the chemical composition and materials' properties; also it provides clinical recommendations for their use. RESULTS: The glass-matrix ceramics and polycrystalline ceramics are presented, as well as recently introduced machinable materials, all-zirconia and resin-matrix ceramics. The specific properties of zirconia, such as transformation toughening, stabilisation of the crystallographic structure, low-temperature degradation and factors affecting the zirconia's ageing, are emphasised. CONCLUSION: The favourable properties of the resin-matrix ceramics, such as modulus of elasticity similar to dentin, shock-absorbing characteristics and high resilience and fracture resistance, are also covered in this article.
ABSTRACT
AIM: The purpose of this review is to represent acids that can be used as surface etchant before adhesive luting of ceramic restorations, placement of orthodontic brackets or repair of chipped porcelain restorations. Chemical reactions, application protocol, and etching effect are presented as well. STUDY SELECTION: Available scientific articles published in PubMed and Scopus literature databases, scientific reports and manufacturers' instructions and product information from internet websites, written in English, using following search terms: "acid etching, ceramic surface treatment, hydrofluoric acid, acidulated phosphate fluoride, ammonium hydrogen bifluoride", have been reviewed. RESULTS: There are several acids with fluoride ion in their composition that can be used as ceramic surface etchants. The etching effect depends on the acid type and its concentration, etching time, as well as ceramic type. The most effective etching pattern is achieved when using hydrofluoric acid; the numerous micropores and channels of different sizes, honeycomb-like appearance, extruded crystals or scattered irregular ceramic particles, depending on the ceramic type, have been detected on the etched surfaces. CONCLUSION: Acid etching of the bonding surface of glass - ceramic restorations is considered as the most effective treatment method that provides a reliable bond with composite cement. Selective removing of the glassy matrix of silicate ceramics results in a micromorphological three-dimensional porous surface that allows micromechanical interlocking of the luting composite.
ABSTRACT
BACKGROUND: The success of prosthetic rehabilitation in patients with removable dentures depends on the achievement of the aesthetics, phonetics and most of all, proper use in the mastication process. All the patients that receive removable prostheses need a feeding education program. They must cut the food into smaller pieces, extend the length of time necessary for chewing and place the food upon both the right and left sides of the mouth at once. Bilaterally chewing with dentures will contribute to increased efficiency and denture stability during mastication. Using the anterior teeth for biting, as a result of increased pressure on the anterior ridge may lead to the anterior hyperfunction syndrome. CASE REPORT: The patient requested dental rehabilitation in our clinic for prosthetic dentistry two and a half years ago. We examined him and made therapy plan, for complete removable maxillary denture and partial mandibular denture. Besides our instructions for proper use of dentures and necessity for regular controls, his next visit was after two and a half years. He came with enlarged tuberosity and papillary hyperplasia in the pre-maxillary region. After oral surgery treatment (laser removing of hyperplastic tissue) and a healing period of four weeks, we made indirect relining on the upper denture, re-occlusion and re-articulation achieving weak contacts between the lower natural teeth and upper teeth of the complete denture. The patient was advised not to bite food with his anterior teeth, and avoid chewing very hard food which tends to imprint and displace dentures. CONCLUSION: Anterior hyperfunction syndrome with its high incidence is a disease with the need of interdisciplinary therapy approach. Fast diagnosis, thorough clinical examination using all available diagnostic tools, and choosing the right treatment is very challenging.
