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.

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.

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.

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Introduction: Nasopharyngeal obstruction is an important etiologic factor in the development of an extreme vertical growth facial pattern, and insufficient transversal growth of the maxilla. The treatment outcomes associated with rapid maxillary expansion in the literature are mainly discussed in terms of changes in dentofacial morphology, without special reference to changes in the pharyngeal airway, the position of the mandible, hyoid bone and the tongue.

Introduction: Nasopharyngeal obstruction is an important etiologic factor in the development of an extreme vertical growth facial pattern, and insufficient transversal growth of the maxilla. The treatment outcomes associated with rapid maxillary expansion in the literature are mainly discussed in terms of changes in dentofacial morphology, without special reference to changes in the pharyngeal airway, the position of the mandible, hyoid bone and the tongue.

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Introduction:A complete or partial absence of an X chromosome in the karyotype of phenotypic females has an impact on craniofacial morphology. The aim of this study was to determine the characteristics of the craniofacial complex in patients with Turner syndrome (TS), and to evaluate the influence of various karyotypes on craniofacial morphology. Materials and methods:The study population was comprised of 40 TS female patients, aged 9.2 to 18 years, and 40 healthy females, aged 9.3 to 18 years, as the control group. The TS patients were subdivided according to karyotype. All study participants were evaluated cephalometrically. An analysis of variance (ANOVA) and Tukey's multiple comparison test were used for analysis of the differences between the means in Turner subgroups and the control group.Results: In general, the girls with TS were characterized by smaller dimensions and an altered morphology of the craniofacial complex compared with the unaffected girls. The curvature of the frontal bone was significantly increased, while the diameter of the head was reduced. Both the maxilla and mandible were retrognathic, posteriorly rotated, and reduced in antero-posterior length. The cranial base was shorter and flattened. Among the different karoytypes, no significant differences were determined in the dimensions of the craniofacial complex in girls with TS. Conclusions:Our findings indicate that the karyotype has no effect on craniofacial morphology and we confirmed that a specific model of craniofacial morphology in individuals with TS is present in early childhood. is approximately one in 2,500 girls. 4 Several karyotypes responsible for the syndrome have been identified, the most common being monosomy X, found in about 50-60% of the girls. Less common are the mosaic and isochromosome for the long arm of the X chromosome.5,6 Short stature, gonadal dysgenesis, pterygium colli, cubitus valgus, and low hairline at the back of the neck are the most common features of this disease. 7The smaller size of teeth in individuals with TS 8-12 is caused by reduced enamel thickness. 13,14 Females with TS have a tendency toward distal molar occlusion, lateral crossbite, and open bite. 8,15,16 Skeletal maturity was retarded by an average of 2.2 years