Digital impression devices are used alternatively to conventional impression techniques and materials. The aim of this study was to evaluate the precision of extraoral digitalization of three types of photosensitive resin polymers used for 3D printing with the aid of a digital extraoral optical scanner. The alignment of the scans was performed by a standard best-fit alignment. Trueness and precision were used to evaluate the models. The trueness was evaluated by using bias as a measure and the standard deviation was used to evaluate the precision. After assessing the normality of the distributions, an independent Kruskal–Wallis test was used to compare the trueness and precision across the material groups. The Mann–Whitney test was used as a post-hoc test for significant differences. The result of the analysis showed significant differences (U = 66, z = −2.337, p = 0.019) in trueness of mesiodistal distances. Upon visual inspection of the models, defects were noticed on two out of nine of the models printed with a photosensitive polymer. The defects were presented as cavities caused by air bubbles and were also reflected in the scans. Mean precision did not vary too much between these three photosensitive polymer resins, therefore, the selection of 3D printing materials should be based on the trueness and the required precision of the clinical purpose of the model.
Childhood and adolescence include periods of growth in which the pediatrician meets multiple challenges in terms of cooperation, compliance with treatment, and the patient�s family, thus constituting the pedodontic triangle. The importance of long-term patient monitoring should not be neglected, especially for those in the stage of growth and development of temporary or permanent dentition, when a real cascade of bad events can be triggered. Mobile dental appliances with the indication to be worn both day and night, less during meals and when tooth cleaning is taking place. They are used for a relatively short period as part of a wider treatment plan. The efficiency of an orthodontic appliance is appreciated by the possibilities it offers to reach the desired result in a minimum treatment time, without affecting the biological integrity of the substrate on which it operates. Ortodontic mobilisable devices used to correct dento-maxillary abnormalities, requires plates with orthodontic force, retention and anchoring. If these are used as contention devices, is needed only retention. Study group regards the selection, examination and orthodontic treatment of 46 cases at the Orthodontic Clinic of the University of Medicine and Pharmacy T�rgu Mure� between 2014-2016.The study deals with the theoretical aspects regarding biomechanics and the principles of orthodontic treatment and at the same time represents a synthetic exposure characteristics of the orthodontic devices, considering the development of new techniques. Orthodontic treatment begins in childhood, around the age of 6 years old or when the child has 4-6 milk teeth, when we already can see problems in growing of jaw and permanent teeth.
Magnesium alloys are considered one of the most promising materials for biodegradable trauma implants because they promote bone healing and exhibit adequate mechanical strength during their biodegradation in relation to the bone healing process. Surface modification of biodegradable magnesium alloys is an important research field that is analyzed in many publications as the biodegradation due to the corrosion process and the interface with human tissue is improved. The aim of the current preliminary study is to develop a polymeric-based composite coating on biodegradable magnesium alloys by the solvent evaporation method to reduce the biodegradation rate much more than in the case of simple polymeric coatings by involving some bioactive filler in the form of particles consisting of hydroxyapatite and magnesium. Various techniques such as SEM coupled with EDS, FTIR, and RAMAN spectroscopy, and contact angle were used for the structural and morphological characterization of the coatings. In addition, thermogravimetric analysis (TGA) was used to study the effect of filler particles on polymer thermostability. In vitro cytotoxicity assays were performed on MG-63 cells (human osteosarcomas). The experimental analysis highlights the positive effect of magnesium and hydroxyapatite particles as filler for cellulose acetate when they are used alone from biocompatibility and surface analysis points of view, and it is not recommended to use both types of particles (hydroxyapatite and magnesium) as hybrid filling. In future studies focused on implantation testing, we will use only CA-based composite coatings with one filler on magnesium alloys because these composite coatings have shown better results from the in vitro testing point of view for future potential orthopedic biodegradable implants for trauma.
Genetics is a key discipline in medicine, but also a clinical discipline with medical and social implications. The interest in reducing the number of genetic disorders and recognizing the risk of them repeating when a family confronts itself with a genetic anomaly becomes more and more important in the hierarchy of prophylactic emergencies. Presenting themselves as metabolic diseases (monogenic mutations) or malformations (polygenic and multifactorial heredity) because of their frequency, these disorders position themselves on an ascendant curve. They become difficult to deal with for the society, for the family and for the interested individual and cause emotional disorders. The Down syndrome is the most frequent type of genetic disorder. It is characterized by a specific set of signs and symptoms. People with Down syndrome require special medical care that, apart from the family, must include a team of doctors of various specializations and also a dentist. They are predisposed to hearing and sight disorders and thyroid problems as well. In 50% of the cases there are also anomalies of the heart, and the risk of leukaemia is 20 times higher. Some of them even develop an Alzheimer type dementia during their life. The people with Down syndrome can have an average IQ up to a moderate form of handicap. In particular, the studies on Down syndrome in dentistry are quite frequent, but they focus more on cavities, periodontal disease and hypodontia. In spite of this, the connection of Down syndrome and dental eruption is less studied. Consequently, the present study is intended to fill this missing part from the specialized literature, focusing on the relation between the Down syndrome and the chronological and dental ages in children. The health of the oral cavity is neglected in these patients, their parents focusing more on the treatment of the other systemic disorders of their children; the lack of interest is reflected in their poor oral hygiene.The trial group included 94 children with mixt dentition, aged between 6 and 12, divided as follows: 36 children with Down syndrome enrolled at the Educational Centre for Inclusive Education no. 1 of Tg. Mures and Alpha Transilvana Foundation. The chronology and the eruption sequences are subjected to certain variations and they are influenced by the presence of cavities, the premature loss or, on the contrary, the prolonged retention of deciduous teeth as well as dental anchylosis. Dental maturation is less subjected to variations, as it is a progressive, continuous and cumulative process. The presence of Down syndrome in children generates a delay in teeth eruption by 1.27 years compared to the data identified in the specialized literature and to the information obtained on the healthy children included in the study.
Additive manufacturing is a technology that has many uses across a variety of fields. Its usage spans many fields, including the fields of art, design, architecture, engineering and medicine, including dentistry. The study aims to evaluate and compare the accuracy of three-dimensional printed dental models based on ethylene di-methacrylate using the SLA and DLP techniques. For evaluation, a reference model containing 16 maxillary permanent molars was chosen. An ATOS Capsule 3D scanner was used to scan the reference model. Using a photo-cured liquid resin, eight three-dimensional printed models were obtained using the reference model as benchmark. Four of the models (A1–A4) were obtained using SLA printing technology and four models (B1–B4) were manufactured using DLP printing technology. A standard best fit method was used to pre-align the reference and the printed model surfaces. The height of the teeth, and the mesial–distal and buccal–lingual distances were analyzed. The assessment of the two manufacturing methods was achieved by using non-parametric tests to compare the mean ranks for the assessed features. The results show that models obtained through DLP had a higher precision but also a higher bias. Both methods still are within the required accuracy range for dental models.
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