RESUMEN
OBJECTIVE: The aim of this research is to study the influence of size and location of wedge-shaped defects of teeth on stress and strain state of restorative material on the basis of biomechanical analysis. PATIENTS AND METHODS: Materials and methods: Biomechanical analysis of the stress-strain state was performed on a jaw bone fragment with canine and premolar inclusion. RESULTS: Results: Tangential stress increase both in the adhesive layer and in restorative material with depth and width (medial-distal size) of restored wedge-shaped defects of teeth,.The most unfavorable loading on a tooth is a joint action of vertical and horizontal loading in lingual- vestibular or vestibular-lingual direction, depending on localization of the restored wedge-shaped defects of teeth. The formation of retention grooves in wedge-shaped defects of teeth reduces the value of the maximum tangential stress in the adhesive layer of restorative material to 25% and extends the longevity of restorations. CONCLUSION: Conclusions: The difference in maximal values of tangential stress increases in adhesive layer of restorative material with or without retention grooves with increasing depth of defect. Thus, it is advisable to form retention grooves in cases of wedge-shaped teeth defects that exceed 1.5 mm. In case of restoration of subgingival wedge-shaped defects of teeth of small height it is recommended to create one retention groove on the gingival or incisal planes of a carious cavity due to significant inconveniences, and sometimes impossibility of formation of traditionally located retention grooves.
Asunto(s)
Resinas Compuestas , Diente Premolar , Análisis de Elementos FinitosRESUMEN
OBJECTIVE: The aim of out research was to determine the effectiveness of the sealing property of adhesive systems V and VII generations by studying the depth of curing, water absorption and water solubility of their samples. PATIENTS AND METHODS: Materials and methods: The study was performed according to ISO / TS 11405: 2015 at the Central Factory Laboratory of JSC "CTOMA", Kharkiv, Ukraine, Certificate of Attestation No. 100-062 / 2015 dated 03/04/2015. For the study we used specially prepared laboratory samples which were made in the form of plates from adhesive system "DC Adhesive NF" (Dental Central) of V generation "Single bond Universal" (3M ESPE) of VII generation. Ð monitor and analyze the results obtained used micrometer MK-25, â4694, â03 / 5321 from 08/18/17; caliper SC-1, No. 267447, No. 03/5322 from 08/18/17; scales AP 210, â112144137, â87027 / 9 from 24.11.2017. RESULTS: Results: According to the results of the investigation the following results were obtained: 1) the average curing depth of V and VII generation of adhesive systems was 4.08mm and 3.51mm respectively at the rate of 2mm; 2) average water absorption: 45.97 µg/mm3 and 30.89 µg/mm3 for V and VII generations respectively; 3) the average water solubility was 6.94 µg / mm3 and 4.17 µg / mm3, respectively. CONCLUSION: Conclusions: According to the results of our laboratory studies, it can be concluded that adhesive systems of V and VII generations can be used for restoration of lesions of tooth hard tissued. Along with this, it can be recommended to use V generation adhesives in closed defects where direct polymerization should be performed and oral fluid access is minimal. Adhesive sysyems of VII generation can be recommended in such cases as: opened restorations, pregingival areas of teeth, cases where a permanent contact of restorations with oral fluid be found along with the cases of autonomic application of adhesive system.
Asunto(s)
Cementos Dentales , Agua , Ensayo de Materiales , UcraniaRESUMEN
OBJECTIVE: Introduction: The condition of hard teeth tissues while choosing treatment method becomes particularly important due to the large development of adhesive technologies and the choice of filling materials. The quality of adhesion is one of the key factors that affects effectiveness of the entire range of therapeutic interventions, that determines the success of therapeutic treatment and the reliability of therapeutic restorations fixation. The aim of the work is to study the condition of hard teeth tissues in carious and non-carious pathology for further rationale of the choice of filling material and adhesive system. PATIENTS AND METHODS: Materials and methods: A thorough examination included teeth that were removed according to the indications. The age of patients, whose teeth were examined, was 25-55 years old according to the classification of age periods adopted at the International Symposium on the Age Periodization (Moscow, 1965). We conducted a morphological study of enamel and dentin of teeth with carious and non-carious lesions (increased erasability, cuneal defects), by obtaining chips and microsections of teeth, followed by examination of the number of enamel prisms, dentinal tubules,their diameter, the thickness of the gaps between these structures. The studies were carried out using a scanning electron microscope (SEM) "Mira 3 LMU" ("Tescan", Czech Republic) with a maximum resolution of 1 nm and a maximum magnification of 1,000,000. Dentally removed teeth were washed in running water, cleaned of plaque, dried by filter paper and crushed by vice, that was followed by the selection of the wreckage for the study. Then, markings in the dentine and enamel zones were made to fix the sizes of enamel prisms and dentinal tubules. RESULTS: Results: After the completion of the determination of enamel prisms and dentinal tubules diameter, counting of their number was carried out according to the method proposed by I.M. Tkachenko, by obtaining a series of digital images of the examined tooth's enamel and dentin with varying degrees of magnification. The number of prisms per unit area characterized the enamel density, on which permeability, hardness, tissue resistance to fracture, bending and modulus of elasticity depends. The number of dentinal tubules characterized the density of dentin and the peculiarities of trophic processes that occur in dentin. Also, in our opinion, the amount of dentinal tubules determines the damping properties of dentin and strength enamel values. CONCLUSION: Conclusions: Thus, the structure of enamel and dentin has peculiarities of the morphological structure at various clinical conditions of hard teeth tissues. This peculiarity can be associated with a decrease of enamel density, that is associated with a decrease in the number of prisms in the non-carious teeth pathology and an increase of the gaps between them.