Background: Esthetic correction represents one of the clinical conditions that required the use of laminate veneers in premolars region. Aim of the study: The purpose of this study was to evaluate the fracture strength of the laminate veneers in maxillary first premolars, fabricated from either composite (direct and indirect techniques) or ceramic CAD/CAM blocks. Materials and Methods: Fifty sound human maxillary premolar teeth were used in this in vitro study. Teeth were divided randomly into one control group and four experimental groups of ten teeth each; Group A: Restored with direct composite veneer (Filtek Z250 XT), Group B: Restored with indirect composite veneers (Filtek Z250 XT), Group C: Restored with lithium disilicate ceramic CAD/CAM blocks (IPS e. max CAD) and Group D: Restored with resin nano ceramic CAD/CAM blocks (Lava Ultimate Restorative). Standard preparations were done using Ceramic Veneer Set (Komet). Indirect laminate veneers were cemented with the Relyx Veneer Cement (3M ESPE) and all specimens were stored in distilled water at 37°C for 2 weeks. The load was applied on the occlusal part of the veneer at 45˚ to long axis of the tooth using universal testing machine. Results were analyzed with one-way ANOVA and LSD tests. Specimens were examined by stereomicroscope at a magnification of 20x to evaluate the mode of failure. Results: Control group showed higher mean of fracture strength with highly significant difference in comparison to the experimental groups (P<0.01). (Group A) showed higher mean of fracture strength with statistically significant difference in comparison to (Group B and Group D). On the other hand the difference between (Group A and Group C) was statistically highly significant. Statistically non-significant difference was found among the three indirectly restored groups. Conclusions: All veneers used in this study can be considered as acceptable treatment in the premolars region for patients with normal biting force. Direct composite veneer is the most favorable technique in term of fracture strength, while IPS e. max CAD laminate veneers were least likely to fracture and most likely to completely debond.
Density Functional Theory (DFT) calculations were carried out to study the thermal cracking for acenaphthylene molecule to estimate the bond energies for breaking C8b-C5a , C5a-C5 , C5-C4 , and C5-H5 bonds as well as the activation energies. It was found that for C8b-C5a , C5-C4 , and C5-H5 reactions it is often possible to identify one pathway for bond breakage through the singlet or triplet states. The atomic charges , dipole moment and nuclear – nuclear repulsion energy supported the breakage bond .Also, it was found that the activation energy value for C5-H5 bond breakage is lower than that required for C8b-C5a , C5a-C5 , C5-C4 bonds which refer to C5-H5 bond in acenaphthylene molecule are weaker than C8b-C5a , C5a-C5 , C5-C
... Show MoreLiquid-side mass-transfer coefficients (KLa) were measured in air-suction type fermentors using physical absorption of oxygen. A fermentor of 0. 5 m i.d. was used with a working capacity of 60 liters of liquid. Tap water was used as the liquid phase, and air was used as the gas phase. The bioreactor mixing system consists of shrouded-disk/curved-blade turbine with six evacuated bending blades. The effect of liquid submergence (S) was investigated. Further, the effects of the ratio of the impeller diameter (D) to the tank diameter (T), and the clearance of the impeller from the tank bottom(C) were also studied. The agitation speed (N) was varied in the range of 50-800 rpm. It was found that the value of K
... Show MoreThe book gives details about the healing power of love
Although the profession of a marriage mediator is dominated by a social character, and it is also characterized by its practice in the midst of strict secrecy, because Eastern societies innately reject this method of searching for a life partner. The two parties play a prominent role of the will in the events of legal effects, and the obligations and rights owed by the contracting parties, which leads us to consider the agreement between the mediator and the one who wants to marry going to the purely contractual nature, and thus requires the correct legal adaptation on the contractual relationship that is achieved between the marriage mediator and his clients from Those who want to get married and therefore we will divide this research into
... Show MoreThe family Pholcidae represented by the species Artema doriae )Thorell, 1881) is recorded in Iraq for the first time.So far, 23 families of spiders have been recorded in Iraq.
In this paper, we add a new family and a description of a species belonging to this family in the checklist of Iraqi spider fauna.
Alzheimer’s disease (AD) is an age-related progressive and neurodegenerative disorder, which is characterized by loss of memory and cognitive decline. It is the main cause of disability among older people. The rapid increase in the number of people living with AD and other forms of dementia due to the aging population represents a major challenge to health and social care systems worldwide. Degeneration of brain cells due to AD starts many years before the clinical manifestations become clear. Early diagnosis of AD will contribute to the development of effective treatments that could slow, stop, or prevent significant cognitive decline. Consequently, early diagnosis of AD may also be valuable in detecting patients with dementia who have n
... Show MoreThis study investigated the effect of applying an external magnetic field on the characteristics of laser-induced plasma, such as its parameters plasma, magnetization properties, emission line intensities, and plasma coefficients, for plasma induced from zinc oxide: aluminum composite (ZO:AL) at an atomic ratio of 0.3 %. Plasma properties include magnetization and emission line intensities. The excitation was done by a pulsed laser of Nd:YAG with 400 mJ energy at atmospheric pressure. Both the electron temperature and number density were determined with the help of the Stark effect principle and the Boltzmann-Plot method. There was a rise in the amount of (ne) and (Te) that was produced
... Show MoreWith the exception of Antarctica, all continents are home to Echinococcus species. These parasite infections are thought to be quite dangerous, causing high rates of morbidity and mortality as well as large financial losses for the cattle sector from a human and veterinary standpoint, the two primary species to consider are Echinococcus granulosus sensu lato (s.l.) and Echinococcus multilocularis, which cause cystic echinococcosis (CE) and alveolar echinococcosis (AE), respectively. The present state-of-the-art knowledge on these two parasites is compiled in this study in four major areas that are pertinent to both human and veterinary professionals: diagnosis, treatment and prevention, clinical symptoms and pathogenesis, and transm
... Show MoreAbstract: To study the effect of nickel chloride on bone composition of mice, a number of biophysical and biochemical parameters have been made use. The animals were divided into control and experimental and further subdivided into three groups I, II and III according to the dose of nickel chloride (NiCl2) administered to them i.e. 5.8, 12.8 and 28.2 mg/kg body weight, respectively. Femur bones were obtained by sacrificing the animals three weeks after weaning them once a week. The percentage loss between the wet weight and dry weight of femur in control animals was found to be 32.5+1.5 .In the three experimental groups I,II and III, the percentage loss was 30.4+1.4, 35.3+2.3 and 38.9+2.2 respectively. The percentage loss between the wet we
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