Mohammad Hashem Hosseini; Ardavan Etemadi; Fatemeh Gorjizadeh
Abstract
Background: Application of zirconia in dentistry has increased due to its good properties. Since zirconia is not possible to be etched, evaluation of the other methods of surface treatment is important.
Objectives: The aim of this study was to evaluate zirconia surfaces treated by different output powers ...
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Background: Application of zirconia in dentistry has increased due to its good properties. Since zirconia is not possible to be etched, evaluation of the other methods of surface treatment is important.
Objectives: The aim of this study was to evaluate zirconia surfaces treated by different output powers of Er: YAG laser and sandblasting technique by scanning electron microscope (SEM). Materials and Methods: 15 specimens were prepared of 3Y-TZP ceramic material. After polishing of all the samples, divided into 5 groups; control group, 1.5 W Er: YAG laser irradiated group, 2.5W Er: YAG laser irradiated group, 3.5 W Er: YAG laser irradiated and sandblasted group. Then SEM image of each group were prepared and analyzed. Results: The SEM images of study groups showed there is no significant difference between control group and laser groups at × 3000, but at the more magnifications (× 15000 and × 60000), with increasing laser power, surface roughness and deformation of crystals increases. SEM of Sandblasted group showed a change in surface texture with the formation of microretentive grooves and deformation of zirconia crystals shape.
Conclusions: By increasing the Er: YAG laser power on zirconia ceramics, the surface roughness increases but not impressive. Application of sandblasting technique on zirconia provides greater surface roughness than Er: YAG laser treatment. 1.5 W (150 mJ) Er: YAG laser radiation has no significant effect on surface morphology of zirconia but 2.5 W (250 mJ) and 3.5 W (350 mJ) outputs, change the surface morphology.
Navid Naseri; Pedram Baghaeian; Maryam Javaherimahd; Fatemeh Gorjizadeh
Abstract
Background: It has been proved that, there's craniofacial asymmetry but much of this skeletal asymmetries are clinically ignorable. This asymmetry may exist in teeth size arranged in right and left sides of human mouth too. Orthodontists should pay attention to bilateral tooth asymmetry in treatment ...
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Background: It has been proved that, there's craniofacial asymmetry but much of this skeletal asymmetries are clinically ignorable. This asymmetry may exist in teeth size arranged in right and left sides of human mouth too. Orthodontists should pay attention to bilateral tooth asymmetry in treatment planning stage.
Objectives: This study was conducted to demonstrate whether the difference between size of left and right side teeth is actual. Materials and Methods: A total of 200 plaster dental molds were used which were collected from a private practice in Tehran. A caliper with accuracy of 0.01 mm was used for measuring teeth and most teeth were measured twice and the average value was considered as the teeth size. In all cases, the Vernier calipers jaws were moved along the teeth longitudinal axis and the biggest width was measured in the contact point area. Results: In average 83.16% of left and right teeth in upper jaw and 83.66% of left and right teeth in the lower jaw were not symmetrical and teeth in the upper and lower jaws were completely similar 16.84% and 16.34%, respectively.
Conclusions: The result of the study showed that nearly 83% of teeth in maxilla and mandible are asymmetric in mesiodistal width. Mandibular second molar and canine showed the highest and lowest bilateral asymmetry respectively.
Tahereh Hosseinzadeh Nik; Fatemeh Gorjizadeh
Abstract
Hemifacial macrosomia (HFM) is the second most common facial congenital anomaly. Deficiency of hard and soft tissue on one side of the face is its obvious clinical finding, which can cause facial asymmetry. Hemifacial microsomia is described in three grades of severity, although grade II has two subgroups ...
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Hemifacial macrosomia (HFM) is the second most common facial congenital anomaly. Deficiency of hard and soft tissue on one side of the face is its obvious clinical finding, which can cause facial asymmetry. Hemifacial microsomia is described in three grades of severity, although grade II has two subgroups (mild and severe). Many anomalies can be misdiagnosed with different grades of Hemifacial microsomia, e.g. Treacher Collins syndrome, traumatic postnatal deformity, Goldenhar syndrome, hemi mandibular elongation, Parry-Romberg syndrome, juvenile rheumatoid arthritis, Nager acrofacial dysostosis syndrome, post axial acrofacial dysostosis, muscle dysfunction, branchio-oto-renal syndrome and Maxillofacial dysostosis. The first step to treating patients with HFM, is an accurate diagnosis. Decision making for treatment planning of patients with HFM, is highly dependent on the severity of the deformity and patients age. In mild grades of the anomaly, functional therapy can improve facial and occlusal symmetry when they are young, but in more severe grades, imposition of orthopedic treatment, may be undesirable and waste of time. Early surgical interventions to encourage the growth in the affected condyle may be helpful in severe cases; however, consultation with the surgeon is advised to determine the patients who need early surgery. Distraction osteogenesis is a controversial treatment modality, which still needs more long-term studies.
