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@#The concept of “minimally invasive dentistry” aims to provide conservative treatment of cavities in which sound dentin is removed. Because the Er: YAG laser can selectively remove caries, the smear layer is removed, dentin tubules are exposed after the preparation of substrate conditioning, and its advantages of precision, safety and painlessness are deeply valued. At the same time, the bonding strength between the prepared dentin surface and the filling material is different due to the different parameters of the Er: YAG laser. In this paper, the principle of dentin bonding, the mechanism of Er: YAG laser action, after treatment of dentin with different parameters (power, energy density, pulse duration, and irradiation distance), whether there is thermal damage to pulp tissue, the ultramicro morphology of dentin surface, the bonding properties of different bonding systems and the filling materials between irradiated hard tissues were reviewed. An appropriate parameter range (power ≤ 10 Hz, energy density ≤ 60 mJ, and pulse duration ≤ 50 μs) combined with water spray cooling will not cause thermal damage to the pulp tissue, while the higher power, energy density and pulse duration of laser treatment for dentin will lead to melting, carbonization, cracks, narrowing of the gap between collagen fibers, etc., which will limit the penetration of adhesives and have a negative impact on bonding. However, whether the adhesive systems based on the smear layer are suitable for dentin after laser treatment needs to be further explored.
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OBJECTIVE@#This study aimed to compare the effect of D55 and D65 light sources on the visual colorimetry performance of dental students by using a homemade light-source shelf.@*METHODS@#Two Vitapan 3D-Master shade guides were randomly selected. One set was used as shade guides. Ten commonly used shade tabs of 2L2.5, 2M2, 2R2.5, 3M2, 3R2.5, 3L1.5, 3R1.5, 3L2.5, 4R1.5, and 4L1.5 were selected from the other set with covered value marks and numbered from 1 to 10. After the colorimetric training, 49 undergraduate dental students were randomly divided into two groups. Each student randomly selected two of the 10 shade tabs, and the colors were subsequently matched under D65 and D55 light sources from a distance of approximately 40 cm. The average color difference (ΔE) between the color selected by each participant and the actual color of shade tabs was calculated. Paired t test was used for statistical analysis.@*RESULTS@#The ΔE values between the color selected by each participant and the actual color of the shade tabs under the D55 light source varied from 0 to 6.540. The average value was 2.501. The ΔE values between the color selected by each participant and the actual color of the shade tabs under the D65 light source varied from 0 to 6.610. The average value was 2.530. No statistically significant difference was observed between the results under the two light sources (P=0.921).@*CONCLUSIONS@#Both D55 and D65 daylight lamps can be used for daily dental colorimetry. These two different color temperatures showed no significant difference.
Assuntos
Humanos , Cor , Colorimetria , Planejamento de Prótese Dentária , Pigmentação em Prótese , Estudantes de OdontologiaRESUMO
@#Unilateral maxillary defects are common clinical maxillofacial deformities. Because of their large area and the complexity of the maxillary structure, the distribution of pressure from dental prostheses and on the sustentacular tissue is usually uneven, which often results in pain or ulceration of the soft tissue and agomphiasis during the therapeutic process. Recently, the finite element method has been used to guide prosthesis design and implantation. This method is conducive to the restoration and stability of the dental prosthesis and the protection of the remaining tissue, which improves restoration quality and patient satisfaction. This paper summarizes the establishment of a three-dimensional finite element model of unilateral maxillary defects and its application in repairing unilateral maxillary defects with traditional prostheses, implant-supported prostheses and surgical flap transplantation combined with prostheses.
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@#It is the key step of the occlusal reconstruction to determine the correct occlusal vertical dimension for edentulous patients. Although there are several methods in clinical practice, there is no ideal way. This paper summarizes the following methods: inter-occlusal distance, closest speaking space method, pre-extraction record, face proportion division method and facial appearance observation, cephalometric analysis, electromyography, swallowing, bite force determination and self feeling method. In this paper, the current research status and the feasibility of each method are discussed.