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1. Shade matching should be done within how much second to avoid fatigue of eyes to colour
- 5
- 10
- 15
- 20
ANSWER a
- Shade guides are used to match with the natural tooth structure that comprise of a set of standard or independently fabricated shades.
- Shade guides can be classified on the basis of material from which they are made, such as composite resin based, acrylic based and ceramic based.
- Generally, shade guides should have a full range of natural color for dental structures.
- As a general standard, each shade tab is composed of an incisal, middle and cervical part that varies in shade on the basis of translucency and color density.
- In prosthetic dentistry, selection of shade is a significant phase in all directions, which, later on, is delivered to the laboratory technician to fabricate indirect restoration.
- Presently, there are a number of accessible shade guides applied in the clinical practice of dentistry: Vita classical (Bad Säckingen, Germany: VITA Zahnfabrik H. Rauter GmbH & Co.), Vita Tooth guide or 3DMaster shade guide (Bad Säckingen, Germany: VITA Zahnfabrik H. Rauter GmbH & Co.) and Chromascop (Buffalo, NY, USA: Ivoclar Vivadent Inc.). They are based on Munsell’s guiding principles that distribute the color space into three dimensions: hue (name of the color), chroma (color density) and value (vitality of color).
Recommended Protocols for Clinical Shade Selection
Shade selection is performed in an organized way that assures accuracy, consistency and predictable effects that are categorically essential in esthetic dentistry. At first, the value is selected for the arrangement of the selection of shade followed by chroma, and finally hue.
Working Site Lighting
Midday sunlight is ideally considered for the best shade selection, because the exposure of midday sunlight comprises nearly the same blend of whole-light wavelengths as compared to the sunlight exposure of morning and evening timings, which are more affluent with reddish and yellow wavelengths. Since dental clinics have no access to sunlight exposure, artificial light must be applied to mimic sunlight. Lamps of artificial light cannot be a perfect replacement for sunlight, but they are sufficient for clinical purposes.
Environment
Surroundings with bright colors should be evaded as they affect suitable color matching through influencing the colors in the reflected light. Unwanted colors in the patient’s jewelry and clothing can be covered with a wrapper, and the patient’s lipstick should be removed to prevent any changes in color perception. The ideal backdrop for color matching is a very light shade of gray. High-gloss surfaces create disturbing shines and should be avoided.
Condition of Teeth
The tooth to be matched and its neighboring teeth must be free of surface stains and plaque along with other deposits. The tooth of interest must be moist with saliva because a lack of moisture will result in a whiter look. Color matching of a tooth ought to be done before applying the rubber dam as the tooth becomes dryer after its use . Selection of shade should not be executed quickly after bleaching as the patient has to be revisited and recalled after 2 to 3 weeks for the comparison of shade .
During the selection of shade, teeth must be distributed into three areas each time, such as gingival area (it provides perfect measurement of dentinal chroma), middle and incisal area (where enamel is more dense and differs from translucent to transparent) .
Distance of the Operator from the Tooth, Position of the Patient and Timing
A distance from the oral cavity of about 61cm (2 feet) to 183 cm (6 feet) is preferably considered for the matching of shade. The position of a patient on the dental chair should be in such a way that the teeth of a patient are at the level of the operator’s eyes. Shade selection must be finalized by the operator in the morning preferably, when eye tiredness is minimal.
Time
Its important not to view the shade comparision for more than 7 s to avoid eye fatigness.
2. Which ceramic is based on lithium disilicate
- IPS empress
- IPS empress 2
- In ceram
- Captek
ANSWER b
IPS Empress 2
IPS Empress 2, the result of the consistent further development of the pressed glass-ceramic, enables you to fabricate three- unit bridges for the anterior and premolar region. The IPS Empress press-ceramic material has proved its worth in clinical use for a number of years.
Particularly aesthetic results have been achieved with inlays, onlays, crowns, veneers. IPS Empress 2 now offers these proven properties for yet another indication: all-ceramic bridges.
Advantages
- Especially developed lithium disilicate framework ceramics
- Newly developed fluorapatite layering ceramics
- Improved fracture resistance
- Very high chemical resistance of both framework and layering ceramics
- High translucency
- Outstanding light-optical properties due to apatite (also a component of natural teeth)
- Abrasion behaviour similar to that of natural enamel
- Ingots available in the most popular Chromascop shades
- Excellent aesthetic appearance
- Renowned technology
- Clinically tested by numerous universities around the world
3. The main compound of most denture cleaning powders is
- Sodium perborate
- Detergents
- Alkali agents
- Hydrogen peroxide
ANSWER a
It contains potassium persulphate and sodium perborate as active ingredients that work together to give a cleansing action. Potassium persulfate and sodium perborate are peroxygen compounds that yield active oxygen on admixture with water, leaving your denture clean and fresh.
4. Kennedy bar connector is a type of
- Lingual bar
- Lingual plate
- Double lingual plate
- Labial bar
ANSWER c
DOUBLE LINGUAL BAR (KENNEDY BAR)
| A double lingual bar = lingual bar + lingual plate major connectors |
INDICATIONS:
A double lingual bar is indicated primarily when contact with the remaining mandibular anterior teeth is indicated, but open embrasures exist.
SHAPE:
- The lower component of this major connector should be half-pear shaped in cross section, with its greatest diameter at the inferior margin.
- The upper bar should be half oval in cross section.
- This bar should be 2 to 3 mm in height and 1 mm thick. It should present a scalloped appearance.
- The two bars should be joined by rigid minor connectors at each end.
ADVANTAGES:
- Indirect retention and horizontal stabilization.
- Because the gingival tissues and the interproximal embrasures are not covered, a free flow of saliva is permitted and the marginal gingiva receives natural stimulation.
DISADVANTAGES:
- Accumulation of debris.
- Discomfort to tongue.
5. In a bilateral distal extension situation all of the following clasps used engage undercut close to the edentulous area except
- Bar clasp
- Embrasure clasp
- Reverse circlet
- Combination clasp
ANSWER d
A combination clasp is a circumferential retainer for a removable dental prosthesis that has a cast reciprocal arm and a wrought wire retentive clasp . It consists of a wrought wire retentive arm and a cast reciprocal arm. The combination of a wrought alloy and cast alloy gives it the name 'combination clasp
