Preclinical Manual of Prosthodontics Question And Answers
Question 1. What is prosthodontics?
Answer:
Prosthodontics is dental specialty pertaining to the diagnosis, treatment planning, rehabilitation and maintenance of the oral function, comfort, appearance and health of patients with clinical conditions associated with missing or deficient teeth and/or maxillofacial tissue using biocompatible substitute.
Read and Learn More: Preclinical Prosthodontics Notes
Question 2. What are the stress bearing areas of the maxillary denture bearing area?
Answer:
The primary stress bearing areas in maxillary denture foundation area are hard palate and firm maxillary tuberosity. Secondary stress bearing areas are rugae and alveolar ridge.
Question 3. What are the relief areas of the maxillary denture bearing area?
Answer:
Relief areas on maxillary denture foundation are incisive papillae, midpalatine raphe, torus palatinus, canine eminence, bony protuberance on ridge.
Question 4. What are the limiting areas of maxillary denture bearing area?
Answer:
They are labial frenum, labial vestibule, buccal frenum, buccal vestibule, hamular notch, posterior palatal seal area and coronomaxillary pouch
Question 5. What are the stress bearing areas of the mandibular denture bearing area?
Answer:
They are buccal-self area and slopes of residual alveolar ridge.
Question 6. What are the relief areas of the mandibular denture bearing area?
Answer:
Crest of residual alveolar ridge, torus mandibularis. In severely resorbed ridges, genial tubercle and mental foramen are considered as relieving areas. Prominent mylohyoid ridge is also considered as relieving structure.
Question 7. What are the limiting areas of mandibular denture bearing area?
Answer:
They are labial frenum, labial vestibule, buccal frenum, buccal vestibule, alveolar lingual sulcus, retromolar pad.
Question 8. Why relief should be given over the midpalatine raphe?
Answer:
The midpalatine suture area is covered with mucous membrane. The submucosal tissue is thinner in this area. Pressure during mastication may causes pain in the region, sometime due to movement of the maxillary denture the area can act as fulcrum and causes pain so selective relief is given during making the final impression.
Question 9. Why incisive papilla should be relieved?
Answer:
Incisive foramen is exit point for nasopalatine vessels and nerves. Incisive foramen is covered with incisive papilla. Compression of the papilla causes paresthesia of soft tissues in the anterior palatal region so relief should be provided while making impression.
Question 10. What is (PPS) posterior palatal seal area?
Answer:
It is area located at or beyond the junction of hard palate and soft palate, on which pressure within physiologic limits can be applied by the prosthesis (Complete denture) to aid in its (Denture’s) retention.
Question 11. What are the functions of posterior palatal seal?
Answer:
The functions of posterior palatal seal are primarily aids in retention. It prevents food entrapment beneath the denture. Reduces the patient’s awareness of this area hence reduces gag reflex. It compensates for volumetric shrinkage of the acrylic resin.
Question 12. What is impression?
Answer:
A negative likeness or copy in reverse of the surface of an object; (an imprint of the teeth and adjacent structures for use in dentistry).
Question 13. List the steps in manipulation of impression compound for making a primary impression.
Answer:
The steps in manipulation of impression compound are breaking the compound in small pieces, softening, kneading, loading of tray, preforming, glazing, tempering, placing the tray in patient’s mouth, moulding the material, removal of set material, and disinfection.
Question 14. Enumerates the theories/techniques of impression making.
Answer:
Theories of impression making are:
- Mucostatic theory
- Mucocompressive theory
- Selective pressure technique.
Question 15. How does extremely high temperature of water affect properties of impression compound?
Answer:
If water with extremely high temperature is used for manipulation of impression compound, the volatile constituents may leach out and alter the properties of impression material.
Question 16. What is tempering?
Answer:
The heated and softened compound after glazing is at temperature around 55–60°C which is intolerable to oral tissue. It is tempered in a water bath to lower th temperature around 45˚C which is well tolerated by oral tissue.
Question 17. What is the purpose of kneading?
Answer:
Kneading is done to uniformly mix all the constituents of the impression compound and improve the handling characteristic of material. It is kneaded under water because water acts as plasticizer.
Question 18. What is the purpose of glazing?
Answer:
Glazing is heating the preformed surface of a compound under a flame to record the minute surface details with minimum distortion of the bulk of material.
Question 19. Why is custom tray required to be fabricated?
Answer:
Custom tray is an individualized tray which closely adapts to the patient’s arch. It provides even thickness of impression material and yields a more accurate impression.
Question 20. What should be the dimensions of custom tray handle?
Answer:
The custom tray handle should be 8 mm in length, 8 mm in height and 3–4 mm in thickness. Maxillary custom tray handle is placed at 45° angulation and mandibular custom tray handle is placed at 90° angulation.
Question 21. What is the need for a spacer in custom tray?
Answer:
Spacer is placed on areas of relief where minimum pressure is to be applied whil impression making. Thus, a space is created in custom tray and no pressure will be applied while making impression.
Question 22. What spacer material is used for fabrication of shellac custom tray and for acrylic special tray?
Answer:
For acrylic custom tray wax is used to make spacer. For shellac custom tray, shellac dusted with French chalk is used as spacer.
Question 23. What are the drawbacks of the shellac custom tray?
Answer:
Shellac is brittle and has less strength. The dimension stability is poor so easily distorts during border moulding procedure due to repeated temperature change.
Question 24. What are the methods of pouring a cast?
Answer:
There are three methods of pouring cast:
- Inversion/two stage pouring method,
- Beading and boxing method
- Plaster pumice method.
Question 25. What is the importance of base and land area of master cast?
Answer:
Base and land area of cast are important to preserve the depth and width of the sulcus, to impart strength to the cast and to protect and preserve anatomical landmarks.
Question 26. What is the purpose of making a record base?
Answer:
It is used to support the occlusal rim material for recording maxillomandibular relation (Jaw relation) and for arranging the artificial teeth.
Question 27. Which area of the base plate should be flled and flushed?.
Answer:
The margin of the base plate should be filed and flushed with the vestibular depth of the cast.
Question 28. What are the requirements of temporary record bases ?
Answer:
It should be well adapted to the final cast, stable and retentive in the mouth, dimensionally stable, smooth and nonirritant to tissue.
Question 29. What should be the ideal thickness of record bases?
Answer:
The record base should be 1 mm thick on the ridge crest and facial slopes. It should be 2 mm thick in palatal and lingual flange region.
Question 30. What is purpose of occlusal rim?
Answer:
It is used to establish jaw relation, to determine lip support and aesthetic, aids in selecting teeth and to position and arrange them, determination of arch form, and determination of occlusal plane.
Question 31. Why is mean value articulator called so?
Answer:
It is called so because it is based on average or fixed values of condylar (33°) and incisal (5°) guidance. The intercondylar distance (110 mm) in mean value articulator is also fixed all average values are used to design it so called as mean value articulator.
Question 32. Which theory is mean value articulator based upon?
Answer:
Mean value articulator is based upon Bonwill’s theory of equilateral triangle.
Question 33. What are the functions of vertical pin?
Answer:
It helps to maintain fixed distance between upper and lower member of articulator.
Question 34. What points do you check prior to mounting wax occlusal rims on the articulator?
Answer:
A thread is used to check whether the anterior and posterior plane of occlusal rims is oriented to the articulator’s incisal pin and horizontal bar. The incisal pin should point at the midline at the junction of upper and lower rims and should not pierce through them. When viewed from top, the casts with rims should appear centered on the articulator.
Question 35. What are the methods of indexing the casts prior to mounting them on an articulator?
Answer:
There are two methods for indexing the casts prior to mounting on articulator.
They are:
- Groove indexing
- Notch indexing.
Question 36. What is the purpose of indexing casts?
Answer:
Indexing of master casts is required because the casts after processing of waxed denture can be remounted in articulator in the same position.
Question 37. Why remounting is done?
Answer:
Remounting is done to remove processing errors in denture after polymerization by selective grinding.
Question 38. What is overjet?
Answer:
The horizontal relationship of the incisal edges of the maxillary incisors to the mandibular incisors when the teeth are in maximum intercuspation.
Question 39. What is vertical overlap or overbite?
Answer:
The vertical relationship of the incisal edges of the maxillary incisors to the mandibular incisors when the teeth are in maximum intercuspation.
Question 40. What is Dentogenic concept?
Answer:
According to this concept, the Artificial teeth are selected according to sex, age and personality of patient. Teeth selected for female patient are rounded and whiter in color to give delicacy to the prosthesis. For male patient teeth with sharp edges and darker in color are selected. Attrition, abraded and gingival recession can be incorporated in denture to give natural look.
Question 41. What is curve of occlusion?
Answer:
The average curve established by the incisal edges and occlusal surfaces of the anterior and posterior teeth in either arch.
Question 42. What is Bonwill’s theory?
Answer:
Described by Bonwill in 1858, a 4-inch equilateral triangle bounded by lines connecting the contact points of the mandibular central incisor’s incisal edge (or the midline of the mandibular residual ridge) to each condyle (usually its midpoint) and from one condyle to the other.
Question 43. What is Monson’s spherical theory?
Answer:
An arrangement of teeth that places their occlusal surfaces on the surface of an imaginary sphere (usually 8 inches in diameter) with its center above the level of the teeth.
Question 44. What is curve of Monson?
Answer:
It is a proposed ideal curve of occlusion in which each cusp and incisal edge touches or conforms to a segment of the surface of a sphere 8 inches in diameter with its center in the region of the glabella.
Question 45. What is anti-Monson curve or reverse curve?
Answer:
In excessive wear of the teeth, the obliteration of the cusps and formation of either flat or cupped-out occlusal
surfaces, associated with reversal of the occlusal plane of the premolar, first and second molar teeth (the third molars being generally unaffected), whereby the occlusal surfaces of the mandibular teeth slope facially instead of lingually and those of the maxillary teeth incline lingually.
Question 46. What is mutually protected occlusion?
Answer:
When posterior teeth are in occlusion, there is gap between opposing anterior teeth and when anterior teeth are in contact there is disocclusion of posterior teeth. This phenomenon is called mutually protected occlusion or Christensen’s phenomenon.
Question 47. What is Leon Williams classification?
Answer:
Leon Williams classification was based on matching tooth form to face form. Individual faces can be divided as square, tapering and ovoid. The teeth for each type can be selected according to facial form.
Question 48. What are the pre-extraction aids for teeth selection?
Answer:
Pre-extraction aids for teeth selection are diagnostic casts, extracted teeth, photographs, and radiographs.
Question 49. What is squint test ?
Answer:
This test is useful in selecting a color which is in harmony with the face. When different shades are compared with face color the shade that appears to be the best match according to the face color is selected.
Question 50. What is buccal corridor or negative space?
Answer:
It is the space between the buccal surface of posterior teeth and inner surface of cheeks. It is influence by buccolingual placement of posterior teeth.
Question 51. What are the parts of flasks?
Answer:
The parts of flasks are:
- Base
- Body/Counter
- Lid.
Question 52. At what stage do you pack acrylic resin?
Answer:
Acrylic resin is packed in the mould cavity in dough-like stage.
Question 53. What is the purpose of trial closure?
Answer:
To remove excess material (Flash) as to minimize the processing errors such as increase of vertical dimension due to excess material.
Question 54. What are processing errors?
Answer:
They are warpage, fracture of denture, change in teeth position, polymerization shrinkage, internal or external porosity and increase in vertical dimension.
Question 55. What is selective grinding?
Answer:
It is intentional alteration of occlusal surfaces of teeth. This is usually done to achieve proper occlusion.
Question 56. What are the components of acrylic partial denture?
Answer:
The components of acrylic partial denture are artificial teeth, the denture base and wrought wire clasp.
Question 57. What are the components of removable cast partial denture?
Answer:
They are major connector, minor connector, direct and indirect retainers, rest, denture base and artificial teeth.
Question 58. What are the functions of a major connector?
Answer:
Major connector has two functions. It connects the components on one side of the arch to the other side of the arch and provides cross-arch stabilization.
Question 59. What are the types of minor connector?
Answer:
There are four types of minor connector as follows:
- Connectorthatjoinstheclasp assembly to the major connector.
- Connector that joins indirect retainers or auxiliary rests to the major connector.
- Connector that joins the denture base to the major connector.
- An approach arm for a vertical projection or bar type clasp.
Question 60. Mention the types of minor connector that joins the denture base to the major connector.
Answer:
They are:
- Lattice Type/Ladder Type
- Mesh Work Type
- Neil Bead/Neil Head Type.
Question 61. What are the parts of the clasp?
Answer:
The parts of clasps are: rest, body of the clasp, shoulder, reciprocal clasp arm, retentive clasp arm, retentive terminal, minor connector, approach arm (in case of bar clasp).
Question 62. What are the parts of a fixed partial denture?
Answer:
Parts of fixed partial denture are pontic, connector and retainer.
Question 63. What is an undercut?
Answer:
The contour of a cross-sectional portion of a residual ridge or dental arch that prevents the insertion of a dental prosthesis or the portion of the surface of an object that is below the height of contour in relationship to the path of placement
Question 64. What is the height of contour?
Answer:
A line encircling a tooth and designating its greatest circumference at a selected axial position determined by a dental surveyor or a line encircling a body designating its greatest circumference in a specified plane.
Question 65. What are the forms of indirect retainer?
Answer:
The indirect retainer can be an auxiliary rest (occlusal rest, cingulum rest or incisal rest). In some cases, major connector provides indirect retention.
Question 66. What is BULL’S law?
Answer:
During selective grinding for alteration of occlusal surfaces the nonfunctional cusp of maxillary teeth and mandibular teeth are altered. This is done according to BULL’S law (Buccal-Upper and LowerLingual).
Leave a Reply