Preclinical Manual of Prosthodontics Question And Answers

Preclinical Manual of Prosthodontics Question And Answers

Question 1. What is prosthodontics?

Answer:

Prosthodontics is a 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 substitutes.

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 the maxillary denture foundation area are the 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 the maxillary denture foundation are incisive papillae, midpalatine raphe, torus palatinus, canine eminence, and bony protuberance on the ridge.

Question 4. What are the limiting areas of the 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 the 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 palatine raphe?

Answer:

The midpalatine suture area is covered with mucous membrane. The submucosal tissue is thinner in this area. Pressure during mastication may cause pain in the region, sometimes due to movement of the maxillary denture the area can act as a fulcrum and cause pain so selective relief is given during making the final impression.

Question 9. Why incisive papilla should be relieved?

Answer:

Incisive foramen is the 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 an impression.

Question 10. What is (the PPS) posterior palatal seal area?

Answer:

It is an area located at or beyond the junction of the 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 the posterior palatal seal?

Answer:

The functions of the posterior palatal seal primarily aid in retention. It prevents food entrapment beneath the denture. Reduces the patient’s awareness of this area hence reducing gag reflex. It compensates for the 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 the manipulation of impression compound for making a primary impression.

Answer:

The steps in manipulation of impression compound are breaking the compound into small pieces, softening, kneading, loading of tray, performing, glazing, tempering, placing the tray in the patient’s mouth, molding the material, removing of set material, disinfection.

Question 14. Enumerates the theories/techniques of impression-making.

Answer:

Theories of impression-making are:

1. Mucostatic theory
2. Mucocompressive theory
3. Selective pressure technique.

Question 15. How does the extremely high temperature of water affect the properties of impression compounds?

Answer:

If water with extremely high temperatures is used for manipulation of the impression compound, the volatile constituents may leach out and alter the properties of the impression material.

Question 16. What is tempering?

Answer:

The heated and softened compound after glazing is at a temperature around 55–60°C which is intolerable to oral tissue. It is tempered in a water bath to lower the temperature to 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 the material. It is kneaded underwater because water acts as a 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 the material.

Question 19. Why is a custom tray required to be fabricated?

Answer:

The custom tray is an individualized tray that closely adapts to the patient’s arch. It provides an even thickness of impression material and yields a more accurate impression.

Question 20. What should be the dimensions of the custom tray handle?

Answer:

The custom tray handle should be 8 mm in length, 8 mm in height, and 3–4 mm in thickness. The maxillary custom tray handle is placed at 45° angulation and the mandibular custom tray handle is placed at 90° angulation.

Question 21. What is the need for a spacer in the custom tray?

Answer:

A spacer is placed on areas of relief where minimum pressure is to be applied while impression making. Thus, a space is created in the custom tray and no pressure will be applied while making an impression.

Question 22. What spacer material is used for the fabrication of a shellac custom tray and for an acrylic special tray?

Answer:

For acrylic custom tray wax is used to make spacer. For the shellac custom tray, shellac dusted with French chalk is used as a 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 the border molding procedure due to repeated temperature changes.

Question 24. What are the methods of pouring a cast?

Answer:

There are three methods of pouring cast:

1. Inversion/two-stage pouring method,
2. Beading and boxing method
3. Plaster pumice method.

Question 25. What is the importance of the base and land area of the master cast?

Answer:

The base and land area of the cast is 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 filled 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 for 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 the palatal and lingual flange region.

Question 30. What is the purpose of the occlusal rim?

Answer:

It is used to establish jaw relation, to determine lip support and aesthetics, aids in selecting teeth and to position and arrange them, determination of arch form, and determination of occlusal plane.

Question 31. Why is the 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 the 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 the mean value articulator based upon?

Answer:

The mean value articulator is based upon Bonwill’s theory of equilateral triangle.

Question 33. What are the functions of a vertical pin?

Answer:

It helps to maintain a fixed distance between the upper and lower members of the 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 the upper and lower rims and should not pierce through them. When viewed from the 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 an articulator.

They are:

1. Groove indexing
2. 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 an articulator in the same position.

Question 37. Why remounting is done?

Answer:

Remounting is done to remove processing errors in dentures 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 the Dentogenic concept?

Answer:

According to this concept, the Artificial teeth are selected according to the sex, age, and personality of the patient. Teeth selected for female patients are rounded and whiter in color to give delicacy to the prosthesis. For male patients teeth with sharp edges and darker in color are selected. Attrition abraded and gingival recession can be incorporated in dentures to give a natural look.

Question 41. What is the curve of occlusion?

Answer:

The average curve is 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 the 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 the 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 a 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’s classification?

Answer:

Leon Williams’s classification was based on matching tooth form to face form. Individual faces can be divided into 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 a squint test?

Answer:

This test is useful in selecting a color that 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 a buccal corridor or negative space?

Answer:

It is the space between the buccal surface of posterior teeth and the inner surface of the cheeks. It is influenced by the buccolingual placement of posterior teeth.

Question 51. What are the parts of flasks?

Answer:

The parts of flasks are:

1. Base
2. Body/Counter
3. Lid.

Question 52. At what stage do you pack acrylic resin?

Answer:

Acrylic resin is packed in the mold cavity in the dough-like stage.

Question 53. What is the purpose of trial closure?

Answer:

To remove excess material (Flash) to minimize processing errors such as increase of vertical dimension due to excess material.

Question 54. What are processing errors?

Answer:

They are warpage, fracture of a denture, change in teeth position, polymerization shrinkage, internal or external porosity, and increase in the vertical dimension.

Question 55. What is selective grinding?

Answer:

It is the intentional alteration of the occlusal surfaces of teeth. This is usually done to achieve proper occlusion.

Question 56. What are the components of an acrylic partial denture?

Answer:

The components of the acrylic partial denture are artificial teeth, the denture base, and wrought wire clasp.

Question 57. What are the components of a removable cast partial denture?

Answer:

They are major connectors, minor connectors, direct and indirect retainers, rest, denture base, and artificial teeth.

Question 58. What are the functions of a major connector?

Answer:

The 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 connectors?

Answer:

There are four types of minor connectors as follows:

• Connectorthatjoinstheclasp assembly to the major connector.
• The connector that joins indirect retainers or auxiliary rests to the major connector.
• The 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 connectors that join the denture base to the major connector.

Answer:

They are:

1. Lattice Type/Ladder Type
2. Mesh Work Type
3. Neil Bead/Neil Head Type.

Question 61. What are the parts of the clasp?

Answer:

The parts of the clasps are the rest, the body of the clasp, shoulder, reciprocal clasp arm, retentive clasp arm, retentive terminal, minor connector, and approach arm (in the case of bar clasp).

Question 62. What are the parts of a fixed partial denture?

Answer:

Parts of fixed partial dentures 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 the 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, a 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).