PROSTHODONTICS Part 1 Flashcards
fixed dental prostheses with ___ of bone support and loss of ___ have a poor prognosis
half or less of bone support and loss of attachment
what is the prognosis of a single retainer cantilever FPD?
poor
in prosthodontics, splinting teeth is generally done to ___
- distribute occlusal forces
- this is recommended where the periodontal surface of the abutment tooth does not provide the needed support for an FPD or RPD
T or F:
multiple splinted abutment teeth does not compromise long-term prognosis
false
T or F:
intermediate abutments compromise long-term prognosis
true
do rigid or nonrigid connectors have a better prognosis?
rigid
when replacing the maxillary or mandibular canine with an FDP, why is it necessary to splint the central and lateral?
to prevent lateral drifting of the FDP
can compromised endodontically treated teeth be used as retainers?
no, they should not be
teeth with a short crown/root ratio (what ratio?) and with what root shape are not good choices for abutments?
<2:1 with conical roots
why are complete dentures contraindicated when only mandibular anterior teeth are present?
because severe damage to the opposing premaxilla occurs (combination syndrome)
___ is considered a terminal hinge position and is defined as “the maxillomandibular relationship in which the condyles articulate with the thinnest avascular portion of their respective discs with the condyle-disc complex in the anterior-superior position against the shapes of the articular eminences”
centric relation
___ is the complete intercuspation of the opposing teeth independent of condylar position
maximal intercuspal position, maximum intercuspation (MI), or centric occlusion
in ___% of people, CR and MI do not coincide
90%
accurate CR interocclusal records require precise manipulation of the mandible by the dentist. which technique is recommended?
the bimanual manipulation technique
casts produced with ___ are more accurately mounted with wax records, and casts obtained with ___ materials are more accurately mounted with elastomeric registration materials or zinc oxide eugenol paste
- irreversible hydrocolloid (alginate)
- elastomeric materials
what is the composition of irreversible hydrocolloid impression material?
- aka alginate
- mainly sodium or potassium salts of alginic acid
- the salts react chemically with calcium sulfate to produce insoluble calcium alginate
- diatomaceous earth is added for strength, and trisodium phosphate and other compounds are added to control the setting rate
how long after mixing the alginate material (“gelation”) should the tray be removed from the mouth?
2-3 minutes
after removing an alginate impression from the patients mouth, how should it be disinfected?
rinse with water and disinfect with glutaraldehyde or iodophor
after taking an alginate impression, what type stone is recommended for pouring the cast? how long does the stone take to set?
type IV or V, and usually takes 30-60 minutes to set
what are the two types of semiadjustable articulators?
arcon and nonarcon
describe arcon semiadjustable articulators
- condyles are attached to the lower member of the articulator, and fossae are attached to the upper member
- more accurate for fabricating fixed restorations
describe nonarcon semiadjustable articulators
- upper and lower members are rigidly attached
- useful for setting teeth for complete and partial dentures
what is an arbitrary facebow?
- orients the cast in the anterior-posterior and mediolateral position in the articulator to anatomic average values
- external auditory meatus is used to stabilize the bow
how do kinematic facebows differ from arbitrary facebows?
they allow more accuracy when mounting casts
what are the 3 major groups of dental implants? what is the most common used today?
- subperiosteal
- transosteal
- endosteal (most common)
what are the contraindications for dental implants?
- acute illness
- terminal illness
- pregnancy
- uncontrolled metabolic disease
- unrealistic patient expectation
- improper patient motivation
- lack of operator experience
- inability to restore with prosthesis
when placing several implants, they should be at least ___mm apart from each other, and ___mm away from the adjacent tooth
- 3mm
- 1mm
what is the recommended number of implants for placement in the elderly edentulous patient?
- two in the mandible
- four in the maxilla
describe the difference between one stage and two stage restoration with implants
- one stage involves the implant body that projects through the soft tissue with a cover screw after surgical placement
- two stage restoration involves covering the cover screw with soft tissue at the time of placement, which is then uncovered in a second operation
after placing a dental implant, how much time should you give to allow for adequate healing before taking final impressions?
2 weeks in a noncritical esthetic area, and 3-5 weeks in esthetic areas
T or F:
attaching implants to natural teeth is not recommended
true
when is it possible for two implants to support a 3-unit FDP?
- when the crown/implant ratio is favorable
- if implants are short and crowns are long, one implant to replace each missing tooth is highly recommended
what are the advantages of cement-retained implant crowns?
- more economical (in some systems)
- allows minor angle corrections to compensate for discrepancies between the implant inclination and the facial crown contour
- easier to use in small teeth than screw-retained implant crowns
what is the disadvantages of cement-retained implant crowns?
requires more chair time and has the same propensity to loosen as screw-retained implants
what are the advantages of screw-retained implant crowns?
- retrievability allows for crown removal, facilitating maintenance (soft tissue evaluation, calculus removal)
- future modification capability
- access hole is through the occlusal table of posterior teeth or lingual of anterior
what is the main disadvantage of screw-retained implant crowns?
the screw may loosen during function because of excessive lateral forces, excessive cantilever force, or improperly screwed crowns
are lateral forces in the posterior or anterior more destructive?
posterior (forces are greater and more destructive)
in dental implants, when unable to eliminate lateral forces, what should you do?
balance the occlusion so that the stress is distributed over as many teeth as possible
in treatment planning for dentures, what is the general rule for residual root tips?
- root tips with no radiolucency and cortical margin of bone intact may remain; inform the patient of their presence and risk and of the need to have them removed in the future
- they should be removed if the cortical plate is perforated or the periodontal ligament or radiolucent area is enlarging
frenectomy surgery is sometimes indicated when treatment planning for complete dentures. what are the most common areas for frenectomy?
in order of most to least common: labial > buccal > lingual
what is a hypermobile ridge and how should it be treated when planning for complete dentures?
- excessive moveable tissue due to fibrous tissue deposition
- should be treated with tissue conditioner
- if tissue conditioner is ineffective, electrosurgery or laser surgery can eliminate tissue
- this procedure might also eliminate the vestibule and risk making it even more difficult to attain a seal
- immediately after surgery, a soft liner must be placed to prevent epulis fissurata from forming
___ is a hyperplastic tissue reaction caused by an ill-fitting or overextended flange in a denture
epulis fissurata
fibrous maxillary tuberosity is common when ___
large maxillary tuberosities contact mandibular retromolar pads
___ is believed to be a specific pattern of bone resorption in the anterior portion of edentulous maxillae, caused by wearing a complete denture opposing anterior teeth
combination syndrome
___ is defined as multiple papillary projections of the epithelium caused by local irritation, poor fitting denture, poor oral hygiene, and leaving dentures in all day and night
- papillary hyperplasia
- candidiasis is the primary cause
- found in the palatal vault
what is the treatment for papillary hyperplasia?
- soak dentures for 30 minutes in a 1% solution of sodium hypochlorite and rinse thoroughly
- use tissue conditioner
___ is characterized by pinpoint hemorrhage or white patches or both, and requires a cytologic smear to confirm infection
candidiasis (candida albicans)
what is the treatment for candidiasis?
- nystatin or clotrimazole pastilles (both contain sugar and should be avoided in diabetic patients)
- clotrimazole or nystatin powder in oral suspension
what are treatment planning modifications for complete denture patients or RPD patients with pagets disease of bone?
denture or RPD may have to be remade periodically because of bone expansion
what are examples of hard tissue surgery that may need to be completed when planning for complete dentures?
- alveoloplasty,
- pendulous tuberosities (limits interarch space)
- sharp, spiny, or extremely irregular ridges
___ is a surgery that increases the relative height of the alveolar process
vestibuloplasty (soft tissue surgery)
T or F:
in the event that a complete denture is impinging on a neurovascular bundle, repositioning of the neurovascular bundle is never indicated
false
what are examples of augmentation surgeries for complete dentures?
- bone grafts
- hydroxyapatite
- freeze-dried bone
- connective tissue
in bone graft procedures, ___% of the bone graft is often lost due to resorption
75%
the ___ record of an edentulous patient provides the ability to increase or decrease the vertical dimension of occlusion more accurately
centric relation
a ___ record registers the anterior-inferior condyle path at one particular point in the translatory movement of the condyles
protrusive
___ phenomenon refers to the distal space created between the maxillary and mandibular occlusal surfaces of the occlusion rims of dentures when the mandible is protruded
christensen’s phenomenon
___ is the position of the mandible when the elevator and depressor muscles are in a state of equilibrium or balance
vertical dimension of rest or physiologic rest position of the mandible
the vertical dimension of rest position commonly results in a separation of the maxillary and mandibular teeth of about ___mm at the premolar region. this separation is called the ___ space
- 3mm
- interocclusal space
what are common effects of excessive vertical dimension of occlusion in complete denture cases?
- excessive display of mandibular teeth
- complaint of fatigue of muscles of mastication
- clicking of the posterior teeth when speaking
- strained appearance of the lips
- patient unable to wear dentures
- discomfort
- excessive trauma to the supporting tissues
- gagging
what are the common effects of insufficient vertical dimension of occlusion in complete denture cases?
- aging appearance on the lower third of the face because of thin lips, wrinkles, chin too near to the nose, and overlapping corners of the mouth
- diminished occlusal force
- angular cheilitis (occurs in conjunction with candidiasis)
___ is an imaginary line traced from the ala of the nose to the tragus of the ear
campers line (helps in establishing the plane of occlusion)
the ___ line is in the traverse plane and is an imaginary line drawn between the pupils of the eyes
interpupillary line (helps in establishing the plane of occlusion)
fricative or labiodental sounds f, v, ph are made between the maxillary incisors contacting the wet/dry lip line of the mandibular lip and help determine what in the complete denture patient?
the position of the incisal edges of the maxillary anterior teeth
linguoalveolar sounds or sibilants (sharp sounds s, z, sh, ch, and j) are made with the tip of the tongue and the most anterior part of the palate or lingual surface of the teeth. these sounds help determine ___ in the complete denture patient
the vertical length and overlap of the anterior teeth
in the complete denture patient, what is a whistling sound indicative of?
having a posterior dental arch form that is too narrow
linguodental sounds (tip of the tongue slighltly between the maxillary and mandibular teeth, such as “this” “that” and “those”) helps determine ___ in the complete denture patient. the “th” sound provides information regarding the ___
- the labiolingual position of the anterior teeth
- labiolingual position of the anterior teeth
in the complete denture patient, vertical dimension is evaluated during pronunciation of what sound? the interincisal separation should be ___mm. what is this space called?
- the s sound
- 1-1.5mm
- the closest speaking space
in the complete denture patient, what are the limiting structures of the maxillary denture?
- anterior region: labial vestibule and buccal vestibules
- posterior region: limit extends to junctions of movable and immovable tissue (coincides with the line drawn through the hamular notches and approx. 2mm anterior to the foveae palatina (vibrating line)
support for a maxillary complete denture is provided by the ___ and ___
maxillary and palatine bones
in the complete denture patient, what are the limiting structures of the mandibular denture?
- anterior labial area, which extends from the labial frenum to the right and left buccal frenums
- buccal vestibules
- retromolar pad
- lingual frenum
- sublingual gland area
- mylohyoid area
- retromylohyoid area
the ___ marks the distal termination of the mandibular edentulous ridge
retromolar pad
how do the buccinator and masseter muscles limit/displace mandibular complete dentures?
- buccinator muscle fibers run in an oblique fashion and have little displacing action
- masseter muscle limits the denture in a lateral direction
maxillary and mandibular lip support in a patient with complete dentures is provided by ___ and ___
facial surfaces of teeth and the denture base
denture ___ refers to resistance to vertical seating forces
denture support
denture ___ is necessary to resist dislodgment of a denture in the horizontal direction
stability
denture ___ is the ability of the denture to withstand dislodging forces exerted in the vertical plane
retention
what are the surfaces of a denture that play a part in retention?
- intimate contact of the denture base and its basal seat
- teeth - no occlusal prematurities to break retention
- design of the labial, buccal, and lingual polished surfaces
what is the primary retentive force for dentures?
saliva to denture and tissues (adhesion)
what is the favorable type of saliva for denture adhesion? what is the unfavorable type?
- favorable type is watery (greater retention)
- unfavorable type is thick and ropy
how is abnormal mucoperiosteum beneath dentures treated?
complete removal of the dentures until the tissues return to a normal size, shape, color, consistency, and texture
candida albicans is normal in the oral cavity, but under trauma or antibiotic usage, it may cause generalized inflammation (candidiasis). it may involve the corners of the mouth (angular cheilitis) which is common in patients with diminished ___
vertical dimension
what is the nystatin rinse prescription regimen for candidiasis infections?
- nystatin oral suspension contains sugary (caution with diabetic patients)
- dispense 60mL of 100,000 units/mL
- take 4mL 3x/day; after each meal, hold in mouth for 2 minutes then expectorate
what is the nystatin cream prescription regimen for candidiasis infections?
- nystatin w/triamcinolone acetonide cream (used for angular cheilitis)
- dispense 15g tube
- instructions: apply to affected area a small amount 4x/day (after meals and bedtime) for 14 days
what are the advantages of retaining roots when planning for overdentures?
- decreases bone resorption
- maintains the proprioceptive fibers within the PDL
what is cheek biting with dentures due to? how can the problem be solved?
- insufficient horizontal overlap between maxillary and mandibular teeth
- reducing the facial of mandibular posterior teeth in question can solve the problem
in denture cases, overextension usually causes ___
dislodgment of the denture
which kennedy classification is described as bilateral edentulous areas located posterior tot he remaining natural teeth?
class I
which kennedy classification is described as a unilateral edentulous area located posterior to the remaining natural teeth?
class II
which kennedy classification is described as a unilateral edentulous area with nautral teeth remaining both anterior and posterior to it?
class III
which kennedy classification is described as a single, but bilateral (crossing the midline), edentulous area located anterior to the remaining teeth?
class IV
how are kennedy classifications determined in cases where extractions are needed?
classifications should follow rather than precede any extractions of teeth that might alter the original classification
what are the rules for kennedy classifications in terms of third molars?
- if a third molar is missing and not to be replaced, it is not considered in the classification
- if a third molar is present and is to be used as an abutment, it is considered in the classification
if a second molar is missing and is not to be replaced, is it considered in the kennedy classification?
no
the most ___ edentulous area determines the kennedy classification
posterior
what are kennedy classification modifications?
- edentulous areas other than those determining the classification
- they are designated by the number of additional edentulous areas, not the extent of modification
which kennedy classification cannot have any modifications?
class IV
what is the function of a major connector?
- to connect all the RPD components on one side of the arch with the opposite side to unite them
- provides stability to resist displacement while in function
should major connectors be flexible or rigid? what tissues should they not be placed on?
- rigid
- not placed on movable tissue
- undercut areas and soft and bony prominences (tori, median palatal suture) should be avoided, removed, or relieved, depending on the severity
which kennedy classifications are anterior-posterior palatal straps useful for?
all classes, especially class II and IV
should major connectors cross the midline at right angles or diagonal?
right angles
what kennedy classifications are single palatal straps useful for? how should they be designed?
- kennedy class III with bilateral, short-span edentulous areas
- palatal strap should be wide and thin for strength and comfort
- anterior border should be posterior to the rugae
describe palatal plate designs. which kennedy classifications are they useful for?
- can be designed as a wide palatal strap short of the rugae area for distal extension RPD where more than the anterior teeth are present (kennedy class I)
- complete palatal strap (most rigid of all major connectors) is indicated when all posterior teeth are missing bilaterally, in a kennedy class I mod I, and for periodontally compromised teeth, shallow vault, small mouth, or flat or flabby ridges
which situations are u-shaped palatal (horseshoe) major connectors useful for?
- used only when other, more rigid designs cannot be used
- commonly used when large, inoperable palatal torus exists or when anterior teeth need replacement
which major connector is the least rigid of all maxillary connectors?
u-shaped palatal (horseshoe)