Miscellaneous Flashcards
when does pre prosthetic surgery take place
before the fabrication of a denture
what is included in pre prosthetic surgery
- maxillary and mandibular tori
- exostoses
- sharp prominents mylohyoid ridges
- epulis fissuratum
what is denture stomatitis
a localized or generalized chronic inflammation of the denture bearing mucosa
what is the clinical presentation of denture stomatitis
redness and a burning sensation with or without discomfort
what is the most likely cause of denture stomatitis
trauma and secondary fungal infection
what is the treatment of denture stomatitis
- improved oral hygieve
- tissue rest
- antifungal therapy
- resilient tissue conditioners
- new, well fitting denures
acute atrophic candiasis presents as:
- a red patch or atrophic or
- erythematour red and painful mucosa
antibiotic sore mouth, a common form of atrophic candidiasis should be suspected on a patient that develops symptoms of:
- oral burning
- bad taste
- sore throat during or after therapy with broad spectrum antibiotics
what patients are susceptible to atrophic candidiasis
- chronic iron deficiency anemia
what kind of candidiasis is denture stomatitis
chronic atrophic candidiasis
where is papillary hyperplasia found
in the palatal vault
what are the causes of papillary hyperplasia
- poor fitting dentures
- poor oral hygiene
- leaving denture in 24 hours a day
what is the treatment for papillary hyperplasia
- educate pt on OH
- advise patient to leave denture out at night
- soak dentures for 30 minutes in a 1% solution of sodium hypochlorite and rinse thoroughly
- use tissue conditioners
- patient should brush irritated area lightly with a soft brush
what is epulis fissuratum
a chroniccally ill fitting denture causes inflammatory fibrous hyperplasia adjacent to its border
- reactive growth in relation to an overextended or ill fitting denture flange
what are the causes of epulid fissuratum
- long term neglect or settling subsequent to residual ridge resorption
- traumatic occlusion of natrual teeth opposing an artificial denture
what is the treatment of epulis fissuratum
surgical removal of the hyperplastic tissue
what is the treatment for hyperplastic tissue
- tissue rest
- soft reline of existing dentures
- change in denture habits- not wearing them 24 hours a day
- surgical removal of the tissue
what is the best impression technique for a patient with loose hyperplastic tissue
to register the tissue in its passive position
what is the most important reason for treatment of hyperplastic tissue before construction of a denture
to provide a firm, stable base for the denture
what is Kelly’s combination syndrome
a specific pattern of bone resorption in the anterior portion of edentulous maxilla
when does kelly’s combination syndrome happen
when a mandibular partial denture is opposed by a maxillary complete denture
what is the cause of kelly’s combination syndrome
- prostheses lose some degree of support as a result of alveolar resorption
- as resorption occurs under mandibular extension bases support for the posterior prosthetic teeth is decreased
- the occlusal forces are concentrated within the anterior sextants, increases forces in anterior maxilla may result in absorption, downward growth of the tuberosities and tipping of the occlusal plane
how is kelly’s combination syndrome treated and how does this fix the issue
- continuous reline or placement of implants in mandibular posterior locations
- this results in more stable occlusal plane and a more equitable distribution of forces to the maxillary denture
what is tissue conditioner
soft materials that are applied to the intaglio surface of a complete or partial denture to allow a more equitable distribution of forces throughout the dental arch
- non- irritating
- non-toxic
- soft, elastic does not undergo permanent deformation
what are tissue conditioners used to treat
unhealthy or abused oral tissues
how long does the softness of tissue conditioner last
about 1 week which then can become hard and an irritant
how often must the tissue conditioner be changed
every 3-5 days
what is tissue conditioner made of
- powder and liquid
- powder is an acrylic polymer, usually ethyl methacrylate
- the liquid is usually a mixture of ethyl alcohol and aromatic ester
- the two combine to form a gel that remains pliable for several days
what is the mechanism of action of tissue conditioner
a combination of improved force distribution and a short term cushioning effect
the intaglio surface of the RPD is checked using:
pressure indicating paste
when is tissue conditioner applied
after intaglio surface is checked with PIP and occlusion is checked normally
how is tissue conditioner applied
- the cameo surface of the prosthesis is painted with separator
- after the tissue conditioner is mixed, flowed onto the intaglio surface of denture
- tissue conditioner distributed evenly using a small spatula
- denture is seated in the mouth under light pressure
- pressure is maintained
- border tissues should be manipulated to border mold the conditioner
for a mandibular RPD, the tongue should be brought:
forward and forcibly placed into each cheek to define the lingual extension accurately
with tissue conditioner if posterior artifical teeth are present:
patient must close the teeth together while the conditioner is still flowable to align the artifiial teeth properly with the opposing occlusion
how long should the patient sit with tissue conditioner under the gel stage has been reached
4-5 minutes
excess tissue conditioner should be removed using:
a sharp blade
areas of contact in tissue conditioner should be removed using:
laborator burs
what should you do with dentures out of the mouth with tissue conditioner on it
- do not let it dry
- submerge in water or a cleansing solution
how is wrought wire made
drawing the metal from which it is made into a wire
wrought wire clasp must have an elongation percentage of:_________ and why?
more than 6% to allow the clasp to bend without microstructure changes that could compromise its physical properties such as fracture
what is cast metal
any metal that is melted and cast into a mold
what is a wrought metal
when casting is cold-worked in some manner to provide the required article or appliance
which have better mechanical properties: wrought wire or cast structure
wrought wire
the wrought wire has ___greater ________ than the cast alloy from which it was fabricated
25%; strength, hardness and tensile strength
the wrought wire has greater _______ than the cast clasps and are ______ than cast clasps
flexibility and adjustability; tougher and more ductile
what does the success of wrought wire clasps depend on
their physical properties and the changes that may occur during fabrication
laboratory procedures can compromise desirable physical properties of wrought wire due to:
improper heating and cooling
what is the mechansim of action of lab errors in fabricating wrought wire
- too much heat
- change in the fibrous microstructure of the wrought wire and getting replaced by a grain or crystalline mcirostructure
- process is known as recrystallization or grain growth
what is the most undesirbale occurrence in wrought wire retentive arms
recrystallizatino or grain growth
the popularity of chromium Cobalt alloys for fabrication of cast frameworks for RPDs has been attributed to their:
- low density (weight)
- high modulus of elasticity (stiffness)
- low material cost
- resistance to tarnish
chromium cobalt allows are ____ in comparison to gold or pallidum alloys
more rigid
how can the stiffness of chromium- cobalt allows be overcome
by including wrought- wire retentive elements in the framework
what does chromium, coblat, and nickel do in chromium alloys for RPDs
- chromium: ensures that the allow will resist tarnish and corrosion due to formation of a complex chromium oxide film
- cobalt: contributes strength, rigidness and hardness
- nickel: increases ductility
what are the minor constituents and their effects on chromium alloys for RPDs
- carbon: effect on strength, hardness and ductility
- tin, indium: improve bonding
the gold allows are _____ as flexible as the chromium- cobalt alloys
twice
what are the advantages of chromium cobalt alloys
- high modulus of elasticity and therefore lower flexibility
- low material cost
- low density (weight)
what are the possible causes of failure of chromium cobalt alloys
- cold working
- shrinkage porosity
- low percent elongation
- excessive carbon in the alloy
why does cold working cause failure of chromium cobalt alloys
reduces the percentage of elongation that causes a decrease in hardness
why does shrinkage porosity cause failure of chromium cobalt alloys
the alloys shrink about 2.3% and the result is porosity
why does low percent elongation cause failure of chromium cobalt alloys
directly related to greater brittleness
why does excessive carbon in the alloy cause failure of chromium cobalt alloys
reacts with the other constituents to form carbides
