Casting alloys and implants (Ch 11 and 12) Flashcards
(32 cards)
1
Q
what is an alloy
A
- combination of metals
- made using the ‘lost wax technique’
- gold alloys = not pure gold
2
Q
what does the ADA classify dental casting alloys based on (3 categories)
A
- high noble
- noble
- base metals
3
Q
what is the purpose of a gold alloy
A
- by combining gold with other metals to form an alloy, it creates the characteristics and hardness required as an excellent choice for an indirect restoration
4
Q
what is palladium
A
- gold alloy
- good corrosive resistance
- increases hardness of the alloy
- was less expensive but currently is more expensive than gold
5
Q
what is platinum
A
- gold alloy
- expensive
- high melting point
- difficulty mixing with gold
6
Q
what is high noble
A
- 60% noble elements
- 40% must be gold
- 20% palladium and platinum
- base metals make up the remaining 40%
- does not tarnish or corrode
- usage declining because of high cost of gold
7
Q
what is noble
A
- 25% noble elements, no requirement for gold
- 75% consists of base metals
8
Q
what are base metals
A
- less than 25% noble elements
- primary base metals used for cast alloys
- copper
- silver
- nickel
- zinc
- tin
9
Q
what is the biocompatibility of noble metals
A
- more biocompatible because they corrode less than base metals
10
Q
what can cause allergic reactions in base metals
A
- contain nickel and beryllium
- nickel has an incidence of 9-12% allergy in population
- greater incidence in women, thought to be due to nickel in jewelry
11
Q
what are wrought metal alloys
A
- an alloy that has been mechanically changed into another form to improve its properties
12
Q
what are wires
A
- wrought metal alloys
- clasps on prosthetic appliances
- lingual arch wires
- ligature wires for ortho and oral surgery for jaw fractures
- preformed provisional crowns: mostly for pedo to maintain tooth till it exfoliates, not used widely in adults
- endodontic files: twisted wire to produce cutting edges to clean and shape canals
- composed of base metals
13
Q
what are arch wires made of
A
- stainless steel
- cobalt-chrome-nickel
- titanium
- or an alloy of nickel and titanium called nitinol
14
Q
what do wires do
A
- resist deformity
- resistance creates ‘memory’
- wire tries to return to its original shape
- is it the ‘memory’ that exerts the forces that move the teeth
15
Q
what is the gauge of the wire
A
- diameter of the wire
- gauge is numbered by thickness
- thicker the wire = smaller the number
- thinner wire has more memory
16
Q
what are brackets and bands
A
- cemented onto the teeth
- formed from stainless steel alloys/plastics
- retain the arch wires (arch wires are held to the brackets by ligature wire or elastics)
17
Q
what are lingual retainers
A
- placed after orthodontic tx
- long-term stabilization
- ensures patient cooperation
- obstacle to flossing
- wire adapter to the lingual surfaces
a) a thick wire bonded on the cuspids or
b) thin wire bonded on each tooth
18
Q
what are implant materials used to replace
A
- one or more single units
- support a full denture
19
Q
what are the 3 main types of implant materials
A
- subperiosteal
- transosteal: a) severe resorption, b) lacks support
- endosteal (endosseous): most widely used; single tooth replacement for supporting CUD, partial, fixed bridges; good success rate (see pics in ppt)
20
Q
what are the 2 different types of implants
A
- one stage: good bone quality; sufficient bone; good initial stability; crown places
- two stage: safer/more conservative; lacks bone support; denture cases
stage 1: implant
stage 2: healing abutment
21
Q
what materials are used in implants and why
A
- titanium
- titanium alloys
- why?: osseointegration: the process whereby bone grows around a titanium implant
22
Q
how does osseointegration happen
A
- surface layer of oxides integrate with bone
- some implant metals have: a surface coating of a thin layer of calcium phosphate (in the form or hydroxyapatite) or plasma proteins
23
Q
what are some contraindications for implants
A
patients who:
- have medical condition (advanced cardio/respiratory disease)
- conditions that affect ability to fight disease (diabetes)
- bisphosphonates - osteoporosis
- compromised immune system
- smokers
- patients unable to conduct good OH
24
Q
what are some indications for using implants
A
- able to restore dentition
- preserving tooth structure
- gingiva is healthier
- preserves bone because not resorbing if placed soon after exo
- complete dentures - better function
- esthetics
25
what is home care like for implants
- customized
- use disclosing agents: check daily for first few weeks, check periodically after patient becomes proficient at cleaning, give disposable mouth mirror
- brushes: use ultra soft bristles, interproximal burgess with nylon coating, end tuft brushes (heating the plastic handle), electric brushes, non-abrasive tp
- floss: thicker floss, superfluous, yarn, gauze strips, wooden plaque removers
26
what antibacterial agents should be used with implants
- chx: 1-2 weeks after second surgical stage; swish gently for 30 seconds, 2x/day; apply directly with inter proximal brush; stains
- essential oil rinse
- biological seal with epithelium
27
scaling for patients with implants
- 3 month recare for one year
- 4 month recare for second year
- 6 month recare after
- use plastic instruments
- graphite curettes
- metal instruments with teflon or gold coating
- special ultrasonic scalers for implants
28
questions to ask patients with implants
- implant mobility
- soreness
- bleeding of periodontal-implant tissues
- looseness of the prosthesis
- pain with chewing
29
what should we be looking for visually in patients with implants
- swelling
- erythema
- bleeding
- other indications of developing problems
30
what kind of probe should be used on perio patients
- plastic probe with light touch
31
things not recommended for patients with implants
- polishing
- conventional steel curettes
- US scalers
- air polishers
32
what is implant failure and what might cause it
- lack of bony integration with the implant
- due to:
1. poor surgical technique, excessive heat when drilling
2. infection of the implant site
3. poor quality of bone
4. placing loading forces on the implant too soon
