Bridge Pontics and the Edentulous Ridge Flashcards
What do we need to know about the edentulous ridge after an extraction?
- a greater amount of alveolar ridge loss following extraction usually occurs in the horizontal dimension and affects the buccal bone of the ridge
- Loss of vertical ridge height can also occur and usually takes place along the buccal aspect of the ridge to a lesser degree than horizontal ridge loss
- The combination of this resorptive pattern results in a ridge that has moved in a palatal/lingual direction and has atrophied vertically
the edentulous ridge after an extraction
A greater amount of alveolar ridge loss following extraction usually occurs in the ______________ dimension and affects the ____________ bone of the ridge
horizontal
buccal
the edentulous ridge after an extraction
____% of alveolar bone dimension can be lost after tooth extraction, with losses reported of up to 6–7 mm
50%
the edentulous ridge after an extraction
Two-thirds of this loss of bone volume can occur within the first _______ months of tooth extraction
three
the edentulous ridge after an extraction
Loss of vertical ridge height can also occur and usually takes place along the ________ aspect of the ridge to a lesser degree than horizontal ridge loss.
buccal
the edentulous ridge after an extraction
Reductions in vertical ridge height ranging from ______ mm have been noted
2–4
the edentulous ridge after an extraction
ridge after an extraction?
Sockets that were preserved with bone grafting and/or membrane on average lost ___ mm less of ridge width, ___ mm less of ridge height, and had ____% more bone volume when compared to sockets that were not grafted
2mm
1mm
20%
the edentulous ridge after an extraction
What loses more bone… maxillary sites or mandibular sites?
maxillary
Before a tooth is extracted what needs to be considered?
consider whether the patient desires to restore this space (implant or bridge) and if so, to analyze the socket for grafting to preserve as much bone as possible
What is the frequency of a class I deformity after an extraction?
F-L Width (32%)
What is the frequency of a class II deformity after an extraction?
O-G Height (3%)
What is the frequency of a class III deformity after an extraction?
F-L and OG Height (56%)
What is the frequency of having a normal or no deformity after an extraction?
8%
What is the pretreatment assessment for a pontic?
- Evaluate the dimensions of the Edentulous space
- Evalutate the positions of the abutment teeth to assess the favorability for a bridge
- Evaluate the possible occlusal outcomes
- Is there a need to reposition the teeth orthodontically prior to fixed work?
Diagnostic Wax up is key to answer these questions before you begin treatment
What materials are used for pontics?
- cast metal
- metal-ceramic
- zirconia or all ceramic
When two materials are used, the finish line for their joining should not be on the…
edentulous ridge
What are the ideal characteristics we look for in a pontic design for esthetics?
-Appearance of replacement
-Replication of “emergence” from ridge
What are the ideal characteristics we look for in a pontic design biologically?
-Ability for the patient to clean well around the bridge/pontic area
-Allows for healthy tissue
-Patient comfort of bridge
-Harmonious occlusion
What are the ideal characteristics we look for in a pontic design mechanically (strength)?
-Rigid framework to resist deformation or fracture
Ideally, a pontic should have the same __________ height as the original or neighboring tooth
inciso-gingival
When resorption of the bone has taken place, the pontic changes shape in order to keep in contact with the…
ridge concavity
_______ of a pontic needs to be blended smoothly to avoid a ledge at the cervical.
Contour
For a pontic, the facial surface is altered to curve gently from the ________________ to the ___________ of the facial surface
gingival-facial to the middle
For a pontic, contour in _________ should approximate the length of the adjacent teeth
Apical ½
What can happen if the pontic does not adapt well?
esthetics, speaking, and food impaction can become troublesome
Pontic ridge contact should ideally be on __________ tissue
keratinized
What happens if you put a pontic on non-keratinized tissue?
ulceration and constant irritation can occur
How should the contact be between the tissue/ridge and the pontic?
- Pontic contact with ridge should not inflict pressure on the tissue
- Contact with the tissue should be minimal
- Pontic shape in contact with tissue should also be convex
What happens if the tissue contact with the pontic is too light?
food impaction, esthetics compromised
What happens if the tissue contact with the pontic is too heavy?
tissue/bone resorption
_________ shape of gingival aspect of pontic allows for easier cleaning for patient
Convex
What are different options for oral hygiene under a pontic?
- Floss Threader
- Super Floss
- Proxabrush
- Rubber Tip
- Water Pik
What is the order of material strength?
Metal > Zirconia > Porcelain > Acrylic
Pontics placed outside of the inter-abutment axis creates _________ on the connectors and abutments which can lead to failure
torque
________ is the biggest reason why we see mechanical failure in bridgework
occlusion
What are the different pontic designs?
- ridge lap (saddle)
- hygenic-perel modification
- modifd ridge lap
- conical
- ovate
What is a ridge lap (saddle) pontic? What are the pros/cons?
-Also known as a Saddle pontic
-Not used any longer
-Forms a large CONCAVE contact area with ridge
-Patient not able to clean
-Creates tissue inflammation leading to tissue ischemia and necrosis
What is a hygenic pontic? What are the pros/cons?
-Also known as Sanitary Pontic
-No contact with Ridge
-at least 2-3mm of space between the ridge and the pontic
-Patient can easily clean without the pontic being a food trap
-Only for use in non-esthetic areas
-Design and shape is CONVEX in all directions.
What is a modified hygenic-perel pontic? What are the pros/cons?
- To increase strength of bridge in connectors with hygenic pontic
- Deflection is increased with less occlusal gingival height. So, lets beef up those connectors!
What is a conical pontic? What are the pros/cons?
-Passive contact with ridge crest
-Rounded and cleansable
-Triangular embrasure space can trap food
-Best suited for thin mandibular ridges
-Also not best for esthetic areas.
What is a modified ridge lap pontic? What are the pros/cons?
-Passive contact facial side of ridge crest
-Can appear very esthetic
-Convex tissue surface contact
-Used frequently in the esthetic areas
-Shape can help keep food from trapping
-Cleansibility much easier for patients
What is a ovate pontic? What are the pros/cons?
- Blunt rounded Pontic shape that is set into a concavity in the tissue of the edentulous ridge
- Cleansable by well educated and motivated
patients - Highly Esthetic
What do you need to do before making an ovate pontic?
Generally requires planning
-Pre-Prosthetic surgery via immediate provisionalization after extraction
-Surgery/modification with provisional to develop tissue shape and contour
-Ovate Pontics keep a slight pressure on the tissue to maintain the effect of emerging from the ridge
________________ is the most common type of pontic because it is esthetic but requires much less effort on the part of the doctor and patient
Modfied Ridge Lap
Connector design is important for the _______ of the FPD.
strength
Typical Connector dimensions are…
Height _____ mm
Width ______ mm
Height 3-4 mm
Width 3-4 mm
Gingival Embrasure form better to be ___ shaped than V shaped
U
Connectors are shaped to be concave in the Buccal Lingual AND the Mesial Distal _________ the ridge.
TOWARD
If you increase the height of the connector you increase the…
strength
Height x2 = increased strength by a cube (x3)
Connectors are designed large enough to prevent fracturing, but not to impinge on…
embrasure and physiological contouring
Anterior connectors are placed more ________ for esthetics
lingually
Anterior connectors are longer ___________ for strength
inciso-gingivally
Anterior connectors considered ”__________” shape
Tear Drop
In posterior connectors, what width is more important for strength: buccal-lingual or occluso-gingival?
occluso-gingival
Posterior connector shape is considered “_____________”
heart shaped
In an all ceramic bridge, connector size is at least ___mm and possibly needs to be larger
4mm
U shaped connectors need a large ________ at the gingival embrasure
radius
Strength is a challenge thus far and there is an increased fracture potential with __________ bridges
all ceramic
Both Full Zirconia and Zirconia based (PFZ) show excellent strength and fracture resistance WHEN the __________ are of the appropriate size.
connectors
Metal frameworks are assembled in two ways:
- Cast/milled as one piece
- Two or more pieces are soldered together (metal only).
Single Piece casting issues to watch for:
- distortion
- challenging to verify fit
How are longer span bridge usually cast?
cast in multiple pieces and soldered together
If your framework has distorted or you have two large pieces of framework to try in, how do you reconnect them?
- Soldering – joining of metals by fusion of filler metal bonding to each of the parts being joined
- Brazing – A specific form of soldering when the filler material has a melting temperature above 450 degrees Celsius.
What is soldering?
- Joining of metals by fusion of filler metal bonding to each of the parts being joined.
- The bond is created by wetting the surface of parent metals with liquified solder
- The metal framework does not melt during this
What is brazing?
A specific form of soldering when the filler material has a melting temperature above 450 degrees Celsius
What do we desire solder to do
for us?
-Resists tarnish and corrosion
-The fusion temperature 100-150 degrees Fahrenheit below that of the substrate metal
-Free flows when melted
-Resists pitting
-Is strong
-Matches color of the two parts being joined.
What factors affect the accuracy and prognosis of soldered connectors?
- Connector Space
- Metal Surface Preparation
- Indexing Technique for Investment
What does a connector space allow for?
- allows the solder to flow in between
- allows for thermal expansion and shrinkage of the solder
- parallel and flat with a space for thickness the size of a business card (0.2mm)
A proper space is small enough to…
minimize distortion from the solder shrinkage as it cools
A proper space is also large enough to allow for a…
strong connector
What is the indexing technique for investment?
- Flow auto-polymerizing acrylic resin into space to hold two pieces together. Each side should be fully seated with margin integrity checked and verified.
- Make an occlusal plaster index to send to the lab for soldering. Framework should be solidly planted in plaster index so that enough of the coronal portion is covered so framework can be held in place.
What is pre-ceramic veneer soldering?
- Uniting components of the same alloy BEFORE porcelain is fired.
- Uses high-fusing solder (is stronger)
- Melt solder with a torch
- Solder has lower melting temp than alloy, but higher melting temp than porcelain firing temperature
- Less Technique Sensitive
What is post-ceramic veneer soldering?
- Uniting components of the same alloy AFTER
porcelain is fired - Uses low-fusing solder (is not as strong)
- Melt solder in oven
- Solder has lower melting temp than alloy and
porcelain - More Technique sensitive
Why can you not add porcelain after post-ceramic veneer soldering?
Temp of Porcelain firing too high. You’d melt the low fusing solder.
How do you fix an open contact with an All metal or PFM crown?
additional soldering
- adding material to contact area smoothing and shaping contact area
