Outcome 5 - Fixed Prosthodontics Flashcards
Define Fixed Prosthesis
The prosthesis is permanently cemented into place and cannot be removed by the patient
Indications for Dental Prosthesis
When there is not enough naturual tooth structure remaining to retiain a new restoration - more coverage with a dental prosthesis may be advised. This can also occur as a result of extensive decay or the loss of tooth structure through disease/trauma
How treatment plan for an indirect restoration is determined?
-Patient History
-full mouth radiographs/specific area radiographs
-intraoral examination
-diagnostic models
-diagnostic models mounted on an articulator
-face bow records
What are indirect restorations?
Unlike restorative restorations such as amalgam or composite, they are not placed directly into the mouth but are made indirectly outsode of the mouth then “fixed” or cemented into place in the mouth permanently
What can restorations be fabricated from?
Gold, precious metal alloys, porcelain, ceramic or combinations of both
What are Inlays?
Restorations resemble class II not involving dental cusps
What are Onlays?
Restoratios involving dental cusps
What are veneers?
Made from porcelain or other ceramic. They are fabricated by technicians in a dental lab and are bonded to the facial surface of prepared anterior teeth by the dental team. These veneers are very aesthetic as porcelain has a more natural appearance and reflects light in much the same way as enamel.
What is a Crown?
A Crown is an indirect restoration that covers all or almost all of the anatomic portion of the tooth.
What is a full crown?
Covers the entire anatomic portion of the tooth
What is a 3/4 Crown?
Usually leave sone surface intact. This surface is often the labial or facial surface with the Crown covering the lingual
What is a bridge?
A bridge is a fixed prosthetic replacement for one or two missing adjacent teeth where there are strong supporting teeth on each side of the gap. The replacement teeth are called pontic and are connected to full crowns on either side of the gap, called abutments.
What are Implant Assisted Crowns & Bridges?
Dental implant is used when natural tooth has been lost. Dental implant is an artificial anchor (post like) that is surgically placed into the bone. Dental implant act as the “root of the tooth” Dental crown or bridge is added to aid intra-oral function. Dental implants are used in fixed and removable prosthetics.(removable prosthetics s will be discussed next semester)
What are Computer Assisted Prosthetics?
Computer assisted restorations use an in-office ceramic restoration system. These systems are often referred to as CAD/CAM which means Computer Assisted Design or Manufacturing. Advantages of using these machines include: one visit procedure, no impressions required, no temporary restoration required, and no outside laboratory costs.
What is a CEREC machine?
uses computer imaging to custom fabricate a ceramic inlay, onlay or crown in the office, within approximately 90 minutes.
What is Core Buildup?
If the tooth is vital, the procedure to create crown length or support is called a core buildup. The core buildup is created in a procedure very similar to a restorative filling.
-Amalgam or Composite resin are often used as core buildup materials though there are reinforced glass ionomer materials specifically designed for core buildup situations
-Retentive pins may also be necessary to retain the core buildup. These must be placed before the core buildup into tooth structure and then incorporated into the buildup material.
- In either case, the core is placed and then reduced in the same way that natural tooth structure would be for the crown or abutment prep
What is a Post & Core?
If the tooth to be crowned had endodontic treatment and lacks support, a post may be placed into one of the filled canals and then a core built up around it. These can be pre-fabricated posts or cast post and cores fabricated by a dental laboratory.
A prefabricated post is cemented deep into one of the canals with a portion remaining out of the canal on which the core material is placed.
Any type of core buildup material can then be placed over the post, which is then reduced again in the same way that natural tooth structure would be for the crown or abutment preparation. A cast post and core is generally made as one unit in the lab. The material used can be metal, resin or ceramic.
What kind of Bonding Systems?
Dentin bonding systems can also be used to create micromechanical retention between the tooth structure and prosthesis.
- Can be self curing or dual cured and can use either a single application or may require the mixing of two materials
- This bonding is usually micro-mechanical in nature and occurs when the surface of the restoration has been microetched
- includes etching of the dentinal tubules, placing a bonding resin or agent and then applying the bonding material to secure the prosthesis
This procedure is the most common method of adhering veneers, but is also often used for ceramic crowns. It is the most complex and time consuming method.
What is Mechanical Tissue Displacement?
Tooth preparation for a fixed prosthetic extends to or slightly below the gingival margin of the tooth. The impression for laboratory fabrication of the prosthetic must extend into the sulcus for accurate replication of the margin. The free gingiva must be retracted and the sulcus widened to enable the impression material to flow around and beyond the margin of the tooth preparation.
Methods of Gingival Retraction?
Physical/Chemical Retraction
Surgical Retraction
What is the most common method of gingival retraction?
Through the placement of a retraction cord within the gingival sulcus
What is Physical / Chemical Gingival Retraction?
Placement of retraction cord within the gingival sulcus
-cord physically forces the gingival tissue away from the tooth, widening the sulcus
-the cord remains within the sulcus for a short period of time and is removed immediately prior to insertion of impression material
What are the Chemical Solutions used during Gingival cord retraction?
-often refered to as hemostatic solutions
-may include aluminum chloride, epinephrine, or ferric sulfate
- tissue management is achieved through the use of chemical agents introuduced to the tissue via the retraction cord to temporarily contract the tissue and act as a vasoconstriction which will control any bleeding that may have been initiated in preparing the tooth.
Other methods of physical gingival retraction?
Cordless retraction materials - provide retraction by injection of a paste like material infused with a hemostatic solution
Gingival Surgical Retraction
alternative to retraction cord placement when there is excess tissue or a deeper sulcus
Dentist uses an electrosurgical tip to cauterize tissue within the inner surface of the sulcus and reduce the crest of the gingiva when necessary
- physically widens the sulcus and controls hemorrhaging
- dental laser is often used to remove excess tissue nowadays
Types of Retraction Cords
- available in different types and thicknesses
- untwisted, twisted, braided or knitted
- may be impregnanted with epinephrine and astringent by the manufacturer for hemostasis (control of bleeding) and contraction of the tissue
- may be non-impregnated for patients with cardiovascular disease
One-Cord Placement Techniques
involves placement of a one cord (size will be indicted by the dentist) to displace tissue
Double-Cord Placement Techniques
can be used when there is greater sulcus depth
involves the use of a smaller cord thickness first following with the thicker cord second
the smaller cord can be left in place while the final impression is being taken
What are interim prosthestics?
Crowns or bridges that are temporarily cemented to a tooth while the permanent prostheses are being fabricated by the dental laboratory. Used to maintain function in that area of the mouth and keep the patient comfortable. Can remain in place from 2 weeks to 1 month
Safety when placing gingival cord
Care and technique must be taken when placing the cord to avoid damage or detachment of the junctional epithelium. Tissue damage requires up to 14 days to heal, but permanent loss of gingival crest height may result.
Interim Prosthetics must meet the following criteria:
- Pulpal Protection
- Positional Stability
- Occlusal Function
- Access for Oral Hygiene
- Physiologic Contours
- Accurate Margins
- Esthetics
- Easy Removal
Pulpal Protection for Interim Prostheses
-prepared vital teeth must be completely covered to protect the pulp from thermal & chemical irritation caused by foods, liquids, bacterial plaque and the passage of air during breathing
Positional Stability for Interim Prosthetics
Interim Crowns or bridges must stabalize the prepared teeth. Resorations should not rock from side to side when seated in the patients mouth
Occlusal Function for Interim Prosthetics
-interim crown/bridge must produce a stable occlusal relationship with the oposing teeth. Lack of occlusal contact can allow the tooth to over-erupt to establish contact, necessitating adjustment of the final restoration. An occlusal contact that is too heavy can cause tooth mobility, sensitivity, or damage to the pulp. Occlusal contact should ideally be lighter on the interim restoration than the adjacent teeth, but still mark with the articulating paper
Access for Oral Hygiene for Interim Prosthetics
With an interim bridge, the embrasures must be open to allow for adequate space for the interdental papillae and provide access for cleaning. A pontic that impinges on tissue could cause irritation and will prevent the patient from practicing proper flossing. There should not be loss of mesio-distal space. Interim crowns that do not have adequate contour for contact can allow tooth movement, resulting in a final restoration that does not seat properly on the prepared tooth
Physiologic Contours for Interim Prosthetics
Crowns that lack appropriate contours affect the health of the tissue. Incorrectly contoured or bulky crowns can also result in the patient catching their lip or cheek on the crown or other structures or tissues. Interim prosthetics should resemble natural tooth anatomy
Esthetics for Interim Prosthetics
Interim crowns should resemble the natural teeth in contour, shade, and function. They should also help maintain the normal esthetic position of the lip and cheek
Removal for Interim Prosthetics
-interim crown or bridge should be removed easily without damage to the prepared tooth or gingival tissues. REmoval can be accomplished with finger pressure, PFI, crown removing instument, Howe pliers.
Removal of interim prosthetics using Howe Pliers
the beaks of the pliers are placed on the vestibular and lingual surfaces of the interim crown/bridge. A gentle rocking back and forth motion should be used until the seal between the tooth and cement is broken.
Removal of interim prosthetics using PFI
Crown - The blade is placed at the crown margin. Pressure is applied away from the tissue to break the seal.
Bridge - alternate between abutment teeth with a gentle rocking motion to break all seals. This prevents too much pressure from being applied to one tooth
Laboratory Steps
- Transportation
- Computer recording of case details
- Pouring of models
- Setting of the articulator
- Waxing of the prosthetic
- Finishing and polishing of the metal structure/substructure
- Porcelain work
- Final finshing and polishing
- Final computer entry and billing
- Transportation
Amout of time required by dental laboratory to complete steps?
5-7 working days, unless the case is very complicted.
How are impressions transported to dental laboratory?
Most dental labs have their own courier to come to your office to pick up the “case”
How does the dental laboratory record your case details?
The reception personnel create a computer record for tracking and billing of the case
How does the dental laboratory pour models?
Specialized technicians pour up the working casts required to fabricate the fixed prosthetic. The models are poured in a very different way than in a dental office in order for the “die” of the prepared tooth to be removed from the rest of the cast.
How does the dental laboratory set the articulator?
The bite registration is sued to properly set the casts onto an articulator. This enables the technicians to simulate the patient’s occlusion during construction of the prosthetic restoration.
How does a dental laboratory wax a prosthetic?
The lab techs create any portion of the prosthetic that is to be made of metal alloy in wax on the die. This wax will eventually be metled away and replaced with the molten metal alloy of choice.
