Fixed Prosthodontics Lecture 5

Types of Fixed Bridges

• There are 12 types of fixed bridges: Fixed Fixed Bridge, Fixed Movable Bridges, Cantilever Fixed Bridges, Spring Cantilever Fixed Bridges, Fixed Removable Bridges, Modified Fixed Removable Bridges, All Metal Fixed Bridges, Metal-ceramic Fixed Bridges, All Ceramic Fixed Bridges, All Acrylic Fixed Bridges, Fiber-reinforced Composite Resin Bridges, and Resin-bonded Fixed Bridges

Fabrication of Fixed Bridges

• The pontics and retainers are fabricated as a single unit pattern
• Multiunit wax patterns are cast separately and approximated against each other and soldered together using a different soldering alloy
• Alternatively, a single unit wax pattern is cast, sectioned using a saw, and then soldered

Soldering in Fixed Bridge Fabrication

• Used to join multiple units together
• Preferred because it avoids galvanic corrosion
• Soldered connectors are uniform, flat, and parallel due to the controllable flow of the solder alloy

Electrosurgical Procedures and Medical Conditions

• Electrosurgical procedures are avoided in patients with pacemakers.
• Adrenaline may be avoided in local anesthetic and during retraction procedures in patients with hypertension.
• Uncontrolled diabetes mellitus can lead to periodontal breakdown and affect prognosis.
• Xerostomia (dry mouth) can lead to caries affecting restoration margins.
• Patients with certain medical conditions, such as pacemakers, may need to discontinue medications before surgical procedures.

Dental History

• Obtaining a dental history provides information about previously rendered dental treatment.
• It highlights genetic predisposition to periodontal disease, malocclusion, and facial deformities.
• It also reveals cause for tooth loss, complications following dental procedures, and patient attitude towards oral hygiene measures.

Clinical Examination

• Clinical examination involves the clinician's use of sight, touch, and hearing to detect conditions outside the normal range.
• General appearance includes gait, weight, skin color, and vital signs (respiration, pulse, temperature, and blood pressure).
• Fixed Prosthodontics involves diagnosis and treatment planning.

Diagnosis and Treatment Planning

• Diagnosis is the determination of the nature of the disease process.
• A good diagnostic work-up includes seven elements: chief complaint, vitality testing, history, extra-oral examination, intra-oral examination, diagnostic casts, and radiographic evaluation.

Chief Complaint

• The chief complaint should be recorded in the patient's own words.
• It should analyze the patient's primary reason for seeking treatment and reveal problems and conditions of which the patient is often unaware.
• Complaints usually belong to one of the following categories: comfort, function, social, or appearance.

History

• A patient's history should include necessary information concerning the reasons for seeking treatment, as well as personal details and past medical and dental experiences.
• A screening questionnaire is useful for history taking.
• Medical history should include any medication the patient is taking and all relevant medical conditions.

Extra-Oral Examination

• Facial asymmetry, cervical lymph nodes, TMJ, and muscles of mastication are assessed.

Diagnostic Aids

• Radiographs, vitality tests, diagnostic casts, and periodontal probes are used as diagnostic aids.

Intra-Oral Examination

• The patient's general oral hygiene is observed, and the presence or absence of inflammation, gingival architecture, and stippling are noted.
• Pockets and tooth mobility are recorded with special attention to any relationship with occlusal prematurities and potential abutment teeth.

Radiographic Evaluation

• Radiographs are examined for caries, P.A lesions, previous endodontic treatment, alveolar bone level, crown-root ratio, root configuration, and direction of root.
• The presence of retained root in edentulous areas is recorded.

Vitality Testing

• Pulpal health must be assessed, usually by measuring the response to percussion, thermal, and electrical stimulation.

Diagnostic Casts

• Diagnostic casts are mounted on a semi-adjustable articulator to assess the edentulous space, abutment teeth, and path of insertion.
• They are used for diagnostic wax-up, constructing special trays, and provisional restorations.

Ideal Treatment Plan

• An ideal treatment plan achieves the best possible long-term outcomes for the patient while addressing all patient concerns and active problems with the minimum necessary intervention.

Occlusion

• In some cases, the abutment teeth are sound, but there is insufficient space for a minimal-preparation retainer, so the choice is between creating space by reducing the opposing teeth, moving the abutment teeth orthodontically, or a combination of these approaches.

Cost

• Partial crowns and complete metal crowns may be less expensive than metal-ceramic crowns.
• Minimal-preparation retainers are the least expensive.
• All-ceramic crowns are the most expensive.

Pontics

• A pontic is an artificial tooth that replaces a missing natural tooth, restoring its function and usually filling the space previously occupied by the clinical crown.
• Ideal requirements of a pontic:
  • Restore function of the replaced tooth.
  • Provide aesthetics and comfort.
  • Be biologically acceptable.
  • Permit effective oral hygiene.
  • Preserve the underlying residual ridge and mucosa.
  • Have adequate strength to withstand occlusal forces.
• Classification of pontics based on the amount of contact with the underlying mucosa:
  • With mucosal contact:
    • Advantage: Aesthetically superior.
    • Disadvantages: Difficulty in cleaning, potential tissue inflammation.
  • Without mucosal contact (hygienic pontic):
    • Advantage: Good access for oral hygiene.
    • Disadvantage: Poor aesthetics.

Crowns

• A crown is a fixed extra-coronal restoration that restores missing tooth structure by surrounding most or all of the remaining structure with material.
• Types of crowns:
  • Full veneer crown: Involves all surfaces of the clinical crown.
  • Partial veneer crown: Covers some of the tooth crown and leaves the other intact (e.g., 3/4 crown, 7/8 crown, pin ledge, etc.).
  • Laminate veneers: A conservative method of restoring the appearance of discolored, pitted, or fractured anterior teeth, consisting of bonding thin ceramic laminates onto the labial surfaces of affected teeth.
  • Complete replacement (Post crown): Replaces the natural crown entirely, retaining itself by means of a dowel (post) extended inside the root canal space of the tooth.

Abutment and Retainer

• An abutment is a tooth to which a bridge (or partial denture) is attached.
• A retainer is a crown or other restoration that is cemented to the abutment.
• The terms 'retainer' and 'abutment' should not be confused or used interchangeably.

Bridge Components

• A span is the space between natural teeth that is to be filled by the bridge.
• A unit, when applied to bridgework, means either a retainer or a pontic.
• A connector (or joint) connects a pontic to a retainer, or two retainers to each other.
• Connectors may be fixed or allow some movement between the components that they join.

Retainer Selection

• Criteria for selecting a particular retainer include:
  • Alignment of abutment teeth and retention.
  • Appearance.
  • Condition of abutment teeth.
  • Conservation of tooth tissue.
  • Occlusion.
  • Cost.

Classification of Fixed Partial Dentures

• According to the location of the edentulous space:
  • Posterior: Fixed partial denture confined to the posterior region.
  • Anterior: Fixed partial denture confined to the anterior region.
  • Combination: Fixed partial denture extending both anteriorly and posteriorly.
• According to the location of the abutment:
  • Conventional: Abutment is located adjacent to the edentulous space and pontic is supported on both sides.
  • Cantilever: Abutment is located adjacent to the edentulous space but pontic is supported on one side only.
  • Spring cantilever: Abutment is not located adjacent to the edentulous space and pontic receives support from one side only.

Types of Connectors

• Fixed-fixed: Connectors on both sides of the pontic are rigid with no scope for any movement.
• Fixed-movable: One of the connectors of the FPD assembly is non-rigid and is made of a precision or semiprecision attachment which allows some vertical movement.
• Fixed-removable: This prosthesis was developed by Dr. James Andrews and is called 'Andrews Bridge'.

Materials Used

• All metal: Used only to replace posterior teeth, not aesthetic.
• Metal ceramic: Also termed as 'porcelain fused to metal' (PFM) crowns/retainers.