Failures In Bridge/Fixed Partial Denture

FAILURES IN FIXED PARTIAL DENTURE


CONTENTS

A bridge is a custom-made device anchored to neighboring natural teeth, which replaces one or more missing teeth. When a lost tooth is replaced with bridgework, the teeth on either side of the missing one are prepared as crowns to hold the bridge in place. Bridges, sometimes referred to as a fixed partial denture, look natural and literally bridge the gap where one or more teeth may have been. Fixed bridges appear and function similar to natural teeth.


INTRODUCTION:
DENTAL RESTORATIONS ,NO MATTER HOW CAREFULLY PLACED, MAY REQUIRE MODIFICATION OR
REPLACEMENT. THE ORIGINAL EVALUATION AND TREATMENT SHOULD HAVE ENSURED GOOD ABUTMENT SELECTION , CROWN PREPARATION WITH ADEQUATE MARGIN PLACEMENT, PONTIC DESIGN AND CORRECT OCCLUSION.  NO GUARANTEE CAN BE GIVEN CONCERNING THE LONGEVITY OF ANY PROSTHESIS .  PATIENTS SOMETIMES CAN PRESENT WITH ONE OF A NUMBER OF MAJOR PROBLEMS AFTER CROWNS OR FIXED PARTIAL DENTURES HAVE BEEN CEMENTED.

CAUSES OF FAILURE

  • Caries
  • Pulp degeneration
  • Periodontal breakdown
  • Occlusal problems
  • Tooth perforation
  • Temperomandibular disorders
  • Mechanical failures:
  • Loss of retention
  • Connector failure
  • Occlusal failure
  • Cementation failure
  • Tooth fracture/ root fracture
  • Porcelain fracture
  • Maintenance failures
  • Esthetic failures
  • Facing failures

Caries:

  • One of the most common biologic failures.
  • Usually perceived by the patient as
  •  Pain or sensitivity to hot ,cold or sweet foods & liquids.
  • Dysgeusia
  • Halitosis
  • Loose restorations
  • Fractured teeth
  • Discolored teeth

Small lesions :

  • Gold foil – filling material of choice for restoring marginal caries.
  • Amalgam – best alterative to gold foil filling because ofits ability to produce long term marginal seal.
  • Composite – indicated for restoration of caries in esthetic zone.
  • Glass ionomer cement.
  • Proximal lesions :
  • Removal of prosthesis is required to obtain access to caries.
  • If the lesion is small, the tooth preparation can be extended to eliminate the caries and a new prosthesis can be fabricated.
  • When the lesion is large, an amalgam restoration is often required.
  • An extensive lesion may require endodontic treatment when pulp has been encroached.
  • A grossly destroyed teeth by caries that cannot be restored must be extracted.
  • Schwartz et al (1970) & Randow et al (1986) both reported caries to be the most frequent cause of failure of existing restorations (36% & 18.3%).
  • Glantz et al .in 1993 reported that of 77 bridges reviewed at 15yrs , 32.5% required removal. Further reported in 1993 that the incidence of caries was not related to the age of the patient , rather , to the time that the bridge had functioned .

Pulp degeneration:

  • This is usually perceived by the patient as:
  • pain – either spontaneous or related to hot or cold or sweet stimuli.
  • pain which is accentuated by lying down or exercise

Causes :

  • Extensive preparation
  • Excess heat generation during preparation
  • Indication for endodontic treatment
  • Post insertion pulpal sensitivity on abutment teeth that doesn’t subside with timeà intense painà periapical pathology detected radiographically

Management:

  • Access preparation – a hole is drilled in the prosthesis through which the biomechanical preparation (BMP) is completed.
  • The access cavity is restored with
  • Gold foil
  • Amalgam
  • Cast metal inlay
  • If the retainer come loose during access opening or if the porcelain fractures, then remaking of the prosthesis may be necessary.
  • A post and core restoration should be considered if little sound tooth structure is remaining.
  • Survival of endodontically treated , post-restored teeth depends on a multitude of factors , all of which are practically impossible to include in a randomized , controlled clinical study.

Following conclusions were derived:

  • Fracture of the tooth was the most common type of failure among the failed post-retained restorations followed by loosening of the post & fracture .
  • Tapered posts more often displayed fracture of the tooth and less often fracture of the post.
  • Fracture of the post was more common among male patients than among female patients.
  • Periodontal breakdown:
  • This is usually perceived by the patient as:
  • Looseness of teeth or bridgework
  • Drifting teeth
  • Bleeding tissues
  • Changes in color of the gums
  • Bad breath
  • Bad taste
  • Pain
  • Abscess formation
  • Poor aesthetics
  • Periodontal disease can produce extensive bone loss , which in course of time results in the loss of abutment teeth and attached prosthesis.
  • Aspects of the prosthesis that interfere with effective plaqueremoval include:
  • Poor marginal adaptation
  • Overcontouring of the axial surfaces of the retainers
  • Excessively large connectors that restrict cervical embrasure space
  • A pontic that contacts too large an area on the edentulous ridge.
  • A prosthesis with rough surfaces which promote plaque accumulation.

Management :

  • Plaque accumulation àProphylaxis, removal of local factor
  • Tissue hyperplasia àGingivoplasty
  • Devitalized & severe bone lossà Endodontic procedure/ bicuspidization hemisection of teeth.
  • Less severe breakdown can be treated without fear of loss of teeth, with small surgery which may produce an unacceptablerelationship between prothesis & the soft tissue.

Occlusal problems:

  • Patients may be uncomfortable with their new occlusions.
  • Some patients tolerate gross occlusal discrepancies without complaining , whereas others are intolerant to discrepancies
  • in the range of 10-15 microns.
  • Occlusal discomfort is perceived by the patient as:
  • General discomfort with the “bite”
  • Sore teeth
  • Loose teeth or bridges
  • Sensitive teeth
  • “Tired” or “sore” muscles
  • Interfering centric and eccentric occlusal contacts can cause:
  • Excessive tooth mobility
  • Irreversible pulpal damage

Management :

  • When detected early occlusal adjustment should be done to eliminate these interferences without permanent damage.
  • Occasionally, a combination of excessive mobility and reduced bone support require extraction of abutment teeth.
  • Irreversible pulpal damage requires endodontic treatment.
  • Change in vertical dimension:
  • VD may be decreased as a result of severe attrition or increased as a result of poor restorative planning.
  • Porcelain occlusal surfaces in short clinical crowns-vd increases
  • Following symptoms may be perceived by the patient:
  • Altered facial appearance
  • Dribbling of saliva àloss of VD can precipitate “angular chelitis”
  • Extreme changes in VD can convert an asymptomatic
  • internal derrangement into a symptomatic one.àalteration in muscle activity can cause “myalgia”.
  • Extreme increase in VD reduces ability of tongue to create a seal during swallowing
  • Compensating movement of the larynx during swallowing
  • Muscle strain & symptoms such as “sore throat” or “tired tongue”
  • Teeth can become sensitive either due to loss of occlusal tissue or due to trauma to the teeth from the increased VD.
  • Clenching of teeth because of premature contact.
  • Loss of posterior vertical dimension à lower anterior teeth occluding more heavily with the palatal surface of the upper anterior teeth causing drifting or failure of anterior restorations.
  • Decrease in the VD can result in occluding of the lower incisors with the palatal soft tissues giving rise to soreness & possible periodontal complications.
  • Decrease or increase in VD
  • Difficulty in mastication
  • Gross increase in the VD
  • Speech problems particularly with sibilants.

Tooth perforation:

  • Improperly located pinholes or pins used in conjunction with pin-retained restorations may perforate the tooth laterally.
  • Management : depends on the location of the perforation.
  • Occlusal to periodontal ligament
  • Extend the preparation to cover the defect.
  • Extends into periodontal ligament
  • Perform periodontal surgery
  • Smoothening of the projecting pin
  • Place a restoration into perforated area
  • Furcation region
  • Surgically inaccessible
  • Severe periodontal problems may ultimately
  • lead to extraction of the tooth.
  • Pulp chamber
  • Endodontic treatment
  • Subpontic inflamation:
  • Perceived by the patient as :
  • Pain
  • Swelling
  • Bad breath
  • Bad taste
  • Bleeding gums
  • Poor esthetics

Leave a Reply

Your email address will not be published. Required fields are marked *