complications and Failures in FPD

Dr. Amar Bhochhibhoya, 2nd Batch, PG Resident, Dept. of Prosthodontics&

Maxillofacial Prosthetics, PDCH

Contents : Introduction

Terminologies Classifications of

failure/complication Management Review of literatures Conclusion References

“Nothing worthwhile is ever without complications.”

Nora Roberts Introduction

A realistic approach to fixed prosthodontics is that “total” success or “total” failure is seldom achieved. Between these extremes lies

a large grey area of partial failures and partial successes.

Knowledge regarding the complications and failures that can occur in fixed prosthodontics enhances the clinician’s ability to complete a thorough diagnosis, develop the most appropriate treatment plan, communicate realistic expectations to patients,

and plan the time intervals needed for post-treatment care.

Terminologies A complication has been

defined as “a secondary disease or condition developing in the course of a primary disease or condition.”

Merriam Webster’s Collegiate Dictionary. 10th ed. Springfield, MA: Merriam-Webster; 1993. p. 236.

A complication represents an unfavorable and unexpected outcome of dental treatment.

Kenneth J. Anusavice. Standardizing failure, success, and survival decisions in clinical studies of ceramic and metal–ceramic fixed dental prostheses. Dental Materials 28(2012) 102-111

Success may be defined as the achievement of treatment planning goals and expectations.

Kenneth J. Anusavice. Standardizing failure, success, and survival decisions in clinical studies of ceramic and metal–

ceramic fixed dental prostheses. Dental Materials 28(2012) 102-111

Survival was defined by percentage of FDRs that remained in situ with or without modifications.

Sailer I, Pjetursson BE, Zwahlen M, Hammerle CH. A systematic review of the survival and complication rates of all-ceramic and metal–ceramic reconstructions after an observation period of at least 3 years. Part II: fixed dental prostheses. Clin Oral Implants Res 2007;18(Suppl. 3): 86–96.

Restoration success is defined as the demonstrated

ability of a restoration (including a prosthesis) to perform as expected.

The success of dental restorations is described in the basis of multiple variables rather than survival percentages alone.

Failure represents the inability of a restoration to perform as expected under typical clinical and patient conditions.

Kenneth J. Anusavice. Standardizing failure, success, and survival decisions in clinical studies of ceramic and metal–ceramic fixed dental prostheses. Dental Materials 28(2012) 102-111

Failure was defined as removal or complication requiring replacement for a FPD, or loss of an abutment.

Mark S. Scurria, James D. Bader, and Daniel A. Shugars. Meta-analysis of fixed partial denture survival: Prostheses and abutments:J Prosthet Dent 1998;79:459-64.

Varieties of terminologies have crept into the dental terminology and they have complicated our classification of success and failure of crown and bridge restorations.

Chadwick et al. suggested many factors that affect the survival of dental restorations:

the type of dentition; site of the restoration;reasons for placement;caries status;age, sex and socioeconomic

characteristics of the patient; oral hygiene;

They indicated that the determination of failure is very problematic since there is no universally applied standard for dentists to determine the success or failure of restorations

Chadwick B, Treasure E, Dummer P, et al. Challenges with studies investigating longevity of dental restorations – a critique of a systematic review. J Dent 2001;29:155–61.

Hickel et al proposed three categories (esthetic, functional, and biological) to simplify clinical evaluation

procedures and to encourage a more detailed analysis of failures.

Hickel R, Peschke A, Tyas M, et al. FDI World Dental Federation: clinical criteria for the evaluation of direct and indirect restorations. Update and clinical examples. J Adhes Dent 2010;12:259–72.

Criteria for grading or classifying the type and severity of the failures are inadequate

There is the additional problem of reaching a common interpretation among investigators on the definition of failure

A simple classification system applicable to all fixed prosthodontic failures

John Joy Manappallil. Classification system for conventional crown and fixed partial denture failures. J Prosthet Dent 2008;99:293-298

Biological complications consisted of caries, loss of pulp vitality, abutment tooth fracture and

progression of periodontal disease.

Technical complications consisted of framework fracture, fracture or chipping of the veneering ceramic, marginal gap/discoloration, and loss of retention.

Sailer I, Pjetursson BE, Zwahlen M, Hammerle CH. A systematic review of the survival and complication rates of all-ceramic and metal–ceramic reconstructions after an observation period of at least 3 years. Part II: fixed dental prostheses. Clin Oral Implants Res 2007;18(Suppl. 3): 86–96.

The lowest incidence of clinical complications was associated with all-ceramic crowns (8%).

Posts and cores (10%) and conventional single crowns (11%) had comparable clinical complications incidences.

Resin-bonded prostheses (26%) and conventional fixed partial dentures (27%) were found to have comparable clinical complications incidences.

When fixed partial denture studies were reviewed, the 3 most commonly reported complications were caries (18% of abutments), need for endodontic treatment (11% of abutments), and loss of retention (7% of prostheses).

The 3 most common complications associated with resin-bonded prostheses were prosthesis

debonding (21%), tooth discoloration (18%), and caries (7%).

less than 15% of fixed partial dentures were removed or in need of replacement at 10 years

nearly one third were removed or in need of replacement at 15 years

less than 5% of abutments were removed at 10 years

Mark S. Scurria, James D. Bader, and Daniel A. Shugars. Meta-analysis of fixed partial denture survival: Prostheses and abutments:J Prosthet Dent 1998;79:459-64.

Biological failures : Caries:

• One of the most common biologic failures • Detection:

Visual inspection (Discoloration around margins)

Probing margins of restorations with a sharp explorer

Radiographs for interproximal caries

Causes:Defective margins (supragingival

preferred over subgingival) Loose retainers that allow gross

leakage to occur Incomplete removal of caries prior

to restoration Poor design leading to food

accumulation Change in the diet of patient

Management: If carious lesion is small --

conservative operative procedures , tooth preparation can be extended to eliminate the caries

An extensive lesion may require endodontic treatment. A grossly destroyed teeth by caries that cannot be restored must be extracted.

Pulp Degeneration:Clinical features: - Postinsertion

pulpal sensitivity in the abutment teeth that does not subside with time; intense pain or periapical abnormality that are detected radiographically.

Causes:- Excess heat generation during

preparation Excess tooth reduction Pin point exposure which may go

unnoticed Occlusal trauma

Prevention:

Use of varnish or dentin bonding agent form an effective barrier and prevents underlying pulp from toxic effects of cement and core materials.

Management: Endodontic intervention

Procedure:

Access preparation:A hole is drilled in the prosthesis

through which the biomechanical preparation (BMP) is completed. The access cavity is restored 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.

Periodontal breakdowns:

Clinical Features: - Gingival recession, furcation, pocket formation, mobility of abutment.

Cause:Prosthesis that hinders good oral

hygiene: Poor marginal adaptation Overcontouring of axial surfaces Large connectors that restrict

cervical embrasures Pontics that contact too large an

area on the edentulous ridge Prosthesis with rough surfaces

which promote plaque accumulation

Traumatic occlusion Insufficient number of abutment selected

Management: If less severe scaling and proper

plaque control Increased severity – surgical

intervention (flap, graft)

Correct occlusion Poor prognosis of abutment

teeth -- crown or bridge and the tooth may have to be removed

Occlusal Problems:Clinical Features:

Large wear facets, mobility, tender on percussion, perforation, cusp fracture, tenderness of the masticatory muscles

Radiographically-widened periodontal ligament

Interfering centric and eccentric occlusal contacts can cause

• Excessive tooth mobility • Irreversible pulpal damage Management:

Occlusal adjustmenta combination of excessive

mobility and reduced bone support --extraction of abutment teeth (traumatic occlusion on teeth previously weakened by periodontal disease or long term presence of occlusal interferences )

Irreversible pulpal damage requires endodontic treatment

In patients with bruxism -- night guards or occlusal splints

MECHANICAL FAILURES:

Loss or retentions:

leverage and unequal occlusal loads on different parts of the bridge

Improper cementation procedures

Saliva and plaque and pumping action of loose retainer are responsible for caries leading to rapid destruction of abutment teeth

Clinical Features:1. Patients awareness of looseness or sensitivity to temperature or sweets. 2. A recurring bad taste or odour

Detection:-

Awareness of movement developing in the bridge.

Clinical examination: unseat existing

prosthesis by lifting the retainers up and down (occlusocervically) while they are held between the fingers and a curved explorer placed under the connector

The occlusal motion causes fluids to be drawn under the casting and when it is reseated with a cervical force the fluid is expressed, producing bubbles as the air

and liquid are simultaneously displaced.

Management:

Removal of the prosthesis & evaluation of the abutment:

Restoration can be dislodged without damage and no caries –Recement

Loss of adequate retention, preparation modified to improve the retention and resistance form (grooves, boxes etc.)

Include additional abutment to increase overall retention

Change the design in some other way (i.e. use of full coverage instead of partial coverage)

Span length is excessive or occlusal forces heavy --- a removable partial denture

CONNECTOR FAILURE :Between an abutment

retainer and a pontic or between two pontics

To avoid breakdown of the solder joint:i) Adequate width and depth

to resist occlusal stress

ii) A sufficient bulk of materialCause: Internal porosity is the cast /

soldered connectors Failure to bond to surface of

metalJoint not be sufficiently large

to resist occlusal forcesImproper flow of metal due

to decreased width between joining parts. Minimum width for solder to flow properly is 0.25mm.

Pontics in a cantilevered relationship with the retainers -- excessive forces on the abutment tooth

Management: Prosthesis should be removed and remade as soon as possible

An inlay like dovetailed preparation can be developed in the metal to span the fracture site and a casting can be cemented to stabilize the prosthesis

Pontics can be removed by cutting through the intact connectors and a temporary

removable partial denture can then be inserted to maintain the existing space and satisfy esthetic requirements.

Occlusal Wear / Perforation:

Heavy chewing forces, clenching or bruxism

Clinical Features: Attrition of opposing teeth, polished

facets on the retainers/ pontics, gingival recession or inflammation

Causes:Faulty preparation/ inadequate occlusal clearanceEven with normal attrition, occlusal surfaces of posterior teeth wear down substantially over a period of time

There perforations allow leakage and caries to occur which leads to prosthesis failure.

Management: Perforation is detected early ---

amalgam restoration, composite resin

Metal surrounding perforation is extremely thin --- new prosthesis

Wear of ceramic cause dramatic wear of the opposing natural teeth. Occlusal wear anticipated -- metal over occluding surfaces (minimize wear and maintain the integrity of opposing teeth)

TOOTH FRACTURE:Coronal fractures:

Caries of abutment teeth

Excessive tooth preparation -- leaving insufficient tooth structure to resist occlusal forces

Use of restorative material which was not retained in sound dentin with pins

Presence of interfering centric of eccentric occlusal contacts

Heavy occlusal forces Attempting to forcefully seat

on improperly fitting prosthesis / incorrect unseating of a cemented bridge

Around inlays and partial veneer crowns, as a result of increasing brittleness, of

tooth structure with age

Management: Defect is small, restored with amalgam, or

resin Questionable integrity of the remaining

tooth structure or restoration-- fabricate a new prosthesis to encompasses the fractured area

Large coronal fracture around partial coverage retainers-- full coverage restorations

Exposure of pulp -- endodontic treatment

Abutment tooth fracture under full coverage restoration usually occur horizontally at the level of finish line

Radicular fractures:

Causes: Most often due to trauma

During endodontic treatment

Forceful seating of postAttempts to fully seat an

improperly fitting post

Root fracture well below the alveolar bone -- extraction, new prosthesis

Fracture terminates at or just below the alveolar bone --periodontal surgery, expose the fracture site encompassed by new prosthesis

ACRYLIC VENEER WEAR OR LOSS:Abrasion can result in loss of

severe amounts of acrylic on

acrylic veneer crowns and pontics.

Cause: • Functional loadings or abrasive foods and habits. • Tooth brush abrasion

Repair:Replacing lost contours with

acrylic resin/ composite resins Composites : More resistant to wear and

Maintain function and appearance longer than acrylic resin repairs

Porcelain Fracture:Porcelain fractures occur with both

metal ceramic and all ceramic crown restorations.

The majority of PFM fracture can be attributed to improper design characteristics of the metal framework or to problem related to occlusion.

All ceramic restorations commonly fail because of deficiencies in tooth preparation or presence of heavy occlusal forces.

Prevalence of ceramic fractures ranged between 5 to 10% over 10 years of use. The reasons for such failures are frequently repeated stresses and strains during chewing function or trauma

M. O¨ ZCAN. Fracture reasons in ceramic-fused-to-metal restorations. Journal of Oral Rehabilitation 2003 30; 265–269

Metal ceramic porcelain failures:

Sharp angles or extremely rough and irregular areas over the veneering

area serve as points of stress concentration that cause crack propagation

and ceramic fracture.

An overly thin metal castings does not adequately support porcelain --- flexure and porcelain fracture

Centric occlusal contact on, or immediately next to, the metal ceramic junction

Occlusions: • Presence of heavy occlusal

forces or parafunctional habits • Centric or eccentric

occlusal interferences

Metal handling procedures: Metal contamination due to

improper handling during casting, finishing or application of the porcelain

Excessive oxide formation on the alloy surface

Metal and Porcelain Incompatibility

The occlusal forces attempt to rotate the restoration. A round preparation form that does not provide adequate resistance to rotational forces can cause vertical fracture

Facial cervical fracture:

a semi lunar form occurs with a short preparation

Short preparation -- forces applied at the incisal edge tip the restoration facially -- cervical porcelain fracture The incisocervical length of the

preparation should be two thirds to three quarters that of the final restoration

Lingual fractures:Semilunar lingual fractures are observed when the occlusion is located cervically to the cingulum of the preparation, where forces on the porcelain are more shear in nature and not well resisted

•Inadequate lingual tooth reduction in which less than 1 mm of porcelain is present

• Heavy occlusal forces

Twenty to 30% reduction in metal–ceramic strength was found in a moist environment

(Sherill & O’Brein, 1974)Silicate bonds in the glassy ceramic

matrix are susceptible to hydrolysis by environmental moisture in the presence of mechanical stress

(Michalske and Freiman,1982)

The most frequent reasons for ceramic failures are related to the cracks within the ceramic.

As the crack propagates through the material, the stress concentration is maintained at the crack tip until the crack moves completely through the material

(Lamon & Evans, 1983).

Technical mistakes:

occasional presence of pores inside the ceramic could account for their weakness and eventual fracture at that site (Oram & Cruickshank-Boyd, 1984)

Faulty design of the metal substructure, incompatible thermal coefficients of expansion between the metal substructure and ceramic, excessive porcelain thickness with inadequate metal support, technical flaws in the porcelain application, occlusal forces or trauma were also included as the failure reasons

(Diaz-Arnold, Schneider & Aquilino, 1989).

Avoidance of acute line angled preparations was advised as they enhance the formation of microcracks within the porcelain during the firing procedures

(Burke, 1996)

It was reported that facings may crack, be fractured or damaged as a result of trauma, parafunctional occlusion or inadequate retention between the veneer and the metal

(Farah & Craig, 1975). Repair Various techniques for repair-

classified into two types: Direct method Repair material: Composite

resin

Lack of longevity is the main drawback because true chemical bonding does not

occur between the current resins and either metal or porcelain, pinholes or groves must be made for mechanical interlocking.

Indirect method Repair material: • Porcelain veneer,• Casting with a fused porcelain

veneer, and• ‘‘Overlay’’ metal-ceramic

crown.

Porcelain Repair (Porcelain fused to metal crown ) With Composite (for optimal results: isolate with rubber

dam) :

A. Etch porcelain/metal surface with 4% hydrofluoric acid for 4 minutes. B. Rinse and dry thoroughly. C. Apply one coat of Porcelain Primer (Silane) to exposed porcelain. D. Light cure for 10 seconds. E. Mix equal amounts of dual cure Opaquer Base & Catalyst. F. Apply thin layer on exposed metal surface to mask out metal shine-through. G. Light cure for 10 seconds. H. Use the composite of choice and light cure in small

increments I. Proceed with finishing and polishing.

A more permanent repair is possible when adequate metal framework thickness is available.

This techniques works best with facially veneered restorations.

Cementation Failure:Causes:

inadequate mechanical retention (limited strength of chemical adhesion, and cohesive strength of cement)

Poor cementation technique:Wrong choice of materialFailure to observe the

manufacturers instructions, Use of old or contaminated

stock, Inadequate P/L ratioInsertion of prosthesis when

cement has set Inadequate isolation

inadequate venting when full crowns are being employed

Design Failure:

Abutment preparation design:

Factors affecting dislodgement:

Taper of preparation: Increased taper reduces ability

of restoration to resist occlusally directed forces and also lessens its ability to interfere with arc of rotation as tipping forces act to unseat the restoration

Taper ≥ 30° failure through loss of retention becomes common Ideal taper for good retention is 7° It is not possible to achieve this taper

clinically without producing some undercuts/ damaging the adjacent teeth. Average taper that have been shown to be clinically successful in a large number of cases is approx.10-20°

Length of Preparation:

Minimum cervico-incisal height -- allows the tooth structure to interfere with arc of rotation as tipping forces attempts to cause rotation around a fulcrum located at the finish line on the opposite side of the tooth

Shorter clinical crowns: surgical crown

lengthening margin subgingivally prepare tooth with less

taper/ parallel walls retention achieved by

pins/ grooves

Circumferential

Irregularities:Circumference of teeth is usually

irregular in form and when tooth is uniformly reduced an irregular shape is formed which enhances ability of restoration to resist both tipping and twisting forces

When tooth encountered is round/ short/ over tapered intentionally formed irregularities such as boxes, grooves may be used to produce areas that interfere with dislodgement of restoration

Occlusal irregularities:

Aids in resistance to dislodging forces

Flat reduction provides little interference and unnecessarily reduces the length of preparation

Irregular reduction according to occlusal plane produces an corrugated sheet effect which enhances the rigidity of the retainer than one plane reduction

Finish line requirements:

Supragingival margins are more acceptable -- proper oral hygiene maintenance

Reduces pulpal sensitivity as they are usually in enamel

Margins should be smooth and even

Rough or irregular margins reduces adaptation and increase plaque formation and gingival inflammation

Structural Durability: Occlusal Reduction:

Minimum of 1.5mm for functional cusps and 1.0 mm for nonfunctional cusps is needed

Inadequate reduction leads to perforation and fracture of metal.

One plane reduction may reduce the incisocervical length and jeopardize the pulp.

Rigidity of metal is increased by following the contours of the crown

Inadequate bridge design:

Underprescribed / Overprescribed bridges: Underprescribed Bridges :

These include designs that are unstable or have few abutment teeth e.g. cantilever bridge carrying pontics that cover too long a span or abutment teeth with too little support

Another under design fault is too conservative in selecting retainer e.g. Class II inlays for fixed bridges

Little can be done other than removing and fabricating new prosthesis

Overprescribed bridges : More abutment teeth than are

necessary, e.g. 1st and 2nd premolar and 2nd molar included to replace 1st molar

Large bridge unit fails –it is possible to section the bridge and remove the failed unit, the failed unit is remade as an individual restoration

Retainers may be overprescribed with complete crowns being used where partial crowns or intracoronal retainers would have been adequate

Marginal Deficiencies: Positive ledge (overhang):

Excess of crown material protruding beyond the margin of preparation

More common with porcelain

Negative ledges:Deficiency of crown material that

leaves the margin of the preparation exposed but with no major gaps between the crown and the tooth

common fault with metal margins Often arises because inadequate

record of margin in the impression, over trimming of die resulting in under extension of the retainer

Supragingival margin or just at the gingival margin, possible to adjust the tooth surface of the crown

Subgingival margin it may still be possible to adjust the ledge with pointed stone or bur, although this may cause gingival damage

Sometimes it is necessary to remove the bridge and adjust

the tooth surface with/ without surgically raising the flap

ESTHETICS FAILURES:Classification of Esthetic Errors:

(Richard E. Lombardi; 1974)

I. Inharmonious dento-facial ratio

1. Shade disharmony2. Compositional

incompatibility Static prosthesis in dynamic

mouth Inharmonious strength or

weakness ofdental composition compared to

background features.

a. Weak mouth with strong face.

b. Strong mouth with weak face.

II. Intrinsic dental disharmony

1. Space allocation errors Inadequate vertical space

allocation Excessive vertical space

allocation Excessive horizontal space

allocation2. Structural line errors

Elevated occlusal plane Occlusal plane drops down

posteriorly Asymmetrical occlusal plane

3. Unnatural lines Reverse smiling line Unnatural axial inclination Cusp less posterior teeth Gradation errors Age-sex personality

disharmony4. Single-line errors

Vertical deviation Horizontal deviation Line conflict

5. Imbalance Midline error Imbalance of directions Artifact error Diastema error

ESTHETICS FAILURES:Ceramic restorations more often fail esthetically than mechanically or biologically.

Poor color match is the frequent reason for most of the remakes of the restorations

Causes: For unacceptable color match. 1) Inability to match the patients natural teeth with available porcelain colors 2) Inadequate shade selection

3) Metamerism 4) Insufficient tooth reduction 5) Failure to properly apply and fire the porcelain

6. Incorrect form or a framework design that displays metal

7. As changes in the natural tooth over the years

8. Partial veneer resonations can be esthetically unacceptable because of over extension of the finish line facially. This displays excessive amount of metal

9. When thin incisors are prepared, the metallic color of the partial coverage casting may be visible through the remaining tooth structure (grayness)

10. The marginal fit or cervical form of a prosthesis can promote plaque accumulation, causing gingival inflammation, which produces an unnatural

soft tissue color or form that is esthetically unacceptable.

CONCLUSION:

The first consideration when confronted with any failure or repair situation is to ascertain the suspected cause. Sometimes this is easy and obvious. If there is a cause that is correctable it should be taken care of first. Care should be taken not to become involved in repairs that should have been

remakes. Repairs are usually second best to the original in one or more ways.

Most failures are unique and present varying challenges to the dentist. Great satisfaction can be achieved in meeting a situation and solving it in an effective and economical manner.

References:

Bernard G N Smith, Leslie C Howe. Planning and making

crowns and bridges.  Fourth Edition, Informa Healthcare,2007

Sailer I, Pjetursson BE, Zwahlen M, Hammerle CH. A systematic review of the survival and complication rates of all-ceramic and metal–ceramic reconstructions after an observation

period of at least 3 years. Part II: fixed

dental prostheses. Clin Oral Implants Res 2007;18(Suppl. 3): 86–96.

R. Naè Paè Nkangas, M. A. M. Salonen-kemppi & A. M. Raustia. Longevity of fixed metal ceramic bridge prostheses: a clinical follow-up

study. Journal of Oral Rehabilitation 2002 29; 140±145

Merriam Webster’s Collegiate Dictionary. 10th ed. Springfield, MA: Merriam-Webster; 1993. p. 236.

M. O¨ ZCAN. Fracture reasons in ceramic-fused-to-metal restorations. Journal of

Oral Rehabilitation 2003 30; 265–269

Mark S. Scurria, James D. Bader, and Daniel A. Shugars. Meta-analysis of fixed partial denture survival: Prostheses and abutments:J Prosthet Dent 1998;79:459-64.

John Joy Manappallil. Classification system for conventional crown and fixed partial denture failures. J Prosthet Dent 2008;99:293-298

Kenneth J. Anusavice. Standardizing failure, success, and survival decisions in clinical studies of ceramic and metal–

ceramic fixed dental prostheses. Dental Materials 28(2012) 102-111

Chadwick B, Treasure E, Dummer P, et al. Challenges with studies investigating longevity of dental restorations – a critique of a systematic review. J Dent 2001;29:155–61

Hickel R, Peschke A, Tyas M, et al. FDI World Dental Federation: clinical criteria for the evaluation of direct and indirect restorations.

Update and clinical examples. J Adhes Dent 2010;12:259–72.

Heintze SD, Rousson V. Survival of zirconia- and metal-supported fixed dental prostheses: a systematic review. Int J Prosthodont 2010;23:493–502.

Charles J. Goodacre. Clinical complications in fixed prosthodontics. J Prosthet Dent 2003;90:31-41.

Sudhir Pawar. Failures of crown and fixed partial dentures -Aclinical survey. Int. Journal of Contemporary Dentistry. JANUARY, 2011, 2(1)

Thank you…..