Simplified technique for the removal of a fixed partial denture

SimpWed technique for the removal of a fixed partial denture Daniel

J. Conny,

State University

D.D.S.,*

and Milton

H. Brown,

D.D.S. **

of New York at Buffalo, School of Dentistry,

1 he replacement of a fixed partial denture may be required for a number of reasons: (1) mechanical failure of the restoration, (2) carious and/or periodontal breakdown of the abutment teeth, (3) the need for more extensive restorative therapy to restore and preserve the remaining teeth, and (4) inadequate esthetics. In removing the defective restoration, every effort must be made to avoid damage to the underlying teeth and adjacent soft tissues. An excellent review of methods for removing cast gold restorations was presented by Oliva.’ The most predictable and least traumatic method involves sacrifice of the restoration. A slot is cut through the retainers, separating them into mesial and distal halves. The slot may be effectively cut using a No. 2 carbide bur with the high-speed handpiece and copious air-water spray. A rigid instrument may then be placed into the slot to pry the segments apart (Fig. 1). This permits easy removal of the restoration while minimizing damage to the supporting tissues. In the following situations, a fixed partial denture must be removed but need not be replaced with a new prosthesis: (1) a restoration which binds and resists removal at the time of try-in, (2) a provisionally cemented restoration which resists removal, (3) a restoration which is incompletely seated at the time of definitive cementation, and (4) a restoration which has one loose retainer while the other remains firmly fixed to the abutment. Under these circumstances, it is understood that the abutment teeth are sound, and the restoration is clinically acceptable. If the fixed partial denture can be removed intact, subsequent definitive cementation may be performed. Both the dentist and the

Buffalo, N.Y.

Fig. 1. Use of sturdy instrument

to pry apart sectioned

casting. patient are spared the emotional and financial trauma of destroying one restoration and making another. Removing a binding or cemented restoration requires force, which should be carefully applied in a direction parallel to, but opposite from, the path of insertion (along the path of withdrawal). This article describes a technique for removing a fixed partial denture utilizing the mechanical advantage of Class I and II lever systems (Fig. 2). This approach permits force to be applied to a restoration along the path of withdrawal in a controlled manager. Fig. 3 illustrates the application of the Class I lever system and the simple, inexpensive items needed for the technique are shown in Fig. 4.

TECHNIQUE *Assistant

Professor,

**Chairman dontics.

0022-3913/81/110505

and

Department Professor,

+ 04$00.40/06

of Fixed Department

1981

Prosthodontics. of

The

Fixed

C. V. Mosby

Prostho-

Co.

The clinical following:

steps in the technique

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include

DENTISTRY

the

505

CONNY

BROWN

F - fulcrum W - work L - load

Class 1 :

AND

Y

Fig. 4. Armamentarium: hemostat, 0.032 inch brass ligature wire, cottonwood bite stick, utility pliers, and fishtail burnisher. Fig. 2. Classification

of lever system.

Fig. 5. Wire loop formed hemostat. Fig. 3. Application of the Class I lever system for removal of anterior retainer of fixed partial denture. 1. Place a 3 inch length of 0.032 inch brass wire (Rocky Mountain Orthodontics, Denver, Colo.) under the rigid connector adjacent to the retainer to be removed. 2. Form and tighten a loop by twisting the loose ends of the wire with a hemostat (Fig. 5). 3. Position the fulcrum over a sound adjacent tooth. 4. Place the rigid lever on top of the fulcrum, with one end engaging the wire loop (Fig. 6). 5. Have the assistant secure the wire loop by grasping the twisted ends firmly with a pair of utility pliers. 6. Apply gradually increasing controlled force to and through the lever to the restoration.

506

by twisting

loose ends using

The amount of force applied is a matter of clinical judgement. Profound local anesthesia generally benefits the patient. It permits the use of sufficient force to dislodge a restoration that might otherwise be uncomfortable. A finger should be placed over the restoration to protect adjacent tissues in the event of sudden dislodgement (Fig. 7).

DISCUSSION If a lixed partial denture must be replaced, the existing restoration may have to be sacrificed. Preserving the supporting abutment teeth is the primary objective when removing the prosthesis. Damage to a critical abutment tooth may dramatically alter the treatment options. If a distal abutment tooth is damaged and subsequently lost, the patient may lose the option of replacing missing teeth with a fixed

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1981

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REMOVING

FIXED

PARTIAL

DENTURE

Fig. 6. Positioning of armamentarium to apply Class II lever force to remove full crown retainer on first molar.

Fig. 7. Successful removal age to abutment teeth.

partial denture. Advantages gained by removing a restoration intact are far outweighed by the potential liabilities such as damage to supporting teeth. Occasionally, it is reasonable to attempt to remove a fixed partial denture intact. The age and health of the patient, economic factors, time and specific clinical circumstances as outlined previously, may all indicate removal of a restoration without damaging it. In such a situation, the dentist is advised to discuss and explain the benefits and liabilities with the patient before attempting the procedure. The dentist must be aware of several factors which significantly influence the feasibility of removing a fixed partial denture intact. These factors include (1) location of the restoration, (2) the number of abutments, (3) the condition of the abutments, and (4) the type of retainers. A consideration of these factors is essential prior to initiating efforts to remove the restoration. Restorations in the posterior quadrants of the mouth usually present problems of access. It is desirable to apply any dislodging force along the path of insertion. Forces directed against the restoration which are not in harmony with the line of withdrawal may prove damaging to the supporting teeth. In the posterior quadrants, inability to properly direct dislodging forces is an indication to sacrifice the restoration and avoid damage to the abutment teeth. The presence of more than two abutments may require excessive force for removing the restoration. The greater the number of abutments, the more force will be necessary. Clinical judgement must be used to avoid irreversible damage to the supporting

teeth. One possible option might include sectioning the extensive restoration and attempting to salvage all or part of it in smaller units. The quality and quantity of sound tooth structure supporting a retainer which is to be removed are critical. The more sound tooth structure under a cast restoration, the less the risk of abutment fracture. Endodontically treated teeth and teeth rebuilt with pin-retained cores (amalgam or composite resin) are poor candidates for forced removal of a fixed partial denture. Such teeth present increased risks in terms of irreversible damage. In situations where less than maximum sound tooth structure is present under a retainer, the fixed partial denture should be sacrificed. It is wiser to replace a restoration than to render a supporting tooth nonrestorable and create additional complications. Another factor that must be considered before attempting to remove a fixed partial denture is the nature of the retainer to be removed. Full crown retainers on short teeth are reasonable risks for forced removal. A totally extracoronal full crown restoration will generate minimal potentially damaging forces on an abutment if the removal effort can be directed along the path of insertion. Sophisticated intracoronal retainers such as pin ledge and threequarter crowns may act as wedges when force is placed against them. This may result in fracture of the abutment, leaving the tooth unrelstorable. Force placed against such retainers should be avoided.

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SUMMARY A simplified method of removing a fixed denture has been described. The principle

partial of the

507

CONNI’

Class I or II lever systems is used to deliver force along the path of withdrawal. Carefully applied, this technique may permit removal of a restoration with minimal trauma to the prosthesis and supporting teeth. Where reasonable pressure fails to dislodge the restoration, it shouId be sacrificed rather than risk permanent damage to the abutment.

AND

BROWN

REFERENCE 1.

Oliva, R. A.: Review of methods for removing restorations. J Am Dent Assoc 995340, 1979.

cast gold

Reprint requests to: DR. DANIEL J. CONNY SUNY AT BUFFALO SCHOOL OF DENTISTRY BUFFALO, NY 14214

We would like to thank Miss Barbara Evans and Mr. Dennis .4tkinson of the Educational Communications Center for assistance with the illustrations.

IADR PROSTHODONTIC

ABSTRACT

A computer analysis of mandibular cinefluorographic technic

movements

using the

L. K. Yohn, D. E. Geister, and A. Koran University

of Michigan,

School

of Dentistry,

Ann

Arbor,

Mich.

The purpose of this study was to measure the anterior-posterior condylar movement in relation to the inferior-superior movement of the mandibular symphysis as a function of time. The opening and closing movements of 25 dentate subjects were investigated using the cinefluorographic technic. A frameby-frame analysis of these movements was made by digitally locating selected radiographic points. The Reprinted from the Journal 1980 (Abst No. 197)] with

508

of Dental permission

Research 159 (Special Issue A), of the author and the editor.

digitized points were entered into a computer. Statistical analysis regarding mandibular geometric movements were made over the patient data base. Through this technic head movements could be accounted for and corrections applied to the indicated mandibular movements. Results indicate that there is considerable anterior-posterior movement of the lcondyle with a range of 9.9 to 21.9 mm. The condyle demonstrated an anterior-posterior movement path which produced a straight line with very little angulation and nearly parallel to Frankfort horizontal plane.

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1981

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