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Fixed partial dentures

Combined electrosurgery and gingival retractionS. Henry Lampert, D.D.S.*Essex Junction, Vt.

E astic impression materials, particularly the reversible hydrocolloids, afford anaccurate means of duplicating the most discreet finishing line of a crown preparationor the detail of an onlay preparation. However, duplication of the finishing line isdependent upon proper gingival retraction.

A method of gingival retraction is described which allows ample working time,ease of operation, and the making of excellent impressions in a field free fromcapillary seepage. The technique combines the use of a retraction cord with anelectrosurgical procedure.ELECTROSURGICAL REDUCTION OF GINGIVAL TISSUES

The Hyfrecatort is used for electrosurgery (Fig. 1). This instrument producesa current for fulguration and desiccation of the tissue. The depth of reduction iseasily controlled. Fulguration occurs when the spark jumps across an air space ontothe tissue. Desiccation occurs when the electrode contacts or is inserted into thetissues.$ The electrode points are extremely fine and are covered with spaghettitubing to reduce the possibility of spark jump to an adjacent tooth (Fig. 2). Thespark will not jump to a dry tooth. Should the spark contact a metallic filling or afixed partial denture, there will be no pulpal damage as a short circuit results. Theenergy is dissipated throughout the fixed partial denture.

The electrosurgical procedure is dependent upon good preoperative evaluationof the oral cavity (Fig. 3). In a crown preparation, the finishing line must be con-fined to the free gingival margin, or sulcus (Fig. 4). In a healthy periodontium, thedepth of the sulcus will range from 1 to 2 mm. Any depth beyond this indicatespocket formation, and requires periodontal therapy.

Before using the Hyfrecator, the depth of the gingival sulcus should be deter-*Assistant Professor of Dental Materials, Department of Dental Hygiene, School of

Allied Health Sciences, University of Vermont, Burlington, Vt.i-The Birtcher Corp., Los Angeles, Calif.$Personal communication: The Birtcher Corp., Los Angeles, Calif.

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Combined electrosurgery and gingival retraction 165

1. A special instrument is used in the electrodesiccation procedure.

Fig. 2. The electrode points allow good control of removal of gingival tissue.

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166 Lampert J. Pros. Dent.February. 1970

Fig. 7. Tf le oral conditions prior to reconstruction.

Fig. 4. The teeth are prepared prior to retracting the gingival tissues.

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Combined electrosurgery and gingival retraction 167

Fig. 5. The electrodesiccation has been completed.

Fig. 6. The retraction cord is placed in the gingival sulcus.

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168 Lampert

Fig. 7. The tissue has been retracted and is ready for the impression to be made.

mined by radiographic and clinical examination. These factors determine the degreeof electrosurgery necessary. Injudicious use of the Hyfrecator can result in tissuedamage. The prime concern is to avoid bone contact with overzealous instrumenta-tion,ELECTRODESICCATION

Anesthesia is provided in the usual manner for the operative area. Palatalanesthesia is necessary in the maxillae and buccal infiltration anesthesia is neededto supplement a mandibular block.

The electrode point is placed just into contact with the tissue. The ideal dialsetting is between 60 and 75. This range gives the optimum control of penetration.

The tissue surrounding the tooth is reduced to the level of the finishing line.Care should be taken to reduce the tissue only to the shoulder, not to the bevel, onanterior restorations. Thus, the gold collar of the crown will remain below thegingival margin. The amount o f desiccation is minimal and the procedure is rapid.This firs t step eliminates the tissue forming the superior portion of the free marginalgingiva (Fig. 5). The odor of burning tissue is removed by the assistant holdingthe suction at the lips. There is a complete absence of hemorrhage.

The friable desiccated tissue is removed interproximally by sliding folded gauzelabiolingually. Friable tissue on the labial, buccal, or lingual surface is removed byrubbing with dry cotton pellets* impregnated with epinephrine by the manufacturer.TRIAL PACKING THE SULCUS

The mucosa, having been denuded of the surface epithelium, is prepared forretraction. The retraction cord is impregnated with racemic epinephrine hydrochlo-ride.? A hemostatic liquid is not required as hemorrhage is eliminated with the

*Racellets, Pascal Company, Inc., Seattle, Wash.tSurgident, Ltd., Los Angeles, Calif.

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Combined electrosurgery and gingival retraction 169

Fig. 8. Finishing lines are accurately reproduced on the cast.

Fig. 9. The trimmed dies are ready for waxing.

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170 Lampert J. Pros. Dent.February, 1970

Fig. 10. The crowns are in place 3 weeks following electrosurgery. Note the condition of themarginal gingiva.

Hyfrecator. A hoe hatchet, Starlite No. 8A* is used to insert the cord.The trial packing of the sulcus serves a dual purpose (Fig. 6). First, it causesa total relaxation of the tissue making subsequent retraction easier. Second, it

affords a check on the exposure of the finishing line.IMPRESSION TECHNIQUE

A dual impression technique is used that includes a full arch as well as sectionalimpressions. The occlusal surfaces of the restorations are waxed on the full cast whilethe margins are completed on the sectional casts. The full cast is also desirable inquadrant reconstruction since it includes the unprepared teeth in the same dentalarch.The retraction cord is used only in making the sectional impressions. The cordcan be used in the full impression, retracting the same teeth as in the sectionalimpression, if duplicate dies are desired. The accuracy with the reversible hydro-colloid impression material allows the dies to be completely interchangeable.

The tissues become more flaccid and retractable with each packing. For thisreason, it is best to make the sectional impression last, because by the third packingthe tissue is extremely relaxed and pliable. The cord is inserted while the reversiblehydrocolloid impression material is tempering. When the cord is removed, the opensulcus permits free flow of the impression material (Figs. 7 to 9) .PATIENT EDUCATION

Following the electrosurgery and gingival retraction, patients are made awarethat they may temporarily experience sensitivity to thermal change. They are

*Star Dental Mfg. Co., Inc., Philadelphia, Pa.

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VoluIm 23Number 2 Combined electrosurgery and gingiual retraction 171

Fig. 11. Eight weeks following the electrodesiccation procedure, the tissue texture is healthy.

Fig. 12. The completed restorations are in place in the mouth.

instructed to coat the tissues with Orabase Emollient* for protection and to reducediscomfort. Instructions are given not to brush the treated tissues for 4 days. Oralhygiene is maintained by gently cleansing the tissues with a soft wash cloth andwarm water mouthwashes, but not saline. High pressure water sprays are to be

*E. R. Squibb & Sons, N. Y.

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172 Lampert J. Pros. Dent.February, 1970avoided for 3 weeks. After 4 days, tooth brushing is reinstituted with a soft tooth-brush for 2 weeks. Within 24 hours, granulation tissue is seen forming on themarginal tissues. In 2 weeks the tissues appear normal to visual examination, and in4 weeks the original tissue contour has returned (Fig. 10).DISCUSSION

A retraction cord placed in a sulcus to expose the finishing line is successful inindividual preparations. In multiple preparations, the problem is that of pushing theinterdental papilla from one tooth to the other. Working rapidly is always necessaryfor the dentist literally races to make impressions before the retracted tissues returnto normal.

Electrosurgery without retraction does not always clearly define the margin ofthe preparation since there is no demarcation of tooth from soft tissue. The elasticimpression materials eliminate the need for copper bands and the possibility ofsevering the epithelial attachment. Fitting of copings and plaster impressions areeliminated which reduces appointment time. This method of retraction combinedwith electrosurgery permits the dentist to fully utilize the elastic impression materials.The electrodesiccation is not radical since the tissue is not reduced beyond thefinishing line of the preparation. Tissue regeneration is rapid. The dentist has ampletime to make his impression, and there is minimal postoperative discomfort to thepatient (Figs. 11 and 12).SUMMARYA combination of electrosurgery of marginal gingival tissues and retraction byplacing the cord in the gingival sulcus allows the making of accurate impressionsof multiple prepared teeth. The technique of this method is described and theadvantages explained.

48 MAIN ST.ESSEX JUNCTION, VT. 05452