A R T IC L E S
How to maintain quality in economy dentures John H. W orm ley, DDS, MS
Shortcuts in the construction of complete dentures are necessary to minimize cost and time required. A system of denture delivery consisting of three short appointments is described. Emphasis is on the use of sound prosthodontic principles that result in a quality service to the edentulous patient.
D u r i n g the US m ilitary involve m ent in Vietnam, two factors made the use of expedient, professionally sound prosthodontic procedures im perative. First, the num erous trainees being readied for combat needed prostheses to satisfy functional and esthetic requirem ents. Second, many prostheses w orn by soldiers in the combat area needed servicing or re placem ent; m any were lost during missions. In training or combat, loss of time for dental care could seri ously affect the efficiency of a m ili tary team. Many com plete dentures were fab ricated during these years. They had to be done quickly to prevent loss of the patient’s tim e from duty. They also had to be professionally accept able to satisfy the patient and to m inim ize loss of time for adjust m ents and remaking. For these rea sons, the m ilitary services needed trained, experienced prosthodontists both at the training centers and in the combat area. Today, the combat zone is m uch
closer and affects the majority of pri vate practitioners. To com pete in the field of economy dentures, time spent on procedures m ust be m inim ized to reduce cost of profes sional time. In this article, a method of expedit ing the construction of dentures w hile m aintaining professionally ac ceptable quality is presented. The individual dentist m ust decide w hat procedures and materials w ill work best for him. In addition, some pa tien t’s requirem ents, regardless of economic status, cannot be satisfied by this sim plified approach. Once it has been ascertained that the patient is ready for dentures, the service can be divided into three ap pointm ents: the im pressions, the recording of jaw relations, and the delivery of the com pleted dentures.
Impressions The majority of edentulous ridges can be recorded adequately w ith a single alginate im pression m ade in
stock trays. Many edentulous algi nate im pression trays are currently available. The use of an alginate adhesive allows the use of trays that are designed for m odeling plastic. A tray that approxim ates the arch as closely as possible is selected. This tray often m ust be m odified w ith waxes or other plastic materials to provide adequate extension and to allow space for a uniform thickness of the im pression material (Fig 1). Denture bases from alginate im pressions are extremely stable. How ever, a com m on pitfall resulting from the use of a stock tray is overexten sion of the lingual m andibular flanges. The experienced operator can make adjustm ents for this to the finished m andibular denture. After loading the tray, extra algi nate is placed in the palate, the buc cal vestibule, and other crucial re gions to prevent voids. It can be in jected or placed m anually. The tim ing recom m ended by the m anufac turer of the alginate is used. To en sure proper posterior extension, the vibrating line and the palatal pterygomaxillary notches are delineated in the m outh by an indelible marker and read in the resulting im pression (Fig 2)• Both m axillary and m andibular im pressions can be made in 15 m in utes. If a large selection of teeth is not stocked, the proper m olds and shade are selected and ordered to be on hand at the second appointm ent. JADA, V ol. 98, February 1979 ■ 215
ARTICLES
Fig 1 • Edentulous impression trays modified for close adaptation.
With the aid of a face-bow, a simple bizygomatic measurement is made in millimeters and divided by 16 to give the width of the maxillary central incisor. The face form is also used to determine the desired mold. At this time, the patient is given printed instructions on the wearing of dentures to review before subsequent appointments. Alginate impressions cannot be boxed without danger of distortion through dehydration or bending of the borders. A two-stage pouring technique is used . The desired peripheral roll is outlined on the alginate with indelible pencil to give the technician a guide to the region that will be covered with the first pour of artificial stone (Fig 3, 4). After the initial set of the first pour, a base is added using a mix of the same waterto-powder ratio to prevent differences in expansion and separation of the base when the cast is subjected to other laboratory procedures.
Jaw relations The two most important considerations in the fabrication of dentures are accurate jaw relations and esthetics. The second appointment encompasses both of these aspects. Accurate record bases are essential. This implies the use of an accurate cast. An attempt to use a secondary impression as a record base for recording jaw relations is often disastrous. To have the tray thick enough to be rigid, it usually has to encroach on the space needed for the occlusion rims and recording medium. The ad216 • JADA, Vol. 98, February 1979
Fig 2 • Posterior limit marked in patient's mouth.
Fig 3 • Maxillary impression witb indelible outline to aid in pouring cast.
dition of the final impression material makes them even bulkier. Also, there is a possibility that the heat used in adding or adjusting the occlusion rims will distort the final impressions. The most accurate record base, other than one that is processed on the master cast, is formed by using the salt-and-pepper or sprinkle method with cold-curing acrylic resin. Severe undercuts are blocked out and the casts are coated with a liquid foil substitute. The maxillary base should encompass the entire periphery. The mandibular base can be designed short of lingual undercuts . No wax rim is added to the base for a single denture. For complete maxillary and mandibular dentures, a wax rim is added to the maxillary base only. The maxillary posterior extension is rechecked and the posterior palatal seal area is determined during the second appointment. The distal limit
Fig 4 • Mandibular impression showing proposed extensions of border.
Fig 5 • Record base indelibly marked to check accuracy of denture base extension.
of the record base is marked with indelible pencil and placed in the mouth. This line will transfer to the palate, and it can be easily determined whether the base extension coincides with the vibrating line and pterygomaxillary notches (Fig 5). The resilient seal area is palpated, and the cast is carved accordingly. If the record base is accurate, the carved posterior palatal seal area can be added to the base with lowfusing greenstick modeling plastic, which is then seated on the moistened cast. The seal is then tested for effectiveness in the mouth.
The single maxillary denture The next procedure is to obtain the occluding vertical dimension. A cone of soft wax is placed in the midline of the record base anterior to the incisive papilla (Fig 6) . Based on Silverman's 1 determination that the
ARTICLES
Fig 10 • Casts temporarily mounted in plasterless articulator.
Fig 6 • Record base with soft wax cone before phonetic tests.
Fig 7 • Notched wax cone (arrow) showing closest speaking space.
Fig 8 • Record base with initial registration of centric relation.
Fig 9 • Refined and trimmed centric relation registration.
closest speaking space is near the occluding vertical dimension, the patient is instructed to repeat words containing sibilant sounds. These sounds are made at the position of closest speaking space. The soft wax cone becomes indented by the mandibular incisors, indicating this position (Fig 7). Swallowing is considered to be done at the level of occluding vertical dimension. The wax cone may or may not be further indented when the patient swallows. The wax cone is cut off approximately 1 mm beyond the notch generated by the patient. A thin layer of sticky wax is added ·to the base in the premolar-molar regions. A rim of softened green modeling plastic or no. 10 x wax* is then attached to these areas . This rim should be triangular in cross section with the apex toward the occlusal surface. A hot spatula is used to seal it. The softened occlusal rim is tempered in a water bath, and the dentist begins to record centric relation. The first closure should stop approximately 2 mm short of contact with the wax cone described previously (Fig 8) . The modeling plastic or wax is chilled thoroughly and trimmed with a knife so that only an index of the tips of the cusp remain (Fig 9). The surface of the record is resoftened with an alcohol torch, tempered in a water bath, and reinserted. The patient is then directed to tap lightly. This tapping continues until
the mandibular teeth are approximately 0.5 mm short of contact with the wax cone. The record is chilled and rechecked . Centric relation is verified by ensuring that the patient can repeatedly close into the cusp indices. The profile of the patient is observed to further check occluding vertical dimension. The patient should be asked whether the denture feels acceptable. Finally, the patient is asked to tap lightly on the hard record and indicate which side contacts first; uniformity of contact is desired. If not uniform, the surface of the entire record is resoftened, and the tapping and checking is repeated until uniformity is achieved. Precautions should be taken to avoid decreasing the occluding vertical dimension. Modeling plastic is an ideal recording material. It can be made uniformly soft. When chilled, it is hard and resists distortion during subsequent procedures. It can easily be resoftened to make corrections. Care should be taken so that the wax record is sufficiently hard before proceeding to the next step. With the aid of the record , the casts are articulated in a plasterless instrument or hand-held in occlusion while the six anterior teeth are set. This is accomplished quickly. Each pair of teeth is checked after setting in place (Fig 10). This is importanl in satisfying the esthetic needs of the
Wormley: QUALITY IN ECONOMY DENTURES • 217
ARTICLES
patient and emphasizing individual attention (Fig 11). On approval of the anterior arrangement, the case can be mounted in a rigid articulator, preferably with the aid of a· face-bow if remounting at insertion is anticipated (Fig 12).
Complete maxillary and mandibular dentures Relating the jaws is essentially the same for the completely edentulous patient. A hard wax occlusal rim is added to the maxillary record base, which is contoured and adjusted for esthetics and establishment of the occlusal plane. The soft wax cone is placed on the mandibular base, and occluding vertical dimension is established as described for the single denture. The maxillary wax rim is keyed in the posterior segments and lubricated to prevent the soft modeling plastic or lO X wax from sticking. Centric relation is established and checked as in the procedure for the single denture (Fig 13). In this instance, the keyed wax occlusal rim takes the place of the natural teeth. The anterior teeth are set to satisfy esthetics and also to determine the anterior portion of the occlusal plane to develop the monoplane occlusion 2 (Fig 14). A face-bow transfer again aids in the articulation. By using a block forll). of monoplane teeth, laboratory procedures are simplified. This appointment can be accomplished in less than 30 minutes .
Delivery of the dentures For best results , old dentures should have been removed from the patient's mouth 48 hours before this appointment so that the basal seat tissues are in their rested form, as they were at the time of the impressions. The tissue &urfaces can then be adjusted accurately using a pressure-indicating material. The patient closes firmly on cotton rolls to apply functional pressure to the bases. This applies uniform pressure without the influence of any irregularities that might exist in the occlusion. 218 • JADA, Vol. 98, February 1979
Fig 11 • Maxillary central incisors placed for proper esthetics and phonetics.
Fig. i:i • Related casts with face-bow transfer . for niounting in articulator.
Fig 13 • Complete maxillary and mandibular a;st ui centric relation. (Lines are drawn paral- · lel to ridges.) Fig 14 • Anteriorteetharrangementreadyfor face-bow and articulation.
Ideally, the dentures should be remounted. However, individual operators with considerable remounting experience can adjust mino~ occlusal discrepancies by intraoral procedures. The dentist should review the instructions with the patient and make arrangements for necessary postinsertion management. This appointment can be conducted in 15 minutes. Good occlusion and well-adapted dentine bases keep postinsertion adjustments to a minimum. Time spent perfecting these at the insertion appointment is more than repaid by avoiding the necessity of using unscheduled time for adjustments.
SUiilmary A method for constructing custom dentures using minimum time at the chair is described. Efficiency with this or any technique is gained only through experience. Although there are many ways of achieving the same
goal , the basic principles of sound prosthodontic procedures must be followed for the service to be professionally acceptable.
The opmwns and assertations expressed herein are those of the author and are not to be construed as official or as reflecting the views of the Department of the Army or the Department of Defense. lO X Wax, Mayea Industries, Inc., Philadelphia, Pa.
Dr. Wormley, a colonel, US Army Dental Corps, formerly chief in the department of removable prosthodontics , Walter Reed Army Medical Center, Washington, DC, is currently chief in the department of removable prosthodontics, USA Dental Activity, DENTAC, Fort Stewart, Ga 31313 . 1. Silverman, M.M. Occlusion in prosthodontics and in the natural dentition. Washington, Mutual Publishing Co., 1962. 2. Brudvik, J.S., and Wormley, J.H. A method of developing monoplane occlusions. J Prnsthet Dent 19(6) 573-580, 1968.