DENTURES can give excellent service for many years without ARTIAL destroying either weak or strong abutment teeth. Proper engineering, which includes proper application of forces, proper position of rests, removal of lateral and protrusive interference, and proper fit are the prime factors of a good partial denture. It is wrong (a) to place a rest on the inclined planes of the lingual surfaces of cuspids and incisors, (b) to place an occlusal rest on the lingual side of a lingually inclined lower molar or bicuspid, (c) to place a rest on the buccal on the buccally inclined upper molar or bicuspid, (d) to place an abutment tooth in a viselike cast clasp where there is no posterior support, unless the tissue and bone are unusually firm, or unless other allowance has been made for the resiliency of the tissue, such as by relining the appliance, or by using a stressbreaker. A precision attachment appliance will not retain abutment teeth longer than any other type of appliance (except from the standpoint of decay). Stress breakers are not necessary, even though I have some partial dentures with stress breakers which have been in use for over fifteen years. By the same token, some clasp and precision attachment dentures have lasted longer on the same type of abutment teeth. If stress breakers are necessary, it would be in a partial denture where only one side is tissue-borne. The tissue-borne partial dentures or those in which at least one side is tissue-borne, are the appliances that have caused the most destruction in the mouth. Frankly, I am almost radical on the subject of saving teeth, and in my practice I make very few full dentures. Many weak abutment teeth, even those with the bifurcation or trifurcation above the bone, can be saved for many years of service without infection.
During the first few months, and even years, after partial dentures are placed in the mouth, there will be some change in the denture-bearing tissue as well as in the abutment teeth. This will happen to a certain degree, regardless of the jaw registrations made, the type of instrument the partial dentures are constructed on, or the type of cusps used. Therefore, it is imperative that the patient return every few months after the partial denture is placed to have the occlusal balance checked so that excessive stress on abutment teeth and any lateral or protrusive interference may be removed. The work load of weak abutment teeth should be minimized greatly. Read before the Academy of Denture Prosthetics Received for publication June 23, 1954. 206
Bilateral balanced occlusion is not necessary in partial dentures or a natural dentition, but (a) the occlusal area of contact should be very small, and it should not be more than 1 to 2 mm. in diameter on weak abutment teeth; (b) any tooth that moves when lateral or centric occlusal contacts are made will cause bone resorption around it, and this interference must be corrected; (cl every weak abutment tooth must have the occlusal stress directed through the strongest part of the tooth. On lower posterior teeth, this means that the stress should be placed upon buccal inclines; and on the upper teeth, it should be placed upon the lingual inclines. ATTACHMENTS
No partial denture attachment should fit the abutment tooth so tightly that it cuts off circulation from the tissue in the saddle areas, thereby causing resorption. Every attachment and clasp should be loose enough on the abutment tooth to allow the appliance to release itself after pressure has been applied. This is the reason I use a clasp consisting of a cast occlusal rest, a cast lingual arm, and a buccal arm extending about 2 mm. onto the buccal surface of the tooth with a 20 gauge stainless steel wire, which is attached in the plastic and which contacts the buccal surface of the tooth, to act only as a retainer. This clasp causes no distal stress on the abutment tooth. The cast buccal extension of the lingual arm prevents lateral thrust. If an all metal base is used, the wire buccal arm of the clasp is soldered to the metal base. When precision attachments are used, they are made to fit very loosely and act only as stabilizers and stops for the appliance. If necessary the bottom is cut out of the attachment, making the denture almost completely tissue-borne. On the lingual side of every attachment, a 20 gauge tension wire is used for retention. This wire is placed below the lingual bulge of the tooth and allows the appliance to release itself after pressure is applied, hut it still retains the appliance. A number of Roach or modified Roach clasps are used. Some of these are used without occlusal rests when that is indicated, as in situations where only one side is tissue-borne. Weak abutment teeth should be splinted together to add years of service. As few as three teeth have been splinted together and used to stabilize appliances satisfactorily for over fifteen years. The home care of the appliances and the abutment teeth must be stressed during the first few months of use of partial dentures. The patient must cooperate or take the blame for decay and other trouble. Practically any type of partial denture that is properly engineered and constructed can give years of good service, whether attached to good or weak abutment teeth, if it is properly checked and balanced at least every six months and provided the patient cooperates with good home care. STARKS BLDG. T2~~~~~~~~a~ 2, KY.