Carl O. Boucher

A critical analysis of mid-century impression techniques for full dentures

Abstract Impression techniques in use at the middle of the twentieth century vary not only in the plan of the technique, but with the use of the plan by each operator as well. Evaluation can be made only by an analysis of the resultant impression, area by area, in relation to the part of the mouth to which that part of the impression is adapted. The supporting structures have equal importance with the limiting structures in this analysis. The value of the procedures used will depend upon the recognition of possibilities and limitations of anatomic form and structure of the mouth, and the characteristics of the impression materials selected. Arbitrary impression techniques do not meet the requirements of an impression technique.

Responsibility of the dentist in complete dentures

Abstract The dentist is obligated to perform certain essential phases of complete denture construction. These include making a comprehensive diagnosis, making certain that the oral tissues are healthy before work is started, making the impressions, producing jaw relation records, selecting the teeth, correcting the jaw relation records, rearranging the anterior teeth for esthetic appearance, correcting the occlusion at the time of the first insertion of the dentures, and making whatever denture adjustments may be necessary. If the dental profession is to maintain its high standard of denture service, the dentist must not delegate to someone else any phase of denture construction he should complete himself.

Influence of occlusal schemes on the muscular activity of edentulous patients

Abstract An investigation utilizing different occlusal schemes on the same denture base was conducted to test the variance in muscle activity during mastication. Results indicate that the anatomic occlusion required the least activity from the closing muscles for all test foods. The reverse curve occlusal scheme required the greatest closing muscle activity during the chewing of carrots and peanuts. Thus, the form of posterior occlusion is an important factor in the amount of muscle activity during mastication.

The relining of complete dentures.

The relining of complete dentures involves solving all of the problems encountered in the construction of new dentures, except positioning individual teeth. The first and most important problem is to achieve a healthy condition of the tissues of the basal seat for the dentures. To do this, the patient must be without his dentures for at least 24 hours before the impressions are made. The dentist looks for errors in the occlusion, the occlusal vertical dimension, and for whatever other changes should be made. A posterior palatal seal is formed in modeling compound on the upper denture before any other change is made on the impression surface. The modeling compound is reheated and the denture is reseated in the mouth to perfect the form of the posterior palatal seal. After each heating, the compound is tempered and placed in the patient’s mouth; slight pressure is applied near the distal end of the denture, and the cheeks are pulled in to mold the compound around the distal ends of the buccal flanges. The width of the posterior palatal seal is reduced to about 2mm.—the width of the area between the bead on the denture and the endof the denture. Space is provided inside the denture for the new impression material by grinding about a 1.0 mm. thickness of resin from the entire palatal surface. All undercuts removed from the labial and buccal flanges. The borders are shortened 1.0 mm. to allow space for the impression material to form a new border. The labial notch is broadened and deepened so it will not interfere with the labial frenum. The lower denture is prepared for the reline impression in exactly the same way as a tray would be prepared for making a new denture. The buccal surfaces of the lingual flanges are ground to minimize the pressure against the mylohyoid ridges and between the tissues of the floor of the mouth and the buccal sides of the lingual flanges. The lingual flange between the premylohyoid eminences is shortened 1 mm. The labial flange between the buccal notches is shortened 1 mm. Shortening the flanges provides space so the impression material canform new borders. Nothing is removed from the buccal flanges, but grooves are cut on the buccal sides of the lingual flanges to facilitate removal of the retromylohyoid eminences

Method of Recording Functional Movements of Full-Denture Bases in Three Dimensions:

Since 1805, when Gariot built the first plain-line articulator, much work has been done on the problem of reproducing jaw movements on a machine. Many methods of recording mandibular movements have been devised; and many instruments have been invented in attempts to produce articulators capable of accurately reproducing those movements. These articulators are of two types: non-adjustable and adjustable. Non-adjustable articulators require only a centricrelation registration, and a proper adjustment of casts to the mechanism. The possible movements on this type are either arbitrary (Evans, Bonwill, Grittman, and Gysi Simplex) or theoretical (Monson, and Hall automatic anatomic). Adjustable articulators require multifarious registrations, the number and kind varying with the instrument. Articulators of this type are divisible into two groups: (a) two-dimensional instruments (Gysi adaptable, Hanau, Snow, and Wadsworth) and (b) three-dimensional instruments (Lentz, Hall, Stansbery, Phillips, Homer and Roberts). Registrations for adjustable articulators are taken either intra-orally or extra-orally. The principal intra-oral checkbite methods are the (a) interposed wax record of forward protrusion (Christenson), and of lateral occlusion (Waugh); (b) interposed metal bite-gages used with forward protrusion (Snow); (c) plaster checkbite (Stansbery); (d) dentographic registration (Luce); (e) carborundum biteplate method (Patterson); and (f) Gysi gothic arch tracings cut in compound bite-rims by pins in the opposing rim (Needles). The principal extra-oral methods are

Discussion of “laws of articulation”

Abstract I agree in part with both Hanaus and Trapozzanos concepts of the laws of occlusion. 1. I see three fixed factors instead of one, with the orientation of the occlusal plane and the incisal guidance angle being additions to the condylar guidance as fixed factors. 2. The angulation of certain cuspal inclines is more important than the height of the cusps per se. 3. The compensating curve is a device for increasing the effective height of the cusps without changing the forms of the individual teeth. 4. Both the cusp height and the compensating curve are means for solving the problems imposed by the Christensen phenomenon. They are the means whereby the space developed at the posterior end of the occluding surfaces which results from the downward movement of the condyles can be closed by tooth contacts. 5. The occlusal plane should be oriented according to esthetic appearance and intraoral soft tissue anatomy (the retromolar pads and tongue) instead of located according to leverage or mechanical requirements. 6. The orientation of the occlusal plane, i.e., the angle of its deviation from the horizontal, does have an effect upon the things that must be done to the angulation of the cuspal inclines, either by tipping the teeth into a compensating curve or the choice of a posterior tooth form. 7. Dr. Trapozzanos diagram can be helpful toward an understanding of the relationship of the tooth surfaces to the end guidances. In closing, I wish to thank Dr. Trapozzano for stimulating me to put these ideas on paper. I feel certain that he has stimulated the reader as well.

Flasking for easy deflasking

Abstract The top half of molds for processing dentures is made in sections in the top half of the flask. This technique speeds up the removal of processed dentures from their molds and reduces the possibility of fracturing either the denture base or the teeth.

Writing as a means for learning

Abstract Writing is a means for learning and re-examining our beliefs. It involves hard work, but it allows a dentist to share his knowledge with his colleagues and to look objectively at himself, his theories, and his techniques. Authors have several responsibilities, which must be respected, and their writing must be so clear and logical that they do not waste the time of their audience—the readers. A sentence outline will help the writer to organize what he wants to say, and the suggestions given in this article regarding writing style will help to hold the readers interest and will make writing easier.

Trends in the practice and philosophy of prosthodontics in the United States

Abstract It has been impossible to explore in depth the trends of all of the many factors involved in prosthodontics within the limited time allotted to me. However, we might summarize the situation in a few statements. 1. The quality of prosthodontic service in the United States is as good or better than any other country in the world. 2. The high quality of prosthodontic service is the result of early individual efforts and supplemented by improved dental education at all levels. 3. If the trend of taking more and more time from the teaching of prosthodontics is continued, the quality of prosthodontic service will deteriorate. 4. Vastly increased amounts of objective prosthodontic research are leading to improved techniques. 5. The use of the services of dental laboratory technicians is making it possible for dentists to care for more people. 6. The dental profession is responsible for all dental services rendered to the public, so the profession must provide adequate work authorization information to laboratory technicians. 7. The American Dental Association and the state dental associations are correct in their opposition to licensure or registration of dental laboratories. 8. The accreditation of dental laboratories by the Joint Commission on the Accreditation of Dental Laboratories is a step toward the best solution of the problem of dentist-laboratory relations. 9. The accreditation program will serve as a guide for dentists to ethical laboratories and to laboratories that are qualified to perform certain services for dentists. 10. The new Dental Laboratory Owners Forum may provide the necessary liaison between the American Dental Association and the dental laboratory industry. 11. The Federation of Prosthodontic Organizations can supply the need for a unified voice in matters concerning prosthodontics.

Implant dentures: Prosthodontic—Unfavorable

Abstract In my discussion of the unfavorable prosthodontic aspects of implant dentures, I have avoided reference to the surgical techniques and consequences which are being discussed by others. I have only touched upon what I believe to be disadvantages or deficiencies of the procedures. The most serious disadvantage is that the procedure cannot be used for those who need it most. It is not advised for aged, infirm, or unhealthy people. Soft tissue-borne dentures can be and are made for these people, and if they are carefully and precisely constructed, these dentures do provide teeth which are comfortable and usable. Judging by the implant dentures I have seen and by many illustrations in books and periodicals, insufficient attention has been paid to jaw relations and occlusion. These are phases of construction techniques that could be corrected easily, however, if more attention was paid to them. The illustrations I have seen of upper implant dentures indicate that too little consideration has been given to phonetics. The shape of the maxillae and mandible is altered by resorption. This resorption may occur under soft tissue-borne dentures and implant dentures alike. It is more disastrous when it occurs under implant dentures. The expense of treatment of edentulous patients by implant dentures makes the procedure unavailable to many people who might be benefited by it. The time involved in treatment of edentulous patients by implant dentures makes the procedure unavailable to most edentulous patients because there are not enough dentists to provide the service, even if all other unfavorable considerations were eliminated. This discussion is not intended to discourage sincere workers from further experimentation in this field of prosthodontics. Instead, I hope that it may point the way to an improvement of implant denture service.