An estimated 32 million Americans are missing some if not all of their natural teeth. With an aging population, the number of edentulous and partially edentulous individuals is expected to grow even larger.1 The demographics of the baby boomer generation and its effects on society are well known. This generation is more educated and more demanding than previous generations. Unlike their parents and grandparents, aging baby boomers are not likely to settle for old denture technology and aesthetically compromised dentures. They are more health conscious and more questioning.
The big question is: Who will make all the dentures that are going to be required in America in the coming years? Unfortunately, many dentists dread and even avoid this task. It is difficult to deal with an upset patient who needs ongoing adjustments, and mutual frustration can result. Does this problem sound familiar? What’s the answer? Refusing to make dentures? Referring new patients who need a partial or complete denture out of your office? Avoiding your existing denture patients who require an answer to their loose and worn dentures?
This article provides a step-by-step easy, predictable, and successful way to make complete maxillary and mandibular dentures. This is not to suggest that the described procedure is the only way to make dentures; rather, it represents an approach that simplifies some of the clinical aspects of denture fabrication.
STEP ONE: COMMUNICATION
The first important step is to ensure that you have good communication. Many patient problems can be avoided if the dentist remembers the adage “inform before you perform.” This, of course, holds true for any dental procedure. But with dentures there are many additional anatomical, social, and psychological factors to be considered. We suggest that an explanation of the proposed treatment plan be discussed in detail with the patient prior to the initiation of treatment. Unfortunately, most patients have unrealistic expectations—especially those who have not had removable dentures before. A simple and honest explanation that addresses patient concerns prior to treatment can avoid disappointment after the dentures are inserted.
If the patient is told that the complete mandibular denture will move to some degree, then the patient accepts the fact that there will be some movement of the mandibular denture. In other words, the patient will have a realistic expectation and understanding of how the mandibular denture will fit. The patient needs to be educated about the condition or state of her existing residual ridges, and how that might affect the support and retention of her dentures. If no prior explanation has been given and the patient is dissatisfied with the fit, then your words will be interpreted as an excuse rather than an explanation. You can never win this patient over. She will feel justified in blaming the dentist for an ill-fitting denture. This is where many denture problems begin.
The pretreatment consultation is also the right time to discuss the concept of dental implants. Dental implants have proved to be an extremely successful treatment modality that provides significantly improved comfort and security for most edentulous patients. It is our belief that dental professionals have an obligation to at least inform their patients about the value of implant-supported prostheses, whether or not your office provides this service. Obviously, factors such as health, economics, and bone availability must be considered; however, the patient has the right to be informed and then make his own decision based on this information.
Just as communication between dentist and patient is essential, so too is the communication between the dentist and the dental laboratory technician.
The Accu-Dent System 1 (Accu-Dent) impression technique is recommended for single-entry impressions for the completely edentulous patient.2 We find that it is the most predictable impression technique on the market for edentulous arches. Unique to this product are: the anatomically designed trays; differing viscosities for both the tray and syringe material; the nonslumping property of the materials; and the syringe delivery system. With the pre-packaged material there is no room for error during mixing.
|Figure 1. Proper placement of the nonslumping syringe material.||Figure 2. Final maxillary impression.|
|Figure 3. Mandibular impression with all anatomical landmarks clearly defined.|
The syringe material is first placed into the sulcus prior to the tray material being seated (Figure 1). This technique ensures accurate and full extensions of the impression material deep into the sulcus and other crucial anatomical landmarks, such as the retromolar pads and hamular notches (Figures 2 and 3). The syringe material’s viscosity is such that it causes no displacement or compression of the tissue. Both the syringe and tray material unite intraorally to form a perfectly detailed impression. The thixotropic tray material allows the dentist full control over the movement of the material, thus eliminating the gag sensations for the patient.
|Figure 4. Syringe tip presses impression material into critical rest and proximal areas.||Figure 5. Detail of tray and syringe materials after removal. This is the final impression.|
When taking impressions for partial dentures, Accu-Dent System 2 is used. The materials and trays are formulated differently for this system, and an additional syringe tip is provided for the delivery system, which greatly assists accurate placement of the syringe material over the occlusal surfaces of the natural dentition. This feature captures exceptional detail of rest preps and proximal surfaces of teeth for accurate framework fabrication3 (Figure 4). The tray material is then placed in a way similar to Accu-Dent System 1, and both tray and syringe material merge upon seating (Figure 5). In addition to partial denture impressions, we find Accu-Dent System 2 particularly useful for immediate dentures and athletic mouth guards.
Centric Tray Registration
|Figure 6. Centric Tray double-arch tray for proper vertical and centric registration.|
Another procedure that we recommend during the impression-taking appointment is the use of the Centric Tray (Figure 6) (Ivoclar North America). The Centric Tray is made of rigid plastic material, and is designed to take a double-arch registration simultaneously. The Centric Tray is used to record a preliminary vertical and centric jaw registration at the same impression appointment. This gives the technician the opportunity to mount the models on an articulator prior to the fabrication of the wax bite rims. This handy instrument can save a lot of valuable chair time and frustration for the next appointment.
|Figure 7. With the Centric Tray in place, patient closes to predetermined vertical.||Figure 8. Registration putty on the Centric Tray after removal.|
An approximate vertical dimension position is determined by using the patient’s existing dentures (if available). The patient is asked to close with the dentures inserted, and the distance between a pen dot on the patient’s nose and their chin is noted. The measurement is adjusted if necessary to better approximate the desired vertical dimension in the new dentures. The dentures are removed and the unloaded Centric Tray is tried in, and the procedures are rehearsed with the patient. Both sides of the centric tray are loaded with regular or fast-set Virtual impression putty (Ivoclar Vivadent). Normally, two scoops of base and two scoops of catalyst are sufficient. The patient is instructed to close slowly while being chin-guided into the centric jaw position. The patient is asked to stop closing once the predetermined vertical is reached (Figure 7). After the material has set, remove the Centric Tray from the mouth and check the record for proper registration of the ridges (Figure 8). It is not imperative to capture the full extension of the ridges with the Centric Tray registration, as the technician will require only to the first molar region to effectively mount the models into the articulator. The Accu-Dent System 1 tray material can be used as an alternative to the VPS putty. This is essential when the natural dentition has significant undercut or when a fixed partial denture is present.
The Centric Tray handle is also compatible with the Universal Transferbow (face bow) (Ivoclar Vivadent). Therefore, a face bow record can also be taken at this appointment if desired. This procedure is optional.
At the end of the first appointment you will have the final Accu-Dent maxillary and mandibular impressions, the Centric Tray record, and the face bow registration (optional).
|Figure 9. Casts can be mounted on articulator of choice.|
Prior to the second appointment the laboratory has mounted the casts and fabricated denture bases with occlusal wax rims. The accurate placement of the casts into the Centric Tray record is facilitated by trimming excess material from the preliminary bite with a sharp scalpel blade. This will allow the technician to place the casts accurately into the indentations of the Virtual putty inside the Centric Tray. Proceed to mount casts on an articulator of choice (Figure 9). The fabrication by the laboratory of maxillary and mandibular light-cured denture bases with occlusal wax rims is greatly facilitated by having the casts premounted using the Centric Tray registration.
|Figure 10. Establishing the wax rim occlusal plane.||Figure 11. Final occlusal wax rims.|
The wax rim occlusal plane is established by bisecting the intervestibular distance (measured from the deepest point of the mucolabial fold in the region of the central incisors [Figure 10] for the anterior reference point, and marking the upper third of the retromolar triangle for the posterior reference point [Figure 11]).
When tried in the patient’s mouth, the preliminary mounting of the casts ensures the dentist that the wax rim occlusion will be very close to that of the Centric Tray registration taken in appointment one, significantly reducing valuable chair time. In addition, the dentist and the technician have an opportunity to evaluate the vertical dimension, jaw relationship, preprosthetic surgery considerations, implant options, etc, early into the treatment.
Once again, while the existing dentures are in the mouth, place a pen dot on the tip of the nose and chin of the patient. Add or subtract to this measurement if necessary to re-establish the desired vertical that was established in appointment one. Remove the existing dentures and place the upper occlusal rim in the mouth. Check for proper lip support and incisal length. You may use a Fox plane to ensure a correct interpupillary line and alatragus line (Campers plane).
|Figure 12. Evaluation of maxillary occlusal wax rim with mandibular rim in place.|
The maxillary occlusal rim is tried in and marked for important information to assist the technician in the setup. When the patient is asked to smile, the midline and the high lip line (smile line) are marked. When the patient’s mouth is at rest, the corners of the mouth are marked to assist in the placement of the maxillary cuspids. We suggest that the mandibular bite rim be inserted at this time to help support the cheeks and lips while evaluating the maxillary occlusal wax rim (Figure 12).
Once you have tested the occlusal rims in the patient’s mouth for proper centric position and you are satisfied with the vertical dimension, remove the bite rims and place keyways in the area of the second bicuspid or first molar region bilaterally in both the maxillary and mandibular occlusal rims. These small v-shaped indentations are captured in the bite registration material, allowing the technician to replace the occlusal rims in their exact position should the registration be dislodged from the rims during shipping. Return the occlusal rims to the patient’s mouth and, with a fast-setting VPS bite registration paste (Virtual bite registration), syringe the material starting distal of the keyway placed in the mandibular occlusal wax rim, syringing in a continuous line to the opposite side, to the distal of the other keyway. Ask the patient to close and hold for the recommended set time. With Virtual material, the set time is 45 seconds. Note: The Shore hardness of the registration material should be at least 80 to ensure adequate rigidity and stability of the record.
Check the vertical dimension once again and be sure it is at the desired measurement. Remove bite rims from the patient’s mouth, separately or together. If separately, they can easily be repositioned in the exact position because of the keyways placed in the wax rims.
Anterior Tooth Selection
Encourage your patient to bring in pictures from previous years. Or better yet, ask her to bring in her partner or a family member during this appointment and allow them to make the decision about anterior teeth together.
The patient’s existing dentures can also serve as an invaluable source of information. Before making any changes to the size and shape of the anterior teeth, first ask patients if they would like a change in their appearance. They may like the shape of their existing denture’s anterior teeth. In such cases, it is recommended that an impression of the upper denture be made and sent to the dental laboratory for study purposes.
It is usually best if the shade of the teeth is chosen by the patient. Most times, our patients want a whiter smile. This is sometimes a paradoxical decision for some patients: they say that they want a white smile but they don’t want the dentures to look like dentures. We have found the Chromascop (Ivoclar Vivadent) shade guide to be an excellent educational tool for demonstrating basic “hues” and “value” information to the patient.
If only minimal information can be obtained from the patient, the task of anterior tooth selection can be accomplished by the laboratory technician using the maxillary model analysis technique as described in detail in the OPA (Occlusal Plane Analyzer) manual (Ivoclar Vivadent). The tooth selection can then be verified by the dentist at the next appointment.
Posterior Tooth Selection
The selection of “flatter” cusp angles for posterior teeth is a popular contemporary concept of denture occlusion because of the reduction of lateral forces to the residual ridges, ensuring more denture stability and retention. Unfortunately, most tooth moulds with flat or flatter cusp designs are aesthetically unacceptable to the patient. However, there are two new denture tooth lines that have recently been introduced by Ivoclar Vivadent—Ortholingual and Orthoplane—that satisfy the biomechanical requirements of flatter occlusion without sacrificing aesthetics or function.
|Figure 13. Ortholingual denture teeth for lingual contact occlusion.||Figure 14. Dominant maxillary lingual cusps contact an uncomplicated mandibular fossa.|
|Figure 15. Longer buccal premolars transition well with the cuspid.||Figure 16. Orthoplane denture teeth for monoplane occlusion.|
The Ortholingual mould has been designed specifically for lingualized (lingual contact) occlusion (Figure 13). The upper lingual cusps are dominant and the lower occlusal fossa is shallow and uncomplicated (Figure 14). This mortar-and-pestle form of occlusion has many advantages.4-6 In particular, it reduces lateral forces due to the minimal occlusal contacting surfaces and shallow cusp angles. In addition, it is a tooth form that is easy to set up and equilibrate, it eliminates cheek biting, and it satisfies the aesthetic demands of the patient. The longer buccal face of the premolars provides a pleasant transition from the cuspids, eliminating poor aesthetics at the maxillary buccal smile line (Figure 15). The double cross-linked resin chemistry also provides a very wear-resistant surface.
The Orthoplane tooth mould provides a monoplane option for those patients who require a zero-degree occlusal scheme (Figure 16). The aesthetics of this mould are exceptional for a non-cusped tooth form. Also, the mandibular mould has been designed to articulate with the ortholingual maxillary mould to create a lingualized (lingual contact) occlusal variation (Figure 17).
|Figure 17. Mandibular Orthoplane central fossa accepts the maxillary Ortholingual cusps for a combination occlusion.||Figure 18. Balanced occlusion set-up.|
|Figure 19. Fast set ridge lap design requires little or no adjustment.||Figure 20. Insertion of final dentures.|
The posterior mandibular teeth are positioned using a tooth setup template (2D template), which is a component of the Stratos 200 articulation system (BPS). This particular template is simple to use since it is attached to the upper member of the articulator. The template ensures that the mandibular posterior teeth are set bilaterally symmetrical on a predetermined anteroposterior (curve of Spee) and mesiolateral curve (curve of Wilson). This greatly facilitates the positioning of the maxillary posterior teeth and the subsequent balanced occlusion (Figure 18). The (fast set) ridge lap design of the Ortholingual and Orthoplane tooth moulds (Figure 19) also significantly decrease time- consuming cervical adjustment during the setup procedure.
At the wax try-in appointment it is always best to have the patient bring in a partner or family member for additional input. How often has a denture been finished according to a patient’s desires, only to be criticized by family members once the patient gets home? If the patient chooses not to have someone else give an opinion at the wax try-in appointment, then the responsibility must be assumed entirely by the patient; reiterate this once again. You can tell your patient it’s just like choosing eyeglasses; some people need the opinion of others to make a final decision.
The occlusion should also be carefully examined at this appointment. If necessary, another centric occlusal record should be taken. After the try-in, the setup should be checked on the articulator and the necessary corrections made.
When the patient and the dentist have accepted the wax try-in, instructions need to be given to the laboratory technician in order to finish the dentures for insertion.
The SR Ivocap system (Ivoclar Vivadent) is a continuous injection heat polymerization system that compensates for chemical shrinkage of the acrylic resin during polymerization, avoids an increase in the vertical dimension, and significantly reduces the movement of teeth, reducing your chairside adjustments significantly.7 It has been our experience that dentures processed with SR Ivocap require significantly fewer sore spot adjustments, retention and stability are enhanced, and the number of postinsertion adjustments are reduced dramatically. Because the polymer is completely saturated into the monomer during the mechanical mixing of the acrylic, the denture base material is void of micro- porosities, thus resisting the colonization of organisms on the tissue contacting surfaces, which can cause denture stomatitis and malodor. In addition, the Ivocap acrylic resin is a high-impact material and is cadmium-free.
With proper communication between dentist, technician and patient, the insertion appointment can be a rewarding, positive experience for everyone (Figure 20). The choice of premium materials and reliable techniques greatly increases our chance for success. Also, the importance of having the patient involved in the clinical process cannot be overemphasized. A few minutes spent with educational materials provides the answers to many of the patient’s concerns, and provides her with the feeling that she is involved with her treatment.
The number of patients who will require removable prosthodontic services is increasing at a staggering rate because of the demographics of the baby boomer population shift. In addition to the active lifestyles of some of our elderly patients, their increased attention to appearance and function has created much higher denture expectations than in the past. The advent of dental implantology has also given us new and exciting treatment options.
The profession clinically and technically faces serious challenges to prepare for these new demands. Removable prosthodontics can be the most rewarding component of our practice. The development, understanding, and use of these new materials and techniques in our practices are critical to our success.
The authors wish to thank Sandra Goergen, Technical Consultant to Ivoclar Vivadent in Schaan, Lichtenstein, for her help in the preparation of this article.
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2. Massad JJ, Connelly ME, Davis B. The Static impression technique for removable prosthodontics. Postgraduate Dentistry (a supplement to the Compendium). 2000;7:3-7.
3. Turbyfill W. Impression techniques for removable partial dentures. Gen Dent. 2001;49:358-364.
4. Massad JJ, Connelly ME. A simplified approach to optimizing denture stability with lingualized occlusion. Compend Contin Educ Dent. 2000;21:555-558,560,562.
5. Parr GR, Ivanhoe JR, Lingualized occlusion: an occlusion for all reasons. Dent Clin North Am. 1996;40:103-112.
6. Lang BR, Razzoog ME. Lingualized integration: tooth molds and an occlusal scheme for edentulous implant patients. Implant Dent. 1992;1:204-211.
7. Sykora O, Sutow E. Practical assessment of a continuous injection denture processing technique (SR-Ivocap). Quintessence Dent Technol. 1988;147-154.
Dr. Ber has been in private practice for 15 years in Oakville, Ontario, Canada. He has a particular interest in cosmetic and implant dentistry as well as precision dentures.
Ms. Tomkins is a BPS masters certified instructor and a clinical and technical consultant for three dental companies. She maintains a full-time private practice with a dentist and a hygienist and manages her own denture education facility, CanDEC (Canadian Denture Education Centre) in Brantford, Ontario, Canada.