Our patients who wear conventional removable appliances are often resigned to a reduced quality of life. Certainly esthetics can be improved with such appliances and there is some increased function, but for those of us who have our natural dentition, we can only imagine what it is like to wear “plastic teeth.” Dentures simply provide the minimal amount of tooth replacement.
Of course, our edentulous patients may continue to lose bone height and contour over time, requiring relines or replacement over the years. With resorption comes loss of facial support, lip support and vertical dimension of occlusion. No one in our society wants to look or feel older. Millions, if not billions, of dollars are spent each year by the public to stay or become more youthful. Just look at every other television commercial focused toward the baby boomer generation.
Although dentures may be an initial cost effective treatment modality they may not serve the best interest in the patient psychological and physical needs long term.
Dental implant reconstruction have become a viable alternative to conventional techniques. Implants help support anything from single teeth replacements to full arch reconstructions. We can use dental implants to support an overdenture, which increases stability and retention.1
Some of the essentials for ideal implant cases are implant position, accommodation for soft tissue health and a knowledgeable dental laboratory that fully understands the principles of design, form and function.
A most popular treatment plan provided to our patients for those who request fixed dentition is the highly advertised “all on 4," or "all on 6” screw retained “hybrid” dentures.2 What this infers is fabrication of a fixed appliance that uses denture teeth and a metal reinforced acrylic denture base. The advantage of these appliances is that the patient obtains permanent teeth, and there is acrylic used to provide lip support. The most graphic advantage is that the palate is not covered to a high level. These appliances are normally implant supported and do not rely on soft tissue contact. However, depending on implant position in the arch, there may be some tissue support of this design.
There are several disadvantages to this product, which include challenging home hygiene care. The patient must be trained to properly maintain under this appliance. Because this type of therapy involves composite (plastic) teeth and an acrylic base (although metal reinforced), the teeth can wear depending on the opposing occlusion. We have seen many of these appliances fracture due to occlusal stresses over time. Yes, even cases that I originally completed are deemed a failure by me over a period of time when esthetics or function are compromised. The appliance can fracture and the vertical dimension of occlusion can diminish. When negative things happen to our reconstructions, the appliances can be removed and corrected getting us back to the body of the dental implants. Remember the hybrid is simply screw retained.
We often consider “good, better, best” when discussing dental options to our patients. I would consider “good” to be the conventional removable appliance. Sure it provides some esthetics and certainly better function than no teeth at all. “Better” may be discussed as an implant retained overdenture.3
Something that is created to create retention and stability for our patients who struggle with our conventional techniques. Locator attachments are a popular method of adding retention when the implants are fairly parallel, or the implants can be connected with screw retained bars with the attachments on those bars.
For some of us, “better” may also be the denture tooth designed screw retained hybrid appliance described above. As technology and materials have improved over the past few years, we can achieve an even higher level of long -term function and esthetics.
We may now have a new “best” course of treatment available to our patients. This includes fabrication of monolithic zirconia (Bruxzir) fixed bridgework over our strategically placed dental implants.4 (Glidewell Lab, Irvine, CA)
FIGURE 1: Pre operative panoramic radiograph illustrating an edentulous maxilla and a few mandibular teeth retaining a conventional removable partial denture.
FIGURES 2 & 3: Pre operative esthetics of conventional maxillary complete denture. Note the upper lip contours.
FIGURES 4 & 5: Intraoral view of irritated maxillary mucosa and worn mandibular teeth.
FIGURE 6: CBCT analysis of hard tissues determines amount of interocclusal space available and vital anatomy.
FIGURE 7: Anatomage software helps in determines amount of available bone and allows for virtual placement of dental implants.
FIGURE 8: Implant position is established pre-operatively. Note 30 degree angle of most posterior implants allowing for a better anteriorposterior spread to support the final prosthesis.
FIGURES 9 & 10: A surgical guide is fabricated to help in angulation and positioning of the dental implants in the maxillary arch. The guide is fixated with stabilizing pins to prevent movement during the surgical osteotomy procedures.
FIGURES 11 & 12: Keys are use to help create the osteotomy preparation, from small diameter to larger diameter in preparation for implant placement.
FIGURE 13: The four dental implants are strategically placed in available bone.
FIGURES 14 & 15: Periapical radiographs illustrate the position of the implants.
FIGURE 16: Following integration of the implants, impression copings are placed. Note that angled abutments engage the implants allowing for nearly parallel positioning for the screws which will maintain the prosthesis.
FIGURE 22: The screw retained, metal reinforced maxillary appliance is placed. Initially the screw holes are covered with a transitional material and the patient will be evaluated for occlusion and any unloosening of the abutment screws over time.
FIGURES 23 & 24: Final esthetics of this denture based appliance. Esthetics are adequate and supportive like the conventional maxillary denture.
FIGURES 25, 26 & 27: After approximately 2 years of function, several issues are noted with the denture tooth appliance. The high quality denture teeth have worn significantly, changing the patient’s esthetics and function.
FIGURES 28 & 29: Although supported by a metal frame, the acylic fractured.
FIGURE 30: It was decided to place an additi onal dental implant to support a zirconia fixed bridge. Impression copings illustrate the angulation the implants needed to be placed so bone is engaged.
FIGURE 31: An open tray impression is made of the impression copings to provide an accurate duplication of the angled implants in place.
FIGURE 31 & 33: A Bruxzir cement on bridge was fabricated, reducing some of the palatal coverage and smoothing out any holes that were present in the previous reconstruction.
FIGURE 34: Custom abutments, with margins at the gingival contours, allow for a healthy tissue response.
FIGURE 35: The Bruxzir bridge is cemented into place with IMPROV dental implant provisional cement.
FIGURE 36: Retracted view of esthetics created with the cement on zirconia bridge
FIGURE37: Final esthetics of the bridge in place. Our patient was pleased with the final esthetic result and function..
Our treatment option discussion will be determined by a few factors. Our implant candidate patients much achieve two important levels. First, for implants to be successful we must consider the overall health of our patients. Uncontrolled medical problems, such as, uncontrolled diabetes, cardiac issues, cancer, liver disease, blood dyscrasias, severe alcoholism, smokers, and bisphosphonate use can affect blood flow and healing to surgical sites.2
The patients also must have enough quality and quantity of bone to accept our implants. Here experience can play a role. The use of CBCT analysis is one modern tool that will help all practitioners better examine the quality and quantity of bone available. I use the Vatech America PaX-i3D Green CT (Vatech America, Fort Lee, NJ)
It is also imperative that we discuss all options with our patients. Becoming well trained in the intricacies of implant dentistry is important. Live patient, hands-on implant training programs like the Engel Institute (Charlotte, NC) provides the dentist outstanding education on the process of implant dentistry.
Bruxzir zirconia provides excellent strength and wear resistance and esthetics which are positive to our patients.4 . The appliance are CAD/CAM designed and milled to the design direction of the dentist.
A positive long-term prognosis is expected with our modern implant techniques. Our patients want their teeth back, as much as is predictably possible with our design and technical skills.
In this case discussion, we were able to initially meet our patients desires and minimize many of her complaints.
This includes creating a fixed appliance which opened up the palate.
This patient no longer wanted any type of removable appliance. However, we did not really meet her long-term functional and esthetic expectations. Over time she became dissatisfied with what we had created. Because the case was simply screw retained we were able to replace her screw retained implant hybrid appliance with a more durable and esthetic full arch bridge.
CASE STUDY
Our patient is a 55-year-old, white female with no significant medical finding. Her ex-conventional maxillary complete denture and removable mandibular partial denture were tolerated for many years. With the advent of popularity of implant dentistry and our patients ability to educate themselves through the internet, she decided to examine other alternatives to improve her quality of life, form and function of her teeth.
Figures 1-5 demonstrate the pre operative panoramic radiograph illustrating the tooth loss and available bone in a two dimensional image. The denture supported her upper lip to some degree, however the intraoral images show irritated maxillary mucosa from long-term palatal coverage with the plastic of the denture and significantly worn mandibular teeth. CBCT analysis using the Vatech PaX-i3D Green CT (Vatech America, Fort Lee, NJ) we can determine the amount of available bone and vital anatomy (Figure 6).
Anatomage software (San Jose,CA) helps us to determine the amount of available bone and helps us virtually choose and place our implants in appropriate position. This includes design of the final prosthesis (Figure 7).
Implant position is established prior to ever surgically interacting with our patient. We consider undercuts and the height and width or the residual ridge. Attached gingiva availability is also critical to long-term success. At this time it was determined that four implants would be positioned to maximize the anterior posterior dimension and create a hybrid appliance to permanently fix the dentition, per the patient’s desires.
To maximize the A-P spread, the most posterior implants were angled in front of the large maxillary sinuses 30 degrees (Figure 8). From the CBCT diagnosis a surgical guide is fabricated.
This will help us properly place the implants per our pre-surgical diagnosis. We can see where the available bone is present and use it to our benefit. This guide is fixated to the arch with stabilizing pins to prevent movement during the surgical osteotomy procedures (Figures 9 & 10).
These precise guides are used with keys of various internal diameter. The osteotomy width and depth are predetermined with the use of this surgical guide and keys (Figures 11 & 12). The four dental implants were strategically placed in available bone (Figure 13). The periapical radiographs illustrate the position of the implants (Figures 14 & 15).
Following integration of the implants for about four months, impression copings are placed. Thirty degree angled abutments engage inside the implants to help upright screw position. It is clear that we now have nearly parallel positioning of all four implants (Figure 16). Note how palatal the anterior implants needed to be positioned to engage bone.
An accurate impression is made using polyvinylsiloxane material (Kettenbach, Huntington Beach, CA) (Figure 17). Our dental laboratory then created a screw retained denture tooth hybrid prosthesis over the four strategically positioned dental implants. Denture teeth are used over a metal cast reinforced acrylic prosthesis (Figures 18 & 19). It is imperative that radiographs are taken post placement to insure a complete seat (Figures 20 & 21).
The screw retained, metal reinforced maxillary appliance is placed. Initially the screw holes are covered with a transitional material and the patient allowed to evaluate for occlusal harmony. Any screw loosening can be easily corrected by simply retrieving the head of the screws (Figure 22). We can see by the final esthetics in Figures 23 and 24 support the lip with the acrylic flanges and provide an adequate vertical dimension of occlusion.
Approximately two years of function, several issues are noted with this denture tooth hybrid screw retained appliance. The high quality denture teeth have worn significantly as they opposed crown and bridgework in the mandible. Esthetics and function are compromised (Figures 25,26 & 27). As important it was noted that although the appliance was metal reinforced, the acrylic on the palate fractured (Figures 28 and 29.)
It was decided by us to place an additional implant and create a Bruxzir zirconia fixed bridge. The impression copings illustrate the angulation the implants were placed in engaged bone (Figure 30). An open tray impression is made of the impression copings to provide an accurate duplication of the angled implants (Figure 31). A Bruxzir cement on bridge was fabricated by Glidewell dental Lab (Irvine, CA ) over prepared custom abutments. This design reduced some of the palatal coverage seen in the original hybrid appliance. This round house bridge is cemented to place using Improv transitional implant cement (Figure 32 & 33). Custom abutments with margins at the gingival contour allow for a healthy tissue response and ability easier home maintenance by the patient (Figure34) The final bridge is cemented (Figure 35). The retracted view seen in Figure 36 illustrate the ability of the bridge to maintain lip and tissue support. The final result of Figure 37 show our pleased patient with esthetics and function. We were able to finally meet the patient’s expectations of minimal palatal coverage and long term durability.
Dr. Timothy Kosinski is an Affiliated Adjunct Clinical Professor at the University of Detroit Mercy School of Dentistry and serves on the editorial review board of Reality, the information source for esthetic dentistry, the Michigan Dental Association Journal, and is the Associate Editor of the national AGD journals. He is a Diplomat of the American Board of Oral Implantology/ Implant Dentistry, the International Congress of Oral Implantologists and the American Society of Osseointegration. He is a Fellow of the American Academy of Implant Dentistry and received his Mastership in the Academy of General Dentistry. Dr. Kosinski has published over 180 articles on the surgical and prosthetic phases of implant dentistry and was a contributor to the textbooks, Principles and Practices of Implant Dentistry, and 2010’s Dental Implantation and Technology. Dr. Kosinski can be reached at: 248 646-8651 or email drkosin@aol. com. www.smilecreator.net.
References:
1 – Oh, SH, Kim Y, et al. “Comparison of Fixed Implant Supported Prostheses, Removable Implant Supported Prostheses and Complete Dentures: Patient Satisfaction and Oral Health Related Quality of Life.” Clin Oral Implants Res. 2014, Oct. 24
2 – Brennan, M. Houston F. et al. “Patient Satisfaction and Oral Health Related Quality of Life Outcomes of Implant Overdentures and Fixed Complete Dentures. “ Int. J. Oral Maxillofac Implants. 2010, Jul-Aug; 25(4): 791-800
3 – Carames, J, Tovar, S et al. “Clinical Advantages and Limitations of Monolithic Zirconia Restorations: Full Arch Implant Supported Reconstruction.” Int. J. Dent. 2015: 2015:392-396.
4 – Harris, D., Hofer, S. et al. “A comparison of Implant Retained Mandibular Overdentures and Conventional Dentures on Quality of Life in Edentulous Patients: A Randomized, Prospective, Within Subject Controlled Clinical Trial. “ Clin Oral Implants Res. 2013. Jan; 24(1): 96-103
5 – Preciado, A, Del Rio, J. et al. “Impact of Various Screwed Implant Prostheses on Oral Health Related quality of Life as Measured with the QoLIP-10 and OHIP-14 Scales: A Cross Sectional Study. J. Dent. 2013, Dec; 41(12): 1196-207.
