Chapter 27 Minimally Invasive Implant Esthetics
All cosmetic principles are based on the tooth setup. With dentures, because of the loss of bone, the teeth must be placed close to the residual ridge to create a stable prosthesis. This often means they cannot be placed in an esthetic position. If, however, these dentures are supported and stabilized with implants, then the teeth can be placed in a more ideal position to achieve the desired esthetic look. Not only is the smile improved, but the lower third of the face is redeveloped from the extreme collapse of the vertical dimension. This approach contributes to the esthetics of the teeth that create the desired smile and facial proportions.
The nose and the chin begin to approximate one another because of the loss of vertical dimension. When the teeth are placed back to where they were before bone loss and once stability is achieved via implants, the facial proportions become more normal. With a typical denture look as a result of significant lost vertical dimension of occlusion, the nose becomes larger proportionate to the face. Reestablishing the proportion between the nose and other structures actually recreates the lost vertical dimension, giving the patient a proportional lower third of the face relative to the nose, eyes, and so on.
In proper position, the front teeth can be compared with the wheel of a wheelbarrow and the condyles act as the handles of the wheelbarrow. When vertical dimension is lost, it is akin to a flat front tire on the wheelbarrow, which puts extra strain and stress on the condyles, creating reduced function and increased muscle fatigue. Reestablishing the vertical dimension and putting the teeth where they are supposed to be reestablishes the condyle in proper position in relation to the base of the skull, thus allowing the muscles of mastication to function more ideally.
The patient with a conventional denture is able to generate only a fraction of the biting force of the patient with his or her own teeth. Through use of small implants for stabilization of the denture, patients gain a significant increase in function. The denture is stable, no longer moving, and no longer relying on the tissue for support. This approach achieves greater function, yields better esthetics, and in many cases positively affects phonetics.
The face of the patient whose nose and chin look like they are about to touch has the appearance of a chronic frown when viewed straight on. The corners of the mouth turn down because of the position of the mandible in relation to the maxilla as a result of significant bone loss. If the denture can be stabilized with implants, it is no longer necessary to rely on tooth position to create stability. The implants allow the teeth to be set in a more ideal position to reestablish the patient’s appearance, eliminating the frown look because the denture is supported by the implants. This also places the teeth so that they support the lip, rather than the lips supporting themselves. Denture patients may look as though they have a wad of tobacco underneath their lower lip because the upper lip is supporting the lower lip and causes it to curl. These people also experience communication problems beyond esthetics. In addition, there is a quality-of-life issue. The first impression they project is that they are unhappy people because of their facial appearance. Once these structures return to a position in which the teeth are in the right place, the lips are supported, the frown look is gone, the lower third of the face is reestablished, and the phonetics are cleaned up. Everything returns to a more ideal functional and esthetic state.
Implants have been in active use for 40 to 45 years. Initially the people who needed the implants the most did not have adequate bone to support the implants available at the time. The typical implants were made of titanium alloy. To use these implants, patients had to undergo very invasive grafting procedures that were only occasionally successful. The implants then evolved into mini-implants, which were not really different from the previous implants as they were still made of titanium and had the same shape. Early attachments were only good if the implants were placed parallel to each other. In most cases this eliminated maxillary treatment because it is almost impossible to place all the implants parallel owing to the anatomic realities. If it was necessary to use attachments that allowed the path of insertion to be altered when implants were not parallel. Thus, due to the superior position of the attachments the bar created, the implants were exposed to increased detrimental lateral forces of mastication. The denture that was supported by a bar (implant supported and implant retained) was exposed to the same forces as any fixed restoration. The bar essentially negated the ability to use a smaller implant because the surface area was lacking for this fixed application. When regular-sized implants were used in a bar-retained overdenture, bone loss would occur after only a few years, primarily because the lateral forces transmitted to the implants were not addressed. The development of an attachment that could alter the path of insertion on divergent implants and minimize lateral forces without a bar was the solution to the overdenture challenge. This new over denture technique produced a tissue-supported, implant-retained prosthesis that reduced the forces enough to make the smaller implants a predictable option.
The ERA® attachment (Sterngold Dental, Attleboro, Massachusetts, Figure 27-1) has been available for many years and was miniaturized and adapted to these smaller implants. The ERA®mini implant (an ERA abutment incorporated onto a 2.2 or 3.25 mm diameter implant) enables the clinician to place implants in areas that are too atrophic for traditional implants. Thus making it possible to treat many more patients in whom the remaining bone width is insufficient to support conventional implants without extensive bone grafting. The ERA®mini implant’s ability to alter the path of insertion and negate the need for a bar in the maxilla, has opened the door to these smaller implants in the maxilla where minimal bone is present, often without additional bone grafting. The success rate of the ERA®mini implants is equal to that of the larger implants in the over denture application primarily due the ability of the ERA® attachment to alter the path of insertion which significantly reduces forces placed on the implant. The ERA® supported denture, whether on conventional or smaller ERA®mini implants, creates a tissue-supported implant-retained prosthesis. Patients who were not eligible for the treatment previously can now proceed with a less invasive and significantly more economical technique. Once a stabilizing platform has been achieved (implant support) and the teeth can be replaced on a denture, the limitations previously caused by a lack of stabilization for the dentures no longer apply.
FIGURE 27-1 The resiliency of the ERA attachment is accomplished by using A, ERA male component with the black processing insert that occupies the entire metal housing. B, The white male insert (arrow) creates 0.4-mm space for resiliency and hinging inside the metal housing.
(Courtesy Sterngold Dental, LLC, Attleboro, Massachusetts.)
The clinician’s goal is to place the teeth in the proper position for function and esthetics whether the case is fixed or removable. The approach in establishing tooth position for function and esthetics is basically the same for dentures as it is for natural dentition. Phonetics are used to help identify the position where the anterior teeth should be relative to one another first and then the posterior teeth are addressed. The ERA® denture patient, because he or she has implants now has a stable platform. It is possible to use the same criteria (with a few exceptions) to reestablish where the teeth provide maximum function. The practitioner is relatively free to have the patient participate in establishing esthetics once position of functional stability has been achieved.
Once the esthetic end result has been determined, the practitioner can proceed to a wax try-in stage. Stabilization via implants at this stage allows the patient to test the phonetics and observe their own esthetics. Rather than proceeding to the finished case and hoping that the patient’s needs are addressed, the patient becomes an active participant, leading to better patient acceptance at the end of the case.
Minimally invasive implant procedures are indicated for patients who have unstable dentures and want to have the increased quality of life that stable dentures can provide. There must be a minimum of 8 mm vertical height and 3 mm width of bone. These parameters are achieved in about 95% of all denture patients. Relating this to a conventional implant, the minimums are 8 mm height and 5 mm width parameters, which are not seen in most long-term denture patients.
It is important to note that most patients are in their 50s, 60s, and 70s. Because they tend to have a multitude of medical problems, dental practitioners must consult these patients’ medical care providers. With few exceptions, most persons at these ages can be treated with guidance from the primary healthcare giver.
It is unlikely that a good result will be achieved if the patient has severe osteoporosis and minimal bone. A subject with osteoporosis but adequate bone could be treated successfully. Hemophilia is a contraindication for any kind of surgery, and certain medical and heart conditions may preclude elective procedures as can radiation treatment of maxilla or mandible.
It is better to place a smaller implant in adequate bone than to place a larger implant where the bone is very thin. Because the maxilla is addressed and bars are not being used, it is necessary to use an attachment that will allow for alteration of the path of insertion. Currently only the ERA® Attachment System (Sterngold Dental) has the ability to alter the path of insertion (Figure 27-2) and create vertical resiliency with multiple retentive strengths (see Figures 27-1 and 27-2). The other small attachments on the market are appropriate only in situations in which the implants are parallel. If the implants can be positioned parallel, almost anything can serve as an attachment. If the osseous contour makes it impossible for the implants to be placed parallel, only the ERA® attachment will alter the path of insertion sufficiently to enable it to be made parallel.
(Courtesy Sterngold Dental, LLC, Attleboro, Massachusetts.)
The technology has expanded, so these implants are starting to be used widely as an orthodontic tool to move teeth and grow bone in lieu of grafting. They are also being used for intruded molars. The primary use for the ERA®mini implant still remains to be in the overdenture applications.
This technology should not be used to support a single tooth restoration, a bicuspid or molar, as this would certainly lead to failure. It is not meant to be used in a fixed application, but primarily for overdenture application when there is insufficient bone to accommodate larger implants.
The goal is to enlighten general dentists to treat their denture patients with ERA®mini implants. There are two different protocols, one for the maxilla and the other for the mandible, owing to the different quality of bone in each. If the bone quality or quantity is difficult to determine with routine radiographs, then a scan appliance with fiduciary markers is created; it is important to make the appliance stable and carefully inserted prior to taking a computed tomography (CT) scan. The information from this scan is entered into one of many computer programs that allow the clinician to view the available bone three-dimensionally and virtually place implants until the result is satisfactory. The plan is recorded along with implant size and sent to be made into a surgical guide appliance. The guide allows placement of the implants in the precise position identified on the computer during the virtual placement. This approach removes anxiety and provides accuracy within a 0.5 millimeter.
Eighty-five percent of patients with bad dentures have already spent a lot of money without comfort or satisfaction. Often it becomes an issue of expense. It is possible to retrofit the existing denture to keep the cost lower. If the patient wants to take the process a step further, this can be achieved in steps. Initially stabilization of the denture provides the comfort the patient is seeking. Once this has been accomplished, the patient is often more open to looking at the esthetics that a new stable, implant supported denture can provide.
The attachment used has resiliency, allows alteration of the path of insertion, and has multiple retentive strengths. This innovation makes it is possible to retrofit the existing denture or a new denture. The implants continue to function as long as the patient needs them. The ERA®mini implant was created by combining a micro ERA® attachment with a smaller implant of the same material makeup as the conventional implant and an aggressive self-tapping thread design. Where the bone is not dense, under-sizing the osteotomy, an effect much like squeezing a sponge (making the sponge denser), is achieved. In maxillary areas where the bone is not of good quality, better bone quality is created by condensing the bone around the implant as it taps its way into the spongy bone. The implant-bone interface is much denser then the surrounding bone and provides stability during the healing phase. Altering the path of insertion, without incorporating detrimental forces of mastication, will correct for misalignment (see Figure 27-2).
The use of CT technology is a major advance. The software has been made more user friendly and provides points of reference that were not previously available. The CT scan is taken with three metal markers that enable a three-dimensional point of reference. Even without extensive training, it is possible to virtually place the implant on the computer’s three-dimensional representation of a specific patient’s mouth. It not only gives the location but provides a relative bone density, maximizing implant placement in the densest bone available. The scan also allows the practitioner to view and avoid areas such as the neurovascular bundle in the lower jaw and the sinuses in the upper jaw, allowing greater predictability and increases the comfort zone for the general dentist.
Using the CT scan prepared guide allows the practitioner to spend less time in the patient’s mouth, increases efficiency, and reduces overhead. With less overhead, the patient may face a reduced cost for the procedure, and making it an option for more patients. Everybody wins because the technology permits greater efficiency and effectiveness in a shorter amount of time. It also makes the procedure less invasive because of the reduced time in the mouth and the lowered potential for post-operative swelling, infection, and so on.
Cosmetic dentistry is both an art and a science. With dentures, the art has basically been eliminated because the teeth cannot be placed exactly as desired without creating an unstable platform and unstable dentures. With the smaller implants and the ability to precisely place them using CT technology, the artistic aspect returns without compromising stability or function. For example, in replacing an anterior tooth in a patient with teeth, photographs are used to characterize the replacement tooth to match the natural teeth next to it; the soft tissue is not part of the treatment. Dentures however present an additional challenge because the tissue is replaced with a resin supporting the teeth that often does not match the patient’s natural soft tissue, making it look very artificial. Once a stable platform has been accomplished, the process can be taken into a different arena. The patient’s soft tissues are photographed, and the photos are sent to the lab. Dentists are no longer limited to a purple or gray modeling of the soft tissue because the lab technician can color-match an accurate photograph of the soft tissue. It is mimicked so that it becomes difficult to see where the soft tissue ends and the denture base begins. Artistically, something totally artificial is made to look natural.
The sequencing establishes the number of visits that will be needed, based on the patient’s initial presentation, and the laboratory technician’s work. All patients are asked about their chief complaint. The practitioner may see other things that need to be done first, but all factors are thrown into the mix. The denture patient usually wants a stable denture and may not even consider the esthetics. The clinician’s job is to encourage patients to look beyond the immediate complaint. Once a stable denture has been created, the patient can be asked how he or she would like the teeth to appear. A list of options can be offered. To achieve a more stable denture usually requires implant placement at some point. If the patient’s other chief complaint is about the plastic on the roof of />