Planning and carrying out implant treatment in the edentulous maxilla is a more difficult and more extensive process than that involved in any other indication. It requires highly meticulous diagnostic investigations, which should routinely include conventional computed tomography (CT) or cone beam computed tomography (CBCT) with a custom template. This is a time-consuming but also very effective method, and should form part of standard diagnosis.

3D diagnosis with a custom template

Usually, the patient for edentulous implant treatment has already been fitted with a complete prosthesis. Provided the tooth set-up is correct, this prosthesis can be used as a basis for fabricating the implant template. To do this, it is duplicated in full and converted into a template made of a transparent but radiopaque plastic (Fig 6-1a). However, if the old restoration does not meet the expectations of either the patient or the dentist, the teeth will need to be set up again according to the principles of full mouth rehabilitation and also duplicated, to allow the optimal implant positions to be determined.

If the duplicated prosthesis is available as a basis for the template, concrete planning for implant placement can now begin. To begin with, it is advantageous to plan more implants than will actually be needed. If analysis of the CT scan images or the situation at the time of implant placement shows that the anatomical structure of the maxillary bone is not suitable for implants at all the planned locations, the described procedure leaves the option of selecting the most favorable sites.

In the first step, one hole is drilled in the template at each of the planned implant positions; these need to reproduce the longitudinal axes of the implants (Fig 6-1b). The drilled holes provide good reference points in both CT and CBCT imaging without producing artifacts.

To ensure that the template remains uncluttered, the author prefers to place the drill holes in positions 1, 3, 5, 6 and 7 (Fig 6-1c). The lateral incisors and the first premolars can then be positioned between the existing holes as required.

Before taking the radiograph, the template is stabilized in the patient’s mouth on the mandibular dentition, with an additional occlusion rim if necessary. A CT or CBCT scan is then performed on the patient while he or she bites down. The resultant data are fed into a planning program, eg, SimPlant (Dentsply) in Digital Imaging and Communications in Medicine (DICOM) format. In the SimPlant program, the maxilla can be visualized in three planes: axial, panoramic or cross-sectional, and also as a 3D reconstruction (Fig 6-1d). The panoramic and axial sections provide the best spatial orientation. However, the actual positioning of an implant usually takes place in the cross-sectional image. This section allows the position of the drill hole and the anatomy of the residual ridge to be brought into line (Fig 6-1e). In region 13, for example, a slight inclination palatally is sufficient to ensure that the implant is anchored in the bone (Fig 6-1f). In region 26, the drill hole corresponds almost exactly to the contours of the residual ridge (Fig 6-1g). However, shifting the implant slightly in the buccal direction allows it to be anchored more evenly in the bone that has been augmented following sinus elevation (Fig 6-1h).

The uniform distribution of thicker bone around the implant ensures a better supply of nutrients to the tissue. Due to anatomical reasons, however, no implants can be placed at some of the initially planned positions, such as region 21, so a substitute site needs to be found (Fig 6-1i). In addition to the template, the titanium pins used to attach the membrane (in this case, regions 13 and 16, buccal side in the axial section) during sinus elevation also provide good spatial reference points (Fig 6-1j).

Thanks to the accurate 3D diagnosis, it proved possible to place the 10 implants in the bone with good stability in the preoperatively planned positions (Fig 6-1k). At the patient’s request, the dental treatment required in the mandible was to take place at a later date.

For the treatment course, see pages 473–479.

Rehabilitation without reconstruction of the posterior maxilla

In an implant-supported restoration of the edentulous maxilla, the esthetic aspects involved in treating the anterior teeth combine with the functional aspects of restoring the posterior teeth. Above all, this means resolving the question of how the masticatory forces in the molar region (the center of occlusal force) are to be absorbed. One problem in the posterior maxilla is that very little bone tissue is often left after teeth are lost, and that this tissue also offers little retention for implants due to its cancellous structure. Without augmentation of the posterior maxilla (sinus floor elevation), implant placement is usually possible only in the anterior maxilla, where the bone supply tends to be sufficient. Even if full rehabilitation of the masticatory organ cannot be achieved, this form of restoration has also proved itself scientifically reliable. A hybrid prosthesis or a cantilever fixed implant bridge with a shortened dental arch (up to the first molar) can be incorporated.

Implant placement

Six implants were inserted into the anterior maxilla (Fig 6-3b). The two distal implants in regions 14 and 24 were inserted with a slight tilt in the mesial direction, to prevent contact with the maxillary sinus. This was followed by augmentation with the harvested bone chips and Bio-Oss (Geistlich). The augmentation material was covered with a membrane 30 × 40 mm in size, divided into two halves. The two halves of the membrane were attached at both the apical and coronal ends with titanium pins (Fig 6-3c).

Exposure and prosthetic restoration

The implants were ready for exposure after 6 months (Fig 6-3d). The incision was made on the palatal side, to allow keratinized gingiva to be transposed toward the labial/buccal vestibule. Once the healing abutments were screwed on, the radius of the flap was increased to such an extent as to necessitate a deficit of approximately 5 mm at the midline (Fig 6-3e; see Note on page 427). At the time of incorporation of the prosthesis 2 months later, nothing identifiable remained of the soft tissue deficit created after the exposure (Fig 6-3f). The palateless prosthesis was stabilized on the bar connector that had been milled at the same time, and additionally “locked on” with two MK1 attachments (Figs 6-3g and 6-3h). When closed, the attachments were flush with the palate plate, so that they were virtually undetectable by the tongue (Fig 6-3i). From the labial/buccal side, the prosthesis can be designed like a complete denture and the access holes to the attachments are barely visible (Fig 6-3j). The follow-up radiograph after 4 years of functional use shows a stable bone situation around the implants (Fig 6-3k). The patient is happy not only about her securely fitting prosthesis and the absence of a plate covering her palate, but also that the cost involved was reasonable (Fig 6-3l).

Implant placement and prosthetic restoration

It proved possible to insert all 10 implants at the planned positions (Fig 6-5b). At the time of exposure, however, it emerged that the 8.5-mm long implant at position 25 had not been osseointegrated. This meant that it had to be removed. A long-term provisional to be supported on the nine osseointegrated implants was fabricated according to the “Progressive Bone Loading” concept (see page 387; Fig 6-5c). This provisional was made of plastic with a metal framework and screwed onto EsthetiCone abutments (Nobel Biocare) (Fig 6-5d). The provisional could not be extended with cantilevers at the distal ends to avoid the risk of excess loading of the implants.

The definitive fixed restoration was fabricated after the patient had worn the fixed provisional for 1 year (Fig 6-5e). A cantilever could now be added to the definitive prosthesis (Fig 6-5f). After 5 years in situ, the front view of the denture is satisfactory, apart from the visible metal parts (Fig 6-5g). The panoramic radiograph shows a currently stable bone situation, along with the extent of the cantilevers (Fig 6-5h).

Implant placement and extraction

However, the diagnostic investigations for the patient’s restoration revealed an incidental finding. On the panoramic radiograph (Fig 6-6b) one can barely distinguish an ectopic, impacted tooth in the maxillary bone in regions 21 to 23. The root apex of this tooth was close to the planned implant position (Fig 6-6c). The three-dimensional (3D) visualization in the CT scan allowed the position of this tooth to be accurately determined. The vertical sections show that the body of the tooth runs from the palate and into the nasal cavity (Fig 6-6d). During implant placement, the palatal mucosa was dissected away, the tooth divided and removed. The extracted tooth can be seen in Fig 6-6e. Following the extraction, the implants were successfully inserted into region 21 and five further positions, as planned.

Prosthetic restoration

The canines were left in situ until the new prosthetic restoration was fabricated, so that they could continue to secure the overdenture (Fig 6-6f). Five weeks after exposure, a fabricated continuous bar connector was screwed on to the six implants (Fig 6-6g). The distal locking attachments hold the palateless denture securely in place (Fig 6-6h). The bar connector and the mucosal situation remain stable 5 years after the implants were loaded with the prosthesis (Fig 6-6i). The condition of the prosthesis is also satisfactory (Fig 6-6j). Moreover, a stable bone situation is apparent from the follow-up panoramic radiograph taken after 5 years (Fig 6-6k).

Implant placement and exposure

The custom-made surgical template with the desired implant positions was fabricated in the laboratory and placed into the operation site following flap reflection (Fig 6-7c). Since the template did not stay in place securely due to the high proportion of unattached mucosa, it was stabilized further with direction indicators once the first two beds were drilled. Only then were the beds for the remaining implants drilled (Fig 6-7d).

The residual ridge had atrophied greatly during the 15 years’ use of the complete denture and was narrower than the diameter of the implants. Consequently, the implant threads were exposed on both the labial/buccal and palatal sides. Moreover, the implants had to be placed further palatally than originally planned (Fig 6-7e). Bone augmentation was performed with a mixture of Bio-Oss and bone chips, not only on the labial/buccal but also the palatal side (Fig 6-7f). Bio-Gide (Geistlich) membranes were used to cover the augmentation.

Following healing and exposure, the implants were fitted with EsthetiCone and angled abutments (Fig 6-7g). The deliberate inclination of implants 13 and 25 to avoid the maxillary sinus was compensated for by using abutments angled at 17 degrees (Fig 6-7h).

Prosthetic restoration

The cantilever implant bridge replacing teeth 16 to 26 was screwed onto the implants with occlusal screws (Fig 6-7i). At the patient’s request, crown 24, like the one in his previous complete denture, was fabricated out of gold (Fig 6-7j). The patient is very satisfied with the fixed restoration of both mandible and maxilla (Fig 6-7k). The follow-up radiograph after 5 years of wear confirms a stable bone situation even in the presence of the inclined implants in regions 13 and 25 and the short 8.5-mm implant in region 15 (Fig 6-7l).

Preoperative preparation

Using two CBCT scans (patient with prosthesis and the prosthesis alone) as the basis, the 3D planning was carried out with the NobelGuide software. Based on the data set, a 3D template was fabricated in Sweden and sent to the clinic (Fig 6-9c). With the aid of the template, implant analogs were inserted into the definitive cast at the exact positions where implants were to be placed in the maxilla later on (Fig 6-9d). The dental prosthesis was then fabricated on the resultant cast even before the operation (Fig 6-9e). The prosthesis needed to be able to compensate for any irregularities, particularly those caused by mucosal resilience during the operation. It was to be used as a long-term provisional restoration and, in the best-case scenario, even as the definitive one. An occlusion rim was also made out of putty to ensure exact positioning of the template (Fig 6-9f).

Implant placement and immediate restoration

Following extensive block and infiltration anesthesia (it is extremely difficult to top up the anesthesia with the template in situ), the template was placed into the mouth with the occlusion rim. To enable the relative positions of the occlusion rim to the template to be verified, vertical lines were drawn on both with a marker pen (Fig 6-9g). After the template was inserted, the patient was asked to bite down hard for a few minutes, to reduce the mucosal swelling caused by the infiltration anesthesia. With the patient still biting down lightly, three holes were drilled through the horizontal sleeves and the template secured to the jaw with three pins. After this, beds were drilled for implants 13 and 24 using sleeves that had been adjusted relative to one another, and these implants were placed. The insertion mounts were then replaced with stabilization abutments and two further implants inserted into regions 14 and 23 (Fig 6-9h). After all the implants were placed, the template was removed, showing how atraumatic this method is (Fig 6-9i). The abutments prepared in advance in the laboratory were screwed on in pairs and incorporated into the dental prosthesis with Pattern Resin (GC America) (Fig 6-9j). The completed dental prosthesis was finished and polished by the laboratory technician (Fig 6-9k) and attached to the implants in the mouth with screws. The screw access holes were provisionally sealed (Fig 6-9l). After only one operation, the patient was able to leave the clinic immediately with a fixed restoration. She was fully fit, with no pain or swelling (Fig 6-9m). The final photo shows the dental prosthesis after 4 years of functional use (Fig 6-9n).

Rehabilitation with reconstruction of the posterior maxilla

Considerable bone loss is often seen in the maxillary sinus due to the loss of teeth in the molar region. This bone loss progresses in the caudal and mesial directions. The technique known as sinus floor elevation, or simply sinus floor elevation, has become an established way of creating a firm “foundation” in this region (see page 383). It is a highly effective surgical procedure, enabling full prosthetic rehabilitation of the posterior maxilla to be achieved.

After bone augmentation in the posterior maxilla, where the masticatory forces are at their most powerful, implants can be placed there in accordance with static principles. In exchange, the anterior maxilla can be restored with pontics fabricated with esthetics in mind, without the use of implants. Moreover, the whole maxilla offers sufficient space for the abutments needed for a provisional restoration, whether it is supported on the patient’s own teeth or on provisional implants.

Sinus floor elevation, implant placement and lateral augmentation

Since the dimensions of the bone in the posterior maxilla were still sufficient to anchor implants with primary stability, implant placement was performed in the same session as sinus elevation (Fig 6-11c). The maxillary sinus was prepared first, after which the implant beds were drilled and the three mesial implants fully inserted.

Initially, the two distal implants were not inserted fully. The maxillary sinus was then augmented, allowing these implants to also be inserted fully. After the cover screws were fitted, lateral augmentation was performed with harvested bone chips and Bio-Oss. The membrane was attached to the maxilla with titanium pins (Fig 6-11d). This procedure was repeated on the left side (Fig 6-11e). The residual ridge was quite narrow in the anterior maxilla, and the implants were inserted further toward the palatal direction (Fig 6-11f). The bone was also augmented over the screw threads exposed on the palatal side (Fig 6-11g). A membrane was attached with pins at the apical end and pushed under the palatal periosteum (Fig 6-11h). This was followed by saliva-proof closure of the operation site. The postoperative panoramic radiograph shows the positions of the implants and the extent of sinus elevation (Fig 6-11i).

Exposure

The healing period was uncomplicated and the implants were exposed 10 months after the first operation (Fig 6-11j). The residual ridge looked much wider compared to baseline, which suggests a successful augmentation (compare Figs 6-11b and 6-11k). On close inspection, however, we found that the solid substructure was covered only with unattached mucosa on the labial side (Fig 6-11l). In fact, the time of implant exposure offers the best opportunity of correcting this, by transplanting keratinized gingiva from the palate to the vestibule in the form of a pedunculated graft (Fig 6-11m). Sutures were used to bring the soft tissue of the palate much closer to the tissue surrounding the implants (Fig 6-11n). On the left side, the implants were already faintly visible through the unattached mucosa (Fig 6-11o). The incision was also made on the palate, alongside the implants (Fig 6-11p). Distal extension of the incision enabled better adaptation of the flap and made suturing easier (Fig 6-11q). Three weeks after exposure, the soft tissue situation on both sides was stable (Figs 6-11r and 6-11s). The zone of attached gingiva around the implants had a positive effect on their long-term prognosis. Direct comparison of the residual ridge at the start of the treatment and after the surgical and regenerative phase shows a marked improvement (Figs 6-11b and 6-11t), which is even more remarkable, given that the result was achieved by relatively simple means (ie, with no bone block grafts, mucosal distraction or free mucosal grafts) in only two sessions. The impression for the prosthetic restoration was taken once the correct positioning of the impression copings was checked on the radiograph (Fig 6-11u).

Sinus floor elevation

The first step was to perform sinus elevation on both sides of the maxilla. Titanium pins (5-mm long) (Figs 6-12h and 6-12j) were used as supports for the augmentation material and the membrane used in the vertical reconstruction of the residual ridge on the left side (at the time, it was level with the palate or even slightly below it; see Fig 6-12i). The augmentation of the cavity in the maxillary sinus and the vertical augmentation were performed with Bio-Oss and a Bio-Gide membrane. Following periosteal slitting and marked mobilization of the mucoperiosteal flap, the operation site was closed with Gore-Tex 4-0 and Mopylen 6-0 sutures (W. L. Gore and Associates and Resorba, respectively). The sutures were removed around 2 and 3 weeks after sinus elevation (Fig 6-12k).

Implant placement

Because of the extreme atrophy (Fig 6-12l), a 1-year healing period was scheduled after sinus elevation and ridge augmentation, before implant placement could take place (Fig 6-12m). The gain in bone mass is clearly apparent in the 3D reconstructions (compare Figs 6-12l and 6-12m). A panoramic radiograph was taken as a check after augmentation (Fig 6-12o). Implant placement was planned using SimPlant, based on the up-do-date CBCT scan (Fig 6-12p).

The overall contours of the residual ridge (Fig 6-12n), but particularly the zones of vertical augmentation in the left premolar region (Fig 6-12q), appeared to have improved markedly relative to baseline (see Fig 6-12f). In accordance with the SimPlant planning, five implants were inserted into the augmented bone on the left side (Fig 6-12r). The right side turned out to be more problematic, as much less bone had formed there. It was only possible to insert four implants here, placing them not in line but alternately on the palatal and buccal side of the crest, to leave sufficient space between them (Fig 6-12s). This staggered placement also ensured better distribution of the masticatory forces over the prosthetic superstructure. The region was re-augmented with the harvested bone chips and Bio-Oss, followed by tight suturing. A postoperative panoramic radiograph was taken after implant placement (Fig 6-12t).

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