Even at the diagnostic stage, the factors that take priority in the posterior maxilla differ from those in the anterior maxilla. The esthetic component plays an important role here also, but the main focus is on the available bone supply and its quality. Typically, the loss of teeth brings with it a reduction in the bone bed, so that implant-based restorations of larger gaps or free-end situations are often possible only with the aid of augmentative measures. Single dental implant placement tends to be a rarity in the posterior maxilla; consequently, it will only be given brief consideration here. The failure risk of single implant placement is higher in the molar region, as the bone here is usually softer and subjected to greater physical forces than in the anterior maxilla.

Diagnosis

Conventional diagnosis

The diagnostic stages involved in a multi-tooth gap and a free-end situation are virtually identical. For prosthetic reasons, the implants should be inserted exactly where the natural teeth were originally located, or would have been located in the ideal-case scenario. These positions are reconstructed by setting up prosthetic teeth onto the maxillary cast in articulation (Figs 5-1a and 5-1b). If ground-down abutment teeth are present, these must also be waxed up (Fig 5-1b).

Fabrication of a radiologic or surgical template

A surgical drill template is constructed from a transparent plastic to allow the implant positions as determined on the cast to be accurately transposed to the patient. Initially, the wax-up needs to be duplicated in plaster, so that a template base can be fabricated using a thermoplastic foil (Figs 5-1c and 5-1d); otherwise, the wax-up would be altered by the heat in the deep-drawing device. The desired implant positions are marked in with a marker pen (Fig 5-1d). The marked sites are drilled and the parallelization pins attached to both the cast and the thermoplastic foil in accordance with the desired implant axes (Fig 5-1e). The pins must be so securely attached to the cast that they remain aligned exactly as required when the thermoplastic foil is removed (Fig 5-1f). Titanium sleeves are incorporated into the template at the specified positions to allow the planned implant sites to be identified in the radiograph. The sleeves are placed onto the parallelization pins, so that the channel of the sleeve reproduces the ideal implant position (Fig 5-1f). Generous openings are cut into the occlusal side of the thermoplastic foil and the latter is placed on the model (Fig 5-1g). The spaces thus created are filled with cold-curing polymer, securely anchoring the titanium sleeves in the template. The resultant template is worked up for the radiologic diagnosis (Fig 5-1h). A panoramic radiograph is taken or a cone beam computed tomography (CBCT) scan prepared with the template (Fig 5-1i). Since the sleeves are made out of titanium rather than steel, the template can also be used for a CT scan.

The inserted sleeves restrict the drilling to a specific course (Fig 5-1j). However, the sleeves can be removed to allow a change in angle if the bone situation is unfavorable (Fig 5-1k). The entire buccal wall of the template should also be removed to give a better view of the operation area. The desired implant positions are still clearly determined by the notches in the palatal part of the template. During the course of implant placement, a template prepared in this way (Fig 5-1l) can be disinfected with, eg, alcohol or chlorhexidine, but must not be sterilized in the autoclave under any circumstances due to the risk of deformation.

For the treatment course, see page 327.

3D diagnosis and planning

Three-dimensional (3D) diagnosis in the posterior maxilla is already of significance in the overall treatment plan. The first decision to be made is whether direct implant placement is possible or whether the bone bed must be augmented first (sinus floor elevation). In the latter case, two CT scans and two sets of 3D planning are likely to be needed: one of each before sinus elevation and one after the bone has been augmented, but before implant placement. In the case presented here, we concentrate on the implant planning following preparation of the bone bed, ie, after sinus elevation (Fig 5-3a). The extent of the augmentation is clearly apparent in the panoramic section (Fig 5-3b). The detailed planning for each individual implant begins on the cross-sectional images (Fig 5-3c). In this projection, the proposed implant is placed into the maxilla virtually, either as a solid image or in outline (Fig 5-3d). On the other hand, the placement and distribution of all the implants can be seen best in the panoramic section (Fig 5-3e). The planned positions of all the implants are then checked in other planes and projection over the entire image surface area (Fig 5-3f). The 3D reconstruction provides the most vivid visualization and is best suited for the patient information procedure (Fig 5-3g). For the purposes of accurate analysis and documentation, the bone quality around each individual implant should also be determined by bone densitometry (Figs 5-3h to 5-3l). Implant 1 (region 23) is to be anchored in the existing local bone and shows the highest density values in the central region (Fig 5-3h). As an approximation, implant 2 (region 24) is to be anchored half in existing and half in augmented bone (Fig 5-3i). The difference between existing local bone and the bone substitute Bio-Oss (Geistlich) in the sinus floor elevation area becomes even more marked around implant 3 (region 25; Fig 5-3j). According to the available calculations, the augmented new bone, rich in Bio-Oss, shows much higher bone density than the autologous bone. Implants 4 and 5 (regions 26 and 27) also show a continuing decrease in the quality of both local and augmented bone in the distal direction (Figs 5-3k and 5-3l). This tendency toward a distal decrease in bone density is confirmed clinically in most cases while the implant beds are being prepared.

For the treatment course, see page 378.

Restoration of single- and multi-tooth gaps

Implant placement

Since the patient did not agree to a sinus floor elevation due to the increased operation time and complexity and the prolonged healing time, it was necessary to find a compromise solution. Positions 12, 14 and 15 were chosen for implant placement. The implant axes were adjusted to the anatomical situation (especially the implant in region 15; Fig 5-4c). Implants 14 and 15 were fitted with cover screws; implant 12 was fitted with a healing abutment for better mucosal support (Fig 5-4d). The postoperative radiograph shows three different implant types (Fig 5-4e). In region 12, where the bone was at its hardest, a self-tapping Brånemark System MK II fixture (15-mm long, 3.75 mm in diameter) was inserted to extend into the cortical bone of the floor of the nasal cavity. In region 14, where the bone was somewhat softer, a standard fixture (18-mm long, 3.75-mm in diameter) was placed parallel to the canine and inserted, without prior thread-cutting, to extend into the cortical bone of the floor of the maxillary sinus. The Brånemark System MK IV fixture has been developed especially for soft bone. It is slightly conical in shape (apical diameter 3.75 mm, coronal diameter 4 mm), has a double thread and thus provides very high primary stability.

Exposure and prosthetic restoration

The patient was able to wear a provisional fixed bridge, supported on teeth 13 and 18, throughout the healing period. The mucosal situation in region 12 was optimized further by the incision used during implant exposure and by the suturing technique (the cosine curve technique, see Note on page 330). The same cosine curve technique was used for the exposure of implants 14 and 15. Copings were fitted both onto the implants in region 12, 14 and 15 and onto natural teeth 13 and 18 (Fig 5-4f). Custom-cast abutments were screwed onto the implants, while copings were cemented onto the natural teeth (Fig 5-4g). The telescopic fixed bridge was now provisionally secured onto all five abutments with TempBond Kerr; Fig 5-4h. The pale veneer was applied to the denture at the express request of the patient (Fig 5-4i).

Implant placement and recording of the implant positions

It proved possible to insert the implants in positions 14, 13, 12, 11 and 21 into the existing local bone. As the buccal and labial atrophy of the residual ridge could not be fully reconstructed, at the request of the patient, the implants were placed further palatally than planned from the prosthetic point of view. To allow the superstructure to be prepared before exposure, it was necessary to record exact the exact positions of the implants and their relationships to one another and to the residual dentition.

For this purpose, impression copings were screwed onto the implants after the latter were inserted. The prepared baseplate was corrected accordingly, due to the greater than expected residual ridge atrophy (Fig 5-6c). The impression copings were integrated into the template with Pattern Resin (GC America)(Fig 5-6d). Once the baseplate was removed, cover screws were screwed onto the implants (Fig 5-6e). The mucoperiosteal flap was mobilized by periosteal slitting. This was followed by tight closure of the wound by suturing. The provisional restoration was prepared during the healing phase (see Note on the laboratory method on page 338).

Exposure with incorporation of the superstructure and gingival augmentation of the residual ridge

Very careful planning is needed for the exposure technique and the incision, especially in the anterior maxilla. The gum line over the future crowns is a key factor in the planning. The prosthesis teeth (without pink acrylic) show the buccal and labial course of the crowns (Fig 5-6f). In this case, all the implant penetration sites were located in the unattached mucosa of the buccal and labial vestibule. The exposure operation was used to gather more attached gingiva around the implants and to correct the mucosal situation.

On the palatal side of the implants, the incision extended only into the mucoepithelium. The epithelialized gingiva was dissected away from the connective tissue towards the palatal direction over a length of approximately 10 mm; this needs to be done without any perforations, if at all possible (split-flap technique). The periosteum was cut through at the end of the mucosal flap (approximately 10 mm palatally of the implants). The long flap extending toward the palatal direction had to be detached from the bone, working toward the labial and buccal vestibule (Fig 5-6g). Once the cover screws were removed, the prepared sterile inner crowns were screwed into place. The implant abutment lying furthest distally was screwed on first with the aid of the transfer (Fig 5-6h). The key could then be used to place the other abutments in any desired sequence. A method that has proved useful is to mark the components on the labial/buccal side so that they can be put into the correct order quickly during the procedure (Fig 5-6i). Once the screws were tightened, the provisional crowns were attached using a little TempBond with added Vaseline and the cement residues removed under visual control (Fig 5-6j).

Attention: When tightening the retaining screws, it is essential to stop the abutments from twisting to the right on their own axes. Even the slightest twist causes tension, the result being that the transfer can only be removed with difficulty and that the superstructure no longer fits.

On the buccal/labial side, the roll flap was adapted to the implant abutments and secured with sutures (roll flap technique; Fig 5-6k). When suturing, the thinned palatal mucosal flap also had to be securely adapted to the bone (Fig 5-6l). Solcoseryl dental adhesive paste was applied and a prepared thermoplastic foil with a palatal cover put into place to allow the tissues to heal undisturbed (Fig 5-6m). The postoperative panoramic radiograph shows the exact fit of the abutments on the implants (Fig 5-6n). The healing phase was uncomplicated (Fig 5-6o).

Prosthetic restoration

More prosthetic steps followed once the situation had stabilized after about 6 to 8 weeks. For the overall rehabilitation, the bridge 22 to 27 was first removed (Fig 5-6p) and the abutment teeth prepared again. This was followed by impression taking. In the laboratory, the split structure was fabricated on the overall cast. The tooth-supported components that were to be cemented on were fitted with attachments for external screw retention. The implant-retained portion was to be cemented on provisionally and screwed onto the rest of the restoration.

The dental bridge 22-24-26-28 and crown 18 were inserted first and retained with Harvard cement (Harvard Dental; Fig 5-6q). After the provisional cement retention, the implant-supported part of the restoration was secured to the external attachments between 21 to 22 and 17 to 18 (Fig 5-6r). Some atrophy of the slightly overcontoured attached gingiva in regions 14 to 21 also had to be taken into account (Fig 5-6s).

The overall fixed maxillary rehabilitation from 18 to 28 was performed satisfactorily even without any bone augmentation (such as sinus floor elevation and posterior residual ridge augmentation). Figure 5-6t shows the patient after the treatment.

Continued follow-up

The patient presented for a check-up 14 years after implant placement. A stable, virtually unchanged situation can be seen in the panoramic radiograph (Fig 5-6u). The fear expressed following incorporation of the restoration, namely that the roll flap on the buccal/labial side of the implants could degenerate, has not been realized even after many years (Fig 5-6v). The extent of the overcontoured attached gingiva, which has been preserved over the years, is particularly marked when compared to the course of the gingiva under the denture span in the molar region (Fig 5-6w). In the 14 years of use, there have been no complications, whether descent of the dental segment or damage to the screw-retained attachment (Fig 5-6x). The patient remains very satisfied with the outcome of the treatment and can laugh and smile freely at all times (Fig 5-6y).

Sinus floor elevation and lateral augmentation

Working under general anesthesia, the procedure began with removal of the bridge on teeth 23, 26 and 28. This was followed by the extraction of teeth 22 and 28. Tooth 16 had already been extracted on a prior occasion, to ensure an intact mucosal layer for coverage after the sinus floor elevation (Fig 5-8e). An incision was made along the palatal surfaces of the teeth with a releasing incision distally of tooth 21. The access window to the maxillary sinus was created cranially of the root apices of tooth 26, without damaging them (Fig 5-8f). The prolonged inflammation around tooth 22 had led to an extensive bone defect, making implant placement impossible without prior augmentation (Fig 5-8g). Both sinus elevation and lateral augmentation were performed with Bio-Oss (particle size 1 to 2 mm) and the harvested bone chips. A large Bio-Gide membrane (Geistlich) (30 × 40 mm) was divided into smaller fragments for the two windows and for lateral augmentation in region 22. These membrane fragments were attached with titanium pins (Fig 5-8h). After the periosteal slitting, the flap was mobilized in such a way as to provide tension-free coverage of the whole operation area. It was attached with Gore-Tex and Mopylen 6-0 sutures (W. L. Gore and Resorba, respectively) using the simple interrupted and mattress stitch techniques (Fig 5-8i). An immediate provisional was fabricated out of Protemp (3M ESPE) over the stumps of teeth 23 and 26 with the aid of thermoplastic foiland incorporated (Fig 5-8j).

Implant placement

After the sutures were removed, the short-term provisional was exchanged for a metal-reinforced, long-term provisional (Fig 5-8k). This provisional replaced teeth 22 and 24, where the implants were to be inserted. Two additional implants were planned in region 27 and one in region 36 (Fig 5-8l). Implant placement took place 10 months after augmentation. The single implant in region 16 was inserted first (Fig 5-8m). Further migration of tooth 15 toward a distal direction is apparent in the occlusal view; this was to be corrected orthodontically (see Figs 5-8e and 5-8m).

On the left side, the incision was made along the palatal surface of the teeth. The releasing incision was made at the height of former tooth 28 (Fig 5-8n). Lateral augmentation in region 22 had also been very successful, and hardly any resorption of the augmentation material was apparent (Fig 5-8o). During preparation of implant bed 22, the bone bed was widened slightly by bone spreading and a 3.5-mm wide Neoss implant was inserted (Fig 5-8p). Further implants were inserted with primary stability in regions 24, 27 and 28 (Fig 5-8q). The single-tooth implant 11 mm in length and 4.5 mm in diameter was then inserted in the region of tooth 36 (Fig 5-8r).

Exposure and orthodontic treatment

All the implants were exposed 1 year after insertion. The long-term provisional was still in use and was removed for the exposure (Fig 5-8s). The incision on the left side was shifted further palatally to widen the zone of keratinized gingiva. The cover screws were replaced with 5-mm high polyetheretherketone (PEEK) abutments and the flaps were adapted onto these (Fig 5-8t).

The long-term provisional needed to be adjusted to the new situation prior to incorporation (Fig 5-8u). On the right side, the gap between teeth 14 and 15 had grown because tooth 15 had migrated further distally. This condition needed to be corrected before the definitive restoration (Fig 5-8v). The large periodontal defect on the mesial surface of this tooth could have been a possible cause for the migration. In the exposure operation, the gingiva was reflected slightly more and this defect carefully cleansed by open curettage (Fig 5-8w). The surface of the root was mechanically cleaned and chemically decontaminated. The flap was fixed with Gore-Tex sutures without filling the defect (Fig 5-8x). The sutures were removed after 2 weeks (Fig 5-8y). After another 2 weeks, the healing abutment was replaced with a definitive titanium abutment, allowing the orthodontic straightening of tooth 15 to begin (Fig 5-8z). For the orthodontic treatment, a partial archwire on a ring was fitted around tooth 17, along with two brackets in regions 14 and 15. Abutment 16 was initially fitted with a provisional crown (Fig 5-8aa).

Ten weeks later, the orthodontic straightening of tooth 15 was completed, allowing the definitive prosthetic restoration to start (Fig 5-8bb). The orthodontic apparatus was removed for this purpose (Fig 5-8cc) and an impression taken for definitive crown 16 (with the prefabricated framework). Until the incorporation of the crown on the following day (Fig 5-8dd), the position of tooth 15 was maintained with a simple spacer. An impression of the left side was taken 3 weeks after the exposure (Fig 5-8ee). Zirconia abutments were fabricated on implants 22 and 24, and titanium ones on implants 27 and 28 (Fig 5-8ff).

The ceramic individual crowns baked onto the zirconia caps were cemented on after the abutment screws were tightened. Crown 36 was also definitively inserted (Fig 5-8gg). After the 2-year treatment, the patient is very satisfied with the final result (Fig 5-8hh).

Implant placement and augmentation

After the palatal ridge incision and the dissection of a mucoperiosteal flap, a small window was cut into the apical premolar region of the maxillary sinus (Fig 5-9c). The maxillary sinus mucosa was detached and the implant beds prepared (Fig 5-9d). The gradual augmentation of the sinus floor with a mixture of Bio-Oss, autologous bone and autologous blood took place alongside the insertion of four implants (Fig 5-9e). The implants were placed so that they protruded approximately 2 to 3 mm above bone level, so that they would offer vertical support to the bone augmentation. The higher cover screw on the canine implant was to act as a zone of support for the membrane, preferably in the titanium-reinforced region. The large titanium-reinforced Gore-Tex TR9W membrane was adjusted and attached on the apical side. The prepared mixture of Bio-Oss and bone was then packed under it (Fig 5-9f).

Following shaping of the residual ridge, the membrane was adapted over the ridge to the palatal side and attached with titanium pins (Fig 5-9g). The flap needed to be repositioned by periosteal slitting without any tension and without exerting any pressure on the augmented area, before the wound was tightly closed with mattress and simple interrupted sutures (Fig 5-9h). The height of the implants above bone level is apparent on the panoramic radiograph, taken directly after the operation (Fig 5-9i). Since the vertical augmentation was undertaken with bone substitutes, a healing period of at least 9 months was required.

Exposure and prosthetic restoration

As a result of the periosteal slitting and the displacement of the unattached mucosa in the coronal direction, there was no keratinized gingiva in the implant region (Fig 5-9j). For this zone to be reconstructed, connective tissue needed to be moved from the palate toward the vestibule. This was achieved with a combination of two methods: the split flap and the roll flap techniques (see pages 528 and 529). Following dissection of the flap, an access to the membrane and to the pins attaching it was created (Fig 5-9k). All the pins were taken out first to allow the membrane to be removed without tearing. To be on the safe side, the membrane was checked for intactness following removal.

The newly formed hard bone tissue had grown over all the cover screws apart from the supporting one, so that it had to be cut away to allow access to the implants (Fig 5-9l).

It had even been possible to reconstruct a bony support for the inter-implant papillae (Fig 5-9m). Healing abutments of reduced diameter were screwed onto the exposed implants to allow the mucosa to regenerate in the spaces between the implants (Fig 5-9n). The roll flap on the buccal/labial side needed to be tightly adapted to the abutments (Fig 5-9o).

The epithelial flap, which had been thinned out on the palatal side, was stabilized on the bone base with overlapping sutures (Fig 5-9p). The sutures were removed gradually over a period of 3 weeks (Fig 5-9q). The impression was taken after 5 to 6 weeks. Implant 22 was loaded with a CerAdapt (Nobel Biocare) abutment and an all-ceramic crown. Implants 23, 24 and 25 were loaded with the aid of the cast coping technique (Fig 5-9r). The follow-up radiograph (Fig 5-9s) shows good mineralization of the augmented bone compared to the baseline findings at the time of implant placement (see Fig 5-9i). Comparison of the intraoral images before and after the treatment makes it clear that not only the teeth, but also the residual ridge and the attached gingiva had been successfully restored (Figs 5-9t and 5-9u). The patient is very happy with this improvement (Fig 5-9v).

Continued follow-up

It is interesting to see how stable the treatment result remained after several years of functional use. The patient presented for a check-up after 13 years, and the clinical situation was documented at this point in time. The osseous situation appeared to be stable on the follow-up panoramic radiograph (Fig 5-9w). Implant 22, loaded with a ceramic individual crown, appears very natural in the overall view (Fig 5-9x).

The implant positioned furthest toward the labial vestibule also shows the highest degree of recession and the highest overall proportion of metal in its superstructure (Fig 5-9y). However, the patient’s upper lip is long enough to allow her to smile broadly without revealing any metal parts (Fig 5-9z). The patient is not bothered by the visible metal edges and is more than satisfied with the final result.

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