Aesthetic implant rehabilitation in the posterior maxillary region: a clinical case with significant osseous loss 8 June 2016
Aesthetic implant rehabilitation in the posterior maxillary region: a clinical case with significant osseous loss
The aesthetics of the smile do not necessarily stop distally of the second premolars, but, in some cases, may involve the first or second molars in patients who have a generous smile. Thus, handling of the temporisation becomes essential in the maxillary posterior regions.
In this clinical case, we expose an example of temporisation in a context of significant bone loss in association with a sinus floor elevation and guided bone regeneration.
Ms. T. consults for an inelegant gingival recession with dental mobility on sector 1. The patient does not have any health problems contra-indicating implant therapy. She smokes occasionally.
At the exobuccal examination, the patient shows a wide gingival smile displaying the first molars. The side view of the smile reveals unsightly gingival level at the second premolar (Fig 1a and b).
Figures 1a and b: The continuity of the gingival smile is interrupted at 15. It will be necessary to rebuild the extension of the gum line for a harmonious smile.
The oral examination immediately reveals a significant gingival recession on 15 and an almost complete root denudation on 17. The teeth are maintained by a dental bridge from 13 to 17 (Fig 2).
Figure 2: The terminal attachment losses on 15 and 17 have induced a collapse of the keratinized tissue. The colorimetry of the adjacent teeth directs us to ceramic prosthetic reconstructions while excluding any metal frame.
Despite the absence of 36, the occlusion at maximal intercuspation is stable and the occlusion is adjusted in group function. The vertical dimension of occlusion is satisfactory.
The patient's oral hygiene must improve.
The panoramic X-ray confirms the attachment loss observed clinically by terminal osteolysis on 15 and 17, and an insufficient endodontic treatment of 17 which leads us to the diagnosis of endo-periodontal lesions; 15 and 17 must be extracted (Fig. 3 a).
Figure 3a: the post on 13 seems too short. 26 and 46 display a periapical inflammatory lesion of endodontic origin.
The volume cone beam CT (CBCT) shows a sufficient bone quality and quantity in both height and width to have an implant in sector 14 (Fig 3b and c).
Figure 3b and c: At once, we observe a usable bone level for a fixed temporisation with a provisional implant in palatal of the alveoli 15. Bone loss at 15 and 17 require a three-dimensional skeletal reconstruction for implant insertion.
First, we proceeded to extract teeth 15 and 17 and then carried out immediate placement of a conventional implant instead of tooth 14 and a temporary implant instead of tooth 15 to support an immediate temporisation like the three unit cantilever bridge with an extension on tooth 16.
Second, within a 3-month healing time, we would conduct a sinus floor elevation using the lateral approach, an implant placement on teeth 16 and 17, and a simultaneous guided bone regeneration.
The proposed prosthetic reconstruction would consist in the realisation of a ceramic screw-retained bridge with a zirconia framework.
A- The first stage: immediate extractions, implant placement and temporisation.
After separation of the bridge at the distal end of the canine, we proceed with the extraction of teeth 15 and 17. A thorough curettage of the alveoli is carried out and the granulation tissue is removed. We rinse well with iodised polyvidone to complete the decontamination process. A crestal and then intrasulcular incision in the mesial area aids lifting of the flap and the final implant instead of tooth 14 is put in place. A second temporary implant (IPI, Immediate Provisional Implant, Nobel Biocare) is then placed in the palatal aspect of the alveoli in tooth 15. The tightening torque of 35 Ncm of the two implants ensures sufficient primary stability for an immediate loading in the aesthetic zone. This involves the placement of a temporary cantilever bridge on teeth 14, 15 and 16. This temporary bridge is not in contact in the occlusion at maximal intercuspation, presenting an absence of posterior and anterior guidance; the patient should avoid chewing on that side for 2 months (Fig. 4a-c).
Figure 4a to c: The temporary implant (2.5*13mm) is offset in the palatal aspect in relation to the 4*13mm RP Nobel Speedy implant (Nobel Biocare) in 14. The three unit temporary bridge with an extension on 16 is screwed onto the implant on 14 and sealed on the provisional implant on 15.
B- The second stage: sinus lift and regeneration.
A mucoperiosteal flap is lifted thanks to a crestal incision followed by a vestibular release incision in the distal zone of 14 and, finally, an intracrevicular incision in the vestibular zone of 18. In order for the vestibular wall of the alveolar bone and the tip of the malar bone to be exposed sufficiently, an appropriate separation of the flap is necessary. A bone window is made using a round bur handpiece and piezoelectric inserts. The Schneiderian membrane of the maxillary sinus is peeled off with precaution starting anteriorly, then medially, and finally posteriorly towards 18. No tearing of the membrane is observed and the antral artery is dissected and cauterized using a bipolar electrosurgery unit (Fig. 5a-c). The sinus floor is filled with hydroxyapatite crystals of bovine origin (Bio-Oss® fine grain (Geistlich)) and implant placement in 16 and 17 with a final tightening torque of 35 Ncm are carried out. The entire area is coated with a mixed Bio-Oss of crushed autogenous bone from the bone window in order to increase the height and thickness of the osseous volume. In order to protect it, a Gore-Tex TR6Y non-resorbable membrane with titanium framework is used which is preformed on the relief of the area to cover the implant and the vestibular window.
.A nail is then used to press this membrane into the disto-vestibular area and a Gore-Tex suture thread in the palatal aspect is used (Fig. 5d-f). Then the hole is covered with a collagen membrane (Bio-Gide ®, Geistlich) to promote bone healing and reduce the risks from exposure. The flap is repositioned and hermetically sutured with resorbable 4/0 and 6/0 Velasorb threads (PPI Pharma) after giving it sufficient elasticity for a suture without tension.
Figure 5a to c: In the course of the operation, the antral artery is localised and left attached. The cauterization with a bipolar surgical knife (KLS Martin, IPP Pharma ) stops the bleeding locally.
Figure 5d to f: The increase in height and thickness by means of the GBR ensures the implants are ideally placed in the buccal corridor. The RP 4*13 mm Nobel Speedy Groovy implants (Nobel Biocare) in 16 and 17 are buried for eight months.
The patient is seen again after 15 days for suture removal and 6 weeks after for a check-up. The removal of the membrane and the functional loading are performed after 8 months. We then observe the vertical and horizontal bone gain obtained through guided bone regeneration. The healing abutments are put in place and the edges are closed (Fig. 6a to c).
Figure 6a to c: The objective is reached. The resulting bone volume surrounds the implants and creates a positively functional and aesthetic environment for the end result.
Before starting the prosthetic stage, we note a lack of gingival volume at the bridge pontic. Therefore, we decide to improve the environment by adding tissue using the buried connective tissue graft technique with a retro-tuberosity graft (Fig. 7a to d).
Figure 7a to d: The palatal position of the provisional implant allows easy manipulation of soft tissue during these stages. The integration of the connective tissue graft from the tuberosity, which is dense in fibres, is complete.
After healing and maturation of the mucosa, the impression of the implant is made using the pick-up technique and a plaster core with zero expansion requested from the prosthesist. Once the patient has tried it out, the impression is validated.
Proper positioning and alignment of the implant allows for a direct screw-retained connection for the bridgework. The zirconia framework made using CAD/CAM and the NobelProcera system is chosen which combines mechanical strength, biocompatibility and aesthetics.
The framework is designed by homothetic reduction of the final restoration to ensure optimal support of the veneering ceramic and limit the risks of chipping. After validation of the latter, the hue is taken and an impression, this time with the framework, is carried out to record the shape of the soft tissue and optimize the emergence profiles of the final restoration.
When fitting the bridge, after checking the adaptation, occlusion, contact points and hue, on the front view, we note a lack of convexity of the vestibular surfaces. This is corrected with liquid composite to provide the prosthesist with the necessary information. Once these changes have been made, the restoration is put in place with a screw tightening torque of 35 Ncm and the sockets are closed with a composite. To perfect the smile, the canine prosthesis is redone (Fig. 8a to e).
Figure 8a to e: The distribution of the implants allows for the construction of a prosthetic framework with gingival embrasures facilitating daily maintenance by the patient. The centering of the sockets of the prosthetic screws respects the cusp-pit ratio necessary for the stability of the occlusion - Prosthesis by Dr. Pierre Cherfane.
Monitoring at 5 years shows excellent aesthetic, biological and functional integration of the restoration and a perfectly satisfied patient (Fig. 9a and b).
Figures 9a and b: The cervical convexity of 15, the shape of the gingival embrasures, and the position of the contact points have contributed to the removal of the keratinized tissue for a harmonious smile line.
Discussion and conclusion
For this case, the immediate loading in the aesthetic zone with a temporary bridge with a molar extension presented a high risk of failure. Its implementation was only possible thanks to the perfect adherence of the patient to the treatment and advice.
The use of a temporary implant was the only possibility for a fixed temporisation from the extraction of non-retainable teeth and in the absence of any posterior dental abutment.
When placing the two most distal implants, it would have been possible to achieve a loading with a bridge based on three conventional implants due to the good primary stability achieved. However, this option would have prevented the guided bone regeneration with a non-resorbable membrane, with adverse consequences on bone integration, the mucosal contour and the aesthetic finish required by the patient.
In conclusion, we can say that the quality of the final aesthetic outcome of implant restoration depends on the quality of the thought process before the treatment and, therefore, the initial treatment implemented with the help of the acquisition of good clinical and radiographic elements. With this clinical case, one can easily see that the pink and white aesthetics are absolutely crucial in the final result of the restoration. Indeed, carrying out a guided bone regeneration in combination with a sinus lift coronally and horizontally increase the osseous and gingival level and, therefore, reduce the height of the clinical crowns while restoring harmonious proportions to the final restorations. Finally, the reconstruction of the interdental papillae is resolved by adding connective tissue from the tuberosity and by leaving necessary maturation time for the zirconia reconstructions.
Key words: dental implant, sinus graft, guided bone regeneration, immediate loading in the aesthetic zone, provisional implant, connective tissue graft
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Hôpital universitaire Pitié-Salpêtrière
Private practice limited to Periodontology and Implantology
Paris, Founder of the IFCIA Institute.