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 »  Home  »  Dental Implant 1  »  Advanced Alveolar Crest Atrophy: An Alternative Treatment Technique for Maxilla and Mandible
Advanced Alveolar Crest Atrophy: An Alternative Treatment Technique for Maxilla and Mandible
Case report.

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Rainer Bocklage, Dr. med. Dent.
DUI, Private Practice, Dormagen, Germany.

Dental implantology has undergone rapid development over the last few years. However, advanced alveolar crest atrophy remains a special challenge in oral implantology. A residual bone height #5 mm in the zones of the maxillary sinus and mandibular nerve, often combined with poor bone density, are the main problems of these implant cases. The conventional maxillofacial therapy consists of augmentation with bone grafting from either the hip, tibia, ribs, or chin in combination with root-form implants.1–4 Because these augmentation procedures require two independent invasive surgeries, which causes a rather long treatment period, another concept of treatment is presented.
With the lateral insertion technique and disk-design implants, the resorbed endentulous arch can be treated without bone grafting in a single surgery session (simultaneously: maxilla and mandible). The possibility of immediate implantation and immediate functional loading on these implants also shortens the procedure. Initial stability is achieved by anchoring the Diskimplants (Victory S.A., Nice, France) in the cortical bone areas. The transitional temporaries, as well as the definitive restorations, are always implantsupported fixed bridges. A clinical case demonstrates this concept of oral implantology.

A healthy 58-year-old woman requested an esthetic and permanent solution with fixed bridgework to replace her missing teeth. The panoramic radiograph revealed an extremely resorbed edentulous maxilla with a prominent sinus and a nearly edentulous mandible with advanced crest atrophy in the area of 46, 47. Scanora (Soredex, Helsinki, Finland) tomographic analysis revealed the anatomical structures in more detail: sinus, nasal fossa, conchae, alveolar and basal bone in the maxilla and mandibular nerve, mental foramen, and alveolar and basal bone in the mandible.
In the implant case presented, the maxillary arch offered very poor bone quantity and quality (type IV bone). In the mandible, excellent bone quality and quantity was noted between the foramina. A sufficient residual bone volume after extraction of teeth 36 and 37 was expected. Severe bone atrophy (thickness >4 mm) was found in the area of 47.

Implant Technique.
The method used for rehabilitation of the edentulous arches in this clinical case consisted of the placement of disk-design implants using the lateral insertion technique. The Diskimplants (Victory S.A.) used were designed in 1982 by Scortecci and further developed by him to the present standard. A turbine working at 60 psi is required. Used properly, there is neither overheating of the bone nor perforation of soft tissue. Laterally, a titanium cutter is used to drill from the outside cortical bone through the laminar bone of the arch to the inside cortical bone. This microsurgical procedure results in tricortical support of the implants. With a Monodiskimplant, the implantation bed is shaped like a T in the maxilla and like an upside-down T in the mandible.
At the beginning of the surgical procedure, a cutter with a diameter of 7 mm is used. The insertion diameter is enlarged in 1-mm steps by successive cutters until the desired implant diameter (maximum of 20 selected implant is impacted laterally into the bone with a surgical mallet and seating instrument. Due to precise microsurgical osteotomy, the initial stability of the disk-design implants is achieved. The implantation procedure is similar for double Diskimplants, which have two basal disks.

Surgical Procedure.
General remarks.
Treatment of such an extensive implant case must be performed under general anesthesia. Surgery on both the maxilla and mandible was performed in a single stage. Sinus elevations were performed on the right and left sinuses. 12 Because of the class IV bone in the maxilla and the small vertical space between the implantation site in area 47 and the mandibular nerve, a very accurate osteotomy was essential.
A local anesthetic (1% Xylocaine POR 8, Astra, Switzerland) was infiltrated in the maxillary surgical site in combination with a local nerve block anesthesia entering from the greater palatine canal. A horizontal incision was made on the crest with a releasing incision on the tuberosity. These incisions permitted optimal mobilization of the mucoperiosteal flap.
To combine sinus-lift and diskdesign implants to create loading zones anterior and posterior to the maxillary sinus in this class IV bone, the lateral wall of the maxilla was exposed completely. The sinus-lift procedure began with preparation of a bone window, followed by elevation of the Schneiderian membrane from the floor of the sinus. A fabricated surgical guide was then placed on the crest for better orientation.
Implant surgery using the previously described lateral osteotomy technique was then performed for insertion of five double Diskimplants. All implants were cortically anchored. Initial stability was excellent. Bone grafting to augment the volume of available bone would have been necessary for placement of root-form implants, but is not necessary with disk-design implants. Finally, the mucoperiosteal flap was repositioned, and the incisions were closed with interrupted nonresorbable sutures.
After mandibular block anesthesia on both sides, a horizontal incision was made on the crest with a releasing incision in the retromolar zones. Adequate mobilization of the mucoperiosteal flap was necessary to visualize the mental foramen and the mandibular nerve. The surgical implant placement procedure began in the intraforaminal crest area.
Bone density and the residual bone height in this particular area were usually excellent. Three diskdesign implants were placed using the osteotomy protocol described earlier. Initial stability of the cortically anchored Diskimplants was easily achieved. Teeth 36 and 37 were extracted, and immediate implantation was prepared. 16 After extraction of these teeth, a simple Diskimplant was inserted laterally into the interdentium septum.
The right lower arch indicated an advanced alveolar crest atrophy. The distance of 4 mm from the implant site to the mandible nerve is usually not sufficient for using screw or cylinder implants for a single-stage surgery procedure. Only by application of nerve transpositioning or bone grafting would the insertion of rootform implants have been possible. With disk-design implants, a successful implantation in this case was practical without bone grafting and nerve transpositioning.

Radiographs After Implant Surgery.
A panoramic radiograph 1 day after operation represents a simple overview of the implants that have been placed. With the Scanora radiograph technique, an efficient diagnosis concerning the bone-implant interface was possible. The Scanora images demonstrated tricortical or multicortical support of the disk-design implants in the cortical bone.
Naturally, an incorrect implant placement (diameter too small or wrong insertion direction) causes implant loss. Therefore, the tricortical support of disk-design implants is imperative. Tomographic images of the implants inserted revealed optimal application of this implant technique (Double Diskimplants: multicortical support. Simple Diskimplants: tricortical support).

Immediate Functional Loading of Diskimplants With Fixed Provisional Restorations.
A main element of this treatment concept is the fabrication of fixed metal-resin restorations for immediate functional loading on the implants 8 to 10 days after surgery. For immediate loading on implants, it was necessary to make impressions at the end of the operation period. First, an approximate determination of the vertical dimension with the impression copings on the implants was realized. Afterwards, the impressions were taken with Blueprint Cremix alginate (Dentsply, Konstanz, Germany) in both arches. An accurate replacement of the impression copings is recommended.
Finally, fabrication of the master models with the implant abutments was done according to conventional prosthodontic model techniques. The maxillary and mandibular master models can be fixed together in the articulator by the transference of the removable prostheses (which were already fabricated in the analysis period to serve as the patient’s template) and the bite impressions taken after setting the implants. A serious problem of large fixed implantsupported restorations is parallelism. Therefore, the abutments must be parallel. (During surgery the positioning of implants has to be strictly controlled.) The dental technician fabricates the metal framework and the occlusal surfaces with resin.
The following working rules must be observed by the dental technician:
  • Narrow occlusal table.
  • Disclusion in group function.
  • No prematurities during function.
  • Allow proper embrasure for maintenance.
Function, esthetics, and phonetics of these one-piece temporaries are to be accounted for. Bone loss in vertical height (large resorption of the maxilla in this implant case) always causes an elongation of the clinical crowns of the implant bridgework. This esthetic problem is solved with red-white esthetics. Eight days after surgery, the provisional bridges were placed on the implants with a temporary cement. Prematurities were eliminated immediately at chairtime. A weekly check of the cement-retained implant prostheses was necessary to observe vertical and horizontal forces on the temporaries. After another 40 days, the definitive implant restorations were realized according to conventional crown and bridge techniques.