Patient: 59 y.o., non-smoker, not suffering from any remarkable systemic disease
The patient referred to us with an upper temporary bridge anchored on 3 roots, the maxillary right lateral central and left canine, and on one dental implant at the left first premolar.
Furthermore, the patient had two other implants at teeth right maxillary premolars with fractured prosthetic connections that were no longer exploitable.
Dental roots exhibited a degree 3 mobility and the implant at maxillary first premolar showed a 4/5 mm horizontal bone resorption with previous abscesses.
Severe bone atrophy in the posterior areas was identified.
Treatment plan
The treatment plan provided for the patient to undergo guided surgery with traditional implants in the anterior areas and 2 free-hand zygomatic implants in the posterior areas, with a total amount of 12 unit immediately-loaded prosthesis.
Data collection
The first step of the treatment plan is the impression-taking of the surgical area, of its antagonist and of the bite block with an intraoral scanner.
Then, facial scans are taken. These latter scans may prove useful as STL files and as a preoperative iconographic documentation.
In the next stage the patient goes for a CBCT examination with stent in place. This extraoral geometry is necessary to realign DICOM files of CBCT with STL files of facial and intraoral scans.
Afterwards, condylar movements are recorded using prosystom software.
This recording collects right and left side condylar movements as well as opening and closing condylar movements that are detected separately and within a full masticatory pattern. Data are subsequently exported into a format readable for the Exocad modelling software.
Intraoral scan files, facial scan files, CBCT files and axiography files are matched inside the software for fabricating a patient-calibrated individual diagnostic wax-up.
The patient-calibrated individual diagnostic wax-up matched with CBCT files (pic. 8) enables us to determine the most suitable implant position by analyzing the quality and quantity of bone in relation to the future teeth position.
This approach is defined as prosthetically-guided surgery, which makes it possible to have a temporary restoration fitting the patient’s masticatory pattern ahead of surgery.
The implants of traditional length in the premaxilla area are virtually placed using the software
and then a 3D-printed surgical guide is manufactured to guide drills and implants into the selected site. As for the zygomatic implants that will be placed free-handed, they are digitally studied as well with prosthetic emergence underneath the first molar teeth.
Surgical intervention
After an infiltration using articaine with adrenaline at 1:100.000, the dental maxillary remaining root, the implants with broken collar at the right maxilla and the implant with peri-implantitis at the left maxilla are removed. Accurate socket cleaning is then performed.
The surgical guide is positioned into the mouth through silicone surgical index and fixed to the upper jaw using positioning pins
The first drill is a mucotome resecting the portion of mucosa in the area where the following drill sequence will make the new socket.
Then the predetermined drilling length is reached after several drilling steps advancing millimetre by millimetre. The newly-created socket is bored by the drills to define its diameter.
The drill sequence shall be strictly followed to achieve a predictable outcome.
Guided surgery as such requires that every single passage is guided by the sleeves where indexed drills have an unequivocal 3D position and a stopper for the cutting part. Furthermore, the implant shall be inserted through the same sleeves without removing the guide.
Implants are picked from the blister-pack using the carrier that is screwed to the implant and works as a guide inside the sleeve.
Once the implant is placed in the new socket, it is held in place by the carrier, thus stabilizing the surgical guide.
After placing all the implants by means of the related carriers and achieving the minimum requested torque for immediate loading, the guide is removed.
For the insertion of zygomatic implants, a mini-invasive access with a 5 mm palatal to the ridge crest incision and some vestibular releasing incisions in the areas of right premolar to second molar and left maxillary premolars are made. Afterwards, the skeletonization of the upper jaw and the exposition of the lateral wall of the maxillary sinus, of the infraorbital nerve and of the body of the zygoma (until detecting the anterior margin of the tendon of the masseter muscle) are performed. By detecting the position of the first molar on each side of the maxillary crest, it is coherently determined the ideal path of the two zygomatic implants. Along the ideal path of the implant, an osteotomy of the lateral wall of the maxillary sinus is performed using a diamond ball burr that enables a reduced detachment of the Schneider membrane. A further osteotomy of the lateral wall is made using a tapered diamond burr;
this latter defines the natural seat of the drill for the final osteotomy.
After defining the new implant socket, the zygomatic implant is placed in compliance with the prosthetic plan. Following a thorough haemostatic control, the mucosa flaps are sutured.
All the inserted implants achieved an insertion torque allowing for immediate loading.
The temporary restoration is bonded using metal-to-metal cement.
