It’s impossible to argue with the clinical efficacy of Dr. Paolo Malo’s “all-on-4”. He has truly had an enormous effect on implant dentistry, many other clinicians have modified His technique according to clinical situations.
The following case demonstrates two surgical modifications since we plan to reconstruct the maxillary arch with 14 units and want to avoid using cantilevering.
This is achieved by elevation the maxillary sinuses in the 1st molar site using intra-crestal lift technique since we have more than 4mm of residual bone and also by placing implants in the Pterygo maxillary region which are commonly referred to as Pterygoids.
47 year old healthy female presents to LIT Institute with failing maxillary fixed bridges cemented 20 years ago.
Clinical view shows that the existent prosthesis was well designed fabricated following Antle’s law
Digital panoramic view reveals broken abutments
Upon removal of the 8 unit segment, we observe complete destruction of the natural abutments. At this conjecture is clear that we must remove all maxillary teeth and place sufficient implants to support a 14 unit fixed prosthesis
Using a CBCT (Carestream 8100, USA) we are able to obtain 2D images that are converted into a 3D working model via conversion of advanced algorithms.
In this frontal 3D image we are able to confirm what we observed clinically, the poor condition of natural abutments and need for full arch extractions.
Lateral left 3D image reveals periapical pathology on several teeth as well as site were implants can be placed in the anterior and posterior region.
3D plan will consist of:
B… implants in the pterygo maxillary region
C…and implants in the 1st molar region by means of intracrestal sinus lifts.
Full muco-periosteal flap from 2nd molar to 2nd molar, autraumatic surgical extractions is achieved and care to preserve the thin buccal bone.
A large bone acrylic bur is used at 35,000 RPM under copious irrigation to plasty the entire ridge and achieve a flat working platform which is essential for placement of RP implants and also creates height for prosthetic components.
Maxillary sinus is identified and outlined with a sterile #2 pencil.
A bone caliper is used to draw a line that will be parallel to the anterior-ascending part of antrum.
This line will guide the placement of the most posterior implant as indicated by Dr. Paolo Malo.
The sinus is outlined posteriorly and a second line is drawn to indicate the placement of a Pterygoid implant.
Orientation of Pterygoids: start at site of ML of the 2nd molar, at 30=45* drilling through the tuberosity and engaging the Lateral Pterygoid plate. This is strictly reserved for advanced doctors that have placed 300+ fixtures.
3D rendering of “all-on-4”, placement in 1st molar via crestal lift and Pterygoid implants.
Six guides pins confirm that the orientation and spacing for the “all-on-4” and for the Pterygoid fixtures are correct.
X-ray verification demonstrate how we have avoided to perforate the maxillary sinuses in an anterior and posterior relation.
Pterygoid implants are inserted manually. This site is always D3-D4 and as such allows for under-preparation of the site by 1-2 drills.
Implant anterior to the maxillary sinus (TUFF series by Noris Medical System, Israel). This self-tapping, aggressive thread design is selected due to its bio-mechanical characteristics.
Initiation of intra-crestal sinus elevation: start with stopper 1mm less than the height of the sinus from the ridge.
Use sinus probe with stopper. Look for one of 3 signs to confirm reaching the sinus membrane.
A…Tactile sense will feel smooth, rubbery or spongy
B…while drilling you might feel a drop
C…patient might feel pain
Once you have confirmed reaching the sinus membrane, begin adding bone particles until site is filled to the crest, proceed to condense site using the instrument and stopper, repeat this step 3-5 times.
What appeared to be an atrophic ridge resulted in a modified “all-on-4” with 4 additional posterior fixtures.
Lets compare our 3D planning with actual free-handed surgery.
Post-op ct-scan demonstrating the clinical advantages from planning a case using 3D models.
The “all-on-4” would had yield a 10 unit prosthesis to occlude with 2nd pre-molars, the addition of Pterygoids allows for incorporating 4 extra molars with
Post-op scan of final surgery, note how every mm of available residual bone has been utilized.
While this might appear to be a “restorative nightmare” due to crazy angulations, is not !
Noris Medical System has 0*, !7*, 30*, 45* and 60 * multi-unit abutments that will allow a screw retained prosthesis with less than 10* divergency.
Soft tissue management cannot be overlooked, mastering suturing techniques is paramount in the healing process.