All on 4 is a wonderful technique, but it is very difficult to perform due to access either under GA or even under local, where the posterior abutments must be fitted in a very limited space. A head light is essential, as is a pressure free clinical environment free from patient expectations of "a same day technique". As with all implant planning, a fall back position is required: 3 stable implants and one "failed" is always a possibility, so that reality must be planned...... the taking of VD, centric, mid-line, smile line, anterior 'setup' must also be prepared at one or 2 postop sessions and really, to tout All on 4 as a "one day technique" is falsely
applying an operator derivative and driven pressure... the time line and delivery does not have to be so tight.. I prefer to place the implants on say a Monday, then try-in on a Wednesday and then provisional insertion on a Friday. Some of my cardiac learning experiences are to remove the handle from the delicate thread of the angulated abutments once immediately removed from the packet for 2 reasons: firstly the handle can bend the threads for the set screw during manipulation to seat the abutment and secondly, the handle can obstruct the passage of the abutment screw, as it needs to be half unscrewed prior to the seating of the abutment screw into the fixture, thus exposing it or the protective cap to possible cross threading. I always apply some Silicone lubricant, yet it is a vexing problem if the patient swallows at that delicate moment or one's glove twirls around the driver! All on 4 is a demanding yet wonderful technique not for the beginner and not for the less than nimble fingered! An additional problem is torquing the abutment screw to 20 Ncm: such a pressure can move the new fixture out of occlusal alignment, a fortuitous 1/4 turn can place the access hole to the more easily accessible buccal, yet if it is more than that, one is faced with either backing out the fixture 3/4 turn or tightening further... but with what? - the abutment screw to more than 20 Ncm? Sometimes a long driver of 12 inches would be grand to deflect the lip and allow more access to one's large hand rather than the saliva coated (little) fingers, fighting the Lock Ness tongue in the shadow of a dim ceiling light? I applaud All on 4, yet it is a VERY demanding technique and best not matched with a simultaneous maxillary and mandibular syn: if one landmark is removed, two implants loose, the dentures to modify, a fall back solution delayed.. yuk.. one at a time for less stomach lining and heart muscle loss.. self inflicted due only to marketing and the patient's expectation based upon a guilt harbored over 30 years of cognoscente neglect! One jaw at a time.. be warned that the patient's neglect has taken 30 years and it is only the Jungian "nurse archetype" of the operator that capitulates to their "abracadabra" desire for an instantaneous solution.
Take your time and don't offer a quick solution because All on 4 is grand, difficult and demanding when the fall back position is demanded by the oseeo-biology. My experience with Novum was wonderful in that the failed implant could be replaced EXACTLY where the structure required: All on 4 often requires a new improved, or better position for a failed fixture, thus a new impression and new super structure AT THE PROVIDER'S COST. "Teeth in an Hour", "Teeth in a Day" is marketing hype designed to sell product and ungenerously bite the COMPLIANT AND CONSUMER DRIVEN provider in "the bum". We all enjoy the immediate rewards of instant dental restitution, yet who needs the stress and the hassle of a broken promise for a sudden release from infected /broken/loose /neglected/over-erupted/
endodontically
questionable sites? Tranquillo and experience will give All on 4 its just position as a difficult, yet wonderful technique in the hands of the gifted,hesitant and cautious practitioner. All on 4 sets the benchmark for all dentistry: why spend more than the fee for All on 4 on multiple crowns or even multiple implants when a simple acrylic renewable structure can be hung off not 12, not 8, not the reliable 6, but a simple 4 fixtures? If I had a stroke and was languishing in a terminal facility, incubating bacteria, give me All on 4, but slowly. A shorten dental arch.. Yes. A lower fee ... Yes, but don't compress the time, for I can create that dimension.