The main objective during the solidarity of the plants is the need to obtain the liability of the connection. This objective admits a certain tolerance in that although enjoying the primary stability implants they are not yet integrated in this phase immediately following the insertion. In the first period, the bone retains its characteristic plasticity and under the action of moderate forces it undergoes positive stimulation in accordance with the laws of Roux and Wolff.
The osseointegration in the presence of small stimulations takes place even faster than it happens around an element in a state of mechanical stillness.
The welding operation is simple in the case of the presence of two plants. In fact two points can always be easily connected by a straight line.
By applying the clamp electrodes at an angle of 90 ° the bar is solidified without moving even during the Ti plastic phase.
It should be remembered in fact that during the application of the welding current that causes the transition from the Alpha form to the Beta form with the consequent return to the initial state, Titanium manifests a plasticity given by the removal of molecular bonds. This plasticity can be exploited to guide the adaptation of the bar to the abutments.
The positioning of the implants on the two jaws is based on the anatomy and consequently roughly on an arc of a circle. this geometrical arrangement complicates the adaptation maneuver of the bar that meets along the path the interference given by the implants following those to be welded.
The previous image (fig. 7-15) clearly shows the interference given by the huge number “3” which prevents the bar from being adapted to the number “2”. The approach by force of the number “2” leads to the transfer of a tensional state to the proximal interface of the bone with consequent lysis. In this regard it should be remembered that we must never bend the implants in order to favor the parallelism of the dies. The emerging abutment in monophasic implantology must be designed and constructed to allow isodromia for drilling without causing an increase in the stress state due to compressions due to mechanical bending maneuvers.
To solve the problem of interference we can therefore use the plastic phase of the Ti. We therefore observe the behavior of the bar with respect to the abutment as the angle of application of the clamp electrodes varies. As already mentioned, positioning at 90 ° does not produce movement. But by varying the angle we can get movements in our favor.
By varying the angle of application of the electrodes the bar in the sharpest 90 ° slope during the passage of current will spontaneously move along a circular arc until it again assumes a 90 ° position with respect to the electrodes. We have therefore achieved a stable displacement without causing tensions to the previously solidarized plants. Unfortunately the fact that the elements are arranged on an arc of a circle does not allow the execution of this single maneuver. In fact, there will certainly be interference from subsequent installations. Therefore a compensatory action is necessary to avoid this occurrence.
It is therefore necessary to model a paradoxical curve that moves away from the number “3” to be able to weld the “2” without interference. It is an action contrary to what would be done instinctively.
The combined action of the compensatory curves associated with that of the left hand during the Ti plastic phase allows us to solidify the individual implants with a monoblock bar along the entire arch.