impianti sottoperiostali alessandria

The Story

Bone atrophy: the dental implant challenge

Implant treatment in case of severe bone atrophy has always been a challenge and a gamble for surgeons.

Bone grafting
Traditional dental implants (defined as endosseous dental implants), involving the insertion of a screw into the bone thickness, were the only ones used for a long time and became the cornerstone of implantology.
Endosseous dental implants are still the most commonly used in non-complex cases, e.g. where there is no bone scarcity.
Where there is insufficient bone available for the insertion of a traditional dental implant, an intense use of regenerative practices has been carried out since the nineties.
However, bone regeneration has considerable contraindications, such as invasive surgeries, long recovery times and above all the uncertainty of the final result.
New implant techniques in the use of residual bone.

More recently we have tried to use the remaining bone from dental extraction in the best possible way using new instruments and implant techniques
These methods use short or inclined implants; an example of this type of technique is the zygomatic implant, where longer screws are used to fix them accurately to the cheekbones.
In any case, endosseous implants always need a substrate, which is necessary for their completion. 

In some very severe cases of atrophy, the surgeon must also calculate the biological cost that patients must pay, in addition to other factors, which often do not recommend treatment.

The juxta-osseous implant as a universal solution
The juxta-osseous implant represents a third treatment option, able to satisfy many conditions. Here is a detailed overview of this old method, revised and corrected from a modern perspective.

Working around the problem of bone atrophy

The problem of bone atrophy remained a complex issue to be resolved with endosseous implants; for this reason, thanks to the Eagle Grid patent, we have been able to deal with it from another point of view.
In fact, Eagle Grid consists of a NON-endosseous implant, which takes advantage of the deep support of a skeletal structure in the subgingival area, instead of expecting to integrate it into the bone.
This technique is taken into consideration for the resolution of severe vertical and transversal bone atrophy, where it is not possible to perform an endosseous implant and where regenerative therapy is not recommended.

The development of the Eagle Grid protocol

    The initial protocol included:

  1. the skeletonization of the bone segment in question, i.e. the detachment of the gum from its seat to allow exposure of the bone;
  2. the acquisition of the cast, which is the impression of the bone with the most hydrophilic materials possible, taking bleeding and the type of plaster into account;
  3. temporary generic suturing (while waiting for the laboratory to produce the lost wax casting metal structure. This used to be generally made in simple base alloy, or rather in Cobalt-base Alloy);
  4. generally within 12 hours, the grid was positioned in its definitive seat in the patient’s mouth, taking advantage of the precision anchorage with the bone while providing a minimum tolerance margin;
  5. Prosthesis with temporary resin teeth were anchored to the already pre-formed abutments of the juxta-osseous grid.

Success and failure of the procedure
The success of this procedure was unfortunately very uncertain, both in the short and in the long term: let’s try to understand why better.
Failure was determined by the start of the bone decubitus, actual bone gaps that often were affected by bacterial infection.
This inconvenience could cause enormous thinning which could also result in actual osteomyelitis, responsible for the removal of all or part of the grid structure.

Origin of the problems

    The causes of the failure of the procedure were mainly of two types:

  • Imprecision regarding the bone on which the structure was anchored. This imprecision given by the empiricism of the procedure meant the grid did not have stability nor uniform support. This could lead to micro-movements responsible for thinning under prosthetic loading.
  • Secondly, the quality of the underlying bone and its density was not always able to withstand the pressure generated by the anchoring surface of the structure. This is most common in some areas of the oral cavity, such as the maxilla or the mandibular lingual zone.

Minor damage
Damage was generated by the exposure of the structure in areas adjacent to the abutments but it was less severe; this event was often aseptic and could be solved with outpatient surgery.
A further problematic element was the engineering of the structure design that was often referred to the dental technician.
In addition to being ethically incorrect, it forced the dentist to make choices that were not agreed upon.
The prognosis could be improved if the grid was joined by a dental prosthesis or traditional endosseous implants.
Another critical factor was that the metal used could cause hypersensitivity or allergic reactions in patients subjected to chromatosis; which is a quite rare, often unpredictable, but not negligible event.

Use of titanium: the qualitative leap
A substantial improvement occurred when the metal was changed, switching to the use of titanium.
From a clinical point of view, this step has led to a noticeable improvement, even though it has created some drawbacks and difficulties for dental technicians.

Scientific publications relating to these applications had maximum consent until the beginning of 2000, after which the use of the juxta-osseous or subperiosteal implants was abandoned by most.