With extensive experience in oral and orthognathic surgery, and intraoral and extraoral implant surgery, Dr. Enrico Agliardi has become well-known as a lucid voice of authority in his native Italy, as well as in the international arena. A respected author as well as an experienced clinician, Dr. Agliardi shares some of his insights concerning implant-based treatment in the following Questions and Answers.
In a situation of limited bone volume in the posterior maxilla due to sinus pneumatization, how would you replace a failing bridge/dentition or restore an edentulous area with a fixed restoration?
Dr. Enrico Agliardi:
In our practice we often see situations like the one depicted in Figure 1 and I think we may find this situation appearing more frequently in the near future. A three unit bridge is present in the right maxilla, replacing both premolars and the first molar, and both abutments have been compromised by periodontal disease.
A conventional approach might include a sinus augmentation with a lateral approach and delayed implant placement and loading, which would result in 12 to 18 months of treatment at high biological and economic costs to the patient. Furthermore, the use of a partial removable prosthesis to restore esthetics and function during the various phases of treatment may risk significant discomfort for the patient.
Fortunately, there is another solution available. I have concentrated the last 7 years of my practice on treating atrophic arches or segments with the use of axial and tilted implants to support fixed immediate restorations, avoiding pre-prosthetic surgery and extensive ridge reconstruction. One of the advantages in implant inclination is that we can place longer fixtures, engaging cortical areas in the mouth, thus increasing the primary stability of the implants.
In this case, after the reflection of the anterior part of the sinus membrane, the osteotomy is prepared with a 40 degree inclination from distal to mesial and an 18mm implant secures coronal anchorage in the residual ridge and apical anchorage in the anterior sinus wall. (Figures 2a and b.) One implant was placed axially in the extraction socket of the first premolar. Both implants reached 50 Newton of final torque, and a screw-retained bridge was delivered three hours afterwards.
This technique, called Trans-Sinus Tilted Implants (TSTI), allows the immediate rehabilitation of posterior segments of the maxilla with a fixed bridge supported by a posterior tilted fixture with an intra-sinus insertion and a conventional axial fixture. Preliminary results from a cohort of subjects treated in my private practice are very encouraging after as much as three years of follow-up (Figures 2b and 3).
When do you propose using the All-on-4® treatment concept as the first choice of treatment ?
Dr. Enrico Agliardi:
In cases similar to this one: the patient here was referred to my practice because she wanted a fixed solution for the rehabilitation of the lower jaw (Figure 4) avoiding 2-stage augmentation procedures and a long treatment time. The use of an improper removable prosthesis has created a severe bone resorption, resulting in a superficial path of the alveolar canal over the years. Since the patient declined any kind of vertical bone augmentation, the only available bone remained in the interforaminal region.
The conebeam-scan verified a narrow interforaminal alveolar process with an hourglass shape. A thorough treatment plan with NobelClinician showed once more that the placement of regular platform implants would be challenging (Figure 5). A consistent surgical bone reduction was necessary until the minimum 5 mm width was obtained. Four implants were placed in the basal bone according to the All-on-4® treatment concept protocol (Figure 6) and an immediate prosthesis was delivered after 3 hours (Figure 7). The post-op OPG indicated implant distribution very similar to the surgical simulation (Figure 8).