Raising of maxillary sinus for later rehabilitation with unitary crowns produced through CAD/CAM

AUTHORS: Prof. Rafael Cury Cecato Prof. Thiago Roberto Gemeli Prof. Stefani Guimarães

RECORD
64-year-old female patient.

COMPLAINT
Discomfort with the removable partial prosthesis and search for better aesthetics.

ANAMNESIS
Although a smoker, the patient was apt to undergo the surgical interventions for rehabilitation with implants.

PLANNING
Unitary cement-retained crowns over implants in the areas of teeth 25 and 26, and later reconstruction of tooth 26.

INTRODUCTION:
During the planning for the rehabilitation of the posterior area of the maxilla, it is not uncommon for the surgeon to face insufficient height of the residual border to anchor the dental implant1, making it inviable for the implantation without the previous reconstruction of the area.

In face of that need, the described technique to raise the maxillary sinus2,3,4 is considered safe and with a predictable prognostics for the reconstruction for the purpose of rehabilitation1. Also, what is important is to consider that the nature of bone grafting (autogenous or substitute) for filling seems not to have an influence in the success rate of the reconstruction5,6, allowing for considerable decrease in post-operative morbidity when avoiding the collection of the patient’s own bone.

Those reasons justify why this technique has been so widely recommended in the last decades as the chosen option for reconstruction in those areas, in case they show low height in the
alveolar border. When the planning includes unitary dental crowns, it is even more important that the bone support is mechanically compatible to the masticatory function.

The manufacture of prosthetic crowns by means of CAD/CAM systems (Computer Aided Design/Computer Aided Manufacturing) shows a precise and fast option to the professional7, since it allows for
the conclusion of the work not only optimized but also with adequate precision in the finish line8 and great adaptation between the internal surface of the crown and the intermediate piece. Although follow up studies still need to be carried out, such technology seems promising in the area of oral rehabilitation.

CASE REPORT

64-year-old patient, smoker, searched for help at a private clinic complaining about dental absence in the posterior area of the left side.

During anamnesis, the patient showed compatible health for the procedures proposed for the rehabilitation with dental implants and image and blood tests (hemogram, fasting glycemia and coagulogram) were requested. At the clinical exam, the absence of teeth 24, 25 and 26 was noticed, however, with prosthetic space for only one premolar and one molar (25 and 26). (Figures Initial and 01).

The blood tests did not show alterations; however, the images showed that the height of the border of the residual bone would be incompatible for the installation of regular length implants, more
specifically in the distal area (Fig. 02). The option for short implant (Short) was discarded due to the diminutive thickness of that area.

The planning consisted of reconstructing the border’s height by means of the technique for raising the maxillary sinus by lateral access, with filling of the sinus antrum with synthetic bone
substitute, composed by Hydroxyapatite (60%) and ß phosphate tricalcium (Nanosynt). One membrane of bovine cortical bone was used previously to the insertion of the bone granulate due to a
perforation in the Schneiderian membrane classified as class I9, occurred during its elevation (Figures 03 and 07). That maneuver is in accordance to what is suggested in the literature for that scenario, where the success rate is not decreased by such intercurrence10,11, if kept within the acceptable limits of control and remediation. No membrane in the lateral access to the antrum was used12.

The post-operative phase happened without intercurrences and around 06 months were waited for the implantation planning (Fig. 08), being 02 Arcsys Implants, one in the area of tooth 25 (Ø3.8X11mm)
and other in the area of tooth 26 (Ø4.3X11). Both obtained locking of 40N.cm and 30N.cm respectively, however, because the patient used partial removable prosthesis, the option was to bury them
instead of installing healing abutments (Fig. 09).

The reopening occurred 06 months later (Figures 10 and 11), in which two temporary crowns were placed on multifunctional healing abutments (5mm – high profile), beginning the pre peri-implantar
tissue conditioning and there they remained for 02 months (Figures 12 and 14). The quality of the mucous tissue conquered with the temporary crowns on the healing abutments was excellent and
corresponds to their biocompatibility (PEEK) (Fig. 15).

During the activation of the final components (a 4.2x6x2.5mm abutment for cement-retained restoration for element 25 and a 4.2x6x3.5mm one for element 26), it was noticed that the prosthetic component over the distal implant (tooth 26) could have a better positioning with a slight alteration of the direction, allowed by the capacity for customization of the angulation of the intermediate pieces of the Arcsys System (Figures 16 and 17). It was a seemingly small change but enough for potentiate the future aesthetic capacity of the future prosthetic crown. The intermediate pieces were then positioned and activated (Figures 18 and 19).

After activation, two other temporary crowns were placed over the respective Multifunctional Impression Caps returning to the patient the aesthetic and the function, in order to continue the tissue
conditioning (Figures 20 and 21).

For the transference molding of the components, together with the tissue form achieved with the conditioning, the Multifunctional Transfers were positioned and involved by a light-curing resinous
material (originally used for gingival protection) Top dam (FGM) (Figures 22 and 23). The peri-implantar health was confirmed with probing the area, confirming tissue stability (Figures 24 and 25).

The crowns were manufactured with blocks of cured composite for CAD/CAM Brava Block (FGM) (Fig. 26) and the cementation with Allcem Core (FGM) resinous cement was carefully done so that there
would be no overflowing to the peri-implantar tissues (extraoral overflow with the analog of the components). The occlusion was then adjusted and the final polishing was carried out with Diamond Pro sandpaper disks (FGM) and Diamond felt disks (FGM) with Diamond Excel polishing paste (FGM). There was an optimum combination of cost-benefit, mechanical resistance, aesthetics (Figures 27 and 28), excellent adaptation/fitting of the pieces and great response of the peri-implantar tissues (Fig. 29).

The conclusion was that the planning, the technique and the materials used are adequate for the excellent and predictable result for such recommendation.