PROSTHETIC REHABILITATION WITH IMMEDIATE LOADING BY MEANS OF VIRTUAL DESIGNING AND COMPUTER ASSISTED SURGERY APPLIED TO A COMPLEX CASE

Numeri Uno, 22: 21-25, 2015

The purpose of this article is to show how, thanks to a completely digital work flow and integrated between the prosthetic and implant planning, it is possible to manage a complex clinical case in a predictable way. The 67 year old patient, in good general state of health, has lost numerous dental elements with adult chronic periodontitis with dental loss of attachment and mobility of the residual teeth. In the upper arch is present a fixed prosthetic rehabilitation on the residual natural teeth from 13 to 25 missing 16, 22, and 24. In the lower arch the persistence of natural teeth from 42 to 32 is highlighted, with the loss of the canines and of all the latero-posterior teeth elements of both sides and the presence of a partial removable prosthesis. In the lower arch is also evident a severe resorption of the distal alveolar crests of both sides with superficialization of the anatomic site of both of the lower alveolar nerves, more evident in the right hemi-mandible. Such situation contrasts with the presence of a well represented alveolar bone support at the lower incisors level which determines an important crestal profiles’ misalignment between the postero lateral and the anterior sectors. Once the periodontal treatment of scaling and root smoothing was performed, the patient expressed her willingness to face rehabilitation of the lower arch only, well aware of the need to also intervene on the upper arch as soon as possible, which now is in transition and maintenance therapy. Therefore a protocol to acquire data is executed, including the report of the intra and extra oral photos, the impressions for study models, a silicone for the report of the inter-maxillary relationships and a facial arch for the set up of an articulator with average values. This, in addition to the preliminary periodontal treatment mentioned previously. Once all the data are analized, it is decided to proceed with selective milling in order to level the occlusal plan to correct the Spee and Wilson curves, and to plan the lower arch surgery with the aid of computer assisted surgery.

The described procedure shows how it is possible to manage a complete digital process without interruptions between the Orthodontist and the Dental technician “computerized”, each of which observing the respective responsibility and competence areas. The use of an open system allows the exchange of project data between the different software modules (implant simulation, anatomical and prosthetic modelling) and the manufacture of models and surgical guides resulting from any CAD CAM technology or rapid prototyping. Especially the use of stereolitography, thanks to the possibility to use different materials with the same production system, allows the Laboratory to produce “in house” all the necessary components for the Patient’s rehabilitation (working models, surgical guides and temporaries), quickly and with contained production costs, allowing to use this technology also for mono-edentulism or partial edentulism clinical cases and not only for total rehabilitation.
In complex cases the advantages of the computer assisted procedures are further evident. Equal implant and prosthetic artefact success and survival percentages, it is clearly showed the possibility to carry out a more accurate diagnosis and planning and a strong reduction of surgery invasiveness, of post-operative pain, of chair-side time, of errors and orthodontist stress, with significant benefits for the patient.