Please activate JavaScript!
Please install Adobe Flash Player, click here for download
ePaper created 2016-04-19, 10:56:04 | version 1.38.0
treatment. The overall shape of the implant and its relation with other anatomic structures, including the graftedboneandthesofttissuewere all fleshed out and requested by the surgical team. One stipulation of the surgical team was to keep the previously grafted fibula. They considered it as a safety measure in eventofimplant’sfailure. The design solution One big challenge to carry out this particular project was to de- sign the implant in such a way that itcanbeeasilyseatedinthecorrect position. There were two major im- pediments to a one-piece implant solution. First of all, the implant was intended to be mounted over theremainingpartsofthepatient’s jaw, i.e. his two rami. To achieve the maximum anchorage from the rami, those parts of the implant connectingthemweresupposedto adapt to their external anatomy. Since the rami converge to the front, the same was expected from the corresponding implant design. However, such designing choice wouldhavemadethematterscom- plicated for surgical placement of the implant. What’s more, the fibrous tissues resulting from the previous surgeries have dramati- cally reduced the patient’s ability to open his mouth. Therefore, DRSK 3-D design team had to cross outtheone-pieceimplantsolution. Eventually by taking different lim- itations into account and after consulting with the surgical team andreceivingtheirendorsement,it wasdecidedtomaketheprosthesis in three pieces. Each of the two larger left and right segments of the implant was designed to be placed and screwed individually over the correspon- dingramus(Fig.3),whileatthefront they met and dovetailed into each other (Fig. 4). A third part then had to be placed over the two pieces at their interface, embrace both and hold them together securely (Figs. 5 & 6). This way the whole thing turned into a unified struc- ture. Excellent fit with 3-D designing The success of the proposed de- signwastoalargeextentrelianton obtaining an excellent fit for each piece. This is the reason why the roleof3-Ddesignandmanufacture was so essential in this procedure. The parts of the right and left sec- tions that meet the rami had to be exactly adapted to the form of their corresponding anatomic structures. Each of them had to be formed in such a way that can fold over the edges of the ramus and embrace it enough for a proper support. Using 3-D design as well guaranteed the perfect contacts between three pieces which other- wise might have been an area of concern for a design of this nature. Giventhenecessityforincluding a prosthetic solution and consider- ing the patient’s limited mouth opening,themostfeasiblesolution was to incorporate the artificial teeth into the structure of the mandibular implant. As described above, during the surgical proce- dure and after screwing left and right pieces over the rami, the two overlapping front ends of left and right parts were fully fixed in place by adding the middle segment. The idea for the final design was toincludetheartificialteethaspart of this middle section. However to eliminate the risk of any force or pressure that would have compromised the success of the surgery, a temporary or surgi- calmiddlepiecewasdesignedtobe placed over the left and right sec- tion at the surgical session (Fig. 5). The function of this piece was sim- plytoholdtwopiecesinplaceatthe front (Fig. 6) before being replaced with the prosthetic, permanent middle sections (Fig.7). The prosthodontic component On the surgical team’s recom- mendation, the mandibular denti- tion included in the design of the middle section only comprised ten teeth including incisors, canines andpremolarsonbothsides(Fig.7). Due to the size of third surgical piece and its function of uniting the other two sections, only in- cisors and canines are in contact with the interconnecting surface of the middle part. So when the middle prosthetic piece is seen in- dependently, the premolars look unsupported in the manner of a cantilever bridge. However, after insertion of this enfolding middle part over the overlapped arms of left and right pieces, the premolars become tightlyincontactwithleftandright sections;thispreventsanydestruc- tive lever function from taking place. Again such close contact has only been enabled by the accuracy of 3-D designing and the following 3-D print procedure. The particular design of arms of left and right pieces, which col- lectively form the body of the mandible, is also worthy of note. These arms feature a 90 degree twist in the approximate area of molars. In this way they can adopt to both the thinner posterior part which is anchored over the ramus and the frontal part that required a broader width for carrying the teeth. Such twist also offered a so- lution for the relative lack of space in the posterior part of the mouth. This curve can as well bolster the physical resistance of the mandi- bular implant to the mechanical pressures. 3-D printing As the designing procedure fin- ished, the designed implant had to be manufactured and delivered tothesurgicalteam.Allthreepieces were3-DprintedinTitaniumGrade5 using EBM technology. Also before installing the implant, patient’s facial skeleton needed to be repro- ducedinaplasticmaterial.Itwas3-D printedbymeansofSLStechnology. This replica was produced in order to give the surgeon a better idea of the surgical site and therefore facil- itatethesurgicalprocess. After the healing period, the time comes for insertion of the prosthetic component. At this stage the surgical middle part will be unscrewed and removed (Fig. 8) and the prosthetic middle section, carrying the teeth, will be inserted (Fig. 9) and fixed in place (Figs. 10 & 11). After checking the occlusion thepatient’sbiteistoberegistered. The sizes of the teeth have to be adjusted accordingly. As the next step, a layer of porcelain should be added to the teeth to finalise the prosthetic phase and thereby the treatment process. Summary In brief, the 3-D design has paved the way for devising unorthodox, novel surgical and prosthodontics solutions, as exemplified by the case presented in this article. Such alternative solutions could not be achieved through traditional tech- nology with the same level of accu- racy, which is essential for achieving thedesiredoutcome.The3-Ddesign- ing and 3-D printing therefore have infinitely widened the scope of maxillofacial surgeries by expand- ing and improving the potentials forcustomisation.Hence,itisnowof utmostimportanceformaxillofacial surgeonstogetfurtherfamiliarwith areasofapplicationoftheseempow- ering tools and learn about oppor- tunitiesforenlistingitsassistance. 21Dental Tribune United Kingdom Edition | 5/2015 TRENDS&APPLICATIONS Dr Saeid Kazemi is the CEO of DRSK, a Swedish company spe- cialised in im- plantology and 3-D services. He can be con- tacted at drsk@ drsk.com. AD Fig.11: Final prosthesis shown over the patient’s model. 11 DTUK0515_20-21_Kazemi 15.10.15 12:06 Seite 2 DTUK0515_20-21_Kazemi 15.10.1512:06 Seite 2