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ePaper created 2017-03-17, 12:34:42 | version 1.38.0
industry | ence is the kind of maintenance to be done. The milled bars and counter-bars are more complex but they do not need the replacement of the retentive attachments. The use of an implant-supported prosthesis in the jaw can be considered a feasible option for the treatment of those patients that re- quire clinical advantages similar to those of a fixed prosthesis but which also require the advantages of a removable denture.15 For the jaw it can be con- cluded that bone resorption, patient satisfaction and prosthetic complications are independent of the number of implants. This shows that it is not possible to establish any- thing that is the optimal number of implants for an implant-supported overdenture.16 In addition, using implants in the lower jaw and using a conventional prosthesis in the upper jaw will likely encounter a full success. Not only the implants in the mandible have a higher success rate compared to those in the upper jaw, but also using a conventional upper prosthesis will decrease the stress that the implant prosthesis is subject to. Conclusion In the rehabilitation of edentulous patients we have no clinical parameters that can guide us during the treatment as we have in fixed prosthesis (Figs. 9a & b). Once positioned the front group and thereby established aesthetic and phonetic param- eters of the patient, a pivotal role on the choice of the type of rehabilitation is played by the vertical dimension or, better, the available space between the arches. According to some authors, the thera- peutic possibilities and the optimal type of pros- thetic restoration is related to the distance between the maxillary and the mandibular arch; this pro- poses a classification, which considers the available vertical size for the rehabilitation, defined as the distance between the mucosa and the incisal/oc- clusal edge of the tooth properly positioned (pros- thetic space).17 These parameters, which are often ignored during the diagnostic phase, are the key to determine suc- cess of both aesthetic and functional rehabilitation. In cases where there is a large prosthetic space (class 1 more or equal to 15 mm) available, choosing a traditional fixed prosthesis would lead to unpleas- ant aesthetics, i. e. long teeth and lack of lip support giving an aged expression to the patient’s face. On the other hand, with a reduced prosthetic space (class 4, less than 7 mm of prosthetic space) opting for a hybrid prosthesis or an overdenture, we would not have enough space to insert the components, resulting in an alteration of the correct vertical di- mension or misplacement of the occlusal plane. Fig. 10 According to this, the diagnostic phase becomes the most important step in which the implant posi- tion is determined as well as the resulting kind of an- chorage. It may be useful to choose between two methods: 1. Detection of the impressions for the preliminary models and the mounting in the articulator with the occlusal rims. The latter will also provide the smile line and the occlusal plane parallel to the Camper plane. 2. Using the existing dentures it should be analysed, if the vertical dimension and the smile line are cor- rect; using the Gutowsky caliper, the distance be- tween the occlusal plane and gum from the inside of the reconstructions should also be measured (Fig. 10). It is therefore clear that the initial diagnostic pro- cess is essential to prevent complications during treatment._ Fig. 9a: The correct detection of the intermaxillary relationship is one of the decisive factors for maintaining the implants’ and prosthesis’ stability. Fig. 9b: The detection of the centric relation can be established with two methods: First, operator- dependent, where the clinician guides the mandible in centric position; second, non-operator-dependent, where the patient performs limited movements and thereby determines the centric position. Fig. 10: The space available between the arches is defined by the distance of mucosa and incisal/occlusal edge of the teeth once properly positioned. Literature Author details c o n t a c t Dr Ugo Torquati Gritti Via Pietro Lissoni 4 20832 Desio (MB), Italy Tel.: +39 0362 302102 ugotorquatigritti@gmail.com implants 1 2017 35