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ePaper created 2017-12-06, 12:03:50 | version 1.38.0
industry | Fig. 15 Fig. 14 Fig. 16 of the sagittal plane (Fig. 18) confirmed the position of the central incisor of the definitive prosthesis in re- lation to the alveolar ridge, highlighting that remov- able rehabilitation was the best choice in this case. Owing to bone resorption in the maxilla, typical of patients with a skeletal Class III malocclusion, it was necessary to place the anterior teeth further in order to provide a Class I ratio. The final result (Fig. 19) con- firmed the excellent aesthetics achieved in both the maxilla and the mandible and the harmonisation with the surrounding tissue. It can also be noted that choosing a higher and lower fixed-removable pros- thesis associated with proper assembly made it pos- sible to restore occlusion by creating an occlusal Class I. A fixed maxillary prosthesis would have re- sulted in the creation of a non-harmonious profile, owing to poor lip support and a retracted maxilla. Ad- ditionally, we would have created a very difficult area for the patient to clean; indeed, food residues would have easily accumulated in such an area. The insertion of a flange, however, allowed the restoration of a correct Class I profile with good support of perioral tissue and proper occlusion. Discussion Loss of teeth and, consequently, of the supportive tissue necessitates restoration with a prosthesis to restore masticatory function and satisfactory aes- thetics. Implantology, in this sense, has considerably expanded therapeutic possibilities by allowing fixed or removable prostheses based on the patient’s need.1, 20 Since in the pathogenesis of periodontitis, there is poor hygiene control, it is important to edu- cate the patient on following a good home hygiene routine and perhaps to propose a therapeutic solution for easy maintenance from a hygiene point of view.21 Preserving some roots and using them as anchor- age allows the reduction of treatment costs, and pro- vides a number of benefits. The maintenance of the periodontal ligament plays an important role in re- ducing maxillary resorption. In addition, the mainte- nance of proprioceptors and mechanoreceptors allows the masticatory system to safeguard the sensory feedback that regulates motor response. Sectioning the remaining teeth at the level of the gingival margins decreases the crown–root ratio, stabilises the tooth and improves the prognosis.22 Fig. 14: At the upper and lower arch level, peri-implant cuff height was evaluated and the low-profile OT Equator attachments were screwed on. Fig. 15: Maxillary cast bar with OT Equator attachments to anchor the definitive removable maxillary prosthesis. Fig. 16: Fixed prosthesis consisting of a double structure. Bone loss caused by periodontitis may not allow the insertion of implants in some sites. In order to overcome this disadvantage, a viable therapeutic possibility is the insertion of tilted implants as an alternative to complex regenerative surgeries, which are expensive and not immune to morbidity.23, 24 In fact, distal angled positioning allows the insertion of longer implants in areas with better bone quality, re- spects the noble structures (such as the inferior alveolar nerve or maxillary sinus) and reduces the cantilevers by better distributing occlusal forces.15, 16 The cantilever reduction is responsible for lower flex- ion of the load-bearing bar and less stress in the abut- ment–bar connective area.14 In order to design the cantilever measurement, it is important to evaluate the distribution of the implants in the arches. An anterior–posterior spread (AP spread) is defined as the distance between the line joining the distal edges of two rear implants with the centre of the more mesial implant. The AP spread is influenced by the shape of the arch: a triangular or elongated shape is associated with a favourable AP spread, while a square shape is unfavourable. A restoration on multi- ple implants to which a load is applied can be consid- ered a Class I lever, in which the extension of the pros- implants 4 2017 27