Page 50 - Impact of implant retained overdenture treatment and speech, oromyofunction, social participation and quality of life.

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Chapter 2
A cone beam computed tomography (CBCT) scan including gutta percha markers provided the correct implant positioning. The markers were placed 18 to 22 mm apart and as parallel to the hinge axis in the canine positions of the mandibular denture. Before placement of the two implants, the CBCT scan with the marked mandibular prosthesis provided information about the bone quantity in the interforaminal region of the mandible. Furthermore it allowed correct angulation of the implants in the bone as to guarantee an axial loading of the denture as well as a perfect location of the future bar within the normal dimensions of the denture. The two implants were placed under local anaesthesia by an experienced surgeon in a one-stage surgical procedure, with appropriate initial stability and clinically parallel in frontal view. Immediately after surgery, healing abutments were placed slightly above mucosal level and the internal surface of the mandibular denture was relieved to provide space for a resilient liner (COE SOFT; GC America Inc.; Illinois, U.S.A.). Antibiotics and analgesics were administrated immediately after surgery. After one week, sutures were removed and the denture base was adjusted whenever required for pain relief or pressure points. The participants were checked after one and two months. Intermediate check-ups were possible on request by the patient in case of discomfort. After a 3-month healing period, a pick-up impression technique in maximal occlusion with a light-body polyether impression material (Permadyne Polyether Impression Material; 3M ESPE; Saint Paul MN, U.S.A.) and the appropriate impression posts (Southern Implants Inc, Irene, South Africa) was made with the existing mandibular denture. CAD-CAM technique was used to fabricate the bar attachment. The mandibular denture was rebased, and the retentive clip was processed by the indirect technique at the dental laboratory (Figure 2). No internal metal reinforcement was inserted in the mandibular dentures. All prosthetic connections and recall procedures were performed by the same faculty members (C.M., E.F.).
The study protocol was designed according to the principles of the Helsinki Declaration on clinical research (1975, revised in 2002). All patients signed a written consent statement before being included in the study. Before this consent they received detailed oral and written information about the study protocol, treatment plan, financial costs, follow-up period, and potential risks and complications. The study was approved by the Ethical Committee of the Ghent University Hospital (2014/1231) on clinical research involving human beings.