Full mouth rehabilitation with maxillary equator® attachment over denture and mandibular hybrid denture-a case report

Implant-supported prosthodontic rehabilitation of total edentulism remains the most complex restorative challenges. The main reason being the number of variables that affect both the aesthetic and functional aspects of the prosthesis. A hybrid denture or the ‘Toronto prosthesis’ is one that is fabricated over a metal framework and retained by screws threaded into implants. This article presents the fabrication of implant-retained maxillary Equator® attachment overdenture opposing mandibular implant-retained hybrid prosthesis. A total of four implants (Equinox®Myriad plus) were placed themaxillary arch and six implants (Equinox®Myriadplus) in themandibular arch. The patient’s occlusal vertical dimension, centric relation, aesthetics and phonetics were determined andmaintained throughout the restorative process. This case report describes the management of a completely edentulous patient with amandibular implant-supported ixed prosthesis andmaxillary implantretained overdenture with Equator® attachment.


INTRODUCTION
For many patients, being edentulous is regarded as a handicap with respect to oral function (Bottlang et al., 2010). This has an impact on their overall well being and quality of life (Alzarea, 2017). With the advent of implants, this is no longer the case. The main objective of implant placement in completely edentulous individuals is to provide ixed support and improved stability for the prosthesis (Hara et al., 2017). Various studies have shown signi icant improvement in the quality of life of edentulous patients after implant therapy (Yoshida et al., 2016). Common treatment options for completely edentulous patients include implant-retained prosthesis, and conventional removable prosthesis (Sargolzaie et al., 2017). Many innovations in attachments have increased the number of options for restorative dentists (Mijiritsky et al., 2014;Mendes et al., 2016). This case report describes the management of a completely edentulous patient with a mandibular implant-supported ixed prosthesis and maxillary implant-retained overdenture with Equator ® attachment.

CASE REPORT
A 60-year-old male patient presented to the Department of Prosthodontics at Saveetha Dental College, with a chief complaint of loose dentures. The patient was edentulous for 4 years and had lost most of his teeth to caries. He was wearing a set of complete dentures for the past 4 years, which was ill-itting and uncomfortable. The patient desired improvement in prosthesis and was advised to go for an implant-retained prosthesis. No relevant medical history was observed. After an initial consultation, a complete extraorall and intraorall examination of the patient was carried out. A diagnostic impression was recorded, and cone-beam computed tomography (CBCT) was advised. The CBCT revealed a close proximity of the right and left sinus loor to the maxillary posterior alveolar ridge. A complete medical and hematological examination revealed no absolute contraindication to any therapeutic or surgical modality.

Figure 3: Veri ications jigs made with Pattern Resin ® (GC Corp, USA)
As the patient was not willing for sinus lift due to increase in treatment time, the treatment planning was limited to 4 implants in the maxilla and 6 implants in the mandible with the present dentures being used as a radiographic stent (Greenberg, 2015). The previous dentures were also used to assess the vertical dimension and the inter arch space prior to treatment planning.
Finally, implant-retained maxillary Equator ® overdenture with a bar-retained hybrid prosthesis in Surgical phase involved the placement of endosseous implants (Equinox Myriad Plus ® ) after administration of local anesthesia. A crestal incision was placed with a number 15 bard parker blade. A full-thickness mucoperiosteal lap was elevated, following which Endosteal implants were placed in in11,21,13,23 regions in the maxilla and 33,35,37,43,45,47 regions in the mandible (Figure 1) (Nejad et al., 2016). The lap was then sutured, and post-operative instructions were given. The delayed loading protocol was followed. Therefore the patient was called back after the 6 month healing period for the prosthetic phase.
In the prosthetic phase, an Orthopantomogram was irst obtained (Figure 1) to evaluate and assess the bone to implant contact. The radiograph showed good bone to implant contact, and the patient was scheduled for stage 2 surgery. Stage 2 surgery was performed under local anesthesia, after the elevation of the lap to expose the cover screws. A fullthickness mucoperiosteal lap elevation (Figure 2) was performed to clinically assess the health of the implants. No fenestration or bone loss was observed clinically. The cover screws were then removed and replaced with healing abutments and the lap sutured was sutured back again.
After 2 weeks, the patient was recalled, and the healing was assessed (Mijiritsky et al., 2014). Upon satisfactory healing, a diagnostic impression was recorded with alginate (Tulip ® ) and standard stock trays. Custom Light polymerised special trays (Polytray ® Delta Dental) were adapted over the casts after blocking out undercuts with wax. Direct impression copings were then placed on the implants and were splinted together ( Figure 3) with pattern resin(GC ® , USA). Pattern resin was used because of its low polymerisation shrinkage value and ease of application. The master impression was then recorded with a medium-bodiedd impress (Abduo and Lyons, 2013) ion material (Figure 4)(Monophase ® Dentsply, USA).
Once the master casts were obtained, they were optically scanned using a model scanner (Zirkon Zahn ® USA). The implant positions were then veri ied with a PMMA (Poly methyl methacrylate) jig, which was designed (Afshari et al., 2017) and milled via CAD-CAM ( Figure 5). The jig was then veriied both clinically as well as radiographically (Buser et al., 2008) for any mis it. Once the it was veriied (D'haese et al., 2000), occlusal rims were fabricated to determine the interocclusal space. The occlusal rims were then placed into the patient's mouth, and the jaw relations (Centric and Vertical) were recorded (Figure 6). Maxillary and mandibular metal frameworks were fabricated and were veri ied for an accurate it, clinically and radiographically in the patient's mouth. After evaluation, the frameworks were sent back to the lab for teeth setting. The patient's son was also called for the trial appointment to assess aesthetics (Laederach et al., 2017). After the trial, the prosthesis was inserted after tightening the abutments to 25Ncm. Occlusal adjustments were made, and bilateral balance was veri ied. The patient was satis ied with his aesthetic appearance and restored chewing function (Figure 7). Peri implant-bone levels were assessed after two years of follow up and were found to be within a normal range (Jawad et al., 2017)

CONCLUSIONS
This case report presents a treatment option and procedure of full mouth rehabilitation involving mandibular implant-supported ixed prosthesis and maxillary implant-retained overdenture with Equator ® attachment.