A 67-year-old nonsmoker female patient in good general health was referred for implant placement and prosthetic rehabilitation in March 2012. She was completely edentulous and had worn full dentures in both arches for 17 years. The dentures at the time of presentation had been fabricated 3 months previously, and the patient was satisfied with the extraoral appearance of the lips and face and tolerated the vertical dimension (Figures 1(a) and 1(b)). Her main complaint was the loss of denture retention even though she used denture adhesive daily. The patient did not grant permission for extraoral photography.
Two (2) duplicates of patient's maxillary dentures were fabricated. One (DentDu-Brm) for the implant planning using clear resin (Paladur; Heraeus Kulzer, Hanau, Germany) for the base and barium sulfate resin (Acryline DVT, Anaxdent, Stuttgart, Germany) for the teeth (Figure 1(c)). The second one was using the same clear resin for the base and the teeth in order to serve as a transfer guide during restoration (DentDu) (Figure 1(d)). Duplicates were checked for intraoral fit before use.
Clinical examination and cone beam computed tomography (CBCT) revealed an extreme atrophy of the maxilla and mandible (Figures 2(a)-2(c)).
The patient's dentures were used for impressions with an alginate material (Alginat rosa; Omnident, Rodgau, Germany) and as guides for the articulation of the casts. Analysis of the articulated casts showed large vertical distances between the maxillary and mandibular alveolar crests (2.3-2.4 cm in the premolar/molar area, 1.9 cm in the anterior area) and a horizontal distance of 1.3 cm in the anterior area (Figure 2(d)). Therefore, rehabilitation with removable restorations was suggested. As the patient refused lateral and vertical augmentation, the decision was made to refabricate implant-retained removable dentures.
Both sinuses were grafted using a bovine xenograph (CompactBoneB; Dentegris, Duisburg, Germany), and the lateral windows were covered with porcine collagen membranes (BoneProtectGuide; Dentegris). In the same session, based on the CBCT, two implants were placed in positions #22 and #27 (SB line, 3.75 mm x 11 mm, Dentegris) and loaded immediately with a bar-retained overdenture using system-specific, prefabricated, angled, and tapered abutments (Figure 3). A bar was milled from type 3 cobalt-chromium-molybdenum alloy (CoCrMo; ZENOTEC NP; Wieland, Pforzheim, Germany), and a metal base (housing) was cast with CoCrMo (Ankatit, Anka Guss, Waldaschaff, Germany). Elastic plastic clips (Preci Matrice; CEKA, Waregem, Belgium) were used to retain the base over the bar (Figure 4).
Five months after sinus augmentation, a total of six implants (#3, 4, 6, 11, and 13; SB line; Dentegris) were placed. CBCT planning software (Sicat Implant, Sicat GmbH, Bonn, Germany) showed that the ideal tooth position was 6.8 mm in front of the alveolar ridge (Figure 5). However, one implant (left sinus, #11) could not be stabilized, so treatment proceeded with the five remaining implants.
The maxillary implants were uncovered 6 months after placement, and impressions were made using an open-tray technique and a polyether impression material (Impregum Penta Soft; 3M ESPE, Neuss, Germany). System-specific ball attachments (BATTs) with their retention elements were mounted on three implants for laboratory transfer. Access windows were created on the buccal side of the DentDu in the areas of the BATTs, and the retention elements were fixed to the DentDu with self-curing modeling resin (Pattern Resin; GC, Alsip, IL, USA). Centric jaw relation was recorded using the same resin (Pattern Resin; GC America Inc., Alsip, IL, USA; Figure 6(a)). A master cast was fabricated, and the BATTs were mounted on the implant analogs. The DentDu with retention elements was then positioned on the master cast, and casts were articulated under the guidance of the DentDu and jaw record (Figure 6(b)).
The maxillary bar was designed using a superimposed DentDu and was positioned as far labial as possible to provide support for the denture base (Figures 7(a) and 7(b)). After verification of the bar's fit, an electroformed mesostructure (ELMES; Galvanogold, Wieland) with a thickness of 0.25 mm was fabricated to conform to the shape of the bar (Figures 7(c)-7(e)). Framework was cast with CoCrMo alloy (Ankatit, Anka Guss, Waldaschaff, Germany) and tried in the patient's mouth to check its passive fit (Figure 7(f) and Figures 8(a) and 8(b)). In addition, a framework for an overdenture base was fabricated by casting CoCrMo alloy (Ankatit, Anka Guss; Figure 8 and Figures 9(a) and 9(b)). The U-shape framework covering the entire ridge including the lingual slope and partial palatal coverage provided rigidity and gains some degree of stability and support from the tissue. To provide passive retention and locking, two swivel-type lock attachments (swivel-type lock, Heraeus Kulzer, Hanau, Germany) were cast with a gold alloy (Hera; Heraeus Kulzer) (Figure 8(d) and Figures 9(c) and 9(d)).
The fabricated maxillary bar was mounted on the implants, the ELMES was placed on the bar (Figure 8(b)), and the jaw relationship was verified with the framework in place (Figure 8(c)). Subsequently, the ELMES was fixed to the framework using a self-cure compomer (AGC Cem, Wieland; Figure 9(c)). Denture teeth (SR; Ivoclar Vivadent, Ellwangen, Germany) were set and tried in before the finishing process. The denture was finished with the use of an autopolymerizing acrylic resin base material (PalaXpress Ultra; Heraeus Kulzer; Germany) and delivered back to the office on the same day (Figures 10-12).
The patient was then enrolled in a 6-month maintenance program. During the three years of observation period, at the follow-up visits, oral hygiene was reinforced together with debridement and prophylaxis.