The patient, a 62-year-old female, was referred by her general dental practitioner with regards to providing a fixed
replacement solution for the upper posterior teeth. She wanted to substitute her existing partial denture.
A full arch metal based partial acrylic denture was previously provided to replace two of her posterior teeth (25, 26), but the patient had not been able to wear this regularly due to its inherent looseness, sensation of a metallic taste, noticeable food packing and halitosis when the denture was used. The patient was also concerned about the dentures’ visible metal clasp arms, which she didn’t approve, and subsequently had them removed, compromising denture retention.
The patient had not worn her dentures for the past year or so, and diminished posterior support and stability created unfavourable loading for the remaining teeth. The patient was therefore worried about excessive occlusal forces being applied to her front teeth, and attended to explore the possibility of fixed restorations for her missing posterior dentition.
Examination and findings
The patient presented with a partially edentulous arch with missing 16, 17 and 25, 26, 27 (figs 1 and 2). Majority of these teeth were lost due to periodontal disease and complications. She also had a heavily restored UR5 (fig 3) and her LR6 was severely broken down. Mobility of tooth 24 and fremitus of the upper central incisors were detected upon
examination.
The patient’s oral hygiene was excellent and her periodontal status and occlusion were stable. The patient was diagnosed with localised marginal gingivitis, occlusal trauma to the anterior teeth with reduced posterior support and an unrestorable 46.
Treatment plan
The following treatment plan was agreed upon to improve function and appearance by utilising a shortened dental arch concept, thereby simplifying treatment:
? Implant crowns 25, 26, 46
? Crown 15
? Monitor 24 (guarded prognosis)
This treatment plan was amended during the proceedings once tooth 46 was extracted and a CT scan of the area obtained; anatomical constraints made surgical implant placement impossible to carry out for this area.
The same scan also showed that implants were possible for sites 25 and 26 without any additional sinus augmentation procedures.
Treatment details
Minor bite adjustment was performed before the implants were placed, with the occlusal adjustment successfully reducing the mobility of tooth 24.
Two Straumann tissue level regular neck 8mm implants were placed in 25 and 26 with simultaneous autogeneous and xenograft bone graft. The implants were completely submerged to allow for optimal osseointegration.
Whilst the implants were left to integrate, tooth 15 was restored with a porcelain fused to metal crown. After three months, the implants were exposed and healing caps secured in place. The implants had healed well and showed no signs of infection or failure (fig 4).
A full arch impression was made using an open-tray technique and a polyether material, Impregum Penta. The open-tray technique was chosen because of its accuracy. Impregum Penta impression material was chosen in view of its excellent flow properties, detail reproduction, hyprophilicity, delayed snap-set and rigid behaviour.
These characteristics help the material to deliver excellent detail without distortion while using a simple mono-phase technique that eliminates the need for two viscosities, thereby simplifying the procedure and reducing material cost. These advantageous clinical qualities help to ensure consistent accuracy of fit for implant fixed and removable prosthesis, as demonstrated by this case.
Impression copings were seated in place, their positions verified visually (fig 5). A customised tray was filled with the Impregum Penta impression material followed by intra-oral syringing of the material around the copings to pick up soft tissue detail (figs 6-8). The tray was placed in the patient’s mouth and held steady until its full setting time of six minutes. The tray was removed and inspected, exhibiting a beautiful impression. After complete setting, the impression and copings were removed, creating a detailed, accurate cast (figs 9-11).
A precise impression was even more important in this case because of a plan to link the two crowns together in order to distribute posterior load more evenly between both implants. The decision to link the crowns was due to several factors: implants resting on bone grafts, implants of shorter length and their position in the arch without any distal posterior natural dentition.
The impression was sent off to the lab (lab 39) for a cast verification acrylic jig on which a working jaw registration was recorded using wax registration medium (fig 12). Two custom-made Straumann titanium CAD/CAM abutments and linked porcelain fused to metal crowns were ordered.
The abutments were secured in place with a metal location jig (fig 13) and torqued according to the manufacturer’s instructions. The crowns were tried in and the occlusion checked prior to final cementation.
Treatment results and conclusions
The patient was very happy with her final restorations (fig 14-17), and reports much improved oral function since receiving her implant restorations. These have provided her with improved posterior support and stability, helping to redistribute the loading on the remaining teeth whilst achieving the desired aesthetic improvement to her smile.