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Case study:Implant dentistry 'upside down'

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  • 1. Clinical Case study: implant dentistry ‘upside down’ Stephen E B Jones, Specialist in restorative dentistry and Ben Page, dental technician describe a case study where implants are placed directly to fit existing fixed restorations Introduction Abstract A 55-year-old healthy female patient was The importance of planning the precise shape and restoration of individual treated at her general practice and had several teeth before placing dental implants has been documented many times over teeth removed and partial dentures made. However subsequently she expressed a wish the last two decades. However there is no mention in the dental literature to return to fixed teeth. In May 2002 eight of succeeding in doing just the opposite – trying to place implants directly dental implants (Nobel Biocare ReplaceSelect, to fit existing fixed restorations. This case study presents a situation where Nobel Biocare UK Ltd), were placed as a single two mandibular three-unit bridges, both originally retained bilaterally by stage procedure, under intravenous sedation. two implants, had to be removed after an implant under each had been Four hydroxyapatite coated implants were lost due to an iatrogenic periimplantitis. Two new implants were precisely placed in the partially dentate maxilla and two placed and new custom abutments were fabricated between the implants each were placed bilaterally in the mandible, and the original bilateral bridgework. Both bridges were then recemented as single stage surgical procedures. Healing eight months after their original ‘failure’. was totally uneventful. Cemented porcelain fused to metal bridgework was subsequently made several months later in both arches using GoldAdapt The problems infected implant as well. In Figure 1 cement (Nobel Biocare UK Ltd) cast-on abutments, On returning to the UK four years later can be seen at the top of the thread on the also commonly known as UCLA abutments she re-attended her original general dental implant ‘in situ’. In Figure 4 the cement (Lewis et al, 1988). The bridges were fitted by practice complaining of a loose bridge. The fragments that were attached can be seen. the patient’s general practitioner to restore the dentist that had fitted the original abutments The reason for the periimplantitis was because patient with a first molar to first molar slightly and bridgework had emigrated and the new the bridge margins at the more distal implants shortened dental arch arrangement. The associate was horrified to see a decemented very had both been cemented subgingivally into a patient went to live abroad and did not attend loose bridge on the lower left, still cemented tight tissue cuff only previously occluded by the one-year recall with either the implant to the loose distal implant. The bridge was relatively narrow healing abutments. In seating surgeon or referring practitioner. simply removed from a mass of surrounding the bridges the cement had been extruded granulation tissue. He immediately referred subgingivally, under pressure, and this cement the patient back to the original implant had traversed the polished titanium collar to surgeon, the author, enclosing the bridge and adhere to the roughened implant surface. implant. This was the subject of an elegant laboratory Stephen E B Jones, Examination revealed a healing socket in study over 10 years ago (Agar et al, 1997) and BDS MSc MGDS the lower left second premolar position where is a well known hazard of cement-retained MRD, Specialist the bridge had been present and radiographic prosthodontic work on implants, especially in in Restorative examination showed a virtually identical the aesthetic zone where it is often desirable to Dentistry. Stephen is a Partner in problem on the lower right. place crown or bridge margins subgingivally. Pentangle Dental A computerised tomography (CT) scan This superfluous cement ridge acts as a ligature, Transformations, a referral practice based was taken. This showed the presence of of the type that has been seen to produce a in Newbury that opened in 2006. His prac- intact lingual and facial bony plates of rapid periimplantitis (Zitzmann et al, 2004) in tice combines teaching with work limited to good dimensions at both infected sites and animal experiments. Periimplantitis represents implant and cosmetic dentistry. the inferior dental nerve canals situated an inflammatory condition that is usually only Ben Page, Dental Technician, gained his immediately beneath. associated with the presence of a submarginal BTEC in Dental Science at South London Fortunately both bridges had been cemented biofilm and with advanced breakdown of College, Lambeth, and worked for Broughton with a semi-permanent resin based cement soft and mineralised tissues surrounding Tyrell from 1991 - 2000. Has been work- ing with all the major implant systems at (Improv – Nobel Biocare UK Ltd). Therefore dental implants. These rapidly progressive Precision Dental Studio since then. He can it was possible to remove the remaining lower periodontal lesions have been observed many be contacted at: right bridge from the more mesial abutment times anecdotally in the dental literature and ben@precisiondentalstudio.co.uk with a Mead crown remover, albeit with the many of these are probably associated with 32 Implant dentistry today November 2007 Volume 1 Number 4
  • 2. Clinical Figure 1: Periimplantitis present Figure 2: Healing socket where bridge removed related to cement Figure 3: CT scans of sites dental cement acting as a foreign body and thoroughly immediately after removing the 4.3mm Replace Select RP, TiUnite surfaces) implicated in the development of the lesion. implant and bridge but it was decided not to implants were placed under infiltration local In these situations a decision has to be made reopen the healing socket on the lower left for anaesthetic (Articaine 4% with 1:100000 regarding management of the problem. The currettage. Both lower bridges, together with adrenaline). Both bridges located well on the options are culture and antibiotic therapy, attached implants, were returned to the dental anterior undamaged abutments and so were resective treatment, and removal of the laboratory and heated slowly to break the able to be used as accurate positioning guides implants (Esposito et al, 2004). Removal of cement seal between the exfoliated implant for the new implants. This was accomplished the second bridge and immediate curettage abutments and the bridges. The two implants by establishing the correct position under the of the chronically infected site was the only and cast-on gold abutments were then bridge with a 2mm twist-drill then verifying sensible solution in this case. returned to Nobel Biocare UK for replacement this using guide pins before completing the under their 10-year warranty agreement. drilling sequence. The CT scan establishes Surgical retreatment Five months later bony healing at the sites the buccolingual dimensions with a degree The socket on the right was curetted was complete and two replacement (10mm x of accuracy that allows only minimal flap November 2007 Volume 1 Number 4 Implant dentistry today 33
  • 3. Clinical Figure 4: Bridge with cement fragments Figure 5: 2mm Guide pin Figure 6: Bridge over guide pin Figure 7: Implant placed Figures 8 and 9: New implants immediately post-placement elevation to be undertaken. The procedure over the undamaged cast-on abutments made of the lower arch in polyvinylsiloxane on the right side is shown in Figures 5-7. The mesially (Temp Bond, Kerr UK Ltd). impression material (Flexitime, Hereaus Kulzer surgical procedure was exactly the same on Monofilament sutures were placed to secure Ltd). A model was produced using 4.3mm the left side. the minimal soft tissue flaps and were removed implant replicas (ReplaceSelect, Nobel Biocare Healing abutments were placed on both one week later. Healing was uneventful. UK Ltd).Two new engaging cast-on GolAdapt the new implants, right and left, in a single- Eight weeks later bony healing was abutments (Nobel Biocare UK Ltd) were cut stage surgery. Temporary crowns were made complete and impressions were taken using an down as required to engage the old bilateral (Prevision, Heraeus Kulzer Ltd) and cemented open tray technique. A master impression was bridgework using a rigid bite registration 34 Implant dentistry today November 2007 Volume 1 Number 4
  • 4. Clinical Figure 10: Cast-on gold abutment as supplied Figure 11: New cast gold abutments on model (GoldAdapt, Nobel Biocare UK Ltd) Figure 12: Right abutment Figure 13: Refitted bridge material (Stonebite, Kerr Ltd). Care was taken putty indices. A small amount of Vaseline There was some minor occlusal adjustment to make sure that the bridges were in occlusion (Elida Faberge Ltd) was used as a separator to the occlusal surface of the right bridge, but with the upper jaw opposing dentition when inside the bridges and the abutment shapes none to the left bridge. After tightening the the registrations were taken. were formed with pattern resin (Duralay, GC abutment screws to 35Ncm the screwheads Gold cast-on custom abutments still Ltd) incrementally applied to the GoldAdapt were covered with a soft wax plug. Both bridges have a lot to offer in dentistry, despite the (Nobel Biocare UK Ltd) abutments. The were cemented with RelyX Unicem (3M/ESPE recent proliferation of titanium and zirconia abutment screw access holes inevitably became Ltd) and the occlusion rechecked. Because of abutments manufactured in many forms occluded by pattern resin and so the set resin the inevitable loss of alveolar ridge hard and (Chee and Jivraj, 2006). had to be cut away to gain access to each screw soft tissue after the loss of the implants the Although it is now routine to form the head. Each abutment was then invested using new bridge margins were inevitably coronal to desired abutment shape in pattern resin or Moldavest Exact (Heraeus Kulzer Ltd) and the gingival margins. This was not a problem casting wax and then produce a replacement placed in the furnace at room temperature, aesthetically and safeguarded against leaving custom abutment in either zirconia or milled then held at 250 degrees centigrade for one any excess cement second time around.A high titanium by the Procera (Nobel Biocare UK hour to burn out the pattern resin. Then the level of oral hygiene can be easily achieved Ltd) method we had received replacement temperature was raised to the final casting because of the necessarily wide residual GoldAdapt abutments under the manufacturer’s temperature of 700 degrees centigrade and embrasure spaces present. warranty. In addition to being strong in thin both abutments were cast using 3 STAR alloy section gold can be cast extremely accurately (Metalordental Ltd) and were left to cool on Conclusion and has a long record in dentistry of excellent the bench. A small layer of red lipstick was Why carry out this form of prosthodontic biocompatibility. painted inside the fit surface of each bridge to gymnastics? Quite simply it comes down, show high spots on each casting. These were like so much in prosthodontics, to cost/ Laboratory procedures adjusted and after finishing and sandblasting benefit. The impression and bite registration In the dental laboratory the upper cast was the work was returned to the surgeon for appointments were rolled into one and there articulated with the lower bridges using fitting. were no intermediate ‘try-ins’ of either metal 36 Implant dentistry today November 2007 Volume 1 Number 4
  • 5. Clinical Figure 14: Bilateral bridges on new abutments Figures 15 and 16: Right and left bridges definitively recemented returned for fitting work or porcelain. Therefore the prosthodontic convincing reasons for using both protocols, Esposito M, Worthington HV, Coulthard P. appointments were essentially completed in only sometimes within the same prosthesis. However Interventions for replacing missing teeth: two long appointments and, with the additional this discussion is way beyond the scope of this treatment of peri-implantitis Cochrane saving of the dental laboratory fees in accepting case report and the reader is advised to read Database Syst Rev. 2004; 18: CD004970. the old bridges and the implant company further on the matter (Michalakis et al, 2003). Lewis S et al. The ‘UCLA’ abutment Int J Oral honouring their 10-year warranty, this made this The implants will be reviewed on the Maxilofac Implants 1988;3:183-189. ‘salvage’ operation relatively inexpensive. anniversary of their placement, which is always Michalakis KX, Hirayama H, Garefis PD. It is not advisable to heat porcelains that have our preferred protocol. Regular dental hygiene Cement-retained versus screw-retained implant been in and out of the oral environment for long appointments every six months have also been restorations: a critical review Int J Oral periods of time, but if the bridges were to remain implemented. Of course if this had been possible Maxillofac Implants 2003;18:719-728. intact there was no option other than heating in one year after the initial implant placements it Zitzmann NU, Berglindh T, Ericsson I, Lindhe order break the cement seal. The patient has been might have been possible to spot the problems J. Spontaneous progression of experimentally warned of the possibility of porcelain fracture in at their inception using routine periodontal induced periimplantitis J Clin Periodontol the future. Even if this occurred it is likely that a screening measures and standard radiographs. 2004;31:845-849. I bridge could still remain functional. Then one or other of the periimplantitis lesions The patient was very happy with the savage might have been averted. Addresses for correspondence: operation. It can always be argued, with the benefit of hindsight, that these problems could References: Stephen Jones – Pentangle Dental Transformations, Newbury, have been avoided if both brides had been Agar J, Cameron SM, Hughbanks JC, Parker Berkshire RG14 1EA screw-retained rather than cement-retained. MH. Cement removal from restorations luted to contact@pentangledental.co.uk Both bridges would have been easily retrievable titanium abutments with simulated subgingival Tel: 01635 550353 and of course the displaced cement would not margins J Prosthet Dent 1997;70:43-47. Ben Page - Precision Exclusive, Preci- have been present in the first instance. The reality Chee W, Jivraj S. Designing abutments for sion Dental Studio, Rivermead, today is that the majority of fixed dental implant cement retained implant supported restorations Thatcham, Berkshire. RG19 4EP Tel: 01635 294200 prostheses are cemented and there are many Brit Dent J 2006;201:559-563 November 2007 Volume 1 Number 4 Implant dentistry today 37

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