Clinical Continued »
to correct OVD, bite and to evaluate tissue support required
Fig 4 Framework try-in close-up Fig 5 Lower jaw condition
Surgical considerations In such cases my approach is firstly to ascertain the corridor of bone that lies between the medial wall of the maxillary sinus and its position. In order to gain this information, one must be familiar with the manipulation of the CT scan image. Often RAW data is needed to draw the correct cross sectional curve along the desired axis of implant place- ment. Pre-formatted scans on some software platforms may not allow the operator to manipulate this curve. The corridor of bone exists in most
Fig 6
Hybrid acrylic-composite prosthesis fabri- cated with screw-retaining inserts
patients and can accommodate a longer implant fixture whereby the cervical implant head can lie distal to the apex of the implant hence negating the need of a sinus graft and allowing the implant to be placed more distal in the arch. For inexperienced implant dentists a
Fig 7 Hybrid acrylic-composite prosthesis
surgical guide to triangulate this posi- tion exactly is an absolute requirement. In practice, this area can be marked out as the zygoma has a distinct curva- ture on exposure of the maxillary jaw. Where the curvature or bulbosity starts is usually the position of the medial wall of the maxillary sinus, then by use of osseotomes/bone expanders, drills and reconfirming this position can be achieved in two ways. Perforation into the sinus via the
Fig 8 Final fixation of the prosthesis
lateral wall and palpation of the medial wall and mark points at 3, 6 and ıımm – or by intra oral X-rays and check the osteotomy site for perforations during surgery. I recognise these are not ever as accurate as a CT-guided stent and the author would always recommend a bone supported stent in these cases as apposed to a soft tissue supported guide. The other consideration is the space
Fig 9 Prosthesis and lip repositioning
along the horizontal plane to place four or up to six implants. Although there is a lot of literature relating to “all-on-4” techniques, the author prefers, where possible, to place six implants due to the fact that, if a failure occurs (it is currently accepted that two in every ı00 or 2 per cent will fail), there is a backup and one can still fabricate a reliable final prosthesis on five or four implants, if equally spread along the arch.
26 Ireland’s Dental magazine
5. CT scans of upper jaw with correct prosthesis in position to study hard tissue relationship and correct tooth position. It was also required in order to ascertain the degree of bone volume/density present.
One must also consider the A-P (Ante-
rior-Posterior) spread of the implants. In such cases there must be adequate A-P spread to allow for favourable loading of the prosthesis as, using this tech- nique cantilevering will be required in most cases.
Healing After placement of the six DIO SM dental implants, a postoperative OPG was taken and the denture relined with soft reline material over the healing abutments. I opted for transmucosal healing as we achieved high levels of primary stability on all the implants. In this case the distal implant on the right side entered the sinus space and we performed a Summer’s Lift. The patient was allowed to heal for a period of five months with the temporary relined denture.
Prosthetic protocol After the healing period, all implants were checked using a periotest to measure osseointegration. The readings were as follows: • UR3 Implant = -7.0 • UR2 Implant = -6.9 • URı Implant = -5.0 • ULı Implant = -8.0 • UL2 Implant = -5.0 • UL3 Implant = -6.0 From the readings, we could see
that all implants had osseointegrated well and showed no pain, mobility, infection, loss of bone or exposed titanium intraorally. We then carried out the following sequence for restoration: ı. Fixture head impressions linked in a special tray. Using floss and GC pattern resin to link impression screws.
2. Try-in of the DIO Multi-Unit angled screw-retained abutments with lab-made positional jig to ensure abutments are parallel.
3. New impression of the Multi-Unit angled abutments and X-ray verifica- tion of correct seating. Again, these are linked using GC pattern resin and a verification jig made by the lab to verify accuracy of model prior to metal framework construction.
4. The denture was relined again over the new abutments.
5. Metal framework try-in – screw- retained and checked for passive fit using the Sheffield test. Re-verification of the midline, re-bite registration, a new face-bow record, intra-oral and extra oral photography to give the technician sufficient data to make
Page 1 |
Page 2 |
Page 3 |
Page 4 |
Page 5 |
Page 6 |
Page 7 |
Page 8 |
Page 9 |
Page 10 |
Page 11 |
Page 12 |
Page 13 |
Page 14 |
Page 15 |
Page 16 |
Page 17 |
Page 18 |
Page 19 |
Page 20 |
Page 21 |
Page 22 |
Page 23 |
Page 24 |
Page 25 |
Page 26 |
Page 27 |
Page 28 |
Page 29 |
Page 30 |
Page 31 |
Page 32 |
Page 33 |
Page 34 |
Page 35 |
Page 36 |
Page 37 |
Page 38 |
Page 39 |
Page 40 |
Page 41 |
Page 42 |
Page 43 |
Page 44 |
Page 45 |
Page 46 |
Page 47 |
Page 48