A single molar implant in a smoker with a previous implant failure
A 57-year-old man requests replacement of his upper left first molar (26), which was lost three years ago. He smokes 10 cigarettes a day and has no intention of stopping. Three years ago an implant at 46 was removed after peri-implantitis, and he says 'the last one failed, so I want something that lasts'. His hygienist reports heavy clenching; there are wear facets on all canines and premolars and marked masseter hypertrophy. The 26 site is fully healed. Cone-beam CT shows 5 mm of bone height below the sinus floor, a 7.5 mm ridge width and 10 mm of mesio-distal space. Tooth 25 has a large composite restoration and no symptoms; 27 has a metal-ceramic crown with a 3 mm pocket distally. The opposing 36 is vital with a large amalgam and craze lines. All probing depths elsewhere are 3 mm or less, no tooth is mobile, and there is no periapical pathology. He does not want a removable prosthesis.
1. Compare a short implant, a sinus floor elevation with a longer implant, and a three-unit fixed partial denture from 25 to 27, and state which you would recommend.
Read the worked answer
Short implant (about 6 mm)
Avoids the sinus entirely, single surgery, no grafting, shorter treatment time. Pooled systematic review survival for short implants in the posterior maxilla is in the region of 95-97% at five years, broadly comparable with longer implants placed after sinus elevation. The risk is primary stability in a 5 mm site, which may be type IV bone.
Sinus floor elevation with a 10 mm implant
Addresses the anatomy definitively, with long-term data on the implant side. But it adds a lateral window, membrane perforation risk, a 6-9 month healing interval, and a second site of failure. In a current smoker - where implant failure risk is roughly doubled - adding a graft that also depends on vascularity is not the option I would choose first.
Three-unit fixed partial denture 25 to 27
No surgery and no smoking penalty. But it commits two heavily restored, currently asymptomatic teeth, and in a clencher it puts the connectors at risk and doubles the number of teeth that can fail. It also makes future hygiene around 26 difficult.
Recommendation
A short implant, provided primary stability can be achieved, with delayed rather than immediate loading. If torque or ISQ is inadequate at surgery, convert to a two-stage approach or abandon the site rather than load a poorly stabilised implant.
The uncomfortable part
His previous peri-implantitis and his smoking matter more than the choice between 6 and 10 mm. Whatever is placed, he needs to hear that recurrence is likely if nothing changes.
2. How would you design the crown and the occlusion to reduce the load on this implant?
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Prosthetic design principles
- Screw-retained rather than cement-retained where the angulation allows. It removes any risk of residual cement, which is a recognised contributor to peri-implant disease - relevant given his history - and it is retrievable.
- Monolithic zirconia or a similarly wear-resistant material, since a cemented ceramic crown in a clencher risks chipping that cannot be polished intra-orally.
- Restoration should be narrower than the tooth it replaces: an occlusal table reduced to roughly 60% of a natural molar and a flatter cusp angle reduce the bending moment on the implant.
- Keep 1.5-2 mm between the implant and 25 and 27 so the embrasures can be cleaned.
Occlusal scheme
- Contact in the central fossa against the opposing 36, with light even contact in centric relation, not heavy holding contacts.
- No working or non-working interferences in lateral excursion; the guidance should be on the canines and anterior teeth.
- Verify with articulating paper and a Shaw or similar gauge, and record the contacts photographically so they can be compared at review.
- A hard night guard, because his clenching is the single biggest threat to the restoration and to the implant.
Note that implant-supported restorations lack proprioceptive protection, so the occlusion must be designed to reduce load rather than rely on the patient's reflexes.
3. How would you frame consent and long-term maintenance for this patient, who says he wants 'something that lasts'?
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Be honest about the numbers
Quote realistic survival rather than a guarantee: short implants around 95% at five years in pooled data, but his smoking roughly doubles failure risk, and a previous early failure suggests he may be a susceptible patient rather than an unlucky one. His clenching adds mechanical risk. The honest statement is that a good outcome is likely but not assured, and that most failures are preventable with maintenance.
Address smoking explicitly
Advise cessation, and record that advice and his refusal. If he will not stop, ask him to abstain for at least the perioperative period (commonly advised as around eight weeks before and eight weeks after), and treat the refusal as an informed decision rather than a reason to refuse care.
Set the maintenance contract
- Hygiene review every three to four months, given a history of peri-implantitis and current smoking.
- Annual radiographs and probing with bleeding and suppuration recorded.
- Night guard use and occlusal review at every visit.
- Explicit instruction to report bleeding or swelling early, since peri-implant mucositis is reversible and peri-implantitis is not.
Document
Record the alternatives offered (short implant, sinus elevation, fixed partial denture, no treatment), the risks discussed, his preference, and his refusal to stop smoking.