Replacing two mandibular molars in a smoker with a shallow, narrow ridge
A 54-year-old man attends for replacement of the mandibular right first and second molars (46, 47), lost 4 years ago. He smokes 20 cigarettes a day and has type 2 diabetes (HbA1c 6.9%, no complications), managed with metformin alone. He asks for "teeth in a day" and refuses a removable denture at any stage. Examination shows a full-mouth plaque score of 38% and bleeding on probing of 42%, with 7 mm pockets on the mesial of 45 and 6 mm on 36; there is 1 mm of keratinised tissue buccal to the edentulous ridge. Cone beam CT shows a ridge width of 5.5 mm and 6.5 mm of bone between the crest and the superior wall of the mandibular canal, with a buccal undercut. The opposing maxillary teeth are heavily restored but functional. He wants implants "as soon as possible" and is not interested in a long discussion about grafting.
1. What must be addressed before any implant is placed, and how would you sequence his care over the next 12 months?
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Nothing about this case is a single-visit problem, and the biggest risks are periodontal and behavioural, not surgical.
1. Periodontal risk assessment and stabilisation (weeks 0–12). Plaque 38% and BOP 42% with 7 mm on 45 and 6 mm on 36 indicate untreated, active periodontitis. Implants placed into an unstable periodontal environment have markedly higher rates of peri-implantitis. He needs: oral hygiene instruction with documentation of technique, full-mouth supra- and subgingival debridement ( staged by quadrant), re-evaluation at 8–12 weeks, and a definitive plan for 45 and 36 based on the re-evaluated pocket chart and radiographs. A patient-level diagnosis (for example, generalised periodontitis, staging based on interdental bone loss and grading based on age and smoking) should be recorded, because it drives the recall interval. The target at re-evaluation is BOP below about 20% and no residual pockets over 4 mm with bleeding.
2. Smoking. This is the single most modifiable implant risk factor: it roughly doubles implant failure and substantially increases peri-implantitis and marginal bone loss, in a dose-dependent way. Offer brief advice, referral to a cessation service and pharmacotherapy; document the offer whatever the response.
3. Diabetes. HbA1c 6.9% is acceptable for implant placement, but check it again closer to surgery and confirm no hypoglycaemic episodes or infections.
4. Sequence. Periodontal treatment → re-evaluation → smoking cessation support → implant surgery at 3–4 months if the tissues are stable → healing → restoration. His "as soon as possible" should be reframed as "as safely as possible", with the timeline written down for him.
2. Compare the options for the vertical and horizontal deficiency at 46/47 and recommend one, with justification and the specific risks of each.
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There is 6.5 mm of bone above the canal and 5.5 mm of width with a buccal undercut. Four options:
A. Short implants (6 mm length, 4.0–4.3 mm diameter). Requires 1 mm of safety above the canal, which is available. Survival in the posterior mandible with short implants is well supported and comparable to longer implants, and it avoids grafting entirely. The buccal undercut means the implant should be placed slightly lingual to the crest with careful angulation, or the buccal contour can be adjusted with a small simultaneous graft. This is my recommendation - it is the least morbid option, needs one surgery, and fits his refusal of lengthy grafting.
B. Vertical ridge augmentation (block graft or GBR with tenting screws) followed by 10 mm implants. Predictable in experienced hands but adds a donor site or a membrane, 6–9 months of healing, resorption, higher cost and higher chance of complications. Also requires a second surgery. Poorly matched to his stated preferences and his smoking status - smoking materially reduces graft success.
C. Nerve lateralisation or transposition. Allows long implants but carries a substantial risk of temporary and permanent neurosensory disturbance (temporary paraesthesia commonly reported in the region of 10–20%, permanent deficit in a small but real percentage). Not justified when a short implant is available.
D. Do nothing / shortened dental arch / removable prosthesis. He has refused a removable prosthesis, and the shortened dental arch is a legitimate but different discussion.
Risks to consent for the chosen option: implant failure (higher in smokers), nerve injury including temporary altered lip and chin sensation, buccal plate perforation in the undercut, peri-implantitis, and the need for a graft if primary stability is inadequate at surgery.
3. How would you counsel him about "teeth in a day", his smoking, and the long-term prognosis of the planned reconstruction?
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On immediate loading: immediate loading is a protocol with conditions, not a promise - primary stability (insertion torque or ISQ above threshold), splinting of multiple implants, absence of parafunction, and good bone quality. Posterior short implants in a smoker with a thin ridge do not meet those conditions, and immediate loading here would raise failure risk. The honest answer is that he can have a fixed provisional tooth replacing the gap relatively early, but the definitive crowns should come after 3–4 months of unloaded healing. If he cannot accept that, the alternative is a cantilevered resin-bonded or conventional bridge - which also has risks - and he should be told the trade-offs rather than simply being refused.
On smoking: explain the numbers in plain language - smokers have roughly double the implant failure rate and more marginal bone loss over time, and the effect is dose-related. The most useful window is stopping at least 1 week before surgery and 8 weeks after. Offer nicotine replacement, varenicline or a cessation service referral, and record that the advice was given. Do not make treatment conditional on quitting, but do not proceed while implying that smoking is irrelevant either.
On prognosis: explain that implants are not a one-off purchase. With his periodontal history, he will need maintenance every 3–4 months initially, with probing and radiographs, and there is a real risk of peri-implant mucositis and peri-implantitis. Give a realistic 10-year outlook with the caveat that smoking and plaque control will largely determine it call. Set the recall interval in writing and make sure he knows the reconstructions can be lost.