Past 10 cigarettes a day, GBR implants lose twice the bone

How much does smoking actually cost an implant placed with simultaneous guided bone regeneration (GBR)? This 5-year retrospective cohort followed 55 patients (130 implants), stratified by smoking intensity around thresholds of 10 and 20 cigarettes/day. Marginal bone loss (MBL) was measured radiographically, and survival analysed with Kaplan-Meier curves and multivariate logistic regression.

At 5 years the gradient was steep and dose-dependent. Patients smoking more than 10 cigarettes/day lost roughly twice the marginal bone of non-smokers and light smokers (2.67 mm vs 1.34-1.40 mm; P < 0.001), and heavy smokers (>20/day) lost the most (2.88 mm). Implant survival held at 100% for non-smokers and light smokers (≤10/day) but fell to 88.1% above that threshold. On multivariate analysis, smoking ≥20 cigarettes/day (odds ratio 16.7) and the use of non-resorbable membranes (odds ratio 10.4) emerged as the dominant independent risk factors for failure.

For clinicians, the value lies in the threshold: 10 cigarettes/day behaves as a clinical inflection point for GBR-supported implants, not a smooth continuum. The membrane signal is equally practical — in this cohort the non-resorbable membrane carried a substantial independent failure risk, a variable that belongs in the planning conversation alongside the patient's smoking habit. As a single-centre retrospective study the findings are associative, not causal, but the magnitude of the effect is hard to ignore.