Survival analysis of implants after surgical treatment of peri-implantitis based on bone loss severity and surgical technique: a retrospective study

Table 4 Survival estimate analysis (Kaplan-Meier and Cox hazard regression) based on peri-implantitis stage and surgical technique

Subgroup	Number	No. of Failures (%)	Cumulative survival rate (95% CI)	Median survival time after surgery in years	Estimated mean survival time after surgery in years (95% CI)	P-value (log-rank test)
1	79	13 (16.5)	70.7 (55.8–85.6)	-*	9.95 (8.98–10.92)	< 0.001*	1.00 (Reference)
Stage 1, Resective surgery	47	9 (19.1)	73.1 (57.8–88.4)		8.99 (8.06–9.93)	0.663
Stage 1, Regenerative surgery	32	4 (12.5)	73.4 (48.9–97.9)		10.25 (8.73–11.77)	0.663
2	70	23 (32.9)	48.9 (27.9–69.9)	8.18	7.96 (6.65–9.26)	< 0.001*	2.25 (1.14–4.45), 0.02*
Stage 2, Resective surgery	35	13 (37.1)	49.9 (29.7–70.1)		7.11 (5.70–8.52)	0.675
Stage 2, Regenerative surgery	35	10 (28.6)	51.1 (19.3–82.9)		8.26 (6.38–10.14)	0.675
3	78	35 (44.9)	21.3 (4.2–38.4)	3.63	5.67 (4.46–6.88)	< 0.001*	4.59 (2.42–8.71), < 0.001*
Stage 3, Resective surgery	20	10 (50.0)	26.0 (1.5–50.5)		4.02 (2.64–5.40)	0.358
Stage 3, Regenerative surgery	58	25 (43.1)	22.7 (3.5–41.9)		6.00 (4.61–7.40)	0.358
Resective surgery	102	32 (31.4)	57.0 (45.4–68.6)		7.60 (6.79–8.42)	0.444
Regenerative surgery	125	39 (31.2)	44.2 (39.3–59.1)		7.73 (6.73–8.72)	0.444
Overall	227	71 (31.3)	47.8 (36.8–58.8)	8.96	7.93 (7.21–8.65)

* Median survival time for stage 1 could not be calculated because the cumulative survival rate remained higher than 50% until the end of the study.
Note: The category with hazard ratio (HR) = 1.0 was considered the reference category to which other categories were compared; Significant p-values are shown with *. P-value (log-rank test) for comparison between stages was significant based on Bonferroni Correction Method ( stage 1 vs. stage 2, p = 0.012; stage 1 vs. stage 3, p < 0.001; stage 2 vs. stage 3, p = 0.008; < 0.016 = 0.05/3). Cox hazards regression analysis based on surgical technique was not conducted because the p-values from the log-rank test were not statistically significant and did not fulfill the criteria. CI = confidence interval.

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