**5. Pattern of bone loss in peri-implantitis**

The pattern of bone loss in peri-implantitis is classified into vertical, horizontal, and combined bone loss. The most common pattern of bone loss is vertical (65%) and then horizontal (22%), and the least common pattern is combined (13%) [11].

## **6. Prevalence of peri-implantitis**

The prevalence of peri-implant mucositis and peri-implantitis has ranged from 19 to 65% and 1 to 47%, respectively [12, 13]. A systematic review revealed that the frequency of peri-implant mucositis was 63.4% on the patient level and 30.7% on the implant level. The peri-implantitis prevalence was 18.8 and 9.6%. In smokers, the frequency of peri-implantitis increased to 36.3% [11]. The prevalence of peri-implant mucositis at the patient level varied between 1.1 and 80% [14–19]. The prevalence of peri-implantitis at the patient level ranged from 1.4 to 53.3% [14, 15, 17–26].
