Fracture of Screw / Implant

Biomechanical overloading and peri-implant vertical bone loss are the two main causes of implant breakage.When the vertical bone loss is significant enough to coincide with the screw's apical limit, the risk of implant breakage increases many times. Implant fractures can also result from defects in the implant's production and design. One risk factor for dental implant fracture is undetected and frequent screw loosening, which suggests a redesign of the prosthesis.

The fracture of the hexagonal head away from the screw's main body is the most common type. A loose screw is more likely to experience significant sideload. An implant abutment screw fracture can be a serious setback since the implant's ability to operate effectively is compromised by the residual piece inside the implant. Occlusal forces drop by 200 to 300 N when patients wear an implant-supported prosthesis, whether it is fixed or detachable. When lateral forces surpass 370 N for abutments with a minimum joint depth of 2.1 mm and 530 N for abutments with a minimum joint depth of 5.5 mm, implant abutments fail.

Compared to implants with a larger diameter, those with a lower diameter—between 4 and 3.75 mm—are more likely to fracture. According to reports, an implant with a 5 mm diameter is three times stronger than one with a 3.75 mm diameter, and an implant with a 6 mm diameter is six times stronger than one with a 3.75 mm diameter. Table 2 lists the risk variables for implant components, which are divided into three categories. By using specific techniques, the risk of abutment screw fracture and loosening can be decreased. These consist of routine follow-up appointments, adjusting the implant to the appropriate torque, comprehending the occlusal scheme, and meticulous treatment planning.

Tabel 2. Risk factors relating to dental implant fracture.