## 4 Discussion
Undetected loosening is a primary cause of screw fractures, with potential contributing factors including bruxism, unfavorable superstructure design, overload, rehabilitation malfunction, inadequate abutment seating, occlusal interferences, and manufacturing errors [1; 3; 6]. Screw loosening can occur when the forces acting to separate the screw joint, such as off-axis occlusal loads, exceed the forces holding the abutment and implant together. Additionally, screw fractures can arise from superstructure misalignment, overload, or malfunction [5]. Research has indicated that screw fractures are often associated with the external hexagon prosthetic connection [19], while implant systems equipped with anti-rotational features, such as an internal hex, tend to exhibit improved strength [19; 20]. These systems, along with those where the abutment is deeply integrated into the implant body, have shown lower rates of complications [21]. Consequently, implant manufacturers have begun designing more robust internal connections to reduce the risk of loosening and subsequent screw fractures [19]. Various techniques for extracting fractured screw fragments have been developed, each dependent on the initial condition of the fragment [20]. Conventional, conservative methods are often recommended as the first line of treatment. For instance, a dental explorer can be rotated counterclockwise to recover the remaining screw fragments, as suggested by previous studies [22]. Other effective techniques include the use of an ultrasonic tip, which has a reported success rate of 73.3% [7], cotton swabs [23], and Er-YAG lasers [24]. In cases where conservative methods fail, more invasive techniques, such as specialized rescue instruments designed by different implant manufacturers, may be employed. One such example is the IMZ TwinPlus Repair Set K 3.3 ([PERSON], Mannheim, Germany) [2; 21]. This method typically involves drilling the fragment to ensure retention before unscrewing it, as described by other researchers [25]. However, this procedure can be complicated and time-consuming for routine clinical use, as it risks damaging the threads within the implant [21; 25]. Previous research suggested the use of two burs: the first is a serrated #557 bur, which is used counterclockwise when the fragment is deep, and the second is a #33 % bur, which is used clockwise when the fragment is coronal for complete fragment extraction to avoid implant damage [26]. The use of these techniques can not only damage the implant but also compromise osseointegration, altering the implant-bone interface due to heat production [27, 28]. Overheating of osseous tissues can lead to irreversible damage. When bone is subjected to temperatures of around 47 \({}^{\circ}\)C for 1 min, this sometimes causes lesions in adipose cells and inconsistent tissue damage [29]. In cases of failure to remove the fractured screw fragment, other less invasive methods have been proposed to save the implant and avoid explantation. In addition, a previous study introduced a custom metal abutment into the implant, repositioning the implant-supported rehabilitation [30]. One study used shorter abutment screws as a replacement without prior removal of the remaining broken screw fragment [31], and another also used a shorter second screw to fix the implant-supported prosthesis, attaching it to the remaining fractured fragment without prior extraction [32]. Despite the use of these methods for fragment extraction, irreversible damage to implants can occur [25]. One study recommended that clinicians must be especially careful to avoid damaging the dental-implant connection, in addition to the implant access channel, when extracting the fractured screw [27].