# Heat Generated during Dental Implant Placement: A Scoping Review
## 2 Materials and Methods
### Irrigation (Internal Coolant, External Coolant, Temperature of the Coolant)  
Irrigation during the osteotomy phase also plays an important role in controlling intraosseous temperature and preventing temperature peaks. The literature on this subject is extensive and reports few contradictory results [20; 98; 99; 100; 101; 102; 103].  
Irrigation methods are categorized as external and internal irrigation. Several studies have shown that irrigation is one of the best methods, if not the best, to reduce heat production. External irrigation is considered sufficient to decrease the measured drilling temperature at the implant/bone tissue surface and avoid structural tissue damage [63; 65; 93; 104]. On the other hand, internal coolant drills have shown varied outcomes in reducing bone temperature, with some studies supporting their effectiveness [105; 106], while others do not [107].  
External irrigation is particularly effective during the most superficial osteotomy phases and is widely used today. Internal irrigation, though less common, is still valid, especially in cases of deep osteotomies. However, an additional source of coolant at 1.5 mm from the bone site does not improve heat dispersion compared to the external irrigation alone [78].  
[PERSON] et al., in 2018, found that double irrigation gave better results in reducing bone heating [106], even when trephine drills were used [120].  
[PERSON] et al. [38] compared the two irrigation methods, revealing that the effect of external irrigation is less effective in deeper osteotomy positions.  
While some studies have suggested internal irrigation is superior in controlling heat, even when used alone [107; 108; 109], other studies argue there is no significant difference when compared to external irrigation, mainly because the latter would act on bone that is less corticalized and therefore less susceptible to heat development [110].  
Another advantage of internal irrigation is that it increases drill lubrication during osteotomy and reduces the accumulation of bone debridement at the osteotomy site [100; 107; 109; 111].  
The other variable frequently discussed in the context of irrigation is the temperature of the irrigant. The reference temperatures for cooled sprinklers range between 0 and 10 degrees Celsius. Intermediate options fall between 15 and 20 degrees, while room-temperature irrigants generally exceed 20 degrees.  
Several studies have revealed a significant difference between room-temperature and cooled sprinklers [20; 29; 78; 84; 112; 113; 114; 115], even in case of guided surgery [67; 116]. In any case, data analysis indicates that even simple temperature control using room-temperature water prevents temperatures from exceeding the literature threshold of 47 degrees.  
Another important factor to consider during the osteotomy phase is the presence and design of a surgical guide. Some studies indicate that irrigants below 20 degrees have been found to be more effective, even when using surgical guides [91]. The study by [PERSON] et al. [117] highlights that the body of the guide can obstruct irrigation flow, necessitating the use of a dedicated irrigation system or internal irrigation to ensure proper cooling of the bone.  
After analyzing irrigation temperatures, some authors have questioned the flow and volume of irrigant used in the osteotomy phase. Some studies have shown that there is no significant difference between the different irrigant volumes (78; 100). Others have shown an important relationship between irrigation volume and temperature control (72; 118).  
Some protocols have also reported high survival rates and bone temperatures above the critical limit in the case of implant preparation without irrigation, though these studies challenge the prevailing literature (119; 120; 121; 35).