# Heat Generated during Dental Implant Placement: A Scoping Review
## 2 Materials and Methods
### Speed (RPM)  
The revolutions per minute (RPM) employed in osteectomies have always been a subject of debate. Several studies have analyzed this variable, yielding conflicting results. While it might seem intuitive to think that as speed increases there is a proportional increase in temperature, several studies have revealed the opposite.  
A 1997 study by [PERSON] et al. demonstrated an inverse relationship between speed and heat generation. This study compared speeds of 2000, 30 k, and 400 k RPM, and found that as speed increased, heat generation decreased during osteotomy [28]. In a study by [PERSON] et al., three different groups of milling speeds were analyzed: 1500, 2000, and 2500 RPM. This study examined different diameters (2 mm versus 2.8 mm) and forces applied during milling (1.2 kg and 2.4 kg). Regardless of diameter and force, maximum heat generation occurred at a milling speed of 2000 RPM [29]. Other studies, including the study by [PERSON] et al., report no significant differences when comparing speeds of 1000, 1500, 2000 RPM [25].  
In a study by [PERSON] et al., the authors reported that doubling instrument rotation speed did not result in significant temperature changes, suggesting a better execution practice and reduced operating time [30]. The study by [PERSON] et al. found that higher speeds led to lower heat generation when comparing speeds of 1225, 1667 and 2500 rpm. According to the authors, this was also due to the speed at which the osteotomy was performed and therefore the real milling time. To reach the 8 mm depth point, the higher RPM drills took less time, causing less friction time and therefore generating less heat. The time required for the bone to return to basal temperature was also quantified in this study; this time was directly proportional to the time necessary for the milling phase. The authors of this study recommended waiting 30 to 60 s between drills to allow the bone to return to basal temperature [31].  
[PERSON] et al. compared speeds of 1000, 1500, and 2000 RPM and found that, even when varying the diameters to 3, 35, and 4 mm, higher speeds led to lower heat generation, shorter working and milling times, as well as reduced temperature variations [32]. Similarly, [PERSON] et al. compared speeds of 1250, 2000, and 2500 RPM and also found that the lowest temperature values were achieved at 2500 RPM, accompanied by reduced milling times and heat generation compared to lower speeds [33].  
[PERSON] et al. found safe a 50 RPM drilling protocol in their study, even without irrigation [34]. Similar results were found by [PERSON] et al. [35], [PERSON] et al. [36], and [PERSON] et al. [37].  
Lower milling speeds enable, at the expense of greater heat generation, better control of movement. This is particularly important when in proximity to vital structures like the maxillary sinus and the inferior alveolar nerve. However, all studies reviewed here reported temperature values below the literature-reported limit of 47 degrees for one minute. Given these findings, adhering to manufacturer-recommended speeds seems to be a reasonable approach for optimizing outcomes during osteotomy.