## 4 Discussion
### Number and Length of Microthreads  
Another interesting aspect is the length of the crest module and consequently the number of microthreads. The number of microthreads varies depending on the size of the implant and typically ranges between 3 and 15. Similarly, the length of a dental implant crest module can vary depending on the size and type of implant being used. Generally, the length of a crest module ranges from 0.5 to 4 mm. We have not found any clinical studies with which to compare our results. Only one study using FEA has addressed this topic. According to this work, a length of 3 mm is recommended, especially if the implant is to receive oblique or horizontal loads [46]. However, in our five-year clinical study, we found no such differences between implants with a length of 1 mm and three microthreads or a length of 3 mm and nine microthreads. We observed that the Ticare Inhex Quattre (three microthreads, 1 mm in length) and Ticare Inhex Standard (nine microthreads, 3 mm in length) implants did not show a statistically significant difference in the marginal (B.L.) after 5 years of function. There were also no statistically significant differences in the clinical variables (plaque index, bleeding index, probing depth, and presence of recession). As mentioned above, we have not found similar clinical studies with which to compare our results. The clinical studies we found have a mean follow-up ranging from 3 to 12 months [6; 23; 41; 42; 43; 47]; one study had a follow-up period reaching 3 years and up [48], and two studies had a follow-up period of 5 years [49; 50]. A study by [PERSON] et al. [50] was performed with delayed implantation and showed good performance for implants with platform switching, microthreads, and a rough surface (SLA). Their results are consistent with ours; however, this study lacked a control group. The second study we found with results after 5 years reported no difference between the presence or absence of microthreads [49]. However, this study evaluated insertion after immediate implantation, and as has been demonstrated, this technique does not prevent bone resorption, regardless of implant design. It has been mentioned that immediate implant installation is conducive to predictable osseointegration and high survival rates but fails to prevent bone remodelling and dimensional reduction of the alveolar ridge [51]. Most of the relevant studies have been performed using FEA models, which should be assessed more qualitatively than quantitatively due to the need for a precise fit. Among the FEA studies most similar to our study, we found one that studied the presence of microthreads over a length of 1, 2, or 3 mm [46]. These researchers concluded that a length of 3 mm yielded the best results, especially for implants subjected to nonaxial loads. Another study investigated different histomorphometric bone changes around non-submerged implants with different machined collar lengths (1.6 vs. 0.4 mm) in a dog model. The researchers concluded that crestal B.L. changes were reduced when implant necks with a rough surface were used [31]. On the other hand, reviews, systematic reviews, and meta-analyses have yielded controversial results due to the heterogeneity of the included studies [30; 35; 44]. The exact effect of subcrasal insertion on dental implant stability is still under investigation. However, research has shown that subcrasal insertion may help improve implant stability and reduce the risk of failure. Studies have demonstrated that inserting a dental implant slightly subcrasal can help increase primary stability, reduce micro-movement, and improve implant osseointegration. Additionally, subcrasal insertion may help reduce crestal bone resorption and decrease the risk of implant failure. Currently, many of the accepted paradigms have been questioned. In order to guarantee an adequate clinical outcome, we no longer look for the longest and widest implants possible, since short but well-designed implants are capable of obtaining an adequate clinical outcome [52].