**2. Characteristics of implants, proposed changes and results obtained**

#### **2.1 Surface treatments**

The first dental implants were developed without any type of surface treatment, they were carried out by a machining process, which resulted in implants with a smooth surface. For a long time, this implant was conceived as the gold standard. Experimental studies comparing smooth and rough surfaces demonstrate a better biological response to the latter. With the evolution of implantology, changes in implant surfaces began to be carried out in order to improve osseointegration [6].

The processes of changes in the surface of implants can be carried out by the addition method, when some type of material is added to the layer by means of plasma spray coating, or subtraction, when part of this surface layer is removed by physical and/or chemical processes, such as abrasion by blasting or acid etching [7]. The texturing of the implant surface can influence the osseointegration process both in cell differentiation, after implant placement, and in the amount of calcified bone matrix [7, 8]. Thakral et al. [9], reported that texturing techniques in dental implants can influence the establishment of osseointegration, both for cell differentiation, after implant insertion, and for calcified bone matrix. Also, according to Wennerberg and Albrektsson [10], the treated surfaces result in greater bone/implant contact (BIC), compared to smooth implants. Thus, implants with textured surfaces are indicated for sites with a lower BIC at the end of surgery. On the other hand, Att et al. [11], state that bone is indistinctly deposited on porous or smooth surfaces. Therefore, porosity would not be a necessary condition for bone apposition to occur.

Regarding the initial stability of the implants, the surface treatment of the implants does not change the initial stability values of the implants, as shown in studies comparing the insertion torque and stability analysis by resonance frequency using implants with the same design with and without surface treatment [12, 13].
