The Effect of Undersized Drilling on the Coronal Surface Roughness of Microthreaded Implants: An In Vitro Study  
[PERSON]  
1 Department of Periodontology and Dental Implantology, School of Dental Medicine, Tel-Aviv University, P.O. Box 39040, Tel Aviv 6997801, Israel; [EMAIL_ADDRESS] (O.M.); [EMAIL_ADDRESS] (T.G.); [EMAIL_ADDRESS] (R.K.)1 Department of Oral Rehabilitation, School of Dental Medicine, Tel-Aviv University, P.O. Box 39040, Tel Aviv 6997801, Israel; [EMAIL_ADDRESS] (A.B.); [EMAIL_ADDRESS] (Z.O.)1 Graduate student.1  
[PERSON]  
1 Department of Periodontology and Dental Implantology, School of Dental Medicine, Tel-Aviv University, P.O. Box 39040, P.O. Box 39040, Tel Aviv 6997801, Israel; [EMAIL_ADDRESS] (O.M.); [EMAIL_ADDRESS] (T.G.); [EMAIL_ADDRESS] (R.K.)1 Department of Oral Rehabilitation, School of Dental Medicine, Tel-Aviv University, P.O. Box 39040, Tel Aviv 6997801, Israel; [EMAIL_ADDRESS] (A.B.); [EMAIL_ADDRESS] (Z.O.)1 Graduate student.1  
[PERSON]  
1 Department of Periodontology and Dental Implantology, School of Dental Medicine, Tel-Aviv University, P.O. Box 39040, P.O. Box 39040, Tel Aviv 6997801, Israel; [EMAIL_ADDRESS] (O.M.); [EMAIL_ADDRESS] (T.G.); [EMAIL_ADDRESS] (R.K.)1 Department of Oral Rehabilitation, School of Dental Medicine, Tel-Aviv University, P.O. Box 39040, Tel Aviv 6997801, Israel; [EMAIL_ADDRESS] (A.B.); [EMAIL_ADDRESS] (Z.O.)1 Graduate student.1  
[PERSON]  
1 Department of Periodontology and Dental Implantology, School of Dental Medicine, Tel-Aviv University, P.O.  
the implant and, upon healing, may result in higher bone to implant contact (BIC) values, especially in low-density bone [7; 8]. During underdrilling, small fragments of bone are compressed towards the intertrabecular spaces and between the implant threads, promoting new bone formation [9]. The stresses created by implant placement in a reduced-diameter implant bed are called force-fitting stresses; they increase the insertion torque and may lead to decreased BIC [10]. Regardless of the technique used for osteotomies preparation--ultrasonic devices or drills [11]--primary stability is greater with a tapered implant design compared to a cylindrical implant design [12].  
Implant stability and BIC levels can be assessed by measuring the insertion torque and removal torque values. Undersized drilling combined with a rough implant design leads to higher insertion and removal torque values [5; 6; 13]. The cervical area of the implant greatly affects implant stability. During loading, the cervical area transmits stresses towards the crestal compact bone [14]. The highest stresses are centered in the area closest to the implant surface. In implants with a larger diameter, the stresses are better distributed [15].  
Various designs of the cervical aspect of the implant have been proposed to minimize marginal bone loss (MBL). These designs include both smooth and rough cervical collars as well as microthreads [16]. Microthreads are small, shallow threads that are added to the implant's cervical area to increase its surface area and minimize peri-implant bone loss [17].  
The increased surface area, in turn, allows for an improved distribution of tension and increased implant stability. In previous research, microthreaded implants have been demonstrated to lead to an increase in BIC values and a decrease in the extent of bone loss [18]. In addition, cervical microthreads absorb vertical forces and transform them into compression forces while decreasing the magnitude of shearing forces at the bone-implant interface [19].  
The aim of this study was to compare the effects of an underdrilling implant placement protocol and those of the manufacturer's recommended protocol on the insertion torque, implant surface temperature and topography of the cervical microthreads of implants.