This study evaluates the accuracy of implant placement by using an implant positional guide versus freehand. The parameters for assessing deviation included (a) coronal deviation, (b) apical deviation, (c) angular deviation, (d) vertical deviation. In this study, we found an overall degree of deviation was significantly lower in guided surgery with implant positional guide approach than the freehand. From all aspects of compatibility of restoration such as functional, esthetical and biological, implants must be placed correctly in an ideal position. Correct implant position not only has favored prosthetic and esthetic outcomes it has also shown long-term stability of peri-implant hard and soft tissues [23].

By introducing guided surgical protocol, static computer-assisted implant placement (sCAIP) helps clinicians to overcome these difficulties. In sCAIP, a digitally designed surgical guide is used to precisely control osteotomy preparation and implant placement. sCAIP approach shows greater accuracy in implant placement, reduces the necessity of invasive adjunctive procedures and bone augmentation, and prevents patient distress. There are two variations of sCAIP namely fully guided (FG) placement and partially guided(PG) placement [24]. In guided surgery, a surgical guide act as a tool that helps in the transfer of a digital surgical treatment plan to the patient [25]. The implant positional guide simplifies the surgical procedure with the precise position of the first drill, the operator does not have to check the axial repeatedly. It helps the clinician to simplify the surgical procedure starting from the diagnostic phase up to the restoration-oriented design [26], thereby helping in the accurate placement of the implant which results in a commendable esthetic and prosthetic outcome [23].

The observed accuracy of the implant positional guide in comparison to freehand in the present study is similar to other reported studies. According to the study of Jaffar Abduo et al. The FG (fully guided) implant shows less deviation than PG (partially guided) and FH (freehand), while the FH implants appeared to have the greatest deviations and variations in most of the variables. On the other hand, PG placement is more accurate than the FH especially, since the coronal and apical accuracy is at a similar level to the FG placement [24]. A randomized controlled trial implemented by Palita Smitkarn et al. showed the median deviations of surgery guide implants in angles, shoulders, and apexes were 2.8 ± 2.6°, 0.9 ± 0.8 mm, and 1.2 ± 0.9 mm, lower than the implant positional guide group [27]. Although the accuracy of FG is higher than PG and FH due to technological advancement [24], the FG protocol is still prone to error. This error can occur at any step of planning, guide fabrication, and implant placement procedure [25].

Although FG protocol has higher accuracy among PG and FH, it is more costly due to the need for a special kit, and the treatment procedure is time-consuming. The present study shows the use of the implant positional guide is cost-effective because it does not require the design of different surgical guides for different implant systems. It uses only a first drill, a metal sleeves and the corresponding drill handles are not required. M. Tallarico et al. demonstrated that when limited space is available, an implant placed using a surgical guide without metal sleeves is more accurate. The non-metal sleeve of small diameter is recommended to reduce lateral drill movement and instrument tolerance [28]. In a nutshell, by controlling the accuracy of the first drill, the implant positional guide has higher accuracy than freehand implants and has less difficulty handling than a regular surgical guide, which also helps reduce the financial burden on the patients. It is a promising technology that guarantees a low cost and high precision of implant surgery.

While the accuracy of the first drill has a significant impact on the final accuracy of the implants, it cannot be ignored that during surgery, when the implantation cavity is enlarged, the implantation position and direction may gradually shift. We think it is workable to control the final implantation position with the implant positional guide. Due to the low cost of the implant positional guide, we can fabricate another guide to match the final drill to control the final implant position. We expect that this can be confirmed in further clinical trials. In addition, all implant surgeries in this clinical trial were flap surgeries. Flapless surgery using the implant positional guide was not performed. We believe that whether there is a difference between the implant accuracy of flap and flapless implantation procedures can be verified in further clinical trials.

The implant positional guide uses model resin material as the 3D printing material, which not only can guarantee a certain strength but also can greatly reduce the cost. However, the model resin material also has disadvantages. It is less strong and has a shorter storage time compared to common surgical guide instruments. It may also be deformed, affecting the precise position of the implant. In addition, as the implant positional guide does not require a metal sleeve, it may produce contamination during the implantation process. But since the guide only needs to be used at the first drilling, the contamination it produces can be washed away immediately. There are no cases of infection in current clinical practice.

Unlike the precise positional of the implant depth of the surgical guide, the implant positional guide needs to observe the graduated line during the implant procedure to determine the implantation depth. Since the graduated line may be partially obscured by the guide or have a limited field of view in case of insufficient mouth opening, the final vertical deviation values are probably closer to the freehand planting measurements.

Despite the simplicity of the use of the implant positional guide, it has certain limitations such as it cannot be used in complex cases for example in multiple missing teeth and edentulous patients. The use of resin makes the production economical but may compromise the strength so the clinician must be cautious while using it. Due to ethical considerations, the implant method is chosen by the patients, complete randomization cannot be guaranteed and could not ignore the presence of selective bias. In addition, blinding could not be guaranteed due to the large difference between the guide and freehand implant methods, which may have an impact on the comparison of implant accuracy between different implant methods. Therefore, it must be acknowledged that the results of the test are limited.