Dental implant placement: How do freehand, guided, navigation, and robotic surgeries compare?

Compounding these errors may be what I will call "freehand misdirection." One such misdirection is social and emotional in context-what some have termed the "art" if not the "flamboyance" of dentistry. I'm talking about an internally marketed dental implant practice where one might find an x-ray screen as big as a home theatre television screen for the purpose of demonstrating the clinician's freehand artistic expertise to the client patient. What was intended to impress the patient-the gigantic, high-definition visual-may backfire, as the implant error is now on full display.

Freehand implant placement is metaphorically like free-range cattle ranching-the principle interest of the endeavor, ie, the implant, may wander and can be unpredictable. Over time, however, what happens with freehand utilization is that experience seems to trump occasional inaccuracy. With practice and acquired know-how, the ease of placing implants most of the time without the added cost or inconvenience of using a guide stent fosters confidence and routine for the clinician. This predictability eventually falls well in line with other clinical procedures that do not require guides, such as restorative dentistry or dental extractions.

When considering other, technically advanced implant placement protocols such as navigation or robotics, one must factor in the cost and training required. These expenses are not inconsequential, and the practitioner must decide whether these methods will be worth attempting from a time/cost benefit ratio. From a practical standpoint, for experienced clinicians the use of these extraneous methods, even a guide stent, is largely unnecessary in most implant placements. However, getting to that experienced state, through much training, practice, and repetition, is another matter. Novice clinicians tend to avoid freehand placement, setting up a scenario where continued and routine use of the more advanced methods is likely to make freehand placement an anachronism over time.

The use of freehand dental implant placement may become relegated to mature practitioners who learned their craft prior to the advent of new technology, such as robotics, navigation, or improved computer-guided methods, or it may wind up being used mainly in rural areas where access to technology might be limited.

Developed to improve implant placement accuracy and precision using a prosthetically driven approach, computed tomography (CT)-guided surgery workflows using surgical guides have been used and refined in implant dentistry for more than 15 years. The techniques are designed to avoid anatomy while implants are placed in a minimally invasive manner. The aim is to reduce tissue trauma, decrease patient postoperative pain and swelling, and improve outcomes. Moreover, once the clinician masters the surgical instrumentation and techniques, significant time savings can be achieved in patient cases involving two or more implants.

Dental implants are commonly placed "freehand," under direct bone visualization after incisions and reflection of soft-tissue flaps. Implants are then placed "by eye" or based on the surgeon's "best estimate," using conventional positioning "stents." The literature is replete with articles supporting the accuracy and predictability of guided surgery compared to freehand placement. The long-term cumulative survival rate for implants placed fully guided is comparable to implants placed freehand. More recently, technologies involving navigation and robotic implant placement have been introduced. There is no literature supporting improved accuracy and predictability of implant placement or enhanced avoidance of vital anatomic structures (eg, teeth, nerves, sinuses, implants) when comparing implants placed using navigation or robotic techniques versus implants placed via guided surgery. Robotic surgery has little definitive literature at all, which in this era of evidence-based patient treatment is troubling.

Guided surgery workflows for single-unit, multiple-unit, and full-arch implant placement have been established and proven, both in the laboratory and clinically, for many years. Multiple well-established software programs (eg, DTX Studio Implant^™, NobelBiocare, nobelbiocare.com; Simplant^®, Dentsply Sirona, dentsplysirona.com; coDiagnostiX^™, Straumann, straumann.com) designed, tested, and proven by major implant manufacturers exist for planning patient cases using guided surgery, and most manufacturers have instrumentation available for the guided placement of their dental implants. Most guided instrumentation kits from larger manufacturers are designed for "fully guided" implant insertion (implant placement through a surgical guide to final depth and angulation with integrated "stops"). Some manufacturers have produced guided dental laboratory componentry for the design and preoperative fabrication of provisional restorations for immediate insertion. No such instrumentation exists for navigation or robotic surgery; techniques are for osteotomies only.

All implant insertion technologies have a cost/benefit ratio. Although additional costs are involved in guided surgery compared with freehand, they are less than those associated with navigation and robotic surgery. The equipment used in navigation and robotic workflows can be very expensive and require substantial surgical operatory space. Additionally, manufacturer per-implant fees are common with these technologies.

Steep learning curves apply to all dental implant placement techniques. Guided implant placement in the second molar areas, with intact opposing dentitions, can be challenging in patients with limited mouth opening. With experience, techniques to overcome these obstacles become available. "Static" surgical guides used in guided surgery limit the surgeon's ability to alter the implant position during surgery. Guided surgery uses principles of reverse engineering in which implant positions are planned based on the intended restoration in relation to the underlying bony anatomy. Evaluation of bone quality and volume and decisions related to proper implant positions are made preoperatively during the planning phase, not intraoperatively.

The question of increased heat generation with static surgical guides has been debated, and though a slight increase in the heat generated at the apex of the osteotomy has been seen, the temperature does not reach levels dangerous to bone cellular health. Also, with guided surgery bulky handpieces and the need to limit patient head movement are non-issues.

To be clear, guided, navigation, and robotic technologies are not easier methods to place dental implants; they are more difficult and complicated methods than freehand. Clinicians should be highly experienced in freehand techniques before introducing any of these advanced technologies into practice.

"Navigation" is the term used for dental implant placement that utilizes computer-generated methods to guide an implant into a planned position. This includes dynamic navigation, static navigation, and robotic navigation. There is no doubt that any form of navigation is more proficient than a freehand approach. This assertion is founded on evidence-based clinical data in which the average deviation from the treatment plan was significantly less when navigation was used. Many freehand implants are placed within the same range of error; however, when taking into consideration a large sample size, navigation was better.

Dynamic navigation allows the surgeon to change implant sizes and position during the procedure. When using dynamic methods a guide stent is not in place. Implants can be placed easily in the second-molar locations, and the patient tracking arrays are typically small and manageable.

Robotic navigation involves a stronger arm than that used in dynamic navigation, providing more control over the positioning of the implant drills, which allows for vertical movement and resistance of lateral deviation. Used routinely in orthopedic surgery, robotic navigation has great potential for implant placement. It is, however, quite expensive and involves a large connection with the jaws for the tracking system.

Static guides utilize metallic sleeves to guide drills for implant site preparation. They are easy to use, reliably position implants, and can be utilized within the office setting to fabricate models for presurgical fabrication or preparation of provisional restorations. While dynamic systems also can be used to accomplish this function, the plan would need to be exported to a specific laboratory for fabrication of provisionals.

When deciding which type of system to use, if navigation improves implant positioning, then clinicians should use it for every patient, every time. In that regard the choice to use dynamic or static navigation is clinician dependent. Robotic methods undoubtedly will become more popular as their cost is reduced and the patient-specific arrays are less bulky.

I have been placing dental implants since their relative infancy in clinical practice, dating back to the 1980s. During this time, placement philosophy has changed in numerous ways, from placing implants in maximum bone to prosthetically driven surgery, to guided surgery, and, finally, to computer-guided surgery. I was fortunate to be involved in beta testing for the first NobelGuide^® (Nobel Biocare, nobelbiocare.com) surgical protocols, and even placed some of the first "teeth in an hour" and "teeth in a day" cases in the United States. Guided surgery was one of those "ah-ha" moments that offered a glimpse into the future and demonstrated how fast implant surgery demands would change.

For the past year, I have had the opportunity to be a "pioneer" user of a robot-assisted dental surgical system (Yomi^® Robotic Implant Surgery, Neocis, neocis.com) to place dental implants. While the system is in its early stages, I believe this technology is the next frontier in dentistry's efforts to provide even greater implant placement precision and accuracy. This particular robotic system allows for placement of implants in difficult anatomical situations in real-time without the use of a prefabricated surgical guide and with extreme accuracy. A cone-beam scan with the use of an in-office splint allows for immediate treatment and placement on the same day. The robotic arm controls depth of placement, mesial-distal and buccal-lingual widths, and any axial rotation. The surgeon has full control and must confirm all readings, and he or she has the ability to override the robot at any time. Also, the implant surgery may be performed fully in manual mode, if so desired.

The major advantage of robotic surgery comes at depth of placement. If, for example, a 10-mm implant is planned, the robot will not allow the surgeon to drill deeper than that. This provides a complete fail-safe. While an experienced surgeon usually is able to place an implant effectively in a buccal-lingual and mesial-distal direction, and guided surgery is useful here as well, guides can fall short on depth placement and allow inadvertent injury to occur to anatomical structures, even with the most careful planning.

Robotic surgery does require a significant learning curve, as it takes time to obtain a feel for the robot and to learn to trust it. Also, looking at a computer screen instead of the surgical site while operating is an adjustment that takes time to get used to. In talking to many of my physician colleagues who perform robotic surgery in other specialties, it may take well over 100 cases to acquire a comfort level. Another drawback is that the acrylic jig that needs to be fabricated against existing teeth is somewhat cumbersome in its existing format. This issue, however, is being addressed through our "pioneer" user group, and the jig fabrication soon will rely on a skeletal rather than tooth fixation. Currently, the robot is approved only for partially edentulous cases. The new fixation system will resolve this and enable the robot to handle fully edentulous cases.

Though only in its infancy in implant surgery, robotic surgery is revolutionizing other areas of medicine. I believe it is just a matter of time before it becomes the standard of care in implant dentistry.

Section Chief, Division of Oral and Maxillofacial Surgery, White Plains Hospital, White Plains, New York; Section Editor, Oral and Maxillofacial Surgery,Compendium; Private Practice
specializing in Oral, Maxillofacial, and Implant Surgery, Scarsdale, New York

Clinical Assistant Professor at New York University, University of Michigan, and University of Colorado at Denver; Diplomate, American Board of Oral and Maxillofacial Surgery

Committee on Continuing Education, American Association of Oral and Maxillofacial Surgeons; Private Practice specializing in Oral Surgery, Metairie, Louisiana

Clinical Instructor of Oral & Maxillofacial Surgery, Boston University Goldman School of Dental Medicine, Boston, Massachusetts; Chief of Oral and Maxillofacial Surgery, Milton Hospital, Milton, Massachusetts; Diplomate, American Board of Oral and Maxillofacial Surgery; Private Practice specializing in Oral Surgery, Quincy, Massachusetts