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Freehand vs. Guided Surgery: Clinical Considerations and Case Examples

SIAMAK ABAI, DDS, MMedSc

by Siamak Abai, DDS, MMedSc


When treatment planning dental implant therapy, one of the biggest questions practitioners face is whether to employ freehand or guided surgery. As with many clinical considerations, the correct answer to this question is contingent upon the unique circumstances of each case and the preferences of the practitioner. Freehand surgery, in which a flap is reflected and the implant is placed according to the available diagnostic information, is a cost-effective approach that is advantageous in many cases. Guided surgery, in which the osteotomy is created through a digitally designed and printed surgical guide, has the potential to afford the highest level of precision and control, and can be invaluable depending on the complexity of the case and the anatomy of the patient.1

The chosen method of surgery affects many aspects of the case, including the diagnostic evaluation, treatment planning, accuracy, patient comfort, and the cost, duration and prosthetic outcome of treatment. Exploring the advantages and disadvantages of each approach, along with case examples, can help clinicians arrive at an informed decision.

Freehand Surgery

In freehand surgery cases, periapical and panoramic radiographs are used to assess the bone available for implant placement as well as the surrounding anatomy. Traditionally, periodontal probes, gauges or calipers have been used during the intraoral examination for bone sounding, which offers a reasonable idea of the height and thickness of the ridge. Further, the surrounding teeth can be used as guides for determining the correct positioning of the implant, noting, for example, that the implant should be placed at least 1.5 mm from any neighboring dentition and 2 mm apical to their cementoenamel junction.

A study cast can be fabricated, upon which measurements can be made to provide a better understanding of the mesial-distal and apico-coronal space available in which to place the implant. Additionally, a diagnostic wax-up can help plan the surgical procedure in a manner that positions the implant to best support the eventual prosthesis. A surgical stent can be fabricated according to the diagnostic wax-up in order to serve as a clinical tool for evaluation of implant position at the time of surgery. During the surgical procedure, the bone underlying the implant site can be evaluated directly and measured with bone calipers after opening the flap.

The availability of CBCT scanning gives practitioners an option that allows for extremely accurate evaluation of these characteristics in three dimensions. Note that although CBCT scanning is most commonly associated with guided surgery, there are cases in which the scan reveals that there is adequate bone and the implant site is a safe distance from critical anatomical landmarks. This indicates a freehand surgical approach in many cases, especially when cost is a concern for the patient. With freehand surgery, the cost to the practitioner is essentially the dental implant and the basic instrumentation needed to place it, resulting in a substantially lower fee for the patient.

Further, collecting the data required for digital treatment planning and guided surgery can require multiple appointments. Thus, when case circumstances indicate that freehand surgery can be safely and predictably executed, this approach will appeal to patients and doctors alike due to the reduced chair time. In some cases, the implant can be placed freehand on the same day that the patient comes in for the initial consultation.

Another advantage of freehand surgery is the capability to manage the keratinized soft tissue, which is often less available after a tooth is lost and the residual ridge has resorbed. One method of reestablishing the gingival contours is to position the surgical flap apically and buccally during freehand surgery.2 This can help establish a situation in which the neck of the implant is surrounded by the 2–4 mm of keratinized tissue needed for healthy and esthetic gingival contours, margins and interdental papillae.

Because a flap must be reflected to perform freehand surgery, the clinician is able to directly visualize the bone, which can be advantageous in many cases. Also, if bone augmentation has been performed and the effectiveness of the grafting procedure needs to be assessed prior to implant placement, reflecting a flap is quite helpful in evaluating whether the graft has successfully integrated with the ridge. While a CBCT scan can offer a reasonable idea of the grafting procedure’s effectiveness, it can be difficult to ascertain the exact quality of the bone without observing the implant site directly.

Although freehand implant placement is a more surgically driven approach, a surgical stent based on a diagnostic wax-up can be used during the procedure to help visualize the planned restoration. The thermoformed appliance is seated over the edentulous space during implant surgery. The stent includes the shape of the planned restoration and an opening for the surgical drills, helping position the osteotomy in alignment with the eventual prosthesis.

Guided Surgery

In guided surgery cases, CBCT scanning and digital intraoral impressions are used to generate a virtual representation of the patient’s jaw and oral anatomy. This is utilized to develop a digital treatment plan in which the exact position of the implant is determined in advance of treatment. A surgical guide is fabricated that controls the osteotomy in precise accordance with the preplanned implant position. The depth, angulation, and mesial-distal and buccal-lingual location of the implant osteotomy are precisely controlled by titanium sleeves situated within the surgical guide.

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Proper positioning of a dental implant 2 mm apical to the cementoenamel junction of and 1.5 mm from the adjacent teeth.

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Execution of a freehand osteotomy through a prosthetic stent, which is included with the Inclusive® Tooth Replacement System (Glidewell Laboratories; Newport Beach, Calif.).

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An osteotomy being created through a surgical guide, which strictly controls the depth and angulation of the implant.

The superior level of accuracy afforded by this approach makes it ideal in situations where there are concerns related to bone volume and the proximity of vital patient anatomy such as the inferior alveolar nerve, sinus and neighboring teeth. In cases of narrow ridges or other instances of limited anatomical space, guided surgery simplifies the task of situating the implant within the available bone. In full-arch indications, guided surgery should always be a strong consideration provided the complexity of such cases and the less invasive nature of the procedure, atraumatic healing process, and the complete control it affords of the inter-implant positions.

Guided surgery is also more prosthetically driven, which is beneficial provided the growing emphasis on final esthetics in implant therapy. The digital treatment-planning element of guided surgery allows the practitioner to begin with the ideal restoration and work down to the implant position. While this approach can be adopted in freehand cases, the precision and control afforded by guided surgery enable the clinician to position and angulate the implant for the most esthetic restorative outcome possible.

A drawback of guided surgery is the higher cost. In addition to the expense of the guide itself, the intraoral scanner and CBCT scanning equipment involved in producing the data needed to fabricate a surgical guide require significant financial investments. For practitioners who do not invest in their own scanning equipment, the cost on a per-case basis is substantially higher.

In cases where cost is not an issue for the patient, guided surgery should be more strongly considered. For patients with limited finances, freehand surgery can offer a more economical approach so long as the circumstances of the case are relatively straightforward and the potential complications, anatomical or otherwise, are minimal. When there is adequate keratinized tissue, the patient can be provided with both options, along with an explanation of the cost differential and the benefits of the more costly approach.

Case Example #1: Freehand Implant Placement

A 54-year-old female with an existing implant, prefabricated stock abutment, and cement-retained crown in the area of tooth #30 presented with pain in the proximity of the restoration, which had been in place for approximately two years (Fig. 1). Intraoral and radiographic examination revealed a significant amount of crestal bone loss and soft-tissue inflammation surrounding the implant. This was likely the result of residual excess cement from the crown delivery appointment. Note that the crown was delivered over a stock abutment, which can make the cleanup of residual cement difficult due to the subgingival platform of the abutment and margins of the crown. To avoid such complications, custom implant abutments, which are produced with proper gingival contours precisely designed to follow the soft-tissue anatomy and thus ease cement cleanup, or screw-retained crowns are recommended.

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Figure 1: The patient presented with a failing implant restoration in the area of tooth #30.

Provided the unfavorable prognosis for the patient’s existing implant, a treatment plan was proposed in which it would be removed and a bone augmentation procedure performed. After healing of the bone graft, a new dental implant would be placed to support a screw-retained crown. Freehand surgical placement was selected for the case, as a flap would need to be reflected in order to visualize the implant site after the bone graft had healed. Although guided surgery was an option, the planned implant position was a safe distance from any vital patient anatomy, and it was important provided the case circumstances to clinically feel and visualize the bone during the surgical procedure.

It was important provided the case circumstances to clinically feel and visualize the bone during the surgical procedure.

The patient agreed to the treatment plan and returned two weeks after the preliminary examination for the removal of her existing implant restoration. First the implant crown was removed, revealing substantial inflammation in the peri-implant soft tissue (Figs. 2a, 2b). The implant was then removed (Figs. 3a, 3b). The socket left by the removed implant and the surrounding ridge were curetted and augmented with a xenograft material to reestablish the horizontal and vertical volume needed for a new implant (Figs. 4a, 4b). The site was sutured (Fig. 5).

After a healing period of approximately four months, the patient returned for evaluation (Fig. 6). With the healing of the hard and soft tissue deemed sufficient for the placement of a new implant, a surgical flap was reflected (Fig. 7). The osteotomy was created utilizing the manufacturer-recommended sequence of drills, following a traditional surgical protocol (Fig. 8). A 3.5-mm-diameter Hahn™ Tapered Implant (Glidewell Direct; Irvine, Calif.) was threaded into the implant site with relative ease (Fig. 9). With excellent initial stability established, a healing abutment was placed (Fig. 10). Complete seating of the healing abutment was verified radiographically (Fig. 11). Lastly, the flap was sutured, completing a relatively straightforward freehand implant placement procedure (Fig. 12).

Four months later, the patient returned for final impressions (Fig. 13). After assessing the soft tissue and confirming adequate implant stability, a transfer coping was seated and a vinyl polysiloxane impression was made so the final screw-retained crown could be produced (Figs. 14a, 14b). The lab fabricated a master cast from the final impression upon which the screw-retained BruxZir® Solid Zirconia crown was designed. The contours of the final crown were carefully created using dental CAD software to conform precisely to the gingival anatomy at the implant site.

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Figure 13: After completion of the healing phase, the patient presented with healthy gingival tissue surrounding the implant site.

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Figures 14a, 14b: A transfer post was seated, and a VPS impression was made, capturing the precise position of the implant and the surrounding gingival anatomy.

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Figures 14a, 14b: A transfer post was seated, and a VPS impression was made, capturing the precise position of the implant and the surrounding gingival anatomy.

The final BruxZir crown was delivered without complication, establishing an accurate fit and a natural-looking emergence profile despite the hard- and soft-tissue limitations present at the time of initial consultation (Fig. 15). Final radiography exhibited stable levels of crestal bone surrounding the Hahn Tapered Implant (Figs. 16a, 16b). The final result provided the patient with an excellent long-term prognosis, overcoming challenging circumstances to achieve an esthetic restoration (Fig. 17).

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Figure 15: The final BruxZir® Solid Zirconia screw-retained crown was delivered over the Hahn Tapered Implant. Camouflage composite was used to seal the screw access hole.

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Figures 16a, 16b: Side-by-side comparison of preoperative radiograph of compromised implant (16a) and final radiograph with new Hahn Tapered Implant (16b) illustrates complete osseointegration as well as regeneration of the crestal bone.

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Figure 17: The patient was extremely pleased with the final restoration, the CAD/CAM design of which established ideal gingival margins.

Case Example #2: Guided Surgery

A 55-year-old male presented for treatment with a missing second molar and in good general physical health (Figs. 1a, 1b). After thorough intraoral and extraoral evaluation, guided implant surgery was proposed to and accepted by the patient, who wanted treatment to be as efficient and painless as possible. The initial CBCT scan and periapical radiograph indicated sufficient vertical and horizontal bone (Figs. 2a, 2b). Because bone grafting was unnecessary and there was adequate keratinized tissue present at the implant site, a flap would not need to be reflected, making the flapless approach facilitated by guided surgery ideal. Further, the added expense was not an obstacle for the patient.

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Figures 1a, 1b: The patient presented with an edentulous space in the area of tooth #30.

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Figures 1a, 1b: The patient presented with an edentulous space in the area of tooth #30.

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Figures 2a, 2b: Radiography and CBCT scanning indicated adequate bone volume for the predictable placement of a dental implant.

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Figures 2a, 2b: Radiography and CBCT scanning indicated adequate bone volume for the predictable placement of a dental implant.

A data collection appointment was scheduled to gather the information needed to produce a digital treatment plan and surgical guide. A digital intraoral impression was taken using an intraoral scanner, the use of which offers improved accuracy by eliminating the distortion that can occur with conventional vinyl polysiloxane materials and stone casts. This information was then combined with the CBCT scanning data to produce a digital treatment plan. This included a virtual representation of the implant restoration site as well as the surrounding patient anatomy and dentition (Fig. 3). This digitization of the patient’s arch was used to treatment plan the placement of the implant within a maximum amount of bone and a safe distance from important anatomical landmarks.

Once the implant position that would best support a functional, esthetic restoration was determined, a surgical guide was designed that would precisely control the location of osteotomy (Fig. 4). Following fabrication of the surgical guide, the patient was called in for the placement of a Hahn Tapered Implant.

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Figure 3: Virtual representation of the patient’s mandible used to preplan the placement of the dental implant.

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Figure 4: Digital treatment planning software was used to design a tooth-supported surgical guide.

First, the surgical guide was tried in to verify the fit of the appliance prior to anesthetizing the patient (Fig. 5). Then, after infiltrating the area with minimal local anesthetic, a tissue punch was used to access the implant site (Fig. 6). The osteotomy was created through the surgical guide following the straightforward drilling protocol of the Hahn Tapered Implant System. A 5.0-mm-diameter implant was placed using an implant driver (Figs. 7a, 7b). With favorable primary stability established, a healing abutment was attached to the implant (Figs. 8a, 8b).

After three months of healing, the patient returned for final impressions. After removing the healing abutment, healthy tissue was observed at the implant site, and stability of the implant was confirmed (Fig. 9). A transfer coping was placed, and a final impression was made using vinyl polysiloxane (Figs. 10a, 10b).

Based on the final impression, the lab produced a screw-retained BruxZir Solid Zirconia crown (Fig. 11). Monolithic zirconia was the material of choice for its strength, esthetics and compatibility with the soft tissue. The final restoration was delivered without complication (Figs. 12a, 12b). The precision and restorative-driven approach facilitated by guided surgery ensured the implant was positioned for an esthetic prosthetic outcome. The final periapical radiograph displayed excellent crestal bone levels in the area of the Hahn Tapered Implant (Fig. 13).

Monolithic zirconia was the material of choice for its strength, esthetics and compatibility with the soft tissue.

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Figure 11: The final screw-retained crown was fabricated from BruxZir Solid Zirconia.

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Figures 12a, 12b: Final screw-retained crown in place after sealing the screw access hole with Camouflage composite.

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Figures 12a, 12b: Final screw-retained crown in place after sealing the screw access hole with Camouflage composite.

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Figure 13: Final radiograph demonstrates stable bone levels around the Hahn Tapered Implant.

Conclusion

Both guided and freehand surgery have their place in the modern implant practice. The circumstances of each case and the situation of the patient ultimately dictate which approach to adopt. The cost-benefit analysis of guided surgery should include a careful assessment of bone levels, the keratinized soft tissue, and whether the increased level of precision is worth the added expense. Even as the cost of CBCT scanning and guided surgery inevitably decreases due to competition, there will always be cases well-suited to a freehand approach.

References

  1. Noharet R, Pettersson A, Bourgeois D. Accuracy of implant placement in the posterior maxilla as related to 2 types of surgical guides: a pilot study in the human cadaver. J Prosthet Dent. 2014 Sep;112(3):526-32.
  2. Bruschi GB, Crespi R, Capparé P, Gherlone E. Clinical study of flap design to increase the keratinized gingiva around implants: 4-year follow-up. J Oral Implantol. 2014 Aug;40(4):459-64.
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