Static Surgical Guides: Tooth-, Mucosa- or Bone-Supported — Which Guide for Which Case?

The tissue a surgical guide rests on determines its stability, its access to the surgical site and, according to systematic reviews, part of its accuracy. Three support families, what three literature reviews report, and a selection grid by type of edentulism.

A static surgical guide transfers the implant plan made on the CBCT and the digitised dental surface to the chairside: virtually positioned guide sleeves dictate the axis and depth of drilling. This transfer is only reliable if the guide returns to exactly the same place every time. The structure it rests on — its support — therefore determines its stability, the surgical approach and part of the final error. This article compares the three support families, summarises what three systematic reviews published in Clinical Oral Implants Research allow us to say, and proposes a selection grid. It is written for practitioners: it replaces neither training in the guided surgery system used nor clinical judgement.

1. Three Support Families

Guides are classically divided into tooth-, mucosa- and bone-supported, to which are added mixed guides (for example teeth and mucosa in an extended partial edentulism). On the header illustration, a mandibular plan, the translucent guide body carries sleeves (white cylinders) aligned with the axis of each implant (green, extended in yellow), the course of the inferior alveolar nerve is traced in orange and three fixation pins (markers FIX1 to FIX3) anchor the guide in the bone. This is the logic shared by all three families: a guide only guides well if it is immobilised.

2. What the Systematic Reviews Report

Three reviews published in the same journal between 2009 and 2018 structure the available data on static guides. Their conclusions complement rather than contradict each other.

Three practical lessons. First, the order of magnitude: a static guide is not accurate to a tenth of a millimetre, and the 2 mm safety margin called for by Tahmaseb et al. is not a theoretical precaution. Second, support matters: the 2017 review concludes that the supporting tissue influences accuracy, with tooth and mucosa support outperforming bone support in the pooled analysis — an advantage that the analysis restricted to retrospective studies does not find for the entry point and apex. Third, the type of support is linked to the type of edentulism: tooth support is mostly met in partial edentulism, mucosa and bone support mostly in complete edentulism, where accuracy is lower. The two effects cannot therefore be separated in the data; this reading is our own inference, not a finding of these reviews.

3. Which Support for Which Case: A Decision Grid

The grid below summarises the usual logic. It replaces neither case-specific planning nor the recommendations of the manufacturer of the system used.

4. Securing the Seating: Seven Checks Before Operating

• Try the guide on the printed model or in the mouth before anaesthesia, using the inspection windows where they exist
• Fix the guide with pins or screws whenever the support is mucosa or bone, and check after each drill pass that it has not moved
• Check the fit after sterilisation or storage: a deformed guide must be remade, not forced
• Check data consistency: in complete edentulism, the scan prosthesis must be perfectly stable in the scanner and the radiopaque markers correctly recognised by the software
• Measure mouth opening and available height: sleeve, key and drill must fit in the space, especially in the posterior region
• Respect a safety margin of at least 2 mm around the inferior alveolar nerve, the sinus and neighbouring teeth (Tahmaseb et al., 2018)
• Keep a fallback plan: know how to continue freehand or postpone if the guide does not seat, then check the actual position on the postoperative CBCT to document the deviation

5. Limits of the Data

The three reviews stress the heterogeneity of techniques, software, manufacturing processes and study designs. The 2018 review rests on a single randomised controlled trial, eight uncontrolled retrospective studies and eleven uncontrolled prospective studies. These works mainly measure the accuracy of implant position, not long-term survival or patient satisfaction, and their means cannot be transposed as such to a given system, printer or operator. Systematically superimposing the postoperative CBCT on the plan remains the best way to know one’s own accuracy.

Key Takeaways

• The support of the guide determines its stability, the surgical approach and part of the accuracy.
• Tooth support: preferred when the remaining teeth are sufficiently numerous, stable and well distributed.
• Mucosa support: minimally invasive, but subject to mucosal mobility; fixation and seating checks are essential.
• Bone support: rigid seating and a view of the bone, at the cost of a flap.
• Whatever the family, plan a safety margin of at least 2 mm and check the position obtained.

References

• Schneider D, Marquardt P, Zwahlen M, Jung RE. A systematic review on the accuracy and the clinical outcome of computer-guided template-based implant dentistry. Clin Oral Implants Res. 2009;20(Suppl 4):73–86.
• Raico Gallardo YN, da Silva-Olivio IRT, Mukai E, Morimoto S, Sesma N, Cordaro L. Accuracy comparison of guided surgery for dental implants according to the tissue of support: a systematic review and meta-analysis. Clin Oral Implants Res. 2017;28(5):602–612. doi:10.1111/clr.12841
• Tahmaseb A, Wu V, Wismeijer D, Coucke W, Evans C. The accuracy of static computer-aided implant surgery: a systematic review and meta-analysis. Clin Oral Implants Res. 2018;29(Suppl 16):416–435. doi:10.1111/clr.13346