The Guide Does Not Seat: A Chairside Protocol for Surgery Day
Updated: Sep 25
Clinically reviewed by Jacob Shrayman, DDS, a general dentist who places implants using TrueGuide surgical guides in his own practice.
The patient is open, the flap is raised or the tissue is punched, and the guide will not go down. This is the article for that moment.
It is written the way we answer the phone when a doctor calls from the operatory, in the order we ask the questions. Nothing here is surgical technique or a decision about a particular patient — those are yours. What follows is what a laboratory knows about why guides do not seat, what can be relieved, what must never be touched, and how to get out of it cleanly.
Three Checks That Tell You It Is Seated
Do all three, dry, before any irrigation and before any drill touches it.
A positive stop. Seat it dry and feel it arrive. A guide that keeps creeping down under pressure is not seated, it is compressing something.
No rock under finger pressure at either end. Press one end, then the other. Any movement at all is a fail.
Contact through the seating verification windows on both sides. Look through and confirm tooth or ridge in contact, not a gap. The windows exist for exactly this. On an edentulous case, confirm the position against the bite index as well.
If any one of the three fails, stop there. Everything below is about why.
The Most Common Reason a Guide Will Not Seat
The mouth changed after the scan.
A temporary was replaced. A tooth was restored. A crown was recemented. Tissue swelled or healed. Someone adjusted a contact. The guide matches the record it was built from, and the record no longer matches the patient.
This is not a manufacturing failure and it is not fixable in the chair. A guide is a physical copy of the surface in the scan; if that surface moved, the guide is now built to a shape that no longer exists. The fix is a new scan and a new guide, which is why we ask you to re-scan after any change to the teeth or tissue the guide will sit on.
It is also the reason for the try-in at the bottom of this article. Five minutes at a consult visit turns this into a scheduling conversation instead of a surgery-day one.
The Second Most Common Reason
Something is binding that is not the seat.
An undercut on a tilted or rotated tooth. A tight interproximal contact. An overhanging restoration margin. A frenum or a flap edge trapped under the flange. A partial denture clasp path the design did not know about.
The tell is that the guide goes most of the way and stops hard at one point, and the windows show contact on one side and a gap on the other. Find the interference before you do anything else: seat it slowly and watch where it catches, or mark the intaglio with a thin layer of indicator and seat it once.
What You Can Relieve and What You Must Not
This is the part that decides whether the case is still guided.
You can relieve, lightly: a tissue undercut, a tight contact, or an interference on a surface that does not carry the seat. Small, controlled, with the guide out of the mouth, and re-check all three seating checks afterward.
You must never relieve the seating surfaces or the sleeve housing. The seating surfaces are the entire reference. Once they are opened up, the guide can drop deeper or tip, and every depth on the drill report is wrong by an unknown amount. The sleeve housing is the thinnest, most loaded part of the guide and the wall around the cylinder is where a guide fractures.
Put plainly: if the only way to make it seat is to grind the surface it seats on, the guide is finished. Go to the bailout sequence below.
When the Guide Rocks
Do not hold it.
A guide you are holding in place is a freehand case with a false sense of security, and it is worse than freehand because you are trusting a sleeve that is no longer pointing where the plan pointed. Angular error from a guide that moves is not small and it is not predictable.
Find the interference, or go freehand on purpose with the drill report in front of you. Both are defensible. Holding it is not.
On a tissue-supported or edentulous guide, rocking usually means either a fixation pin has not engaged or the tissue is compressing unevenly. On a tooth-supported guide it usually means an undercut on one abutment tooth, or support taken from a tooth that has since moved or been restored.
When One Fixation Pin Will Not Seat
Stop before you place the rest.
A pin that spins, engages nothing, or will not reach bone means the guide is not fixed, and on a stackable case it means the base is not fixed and every component above it has lost its reference. Bone softer than the CBCT suggested is the usual cause.
The decision is yours, but the laboratory's view is simple: an unfixed base is not a guided case. Either find purchase elsewhere in the planned pin path, or treat the case as freehand from that point with the plan as a reference.
When the Drill Cannot Reach the Sleeve
This is a planning problem that shows up in the chair, and it shows up in the second molar region more than anywhere else.
The height you need is the sum of the sleeve height, the guide thickness, the tissue, the length of drill above the sleeve, and the head of the handpiece. A fully guided stack in the molar region wants roughly 50 mm of opening and a premolar site roughly 32 mm, while the mean opening actually available at a molar site is about 31 mm. The requirement is set by your implant system, not by us.
If you are in this position with the patient open, the case is freehand or pilot at that site today. The four things that would have prevented it all happen before it prints: a shorter vertical offset, a shorter guided drill, an open-side sleeve or a keyless kit, or that one site planned pilot-only with the rest fully guided. Send us the patient's maximum opening and the site with the case and we run it before we design.
If the Guide Cracks
Stop, and get every piece out. Account for all of them before you continue.
Then decide: freehand from the plan, or reschedule. Do not reassemble a cracked guide and keep drilling. A guide with a fracture line through it is no longer rigid, and a fragment in the field is a bigger problem than a rescheduled surgery.
Three things cause it. A thin section over a long span. Side load from the handpiece, usually when access is tight and the handpiece is being levered. And a guide that has been autoclaved more than once — printed guide resins are supplied for a single cycle, and repeat sterilization is not something we recommend.
If you routinely work long spans, tell us the span when you send the case and we add bulk or a strut where it matters. That costs nothing and it is the difference between a guide that flexes and one that does not.
If a Sleeve Comes Loose
Stop and retrieve it.
Do not drill through the empty housing. The resin hole is not the drill diameter and it is not the drill axis — it is the outside of where the sleeve was. And do not glue a sleeve back in and keep going; there is no way to confirm its depth or its angle once it has moved.
That site is freehand today. Tell us, because a sleeve that releases is our problem, not yours.
When the Implant Does Not Land at the Planned Depth
Check three things, in this order.
Was the guide fully seated for that osteotomy? A guide sitting 1 mm high puts the implant 1 mm shallow, and nothing downstream corrects it.
Was it the right handle and the right vertical offset from your kit? H2, H4 and H6 are 2, 4 and 6 mm from the top of the sleeve to the implant shoulder, and mixing them is an easy mistake under a drape.
Did you use the depth from the drill report rather than the implant's nominal length? Those are different numbers and the report is the one that accounts for the offset.
Take a radiograph and correct it the same day rather than at the restorative appointment.
The Bailout Sequence, Decided Before You Start
Have it before the patient sits down, not after the guide fails.
Plan A is the guide as designed. Plan B is pilot-only through the guide or through a pilot sleeve, finishing freehand. Plan C is freehand with the plan and the drill report open as a reference — you still have the trajectory, the depths and the margins, whether or not the guide is in the mouth.
Have your regular drills open on the tray from the start. A tray that only holds a guided kit is what turns a guide problem into a canceled surgery.
And one thing worth saying plainly: if you get in there and the anatomy does not match what the plan assumed, take the guide out. The guide is a plan, not an order. You are the one looking at the bone.
The Try-In That Prevents Most of This
Seat the guide at a consult visit before surgery day. Dry, three checks, five minutes.
It catches the mouth-changed-after-the-scan problem, which is the biggest one, and it catches binding, which is the second. It converts a surgery-day failure into a phone call and a remake with time to spare. There is no version of this that costs more than it saves.
If the guide has been sitting for a while, try it on the model first. Use a guide within about two weeks where you can; printed guide resins drift slightly in storage and light accelerates it, so keep it pouched, cool and out of direct light. Past a month we recommend a model try-in before surgery, and if the fit has moved we reprint it.
Whose Problem It Is
We would rather put this in writing than have it be a conversation after something goes wrong.
If it is our work — design, printing, warping, sleeve placement — we remake the guide at no charge and overnight it to you at our cost. If the records we accepted caused it, the remake is half price. If we flagged the records and the case was built anyway, or the mouth changed after the scan, it is a new case at full price.
Call us from the operatory if you need to. We would rather talk you through it live than read about it later.
Common Questions
How do I know the guide is fully seated?
Three checks, dry: a positive stop, no rock under finger pressure at either end, and contact visible through the seating verification windows on both sides. On an edentulous case, confirm against the bite index.
It rocks on the distal. Can I just hold it?
No. A guide being held is a freehand case with a false sense of security. Find the interference, or go freehand on purpose.
The guide will not seat. What is the most likely cause?
The mouth changed after the scan — a temporary replaced, a tooth restored, tissue swollen or healed. Second most likely is an undercut or a tight contact binding it somewhere that is not the seat.
Can I relieve the guide chairside?
A tissue undercut or a tight contact on a surface that does not carry the seat, lightly, yes. Never the seating surfaces and never the sleeve housing. Once the seat is relieved, the plan it was built from no longer applies.
Can I drill through a guide that is not fully down?
No. The depths on the drill report assume the guide is seated. A guide sitting high puts every osteotomy shallow by that amount, and a guide that is tipped puts them off axis as well.
One fixation pin will not engage. Do I carry on?
An unfixed guide is not a guided case, and on a stackable base every component above it has lost its reference. Find purchase elsewhere in the planned pin path, or treat it as freehand with the plan as a reference.
The handpiece will not reach the sleeve on a second molar.
That site is pilot or freehand today. A fully guided stack in the molar region wants roughly 50 mm of opening and the mean available at a molar site is about 31 mm. Send us the patient's opening with the case and we check it before we design.
The guide cracked while I was drilling.
Stop, retrieve every fragment and account for all of them, then decide freehand or reschedule. Do not keep drilling through a fractured guide.
Why do guides crack?
A thin section over a long span, side load from the handpiece in tight access, or a guide that was autoclaved more than once. Tell us the span up front and we add bulk or a strut.
A sleeve came out. Can I drill through the hole?
No. The resin hole is neither the drill diameter nor the drill axis. Do not glue the sleeve back in either — its depth and angle cannot be confirmed once it has moved.
The implant did not reach the planned depth.
Check full seating, then the handle and vertical offset from your kit, then whether the depth used came from the drill report rather than the implant's nominal length. Take a film and correct it the same day.
What is a vertical offset and why does it matter here?
The distance from the top of the sleeve to where the implant shoulder lands. H2 is 2 mm, H4 is 4 mm, H6 is 6 mm. Using the wrong handle changes every depth on the report.
What is my fallback if the guide cannot be used?
Pilot through the guide if that is still possible, otherwise freehand with the plan and the drill report open. Have your regular drills on the tray from the start.
Should I try the guide in before surgery day?
Yes. Five minutes at a consult visit, dry, three checks. It catches both of the common failure causes while there is still time to remake.
The guide has been in the drawer for two months. Is it still good?
Try it on the model first. Printed resins drift slightly in storage and light accelerates it. Past a month we recommend a model try-in, and if the fit has moved we reprint it.
Can I autoclave the guide a second time?
We supply one guide per case and do not recommend re-sterilizing and reusing it. A single cycle changes dimensions by under about 0.1 mm in published testing, and 121 degrees Celsius is gentler than 134.
I got in there and the plan does not match the bone. Now what?
Take the guide out. The guide is a plan, not an order, and you are the one looking at the bone. The drill report still gives you the trajectory and the margins.
If the guide does not fit, who pays for the remake?
If it is our work — design, printing, warping, sleeve placement — we remake at no charge and overnight it at our cost. If the records we accepted caused it, the remake is half price. If we flagged the records and the case was built anyway, or the mouth changed after the scan, it is a new case.
Send a Case
Upload your CBCT, intraoral scan, bite and Rx on the Submit a Case page, or call (201) 255-4233. If you are in the chair right now with a guide that will not seat, call — that line reaches the laboratory.
Comments