Guide · Full-arch
Food trapping under a full-arch bridge: intaglio and hygiene
Why food collects under a full-arch implant bridge, how to spot an intaglio that cannot be cleaned, and which intaglio to ask the lab for instead.
Short answer
A full-arch implant bridge traps food when its intaglio, the surface facing the ridge, is concave or saddle-shaped, or when a brush can't pass between the bridge and the abutments. On the prosthesis side, what helps is a flat or convex, polished intaglio with hygiene access at every abutment, tested on the provisional before the definitive.
Step by step
- 01
Take the bridge out and find the debris
With the bridge out, see where the debris sits: on the intaglio over the ridge, next to the abutments or under the cantilevered ends. Photograph the intaglio and the ridge; the photos help explain the problem on the order.
- 02
Examine the mucosa with the bridge out
Probe the abutments with the prosthesis removed and record bleeding, suppuration and any hyperplastic tissue under the intaglio. Without the bridge, the probe goes deeper and the diagnosis is more accurate.
- 03
Test access at every abutment
Seat the bridge again and pass an interdental brush or floss under the intaglio, one abutment at a time. Where the instrument can't get through in the chair, cleaning at home won't reach either.
- 04
Read the shape of the intaglio
A concave intaglio, a saddle over the ridge or a step where it meets the tissue holds more. A flat or convex, polished intaglio lets the brush glide.
- 05
Fix it on the provisional before remaking
In PMMA, the intaglio can be recontoured, polished and tested for a few weeks. With zirconia, avoid major chairside adjustments: try the new contour in PMMA first.
- 06
Send the lab what changed
For the new bridge, scan the current ridge without the prosthesis, the scan bodies, and the adjusted bridge in and out of the mouth. Note on the order where food was collecting and the intaglio you want.
Why does food collect under a full-arch bridge?
Food collects under a full-arch bridge when the intaglio forms a pocket over the ridge that the tongue and the brush can’t reach. In an in vitro study by Jia and Yang (The Journal of Prosthetic Dentistry, 2024), 68 full-arch prostheses were made with saddle, flat, scalloped or ovate intaglios. The saddle design retained more biofilm than the other three, even after flossing.
In the same study, biofilm area grew with transmucosal height. The prostheses sat on subperiosteal implants in a lab model, but the logic carries over to any full-arch intaglio: the deeper and more concave the pocket, the less cleaning reaches it.
In the maxilla, implant position matters too. In a narrative review of upper full-arch restorations, Block (Journal of Oral and Maxillofacial Surgery, 2023) lists difficulty with daily hygiene among the drivers of biologic complications. He asks for implants placed so the bridge gives access to every one of them for maintenance.
Does poor hygiene access raise the risk of peri-implantitis?
Poor hygiene access goes with more peri-implantitis. Serino and Ström (Clinical Oral Implants Research, 2009) examined 23 partially edentulous patients referred for peri-implantitis treatment. Of the implants without proper hygiene access, 65% had peri-implantitis; of those with access, 82% were free of disease.
Group 3 of the 6th EAO Consensus Conference (Clinical Oral Implants Research, 2021) reached the same conclusion: prosthesis overcontouring and restricted hygiene access increase the risk of peri-implantitis. Food trapping itself wasn’t measured as a cause; what the studies measure is access.
What does an easy-to-clean full-arch intaglio look like?
An easy-to-clean full-arch intaglio is flat or convex, polished, and lets an interdental brush pass under the bridge next to each abutment. The ITI Blog piece on monolithic zirconia full-arch bridges (Said Sánchez, 2022) calls for a flat or convex intaglio designed for hygiene. The cleaning routine gets tested on the PMMA prototype, before the zirconia.
In the maxilla, the intaglio also affects speech and lip support, and the space under it is a trade-off between hygiene and esthetics that gets settled with the patient in the chair. Our guide to speech problems with an upper full-arch bridge covers what the only trial on open versus closed spaces found.
Which signs point to the cause, and what do you do?
The causes below come from studies on intaglio design, hygiene access and maintenance. Each row gives the sign you see in the chair and what changes in the bridge or the routine.
| cause | sign | what to do | source |
|---|---|---|---|
| Concave intaglio, saddle over the ridge | debris and biofilm on the intaglio when the bridge comes out | ask for a flat or convex, polished intaglio | Jia and Yang, 2024; Said Sánchez, 2022 |
| No brush access at the abutments | bleeding on probing and plaque at the abutments | open access in the design and test it on the provisional | Serino and Ström, 2009; Schwarz and colleagues, 2021 |
| Deep pocket between intaglio and ridge | more biofilm area under the bridge | reduce the pocket depth in the design | Jia and Yang, 2024 |
| Tissue growing under the intaglio | hyperplastic mucosa when the bridge is removed | treat the tissue and review intaglio shape and polish before the new bridge | Papaspyridakos and colleagues, 2012 |
| Maintenance without removing the bridge | plaque on the inner surfaces and at the connection | remove the bridge at maintenance, especially with pockets over 5 mm | Yin and colleagues, 2025 |
| Probing with the bridge in place | pockets underestimated | probe with the bridge removed | Xu and colleagues, 2026 |
Does maintenance require removing the bridge?
Maintenance on a screw-retained full-arch bridge cleans better with the bridge out. Yin and colleagues (The Journal of Prosthetic Dentistry, 2025) cleaned 23 implant-supported fixed prostheses ultrasonically without removing them. On average the cleaning removed 45% of the stained biofilm, and 54.6% remained. The authors point to the connection and the mucosal and proximal surfaces as what cleaning in place misses; with pockets over 5 mm, results were worse.
Removing the bridge also sharpens the diagnosis. In a study of 83 implants (Xu and colleagues, Clinical Oral Implants Research, 2026), probing without the prosthesis read 0.9 mm deeper on average and picked up peri-implantitis more accurately. The maintenance interval is your call.
What should you ask the lab for when remaking the intaglio?
To remake the intaglio, send the current ridge scanned without the bridge, scan bodies on every abutment, and the bridge or adjusted provisional scanned in and out of the mouth. On the order, note where food was collecting, the intaglio you want (flat or convex) and which abutments the brush needs to clear.
Smile Digital Lab, a digital dental lab in São Paulo, Brazil, designs the intaglio over the scanned ridge. If you ask to see the design, the case holds at the Approval stage and moves on only after you reply. The scan sequence is in our full-arch scanning guide, and the materials comparison is in full-arch zirconia, titanium or PMMA.
Related services
Open a portal accountFrequently asked questions
Will closing the space under the bridge fix it?
It removes the pocket but also blocks the brush, and the 2021 EAO consensus links restricted hygiene access to more peri-implantitis. The goal is a flat or convex intaglio the brush can reach at every abutment, not a sealed one nobody can clean.
Can tissue grow under the bridge?
It can. In the systematic review by Papaspyridakos and colleagues (2012), hyperplasia or hypertrophy of the tissue around full-arch bridges was the most frequent prosthesis-related biologic complication: 13% at five years and 26% at ten.
Does a zirconia bridge trap less food than an acrylic one?
We found no study comparing food trapping between materials. The studies compare complications and peri-implantitis, and our article on full-arch zirconia, titanium or PMMA brings those together. For food trapping, what the evidence points to is intaglio shape and hygiene access.
Sources
- Biofilm accumulation on complete arch subperiosteal implant-supported prostheses: effect of pontic type · The Journal of Prosthetic Dentistry (Jia and Yang, 2024)
- Peri-implantitis in partially edentulous patients: association with inadequate plaque control · Clinical Oral Implants Research (Serino and Ström, 2009)
- Peri-implantitis: summary and consensus statements of group 3. The 6th EAO Consensus Conference 2021 · Clinical Oral Implants Research (Schwarz et al., 2021)
- Maxillary full arch restorations - biological complications: a narrative review outlining criteria for long term success · Journal of Oral and Maxillofacial Surgery (Block, 2023)
- Necessity of removing implant-supported prostheses when conducting supportive peri-implant therapy: a clinical study · The Journal of Prosthetic Dentistry (Yin et al., 2025)
- Diagnostic accuracy of peri-implant probing with or without prostheses in detecting peri-implantitis · Clinical Oral Implants Research (Xu et al., 2026)
- A systematic review of biologic and technical complications with fixed implant rehabilitations for edentulous patients · The International Journal of Oral & Maxillofacial Implants (Papaspyridakos et al., 2012)
- 10 considerations on the use of monolithic zirconia for one-piece implant-supported fixed complete dental prostheses · ITI Blog (Said Sánchez, 2022)
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