Abutment screw
Clamps the multi-unit abutment into the implant. Tightened once at abutment delivery to the connection-specific value; settles in the first minutes.
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IMPLANT TORQUE · MULTI-UNIT ABUTMENT
The multi-unit abutment settling effect.
A multi-unit restoration has two screw joints, and both lose part of their preload in the first minutes after the wrench clicks. This page puts the measured losses, the re-tightening studies and the manufacturer statements side by side — with every figure sourced, and every gap named.
Schematic preload curve, not to scale. Percentages are the ranges reported by the cited in-vitro studies for the component and torque named beside each one.SCREW JOINTSMulti-unit → implant · prosthesis → multi-unit
SOURCES READ37 peer-reviewed papers · 7 manufacturer documents
EDITORIAL VISUALIZATIONPRELOAD OVER TIMEThe wrench clicks. The screw stretches.
Torque applied100 %
- SOURCESSakaguchi 1995 Vinhas 2020
TWO JOINTS, TWO NUMBERS
The multi-unit is not one screw. It is two.
The abutment screw clamps the multi-unit abutment into the implant. The prosthetic screw clamps the bridge onto the abutment. They are tightened to different values, they settle independently, and when the lower one is tightened the upper one is affected — a 1995 contact analysis found fastening the prosthetic screw reduced the clamping force at the abutment–implant interface by half. Nobel Biocare publishes both numbers per connection in IFU1075:
Prosthetic screw
Clamps the bridge onto the multi-unit. Opened and closed at every try-in and every recall — each one a tightening cycle on the same screw.
| Nobel Biocare connection | Straight multi-unit → implant | 17° / 30° multi-unit → implant | Prosthetic screw → multi-unit |
|---|---|---|---|
| Conical connection (CC) | 35Ncm | 15Ncm | 15Ncm |
| Tri-oval conical connection (TCC · N1) | 20Ncm | 20*Ncm | 15Ncm |
| Tri-channel | 35Ncm | 15Ncm | 15Ncm |
| External hex | 35Ncm | 15Ncm | 15Ncm |
Verbatim from IFU1075 Table 1, “Multi-unit Abutment Screw Tightening Torques and compatible screwdrivers”. The asterisk is Nobel Biocare’s. The 45°/60° Zygoma multi-unit on external hex is listed at 35 Ncm. The public Prosthetic Torque Guide shows 15 Ncm for 17°/30° multi-unit abutments and prosthetic screws and 35 Ncm for “all other abutments”, without the TCC exception.
MULTI-UNIT-CLASS VALUES FROM OTHER MANUFACTURERS WE READ
35Ncm15Ncm
“Abutment (incl. angled abutments) 35 Ncm”; “Occlusal screws 15 Ncm”.
Straumann 70288032 · 20Ncm10Ncm
Straight 32 Ncm, angled 20 Ncm; definitive prosthesis 10 Ncm.
Neodent GM Prosthetics Manual20Ncm10Ncm
Low Profile abutments 20 Ncm; cylinder retaining screws 10 Ncm.
ZimVie T3 Restorative Manual30Ncm—
Straight and angled tapered abutments 30 Ncm. Prosthetic screw value not in the fetched guide.
ZimVie RevitaliZe guideValues are quoted from manufacturer documentation and can change by component, platform and revision. Confirm the IFU for the component and lot in your hand before torquing.
THE TEN-MINUTE QUESTION
Re-tighten, yes. After exactly ten minutes — the evidence is split.
The ten-minute rule traces to Siamos 2002 and Winkler 2003. Later studies tested the interval itself. Read left to right: what was tested, what was found, on which component.
EDITORIAL VISUALIZATION| Study | Component · torque · design | Finding on the interval | Supports a fixed 10 min? |
|---|---|---|---|
| Siamos 2002Open source | Abutment screws · 25–40 Ncm · in vitro, re-torqued after 10 min | “Retightening abutment screws 10 minutes after the initial torque applications should be routinely performed.” | Supports |
| Kim 2011Open source | Abutment screws · 30 Ncm · 5 connections, settling measured by assembly length | Recommends tightening at least twice at a 10-minute interval; settling plateaus after the second tightening. | Supports |
| Handa 2023 (thesis)Open source | Nobel straight multi-unit · prosthetic screw 15 Ncm · 9 protocols (MSc thesis) | Re-tightening after 10 minutes gave the highest removal torque (12.83 Ncm) versus 10.64 Ncm for a single tightening. Removal torque was always below the applied 15 Ncm. | Supports |
| Varvara 2020Open source | Abutment screws · 35 Ncm · re-tightened at 2, 5 or 10 min, two designs | Two minutes gave the lowest preload loss; 11.6 % lost with no re-tightening. Authors call for randomized clinical trials before a standard interval. | Re-tighten yes · interval open |
| Khalili 2019Open source | Abutment screws · 10 min vs 2 weeks vs none · 100 000 cycles | Re-tightening after 10 minutes and after 2 weeks were “equally effective” against a single tightening. | Re-tighten yes · interval open |
| Sun 2024Open source | Abutment screws · 150 implants · re-torque at 10 min vs loosen-and-immediately-re-torque vs once | Loosening and immediately re-torquing matched the 10-minute protocol and beat a single tightening (immediate stability +6.28–21.58 %, long-term +11.77–44.87 %). | Re-tighten yes · interval open |
| Alnasser 2021Open source | Abutment screws · 32 Ncm · 10-min interval vs no interval vs once vs tighten–counter-tighten cycles | No significant difference between a 10-minute interval, no interval, or a single tightening. Three tighten–counter-tighten cycles gave higher values. | Does not support |
| Al-Otaibi 2018Open source | Full-arch abutment screws · 35 Ncm · torque held 0, 10 or 30 s | Holding the torque longer did not raise removal torque (24.44 Ncm immediate vs 23.37 Ncm at 30 s). Holding is not the same as re-tightening. | Does not support |
WHAT THE EVIDENCE SUPPORTS
What the fetched evidence supports: a second tightening leaves more preload than a single one, in vitro, across abutment screws and — in one thesis — the 15 Ncm multi-unit prosthetic screw. What it does not establish: that the interval must be ten minutes. No randomized clinical trial of a re-torque interval was found.
WHAT THE MANUFACTURERS STATE
Torque values, yes. A settling protocol, no.
We searched the fetched Nobel Biocare, Straumann, Neodent and ZimVie documents for “preload”, “settling”, “re-torque” and any timed re-tightening. The single re-tightening sentence found is conditional. The ten-minute protocol belongs to the literature, not to any IFU.
MANUFACTURERNobel Biocare
Conditional re-tightening“Caution — Each time a component is connected to the straight Multi-unit Abutment, make sure the clinical screw is not loosened and is re-tightened if necessary.”Verbatim (English)The only re-tightening sentence in IFU1075. It is conditional (“if necessary”) and sits in the straight multi-unit placement steps, after the caution never to exceed the maximum torque. The words “preload”, “settling” and any minute count do not appear in the IFU, the Prosthetic Torque Guide or the 2011 multi-unit quick guide.
MANUFACTURERStraumann
No re-tightening statement“Make sure the abutments are torqued down with 35 Ncm.”Verbatim (English)Screw-retained abutments 35 Ncm, occlusal screws 15 Ncm. No re-tightening, preload or settling statement in the fetched handling document.
MANUFACTURERNeodent
No re-tightening statement“Place the definitive prostheses, using the Neo Torque Wrench with a torque of 10 N.cm.”Verbatim (English)Mini Conical straight 32 Ncm, angled 20 Ncm, prosthesis 10 Ncm. No re-tightening, preload or settling statement in the Grand Morse prosthetics manual.
MANUFACTURERZimVie
Procedural step, not a protocol“Retighten the abutments to 30 Ncm using the Restorative Torque Wrench [TWR].”Verbatim (English)An impression-step instruction after removing the healing caps, not a settling protocol: no interval, and no “preload” or “settling” anywhere in the two ZimVie guides read.
STRAIGHT VERSUS ANGLED
Angulation changes the loss. The studies disagree on how much.
Four recent studies looked at straight versus angled multi-unit abutments. Three in-vitro papers find more loosening with angulation — but not on the same abutment, not at the same torque, and not always the same angle. One clinical series finds no difference.
- 16.43–28.78 %Prosthetic screw 15 Ncm · straight vs 30° multi-unit · zirconia plate
Torque loss per abutment before cyclic loading; significantly higher on the 30° abutment. Prosthetic screw deformation in 100 % of the 30° group.
SOURCESPibulniyom 2026 - 11.4 → 19.15 %Bredent Sky multi-unit · abutment 25 Ncm · prosthesis 18 Ncm · 0° / 35°
Abutment-screw torque loss rose from 11.4 % (both straight) to 19.15 % (both 35°) after aging.
SOURCESAl-Zordk 2021 - 25.1 → 16.8 NcmNucleoss multi-unit · abutment screw 25 Ncm all angles · 0° / 17° / 30°
Removal torque after aging fell to 20.1 Ncm on straight and 16.8 Ncm on 17° abutments — the 17° group, not the 30°, was lowest.
SOURCESSalama 2023 - p = 0.19Retrospective clinical · 308 abutments · zirconia prostheses
No significant difference in torque loss between angled, straight and solid abutments; multi-unit prostheses showed less torque loss than single units.
SOURCESSavabi 2026
GAP STATED AS A GAP
Not established: a measured preload loss for Nobel Biocare multi-unit abutments at the IFU torques (35 Ncm straight, 15 Ncm angled). The nearest data is the Manitoba thesis on the 15 Ncm prosthetic screw of a straight Nobel multi-unit. This page does not fill that gap with a number.
EDITORIAL VISUALIZATION
EDITORIAL VISUALIZATIONSCREW REUSE
Every try-in is a tightening cycle.
- 01
Prosthetic screw at 25 Ncm: after 10 insertion cycles a new screw should be used to maximise reverse torque.
SOURCESGuzaitis 2011 - 02
Titanium, gold and gold-coated abutment screws all showed some decay in preload with repeated tightening, irrespective of abutment type and torque.
SOURCESByrne 2006 - 03
Across seven systems at 20 Ncm, torque loss grew from 3–20 % on the first opening to 4.5–36 % averaged over thirty cycles.
SOURCESWeiss 2000 - 04
In multi-unit dentures with misfit, re-torquing the 10 Ncm titanium prosthetic screws made the misfit effect on loosening torque insignificant.
SOURCESSpazzin 2010
The direction is not uniform across the literature: some studies report removal torque rising with a second or repeated tightening (Kim 2011, Handa 2023), others report progressive loss with many cycles. Screw material, lubrication and connection differ between them.
QUESTIONS
Settling effect, answered from the sources.
Values are quoted from manufacturer documentation and can change by component, platform and revision. Confirm the IFU for the component and lot in your hand before torquing.
01What is the settling effect on a multi-unit abutment?+
Settling, or embedment relaxation, is the loss of preload that happens after tightening as the microscopically rough thread and seating surfaces flatten under load. The screw shortens slightly and part of the clamping force is gone before any chewing load. Reviews put the early loss at roughly 2–10 % of the initial preload; one study measured 11.6 % at 35 Ncm without re-tightening. A multi-unit restoration has two such joints — abutment-to-implant and prosthesis-to-abutment — and each settles on its own.
02Should I re-torque a multi-unit abutment after ten minutes?+
In-vitro studies consistently find that a second tightening to the same value leaves more preload than a single one, including one thesis on the 15 Ncm prosthetic screw of a straight Nobel Biocare multi-unit, where re-tightening after ten minutes gave the highest removal torque. The exact interval is not settled: Varvara 2020 found two minutes best, Khalili 2019 found two weeks equal to ten minutes, Sun 2024 found loosening and immediately re-torquing equal to ten minutes, and Alnasser 2021 found no difference at all. No manufacturer on this page states a timed re-torque; Nobel Biocare says to re-tighten the clinical screw “if necessary” each time a component is connected.
03Does Nobel Biocare state a settling or re-torque protocol?+
No. IFU1075 for Multi-unit Abutments contains one re-tightening sentence, and it is conditional: each time a component is connected to the straight Multi-unit Abutment, make sure the clinical screw is not loosened and re-tighten it if necessary. The words “preload” and “settling” and any minute count do not appear in the IFU, the Prosthetic Torque Guide or the multi-unit quick guide. The ten-minute figure comes from Siamos 2002 and Winkler 2003.
04What torque does Nobel Biocare publish for the multi-unit abutment and its prosthetic screw?+
From IFU1075 Table 1: straight Multi-unit Abutment 35 Ncm on conical, tri-channel and external hex connections and 20 Ncm on the tri-oval conical connection; 17° and 30° Multi-unit Abutments 15 Ncm (20 Ncm on tri-oval conical); prosthetic screw 15 Ncm on every connection. Confirm the IFU packed with your component and lot.
05Are angled multi-unit abutments more prone to loosening?+
Three in-vitro studies report more torque loss with angulation — on a 30° abutment with the 15 Ncm prosthetic screw (Pibulniyom 2026), on 35° Bredent Sky abutments (Al-Zordk 2021) and, unexpectedly, on 17° rather than 30° Nucleoss abutments (Salama 2023). A retrospective clinical study of 308 abutments found no difference between angled, straight and solid abutments (Savabi 2026). The studies use different systems and torques, so the size of the effect is not established.
06How many times can the prosthetic screw be tightened before it should be replaced?+
For the prosthetic screw studied by Guzaitis 2011 at 25 Ncm, a new screw is advised after ten insertion cycles. Byrne 2006 and Weiss 2000 report preload decaying with repeated tightening across screw materials and systems. Every try-in counts as a cycle. Follow the manufacturer’s single-use or reuse statement for the screw in your hand.
REFERENCES
Everything this page quotes.
PubMed abstracts were read for every paper; full text where the journal allowed it. Manufacturer PDFs were downloaded and searched. Winkler 2003 and Siamos 2002 were read as abstracts only. Fetched 2026-09-05.
- 01Winkler S, Ring K, Ring JD, Boberick KG. Implant screw mechanics and the settling effect: overview. J Oral Implantol 2003;29:242–245.Peer-reviewed / thesis
- 02Siamos G, Winkler S, Boberick KG. Relationship between implant preload and screw loosening on implant-supported prostheses. J Oral Implantol 2002;28:67–73.Peer-reviewed / thesis
- 03Kim KS, Lim YJ, Kim MJ, et al. Variation in the total lengths of abutment/implant assemblies generated with a function of applied tightening torque. Clin Oral Implants Res 2011;22:834–839.Peer-reviewed / thesis
- 04Vinhas AS, Aroso C, Salazar F, et al. Review of the mechanical behavior of different implant-abutment connections. Int J Environ Res Public Health 2020;17:8685.Peer-reviewed / thesis
- 05Effect of abutment type and tightening sequence on torque maintenance capacity after mechanical cycling in splinted implant-supported restorations. Oral 2021;1(4):29.Peer-reviewed / thesis
- 06Varvara G, Sinjari B, Caputi S, Scarano A, Piattelli M. The relationship between time of retightening and preload loss of abutment screws for two different implant designs. J Oral Implantol 2020;46:13–17.Peer-reviewed / thesis
- 07Weiss EI, Kozak D, Gross MD. Effect of repeated closures on opening torque values in seven abutment-implant systems. J Prosthet Dent 2000;84:194–199.Peer-reviewed / thesis
- 08Pardal-Peláez B, Montero J. Preload loss of abutment screws after dynamic fatigue in single implant-supported restorations. A systematic review. J Clin Exp Dent 2017;9:e1355–e1361.Peer-reviewed / thesis
- 09Khalili M, Luke A, El-Hammali H, DiPede L, Weiner S. Efficacy of several retightening protocols for maintaining clamping force in the implant-abutment joint: an in vitro pilot study. Int J Oral Maxillofac Implants 2019;34:1084–1090.Peer-reviewed / thesis
- 10Alnasser AH, Wadhwani CPK, Schoenbaum TR, Kattadiyil MT. Evaluation of implant abutment screw tightening protocols on reverse tightening values: an in vitro study. J Prosthet Dent 2021;125:486–490.Peer-reviewed / thesis
- 11Sun M, Shui Y, Zhang Y, et al. Influence of abutment screw-tightening methods on the screw joint: immediate and long-term stability. Int J Dent 2024;2024:5768318.Peer-reviewed / thesis
- 12Al-Otaibi HN, Al-Fouzan AF, Al-Mufleh TS, Labban N. Effect of different maintenance time of torque application on detorque values of abutment screws in full-arch implant-supported fixed prostheses. Clin Implant Dent Relat Res 2018;20:848–851.Peer-reviewed / thesis
- 13Handa KK. The effect of screw torque maintenance and re-applying screw torque on the retention of prosthetic screw for multi-unit implant restorations [MSc thesis]. University of Manitoba; 2023.Peer-reviewed / thesis
- 14Spazzin AO, Henrique GE, Nóbilo MA, et al. Effect of retorque on loosening torque of prosthetic screws under two levels of fit of implant-supported dentures. Braz Dent J 2010;21:12–17.Peer-reviewed / thesis
- 15Farina AP, Spazzin AO, Consani RL, Mesquita MF. Screw joint stability after the application of retorque in implant-supported dentures under simulated masticatory conditions. J Prosthet Dent 2014;111:499–504.Peer-reviewed / thesis
- 16Guzaitis KL, Knoernschild KL, Viana MA. Effect of repeated screw joint closing and opening cycles on implant prosthetic screw reverse torque and implant and screw thread morphology. J Prosthet Dent 2011;106:159–169.Peer-reviewed / thesis
- 17Byrne D, Jacobs S, O'Connell B, Houston F, Claffey N. Preloads generated with repeated tightening in three types of screws used in dental implant assemblies. J Prosthodont 2006;15:164–171.Peer-reviewed / thesis
- 18Salama AA, Radwan MM, Bushra SS. Influence of thermo-mechanical aging on straight versus angled multi-unit abutments screw joint stability. Egyptian Dental Journal 2023;69:487–495.Peer-reviewed / thesis
- 19Al-Zordk W, Al-Dobaisi T, Ghazy M. Torque maintenance of screw-retained implant-supported anterior fixed dental prosthesis with different abutment angulations after aging. Int J Oral Maxillofac Implants 2021;36:723–729.Peer-reviewed / thesis
- 20Pibulniyom M, Fattouhi M, Chiam SY, et al. The influence of multi-unit abutment angulation on the prosthetic screw-joint stability. J Prosthodont 2026;35:210–218.Peer-reviewed / thesis
- 21Savabi S, Nejatidanesh F, Savabi G, et al. Screw loosening and torque loss of zirconia-based implant-supported dental prostheses: a retrospective clinical study. Int J Oral Maxillofac Implants 2026 (online ahead of print).Peer-reviewed / thesis
- 22Sakaguchi RL, Borgersen SE. Nonlinear contact analysis of preload in dental implant screws. Int J Oral Maxillofac Implants 1995;10:295–302.Peer-reviewed / thesis
- 23Nobel Biocare. Instructions for use — Multi-unit Abutments and Healing Caps (IFU1075, EN_GB 06).Manufacturer document
- 24Nobel Biocare. Prosthetic Torque Guide.Manufacturer document
- 25Straumann. Basic Information — Screw-retained Abutments, technical handling information (702880).Manufacturer document
- 26Neodent. Prosthetics Manual Grand Morse (10129).Manufacturer document
- 27ZimVie. T3, T3 PRO and Osseotite Implant Restorative Manual (ZVINST0102).Manufacturer document
- 28ZimVie. RevitaliZe Patient Solutions — Surgical and Restorative Technique Guide (ZVINST0152).Manufacturer document
Values are quoted from manufacturer documentation and can change by component, platform and revision. Confirm the IFU for the component and lot in your hand before torquing.
AFTER THE CLICK
Read the value here. Keep it in the case.
TrazaLab records the implant line with its torque on the tooth site, writes it into the Digital Rx, and shows the laboratory exactly what was applied — or exactly what was not confirmed.