Montgomery in Dentistry: the Legal Test and Material Risks

What the Montgomery standard actually requires

Before 2015, the adequacy of risk disclosure was judged by the Bolam test — essentially, "would a responsible body of clinicians have disclosed this?" Montgomery v Lanarkshire Health Board [2015] UKSC 11 replaced that test for information and risk disclosure with a patient-centred standard.

The duty, in the words the Supreme Court used, is that a clinician must take reasonable care to ensure that the patient is aware of any material risks involved in any recommended treatment, and of any reasonable alternative or variant treatments.

The test for whether a risk is material is twofold. The objective limb: would a reasonable person in the patient's position be likely to attach significance to the risk? And the subjective limb: is the clinician aware, or should the clinician reasonably be aware, that this particular patient would be likely to attach significance to it?

Two practical consequences follow. First, materiality is not a fixed percentage — a low-frequency risk can still be material if its consequences are severe or if it matters to this patient (for example, altered tongue sensation for a wind-instrument player, or any aesthetic risk for a patient whose occupation depends on appearance). Second, the standard is a dialogue, not a disclaimer: the patient must be given the opportunity to ask questions and the information must be comprehensible, not buried in a signed form.

The Supreme Court described the clinician's advisory role as dialogue (para 90): the aim is that the patient understands the benefits and risks of the proposed treatment and any reasonable alternatives, so the duty is not met by giving technical information the patient cannot reasonably be expected to grasp, or by routinely demanding a signature on a consent form. The therapeutic exception, withholding a risk whose disclosure would be seriously detrimental to the patient's health (para 88), is limited and must not be used to stop a patient making an informed choice the clinician thinks is contrary to their best interests (para 91).

The three elements of valid consent

For consent to be legally valid in the UK, all three of the following must be present. A signed consent form is evidence that a conversation happened — it is not consent in itself.

1. Capacity — the patient must be able to understand, retain, weigh and communicate the decision (Mental Capacity Act 2005 in England & Wales; equivalent frameworks in Scotland and Northern Ireland). Capacity is decision-specific and time-specific. For children, consider Gillick competence and the relevant age-of-consent rules.
2. Information — the patient has been told about the nature and purpose of the treatment, the material risks, the reasonable alternatives (including no treatment and its consequences), and the likely outcomes — to the Montgomery standard above.
3. Voluntariness — the decision is made freely, without coercion or undue influence from clinicians, family or financial pressure.

Consent is also a continuing process: it can be withdrawn at any time, should be revisited if the plan, the costs, the operator or the patient's circumstances change, and (for anything beyond simple, low-risk care) is best taken at a separate visit from the one at which treatment is carried out, so the patient has time to reflect.

What to document for consent

Good consent records are the single most effective medico-legal protection, because in a complaint or claim the question is rarely "did you treat well?" but "can you evidence what you discussed?" If it is not in the notes, it is very hard to prove it was said. FGDP/CGDent record-keeping guidance and defence organisations expect the consent conversation to be recorded contemporaneously. A defensible consent note should capture:

• The specific procedure discussed and its purpose / clinical justification (why this tooth, why now).
• The material risks discussed, named individually — not "risks explained". Record the ones relevant to this patient and procedure.
• The reasonable alternatives offered, including no treatment and its consequences.
• Expected outcomes, prognosis and any uncertainty, plus likely number of visits and after-care.
• Costs / NHS vs private status where relevant, and any plan or payment discussion.
• Patient-specific factors — questions the patient asked, concerns they raised, anything that made a particular risk material to them, and any information leaflets given.
• Confirmation that the patient had the opportunity to ask questions and that their understanding was checked.
• The decision and consent (and, for higher-risk or surgical care, a signed consent form and, ideally, a cooling-off period).
• Capacity / best-interests notes where relevant, and for children the basis of consent (parental responsibility / Gillick competence).

Material risks by procedure (quick reference)

The table below summarises the headline material risks and figures most commonly discussed for routine UK dental procedures, taken from the Nosht Consent Checklists dataset. These are prompts for discussion, not an exhaustive or patient-specific list. Tailor the conversation to the individual; the procedure sections beneath give the fuller lists.

Per-procedure material risks (the consent conversation)

The lists below mirror the Nosht Consent Checklists tool. They are discussion prompts — what a reasonable patient would commonly want to know — not a script, and not a substitute for tailoring to the individual.

Extraction (simple). Discuss: why the tooth cannot be saved; that it is done under local anaesthetic with forceps/elevators; post-op instructions (bite on gauze, soft diet, no rinsing for 24 hours); recovery (1–2 weeks for socket healing); replacement options (denture, bridge, implant, or accept the space); and the consequences of not extracting (infection, pain, spread). Material risks: pain; swelling; bleeding that may persist for several hours; dry socket (alveolar osteitis); nerve damage — numbness/tingling of lip, chin or tongue (lower teeth); oro-antral communication (upper premolars/molars); root fracture needing surgical retrieval; damage to adjacent teeth/restorations; socket infection; bruising; a stiff jaw / limited opening (usually short-lived). Explain that the space will remain: neighbouring teeth may drift or tilt and the opposing tooth over-erupt, affecting the bite. Reasonable alternatives: root canal treatment to retain the tooth; restoring the tooth (filling/crown) if restorable; periodontal treatment if gum disease is the reason; monitoring if symptom-free; specialist referral; no treatment.

Surgical extraction / wisdom tooth. Discuss: the indication for removal (NICE TA1 / RCS England 2020, e.g. a second or later episode of pericoronitis, unrestorable caries, untreatable pulpal or periapical disease, resorption, cyst or tumour); why a surgical approach is needed (impaction, angulation, root morphology); that it involves a flap, bone removal, sectioning and sutures; radiographic findings (proximity to the IAN canal / sinus); anaesthesia options (LA, LA with sedation, or GA); post-op regime; time off work/activities (2–5 days); suture removal if non-resorbable. Material risks: pain, swelling and bruising (may be significant for 5–7 days); inferior alveolar nerve (IAN) damage — numbness of lip and chin; temporary in about 1.2% and permanent in about 0.28% (Kang et al. 2020), higher when the X-ray shows the roots close to the canal; lingual nerve damage — numbness/altered taste of tongue; temporary in about 1% and permanent in about 0.3% (Renton & McGurk 2001); numbness may be temporary (weeks–months) or permanent; bleeding; dry socket (up to almost 30% after surgical third-molar removal, RCS England 2020); jaw fracture (rare, about 1 in 22,000 operations; higher risk in an atrophic mandible); trismus; infection requiring antibiotics; oro-antral communication (upper wisdom teeth); damage to adjacent teeth. Reasonable alternatives: monitoring with radiographic review if asymptomatic; coronectomy (deliberate root retention to protect the IAN); referral to oral surgery / maxillofacial; extraction under GA; no treatment, managing symptoms if they recur (e.g. after a first episode of pericoronitis), with the consequences of leaving the tooth discussed.

Root canal treatment. Discuss: the reason for RCT (irreversible pulpitis, necrotic pulp, periapical pathology); the procedure (access, cleaning, shaping, obturation); 1–3 visits depending on complexity; rubber dam isolation; that the tooth will usually need a crown/onlay afterwards; and the likely outcome (complete healing on X-ray in about 68–85% of teeth by strict criteria, Ng et al. 2007; about 86–93% of root-filled teeth still present after 2–10 years, Ng et al. 2010). Material risks: file fracture; root perforation; missed canal; treatment failure / persistent infection; need for retreatment, apicectomy or extraction; flare-up between visits; tooth fracture if not restored promptly with a crown; discolouration over time; sodium hypochlorite incident (rare but serious). Reasonable alternatives: extraction (± replacement); referral to an endodontist; vital pulp therapy — full pulpotomy for a vital tooth with irreversible pulpitis, or pulp capping / partial pulpotomy only if the pulp is judged reversibly inflamed (ESE 2023); no treatment (with risk of worsening infection, abscess, cellulitis).

Crown / bridge. Discuss: the reason and the preparation required; material options (PFM, zirconia, e.max, gold); typically 2 visits (preparation + fit); a temporary crown between visits; shade and aesthetics; longevity (about 95% of crowns still in place at 5 years, Sailer et al. 2015; about 89% of conventional bridges at 10 years, Pjetursson et al. 2007); that bridge abutment teeth require irreversible preparation; and, for a bridge, cleaning under the false tooth every day with special floss or other cleaning aids (Oral Health Foundation). Material risks: post-op sensitivity; pulp death requiring root canal treatment (about 5% of crowned teeth, about 7% after more than 10 years, Al-Manei et al. 2023; higher for bridge abutments, about 3 in 10 by 10 years in one long-term study, Cheung et al. 2005); shade mismatch; cement failure/debond; porcelain fracture; periodontal issues at margins; recurrent caries; abutment failure (bridges); bite adjustment at fit. Reasonable alternatives: direct composite; onlay/overlay (more conservative); removable partial denture; implant-supported restoration; resin-bonded (Maryland) bridge; accept the space.

Dentures (complete / partial). Discuss: the type (complete, partial acrylic or cobalt-chrome); the visits (impressions, bite registration, try-in, fit); the adaptation period; cleaning/maintenance; the need for review and reline; and realistic expectations. Material risks: initial speech changes; sore spots/ulceration; difficulty eating some foods; ongoing bone resorption, so relines or a replacement will be needed over time; reduced taste (upper complete); gagging; looseness (esp. lower complete); increased caries/perio risk around clasps (partial); denture stomatitis. It can take a few weeks to get used to new dentures (NHS). For an immediate denture (fitted on the day of extraction), also discuss that it will loosen as the gums heal, may need a lining while healing (usually 3–6 months), is normally replaced once healing is complete (and the cost of this), and is not removed for the first 24 hours. Reasonable alternatives: implant-retained overdenture; fixed bridgework (only where teeth remain to support it); implants with a fixed prosthesis; accept the spaces.

Dental implant. Discuss: suitability; the timeline (surgery, healing 3–6 months, restoration); possible bone graft/sinus lift; that smoking raises the risk of implant failure (Mustapha et al. 2021); that a history of gum disease, poor plaque control and no regular maintenance raise the risk of peri-implantitis (Schwarz et al. 2018); maintenance demands; cost/plan cover; and survival (about 96% of implants still in place at 10 years, Howe et al. 2019; survival is not the same as success). Material risks: nerve damage (IAN or mental nerve); sinus perforation (upper); failure to osseointegrate; peri-implantitis (infection and bone loss); bone-graft failure; post-op pain/swelling/bruising; bleeding; prosthetic complications (screw loosening, porcelain fracture); need for further surgery if it fails; damage to adjacent teeth. Reasonable alternatives: conventional fixed bridge; removable denture; resin-bonded bridge; accept the space.

Whitening / bleaching. Discuss: the type (home trays or in-office); pre-treatment assessment (caries, restorations, gingival health); that existing restorations will not whiten and may need replacing; realistic shade expectations; duration (home 2–4 weeks; in-office 1–2 sessions); and UK legal concentration limits — under the Cosmetic Products Enforcement Regulations 2013, products releasing >0.1% and up to 6% hydrogen peroxide may be supplied/used only by a dental professional, the first use must be by or under the supervision of a dentist, the patient must be 18 or over, and anything releasing >6% is illegal for cosmetic tooth whitening. Material risks: tooth sensitivity (may be significant); gingival irritation; uneven result; colour relapse over months to years; restoration mismatch; less predictable for tetracycline staining or fluorosis, which may need prolonged treatment or an alternative (tetracycline: Leonard 2003); temporary increase in tooth porosity. Reasonable alternatives: composite bonding; veneers, porcelain or composite (a small amount of enamel is usually removed first, which cannot be undone); microabrasion (superficial enamel defects or stains such as white spots or mild fluorosis; removes a thin layer of enamel); professional cleaning for extrinsic surface stain; no treatment. For internal (non-vital) bleaching of a root-filled tooth, the root filling must be sealed off first, and external cervical resorption, which can lead to loss of the tooth, is a rare but material risk (Newton & Hayes 2020).

Orthodontics. Discuss: the appliance (fixed brackets, aligners, removable); duration (typically 12–24 months); any planned extractions; reviews every 4–8 weeks; that oral hygiene is critical (higher caries risk); long-term (often lifelong) retainers and their cost; dietary restrictions; what treatment will and will not achieve, particularly if its aims are limited; the patient's responsibilities (oral hygiene, wear as instructed, attendance); and cost. Material risks: root resorption; decalcification/white-spot lesions; relapse without retainer wear; treatment longer than estimated; soft-tissue ulceration; bracket debonding; loss of vitality (rare, but higher in previously injured teeth); gingival recession; nickel allergy. Reasonable alternatives: accept current alignment; cosmetic bonding/veneers (camouflage); a different appliance type; surgical orthodontics (skeletal discrepancy).

Use the Nosht Consent Checklists tool

This page explains the standard and the material risks. To work through a consent conversation in clinic and produce a record, Nosht has a dedicated Consent Checklists tool: pick a procedure and work through four sections — discussion points, material risks, reasonable alternatives and expected outcomes — ticking items as you cover them, then copy a note-ready summary (with a Montgomery statement and an items-discussed count) straight into your clinical record. It covers 8 common procedures (simple and surgical extraction, RCT, crown/bridge, dentures, implant, whitening and orthodontics). The tool is a deterministic reference aide-mémoire: it works from a fixed UK consent dataset, stores nothing (state is in-memory only), and is not generated by a language model — the prompts and figures are fixed by design.

Nosht's separate note-writing features optionally use clinician-reviewed AI (Anthropic Claude Haiku 4.5) to help structure clinical notes from what you type; the clinical reference tools like Consent Checklists are deterministic and are not AI-generated. The checklist supports — it does not replace — the consent conversation: always tailor the discussion to the individual patient and document consent in your notes.

Sources

• GDC Standards for the Dental Team, Principle 3: Obtain valid consent (accessed 18 October 2026)
• Montgomery v Lanarkshire Health Board (UK Supreme Court, 2015, UKSC 11) (accessed 18 October 2026)
• Mental Capacity Act 2005 (accessed 18 October 2026)
• The Cosmetic Products Enforcement Regulations 2013 (SI 2013/1478) (accessed 18 October 2026)
• NICE TA1: Guidance on the extraction of wisdom teeth (accessed 18 October 2026)