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Key Facts: Internat en Odontologie Exam

3 DES

Residency specialties: Orthopédie Dento-Faciale (ODF), Chirurgie Orale (CO), Médecine Bucco-Dentaire (MBD)

Code de la santé publique (Art. R. 634-1)

400 points

Total across the 360-point composition and 40-point LCA papers

Arrêté du 17 novembre 2011 modifié

6 Hours

Total duration of the two three-hour written papers

Arrêté du 17 novembre 2011 modifié

100%

National ranking merit-based residency post allocation

Centre National de Gestion (CNG)

3–4 Years

Full-time salaried hospital residency training duration (3 years for ODF/MBD, 4 years for CO)

Ministère de la Santé / CNG

The Concours National de l'Internat en Odontologie is the CNG-administered specialist-residency competition. Its two three-hour papers award 360 points for composition and 40 for LCA. This 111-question bank is an English-language MCQ study adaptation covering dental knowledge and article appraisal.

Sample Internat en Odontologie Practice Questions

Try these sample questions to review concepts for the Internat en Odontologie exam. Each question includes a detailed explanation. Start the interactive quiz above for the full 111+ question experience with AI tutoring.

1According to the International Caries Detection and Assessment System (ICDAS) and French conservative dentistry guidelines, which clinical presentation corresponds to an ICDAS code 2 lesion?

A.A distinct visual change in enamel seen without air drying, localized to the pit or fissure

B.First visual change in enamel visible only after prolonged air drying

C.Localized enamel breakdown with microcavitation but without visible dentin

D.An underlying dark shadow from dentin with or without localized enamel breakdown

Explanation: An ICDAS code 2 lesion is characterized by a distinct visual opacity or discoloration in enamel that is clearly visible even when the tooth surface is moist. In contrast, an ICDAS code 1 lesion is an initial visual change that is detectable only after prolonged air drying (5 seconds).

2Which monomer in universal dental adhesives is specifically responsible for chemical bonding to hydroxyapatite through calcium chelation and nanolayering?

A.Bis-GMA (bisphenol A-glycidyl methacrylate)

B.10-MDP (10-methacryloyloxydecyl dihydrogen phosphate)

C.TEGDMA (triethylene glycol dimethacrylate)

D.HEMA (2-hydroxyethyl methacrylate)

Explanation: 10-MDP possesses a hydrophobic methacrylate group, a long hydrophobic carbon spacer chain, and a hydrophilic dihydrogen phosphate group that forms stable calcium salts with hydroxyapatite. This chemical interaction produces regular 10-MDP-calcium nanolayers that enhance hydrolytic bond stability over time.

3A 24-year-old patient presents with intense, throbbing, spontaneous pain in tooth 16 that worsens with cold fluids and lingers for more than 40 seconds. Periapical radiography reveals deep occlusal caries approaching the pulp chamber without periapical radiolucency. What is the definitive pulpal diagnosis according to AAE and French endodontic consensus?

A.Reversible pulpitis

B.Pulp necrosis

C.Symptomatic irreversible pulpitis

D.Asymptomatic irreversible pulpitis

Explanation: Symptomatic irreversible pulpitis is defined by spontaneous or provoked intense pain that persists long after the thermal stimulus is removed. The lingering reaction to cold (>30–40 seconds) indicates vital pulp tissue experiencing severe, non-resolving inflammatory alterations requiring pulpectomy or vital pulp therapy.

4During endodontic chemo-mechanical preparation, which chemical irrigant is primarily used to dissolve the inorganic component of the smear layer and expose dentinal tubules?

A.Sodium hypochlorite (NaOCl 2.5–5.25%)

B.Chlorhexidine digluconate (CHX 2%)

C.Citric acid or 17% EDTA

D.Hydrogen peroxide (H2O2 3%)

Explanation: 17% Ethylenediaminetetraacetic acid (EDTA) or 10% citric acid is a chelating agent that reacts with calcium ions to demineralize and remove the inorganic debris of the endodontic smear layer. Sodium hypochlorite acts on organic tissue, making sequential alternation of NaOCl and EDTA essential for complete smear layer clearance.

5According to the 2020 IADT guidance, what definitive-treatment assessment follows identification of an uncomplicated crown-root fracture with a mobile coronal fragment?

A.Rigid splinting of the mobile coronal fragment for 8 to 12 weeks

B.Immediate surgical extrusion and extraction within 24 hours

C.Immediate pulp extirpation through the mobile coronal fragment without stabilization

D.Removal of the mobile coronal fragment followed by evaluation for gingivectomy, extrusion, or extraction

Explanation: After clinical and radiographic assessment, removal of a loose fragment may be needed to expose the fracture extent and assess restorability. Subsequent options include restoration, gingival surgery, orthodontic or surgical extrusion, root treatment when indicated, or extraction. IADT also allows temporary stabilization of a loose fragment to adjacent teeth while a treatment plan is established; there is no universal splinting duration in the way the former stem implied.

6What clinically important interaction occurs if sodium hypochlorite (NaOCl) is mixed directly with chlorhexidine (CHX) during root canal irrigation?

A.An insoluble orange-brown precipitate that can stain dentine and obstruct tubules

B.Calcium hydroxide crystals

C.Trihalomethane gas

D.Chelated EDTA salt

Explanation: Direct contact between NaOCl and chlorhexidine produces an insoluble orange-brown precipitate that can stain dentine and interfere with canal cleaning and obturation. The precipitate's chemical composition—and specifically whether free para-chloroaniline is present—has been disputed by analytical studies, so it should not be taught simply as 'toxic PCA'. The irrigants should be separated with an appropriate intermediate flush and drying protocol.

7A patient experiences an avulsion of tooth 21 with an extra-oral dry time of 15 minutes. The tooth is immediately replanted at the dental office within 45 minutes of the injury. What is the recommended splinting type and duration according to IADT guidelines?

A.Rigid wire composite splint for 6 weeks

B.Flexible or semi-rigid splint for 2 weeks

C.Semi-rigid splint for 4 months to prevent replacement resorption

D.No splinting required if the tooth fits snugly into the alveolus

Explanation: When extra-oral dry time is under 60 minutes, periodontal ligament cells remain viable. The IADT guidelines recommend gentle repositioning and passive, flexible splinting (using orthodontic wire or nylon fishing line with composite) for 2 weeks to allow physiological mobility and stimulate functional periodontal ligament fiber reattachment.

8Which metallurgical phase transition gives nickel-titanium (NiTi) endodontic rotary instruments their property of shape memory and pseudo-elasticity?

A.Transformation from face-centered cubic alpha phase to hexagonal close-packed beta phase

B.Cubic austenite phase transitioning stress-induced to monoclinic martensite phase

C.Amorphous vitreous phase transforming into crystalline quartz

D.Ferrite transition to pearlite under elevated hydraulic pressure

Explanation: The superelastic behavior of NiTi instruments is driven by a reversible, diffusionless, stress-induced martensitic transformation. When subjected to stress, the high-temperature austenitic crystalline phase (ordered B2 cubic lattice) transforms into the more flexible martensitic phase (B19' monoclinic lattice), allowing the instrument to endure high elastic strain without plastic deformation.

9In vital pulp therapy of a permanent mature tooth with deep caries and pinpoint mechanical exposure, which capping biomaterial demonstrates superior dentin bridge formation and long-term pulp vitality compared to calcium hydroxide?

A.Zinc oxide eugenol cement

B.Mineral trioxide aggregate (MTA) or calcium silicate bioceramics

C.Resin-modified glass ionomer cement (RMGI)

D.Polycarboxylate cement

Explanation: Hydraulic calcium silicate cements such as MTA and Biodentine release calcium hydroxide upon hydration, induce alkaline pH, promote alkaline phosphatase activity, and stimulate odontoblast-like cell differentiation. They produce thicker, more continuous, and tunnel-defect-free dentin bridges with significantly less pulpal inflammation than traditional calcium hydroxide.

10What is the primary mechanism of action of silver diamine fluoride (SDF 38%) in arresting active dentinal carious lesions?

A.Thermal ablation of microbial biofilms via exothermic precipitation

B.Total demineralization of infected dentin to facilitate spontaneous exfoliation

C.Inhibition of matrix metalloproteinases (MMPs), bactericidal action of silver, and fluorhydroxyapatite formation

D.Polymerization of dentinal fluid into an impermeable polyurethane barrier

Explanation: Silver diamine fluoride arrests caries through a synergistic tri-modal action: silver ions exert potent bactericidal effects by disrupting bacterial cell walls and DNA synthesis; silver and fluoride inhibit host collagenases and matrix metalloproteinases (MMP-2, -8, -9); and fluoride promotes remineralization by forming acid-resistant fluorhydroxyapatite.

About the Internat en Odontologie Exam

The Concours National de l'Internat en Odontologie is the premier French competitive examination for dental graduates and students in their final year of dental surgery (DFASO 2). Administered by the Centre National de Gestion (CNG) under the authority of the French Ministry of Health, this highly competitive national exam governs access to Diplômes d'Études Spécialisées (DES) residencies in Orthopédie Dento-Faciale (ODF, 3 years), Chirurgie Orale (CO, 4 years, shared with medicine), and Médecine Bucco-Dentaire (MBD, 3 years). Successful candidates are appointed as hospital dental residents (internes en odontologie) across University Hospital Centers (CHU) and receive full-time salaried specialist clinical training.

Exam sponsor: Centre National de Gestion (CNG). The requirements and fees below concern the certification or admission exam, separate from our free practice resources.

Assessment

The current national rules specify two anonymous written papers: a three-hour composition paper worth 360 points and a three-hour lecture critique d'article (LCA) paper worth 40 points, for 400 points total. The 2026 opening order governs eligibility and the national session; successful candidates choose available DES posts in national rank order.

Time Limit

Composition paper 3h + LCA paper 3h (6 hours total)

Passing Score

Competitive national ranking determining allocation into DES in Orthopédie Dento-Faciale, Chirurgie Orale, and Médecine Bucco-Dentaire

Exam / Certification Fees

No separate examination fee is stated in the 2026 opening order

Exam sponsor website

Fees, eligibility, and exam policies can change. Confirm them with the exam sponsor before applying or paying.

Official sources

Our practice resources: topics covered

We aim to reflect publicly available exam outlines and topic information in our study resources. Coverage, format, and difficulty may differ from the actual exam, and we cannot guarantee that every detail is accurate or current. Confirm exam requirements, fees, and policies with the official exam sponsor.

22.52%

Odontologie conservatrice et endodontie

Cariology, operative dentistry, adhesive biomaterials, composite resins, endodontic pathology, root canal therapy, and dental traumatology

22.52%

Parodontologie et chirurgie orale

Periodontal anatomy, AAP/EFP 2018 classification, surgical periodontal therapy, implantology, oral surgery, bone grafting, and cysts and tumors

22.52%

Prothèses et réhabilitation occlusale

Fixed prosthodontics, ceramic biomaterials, removable complete and partial dentures, occlusion, temporomandibular disorders, and CAD/CAM

22.52%

Orthopédie dento-faciale, pédodontie et médecine bucco-dentaire

Craniofacial growth, cephalometrics, interceptive orthodontics, pediatric dentistry, pulpotomy, MIH, and oral mucosal diseases

9.91%

Lecture critique d'article (LCA)

Clinical research design, randomization, bias, effect measures, diagnostic accuracy, confidence intervals, and applicability to dental care

Preparing for the Internat en Odontologie Exam

What You Need to Know

Passing score: Competitive national ranking determining allocation into DES in Orthopédie Dento-Faciale, Chirurgie Orale, and Médecine Bucco-Dentaire
Assessment: The current national rules specify two anonymous written papers: a three-hour composition paper worth 360 points and a three-hour lecture critique d'article (LCA) paper worth 40 points, for 400 points total. The 2026 opening order governs eligibility and the national session; successful candidates choose available DES posts in national rank order.
Time limit: Composition paper 3h + LCA paper 3h (6 hours total)
Exam / certification fees: No separate examination fee is stated in the 2026 opening order Official sources

Using Our Practice Resources

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Internat en Odontologie: Suggested Study Strategy

1Thoroughly review the official 2018 AAP/EFP classification of periodontal and peri-implant diseases, focusing on staging (severity and extent) and grading (rate of progression and risk factors).

2Memorize the International Association of Dental Traumatology (IADT) and HAS guidelines for traumatic dental injuries, particularly luxation, avulsion management (storage media, splinting duration), and root fractures.

3Master biomechanical preparation criteria for fixed and adhesive prosthodontics: ferrule effect (minimum 1.5–2 mm height), biologic width / supracrestal tissue attachment, and ceramic bonding protocols.

4Practice critical reading of dental clinical trials (LCA): CONSORT guidelines, Jadad scale, randomization methods, blinding, intention-to-treat analysis, and risk of bias assessment.

5Understand pediatric dental therapeutics, including pulpotomy with MTA/biodentine, Hall technique for stainless steel crowns, and molar-incisor hypomineralization (MIH) management.

Frequently Asked Questions

What is the format and duration of the Concours de l'Internat en Odontologie?

The current rules specify two anonymous written papers of three hours each: a 360-point composition paper and a 40-point lecture critique d'article (LCA) paper.

Which specialties (DES) can be pursued through the internat?

Laureates access three distinct Diplômes d'Études Spécialisées (DES): (1) DES en Orthopédie Dento-Faciale (ODF, 3 years), (2) DES en Médecine Bucco-Dentaire (MBD, 3 years), and (3) DES en Chirurgie Orale (CO, 4 years), which is shared jointly between the dental and medical internat tracks.

Who is eligible to participate in the national competition?

Candidates must have validated the second cycle of dental surgery studies (5th year / DFASO 2) or hold a French State Diploma of Doctor in Dental Surgery, or an equivalent dental qualification issued by an EU/EEA member state, pursuant to the Arrêté du 12 février 2026.

Is there a registration fee for the examination?

The 2026 opening order does not state a separate examination fee. Candidates should follow the current CNG registration notice rather than assume a universal charge or exemption.

How are residency training posts and university hospital locations allocated?

Following anonymous grading, a single national ranking list (classement national informatisé) is established by the CNG. Candidates choose their DES specialty and University Hospital Center (CHU / Interrégion) in strict order of merit during the computerized matching procedure.