Iran OMFS Board Exam cheat sheet

Forceps extraction of a maxillary first molar: the buccal roots lie closest to the buccal plate; the palatal root is the largest and most divergent, so apply slow buccal-lingual-palatal expansion rather than apical force.

Winter classification of mandibular third molar angulation uses the angle between the long axis of the second and third molars: mesioangular, distoangular, horizontal, vertical, buccoangular, linguoangular.

Pell and Gregory classification: Class I/II/III by ramus relationship (available space anterior to the anterior border of the ramus), and Position A/B/C by depth relative to the occlusal plane of the second molar.

Lingual nerve is at risk during lingual split or lingual retraction; it lies about 3 mm inferior to the alveolar crest in the third molar region and can be 2-3 mm from the lingual plate.

Inferior alveolar nerve proximity on panoramic imaging: signs of high risk include root deflection, narrowing of the canal, darkening of the root, and interruption of the canal's white line; CBCT is indicated for these.

Dry socket (alveolar osteitis) typically presents on postoperative days 2-4 with severe throbbing pain, empty socket, exposed bone, and no purulence; treatment is irrigation and a medicated dressing, not antibiotics.

Warfarin does not require routine discontinuation for simple extractions when INR is within therapeutic range (usually <=3.5 for simple extractions); check INR on the day and use local hemostatic measures.

For a mandibular molar with hypercementosis or divergent roots, sectioning into individual roots reduces root fracture and nerve traction; a buccal and lingual trough with a straight elevator is preferred over a single forceps delivery.

Odontogenic keratocyst: parakeratinized stratified squamous lining, corrugated surface, palisaded hyperchromatic basal cells, satellite cysts; high recurrence, associated with PTCH1 and nevoid basal cell carcinoma syndrome.

Ameloblastoma: peripheral palisading with reverse polarity, stellate reticulum-like center, islands with cystic degeneration; the unicystic mural type has higher recurrence than intraluminal type.

Adenomatoid odontogenic tumor: often in young patients, anterior maxilla, associated with an impacted canine; duct-like structures and rosette-like calcifications.

Odontoma is the most common odontogenic tumor; compound type has tooth-like denticles, complex type has an irregular mass; both are hamartomas.

Pleomorphic adenoma has a capsule that may be incomplete; enucleation with margin or superficial parotidectomy is preferred over simple enucleation for parotid lesions to reduce recurrence.

Mucoepidermoid carcinoma grading uses cystic component, mucin production, mitoses, neural invasion, and necrosis; MECT1-MAML2 (CRTC1-MAML2) translocation is characteristic.

Lichen planus: band-like lymphocytic infiltrate at the epithelial-connective tissue interface, basal cell liquefactive degeneration, Civatte bodies; erosive type needs biopsy to exclude dysplasia.

Epulis fissuratum and inflammatory papillary hyperplasia are reactive to denture trauma; treatment is surgical excision plus denture correction, and biopsy is required if the clinical picture is atypical.

Le Fort I: horizontal fracture above the apices, through the pterygoid plates; Le Fort II: pyramidal, through the infraorbital rim and nasal bones; Le Fort III: craniofacial disjunction through the nasofrontal suture and zygomatic arch.

Zygomaticomaxillary complex fracture: evaluate the infraorbital nerve, malar projection, eye level, and trismus; the orbital floor and lateral orbital wall are common sites of entrapment.

Orbital floor blowout: forced duction test and coronal CT are key; urgent repair for trapdoor fracture with muscle entrapment in children, within 24-48 hours.

Mandibular angle fracture fixation: a single noncompression miniplate at the superior border may be insufficient for angle fractures; a tension band plus inferior border plate or a single strong plate along the ideal line of osteosynthesis is used.

Condylar fracture: most can be managed closed with early mobilization; absolute indications for open reduction include displacement into the middle cranial fossa, inability to obtain occlusion, and foreign body.

Panfacial fracture sequencing: reestablish the mandible and occlusion first, then the midface from stable to unstable (zygoma, then maxilla, then nose/orbit), and restore vertical and horizontal buttresses.

Dentoalveolar trauma: avulsed permanent tooth - replant immediately or store in milk/saline; splint flexibly for up to 2 weeks; avulsed primary tooth is not replanted.

Naso-orbito-ethmoid fracture: assess telecanthus and medial canthal tendon attachment; intercanthal distance >35-40 mm suggests displacement; repair with transnasal wire or plate fixation.

Le Fort I advancement: the maxilla can be advanced about 5-10 mm; greater advancement requires bone grafting and attention to the soft palate and velopharyngeal function; the descending palatine artery is at risk during downfracture.

BSSO: the lingual nerve is at risk during medial osteotomy and retraction; the inferior alveolar nerve is at risk during split; the proximal segment must be seated in the condylar fossa.

Skeletal Class III correction: mandibular setback is limited by the airway and the posterior pharyngeal wall; large setbacks increase OSA risk; bimaxillary surgery may be preferred.

Vertical ramus osteotomy (IVRO) avoids the inferior alveolar nerve but requires maxillomandibular fixation for healing; it is useful in large setbacks and in patients with nerve risk.

Segmental Le Fort I: anterior segmental osteotomy is used for maxillary excess with normal posterior occlusion; the greater palatine artery and the palatal mucosa are the blood supply, so avoid a full palatal flap.

Distraction osteogenesis: latency 5-7 days, distraction rate 1 mm/day, consolidation 6-8 weeks or more; used in mandibular hypoplasia and craniofacial syndromes.

Cleft orthognathic surgery: maxillary hypoplasia is common after cleft repair; Le Fort I advancement may need more graft and has higher relapse; consider velopharyngeal insufficiency risk.

Surgical relapse after mandibular advancement is greater with larger advancement and with counterclockwise rotation; rigid internal fixation and overcorrection reduce relapse.

TMD classification: masticatory muscle disorders (myalgia, myofascial pain), disc displacement with or without reduction, arthralgia, degenerative joint disease, and headache attributed to TMD.

Disc displacement with reduction: reciprocal click, normal opening; with reduction and intermittent locking: click plus episodes of locking; without reduction: limited opening, deviation to the affected side, no click.

First-line management of TMD: patient education, self-care, soft diet, NSAIDs, physiotherapy, and occlusal splint; irreversible occlusal adjustment is not first-line.

Trigeminal neuralgia: paroxysmal, electric shock-like pain in V2/V3, triggered by touch, chewing, or cold; carbamazepine is first-line; MRI to exclude secondary causes.

Post-traumatic trigeminal neuropathic pain: pain in the distribution of a nerve after trauma, with altered sensation; diagnosis requires history of trauma and sensory change.

Temporomandibular joint ankylosis: fibrous or bony fusion; causes include trauma, infection, and previous surgery; treatment is resection with interpositional arthroplasty and early mobilization.

Burning mouth syndrome: burning in the tongue and lips, often bilateral, no visible lesions, associated with xerostomia and taste change; consider B12, folate, iron, and diabetes screening.

Red flags in facial pain: unilateral hearing loss, nasal obstruction, epistaxis, cranial nerve deficits, weight loss, and persistent ulceration require imaging and biopsy to exclude malignancy.

Implant survival is influenced by primary stability, bone quality, and loading protocol; immediate loading requires adequate insertion torque and splinting.

Guided bone regeneration: barrier membrane plus particulate graft; membrane exposure is the main complication; primary closure and soft tissue thickness are critical.

Free fibula flap: reliable bone length, can include skin paddle; the peroneal artery and its septocutaneous perforators supply the skin; contraindicated if the peroneal artery is the dominant supply to the foot.

Deep circumflex iliac artery (DCIA) flap: good bone height and width for mandibular reconstruction; the internal oblique muscle can be included.

Radial forearm free flap: thin, pliable skin for intraoral lining; the radial artery and venae comitantes; Allen test is required preoperatively.

Zygomatic implants: anchored in the zygomatic body; used for severe maxillary atrophy; risk of sinusitis and orbital injury; require careful trajectory planning.

Osteoradionecrosis: irradiated bone with hypocellularity, hypovascularity, and hypoxia; treatment includes antibiotics, hyperbaric oxygen in selected cases, and resection with vascularized reconstruction for advanced disease.

Medication-related osteonecrosis of the jaw: exposed bone for >8 weeks in a patient on antiresorptives or antiangiogenics; conservative management first; surgery for advanced stages.

Recurrent aphthous stomatitis: minor (<1 cm, heals in 1-2 weeks), major (>1 cm, scarring), herpetiform (multiple small); treat with topical corticosteroids and check for deficiencies.

Oral lichen planus is a chronic T-cell-mediated disease; erosive/atrophic forms need biopsy and follow-up because of malignant transformation risk (low but real).

Leukoplakia: white patch that cannot be rubbed off and cannot be diagnosed as another disease; biopsy for dysplasia; risk factors include tobacco and alcohol.

Oral candidiasis: pseudomembranous (thrush), erythematous, and hyperplastic forms; risk factors include xerostomia, inhaled steroids, diabetes, and immunosuppression; treat with topical nystatin or systemic fluconazole.

Pemphigus vulgaris: intraepithelial IgG autoantibodies to desmoglein 1 and 3; flaccid bullae, positive Nikolsky sign; direct immunofluorescence shows intercellular IgG.

Mucous membrane pemphigoid: subepithelial blistering, linear IgG/C3 at the basement membrane; ocular involvement requires systemic therapy.

Sjögren syndrome: dry eyes and mouth, anti-Ro/SSA and anti-La/SSB, labial salivary gland biopsy with focal lymphocytic sialadenitis; increased lymphoma risk.

Oral cancer red flags: nonhealing ulcer >2 weeks, induration, fixed mucosa, neck mass, and persistent hoarseness; urgent referral for biopsy.

Ludwig angina: bilateral submandibular and sublingual space infection with floor-of-mouth elevation, tongue displacement, and airway compromise; treatment is airway control, IV antibiotics, and surgical drainage.

Danger space and retropharyngeal spread: infection can track to the mediastinum; CT of the neck and chest is indicated for dysphagia, neck swelling, or airway symptoms.

Cavernous sinus thrombosis: from maxillary anterior or midface infection via the angular vein; signs include proptosis, ophthalmoplegia, and fever; requires IV antibiotics and imaging.

Odontogenic infection microbiology is polymicrobial, with streptococci and anaerobes (Prevotella, Porphyromonas, Fusobacterium); amoxicillin-clavulanate or clindamycin are common choices.

Antibiotic stewardship: incision and drainage plus removal of the source is primary; antibiotics are adjunctive and should be narrowed based on culture when possible.

Submandibular space infection: the mylohyoid muscle separates the sublingual and submandibular spaces; infection of the second and third molars often spreads to the submandibular space.

Necrotizing fasciitis: rapid spread, pain out of proportion, crepitus, and systemic toxicity; urgent surgical debridement and broad-spectrum antibiotics; imaging should not delay surgery.

Osteomyelitis of the mandible: clinical diagnosis with imaging; treatment includes antibiotics, removal of the source, and sometimes resection; chronic disease may need decortication.

Lidocaine 2% with 1:100,000 epinephrine: maximum dose 4.4 mg/kg (or 7 mg/kg with epinephrine in some guidelines); calculate mg and cartridge count before injection.

Epinephrine in local anesthetic: maximum recommended dose in healthy adults is about 0.2 mg; in cardiac patients, limit to about 0.04 mg (2 cartridges of 1:100,000).

Malignant hyperthermia: triggered by volatile anesthetics and succinylcholine; signs include hyperthermia, rigidity, and hypercarbia; treat with dantrolene.

Midazolam: benzodiazepine used for sedation; flumazenil reverses; risk of respiratory depression; monitor with capnography and pulse oximetry.

Propofol: rapid onset and offset; causes hypotension and apnea; no antagonist; used for sedation and induction.

Ketamine: dissociative anesthetic with analgesia; can cause emergence reactions and increased secretions; useful in pediatric sedation and asthma.

Perioperative anticoagulation: for patients on DOACs, timing of interruption depends on renal function and bleeding risk; check with the prescribing physician; local hemostatic measures are key.

Postoperative nausea and vomiting: risk factors include female sex, nonsmoking, history of PONV, and opioids; use multimodal prophylaxis with dexamethasone and ondansetron.

Cleft lip repair is typically performed at 3-6 months (rule of 10s: weight >10 lb, hemoglobin >10 g/dL, age >10 weeks); cleft palate repair at 9-18 months.

Cleft palate repair aims to close the defect, restore the levator sling, and preserve blood supply; the greater palatine vessels are the main pedicle for mucoperiosteal flaps.

Velopharyngeal insufficiency after cleft palate repair: hypernasal speech, nasal emission; evaluate with nasopharyngoscopy or videofluoroscopy; treatment includes speech therapy and pharyngeal flap or sphincter pharyngoplasty.

Pierre Robin sequence: micrognathia, glossoptosis, and airway obstruction; often with cleft palate; manage airway first, then feeding, then surgery.

Hemifacial microsomia: first and second branchial arch derivatives affected; mandibular hypoplasia, ear anomalies; treatment staged with distraction and orthognathic surgery.

Crouzon syndrome: craniosynostosis with midface hypoplasia and exophthalmos; FGFR2 mutations; treatment includes cranial vault remodeling and midface advancement.

Alveolar bone grafting for cleft: typically at 6-12 years, before canine eruption; iliac crest is a common donor; improves bone support and allows tooth eruption.

Cleft team care is multidisciplinary: audiology, speech, orthodontics, genetics, psychology, and surgery; long-term follow-up is essential.

Trigeminal nerve: V1 ophthalmic, V2 maxillary, V3 mandibular; V3 exits the foramen ovale and gives off the inferior alveolar, lingual, and buccal nerves.

Facial nerve: exits the stylomastoid foramen; divides into temporal, zygomatic, buccal, marginal mandibular, and cervical branches; the marginal mandibular branch is at risk in submandibular surgery.

Blood supply of the face: facial artery from the external carotid; the angular artery anastomoses with the ophthalmic artery, providing a route for cavernous sinus infection.

Lingual nerve: runs medial to the mandible, crosses the submandibular duct; at risk during third molar surgery and submandibular gland excision.

Bone healing: primary healing with rigid fixation; secondary healing with callus; the mandible has a rich blood supply; the irradiated mandible has poor healing.

Nerve injury classification (Seddon): neurapraxia (reversible), axonotmesis (axon damaged, myelin intact), neurotmesis (complete transection); Sunderland grades I-V.

Wound healing phases: hemostasis, inflammation, proliferation, and remodeling; collagen type III is replaced by type I during remodeling.

Antibiotic prophylaxis for infective endocarditis: only for high-risk cardiac conditions (prosthetic valve, previous IE, certain congenital heart disease) before invasive dental procedures; follow current national guidance.

Sensitivity = true positives / (true positives + false negatives); specificity = true negatives / (true negatives + false positives); both are intrinsic to the test and independent of prevalence.

Positive predictive value depends on prevalence; a positive test in a low-prevalence population has a lower PPV than in a high-prevalence population.

Randomized controlled trial: randomization reduces selection bias; blinding reduces measurement and performance bias; intention-to-treat analysis preserves randomization.

Confidence interval: 95% CI means that if the study were repeated, 95% of such intervals would contain the true parameter; it is not a 95% probability that the true value lies in the interval.

P-value: probability of observing the data (or more extreme) if the null hypothesis is true; it is not the probability that the null hypothesis is true.

Number needed to treat = 1 / absolute risk reduction; NNT is useful for clinical decision-making.

Systematic review: explicit search strategy, inclusion criteria, quality assessment, and meta-analysis when appropriate; heterogeneity is assessed with I-squared and Cochran Q.

Levels of evidence: systematic reviews of RCTs at the top; then RCTs, cohort studies, case-control studies, case series, and expert opinion.

Informed consent requires disclosure of diagnosis, proposed treatment, alternatives, risks, benefits, and consequences of no treatment; it must be documented and obtained by the treating clinician.

Confidentiality: patient information may be disclosed only with consent or where required by law; minimum necessary disclosure applies.

Medical error disclosure: patients should be told about harmful errors; disclosure is an ethical and often legal duty; documentation should be factual and timely.

Record keeping: contemporaneous, legible, signed, and dated notes; alterations should be dated and signed; records are legal documents.

Negligence requires duty, breach, causation, and damages; expert testimony is often needed to establish the standard of care.

Scope of practice: treatment should be within the clinician's training and competence; referral is appropriate when beyond that scope.

Patient safety: wrong-site tooth extraction prevention includes verification of patient identity, tooth number, and imaging; use a surgical safety checklist.

Advertising and social media: avoid misleading claims, protect patient privacy, and obtain consent for identifiable images.