Canine Skull and Dental Anatomy for Practice
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Skull foramina, cranial nerves, the dental formula, occlusion patterns, and the radiographic anatomy behind every dental extraction and regional nerve block in the dog.
- The canine skull has 36–50 bones (depending on whether hyoid, ear ossicles, and sutural bones are counted). The key foramina — infraorbital, mental, mandibular, supraorbital, stylomastoid — are the targets for regional nerve blocks in dental and maxillofacial surgery.
- The permanent dental formula of the dog is I 3/3, C 1/1, P 4/4, M 2/3 = 42 teeth. The deciduous formula is i 3/3, c 1/1, p 3/3 = 28 teeth. The maxillary fourth premolar (P4, the carnassial tooth) and the mandibular first molar (M1, the mandibular carnassial) are the largest teeth and the most common sites of slab fractures and periodontal disease.
- Dental occlusion in the dog: the mandibular incisors rest just palatal (lingual) to the maxillary incisors (scissor bite). The mandibular canine tooth fits into the diastema between the maxillary third incisor and the maxillary canine. Malocclusion — most commonly base-narrow mandibular canines (linguoversion) in dolichocephalic breeds and maxillary brachygnathism ('underbite') in brachycephalic breeds — causes traumatic occlusion and requires interceptive orthodontics or extraction.
- Periodontal disease is the most common disease of adult dogs — by age 3, >80 % of dogs have some degree of periodontitis. The progression from gingivitis (reversible) to periodontitis (irreversible attachment loss) is driven by the subgingival plaque biofilm, which mineralises to calculus, extending into the periodontal pocket.
- The five major skull shapes — dolichocephalic (Collie, Greyhound), mesaticephalic (Labrador, Beagle), and brachycephalic (Bulldog, Pug) — affect not only dental occlusion and periodontal disease patterns but also the position of the skull foramina relative to palpable landmarks.
- A swelling ventral to the eye (infraorbital region) in a dog with a fractured maxillary carnassial tooth (P4) is a tooth root abscess (carnassial tooth abscess) with a draining tract until proven otherwise — the abscess tracks along the path of least resistance, breaking through the maxillary bone ventral to the orbit.
- An oral mass in a dog that bleeds easily, is ulcerated, and has a radiographic appearance of bone lysis is an oral neoplasia (squamous cell carcinoma, fibrosarcoma, or malignant melanoma) until proven otherwise — incisional biopsy is mandatory.
- A dog with the mandible 'dropped' and unable to close the mouth has a mandibular fracture or temporomandibular joint (TMJ) luxation until proven otherwise. If the mandible deviates to one side, the luxation/fracture is on the side TOWARD which the mandible deviates (because the intact side's muscles pull the mandible toward the intact side).
- A dog with chronic halitosis, weight loss, and dysphagia that is refractory to dental treatment has an oropharyngeal or oesophageal foreign body, neoplasia, or systemic disease until proven otherwise — a thorough oral examination under anaesthesia, thoracic radiographs, and blood work are indicated.
The Canine Skull: Bones, Sutures, and Shape Variation
The canine skull is a complex structure of flat and irregular bones united by sutures (fibrous joints) that ossify with age. It houses and protects the brain, the special sense organs (olfactory, visual, auditory), and the upper respiratory and digestive tracts. The skull can be divided into the neurocranium (the bony case for the brain — frontal, parietal, occipital, temporal, sphenoid, ethmoid bones) and the splanchnocranium (the facial skeleton — maxilla, incisive, nasal, zygomatic, lacrimal, palatine, vomer, pterygoid, and mandible).
| Skull Region | Key Bones | Key Features | Clinical Relevance |
|---|---|---|---|
| Calvaria (skull cap) | Frontal, parietal, occipital (squamous part) | The frontal bone forms the dorsal roof of the skull; the external sagittal crest (midline ridge) is the attachment for the temporal muscles | Craniotomy approaches: the rostrotentorial craniotomy enters through the frontal and parietal bones to access the olfactory bulbs and frontal cortex. The external sagittal crest is a thick ridge — avoid it during incision |
| Facial skeleton | Maxilla, incisive, nasal, zygomatic, lacrimal | The maxilla bears the maxillary cheek teeth (P1–P4, M1–M2); the incisive bone bears the maxillary incisors and is separated from the maxilla by the incisivomaxillary suture; the zygomatic bone forms the ventral orbital rim and the zygomatic arch (with the temporal bone) | The incisivomaxillary suture is a site for an oronasal fistula in dogs with severe periodontal disease around the maxillary incisors |
| Temporal bone | Squamous, petrous, and tympanic parts | The tympanic bulla houses the middle ear; the petrous part houses the inner ear; the temporomandibular joint (TMJ) is formed by the mandibular fossa of the squamous part and the condylar process of the mandible | Tympanic bulla osteotomy (ventral or lateral approach) for otitis media; the facial nerve (CN VII) exits the stylomastoid foramen immediately caudal to the tympanic bulla — it must be identified and protected during bulla surgery |
| Mandible | Body, ramus, coronoid process, condylar process, angular process | The mandibular body bears the mandibular teeth; the mandibular canal runs through the body and contains the inferior alveolar nerve and vessels; the mental foramina (rostral, middle, caudal) are the exits for the mental nerves | Mandibular fractures are classified as favourable (the masseter and temporalis muscles pull the fracture fragments together) or unfavourable (the muscles pull the fragments apart). A favourable fracture may heal with a tape muzzle; an unfavourable fracture requires surgical fixation |
Skull Foramina and Cranial Nerve Exits
The cranial nerves exit the skull through predictable foramina. The distances between these foramina vary with skull shape, but the sequence and relationships are invariant. For regional anaesthesia of the head, you must know the foramen, the nerve that exits it, and the palpable landmark that guides your needle.
| Foramen | Nerve (CN) | Structures Innervated | Palpable Landmark (Mesaticephalic Dog) | Clinical Block Technique |
|---|---|---|---|---|
| Infraorbital foramen | Infraorbital n. (V2 — maxillary division of trigeminal) | Maxillary incisors, canine, premolars, and molars (via the superior alveolar branches); skin of the upper lip, nose, and rostral maxilla | Dorsal to the distal root of P3; the foramen is palpable as a depression in the maxillary bone | Insert a 25G needle into the infraorbital foramen and advance into the infraorbital canal (not just at the foramen). Inject 0.5–1.0 mL of local anaesthetic. This block desensitises all maxillary teeth on the ipsilateral side |
| Mental foramina (rostral, middle, caudal) | Mental n. (V3 — mandibular division of trigeminal, via the inferior alveolar nerve) | Skin and mucosa of the lower lip and chin; the rostral mental foramen supplies the incisor region | The middle mental foramen is ventral to the mesial root of P2; the caudal mental foramen is ventral to the mesial root of P3 | A mental nerve block only desensitises the rostral mandibular soft tissues (lip, chin, rostral mucosa) — it does NOT anaesthetise the mandibular teeth. For mandibular tooth anaesthesia, the inferior alveolar nerve must be blocked at the mandibular foramen |
| Mandibular foramen | Inferior alveolar n. (V3) | ALL mandibular teeth on the ipsilateral side; the nerve continues as the mental nerve after exiting the mental foramina | On the medial surface of the mandibular ramus, approximately at the level of the last molar (M3); the foramen is not palpable, but the medial mandible is | Advance a 22G or 25G, 1.5-inch needle along the medial surface of the mandibular ramus, aiming for a point approximately 1 cm rostral to the angular process and 1 cm dorsal to the ventral border of the mandible. Walk the needle off the ventral border and advance it dorsally along the medial surface of the ramus. Aspirate, then inject 1–2 mL of local anaesthetic. This block desensitises ALL mandibular teeth on that side |
| Supraorbital foramen | Supraorbital n. (V1 — ophthalmic division of trigeminal, via the frontal nerve) | Skin of the upper eyelid and forehead | At the dorsal orbital rim, at the zygomatic process of the frontal bone; the foramen is palpable as a depression | A 25G needle is inserted into (or just at the opening of) the supraorbital foramen. Inject 0.5 mL. This block desensitises the upper eyelid for minor procedures (e.g., eyelid mass removal) |
| Stylomastoid foramen | Facial n. (CN VII) | Muscles of facial expression; parasympathetic innervation to the lacrimal, nasal, and salivary glands; taste from the rostral two-thirds of the tongue (via the chorda tympani) | Caudal to the ear base, ventral to the horizontal ear canal, immediately caudal to the tympanic bulla | A block at this foramen provides eyelid akinesia and desensitises the ear canal and tympanic membrane for ear surgery. It is also used diagnostically: if a dog with hemifacial spasm improves after a stylomastoid block, the lesion is peripheral (facial nerve) rather than central |
Dental Formula and Tooth Anatomy
The dog is a diphyodont (two sets of teeth — deciduous and permanent) and heterodont (different tooth types — incisors, canines, premolars, molars). The permanent dentition comprises 42 teeth; the deciduous dentition has 28 teeth (no deciduous molars — molars have no deciduous precursors).
| Tooth Type | Permanent Formula (Maxillary/Mandibular) | Deciduous Formula (Maxillary/Mandibular) | Eruption (Permanent) | Root Number |
|---|---|---|---|---|
| Incisors | I 3/3 | i 3/3 | 2.5–5 months | 1 root per incisor |
| Canines | C 1/1 | c 1/1 | 4–6 months (mandibular often erupt before maxillary) | 1 root per canine (the canine root is the longest tooth root in the dog — up to 2× the crown length) |
| Premolars | P 4/4 (maxillary: P1–P4; mandibular: P1–P4) | p 3/3 (P1 is absent in the deciduous dentition; the deciduous carnassial is p3) | 4–6 months | Maxillary P4 (carnassial): 3 roots (mesiobuccal, distobuccal, palatal). Mandibular P4: 2 roots. P1: 1 root. P2–P3: 2 roots each |
| Molars | M 2/3 (maxillary: M1–M2; mandibular: M1–M3 — note mandible has an extra molar) | None (molars have no deciduous precursors) | M1: 5–7 months; M2: 6–8 months; M3: 7–9 months | Maxillary M1: 3 roots (mesiobuccal, distobuccal, palatal). Maxillary M2: 3 roots. Mandibular M1 (mandibular carnassial): 2 roots (mesial, distal). Mandibular M2–M3: 2 roots each (M3 may have 1 root in small breeds) |
The permanent dental formula can be written as: 2 × (I 3/3, C 1/1, P 4/4, M 2/3) = 42 teeth. The maxillary arcade is wider than the mandibular arcade (anisognathism), so the maxillary cheek teeth sit buccal (outside) the mandibular cheek teeth in normal occlusion.
The carnassial teeth are the largest, most robust teeth in the carnivore dentition — the maxillary P4 and the mandibular M1. They function as shearing blades (the buccal surface of the mandibular M1 shears against the palatal surface of the maxillary P4) for cutting meat and crushing bones. These two teeth are the most common sites of slab fractures (a vertical fracture of the buccal surface, exposing the pulp) and carnassial tooth abscesses.
Dental Occlusion: Normal, Abnormal, and Clinical Consequences
Normal canine occlusion is a scissor bite: the mandibular incisors rest just palatal (lingual) to the maxillary incisors, with the incisal edges of the mandibular incisors contacting the cingulum (the palatal shelf) of the maxillary incisors. The mandibular canine tooth fits into the diastema (space) between the maxillary third incisor (I3) and the maxillary canine tooth. The premolars interdigitate in a 'pinking shear' pattern, with the mandibular premolars positioned palatal to the maxillary premolars.
| Malocclusion Type | Description | Common Breeds | Consequences | Treatment |
|---|---|---|---|---|
| Maxillary brachygnathism (underbite, class III malocclusion) | The mandible is longer than the maxilla → the mandibular incisors are rostral to the maxillary incisors | Brachycephalic breeds (Bulldog, Pug, Boxer, Shih Tzu) — this is actually the breed standard for some | Traumatic occlusion (mandibular incisors traumatise the palatal mucosa); the mandibular canines may impinge on the maxillary canines or the palate | If traumatic: extraction of the offending tooth, crown reduction with pulp capping, or orthodontic movement (in young dogs with actively erupting teeth) |
| Mandibular brachygnathism (overbite, class II malocclusion) | The mandible is shorter than the maxilla → the mandibular incisors are caudal to their normal position (but still palatal to the maxillary incisors) | Dolichocephalic breeds (Collie, Borzoi, Greyhound) | The mandibular canines may traumatise the palatal mucosa or the maxillary canines | Same as above: extraction, crown reduction, or orthodontic movement of the offending tooth |
| Linguoversion of the mandibular canines (base-narrow canines) | The mandibular canines erupt too far palatally (lingually) → they traumatise the hard palate, creating 'palatal pockets' | Dolichocephalic breeds (most common in Collies, Shelties, and sight hounds) | Deep, painful indentations or perforations in the hard palate; chronic pain, reluctance to eat, secondary infection | Ball therapy (encourage the dog to carry a ball of appropriate size to push the canines buccally — effective only in young dogs during active eruption, 4–6 months); extraction of the deciduous mandibular canines (if the permanent canines are erupting lingually); orthodontic movement with an inclined plane or expansion device |
| Rostral crossbite | One or more maxillary incisors are palatal to the mandibular incisors (instead of labial to them) | Any breed; often hereditary | Traumatic occlusion; the malpositioned tooth may be non-vital (the pulp is exposed or the tooth is mobile) | Extraction if the tooth is non-vital or causing significant trauma; orthodontic movement if the tooth is vital and the dog is young |
Radiographic Anatomy for Dental Extractions
Dental radiography is NOT optional for extractions — it is mandatory. Intraoral radiographs reveal: root number and morphology (especially important for the carnassial teeth, which have three roots), root fractures (complete or incomplete), retained root tips, periapical lucency (evidence of apical periodontitis or abscess), periodontal bone loss (horizontal or vertical), the relationship of tooth roots to the mandibular canal (mandibular teeth) or nasal cavity and infraorbital canal (maxillary teeth), and the presence of supernumerary roots or fused roots.
| Tooth | Radiographic View | What to Evaluate | Common Findings |
|---|---|---|---|
| Maxillary P4 (carnassial) | Lateral view (bisecting angle technique); the film is placed intraorally, parallel to the hard palate | Three roots (mesiobuccal, distobuccal, palatal); the mesiobuccal root is the largest and most likely to fracture; the palatal root is the most difficult to extract and is the one most likely to be retained | Slab fracture of the buccal surface (a vertical fracture line is visible on the radiograph); periapical lucency around one or more roots (tooth root abscess); retained root tip (a radiopaque fragment in the alveolus after extraction) |
| Mandibular M1 (mandibular carnassial) | Lateral view; the film is placed intraorally, parallel to the ventral border of the mandible | Two roots (mesial, distal); the distal root is larger and curves distally; the mandibular canal runs ventral to the roots — the mesial root of M1 is the closest root to the mandibular canal | Periapical lucency; mandibular fracture risk: a dog with severe periodontal bone loss around M1 is at risk of iatrogenic mandibular fracture during extraction — always obtain a preoperative radiograph to assess the ventral mandibular bone height (>3 mm of ventral bone is needed for mandibular stability) |
| Maxillary canine | Lateral view; occlusal view (the film is placed between the maxillary and mandibular teeth, and the beam is directed at 90° to the palate) | Single root; the canine root is the longest root in the dog — it extends to the level of the distal root of P2; periapical lucency at the apex | Tooth root abscess from a fractured canine (often from chewing on hard objects); the abscess may drain through the skin of the face (infraorbital fistula) or into the nasal cavity (causing unilateral nasal discharge) |
| Mandibular canine | Lateral view; occlusal view | Single root; the mandibular canine root extends to the level of the distal root of P2; it is closely associated with the mental foramen and the rostral extent of the mandibular canal | Similar to maxillary canine; the abscess may drain through the ventral mandible (submandibular swelling) or intraorally |
Regional Nerve Blocks for Dentistry and Maxillofacial Surgery
Regional anaesthesia of the head enables dental extractions, maxillofacial fracture repair, and soft-tissue surgery to be performed with reduced general anaesthetic requirements and excellent postoperative analgesia. The trigeminal nerve (CN V) provides sensory innervation to the teeth, oral mucosa, and facial skin, and its three divisions are the targets for dental nerve blocks.
| Block | Nerve(s) Blocked | Indication | Technique Summary | Volume (Dog, 20 kg) |
|---|---|---|---|---|
| Infraorbital nerve block | Infraorbital n. (V2) → superior alveolar branches → all maxillary teeth on the ipsilateral side | Extraction or surgery of any maxillary tooth; maxillary fracture repair; nasal surgery | Insert a 25G needle into the infraorbital foramen (dorsal to the distal root of P3). Advance the needle 2–5 mm into the infraorbital canal. Aspirate, then inject. Massage the area to distribute the local anaesthetic | 0.5–1.0 mL |
| Inferior alveolar nerve block (mandibular foramen block) | Inferior alveolar n. (V3) → all mandibular teeth on the ipsilateral side | Extraction or surgery of any mandibular tooth; mandibular fracture repair | Advance a 22G or 25G needle along the medial surface of the mandibular ramus. Landmark: at the level of the last molar (M3), palpate the ventral border of the mandible. Insert the needle 1 cm dorsal to the ventral border and advance it along the medial surface of the ramus. Aspirate (the maxillary artery runs in this region), then inject | 1–2 mL |
| Mental nerve block | Mental n. (V3) → skin and mucosa of the lower lip and chin | Lower lip laceration repair; biopsy or removal of lower lip masses | Insert a 25G needle into (or just at the opening of) the middle or caudal mental foramen (ventral to P2 or P3). Aspirate, then inject | 0.5 mL |
| Maxillary nerve block (extraoral approach) | Maxillary n. (V2) → entire maxillary region on the ipsilateral side, including the maxillary teeth, upper lip, nose, and palate | Major maxillofacial surgery; enucleation; rhinotomy | Extraoral approach: Insert a 22G, 1.5-inch needle ventral to the zygomatic arch, at the level of the lateral canthus. Advance the needle caudoventrally toward the pterygopalatine fossa. Aspirate, then inject. This is a deep block and carries a risk of retrobulbar haemorrhage — use with caution and consider ultrasound guidance | 1–2 mL |
| Retrobulbar block | CN II (optic), III (oculomotor), IV (trochlear), V (trigeminal — ophthalmic division), VI (abducens) | Enucleation; intraocular surgery; treatment of acute glaucoma (reduces intraocular pressure by blocking autonomic input) | Curved needle technique: Insert a 22G, 1.5-inch curved needle at the lateral canthus, directed toward the contralateral mandibular ramus. Aspirate, then inject. Alternatively, a two-point injection (dorsal and ventral to the globe). Retrobulbar haemorrhage is a recognised complication | 2–4 mL total (divided between injection sites) |
- The infraorbital foramen is dorsal to the distal root of the maxillary third premolar (P3) in the dog. For an infraorbital nerve block, advance the needle into the infraorbital canal (not just at the foramen) to anaesthetise the maxillary cheek teeth and the ipsilateral maxillary bone.
- The mandibular foramen is on the medial surface of the mandibular ramus, approximately at the level of the last molar (M3). The inferior alveolar nerve enters here, and a nerve block at this foramen anaesthetises all mandibular teeth on that side. The needle is advanced along the medial mandible, staying close to the bone to avoid the lingual nerve.
- Dental radiographs are essential for every extraction — at least 40 % of the tooth structure (the roots) and 60 % of the periodontal attachment are invisible on oral examination alone. Intraoral radiographs reveal root fractures, retained root tips, periapical lucencies, and the extent of periodontal bone loss.
- When extracting a maxillary carnassial tooth (P4), the three roots must be sectioned and elevated individually. The mesiobuccal root is the most likely to fracture because it curves distally. If a root tip is left behind, the most common cause of a persistent oronasal fistula is a retained mesiobuccal root fragment.
Frequently asked questions
The permanent dental formula is I 3/3, C 1/1, P 4/4, M 2/3 = 42 teeth. Written out: 2 × (incisors 3/3 + canines 1/1 + premolars 4/4 + molars 2/3). The maxillary arcade has 20 teeth (I3, C1, P4, M2 on each side); the mandibular arcade has 22 teeth (I3, C1, P4, M3 on each side). The deciduous formula is i 3/3, c 1/1, p 3/3 = 28 teeth — no deciduous molars and only 3 deciduous premolars (p1 is absent in the deciduous dentition).
Landmark: the infraorbital foramen is dorsal to the distal root of the maxillary third premolar (P3). Palpate the foramen as a depression in the maxillary bone — it is more easily palpated in dolichocephalic and mesaticephalic breeds; in brachycephalic breeds, the foramen is displaced rostrally (dorsal to P2). Insert a 25G needle into the foramen and advance it 2–5 mm into the infraorbital canal. Aspirate (the infraorbital artery runs alongside the nerve in the canal). Inject 0.5–1.0 mL of local anaesthetic (lidocaine 2 % or bupivacaine 0.5 %). Massage the area for 30 seconds to distribute the anaesthetic along the canal. Onset is 5–10 minutes. This block desensitises ALL maxillary teeth and the ipsilateral maxillary bone, upper lip, and nasal planum. It does NOT desensitise the palate — the palatal mucosa is supplied by the greater palatine nerve (also V2) and must be blocked separately if needed.
A slab fracture is a vertical fracture of the buccal (cheek-side) surface of a tooth, creating a 'slab' of enamel and dentin that may be loose or may separate entirely, exposing the pulp cavity. The maxillary P4 is the most commonly affected tooth because it is the largest tooth in the canine dentition and bears the brunt of the shearing and crushing forces during chewing. Hard objects (bones, antlers, nylon chews, ice cubes) are the most common cause. A slab fracture that exposes the pulp (visible as a red or black spot in the fracture line) is a dental emergency — the exposed pulp becomes necrotic, leading to a periapical abscess. Treatment: extraction of the fractured tooth or root canal therapy (endodontic treatment) if the tooth is strategically important and the owner wishes to save it.
The risk of iatrogenic mandibular fracture is highest during extraction of the mandibular first molar (M1), especially in small-breed dogs with pre-existing periodontal bone loss. Risk assessment: (1) Obtain a preoperative intraoral radiograph. (2) Measure the height of the ventral mandibular bone (the bone ventral to the tooth roots) — a minimum of 3 mm of ventral bone height is needed for mandibular stability after extraction. If the ventral bone height is <3 mm, the mandible is at high risk of fracture. (3) Assess for pre-existing pathological fracture (a fracture through an area of severe bone loss — often the mandible is already fractured and the tooth is the only thing holding the segments together). (4) Use a gentle, atraumatic extraction technique — section multi-rooted teeth, use sharp elevators, avoid excessive leverage on the buccal bone plate, and support the ventral mandible with your fingers during elevation. (5) If a fracture occurs, stabilise with an intraoral splint (acrylic or composite bonded to the adjacent teeth) or, in severe cases, bone plating.
Gingivitis is inflammation of the gingiva (gums) without loss of the periodontal attachment — it is REVERSIBLE with professional dental cleaning and home care (tooth brushing, dental chews, oral rinses). Signs: red, swollen gingiva that bleeds on probing; no periodontal pocketing or attachment loss on radiographs. Periodontitis is inflammation of the periodontium (gingiva, periodontal ligament, cementum, alveolar bone) with irreversible loss of the periodontal attachment. Signs: gingival recession, periodontal pocketing (>3 mm depth in a dog), alveolar bone loss on radiographs, tooth mobility, and in advanced cases, oronasal fistulas or pathological fractures. Periodontitis is managed but not cured — the goal is to arrest the disease progression and prevent tooth loss.
Self-check quiz
Test yourself. Answers are below each question — cover them first if you are studying.
- A) I 3/3, C 1/1, P 3/3, M 3/3 = 40 teeth
- B) I 3/3, C 1/1, P 4/4, M 2/3 = 42 teeth
- C) I 2/2, C 1/1, P 3/3, M 2/2 = 32 teeth
- D) I 3/3, C 1/1, P 4/4, M 3/3 = 44 teeth
Show answer
Answer: B) I 3/3, C 1/1, P 4/4, M 2/3 = 42 teeth
The canine permanent dental formula is 42 teeth: I=incisors (3 upper, 3 lower per side), C=canines (1 each), P=premolars (4 upper, 4 lower per side), M=molars (2 upper, 3 lower per side). The maxillary arcade has 20 teeth; the mandibular arcade has 22 teeth. Note the mandible has an extra molar (M3) compared to the maxilla.
- A) Infraorbital foramen
- B) Mental foramen
- C) Mandibular foramen
- D) Stylomastoid foramen
Show answer
Answer: C) Mandibular foramen
The inferior alveolar nerve enters the mandible at the mandibular foramen (on the medial surface of the mandibular ramus) and runs within the mandibular canal, giving off branches to all mandibular teeth before exiting the mental foramina as the mental nerve. A block at the mandibular foramen desensitises ALL mandibular teeth. The mental nerve block only desensitises the lower lip and chin. The infraorbital foramen block desensitises the maxillary teeth.
- A) Zygomatic sialadenitis
- B) Tooth root abscess (carnassial tooth abscess)
- C) Orbital cellulitis
- D) Maxillary sinusitis
Show answer
Answer: B) Tooth root abscess (carnassial tooth abscess)
The roots of the maxillary P4 extend dorsally, close to the ventral orbital rim. When a fractured P4 becomes abscessed, the infection tracks along the path of least resistance — breaking through the thin maxillary bone ventral to the orbit and forming a fluctuant swelling ('carnassial abscess'). The swelling is ventral to the eye, not involving the orbit or the zygomatic salivary gland. Drainage and extraction of the P4 (or root canal therapy) is curative.
- A) 1 root
- B) 2 roots (mesial and distal)
- C) 3 roots (mesiobuccal, distobuccal, palatal)
- D) 3 roots (mesial, distal, lingual)
Show answer
Answer: C) 3 roots (mesiobuccal, distobuccal, palatal)
The maxillary P4 has three roots: mesiobuccal (MB), distobuccal (DB), and palatal (P). The MB root is the largest and most likely to fracture during extraction. The palatal root curves palatally and is the most difficult to extract. All three roots must be sectioned and elevated individually.
- A) Extraction of the mandibular canines
- B) Ball therapy (encourage the puppy to carry a ball to push the canines buccally)
- C) Crown reduction with pulp capping
- D) Orthodontic expansion device
Show answer
Answer: B) Ball therapy (encourage the puppy to carry a ball to push the canines buccally)
At 5 months, the permanent canines are still erupting and the bone is still remodelling. Ball therapy — encouraging the puppy to carry a ball or chew toy of an appropriate diameter — can guide the erupting canines into a more buccal position. This is only effective during the active eruption phase (4–6 months). Extraction of the deciduous mandibular canines may also be indicated if they are interfering with the permanent canines. If ball therapy fails, orthodontic movement or extraction of the permanent canines may be necessary.
