Diagnosis: Parulis (Gum Boil) — from a Periapical/Periradicular Abscess

Parulis (arrow) — the gingival swelling with draining sinus tract. (Tintinalli's Emergency Medicine)

Pathophysiology

1. Dental caries → enamel breakdown → invasion of dentinal tubules → pulpitis
2. If untreated: irreversible pulpitis → pulp necrosis
3. Infection spreads apically → periapical abscess
4. Abscess follows path of least resistance through alveolar bone → perforates cortex → drains through gingiva = parulis

Key Examination Points

Investigations

• Periapical dental X-ray (intraoral): look for periapical radiolucency (dark halo around root apex), widening of periodontal ligament space, or loss of lamina dura. This confirms the diagnosis and guides treatment.

Management

• Antibiotics — Amoxicillin is first-line in children (penicillin, amoxicillin, metronidazole, or clindamycin for penicillin allergy). Cover typical oral flora.
• Analgesia — Ibuprofen ± paracetamol (NSAIDs preferred over opioids per ADA guidelines). Avoid injecting local anesthetic directly at the infected/fluctuant site; use a regional block away from the infected tissue if needed.
• The parulis itself is already draining, so formal I&D is not required here. Encourage saline mouth rinses to promote drainage.

• Primary tooth with abscess in a 6-year-old: options are pulpectomy + stainless steel crown (if tooth is restorable and root resorption is not advanced) or extraction.
• Extraction is often preferred for primary teeth close to natural exfoliation time or with extensive root resorption — check the X-ray and the child's dental development stage.
• Space maintainer may be needed after extraction if the permanent successor is not ready to erupt.

Red Flags Requiring Urgent Escalation

• Facial swelling, trismus, or difficulty swallowing → spread to fascial spaces (risk of Ludwig's angina or cavernous sinus thrombosis via infraorbital space)
• Fever, malaise, or elevated WBC → systemic involvement → IV antibiotics/hospital admission
• Periorbital swelling (maxillary teeth) → infraorbital space infection

Root Canal Treatment (RCT) — Step-by-Step Procedure

Step 1 — Diagnosis & Pre-op Assessment

• Clinical examination: tenderness to percussion, palpation, cold/heat testing
• Periapical X-ray: assess root length, number of canals, periapical status, root curvature, root resorption
• Confirm irreversible pulpitis or pulp necrosis (± periapical abscess)

Step 2 — Local Anesthesia

• Infiltration (maxillary teeth) or inferior alveolar nerve block (mandibular teeth)
• For necrotic pulp with acute abscess: anesthesia may be difficult due to lowered local pH; consider intraosseous or intrapulpal injection as supplement
• Long-acting agent (e.g., bupivacaine) reduces post-op discomfort

Step 3 — Rubber Dam Isolation

• Mandatory — prevents contamination of the canal with saliva, protects the patient from irrigants and instruments
• Rubber dam clamp placed on the tooth; dam punched and stretched over the tooth

Step 4 — Access Cavity Preparation

• Objective: straight-line access to all root canal orifices
• High-speed bur used to open the crown through:
  • Anterior teeth: lingual/palatal surface
  • Premolars: occlusal surface
  • Molars: occlusal surface
• Remove entire roof of pulp chamber; locate all canal orifices
• Trephination with an endodontic explorer

Step 5 — Working Length Determination

• Electronic apex locator (preferred) measures distance from access opening to the apical constriction (~0.5–1 mm short of radiographic apex)
• Confirmed with a working length X-ray (file in canal, correlated with radiograph)
• Working length = prevents over-instrumentation beyond the apex

Step 6 — Canal Cleaning & Shaping (Chemo-mechanical Preparation)

a. Mechanical instrumentation

• Manual K-files or H-files (ISO sizes 06–140) OR rotary NiTi files (e.g., ProTaper, WaveOne, Reciproc)
• Technique options:
  • Step-back: start small (size 10/15), work toward apex, then step back in 1 mm increments with progressively larger files
  • Crown-down: start coronal, work toward apex (preferred with rotary NiTi)
• Goal: remove infected dentin, shape the canal to a tapering funnel form

b. Irrigation (chemical cleaning)

• Irrigate copiously between each file; needle kept loose in canal (never wedged)

Step 7 — Canal Drying

• Paper points (ISO-sized, matching the master apical file size) inserted to working length to absorb all moisture

Step 8 — Intracanal Medication (if multi-visit)

• Calcium hydroxide paste placed in canal between appointments
• Action: raises pH → kills residual bacteria, dissolves tissue, promotes healing of periapical lesion
• Sealed with temporary restoration (e.g., Cavit, IRM)
• Wait 1–2 weeks before obturation (especially if abscess present, as in this child's case)

In single-visit RCT (no active infection, non-vital tooth), steps 8 and obturation happen in the same appointment.

Step 9 — Obturation (Sealing the Canal)

Materials:

• Gutta-percha (GP) — primary filling material (semi-solid rubber)
• Root canal sealer (e.g., AH Plus, zinc oxide eugenol–based, calcium silicate–based)

Techniques:

• Excess GP cut at canal orifice with a heated instrument
• Check with post-obturation X-ray: fill should be 0.5–1 mm short of radiographic apex, homogeneous, with no voids

Step 10 — Coronal Restoration

• Crucial step — the most common cause of RCT failure is coronal leakage, not poor obturation
• Temporary restoration placed immediately
• Permanent restoration (composite, full-coverage crown) placed within 2–4 weeks
• Posterior teeth (premolars, molars) must receive a crown — RCT makes the tooth brittle and prone to fracture

Post-op Care

• Mild soreness for 24–72 hours (periapical inflammation) — ibuprofen ± paracetamol
• Avoid chewing on the tooth until crown placed
• Review X-ray at 6 months and 1 year to confirm periapical healing

RCT vs. Pulpectomy in Primary (Deciduous) Teeth

• Only resorbable filling materials used (e.g., zinc oxide eugenol paste, Metapex) — because the roots must resorb naturally as the permanent tooth erupts
• Gutta-percha is not used in primary teeth (it doesn't resorb)
• Instrumentation is more conservative to avoid damage to the permanent tooth bud below