Endodontics and Periodontics
Endodontic principles
Diagnose the pulp and the periapex separately: reversible pulpitis (provoked, brief pain), irreversible pulpitis (spontaneous, lingering), necrotic pulp, symptomatic apical periodontitis, acute apical abscess. Working length ends at the apical constriction, roughly 0.5–1 mm short of the radiographic apex. Cleanse with sodium hypochlorite (tissue solvent, antibacterial, 0.5–5.25%); EDTA removes the smear layer; never mix NaOCl and chlorhexidine - a precipitate forms. Calcium hydroxide is the common intracanal medicament. Obturate with gutta-percha and sealer, and confirm the coronal seal - most failures are coronal leakage, missed canals (especially MB2) or untreated anatomy.
Periodontal principles
The 2018 classification separates staging (severity and complexity: CAL, bone loss, tooth loss) from grading (rate of progression, risk factors). Stage I/II involve CAL of 1–4 mm and coronal-third bone loss; Stage III involves CAL of 5 mm or more with mid-third bone loss and up to four teeth lost; Stage IV adds five or more lost teeth, apical-third bone loss and complex rehabilitation needs. Grade A is slow, B moderate, C rapid - driven by smoking and poorly controlled diabetes.
Traps
Pocket depth alone does not diagnose periodontitis; you need clinical attachment loss. Gingival enlargement from drugs (phenytoin, nifedipine, ciclosporin) reverses only partly with hygiene. Mobility is graded 0–3; furcation involvement I–IV. Non-surgical periodontal therapy plus maintenance remains the foundation; antibiotics are an adjunct, never a substitute.
Rule of thumb
If the question asks how to confirm attachment loss, the answer is probing depth combined with the position of the gingival margin relative to the CEJ.