Endodontics – Retreatment, Geriatric & Surgical Endo, Single-Visit Therapy, Resorption, Lasers, Regeneration & Bleaching

Vocabulary flashcards covering key terms, instruments, procedures, materials, pathologies, and concepts from comprehensive endodontic lecture notes: retreatment, geriatric considerations, single-visit therapy, surgical principles, resorption types, laser applications, regenerative endodontics, and tooth bleaching techniques.

Endodontic Retreatment

Non-surgical procedure to remove previous obturation, correct failure causes, re-clean/shape, and re-obturate to restore function and allow periradicular healing.

Criteria for Endodontic Success (Clinical)

No tenderness, normal mobility, no discomfort, normal form/function/esthetics, no infection, swelling, sinus tract, or periodontal breakdown.

Criteria for Endodontic Success (Radiographic)

Normal or slightly thick PDL space, reduction/elimination of rarefaction, intact lamina dura, absence of resorption, dense 3-D fill.

Primary Etiologic Factor in Endodontic Failure

Microbial infection within the root-canal system.

Potential Endodontic Failure

Tooth planned for new crown where existing debridement/obturation quality is questionable; at risk for future failure.

Endodontic Retreat­ment Advantages

Avoids surgery, improves subsequent surgical prognosis, maintains crown-root ratio, better patient acceptance, fewer medical contraindications.

Endodontic Retreat­ment Disadvantages

Unpredictable, time-consuming, costly, possible restoration fracture or need for crown replacement.

Retreatment Access Sequence

Coronal → middle → solvent → patency → working length → apical preparation.

Trans-metal Bur

Special bur for cutting through metal and ceramic during retreatment access.

Tungsten-Carbide End-Cutting Bur

Bur of choice for penetrating existing crowns without skidding.

Crown Removal – Grasping Instrument

Applies inward pressure on opposing handles to lift crown (e.g., K.Y. pliers).

Crown Removal – Percussive Instrument

Delivers controlled tapping force to dislodge restorations (e.g., Coronaflex).

Ultrasonic Energy (Crown/Post)

High-frequency vibration to break cement bonds and facilitate crown or post removal.

Gonon Post Removing System

Mechanism using trephine and extractor to remove parallel or tapered passive posts.

Ruddle Post Removal System

Kit with trephines and tubes for removal of various post types with minimal dentin loss.

Silver Point Removal

Usually accomplished with three Hedström files twisted onto point and withdrawn.

Endosolv-E

Solvent formulated to soften ZOE-based pastes during retreatment.

C+ File

Stainless-steel file with extra stiffness and sharp tip for negotiating calcified canals.

Causes of Instrument Separation

Metal fatigue, unwinding, overuse, excessive bending, improper use, kinking, or corrosion.

Masseran Kit

System of trephine burs and extractors to retrieve broken instruments; cuts CCW and removes dentin aggressively.

Microtube–Screw Wedge Technique

45°-beveled tube slides over broken object; internal stylus turned CCW wedges and extracts fragment.

Age Changes – Enamel

Reduced interprismatic matrix → increased brittleness and crack susceptibility.

Age Changes – Dentin

Secondary/tertiary dentin deposition, reduced tubule diameter, increased calcification, pulp chamber flattening.

Age Changes – Pulp

Decreased volume, fewer cells/vessels/nerve fibers, increased collagen, pulp stones, reduced sensitivity.

Age Changes – Cementum

Thickness may triple (400-500 µm), complicating WL determination and radiographic length interpretation.

Geriatric Endo Diagnostic Challenge

Calcified canals yield false-negative pulp tests; cracked teeth often mimic pulpitis.

Geriatric Access Tips

Use enhanced illumination/magnification, DG-16 explorer, small K-files (#8), create glide path before rotary.

Apical Patency Difficulty (Elderly)

Increased cementum length and canal calcification hinder keeping apex patent.

Single-Visit Endodontics

Complete cleaning, shaping, and obturation in one appointment (≤60 min per Oliet).

Single-Visit Indication – Vital Tooth

Asymptomatic pulp, no apical pathology, patient cooperative and time available.

Single-Visit Contraindication – Acute Apical Abscess

Symptomatic infection with purulent drainage requires multiple visits or drainage.

Single-Visit Advantage – Microbial Control

Eliminates inter-appointment contamination and flare-ups by sealing immediately.

Single-Visit Disadvantage – Clinician Fatigue

Prolonged single session may tire operator and increase errors.

Crown-Down Technique

Enlarges coronal third first, reducing apical debris extrusion and expediting canal prep; preferred for single-visit cases.

Thermoplasticized GP Systems

Injectable gutta-percha (System-B, Obtura, Elements) enabling rapid obturation.

Surgical Endodontics

Removal of tissues other than canal contents (e.g., periradicular surgery) to retain tooth.

Periradicular Surgery Indication – Persistent Lesion

Symptomatic or enlarging lesion on well-treated root where orthograde retreatment is impractical.

Periradicular Surgery Contraindication – Unrestorable Tooth

Poor prognosis due to inadequate crown/root ratio or periodontal support.

Triangular Flap

Sulcular horizontal + one vertical release; offers good access and simple closure.

Rectangular Flap

Sulcular horizontal + two vertical releases; provides greatest access but harder to reposition.

Semilunar Flap

Submarginal curved incision; limited to incision & drainage because of poor closure and scarring.

Ochsenbein-Luebke Flap

Submarginal scalloped rectangular flap sparing marginal gingiva; good access with esthetic benefit.

Osteotomy

Bone window (≈4 mm) created with round bur under coolant to access root apex.

Root-End Resection (Apicoectomy)

Removal of ≈3 mm of apex perpendicular to root to eliminate lateral canals and reduce tubule leakage.

Root-End Preparation

Class I cavity 3 mm deep using ultrasonic tips, parallel to canal, removing isthmus tissue.

Retrograde Filling – MTA

Biocompatible, hydrophilic, radiopaque cement with superior seal but long set and high cost.

Retrograde Filling – Super-EBA/IRM

Reinforced ZOE materials with good strength and lower solubility than plain ZOE.

Surgical Wound Healing Time

Primary intention in 5 days if sutures intact; radiographic bone repair visible ~6 months; complete by 1 year.

Intentional Replantation

Planned extraction, extraoral endodontic repair, and re-insertion of tooth when other treatments impossible.

Hemisection

Surgical separation and removal of one root and associated crown segment of multirooted tooth.

Bicuspidization

Splitting mandibular molar into two premolar-like units, each restored separately.

Root Resection (Root Amputation)

Removal of an entire root while retaining coronal portion and remaining roots.

Endodontic Implant (Historic)

Metal pin extending through apex into bone to stabilize tooth with lost periodontal support.

External Surface Resorption

Self-limiting superficial resorption after luxation/ortho; observe and eliminate stimuli.

External Inflammatory Resorption

Bowl-shaped radiolucencies post-trauma; treat with RCT, Ca(OH)₂ dressing, possible MTA obturation.

External Replacement Resorption (Ankylosis)

PDL lost; root replaced by bone, metallic percussion; decoronation recommended in growing patients.

External Cervical Resorption

Pink discoloration cervical area; treat with trichloroacetic acid, curettage, restoration; RCT if pulp exposed.

Internal Inflammatory Resorption

Uniform radiolucent enlargement of canal; treat with RCT, irrigants, Ca(OH)₂; thermoplastic GP for defects.

Internal Replacement Resorption

Mottled root radiolucency with bone-like deposition; manage with RCT or decoronation in young.

SLOB Rule

Same-Lingual-Opposite-Buccal principle to localize resorptive lesions radiographically.

Class 1 Laser (ANSI)

Low-power device safe under normal use (e.g., laser pointer).

Er:YAG Laser

2940 nm; cuts hard tissue with minimal heat, used for cavity prep, etching, periradicular surgery.

Nd:YAG Laser

1064 nm solid-state laser used for caries prevention, pulp testing, soft-tissue applications.

Laser Doppler Flowmetry

Non-invasive optical method to assess pulp blood flow and vitality.

Laser-Assisted Bleaching

Activation of peroxide gels using argon, CO₂, or diode lasers to accelerate whitening.

Tissue Engineering Triad

Stem cells, scaffold, and signaling molecules (growth factors) required for regeneration.

Stem Cells of Apical Papilla (SCAP)

Postnatal mesenchymal stem cells from root tip capable of forming dentin-like tissue.

Growth Factors in Dentin

BMP-2, BMP-7, TGF-β sequestered in dentin matrix, released on demineralization to promote repair.

Scaffold Requirements

3-D, porous, biocompatible, biodegradable, nutrient diffusion, adequate strength, maintains shape.

Revascularization Protocol – Triple Antibiotic Paste

1:1:1 mix of ciprofloxacin, metronidazole, minocycline placed for 3–4 weeks to disinfect necrotic immature tooth.

Bleeding Scaffold (Revascularization)

Over-instrumentation induces blood clot that supplies cells and signals; CollaPlug placed 3 mm below CEJ.

Vital Pulp Therapy – Direct Pulp Cap

Placement of biocompatible material (e.g., MTA) directly over small pulp exposure to maintain vitality.

Apexogenesis

Maintenance of vital pulp in immature root to allow natural root development and apex closure.

Apexification

Induction of calcified barrier at apex of non-vital immature tooth with Ca(OH)₂ or MTA.

Hydrogen Peroxide (Bleaching)

Powerful oxidizer; 35-40 % in-office, 3-6 % OTC; unstable, burns tissues on contact.

Carbamide Peroxide

Urea + hydrogen peroxide; 10–22 % gels for night-guard home bleaching.

Walking Bleach

Intracoronal mixture of sodium perborate + water sealed in access cavity for several days to whiten non-vital tooth.

Thermocatalytic Bleaching

In-office non-vital bleaching using 30-35 % H₂O₂ activated by heat or light.

External Cervical Resorption Risk Factor

Using sodium perborate with 30 % H₂O₂ in walking bleach increases resorption risk.

Night-Guard Bleaching

Patient-applied tray with 10–15 % carbamide peroxide worn overnight for 2–6 weeks.

Microabrasion

Removal of superficial enamel stains using 37 % phosphoric acid + pumice slurry rubbed for seconds.

Macroabrasion

Mechanical removal of localized superficial defects with fine diamond/fissure bur; often combined with microabrasion.

Bleaching Contraindication – Severe Fluorosis

Porous pitted enamel responds poorly; consider veneers instead.

Bleaching Adverse Effect – Sensitivity

Transient dentin hypersensitivity managed with fluoride varnish, potassium nitrate toothpaste, or sodium ascorbate before bonding.

Barrier Materials for Walking Bleach

MTA or RMGIC placed 2 mm over gutta-percha at CEJ to prevent peroxide leakage and resorption.

Swimmer’s Calculus

Brown-black extrinsic stain from pool water chemicals on frequent swimmers’ teeth.

Diagnodent

Laser-induced fluorescence device for early caries detection.

Er,Cr:YSGG Laser

2780 nm wavelength useful for hard-tissue ablation with minimal thermal damage.

Platelet Rich Plasma (PRP)

Blood concentrate rich in growth factors used as scaffold alternative in regenerative endodontics.

Platelet Rich Fibrin (PRF)

Second-generation platelet concentrate without anticoagulants, forming fibrin matrix releasing growth factors.

Class 4 Laser Hazard

High-power (>0.5 W) lasers posing eye, skin, and fire risks; requires strict safety measures.

MTA Advantages (Apical Filling)

Biocompatible, sets in moisture, excellent seal, induces cementogenesis and osteogenesis.

Endodontic Microscope Benefit

Enhanced visualization for identifying calcified canals, cracks, and aiding instrument retrieval.

KP Retractor

Periosteal retractor (KP-1/2/3) used to hold flap against bone during periradicular surgery.

Lignocaine with 1:50,000 Adrenaline

Preferred local anesthetic concentration for enhanced hemostasis in periradicular surgery.

Air Emphysema Risk

Using high-speed handpiece exhausting air at bur tip during surgery can force air into tissues; use rear-vented handpiece.

Barnes Criteria for Root Apex Identification

Root appears yellow, hard, smooth, non-bleeding, surrounded by PDL staining blue with methylene.

Scar Healing after Surgery

Dense fibrous tissue may fill defect when cortical plates lost; considered successful if asymptomatic.

Decoronation

Removal of crown and submergence of root to preserve alveolar ridge in ankylosed teeth of growing patients.

Sodium Hypochlorite (Bleach Side-Effect)

Increases enamel porosity and alters Ca:P ratio; post-bleach fluoride recommended.