Storage Medium for Avulsed Permanent Teeth

A University Examination Essay in Pediatric and Preventive Dentistry

Introduction

Pathophysiology: Why the PDL Matters

• Within 30 minutes of extraoral dry time, most PDL cells are non-viable (IADT 2020).
• After 60 minutes of completely dry storage, PDL cells are considered uniformly dead, and replantation, while still possible for alveolar bone preservation, will predictably result in ankylosis and root resorption.

1. Osmolality close to physiologic (260-320 mOsm/kg) to prevent osmotic cell lysis or swelling
2. pH between 6.5 and 7.5 to maintain cellular enzymatic function
3. Nutrients (glucose, amino acids, growth factors) to sustain cellular metabolism
4. Non-cytotoxicity - absence of harmful chemicals or microorganisms

Classification of Storage Media

Table 1: Classification of Storage Media for Avulsed Permanent Teeth

Tier 1 Storage Media (Recommended by IADT 2020)

1. Milk

• Osmolality of whole cow's milk (approx. 270-280 mOsm/kg) closely mirrors physiologic tissue fluids.
• pH of 6.4-6.8 is compatible with PDL cell survival.
• Contains essential nutrients: calcium, phosphate, glucose, amino acids, and casein, which provide short-term metabolic support.
• Contains epidermal growth factor (EGF), which actively promotes PDL cell proliferation.
• Largely free of bacteria when refrigerated.
• Cold temperature (4°C) further slows cellular metabolism and reduces autolysis, extending viability.

"In descending order of preference, milk, HBSS, saliva (after spitting into a glass), or saline are suitable and convenient storage mediums." - IADT 2020 Guidelines (Fouad et al., Dental Traumatology 2020;36:331-342)

2. Hank's Balanced Salt Solution (HBSS)

• pH of 7.2-7.4 (precisely physiologic) maintained by HEPES or bicarbonate buffers.
• Osmolality of 270-280 mOsm/kg - virtually identical to extracellular fluid.
• Contains glucose, amino acids, and essential electrolytes (Na⁺, K⁺, Ca²⁺, Mg²⁺, Cl⁻, HCO₃⁻, HPO₄²⁻) to sustain aerobic metabolism.
• Clinically demonstrated to maintain PDL cell viability for 24-72 hours (Roberts & Hedges', 2014) or up to 24 hours (Rosen's Emergency Medicine, 2022).
• The systematic review by Osmanovic et al. (2018) found HBSS maintained 57.3% PDL viability at 24 hours.

3. Dulbecco's Modified Eagle's Medium (DMEM) and Other Culture Media

Tier 2 Storage Media (Acceptable but Suboptimal)

4. Saliva

• Isotonic and biologically compatible.
• Contains growth factors, antimicrobial proteins (lysozyme, secretory IgA, lactoferrin), and proteins that may support PDL cells.

• Variable pH and osmolality between individuals and over time.
• Contains bacteria that can colonize the root surface and cause inflammatory root resorption.
• Hypoxic environment in oral storage leads to metabolic stress.
• Not recommended for young children or unconscious patients due to aspiration risk.
• Recommended duration: up to 30-60 minutes only.

5. Normal Saline (0.9% NaCl)

• Widely available in clinical settings (ambulances, first aid kits, emergency departments).
• Isotonic - prevents acute osmotic cell lysis.

• No nutritional content - cells rapidly exhaust available substrates.
• Acidifies quickly, becoming cytotoxic within 1-2 hours.
• Generally considered acceptable for up to 30-60 minutes only.
• Inferior to milk and HBSS for extended storage.

Tier 3 Storage Media (Investigational / Emerging Evidence)

6. Propolis (10% Concentration)

• Chhabra et al. (2025, Frontiers in Medicine, [PMID: 41114008]) conducted a PRISMA-compliant systematic review of 11 studies. Their results showed that 10% propolis preserved the highest number of viable PDL cells at 30 minutes of extraoral dry time compared to HBSS, milk, coconut water, and pomegranate juice. At extended time points (3, 6, 12, and 24 hours), 10% propolis demonstrated superior PDL cell preservation.
• The network meta-analysis by Zhang et al. (2021, Frontiers in Medicine, [PMID: 34708058]) included 20 RCTs (31 reports) and found that propolis ranked highest in network meta-analysis for PDL cell viability, being statistically superior to HBSS (SMD -5260.24; 95% CrI -10447.39 to -70.37) and milk.
• The systematic review by Resende et al. (2020, Dental Traumatology, [PMID: 31328384]) identified propolis as one of the three most studied plant-derived storage media alongside coconut water and Aloe vera.

7. Coconut Water

8. Aloe Vera Gel

9. Egg White

10. Other Investigated Media

Tier 4: Media to Avoid

Tap Water / Distilled Water

Dry Storage (Air-Drying)

IADT 2020 Priority Order for Storage Media

Table 2: IADT 2020 Recommended Storage Media - Priority Order

Flowchart 1: Emergency Management of Avulsed Permanent Tooth - Storage Medium Decision

TOOTH AVULSED
      |
      v
Is immediate replantation possible?
(Patient conscious, cooperative, no aspiration risk)
      |
     /|\
   YES   NO
    |     |
    v     v
REPLANT  STORE IN MEDIUM
IMMEDIATELY  
(Handle crown only;
rinse with saline if dirty)
      |
      v
Storage Medium Available?
      |
      |---YES: MILK (1st choice) ---------> Store up to 6-8 h
      |
      |---YES: HBSS / Save-A-Tooth -------> Store up to 24-72 h
      |
      |---YES: Saline (0.9% NaCl) ---------> Store up to 30-60 min
      |
      |---YES: Patient's own saliva -------> Store up to 30 min
      |
      |---ONLY WATER available -----------> Store (last resort); 
      |                                     proceed immediately
      |
      |---NOTHING available -------------> Buccal sulcus storage
                                           (if safe)
      |
      v
PROCEED TO DENTAL CLINIC / EMERGENCY DEPARTMENT
(Minimise transport time)
      |
      v
Assess extra-oral dry time (EODT)
      |
      |--- EODT < 60 min (in medium) -----> PDL possibly viable
      |                                     Standard replantation protocol
      |
      |--- EODT > 60 min (any condition) -> PDL likely non-viable
                                            Delayed replantation protocol
                                            (space/bone maintenance purpose)

Flowchart 2: PDL Cell Condition Assessment Before Replantation (IADT 2020)

EVALUATE AVULSED TOOTH ON ARRIVAL

Group A: PDL CELLS VIABLE
- Tooth replanted within ~15 min at accident site
- Action: Standard replantation; root canal after 7-10 days (closed apex)
         or monitor for revascularization (open apex)

Group B: PDL CELLS COMPROMISED BUT POSSIBLY VIABLE
- Tooth stored in: milk, HBSS, saliva, or saline
- EODT (total dry time) < 60 minutes
- Action: Gently agitate in storage medium to clean; do NOT scrub root
         Replant; flexible splint 2 weeks; systemic antibiotics; follow-up

Group C: PDL CELLS NON-VIABLE
- EODT > 60 minutes regardless of storage medium
- Action: Decoronate root or delayed replantation for bone preservation
         Expect ankylosis and eventual root resorption
         Long-term: dental implant or space maintainer planning

Key Properties of Ideal Storage Media: Comparative Analysis

Table 3: Physicochemical Properties and PDL Viability Data

Effect of Time and Medium on Clinical Outcome

• 0-15 minutes: PDL cells are optimally viable even without a storage medium (mild dehydration occurs).
• 15-30 minutes dry: Progressive cell death begins; approximately 50% PDL viability.
• 30-60 minutes dry: Majority of PDL cells non-viable. IADT 2020 states "most PDL cells are non-viable after 30 minutes of dry time."
• >60 minutes dry: Near-complete PDL cell death; replantation for bone/space preservation only.

• In milk: PDL cells remain viable for up to 4-8 hours (Roberts & Hedges').
• In HBSS: PDL cells remain viable for up to 24-72 hours (Roberts & Hedges'; Tintinalli's).
• In Viaspan: 88.4% viability maintained at 24 hours (Osmanovic et al. 2018).

Special Considerations in Pediatric Patients

Open Apex (Immature Permanent Teeth)

• If EODT < 60 minutes and apex open: attempt replantation and monitor for revascularization (pulp revascularization protocol). Root canal treatment is deferred.
• If EODT > 60 minutes: standard replantation; root canal with calcium hydroxide or MTA obturation likely required.

Avulsion of Primary Teeth

Avulsion in Children with Special Health Care Needs

The Role of the Pediatric Dentist and First Responder

1. Patient/parent education: Schools, sports coaches, and parents must be educated on the correct first-aid response: retrieve the tooth by the crown, rinse briefly (10 seconds), place in cold milk, and proceed immediately to a dental clinic.
2. Availability of Save-A-Tooth kits: Pediatric dental offices and school nursing rooms should stock HBSS-based kits.
3. Public health messaging: Milk refrigerators are universally available in schools - this must be communicated as the emergency storage solution of choice.

Summary and Conclusions

Table 4: Summary - Key Clinical Messages for Examination

References

1. Fouad AF, Abbott PV, Tsilingaridis G, et al. International Association of Dental Traumatology Guidelines for the Management of Traumatic Dental Injuries: 2. Avulsion of Permanent Teeth. Dental Traumatology 2020;36(4):331-342. doi: 10.1111/edt.12573. [Endorsed by AAPD 2020]
2. Osmanovic A, Halilovic S, Kurtovic-Kozaric A, Hadziabdic N. Evaluation of periodontal ligament cell viability in different storage media based on human PDL cell culture experiments - a systematic review. Dental Traumatology 2018;34(6):393-399. [PMID: 30193009]
3. Longo DL, Fumes AC, Küchler EC, et al. Efficiency of different storage media for avulsed teeth in animal models: a systematic review. Dental Traumatology 2018;34(1):12-16. [PMID: 28853235]
4. Resende KKM, Faria GP, Longo DL, et al. In vitro evaluation of plants as storage media for avulsed teeth: a systematic review. Dental Traumatology 2020;36(2):109-120. [PMID: 31328384]
5. Zhang N, Cheng Y, Li F, Kang Q. Network Meta-Analysis of 10 Storage Mediums for Preserving Avulsed Teeth. Frontiers in Medicine 2021;8:749278. [PMID: 34708058]
6. Chhabra C, Chhabra KG, Thangeswaran S, Shere S. Concentration of propolis as a storage medium for avulsed teeth: a systematic review. Frontiers in Medicine 2025;12:1583113. [PMID: 41114008]
7. Zerman N, Paglia L, Silva R. Replantation after avulsion of permanent teeth: clinical procedures and adherence of cases reports to IADT Guidelines - a scoping review. European Journal of Paediatric Dentistry 2026. [PMID: 40654128]
8. Rosen's Emergency Medicine: Concepts and Clinical Practice (9th ed., 2022). Chapter 56: Tooth Avulsion, pp. 869-871.
9. Tintinalli's Emergency Medicine: A Comprehensive Study Guide (9th ed.). Chapter 245: AVULSIONS, pp. 1629-1630.
10. Roberts & Hedges' Clinical Procedures in Emergency Medicine (6th ed., 2014). Chapter 64: Luxation and Subluxation, pp. 1826-1828.
11. The Harriet Lane Handbook (23rd ed., Johns Hopkins Hospital). Dental Emergencies - Storage Media Priority.
12. Blomlöf L. Milk and saliva as possible storage media for traumatically exarticulated teeth prior to replantation. Swedish Dental Journal Supplement 1981;8:1-26. [Foundational study]

• IADT 2020 Guidelines provide a priority order (descending preference): Milk > HBSS > Saliva > Saline > Water, without using a "tier" terminology.
• Osmanovic et al. 2018 (PMID: 30193009) and Zhang et al. 2021 (PMID: 34708058) rank media by PDL cell viability percentages and statistical comparisons, but do not use a tiered classification.
• Roberts & Hedges' and Tintinalli's present storage media as a ranked list based on availability and efficacy, again without formal tiers.

• Evidence strength
• Physiologic compatibility
• Clinical availability

1. Attribute the tier framework to your own synthesis - stating it is a structured organization of the IADT 2020 priority order and systematic review evidence.
2. Use the IADT 2020 priority order directly instead, which is the citable, guideline-backed ranking.