Introduction

Key Takeaway: Your dentist will ask you to pick a filling. Tooth-colored resin looks good. Silver fillings last a long time. Your choice between these and other options affects how long your filling lasts, how much of your tooth structure needs removal, and how...

Your dentist will ask you to pick a filling. Tooth-colored resin looks good. Silver fillings last a long time. Your choice between these and other options affects how long your filling lasts, how much of your tooth structure needs removal, and how it looks. Some materials are better for back teeth, others for front teeth where appearance matters most. This guide helps you understand the real trade-offs.

Glass ionomer releases fluoride (a mineral that fights cavities). Each type has good and bad sides. Learn about your choices to pick what works best for you and your budget.

Composite Resin: Properties and Indications

What It Is and How It Works

Composite resin is a tooth-colored plastic filling. It's made of plastic mixed with hard powder bits. A special light hardens it.

How Strong Is It:
  • Very strong when you chew
  • Can chip on the edges
  • Wears faster than silver fillings
  • Gets stains over 5-7 years
How It Looks:
  • Over 100 colors to pick
  • Looks like your tooth
  • Some see-through, some solid
  • Glows like real teeth

Indications by Cavity Class

Class I (Occlusal/Pit-and-Fissure Caries):
  • Indication: Excellent for Class I restorations; strong posterior composite materials withstand occlusal forces
  • Advantages: Esthetic (invisible), conservative (minimal preparation required), permits direct restoration
  • Considerations: Proper layering technique critical to minimize shrinkage; incremental application with 1-1.5 mm increments
  • Longevity: 7-10 year clinical studies show 80-90% Class I composite survival; primary failure mode is secondary caries at margins
Class II (Proximal Caries):
  • Indication: Excellent, with proper matrix band and composite placement technique
  • Key factors: Tight matrix band (prevents flash; ensures correct contour), proper proximal fill (replicate natural embrasure), adequate interproximal contacts (prevent food impaction)
  • Technique: Incremental placement with matrix band under tension; proximal surface restoration requires careful contouring
  • Longevity: 8-12 year survival 70-85%; often limited by secondary caries at margins or proximal contact failure
Class III and IV (Anterior):
  • Indication: Gold standard for anterior restorations; esthetics essential
  • Advantages: Direct restoration achievable same appointment; excellent shade/translucency control
  • Class III technique: Conservative preparation, minimal reduction, acid-etch adhesive bonding; excellent outcomes
  • Class IV: Fractured incisal edge; restoration requires proper incisal edge anatomy for function; indirect restoration (veneer) often preferred if significant loss
  • Longevity: 10-15+ year survival for Class III/IV anterior composites; failure primarily from chipping or secondary caries
Class V (Cervical Caries):
  • Indication: Excellent material choice for Class V restorations (cervical erosion, cervical caries)
  • Considerations: Adhesion in dentin-rich cervical areas important; use of intermediate glass ionomer layer (sandwich technique) provides fluoride and remineralization benefit
  • Technique: Proper moisture control, adequate bonding; chamfer or bullnose margin prep improves longevity
  • Longevity: 7-10 years typical for cervical restorations; bulk restoration preferred over thin restoration in sensitive areas

Composite Resin Placement Technique Impact on Longevity

Critical variables: 1. Acid-etch adhesive protocol: Phosphoric acid etching creates micro-retentive surface; essential for composite retention
  • Timing: Etch 15-20 seconds on enamel; 10-15 seconds on dentin
  • Rinsing: Thorough water rinse to remove etchant; tooth surface must appear whitish-opaque when dry
  • Bonding agent: Apply primer then bonding resin; dual-cure or light-cure systems available; ensure complete coverage
2. Incremental layering: Place composite in 1-1.5 mm increments. Light-cure each layer
  • Rationale: Reduces polymerization shrinkage stress; ensures complete polymerization (light must penetrate entire increment)
  • Failure mode: Thick increments (>2 mm) incompletely polymerize in depth; increases secondary caries risk
3. Margin management: Margins placed in enamel preferentially; beveled margins increase longevity by increasing surface area for bonding

4. Contour and contact: Proper occlusal anatomy and tight proximal contacts prevent premature failure and secondary caries

Composite Pros and Cons

Good things:
  • Looks natural and matches your tooth
  • Saves more of your tooth
  • Can be fixed or added to if it breaks
  • Done in one visit
  • Safe for your mouth
Problems:
  • May shrink when it hardens and leave tiny gaps
  • Dentist must keep it dry and build it in thin layers
  • Wears down and gets scratched over time
  • Edges can stain and show after 5-7 years
  • Lasts 7-12 years on average (shorter than silver)

Dental Amalgam: Silver Fillings

What It Is

Amalgam is a silver filling made from mercury mixed with silver, tin, copper, and zinc. It takes 24 hours to harden after placement.

How Strong Is It:
  • Very strong under pressure
  • Similar strength when bent as composite
  • Resists wear extremely well (less than 1 micrometer per year)
  • Stays in place long-term with minimal gaps forming
How Safe Is It: Amalgam is safe. It releases very little mercury. Science shows no health risk. When It's Best Used:
  • Large back teeth fillings
  • For hard biters or teeth grinders
  • When keeping the area dry is hard
  • For people with lots of cavities (silver seals better)
  • Simple cavities

Amalgam Pros and Cons

How Long It Lasts:
  • 95% survive 10 years
  • 80-90% last 20 years
  • Typically lasts 12-18 years (longer than white fillings)
Good things:
  • Lasts a very long time
  • Seals well and stops cavities from coming back
  • Easy to place (doesn't need extreme care)
  • Very strong
  • Wears very little
Problems:
  • Silver/gray color (not good for front teeth)
  • Needs more of your tooth removed than composite
  • Hard to remove if you need it taken out
  • Some worry about mercury (though science says it's safe)
  • Rare mercury allergy

Glass Ionomer Cement (GIC)

What It Is

Glass ionomer is a tooth-colored filling made of glass powder and acid. They mix and harden together. It releases fluoride to fight cavities.

How Strong Is It:
  • Medium strong when you chew (weaker than other types)
  • Can break easily
  • Wears at a medium rate
  • Not for big chewing areas
Fluoride Release: Releases fluoride right after placement. Keeps going for months. Stops cavities on nearby teeth.
  • Moisture sensitivity: Very wet while hardening. Water makes it weak and short-lived.
How It Looks:
  • Color choices: Fewer color choices than composite, but okay for back teeth
  • Shine and see-through: More see-through than composite, and matches teeth fairly well

Indications

Primary indications:
  • Class III/IV: Excellent for anterior restorations when esthetics not paramount (cervical Class III, small cavities)
  • Class V: Ideal for cervical lesions; fluoride release provides remineralization benefit
  • Temporary restorations: Excellent for interim coverage pending definitive restoration
  • ART (Atraumatic Restorative Treatment): Recommended for primary/pediatric dentistry and remote settings where moisture control difficult
  • Intermediate layer: Used as liner beneath composite (sandwich technique) in Class II restorations; fluoride benefit
  • Highly caries-risk patients: Fluoride release provides ongoing anticaries protection
Class indications:
  • Class I/II (posterior): Limited use; inadequate strength for large posterior restorations; used only when esthetics essential or other contraindication to amalgam/composite
  • Class III/V: Excellent; sufficient strength for these smaller restorations

GIC Longevity Data

Clinical performance:
  • 5-year survival: 70-80% for Class I/II restorations (lower than composite/amalgam)
  • 10-year survival: 40-60%; frequent replacement necessary in posterior restorations
  • Class V cervical: 70-80% 10-year survival; superior to composite for cervical lesions
Failure modes:
  • Bulk fracture (lack of strength)
  • Marginal breakdown/ditching (moisture sensitivity, wear)
  • Secondary caries (despite fluoride release, bulk restoration failure rate higher than alternatives)

Resin-Modified Glass Ionomer (RMGIC): Properties and Indications

Composition and Properties

Basic components:
  • Hybrid of GIC and composite resin
  • Contains both acid-base reaction components (GIC) and light-activated resin component
  • Fluoride release similar to GIC (15-20 μg/cm²/day initially)
  • Improved strength compared to conventional GIC (250-350 MPa compressive strength vs. 160-250 MPa)
Properties (compared to GIC):
  • Strength: 30-50% improved over conventional GIC; remains below composite/amalgam
  • Wear resistance: Better than GIC; comparable to composite
  • Moisture sensitivity: Less sensitive than GIC; can tolerate some moisture during setting
  • Setting time: Faster than conventional GIC (light-polymerization plus acid-base reaction)

Indications

  • Similar to GIC with improved strength and durability
  • Class V: Preferred over conventional GIC for cervical lesions requiring greater strength
  • Pediatric: Excellent for primary/young permanent teeth; fluoride benefit with improved durability
  • Intermediate layer: Sandwich technique beneath composite in Class II restorations
  • Transitional restorations: Better than conventional GIC for temporary use

Clinical Performance

5-year survival: 80-90% for Class I/II 10-year survival: 70-85%; superior to conventional GIC; comparable to composite for Class V restorations

Compomers: Properties and Indications

Composition and Properties

  • Hybrid material combining composite and compomer (polyalkenoate) components
  • Light-activated polymerization (unlike GIC and RMGIC that rely on acid-base reaction)
  • Limited fluoride release compared to GIC (10-20 μg/cm²/day)
  • Strength comparable to composite (300+ MPa compressive strength)

Indications

  • Similar to RMGIC but less advantage; primarily used for pediatric Class I/II and Class V
  • Fluoride benefit intermediate between composite and GIC
  • Superior esthetics compared to RMGIC; inferior to composite

Bulk-Fill Composites: Properties and Indications

Composition and Properties

  • Composite resins with modified filler particle size, filler percentage, and/or resin composition permitting increments up to 4-5 mm depth
  • Reduced polymerization shrinkage stress compared to conventional composites
  • Improved light penetration (lower opacity allows thicker increments to polymerize completely)
Advantages over conventional composite:
  • Faster placement (fewer increments needed; appointment time reduced)
  • Potentially reduced shrinkage stress
  • Possibly improved marginal adaptation
Disadvantages:
  • Cost higher than conventional composite
  • Some bulk-fill materials inferior surface characteristics (rougher finish)
  • Long-term data limited (5-7 year clinical studies showing comparable outcomes to conventional composite; 10+ year data lacking)

Indications

  • Class I, II posterior restorations where speed advantageous
  • Large cavities where conventional incremental technique cumbersome
  • Remaining evidence suggests outcomes equivalent to conventional composite; bulk-fill materials do not appear to improve longevity

Clinical Performance

  • 5-year survival: 85-95% comparable to conventional composite
  • Long-term data: Limited; studies ongoing

Material Selection Decision Tree by Cavity Class

Class I (Occlusal Caries)

Material hierarchy (best to acceptable): 1. Amalgam (if posterior visible area minimal)
  • Timeline: Single appointment; hardens within 24 hours for functional use
  • Longevity: 12-18 years; 95%+ 10-year survival
2. Composite (preferred for esthetics or patient preference)
  • Timeline: Single appointment
  • Longevity: 7-12 years; 80-90% 10-year survival
  • Technique: Incremental layering essential; light-cure each layer
3. Bulk-fill composite (alternative to conventional composite; faster)
  • Longevity: Comparable to conventional composite (insufficient long-term data)

Class II (Proximal Caries)

Material hierarchy: 1. Amalgam (posterior, not visible)
  • Longevity: 12-18 years; 95%+ 10-year survival
  • Indications: Large restorations, heavy occlusion, difficult moisture control
2. Composite (preferred for esthetics, anterior visible)
  • Technique: Matrix band essential; tight band ensures proper restoration contour and prevent flash
  • Longevity: 8-12 years; 70-85% 10-year survival
3. Sandwich technique (composite + GIC/RMGIC liner)
  • Rationale: RMGIC liner provides fluoride and serves as stress-absorbing intermediate layer
  • Technique: Place RMGIC liner to depth, then composite restoration over liner
  • Longevity: Potentially improves composite durability in large Class II restorations

Class III (Anterior Proximal)

Material hierarchy: 1. Composite (gold standard)
  • Longevity: 10-15+ years; excellent esthetics essential for anterior
  • Technique: Acid-etch, incremental placement; proper proximal fill without flash
2. GIC/RMGIC (when esthetics less critical)
  • Longevity: 5-10 years
3. Ceramic veneer (if significant structure loss; indirect restoration)
  • Longevity: 10-15+ years

Class IV (Anterior Incisal Edge Fracture)

Material hierarchy: 1. Composite (direct restoration, single appointment)
  • Longevity: 10-15+ years if proper technique and adequate bulk/support
  • Technique: Proper incisal anatomy and buccal/lingual contour essential
2. Ceramic veneer or crown (if significant loss, esthetics demanding)
  • Longevity: 10-15+ years
  • Indication: >50% incisal loss or unsatisfactory composite result

Class V (Cervical Caries/Erosion)

Material hierarchy: 1. RMGIC (preferred for cervical lesions)
  • Longevity: 7-10 years
  • Advantage: Fluoride release, superior bond to dentin, conservative preparation
2. Composite (acceptable alternative)
  • Longevity: 7-10 years
  • Technique: Chamfer or bullnose margin improves longevity
3. GIC (economical, excellent fluoride benefit)
  • Longevity: 5-7 years

Clinical Performance Summary by Material

| Material | Class I/II 10-Yr Survival | Longevity | Esthetics | Strength | Cost | |---|---|---|---|---|---| | Amalgam | 95%+ | 12-18 yrs | Poor | Excellent | Low | | Composite | 80-90% | 7-12 yrs | Excellent | Good | Moderate | | Bulk-Fill Composite | ~85% | 7-12 yrs | Excellent | Good | Moderate-High | | Glass Ionomer | 60-70% | 5-8 yrs | Fair | Poor | Low | | RMGIC | 75-85% | 7-10 yrs | Fair | Fair | Moderate | | Compomer | 75-85% | 7-10 yrs | Good | Fair | Moderate |

Every patient's situation is unique. Talk to your dentist about the best approach for your specific needs.

Conclusion

Picking a filling depends on the cavity type and place. Learn more about Medication Interactions and Oral for additional guidance. Amalgam is best for back teeth. It lasts 12-18 years and is very tough. Great for large fillings and hard biters.

Composite looks great. It lasts 7-12 years when placed well. Glass ionomer releases fluoride. Great for high cavity risk. But it's not as strong. Bulk-fill composites are fast but don't last longer. Your dentist picks the best material for your cavity type.

When your dentist finds a cavity, you have choices. Learn more about Choosing a Dentist Finding for additional guidance. Talk to your dentist about what works best for you.

> Key Takeaway: Introduction