10.4 Pit and Fissure Sealants, Casein Phosphopeptide-Amorphous Calcium Phosphate (CPP-ACP)

10.4 Pit and Fissure Sealants, Casein Phosphopeptide-Amorphous Calcium Phosphate (CPP-ACP)

Preventive restorative procedures and non-invasive remineralisation therapies represent major pillars of modern Australian pediatric and adult preventive dentistry. Complex occlusal pit and fissure anatomy accounts for over 80% to 90% of all carious lesions in permanent pediatric dentition. Combining micro-mechanically bonded pit and fissure sealants with bio-active remineralising technology—specifically Casein Phosphopeptide-Amorphous Calcium Phosphate (CPP-ACP / Recaldent)—enables clinicians to protect high-risk anatomical sites and arrest non-cavitated enamel lesions. Mastering these materials, techniques, and biological contraindications is essential for clinical practice and the Australian Dental Council (ADC) Written Examination.

---

1. Pit & Fissure Vulnerability & Sealant Indications

A. Occlusal Anatomy & Caries Vulnerability

Occlusal surfaces of newly erupted permanent first and second molars possess complex morphological invaginations (categorised anatomically as I, K, U, V, and Y-type fissures). Deep I-type and K-type fissures often narrow down to fissure widths of < 0.1 mm, which is significantly smaller than the diameter of a single toothbrush bristle (~0.2 mm). These retentive anatomical invaginations shield acidogenic anaerobic bacteria (S. mutans) from mechanical toothbrushing and salivary buffering, creating a highly cariogenic micro-environment.

B. Indications & Contraindications for Pit & Fissure Sealants

Guidelines from the Australian Academy of Paediatric Dentistry (AAPD) and ADA support evidence-based sealant application:

• Primary Prevention Indications: Newly erupted permanent molars (within 2 to 4 years post-eruption) in children and adolescents classified as Moderate or High Caries Risk, or teeth presenting with deep, retentive, stained fissures.
• Secondary Prevention Indications: Teeth displaying non-cavitated enamel lesions (ICDAS Codes 1 and 2, or radiographically E1/E2 lesions). Sealing non-cavitated lesions deprives trapped bacteria of fermentable carbohydrate substrates, causing bacterial viability to plummet and arresting lesion progression.
• Contraindications:
  1. Fully cavitated carious lesions extending into dentine (ICDAS Codes 3 to 6 requiring operative restoration).
  2. Approximal (interproximal) dentinal caries on the same tooth.
  3. Shallow, well-coalesced, self-cleansing occlusal fissures in low-risk individuals.

---

2. Material Science Selection Matrix: Resin vs. Glass Ionomer Sealants

Selecting the appropriate sealant material depends on patient compliance, tooth eruption stage, and moisture isolation feasibility.

---

3. Step-by-Step Clinical Protocol for Resin Pit & Fissure Sealants

Execution of precise clinical steps is vital to eliminate microleakage, which can lead to secondary caries under the sealant.

1. Surface Cleansing: Thoroughly clean the occlusal surface using a slurry of oil-free pumice and water with a prophy brush or cup, or use air abrasion (aluminum oxide). Avoid commercial prophylaxis pastes containing oils or fluorides, as oils impair resin bonding and excess fluoride reduces acid etch depth.
2. Isolation: Establish absolute moisture isolation using a rubber dam (gold standard) or cotton rolls combined with dry angles and high-volume evacuation.
3. Acid Etching: Apply 37% phosphoric acid gel to the fissure network, extending 2 mm up the cusp inclines.
   • Permanent Enamel: Etch for 15 to 20 seconds.
   • Primary Enamel: Etch for 20 to 30 seconds (due to the presence of an organic, aprismatic enamel surface layer).
4. Rinsing & Drying: Wash thoroughly with water spray for 15 seconds. Dry with clean, oil-free compressed air until the etched enamel exhibits a uniform, frosty, chalky-white appearance.
   • CRITICAL CONTAMINATION RULE: If saliva contacts etched enamel even for 1 second, salivary proteins immediately adsorb onto enamel micro-pores. The clinician must re-isolate, re-etch for 10 seconds, rinse, and re-dry.
5. Bonding Agent Application (Recommended): Applying a single coat of a universal or etch-and-rinse bonding agent prior to sealant placement significantly increases bond strength and reduces microleakage.
6. Sealant Placement & Light-Curing: Apply resin sealant slowly to avoid incorporating air bubbles. Tease the material into deep fissures using a sharp explorer tip. Light-cure for 20 seconds.
7. Post-Placement Inspection: Inspect the sealant with an explorer to confirm complete coverage, smooth margins, and absence of voids. Check occlusion with articulating paper and adjust high spots using a fine finishing diamond bur.

---

4. Casein Phosphopeptide-Amorphous Calcium Phosphate (CPP-ACP / Recaldent)

Developed at the University of Melbourne, Casein Phosphopeptide-Amorphous Calcium Phosphate (CPP-ACP) commercialized as Recaldent represents a breakthrough bio-active remineralisation technology.

A. Biological Derivation & Mechanism of Action

CPP-ACP is derived from the milk protein casein (specifically a tryptic digest of bovine milk casein). Casein phosphopeptides (CPP) contain specific multiphosphoseryl sequence motifs that bind and stabilize calcium ($Ca^{2+}$) and phosphate ($PO_4^{3-}$) ions in an amorphous, soluble state (Amorphous Calcium Phosphate - ACP).

CPP-ACP Remineralisation Bio-Mechanism:

 [CPP Cluster] <---> Binds & Stabilizes <---> [Ca2+ and PO43- (ACP State)]
                                  |
           Attaches to Plaque Biofilm & Enamel Surface
                                  |
    Under Acid Challenge (pH Drop) --> Releases Free Ca2+ & PO43- Ions
                                  |
    Diffuses down concentration gradient into Subsurface Enamel Lesion
                                  |
           Drives Subsurface Crystal Growth & Remineralisation

• Super-Saturation Reservoir: CPP-ACP binds readily to oral mucosal surfaces, salivary pellicle, and plaque biofilm, establishing a high-concentration reservoir of bio-available calcium and phosphate.
• Acid-Triggered Release: When plaque pH drops during an acid challenge, CPP releases free $Ca^{2+}$ and $PO_4^{3-}$ ions into plaque fluid, suppressing demineralisation.
• Subsurface Remineralisation: Driven by concentration gradients, free $Ca^{2+}$ and $PO_4^{3-}$ ions diffuse through the porous surface zone into the body of subsurface enamel lesions (e.g., post-orthodontic white spot lesions or Molar Incisor Hypomineralisation - MIH), remineralising hydroxyapatite crystals.

B. Clinical Indications for CPP-ACP (Tooth Mousse)

• Remineralisation of post-orthodontic debonding white spot lesions.
• Management of sensitivity and enamel fragility in Molar Incisor Hypomineralisation (MIH).
• Relief of dentine hypersensitivity following tooth whitening or periodontal surgery.
• High Caries Risk and Extreme Risk patients suffering from radiation-induced xerostomia or Sjögren's syndrome.

---

5. CPP-ACFP (Recaldent + Fluoride) & Absolute Contraindications

A. Synergistic Action of CPP-ACFP (Tooth Mousse Plus / MI Paste Plus)

CPP-ACFP incorporates 900 ppm fluoride (0.2% NaF) into the CPP-ACP complex. This combination produces a powerful synergistic effect: CPP-ACP delivers the necessary calcium and phosphate building blocks, while fluoride accelerates the crystal transformation into fluorapatite ($Ca_{10}(PO_4)_6F_2$). This co-delivery avoids the premature precipitation of insoluble calcium fluoride crystals that occurs when high-dose fluoride is applied alone without adequate calcium.

• Clinical Application Protocol: Apply a pea-sized amount to tooth surfaces using a clean finger, microbrush, or custom soft tray after evening toothbrushing. Expectorate after 3 minutes; do not rinse, eat, or drink for 30 minutes.

B. Absolute Clinical Contraindication (ADC Exam Must-Know)

• IgE-Mediated Milk Protein (Casein) Allergy: CPP-ACP is derived from bovine milk casein. Products containing Recaldent (GC Tooth Mousse, GC Tooth Mousse Plus, MI Paste) are STRICTLY CONTRAINDICATED in patients with a confirmed IgE-mediated milk protein allergy.
• Lactose Intolerance Distinction: CPP-ACP products are SAFE for patients with Lactose Intolerance. Lactose is a milk sugar, whereas CPP-ACP is a purified protein complex; total lactose content in Tooth Mousse is below analytical detection limits (<0.01%).

---