Comparison of deproteinization agents on bonding to developmentally hypomineralized enamel

J Dent. 2017 Dec;67:94-101. doi: 10.1016/j.jdent.2017.10.004. Epub 2017 Oct 12.


Objective: To compare bonding of dental adhesive to hypomineralized enamel (HE) after pre-treatment with either 5% sodium hypochlorite (NaOCl) solution or papain-based papacarie gel.

Methods: Normal enamel (NE) and HE obtained from hypomineralized first permanent molars were acid-etched with 32% phosphoric acid and randomly allocated into no deproteinization, deproteinization using 5% NaOCl, or deproteinization usping papacarie gel groups. Subsequently, the specimens were bonded, packed with composite resins and subjected to micro-shear bond strength (MSBS) testing and the data analysed using 2-way ANOVA and Tukey tests. Furthermore, specimens from all groups were subjected for qualitative analysis using scanning electron microscope.

Results: Two way-ANOVA showed that the factor "enamel substrate" was significant (p<0.001), "enamel pre-treatment" was not significant and interaction of the two factors was significant (p=0.005). HE produced inferior bonding with dental adhesive compared to NE. Enamel pre-treatment with deproteinization agents enhanced bonding to HE. No significant difference in MSBS was evident between the two deproteinization agents (p>0.05). Qualitative analysis of acid-etched moderate HE showed barely visible enamel rods with irregular etching pattern. Following acid etching and deproteinization, Type I and II etching patterns were observed in moderate HE; while a porous enamel surface with more profound etching patterns in severe HE.

Conclusions: Papain-based papacarie could be an alternative deproteinization agent for bonding dental adhesive to HE.

Clinical significance: Papain-based papacarie, a natural deproteinization agent and a proven chemo-mechanical caries removal agent could be an alternative to NaOCl for enhancement of bond durability of adhesive restorations to HE.

Keywords: Bonding; Dental adhesive; Deproteinization; Hypomineralized enamel; Papacarie; Sodium hypochlorite.

MeSH terms

  • Acid Etching, Dental / methods*
  • Composite Resins / chemistry*
  • Dental Bonding / methods*
  • Dental Cements / chemistry
  • Dental Cements / pharmacology*
  • Dental Enamel / drug effects*
  • Dental Enamel / ultrastructure
  • Dental Enamel Proteins / drug effects*
  • Dental Stress Analysis / instrumentation
  • Dentin-Bonding Agents / chemistry
  • Dentin-Bonding Agents / pharmacology*
  • Humans
  • Materials Testing
  • Molar
  • Papain / chemistry
  • Papain / pharmacology
  • Phosphoric Acids / chemistry
  • Protein Denaturation
  • Resin Cements / chemistry
  • Shear Strength
  • Sodium Hypochlorite / chemistry
  • Sodium Hypochlorite / pharmacology
  • Surface Properties


  • Composite Resins
  • Dental Cements
  • Dental Enamel Proteins
  • Dentin-Bonding Agents
  • Papacarie
  • Phosphoric Acids
  • Resin Cements
  • Sodium Hypochlorite
  • phosphoric acid
  • Papain