Restor Dent Endod.  2016 Nov;41(4):255-261. 10.5395/rde.2016.41.4.255.

Elemental analysis of caries-affected root dentin and artificially demineralized dentin

• Sung YH
• Son HH
• Yi K
• Chang J

• KMID: 2356001
• DOI: http://doi.org/10.5395/rde.2016.41.4.255

Abstract

OBJECTIVES
This study aimed to analyze the mineral composition of naturally- and artificially-produced caries-affected root dentin and to determine the elemental incorporation of resin-modified glass ionomer (RMGI) into the demineralized dentin.
MATERIALS AND METHODS
Box-formed cavities were prepared on buccal and lingual root surfaces of sound human premolars (n = 15). One cavity was exposed to a microbial caries model using a strain of Streptococcus mutans. The other cavity was subjected to a chemical model under pH cycling. Premolars and molars with root surface caries were used as a natural caries model (n = 15). Outer caries lesion was removed using a carbide bur and a hand excavator under a dyeing technique and restored with RMGI (FujiII LC, GC Corp.). The weight percentages of calcium (Ca), phosphate (P), and strontium (Sr) and the widths of demineralized dentin were determined by electron probe microanalysis and compared among the groups using ANOVA and Tukey test (p < 0.05).
RESULTS
There was a pattern of demineralization in all models, as visualized with scanning electron microscopy. Artificial models induced greater losses of Ca and P and larger widths of demineralized dentin than did a natural caries model (p < 0.05). Sr was diffused into the demineralized dentin layer from RMGI.
CONCLUSIONS
Both microbial and chemical caries models produced similar patterns of mineral composition on the caries-affected dentin. However, the artificial lesions had a relatively larger extent of demineralization than did the natural lesions. RMGI was incorporated into the superficial layer of the caries-affected dentin.

Keyword

Artificial caries; Caries-affected dentin; Resin-modified glass ionomer (RMGI); Root caries

MeSH Terms

Bicuspid
Calcium
Dentin*
Electron Probe Microanalysis
Glass
Hand
Humans
Hydrogen-Ion Concentration
Microscopy, Electron, Scanning
Miners
Models, Chemical
Molar
Root Caries
Streptococcus mutans
Strontium
Calcium
Strontium

Figure

• 

  Figure 1 Images of the cross-sectioned surfaces of the specimens from the microbial model (a) and the chemical model (b). EPMA analysis was performed perpendicular to the interface between the caries-affected dentinal wall and RMGI restoration (arrows). EPMA, electron probe microanalysis; RMGI, resin-modified glass ionomer.

• 

  Figure 2 Schematic diagram of the calculation of mineral loss (A) in percentage in the lesion area. The Ca and P contents in the sound dentin (S) were set to 100%. The percentages of Ca and P lost in the demineralized area were calculated. The width (µm) of the demineralized area in the caries-affected dentin was measured where the Ca content ranged between 10% (a) and 95% (b) of that of sound dentin. S is an average mineral content of sound dentin. cps, counts per second. A=b-a×S-∫ab(x-ray intensity of ion) B=∫ab(x-ray intensity of ion)

• 

  Figure 3 SEM images (×300) of the cross-sectioned specimens with artificial caries produced from the (a) microbial, (b) chemical, and (c) natural caries models. All three specimens demonstrate features of caries-affected dentin. A dark band of demineralization zone (dark arrows) is comprised of mineral-depleted intratubular dentin and widened intertubular spaces. The white lines (light arrows) perpendicular to the interface between RMGI and dentin are EPMA scan lines. SEM, scanning electron microscopy; RMGI, resin-modified glass ionomer; EPMA, electron probe microanalysis.

• 

  Figure 4 The mean weight percentages of Ca, P, and Sr were measured at intervals of 0.5 µm starting from the surface of the caries-affected dentin to the deep sound dentin in the microbial, chemical, and natural caries models. (a and b) The Ca and P contents quickly recovered within 20 - 30 µm of the natural caries lesion. Loss of Ca and P gradually recovered at a depth of 80 µm in the chemical caries lesion, while the loss extended to a depth of 140 µm in the microbial caries lesion; (c) The Sr content arose at the surface of the caries-affected dentin within 20 µm, more narrowly in the natural caries lesion. Ca, calcium; P, phosphate; Sr, strontium.

Reference

1. Heijnsbroek M, Paraskevas S, Van der Weijden GA. Fluoride interventions for root caries: a review. Oral Health Prev Dent. 2007; 5:145–152.

2. Amer RS, Kolker JL. Restoration of root surface caries in vulnerable elderly patients: a review of the literature. Spec Care Dentist. 2013; 33:141–149.

3. Perdigão J. Dentin bonding-variables related to the clinical situation and the substrate treatment. Dent Mater. 2010; 26:e24–e37.

4. Ngo H, Ruben J, Arends J, White D, Mount GJ, Peters MC, Faller RV, Pfarrer A. Electron probe microanalysis and transverse microradiography studies of artificial lesions in enamel and dentin: a comparative study. Adv Dent Res. 1997; 11:426–432.

5. Ngo HC, Mount G, McIntyre J, Do L. An in vitro model for the study of chemical exchange between glass ionomer restorations and partially demineralized dentin using a minimally invasive restorative technique. J Dent. 2011; 39:Supplement 2. S20–S26.

6. Hevinga MA, Opdam NJ, Frencken JE, Truin GJ, Huysmans MC. Does incomplete caries removal reduce strength of restored teeth? J Dent Res. 2010; 89:1270–1275.

7. ten Cate JM, Buijs MJ, Miller CC, Exterkate RA. Elevated fluoride products enhance remineralization of advanced enamel lesions. J Dent Res. 2008; 87:943–947.

8. Kidd EA, Fejerskov O. What constitutes dental caries? Histopathology of carious enamel and dentin related to the action of cariogenic biofilms. J Dent Res. 2004; 83(Spec No C):C35–C38.

9. Schwendicke F, Meyer-Lueckel H, Schulz M, Dörfer CE, Paris S. Radiopaque tagging masks caries lesions following incomplete excavation in vitro. J Dent Res. 2014; 93:565–570.

10. Pugach MK, Strother J, Darling CL, Fried D, Gansky SA, Marshall SJ, Marshall GW. Dentin caries zones: mineral, structure, and properties. J Dent Res. 2009; 88:71–76.

11. Joves GJ, Inoue G, Nakashima S, Sadr A, Nikaido T, Tagami J. Mineral density, morphology and bond strength of natural versus artificial caries-affected dentin. Dent Mater J. 2013; 32:138–143.

12. Shen S, Samaranayake LP, Yip HK. In vitro growth, acidogenicity and cariogenicity of predominant human root caries flora. J Dent. 2004; 32:667–678.

13. McComb D, Erickson RL, Maxymiw WG, Wood RE. A clinical comparison of glass ionomer, resin-modified glass ionomer and resin composite restorations in the treatment of cervical caries in xerostomic head and neck radiation patients. Oper Dent. 2002; 27:430–437.

14. De Moor RJ, Stassen IG, van't Veldt Y, Torbeyns D, Hommez GM. Two-year clinical performance of glass ionomer and resin composite restorations in xerostomic head- and neck-irradiated cancer patients. Clin Oral Investig. 2011; 15:31–38.

15. Coutinho E, Yoshida Y, Inoue S, Fukuda R, Snauwaert J, Nakayama Y, De Munck J, Lambrechts P, Suzuki K, Van Meerbeek B. Gel phase formation at resin-modified glass-ionomer/tooth interfaces. J Dent Res. 2007; 86:656–661.

16. AL-Helal AS, Armstrong SR, Xie XJ, Wefel JS. Effect of smear layer on root demineralization adjacent to resin-modified glass ionomer. J Dent Res. 2003; 82:146–150.

17. Ab-Ghani Z, Ngo H, McIntyre J. Effect of remineralization /demineralization cycles on mineral profiles of Fuji IX Fast in vitro using electron probe microanalysis. Aust Dent J. 2007; 52:276–281.

18. Borczyk D, Piatowska D, Krzemiński Z. An in vitro study of affected dentin as a risk factor for the development of secondary caries. Caries Res. 2006; 40:47–51.

19. Boston DW, Liao J. Staining of non-carious human coronal dentin by caries dyes. Oper Dent. 2004; 29:280–286.