Abstract
Oral biofilm reactor (OBR) and pH cycling (pHC) artificial caries model were employed to evaluate the anti-demineralization effects of four composite filling systems on enamel–root dentin junction. Sixty-four enamel–root dentin blocks (6 mm × 6 mm × 2 mm) each with a cylindrical cavity were randomly assigned to the pHC and OBR group, then four subgroups (n = 8) and filled with either the Beautifil II (BEF, SPRG-filler-containing) or Estelite (EST) composite after the adhesive (either Single Bond Universal (SBU) or FL Bond II (FL, SPRG-filler-containing)). The demineralization lesions of filling interface were examined by micro-computerized tomography (μCT) and swept-source-optical coherence tomography (SS-OCT). According to the degree of interface damage, the caries lesions were sorted into four types: Type A and B (no attachment loss); Type C and D (attachment loss). EST/SBU showed the worst demineralization lesion and attachment loss (100% Type D), while BEF/FL exhibited the shallowest lesion depth (p < 0.05, 145 ± 45 μm on enamel, 275 ± 35 μm on root dentin) and no attachment loss (75% Type A and 25% Type B). Using FL adhesive alone does not effectively reduce enamel demineralization. BEF plays a leading role in acid resistance. The combination of BEF and FL showed a cumulative synergistic effect on anti-demineralization.
Highlights
The applications of adhesives and resin based composite materials have rapidly gained popularity in dentistry based on the concept of minimal intervention
All specimens were randomly divided into two experimental groups (N = 32): the pH cycling model and the oral biofilm reactor (OBR) model
Representative cross-sectional swept-sourceoptical coherence tomography (SS-optical coherence tomography (OCT)) images obtained from pH cycling (pHC) and OBR models are shown in Figures 3 and 4, respectively
Summary
The applications of adhesives and resin based composite materials have rapidly gained popularity in dentistry based on the concept of minimal intervention. The development of recurrent caries remains one of the primary reasons for composite filling replacement [1,2]. Recurrent caries is caused by bacterial infection from either the remaining intrinsic caries or the infiltration of extrinsic cariogenic plaque. When a microleakage has occurred or the bonding interface between the composite restoration and tooth surface has been compromised, the biofilm will accumulate and enhance further bacterial growth that can quickly reach the dentinal tubules. Due to the aging of the global population, especially in developed countries, the risk of root dentin exposure to caries or recurrent caries is increasing [3,4]. Recurrent root caries are more difficult to approach because of their location, which increases the difficulty of treatment by the dentist
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