Secondary Caries Adjacent to Bulk or Incrementally Filled Composites Placed after Selective Excavation In Vitro.

OBJECTIVES: selective caries excavation (SE) is recommended for deep carious lesions. Bulk fill composites (BF) may be considered to restore SE-cavities. We compared the susceptibility for secondary caries adjacent to BF versus incrementally filled composites (IF) in SE and non-selectively excavated teeth (NS) in vitro. METHODS: in 72 extracted human premolars, artificial caries lesions were induced on pulpo-axial walls of standardized cavities. The lesions were left (SE) or removed (NS), and teeth were restored using two BF, GrandioSO x-tra/Voco (BF-Gra) and SDR/Dentsply (BF-SDR), and an IF, GrandioSO/Voco (IF-Gra) (n = 12/group for SE and NS). After thermo-mechanical cycling (5-55 °C, 8 days), teeth were submitted to a continuous-culture Lactobacillus rhamnosus biofilm model with cyclic loading for 10 days. Mineral loss (ΔZ) of enamel surface lesions (ESL), dentin surface lesions (DSL), and dentin wall lesions (DWL) was analyzed using transversal microradiography. RESULTS: ΔZ was the highest in DSL, followed by ESL, and it was significantly lower in DWL. There were no significant differences in ΔZ between groups in DSL, ESL, and DWL (p > 0.05). Regardless of lesion location, ΔZ did not differ between SE and NS (p > 0.05). CONCLUSIONS: BF and IF both showed low risks for DWL (i.e., true secondary caries) after SE in vitro, and surface lesion risk was also not significantly different between materials. SE did not increase secondary caries risk as compared with NS. CLINICAL SIGNIFICANCE: the risk of secondary caries was low after selective excavation in this study, regardless of whether bulk or incrementally filled composites were used.

Remineralization effects of conventional and experimental ion-releasing materials in chemically or bacterially-induced dentin caries lesions.

OBJECTIVES: The aim of this study was to evaluate the remineralization effects of conventional and experimental ion-releasing materials on different artificial dentin carious lesions. METHODS: Forty human dentin discs were submitted to different demineralization protocols for simulated caries lesion: (D1) Shallow chemically-induced caries, (D2) deep chemically-induced caries, (D3) deep bacterially-induced caries. Each disc was divided in five parts; one of those served as baseline control. The remaining parts of each disc (n=12-16/group) were treated using the following materials: EXP, an experimental resin-based bioactive material consisting of a self-etch primer and an adhesive containing a fluoride-doped bioglass; GIC, a glass ionomer cement (Riva LC); MTA, Mineral Trioxide Aggregate (ProRoot MTA); BIO, a calcium silicate cement (Biodentine). Specimens were mounted in a dual-chamber device to simulate the exposure to pulpal pressure and oral fluids. After 3 months, mineral and mechanical gains were assessed using transverse microradiography (vol% × µm) and microhardness measurements (VHN). Characterization using confocal microscopy and transmission electron microscopy (TEM) was also performed. RESULTS: All four restorative materials induced mineral gains regardless of the protocol for caries lesion, without significant differences between materials. Microhardness significantly increased in the groups BIO and MTA, but not GIC; EXP only provided hardness gains in D3-lesions. Fluorescence and confocal microscopy confirmed these results. There was a clear "top-down" remineralization in the groups BIO and MTA, and "bottom-up" intrafibrillar collagen remineralization in EXP. SIGNIFICANCE: Mineral gains did not always translate into hardness gains. Biodentine and MTA induced evident mineral precipitation, but intra/inter-fibrillar collagen mineral infiltration was only provided by biomimetic remineralisation via the use of the experimental adhesive. Complete remineralization of caries lesions remains a challenge.

In vitro performance of the DIAGNOcam for detecting proximal carious lesions adjacent to composite restorations.

OBJECTIVES: To assess the accuracy of near-infrared-light transillumination (DIAGNO) compared to visual-tactile (VT) and radiographic (RA) evaluation of proximal carious lesions adjacent to composite restorations in vitro. METHODS: Two hundred extracted posterior permanent human teeth with occluso-proximal composite restorations were allocated to 50 groups of four posterior teeth, and mounted in a pilot-tested diagnostic model in a dummy head. The teeth were independently assessed by two examiners. Transverse microradiography and visual assessment served as reference tests to detect any lesions (prevalence 24%) and cavitated lesions (18%), respectively, adjacent to restorations. Sensitivity, specificity, positive and negative predictive values and the area under the receiver-operating-characteristics curve (AUC) were calculated. RESULTS: To detect any proximal carious lesions adjacent to composite, the mean sensitivity/specificity were 0.63/0.95 for DIAGNO, 0.70/0.88 for RA when lesions radiographically extending into enamel and dentin were considered, 0.26/0.98 for RA when only lesions extending into dentin were considered, and 0.31/0.96 for VT. For cavitated lesions adjacent to proximal composite restorations, these values were RA (enamel and dentin) 0.84/0.88, RA (dentin) 0.34/0.99, DIAGNO 0.69/0.94 and VT 0.40/0.97. AUC did not differ significantly between RA and DIAGNO, while VT showed significantly lower values (p < 0.05). CONCLUSION: Within the limitations of this study, DIAGNO seems useful for detecting proximal carious lesions adjacent to restorations. CLINICAL RELEVANCE: Near-infrared-light transillumination could be used as a radiation-free adjunct or alternative to RA for detecting carious lesions adjacent to composite restorations.

Glass hybrid, but not calcium hydroxide, remineralized artificial residual caries lesions in vitro.

OBJECTIVES: For deep carious lesions, less invasive carious tissue removal is recommended. The resulting residual carious lesions might benefit from remineralization by lining or restoration materials. We aimed to compare mineral gains in artificial residual lesions provided by calcium hydroxide and glass hybrid materials in combination with pulpal fluid simulation. METHODS: On the coronal aspect of human dentin discs (n = 20), artificial carious lesions were induced using acetic acid. Median mineral loss ΔZ [25th/75th percentiles] of resulting lesions was 1643 [1301/1858] vol% µm. One third of each disc served as baseline sample. The remaining disc was divided into four groups, each being covered with one experimental material (n = 20/group): flowable composite (control (CO)), setting or non-setting calcium hydroxide liner plus flowable composite (CH-S, CH-NS), and glass hybrid (GH). Samples were mounted in a dual-chamber device. Pulpal surfaces were exposed to simulated pulpal fluid at 2.94 kPa. Coronal surfaces were exposed to artificial saliva and rinsed with 200 ppm NaF every 2 weeks. After 12 weeks, mineral loss differences (ΔΔZ) were assessed using transverse microradiography. Electron probe microscopic analysis was used to measure fluoride and strontium concentrations. RESULTS: Mineral gains were not significantly different between CO (ΔΔZ = 372 [115/501] vol% µm), CH-S (ΔΔZ = 317 [229/919] vol% µm), or CH-NS (ΔΔZ = 292 [130/579] vol% µm; p > 0.05/Wilcoxon test) but significantly increased in GH (ΔΔZ = 1044 [751/1264] vol% µm, p < 0.001). Samples in GH showed fluoride and strontium enrichment deep into the dentin. Such enrichment was not found in CO. CONCLUSIONS: Within the limitations of this study, GH, but not calcium hydroxide, provided coronal remineralization of residual carious lesions. CLINICAL RELEVANCE: Glass hybrids might provide additional remineralization of residual carious lesions. The functional implications of this mineral gain need to be evaluated.

Pulpal Remineralisation of Artificial Residual Caries Lesions in vitro.

We assessed pulpal remineralisation of caries lesions in vitro. On the coronal aspect of human dentin discs (n = 70), artificial lesions [mineral loss x0394;Z (mean ± SD) = 3,060 ± 604 vol% × µm] were induced, covered and pulpal surfaces exposed to pulpal fluid, remineralisation medium or water at pressures of 0, 1.47 or 2.94 kPa for 3 months. Mineral loss differences were assessed using transversal microradiography. No significant mineral gain occurred at 0 kPa and in samples exposed to water. At 1.47 and 2.94 kPa, pulpal and remineralisation fluid induced significant mineral gain [x0394;x0394;Z = 1,317 (25th/75th percentiles: 735/1,541) vol% × µm; p < 0.001]. Pressure and fluid composition determined pulpal remineralisation in vitro.