Biomimetic Remineralization of Artificial Caries Lesions with a Calcium Coacervate, Its Components and Self-Assembling Peptide P11-4 In Vitro.

The application of calcium coacervates (CCs) may hold promise for dental hard tissue remineralization. The aim of this study was to evaluate the effect of the infiltration of artificial enamel lesions with a CC and its single components including polyacrylic acid (PAA) compared to that of the self-assembling peptide P11-4 in a pH-cycling (pHC) model. Enamel specimens were prepared from bovine incisors, partly varnished, and stored in demineralizing solution (DS; pH 4.95; 17 d) to create two enamel lesions per sample. The specimens were randomly allocated to six groups (n = 15). While one lesion per specimen served as the no-treatment control (NTC), another lesion (treatment, T) was etched (H3PO4, 5 s), air-dried and subsequently infiltrated for 10 min with either a CC (10 mg/mL PAA, 50 mM CaCl2 (Ca) and 1 M K2HPO4 (PO4)) (groups CC and CC + DS) or its components PAA, Ca or PO4. As a commercial control, the self-assembling peptide P11-4 (CurodontTM Repair, Credentis, Switzerland) was tested. The specimens were cut perpendicularly to the lesions, with half serving as the baseline (BL) while the other half was exposed to either a demineralization solution for 20 d (pH 4.95; group CC + DS) or pHC for 28 d (pH 4.95, 3 h; pH 7, 21 h; all five of the other groups). The difference in integrated mineral loss between the lesions at BL and after the DS or pHC, respectively, was analyzed using transversal microradiography (ΔΔZ = ΔZpHC - ΔZbaseline). Compared to the NTC, the mineral gain in the T group was significantly higher in the CC + DS, CC and PAA (p < 0.05, Wilcoxon). In all of the other groups, no significant differences between treated and untreated lesions were detected (p > 0.05). Infiltration with the CC and PAA resulted in a consistent mineral gain throughout the lesion body. The CC as well as its component PAA alone promoted the remineralization of artificial caries lesions in the tested pHC model. Infiltration with PAA further resulted in mineral gain in deeper areas of the lesion body.

Effects of Ion-Releasing Materials on Dentine: Analysis of Microhardness, Appearance, and Chemical Composition.

The aim of this study was to compare the potential of standard ion-releasing materials to repair demineralized lesions with recently introduced alkasite and glass hybrid materials. Glass ionomer (GC Fuji TRIAGE), two glass hybrids (EQUIA Forte HT, Riva SC), calcium silicate cement (Biodentine) and an alkasite (Cention Forte) were tested. A total of 72 human third molars were used for sample preparation; on the dentine surface, a class-I cavity was prepared, and one half was covered with nail varnish. The teeth were subjected to a demineralization protocol, filled with the examined materials, and cut in half. The evaluation included a dentine microhardness assessment (n = 10) and SEM/EDS analysis (n = 2). The results were analyzed using SPSS 22.0 statistical software and compared using an analysis of variance and Scheffe post-hoc test. The statistical significance level was set to 0.05. Mean microhardness values (HV0.1) after 14 and 28 days were, respectively: EQUIA Forte HT (26.7 ± 1.45 and 37.74 ± 1.56), Riva Self Cure (19.66 ± 1.02 and 29.58 ± 1.18), Cention Forte (19.01 ± 1.24 and 27.93 ± 1.33), Biodentine (23.35 ± 1.23 and 29.92 ± 1.02), GC Fuji TRIAGE (25.94 ± 1.35 and 33.87 ± 5.57) and control group (15.57 ± 0.68 and 15.64 ± 0.82). The results were significantly different between most groups (p < 0.001). SEM/EDS revealed varying patterns, material deposits and distinct elemental variations. To conclude, all materials increased microhardness and affected the dentine surface appearance and chemical composition; EQUIA Forte HT demonstrated the most pronounced effects.

Accuracy of different approaches for detecting proximal root caries lesions in vitro.

OBJECTIVES: The objective was to evaluate the diagnostic accuracy of radiographic evaluation (XR), visual-tactile assessment (VT), laser-fluorescence (LF) (DIAGNOdent Pen/KaVo), and near-infrared-light transillumination (NILT) (DIAGNOcam/KaVo) on proximal root caries lesions in vitro. METHODS: Two-hundred extracted permanent premolars and molars with and without proximal root caries lesions were allocated to 50 diagnostic models simulating the proximal contacts between teeth and mounted in a phantom dummy head. Two independent examiners used the diagnostic approaches to detect any or advanced root caries lesions, with histologic evaluation of the lesions serving as reference. Receiver operating characteristic (ROC) curves were employed, and sensitivity, specificity, and the area under the ROC curve (AUC) are calculated. Significant differences in mean AUCs between approaches were assumed if p < 0.05 (two-sample t-test). RESULTS: NILT was not applicable for proximal root caries detection. The sensitivity/specificity to detect any lesions was 0.81/0.63 for XR, 0.76/0.88 for VT and 0.81/0.95 for LF, and the sensitivity/specificity to detect advanced lesions was 0.43/0.94 for XR, 0.66/0.99 for VT, and 0.83/0.78 for LF, respectively. For both, any and advanced root caries lesions, mean AUCs for LF and VT were significantly higher compared to XR (p < 0.05). For any root caries lesions, LF was significantly more accurate than VT (p = 0.01), but not for advanced root caries lesions (p = 0.59). CONCLUSIONS: Under the in vitro conditions chosen, LF and VT were more accurate than XR to detect proximal root caries lesions, with LF being particularly useful for initial lesion stages. CLINICAL RELEVANCE: LF might be a useful diagnostic aid for proximal root caries diagnosis. Clinical studies are necessary to corroborate the findings.

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.

Detecting white spot lesions on dental photography using deep learning: A pilot study.

OBJECTIVES: We aimed to apply deep learning to detect white spot lesions in dental photographs. METHODS: Using 434 photographic images of 51 patients, a dataset of 2781 cropped tooth segments was generated. Pixelwise annotations of sound enamel as well as fluorotic, carious or other types of hypomineralized lesions were generated by experts and assessed by an independent second reviewer. The union of the reviewed annotations were used to segment the hard tissues (region-of-interest, ROI) of each image. SqueezeNet was employed for modelling. We trained models to detect (1) any white spot lesions, (2) fluorotic lesions and (3) other-than-fluorotic lesions. Modeling was performed on both the cropped and the ROI images and using ten-times repeated five-fold cross-validation. Feature visualization was applied to visualize salient areas. RESULTS: Lesion prevalence was 37 %; the majority of lesions (24 %) were fluorotic. None of the metrics differed significantly between the models trained on cropped and ROI imagery (p > 0.05/t-test). Mean accuracies ranged between 0.81-0.84, without significant differences between models trained to detect any, fluorotic or other-than-fluorotic lesions (p > 0.05). Specificities were 0.85-0.86; sensitivities were lower (0.58-0.66). Models to detect any lesions showed positive/negative predictive values (PPV/NPV) between 0.77-0.80, those to detect fluorotic lesions 0.67 (PPV) to 0.86 (NPV), and those to detect other-than-fluorotic lesions 0.46 (PPV) to 0.93 (NPV). Light reflections were the main reason for false positive detections. CONCLUSIONS: Deep learning showed satisfying accuracy to detect white spot lesions, particularly fluorosis. Some models showed limited stability given the small sample available. CLINICAL SIGNIFICANCE: Deep learning is suitable for automated classification of retro- or prospectively collected imagery and may assist practitioners in discriminating white spot lesions. Future studies should expand the scope into more granular multi-class detections on a larger and more generalizable dataset.

Secondary caries risk of different adhesive strategies and restorative materials in permanent teeth: Systematic review and network meta-analysis.

OBJECTIVES: Secondary caries is a major long-term complication of dental restorations. Different adhesive strategies and restorative materials may affect secondary caries risk. We aimed to systematically review and synthesize the secondary caries risk of different adhesive strategies and restorative materials. SOURCES: Medline via PubMed 01/2005-10/2019. STUDY SELECTION: Randomized controlled studies with minimum 2 years follow-up, comparing different adhesive strategies and/or restorative materials in permanent teeth were included. Our outcome was the occurrence of secondary caries. Bayesian pairwise and network-meta-analysis were conducted. DATA: We included 50 trials; 19 assessing secondary caries depending on different adhesive strategies, 31 on restorative materials. Studies were published between 2005 and 2017, largely of unclear risk of bias, and included a mean of 40 (range: 8-90) participants and 46 (range: 14-200) placed restorations. Mean follow-up was 43 (range: 24-180) months. Secondary caries was a rare event; the majority of studies did not find any lesions. Network meta-analysis found great uncertainty. 3-step etch-and-rinse adhesives showed the lowest risk of secondary caries, 2-step etch-and-rinse the highest. For restorative materials, resin-modified glass ionomer showed the lowest risk of secondary caries. Most resin composites showed similar risks. CONCLUSION: Data from randomized trials comparing different adhesive strategies or restorative materials are extremely scarce. The differences between materials were limited over the observational period of the included studies. The yielded rankings should be interpreted with caution. CLINICAL SIGNIFICANCE: Despite often claimed to be a major complication of restorations, there is surprisingly little data on secondary caries from randomized trials. Longer-term studies may be needed to identify differences in secondary caries risk between materials.

Secondary caries: what is it, and how it can be controlled, detected, and managed?

OBJECTIVES: To assess how to control, detect, and treat secondary caries. This review serves to inform a joint ORCA/EFCD consensus process. METHODS: Systematic and non-systematic reviews were performed or consulted and narratively synthesized. RESULTS: Secondary (or recurrent) caries is defined as a lesion associated with restorations or sealants. While the restorative material itself has some influence on secondary caries, further factors like the presence and size of restoration gaps, patients' caries risk, and the placing dentist's experience seem more relevant. Current detection methods for secondary caries are only sparsely validated and likely prone for the risk of over-detection. In many patients, it might be prudent to prioritize specific detection methods to avoid invasive overtreatment. Detected secondary caries can be managed either by repair of the defective part of the restoration or its complete replacement. CONCLUSIONS: There is sparse data towards the nature of secondary caries and how to control, detect, and treat it. CLINICAL SIGNIFICANCE: Despite often claimed to be a major complication of restorations, there is surprisingly little data on secondary caries. Longer-term studies may be needed to identify differences in secondary caries risk between materials and to identify characteristic features of progressive lesions (i.e., those in need of treatment).

Restoration integrity, but not material or cementation strategy determined secondary caries lesions next to indirect restorations in vitro.

OBJECTIVE: Secondary caries lesions next to direct restorations are associated with the restoration material and the integrity of the tooth-restoration-interface (presence of interfacial gaps) as well as the application of masticatory forces. It remains unclear if this is true for indirect restorations. We aimed to evaluate secondary lesions next to conventionally-cemented partial gold (PG) and adhesively-cemented partial ceramic (PC) restorations, placed with or without interfacial gaps. METHODS: In human molars, standardized two-surfaced cavities were prepared. Four groups (restoration material+cementation strategy) were compared: (1) gold+glass ionomer cement (Degudent/Ketac Cem), (2) lithium disilicate ceramic+self-adhesive resin cement (IPS e.max Press/RelyX Unicem 2), (3) lithium disilicate ceramic+self-etch adhesive+resin cement (IPS e.max Press/Adhese Universal/Variolink Esthetic DC), (4) lithium disilicate ceramic+etch-and-rinse adhesive+resin cement (IPS e.max Press/Syntac/Variolink Esthetic DC). Half of the restorations received a simulated interfacial gap (mean gap height was 237µm), while the other half did not (n=12/group). Specimens were submitted to a Lactobacillus rhamnosus-monospecies-biofilm-model with concomitant cyclic loading for 10 days. Mineral loss (ΔZ) of enamel-surface-lesions (ESL) and dentin-wall-lesions (DWL) was analyzed using transversal microradiography. RESULTS: For ESL, neither the presence of an interfacial gap nor the restoration material nor the cementation strategy had a significant influence on ΔZ (p>0.05/Generalized Linear Modelling). For DWL, ΔZ was significantly higher beneath restorations with interfacial gaps (p=0.003/GLM); the restoration material and cementation strategy did not have a significant influence (p>0.05). SIGNIFICANCE: The presence of interfacial gaps, but not the restoration material or cementation strategy determined secondary caries lesions next to indirect restorations in vitro.

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.

Effect of Final Irrigation Protocol and Etching Mode on Bond Strength of a Multimode Adhesive in the Root Canal.

PURPOSE: To analyze the effects of ethanol for final post space irrigation and etching mode on the bond strength of fiber posts luted with a mild multimode adhesive (pH 2.3) as compared with a reference group using a self-adhesive resin cement (SAR). MATERIALS AND METHODS: Human anterior teeth were endodontically treated. After post space preparation, the root canals were irrigated using 1% sodium hypochlorite (NaOCl) applied with passive ultrasonic irrigation, followed by either distilled water (control) or distilled water and ethanol 99% as final post space irrigation. Fiber posts were luted using Futurabond U in self-etch mode (FU-SE), Futurabond U in etch-and-rinse mode (FU-ER), or Futurabond DC (SE) in combination with a dual-curing core buildup material (Grandio Core, all VOCO); alternatively, posts were inserted using a self-adhesive composite cement (RelyX Unicem 2, 3M ESPE). Bond strengths were evaluated using push-out tests following thermocycling (TC) and storage in 0.9% NaCl for 3 months. RESULTS: Mean push-out bond strengths (MPa) were significantly affected by the luting system (p < 0.0005) but not by the irrigation protocol (p = 0.068; ANOVA), although a significant interaction between the factors "luting agent" and "pre-treatment" was observed. FU E&R (21.28 [4.34]) and RX (20.12 [7.32]) revealed significantly higher bond strengths compared to FU SE (15.9 [6.02]), whereas F DC (18.8 [6.9]) did not differ significantly from all other groups. Ethanol pre-treatment increased bond strength in the apical part of the root canal for all materials, with the exception of FU E&R. CONCLUSION: Mild multimode adhesives exhibit comparable mean bond strengths to a SAR cement within the root canal for luting fiber posts if applied in an etch-and-rinse mode. Using this approach, ethanol application has no positive effects on bond strength.

The association between loading of restorations and secondary caries lesions is moderated by the restoration material elasticity.

OBJECTIVES: Secondary caries limits the longevity of restorations and is thought to be associated with faulty restorations, e.g. dentin-restoration interfacial gaps. Recent evidence indicates that loading of restorations might aggravate the effects of gaps on interfacial mineral loss. It is unclear if this effect of loading is dose-dependent or not, and if restoration material properties like elasticity moderate the association between load and mineral loss. We hypothesized that mineral loss of secondary lesions increases with increasing load, and that this association is moderated by the elastic modulus of the placed restoration material. METHODS: Dentin-restoration specimens with simulated interfacial gaps were submitted to cariogenic Lactobacillus-rhamnosus-biofilms for 10days, and concurrently loaded with different loads (0/42/84/126g per specimen, n=12/group). Two different composites (LEC: low elastic-modulus composite, HEC: high elastic-modulus composite) were employed. Transversal microradiography was used to evaluate the superficial and interfacial (wall) lesion mineral loss. Generalized linear modeling (GLM) was used to evaluate the association between loading, material and their interaction on mineral loss. RESULTS: Surface mineral loss was not significantly associated with loading, material, or their interaction (p-values ranged between p=0.062 and 0.526). For deep interfacial (wall) lesions, the applied load (p=0.023) but not the material (p=0.382) showed a significant effect. The interaction between both significantly affected mineral loss (p=0.01). Loads of ≥84g per specimens were associated with higher wall lesion mineral loss. CONCLUSIONS: Loads above a certain threshold significantly increased interfacial (wall) lesion mineral loss. This association was moderated by the elasticity of the placed restoration materials. CLINICAL SIGNIFICANCE: The clinical relevance of our findings remains unclear, as future studies are needed to understand how exactly both load and material elasticity affect secondary lesion induction.

Risk of caries adjacent to different restoration materials: Systematic review of in situ studies.

OBJECTIVES: The risk of 'caries adjacent to restorations' (CAR) might depend on the used restorative materials. In situ studies are often used to compare the risk of caries adjacent to different materials. We aimed to review in situ studies to evaluate how different materials contribute to risk of CAR. DATA SOURCES: We included in situ controlled trials comparing directly placed restorative materials, reporting on caries (mineral loss, measured via radiography or micro-hardness) adjacent to these materials. Medline, Embase and Cochrane CENTRAL were systematically searched. Screening and data extraction was performed independently by two authors. Materials were classified according to the used adhesive and restorative materials. Fixed-effects pairwise and frequentistic network meta-analyses were performed STUDY SELECTION: Nine studies (132 patients, 8 materials) were included, yielding inconsistent results. We could not identify underlying reasons, as confounders were only limitedly reported. The resulting material rankings come with great uncertainty, and raise doubts as to the validity and transferability of in situ studies as well as the applicability of their findings. CONCLUSIONS: The current body of evidence of in situ studies is insufficient for firm conclusions as to the caries risk adjacent to different materials. The validity and applicability of included studies remain uncertain. CLINICAL SIGNIFICANCE: While single in situ studies seem to convey consistent and applicable information, the overall body of evidence is inconsistent, limiting the conclusions which can be drawn from it.

Radiographic, antibacterial and bond-strength effects of radiopaque caries tagging.

Selectively excavated carious lesions remain radiographically detectable. Radiopaque tagging could resolve the resulting diagnostic uncertainty. We aimed to evaluate if tagging depends on lesions depths, is antibacterial, or affects dentin bond-strengths. Artificial lesions (depth-range: 152-682 µm, n = 34/group) were induced in human dentin samples, evaluated using wavelength-independent microradiography, treated with one of two tagging materials (70% SnCl2, 30% SnF2) and re-evaluated. To evaluate antimicrobial effects, 40 dentin samples were submitted to a Lactobacillus rhamnosus invasion-model. Infected samples were treated with placebo, 0.2% chlorhexidine, SnCl2, SnF2 (n = 10/group). Dentin was sampled and colony-forming units/mg determined. Micro-tensile bond-strengths of adhesive restorations (OptiBond FL, Filtek Z250) to tagged or untagged, sound and carious dentin were assessed (n = 12/group). Tagged surfaces were evaluated microscopically and via energy-dispersive X-ray-spectroscopy (EDS). Tagging effects of both materials decreased with increasing lesion depths (p < 0.001). Un-/chlorhexidine-treated dentin contained significantly more viable bacteria (median 7.3/3.7 × 10(5) CFU/mg) than tagged dentin (no CFU detectable, p < 0.001). Tagging decreased bond strengths (p < 0.001) on sound (-22%/-33% for SnCl2/SnF2) and carious dentin (-50%/-54%). This might be due to widespread tin chloride or fluoride precipitation, as detected via microscopy and EDS. While radiopaque tagging seems beneficial, an optimized application protocol needs to be developed prior clinical use.

Penetration of micro-filled infiltrant resins into artificial caries lesions.

OBJECTIVES: Infiltrants are non-filled low-viscosity resins that have been developed to arrest lesion progression by penetrating into the porosities of non-cavitated lesions where they are hardened and arrest lesion progression. The addition of fillers to infiltrant resin might combine the high penetrativity of the former with the better applicability of composite resins. The aim of the present study was to evaluate the penetration of different experimental micro-filled infiltrant resins (MFIRs) into artificial enamel lesions. METHODS: An infiltrant (Icon; DMG) was mixed with either one of three fillers [OF83: organic filler (83µm), OF42: organic filler (42µm) or GF0.7: glass filler (0.7µm)] reaching 35, 45 and 55% filler content, respectively. In each of 180 bovine enamel specimens three artificial lesions were created; two lesions were etched for 5s (37% H3PO4), leaving one lesion as control. Specimens were randomly allocated to 10 groups, in which either one of the MFIRs or the infiltrant was applied onto the two etched lesions for either 5s or 10s (n=18/group). Percentage of penetration (PP) was calculated and analysed. RESULTS: For both application times a significant influence of filler size but not of filler concentration on PP could be revealed (p<0.05; two-way ANOVA). PP of MFIRs-OF42 was not significantly different from unfilled infiltrant but significantly higher than those of OF83 and GF0.7 (p<0.05; two-way ANOVA). CONCLUSIONS: MFIRs-OF42 showed the ability to penetrate into artificial enamel caries lesions similar to the unfilled infiltrant resin. CLINICAL SIGNIFICANCE: MFIRs could provide a new micro-invasive treatment for small-cavitated lesions.