PURPOSE:The purpose of this in vitro study was to assess the effects of occlusal thickness and thermomechanical aging on the fracture load of additively manufactured (AM) definitive crowns made from resins with different compositions, compared with crowns subtractively manufactured (SM) from a polymer-infiltrated ceramic network. MATERIALS AND METHODS:Crowns were designed using scans of three mandibular first molar typodonts prepared with occlusal reductions of 1, 1.5, or 2 mm. These designs were used to fabricate crowns either additively (FREEPRINT Crown [AM-FC], Rodin Sculpture [AM-RS], and Rodin Sculpture 2.0 [AM-RS2]) or subtractively (Enamic [SM-VE]) (N = 14). The same typodont scans were used to additively manufacture resin abutments, and each crown was cemented onto its corresponding abutment using a dual-polymerizing resin cement. After cementation, crowns were randomly assigned to nonaged or aged groups (n = 7). Crowns in the aged groups were subjected to thermomechanical aging before load-to-fracture testing, whereas crowns in the nonaged groups were tested without having been aged. Fracture load data were analyzed with a generalized linear model and Bonferroni-corrected post hoc tests (α = 0.05). RESULTS:All crowns survived thermomechanical aging. Fracture load values were significantly affected by material type, occlusal thickness, and aging, as well as by the two-way interactions involving aging (p ≤ 0.003). SM-VE crowns showed the lowest loads, regardless of the aging condition within each thickness (p ≤ 0.024). While aging did not reduce the fracture load of subtractively manufactured crowns, it reduced the fracture load of additively manufactured crowns and across all occlusal thicknesses (p < 0.001). Among all nonaged crowns, 2-mm crowns had the highest fracture load, whereas in the aged groups, 1.5-mm crowns demonstrated the lowest fracture loads (p < 0.001). CONCLUSIONS:Additively manufactured crowns exhibited higher fracture load than subtractively manufactured crowns made of polymer-infiltrated ceramic network despite their reduced strength following thermomechanical aging. The influence of occlusal thickness on fracture load depended on the aging condition, with all additively manufactured crowns showing a reduction in strength after aging.

Statement of problem Whether the manufacturing protocol (build orientation and sintering schedule) of additively manufactured (AM) zirconia impacts the bond strength compared with subtractively manufactured (SM) zirconia remains unclear. Purpose The purpose of this in vitro study was to evaluate the effect of build orientation (45 degrees and vertical), sintering schedule (1-step and 2-step), and resin cement on the shear bond strength (SBS) and failure mode of AM zirconia bonded to dentin compared with that of SM zirconia. Material and methods One hundred fifty 3Y-TZP zirconia cylinders (Ø2×4 mm) were produced by AM (INNI Cera BCM-W1000) or SM (IPS e.max ZirCAD MT). AM specimens were printed vertically at 90 degrees or at 45 degrees and subjected to 1-step or 2-step sintering; SM specimens were milled and sintered. The specimens were divided into 3 subgroups to be luted to human dentin (n=10) with 3 dual-polymerizing resin cements (SpeedCEM Plus; Ivoclar AG, RelyX Ultimate; 3M Dental, Panavia V5; Kuraray Noritake Dental). Dentin and zirconia surfaces were pretreated per cement and manufacturer protocols. After 24 hours, SBS was measured, and failure modes evaluated. The data were analyzed using 2-way ANOVA to assess the effects of manufacturing technique (AM or SM) and resin cement and using 3-way ANOVA exclusively within the AM group to evaluate the effects of build orientation, sintering schedule, and resin cement, followed by Tukey post hoc tests (α=.05). Results According to the 2-way ANOVA, zirconia manufacturing technique (AM or SM) did not significantly influence SBS, whereas resin cement had a significant effect (P<.001). Within the AM groups, the 3-way ANOVA revealed that resin cement was also the only factor significantly affecting SBS (P<.001), with no significant effects of build orientation or sintering schedule (P>.05). SpeedCEM Plus (8.9 ±3.7 MPa) showed the significantly lowest SBS and RelyX Ultimate (15.1 ±5.3 MPa), and Panavia V5 (15.7 ±4.9 MPa) yielded similar SBS. No significant difference was found in failure mode between AM and SM zirconia (P=.647), but differences existed between cements (P<.001). Almost all failures (98%) in SpeedCEM Plus groups were adhesive at the dentin-cement interface. The RelyX Ultimate and Panavia V5 groups had approximately 20% adhesive and approximately 50% cohesive failures within dentin. Conclusions No significant differences in SBS or failure mode were found between AM and SM zirconia. Build orientation and sintering schedule of AM zirconia had no influence on the bond strength of zirconia to dentin, whereas resin cement had a significant effect. In general, SpeedCEM Plus resulted in the significantly lower bond strength of AM and SM zirconia to dentin than did RelyX Ultimate or Panavia V5.

STATEMENT OF PROBLEM:Although minimally invasive repair of existing resin-based restorations is clinically advantageous, the effects of different surface pretreatments on additively and subtractively manufactured resins remain insufficiently studied. This lack of evidence hinders the development of a standardized and reliable protocol for the repair of such materials. PURPOSE:This in vitro study aimed to evaluate the impact of different mechanical and chemical surface pretreatments (airborne-particle abrasion, grinding, universal adhesive application, or no treatment) on the shear bond strength (SBS) of composite resin repairs on hydrothermally aged resin-based materials, used either additively or subtractively for definitive fixed dental prostheses. MATERIAL AND METHODS:A total of 240 resin disks (Ø10×2 mm) were fabricated using 3 additive manufacturing resins (C&B Permanent; Tera Harz TC-80DP; and Crowntec); and 1 subtractive manufacturing resin (Brillant Crios) (n=60 each). All specimens underwent hydrothermal aging through 5000 thermal cycles between 5 °C and 55 °C. Disks were randomly assigned into 3 mechanical pretreatment groups: airborne-particle abrasion with 50 µm Al₂O₃ particles, grinding with a diamond rotary instrument, or no treatment (control) (n=20 each). Each group was then randomly divided into 2 chemical surface pretreatment subgroups: application of a universal adhesive (Clearfil Universal Bond Quick) or no treatment (control) (n=10 each) and then composite resin (Clearfil Majesty ES-2 Classic) was bonded in the center of the surface-treated area. SBS was assessed using a universal testing machine at a crosshead speed of 1 mm/minute. Failure modes were analyzed under a microscope at ×12.5 magnification. Statistical analysis included a 3-way ANOVA and chi-squared test to evaluate the effects of material, mechanical pretreatment, and adhesive on SBS (α=.05). RESULTS:The application of an adhesive substantially increased the SBS (Mean difference (MD): 6.91 ±3.30 MPa; P<.001). When adhesive was used, no differences were observed between resin materials or mechanical surface pretreatments (airborne-particle abrasion or grinding) in either SBS or failure mode (chi-squared test). In contrast, in the absence of adhesive, significant differences were found between materials (P<.001) and mechanical pretreatment (P=.001) for both outcomes. CONCLUSIONS:Repair bond strength depended on the application of an adhesive. When applied, the impact of resin material and mechanical pretreatment remained minimal.

PURPOSE:To modify phosphoric acid (PA) with polyphenol-rich plant extracts and verify their effect on immediate (24 h) and long-term (1 year) micro-shear bond strength (µSBS) of an adhesive system to sound and eroded dentin. MATERIALS AND METHODS:420 dentin specimens (360 for µSBS and 60 for characterization) were prepared and divided into two substrate-subgroups: sound (untreated) and eroded dentin (underwent 10 cycles of 1 h exposure to human saliva and 5 min immersion in citric acid). The specimens from each subgroup were randomly distributed into six groups, according to PA (n = 30/group): PA-EXP (experimental control), PA-GSE (PA-EXP + grape seed extract), PA-BLU (PA-EXP + blueberry extract), PA-CRA (PA-EXP + cranberry extract), PA-GRE (PA-EXP + green tea extract), PA-COM (commercial control). After etching with the respective PA (15 s), specimens were restored with adhesive and composite resin. Half of the specimens of each group were subjected to µSBS testing after 24 h and the other half after 1 year of storage (tap water, 37°C). Analyses were made with three-way ANOVA and post-hoc Tukey tests (α = 0.05). RESULTS:Higher µSBS was observed to sound dentin than to eroded dentin, regardless of the storage time, except for PA-BLU and PA-GSE after 1 year (p = 0.40 and p = 0.10, respectively). After 24 h, for both substrates, PA-COM presented statistically significantly lower µSBS than the other PAs. After 1 year, µSBS was significantly reduced for all groups except for the PA-COM (sound: p = 0.67; eroded: p = 0.13). CONCLUSION:Compared to the commercial PA, the modified PAs improved the immediate µSBS and gave similar long-term µSBS to sound as well to eroded dentin.

ObjectiveTo evaluate how restorative material, resin cement, and cyclic loading affect the fracture resistance of resin-based crowns fabricated by using additive or subtractive manufacturing.MethodsA right first molar crown standard tessellation language (STL) file was used to fabricate 120 crowns from one subtractively manufactured polymer-infiltrated ceramic network (SM) and two additively manufactured resin composites (AM-B and AM-S) (N = 40). These crowns were randomly divided into 4 groups within each material according to the dual-polymerizing resin cement to be used (RX and PN) and the aging condition (n = 10). After cementation, the crowns without cyclic loading were subjected to fracture testing, while the others were first cyclically loaded (1.7 Hz, 1.2 million cycles, and 49-N load) and then subjected to fracture testing. Data were analyzed with generalized linear model analysis (α = .05).ResultsFracture resistance of the crowns was affected by material, resin cement, and cyclic loading (P ≤ .030). However, none of the interactions significantly affected fracture resistance of tested crowns (P ≥ .140). Among tested materials, SM had the highest fracture resistance, whereas AM-B had the lowest (P ≤ .025). RX led to higher fracture resistance, and cyclic loading decreased the fracture resistance (P ≤ .026).SignificanceTested materials can be considered reliable in terms of fracture resistance in short- or mid-term (5 years of intraoral simulation) when used for single molar crowns with 2 mm occlusal thickness. In the long term, polymer-infiltrated ceramic network crowns cemented with RelyX Universal may provide promising results and be less prone to complications considering higher fracture resistance values obtained.

OBJECTIVES:To assess the degree of tooth wear in children and adolescents by application of a qualitative wear index and by quantitative measurement on digital models. The hypothesis was that the quantitative method would be sensitive to reliably measure tooth wear. METHODS:Existing digital models (n = 24) gathered from a prospective clinical study were analysed. The models were obtained at two time points (11-17 months apart) from a cohort of young individuals (11-16 years old) with permanent dentition. Dental wear was scored per sextant on the models according to the qualitative criteria by two examiners and was then quantified on reference teeth (central incisors, canines and first molars). Data were analysed using Cohen's kappa coefficient, Kruskal-Wallis tests followed by Mann-Whitney U, and correlation tests, all with a significance level of 0.05. RESULTS:According to the qualitative assessment, all subjects showed signs of tooth wear and the severity of scores was higher in the anterior dentition (P ≤ 0.003). Inter-examiner reliability was 0.652 (P < 0.001) while intra-examiner reliability was 0.618 and 0.571 (P < 0.001), respectively. The quantitative analysis showed median tooth wear of 0.09 mm (range: 0 - 0.56 mm). There was no significant correlation between the quantitative measurements of tooth wear and age, sex assigned at birth, time span between scans, or sum of index scores. CONCLUSIONS:The quantitative method was sufficiently sensitive to reliably measure tooth wear on digital models in ≥ 92 % of the investigated teeth. The use of the qualitative wear index on digital models proved dubious due to moderate intra- and inter-reliability ratings. CLINICAL SIGNIFICANCE:Our results show increased prevalence and severity of tooth wear in children and adolescents, which raise concern about the current lifestyle habits in our society. Intraoral scanning can be used to quantify tooth wear at an early stage and thus help design individual strategies to prevent further tooth loss.

ObjectivesDue to innumerable confounding factors and a high number of types and brands of dental restorative materials, the clinical performance of restorative materials are sought predicted by various in vitro tests. However, only few such tests have been found to correlate well with clinical findings. Thus, the present study determined the in vitro dentin bond strength and marginal adaptation of Class II restorations and correlated the results to their clinical outcomes.MethodsDentin bond strength (µTBS and µSBS) and marginal gap formation of Class II restorations (replica technique and SEM) were measured after 24 h and 6 m water storage using eight combinations of adhesive and resin composite. Clinical outcomes (mean survival time, Hazard Ratio, annual failure rate; n = 10.695) were gained from a data set of a retrospective multicenter study of direct restorations.ResultsSignificant differences were found for dentin bond strength and marginal gap formation between the restorative material groups, and negative effects of long-term storage were observed. µTBS correlated significantly with certain clinical outcomes of Class I restorations, while µSBS correlated with certain clinical outcomes of Class II, III, IV and V restorations. Marginal gap formation in enamel and number of paramarginal fractures correlated with certain clinical outcomes of Class II restorations.SignificanceUsing the same restorative materials in vitro as in vivo, gave significant, but weak correlations between in vitro bond strength or marginal adaptation and clinical outcomes, lending support to the use of in vitro tests in early stages of material selection.

PURPOSE:To assess the manufacturing accuracy, intaglio surface adaptation, and survival of resin-based CAD/CAM definitive crowns created via additive manufacturing (AM) or subtractive manufacturing (SM).MATERIALS AND METHODS:A maxillary right first molar crown was digitally designed and manufactured using AM hybrid resin composite (VarseoSmile Crown Plus, Bego [AM-HRC]), AM glass filler-reinforced resin composite (Crowntec, Saremco Dental [AM-RC]), and SM polymer-infiltrated ceramic (Vita Enamic, VITA Zahnfabrik [SM-PICN]). Manufacturing accuracy (trueness and precision) was assessed by computing the root mean square (RMS) error (in μm; n = 15 per material). Intaglio surface adaptation was assessed by calculating the average gap distance (μm). Ten crowns from each group were cemented on fiberglass-reinforced epoxy resin dies and cyclically loaded to simulate 5 years of functional loading. One-way ANOVA, post hoc Bonferroni comparison tests, and Levene's test were used to analyze the data (α = .05).RESULTS:AM-RC had higher overall trueness than AM-HRC and SM-PICN (P ≤ .05), whereas the trueness of AM-RC on the external surface was similar to that of SM-PICN (P = .99) and higher than AM-HRC (P = .001). SM-PICN had lower precision than AM-RC and AM-HRC overall and at internal occlusal surfaces (P ≤ .05). Overall intaglio surface adaptation was similar between all groups (P = .531). However, for the axial intaglio surface, AM-RC and AM-HRC had higher adaptation than SM-PICN (P ≤ .05). All tested crowns survived the cyclic loading simulation of 5 years clinical use.CONCLUSIONS:AM-RC showed high manufacturing accuracy and adaptation. The tested resin-based CAD/CAM materials demonstrated clinically acceptable manufacturing accuracy and simulated medium-term durability, justifying the initiation of clinical investigations to determine their potential implementation in daily clinical practice.

PURPOSE To evaluate the effect of polishing and denture cleansers on the surface roughness (Ra ) of new-generation denture base materials that are additively, subtractively, and conventionally fabricated, while also assessing their color change after cleansing. MATERIAL AND METHODS One hundred and fifty disk-shaped specimens (AE10×2 mm) were prepared from five denture base materials (one subtractively manufactured nanographene-reinforced prepolymerized polymethylmethacrylate (PMMA) (SM-GC), one subtractively manufactured prepolymerized PMMA (SM-PM), two additively manufactured denture base resins (AM-DT and AM-ND), and one heat-polymerized PMMA (CV) (n = 30). The Ra of the specimens was measured before and after conventional laboratory polishing, while color coordinates were measured after polishing. Specimens were then divided into three subgroups based on the denture cleanser: distilled water, 1% sodium hypochlorite (NaOCl), and effervescent tablet (n = 10). The Ra and color coordinates were remeasured after nine cleaning cycles over a period of 20 days. The CIEDE200 formula was used to calculate the color differences (ΔE00 ). Two-way analysis of variance (ANOVA) was used to analyze the Ra values before (n = 30) and after (n = 10) cleansing, while repeated measures ANOVA was used to analyze the Ra of material-time point pairs within each denture cleanser (n = 10). ΔE00 data after denture cleansing was also analyzed by using two-way ANOVA (n = 10) (α = .05). RESULTS Before polishing, Ra varied significantly among the materials. SM-GC and SM-PM had the lowest and AM-ND the highest Ra values (P<.001). Polishing significantly reduced Ra of all materials (P<.001), and after polishing, Ra differences among materials were nonsignificant (P≥.072). Regardless of the denture cleanser, the Ra of AM-DT, AM-ND, and CV was the highest before polishing when different time points were considered (P<.001). After cleansing, AM-ND had the highest Ra of all the materials, regardless of the cleanser (P≤.017). AM-DT had higher Ra than SM-PM when distilled water (P = .040) and higher Ra than SM-GC, SM-PM, and CV when NaOCl was used (P<.001). The type of cleanser significantly influenced the Ra of AM-DT, AM-ND, and CV. For AM-DT, NaOCl led to the highest Ra and the tablet led to the lowest Ra (P≤.042), while for AM-ND, distilled water led to the lowest Ra (P≤.024). For CV, the tablet led to lower Ra than distilled water (P = .009). Color change varied among the materials. When distilled water was used, SM-GC had higher ΔE00 than SM-PM and AM-DT (P≤.034). When NaOCl was used, AM-ND had higher ΔE00 than SM-GC, SM-PM, and AM-DT, while CV and SM-GC had higher ΔE00 than SM-PM and AM-DT (P≤.039). Finally, when the tablet was used, AM-ND and CV had the highest ΔE00 , while AM-DT had lower ΔE00 than SM-GC (P≤.015). CONCLUSIONS The tested materials had unacceptable surface roughness (>0.2 μm) before polishing. Roughness decreased significantly after polishing (<0.2 μm). Denture cleansers did not significantly affect the surface roughness of the materials, and roughness remained clinically acceptable after cleansing (<0.2 μm). Considering previously reported color thresholds, AM-ND and CV had unacceptable color change regardless of the denture cleanser, and the effervescent tablet led to perceptible, but acceptable color change for SM-GC, SM-PM, and AM-DT. This article is protected by copyright. All rights reserved.

The aim of this study was to compare the assessment of tooth wear performed on digital models with the one conducted at the clinical examination. Seventy-eight volunteers (29 males and 49 females, age range 20–30 years) with at least 24 teeth, normal oral function, and a neutral transverse relationship were examined. During the clinical examination, dental wear was registered according to the Basic Erosive Wear Examination (BEWE) index. Subsequently, the BEWE index was blindly applied by two examiners on digital models obtained from the volunteers. Data were analyzed using weighted Cohen’s kappa coefficient and correlation tests with a confidence interval of 95%. All volunteers showed signs of tooth wear. Anterior teeth showed increased severity of tooth wear than first molars. Early loss of tooth substance could be identified on the digital models, including in areas with challenging direct intraoral visual access. Approximately 50% of the scores based on clinical examination agreed with those based on examination of digital models (k = 0.543, p < 0.01). A moderate, positive correlation was observed between scores registered clinically and on digital models (Spearman's rho = 0.560, p < 0.001). Considering the rather low agreement between the clinical and digital scores, alternatives to using BEWE on digital models are needed.

Statement of problem. Additively manufactured composite resins for definitive restorations have been recently introduced. The bond strength between these composite resins and different substrates has not been extensively studied. Purpose. The purpose of this in vitro study was to measure the shear bond strength (SBS) between additively manufactured composite resins and dentin and titanium substrates and compare those with the SBS between subtractively manufactured polymer-infiltrated ceramic and the same substrates (dentin and titanium), when different dual-polymerizing resin cements were used. Material and methods. One hundred and eighty cylinder-shaped specimens (& Oslash;5x5 mm) were prepared from 3 materials recommended for definitive restorations: an additively manufactured composite resin (Crowntec [CT]); an additively manufactured hybrid composite resin (VarseoSmile Crown Plus [VS]); and a subtractively manufactured polymer-infiltrated ceramic (Enamic [EN]) (n=60). Specimens were randomly divided into six subgroups to be cemented to the two substrates (dentin and titanium; n=30) with 1 of 3 resin cements (RelyX Universal, Panavia V5, and Variolink Esthetic DC) (n=10). The restoration surface to be bonded was treated according to the respective manufacturer's recommendations. Dentin surfaces were treated according to the resin cement (Scotchbond Universal Plus Adhesive for RelyX Universal, Panavia V5 Tooth Primer for Panavia V5, and Adhese Universal for Variolink Esthetic DC), while titanium surfaces were airborne-particle abraded, and only the specimens paired with Panavia V5 were treated with a ceramic primer (Clearfil Ceramic Primer Plus). SBS was measured in a universal testing machine at a crosshead speed of 1 mm/min. Failure modes were analyzed under a microscope at x12 magnification. Data were analyzed by using 2-way analysis of variance and Tukey honestly significant difference tests (a=.05). Results. When SBS to dentin was considered, only restorative material, as a main factor, had a significant effect (P<.001); EN had the highest SBS (P<.001), while the difference in SBS values of CT and VS was not significant (P=.145). As for SBS to titanium, the factors restorative material and resin cement and their interaction had a significant effect (P<.001). Within each resin cement, EN had the highest SBS to titanium (P<.001), and within each restorative material, Variolink resulted in the lowest SBS (P<.010). Overall, EN and RelyX were associated with the highest SBS to titanium (P<.013). Mixed failures were predominant in most groups. Conclusions. Regardless of the substrate or the resin cement used, the subtractively manufactured polymer-infiltrated ceramic had higher shear bond strength than the additively manufactured composite resins. The SBS of the additively manufactured composite resins, whether bonded to dentin or titanium, were not significantly different from each other. Regardless of the restorative material, Variolink DC resulted in the lowest SBS for titanium surfaces. (J Prosthet Dent 2024;132:1067.e1-e8)

Hovedbudskap Multimodale bindingssystemer giver tandlægen mulighed for at vælge den bindingsstrategi, der er bedst egnet til en given klinisk opgave. Evidensen understøtter anvendelse af multimodale bindingssystemer kombineret med selektiv emaljeætsning. En ultrakort dentinætsning i 3 sek. kombineret med 15 sek. emaljeætsning ser også lovende ud.

Objectives: To investigate the impact of adhesive application errors on dentin bond strength of resin composite.Material and Methods: 165 extracted permanent human molars were ground to mid-coronal dentin. The dentin specimens were treated with one of three adhesive systems (OptiBond FL, Clearfil SE, Scotchbond Universal) either according to manufacturer’s instructions or with systematic errors in the application procedure and before application of resin composite (Filtek Z250). After storage (37 °C, 100% humidity, 24 h) shear bond strength (SBS) was measured and data analysed with either one-way ANOVA followed by Tukey tests (OptiBond FL, Scotchbond Universal, control groups) or Kruskal-Wallis followed by Wilcoxon tests (Clearfil SE). Finally, the failure mode of all specimens was assessed.Results: With OptiBond FL and Clearfil SE omitted application (p ≤ 0.0001) as well as no evaporation (p ≤ 0.001) of the solvents in the primer significantly reduced the SBS. Omitted application of the adhesive, respectively the bond, had a negative influence on the SBS of Clearfil SE (p < 0.0001), but not of OptiBond FL (p = 0.776). With Scotchbond Universal, no evaporation of the solvents (p < 0.0001) as well as no light-cure (p = 0.0004) had a significant negative influence on the SBS. Using the adhesive systems according to manufacturer’s instructions, Clearfil SE achieved significantly lower SBS than OptiBond FL and Scotchbond Universal (p = 0.0027). Adhesive failure at the dentin surface was generally the most frequent failure mode observed.Conclusion: All three adhesive systems tested were sensitive to application errors. For optimal result and longest possible durability of resin restorations, clinicians should strictly adhere to the manufacturer’s instructions.

This article refers to:Effect of cementation techniques on fracture load of monolithic zirconia crowns

HovedbudskapForståelse for retentionscementernes sammensætning og egenskaber er afgørende for valget af den bedst egnede cement i enhver given klinisk situation.Plastcementer kan anvendes til alle restaureringstyper, men bør anvendes til cementering af lavstyrke keramiskrestaureringer, under forudsætning af tilstrækkelig tørlægning.Glasionomercementer er et godt alternativ til cementering ved utilstrækkelig tørlægning, dog ikke egnet til lavstyrke keramiske restaureringer samt ej-retentive restaureringer.Zinkfosfatcement må gerne anvendes til cementering af metalliske restaureringer, især ved subgingivale præparationer.

Abstract Objectives: Adhesion and marginal adaptation of a claimed bioactive restorative material (ACTIVA BioACTIVE Restorative) to human teeth were compared with those of a resin-modified glass ionomer cement (Fuji II LC) and a control resin composite (Ceram X Mono). Material and Methods: Shear bond strength and marginal adaptation to enamel and dentine were assessed after no pretreatment of the hard tissues or after etching with phosphoric acid (ACTIVA BioACTIVE Restorative and Ceram X Mono) or polyacrylic acid (Fuji II LC). For ACTIVA BioACTIVE Restorative, the effect of applying a self-etch adhesive (Xeno Select, Dentsply Sirona) was also investigated. Data were analyzed using non-parametric tests (α = 0.05). Results: Bond strength and marginal adaptation in enamel and dentine were significantly different among the investigated materials (p<.05). Due to loss of restorations, it was not possible to measure bond strength of ACTIVA BioACTIVE Restorative if no pretreatment was performed or if dentine was etched; however, use of the self-etch adhesive resulted in similar bond strength as Ceram X Mono. Etching improved adhesion of Fuji II LC to enamel and dentine. Regarding marginal adaptation, ACTIVA BioACTIVE Restorative showed the highest wall-to-wall contraction to enamel in all pretreatment groups and the overall highest wall-to-wall contraction to dentine after etching. Due to loss of restorations, no marginal assessment was possible on cavities with margins in dentine when no pretreatment was used. The use of a self-etch adhesive with ACTIVA BioACTIVE Restorative resulted in similar adaptation to dentine compared to the other materials. Conclusion: The self-adhesive property of ACTIVA BioACTIVE Restorative is nonexistent.

Purpose: To investigate the repair bond strength (RBS) of a resin composite to six restorative materials either mediated by application of a silane and a bonding agent or by application of a universal adhesive. Methods and Materials: Thirty specimens were produced from each restorative material: an amalgam alloy (ORALLOY MAGICAP S), a direct resin composite (Filtek Z250), two indirect resin composites (Paradigm MZ100 and Lava Ultimate), a hybrid ceramic (VITA ENAMIC), and a feldspar ceramic (VITABLOCS Mark II). The specimens were stored for 3 months in tap water (37°C) for artificial ageing. After storage, the surfaces of all specimens were sandblasted (aluminum oxide, grain size: 25 μm), water-sprayed, and air-dried. Subsequently, the surfaces of half of the specimens (n=15/restorative material) were treated with a silane (Monobond Plus) followed by application of a bonding agent (OptiBond FL Adhesive) whereas the other half was treated with a universal adhesive only (Scotchbond Universal). A resin composite (Filtek Z250) was applied as repair material on the treated surfaces and the specimens were stored for 24 hours (37°C, 100% humidity). Then, RBS was measured by means of a shear bond strength test. Due to normally distributed data (Shapiro Wilk’s test: p=0.216), RBS-values were analyzed with a parametric ANOVA and two-sample t-tests. The p-values were corrected with Bonferroni-Holm adjustment for multiple testing (significance level: α=0.05). Results: Mean values (standard deviations) (MPa; Monobond Plus and OptiBond FL Adhesive / Scotchbond Universal) were: 18.6 (3.2) / 17.2 (3.1) for ORALLOY MAGICAP S, 19.8 (3.9) / 17.0 (3.5) for Filtek Z250, 19.9 (3.2) / 17.6 (3.7) for Paradigm MZ100, 20.5 (4.2) / 18.1 (4.6) for Lava Ultimate, 23.9 (5.0) / 17.1 (3.2) for VITA ENAMIC, and 22.3 (4.3) / 12.5 (4.9) for VITABLOCS Mark II. For VITA ENAMIC and VITABLOCS Mark II, treatment with Monobond Plus and OptiBond FL Adhesive showed a significantly higher RBS than did treatment with Scotchbond Universal (p≤0.0009). For the other four restorative materials, RBS did not significantly differ between the two treatments (p≥0.207). Conclusion: Clinically (with the exception of amalgam alloy), the material of a restoration to be repaired may be unknown. Consequently, when repairing restorations with resin composite it seems advisable to use a silane followed by a bonding agent since for two out of the six restorative materials investigated, the use of a universal adhesive showed lower repair bond strength.