Does the universal adhesive's film thickness affect dentin-bonding effectiveness?

OBJECTIVES: To investigate the influence of adhesive resin application modalities on the film thickness of the adhesive resin and the effectiveness of a two-step universal adhesive (UA) bonded in self-etch (SE) bonding mode to high C-factor class-I cavity-bottom dentin. MATERIALS AND METHODS: After application of the primer of G2-Bond Universal (G2B, GC), the adhesive resin was applied into standard class-I cavities (human molars) following four application modalities: (1) one layer, strongly air-blown; (2) one layer, gently air-blown; (3) two layers, each gently air-blown; (4) one layer, not air-blown. After being restored with composite, each tooth was sectioned to obtain one micro-specimen (n = 10), of which the adhesive resin film thickness was measured using optical microscopy. The micro-tensile bond strength (µTBS) was tested immediately or upon 100,000 thermocycles. Statistical analyses involved Kruskal-Wallis and Mann-Whitney U testing (p < 0.05). RESULTS: G2B's µTBS was significantly affected by the adhesive resin application modality and aging. Gently air-blowing the adhesive resin resulted in significantly higher immediate µTBS than strong air-blowing or no air-blowing. No significant difference in µTBS was found between single or double gently air-blown adhesive resin applications. The adhesive resin film thickness significantly varied with the application modalities. CONCLUSIONS: A too thin or too thick adhesive resin film thickness adversely affected bond strength of the two-step UA applied in SE mode and high C-factor condition. CLINICAL RELEVANCE: The adhesive resin layer thickness can affect the bonding performance of two-step UAs in high C-factor cavities. Dental clinicians remain advised to avoid improper air-blowing of UAs and strictly follow the application instructions.

Quick bonding using a universal adhesive.

OBJECTIVES: This study aimed to measure the microtensile bond strength (µTBS) of a new universal adhesive (UA) bonded to dentin following a quick bonding mode. MATERIALS AND METHODS: The experimental UA 'SKB-100,' now commercialized as Clearfil Universal Bond Quick ('C-UBq'; Kuraray Noritake), was investigated, with Scotchbond Universal ('SBU'; 3M Oral Care) and the two-step self-etch (SE) adhesive Clearfil SE Bond 2 ('C-SE2'; Kuraray Noritake) serving as references. The adhesives were employed separately in etch&rinse (E&R) and SE modes on each tooth half following a split-tooth design and following their respective instructions for use, except for C-UBq that besides the manufacturer's instructed quick bonding mode was also applied and left untouched for 20 s prior to light curing ('C-UBq_20s') and for C-SE2 that was also applied in the E&R mode. µTBS of half of the specimens was measured upon 1 week (1w), with the other half tested after 6-month (6m) storage in distilled water at 37 °C. Data were statistically analyzed using linear mixed-effects modeling and three-way ANOVA (p < 0.05). The adhesive-dentin interfaces were ultrastructurally characterized by TEM. RESULTS: C-UBq revealed a significantly lower µTBS than C-SE2. The highest µTBS was recorded for C-UBq_20s_1w and C-SE2_1w, both when applied in E&R mode. However, µTBS of C-UBq_20s significantly decreased upon aging in both modes. C-SE2 presented the significantly highest 'aged' µTBS. CONCLUSION: C-UBq applied in the quick bonding mode did not underperform to the UAs applied for 20 s. Superior bonding effectiveness was achieved by C-SE2 in SE and E&R bonding modes. CLINICAL RELEVANCE: Extended application time of C-UBq improved solely its immediate but not aged bonding effectiveness.

Secondary caries: prevalence, characteristics, and approach.

OBJECTIVES: The objectives of this cross-sectional survey were to determine the prevalence of secondary caries (SC) in general population, to identify patient- and material-related factors which may affect the prevalence, and to describe some clinical characteristics of SC lesions. MATERIALS AND METHODS: A total of 4036 restorations in 450 patients, who visited the university dental clinic for a regular (half) yearly checkup, were examined clinically (and radiographically) for the presence of SC. Clinical characteristics of the detected SC lesions (size, activity, and location) and the planned treatment were recorded. In addition, patients' caries-risk status was assessed according to the modified "cariogram" model. RESULTS: In total, 146 restorations were diagnosed with SC, which gives an overall prevalence of 3.6%. Restorative material, restoration class, patient's caries risk, and smoking habits were shown to be important factors, as SC prevalence was significantly higher with composites, class II restorations, high-caries-risk patients, and smokers. Restorations' gingival margins were most frequently affected by SC. The largest number of restorations with SC (72%) was scheduled for the replacement. CONCLUSIONS: Prevalence of SC was higher with composite than with amalgam restorations, irrespective of the patient's caries-risk status. Gingival margins of class II, including MOD restorations, seem to be the place of less resistance to SC development. Management of SC seems to place a considerable burden on the health care workforce and expenditure. CLINICAL RELEVANCE: Secondary caries (SC) is considered to be the main cause of dental restoration failure and one of the biggest clinical challenges related to dental composites. Nevertheless, its prevalence in daily practice is still not clear, which impedes an accurate estimation of its impact on health care costs.

Nonretentive Bonded Ceramic Partial Crowns: Concept and Simplified Protocol for Long-lasting Dental Restorations.

PURPOSE: Adhesively luted partial ceramic crowns have been documented to be clinically more durable than direct composite restorations when minimally invasively restoring large defects (replacing two cusps or more) in posterior teeth. The clinical longevity of such restorations is largely determined by the tooth-preparation design, material selection and adhesive luting procedure. The most frequently recorded failure in medium- to long-term clinical trials is fracture of the restoration. The clinical protocol of adhesively luted partial ceramic crowns can be optimized by taking the etiology of these restoration fractures into account. In this article, a simplified nonretentive bonded ceramic partial crown concept is presented that aims to achieve an adhesively luted ceramic restoration - composite cement - residual tooth structure biomechanical unit that maximally resists functional aging. Therefore, the three primary components of the bonded restoration-cement-tooth complex must function in synergy. Methods, Results and Discussion: The clinical protocol starts with a tooth preparation designed to optimally absorb chewing stress. A stable, internally rounded and gently sloping tooth-preparation design with all outer margins inclined towards the tooth center assures a favorable and homogenous stress distribution with low cyclic fatigue subjected to the adhesive interface. This preparation form additionally enables the dental technician to fabricate a well-seating and -fitting ceramic restoration of uniform thickness. As restoration material, monolithic lithium-disilicate glass ceramic is sufficiently strong for the partial crown indication and preferred in order to decrease the fracture risk. Clinically essential for a long-lasting restoration is the optimal bond that can be obtained by combined micromechanical interlocking and chemical bonding of composite cement to hydrofluoric acid-etched and silanized glass ceramic. CONCLUSION: The clinical effectiveness of this nonretentive bonded ceramic partial crown concept is confirmed by the overall high success rate as well as the very low fracture and debonding rate, as was recorded in long-term clinical trials.

Nine-year Clinical Performance of a HEMA-free One-step Self-etch Adhesive in Noncarious Cervical Lesions.

PURPOSE: One-step self-etch adhesives are among the most popular adhesives to directly bond composite to tooth tissue, mainly because of their perceived ease-of-use. The aim of this randomized controlled trial was to evaluate the clinical performance of a HEMA-free 1-step self-etch adhesive (1SEa), as compared with a 3-step etch-and-rinse adhesive (3E&Ra). MATERIALS AND METHODS: 267 non-carious cervical lesions in 52 patients were restored with a microhybrid composite Gradia Direct (GC), bonded in random order either with the HEMA-free 1SEa G-Bond (GB; GC) or the considered gold-standard 3E&Ra Optibond FL (OFL; Kerr). The restorations were evaluated after 6 months, 1, 2, 3, 5 and 9 years of clinical service for retention, marginal adaptation, marginal discoloration, caries occurrence and tooth sensitivity. Statistical analysis was done using a logistic regression model with generalized estimating equations (2-way GEE model). RESULTS: The patient recall rate at 9 years was 82.6%. The overall clinical success rate was 80.3% and 79.5% for GB and OFL, respectively. In total, 47 restorations (23 GB, 24 OFL) failed because of retention loss, severe marginal defects and/or discoloration and/or caries. A similar retention rate of 89.7% was recorded for both adhesives GB and OFL. Slight marginal defects and superficial marginal discoloration, though both still clinically acceptable, were significantly more observed at the incisal enamel side of GB (92.4% and 52.1%, respectively) than OFL (59.6%; 30.8%) restorations (p < 0.05). CONCLUSION: After 9 years of clinical service, class-V restorations bonded with the HEMA-free 1SEa performed clinically equally successful as those bonded with the 3E&Ra. However, more marginal deterioration, though still clinically acceptable, was recorded at the incisal enamel side for the 1SEa.

Bonding Effectiveness of Luting Composites to Different CAD/CAM Materials.

PURPOSE: To evaluate the influence of different surface treatments of six novel CAD/CAM materials on the bonding effectiveness of two luting composites. MATERIALS AND METHODS: Six different CAD/CAM materials were tested: four ceramics - Vita Mark II; IPS Empress CAD and IPS e.max CAD; Celtra Duo - one hybrid ceramic, Vita Enamic, and one composite CAD/CAM block, Lava Ultimate. A total of 60 blocks (10 per material) received various mechanical surface treatments: 1. 600-grit SiC paper; 2. sandblasting with 30-µm Al2O3; 3. tribochemical silica coating (CoJet). Subsequent chemical surface treatments involved either no further treatment (control), HF acid etching (HF), silanization (S, or HF acid etching followed by silanization (HF+S). Two specimens with the same surface treatment were bonded together using two dual-curing luting composites: Clearfil Esthetic Cement (self-etching) or Panavia SA Cement (self-adhesive). After 1 week of water storage, the microtensile bond strength of the sectioned microspecimens was measured and the failure mode was evaluated. RESULTS: The bonding performance of the six CAD/CAM materials was significantly influenced by surface treatment (linear mixed models, p < 0.05). The luting cement had a significant influence on bond strength for Celtra Duo and Lava Ultimate (linear mixed models, p < 0.05). Mechanical surface treatment significantly influenced the bond strength for Celtra Duo (p = 0.0117), IPS e.max CAD (p = 0.0115), and Lava Ultimate (p < 0.0001). Different chemical surface treatments resulted in the highest bond strengths for the six CAD/CAM materials: Vita Mark II and IPS Empress CAD: S, HF+S; Celtra Duo: HF, HF+S; IPS e.max CAD: HF+S; Vita Enamic: HF+S, S. For Lava Ultimate, the highest bond strengths were obtained with HF, S, HF+S. Failure analysis showed a relation between bond strength and failure type: more mixed failures were observed with higher bond strengths. Mainly adhesive failures were noticed if no further surface treatment was done. The percentage of adhesive failures was higher for CAD/CAM materials with higher flexural strength (Celtra Duo, IPS e.max CAD, and Lava Ultimate). CONCLUSION: The bond strength of luting composites to novel CAD/CAM materials is influenced by surface treatment. For each luting composite, an adhesive cementation protocol can be specified in order to obtain the highest bond to the individual CAD/CAM materials.

Five-year clinical performance of a HEMA-free one-step self-etch adhesive in noncarious cervical lesions.

OBJECTIVES: The objective of this randomized controlled trial was to evaluate the clinical performance of a 2-hydroxyethyl methacrylate (HEMA)-free one-step adhesive. MATERIALS AND METHODS: Two hundred sixty-seven cervical lesions in 52 patients were restored with the composite Gradia Direct (GC), bonded with either the one-step self-etch adhesive G-Bond (GC) or the three-step etch-and-rinse adhesive Optibond FL (Kerr) in a random order. The restorations were evaluated for retention, marginal integrity, marginal discoloration, and caries occurrence after 5 years. Specific statistics were used to account for the clustered data (multiple restorations per patient). RESULTS: The clinical success rate for G-Bond (87.4 %) was not significantly different from that of Optibond FL (90.9 %). Both adhesives showed progressive marginal deterioration, but G-Bond exhibited more small enamel defects and marginal discoloration, and unlike previous recalls, several restorations failed because of deep microleakage. Large sclerotic lesions were a significant risk factor for retention loss with G-Bond. Irrespective of the adhesive, almost all restorations with retention loss were located in the lower jaw. CONCLUSION: After 5 years of clinical service, restorations bonded with the HEMA-free one-step adhesive did not need repair or replacement more often than those with the three-step etch-and-rinse adhesive, and both adhesives had a high retention rate (>90 %). There were indications that G-Bond did not (self-)etch enough in some clinical situations, as G-Bond exhibited more incisal defects and marginal discolorations, and sclerotic lesions were at higher risk of retention loss. CLINICAL RELEVANCE: The clinical performance of the HEMA-free one-step adhesive was clinically acceptable after 5 years.

Multi-Parameter Characterization of HEMA/BPA-free 1- and 2-step Universal Adhesives Bonded to Dentin.

PURPOSE: This study aimed to investigate the bonding effectiveness of two HEMA/BPA-free universal adhesives (UAs) to flat dentin, to characterize their adhesive-dentin interfacial ultrastructure, and to measure their water sorption (Wsp), water solubility (Wsl), and hydrophobicity. MATERIALS AND METHODS: The immediate and aged (50,000 thermocycles) microtensile bond strength (µTBS) to flat dentin of the HEMA/BPA-free UAs Healbond Max (HbMax; Elsodent) and Healbond MP (HbMP; Elsodent) as well as the reference adhesives OptiBond FL (Opti-FL; Kerr), Clearfil SE Bond 2 (C-SE2; Kuraray Noritake), and Scotchbond Universal (SBU; 3M Oral Care) was measured. The adhesive-dentin interfaces of HbMax and HbMP were characterized by TEM. Wsp and Wsl of all adhesive resins and of the primer/adhesive resin mixtures of HbMax, Opti-FL, and C-SE2 were measured. Hydrophobicity was determined by measuring the contact angle of water dropped on adhesive-treated dentin. RESULTS: In terms of µTBS, HbMax and HbMP performed statistically similarly to Opti-FL and C-SE2, but outperformed SBU. Aging only significantly reduced the µTBS of SBU when applied in E&R bonding mode. TEM revealed typical E&R and SE hybrid-layer ultrastructures at dentin, while electron-lucent globules of unknown origin, differing in size and shape, were observed within the adhesive resin of HbMP and even more frequently in that of HbMax. Higher Wsp was measured for the primer/adhesive resin mixtures than for the adhesive resins. Opti-FL was more hydrophobic than all other adhesives tested. CONCLUSION: The HEMA/BPA-free UAs bonded durably to flat dentin with bond strengths comparable to those of the gold-standard E&R/SE adhesives and superior to that of the HEMA/BPA-containing 1-step UA.

Bonding of Composite Cements Containing 10-MDP to Zirconia Ceramics Without Dedicated Ceramic Primer.

PURPOSE: To measure zirconia-to-zirconia microtensile bond strength (µTBS) using composite cements with and without primer. MATERIALS AND METHODS: Two Initial Zirconia UHT (GC) sticks (1.8x1.8x5.0 mm) were bonded using four cements with and without their respective manufacturer's primer/adhesive (G-CEM ONE [GOne] and G-Multi Primer, GC; Panavia V5 [Pv5]), and Panavia SA Cement Universal [PSAu], and Clearfil Ceramic Plus, Kuraray Noritake; RelyX Universal (RXu) and Scotchbond Universal Plus [SBUp], 3M Oral Care). Specimens were trimmed to an hour-glass shaped specimen whose isthmus is circular in cross-section. After 1-week water storage, the specimens were either tested immediately (1-week µTBS) or first subjected to 50,000 thermocycles (50kTC-aged µTBS). The fracture mode was categorized as either adhesive interfacial failure, cohesive failure in composite cement, or mixed failure, followed by SEM fracture analysis of selected specimens. Data were analyzed using linear mixed-effects statistics (α = 0.05; variables: composite cement, primer/adhesive application, aging). RESULTS: The statistical analysis revealed no significant differences with aging (p = 0.3662). No significant difference in µTBS with/without primer and aging was recorded for GOne and PSAu. A significantly higher µTBS was recorded for Pv5 and RXu when applied with their respective primer/adhesive. Comparing the four composite cements when they were applied in the manner that resulted in their best performance, a significant difference in 50kTC-aged µTBS was found for PSAu compared to Pv5 and RXu. A significant decrease in µTBS upon 50kTC aging was only recorded for RXu in combination with SBUp. CONCLUSION: Adequate bonding to zirconia requires the functional monomer 10-MDP either contained in the composite cement, in which case a separate 10-MDP primer is no longer needed, or in the separately applied primer/adhesive.

Four-year clinical evaluation of a self-adhesive luting agent for ceramic inlays.

OBJECTIVES: The aim of this randomized controlled clinical trial was to evaluate the 4-year clinical performance of a self-adhesive resin cement, RelyX Unicem (3M ESPE), used for cementation of ceramic inlays. In addition, the influence of selectively acid-etching enamel prior to luting on the clinical performance of the restorations was assessed. METHODS: Sixty-two IPS Empress 2 inlays/onlays were placed in 31 patients by two experienced clinicians. The restorations were luted with RelyX Unicem with (=experimental group: E) or without (=control group: NE) prior enamel etching with phosphoric acid. At baseline, 6 months, and 1, 2, and 4 years after placement, the restorations were assessed by two calibrated investigators using modified USPHS criteria. Ten selected samples of each group were investigated under SEM regarding morphological changes at the cement-inlay interface. RESULTS: The recall rate at 4 years was 97%. Two restorations (1 E, 1 NE) were lost, and one (E) had to be replaced due to inlay and tooth fracture resulting in a survival rate of 95%. No significant differences between the experimental and control group were noticed regarding all criteria (McNemar, p < 0.05). An obvious deterioration in marginal integrity was observed after 4 years as only 5% (E = 7%; NE = 3%) of the restorations exhibited an excellent marginal adaptation. In 90% of the restorations small, still clinically acceptable marginal deficiencies were observed. SEM of the luting gap showed an increased wear of the RelyX Unicem cement over the 4-year period. CONCLUSIONS: The self-adhesive luting cement RelyX Unicem can be recommended for bonding of ceramic inlays/onlays. Additional selective enamel etching does not improve the clinical performance of the restorations within the 4-year period. CLINICAL RELEVANCE: The self-adhesive resin composite RelyX Unicem showed acceptable clinical performance after 4 years of clinical service.

Fourteen-year Clinical Performance of a HEMA-free One-step Self-etch Adhesive in Non-carious Cervical Lesions.

PURPOSE: This randomized controlled trial aimed to evaluate the 14-year clinical performance of a HEMA-free 1-step self-etch adhesive (1SEa) compared with that of a 3-step etch-and-rinse adhesive (3E&Ra). MATERIALS AND METHODS: 267 non-carious cervical lesions in 52 patients were restored with the microhybrid composite Gradia Direct (GC), bonded in random order either with the HEMA-free 1SEa G-Bond (GB; GC) or the 3E&Ra Optibond FL (OFL; Kerr), which is considered the gold-standard E&Ra (control). The restorations were followed over 14 years for retention, marginal adaptation and discoloration, and caries occurrence. Statistical analysis involved a logistic regression model with generalized estimating equations (2-way GEE model). RESULTS: The patient recall rate at 14 years was 63%. In total, 79 restorations (39 GB, 40 OFL) failed because of retention loss (GB: 19.4%, OFL: 19.6%), severe marginal defects, discoloration and/or caries (GB: 21.7%; OFL: 22.5%). The overall clinical success rate was 58.9% and 57.9% for GB and OFL, respectively. The number of restorations with an unacceptable marginal defect (GB: 14.5%; OFL: 19.2%) and deep marginal discoloration (GB: 18.2%; OFL: 13.2%) increased during the last 5 years. No significant difference in overall clinical performance was recorded between the two adhesives (p > 0.05). Changes in the medical health of some patients and recurrence of abrasion/erosion/abfraction increased the failure rate and retention rate. CONCLUSION: After 14 years, restorations bonded with the HEMA-free 1SEa performed as well as those bonded with the 3E&Ra gold standard. Unacceptable marginal deterioration was the main reason for failure, followed by loss of retention.

Experimental two-step universal adhesives bond durably in a challenging high C-factor cavity model.

OBJECTIVES: To determine the bonding effectiveness of experimental 2-step universal adhesives (UAs) to high C-factor class-I cavity-bottom dentin and to assess the potential bond-strength contribution of an additional flowable composite layer. METHODS: Three experimental 2-step UA formulations, involving the application of a 10-MDP-based primer followed by a hydrophobic adhesive resin with a 15-to-20-µm film thickness and differing only for filler, referred to as BZF-21 (silica and bioglass filler), BZF-29 (silica filler) and BZF-29_hv (higher silica-filler loading resulting in a higher viscosity), all prepared by GC, along with three representative commercial adhesives, Clearfil SE Bond 2 (C-SE2, Kuraray Noritake), G-Premio Bond (G-PrB, GC) and OptiBond FL (Opti-FL, Kerr), were comparatively investigated for their 'immediate' and 'aged' (50,000 thermocycles) micro-tensile bond strength (µTBS), when applied either in etch-and-rinse (E&R) or self-etch (SE) mode, to high C-factor class-I cavity-bottom dentin (n = 10; 10 experimental groups). Four additional experimental groups involved the extra application of the flowable composite G-ænial Universal Flo (GC), employed as an intermediate liner in combination with the adhesives BZF-29 and G-PrB and again applied both in E&R or SE mode. Statistical analysis was performed using linear mixed-effects (LME) modelling and linear regression analysis (p < 0.05). RESULTS: All 2-step UAs performed similarly when compared to the gold-standard E&R Opti-FL and SE C-SE2 adhesives, except for the aged µTBS of BZF-29_hv applied in E&R mode, and significantly outperformed the 1-step UA G-PrB. Significant reduction in µTBS upon aging was only recorded for 2-step UAs applied in E&R mode. The extra flowable composite layer significantly improved G-PrB's µTBS. SIGNIFICANCE: The experimental 2-step UAs revealed favorable bonding performance in the challenging high C-factor class-I cavity model, comparable to that of the multi-step gold-standard E&R and SE adhesives and superior to that of the 1-step UA investigated. An additionally applied flowable composite layer compensated for the lower bonding effectiveness of the 1-step UA in the high C-factor cavity model.

Adhesive Performance Assessment of Universal Adhesives and Universal Adhesive/Composite Cement Combinations.

PURPOSE: To investigate the bonding performance of three universal adhesives (UAs) to dentin and the effect of different curing modes and hydrofluoric-acid (HF) etching of lithium-disilicate glass-ceramic on the adhesive performance of two UA/composite cement (CC) combinations. MATERIALS AND METHODS: In the first project part, the immediate and aged (25k and 50k thermocycles) microtensile bond strength (µTBS) of the two light-curing UAs G2-Bond Universal (G2B; GC) and Scotchbond Universal Plus (SBUp; 3M Oral Care), and the self-curing UA Tokuyama Universal Bond II (TUBII; Tokuyama) to flat dentin was measured, when applied in both E&R and SE bonding mode using a split-tooth design (n = 10). The resultant adhesive-dentin interfaces were characterized using TEM. In the second project part, CAD/CAM composite blocks were luted to flat dentin with either Scotchbond Universal Plus/RelyX Universal (SBUp/RxU; 3M Oral Care) or Tokuyama Universal Bond II/Estecem II Plus (TUBII/ECIIp; Tokuyama Dental) using different curing modes (AA mode: auto-curing of both adhesive and cement; AL mode: auto-curing of adhesive and light-curing of cement), upon which their immediate and aged (25k and 50k thermocycles) µTBS was measured. In the third project part, the same UA/CC combinations were luted to CAD/CAM glass-ceramic to measure their immediate and aged (6-month water storage) shear bond strength (SBS). RESULTS: In E&R bonding mode, the performance of G2B, SBUp and TUBII was not significantly different in terms of µTBS, while G2B and SBUp significantly outperformed TUBII in SE bonding mode. No significant difference in µTBS was found between the SBUp/RxU and TUBII/ECIIp UA/CC combinations, regardless of bonding mode, aging time, or curing mode. The cement-curing mode did not significantly influence µTBS, while a significantly higher µTBS was recorded for the UA/CC combinations applied in E&R bonding mode. HF significantly improved the SBS of the UA/CC combinations to glass-ceramic. CONCLUSION: The self-curing adhesive performed better when applied in E&R than in SE bonding mode. The curing mode did not influence the adhesive performance of the composite cements, while an E&R bonding mode rendered more favorable adhesion in a self-curing luting protocol. When bonding to glass-ceramic, the adhesive performance of the universal adhesive/composite cement combinations benefited from HF etching.

Three-year Clinical Performance of a Universal Adhesive in Non-Carious Cervical Lesions.

PURPOSE: The aim of this randomized controlled clinical trial was to evaluate the 3-year clinical performance of a universal adhesive (Clearfil Universal Bond Quick (CUBQ); Kuraray Noritake) when restoring non-carious cervical lesions (NCCLs) using two different application modes (etch-and-rinse vs self-etch with prior selective enamel etching). MATERIALS AND METHODS: Fifty-one patients participated in this study. A total of 251 NCCLs (n = 251) were assigned to two groups: 1) CUBQ applied in etch-and-rinse mode (n = 122; CUBQ-ER) and 2) CUBQ applied in self-etch mode with prior selective etching of enamel with phosphoric acid (n = 129; CUPQ-SEE). The same resin composite, Clearfil Majesty ES-2 (Kuraray Noritake), was used for all restorations. The restorations were evaluated at baseline, 1 and 3 years using FDI criteria: marginal staining, fracture and retention, marginal adaptation, post-operative sensitivity and recurrence of caries. Statistical analysis was performed using a logistic regression model with generalized estimating equations (2-way GEE model). RESULTS: The patient recall rate at 3 years was 90%. After 3 years, both groups presented an increase in the percentage of small but still clinically acceptable marginal defects (CUBQ-ER: 67%, CUBQ-SEE: 63.2%) and marginal staining (CUBQ-ER: 32.6%, CUBQ-SEE: 31.7%). The overall success rate was 82.6% and 83.8% for CUBQ-ER and CUBQ-SEE, respectively. In total, 38 restorations (19 CUBQ-ER, 19 CUBQ-SEE) failed because of loss of retention, fracture, severe marginal defect and/or marginal discoloration. A retention rate of 87.2% and 86.3% was recorded for CUBQ-ER and CUBQ-SEE, respectively. No significant difference was observed between the two bonding-mode groups for any of the evaluated parameters. CONCLUSION: After 3 years of clinical service, Clearfil Universal Bond Quick performed similarly in etch-and-rinse and self-etch modes with prior selective enamel etching.

A 13-year clinical evaluation of two three-step etch-and-rinse adhesives in non-carious class-V lesions.

This 13-year randomized clinical trial compared the clinical effectiveness of two three-step etch-and-rinse adhesives in combination with a hybrid, stiffer composite versus a micro-filled, more flexible composite. The influence of composite stiffness on the clinical performance of one of the adhesives was assessed as well. One hundred and forty-two non-carious cervical lesions were restored with composites with contrasting stiffness. Seventy-one patients randomly received two cervical restorations placed following two out of three adhesive procedures: (1) the three-step etch-and-rinse adhesive Permaquick applied with the stiff micro-hybrid composite Amelogen Hybrid (PMQ-H, Ultradent), (2) Permaquick applied with the more flexible micro-filled Amelogen Microfill (PMQ-M, Ultradent), or (3) the "gold-standard" three-step etch-and-rinse adhesive Optibond FL applied with the micro-hybrid composite Prodigy (OFL-P, Kerr). The restorations were evaluated after 6 months, 1, 2, 3, 5, 7, and 13 years of clinical service regarding their retention, marginal integrity and discoloration, caries occurrence, preservation of tooth vitality, and post-operative sensitivity. Retention loss, severe marginal defects, and/or discoloration that needed intervention (repair or replacement) and the occurrence of caries were considered as clinical failures. The recall rate at 13 years was 77%. Bond degradation after 13 years was mainly characterized by a further increase in the presence of small but clinically acceptable marginal defects and superficial marginal discoloration. Twelve percent of the OFL-P restorations were clinically unacceptable. In the PMQ group, 22% of the PMQ-M restorations and 26% of the PMQ-H restorations needed repair or replacement. Regarding the clinical failure rate, Optibond FL scored significantly better than Permaquick (McNemar; p = 0.015). No statistically significant differences were found between the micro-filled and the hybrid composite for each of the parameters evaluated (McNemar, p > 0.05). After 13 years of clinical functioning, the clinical effectiveness of the three adhesive/composite combinations remained highly acceptable.

Nanohybrid and microfilled hybrid versus conventional hybrid composite restorations: 5-year clinical wear performance.

UNLABELLED: The 5-year findings of a randomized clinical trial testing the null hypothesis that there are no differences between the clinical-wear performances of nano-, microfilled-, and conventional hybrids placed in class I and class II cavities are reported. Effects of subject-, operator-, and restoration-related variables on wear were assessed. Sixteen Tetric-C, 17 Tetric-EC, and 16 Gradia-DP restorations were placed in human molars and recalled at baseline, 6 months and at yearly intervals. The gypsum replicas at each recall were scanned (3D laser scanning), epoxy resin replicas were observed under scanning electron microscope and linear mixed models were used to study the influence of different variables on wear. The generalized vertical wear rate/month were (1.4 µm Tetric-C and Tetric-EC; 1.8 µm Gradia-DP) and volume wear rate/month were (0.017 mm(3) Tetric-EC; 0.018 mm(3) Gradia-DP, and 0.011 mm(3) Tetric-EC). Operator-cavity type interaction and surface area of restorations did significantly influence the volume wear rates (p < 0.05). The three wear patterns: fatigue cracks at heavy occlusal contact area/OCA, pitting at light OCA, and scratches/striations along the food escape pathways were evident. The three hybrids differed significantly in volume wear due to material and operator variables. CLINICAL RELEVANCE: Clinically, operators and cavity type can affect restorations' wear magnitude but do not contribute to increased functional risk of fracture or harmful effect on pulp and periodontal biocompatibility.

Clinical effectiveness of a one-step self-etch adhesive in non-carious cervical lesions at 2 years.

A 2-year randomized, controlled prospective study evaluated the clinical effectiveness of a one-step self-etch adhesive and a "gold-standard" three-step etch-and-rinse adhesive in non-carious Class-V lesions. The null hypothesis tested was that the one-step self-etch adhesive does perform clinically equally well as the three-step etch-and-rinse adhesive. A total of 161 lesions in 26 patients were restored with Clearfil AP-X (Kuraray). The restorations were bonded either with the "all-in-one" adhesive Clearfil S3 Bond (Kuraray) or with the three-step etch-and-rinse adhesive Optibond FL (Kerr). The restorations were evaluated at baseline and after 6 months, 1 and 2 years, regarding their retention, marginal adapation, marginal discoloration, caries occurrence, preservation of tooth vitality and post-operative sensivity. Retention loss, severe marginal defects and/or discoloration that needed intervention (repair or replacement) and the occurrence of caries were considered as clinical failures. The recall rate at 2 years was 93.8%. Only one Clearfil S3 Bond restoration was lost at the 2-year recall. All other restorations were clinically acceptable. The number of restorations with defect-free margins decreased severely during the 2-year study period (to 6.7% and 25.3% for Clearfil S3 Bond and Optibond FL, respectively). The Clearfil S3 Bond restorations presented significantly more small marginal defects at the enamel side than the Optibond FL restorations (Clearfil S3 Bond: 93.3%; Optibond FL: 73.3%; p = 0.000). Superficial marginal discoloration increased in both groups (to 53.3% and 36% for Clearfil S3 Bond and Optibond FL, respectively) and was also more pronounced in the Clearfil S3 Bond group (p = 0.007). After 2 years, the simplified one-step self-etch adhesive Clearfil S3 Bond and the three-step etch-and-rinse adhesive Optibond FL were clinically equally successful, even though both adhesives were characterized by progressive degradation in marginal integrity. Clearfil S3 Bond exhibited more small enamel marginal defects and superficial marginal discolorations.

Dentin conditioned with a metal salt-based conditioner.

OBJECTIVES: Universal adhesives (UAs) can optionally be applied in either an etch-and-rinse (E&R) or self-etch (SE) bonding mode. As the preferred bonding mode differs for enamel versus dentin, a universal conditioner for both enamel and dentin in replacement of the relatively aggressive phosphoric-acid etchant remains desirable. This study aimed to test if a metal salt-based etchant (ZrO(NO3)2) provides as durable bonding to dentin as a classic E&R or SE bonding mode METHODS: Before applying the UA Adhese Universal ('AdU'; Ivoclar Vivadent) to bur-cut dentin of 24 teeth (n = 8), dentin was conditioned with either (1) an experimental metal salt-based conditioner ('ZON'; Ivoclar Vivadent) or (2) 37% phosphoric acid (Total Etch gel, Ivoclar Vivadent), representing a classic 'E&R' mode; (3) a third experimental group involved AdU applied in SE mode. Bonding effectiveness was determined in terms of immediate ('1w') and aged ('50k' TC) micro-tensile bond strength (µTBS) to bur-cut dentin. Adhesive-conditioned dentin interfacial interactions were characterized by S/TEM. RESULTS: Linear mixed-effects modeling revealed significantly higher immediate µTBS to dentin of ZON_AdU than E&R_AdU, while ZON_AdU performed not significantly different from SE_AdU. No significant differences were found between the three experimental groups after 50k TC (aged µTBS). S/TEM disclosed less exposure of dentinal collagen fibrils when AdU was bonded upon ZON etching than when applied in E&R mode. Moreover, ZON resulted in more hydroxyapatite (HAp) crystals remaining at the bottom of the hybrid layer, while dentinal tubule orifices remained nearly fully closed, by which hardly any resin tags were formed. SIGNIFICANCE: The alternative metal salt-based conditioner revealed at dentin a more HAp-protected hybrid layer with less exposure of collagen fibrils, while a comparable bond strength was obtained to that with a phosphoric-acid E&R as well as with an SE (no conditioner) bonding mode. These findings confirm that the metal salt-based conditioner can be considered as a suitable alternative (enamel/)dentin conditioner to classic phosphoric acid employed in an E&R bonding mode.

3D printing and milling accuracy influence full-contour zirconia crown adaptation.

OBJECTIVES: To correlate trueness and cement-space characteristics of crowns milled chairside and in the laboratory with those of inkjet 3D-printed crowns, and to assess whether 3D-printing accuracy meets the clinical standard. METHODS: Thirty crowns were either (1) milled using a chairside Cerec MCXL unit from Cerec Zirconia Mono L (Dentsply Sirona), (2) milled using a LX-O 5-axis (Matsuura Machinery) industrial machine from Initial Zirconia HT (GC), or (3) 3D-printed using an inkjet Carmel 1400 (Xjet) printer (n = 10). Crown trueness determined by comparing the original CAD with each visible-light digitized crown was correlated with the 3D cement-space characteristics recorded by micro-CT. Statistics involved Kruskal-Wallis testing and Spearman correlation. RESULTS: Crown trueness at the intaglio marginal area positively correlated with the marginal and axial cement-space characteristics. 3D-printing revealed data in-between those of the two milling systems with undercut values being not statistically different from those recorded for chairside milling and a low overcut level that was statistically similar to that obtained by laboratory milling. Laboratory milling revealed a significantly better marginal accuracy with a consequently lower cement-space thickness. A higher overcut level was recorded for the chairside-milled crowns in the marginal/occlusal thirds, resulting in the significantly highest occlusal cement-space thickness and cement-volume percentage with a cement thickness above 120 µm (limit considered as clinically acceptable). No statistical difference in trueness was found for the external crown dimensions. SIGNIFICANCE: The 3D-printed zirconia crowns provided sufficient manufacturing accuracy for clinical use. Accurate milling and printing of the crown's intaglio marginal area is primordial.

Three-year clinical performance of a HEMA-free one-step self-etch adhesive in non-carious cervical lesions.

Despite the fact that one-step adhesives are currently used routinely in clinical practice, long-term studies on their clinical performance are scarce. The objective of this randomized controlled clinical trial was to test the hypothesis that a 2-hydroxyethyl methacrylate (HEMA)-free one-step self-etch adhesive performs worse than a conventional multistep etch-and-rinse adhesive. Two-hundred and seventy-six non-carious cervical lesions in 52 patients were restored with a micro-hybrid composite (Gradia Direct; GC). These restorations were bonded in random order either with the HEMA-free one-step adhesive G-Bond (GC) or with the 'gold-standard' (control) three-step adhesive Optibond FL (Kerr). The restorations were evaluated after 6, 12, 24, and 36 months of clinical service regarding retention, marginal adaptation, microleakage, caries occurrence, and sensitivity. After a medium-long period of 3 yr, similar success in clinical performance was observed for the simplified all-in-one adhesive and the conventional three-step adhesive. However, the one-step adhesive exhibited significantly more incisal marginal defects and discolorations. Whereas marginal degradation appeared to arrest for the multistep etch-and-rinse adhesive after 12 months, the enamel margins of the restorations bonded with the one-step self-etch adhesive continued to deteriorate. These incisal marginal defects were, however, small and could easily be removed by polishing. For both adhesives, large and sclerosed lesions appeared to be at higher risk of retention loss.