Biological interaction, esthetics, handling, and loss rate of temporary luting cements - a clinical single-blind randomized controlled trial.

OBJECTIVES: To evaluate three temporary luting cements in terms of their restoration loss rates, biological interactions, esthetic properties, and handling characteristics. MATERIALS AND METHODS: 75 adults requiring fixed prosthodontics voluntarily participated in a single-blind, randomized controlled trial. After preparation, temporary restorations were luted with a randomly selected temporary luting cement (either Provicol QM Plus (PQP), Bifix Temp (BT), or Provicol QM Aesthetic (PQA)). Clinical examinations were performed one to two weeks after cementation. The following criteria were evaluated: tooth vitality, percussion, hypersensitivity, gingival bleeding, odor formation, esthetics, cement handling, removability, cleanability, and retention loss. Antagonistic teeth served as controls. Statistical analysis was performed using the paired t-test, one-way ANOVA, Pearson's chi-square and Fisher's exact test, where appropriate. RESULTS: The overall loss rate of temporary restorations was 16.0%, showing no cement-specific differences. Postoperative hypersensitivity occurred in 8% of cases regardless of cement type. Esthetic impairment was reported by 31% of the PQP-fixed restorations, compared with 4.0% and 4.2% of the BT and PQA-bonded restorations. Cement application was reported to be easy in 100% of cases, excess removal in 88-96%, depending on the cement used. CONCLUSIONS: The choice of luting material affects the esthetic appearance of a temporary restoration and should be considered, particularly in restorations in esthetically demanding areas. No significant differences between the cements were identified regarding biocompatibility, handling, and loss rate. CLINICAL RELEVANCE: Translucent cements can help to reduce color interferences, resulting in a more appealing appearance of the temporary restoration.

Historical Perspectives and Comparisons on the Use Plastic-Based Cements in Endodontics and Prosthodontics: Part 2 - Oxyphosphates.

Oxyphosphate of zinc was used for years to treat teeth by different approaches and procedures. Like oxychloride of zinc, success of the material depended on how well the procedures were conducted and largely on the mix of the material. This article aims to review the evolutionary history of this material with a view to its clinical uses, properties, procedures, applications, and successes when used in the management of decayed tooth structure and rebuilding of teeth. Perspectives proffered within focus cover 110 years from 1850 to 1960.

Abutment margin levels and residual cement occurrence in cement-retained implant restorations: An observational study.

OBJECTIVES: To evaluate the association between different vertical levels of the abutment margin and residual cement prevalence in cement-retained implant restorations with customized abutments. METHODS: One hundred and nine single-unit cement-retained implant restorations with a screw-access channel were included. The crowns were intraorally cemented on the abutments, and excess cement was removed. The abutment-crown complex was unscrewed, and the abutment-crown complex and peri-implant tissue were photographed. Residual cement presence was recorded by dividing the abutment-crown complex and peri-implant tissue into four quadrants: mesial, distal, buccal, and lingual. The prevalence of residual cement was compared according to the height of the custom abutment margin of the corresponding quadrant. A multilevel model was used for statistical analysis (α = .05). RESULTS: Cement remnants were discovered on 72.48% of the dental implants. When the restoration quadrants were compared, cement remnants were present on 51.38%, 39.45%, 20.18%, and 17.43% of the mesial, distal, buccal, and lingual surfaces, respectively (p < .01). Regarding the abutment margin level, cement residues were found in 60.22% and 61.4% of the 0.5 mm subgingival and ≥1 mm subgingival margin groups, respectively, which were significantly more than those in the supragingival (23.65%) and equigingival (26.59%) margin groups (p < .01). After adjustment for confounding factors, the adjusted odds ratio (with 95% confidence interval) for residual cement in the subgingival margin groups was 3.664 (1.71, 7.852) when compared to the supragingival and equigingival margin groups. CONCLUSIONS: The risk of residual cement occurrence was 3.66-fold higher with a subgingival abutment margin than with supragingival and equigingival abutment margins.

Effect of temporary cements and their removal methods on the bond strength of indirect restoration: a systematic review and meta-analysis.

OBJECTIVES: For a conventional indirect restoration, temporary cementation inevitably contaminated collapsed dentin collagen. The purpose of this review was to evaluate the optimal strategy for minimizing its negative effects. MATERIAL AND METHODS: Databases such as PubMed, Web of Science, EMBASE, and the Cochrane Library were searched for in vitro studies, involving the influence of immediate dentin sealing (IDS), different temporary cements, and their removal strategies on dentin bond strength. The meta-analysis used the inverse variance method with effect method of the standardized mean difference and statistical significance at p ≤ 0.05. The I2 value and the Q-test were used to assess the heterogeneity. RESULTS: A total of 14 in vitro trials were subjected to the meta-analysis. Within the study's limitations, we assumed that IDS eliminated the negative effects of temporary bonding, achieving the comparable immediate bond strength with the control (p = 0.46). In contrast, under delayed dentin sealing (DDS), temporary cementation statistically decreased bond strength (p = 0.002). Compared with resin-based and non-eugenol zinc oxide cements, polycarboxylate and calcium hydroxide cements performed better on bond strength with no statistical difference from the control group (p > 0.05). Among the removal methods of temporary cements, the Al2O3 abrasion restored the decreased bond strength (p = 0.07) and performed better than hand instruments alone (p = 0.04), while pumice removal slightly reduced the bond strength in contrast with the control group (p = 0.05, 95% CI = - 1.62 to 0). CONCLUSIONS: The choices of IDS, polycarboxylate and calcium hydroxide temporary cements, Al2O3 abrasion removal method were feasible and efficient to enhance the bond strength. CLINICAL RELEVANCE: It is worthwhile applying IDS technique, polycarboxylate and calcium hydroxide temporary cements during indirect restoration. The Al2O3 abrasion of cleaning dentin can minimize the negative effects of temporary cement.

Effect of apical root resection, orthodontic extrusion, and surgical crown lengthening on load capability.

OBJECTIVES: This study aims to investigate the load-to-fracture of procedures changing crown-to-root ratio (RCRR) aimed to restore severely damaged upper central incisors to avoid tooth extraction compared to implant placement. There is no evidence on load capability after apical root resection (AR), orthodontic extrusion (OE), and surgical crown lengthening (SCL) in respect to RCRR, respectively. MATERIAL AND METHODS: Human maxillary central incisors were endodontically treated, decoronated, and divided into 4 groups (n = 48). The following specimen preparation was performed: (I) adhesive core-and-post build-up (control), (II) as (I) and 2 mm apical root resection (AR), (III) before adhesive core-and-post build-up teeth were shortened 2 mm coronally (OE) (IV) as (I), but specimens were embedded 4 mm instead of 2 mm below the CEJ (SCL), group (V) implant-borne restoration with individual all-ceramic abutments (n = 12; ∅4.1/l = 12 mm) (IBR). All specimens received all-ceramic crowns, thermo-mechanical (TML), and subsequent linear loading (LL) until failure. RCRR were calculated and log-rank, Kruskal-Wallis, Mann-Whitney U, ANOVA, and chi-square tests applied (p = 0.05). RESULTS: Fracture loads after subsequent LL differed significantly (p = 0.001) between groups, while implants showed the highest values. Fmax median (min/max) were as follows: (I) 252 (204/542), (II) 293 (243/443), (III) 253 (183/371), (IV) 195 (140/274), and (V) 446 (370/539). Pair-wise comparison showed significant differences (p = 0.001) between group I/IV and group V, I, and IV (p = 0.045), II and IV (p = 0.001), and III compared to IV (p = 0.033), respectively. RCRR below 1 significantly increased load capability compared to RCRR = 1. CONCLUSIONS: OE appears to preferably ensure biomechanical stability of teeth that are endodontically treated and receive core-and-post and crown placement compared to SCL. AR has no adverse biomechanical impact. RCRR < 1 is biomechanically beneficial. CLINICAL RELEVANCE: For endodontically treated and restored teeth, orthodontic extrusion should be preferred compared to surgical crown lengthening prior single-crown restoration. As orthodontic extrusion, apical root resection has no adverse effect on load capability. Single-crown implant-borne restorations are most load capable.

Effect of thickness of CAD/CAM materials on light transmission and resin cement polymerization using a blue light-emitting diode light-curing unit.

OBJECTIVE: Evaluate the effect of thickness of high-translucency (HT) CAD/CAM materials on irradiance and beam profile from a blue light-emitting diode light-curing unit (LCU) and on the degree of conversion (DC) and maximum polymerization rate (Rpmax ) of a light-cured resin cement (LCC). MATERIAL AND METHODS: The direct output from the LCU, the light transmission and irradiance ratio (IR) through one conventional composite and nine HT CAD/CAM materials (0.5, 1.0, 1.5, or 2.0-mm thick; n = 5) were measured with a integrating sphere coupled to a spectrometer. The light beam was assessed with a beam profiler camera. The DC at 600 s and the Rpmax of one LCC was determined using a Fourier transform infrared spectrometer (n = 5). Data were analyzed by ANOVA followed by Tukey's tests, and Dunnett's test was also used for irradiance data (α = 0.05). RESULTS: A significant decrease in irradiance through all materials occurred as thickness increased. Thin CAD/CAM materials improved light homogeneity, which decreased with the increase in thickness. The DC of the LCC directly exposed to light was the same as when exposed to 45%, 25%, 15%, or 5% IRs. Rpmax decreased with the decrease in IR. CONCLUSIONS: Although the HT CAD/CAM materials reduced the irradiance from the LCU, minor effects were observed in the LCC's DC. CLINICAL SIGNIFICANCE: Despite the light attenuation of blue light through different CAD/CAM materials that were up to 2-mm thick, the degree of conversion of one brand of light-cured resin cement was clinically acceptable when the LCU was used for 30 s.

Dental Luting Cements: An Updated Comprehensive Review.

The cementation of indirect restoration is one of the most important steps in prosthetic and restorative dentistry. Cementation aims to bond the prosthetic restoration to the prepared enamel or enamel and dentine. Successful cementation protocols prevent biofilm formation at the margin between tooth and restoration and minimize mechanical and biological complications. With the advancements in dental cements, they have been modified to be versatile in terms of handling, curing, and bond strengths. This review presents updates on dental cements, focusing on the composition, properties, advantages, limitations, and indications of the various cements available. Currently, dental restorations are made from various biomaterials, and depending on each clinical case, an appropriate luting material will be selected. There is no luting material that can be universally used. Therefore, it is important to distinguish the physical, mechanical, and biological properties of luting materials in order to identify the best options for each case. Nowadays, the most commonly used dental cements are glass-ionomer and resin cement. The type, shade, thickness of resin cement and the shade of the ceramic, all together, have a tangible influence on the final restoration color. Surface treatments of the restoration increase the microtensile bond strength. Hence, the proper surface treatment protocol of both the substrate and restoration surfaces is needed before cementation. Additionally, the manufacturer's instructions for the thin cement-layer thickness are important for the long-term success of the restoration.

Effect of the thickness of CAD-CAM materials on the shear bond strength of light-polymerized resin cement.

This study aimed to investigate the effect of the thickness of computer aided design-computer aided manufacturing (CAD-CAM) restorative materials on the bond strength of light-polymerized resin cement. Ninety specimens were prepared from three different CAD-CAM materials (a leucite-based glass-ceramic [Empress CAD], a polymer-infiltrated ceramic network [Vita Enamic], and a zirconia-reinforced lithium silicate glass-ceramic [Vita Suprinity]) in different thicknesses (1, 2, and 3 mm). One surface of each specimen was treated by using a single-step self-etching ceramic primer (Monobond Etch & Prime). Light-polymerized resin cement was bonded to treated surfaces by exposure to a light-emitting diode curing unit from the untreated side of the samples. Shear bond strength (SBS) between the ceramic and the resin cement was measured by using a universal testing machine. The leucite-based glass-ceramic had higher SBS values than the other materials at each thickness. For each material, 1 mm-thick specimens had the highest SBS values. The difference between the SBS values of 2 mm- and 3 mm-thick polymer-infiltrated ceramic network was nonsignificant, whereas the SBS values of 2 mm-thick leucite-based glass-ceramic and the zirconia-reinforced lithium silicate glass-ceramic were significantly higher than those of the corresponding 3 mm-thick specimens. The choice of the material and its thickness may be highly important for clinical success when light-polymerized resin cements are used for cementation.

A systematic review and meta-analysis on using preheated resin composites as luting agents for indirect restorations.

OBJECTIVES: This systematic review investigated the hypothesis that preheated resin composites (RCs) used as luting agents improve the mechanical properties, physicochemical performance, and color of indirect ceramic restorations. MATERIALS AND METHODS: Literature search was performed in three databases (Medline/PubMed, Scopus, and Web of Science) and in the grey literature (OpenGrey, ProQuest, and Catalog of Theses & Dissertations from CAPES). Eligibility criteria included only studies comparing at least one preheated RC used as a luting agent with resin cements. RESULTS: Data regarding the mechanical properties, physicochemical characteristics, and color were analyzed qualitatively, and the microtensile bond strength and film thickness were also evaluated by meta-analysis. The search strategy identified 3894 papers, and 28 were full-text screened. Seven studies were included in the review, and 5 were included in the meta-analysis. No significant difference was found for microtensile bond strength (P = 0.14). Preheated RCs showed significantly higher film thickness than resin cements (P = 0.001). CONCLUSION: Overall, the use of preheated RCs as luting agents offers similar to poorer performance than using resin cements for bonding indirect restorations. CLINICAL RELEVANCE: Despite the claim that preheated RC could be used as a luting agent, further studies should investigate the effect of clinically unacceptable film thickness.

Fracture load of zirconia crowns based on preparation and cement type.

Limited research has been published evaluating the failure of zirconia crowns with less retentive tooth preparations. The purpose of this study was to evaluate the effect of axial wall height (AWH) and cement type on the fracture load of cubic phase-containing zirconia crowns. Standardized crown preparations with an AWH of 0, 2, or 4 mm (n = 10) were made in 90 extracted human maxillary third molars. The preparations were scanned, and crown restorations were designed. Cubic phase-containing zirconia crowns were milled and cemented with a resin-modified glass ionomer cement, a self-adhesive resin cement, or an adhesive resin cement. The specimens were subjected to thermocycling and cyclic loading. Each crown specimen was positioned in a universal testing machine so that the long axis of the tooth was at a 60° angle to the testing fixture and loaded until failure using a stainless steel rod resting on the buccal incline of the palatal cusp. Data were found to have a nonnormal distribution and were analyzed with Kruskal-Wallis and Mann-Whitney U tests (α = 0.05). Statistically significant differences in the median fracture loads of the groups were found based on both AWH and cement type (P < 0.05). Regardless of cement type, the median fracture loads were significantly lower in the 0-mm AWH groups than in the 2-mm and 4-mm AWH groups, which were not significantly different from each other. Compared to the other cement types, adhesive resin cement resulted in a significantly greater median fracture load when the AWH was 0 mm. The use of an adhesive resin cement with a cubic phase-containing zirconia crown may provide greater fracture resistance for preparations with minimal AWH.

COMPARATIVE ANALYSIS OF ENDURANCE CEMENTS FOR THE FIXATION OF NON-REMOVABLE ORTHOPEDIC CONSTRUCTIONS UNDER THE ACTION OF CYCLIC COMPRESSION.

OBJECTIVE: The aim: To conduct studies of the physical and mechanical properties of cements for fixation, namely the duration of cement samples under cyclic compression. PATIENTS AND METHODS: Materials and methods: We have conducted a study of 6 cements for permanent fixation of fixed structures of dentures. To study the duration of cements under cyclic compression, a special stand was used, which allows testing samples for cyclic compression with a load frequency of 5.4 Hz or 324 cycles per minute and an increase in compression in a cycle from 10 to 100 kg/s. RESULTS: Results: Comparative analysis of the mechanical properties in compression of dental cements for permanent fixation showed that the obtained deformation curves differ significantly in each of the cement samples used in the study. CONCLUSION: Conclusions: The results of the study of the physical and mechanical properties of cements indicate that the most optimal complex of properties is possessed by the zincphosphate cement Unitsem and glass ionomer cements Cemion and Fuji I. This is most clearly confirmed when studying the duration of cement samples under cyclic compression, which simulates a real situation.

Cytotoxicity of contemporary resin-based dental materials in contact with dentin.

In this study, the cytotoxicity of different combinations of contemporary resin-based restoratives (adhesives, composites, luting agents) against human keratinocytes (HaCaT) was evaluated under two conditions, whether materials were applied to dentin or not. Adhesives (3-step etch-and-rinse/3ER: OptiBond FL; 2-step self-etch/2SE Clearfil SE Bond; Single Bond Universal/UNI), composites (conventional composite resin/CCR: Filtek Z350XT; flowable/FCR: Filtek Z350XT Flow; self-adhesive composite resin/SACR: Dyad Flow), and luting agents (conventional luting agent/CLA: Variolink-II; self-adhesive luting agent/SLA: RelyXU200) were combined according to their clinical use. Eluates from polymerized specimens applied to dentin were placed in contact with cells grown for 1 and 7 d. The controls were defined by cells without material contact. Cell viability was determined using MTT [3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide)] assay. C=C conversion was investigated using Fourier-transform infrared spectroscopy. After 1 d of incubation, when dentin was not present, 2SE yielded the highest cell viability, whereas 3ER, UNI, and SACR showed higher cell viability in the presence of dentin. After 7 d, when dentin was absent, 2SE and CLA achieved significantly higher cell viability. The presence of dentin resulted in a drastically higher cell viability for all materials, except 2SE and CLA. UNI had the lowest C=C conversion. The presence of dentin was a significant factor, which resulted in higher cell viability than what was seen for the material specimens per se. All materials resulted in a lower viability of HaCaT than what was seen under the no-material control conditions, with effects mainly limited to the first 24 h.

Heating and preheating of dental restorative materials-a systematic review.

OBJECTIVES: To perform a review on the influence of preheating and/or heating of resinous and ionomeric materials on their physical and mechanical properties and to discuss the benefits and methods of preheating/heating that have been used. MATERIAL AND METHODS: A search was performed in the Pubmed, Scopus, Scielo, and gray literature databases. In vitro studies published from 1980 until now were searched using the descriptors "composite resins OR glass ionomer cements OR resin cements OR adhesives AND heating OR preheating." Data extraction and quality of work evaluation were performed by two independent evaluators. RESULTS: At the end of reading the search titles and abstracts, 74 articles were selected. Preheating of composite resins reduces viscosity, facilitates adaptation to cavity preparation walls, increases the degree of conversion, and decreases the polymerization shrinkage. Preheating of resin cements improves strength, adhesion, and degree of conversion. Dental adhesives showed good results such as higher bond strength to dentin. However, unlike resinous materials, ionomeric materials have an increase in viscosity upon heating. CONCLUSIONS: Preheating improves the mechanical and physical properties. However, there is a lack of clinical studies to confirm the advantages of preheating technique. CLINICAL RELEVANCE: Preheating of dental restorative materials is a simple, safe, and successful technique. In order to achieve good results, agility and training are necessary so the material would not lose heat until the restorative procedure. Also, care is necessary to avoid bubbles and formation of gaps, which compromises the best restoration performance.

[Comparison of residual cement between CAD/CAM customized abutments and stock abutments via digital measurement in vitro].

OBJECTIVE: To compare the residual cement between computer aided design/computer aided manufacturing customized abutments (CCA) and stock abutments (SA), and to evaluate the feasibility of digital measurement for residual cement volume by three-dimensional scanning. METHODS: Twenty master models needed in this study were all taken from one 47-year-old patient with arrested periodontitis, who had already had an implant placed at his right upper central incisor site in the Department of Periodonto-logy, Peking University School and Hospital of Stomatology. After 4 weeks of soft tissue conditioning by means of customized healing abutment, the height of peri-implant soft tissue was measured, from the implant platform to mucosal margin, as 5 mm. Using customized impression coping, the impression was taken and twenty models were fabricated and allocated to 4 groups according to the type of abutments: CCA1 (5 mm transmucosal height CCA, with margin at tissue level), CCA2 (4 mm transmucosal height CCA, with 1 mm submucosal margin), SA1 (3 mm transmucosal height SA, with 2 mm submucosal margin) and SA2 (1 mm transmucosal height SA, with 4 mm submucosal margin). Crowns were cemented to the abutments, which were seated on the working models. Excess cement was removed by a prosthodontic specialist. Thereafter, the volume of residual cement was evaluated by using three-dimensional scanning technique. The area proportion of residual cement was calculated on photographs taken by a single lens reflex camera. The weight of residual cement was weighed by an analytical balance. And the correlation of residual cement volume data with residual cement area proportion or weight of residual cement acquired by traditional methods was analyzed. RESULTS: Residual cement was observed on all the experiment samples. The residual cement volume of CCA was significantly less than that of SA [(0.635 3±0.535 4) mm3 vs. (2.293 8±0.943 8) mm3, P < 0.001]. Consistently, CCA had less residual cement area proportion and weight than those of SA [area proportion: 7.57%±2.99% vs. 22.68%±10.06%, P < 0.001; weight: (0.001 5±0.001 0) g vs. (0.003 7±0.001 4) g, P < 0.001]. The residual cement volume was strongly correlated with the residual cement area proportion and residual cement weight (r>0.75, P < 0.001). CONCLUSION: These in vitro results suggest that CCA minimized the residual cement more effectively than SA. The method to digitally evaluate the residual cement volume is feasible, but its validity and reliability need to be further studied.

Effect of Thickness of Ceramic Veneers on Color Stability and Bond Strength of Resin Luting Cements Containing Alternative Photoinitiators.

PURPOSE: To evaluate the light transmittance of ceramic veneers of different thicknesses and verify their influence on the degree of conversion, color stability, and dentin bond strength of light-curing resin cements containing different photoinitiator systems. MATERIALS AND METHODS: Experimental resin cements were fabricated containing camphorquinone and amine (CQ-amine), TPO, Ivocerin (IVO), or TPO and Ivocerin (TPO-IVO). All photoinitiators were characterized by UV-Vis spectrophotometry. Disk-shaped lithium disilicate ceramic specimens that were 0.4, 0.7, and 1.5 mm in thickness were prepared using IPS e.max Press (Ivoclar Vivadent, shade LT/A2). Light transmittance through each specimen was measured using spectrophotometry. Specimens of each cement (n = 10) were made in a custom-designed mold and were light cured through each glass-ceramic disk using a multiwave LED (Bluephase G2, Ivoclar Vivadent). CS was evaluated using spectrophotometry before and after artificial aging with UV light. DC was evaluated using FTIR-spectroscopy. Dentin µSBS was evaluated using 0.75-mm-thick specimens that were light cured under the same protocol (n = 10). All data were submitted to two-way ANOVA and Tukey's test (α = 0.05; ß = 0.2). RESULTS: CQ-amine cements showed the highest color changes (p < 0.05) due to increased yellowing when compared to the amine-free cements (p < 0.05). However, all cements showed a significant color change after aging when cured through ceramics up to 1.5 mm thick (p < 0.05). The TPO-IVO cement showed the highest DC and the IVO cement showed a similar DC when compared to the CQ-amine cement. The TPO cement presented the lowest DC (p = 0.0377). No differences in mean dentin µSBS were found among the cements, except for the TPO cement, which presented a lower mean dentin µSBS (p = 0.0277). CONCLUSION: Amine-free cements containing Ivocerin and TPO seem to be a better alternative to CQ-amine cements, while not reducing either DC or dentin µSBS of amine-free cements. However, CQ-amine and amine-free cements still seem to change color over time.

Physical Properties, Film Thickness, and Bond Strengths of Resin-Modified Glass Ionomer Cements According to Their Delivery Method.

PURPOSE: To determine the effect of changing the dispensing or mixing method of resin-modified glass ionomer (RMGI) cements on their water sorption, solubility, film thickness, and shear bond strength. MATERIALS AND METHODS: Disc-shaped specimens of RMGI cements (RelyX: Luting [handmix], Luting Plus [clicker-handmix], Luting Plus [automix], GC: Fuji PLUS [capsule-automix], FujiCEM 2 [automix], [n = 10]) were prepared according to ISO standard 4049 for water sorption and solubility tests. Furthermore, the percentage of mass change, percentage of solubility, and percentage of water absorbed was also determined. Film thickness was measured according to ISO standard 9917-2; the mean of 5 measurements for each cement was calculated. Shear bond strength for each cement was determined according to ISO standard 29022 before and after thermocycling at 20,000 cycles, temperatures 5 to 55°C with a 15-second dwell time (n = 10/subgroup). Two- and one-way ANOVA were used to analyze data for statistical significance (p < 0.05). RESULTS: Water sorptions of the RMGI cements were in close range (214-250 µg/mm3 ) with no statistical differences between counterparts (p > 0.05). RelyX Luting Plus (clicker-handmix) displayed lower solubility than its handmix and automix counterparts (p < 0.05). Film thickness of RelyX cements was significantly different (p < 0.05). RelyX Luting Plus (automix) had the lowest film thickness (19 µm) compared to its handmix (48 µm) and clicker-handmix (117 µm) counterparts (p < 0.05). GC Fuji PLUS (capsule-automix, 22 µm) was significantly lower than the automix version (GC FujiCEM 2, 127 µm) (p < 0.05). Shear bond strength of RelyX Luting Plus (automix) was significantly lower than its handmix and clicker-handmix versions (p < 0.05). GC Fuji PLUS (capsule-automix) was significantly higher than GC FujiCEM 2 (automix) (p < 0.05). The binary interaction of the two independent variables (dispensing/mixing method and thermocycling) was significant for the shear bond strengths of the GC cements only (p < 0.05). CONCLUSIONS: Change in the dispensing/mixing method of RMGI cement from the same brand may have an effect on its physical properties, in addition to its film thickness and shear bond strength. Newer, easier, and faster cement delivery systems are not necessarily better. Clinical outcomes of these differences are yet to be confirmed.

The Effect of CAD/CAM Crown Material and Cement Type on Retention to Implant Abutments.

PURPOSE: To evaluate the pullout resistance of CAD/CAM implant-supported crowns cemented with provisional and definitive cements on Ti-base implant abutments. MATERIALS AND METHODS: Sixty crowns were milled for use in Ti-base implant abutments and divided (n = 15/group) according to material, as follows: (a) [Pr] Temporary acrylic resin; (b) [Co-Cr] Cobalt-Chromium alloy; (c) [Zr] polycrystalline zirconia; and (d) [Ti] titanium. The cementation was performed with RelyX Temp NE (RxT) cement or RelyX U200 self-etching resin cement, under a 50 N (5 kg) load for 10 minutes. Twenty-four hours after cementation, the crowns were subjected to the pullout test in a universal test machine, at a 1.0 mm/min crosshead speed. The tests were performed first without cement to evaluate frictional resistance (Baseline), then with provisional cement (RelyX Temp NE without cement again (Baseline After RxT), and finally with resin cement (U200). The results were analyzed by ANOVA and Tukey test (p < 0.05). RESULTS: Data evaluation as a function of cement type demonstrated the superiority of resin-based cements relative to provisional and baseline groups (p < 0.01). While Co-Cr crowns presented the highest pullout strength values, Pr showed the lowest values (data collapsed over cement) (p < 0.001). Retentiveness data as a function of both factors demonstrated similar pullout resistance between groups without cement (p < 0.001), except Zr baseline. Also, Co-Cr presented higher pullout strength compared to other materials. CONCLUSIONS: Self-adhesive resin cement exhibited superior retention compared to temporary cement, regardless of crown material. Co-Cr and titanium presented higher levels of retention to Ti-base abutment after being cemented.

Dislodgment Resistance of Bioceramic and Epoxy Sealers: A Systematic Review and Meta-analysis.

OBJECTIVES: The aim of the present systematic review was to evaluate if epoxy resin-based root canal sealers present superior push-out bond strength compared to calcium silicate-based root canal sealers. METHODS: The inclusion criteria consisted of in vitro studies that compared the push-out bond strength of epoxy resin-based and calcium silicate-based sealers. A systematic search was performed in the following databases for articles published until February 2018: PubMed, ScienceDirect, Scopus, Web of Science, and OpenGrey. The quality assessment and data extraction of the selected articles were performed. A meta-analysis of the pooled data and the subgroups according to the root thirds was carried out using the RevMan software (P < .05). RESULTS: The search resulted in 2292 studies. After the duplicate studies were removed and the title and abstract were read, 20 studies were selected and 17 were considered as having a low risk of bias. The pooled meta-analysis comparing epoxy resin-based (n = 467) and paste-to-paste calcium silicate-based root canal sealers (n = 467) demonstrated higher mean push-out bond strength values (P < .001) for the epoxy resin-based root canal sealers; the heterogeneity among studies was 85% (I2). The comparisons between epoxy resin-based (n = 358) and premixed ready-to-use calcium silicate-based root canal sealers (n = 358) also demonstrated a significant difference between the sealers (P < .05), with an I2 of 95%. The subgroup analysis showed that only in the middle third, were increased bond strength values for epoxy resin-based sealer observed (P < .001), with an I2 of 94%. CONCLUSIONS: The epoxy resin-based sealer demonstratedhigher push-out bond strength than paste-to-paste calcium silicate-based root canal sealer regardless of the root third assessed. In addition, the epoxy resin-based sealer exhibited increased push-out bond strength in comparison with premixed ready-to-use calcium silicate-based root canal sealer when evaluating the middle third.

In vivo biocompatibility and biomineralization of calcium silicate cements.

A new mineral trioxide aggregate (MTA) material has been developed with a modified composition that requires investigations to support its clinical use. This study evaluated the biocompatibility and biomineralization of this new MTA material and compared it with that of two other MTA cements over time. Tubes containing materials (or empty tubes as controls) were inserted into the subcutaneous tissues of 40 rats. On days 7, 15, 30, 60, and 90, the tubes were removed with the surrounding tissues, which were either stained with haematoxylin and eosin or von Kossa for further analyses or unstained for observation under polarized light. On days 7 and 15, moderate inflammation was observed in most specimens, and the fibrous capsule was thick. On day 30, there was mild inflammation in all groups, and the fibrous capsule was thin. On days 60 and 90, there was mild inflammation in the material groups, while the control group showed no inflammation, although no statistically significant difference between the groups was observed and the fibrous capsule was thin. All material groups showed structures that stained with von Kossa and could be observed under polarized light; this was not found for the control. In conclusion, the new MTA material had biocompatibility and biomineralization properties similar to those of the two existing MTA materials.

The influence of the emergence profile on the amount of undetected cement excess after delivery of cement-retained implant reconstructions.

OBJECTIVE: To test whether or not one of two emergence profile designs (concave or convex) is superior to the other in terms of remaining cement following cementation of reconstructions on individualized abutments and careful cement removal. MATERIALS AND METHODS: A central incisor with a single implant-supported reconstruction was selected as a model. Six types of abutments (n = 10) with two different emergence profile designs (concave (CC) and convex (CV)) and three crown-abutment margin depths (epimucosal, 1.5 mm submucosal, 3 mm submucosal) were fabricated through a CAD/CAM procedure. Lithium disilicate reinforced ceramic crowns were cemented with chemically polymerized resin cement. A blinded investigator attempted to remove all cement excess. Thereafter, the entire reconstruction was unscrewed and analyzed for the overall amount and the depth of cement excess. Kruskal-Wallis and Mann-Whitney tests were used to investigate differences between groups. When more than two groups were compared between each other, a Bonferroni correction of the P value was performed. RESULTS: Concave abutments presented significantly more cement remnants than CV abutments when the entire abutment area of the epimucosal margin groups was evaluated (CC0 mm: mean 2.31 mm2 (SD 0.99) vs. CV0 mm: mean 1.57 mm2 (SD 0.55); P = 0.043). A statistically significant increase in remnants was detected when the crown-abutment margin was located more submucosally for every abutment studied (0 mm vs. 1.5 mm: P < 0.000, 0 mm vs 3 mm: P < 0.000, 1.5 mm vs. 3 mm: P < 0.000). The buccal quadrant demonstrated the least, whereas the oral and interdental quadrants showed the greatest amount of cement excess. CONCLUSIONS: Concave emergence profile abutments and deep crown-abutment margin positions increased the risk of cement excess. Oral and interdental areas are more prone to cement remnants than other surface areas.