Is Conventional Resin Cement Adhesive Performance to Dentin Better Than Self-adhesive? A Systematic Review and Meta-Analysis of Laboratory Studies

Contemporary Concepts of Adhesive Cementation of Glass-Fiber Posts: A Narrative Review

(1) Background: Cementation of glass fiber posts to root canals has been associated with various failures, especially debonding. This narrative review aims to present the contemporary concepts concerning the adhesive cementation of glass fiber post and to discuss the optimal management of these factors. (2) Methods: Electronic search was performed in MEDLINE/Pub Med and Google Scholar using selected keywords examining the parameters post length, surface treatment of glass fiber posts, post space preparation and dentin pretreatment, resin cement selection, adhesive systems and hybrid layer formation, and clinical techniques. (3) Results: The search led to the selection of 44 articles. Epoxy resin-based endodontic sealers are recommended and the use of temporary cement in the root canal should be avoided. The minimum length of a glass fiber post adhesively cemented to a root canal is 5 mm. Irrigating the root canals with chlorhexidine, MTAD, or EDTA (alone or in combination with NaOCl) after post space preparation seems to enhance the bond strength. Silane application on the surface of the post seems to be beneficial. Concerning resin cements and adhesive systems, the results were rather inconclusive. Finally, resin cement should be applied inside the root canal with an elongation tip and photoactivation should be delayed. (4) Conclusions: Contemporary concepts of adhesive cementation of glass fiber posts can indeed improve the bond between glass fiber posts, resin cement, and root canal dentin, however, evidence coming from long-term randomized prospective clinical trials is needed in order to obtain safer conclusions.

Medium-term evaluation of the bond strength and dentin penetration of self-adhesive resin cements to root dentin

BACKGROUND

Medium-term evaluate the bond strength and tag formation in root dentin using self-adhesive cements Maxcem Elite (MCE), Relyx U200 (RU2), SeT PP (SPP) and Megalink (MGL) compared to conventional cement Relyx ARC (ARC) for glass fibre post cementation.

MATERIALS AND METHODS

One hundred bovine incisors roots were endodontically treated and divided into 5 groups (n = 20) according to the cementation system: MCE, RU2, SPP, MGL and ARC. All cementation systems were evaluated at 24 h (1) and 12 months (2) after post cementation. Specimens from the cervical, middle and apical thirds of the root were submitted to push-out bond strength test and confocal laser microscopy to verify the dentin penetration. The adhesive failure mode was classified as adhesive, cohesive and mixed. Data were analysed by one-way ANOVA and Tukey tests (α = 5%).

RESULTS

ARC-1 and ARC-12 showed the highest bond strength (P < 0.05). ARC showed the greatest tag extension, regardless of the third (P < 0.05). The most frequent failure mode in the 24-h analysis was cohesive, regardless of the cement used. For the 12-month analysis, mixed failure was the most frequent.

CONCLUSION

Conventional cement (ARC) showed the highest bond strength and tag extension, regardless of the evaluation period. In all cementation systems, the bond strength decreased after 12 months. © 2023 Australian Dental Association.

Self-adhesive resin cement versus conventional cements on the failure rate of indirect single-tooth restorations: A systematic review and meta-analysis of randomized clinical trials

STATEMENT OF PROBLEM

Cementation is one of the most critical steps that influence the failure rates of indirect restorations. Self-adhesive resin cements arose out of the need for technical simplification of this procedure to reduce the risk of operative errors, with good acceptance by clinicians. How the failure rate of indirect single-tooth restorations cemented with self-adhesive resin cements compares with the failure rate of those cemented conventionally is unclear.

PURPOSE

The purpose of this systematic review and meta-analysis of randomized clinical trials was to compare self-adhesive resin cements versus conventional cements on the failure rates of indirect restorations.

MATERIAL AND METHODS

The review was registered at the International Prospective Register of Systematic Reviews (PROSPERO - CRD42020215577). The search strategy was adapted for 5 databases (PubMed, The Cochrane Library, EMBASE, Web of Science, and LILACS) and 1 nonpeer-reviewed literature source (clinicaltrials.gov). The strategy was guided by the problem/population, intervention, comparison, outcome (PICO) question: adults indicated for indirect restorations -P, self-adhesive resin cement -I, conventional cement-C, failure rates-O. The risk of bias was assessed using the Cochrane risk of bias (RoB2) tool and guidelines. Meta-analysis merged the results from included studies by pooling the hazard ratios and standard errors, available or estimated. The certainty of evidence was assessed by using the classification of recommendations, evaluation, development, and evaluation (GRADE) approach.

RESULTS

Nine randomized clinical trials were included in qualitative and quantitative analysis. Eight studies detected nonsignificant differences in failure rates between cements. Only 1 study reported a significantly higher failure rate on single-tooth ceramic crowns luted with self-adhesive resin cement. Nonsignificant differences were detected after the results from all studies had been pooled.

CONCLUSIONS

Based on clinical evidence, self-adhesive resin cements can be recommended for the cementation of indirect single-tooth restorations with a similar risk of failure to conventional cements.

Scanning electron microscopy observation of dentin bond interfaces in different types of resin luting cements

This study aimed to observe and compare the resin luting cement (RLC)/dentin interfaces of different types of RLC systems with scanning electron microscopy (SEM). This study evaluated six self-adhesive resin luting cement systems (SARLCs), four systems combining a SARLC with a tooth primer (SARLCPs), and six conventional resin luting cement systems (CVRLCs). Cured resin composite rods were bonded to bovine dentin using RLCs in different etching modes. The morphological features at the interfaces were observed using SEM. Although all RLCs in etch-&-rinse (ER) mode showed a clear hybrid layer, most SARLCs had a thinner and more porous hybrid layer than the SARLCPs and CVRLCs. All SARLCPs with primer and CVRLCs showed a thin high-density layer below the primer layer in both etching modes. CVRLCs and SARLCPs with primer treatment systems may be more versatile and reliable when compared to simplified RLC systems.

Effect of Immediate Dentin Sealing on the Bonding Performance of Indirect Restorations: A Systematic Review

The popular immediate dentin sealing (IDS) technique is used to improve the bond strength of indirect restorations. This systematic review assessed whether bond strength is affected by the type of aging conditions, bonding agents, flowable resin composites, impression materials, temporary materials, and/or resin cement used within the IDS procedure. A comprehensive database search of PubMed, Embase, Scopus, Ovid Medline, Web of Sciences, Cochrane Library, Dentistry & Oral Sciences Source, and ProQuest was carried out up to 30 January 2024 without publication year or language limitations. Only in vitro full-texts regarding the effect of IDS on bond strength were included, and the quality of their methods was assessed via a Risk of Bias (RoB) test. In total, 1023 pertinent studies were initially found, and 60 articles were selected for review after screening for the title, abstract, and full texts. IDS application improves the bond strength of indirect restorations to dentin and reduces the negative effects of temporary materials on the bond durability of final indirect restorations. Filled dentin bonding agents or combinations with flowable resin composite are preferred to protect the IDS layer from conditioning procedures.

Comparing Various Resin Luting Cement Systems in Different Etching Modes Through Bond Durability and Morphological Features

OBJECTIVES

This study aimed to investigate bond performance of various resin luting cement (RLC) systems on enamel and dentin in different etching modes and to compare the RLC-tooth interface morphology using scanning electron microscopy (SEM).

METHODS AND MATERIALS

The self-adhesive RLC systems used in combination with universal adhesives were as follows: Scotchbond Universal Adhesive Plus + RelyX Universal (3M Oral Care) and Clearfil Universal Bond Quick ER + SA Luting Multi (Kuraray Noritake Dental). These RLC systems were also used alone as self-adhesive RLC systems without universal adhesives (self-adhesive mode). The conventional RLC systems for comparison materials were as follows: BeautiBond Xtream + ResiCem EX (Shofu) and Tooth Primer + Panavia V5 (Kuraray Noritake Dental). Twelve specimens were prepared for each group to measure shear bond strength (SBS) in different etching modes. A stainless-steel rod was used as a substitute for indirect restorations. Bonded specimens were allocated to baseline (stored for 24 hours) and artificially aged (thermocycling [TC] for 10,000 cycles) groups. Representative treated tooth surfaces and RLC-tooth interfaces were observed using SEM.

RESULTS

Three-way analysis of variance (ANOVA) revealed that all the factors (etching mode, storage period, and RLC system) had a significant influence on the enamel SBS values (p<0.05). Enamel SBS was significantly higher in etch-&-rinse (ER) mode than in self-etch (SE) mode, regardless of RLC system or storage period. Three-way ANOVA showed that all the factors had a significant influence on the dentin SBS values (p<0.001). Most RLC systems showed significantly higher dentin SBS in SE mode than in ER mode, regardless of storage period. However, the combination with Scotchbond Universal Adhesive Plus and RelyX Universal showed no significant difference in SBS values between etching modes at the baseline and showed a significantly higher SBS value in ER mode than in SE mode after TC.

CONCLUSIONS

The self-adhesive RLC systems with universal adhesives tended to show higher enamel and dentin bond performance than the self-adhesive RLC systems alone. The morphology of treated tooth surfaces and resin cement-tooth interfaces were dependent on the RLC system and etching mode used. The RLC systems with primer application showed a thin, high-density layer above the intact dentin in both etching modes, suggesting chemical interaction.

A comprehensive review of resin luting agents: Bonding mechanisms and polymerisation reactions

The field of dentistry is constantly evolving and increasingly embracing minimally invasive approaches. One such approach, which is bonding to the tooth structure, particularly enamel, has been shown to offer the most predictable outcomes. However, there are instances where significant tooth loss may limit treatment options for a restorative dentist. In these scenarios, indirect restoration might be the preferred treatment option. This literature review provides a comprehensive examination of the currently available resin luting agents and their bonding requirements. It provides valuable insights for dental professionals seeking an in-depth understanding of the current state of the field and the future prospects of dental adhesion.

Influence of different curing modes on the bonding effectiveness of self-adhesive resin luting cements in combination with universal adhesives

OBJECTIVES

This study aimed to investigate the immediate dentin bond performance and bond durability of self-adhesive resin luting cements (RLCs) in combination with universal adhesives in different curing modes.

METHODS

Two self-adhesive RLCs were used with universal adhesives as primers. They were also used alone as self-adhesive RLCs. Two multiple-step RLC systems were used as comparison materials. To measure the shear bond strength (SBS) in different curing modes, 12 specimens were prepared for each group. Stainless-steel rods were bonded to bovine dentin, and the bonded specimens were assigned to the baseline group (stored for 24 h) and artificially aged group (thermal cycling [TC], 10,000 cycles). After each storage period, the SBS of the bonded specimens was measured. The Knoop hardness number (KHN) of the cured RLCs was measured with or without primer application in different curing modes at 24 h and after 10,000 TC. The representative RLC/dentin interfaces were observed using scanning electron microscopy (SEM).

RESULTS

Dentin SBS was significantly influenced by the RLC system but not by the curing mode. Self-adhesive RLCs alone showed significantly lower SBS values than self-adhesive RLCs with primer regardless of the curing mode or storage period. The storage period, curing mode, and RLC system significantly influenced the KHN.

SIGNIFICANCE

The use of universal adhesives as a primer may help enhance the immediate dentin bond performance and bond durability of self-adhesive RLCs.

Bond Strength of a Novel Universal Resin Cement to Dentin with or without an Adhesive Bonding Agent: An In Vitro Study

AIM

The purpose of this study was to evaluate the bond strength and fracture mode of universal resin cement to dentin compared to self-adhesive and adhesive resin cement with and without an adhesive bonding agent.

MATERIALS AND METHODS

Seventy-two molar teeth were sectioned to expose coronal dentin, divided into three groups, and assigned to RelyX Universal (universal), RelyX Ultimate (adhesive), or RelyX Unicem 2 (self-adhesive) cements from 3M. The 3 groups were further subdivided into 2 subgroups of 12 specimens each, with or without the use of an adhesive bonding agent. Lithium-disilicate discs were bonded to the dentin surface using the cements, stored for 24 hours in distilled water, and subjected to 2,000 thermocycles before shear bond strength testing and fracture mode analysis.

RESULTS

Significant differences in bond strength and fracture mode were found between groups based on cement or the use of a bonding agent. Both the universal and adhesive cements had significantly greater bond strengths to dentin with the use of a bonding agent versus no bonding agent. With the self-adhesive cement, there was no significant increase in bond strength to dentin with the use of a bonding agent.

CONCLUSION

The novel universal resin cement had similar bond strengths to dentin as the adhesive cement with the use of a bonding agent, and similar bond strengths as the self-adhesive cement without the use of a bonding agent. The adhesively bonded universal cement had the greatest percentage of mixed and cohesive fractures.

CLINICAL SIGNIFICANCE

When greater adhesion is needed clinically, the novel universal resin cement may be used with an adhesive bonding agent. However, when less adhesion is needed, it could be used without a bonding agent in self-adhesive mode.

Resin composite cements: Current status and a novel classification proposal

OBJECTIVES

Currently, a classification of resin cements that includes relatively recently formulated ("universal") cements is lacking. Furthermore, the terminology used to define different resin cements in the scientific reports is inconsistent. Accordingly, this work aims to: (i) propose a novel classification of resin composite cements; (ii) disambiguate the term "universal cements" and (iii) present an overview of the properties of these cements.

METHODS

An analysis of peer-reviewed literature (PubMed search), as well as market research on definitive resin composite cements were performed.

RESULTS

A tendency toward simplified and versatile luting materials was observed both in the scientific literature and on the dental market with the advent of self-adhesive/one-step resin cements. However, additional priming procedures were necessary to improve their bonding performance in certain clinical situations. Hence, several cements that can be applied both in adhesive and self-adhesive mode were introduced. These cements are associated with a universal adhesive resin, that can be used as a tooth and/or restorative material primer, without the need for other priming systems, regardless of the substrate. These systems should be considered truly universal. Therefore, we hereby suggested a new classification of resin-based cements: (1) adhesive/multi-step; (2) self-adhesive/one-step; (3) universal cements (one- or multi-step). Despite promising in vitro results, clinical trials and long-track laboratory studies are necessary to confirm the reliability of the universal cements.

CONCLUSIONS

This review presented the current advances in the field of resin-based cements, which are reflected in the proposed classification. The term "universal cement" was disambiguated, which will help standardize the terminology used in published research.

CLINICAL SIGNIFICANCE

The classification of resin-based cements and a better understanding of the proper terminology will help standardize the terminology in published research, as well as improve the understanding of the clinical practitioners of the different indications and possible modalities of use of the available cements.

Selective adhesive luting: A novel technique for improving adhesion achieved by universal resin cements

OBJECTIVE

We aimed to introduce the concept of "Selective adhesive luting-SAL" which is explained through clinical steps and supported by preliminary laboratory evidence.

CLINICAL CONSIDERATIONS

Cementation with rubber dam is difficult to perform in case of short abutment teeth and/or subgingival crown margins. By means of universal resin cements/universal adhesive systems, which can be employed in self-adhesive as well as adhesive luting procedures, this paper presents a novel technique allowing clinicians to perform reliable cementation where rubber dam isolation is difficult. The SAL technique entails the application of a universal adhesive system only on easily accessible abutment surfaces, enabling simultaneous adhesive and self-adhesive luting in different portions of the abutment. The SAL clinical workflow is explained through prosthodontic rehabilitation of maxillary right central incisor affected by microdontia and restored with a lithium-disilicate crown. Furthermore, our laboratory microshear bond strength study supports the rationale behind SAL application demonstrating higher bond strength even when the adhesive resin is placed only on one portion of the cementation substrate.

CLINICAL SIGNIFICANCE

This article advocates the application of SAL technique in clinical situations where effective adhesive luting is uncertain, since it can improve the adhesion between the tooth and universal resin cements.

Evaluation of Bond Strength and Fracture Load of Teeth With Flared Root Canals Restored With Prefabricated, Anatomical, and Computer-aided Design and Computer-aided Manufacturing Fiber Posts

PURPOSE

This study compared the use of anatomical glass fiber posts using bulk-fill composite resin with computer-aided design and computer-aided manufacturing (CAD/CAM) milled glass fiber post in oversized root canals, through bond strength (BS) and fracture resistance (FR) tests (fracture load).

METHODS AND MATERIALS

A total of 48 mandibular premolars were selected, half of them had their crowns removed at the cemento-enamel junction (CEJ) and the other half were sectioned 2 mm above the CEJ. Subsequently, teeth were endodontically treated. After 1 week, the standard preparation of the canals was carried out, and the roots were divided into three groups (n=16), according to the use of different restorative techniques (control: prefabricated glass fiber post [PFP], direct anatomical glass fiber post [AFP], and CAD/CAM milled glass fiber post [MFP]). After luting procedures using Single Bond Universal and RelyX Ultimate (3M ESPE), for eight teeth in each group, six specimens were obtained (two slices from each root third: cervical, middle, and apical). For the remaining eight roots of each group, standardized preparations for metal-free crowns, milling of 5 mol% yttria-stabilized tetragonal zirconia polycrystalline, cementation of the crowns, and periodontal ligament simulation were performed. Then, for each group, the BS was evaluated through the push-out test, and the FR was evaluated in compression. The data obtained from BS were submitted to two-way analysis of variance (ANOVA; group vs root region) and Tukey (α=0.05) and from FR to one-way ANOVA (group) and Tukey (α=0.05).

RESULTS

For the BS test, the MFP group was statistically superior to the PFP group in all root regions and was statistically superior to the AFP group only in the cervical region, being statistically similar in the middle and apical root regions. For the FR test, the MFP group was statistically superior to the PFP and AFP groups.

CONCLUSION

The milled fiber post technique can be a legitimate alternative in the restoration of weakened roots with flared root canals.

Survival rate and treatment success of glass fiber posts cemented with two adhesive cementation strategies after up to 106 months: a randomized clinical trial

OBJECTIVES

The objective of this study is to evaluate the longevity of two fiber post cementation strategies in a prospective, multicenter, non-inferiority, double-blind randomized controlled trial.

METHODS

A total of 152 teeth, with adequate endodontic treatment and loss of coronal structure and bilateral simultaneous posterior occlusal contacts, were randomly allocated to receive glass fiber posts cemented with a conventional cementation strategy (CRC group: adhesive system + resin cement) (Adper Single Bond + RelyX ARC; 3 M-ESPE) or a self-adhesive cementation strategy (SRC group: self-adhesive resin cement; RelyX U100/U200; 3 M-ESPE). The patients were recalled annually for clinical and radiographical evaluation with a 93% recall rate (142 teeth, with 74 at CR groups and 68 at SRC group). The primary outcome was survival rate, considering the fiber post debonding (loss of retention). The secondary outcome included the success rate of the prosthetic treatment with crown debonding, post fracture, and tooth loss (not related to post failure). Both outcomes were evaluated annually. The Kaplan-Meier method and Cox regression with 95% confidence interval were used for the statistical analysis.

RESULTS

For the primary outcome (failures directly related to fiber posts cementation strategy), there were 4 fiber post debondings (2 per group), 8 root fractures (3 for SRC group and 5 for CRC group), and one mixed failure (debonding combined with root fracture for CRC), with both strategies presenting similar survival rates (p = 0.331), with 88.9% for the CRC group and 90.9% for the SRC group. For the secondary outcome (failures not related to fiber post cementation strategies), there were 8 crown debondings, 3 post fractures, and 3 tooth losses, with no statistically difference between groups (p = 0.701), with 77% for SRC and 82% for CRC.

CONCLUSION

Fiber post cementation strategies with conventional or self-adhesive resin cement presents similar tooth survival and success rates.

TRIAL REGISTRATION

NCT01461239 CLINICAL RELEVANCE: Both adhesive cementation strategies led to high survival and success rates and are indicated for fiber post cementation, even after a long follow-up period (up to 106 months).

Longevity of metal-ceramic single crowns cemented onto resin composite prosthetic cores with self-adhesive resin cement: an update of a prospective analysis with up to 106 months of follow-up

OBJECTIVES

To evaluate the longevity of metal-ceramic single crowns cemented onto resin composite prosthetic cores using a self-adhesive resin cement in a prospective clinical descriptive study.

METHODS

A total of 152 teeth were endodontically treated and received resin composite prosthetic cores and metal-ceramic crowns cemented with a self-adhesive resin cement. The patients included in the sample were recalled for clinical and radiography evaluation in an up-to-106-month period after the final cementation procedures, with an average of 62 months of follow-up. 91.5% of the sample (142 teeth) were evaluated regarding the treatment survival rate, analyzed considering the loss of crown retention (crown debonding) and tooth loss as the primary outcome. In addition, post debonding, and root fracture occurrences were also recorded as secondary outcomes to evaluate the success rate of the prosthetic treatment. The aesthetic parameters were also evaluated according to the FDI criteria. The Kaplan-Meier method and Cox regression with 95% confidence interval were applied for the statistical analysis.

RESULTS

Regarding the primary outcome, the metal-ceramic crowns cemented with self-adhesive resin cement presented a high survival rate (91.5%), with 8 crown debondings and 3 tooth losses (1 due to caries and 2 due to periodontal disease) occurring after the evaluation period. For secondary outcomes, 9 root fractures and 4 post debondings occurred, generating a success rate of 72%. All crowns had a score 1 on the FDI criteria, indicating that they were clinically excellent or very good regarding the aesthetic parameters.

CONCLUSION

The metal-ceramic crowns luted with a self-adhesive resin cement presented a survival rate of 91.5% after an average of 62 months of follow-up. Furthermore, the restorations remained aesthetically satisfactory over time, without changes that would indicate prosthetic retreatment. A success rate of 72% was obtained considering the secondary outcome, mainly related to intraradicular retainer failures (root fractures or post debonding).

CLINICAL SIGNIFICANCE

The self-adhesive resin cement is clinically indicated for cementation of metal-ceramic crowns onto resin composite prosthetic cores.

Clinical reliability of self-adhesive luting resins compared to other adhesive procedures: A systematic review and meta-analysis

OBJECTIVES

This systematic review aimed to collect and interpret the randomized clinical trials (RCTs) that investigated the outcome of the self-adhesive luting resins (SA) compared to total-etch (TE), selective etch with dentin adhesives (Sle), selective etch without dentin adhesives (SleSA) or self-etch adhesives (SE).

DATA SOURCES

A thorough search of Internet databases was conducted without language restrictions, and the search ran up to and including April 2022. The illegible records citations were checked for more relevant clinical studies.

STUDY SELECTION/RESULTS

The inclusion criteria were randomized controlled trials (RCTs) that compared self-adhesive luting resins with total-etch, selective-etch, or self-etch adhesives regarding postoperative sensitivity, incidences of debonding, and survival rates of indirect restorations. From 1732 records, 9 RCTs met the eligibility criteria. Three RCTs compared total-etch adhesive to self-adhesive luting resin for intracoronal restorations, one RCT compared selective etch to self-adhesive luting resin for inlays, and 5 RCTs compared self-adhesive to other protocols for partial ceramic crowns. Postoperative sensitivity showed a non-statistically significant difference between SA and other adhesive protocols, SA revealed a non-statistically significant difference in debonding and survival to TE, but a lower statistically significant difference to Sle, SleSA, and SE.

CONCLUSIONS

Postoperative sensitivity might not be affected by the adhesive protocol. In relatively short observation, TE revealed comparable survival to SA for intracoronal restorations. SE and Sle exhibited the best clinical outcomes, followed by SleSA. Selective etch, and self-etch adhesives are preferable to self-adhesive resins.

CLINICAL SIGNIFICANCE

The significance of enamel etching and the superiority of self-etching adhesives over self-adhesive luting resins for reliable and durable bonding and improved clinical outcomes. However, long-term RCTs, particularly for total-etch comparison to self-adhesive luting resins, might be recommended to derive further evidence.

Update on Dental Luting Materials

A dental luting material aids in the retention and stability of indirect restorations on the prepared tooth structure. In dentistry, clinicians are using a wide range of luting materials for the cementation of indirect restorations. Zinc oxide eugenol and non-eugenol cements, zinc phosphate cement, zinc polycarboxylate cement, glass ionomer cement and resin cements are common dental cements used in dentistry. Each luting material or cement possesses unique properties and clinical implications. An ideal luting cement should be biocompatible, insoluble, resistant to thermal and chemical assaults, antibacterial, aesthetic, simple and easy to use. It should have high strength properties under tension, shear and compression to resist stress at the restoration-tooth interface, as well as adequate working and setting times. So far, no luting material possesses all of these properties of an ideal cement. Scientists have been modifying the conventional luting cements to improve the material's clinical performance and developing novel materials for clinical use. To achieve the best clinical outcome, clinicians should update their knowledge and gain a good understanding of the luting materials so that they can make a wise clinical decision on the material selection and obtain an insight into the development of luting cements. Therefore, the objective of this study is to provide a discussion on the physical, chemical, adhesive and aesthetic properties of common luting materials. The clinical indications of these luting materials are suggested based on their properties. In addition, overviews of the modification of the conventional luting materials and the newly developed luting materials are provided.

HASTABAŞI CAD-CAM BLOKLARIN EROZE DENTİNE MAKASLAMA BAĞLANMA DAYANIMI

Amaç: Bu çalışmada hastabaşı bilgisayar destekli tasarım-bilgisayar destekli üretim (CAD-CAM) bloklarının self-etch ve self-adeziv rezin simanlar kullanılarak gastrik erozyona uğratılmış dentine olan makaslama bağlanma dayanımlarının değerlendirilmesi amaçlanmıştır. Gereç ve Yöntemler: Yüz seksen dentin örneği sağlam dentin ve eroze dentin olmak üzere iki gruba ayrılmıştır. Eroze dentin grubunda örnekler HCI (0,01 M, pH 2, 2 dk) ile erozyona uğratılmış ve 60 dk yapay tükrükte bekletilmiş, sonrasında, elektrikli diş fırçası kullanılarak (2N, 15 s) fırçalanmıştır. Bu döngü üç kere tekrar edilmiştir. Lava Ultimate (LU), Vita Enamic (VE) ve Vita Suprinity (VS) CAD-CAM blokları (3x3x3 mm3, n=15/grup) self-etch Multilink N (MN) ve self-adeziv RelyX U200 Automix (RU) rezin simanları kullanılarak sağlam ve eroze dentin örneklerine simante edilmiştir. Makaslama bağlanma dayanımı 24 saat sonra ölçülmüştür. Başarısızlık tipi stereomikroskop kullanılarak değerlendirilmiştir. Veriler üç-yönlü ANOVA ve Bonferroni düzeltmesi kullanılarak analiz edilmiştir (p˂0,05). Bulgular: Makaslama bağlanma dayanımı ana faktörlerden önemli ölçüde etkilenmiştir: diş yapısı (p=0,011), rezin simanlar (p˂0,001) ve CAD-CAM bloklar (p=0,001). LU sağlam dentine RU ile simante edildiğinde, eroze dentinle karşılaştırıldığında daha yüksek bağlanma dayanımı elde edilmiştir (p=0,001). MN kullanıldığında, RU’dan daha yüksek bağlanma dayanımı değerleri elde edilmiştir (p

Impact of Immediate and Delayed Photo-activation of Self-adhesive Resin Cements on Bonding Efficacy and Water Uptake Under Simulated Pulpal Pressure

This study investigated the effect of immediate versus delayed photo-activation on the bonding performance and water uptake of self-adhesive (SA) resin cements under simulated pulpal pressure (SPP). The occlusal dentin surface was exposed in 66 extracted third molars. Resin composite cylinders were cemented to dentin under SPP, with either RelyX Unicem 2 (RU) (3M Oral Care, St Paul, MN, USA) or Maxcem Elite (MC) (Kerr, Orange, CA, USA). Each cement group was equally divided into three groups (n=8 each) according to the time elapsed between placement and photo-activation: immediate activation (IM), 30-second delayed activation (D30), or 120-second delayed activation (D120). Shear bond strength (SBS) was measured, and the type of failure was determined using a stereomicroscope. Three additional samples from each experimental subgroup were used for confocal laser scanning microscopy (CLSM) analysis. A fluorescent dye solution was added to the pulpal fluid reservoir, then a CLSM was used to detect the dye distribution within the tooth-restoration interface. Two-way analysis of variance (ANOVA) and the Tukey post-hoc test were used to analyze the SBS results (α=0.05). D30 resulted in a significantly higher mean SBS in the two cement groups than IM and D120 (p<0.05). RU showed significantly higher SBS values than MC regardless of the time of light activation (p<0.05). RU showed less dye uptake confined to the cement-dentin interface compared to the MC groups, which showed dye uptake throughout the entire thickness of the cement layer and gap formation at the interface, especially in the D120 group. The 30-second photo-activation delay group significantly improved the bond strength of SA cements. Delaying the photo-activation to 120 seconds increased pulpal fluid uptake by SA cements and compromised the integrity of the bonded interfaces.

The Effect of Different Abrasives on the Shear Bond Strength of Adhesive Resin Cements to Dentin

Aim:

The aim of this study was to evaluate the influence of dentin surface preparation with coarse diamond, extra-fine diamond, and polishing discs on the shear bond strength (SBS) of two resin cements (RCs) to dentin.

Materials and Methods:

Sixty-six recently extracted human mandibular third molar teeth that were free of cracks, caries, or restorations were collected. Sixty teeth were used for the SBS test. The occlusal part of the crowns was cut to expose mid-coronal dentin. The teeth were divided into three dentin preparation groups: coarse diamond (Meisinger, Germany), extra-fine diamond, and polishing discs (SofLex, 3MESPE, USA), and further conventional RC combined with a self-etch adhesive (Panavia F2.0/ED Primer II, Kuraray, Japan) or self-adhesive RC (Maxcem Elite, Kerr, USA) subgroups ( n = 10). Sixty composite resin blocks were prepared (diameter: 3 mm, height: 4 mm) and bonded to the teeth according to the groups. The SBS test was performed with a universal testing device. Six teeth were used for the observation of prepared dentin surfaces and the resin–cement dentin interfaces using field emission scanning electron microscopy (Mira 3 XMU, Tescan). Statistical analyses were performed using the Mann–Whitney U and Kruskal–Wallis tests ( P < .05).

Results:

Panavia F2.0/ED Primer II exhibited significantly higher SBS values for coarse and extra-fine diamond than for the polishing discs ( P <.05). Regarding Maxcem Elite, no significant difference was observed for the preparation methods ( P > .05). Panavia F2.0/ED Primer II had higher bond strength than Maxcem Elite for the dentin surface prepared with the coarse diamond ( P <.05). The differences were not significant for the extra-fine diamond and the polishing disc groups ( P > .05).

Conclusion:

The use of polishing discs did not increase the SBS of the RCs to the dentin.

Comparison of the Mechanical Properties and Push-out Bond Strength of Self-adhesive and Conventional Resin Cements on Fiber Post Cementation

OBJECTIVES

The purpose of this study was to compare the mechanical properties and push-out bond strength of self-adhesive resin cements (SACs) and a conventional resin cement (CRC).

METHODS AND MATERIALS

Eighty bovine incisors were divided into four groups for cementation of a fiberglass post (Whitepost - FGM Dental Group, Coral Springs, FL) with different resin cements: three SACs (Maxcem Elite, MAX - Kerr; Calibra Universal, CAL - Dentsply; and RelyX Unicem 2, RUN - 3M Oral Care) and one CRC (RelyX Ultimate, RXU - 3M Oral Care). The groups were subdivided into two groups each (n=10) for evaluation of the push-out bond strength test (POBS) after 24 hours of water storage or after thermal aging (5000 cycles), following 24 hours of storage. The failure modes were evaluated using a stereomicroscope. Flexural strength (FS) and modulus of elasticity (EM) were determined using a three-point bending. Also, pH of the cements was measured over 48 hours and filler morphology was observed by scanning electron microscopy. Appropriate statistical analyses were performed by SPSS 21.0 (SPSS Inc., Chicago, IL, USA), with a significance level set at 5%. Results: RXU presented the highest POBS at both evaluation times. Among the SACs, RUN and CAL presented significantly lower POBS than MAX in cervical and middle-thirds at the 24-hour evaluation, and in all root regions after thermocycling. Adhesive failure between the cement and dentin were the most prevalent fractures at both times evaluated. MAX presented the lowest FS and RUN showed the highest EM. The pH reached the minimal point at the 30-minute evaluation for RXU and MAX. For RUN and CAL, the minimal pH was observed at the 60-minute evaluation. RXU and RUN presented spherical and regular filler particles, while MAX and CAL presented irregularly shaped and sized filler particles.

CONCLUSIONS

The mechanical behavior of SACs is not superior to CRC; however, among all the SACs evaluated, MAX presented the highest POBS and stability after thermocycling evaluation. MAX also reached the closest neutral pH after 48 hours. Therefore, SACs with low initial pH and strong neutralization reactions are recommended, because these characteristics may lead to better mechanical properties and stability.

Shear bond strength of resin bonded zirconia and lithium disilicate - effect of surface treatment of ceramics and dentin

Objectives:The purpose of the study was to investigate the effect of ceramic surface pretreatment, effect of resin cement and dentin surface roughness on shear bond strength.

Methodology: Zirconia rods (n = 140) were randomly assigned to air born particle abrasion with aluminum oxide (Al₂O₃) or hot etching with potassium hydrogen difluoride (KHF₂). Lithium disilicate rods (LDS; n = 50) etched with hydrofluoric acid served as reference material. In Part 1 of the study, ceramic rods were cemented to bovine dentin using 5 dual-polymerizing resin cements (Variolink Esthetic, Multilink Automix (Ivoclar Vivadent), Duo-Link (BISCO Dental), Panavia F2.0 (Kuraray Dental), RelyX Unicem (3 M)). Shear bond strength was tested and fracture morphology determined. In Part 2 of the study, test groups with the highest frequency of adhesive fractures between cement and dentin were selected for further bond strength testing with different surface roughness of dentin; ground with P1200 or P80 silicon carbide paper. Dentin samples were fractured vertically to the cemented surface and the adherence between cement and dentin was studied.

Results: The results of Part 1 showed that hot etching of zirconia significantly improved bond strength to Duo-Link cement. In Part 2, RelyX Unicem showed significantly higher bond strength to P1200 compared to P80 ground dentin. For Variolink Esthetic, bond strengths to P1200 and P80 ground dentin were similar. Adhesive fracture between cement and dentin dominated.

Conclusions: A smooth dentin surface (P1200) improved bond strength to RelyX Unicem. Surface roughness was not important for Variolink Esthetic.

Influence of inorganic composition and filler particle morphology on the mechanical properties of self-adhesive resin cements

Objectives

This study aimed to evaluate the influence of inorganic composition and filler particle morphology on the mechanical properties of different self-adhesive resin cements (SARCs).

Materials and Methods

Three SARCs including RelyX Unicem-2 (RUN), Maxcem Elite (MAX), and Calibra Universal (CAL) were tested. Rectangular bar-shaped specimens were prepared for flexural strength (FS) and flexural modulus (FM) and determined by a 3-point bending test. The Knoop microhardness (KHN) and top/bottom microhardness ratio (%KHN) were conducted on the top and bottom faces of disc-shaped samples. Sorption (Wsp) and solubility (Wsl) were evaluated after 24 hours of water immersion. Filler morphology was analyzed by scanning electron microscopy and X-ray energy dispersive spectroscopy (EDS). FS, FM, %KHN, Wsp, Wsl, and EDS results were submitted to 1-way analysis of variance and Tukey’s post-hoc test, and KHN also to paired t-test (α = 0.05).

Results

SARC-CAL presented the highest FS value, and SARC-RUN presented the highest FM. SARC-MAX and RUN showed the lowest Wsp and Wsl values. KHN values decreased from top to bottom and the SARCs did not differ statistically. Also, all resin cements presented carbon, aluminum, and silica in their composition. SARC-MAX and RUN showed irregular and splintered particles while CAL presented small and regular size particles.

Conclusions

A higher mechanical strength can be achieved by a reduced spread in grit size and the filler morphology can influence the KHN, as well as photoinitiators in the composition. Wsp and Wsl can be correlated with ions diffusion of inorganic particles.

Bonding Reactions of Dental Self-Adhesive Cements with Synthetic Hydroxyapatite as a Function of the Polymerization Protocol

Objectives

This study evaluated the influence of the cement composition and different polymerization protocols on the bonding chemical interaction of self-adhesive cements with synthetic hydroxyapatite.

Materials and Methods

Two commercial self-adhesive resin cements (RelyX U200 and Maxcem Elite) were selected, manipulated, mixed with hydroxyapatite dry powder (HAp), dispensed into molds, and distributed into three groups according to polymerization protocols: immediate photoactivation (IP); delayed photoactivation, 10 min self-curing and light-curing (DP); and chemical activation (CA, no light exposure). The detailed chemical information, at atomic scale, on the surface and deeper into the bulk of self-adhesive cement/hydroxyapatite mixtures was evaluated with X-ray photoelectron spectroscopy (XPS).

Results

Chemical elements were detected in both cements, such as Na, O, Ca, C, P, and Si. Other elements were detected in minor concentrations. RelyX U200 exhibited the most intense formation of calcium salts products when the cement/HAp mixtures were photoactivated (immediate or delayed). RelyX U200/HAp mixture under delayed photoactivation (DP) also exhibited higher binding energy between calcium moieties of the HAp and methacrylates in the cement. A higher energy difference in the interaction of HAp with the cement comparing the bulk and surface areas was observed when RelyX U200 underwent the delayed photoactivation protocol. Maxcem Elite exhibited an increased chemical reactivity when either chemically activated or immediately photoactivated and a higher binding energy of the carboxyl groups bonded to the calcium of HAp when chemically activated.

Conclusions

The interaction of cements with hydroxyapatite is chemical in nature and leads to the formation of calcium salts, which may favor better integrity and longevity of adhesive restorations. The polymerization protocol affects the chemical interaction in mixtures of self-adhesive cements and hydroxyapatite, influencing the formation of these salts and the establishment of intermolecular interactions between the HAp and the cements.

Effects of Immediate and Delayed Cementations for CAD/CAM Resin Block after Alumina Air Abrasion on Adhesion to Newly Developed Resin Cement

The purpose of this study was to evaluate the effect of one week of Computer-aided design/Computer-aided manufacturing (CAD/CAM) crown storage on the μTBS between resin cement and CAD/CAM resin composite blocks. The micro-tensile bond strength (μTBS) test groups were divided into 4 conditions. There are two types of CAD/CAM resin composite blocks, namely A block and P block (KATANA Avencia Block and KATANA Avencia P Block, Kuraray Noritake Dental, Tokyo, Japan) and two types of resin cements. Additionally, there are two curing methods (light cure and chemical cure) prior to the μTBS test—Immediate: cementation was performed immediately; Delay: cementation was conducted after one week of storage in air under laboratory conditions. The effect of Immediate and Delayed cementations were evaluated by a μTBS test, surface roughness measurements, light intensity measurements, water sorption measurements and Scanning electron microscope/Energy dispersive X-ray spectrometry (SEM/EDS) analysis. From the results of the μTBS test, we found that Delayed cementation showed significantly lower bond strength than that of Immediate cementation for both resin cements and both curing methods using A block. There was no significant difference between the two types of resin cements or two curing methods. Furthermore, water sorption of A block was significantly higher than that of P block. Within the limitations of this study, alumina air abrasion of CAD/CAM resin composite restorations should be performed immediately before bonding at the chairside to minimize the effect of humidity on bonding.

Assessment of Degree of Conversion and Knoop Microhardness of Different Resin Cementing Agents

Background:

There are still controversies in the literature as to which is the best resinous cementing agent. Due to this fact and the immense availability of types and brands of cementing agents, further studies are needed to evaluate the properties of these important dental materials.

Objective:

To assess the degree of monomer conversion (DC) and Knoop microhardness (KHN) of four resin cements: two conventional dual-cured resin cements (EnForce and RelyXARC); one self-etching cement (RelyXU100); and one chemically-activated cement (Cement-Post).

Methods:

20 Pieces were made to assess KHN, and 20 to assess DC (n = 5). The DC was analyzed using a Fourier-transform infrared spectrometer, and KHN of the base and the top of the pieces were assessed using the Future-Tech microhardness tester. The data of KHN were statistically analyzed by two-factor ANOVA, and data related to DC were analyzed by the Kruskal-Wallis non-parametric test. The analysis of the correlation between KHN and DC of the cementing agents was performed by linear regression.

Results:

Dual-cured cements exhibited lower average KHN values at the base than at the top of the pieces (p <0.05). The self-etching cement had a significantly higher average KHN value than the other assessed cements (p <0.05). The DC of the dual-cured cement did not differ (p >0.05). The chemically-activated cement exhibited the lowest averages of KHN and DC values (p <0.05). Linear regression analysis indicated a strong correlation between DC and KNH (p = 0.043; R2 = 0.96); however, a specific hardness value could not be correlated to a specific DC value.

Conclusion:

Preferably, dual-cured resin cements (conventional or self-etching) should be used. Chemically-activated resin cements should be avoided due to their lower averages of DC and KHN values.

Randomized clinical split-mouth study on the performance of CAD/CAM-partial ceramic crowns luted with a self-adhesive resin cement or a universal adhesive and a conventional resin cement after 39 months

Objectives To determine the clinical performance of partial ceramic crowns (PCCs) luted with a conventional resin cement combined with a universal adhesive without or with selective enamel etching or luted with a self-adhesive resin cement. Methods In a split-mouth design, each three CAD/CAM-PCCs (Vita Mark II, Cerec) were placed in 50 patients. Two PCCs were luted with a conventional resin cement (RelyX Ultimate) combined with a universal adhesive (Scotchbond Universal) without (SB-E) or with (SB+E) selective enamel etching. The third PCC was luted with a self-adhesive resin cement (RelyX Unicem 2; RXU). Chi-square tests (α≤0.05) were applied. Based on clinical failures (complete debonding or need for replacement of the restorations), Kaplan-Meier survival analysis was performed. Results 31 patients were evaluated clinically using FDI criteria at 39 months. Clinically acceptable results were detected over time, except for "fracture of material and retention" (inacceptable fractures and debondings). Within materials, statistically significant differences (p ≤ 0.003) between baseline and 39 months were found for "marginal adaptation" and "marginal staining". At 39-month, SB+E and SB-E showed significantly better results compared to RXU in "marginal adaptation"(p ≤ 0.021) and "marginal staining"(p ≤ 0.013). Kaplan-Meier analysis showed higher survival rates after 39 months for SB+E (96%) and SB-E (88%) compared to RXU (69%) with statistically significant differences between RXU vs. SB-E (p = 0.022) and RXU vs. SB+E (p ≤ 0.001). Conclusions After 39-months, PCCs luted with the self-adhesive resin cement exhibited a statistically significant inferior survival rate compared to restorations luted with the conventional resin cement combined with a universal adhesive without or with selective enamel etching. Clinical significance Currently, self-adhesive resin cements cannot be recommended for luting partial ceramic crowns. However, the standard adhesive luting procedure comprising a universal adhesive and luting composite yielded good clinical results for more than 3 years irrespectively of application of a selective enamel etching step.

Predictable bonding of adhesive indirect restorations: factors for success

Adhesive indirect restorations are a popular restorative treatment option. This article discusses the many factors that contribute to their successful adhesive cementation, including a review of how to surface treat and manage contaminants across the wide range of indirect materials available.

Critiques the current various adhesive strategies used by resin cements at the tooth tissue interface.

Describes how to prepare the fitting surface of a wide range of restorative materials for adhesive cementation.

Discusses how to mitigate against contaminants during the adhesive cementation process.

Micromorphology of the Adhesive Interface of Self-Adhesive Resin Cements to Enamel and Dentin

Interfaces between dentin, enamel and luting agents were characterized using low vacuum Scanning Electron Microscopy (SEM). After smear layer creation, one of three luting agents (RelyX Unicem 2, Clearfil SA Cement and Panavia F 2.0/ED Primer II) was applied on 60 enamel-dentin specimens and dual-cured or self-cured. Specimens were polished (Experiment 1) and subsequently demineralized and deproteinized (Experiment 2). Adhesive interfaces were analyzed (low vacuum SEM, ×3000). Presence of an interdiffusion zone, tag-like structures (dentin) and marginal gaps (enamel) were assessed. Non-parametrical tests (χ²-test, α = 0.05) were performed. The first null-hypothesis was that the adhesive interface micromorphology between enamel and dentin and self-adhesive resin cements (SARCs) is similar with conventional resin cement used with a self-etch adhesive (CRC+SE). The second null-hypothesis was that the micromorphology is not influenced by curing modes. Interdiffusion zones and tag-like structures (dentin) were observed more frequently for CRC+SE compared to SARCs. For each luting agent, there was a non-significant (p > 0.05) tendency for interdiffusion zone and tag-like structures detectable in more specimens after self-curing compared to dual-curing. Marginal gaps (enamel) were found only for SARCs. The first null-hypothesis was not rejected fully: Tag-like structures and interdiffusion zones in dentin were found for CRC+SE and SARCs. The second null-hypothesis was not rejected.