This laboratory study aimed to evaluate the effects of zirconium dioxide (ZrO2) slurry surface treatment on the bond strength of ultratranslucent zirconia to resin cement using different ceramic primers. The surface morphology was evaluated by scanning electron microscopy (SEM) and atomic force microscopy (AFM), and the interface was evaluated by SEM. Additionally, the phase composition was analyzed by X-ray diffraction (XRD). Specimens of zirconia (n=120) were obtained and divided into two groups according to the surface treatment: (1) airborne particle abrasion with 50-mu m aluminum oxide (n=60) and (2) ZrO2 slurry (n=60). The 60 specimens were then further divided into three groups (n=20) according to the ceramic primer application: no primer (NP), Monobond N (MB), and Clearfil ceramic primer (CP). Four resin cement cylinders were built on each ceramic specimen. Half of the specimens (n=10) were subjected to a microshear bond strength (mu SBS) test after 24 hours of storage in distilled water, and the other half (n=10) were subjected to a mu SBS test after thermocycling. Additional specimens were prepared for SEM, AFM, and XRD analyses. According to the Kruskal-Wallis and Student-Newman-Keuls post hoc tests, the mu SBS values were significantly higher for MB and CP than for NP (p<0.05), and there were no significant differences in mu SBS for both surface treatments associated with MB and CP after 24 hours of storage (p>0.05). Thermocycling significantly decreased the mu SBS values for all specimens, especially for the NP groups and ZrO2 slurry treatment groups, and gaps at the interface were observed by SEM. SEM and AFM analyses showed agglomerate-type irregularities on the ceramic surface for ZrO2 slurry treatment. XRD spectra showed that ZrO2 slurry did not cause phase transformation. It was concluded that ZrO2 slurry promoted irregularities on the ultratranslucent zirconia surface, not causing phase transformation; moreover, the values of mu SBS were comparable to those of airborne particle abrasion with aluminum oxide. However, neither surface treatment nor ceramic primer prevented the degradation of the interface.

OBJECTIVE:This study compares the physical properties and clinical performance of short fiber reinforced composites (SFRC) to those of particulate-filled resin-based composites (PFRC) for class I and II direct restorations in permanent dentition.METHODS:Systematic review and meta-analysis was conducted using PubMed, Embase (Elsevier), and Dentistry and Oral Sciences Source (EBSCO) databases. The outcomes evaluated were physical properties including flexural strength, flexural modulus, elastic modulus, microhardness, shrinkage, fracture toughness, degree of conversion, and depth of cure. Clinical performance was evaluated with a systematic review.RESULTS:The meta-analyses favored SFRC for flexural strength and fracture toughness compared to every PFRC subgroup, with a high quality of evidence. For all other properties, the meta-analyses favored SFRC to overall PFRC, with some non-significant differences with certain PFRC subgroups. The most recent clinical trial showed SFRC performed similarly to PFRC, however older studies suggest inferior surface texture and discoloration of SFRC compared to PFRC.CONCLUSION:This study can aid dental professionals in clinical decision making, supporting that SFRC offers improved physical properties, especially fracture resistance and flexural strength, compared to PFRC.

Objectives: To investigate the influence of curing distance on the degree of conversion (DC) of a resin-based composite (RBC) when similar radiant exposure was achieved using six different light-curing units (LCUs) and to explore the correlation among irradiance, radiant exposure, and DC. Methods and Materials: A managing accurate resin curing-resin calibrator system was used to collect irradiance data for both top and bottom specimen surfaces with a curing distance of 2 mm and 8 mm while targeting a consistent top surface radiant exposure. Square nanohybrid-dual-photoinitiator RBC specimens (5 x 5 X 2 mm) were cured at each distance (n=6/LCU/distance). Irradiance and DC (micro-Raman spectroscopy) were determined for the top and bottom surfaces. The effect of distance and LCU on irradiance, radiant exposure, and DC as well as their linear associations were analyzed using analysis of variance and Pearson correlation coefficients, respectively (alpha=0.05). Results: While maintaining a similar radiant exposure, each LCU exhibited distinctive patterns in decreased irradiance and increased curing time. No significant differences in DC values (63.21%-70.28%) were observed between the 2- and 8-mm distances, except for a multiple-emission peak LCU. Significant differences in DC were detected among the LCUs. As expected, irradiance and radiant exposure were significantly lower on the bottom surfaces. However, a strong correlation between irradiance and radiant exposure did not necessarily result in a strong correlation with DC. Conclusions: The RBC exhibited DC values >63% when the top surface radiant exposure was maintained, although the same values were not reached for all lights. A moderatestrong correlation existed among irradiance, radiant exposure, and DC.

OBJECTIVES::To evaluate 1) the internal adaptation of a light-activated incremental-fill and bulk-fill resin-based composite (RBC) materials by measuring the gap between the restorative material and the tooth structure and 2) the aging effect on internal adaptation.METHODS AND MATERIALS::Seventy teeth with class I cavity preparations were randomly distributed into five groups; four groups were restored with bulk-fill RBCs: Tetric EvoCeram Bulk Fill (TEC), SonicFill (SF), QuiXX Posterior Restorative (QX), and X-tra fil (XF); the fifth group was restored with incremental-fill Filtek Supreme Ultra Universal Restorative (FSU). One-half of the specimens of each group were thermocycled. Each tooth was sectioned, digital images were recorded, and the dimensions of any existing gaps were measured. Data were analyzed using analysis of variance (α=0.05).RESULTS::FSU had the smallest gap measurement values compared with the bulk-fill materials except QX and TEC ( p≤0.008). FSU had the smallest sum of all gap category values compared with the bulk-fill materials, except QX ( p≤0.021). The highest gap incidence and size values were found at the composite/adhesive interface. All aged groups had greater gap values in regard to the gap measurement and the sum of all gap categories compared with non-aged groups.SIGNIFICANCE::The incrementally placed material FSU had the highest internal adaptation to the cavity surface, while the four bulk-fill materials showed varied results. Thermocycling influenced the existing gap area magnitudes. The findings suggest that the incremental-fill technique produces better internal adaptation than the bulk-fill technique.

What is a general dentist, anyway? Today, my answer includes at least three parts and is biased by what I have experienced in the United States: 1) we had at least a tangible idea of how to answer this question over the past 50 years or so; 2) we have little idea of what the answer will be 10 to 20 years from now; and 3) the question is critical as dental education grapples with its purpose and function. As I think back over my clinical career as a general dentist, I ask myself, “Why am I in academic dentistry today?” After 16 years of full-time practice, I joined the world of full-time academic dentistry in 2000. Several factors contributed to my making the change. Among those, I did not like the way insurance companies were driving us further and further toward a procedure-driven mentality instead of a total-patient care mentality. I believe there is no way to win the battle against this pressure if we do not lay the groundwork with our students. I find this battle has not become easier, yet I still believe it to be key to what a general dentist will be in the years to come.During my years in academics, I have often heard discussion about the evils of procedure-driven graduation requirements. Procedures become education currency, and this creates a numbers game that drives students away from a total-patient care mind-set, just as it can for private practitioners. And on the other side of the argument is the understanding that without an adequate number of procedures, students do not gain the surgical skills needed to predictably provide the care needed for our patients. Twenty years ago, there was a significant push in dental education away from discipline-based departments. Many schools created mega-departments with the belief that this would enhance our ability to provide total-patient care and decrease emphasis on procedures. But what goes around, often comes around, and some of those mega-departments have been deconstructed back into discipline-based departments where numbers can still reign. What does that mean for the training of our students and for the direction of our profession?If someone had told me 30 years ago that, before my career was over, dental students would no longer be able to replace missing canines as a matter of routine, I would have truly thought that they had lost their mind. But that is the state of our world. In one sense, this is a result of our success. Many procedures that were commonplace during the majority of my career are no longer so. Oral disease has not been eradicated, but the utilization of dental care has been changing.1,2 During the last quarter of the 20th century, many successful dental practices were based on the endodontic and prosthodontic needs of all segments of the population. As overall dental health has improved for the upper and middle classes, we now find a greater percentage of restorative needs in the lower socioeconomic class and the geriatric population. This is challenging our system and, therefore, the reality of what a general dentist will actually be. We need to figure out how to respond.In the practice world, one response has been the growth of larger group- and corporate-owned practices. Yes, there are other factors that contribute to this, but I would suggest that the need to increase volume to maintain desired cash-flow levels is one of the contributing factors. A large amount of the disease that needs to be treated exists in a portion of the population that does not have the financial resources to pay for that treatment. A basic understanding of economics suggests that this negative pressure on fees will lead toward a need for increased volume. This also puts added stress on dental education as we traditionally think about it. You see, some of these patients are those that used to frequent dental school clinics to take advantage of a reduced fee schedule. Now, many school fees are not so reduced, and if these patients pursue care, they may do so for similar or marginally higher fees without having to invest the large amount of time that the educational environment has traditionally demanded.In academics, I believe we are largely kicking this challenge down the road. In some institutions, this may be tied to the reemergence of discipline-based clinics, at least for early clinical experiences. I believe these clinics help calibrate early clinical experiences and solidify basic concepts. But even as this occurs, more procedures are being handed to residents, while fewer procedures are available for pre-doctoral students. I have heard it argued that residents in prosthodontics and the increased number of operative dentistry programs are finishing their training with levels of restorative experience somewhat comparable to what pre-doctoral students had 30 years ago. And our pre-doctoral students are graduating with the hope that they will find some way to pay their debts. What is it that we truly expect them to do?Part of the current environment is the increased number of training programs in operative dentistry that we now see in the United States. For most of my career, there were four such programs. Today, the number is now in double digits. I contend that these and other advanced training and postgraduate year 1 programs will become more important for the next era of dentistry as traditional pre-doctoral programs are less and less able to provide the repetitions beyond competency essential to the training of our next generation of clinicians.Isn't it time to embrace our reality? I see some progress with the growth of interprofessional education—working with teams of other health care providers in an educational environment. Oral health is an integral part of total health. We must embrace our role as oral health care providers; we contribute to the overall health of the people who come to see us. A dental career that thrives on the traditional restorative approaches of our past is becoming more and more difficult to achieve and, educationally, is being driven into the hands of a fewer number of well-trained practitioners.Where does that leave the general dentist of the future? When leaving dental school, more advanced training may be a necessity for each new graduate. If so, that training should be available in the graduate's desired area of emphasis. In addition, new dentists must leave school understanding that they are overseeing total oral health care that is a critical component of the overall health of their patients. Knowing how to guide treatment for each patient should be at the core of a general dentist's activity. In this issue of Operative Dentistry, you will find an invited article from last February's Academy of Operative Dentistry Buonocore lecturer, Falk Schwendicke.3 Its content should stimulate thought.So, why did I jump to academic dentistry? Toward the top of the list of reasons was the desire to help students think less about procedure-driven care and more about total-patient care. What do I see today? Dental education is struggling to cope with what total-patient oral health care looks like in a world where traditional dental diseases do not have a great enough prevalence in the right populations to support all of the dentists being trained, at least not in our historical way of thinking. This in the midst of a remuneration system that demands surgical procedures be accomplished to pay off debt and earn a living. We are at a crossroads, and great leadership is needed to guide us through this period of change.

The present study investigated the effect of three high-viscosity bulk-fill resin-based composite materials on cuspal deflection in natural teeth. Thirty-two sound maxillary premolar teeth with large slot mesio-occlusal-distal cavities were distributed into four groups (n=8). Three groups were restored with bulk-fill resin composite materials (Tetric EvoCeram Bulk Fill, Ivoclar Vivadent, Schaan, Liechtenstein; x-tra fil, VOCO, Cuxhaven, Germany; and SonicFill, Kerr, Orange, CA, USA) in a single 4-mm increment. The conventional composite group, Filtek Z100 (3M ESPE, St Paul, MN, USA), was used to restore the cavities in 2-mm increments. Cusp deflection was recorded postirradiation using a Nikon measurescope UM-2 (Nikon, Tokyo, Japan) by measuring the changes in the bucco-palatal widths of the teeth at five minutes, 24 hours, and 48 hours after completion of the restorations. Cuspal deflection was significantly higher in the conventional composite than in the Tetric EvoCeram Bulk Fill ( p=0.0031), x-tra fil ( p=0.0029), and SonicFill Bulk ( p=0.0002) groups. There were no significant differences in cuspal deflection among the three bulk-fill materials (all p<0.05). In conclusion, all the investigated bulk-fill resin composites exhibited cuspal deflection values that were smaller than those associated with a conventional incrementally placed resin composite.

This study aimed to compare the effect of two concentrations of triple antibiotic paste (TAP) with or without ethylenediaminetetraacetic acid (EDTA) on surface loss and surface roughness of radicular dentine. Human radicular dentine specimens were randomized into six experimental groups (n = 16 per group). The first and second groups were treated with 1,000 mg/mL or 1 mg/mL of TAP for 4 weeks. The third and fourth groups were treated with 1,000 mg/mL or 1 mg/mL of TAP for 4 weeks followed by 17 % EDTA for 5 min. The fifth group was treated with 17 % EDTA for 5 min and the sixth group received no treatment (control). Dentine surface loss and surface roughness were quantified after various treatments using optical and contact profilometry, respectively. One-way ANOVA followed by Fisher's protected least significant differences was used for statistical analyses. All treatment groups showed significantly higher surface loss compared to the untreated dentine. Dentine treated with 1,000 mg/mL had significant increase in surface loss and surface roughness compared to dentine treated with 1 mg/mL of TAP. The use of EDTA after both concentrations of TAP did not have significant additive effect on surface loss and surface roughness of dentine. The clinically used concentration of TAP (1,000 mg/mL) caused significantly higher surface loss and surface roughness of radicular dentine compared to the use of 1 mg/mL of TAP. Furthermore, the substantial amount of dentine surface loss and surface roughness detected in the current study may be attributed to TAP rather than EDTA.

The purpose of this study was to evaluate the influence of direct base and indirect inlay materials on stress distribution and fracture resistance of endodontically treated premolars with weakened cusps. Forty healthy human premolars were selected; five were left intact as controls (group C+), and the others were subjected to endodontic treatment and removal of buccal and lingual cusp dentin. Five teeth were left as negative controls (group C-). The remaining 30 teeth were divided into two groups according to the direct base material (glass ionomer [GIC] or composite resin [CR]). After base placement, each group was subjected to extensive inlay preparation, and then three subgroups were created (n=5): no inlay restoration (GIC and CR), restored with an indirect composite resin inlay (GIC+IR and CR+IR), and restored with a ceramic inlay (GIC+C and CR+C). Each specimen was loaded until fracture in a universal testing machine. For finite element analysis, the results showed that the removal of tooth structure significantly affected fracture resistance. The lowest values were presented by the negative control group, followed by the restored and based groups (not statistically different from each other) and all lower than the positive control group. In finite element analysis, the stress concentration was lower in the restored tooth compared to the tooth without restoration, whereas in the restored teeth, the stress concentration was similar, regardless of the material used for the base or restoration. It can be concluded that the inlay materials combined with a base showed similar behavior and were not able to regain the strength of intact tooth structure.

The dental scientific literature is being challenged as a rapidly increasing number of “peer-reviewed” journals strains the ability of the qualified reviewer pool to meet the demand. (In 2014, Thomas Reuters Journal Citation Reports assigned an Impact Factor for 88 dental journals. Five years earlier, they rated only 64.) In addition to this expanding group of traditional publications is a large number of recently introduced online journals. Just as with print journals, online publications demonstrate a wide range of scientific rigor and review. Some of them deserve and are receiving support from reviewers.Significant changes are also occurring within the reviewer pool. In some places in the world, such as the United States, the number of tenured and tenure-track faculty has greatly decreased. It is this group which has provided significant peer-review support over the past decades. Many of the recently hired younger faculty come on board as clinical track faculty with little incentive to be involved with research and the peer review process. Oftentimes, the new faculty have minimal previous research experience and no desire to participate as reviewers.These factors (increasing journals and decreasing reviewers) result in fewer people being asked to carry a greater load in providing peer review oversight of our literature. When I gather with other editors, a common topic of conversation is the shortage of qualified and willing reviewers. Clearly, the future of peer review, and how it is accomplished, is being challenged. Thankfully, Operative Dentistry continues to benefit from the dedicated service of a large number of volunteer reviewers who provide important feedback for the authors of manuscripts to improve the content and presentation of information. Reviewers also provide critical information for the editor as ultimate publication decisions are made for each article. Of the 504 articles submitted to this journal over the past year, a total of 120 articles were accepted. Each article had at least two reviewers who worked with the authors and the editorial team to improve, and then approve the submission. To be done well, this task requires significant effort and a commitment to excellence.I remain extremely grateful to the group of scientists and clinicians who provide this critical service. What follows is a list of people who have provided reviews for us over the past year. I thank each one of them. And you, as a reader of Operative Dentistry, if you know any of these people, give them your thanks as well. They are a committed group of volunteers working diligently to maintain the integrity of peer review!

This study assessed marginal leakage and fracture resistance of computer-aided design/computer-aided manufacturing (CAD/CAM) fabricated ceramic crowns with intracoronal extensions into the pulp chambers of endodontically treated teeth (endocrowns) using either feldspathic porcelain (CEREC Blocks [CB], Sirona Dental Systems GmbH, Bensheim, Germany), lithium disilicate (e.max [EX], Ivoclar Vivadent, Schaan, Liechtenstein), or resin nanoceramic (Lava Ultimate [LU], 3M ESPE, St Paul, MN, USA).). Thirty extracted human permanent maxillary molars were endodontically treated. Standardized preparations were done with 2-mm intracoronal extensions of the endocrowns into the pulp chamber. Teeth were divided into three groups (n=10); each group was restored with standardized CAD/CAM fabricated endocrowns using one of the three tested materials. After cementation with resin cement, specimens were stored in distilled water at 37°C for one week, subjected to thermocycling, and immersed in a 5% methylene-blue dye solution for 24 hours. A compressive load was applied at 35 degrees to long axis of the teeth using a universal testing machine until failure. Failure load was recorded, and specimens were examined under a stereomicroscope for modes of failure and microleakage. Results were analyzed using one-way analysis of variance and Bonferroni post hoc multiple comparison tests (α=0.05). LU showed significantly (p<0.05) higher fracture resistance and more favorable fracture mode (ie, fracture of the endocrown without fracture of tooth) as well as higher dye penetration than CB and EX. In conclusion, although using resin nanoceramic blocks for fabrication of endocrowns may result in better fracture resistance and a more favorable fracture mode than other investigated ceramic blocks, more microleakage may be expected with this material.

OBJECTIVE:We examined the influence of light intensity on surface free energy characteristics and dentin bond strength of dual-cure direct core build-up resin systems.METHODS:Two commercially available dual-cure direct core build-up resin systems, Clearfil DC Core Automix with Clearfil Bond SE One and UniFil Core EM with Self-Etching Bond, were studied. Bovine mandibular incisors were mounted in acrylic resin and the facial dentin surfaces were wet ground on 600-grit silicon carbide paper. Adhesives were applied to dentin surfaces and cured with light intensities of 0 (no irradiation), 200, 400, and 600 mW/cm(2). The surface free energy of the adhesives (five samples per group) was determined by measuring the contact angles of three test liquids placed on the cured adhesives. To determine the strength of the dentin bond, the core build-up resin pastes were condensed into the mold on the adhesive-treated dentin surfaces according to the methods described for the surface free energy measurement. The resin pastes were cured with the same light intensities as those used for the adhesives. Ten specimens per group were stored in water maintained at 37°C for 24 hours, after which they were shear tested at a crosshead speed of 1.0 mm/minute in a universal testing machine. Two-way analysis of variance (ANOVA) and a Tukey-Kramer test were performed, with the significance level set at 0.05.RESULTS:The surface free energies of the adhesive-treated dentin surfaces decreased with an increase in the light intensity of the curing unit. Two-way ANOVA revealed that the type of core build-up system and the light intensity significantly influence the bond strength, although there was no significant interaction between the two factors. The highest bond strengths were achieved when the resin pastes were cured with the strongest light intensity for all the core build-up systems. When polymerized with a light intensity of 200 mW/cm(2) or less, significantly lower bond strengths were observed. CONClUSIONS: The data suggest that the dentin bond strength of core build-up systems are still affected by the light intensity of the curing unit, which is based on the surface free energy of the adhesives. On the basis of the results and limitations of the test conditions used in this study, it appears that a light intensity of >400 mW/cm(2) may be required for achieving the optimal dentin bond strength.

This article presents details of fabrication, biological activity ( i.e., anti–matrix metalloproteinase [anti-MMP] inhibition), cytocompatibility, and bonding characteristics to dentin of a unique doxycycline (DOX)–encapsulated halloysite nanotube (HNT)–modified adhesive. We tested the hypothesis that the release of DOX from the DOX-encapsulated nanotube-modified adhesive can effectively inhibit MMP activity. We incorporated nanotubes, encapsulated or not with DOX, into the adhesive resin of a commercially available bonding system (Scotchbond Multi-Purpose [SBMP]). The following groups were tested: unmodified SBMP (control), SBMP with nanotubes (HNT), and DOX-encapsulated nanotube-modified adhesive (HNT+DOX). Changes in degree of conversion (DC) and microtensile bond strength were evaluated. Cytotoxicity was examined on human dental pulp stem cells (hDPSCs). To prove the successful encapsulation of DOX within the adhesives—but, more important, to support the hypothesis that the HNT+DOX adhesive would release DOX at subantimicrobial levels—we tested the antimicrobial activity of synthesized adhesives and the DOX-containing eluates against Streptococcus mutans through agar diffusion assays. Anti-MMP properties were assessed via β-casein cleavage assays. Increasing curing times (10, 20, 40 sec) led to increased DC values. There were no statistically significant differences ( p > .05) in DC within each increasing curing time between the modified adhesives compared to SBMP. No statistically significant differences in microtensile bond strength were noted. None of the adhesives eluates were cytotoxic to the human dental pulp stem cells. A significant growth inhibition of S. mutans by direct contact illustrates successful encapsulation of DOX into the experimental adhesive. More important, DOX-containing eluates promoted inhibition of MMP-1 activity when compared to the control. Collectively, our findings provide a solid background for further testing of encapsulated MMP inhibitors into the synthesis of therapeutic adhesives that may enhance the longevity of hybrid layers and the overall clinical performance of adhesively bonded resin composite restorations.

Although there is strong evidence for the effectiveness of sealants, one major barrier in sealant utilization is the concern of sealing over active caries lesions. This study evaluated detection and monitoring of caries lesions through a clear sealant over 44 mo. Sixty-four 7- to 10-year-old children with at least 2 permanent molars with International Caries Detection and Assessment System (ICDAS) scores 0-4 (and caries less than halfway through the dentin, radiographically) were examined with ICDAS, DIAGNOdent, and quantitative light-induced fluorescence (QLF) before sealant placement and 1, 12, 24, and 44 mo (except QLF) after. Bitewing radiographs were taken yearly. DIAGNOdent and QLF were able to distinguish between baseline ICDAS before and after sealant placement. There was no significant evidence of ICDAS progression at 12 mo, but there was small evidence of minor increases at 24 and 44 mo (14% and 14%, respectively) with only 2% ICDAS ≥ 5. Additionally, there was little evidence of radiographic progression (at 12 mo = 1%, 24 mo = 3%, and 44 mo = 9%). Sealant retention rates were excellent at 12 mo = 89%, 24 mo = 78%, and 44 mo = 70%. The small risk of sealant repair increased significantly as baseline ICDAS, DIAGNOdent, and QLF values increased. However, regardless of lesion severity, sealants were 100% effective at 12 mo and 98% effective over 44 mo in managing occlusal surfaces at ICDAS 0-4 (i.e., only 4 of 228 teeth progressed to ICDAS ≥ 5 associated with sealants in need of repair and none to halfway or more through the dentin, radiographically). This study suggests that occlusal surfaces without frank cavitation (ICDAS 0-4) that are sealed with a clear sealant can be monitored with ICDAS, QLF, or DIAGNOdent, which may aid in predicting the need for sealant repair.

The present study assessed the polymerization shrinkage stress kinetics of five low-shrinkage light-cured bulk-fill resin composites: Surefil SDR flow (SF, Dentsply), Tetric EvoCeram Bulkfil (TE, Ivoclar Vivadent), Venus Bulk Fill (VB, Heraeus Kulzer), x-tra fil (XF, Voco), and experimental bulk fill (FB, 3M ESPE). Filtek Z250 (FZ, 3M ESPE) was used as a control. Real-time shrinkage stress of investigated composites was measured using a tensometer; maximum shrinkage stress, stress rate (Rmax), and time to reach maximum stress rate (tmax) were recorded. Flexural strength and modulus were measured using a standard procedure, and curing efficiency of 4-mm long specimens was determined using bottom/top percentage Knoop microhardness. Data were analyzed using one-way analysis of variance and Bonferroni multiple range tests at a significance level of α=0.05. Results of shrinkage stress, Rmax, and tmax of all bulk-fill materials were significantly lower (p<0.05) than those of the control except for XF. All tested bulk-fill materials were able to achieve acceptable curing efficiency (≥80% bottom/top percentage) at 4-mm depth. In conclusion, this study reports a significant reduction in polymerization shrinkage stress while maintaining comparable curing efficiency at 4 mm for some bulk-fill composites and supports their potential use in posterior clinical situations.