Bonding to industrial indirect composite blocks: A systematic review and meta-analysis

Survival and Complications of Partial Coverage Restorations on Posterior Teeth-A Systematic Review and Meta-Analysis

OBJECTIVE

To determine the clinical performance of partial coverage restorations (PCR) (onlays, occlusal veneers, and partial crowns) composed of different ceramic and ceramic-based materials to treat extended posterior defects.

MATERIALS AND METHODS

MEDLINE, Scopus, CENTRAL, ClinicalTrials.gov, and the International Clinical Trials Registry Platform were searched (inception-February 2024) for randomized controlled trials (RCT) comparing posterior PCRs composed of different ceramic and ceramic-based materials with a minimum follow-up of 1 year.

RESULTS

Six RCTs were included. Resin matrix ceramic (RMC) and lithium disilicate (LDS) restorations had a 3-year survival rate of 89.3% (95% CI 76.4-95.3) and 93.7% (95% CI 83.7-97.7), respectively, and leucite-reinforced glass ceramic (LRGC) restorations a range between 96.1% (95% CI 90.1-98.9) compared with RMC and 98.3% (95% CI 90.8-100) compared with LDS. After 1-3 years of follow-up, LDS slightly outperformed RMC on restoration failure and loss of retention (1.56 more failures and 1.78 more loss of retentions for RMC per 100 restoration-years [low certainty evidence]). No statistically significant differences between ceramic and ceramic-based materials were detected in short-term follow-up (1-3 years of follow-up). The long-term performance of posterior PCRs is uncertain.

CONCLUSION

The survival of LDS restorations may slightly outperform RMC restorations after 3 years of follow-up across outcomes, except for bulk fracture. RCTs providing medium to long-term data are needed.

CLINICAL SIGNIFICANCE

Ceramic and ceramic-based PCRs are a reliable treatment option to restore extended posterior defects.

Comparison of the effects of laser systems and cold atmospheric plasma on the surface roughness and shear bond strength of flexible hybrid ceramics

The aim of this study was to compare the effects of laser systems and cold atmospheric plasma (CAP) on the surface roughness (Ra) and shear bond strength (SBS) of flexible hybrid ceramics (FHCs). Eighty FHC samples were divided into 5 groups to be subjected to surface treatments (hydrofluoric acid (HFA), HFA + 5 W Er: YAG laser (HFA + 5WE), HFA + 3 W Er: YAG laser (HFA + 3WE), HFA + ultrafast fiber laser (HFA + FL), and CAP). The Er: YAG laser (AT Fidelis Plus III, Fotona, Slovenia) was operated with a 0.9 mm diameter tip, delivering 250 mJ and 150 mJ per pulse, with output powers of 5 W and 3 W, and fluences of 23,623 J/cm² and 14,157 J/cm², respectively, at a frequency of 20 Hz and a pulse duration of 600 µs for 30 s. The FL (FiberLAST Inc., Turkey) was applied with a 7 mm spot size, 1 mJ pulse energy, 20 W output power, 100 kHz repetition rate, ultrashort pulse length (100 ns), and the fluence of 1,820 J/cm² for 7 s. The CAP (PiezoBrush PZ3, Relyon Plasma, Germany) applied to the surfaces for 80 s at a treatment speed of 5 cm2/s and 100% plasma power. After the Ra values were measured, each group was divided into 2 subgroups to be cemented with total-etch (TE) and self-adhesive (SA) resin cements. The SBS of all the samples was measured. One sample was randomly selected from each group, and the fractured surfaces were examined by SEM analysis. The significance level was at P < 0.05. HFA + FL had the highest Ra values, and there was no significant difference between HFA + FL and HFA + 5WE (P > 0.05). There was no difference in Ra between CAP and HFA (P > 0.05). The highest SBS values were observed for the samples cemented with TE after HFA + FL. The difference between the SBS values of the groups cemented with TE after CAP, HFA + 5WE, HFA + 3WE, and HFA + FL was not significant (P < 0.05). The use of FL may be a promising method to improve SBS without causing thermal damage when using TE or SA cements. CAP can be recommended as a practical and safe treatment with SA cement because it is suitable for chairside use with a handheld device and does not change the physical properties of the material.

Bonding effectiveness of multi-step adhesive resin cements to CAD/CAM blocks: impact of thermal cycling and surface treatment methods

BACKGROUND

To investigate the effects of thermal cycling and surface treatment methods on the bonding effectiveness of multi-step resin cements to CAD/CAM blocks.

METHODS

A total of 198 slices, 66 each from CAD/CAM blocks (feldspathic ceramic: Vitablocs TriLuxe Forte, V; resin matrix ceramics (RMCs): Cerasmart, C; and Shofu Block HC, S), were obtained and randomly divided into two subgroups for etching with hydrofluoric acid (HFA) and sandblasting with Al2O3 (SB). After the surface treatments, one etched and one sandblasted sample of each CAD/CAM block was observed via SEM analysis at 500× magnification. The remaining 32 etched and 32 sandblasted samples of each CAD/CAM block were divided into two subgroups to be cemented with total-etch (TE) and self-etch (SE) resin cements. Then, half of the 16 samples in all the subgroups were subjected to aging (TC) for 5000 cycles (n = 8). The shear bond strength (SBS) of each sample was measured. Four-way analysis of variance (ANOVA) and Tukey tests were used to analyze the data (p < 0.05).

RESULTS

With or without TC, the highest SBS values for V were obtained with the HFA-TE and HFA-SE interactions, respectively. C presented the highest SBS values with HFA-SE and SB-TE interactions, whereas S presented the highest SBS values with SB-TE and HFA-TE interactions. Except the SB-SE interaction, C presented lower SBS values after TC than other materials. HFA created less porosity on the C and S surfaces than V. SB visibly roughened the surfaces of all the materials but caused fractures, cracks, and damage to the surfaces.

CONCLUSION

Similar SBS values can be achieved between feldspathics, RMCs, and multi-step adhesive resins with both HFA and SB treatments. However, the SBS values obtained from the SB-SE interaction may be below the recommended threshold values for all materials after TC. SB can cause distinctive cavities, fissures, and damage, especially on the surfaces of RMCs.

Current prospect of dental zirconia recycling: A scoping review

PURPOSE

This scoping review aimed to identify and discuss the recyclability of dental zirconia residuals along with the factors influencing the properties of dental recycled zirconia.

STUDY SELECTION

In vitro studies written in both English and Chinese that evaluated the recyclability of dental zirconia residue were selected. A literature search was conducted in Medline, PubMed, Web of Science, and Cochrane Library databases with no restrictions on the publication year.

RESULTS

Sixteen studies were included in this review. Residual dental zirconia can be recycled. Cold isostatic pressing improved the density of recycled zirconia compared with uniaxial pressing. Recycled zirconia powder with fine particles enhanced the performance of recycled zirconia compared with coarse particles. A presintering temperature of 950 to 1100°C was suitable for preparing recycled zirconia presintered bodies. Recycled zirconia may require a higher sintering temperature (≥1500°C) compared with commercially available zirconia. Additionally, recycled zirconia powder can enhance the properties of polymethylmethacrylate as a reinforcing filler and can be combined with alumina powder to obtain an alumina/zirconia composite material.

CONCLUSIONS

Despite a limited body of literature, the recycling and reutilization of dental zirconia residuals are feasible and reliable, and can reduce economic and environmental losses. Nevertheless, several factors influence the recycling effect, including the particle size, molding techniques, and sintering parameters. In addition, recycled zirconia powder can act as a reinforcing filler, potentially enhancing the mechanical properties of other materials. To realize commercially viable recycled zirconia materials, further studies are essential to comprehensively explore and understand their recycling performance.

Different surface treatments on recently introduced CAD-CAM resin-modified ceramics: Implications on bond strength

STATEMENT OF PROBLEM

The diverse chemical composition of recently introduced resin-modified ceramics complicates the establishment of a universally accepted clinical bonding protocol.

PURPOSE

The purpose of this in vitro study was to evaluate the influence of different surface treatments of resin-modified ceramics on the bond strength to a resin cement.

MATERIAL AND METHODS

Sixteen 10×12×3-mm resin-modified ceramic slices were obtained from each material (Cerasmart; GC, Shofu Block HC; Shofu, Vita Enamic; Vita, Evolux hybrid; BlueDent, Alium; Alium). Slices were assigned to 4 groups based on surface treatments: Control (no treatment), airborne-particle abrasion with Al2O3 (Al2O3), conditioning with 9% HF (HF), and Al2O3+HF. After treatments and silane coupling agent (Monobond N; Ivoclar) application, 7 resin cement cylinders (Choice 2 veneer; Bisco) were built on each slice and light polymerized for 20 seconds. Half of the specimens (n=14 cylinders) were stored for 24 hours, and the other half were thermocycled (20 000 cycles, 5 °C to 55 °C, 30-second dwell time). Microshear bond strength was tested and analyzed with 3-way ANOVA and the Tukey HSD test (α=.05), and failure patterns were classified. Surface morphology after treatments was observed with scanning electron microscopy and Raman spectroscopy.

RESULTS

After 24 hours, all treatments induced higher bond strength (P<.05) than in the control in Evolux. Al2O3+HF caused higher bond strength (P<.05) than in the control in Cerasmart and Shofu, and higher bond strength than Al2O3 in Cerasmart. However, it resulted in lower bond strength (P<.05) than Al2O3 in Alium. After thermocycling, irrespective of the resin-modified ceramic, all treatments induced higher bond strength (P<.05) than in the control. HF induced lower bond strength (P<.05) than Al2O3 in Alium. Al2O3+HF caused the highest bond strength (P<.05) in Evolux and higher bond strength (P<.05) than HF in Vita Enamic. Adhesive failures were prevalent under control conditions, and mixed failures were common after treatments. Al2O3 induced surface alterations in all resin-modified ceramics. HF notably altered Vita Enamic, while it had no noticeable impact on the other resin-modified ceramics. Al2O3+HF caused a considerable alteration in Vita Enamic and modified the other resin-modified ceramics. Vita Enamic had the characteristic vibrational bands of inorganic compounds, while the other resin-modified ceramics exhibited distinct bands associated with organic compounds.

CONCLUSIONS

Airborne-particle abrasion with Al2O3 followed by HF yielded the highest bond strength, regardless of the resin-modified ceramic, except for Alium, which demonstrated better bond strength after airborne-particle abrasion with Al2O3. 9% HF for 30 seconds caused notable surface alterations in Vita Enamic, negatively impacting its bond strength. Vita Enamic was the only resin-modified ceramic displaying both organic and inorganic composition, while the other resin-modified ceramics showed predominantly organic composition.

Full-Mouth Rehabilitation of a 15-Year-Old Girl Affected by a Rare Hypoparathyroidism (Glial Cell Missing Homolog 2 Mutation): A 3-Year Follow-Up

OBJECTIVE

Familial isolated hypoparathyroidism is a rare genetic disorder due to no or low production of the parathyroid hormone, disturbing calcium and phosphate regulation. The resulting hypocalcemia may lead to dental abnormalities, such as enamel hypoplasia. The aim of this paper was to describe the full-mouth rehabilitation of a 15-year-old girl with chronic hypocalcemia due to a rare congenital hypoparathyroidism.

CLINICAL CONSIDERATIONS

In this patient, in the young adult dentition, conservative care was preferred. Onlays or stainless-steel crowns were performed on the posterior teeth, and direct or indirect (overlays and veneerlays) were performed on the maxillary premolars, canines, and incisors, using a digital wax-up. The mandibular incisors were bleached. The treatment clearly improved the patient's oral quality of life, with fewer sensitivities, better chewing, and aesthetic satisfaction. The difficulties were the regular monitoring and the limited compliance of the patient.

CONCLUSION

Despite no clinical feedback in the literature, generalized hypomineralized/hypoplastic teeth due to hypoparathyroidism in a young patient can be treated as amelogenesis imperfecta (generalized enamel defects) with a conservative approach for medium-term satisfactory results.

HIGHLIGHTS

This study provides new insights into the management of enamel hypoplasia caused by familial isolated hypoparathyroidism, helping to improve patient outcomes in similar cases.

Influence of Immediate Dentin Sealing on Bond Strength of Resin-Based CAD/CAM Restoratives to Dentin: A Systematic Review of In Vitro Studies

Immediate dentin sealing (IDS) is a method of improving the bond strength of indirect dental restorative materials to dentin and belongs to the biomimetic protocols of contemporary dentistry. The purpose of this systematic review was to evaluate the effect of IDS on the bond strength of resin-based CAD/CAM materials to dentin. PubMed and MEDLINE, Scopus, and the Web of Science were searched by two individual researchers, namely for studies that have been published in English between 1 January 2005 and 31 December 2023 in accordance with the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) statement. The inclusion criteria encompassed articles related to in vitro studies, measuring the bond strength through microtensile bond strength (μ-TBS), micro-shear bond strength (μ-SBS), tensile bond strength (TBS) or shear bond strength (SBS) tests after the use of the IDS technique. The included restorative materials comprised resin-based CAD/CAM materials bonded to dentin. A total of 1821 studies were identified, of which 7 met the inclusion criteria. A meta-analysis was not deemed appropriate due to the high level of diversity inthe publications and techniques. The use of IDS yielded higher bond strength outcomesin various experimental conditions and resin-based CAD/CAM materials. Overall, IDS in CAD/CAM restorations may contribute to better clinical outcomesand improved restoration longevity due to this property.

Clinical performance comparison between lithium disilicate and hybrid resin nano-ceramic CAD/CAM onlay restorations: a two-year randomized clinical split-mouth study

A total of 20 lithium disilicate glass-ceramics (IPS e.max CAD, Ivoclar Vivadent) and 20 resin nano-ceramic (Voco Grandio Blocks) onlay restorations were performed in 20 patients using a split-mouth design to compare the two-year clinical performance of lithium disilicate and resin nano-ceramic onlay restorations. Both restorations were evaluated at baseline, one-year, and two-year clinical follow-ups based on the modified United States Public Health Service (USPHS) criteria. Chi-square and Fisher's exact tests showed no statistically significant difference between Voco Grandio and IPS e.max ceramic restorations for all evaluated parameters during the different follow-up periods (p > 0.05). Cochrane's and MC-Nemar's tests indicated statistically significant differences regarding color match within the Voco Grandio group. They also indicated statistically significant differences in marginal discoloration, marginal adaptation, surface texture, and postoperative hypersensitivity within both ceramic material groups (p < 0.05). Kaplan-Meier curve indicated that the survival rate of both ceramic materials was 90%. After two years of clinical service, IPS e.max CAD and Voco Grandio onlay restorations exhibited similar clinical performance.

The effect of repair protocols and chewing simulation on the microtensile bond strength of two resin matrix ceramics to composite resin

BACKGROUND

To assess the micro tensile bond strength (µTBS) of two resin matrix ceramic (RMC) blocks bonded to composite resin by using different repair protocols with and without chewing simulation (CS).

MATERIALS AND METHODS

Two resin matrix ceramic blocks (Vita Enamic and Lava Ultimate) were divided into 4 groups according to the surface treatments: Bur grinding (control), Bur grinding + silane, 9.5% HF acid etching, and 9.5% HF acid etching + silane. The single bond universal adhesive was applied on all specimens after the surface treatments according to the manufacturer's instructions, it was administered actively on the treated surface for 20 s and then light cured for 10 s, followed by incremental packing of composite resin to the treated surface. Each group was further divided into 2 subgroups (with/without chewing simulation for 500,000 cycles). A micro tensile bond strength test was performed for each group (n = 15). The effect of surface treatments on the materials was examined by using a scanning electron microscope (SEM). The micro tensile bond strength (MPa) data were analyzed with a three-way ANOVA, the independent t-test, and one-way ANOVA followed by the Tukey post-hoc test.

RESULTS

µTBS results were significantly higher for Lava Ultimate than Vita Enamic for all the surface treatment protocols with (p < 0.01). The chewing simulation significantly negatively affected the micro-tensile bond strength (p < 0.001). Bur grinding + saline exhibited the highest bond strength values for Lava Ultimate, both with and without chewing simulation. For Vita Enamic, bur grinding + saline and HF acid + saline showed significantly higher bond strength values compared to other surface treatments, both with and without chewing simulation (p ≤ 0.05).

CONCLUSION

Bur grinding + silane could be recommended as a durable repair protocol for indirect resin matrix ceramics blocks with composite resin material.

β-Tricalcium Phosphate as Alveolar Bone Grafting in Cleft Lip/Palate: A Systematic Review

The aim of this systematic review is to describe and identify the prospects of β-Tricalcium Phosphate (β-TCP) as an alveolar bone grafting (ABG) material in cleft lip/palate (CL/P) or alveolar bone cleft defects. A systematic review protocol based on the Preferred Reporting Items for Systematic Reviews and Meta-Analyses 2020 (PRISMA 2020) was drafted. The literature search was conducted using MEDLINE/PubMed, Web of Science/ISI Web of Knowledge, Scopus, and the Cochrane Library, with English as the inclusion criterion and no publication year limits. The keywords yielded a total of 5824 publications. After removing duplicates and non-English articles, there were 3196 suitable articles available for evaluation. Subsequently, 1315 studies remained after reviewing titles and abstracts. Furthermore, 85 full articles were assessed for eligibility. After reading the complete texts of those papers, 20 were eventually selected that matched the inclusion requirements. Thirteen out of the twenty studies included in this systematic review were deemed to have a low risk of bias; one had a high risk of bias; and six had a moderate risk of bias due to not reporting randomization. β-TCP, when used as an ABG material, is biocompatible, visible, practical, offers a less invasive procedure, and does not interfere with orthodontic treatment. Synthetic β-TCP for ABG can be an alternative to autologous bone grafts under certain terms and conditions. The efficacy of β-TCP for ABG in CL/P or alveolar bone cleft defects can be enhanced through a tissue engineering approach that combines β-TCP with growth factors, mesenchymal stem cells, or other graft materials, along with modifications to β-TCP's physical properties.

Physical Properties and Clinical Performance of Short Fiber Reinforced Resin-based Composite in Posterior Dentition: Systematic Review and Meta-analysis

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.

Effect of different surface treatments on resin-matrix CAD/CAM ceramics bonding to dentin: in vitro study

BACKGROUND

Evaluating the effect of different surface treatment methods on the micro-tensile bond strength (µTBS) of two different resin-matrix computer-aided design/computer-aided manufacturing (CAD/CAM) ceramics (RMCs).

METHODS

A standardized inlay preparations were performed on 100 intact maxillary premolars. According to the type of the restorative material, the teeth were randomly divided into two equally sized groups (n = 50): (polymer-infiltrated ceramic (Vita Enamic) and resin-based composites (Lava Ultimate)). The inlays were fabricated using CAD/CAM technology. In each group, the specimens were randomly assigned to five subgroups (n = 10) according to the surface treatment method: group 1 used was the control group (no surface treatment); group 2, was treated with air abrasion with 50 μm Al2O3 (A) and universal adhesive (UA); group 3, was treated with air abrasion with 50 μm Al2O3 (A) and silane coupling agent (S); group 4, was treated with hydrofluoric acid (HF) and universal adhesive (UA) and group 5, was treated with Hydrofluoric acid (HF) + silane coupling agent (S). The inlays were then cemented to their respective preparations using dual-cure self-adhesive resin cement (RelyX U200, 3 M ESPE) according to the manufacturer's instructions. The µTBS test was conducted in all groups, and stereomicroscope and scanning electron microscope were used to inspect the failure mode. The data were statistically analyzed using a two-way analysis of variance (ANOVA) and Tukey's post-hoc multiple comparison tests at a significance level of p < 0.05.

RESULTS

Surface treatments significantly increased the µTBS of the materials compared to the control group (p < 0.05). For CAD/CAM RBCs, the µTBS value highest in group 2 whereas, for PICN, the µTBS value was highest in group 3. Cohesive failure of CAD/CAM restorative material was the most predominant mode of failure in all treated groups, whereas adhesive failure at restoration-cement interface was the most predominant failure mode in the control group.

CONCLUSION

Surface treatments increase the µTBS of resin-matrix CAD/CAM ceramics to tooth structure. Air abrasion followed by universal adhesive and hydrofluoric acid followed by silane application appears to be the best strategies for optimizing the bond strength of CAD/CAM RBCs and PICN respectively.

Influence of surface treatment and ageing on the bond strength of resin cement to hybrid and glass-ceramic CAD/CAM materials

The influence of different surface treatments and ageing on the shear bond strength (SBS) of computer-aided design/computer-aided manufacturing (CAD/CAM) materials is still contentious. Therefore, this study evaluated the effect of surface treatments and ageing on the SBS of resin cement to polymer-infiltrated ceramic network (PICN) and zirconia-reinforced lithium silicate (ZLS) CAD/CAM materials. Specimens of PICN (n=10) and ZLS (n=10) were submitted to four surface treatment groups: 1) 5% hydrofluoric acid etching (HF) + silanisation (SI); 2) Air abrasion (AB)+HF+SI; 3) HF + universal adhesive (UA); 4) AB+HF+SI+UA. The treated specimens were bonded with resin cement cylinders and tested in SBS after 24 h and one year of water storage. Data were assessed by "analysis of variance" (ANOVA) and Tukey test (α=0.05) and failure modes were classified. No significant differences were observed among treatments at each evaluation time (p>0.05). SBS decreased after one year of storage, except for PICN treated with HF+UA (p=0.068). Air-abraded groups displayed a lower SBS reduction for ZLS. PICN and ZLS exhibited predominantly adhesive and mixed failures, but at one year, PICN cohesive failures increased. In conclusion, HF+UA is an effective surface treatment for PICN, while the combination AB+HF+SI+UA was more appropriate for ZLS. The water storage for one year reduced the SBS for most groups.

García A, G. Mikos A, M. Anderson J, Zhang X. Evidence-based biomaterials research

The fast development of biomaterials science and engineering has generated significant number of studies and publications as well as tremendous amount of research data. A methodology is needed to translate such research data and results to validated scientific evidence. This article for the first time proposes the concept and methodology of evidence-based biomaterials research, which is to use evidence-based research approach represented by systematic reviews to generate evidence for answering scientific questions related to biomaterials. After briefly introducing the advancement of biomaterials since 1950s, the scientific and engineering nature of biomaterials are discussed along with the roadmap of biomaterials translation from basic research to commercialized medical products, and the needs of scientific evidence. Key information of the evidence-based approach such as its origination from evidence-based medicine, levels of evidence, systematic review and meta-analysis, differences between systematic and narrative reviews is then highlighted. Applications with a step-by-step procedure of conducting evidence-based biomaterials research, three examples of biomaterials research using evidence-based approach to generate scientific evidence, and opportunities and challenges of evidence-based biomaterials research are presented. With its notable impact on the practice of medicine, the evidence-based approach is also expected to make influential contributions to the biomaterials field.

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Evidence-based biomaterials research (EBBR) is very important for biomaterials.

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Authors for the first time propose the concept, practice and methodology of EBBR.

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EBBR uses an evidence-based approach of systematic review and meta-analysis.

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Key elements of an evidence-based approach are discussed.

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Procedures and examples of evidence-based biomaterials research are illustrated.

Shear Bond Strength of a Direct Resin Composite to CAD-CAM Composite Blocks: Relative Contribution of Micromechanical and Chemical Block Surface Treatment

This study aims to compare the shear bond strength (SBS) of a direct resin composite to CAD-CAM resin composite blocks treated with different surface treatments: micromechanical, chemical or a combination of both. Eight CAD-CAM resin composite blocks, namely Brilliant Crios, Cerasmart 270, Vita Enamic, Grandio block, Katana Avencia, Lava Ultimate, Tetric CAD and Shofu Block HC were chosen. The micromechanical surface treatment protocols tested were hydrofluoric acid, polyacrylic acid or sandblasting, and the chemical one was a universal primer. These treated CAD-CAM blocks were tested to determine the SBS of a light-curing composite resin Z100 bonded to their surface. Two-way ANOVA followed by Tukey’s post hoc test was used to investigate the difference in SBS. Failures were analyzed by Fisher’s exact test. Bonding interfaces were examined by scanning electron microscopy. The micromechanical surface treatments give the highest SBS values: sandblasting appears to be the most efficient procedure for dispersed filler composite blocks, while hydrofluoric acid etching is preferable for polymer-infiltrated ceramic network (PICN) blocks. The use of universal primer does not improve SBS values on dispersed filler composite blocks. For PICN blocks, the use of universal primer significantly increases SBS values when combined with hydrofluoric acid etching.

Clinical performance of resin-matrix ceramic partial coverage restorations: a systematic review

OBJECTIVE

To evaluate clinical performance of the new CAD/CAM resin-matrix ceramics and compare it with ceramic partial coverage restorations.

MATERIALS AND METHODS

An electronic search of 3 databases (The National Library of Medicine (MEDLINE/PubMed), Scopus, and the Cochrane Central Register of Controlled Trials) was conducted. English clinical studies published between 2005 and September 2020 that evaluated the clinical performance of CAD/CAM resin-matrix ceramics inlays, onlays, or overlays were selected. The primary clinical question was applied according to PICOS strategy (Population, Intervention, Comparison, Outcome, Study design). The included studies were individually evaluated for risk of bias according to the modified Cochrane Collaboration tool criteria.

RESULTS

A total of 7 studies were included according to the established inclusion and exclusion criteria. From the included studies, 6 were randomized clinical trials while one study was longitudinal observational study without control group. According to the results of the included studies, the success rate of CAD/CAM resin-based composite ranged from 85.7 to 100% whereas the success rate reported for ceramic partial coverage restorations ranged from 93.3 to 100%. Fractures and debondings are found to be the most common cause of restorations failure.

CONCLUSION

CAD/CAM resin-based composite can be considered a reliable material for partial coverage restorations with clinical performance similar to glass ceramic restorations. However, this result needs to be confirmed in long-term evaluations.

CLINICAL RELEVANCE

CAD/CAM resin-based composites provide a potential alternative to ceramic indirect restorations. However, clinicians must be aware of the lake of knowledge regarding long-term outcome.

Full mapping tensile bond strength of luting in search for differences due to centripetal curing shrinkage

OBJECTIVES

testing if hypothetical transverse centripetal strains due to polymerization contraction of luting materials produce differential alterations in its bonding to luted structures, depending on distances to the center of the luting mass, and if this effect is C-factor related. Two hypotheses were tested: (1) there is a statistically significant decreasing relationship between the bonding strength and the transverse distances to the center of the luting material, and (2) there is a statistically significant difference between bonding strengths among luting spaces with different configuration factors.

METHODS

10 PMMA (15 mm Ø) pairs of cylinders were cemented (Scotchbond Universal adhesive & Relyx Universal, both chemically cured) in a compliant setup under two (20 and 70 N) luting forces forming 2 groups (5 samples each), resulting in different C-factors. Whole samples were sectioned in x and y directions obtaining non-trimmed beams from all along the luting surfaces. Their relative positions in each sample were assessed before separating and categorized (10 categories) according to their distances to the center of the sample. All beams were tested in tension and, because of their uneven bonding areas and to balance its influence, UTS results were transformed into UTS_res. First hypothesis was tested trough a linear relationship between UTS_res and distances to vertical centers per samples. Second hypothesis was tested using Mann-Whitney U tests to compare UTS_res between groups, along all categories. Further Weibull analysis was applied.

RESULTS

ANOVA's p of the regression UTS_res - categories were statistically significant for all samples in group 70 N and for all except one in group 20 N: first hypothesis is partially maintained. Although Mann-Whitney tests p comparing UTS_res of both groups for all categories but the first were statistically significant this hypothesis was maintained relying in Weibull analysis.

SIGNIFICANCE

bonded attachment of cemented materials decreases from centers to outbounds in plane, extensive surfaces, and this decrease is C-factor related.

Bonding ability of resin cements to different types of CAD/CAM composite blocks

This study investigated the bonding performance of two different types of resin cements to computer-aided design/computer-aided manufacturing (CAD/CAM) composite blocks based on the shear bond strength (SBS) test. A silane-containing self-adhesive resin cement (Panavia SA Cement Universal) and resin luting cement (Block HC Cem) with a primer, were used. Specimens were fabricated from three different types of CAD/CAM composite blocks, and their surfaces were blasted with alumina. Resin cements were bonded to the specimens, and their SBSs were measured after 15 min, 24 h, and after being subjected to thermal cycling for 10,000 and 30,000 cycles. Three-way ANOVA for bond strength revealed that CAD/CAM composite block, resin cement and storage time significantly influenced the SBS values, and the three-way interactions between the evaluated factors, and all the interactions were significant. It was concluded that the bonding performance of resin cements to CAD/CAM composite blocks were material and storage period dependent.

Annual review of selected scientific literature: A report of the Committee on Scientific Investigation of the American Academy of Restorative Dentistry

The Scientific Investigation Committee of the American Academy of Restorative Dentistry offers this review of the 2020 professional literature in restorative dentistry to inform busy dentists regarding noteworthy scientific and clinical progress over the past year. Each member of the committee brings discipline-specific expertise to this work to cover this broad topic. Specific subject areas addressed include prosthodontics; periodontics, alveolar bone, and peri-implant tissues; implant dentistry; dental materials and therapeutics; occlusion and temporomandibular disorders (TMDs); sleep-related breathing disorders; oral medicine and oral and maxillofacial surgery; and dental caries and cariology. The authors focused their efforts on reporting information likely to influence day-to-day dental treatment decisions with a keen eye on future trends in the profession. With the tremendous volume of dentistry and related literature being published today, this review cannot possibly be comprehensive. The purpose is to update interested readers and provide important resource material for those interested in pursuing greater detail. It remains our intent to assist colleagues in navigating the extensive volume of important information being published annually. It is our hope that readers find this work useful in successfully managing the dental patients they encounter.

Alumina particle air-abrasion and aging effects: Fatigue behavior of CAD/CAM resin composite crowns and flexural strength evaluations

The aim of this study was to characterize the flexural strength and elastic modulus of CAD/CAM resin composite material and to evaluate the influence of different surface treatments and storage conditions on the fatigue behavior of bonded composite crowns. Bars (flexural strength, n= 30; elastic modulus, n= 5) (1.2 × 4 × 12 mm) were produced for three-point bending test and CAD/CAM milled crowns (n= 5) (thickness= 1 mm) adhesively cemented to an epoxy resin substrate for fatigue tests. Bars and crowns were randomly allocated into two "surface treatments": no surface treatment (CTRL) and air-abrasion with 110 μm Al₂O₃ particles (AlOx); while the crowns were also subdivided into "aging condition" (baseline - storage for 24 h to 7 days, and aging - storage for 150 days + 25,000 thermal cycles). The three-point bending test was performed according to ISO 6872 and the luted crowns were subjected to step-stress fatigue test (initial load of 200 N; step-size of 50 N; 10,000 cycles per step; 20 Hz). Complementary analysis by Stereomicroscopy and Field Emission Scanning Electron Microscopy (FE-SEM) were performed. The flexural strength and fatigue data were submitted to statistical tests (α= 0.05). The results showed that air-abrasion reduces the flexural strength and the characteristic strength of the resin composite, without modifying its elastic modulus or its structural reliability (Weibull Modulus). Air-abrasion did not influence the fatigue behavior of the cemented crowns. Notwithstanding, a decrease in the survival rate was observed after 445,000 cycles (2,400 N) when subjected to aging at both the CTRL or AlOx conditions. FE-SEM micrographs of the crowns showed that alumina particle air-abrasion treatment can modify the topography of its treated inner surface. Therefore, air-abrasion with alumina powder introduces defects onto the surface of the CAD/CAM resin composite material, decreasing the flexural strength, but without changing its elastic modulus and reliability. Adhesive cementation onto an epoxy resin substrate prevented an influence of the introduced defects on the fatigue performance of the resin composite restoration. Nevertheless, the fatigue behavior may be damaged by aging regimen.

Effect of Different Surface Treatment Methods on Bond Strength of Dental Ceramics to Dental Hard Tissues: A Systematic Review

For long-term successful use of ceramic materials in dental procedures, it is necessary to ensure reliable bonding of restorations to dental substrates. This can be achieved by the application of a proper luting cement and through additional surface conditioning. The present systematic review summarizes the most up-to-date evidence on the use of different surface modification methods to enhance the bond strength of dental ceramics to the hard tissues of the teeth. The authors of the review searched the Web of Science, Scopus, and MEDLINE databases to identify relevant articles published between 1 January 2010 and 1 January 2020. A total of 4892 records were identified, and after screening, the full text of 159 articles was evaluated, which finally resulted in the inclusion of 19 studies. The available reports were found to be heterogeneous in terms of materials and methodology, and therefore, only within-studies comparison was performed instead of comparison between studies. A statistically significant difference in the bond strength between the samples treated with different methods of surface conditioning, or between conditioned and nonconditioned samples, was revealed by most of the studies. Predominantly, the studies showed that a combination of mechanical and chemical methods was the most effective way of enhancing bond strength. Artificial aging and luting cement were also identified as the factors significantly influencing bond strength.

Effects of Aging on the Color and Translucency of Monolithic Translucent Y-TZP Ceramics: A Systematic Review and Meta-Analysis of In Vitro Studies

Background

Monolithic restorations made of translucent yttria-stabilized tetragonal zirconia polycrystal (Y-TZP) have become popular over the past few decades. However, whether aging affects the color and translucency of monolithic translucent Y-TZP is unclear.

Objective

The aim of this systematic review and meta-analysis of in vitro studies was to evaluate the effects of aging on the color and translucency of monolithic translucent Y-TZP ceramics.

Materials and Methods

This systematic review/meta-analysis was reported according to the PRISMA statement and registered in the OSF registries (https://osf.io/5qjmu). Four databases including Medline via the PubMed, Embase, and Web of Science databases and the Cochrane Library were searched using no publication year and language limits. The last search was executed on November 20, 2020. In vitro studies comparing the translucency and/or color of monolithic translucent Y-TZP ceramics before and after simulated aging were selected. Meta-analyses were performed using Review Manager software (version 5.3, Cochrane Collaboration, Oxford, UK) with random-effects models at a significance level of 0.05. A risk-of-bias assessment was also performed for the included studies.

Results

Of the 188 potentially relevant studies, 13 were included in the systematic review. The hydrothermal aging duration ranged from 1 to 100 h at relatively similar temperatures (~134°C). In the general meta-analyses, the aged Y-TZP ceramics exhibited similar translucency parameter (TP), L^∗, and b^∗ values compared with the nonaged controls (P = .73, P = .49, and P = .62, respectively). Moreover, there was a significant difference between the aged and nonaged Y-TZP ceramics in the a^∗ value (P = .03; MD = −0.26; 95% CI = −0.51 to − 0.02), favoring the nonaged Y-TZP ceramics. The subgroup analyses showed that the duration of aging contributed to changes in the translucency and color of the Y-TZP ceramics.

Conclusions

The optical properties of monolithic translucent Y-TZP ceramics were stable after hydrothermal aging at 134°C and 0.2 MPa for ≤20 h. Moreover, clinically unacceptable changes in the translucency and color of monolithic translucent Y-TZP ceramics were found after hydrothermal aging for >20 h.

Bonding performance of dispersed filler resin composite CAD/CAM blocks with different surface treatment protocols

The effect of various pretreatments on the bonding of a resin cement to resin-composite CAD/CAM blocks (RCBs) was examined. The surface of dispersed-filler RCBs (DF-RCBs) and a polymer infiltrated ceramic network RCB (PICN-RCB) was roughened using hydrofluoric acid etching (HF) or sandblasting, and followed by silanization and/or universal adhesive (UA) application. Microtensile bond strength (µTBS), surface roughness parameters (arithmetical mean height (Sa); developed interfacial area ratio (Sdr)), and critical surface energy (γ_c) were determined. For most DF-RCBs, the highest µTBS was obtained using HF+UA. UA application to DF-RCBs resulted in similar or higher µTBS compared to silanization, which indicates that silane treatment is not crucial for DF-RCBs, especially after HF. In contrast, the highest µTBS to PICN-RCB was obtained with silanization. Both roughening pretreatments significantly increased the surface roughness parameters and the γ_c of all RCBs. The γ_c was positively correlated with Sa (r=0.756, p<0.001) and Sdr (r=0.837, p<0.001).

Effect of Cleaning Protocol on Bond Strength between Resin Composite Cement and Three Different CAD/CAM Materials

The present investigation tested the effect of the cleaning method on the tensile bond strength (TBS) between one resin composite cement (RCC) and three different computer aided design/computer aided manufacturing (CAD/CAM) materials, namely zirconia, lithium disilicate ceramic and resin composite. Ninety specimens were prepared from each CAD/CAM material (N = 270). The specimens were pre-treated respectively, divided into five subgroups and subjected to five different cleaning protocols, namely i. 37% phosphoric acid, ii. ethanol, iii. phosphoric acid + ethanol, iv. cleaning paste, v. distilled water. After cleaning, the specimens were either conditioned using a universal primer or a universal adhesive and bonded using a dual-curing RCC. After thermo-cycling (20,000x at 5 °C/55 °C), TBS and fracture patterns were evaluated. The data was analyzed using 1- and 2-way Analysis of Variance (ANOVA) with post-hoc Scheffé and partial eta-squared (ƞ_P²), Kruskal-Wallis, Mann-Whitney U and Chi² tests (p < 0.05). The CAD/CAM material showed an impact on the BS while the cleaning protocol did not affect the results. Zirconia obtained the highest BS, followed by lithium-disilicate-ceramic. Resin composite resulted in the overall lowest BS. For most fracture patterns, the cohesive type occurred. All tested cleaning protocols resulted in same BS values within one CAD/CAM material indicating that the impact of the cleaning method for the restorative material seems to play a subordinate role in obtaining durable bond strength to resin composite cement. Further, it indicates that the recommended bonding protocols are well adjusted to the respective materials and might be able to compensate the impact of not accurately performed cleaning protocols.

Tensile Strength and Failure Types of Direct and Indirect Resin Composite Copings for Perio-Overdentures Luted Using Different Adhesive Cementation Modalities

Perio-overdenture design helps to reduce periodontal diseases and secondary caries on abutment teeth. Composite copings can be cemented adhesively to the abutment teeth with different techniques. In this study, direct/indirect resin composite copings for perio-overdentures, luted using different adhesive cementation modalities were compared. Human teeth (N = 40) were prepared to receive spherical attachment copings and randomly divided into four groups: (1) resin-composite copings bonded directly (DC), (2) composite copings made indirectly, luted with dual-polymerized resin cement (ICV), (3) composite copings made indirectly, bonded with resin composite (ICT), (4) composite copings made indirectly, bonded with resin composite after the immediate dentin sealing method (IDS). Specimens were tested for tensile failure and one-way ANOVA (alpha = 0.05) was performed and the two-parameter Weibull modulus, scale (m) and shape (₀) were calculated. Mean tensile load (N) was significantly higher for Group IDS (238 ± 81) than for the other groups (144 ± 53–184 ± 46) (p < 0.05). Group IDS (0.54 ± 0.25 mm) showed significantly higher deformation (mm) than other groups (0.2 ± 0.1–0.32 ± 0.15) (p < 0.05). Weibull distribution presented lower shape (₀) for DC (3.33) compared to other groups (3.57–4.99). Cohesive coping failures were more frequent in Group IDS (60%) and mixed failures in other groups (40–60%). In conclusion, IDS copings could be preferred over other fabrication and adhesion modalities.