Tensile bond strength of indirect composites luted with three new self-adhesive resin cements to dentin

Fracture Resistance of Laboratory Composite Versus All-Ceramic Restorations in Class II Inlay Cavity Preparations: An In Vitro Study

BACKGROUND

A posterior tooth's occlusal surfaces and the proximal surface can be restored by using an inlay, which is an intra-crown cast reconstruction without affecting the cusps of the tooth. When an inlay is prepared using an indirect approach, issues with traditional filling approaches, including poor morphology of the occlusal aspect or proximal aspect, inadequate resistance to wear, or subpar mechanical qualities of the directly inserted filler substance, are overcome.

AIM

The current study was conducted in order to compare and assess the resistance to fracture of dental materials used in the preparation of inlay restorations indirectly, like composite restorations prepared by laboratories indirectly, inlays formed indirectly of monolithic translucent ceramic derived from zirconia, and inlays formed indirectly of traditional monolithic ceramic derived from zirconia.

METHODS AND MATERIALS

For the investigation, 100 human premolars of the maxilla that were extracted recently were chosen. A self-polymerizing acrylic resin was used to incorporate the tooth roots in a band made up of polyvinyl chloride up to 2 mm below the cement-enamel junction. The dimension of the band was 1.3 cm by 1.9 cm. Five categories of 20 specimens of such teeth were formed. Category one, featuring teeth in good condition, acted as the positive control category. The remaining four categories of teeth received inlay tooth preparation. The research samples underwent thermocycling after having been preserved for a full week following the cementation of inlay replacements. Then, in a universal testing apparatus, every sample endured axial compressive force with a metal globe delivered vertically at a crosshead rate of 1 mm/minute. The amount of force necessary to cause a fracture was measured in Newtons (N).

RESULTS

The mean values of resistance against fracture in specimens in categories 1-5 were 1208.87 N, 614.89 N, 733.05 N, 1179.14 N, and 1148.49 N, respectively. The values of fracture resistance in specimens where an inlay cavity preparation was done but not filled were lower than those in traditional monolithic ceramic derived from zirconia and tooth specimens with inlays formed of monolithic translucent ceramic derived from zirconia, and the difference was significant statistically (p=0.001). The values of fracture resistance in composite inlay restorations prepared by laboratories were indirectly lower than those of monolithic ceramic derived from zirconia and tooth specimens with inlays formed of monolithic translucent ceramic derived from zirconia, and the difference was significant statistically (p=0.004).

CONCLUSION

Within the constraints of the current investigation, we can state that indirect zirconia-based ceramic products offer adequate fracture resistance, but additional research is needed to determine how well these materials hold up under different types of pressures before employing them in clinical tooth restoration.

Fracture resistance of lab composite versus all-ceramic restorations in class II inlay cavity preparations: An in vitro study

Aim

The aim of this study was to evaluate and compare the fracture resistance of inlay preparations restored with indirect lab composite, conventional and translucent monolithic zirconia-based ceramics.

Materials and Methods

Fifty freshly extracted human maxillary premolars were selected for the study. Standardized inlay cavities were prepared and restored with indirect lab composite, conventional monolithic zirconia-based ceramic and translucent monolithic zirconia-based ceramic. After restoration each sample was subjected to axial compressive load with Universal testing machine. The force required to induce fracture was recorded in Newton (N).

Statistical Analysis Used

The data were analyzed using the one-way ANOVA test and Post hoc Bonferroni multiple comparison test.

Results

Results revealed that fracture resistance of prepared inlay cavities restored with conventional monolithic zirconia-based ceramics was found to be best followed by other groups. Group I > Group IV > Group V > Group III > Group II.

Conclusion

The fracture resistance of conventional monolithic zirconia-based ceramic inlays and translucent monolithic zirconia-based ceramic inlays were comparable with intact teeth but, indirect lab composite inlays showed lower fracture resistance than all.

Substantial regional differences in the biomechanical behavior of molar treated with selective caries tissue removal technique: a finite element study

OBJECTIVES

Selective caries removal (SCR) is recommended over non-selective removal for managing deep carious lesions to avoid pulp exposure and maintain pulp vitality. During SCR, residual carious dentin is left behind and sealed beneath the restoration. The biomechanical effects of such residual lesions on the restored tooth remain unclear and were assessed using finite element modeling (FEM).

METHODS

Based on μ-CT images of a healthy permanent human third molar, we developed five finite element models. Generic class I and II cavity restorations were modeled where residual lesions of variable sizes were either left or fully removed on occlusal and proximal surfaces. The cavities were restored with adhesive composite. All 3D-FE models were compared with a model of a healthy, non-treated molar. A vertical load of 100 N was applied onto the occlusal surface.

RESULTS

Regardless of the lesion size, in molars with occlusal lesions higher mean stresses were predicted along the filling-lesion interface than in all other models. The smallest occlusal lesion (Ø₁ = 1 mm) resulted in the highest maximum stresses at the filling-lesion interface with large stress concentrations at the filling walls indicating failure risk. In conclusion, lesion site and extent are influencing parameters affecting the filling-lesion interactions and thus the biomechanical behavior of the tooth after SCR.

SIGNIFICANCE

Retaining carious lesions around the pulpal floor affects the deformation and stress states in tooth-filling complexes. The higher stresses observed in molars with occlusal lesions may affect restoration stability and longevity. Suprisingly, more extended occlusal lesions may provide a more favorable tooth performance than less extended ones. In contrast, in molars with proximal lesions the residual lesion had only limited effect on the tooth's biomechanical condition.

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

CLINICAL RELEVANCE

Conventional multistep resin cements presented higher adhesive performance to dentin than simplified self-adhesive cements, which is an important criterion for indirect restoration prognosis.

SUMMARY

This study aimed to conduct a systematic review of the literature on laboratory studies assessing bonding performance to dentin of conventional and self-adhesive resin cements, in cementing indirect restorations. This review was reported according to the PRISMA Statement. Of a total of 518 studies, 36 were screened full text and reviewed according to exclusion criteria. Nineteen papers were included in the systematic review and meta-analyses, according to the following inclusion criteria: studies that evaluated the bond strength to dentin of indirect restorations cemented with dual conventional or self-adhesive resin cements and those that presented bond strength data in MPa as an outcome. Statistical analyses were conducted using Rev-Man 5.1. Comparisons were performed with random effects models at 5% significance level. A global analysis comparing conventional and self-adhesive cements and three subgroup analyses comparing immediate and long-term results were performed. Global analysis showed a difference between groups, with conventional resin cements presenting higher bond strength results than self-adhesive resin cements, in immediate and long-term time periods (both p=0.03). Immediate and longterm bond strength results were different for self-adhesive cements, favoring immediate bond strength (p=0.03), but immediate and long-term bond strength results for conventional resin cements were not different (p=0.06). Medium or high risk of bias was found in all studies. Conventional multistep resin cements showed superior overall adhesive performance compared with simplified self-adhesive resin cements when used to cement indirect restorations to dentin.

Effect of photo-polymerization mode on the degree of conversion of resin cement under different ceramic materials

BACKGROUND

This study evaluated the effect of different polymerization modes and duration on the degree of conversion (DC) of resin cement under different types of ceramics.

METHODS

Ceramic materials were divided into 3 groups (N.=60): group 1, Cerasmart; group 2, Vita Enamic; and group 3, Vita Mark II. Each group was then divided into three subgroups (N.=20) according to the polymerization mode (A: low-intensity; B: high-intensity; and C: soft-start). Subgroups were then divided into two further groups according to the polymerization time (I: 10 s; and II: 20 s). DC of light-cured resin cement beneath different kinds of ceramics was tested using FTIR spectroscopy. Results were compared to a control group cured without overlying ceramic.

RESULTS

While the type of ceramic and mode of polymerization showed a significant effect on the DC of resin cement, polymerization duration did not. Vita Mark II group showed the highest DC of resin cement followed by Vita Enamic and Cerasmart. High- and low-intensity polymerization modes did not show significant difference, but both showed significantly lower DC when compared to soft start mode.

CONCLUSIONS

Type of ceramic and polymerization mode showed a direct effect on the DC of resin cement.

Dawn of a New Age Fissure Sealant? A Study Evaluating the Clinical Performance of Embrace WetBond and ART Sealants: Results from a Randomized Controlled Clinical Trial

OBJECTIVES

 The main purpose of this article is to evaluate the clinical performance of atraumatic restorative treatment (ART) sealant versus Embrace WetBond sealant in terms of retention and fissure caries prevention among a section of school children in the southern Indian state of Karnataka (ClinicalTrials.gov NCT02716558).

MATERIALS AND METHODS

 After obtaining consent from the parents and screening the children against the inclusion cum exclusion criteria, 90 school children whose mandibular first molars were caries free and with a well-defined pit and fissure system were recruited for this spilt mouth trial. The respective molars were allocated either to the ART sealant or the embrace group after the randomization process. The sealants were applied according to the manufacturer's instructions and followed up at the end of 3rd, 6th, and 12th month, respectively. The outcome measures assessed were the retention and the caries preventive effects of the materials.

RESULTS

 At the end of the 6th month, about one-fourth of the sealants in either group remained totally intact, without evidence of caries. No significant differences were seen between the sealants either in terms of retention or caries preventive benefits at the end of 12 months.

STATISTICAL ANALYSIS

 The chi-squared test was used to check differences in proportions. The significance value was set at <0.05. Kappa test was performed to assess the intraexaminer reproducibility with respect to retention and caries status.

CONCLUSION

 The moisture-tolerant resin sealant could not replicate the physical properties usually associated with conventional resin sealants. The usage of ART sealants was deemed to be less cumbersome in an outreach setting as observed in this trial.

Resistência de união de diferentes cimentos resinosos a cerâmica à base de dissilicato de lítio

Resumo Introdução O sucesso de restaurações indiretas depende de uma adequada união entre o cimento e o substrato dental. Portanto, a seleção e o conhecimento das características dos agentes cimentantes são importantes para a retenção da restauração indireta. Objetivo Avaliar a resistência de união de dois cimentos resinosos diferentes à cerâmica de dissilicato de lítio. Metodologia Dois grupos experimentais foram confeccionados: cimento resinoso convencional (Grupo CRC) e cimento resinoso autoadesivo (Grupo CRA). Para isso, dez discos de cerâmica de dissilicato de lítio (10 mm) foram pré-fabricados e, sobre cada disco, foram confeccionados quatro postes de cimento (0,7×1,0 mm), obtendo-se um total de 20 amostras de cada tipo de cimento. Os discos tiveram o mesmo tratamento de superfície para os dois grupos, que é padrão para as cerâmicas ricas em sílica, de acordo com o protocolo estabelecido pelo fabricante. As amostras foram submetidas ao teste de microcisalhamento para avaliar a resistência de união entre o cimento e a cerâmica. Posteriormente, o modo de falha foi analisado em microscópio ótico. Resultado Os dados obtidos foram submetidos a teste estatístico. Foi observado que o grupo CRC apresentou maiores valores de resistência de união (15,29 MPa) em relação ao grupo CRA (12,41 MPa). Na análise do modo de falha, nenhuma amostra obteve fratura do tipo adesiva. Em ambos os grupos, CRC (75%) e CRA (65%), obtiveram-se mais falhas do tipo mista, seguidas pela falha coesiva. Conclusão Ambos os cimentos apresentaram adesão à cerâmica. O cimento resinoso convencional apresentou maior adesão a cerâmica à base de dissilicato de lítio que o cimento resinoso autoadesivo.

Surface treatment comparison by application of diamond bur and Er,Cr:YSGG at different powers: morphological and mechanical evaluation

Purpose: This study evaluated the micro-tensile bond strength of new and previous composite resin restorations after surface treatment with diamond bur and Er,Cr:YSGG laser at different power settings (2,3 and 4 W). Materials and methods: Micro-hybride composite resin was inserted in metallic mold 5 ×5 ×15 mm and cured for 40 sec according to manufacturer's instruction.12 blocks were made. The bonded surfaces of the 12 blocks so obtained were subsequently ground using Silicon Carbide papers 1200 grit, for 15 seconds under running water. Then the samples randomly were divided into 4 groups: (G1) Bur-treated, (G2) Er,Cr:YSGG laser with power of 2 W and energy of 100 mJ, (G3) Er,Cr:YSGG laser with power of 3 W and energy of 150 mJ, (G4) Er,Cr:YSGG laser with power of 4 W and energy of 200 mJ. One sample of each group was analyzed by SEM while, after cutting the blocks to 1 mm² of area samples, the others samples were mechanically tested by Universal testing machine with the speed of 0.5 mm per minute till fracture point. Data were analysed using One-Way ANOVA and Tukey Test. Results: T-test showed no significantly differences between G2 and G4(P=0.064) while G3 demonstrated significant differences than G2 (P=0.001) and G4(P=0.000) and also between samples treated with bur (G1) and G2 (P=0.242) ,G3 (P=0.000) ,G4 (P=0.829); G1 didn't significantly differ to G2 and G4(P>0.05), while G1 and G3(P<0.05). Conclusion: On surface treatment of repaired composite, samples treated by laser at 3W power showed better condition of micro-tensile bond strength.

Effect of indirect composite treatment microtensile bond strength of self-adhesive resin cements

Background

No specific indications about the pre-treatment of indirect composite restorations is provided by the manufacturers of most self-adhesive resin cements. The potential effect of silane treatment to the bond strength of the complete tooth/indirect restoration complex is not available.The aim of this study was to determine the contribution of different surface treatments on microtensile bond strength of composite overlays to dentin using several self-adhesive resin cements and a total-etch one.

Material and Methods

Composite overlays were fabricated and bonding surfaces were airborne-particle abraded and randomly assigned to two different surface treatments: no treatment or silane application (RelyX Ceramic Primer) followed by an adhesive (Adper Scotchbond 1 XT). Composite overlays were luted to flat dentin surfaces using the following self-adhesive resin cements: RelyX Unicem, G-Cem, Speedcem, Maxcem Elite or Smartcem2, and the total-etch resin cement RelyX ARC. After 24 h, bonded specimens were cut into sticks 1 mm thick and stressed in tension until failure. Two-way ANOVA and SNK tests were applied at α=0.05.

Results

Bond strength values were significantly influenced by the resin cement used (p<0.001). However, composite surface treatment and the interaction between the resin cement applied and surface treatment did not significantly affect dentin bond strength (p>0.05). All self-adhesive resin cements showed lower bond strength values than the total-etch RelyX ARC. Among self-adhesive resin cements, RelyX Unicem and G-Cem attained statistically higher bond strength values. Smartcem2 and Maxcem Elite exhibited 80-90% of pre-test failures.

Conclusions

The silane and adhesive application after indirect resin composite sandblasting did not improve the bond strength of dentin-composite overlay complex. Selection of the resin cement seems to be a more relevant factor when bonding indirect composites to dentin than its surface treatment.

Key words:Bond strength, self-adhesive cement, silane, dentin, indirect composite.

Effect of Different Powers of Er,Cr:YSGG Laser Treatment on Surface Morphology of Microhybride Composite Resin: Scanning Electron Microscope (SEM) Evaluation

INTRODUCTION

The aim of this study was to evaluate and compare microhybride composite treated by bur and different power of Erbium, Chromium doped Yttrium Scandium Gallium Garnet (Er,Cr:YSGG) laser by Scanning Electron Microscope (SEM).

METHODS

21 microhybride composite blocks (DiaFil TM, DiaDent, Korea) with 2 × 4 × 4 mm dimensions were made. The bonding surface of these blocks were polished, The samples were put into 6 groups for laser irradiation as follows: Group 1 (power: 1W, Energy: 50 mJ); Group 2(power: 2 W, Energy: 100mJ); Group 3 (power: 3W, Energy: 150mJ); Group 4 (power: 4W, Energy: 200mJ); Group 5 (power: 5W, Energy: 250mJ) and Group 6(power:6 W, Energy:300mJ). One group prepared by bur- treated. All samples were prepared by repetition rate of 20 Hz. Then, the samples were prepared for SEM examination.

RESULT

Some irregularities were seen in Er,Cr:YSGG laser samples in comparison to Bur group that produced favorable surface for adhesion of repair composite.

CONCLUSION

Among different lasers, Er;Cr:YSGG laser can be chosen as a suitable technique for surface treatment of unsatisfactory composites.

Resin bond to indirect composite and new ceramic/polymer materials: a review of the literature

STATEMENT OF THE PROBLEM

Resin bonding is essential for clinical longevity of indirect restorations. Especially in light of the increasing popularity of computer-aided design/computer-aided manufacturing-fabricated indirect restorations, there is a need to assess optimal bonding protocols for new ceramic/polymer materials and indirect composites.

PURPOSE OF THE STUDY

The aim of this article was to review and assess the current scientific evidence on the resin bond to indirect composite and new ceramic/polymer materials.

MATERIALS AND METHODS

An electronic PubMed database search was conducted from 1966 to September 2013 for in vitro studies pertaining the resin bond to indirect composite and new ceramic/polymer materials.

RESULTS

The search revealed 198 titles. Full-text screening was carried out for 43 studies, yielding 18 relevant articles that complied with inclusion criteria. No relevant studies could be identified regarding new ceramic/polymer materials. Most common surface treatments are aluminum-oxide air-abrasion, silane treatment, and hydrofluoric acid-etching for indirect composite restoration. Self-adhesive cements achieve lower bond strengths in comparison with etch-and-rinse systems. Thermocycling has a greater impact on bonding behavior than water storage.

CONCLUSIONS

Air-particle abrasion and additional silane treatment should be applied to enhance the resin bond to laboratory-processed composites. However, there is an urgent need for in vitro studies that evaluate the bond strength to new ceramic/polymer materials.

CLINICAL SIGNIFICANCE

This article reviews the available dental literature on resin bond of laboratory composites and gives scientifically based guidance for their successful placement. Furthermore, this review demonstrated that future research for new ceramic/polymer materials is required.

Effect of Laser Treatment on Surface Morphology of Indirect Composite Resin: Scanning Electron Microscope (SEM) Evaluation

INTRODUCTION

The aim of this study was to evaluate and compare the Scanning electron microscope (SEM) of indirect composite conditioned by Erbium-Doped Yttrium Aluminum Garnet (Er:YAG) laser, Neodymium-Doped Yttrium Aluminium Garnet (Nd:YAG) laser and Carbon Dioxide (CO2) laser.

METHODS

18 indirect composite blocks (GC Gradia DA2, Japan) with 15 × 10 × 10 mm dimensions were made. The bonding surface of these blocks were polished, then the samples were divided into six groups as follow: Er:YAG laser with output power of 0.5 W and frequency of 10 Hz, Nd:YAG laser with output power of 0.25, 0.5 W and frequency of 10 Hz, CO2 laser with output power of 0.5 W and frequency of 10 Hz and 5 Hz, and no treatment. Then, the surfaces were evaluated by SEM.

RESULTS

Irregularities were observed in Er:YAG laser samples compared to control group that produced suitable retention for adhesion of cements. Nd:YAG and CO2 lasers showed melting areas.

CONCLUSION

Among different lasers, Er:YAG laser can be used as an alternative technique for surface treatment of indirect composites.

Efficacy of a moisture-tolerant material for fissure sealing: a prospective randomised clinical trial

OBJECTIVES

Fissure sealings offer nearly complete protection against fissure caries, provided that they are adequately applied, for composite-based sealants with sufficient moisture control. This is not always attainable, particularly in children with low compliance. To counter this problem, a moisture-tolerant sealant has been developed. The present randomised clinical trial compared such a moisture-tolerant material (Embrace) with a conventional sealant (Helioseal).

MATERIAL AND METHODS

In 55 participants (mean age, 10 ± 3 years), corresponding molar pairs were sealed with either Embrace or Helioseal. Retention, quality of sealing, and caries were clinically examined, both tactilely and visually, immediately and after 1 year.

RESULTS

After 1 year, 93% of Helioseal sealings were complete, whereas 60% of Embrace sealings showed partial and 13% complete loss. The surface quality of Embrace was significantly worse than that of Helioseal. After the use of Embrace, the sealant margin was noticeable as a slight (distinct) step in 36% (15%). The visual (tactile) examination showed a rough surface in 78% (33%) in the case of Embrace. The Helioseal surfaces were shiny (smooth) in all cases (all differences between Helioseal and Embrace, p ≤ 0.001). Caries was found only after the use of Embrace (4%, n.s. compared to Helioseal).

CONCLUSION

The moisture-tolerant material Embrace was distinctly inferior to Helioseal because Embrace showed weaknesses in retention and surface quality.

CLINICAL RELEVANCE

Even if a moisture-tolerant sealant would be desirable in particular for children with low compliance, the tested material does not represent an alternative to the standard preparation.