Effect of different luting materials on the marginal adaptation of Class I ceramic inlay restorations in vitro

The incidence of dental fractures in the Italian population during the COVID-19 pandemic: An observational study

Background

The COVID-19 infection has become a pandemic after breaking out in China in the past months of 2019 and spreading rapidly worldwide. To counter this pandemic, several governments worldwide have taken several drastic measures to try to stop the spread of the virus, including a very strict lockdown that has caused a sudden and, in many cases, negative change in people's daily lives. In the literature, several studies have shown how the pandemic has significantly impaired many people's mental health, causing short- and long-term stress, anxiety, and sleep disturbances.

Introduction

This study aims to analyze the correlation between the stress caused by the COVID-19 pandemic and the parafunctions of the temporomandibular joint and masticatory muscles, which in turn, have led to an increase in the incidence of fractures and dental injuries. The ultimate goal is to understand the best choice the dentist must make in the preventive and therapeutic fields.

Materials and Methods

A questionnaire called "Incidence of tooth fractures during the COVID-19 pandemic" was prepared using the Google® Forms platform. This questionnaire consists of 13 questions. This electronic questionnaire was addressed to all dentists in the Campania Region (ITA) and disseminated through social networks such as WhatsApp® or Facebook® or E-mail.

Results

A total of 730 dentists completed the survey. Of these, 450 (61.7%) stated that the number of patients reporting muscle and joint pain in the morning had increased during the COVID-19 pandemic. 414 (56.7%) dentists noted an increase in parafunction and 392 (53.6%) an increase in dental fractures during the pandemic period.

Discussion and Conclusions

As can be seen from the study results, an important correlation was found between the stress resulting from the COVID-19 pandemic and dental fractures. The dental elements treated endodontically, depending on the extent of the damage, require restoration, which is also the best preventive strategy in the case of dental fractures.

Evaluation of Cements Curing Modes Regarding Microleakage During Cementation of E-max Laminate Veneers

Purpose: The aim of this study is to investigate the effect of the curing modes of two adhesive resin cements (Light cure mode of the Variolink Veneer, the self-cure mode and dual cure mode of the Multilink Automix) on the marginal leakage of lithium disilicate ceramic laminate veneers. Methods: A total number of forty eight extracted natural central incisors were prepared to receive ceramic laminate veneers, constructed using E-max ceramic divided into three groups cemented using three curing modes of two adhesive resin cements {light-cure mode of Variolink Veneer, self-cure mode of Multilink Automix and dual-cure mode of Multilink Automix adhesive resin cements} . Die penetration test was done using the methylene blue stain {qualitative assessment} for testing the die penetration along the tooth/ceramic interface. Results: Descriptive statistical analysis revealed that the self-curing mode recorded the significantly least degree of leakage compared to the light and dual cure modes.  The self-cure mode recorded (0.1±0.3) which was significantly lower than light cure (1.2 ±0.9) and dual cure mode (1.2 ±0.4), there was no statistical significant difference between the later two curing modes. The self-cure mode of the resin cement is considered a more effective method for having the least marginal leakage at the tooth/ceramic interface. There was no difference between the light cure mode and the dual cure mode.

Microleakage of porcelain laminate veneers cemented with different bonding techniques

Background

Porcelain laminate veneers (PLV) are continued to be popular in modern dental practice due to its high aesthetic outcome and conservative tooth preparation. The composite resins are commonly used as luting agents for cementation of PLV. Polymerisation shrinkage induced marginal gap and interfacial leakage is the persistent limitation with the resin luting cements. The objective of the study was to assess the effect of various dentin bonding techniques on the microleakage after accelerated ageing in porcelain laminate veneres.

Material and Methods

Forty intact, premolar teeth were prepared to receive the PLV. The lithium disilicate PLV were fabricated from IPS e.max System. The intaglio surfaces were prepared with hydrofluoric acid and silane. Teeth samples were randomly divided among four groups of ten each according to the tooth surface preconditioning; it included etch-wash light cure, etch-wash dual cure, self-etch and self-adhesive techniques. The Teeth samples were subjected to the accelerated ageing with thermocycling and exposure to xenon light. The microleakage was accessed with die penetration test using 0.5% basic fuchsin. The data was statistically analysed by Kruskal-Wallis and Mann-Whitney U tests.

Results

The etch-wash dual cure resin cements recorded the lowest interfacial microleakage score of 0.90 and 0.60 at cervical tooth-composite resin and incisal enamel-composite regions respectively. The highest corresponding values of 3.00 and 1.60 was recorded with self-Adhesive resin luting cements. The microleakage at cervical tooth- composite interface was significantly higher in comparison to incisal enamel-composite interface across all the tested groups. The microleakage values at porcelain-composite interface was considerably less to the tooth- composite interface.

Conclusions

Etch-wash composite resin luting cements for PLV provided the best bonding interface, with the least interfacial microleakage. Key words:Porcelain laminate veneer, Microleakage, Tooth conditioning, Bonding techniques.

Evaluation of adaptation of ceramic inlays using optical coherence tomography and replica technique

Optical coherence tomography (OCT) has generally been used as a nondestructive technique to evaluate integrities of composite restorations. We investigated marginal and internal adaptations of ceramic inlay restorations with OCT and compared them to results with the silicone replica technique. Round-shaped class I cavities were prepared on 16 human maxillary first premolar teeth. Ceramic inlays were fabricated. Silicone replicas from inlays were obtained and sectioned to measure marginal and internal adaptations with a stereomicroscope (Leica Dfc 295, Bensheim, Germany). Inlays were cemented on respective teeth. Marginal and internal adaptations were then measured with the OCT system (Thorlabs, New Jersey, USA) in 200- μm intervals. Replica and OCT measurements were compared with independent samples t-tests. A paired t-test was used to evaluate the marginal and internal adaptations of each group (p < 0.05). Marginal and internal adaptations were 100.97 ± 31.36 and 113.94 ± 39.75 μm, respectively, using the replica technique and 28.97 ± 17.86 and 97.87 ± 21.83 μm, respectively, using OCT. The differences between the techniques were significant (p = 0.00 and p = 0.01, respectively). On evaluation within the groups, internal adaptation values were found to be significantly higher than the marginal adaptation values for the replica technique (p = 0.00) and OCT (p = 0.00). Therefore, the replica and OCT techniques showed different results, with higher values of marginal and internal adaptation found with the replica technique. Marginal and internal adaptation values of ceramic inlays, whether measured by replica or OCT techniques, were within clinically acceptable limits.

Cementation of Glass-Ceramic Posterior Restorations: A Systematic Review

Aim. The aim of this comprehensive review is to systematically organize the current knowledge regarding the cementation of glass-ceramic materials and restorations, with an additional focus on the benefits of Immediate Dentin Sealing (IDS). Materials and Methods. An extensive literature search concerning the cementation of single-unit glass-ceramic posterior restorations was conducted in the databases of MEDLINE (Pubmed), CENTRAL (Cochrane Central Register of Controlled Trials), and EMBASE. To be considered for inclusion, in vitro and in vivo studies should compare different cementation regimes involving a “glass-ceramic/cement/human tooth” complex. Results and Conclusions. 88 studies were included in total. The in vitro data were organized according to the following topics: (micro)shear and (micro)tensile bond strength, fracture strength, and marginal gap and integrity. For in vivo studies survival and quality of survival were considered. In vitro studies showed that adhesive systems (3-step, etch-and-rinse) result in the best (micro)shear bond strength values compared to self-adhesive and self-etch systems when luting glass-ceramic substrates to human dentin. The highest fracture strength is obtained with adhesive cements in particular. No marked clinical preference for one specific procedure could be demonstrated on the basis of the reviewed literature. The possible merits of IDS are most convincingly illustrated by the favorable microtensile bond strengths. No clinical studies regarding IDS were found.

Five-year retrospective clinical study of indirect composite restorations luted with a light-cured composite in posterior teeth

OBJECTIVES

The purpose of this study was to evaluate the clinical performance of indirect composite onlays-overlays bonded with a light-cured composite on vital molars.

MATERIALS AND METHODS

Forty-one patients were restored with 79 indirect composite restorations. The restorations were studied for an observation time of 5 years. Marginal adaptation, marginal discolouration, secondary caries, colour match and anatomic form were clinically examined following modified United States Public Health Service criteria. Each restoration was also examined for fractures and debonding. Endodontic complications were registered. Survival rate, based just on failures that required a replacement, and success rate that included also failures that required a repair intervention were statistically determined using a restoration and a patient-related analysis.

RESULTS

After 5 years, using each restoration as a statistical unit, the survival rate was 91.1% and the success rate 84.8%, with a high Kaplan-Meier estimated success probability of 0.852. Using the patient as the statistical unit, the survival rate was 90.2% and the success rate 85.4%, corresponding to a Kaplan-Meier estimated success probability of 0.857. On the basis of the criteria used, most of the restorations rated Alpha. Regarding marginal adaptation and marginal discolouration, 5 and 10.1% of the restorations, respectively, revealed Bravo ratings

CONCLUSIONS

Indirect composite restorations offer a predictable and successful treatment modality giving an optimal preservation of sound tooth tissue.

CLINICAL RELEVANCE

The preparation, cementation and finishing procedures are considered key factors for the long-term success of the indirect composite restorations.

Physical properties of dual-cured luting-agents correlated to early no interfacial-gap incidence with composite inlay restorations

OBJECTIVES

The aims of this investigation were to investigate dual-cured luting-agents as to whether their bond strength, dimensional change and flexural modulus influence no interfacial-gap incidence parameters of composite inlay restorations during the early stages. The correlations of interest were between: (a) their shear bond strength to dentin, (b) their dimensional change on setting, (c) their flexural modulus, and (d) no interfacial-gap incidence with indirect restorations.

METHODS

Seven dual-cured luting-agents, one self-adhesive resin cement, six resin cements and one resin-modified glass-ionomer for luting, were investigated with specimen sub-groups (n=10) for each property measured. The principal series of experiments were conducted in dentin cavities with interfacial polishing either immediately (3 min) after setting or after 1-day water-storage. After the finishing procedure, each tooth was sectioned in a buccolingual direction through the center of the restoration, and the presence or absence of interfacial-gaps was measured (and then summed for each cavity) at 14 points (each 0.5mm apart) along the composite inlay restoration interface (n=10 per group; total points measured=140), and was expressed by percentage of measured total points. The shear bond strengths to dentin, setting shrinkage-strain and flexural modulus were measured. To estimate the dimensional change of luting-agents, the maximum marginal gap-width and the opposing-width that occurred with luting-agents in a Teflon mold were measured. Moduli were measured in 3-point bending.

RESULTS

For all composite inlay restorations, polished immediately after setting, an incidence of summed no-gaps of 69-88% was observed. For specimens polished after 1 day, a significantly (p<0.05) decreased number of 91-96% summed no-gaps occurred. After 1-day storage, shear bond strengths to dentin and flexural modulus increased highly significantly (p<0.001) for many materials, whereas dimensional changes in the Teflon mold were non-significantly different (p>0.05). There was a highly significant correlation between no interfacial-gap incidence and shear bond strength (r=0.702, p=0.002, n=16). As the dimensional change (shrinkage) within Teflon molds increased, the no interfacial-gap incidence of dentin/inlay interfaces with 'no-gaps' decreased (r=-0.574, p=0.02, n=16). Flexural moduli significantly correlated with no interfacial-gap incidence in the composite inlay restorations (r=0.695, p=0.003, n=16).

SIGNIFICANCE

For three classes of luting-agents during the early stage of setting (<1 day), the shear bond strength to dentin, the dimensional change measured by marginal gaps in Teflon mold and flexural moduli correlated with no interfacial-gap incidence in the composite inlay restoration.

Influence of air-abrasion on zirconia ceramic bonding using an adhesive composite resin

OBJECTIVES

Air-abrasion as bonding conditioning method for zirconia ceramic might compromise the mechanical strength of zirconia restorations. The purpose of this study was to evaluate the influence of surface conditioning parameters, i.e., air-abrasion with reduced pressure or no air-abrasion and priming with adhesive primers on the long-term resin bond strength to zirconia ceramic.

METHODS

Zirconia ceramic disks were polished with 600 grit abrasive paper. Plexiglas tubes filled with composite resin were bonded with RelyX Unicem luting composite resin to the conditioned zirconia disks. Three surface conditions (unconditioned, air-born particle abrasion at 0.05 or 0.25 MPa) and four priming conditions (no priming, priming with Metal/Zirconia Primer, priming with Alloy Primer, priming with Clearfil Ceramic Primer) were tested. Sixteen specimens of each combination were bonded. Subgroups of eight bonded samples were stored in water either for 3 days or 150 days with 37,500 thermocycling. Tensile bond strengths (TBSs) were determined with a universal testing machine at a crosshead speed of 2mm/min.

RESULTS

Without priming, RelyX Unicem showed durable bond strength to 0.25 MPa airborne-particle abraded ceramic. When combined with 10-methacryloyloxy-decyl dihydrogenphosphate containing primers, air-abrasion resulted in a durable TBS to zirconia ceramic even at a reduced abrasion pressure. However, combined with Metal/Zirconia Primer air-abrasion did not provide a durable TBS to zirconia ceramic.

SIGNIFICANCE

Using a self-adhesive luting resin composite (RelyX Unicem), air-abrasion at 0.25 MPa or the combination of low pressure air-abrasion and priming with MDP-containing primers seems to be useful to achieve durable long-term bonding to zirconia ceramic.

In vitro evaluation of push-out bond strength of direct ceramic inlays to tooth surface with fiber-reinforced composite at the interface

STATEMENT OF PROBLEM

Failure of a restoration, where a part of a ceramic inlay and/or a cusp is fractured, is a common clinical problem. The application of fiber-reinforced composites at the tooth-inlay interface may prevent undesirable fractures in dental restorations. There is little information regarding the effect of a fiber- reinforced composite layer on the push-out bond strength of ceramic inlays to tooth structure.

PURPOSE

The purpose of this study was to compare push-out bond strengths of ceramic inlays to tooth structure using a layer of fiber weave-reinforced composite at the tooth interface with different adhesive systems.

MATERIAL AND METHODS

Forty standardized occlusal, conically-shaped cavities, 5 mm in occlusal diameter, 3.5 mm in cervical diameter and 3.5 mm deep, were prepared in extracted human molars using a truncated cone-shaped diamond rotary cutting instrument, the dimensions of which corresponded with those of prefabricated ceramic inlays. The teeth were divided into 2 groups according to the adhesive system used. Solobond Plus was used as a total-etching system and Futurabond NR as a self-etching system. Preetched and silanized ceramic inlays were bonded to tooth structure with or without a layer of bidirectional fiber weave (StickTech). The groups without fiber-reinforced composite layer served as controls. The inlays were cemented with dual-polymerizing luting composite (Bifix QM) and light polymerized for 40 seconds from the buccal, lingual, and occlusal surfaces. Specimens were thermal cycled (6000 x 5 degrees -55 degrees C) and 3.5-mm-thick discs were prepared for the push-out test. The discs (n=10) were tested in a universal testing machine and pushed out with a cross-head speed of 1.0 mm/min. The data were analyzed with analysis of variance (ANOVA) (alpha=.05). Failure modes were analyzed using a stereomicroscope and SEM.

RESULTS

Push-out mean bond strength (SD) values in MPa of direct ceramic inlays were: Solobond Plus (control): 9.7 (3.9), Solobond Plus with fiber-reinforced composite: 10.5 (5.0), Futurabond NR (control): 8.4 (2.5), Futurabond NR with fiber-reinforced composite: 8.6 (2.2). The differences between groups were not significant for either adhesive system or with the use of fiber-reinforced composite layer at the interface. Mixed failures were observed in the control groups, whereas in the fiber-reinforced composite layer groups, failures were mostly cohesive within the fiber layer. No cohesive fracture of the tooth was observed when a layer of fiber weave was placed at the interface.

CONCLUSION

Within the limitations of this in vitro study, a fiber-reinforced composite layer at the bonding interface of ceramic inlay did not influence the push-out bond strength. Futurabond NR self-etching system and Solobond Plus total-etching system demonstrated similar push-out bond strengths.

Eight year results with direct ceramic restorations (Cerana)

BACKGROUND

Single-visit system ceramic restorations are now in use to provide an alternative to resin-based materials. Inserts have been shown to improve characteristics of composite restorations.

OBJECTIVE

To investigate the longevity of Cerana (Nordiska Dental, Sweden) in a prospective clinical trial.

METHODS

Cerana restorations use matched drills with pre-etched and silanated leucite inserts cemented using a conventional restorative composite resin material. The results of 33 Cerana restorations up to eight years (25 Class I, eight class II) are presented. Restorations were reviewed and assessed by two examiners using modified USPHS criteria for anatomical form (AF) A-C, marginal adaptation (MA) A-D, surface roughness (SR) A-D, marginal discoloration (MD) A-C, colour match (CM) A-C and discomfort (DT) A-D as well as retention.

RESULTS

The percentage of A scores for AF, MA, SR, MD, CM and DT at baseline (n = 33) were: 100, 100, 79, 100, 21, 100; after two years (n = 27) 100, 85, 33, 100, 19, 100 and after four years (n = 24) 96, 75, 17, 96, 25, 100. At six years (n = 20) 95, 70, 10, 95, 15, 100 and finally at the eight year recall (n = 18) 94, 61, 0, 94, 6, 100. AF was maintained in all except for one fractured marginal ridge. MA of the insert was good but composite was lost where exposed. SR increased to a B score for all inserts. MD at B grade was observed in 6% between composite and tooth but none between insert and composite. CM was stable in all cases. DT nil in all. There were no scores less than B. All reviewed restorations were retained, clinically acceptable and in function except for two lost for reasons not directly related to the Cerana insert. One class II restoration had a fractured marginal ridge but otherwise remains satisfactory.

CONCLUSIONS

The results suggest that these restorations can be expected to perform well. Cerana is acceptable in terms of aesthetics, patient acceptance, occlusal wear and ease of use and is a good alternative for a single-visit, tooth coloured restoration in suitable cavity shapes.

Ceramic inserts do not generally improve resin composite margins

summary Ceramic inserts are reported to possibly reduce polymerization shrinkage for posterior resin composite fillings. The aim of the present investigation was to evaluate the effect of different insert systems before and after thermomechanical loading. Sixty sound human third molars received occlusomesial Class II cavities, 40 with proximal margins 2 mm above and 20 with proximal margins 1 mm below the cementum-enamel junction. The specimens were randomly assigned to one of the six experimental groups (n = 10). The enamel-bordered cavities were restored with Syntac classic and Tetric Ceram (ST), Syntac classic, Tetric Ceram and beta-quartz inserts (TB), Syntac classic, Tetric Ceram and Cerana inserts (TC), Syntac classic, Tetric flow and SonicSys approx inserts (TS). The dentin-limited cavities were filled with Syntac classic and Tetic Ceram (DT), Syntac classic, Tetric flow and SonicSys approx inserts (DS). Before and after thermomechanical loading (100 000 x 50 N, 2500 x 5 degrees C/55 degrees C), replicas were made and both interfaces tooth/composite and insert/composite were examined under a scanning electron microscope at 200x. The Cerana and SonicSys insert groups showed significantly less gaps in enamel (P < 0.05). With beta-quartz inserts, no reduction of gaps was found (P > 0.05). Marginal integrity in dentine-bordered specimens could not be improved with SonicSys inserts (P > 0.05). The bonding performance insert/composite was promising for all IPS Empress inserts (Cerana, SonicSys enamel) but worse for beta-quartz inserts. Regarding gap formation between resin composite and tooth, Cerana and SonicSys inserts significantly reduced gaps. The use of SonicSys inserts in deep proximal cavities cannot be recommended.