Influence of the adhesive strategy in the sealing ability of resin composite inlays after deep margin elevation

In Vitro Effect of the Length of Relocated Cervical Margin with Casting Post and Core, Prefabricated Fiber Post, and Polyethylene Fiber with a Composite Core on Fracture Resistance and Marginal Integrity

Objective

This study aimed to assess the effect of length of the relocated cervical margin with casting post and core (CP), prefabricated fiber post and composite core (PFP), and polyethylene fiber-reinforced composite (PEFRC) on fracture resistance and marginal integrity.

Materials and Methods

In this in vitro study, 70 sound human maxillary premolars were divided into seven groups according to the type of post and core system and length of the relocated cervical margin (n = 10): control (no preparation), PFP-3, PEFRC-3, CP-3 with 3 mm of cervical margin relocation (CMR), PFP-6, PEFRC-6, and CP-6 (with 6 mm of CMR). The samples were restored with zirconia crowns (except the control group). Epoxy resin replicas were fabricated before and after thermomechanical loading. Marginal integrity was assessed at the luting cement-core, core-tooth, and luting cement-enamel interfaces under a scanning electron microscope (SEM) (×200). Fracture resistance and failure mode were subsequently assessed. Data were analyzed by independent t-test, paired t-test, ANOVA, Tukey-Games Howell, Mann-Whitney, Kruskal-Wallis, Wilcoxon, Mann-Whitney with Bonferroni correction, and Fisher-Freeman-Halton tests (α = 0.05).

Results

The marginal integrity of the groups with 3 mm of CMR followed the following order: PEFRC > PFP > CP at all interfaces (P  < 0.05). In 6-mm CMR groups, this order was CP < PFP = PEFRC at the luting cement-core and (CP < PEFRC) = PFP at the core-tooth interface. No significant difference was found in fracture resistance when comparing the 3-mm CMR groups with each other (P  > 0.05). PFP-6 showed higher FR than CP-6 (P  < 0.001). PEFRC-6 had no significant difference with PFP-6 and CP-6 (P  > 0.05). In each post and core system, 3-mm CMR groups showed higher marginal integrity and fracture resistance (P  < 0.05).

Conclusion

Increasing the length of the relocated cervical margin decreased the marginal integrity and fracture resistance of all three systems of CP, PFP, and PEFRC.

Deep margin elevation in restorative dentistry: A scoping review

OBJECTIVES

Deep margin elevation (DME) is a restorative approach offering the possibility of performing stepwise elevation of deep proximal cavities to create more favourable margins for direct or indirect restorations. The objectives of this scoping review were to explore what is known or unknown about DME by describing a wide ranging evidence base including peer reviewed literature and non-traditionally published information on the web.

DATA

Data were extracted from the included evidence in order to describe the following: the extent and nature of the evidence base; the situations which are appropriate for DME; the materials and techniques which are used; the outcomes which have been measured in empirical studies; the risks which have been reported; and the findings which have been reported in studies which compared DME to surgical crown lengthening.

SOURCES

This scoping review included a wide range of published evidence and extensive web searching for grey literature, including CPD, training and multimedia information.

STUDY SELECTION

The findings revealed a range of published literature as well as freely available, online information advising practitioners about DME. Most empirical evidence was based on in vitro studies, and there were few clinical studies comparing DME to crown lengthening. Online information included recent, multimedia sources.

CONCLUSIONS

DME is a technique that can be used with motivated patients with good oral hygiene if rubber dam isolation is achieved, if there is no invasion of the connective tissue space, and if a strict restorative protocol is adhered to.

CLINICAL SIGNIFICANCE

With phasing out of amalgam and adhesive dentistry increasing in popularity, DME addresses multiple clinical problems associated with sub-gingival margins prior to restoration.

A Comparative Evaluation of the Bonding Strength, Marginal Adaptation, and Microleakage of Dental Cements in Prosthodontics: An In Vitro Comparative Study

BACKGROUND

The primary function of dental cement is to seal and support prosthodontic restorative materials. Proper selection of the dental cement contributes to the clinical success of the restoration.

METHODS

A total of 166 molar tooth samples were prepared to simulate the type of tooth commonly found in prosthodontic practice. Each sample was restored using one of the tested dental cement materials employing a prestabilized methodology. The performance of resin-modified glass ionomer cement (RMGIC) (GC Fuji PLUS Capsule, GC America, Alsip, IL), zinc phosphate cement (ZPC) (Dentsply Sirona, Charlotte, NC), and resin cement (RC) (RelyX ARC, 3M ESPE, Saint Paul, MN) in bonding strength, marginal adaptation, and microleakage was evaluated and compared. The bonding strength, marginal adaptation, and microgroove were tested using specific established methodologies. The outcomes were then analyzed using statistical analyses for means and standard deviations to compare different types of dental cement.

RESULTS

The total outcome shows that the highest bonding strength with the highest mean was the resin cement, rating 24.8 MPa, followed by RMGIC and ZPC at 20.5 and 18.9 MPa, respectively. The marginal adaptation scores indicate that RC had the highest score at a mean of 4, followed by ZPC at 3.2 and RMGIC at 2.5. The dye penetration measurements in millimeters revealed that ZPC had a penetration of 0.31 mm, RMGIC had a penetration of 0.25 mm, and RC had the least penetration at 0.20 mm. The results of the statistical data analysis show significant differences between the dental cements in bonding strength and marginal adaptation.

CONCLUSION

In conclusion, resin cement demonstrated superior performance in bonding strength, marginal adaptation, and resistance to microleakage compared to RMGIC and zinc phosphate cement. These findings highlight the importance of selecting resin cement for achieving optimal clinical outcomes in prosthodontic restorations.

One case of complicated crown root fracture of upper anterior teeth managed by multidisciplinary joint approaches

Complicated crown root fracture is a serious combined fracture of the enamel, dentin, and cementum in dental trauma. The treatment method is complicated. During the procedure, the condition of pulp, periodontal, and tooth body should be thoroughly evaluated, and a multidisciplinary approach combined with sequential treatment is recommended. This case reported the different treatment and repair processes of one case of two affected teeth after complicated crown root fracture of upper anterior teeth, including regrafting of broken crown after flap surgery at the first visit, direct resin repair to remove broken fragments, and pulp treatment and post-crown repair at the second visit. After 18 months of follow-up, the preservation treatment of the affected teeth with complicated crown root fracture was achieved. Therefore, fragment reattachment and post-crown restoration are feasible treatment options for children with complicated crown root fracture.

Effect of cervical margin relocation on marginal adaptation and microleakage of indirect ceramic restorations

PURPOSE

This study evaluated the effect of cervical margin relocation (CMR) with two different materials and contamination with hemostatic agents on the margin adaptation and microleakage of ceramic restorations.

MATERIALS AND METHODS

Mesial-occlusal-distal cavities were prepared in 60 human first molars and distributed to 3 groups (n = 20) according to the margin relocation procedure. The groups were: group F; flowable composite applied in two 2 mm increments, group B; bulk-fill flowable composite applied as a bulk increment of 4 mm thickness and group C (control); no CMR was done. Each group was subdivided into two subgroups (subgroup N; no hemostatic agent applied and subgroup H; hemostatic agent was applied). In all groups, ceramic inlays were prepared and cemented. The samples were subjected to thermocycling (10,000 cycles). The adaptation of the cervical margin was evaluated with scanning electron microscopy (200×). Samples were then assessed for microleakage analysis with the dye penetration method. Marginal adaptation data were normally distributed and analyzed using two-way ANOVA followed by Tukey's post hoc test. Ordinal microleakage score data were analyzed using cumulative link models followed by the analysis of deviance using Wald chi-square tests.

RESULTS

Both CMR and contamination with a hemostatic agent had significant effects on the margin adaptation of the cervical margin. Group C showed the highest adaptation with no significant difference from group F. The lowest adaptation was revealed in group B with a significant difference from group C. Subgroup N (in all groups) showed a statistically higher adaptation than subgroup H. Regarding microleakage assessment, CMR had no significant effect but hemostatic agent application showed a significantly higher microleakage score for all groups.

CONCLUSIONS

Both the CMR procedure and contamination with AlCl3 hemostatic agent had a negative effect on marginal adaptation. For microleakage assessment, only contamination with hemostatic agent negatively affected the microleakage with no effect on the margin relocation procedure.

Comparison of Various Commonly Used Luting Cements on the Success of Composite Inlays Assessed by the Levels of the Microleakage-An In vitro Study

Introduction

Indirect composite restoration is one of the commonly followed procedures in the posterior teeth. The success of this is dependent on many factors, one being the luting cement. Hence, the current study explores the microleakage of the two luting cements at 2 different times.

Materials and Methods

Eighty extracted human teeth were taken, and class II cavities were made that were to receive the composite inlays. They were grouped as supragingival and subgingival, which for further divided as were further subdivided to be observed for marginal leakage at cervical and occlusal margins, at the end of a day and 1 month. Each group had ten specimens. The luting cements that were evaluated were Variolink N and RelyX Unicem. After the composite inlay restoration was done for all the specimens, the sections were put on slides, and a stereomicroscope was used to measure the amount of dye penetration. Leakage was evaluated and compared using Mann-Whitney U test.

Results

At the end of 1 day, there was no significant alteration in the microleakage in the occlusal or cervical regions for either region supragingivally or subgingivally between the two luting cements. Significant difference between the two cements at the cervical borders at the end of a month was seen for both the margins. When compared supragingivally and subgingivally at the end of 1 day or at the end of 1 month, there was not a significant difference for any of the cements.

Conclusion

Within the constraints of the current investigation, it can be said that there was similar microleakage for both Variolink N and RelyX Unicem at the conclusion of a day's storage time. After a 1-month storage period, RelyX Unicem showed more cervical microleakage than Variolink N.

Survival and debonding resistance of posterior cantilever resin-bonded fixed dental prostheses for moderately and severely worn dentition during thermomechanical loading

OBJECTIVES

The purpose of this study was to investigate the survival rate, the debonding resistance, and the failure modes of different occlusal veneer designs when used as a retainer for posterior cantilever, resin-bonded fixed dental prostheses (RBFDPs) at two tooth wear levels.

METHODS

Four test groups were assigned: two groups with occlusal-proximal preparation (PT1 and PT2 for grade 2 and 3 wear), and two groups for occlusal-proximal and lingual preparation (PLT1 and PLT2 for grade 2 and 3 wear) Monolithic zirconia ceramic (3Y-TZP) RBFDPs were luted with an adhesive bonding system (Panavia V5). The specimens underwent a chewing simulation for 1.200.000 cycles with a load of 5 kg and thermocycling for 7500 cycles between 5 °C and 55 °C. The surviving restorations were debonded under quasi-static conditions. The results were analyzed with ANOVA.

RESULTS

The specimens exhibited a 100 % survival rate after thermomechanical fatigue loading. The debonding resistance was statistically significant higher for group PLT1 than for group PT1 (P = 0.004), and higher for group PT2 than group PT1 (P ≤ 0.001). However, the debonding resistance showed no statistically significant difference between groups PT2 and PLT2 (P = 0.343), and groups PLT1 and PLT2 (P = 0.222). Groups PT1 and PT2 showed favorable failure modes in 62.5 % and 0.00 % of the specimens, respectively. While groups PLT1 and PLT2 presented 25 % favorable failure modes.

SIGNIFICANCE

Occlusal veneers showed promising results as a retainer for cantilever RBFDPs. The lingual extension might increase debonding resistance. Nevertheless, conservative designs with lingual and proximal bevels are to be recommended, irrespective of the level of tooth wear.

Deep margin elevation-Present status and future directions

OBJECTIVE

Deep margin elevation (DME) is a treatment approach to relocate the cervical margin of teeth with subgingival defects to a supragingival position with a direct restoration to facilitate rubber dam isolation, impression taking, and bonding of indirect restorations. This article provides an overview of the current scientific evidence on DME and future directions for research.

OVERVIEW

The review included 38 studies on DME, most conducted in vitro. These studies indicate that DME has no detrimental effect on the fracture resistance of restored teeth. Evidence on the impact of DME on marginal quality is conflicting, but most in vitro studies observed no negative effect. Clinical studies, most comprising small patient cohorts, demonstrated favorable restorative outcomes and suggest that DME restorations made with scrupulous care are compatible with periodontal health. Bleeding on probing may occur more frequently at sites with DME, though evidence on this is not unequivocal.

CONCLUSIONS

Current evidence, based largely on laboratory studies and limited clinical data, supports DME as a viable approach to restore teeth with localized subgingival defects. However, further clinical studies with long-term follow-ups are required to provide corroborative evidence.

CLINICAL SIGNIFICANCE

Current evidence suggests that DME is a viable approach to restore teeth with localized subgingival defects as a possible alternative to surgical crown lengthening. Proper working field isolation, meticulous care in the bonding and buildup procedure, and biofilm removal through patient-performed oral hygiene and professional maintenance care are crucial. As scant clinical trial-based evidence is available today, further research is needed to evaluate the long-term performance of DME restorations and their impact on periodontal health.

Deep Margin Elevation: Current Concepts and Clinical Considerations: A Review

Dietschi and Spreafico first proposed deep margin elevation (DME) in 1998 to address the multiple clinical problems associated with sub-gingival margins, where sub-gingival margins will be repositioned coronally using composite resin restorations. Given that dentistry is directing towards conservatism, its use is currently trending. Materials and Methods: a search was performed through PubMed, Scopus, and Google Scholar search engines to obtain relevant articles with no time restriction. Results: With biological width taken into consideration, well-defined and polished sub-gingival restorations are compatible with periodontal health. Marginal integrity in the DME technique seems to be affected by the type of adhesive, restoration, and incremental layering of the restoration. Regarding fracture resistance, DME has no significant effects. Conclusion: The DME technique seems to be a minimally invasive alternative to surgical crown lengthening (SCL) and orthodontic extrusion (OE) with respect to biological width. Well-controlled clinical trials are limited in this field; further long-term follow-up studies emphasizing the periodontal outcomes and prevention of complications are needed.

Effect of Additional Dry Heat Curing on Microflexural Strength in Three Types of Resin Composite: An In Vitro Study

Aim: Additional dry heat curing is a method that favorably influences the mechanical properties of an indirect resin composite restoration. Microflexural strength is a property currently applied for the evaluation of indirect resin composite restorations. The aim of the present study was to assess the effect of additional dry heat curing on microflexural strength in three types of direct-use resin composites. Materials and Methods: This in vitro study consisted of 70 resin composites samples made with a 6 × 2 × 1 mm metal matrix and divided into seven experimental groups, which included Gr1a: Tetric N-Ceram without additional dry heat curing (n = 10); Gr1b: Tetric N-Ceram with additional dry heat curing (n = 10); Gr 2a: Filtek Z350 XT without additional dry heat curing (n = 10); Gr2b: Filtek Z350 XT with additional dry heat curing (n = 10); Gr3a: Filtek Z250 without additional dry heat curing (n = 10); Gr3b: Filtek Z250 with additional dry heat curing (n = 10); and Gr4: SR Nexco Paste (control) without additional dry heat curing (n = 10). The samples were stored in distilled water at 37 °C for 24 h. A universal testing machine with a 2000 N load cell at a speed of 1 mm/min was used to assess flexural strength. The data were analyzed with a parametric ANOVA test with Tukey’s post hoc intergroup factor (for groups without heat treatment) and a nonparametric Kruskall Wallis test with Bonferroni’s post hoc (for groups with heat treatment). In addition, the comparison of independent groups in each resin composite type with and without heat treatment was performed with a Mann Whitney U test. A significance level of p < 0.05 was considered. Results: The Filtek Z250 resin composite with and without additional dry heat curing presented the highest microflexural strength values with 137.27 ± 24.43 MPa and 121.32 ± 9.74 MPa, respectively, while the SR Nexco Paste (control) resin composite presented the lowest microflexural strength values with 86.06 ± 14.34 MPa compared to all the resin composites with additional dry heat curing. The Filtek Z250 and Filtek Z350XT resin composites with and without additional dry heat curing presented significantly higher microflexural strength versus the SR Nexco (p < 0.05) and Tetric N-Ceram (p < 0.05) resin composites. In addition, the Filtek Z350XT and Tetric N-Ceram resin composites with additional dry heat curing showed significantly higher microflexural strength (p < 0.05) compared to those without additional dry heat curing. Conclusions: The Filtek Z250 and Z350XT resin composites had significantly higher microflexural strength values with and without additional dry heat curing. In addition, the Filtek Z350XT and Tetric N-Ceram resin composites subjected to additional dry heat curing showed significantly higher microflexural strength compared to when they did not receive the same procedure, a situation that did not occur with the Filtek Z250 resin composite.

Deep Margin Elevation: A Literature Review

A conservative approach for restoring deep proximal lesions is to apply an increment of composite resin over the preexisting cervical margin to relocate it coronally, the so-called “deep margin elevation” (DME). A literature search for research articles referring to DME published from January 1998 until November 2021 was conducted using MEDLINE (PubMed), Ovid, Scopus, Cochrane Library and Semantic Scholar databases applying preset inclusion and exclusion criteria. Elevation material and adhesive system employed for luting seem to be significant factors concerning the marginal adaptation of the restoration. This technique does not affect bond strength, fatigue behavior, fracture resistance, failure pattern or repairability. DME and subgingival restorations are compatible with periodontal health, given that they are well-polished and refined. The available literature is limited mainly to in vitro studies. Therefore, randomized clinical trials with extended follow-up periods are necessary to clarify all aspects of the technique and ascertain its validity in clinical practice. For the time being, DME should be applied with caution respecting three criteria: capability of field isolation, the perfect seal of the cervical margin provided by the matrix, and no invasion of the connective compartment of biological width.