Liners and bases in general dentistry

Evaluation of Physical Properties in Carboxymethyl Chitosan Modified Glass Ionomer Cements and the Effect for Dentin Remineralization: SEM/EDX, Compressive Strength, and Ca/P Ratio

OBJECTIVE

 The aim of this article was to evaluate the effects of modifying glass ionomer cement (GIC) with carboxymethyl chitosan (CMC) on surface morphology and remineralization outcomes by examining dentin morphology and calcium ion composition changes.

MATERIALS AND METHODS

 Thirty holes in a cylindrical acrylic mold were filled with three groups of restorative materials: GIC, GIC modified with CMC (GIC-CMC) 5%, and GIC-CMC10%. The surface morphology of each group's materials was observed using scanning electron microscopy (SEM). The compressive strength measurement was performed using a universal testing machine. The dentin remineralization process was performed by applying GIC, GIC-CMC5%, and GIC-CMC10% materials for 14 days on demineralized dentin cavities treated with 17% ethylenediamine tetraacetic acid (EDTA) for 7 days. A morphological evaluation was conducted using SEM. The calcium ion composition and calcium-to-phosphorous (Ca/P) ratio were examined using an energy-dispersive X-ray (EDX).

STATISTICAL ANALYSIS

 The one-way ANOVA and post-hoc Bonferroni test were used to evaluate the compressive strength within the three groups (p < 0.05). The Kruskal-Wallis and subsequent Mann-Whitney U tests were conducted to compare the four groups of calcium ions (p < 0.05).

RESULTS

 The modification of GIC with CMC affected the morphological changes in the materials in the form of reduced porosity and increased fractures. A significant difference was found in compressive strength between the GIC-CMC modification materials of GIC-CMC5% and GIC-CMC10% and the GIC control group. The dentin tubule morphology and surface changes were observed after applying GIC, GIC-CMC5%, and GIC-CMC10% materials for 14 days, as evaluated by SEM. The EDX examination showed an increase in calcium ion content and hydroxyapatite formation (Ca/P ratio) after applying the GIC-CMC10% material.

CONCLUSION

 The surface porosity of the GIC modification material with the addition of CMC tended to decrease. However, an increase in cracked surfaces that widened, along with the rise in CMC percentage, was found. This modification also reduced the compressive strength of the materials, with the lowest average yield at 10% CMC addition. Therefore, the modification of GIC with CMC affects changes in morphology, calcium ion composition, and Ca/P ratio in demineralized dentin.

Orifice barrier preferences for coronal restoration of root filled teeth by endodontists and other dental practitioners in Australia: A questionnaire survey

OBJECTIVES

To compare the use of orifice barriers (OB) in root-filled teeth (RFT) between specialist endodontic practitioners (SEP) and general and other specialist practitioners (GDP+), and identify common materials, reasons for selection, and techniques.

METHODS

An online survey was distributed to SEP and GDP+ practising in Australia. Demographic and multiple-choice questions relating to material selection and technique choices were asked to evaluate and relate usage patterns to practising and training backgrounds. Fisher's exact tests were undertaken to compare categorical variables across practitioner groups. Significance level was set at p<.05.

RESULTS

There were 457 eligible responses: 393(86%) GDP+ and 64(14%) SEP. Of 429 reporting endodontically treating or restoring teeth, 317(73.9%) placed OB; preferred depth of root filling removal by most (91.8%) was ≤ 2 mm, with more SEP preferring 2 mm than GDP+(p=.02). Preferred materials for OB were conventional and resin-modified GIC (GIC), resin composite materials (RC), Cavit™ and zinc polycarboxylate cement (ZPC). 'Ease of use' was a common reason among all practitioners for GIC and RC. Significantly more SEP(p<.001) chose ZPC in all teeth and more commonly because of 'Ease of use' for both posterior (p<.001) and anterior (p=.002) teeth. All ZPC-using SEP preferred using a paste-filler/lentulo spiral, significantly more than GDP+ for posterior (p<.001) and anterior (p=.002) teeth. Cavit™ was often chosen for 'Sealing ability'.

CONCLUSIONS

OB were widely placed by dental practitioners in Australia, with a small group of materials selected, most commonly for ease of use or sealing ability. The findings of this study suggest that further research should be undertaken to investigate the relative performance of these materials as OB and to inform the clinician's choices when restoring RFT.

Acemannan-containing bioactive resin modified glass ionomer demonstrates satisfactory physical and biological properties

Background/purpose

Resin-modified glass ionomers (RMGIs) have been recommended as liner and cement to provide the teeth with mechanical support, a chemical barrier, and thermal insulation. Acemannan, the main polysaccharide extracted from Aloe vera, is a promising inductive material in vitro and in vivo. This study aimed to develop acemannan-containing bioactive resin-modified glass ionomers (RMGIs).

Materials and methods

Acemannan (3%, 5%, and 10%) was added to the three types of RMGIs (RU-HBM1/Fuji II LC/Vitrebond) to generate 3%, 5%, and 10% aceRMGIs (aceRU/aceFuji/aceVB). The materials were evaluated for depth of cure/flexural strength/cumulative fluoride ion release. Cell viability and vascular endothelial growth factor (VEGF) and bone morphogenetic protein-2 (BMP-2) secretion were determined using MTT/apoptosis/necrosis assays, and ELISA kits, respectively. RMGI without acemannan were used as controls.

Results

The aceRMGIs met the ISO requirements for depth of cure and flexural strength. Adding 10% acemannan increased the cumulative fluoride release in the RU and FJ groups, but slightly decreased it in the VB group (P < 0.05). The MTT assay revealed 10% aceRU and all aceFJ groups significantly increased cell viability compared with each control group (P < 0.05). Apoptosis/necrosis assay showed the biocompatibility of all aceRMGIs. Adding acemannan to RMGIs significantly induced VEGF expression in a dose dependent manner while 5% and 10% aceRU significantly induced BMP-2 expression compared with RU group (P < 0.05).

Conclusion

We conclude that 5-10% acemannan in RMGI is the optimal concentration based on its physical properties and ability to induce pulp cell proliferation and growth factor secretion.

Thermophysical properties and bonding with composite resin of premixed mineral trioxide aggregate for use as base material

Dental bases require low thermal conductivity and good mechanical properties, such as bonding with composite resins. This study aims to elucidate the physicochemical properties of premixed mineral trioxide aggregate (MTA) for its suitability as a dental base and to explore the optimal adhesive strategy with composite resin. The thermal conductivity and compressive strength of this premixed MTA are 0.12 W/(m•K) and 93.76 MPa, respectively, Which are deemed adequate for its application as dental base. When bonded to composite resin, the use of 37% phosphoric acid etching before applying the Clearfil SE bond significantly reduced the bonding strength between composite resin and premixed MTA. This was because the compressive strength and Vickers hardness of premixed MTA decreased, and tricalcium silicate was dissolved from the surface during acid etching. Therefore, it is recommended to avoid using 37% phosphoric acid etching when bonding premixed MTA and composite resin as a dental base.

Subcutaneous tissue reaction to a novel nano zinc oxide eugenol dental cement

BACKGROUND

Zinc oxide eugenol (ZOE) cement is a popular dental material due mainly to its analgesic, antibacterial and anti-inflammatory effects. The formulation of ZOE cement from nano particle-sized zinc oxide (ZnO) has the potential to increase these properties as well as reduce its adverse effects to the surrounding tissues.

OBJECTIVE

This study evaluated the subcutaneous tissue response towards nano ZOE cements (ZOE-A and ZOE-B) in comparison to conventional ZOE (ZOE-K).

METHODS

Test materials were implanted into 15 New Zealand white rabbits. Tissue samples were obtained after 7, 14, and 30 days (n = 5 per period) for histopathological evaluation of inflammatory cell infiltrate, fibrous tissue condensation, and abscess formation.

RESULTS

ZOE-A showed the lowest score for the variable macrophage and lymphocyte at day 7. Both ZOE-A and ZOE-B presented lower fibrous tissue condensation and abscess formation compared to conventional ZOE-K. By day 30, ZOE-A exhibited less lymphocytic and neutrophilic infiltrate compared to the other materials, while ZOE-B had the lowest score for macrophages. ZOE-K exerted higher inflammatory cell response at almost all of the experimental periods. All of the materials resulted in thin fiber condensation after 30 days.

CONCLUSIONS

Rabbit tissue implanted with ZOE-A and ZOE-B showed better response compared to ZOE-K.

Biological considerations of dental materials as orifice barriers for restoring root-filled teeth

There is ample published literature regarding the technical aspects of restoring root-filled teeth, but little concerning the biological impacts, consequences, and criteria for the selection of direct restorative materials following endodontic treatment. The provision of an effective coronal seal in addition to a sound root filling is known to be important in the prevention of root canal infection. This review seeks to explore the evidence concerning the selection of dental materials in the restoration of root-filled teeth, specifically with a close examination of the properties of commonly used materials as orifice barriers. © 2023 Australian Dental Association.

Evaluating fluoride uptake of dentin from different restorative materials at various time intervals - In vitro study

Background

Glass ionomer cement is very popular in clinical practice due to their antibacterial and cariostatic properties, which is totally dependant on the amount of fluoride release and uptake by dentine. The short-term and long-term fluoride uptake by dentine from commercially available restorative materials like nano-ionomer, zirconia reinforced glass ionomer cement and flowable composite is of clinical interest.

Objective

To evaluate and compare Nano-ionomer, Zirconia reinforced glass ionomer, and flowable composite resin for the fluoride uptake by dentin at different time intervals.

Results

One-way ANOVA (Tukey-Kramer Multiple Comparison Test) was applied to test the comparison of mean values of all parameters compared together. The student's paired 't' test was applied to compare groups. The fluoride uptake was evaluated at 3 days and 42 days. At 3 days dentin showed higher fluoride uptake with Zirconomer (Group Z) as compared to Ketac N100 and SDR Composite which was statistically significant. At 42 days higher fluoride uptake was seen in Ketac N100 (Group K) as compared to Zirconomer and SDR composite which was also statistically significant.

Conclusion

Fluoride uptake by dentine was seen in all study materials. Fluoride uptake by dentine at 3 days was seen maximum in Zirconomer, whereas fluoride uptake at 42 days was more in Ketac N100.

Vital pulp therapy following pulpotomy in immature first permanent molars with deep caries using novel fast-setting calcium silicate cement: A retrospective clinical study

OBJECTIVES

To compare the success rate of vital pulp therapy following complete pulpotomy in immature first permanent molars, during caries treatment, using novel fast-setting calcium silicate cement (Novel CSC) versus MTA.

METHODS

Six- to eight- years old children, who received pulpotomy of first immature permanent molar using one layer novel CSC (Protooth) or two layers slow-setting MTA (MTA Angelus) covered with glass ionomer were recalled for radiographic and clinical evaluation after two years. The effects of cement type, age, gender, jaw, anesthesia type, and restoration type were assessed on the clinical success of pulpotomy and continued root formation (apexogenesis) as the treatment outcome.

RESULTS

Out of 366 included teeth in the study, 316 teeth were available for statistical analysis. The mean observation time was 28.2 ± 2.7 months. Novel CSC showed significantly higher clinical success rate (93.1%) compared to MTA (84.5%). Restored teeth with stainless steel crowns after pulpotomy and treatments performed under general anesthesia had a statistically significant effect on treatment outcome in contrast to age, gender, and jaw type.

CONCLUSION

The observations of this retrospective study suggested that the success rate of vital pulp therapy following complete pulpotomy using one layer fast-setting novel CSC was significantly higher than slow-setting MTA covered with glass ionomer. Treatment under general anesthesia and restoration using stainless steel crowns influenced the treatment outcome.

CLINICAL SIGNIFICANCE

Novel fast-setting calcium silicate cement is a promising new biomaterial for vital pulp therapy in immature permanent molars that allows complete root formation overtime with apexogenesis. Clinicians must also be aware of the importance of immediate definitive restoration and proper sealing and isolation in vital pulp therapy.

The influence of a liner on deep bulk-fill restorations: Randomized clinical trial

OBJECTIVE

The aim of this study was to evaluate the influence of a liner on the clinical performance of deep posterior restorations performed with bulk-fill composite.

METHODS

30 subjects received two restorations on deep preparations in posterior teeth, without pulpal exposure, after selective carious-tissue removal in one-stage. The internal walls reached the inner quarter of dentin, but with a radiographically detectable zone of firm dentin remaining. The pulpal protection using a layer of glass ionomer composite liner (Ionoseal, Voco) was applied in just one preparation. The adhesive system Futurabond U (Voco) was applied in all preparations, which were restored with the bulk-fill pure Ormocer nanohybrid composite (Admira Fusion Xtra - Voco), in up to 4 mm thick increments. All restorations were evaluated using the FDI criteria after 7 days, 6, 12 and 24 months postoperatively.

RESULTS

After 24-months, 25 patients attended the recall and 50 restorations were evaluated. The Fisher's statistical analysis (5%) showed no difference between the techniques for the esthetic, functional and biological properties. No postoperative sensitivity was reported for both groups.

CONCLUSION

The application of a liner did not influence the clinical performance of deep restorations with bulk-fill Ormocer composite.

CLINICAL RELEVANCE

The application of a liner with a GIC-based material did not have a significant effect on the clinical performance of bulk-fill restorations and seems to be unnecessary for the material tested.

Bond strength between dentine and a novel fast-setting calcium silicate cement with fluoride

The aim of this study was to evaluate the dentine bond strength of a novel fast-setting calcium silicate cement (Protooth) versus a calcium hydroxide-based cement (Dycal), a calcium silicate cement (ProRoot MTA), and a glass ionomer cement (Ketac-Molar). Mid-root dentine slices of 1 mm thickness were obtained from human maxillary incisors. After enlarging the lumen of the canal to 1.3 mm, the cavities were randomly filled with test materials. Samples were immersed in physiological-like solution. The push-out bond strength was tested on days 1, 28, and 180 (n = 12). Failure types of bonding were determined using a stereomicroscope. We analysed the data using linear regression. Dycal and day 1 were considered as reference for cement type and assessment time, respectively. Protooth, Ketac-Molar, and ProRoot MTA demonstrated higher push-out bond strength than Dycal. The push-out bond strength in the Protooth group increased on day 28 and 180. The bond strength of Ketac-Molar was significantly reduced on day 28. Dycal showed a significant decrease in bond strength on day 180 compared with that on day 1 and 28. Mixed failure was the dominant failure type. Protooth bonding to dentine was increased with time, in contrast to that of ProRoot MTA, Dycal, and Ketac-Molar, as a function of time.

Direct pulp capping of primary molars using a novel fast-setting calcium silicate cement: a randomized clinical trial with 12-month follow-up

Objective: Novel fast-setting calcium silicate cement with fluoride (Protooth) has been developed for potential applications in tooth crowns. The aim of this study was to evaluate the success rate of direct pulp capping in primary molars using two-layer mineral trioxide aggregate (MTA) and overlying glass ionomer cement versus one-layer novel calcium silicate cement with 4 to 10 minutes setting time. Materials and methods: Ninety bilaterally symmetrical primary molars in the same jaw in 45 patients aged 5 to 7 years were included. Exposed pulps following caries removal were randomly capped with one-layer novel calcium silicate cement or two-layer MTA and glass ionomer cement. All cavities were filled with amalgam. Clinical and radiographic evaluations were performed after six and twelve months. 41 patients were available for the evaluations at the end of the 12-month follow-up. Results: The overall success rate of direct pulp capping, in a split-mouth design, using MTA covered with glass ionomer cement or one-layer novel calcium silicate cement after 12 months were 90% (37 out of 41 cases) and 85% (35 out of 41 cases), respectively, without statistically significant differences after 6 and 12 months. Conclusion: Within the limitations of this study, clinical and radiographic evaluations suggested one-layer novel calcium silicate cement would be successfully used in direct pulp capping of primary molars as a practical alternative to two-layer MTA and overlying glass ionomer cement.

Surface morphological and mechanical properties of zinc oxide eugenol using different types of ZnO nanopowder

Zinc oxide eugenol (ZOE) cements are generally made up of 80%-90% ZnO powder while the remaining content consists of eugenol bonding resin. ZnO structure plays a major role in the morphology and mechanical properties of ZOE. In this study, we investigated the effects of different particle sizes/shapes of ZnO particles on the surface and mechanical properties of ZOE. Three samples were prepared namely ZnO-Ax, ZnO-B and ZnO-K. The crystallite sizes calculated from XRD were 37.76 nm (ZnO-Ax), 39.46 nm (ZnO-B) and 42.20 nm (ZnO-K) while the average particle sizes obtained by DLS were 21.11nm (ZnO-Ax), 56.73 nm (ZnO-B) and 2012 nm (ZnO-K). Results revealed that the compressive strengths of ZOE-Ax and ZOE-B were improved by 87.92% and 57.16%, respectively, relative to that of commercial ZOE-K. Vickers hardness test demonstrated that the hardness of ZOE-Ax and ZOE-B also increased by 74.9% and 31.1%, respectively. The ZnO-Ax nanostructure possessed a small average particle size (21.11 nm), a homogeneous size distribution (DLS) and an oxygen-rich surface (from EDS and elemental mapping). Meanwhile, ZnO-B exhibited a slightly larger average particle size of 56.73 nm compared with that of other samples. Sample ZnO-Ax demonstrated the highest compressive strength which was attributed to its large particle surface area (21.11 nm particle size) that provided a large contact area and greater interfacial (or interlock) bonding capability if compared to that of ZnO-K sample (2012 nm particle size).

Novel metformin-containing resin promotes odontogenic differentiation and mineral synthesis of dental pulp stem cells

This represents the first report on the development of metformin-containing dental resins. The objectives were to use the resin as a carrier to deliver metformin locally to stimulate dental cells for dental tissue regeneration and to investigate the effects on odontogenic differentiation of dental pulp stem cells (DPSCs) and mineral synthesis. Metformin was incorporated into a resin at 20% by mass as a model system. DPSC proliferation attaching on resins was evaluated. Dentin sialophosphoprotein (DSPP), dentin matrix phosphoprotein 1 (DMP-1), alkaline phosphatase (ALP), and runt-related transcription factor 2 (Runx2) genes expressions were measured. ALP activity and alizarin red staining (ARS) of mineral synthesis by the DPSCs on resins were determined. DPSCs on metformin-containing resin proliferated well (mean ± SD; n = 6), and the number of cells increased by 4-fold from 1 to 14 days (p > 0.1). DSPP, ALP, and DMP-1 gene expressions of DPSCs on metformin resin were much higher than DPSCs on control resin without metformin (p < 0.05). ALP activity of metformin group was 70% higher than that without metformin at 14 days (p < 0.05). Mineral synthesis by DPSCs on metformin-containing resin at 21 days was 9-fold that without metformin (p < 0.05). A novel metformin-containing resin was developed, achieving substantial enhancement of odontoblastic differentiation of DPSCs and greater mineral synthesis. The metformin resin is promising for deep cavities and perforated cavities to stimulate DPSCs for tertiary dentin formation, for tooth root coatings with metformin release for periodontal regeneration, and for root canal fillings with apical lesions to stimulate bone regeneration.

Effect of Different Liners on Pulpal Outcome after Partial Caries Removal: A Preliminary 12 Months Randomised Controlled Trial

Aim: The aim of this double-blinded parallel randomised controlled trial was to compare the effect of different liners on 12-month pulp health outcomes after partial caries removal (PCR) with composite restorations in permanent molars. Methods: The study was registered at clinicaltrials.gov with registration No. NCT0328695 and conducted in the Department of Conservative dentistry and Endodontics, Post Graduate Institute of Dental Sciences Rohtak with no external financial support. One hundred and ninety-eight participants (116 males, 82 females and age 14–54 years) with vital permanent mature mandibular molars having deep caries involving two-thirds or more of dentin were randomised to calcium hydroxide (CH), resin-modified GIC (RMGIC) and no liner (DC) groups after PCR. After a follow-up time of 12 months, success was defined as positive response to pulp sensibility and absence of periapical alterations. Results: Categorical variables were compared using chi-square test. Two analytical approaches were used, such as intention-to-treat and per-protocol approach. Success rates in per-protocol approach were 96.8, 96.5, and 94.6% for CH, RMGIC and DC groups, respectively with no significant difference between 3 groups (p = 0.811). None of the baseline variables had any significant influence on the treatment success. Conclusion: Partial caries excavation has a high success rate to treat deep carious lesions in permanent teeth after 12 months of follow-up, indicating that the retention of carious dentin does not interfere with pulp vitality or restoration survival. Also, the success of the treatment is independent of the lining material used over the demineralized dentin.

In vitro cytotoxic evaluation of novel fast-setting calcium silicate cement compositions and dental materials using colorimetric methyl-thiazolyl-tetrazolium assay

A novel fast-setting calcium silicate cement with fluoride (CSC) has been developed for potential application in tooth crowns. This study compared the cytotoxicity of CSC compositions and a variety of dental materials. We tested CSC compositions (Protooth), MTA, Biodentine, Ketac Molar, Fuji II LC, Vitrebond, DeTrey Zinc, Dycal, and IRM, DMEM (negative control) and 1% NaOCl (positive control). After setting of cements for 24 h, specimens were immersed in DMEM for 24 h to obtain material elutes. The elutes were serially diluted in serum-free DMEM to obtain three dilutions. L929 mouse fibroblast cells (1 × 10⁴ cells per well) were treated for 24 h with elute dilutions (n = 3). Cytotoxicity was determined using methyl-thiazolyl-tetrazolium assay in triplicate. CSC compositions, MTA, and Biodentine showed no significant reduction in cell viability compared to DMEM. There was no significant difference in cell viability, at any of three dilutions, between CSC compositions and either MTA or Biodentine. Cytotoxicity was significantly lower for CSC compositions than for Vitrebond, DeTrey Zinc, Dycal, IRM, and 1% NaOCl, at all three dilutions, and undiluted Fuji II LC elute. In contrast to resin-modified glass ionomers, zinc phosphate cements, Dycal, and IRM, the CSC compositions showed no cytotoxic potential.

Evaluation of calcium release and pH value of light-cured cavity liners for pulp-capping materials

Abstract Introduction Cavity liners based calcium hydroxide present low strength and high solubility that is consider a disadvantage. In order to enhance these properties it was developed a light-cured cavity liner based calcium hydroxide containing resin. Objective The purpose of this study was to evaluate the pH and calcium release of light-cured cavity liners. Material and method There were prepared specimens (n=10) with the Ultra-Blend ® plus, Biocal® (light cured cements) and Hydro C® (control). The samples were stored in 10 mL of distilled water and maintained at 37 °C. After 24 hours, 7, and 14 days, there were analyzed pH and the release of calcium levels. The data were statistically analyzed by ANOVA and Tukey test (α = 0.05). Result The results of pH showed Hydro C > Ultra-Blend plus > Biocal. Biocal presented worst calcium release. Conclusion Light-cured materials present lower calcium release and alteration in pH values.

An end to linings under posterior composites?

BACKGROUND AND OVERVIEW

There is an uncertainty among dentists as to whether to place a lining under a direct posterior composite restoration and, if so, what material or combination of materials to use. In this article, the authors consider the evidence for the placement of a lining under posterior composites of different depths, including indications and contraindications for different lining materials.

CONCLUSIONS

The available evidence does not support the use of linings under direct, bonded posterior composites, unless being placed in deep cavities for therapeutic reasons.

PRACTICAL IMPLICATIONS

The best available evidence indicates that dentists can place posterior composites without linings, except for therapeutic purposes, with no adverse effect on postoperative complications, with possible improvements in performance in clinical service, and with efficiency savings in chairside time.

Physical-Mechanical Properties and Micromorphology of Calcium Cements Exposed to Polyacrylic and Phosphoric Acids

OBJECTIVE

To evaluate if physical and mechanical properties of self-curing calcium hydroxide cements were affected by contact with polyacrylic and phosphoric acids.

MATERIALS AND METHODS

Resin-containing (Life (LF)) and resin-free (Hydro C (HyC)) materials were subjected to polyacrylic acid conditioning and rinsing (POL); phosphoric acid conditioning and rinsing (PHO); rinsing only; and no treatment (n = 10). Water sorption/solubility, release of hydroxyl ions (pH), roughness (Ra), and impact resistance were evaluated. Additional samples (n = 1) were prepared for scanning electron microscopy (SEM) analysis of the surface morphology. Data were analyzed by two-way ANOVA and Tukey post hoc test (P < 0.05).

RESULTS

Water sorption was significantly higher for LF when in contact with PHO and lower for POL (P < 0.05). The mean solubility was higher with POL for both cements (P < 0.05). PHO increased the mean surface roughness for HyC (P < 0.01); a significant decrease was noted for LF after contact with both acids (P < 0.01). PHO promoted lower release of hydroxyl ions on both cements (P < 0.05). For LF, rinsing, PHO, and POL presented similar morphology, differing from the control group. For HyC, PHO and POL presented similar morphology, differing from the control group.

CONCLUSIONS

PHO had a negative effect on the physical properties of the cements tested, except for the solubility test. POL affected roughness and solubility of HyC cement.

CLINICAL RELEVANCE

Clinical procedures that require polyacrylic and phosphoric acid conditioning must be done carefully on self-curing calcium hydroxide cements in order to avoid negative impact on their properties.

Diametral tensile strength of novel fast-setting calcium silicate cement

Novel fast-setting calcium silicate cement with fluoride (CSC) has been developed for potential applications in tooth crown. The aim of this study was to test the diametral tensile strength (DTS) of different CSC compositions in humid condition on day1, 28, and 180. We tested 'bond CSC' with 3.5% fluoride and no radiocontrast, 'CSC' with 3.5% fluoride and 10% radiocontrast, 'ultrafast CSC' with 3.5% fluoride and 20% radiocontrast, 'high fluoride CSC' with 15% fluoride and 25% radiocontrast, Biodentine, and MTA. We filled the cements after mixing to cylindrical molds. Specimens were stored in >95% humidity. DTS was measured at each time point. CSC compositions had statistically higher DTS compared to MTA and Biodentine on day1. Bond CSC showed higher DTS versus all cements, except CSC, at all time points. DTS of all cements, except Biodentine, significantly increased in humid condition on day28 and day180 compared to day1.

Calcium hydroxide liners: a literature review

OBJECTIVE

This review integrates the literature on cavity liners and current concepts of pulp protection with the aim of establishing a better understanding of the role of calcium hydroxide as a cavity liner.

MATERIALS AND METHODS

A search was conducted through PubMed, MEDLINE, and Ovid for articles with the criteria for the following terms: cavity liners and bases, pulp protection, and calcium hydroxide liners. No specific inclusion or exclusion criteria were applied as to what articles would be included in this review. It was hoped that the extent of the literature reviewed would be as comprehensive as possible.

CONCLUSION

This review underlines the fact that calcium hydroxide liners should only be used in the deepest spots in the cavity where the remaining dentine thickness is ≤0.5 mm. A protective layer of resin-modified glass ionomer should always follow the application of calcium hydroxide liners.

Effect of Different Intermediary Bases on Microleakage of a Restorative Material in Class II Box Cavities of Primary Teeth

Introduction

The aim of this in vitro study was to assess and compare the effect of different intermediary bases on microleakage between tooth and a nanocomposite interface in Class II box cavities in primary teeth.

Methods

Standard Class II box cavities were prepared in 52 primary molars and randomly divided into 9 groups according to the intermediary base used (Multicore Flow, Fuji II LC, SDR, Smart Dentin Replacement, and Biodentine). All specimens were subjected to thermocycling and prepared for microleakage testing and evaluation.

Results

There was significant difference in the mean ranks of microleakage between the 9 groups, which was observed in the gingival side (p<0.0001) and the occlusal side (p<0.0001). The mean ranks microleakage was significantly higher with experimental SDR, experimental Multicore Flow, and positive control materials when compared with the other 6 groups. The microleakage mean ranks were statistically significantly lower in experimental Fuji II LC, experimental Biodentine, and all negative control groups when compared with the other 3 groups.

Conclusions

Microleakage is affected by the application of intermediate material. Experimental Biodentine and Fuji II LC showed the lowest microleakage while experimental SDR and experimental Multicore Flow showed the highest microleakage.

Cavity lining in primary teeth

DATA SOURCES

Embase, Medline, Cochrane Central, Biomed Central and Open Grey databases and bibliographies of identified studies.

STUDY SELECTION

Randomised controlled trials investigating humans with primary caries lesions receiving operative treatment involving caries removal and restoration, with minimum two treatment groups comparing different cavity treatments before restoration (no lining versus lining) were included.

DATA EXTRACTION AND SYNTHESIS

Data were extracted independently by two reviewers and study quality assessed using the Cochrane risk of bias tool. Random effect meta-analysis was carried out.

RESULTS

Three studies involving a total of 89 patients were included. All the studies involved primary teeth and were conducted in Brazil. Follow-up periods ranged from 26-53 months. All the studies were considered to be at high risk of bias. Restoring the cavity without lining did not significantly affect the risk of failure. The quality of the evidence was low.

CONCLUSIONS

Current evidence does not support strong recommendations to use or not to use liners after caries removal and before restoring cavities. Our findings are restricted to primary teeth after selective excavation, with only one liner (calcium hydroxide) being used for comparison.

Cavity lining after excavating caries lesions: meta-analysis and trial sequential analysis of randomized clinical trials

OBJECTIVES

After removal of dentine caries lesions, cavity lining has been advocated. Non-clinical data support this approach, but clinical data are sparse and ambiguous. We aimed at evaluating the benefits and harms of cavity lining using meta-analysis and Trial Sequential Analysis.

DATA

We included randomized clinical trials comparing restorations without versus with cavity lining for treating primary caries lesions. Only trials reporting failure (defined as need to re-retreat) after ≥1 year follow-up were included. Trial selection, data extraction, and risk of bias assessment were conducted independently by two reviewers. We conducted random-effects intention-to-treat and per-protocol meta-analyses, and Trial Sequential Analysis to control for random errors.

SOURCES

Electronic databases (PubMed, Embase, CENTRAL) were systematically screened, and hand searches and cross-referencing performed.

STUDY SELECTION

From 128 studies, three randomized trials (89/130 patients or teeth), all treating primary teeth, were included. The trials had high risk of bias. All trials compared no lining versus calcium hydroxide lining after selective caries removal followed by adhesive restoration. Follow-up was 36 to 53 months. Restoring the cavity without lining did not significantly affect the risk of failure (intention-to-treat relative risk (RR) (95% confidence interval) 0.71 (0.49-1.04), per-protocol RR 0.52 (0.24-1.10). According to Trial Sequential Analysis, no firm evidence was reached. The quality of evidence was very low.

CONCLUSIONS

Strong recommendations for using cavity liners are unsubstantiated, but firm evidence for omitting lining is also unavailable. Our findings apply only to primary teeth and calcium hydroxide liner.

CLINICAL SIGNIFICANCE

Whilst lining is frequently performed in dental practice, very few randomized clinical trials investigated this issue. The three trials included in this review treated deciduous teeth and did not find lining with calcium hydroxide beneficial. Lining is not supported by sufficient clinical evidence.