Analysis of pulpal reactions to restorative procedures, materials, pulp capping, and future therapies

Delayed vs. immediate placement of restorative materials over Biodentine and RetroMTA: a micro-shear bond strength study

BACKGROUND

The aim of the present study was to investigate the micro-shear bond strength (µSBS) of various restorative materials applied on two different fast-setting calcium silicate-based materials and to evaluate the effect of restoration time on µSBS.

METHODS

A total of 180 acrylic blocks with a cavity in the center were randomly divided into 2 main groups according to the capping material to be used (Biodentine or RetroMTA). The specimens were also randomly divided into 3 groups according to the restoration time (3 min, 12 min, 24 h). After the specified waiting periods, glass hybrid material (EQUIA Forte HT), resin composite (Filtek Z550) and light-cured calcium silicate material (Theracal LC) were placed on the specimens with tygon tubes. The specimens were kept for 24 h and then subjected to µSBS test. Statistical analysis was performed by 3-way ANOVA followed by Tukey test for pairwise comparisons (α = 0.05).

RESULTS

There is a statistically significant difference (p < 0.05) between the µSBS values obtained by applying resin composite on RetroMTA after different setting times (24 h > 12 min > 3 min). The µSBS obtained for the Biodentine-resin composite at the end of the 3 min setting time is significantly lower (p < 0.05) than the µSBS values at 12 min and 24 h. For both calcium silicate cements, at the end of all time periods, the µSBS obtained when resin composite was applied at the end was higher than the other materials (p < 0.05).

CONCLUSIONS

For Biodentine-resin composite bonding, the manufacturer's recommendation of 12 min can be considered an appropriate time, whereas for RetroMTA-resin composite bonding, the µSBS increased as the waiting time increased. Regardless of the waiting time, it is recommended to prefer direct composite resin restoration over Biodentine and RetroMTA.

Retrospective clinical study on the performance and aesthetic outcome of pressed lithium disilicate restorations in posterior teeth up to 8.3 years

OBJECTIVES

Evaluation of cumulative survival and complication rate of monolithic lithium disilicate inlays and partial crowns performed by supervised undergraduate students up to 8.3 years of clinical service.

MATERIALS AND METHODS

In this retrospective clinical study 143 lithium disilicate posterior restorations (IPS e.max Press) were examined according to the FDI criteria. A standardised questionnaire was used to determine patient satisfaction. The aesthetic outcome was evaluated by dentists and dental technicians using intraoral photographs. Data were descriptively analysed. Cumulative survival and success rates were calculated using Kaplan-Meier estimation.

RESULTS

The cumulative survival rate of lithium disilicate restorations was 97.5% after a mean service time of 5.9 years and 95.0% after 8.3 years. The cumulative success rate decreased from 94.4% after 5.9 years to 30.7% after 8.3 years. Repairs were required for 7 restorations (4.9%), and 5 (3.5%) were classified as failures. The results of the questionnaire indicate a high level of patient satisfaction. The subjective aesthetics were assessed more critically by dental technicians compared to dentists.

CONCLUSION

Lithium disilicate posterior restorations survived successfully up to 8.3 years when carried out by undergraduate students.

CLINICAL RELEVANCE

Pressed lithium disilicate glass ceramic inlays and partial crowns are reliable treatment options in posterior teeth.

Comparative Biocompatibility and Odonto-/Osteogenesis Effects of Hydraulic Calcium Silicate-Based Cements in Simulated Direct and Indirect Approaches for Regenerative Endodontic Treatments: A Systematic Review

BACKGROUND

Regenerative dentistry is the operation of restoring dental, oral and maxillofacial tissues. Currently, there are no guidelines for the ideal cement/material in regenerative endodontic treatments (RET). Hydraulic calcium silicate-based cements (hCSCs) are currently the material of choice for RET.

OBJECTIVES

This systematic review was conducted to gather all of the different direct and indirect approaches of using hCSCs in RET in vitro and in vivo, and to ascertain if there are any superiorities to indirect approaches.

METHODS AND MATERIALS

This systematic review was conducted according to the 2020 PRISMA guidelines. The study question according to the PICO format was as follows: Comparison of the biological behavior (O) of stem cells (P) exposed to hCSCs through direct and indirect methods (I) with untreated stem cells (C). An electronic search was executed in Scopus, Google Scholar, and PubMed.

RESULTS

A total of 78 studies were included. Studies were published between 2010 and 2022. Twenty-eight commercially available and eighteen modified hCSCs were used. Seven exposure methods (four direct and three indirect contacts) were assessed. ProRoot MTA and Biodentine were the most used hCSCs and had the most desirable results. hCSCs were either freshly mixed or set before application. Most studies allowed hCSCs to set in incubation for 24 h before application, which resulted in the most desirable biological outcomes. Freshly mixed hCSCs had the worst outcomes. Indirect methods had significantly better viability/proliferation and odonto-/osteogenesis outcomes.

CONCLUSION

Biodentine and ProRoot MTA used in indirect exposure methods result in desirable biological outcomes.

An in vitro anti-inflammatory effect of Thai propolis in human dental pulp cells

OBJECTIVE

To explore the potential for development of Thai propolis extract as a pulp capping agent to suppress pulpal inflammation from dental pulp infections. This study aimed to examine the anti-inflammatory effect of the propolis extract on the arachidonic acid pathway, activated by interleukin (IL)-1β, in cultured human dental pulp cells.

METHODOLOGY

Dental pulp cells, isolated from three freshly extracted third molars, were first characterized for their mesenchymal origin and treated with 10 ng/ml of IL-1β in the presence or absence of non-toxic concentrations of the extract from 0.08 to 1.25 mg/ml, as determined by the PrestoBlue cytotoxic assay. Total RNA was harvested and analyzed for mRNA expressions of 5-lipoxygenase (5-LOX) and cyclooxygenase-2 (COX-2). Western blot hybridization was performed to investigate COX-2 protein expression. Culture supernatants were assayed for released prostaglandin E2 levels. Immunofluorescence was conducted to determine involvement of nuclear factor-kappaB (NF-kB) in the inhibitory effect of the extract.

RESULTS

Stimulation of the pulp cells with IL-1β resulted in the activation of arachidonic acid metabolism via COX-2, but not 5-LOX. Incubation with various non-toxic concentrations of the propolis extract significantly inhibited upregulated COX-2 mRNA and protein expressions upon treatment with IL-1β (p<0.05), resulting in a significant decrease in elevated PGE2 levels (p<0.05). Nuclear translocation of the p50 and the p65 subunits of NF-kB upon treatment with IL-1β was also blocked by incubation with the extract.

CONCLUSIONS

Upregulated COX-2 expression and enhanced PGE2 synthesis upon treatment with IL-1β in human dental pulp cells were suppressed by incubation with non-toxic doses of Thai propolis extract via involvement of the NF-kB activation. This extract could be therapeutically used as a pulp capping material due to its anti-inflammatory properties.

Development of a new universal adhesive containing CPNE7-derived peptide and its potential role in reducing postoperative sensitivity

Post-operative sensitivity (POS) is the most common clinical dental complaint after tooth preparation and resin-based composite restoration. In our previous study, copine 7 (CPNE7) and CPNE7-derived peptide (CPNE7-DP) induced in vitro odontoblast differentiation and in vivo dentin formation. Here, we incorporated CPNE7-DP into All-Bond Universal (ABU) adhesive, developing ABU/CPNE7-DP. This study aimed to investigate the possibility of reducing POS using ABU/CPNE7-DP. We first determined the stability of CPNE7-DP under low pH. Furthermore, we evaluated its dentinal tubule penetration, in vitro odontogenic differentiation potential, in vivo tertiary dentin formation and its effects on bonding performance. CPNE7-DP was stable at pH 1.2, even lower than ABU's pH of 3.2. ABU/CPNE7-DP can penetrate dentinal tubules, stimulate odontoblast differentiation in vitro and generate tertiary dentin with tubular structure in vivo without interfering with bonding performance. Therefore, ABU/CPNE7-DP may serve as a novel bioactive adhesive for reducing POS.

Evaluation of Direct and Indirect Pulp Capping With Biodentine in Vital Permanent Teeth With Deep Caries Lesions

INTRODUCTION

Pulp capping is a procedural method of preserving pulp vitality following deep caries damage or accidental pulp exposure. Biodentine is a calcium silicate material that has been promoted for use in pulp capping among various clinical applications. This study evaluated the outcome of pulp capping with Biodentine following curettage of deep caries in the case series of permanent mature teeth.

MATERIALS AND METHODS

The study was carried out on 40 teeth with advanced caries treated by direct and indirect pulp capping using Biodentine, within a follow-up of six months. This was carried out at the Department of Conservative Dentistry-Endodontics of the CCTD Ibn Rochd-Casablanca.  Results: In this study, 43 teeth from 37 patients were treated with direct pulp capping and indirect pulp capping using Biodentine. The success rate of pulp capping was 90% at one month, 85% at three months, and 80% at six months.

CONCLUSION

The results of the studies conducted using Biodentine indicate that it is a suitable material for direct and indirect pulp capping, due to its bioactivity and ability to form a dentinal bridge.

The scientific management of deep carious lesions in vital teeth using contemporary materials—A narrative review

Aim

The aim of this article is to review the scientific evidence for deep caries removal in permanent vital teeth and the choice of dentine replacement material and restoration of the teeth to maintain long term tooth vitality and function.

Method

The two position statements namely the European Society of Endodontology and the American Association of Endodontists position statements on vital pulp therapy will be scrutinized and compared with regards to the deep caries removal strategy and assessed for evidence of best practice. The properties of materials used to manage vital pulps and the best way to restore the teeth will be reviewed and guidance on the full management of vital teeth will be suggested.

Conclusions

Promoting new treatment modalities for reversible and irreversible pulpitis allowing for pulp preservation should be considered. Although debatable, cases with deep caries should be managed by complete non-selective caries removal which will allow for pulpal management if needed and a more predictable outcome can be expected when using the new materials and treatment modalities of vital pulp therapy.

Assessing the antimicrobial properties of copper-iodide doped adhesives in an In vitro caries model: A pilot study

Context:

Recurrent caries are the leading cause of composite resin failure.

Aims:

The purpose of this pilot study was to test the efficacy of a novel copper iodide (CuI) containing dental adhesive in an in vitro caries model.

Subjects and Methods:

Streptococcus mutans and Lactobacillus acidophilus were grown individually on the complex medium for 48 h at 37°C. The pH of the mixed medium was 7.0 initially and tested every 24 h. 40 extracted teeth were prepared with standardized cavity preparations and coated with control or experimental CuI adhesives and imaged using a micro-computed tomography (microCT). Four study groups were evaluated: (1) control (2) 0.5 μg/ml CuI (3) 1.0 μg/ml CuI, 4) 5.0 μg/ml CuI. After incubation, the teeth were re-imaged using the microCT. Utilizing AnalyzePro software the three-dimensional data sets were overlaid and demineralization was measured and statistics were run.

Statistics:

Stratified ANOVA models were run to determine if there were differences between the control and experimental adhesive groups. Similarly, pH and bacterial concentrations were evaluated to ensure the viability of polymicrobial specimen.

Results and Conclusions:

Significant differences were found between the control group and the 1.0 and 5.0 CuI adhesive groups. No differences in pH were noted between the groups. Overlaid changes in demineralization were recorded as volume loss. CuI adhesives with 5 mg/ml or higher have the potential to limit tooth demineralization after bacterial penetration of a dental restoration in an in vitro caries model. Further testing is needed.

Endodontic Treatment of a Traumatic Tusk Fracture With Exposed Pulp in an Asian Elephant (Elephas maximus)

Tusk fracture in elephants is a common incident often resulting in pulp exposure and pulpitis. Extensive lavage, endodontic therapy, direct pulp capping, or extraction are treatment options. In this report, the successful management of a broken tusk of a juvenile male Asian elephant (Elephas maximus) including morphological analysis of the tusk tip 2 years after surgery are presented. Treatment was carried out under barn conditions and included antimicrobial photodynamic therapy and partial pulpotomy with direct pulp capping. Immediate pain relief was reached. The fractured tusk was preserved and continued to grow. The therapeutic filling material remained intact for over 1 year but was absent 2 years after treatment. The former pulp cavity of the tusk tip was filled with reparative dentin, osteodentin, and bone, but the seal between these hard tissues and pulp chamber dentin was incomplete. Radiographs obtained 3 years after treatment showed no differences in pulp shape, pulp width, and secondary dentin formation between the treated right and the healthy left tusk. It can be concluded that in case of an emergency, the endodontic therapy of a broken elephant tusk can be attempted under improvised conditions with adequate success. Photodynamic therapy might contribute to prevent infection and inflammation of the pulp. The decision tree published by Steenkamp (2019) provides a valuable tool to make quick decisions regarding a suitable therapy of broken tusks.

Effects of rice fermented extracts, "Sake Lees", on the functional activity of odontoblast-like cells (KN-3 cells)

This study was designed to investigate the effects of Sake Lees extracts (SLE, Sake Kasu) on the functional activity of odontoblastic cells and tooth pulp of the rats. For in vitro studies, a rat clonal odontoblast-like cell line, KN-3 cells were cultured. SLE significantly decreased KN-3 cell proliferation, but showed no significant cytotoxicity. SLE effects on several protein productions of KN-3 cells were compared with PBS. SLE and PBS increased alkaline phosphatase (ALP), dentin sialoprotein (DSP), and osterix in a day-course dependent manner, while SLE increased the induction of ALP on day 9-21 and DSP on day 15-21. SLE also increased Runx2 expression on day 3 and 9 compared to PBS. Alizarin Red stainings revealed that SLE showed a subtle increase in mineralization of KN-3 cells on day 15 and 21. A histological investigation was conducted to assess if SLE induced reparative dentin formation after direct capping at the exposed tooth pulp in rats, suggesting that SLE could increase the reparative dentin formation more than PBS. These findings suggest that Sake Lees could have functional roles in the alterations of odontoblastic activity, which might influence the physiology of the tooth pulp.

A retrospective cross-sectional study of early patient-reported failures of direct restorations placed in a primary dental care setting

Introduction A retrospective cross-sectional study of early patient-reported failures of restorations was initiated to understand the reasons and factors associated with early failure. Early patient-reported failures are defined as restorations requiring replacement within three months of placement.Aim To investigate if restorative material placed or any other tooth/restoration/patient factors may be associated with early patient-reported failures.Methods In total, 360 restorations were replaced from January 2016 to December 2017. Multivariable analyses (logistic regression model) were used to identify any patient/tooth/restoration factors that were associated with early patient-reported failures.Results Dislodgement, fracture and pain/sensitivity were the three main failure modes. There was significant association between restorative material type and dislodgement and restoration fracture. The odds of dislodgement for composite resin (CR) were 4.3 times higher compared to amalgam. The odds of dislodgement for glass-ionomer cement (GIC) and resin-modified GIC were 3.7 times higher compared to amalgam. The odds of fracture for CR were ten times lower compared to amalgam. The odds of pain for teeth with a history of restoration failure for a particular tooth were five times lower compared to no history of restoration failure for a particular tooth.Conclusions Restorative material type affected patient-reported failures.

The Effect of Calcium-Silicate Cements on Reparative Dentinogenesis Following Direct Pulp Capping on Animal Models

Dental pulp vitality is a desideratum for preserving the health and functionality of the tooth. In certain clinical situations that lead to pulp exposure, bioactive agents are used in direct pulp-capping procedures to stimulate the dentin-pulp complex and activate reparative dentinogenesis. Hydraulic calcium-silicate cements, derived from Portland cement, can induce the formation of a new dentin bridge at the interface between the biomaterial and the dental pulp. Odontoblasts are molecularly activated, and, if necessary, undifferentiated stem cells in the dental pulp can differentiate into odontoblasts. An extensive review of literature was conducted on MedLine/PubMed database to evaluate the histological outcomes of direct pulp capping with hydraulic calcium-silicate cements performed on animal models. Overall, irrespective of their physico-chemical properties and the molecular mechanisms involved in pulp healing, the effects of cements on tertiary dentin formation and pulp vitality preservation were positive. Histological examinations showed different degrees of dental pulp inflammatory response and complete/incomplete dentin bridge formation during the pulp healing process at different follow-up periods. Calcium silicate materials have the ability to induce reparative dentinogenesis when applied over exposed pulps, with different behaviors, as related to the animal model used, pulpal inflammatory responses, and quality of dentin bridges.

Deciphering Reparative Processes in the Inflamed Dental Pulp

Research over several decades has increased our understanding of the nature of reparative and regenerative processes in the dental pulp, at both the cellular and molecular level. However, advances in scientific knowledge have not translated into novel clinical treatment strategies for caries-induced pulpitis. This narrative review explores the evidence regarding the ability of inflamed pulp tissue to heal and how this knowledge may be used therapeutically. A literature search and evidence analysis covering basic, translational and clinical pulp biology research was performed. The review focuses on (1) the regenerative and defense capabilities of the pulp during caries-induced inflammation; (2) the potential of novel biomaterials to harness the reparative and regenerative functions of the inflamed pulp; and (3) future perspectives and opportunities for conservative management of the inflamed pulp. Current conservative management strategies for pulpitis are limited by a combination of unreliable diagnostic tools and an outdated understanding of pulpal pathophysiological responses. This approach leads to the often unnecessary removal of the entire pulp. Consequently, there is a need for better diagnostic approaches and a focus on minimally-invasive treatments utilizing biologically-based regenerative materials and technologies.

Pulp tissue reaction to a self-adhesive, resin-based direct pulp capping material containing surface pre-reacted glass-ionomer filler

OBJECTIVE

This study aimed to evaluate the effect of direct pulp capping using an experimental self-adhesive resin for direct pulp capping (SRD) containing silica and surface pre-reacted glass-ionomer (S-PRG) filler on pulpal healing and to monitor the dentin bridge formation in rat pulp 2-4 weeks after operation.

METHODS

Five types of SRDs (SRD-0: S-PRG fillers 0 wt%; SRD-1: S-PRG fillers 9.1 wt%; SRD-2: S-PRG fillers 18.4 wt%; SRD-3: S-PRG fillers 27.8 wt%; and SRD-6: S-PRG fillers 57.4 wt%) were prepared, and mineral trioxide aggregate (MTA) was used as control (n = 8). Direct pulp capping was performed on rats that were sacrificed for further evaluation 2 or 4 weeks after the operation. The pulp tissue disorganization (PTD), inflammatory cell infiltration (ICI), and reparative dentin formation were histopathologically evaluated; the data were statistically analyzed using the Kruskal-Wallis and the Mann-Whitney U tests.

RESULTS

The histopathological evaluation of SRD-1-treated test animals 2 weeks post-operation revealed inferior PTD and ICI when compared with that of MTA. Even 4 weeks after the operation in SRD-1- and SRD-2-treated rats, the PTD and ICI were inferior when compared with those of MTA. The dental specimens of SRD-0 and MTA showed orthodentin formation, whereas SRD-treated test animals showed osteodentin formation at a position slightly deeper than the site of the pulpal exposure.

SIGNIFICANCE

The reparative dentin formed by SRD-0 and MTA was genuine, whereas that formed by SRD-3 and SRD-6 was ossified and ectopic. SRD may have the potential to be utilized clinically as a direct pulp capping material.

Bacterial Adhesion of Streptococcus mutans to Dental Material Surfaces

The aim of this study was to investigate and understand bacterial adhesion to different dental material surfaces like amalgam, Chromasit, an Co-Cr alloy, an IPS InLine ceramic, yttrium stabilized tetragonal polycrystalline zirconia (TPZ), a resin-based composite, an Au-Pt alloy, and a tooth. For all materials, the surface roughness was assessed by profilometry, the surface hydrophobicity was determined by tensiometry, and the zeta potential was measured by electrokinetic phenomena. The arithmetic average roughness was the lowest for the TPZ ceramic (R_a = 0.23 µm ± 0.02 µm), while the highest value was observed for the Au-Pt alloy (R_a = 0.356 µm ± 0.075 µm). The hydrophobicity was the lowest on the TPZ ceramic and the highest on the Co-Cr alloy. All measured streaming potentials were negative. The most important cause of tooth caries is the bacterium Streptococcus mutans, which was chosen for this study. The bacterial adhesion to all material surfaces was determined by scanning electron microscopy. We showed that the lowest bacterial extent was on the amalgam, whereas the greatest extent was on tooth surfaces. In general, measurements showed that surface properties like roughness, hydrophobicity and charge have a significant influence on bacterial adhesion extent. Therefore, dental material development should focus on improving surface characteristics to reduce the risk of secondary caries.

Longevity of lithium disilicate indirect restorations in posterior teeth prepared by undergraduate students: A retrospective study up to 8.5 years

OBJECTIVES

To analyze retrospectively the clinical performance and survival of lithium disilicate inlays, partial crowns and crowns placed by undergraduate students.

METHODS

250 lithium disilicate posterior restorations (IPS™Emax Press) were evaluated. Mean service time was 6.6 years (79 months) with a maximum observation time of 8.5 years (102 months). Clinical performance was assessed using FDI Criteria. Descriptive statistics were used to display the distribution of the criteria. Success and survival of the restorations were calculated with the Kaplan Meier method. A Cox regression analysis was performed to detect influencing parameters for the survival or the success of the restorations.

RESULTS

Survival and success rates of lithium disilicate indirect restorations were calculated at 6.6 years with 96.3 % and 93.8 %, respectively. After 8.5 years the survival rate was calculated with 94 % and the success rate with 83.8 %. 10 out of 250 restorations (4%) failed, while the main reasons for failure were fracture of material, debonding/loss of restoration, endodontic complications as well as recurrence of caries. A Cox regression analysis failed to show a correlation between restoration failure and the experience level of the students, an existing root canal treatment, type of tooth, bruxism or the use of rubber dam.

CONCLUSIONS

Lithium disilicate indirect posterior restorations demonstrate a high success and survival rate after a mean service of 6.6 years when placed by undergraduate students with different levels of experience. Co-factors influencing the survival or success rate of these restorations could not be identified.

CLINICAL SIGNIFICANCE

Lithium disilicate restorations show a good clinical performance up to 8.5 years when prepared by undergraduate students.

Advanced in Vitro Experimental Models for Tissue Engineering-based Reconstruction of a 3D Dentin/pulp Complex: a Literature Review

OBJECTIVE

Experimental procedures have been used to monitor cellular responses at the dentin/pulp interface. Aiming to divert from in vivo studies and oversimplified two-dimensional assays, three-dimensional (3D) models have been developed. This review provides an overview of existing literature, regarding 3D in vitro dentin/pulp reconstruction.

MATERIAL & METHODS

PubMed, Scopus, Cochrane Library and Web of Science- were systematically searched for attributes between 1998 and 2020. The search focused on articles on the development of three-dimensional tools for the reconstruction of a dentin/pulp complex under in vitro conditions, which were then screened and qualitatively assessed. Article grouping according to mode of implementation, resulted in five categories: the customised cell perfusion chamber (CPC) (n = 8), the tooth bud model (TBM) (n = 3), the 3D dentin/pulp complex manufactured by tissue engineering (DPC) (n = 6), the entire tooth culture (ETC) (n = 4) and the tooth slice culture model (TSC) (n = 5).

RESULTS

A total of 26 publications, applying nine and eight substances for pulp and dentin representation respectively, were included. Natural materials and dentin components were the most widely utilized. The most diverse category was the DPC, while the CPC group was the test with the highest longevity. The most consistent categories were the ETC and TSC models, while the TBM presented as the most complete de novo approach.

CONCLUSIONS

All studies presented with experimental protocols with potential upgrades. Solving the limitations of each category will provide a complete in vitro testing and monitoring tool of dental responses to exogenous inputs.

CLINICAL RELEVANCE

The 3D dentin/pulp complexes are valid supplementary tools for in vivo studies and clinical testing. Graphical Abstract.

Application of BMP-2/FGF-2 gene-activated scaffolds for dental pulp capping

OBJECTIVES

To evaluate the effect of non-viral gene therapy on human dental pulp stem cells (DPSCs) in an in vitro and an ex vivo model.

MATERIALS AND METHODS

Nanoplexes comprising polyethyleneimine (PEI) and plasmid DNA (pDNA) encoding for fibroblast growth factor-2 (pFGF-2) and bone morphogenic protein-2 (pBMP-2) were cultured with DPSCs to evaluate cytotoxicity, protein expression, and mineralization activity. Collagen scaffolds loaded with these nanoplexes or mineral trioxide aggregate (MTA) were utilized in an ex vivo tooth culture model to assess pulp response, over a period of 14 days. All nanoplex formulations were characterized for size and zeta potential by measuring dynamic light scattering and electrophoretic mobility, respectively.

RESULTS

DPSCs treated with the nanoplexes showed increased cell proliferation and enhanced expression of BMP-2 and FGF-2 proteins. Collagen scaffolds containing PEI-pBMP-2 and/or pFGF-2 nanoplexes significantly increased cell proliferation, BMP-2 and FGF-2 expression, and mineralization when compared to MTA. Ex vivo histology showed a well-preserved pulp and healthy tissue in both the MTA and scaffold groups. Connective tissue in contact with the scaffold was dense and homogeneous, with some cells present in contact and within the scaffold.

CONCLUSION

Transfection of DPSCs with pBMP-2/pFGF-2 nanoplexes resulted in increased expression of BMP-2 and FGF-2, enhanced proliferation, and mineralization properties compared to MTA. These findings were supported by the ex vivo observations.

CLINICAL RELEVANCE

This biological approach in pulp capping brings new insights into the effective management of engineered pulp tissues, mainly those generated by the transplantation of DPSCs in empty root canals.

Self-healing biomaterials: The next generation is nano

The U.S. Agency for Healthcare Research and Quality estimates that there are over 1 million total hip and total knee replacements each year in the U.S. alone. Twenty five percent of those implants will experience aseptic loosening, and bone cement failure is an important part of this. Bone cements are based on poly(methyl methacrylate) (PMMA) systems that are strong but brittle polymers. PMMA-based materials are also essential to modern dental fillings, and likewise, the failure rates are high with lifetimes of 3-10 years. These brittle polymers are an obvious target for self-healing systems which could reduce revision surgeries and visits to dentist. Self-healing polymers have been described in the literature since 1996 and examples from Roman times are known, but their application in medicine has been challenging. This review looks at the development of self-healing biomaterials for these applications and the challenges that lie between development and the clinic. Many of the most promising formulations involve introducing nanoscale components which offer substantial potential benefits over their microscale counterparts especially in composite systems. There is substantial promise for translation, but issues with toxicity, robustness, and reproducibility of these materials in the complex environment of the body must be addressed. This article is categorized under: Therapeutic Approaches and Drug Discovery > Emerging Technologies Nanotechnology Approaches to Biology > Nanoscale Systems in Biology Implantable Materials and Surgical Technologies > Nanomaterials and Implants.

Pulp vitality during ultrasonic tooth preparation. Part 2

BACKGROUND

Ultrasonic devices have a lot of dental application specially in hygiene and surgery. However there are some disadvantages like cut slowness and heat production. Prosthodontics application is less investigated. In particular the heat production could be an important factor for the clinician. In fact more than 5.5 °C temperature increasing could determine pulp necrosis during tooth preparation. The aim of this study is to investigate the increasing of temperature during finishing line repositioning and polishing phases using ultrasounds inserts and to verify if it remains within the limit of 5.5 °C.

METHODS

A sample of 32 human molars (extracted for periodontal reasons) was selected. The teeth were endodontically treated and prepared with burs in order to obtain a prosthetic round chamfer preparation, leaving the apical portion pervious for inserting the thermocouple probe. Then, they were inserted in plaster cubes up to the cement-enamel junction. A wall has been selected for each tooth for margin repositioning and finishing and prepared with the piezoelectric instrument (Multipiezo Touch with TipHolder DB2, Mectron, Carasco, Genoa, Italy). A mechanical arm was used to standardize the operator-dependent parameters. These parameters were: the pressure exerted on the dental wall, the cutting length and the time required for margin repositioning and finishing. The test phase consisted in a first stage of margin repositioning using an regular ultrasound tip with a diamond grain of 120 micron (DB120, Mectron, Carasco, Italy) (group 1), followed by a second finishing step conducted by a extra fine ultrasound tip with a diamond grain of 60 micron (DB60, Mectron, Carasco, Italy) (group 2). Each test lasted 60 seconds: this was the time that the mechanical arm needed to accomplish 32 rides. During these stages the intrapulpal temperature has been recorded thanks to a thermocouple. The obtained temperature data were analyzed by Kruskal-Wallis test and Mann-Withney post-hoc test, without Bonferroni correction (P<0.001).

RESULTS

The average pulpal temperature increase was 4.65 °C with a standard deviation of 0.99 °C for the DB 120 ultrasonic tip and 5.40 °C with a standard deviation of 0.84 °C for the DB 60 ultrasonic tip. However, neither of the instruments reach the medium critical level of 5.5°C reported in the literature, there are some single values who exceed it. There is statistically significant difference using tips with different granulometries within the two groups (P value =0.013).

CONCLUSIONS

Ultrasonic tools are very performing to achieve results in repositioning and polishing of prepared tooth. The in-vitro analysis show that the pulp temperature increasing remains within the safe limits literature shows. It is important underline the polishing phase is the most critical and the clinicians have to pay attention to irrigation and pression to avoid pulp damages. Additional clinical studies have to be performed to confirm these results.

Minimal invasive microscopic tooth preparation in esthetic restoration: a specialist consensus

By removing a part of the structure, the tooth preparation provides restorative space, bonding surface, and finish line for various restorations on abutment. Preparation technique plays critical role in achieving the optimal result of tooth preparation. With successful application of microscope in endodontics for >30 years, there is a full expectation of microscopic dentistry. However, as relatively little progress has been made in the application of microscopic dentistry in prosthodontics, the following assumptions have been proposed: Is it suitable to choose the tooth preparation technique under the naked eye in the microscopic vision? Is there a more accurate preparation technology intended for the microscope? To obtain long-term stable therapeutic effects, is it much easier to achieve maximum tooth preservation and retinal protection and maintain periodontal tissue and oral function health under microscopic vision? Whether the microscopic prosthodontics is a gimmick or a breakthrough in obtaining an ideal tooth preparation should be resolved in microscopic tooth preparation. This article attempts to illustrate the concept, core elements, and indications of microscopic minimally invasive tooth preparation, physiological basis of dental pulp, periodontium and functions involved in tool preparation, position ergonomics and visual basis for dentists, comparison of tooth preparation by naked eyes and a microscope, and comparison of different designs of microscopic minimally invasive tooth preparation techniques. Furthermore, a clinical protocol for microscopic minimally invasive tooth preparation based on target restorative space guide plate has been put forward and new insights on the quantity and shape of microscopic minimally invasive tooth preparation has been provided.

[Minimal invasive microscopic tooth preparation based on endodontic, periodontal and functional health]

Tooth preparation is the primary and core operation technique for dental esthetic restoration treatment, due to its effect of providing restoration space, bonding interfaces and marginal lines for dental rehabilitation after tooth tissue reduction. The concept of microscopic minimal invasive dentistry put forward the issue of conducting high-quality tooth preparation, conserve tooth-structure, protect vital pulp and periodontal tissue simultaneously. This study reviewed the concepts, physiology background, design and minimal invasive microscopic tooth preparation, and in the meantime, individualized strategies and the two core elements of tooth preparation (quantity and shape) are listed.

Influence of silica nanocoating on stain susceptibility and superficial integrity of dimethacrylate-based composites

The aim of this study was to investigate the ability of a novel silica (SiO₂ )-based nanocoating approach to extend the superficial integrity of current composites. Cylindrical discs (7 × 2 mm) were produced from nanohybrid and nanofilled composites. Specimens in control groups were not coated, but SiO₂ nanocoating was performed on specimens in experimental groups (n = 8). Specimens were stored for 24 h in distilled water at 37°C (baseline) and then artificially aged for 15, 90, or 180 d in a low-pH staining solution. Surface roughness (Ra) was measured using a profilometer, and a goniometer was used to determine surface free energy (SFE). Color change was evaluated by a reflectance spectrophotometer, applying the color distance metric, ΔE₀₀ , according to the Commission Internationale de l'Eclairage (CIE) L*a*b* coordinates. Data were subjected to repeated-measures anova and the Tukey post-hoc test. Composites presented visually perceptible color changes (ΔE₀₀  > 0.81) as early as 15 d of aging, with significantly higher ΔE₀₀ values recorded over time. Nanocoating with SiO₂ significantly reduced the SFE of composites at all storage times, and significantly lower Ra values were identified after aging. Nanohybrid and nanofilled composites were susceptible to substantial hydrolytic superficial degradation and staining, which was dramatically attenuated by the proposed SiO₂ nanocoating approach. Nanocoating effectively lowered the SFE of composites, thus minimizing water-composite interactions, which contributed to reduced superficial deterioration and lower stain susceptibility over time.

Effects of mineral trioxide aggregate, calcium hydroxide, biodentine and Emdogain on osteogenesis, Odontogenesis, angiogenesis and cell viability of dental pulp stem cells

BACKGROUND

Vital pulp therapy preserves and maintains the integrity and the health of dental pulp tissue that has been injured by trauma, caries or restorative procedures. The enhancement of cells viability and formation of reparative dentine and new blood vessels are vital determinants of the success of direct pulp capping. Therefore, the aims of this study was to evaluate and compare the in vitro osteogenic, odontogenic and angiogenic effects of mineral trioxide aggregate (MTA), calcium hydroxide [Ca(OH)₂], Biodentine and Emdogain on dental pulp stem cells (DPSCs) and examine the effects of the tested materials on cell viability.

METHODS

DPSCs were treated with MTA, Ca(OH)₂, Biodentine or Emdogain. Untreated cells were used as control. The cell viability was measured by MTT assay on day 3. Real-Time PCR with SYBR green was used to quantify the gene expression levels of osteogenic markers (alkaline phosphatase and osteopontin), odontogenic marker (dentin sialophosphoprotein) and angiogenic factor (vascular endothelial growth factor) on day 7 and day 14.

RESULTS

All capping materials showed variable cytotoxicity against DPSCs (77% for Emdogain, 53% for MTA, 26% for Biodentine and 16% for Ca(OH)₂ compared to control (P value < 0.0001). Osteopontin (OPN) and dentin sialophosphoprotein (DSPP) gene expression was increased by all four materials. However, alkaline phosphatase (ALP) was upregulated by all materials except Emdogain. Vascular endothelial growth factor (VEGF) expression was upregulated by all four tested materials except Ca(OH)₂.

CONCLUSIONS

Our results suggest MTA, Biodentine and Emdogain exhibit similar attributes and may score better than Ca(OH)₂. Emdogain could be a promising alternative to MTA and Biodentine in enhancing pulp repair capacity following dental pulp injury. However, further future research is required to assess the clinical outcomes and compare it with the in vitro findings.

Hydrophobic and antimicrobial dentin: A peptide-based 2-tier protective system for dental resin composite restorations

Dental caries, i.e., tooth decay mediated by bacterial activity, is the most widespread chronic disease worldwide. Carious lesions are commonly treated using dental resin composite restorations. However, resin composite restorations are prone to recurrent caries, i.e., reinfection of the surrounding dental hard tissues. Recurrent caries is mainly a consequence of waterborne and/or biofilm-mediated degradation of the tooth-restoration interface through hydrolytic, acidic and/or enzymatic challenges. Here we use amphipathic antimicrobial peptides to directly coat dentin to provide resin composite restorations with a 2-tier protective system, simultaneously exploiting the physicochemical and biological properties of these peptides. Our peptide coatings modulate dentin's hydrophobicity, impermeabilize it, and are active against multispecies biofilms derived from caries-active individuals. Therefore, the coatings hinder water penetration along the otherwise vulnerable dentin/restoration interface, even after in vitro aging, and increase its resistance against degradation by water, acids, and saliva. Moreover, they do not weaken the resin composite restorations mechanically. The peptide-coated highly-hydrophobic dentin is expected to notably improve the service life of resin composite restorations and to enable the development of entirely hydrophobic restorative systems. The peptide coatings were also antimicrobial and thus, they provide a second tier of protection preventing re-infection of tissues in contact with restorations. STATEMENT OF SIGNIFICANCE: We present a technology using designer peptides to treat the most prevalent chronic disease worldwide; dental caries. Specifically, we used antimicrobial amphipathic peptides to coat dentin with the goal of increasing the service life of the restorative materials used to treat dental caries, which is nowadays 5 years on average. Water and waterborne agents (enzymes, acids) degrade restorative materials and enable re-infection at the dentin/restoration interface. Our peptide coatings will hinder degradation of the restoration as they produced highly hydrophobic and antimicrobial dentin/material interfaces. We anticipate a high technological and economic impact of our technology as it can notably reduce the lifelong dental bill of patients worldwide. Our findings can enable the development of restorations with all-hydrophobic and so, more protective components.

Dental cavity liners for Class I and Class II resin-based composite restorations

BACKGROUND

Resin-based composite (RBC) is currently accepted as a viable material for the restoration of caries for posterior permanent teeth requiring surgical treatment. Despite the fact that the thermal conductivity of the RBC restorative material closely approximates that of natural tooth structure, postoperative hypersensitivity is sometimes still an issue. Dental cavity liners have historically been used to protect the pulp from the toxic effects of some dental restorative materials and to prevent the pain of thermal conductivity by placing an insulating layer between restorative material and the remaining tooth structure. This is an update of the Cochrane Review first published in 2016.

OBJECTIVES

The objective of this review was to assess the effects of using dental cavity liners in the placement of Class I and Class II resin-based composite posterior restorations in permanent teeth in children and adults.

SEARCH METHODS

Cochrane Oral Health's Information Specialist searched the following databases: Cochrane Oral Health's Trials Register (to 12 November 2018), the Cochrane Central Register of Controlled Trials (CENTRAL; 2018, Issue 10) in the Cochrane Library (searched 12 November 2018), MEDLINE Ovid (1946 to 12 November 2018), Embase Ovid (1980 to 12 November 2018) and LILACS BIREME Virtual Health Library (Latin American and Caribbean Health Science Information database; 1982 to 12 November 2018). We searched ClinicalTrials.gov and the World Health Organization International Clinical Trials Registry Platform for ongoing trials. No restrictions were placed on the language or date of publication when searching the electronic databases.

SELECTION CRITERIA

We included randomized controlled trials assessing the effects of the use of liners under Class I and Class II posterior resin-based composite restorations in permanent teeth (in both adults and children). We included both parallel and split-mouth designs.

DATA COLLECTION AND ANALYSIS

We utilized standard methodological procedures prescribed by Cochrane for data collection and analysis. Two review authors screened the search results and assessed the eligibility of studies for inclusion against the review inclusion criteria. We conducted risk of bias assessments and data extraction independently and in duplicate. Where information was unclear we contacted study authors for clarification.

MAIN RESULTS

Eight studies, recruiting over 700 participants, compared the use of dental cavity liners to no liners for Class I and Class II resin-based composite restorations.Seven studies evaluated postoperative hypersensitivity measured by various methods. All studies were at unclear or high risk of bias. There was inconsistent evidence regarding postoperative hypersensitivity (either measured using cold response or patient-reported), with a benefit shown at some, but not all, time points (low-quality evidence).Four trials measured restoration longevity. Two of the studies were judged to be at high risk and two at unclear risk of bias. No difference in restoration failure rates were shown at 1 year follow-up, with no failures reported in either group for three of the four studies; the fourth study had a risk ratio (RR) 1.00 (95% confidence interval (CI) 0.07 to 15.00) (low-quality evidence). Three studies evaluated restoration longevity at 2 years follow-up and, again, no failures were shown in either group.No adverse events were reported in any of the included studies.

AUTHORS' CONCLUSIONS

There is inconsistent, low-quality evidence regarding the difference in postoperative hypersensitivity subsequent to placing a dental cavity liner under Class I and Class II posterior resin-based composite restorations in permanent posterior teeth in adults or children 15 years or older. Furthermore, no evidence was found to demonstrate a difference in the longevity of restorations placed with or without dental cavity liners.

Polymer–antibiotic conjugates as antibacterial additives in dental resins

Dental resins containing polymer–antibiotic conjugates (PACs) demonstrate significant antibacterial properties.

Gene expression and protein synthesis of esterase from Streptococcus mutans are affected by biodegradation by-product from methacrylate resin composites and adhesives

An esterase from S. mutans UA159, SMU_118c, was shown to hydrolyze methacrylate resin-based dental monomers.

OBJECTIVE

To investigate the association of SMU_118c to the whole cellular hydrolytic activity of S. mutans toward polymerized resin composites, and to examine how the bacterium adapts its hydrolytic activity in response to environmental stresses triggered by the presence of a resin composites and adhesives biodegradation by-product (BBP).

MATERIALS AND METHODS

Biofilms of S. mutans UA159 parent wild strain, SMU_118c knockout strain (ΔSMU_118c), and SMU_118c complemented strain (ΔSMU_118cC) were incubated with photo-polymerized resin composite. High performance liquid chromatography was used to quantify the amount of a universal 2,2-Bis[4-(2-hydroxy-3-methacryloxypropoxy)phenyl]propane (bisGMA)-derived BBP, bishydroxy-propoxy-phenyl-propane (bisHPPP) in the media. Fluorescence in situ hybridization (FISH) and quantitative proteomic analysis were used to measure SMU_118c gene expression and production of SMU_118c protein, respectively, from biofilms of S. mutans UA159 wild strain that were cultured with bisHPPP.

RESULTS

The levels of bisHPPP released from composite were similar for ΔSMU_118c and media control, and these were significantly lower compared to the parent wild-strain UA159 and complemented strain (ΔSMU_118cC) (p < 0.05). Gene expression of SMU_118c and productions of SMU_118c protein were higher for bisHPPP incubated biofilms (p < 0.05).

SIGNIFICANCE

This study suggests that SMU_118c is a dominant esterase in S. mutans and capable of catalyzing the hydrolysis of the resinous matrix of polymerized composites and adhesives. In turn, the bacterial response to BBP was to increase the expression of the esterase gene and enhance esterase production, potentially accelerating the biodegradation of the restoration, adhesive and restoration-tooth interface, ultimately contributing to premature restoration failure.

STATEMENT OF SIGNIFICANCE

We recently reported (Huang et al., 2018) on the isolation and initial characterization of a specific esterase (SMU_118c) from S. mutans that show degradative activity toward the hydrolysis of dental monomers. The current study further characterize this enzyme and shows that SMU_118c is a dominant degradative esterase activity in the cariogenic bacterium S. mutans and is capable of catalyzing the hydrolysis of the resinous matrix of polymerized composites and adhesives. In turn, the bacterial response to biodegradation by-products from composites and adhesives was to increase the expression of the esterase gene and enhance esterase production, accelerating the biodegradation of the restoration, adhesive and the restoration-tooth interface, potentially contributing to the pathogenesis of recurrent caries around resin composite restorations.

Pulpal Temperature Rise: Evaluation after Light Activation of Newer Pulp-Capping Materials and Resin Composite

Background:

To evaluate temperature changes in pulp chamber during light activation of newer pulp- capping materials and composite resin using light-emitting diode.

Materials and Methods:

A standardized Class I cavity was prepared in 80 extracted, intact, noncarious mandibular first molars, keeping remaining dentin thickness of 0.5 mm. The teeth were divided into four groups of 20 teeth each. Following this, apical third of the mesial root of each tooth was cut and a K type thermocouple attached to digital thermometer was inserted into pulp chamber from the sectioned mesial root. Whole assembly with teeth was suspended in water bath with constant temperature at 37°C. The previously divided teeth in four groups, were lined with Calcimol LC (Group A), Activa (Group B), TheraCal LC (Group C), and Ionoseal (Group D), followed by 3 increments of Filtek Z350 × T universal restorative. The temperature rise following light activation of pulp-capping material, bonding agent, and composite was noted.

Results:

The temperature rise in the pulp chamber after light activation of Activa was highest among all pulp-capping materials, followed by teeth lined with Calcimol LC, Ionoseal, and least in teeth with TheraCal LC.

Conclusions:

Temperature rise in the pulp chamber after light activation of newer pulp-capping materials and composite was below critical threshold for irreversible pulpal damage. Among all the pulp-capping materials, TheraCal LC showed lowest temperature rise in pulp chamber.

In-vitro analysis of maxillary first molars morphology using three dimensional Micro-CT imaging: considerations for restorative dentistry

PURPOSE

The aim of this study was to determine the differences between the positional relationship of the crown contour and the pulp chamber of left and right maxillary first molars, as well as their morphological characteristics by using micro-CT system with reconstruction from a volumetric rendering software.

MATERIALS AND METHODS

In total, 21 extracted maxillary first molars, including 11 left and 10 right teeth, were used. The positional relationship between the crown contour, pulp chamber and morphology of the teeth were investigated three-dimensionally by means of micro-CT imaging.

RESULTS

Closest distance of mesio-buccal pulp horn to enamel surface in mm was calculated as 2.5±0.20 mm for right and 2.29±0.17 mm for left teeth. This difference was statistically significant (p=0.017). The means of closest distance of disto-buccal pulp horn to enamel surface were also significantly different between left and right teeth (p=0.001). The mean pulp volumes of right side and left side teeth were, respectively, 32.94±3.19 mm³ and 33.71±2.82 mm³ but this difference was not statistically significant.

CONCLUSION

These results suggest that right and left maxillary first molars should be treated differently during preparation of cavities. Further studies must be done with larger samples as well as for other molar teeth in different populations to reveal the morphology of the molar for further considerations in restorative dentistry.

Esterase from a cariogenic bacterium hydrolyzes dental resins

OBJECTIVES

To identify and characterize specific esterases from S. mutans with degradative activity toward methacrylate-based resin monomers.

METHODS

Out of several putative esterases, an esterase encoded in an Open Reading Frame as SMU_118c (The National Center for Biotechnology Information, NCBI), was found to have true hydrolase activities. SMU_118c was cloned, expressed, purified and further characterized for its respective hydrolytic activity towards ester-containing nitrophenyl substrates and the universal resin monomers bis-phenyl-glycidyl-dimethacrylate (bisGMA) and triethyleneglycol dimethacrylate (TEGDMA) at neutral (7.0) or cariogenic (5.5) pH. Mass spectrometry (MS) was used to verify the expression of SMU_118c protein in S. mutans UA159.

RESULTS

Similar to the whole cell activity of S. mutans, SMU_118c showed the highest affinity toward para-nitrophenyl acetate (pNPA) and para-nitrophenyl butyrate (pNPB) vs. ortho-nitrophenyl butyrate (oNPB) and butyrylthiocholine iodide (BTC) (p < 0.05). The esterase retained 60% of its activity after 21 days and hydrolyzed bisGMA at a higher rate than TEGDMA at both neutral and cariogenic pH (p < 0.001), similarly to the predominant human salivary esterase degradative activity. MS confirmed that SMU_118c is an intracellular protein in S. mutans UA159 and expressed under pathogenic (pH 5.5) growth conditions.

SIGNIFICANCE

The similarity in the activity profile to the whole S. mutans bacterial cell, the stability over time at cariogenic pH, the preference to hydrolyze bisGMA and confirmed expression profile suggest that SMU_118c could be a significant contributor to the whole bacterial degradative activity of S. mutans toward the degradation of resin composites, adhesives and the restoration-tooth interface, potentially accelerating restoration's failure.

STATEMENT OF SIGNIFICANCE

The current study builds upon our highly-cited previous study by Bourbia et al., (JDR, 2013) that reported on that the cariogenic bacterium, S. mutans has esterase-like activities that enable the bacterium to degrade dental composites and adhesives. The current submission is the first to report on the isolation and characterization of the specific esterase activity (SMU_118c) from S. mutans that is a significant contributor to the whole bacterial degradative activity toward the hydrolysis of dental resins. This activity compromises the restoration-tooth interface, increases interfacial bacterial microleakage (Kermanshahi et al., JDR 2010), potentially contributing to the pathogenesis of recurrent caries around resin composite restorations. This represent a significant contribution to the field of biomaterials and their clinical performance.

Effectiveness of the DHMAI monomer in the development of an antibacterial dental composite

OBJECTIVE

Development of antibacterial dental composites is the ultimate goal to decrease carious disease occurrence and increase the restoration longevity. For this purpose, the quaternary ammonium dimethyl-hexadecyl-methacryloxyethyl-ammonium iodide (DHMAI) and the methacryloyloxyethylphosphorylcholine (MPC) have been incorporated in experimental methacrylate-based composite resins. This aims to first investigate the effect of each alone and then their combined effect.

METHODS

Synthesized DHMAI and commercial MPC were added either alone or combined at different concentrations to experimental dental composite. Flexural strength (FS) and modulus (FM) were tested to select the optimal concentrations. Only selected composites were evaluated for Vickers hardness (HV) and the degree of conversion (DC) using fourier transform infrared spectroscopy analysis (FTIR-ATR). Antibacterial activity was assessed using tests on colony-forming unit (CFU), scanning electron microscopy (SEM) and Alamarblue assay to measure the metabolic activity. Streptococcus mutans biofilm was chosen to be grown on the composite surfaces during 96h at 37°C.

RESULTS

Incorporation of 7.5% DHMAI in composite improved the degree of conversion and gave a strong antibacterial effect with a reduction of (∼98%) in CFU and (∼50%) of metabolic activity with acceptable mechanical properties. Addition of MPC to DHMAI affects mechanical properties of composites without providing a better antibacterial activity.

SIGNIFICANCE

Composites with DHMAI greatly reduced S. mutans biofilm and improved the degree of conversion without scarifying the composites' mechanical properties. DHMAI may have wide applicability to other dental materials in order to inhibit caries and improve the longevity of restorations.

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.

Degradation of Resin Restorative Materials by Streptococcus Mutans: A Pilot Study

OBJECTIVE

To evaluate the degradation of three resin based restorative materials by S Mutans.

STUDY DESIGN

Class I cavity was prepared in extracted premolars and were randomly divided into 3 groups (Group I - Conventional composite (CC), Group II - Resin Modified GIC and Group III-Giomer). Teeth were then restored by respective restorative material and equally divided in two subgroups (Control and Experimental). Experiment subgroup samples were then incubated in 2 ml of BHI with 1:10 dilution of SM (MTCC-497) grown overnight in BHI whereas control subgroup samples were incubated in BHI without SM. The incubation solution was collected at 2,14 and 30 days interval, and the analysis for identification and quantification of Bis-HPPP was done by High performance Liquid Chromatography.

RESULTS

Statistical analysis of the collected data revealed a statistically increased Bis HPPP production in the presence of SM in all the tested materials, with minimum in Resin Modified GIC and a maximum in Conventional Composite (CC).

CONCLUSION

SM degrades the resin based restorative materials & among the tested materials Resin Modified GIC appears to be most Biostable.

Probing the neutralization behavior of zwitterionic monomer-containing dental adhesive

OBJECTIVE

To investigate the polymerization kinetics, neutralization behavior, and mechanical properties of amine-functionalized dental adhesive cured in the presence of zwitterionic monomer, methacryloyloxyethyl phosphorylcholine (MPC).

METHODS

The control adhesive was a mixture based on HEMA/BisGMA/2-N-morpholinoethyl methacrylate (MEMA) (40/30/30, w/w/w). The control and experimental formulations containing MPC were characterized with regard to water miscibility of liquid resins, photopolymerization kinetics, water sorption and solubility, dynamic mechanical properties and leachables from the polymers (aged in ethanol). The neutralization behavior of the adhesives was determined by monitoring the pH of lactic acid (LA) solution.

RESULTS

The water miscibility decreased with increasing MPC amount. The water sorption of experimental copolymer specimen was greater than the control. The addition of 8wt% water led to improved photo-polymerization efficiency for experimental formulations at MPC of 2.5 and 5wt%, and significant reduction in the cumulative amounts of leached HEMA, BisGMA, and MEMA, i.e. 90, 60 and 50% reduction, respectively. The neutralization rate of MPC-containing adhesive was faster than control. The optimal MPC concentration in the formulations was 5wt%.

SIGNIFICANCE

Incompatibility between MEMA and MPC led to a decrease in water miscibility of the liquid resins. Water (at 8wt%) in the MPC-containing formulations (2.5-5wt% MPC) led to higher DC, faster RPmax and significant reduction in leached HEMA, BisGMA, and MEMA. The neutralization rate was enhanced with the addition of MPC in the amine-containing formulation. Promoting the neutralization capability of dentin adhesives could play an important role in reducing recurrent decay at the composite/tooth interface.

Dental cavity liners for Class I and Class II resin-based composite restorations

BACKGROUND

Resin-based composite (RBC) is currently accepted as a viable material for the restoration of caries for posterior permanent teeth requiring surgical treatment. Despite the fact that the thermal conductivity of the RBC restorative material closely approximates that of natural tooth structure, postoperative hypersensitivity is sometimes still an issue. Dental cavity liners have historically been used to protect the pulp from the toxic effects of some dental restorative materials and to prevent the pain of thermal conductivity by placing an insulating layer between restorative material and the remaining tooth structure.

OBJECTIVES

The objective of this review was to assess the effects of using dental cavity liners in the placement of Class I and Class II resin-based composite posterior restorations in permanent teeth in children and adults.

SEARCH METHODS

Cochrane Oral Health's Information Specialist searched the following databases: Cochrane Oral Health's Trials Register (to 25 May 2016), the Cochrane Central Register of Controlled Trials (CENTRAL; 2016, Issue 4) in the Cochrane Library (searched 25 May 2016), MEDLINE Ovid (1946 to 25 May 2016), Embase Ovid (1980 to 25 May 2016) and LILACS BIREME Virtual Health Library (Latin American and Caribbean Health Science Information database; 1982 to 25 May 2016). We searched ClinicalTrials.gov and the World Health Organization International Clinical Trials Registry Platform for ongoing trials. No restrictions were placed on the language or date of publication when searching the electronic databases.

SELECTION CRITERIA

We included randomized controlled trials assessing the effects of the use of liners under Class I and Class II posterior resin-based composite restorations in permanent teeth (in both adults and children). We included both parallel and split-mouth designs.

DATA COLLECTION AND ANALYSIS

We utilized standard methodological procedures prescribed by Cochrane for data collection and analysis. Two review authors screened the search results and assessed the eligibility of studies for inclusion against the review inclusion criteria. We conducted risk of bias assessments and data extraction independently and in duplicate. Where information was unclear we contacted study authors for clarification.

MAIN RESULTS

Eight studies, recruiting over 700 participants, compared the use of dental cavity liners to no liners for Class I and Class II resin-based composite restorations.Seven studies evaluated postoperative hypersensitivity measured by various methods. All studies were at unclear or high risk of bias. There was inconsistent evidence regarding postoperative hypersensitivity (either measured using cold response or patient-reported), with a benefit shown at some, but not all, time points (low-quality evidence).Four trials measured restoration longevity. Two of the studies were judged to be at high risk and two at unclear risk of bias. No difference in restoration failure rates were shown at one year follow-up, with no failures reported in either group for three of the four studies; the fourth study had a risk ratio (RR) 1.00 (95% confidence interval (CI) 0.07 to 15.00) (low-quality evidence). Three studies evaluated restoration longevity at two years follow-up and, again, no failures were shown in either group.No adverse events were reported in any of the included studies.

AUTHORS' CONCLUSIONS

There is inconsistent, low-quality evidence regarding the difference in postoperative hypersensitivity subsequent to placing a dental cavity liner under Class I and Class II posterior resin-based composite restorations in permanent posterior teeth in adults or children 15 years or older. Furthermore, no evidence was found to demonstrate a difference in the longevity of restorations placed with or without dental cavity liners.

Laser use in direct pulp capping: A meta-analysis

BACKGROUND

The authors of this study evaluated the effects of lasers on the outcome of direct pulp capping by means of a meta-analysis.

TYPES OF STUDIES REVIEWED

The authors completed a literature search on PubMed, Cochrane Library, Embase, and China National Knowledge Infrastructure, as well as a manual search of the reference lists of all identified articles since the introduction of lasers in endodontics in 1971 through May 30, 2016. The authors systematically evaluated the studies that met the inclusion criteria and performed a meta-analysis.

RESULTS

The authors selected 5 studies about 4 laser systems (carbon dioxide; diode; erbium,chromium:yttrium-selenium-gallium-garnet; and erbium:yttrium-aluminum-garnet) from the 510 articles to be included in this meta-analysis. Using a fixed-effects model, they found no significant heterogeneity between these studies (χ² = 0.83, P = .99, I² = 0%). Their results showed that the success rate (89.9%) of the laser groups was higher than that of 67.2% of the control groups, and the difference was statistically significant (risk ratio, 1.35; 95% confidence interval, 1.23-1.49; P < .00001).

CONCLUSIONS AND PRACTICAL IMPLICATIONS

On the basis of the limited evidence, the use of lasers effectively improved the prognosis of direct pulp capping treatment for permanent teeth.

Monitoring of cariogenic demineralization at the enamel-composite interface using swept-source optical coherence tomography

OBJECTIVES

The aim of this study was to evaluate enamel demineralization at composite restoration margins caused by cariogenic biofilm using swept-source optical coherence tomography (SS-OCT).

METHODS

Sixty round-shaped cavities were prepared on the mid-buccal enamel surface of extracted human molars. The cavities were restored with Estelite Flow Quick flowable composite using either Clearfil SE Bond or Clearfil Tri-S Bond ND bonding agents. Streptococcus mutans suspension was applied to form a cariogenic biofilm on the surface. After 1, 2, or 3 weeks of incubation (n=10), the biofilm was removed to observe the carious demineralization at the cavosurface margins using SS-OCT. The gap along the enamel-composite interface was recorded on each adhesive system. Confirmatory direct observation was accomplished at the same location using confocal laser scanning microscope.

RESULTS

The demineralized enamel around the restorations was observed as a zone of intensified brightness in SS-OCT. The demineralized lesion on the cervical enamel was significantly deeper than that on the occlusal enamel (p<0.05). However, the extension of enamel demineralization at the enamel-composite interface was significantly deeper at the occlusal wall than the cervical wall (p<0.05). The extension in Tri-S Bond ND group was significantly deeper than in SE Bond group (p<0.05). A significant increase in gap formation was found after the extension of demineralization compared with the baseline.

SIGNIFICANCE

The carious demineralization around composite restorations were observed as a bright zone in SS-OCT during the process of bacterial demineralization. SS-OCT appears to be a promising modality for the detection of caries adjacent to an existing restoration.

Nestin expressions of exposed pulp after direct pulp capping by calcium hydroxide and platelet rich plasma

OBJECTIVE

The aim of this study was to evaluate nestin expression of pulp tissue following direct pulp capping with platelet-rich plasma (PRP).

MATERIALS AND METHODS

The thirty sound teeth from Sprague-Dawley rats were used and divided into two groups: Groups 1, teeth were capped with calcium hydroxide/Ca(OH)2 (n = 15) and Group 2 with PRP (n = 15). After 1(st), 7(th), and 21(st) days, respectively, 5 teeth each group (American Dental Association 41) were processed for light microscopic examination. Expressions of nestin were assessed by immunohistochemical techniques.

RESULTS

Nestin expression of Ca(OH)2 on the distance place of exposure at 1(st) and 7(th) days were 80% and at 21(st) day were 60%. Nestin expression of PRP on the distance place at 1(st) day was 80%, 7(th) 100%, and 21(st) day was 80%. At day 21 observation, Kruskal-Wallis test shows nestin expression was increased significantly in PRP groups (P < 0.05), but it was not increase significantly compare with Ca(OH)2.

CONCLUSION

PRP had ability as a direct pulp capping material to induce nestin expression.

Histological evaluation of mineral trioxide aggregate and enamel matrix derivative combination in direct pulp capping: An in vivo study

AIM

The aim of this study is to evaluate the response of human pulp tissue to mineral trioxide aggregate (MTA), Emdogain (EMD), and combination of MTA/EMD.

MATERIALS AND METHODS

This study was performed on sixty intact first and second premolars of human maxillary and mandibular teeth. A standard pulpal exposure was done on all the teeth and was divided into three groups of twenty teeth each and was capped with MTA, EMD, and MTA/EMD combination. The final restoration was done with resin-modified glass ionomer cement. The teeth were then extracted on the 15^th or 45^th day and histological evaluation done.

RESULTS

Differences in inflammatory response and thickness of dentin bridge formation of the exposed pulp to the three different groups were statistically evaluated using Chi-square and Mann-Whitney tests and were found to be significant. No significant difference was found between MTA/EMD and MTA in terms of calcified bridge formation and pulp inflammatory response to the capping materials.

CONCLUSIONS

MTA and MTA/EMD combination produced a better quality hard tissue response compared with the use of EMD.

Efficacy of Erbium, Chromium-doped:Yttrium, Scandium, Gallium, and Garnet Laser Irradiation Combined with Resin-based Tricalcium Silicate and Calcium Hydroxide on Direct Pulp Capping: A Randomized Clinical Trial

INTRODUCTION

The purpose of this randomized clinical study was to evaluate the efficiency of erbium, chromium-doped:yttrium, scandium, gallium, and garnet (Er,Cr:YSGG) laser irradiation combined with a resin-based tricalcium silicate material and calcium hydroxide in direct pulp capping for a 6-month follow-up period.

METHODS

A total of 60 teeth of 60 patients between the ages of 18 and 41 years were recruited for this study. Sixty permanent vital teeth without symptoms and radiographic changes were randomly assigned to the following 4 groups (n = 15): Gr CH, the exposed area was sealed with calcium hydroxide (CH) paste; Gr laser CH, the treated area was sealed with CH paste after Er,Cr:YSGG laser irradiation at an energy level of 0.5 W without water and with 45% air; Gr TheraCal, TheraCal LC (Bisco, Schaumburg, IL) was applied directly to the exposed pulp; and Gr Laser TheraCal, TheraCal LC was applied after irradiation with an Er,Cr:YSGG laser. At the 1-week and 1-, 3-, and 6-month recall examinations, the loss of vitality, spontaneous pain, reactions to thermal stimuli and percussion, and radiographic changes were considered as failure.

RESULTS

The success rates in the CH and TheraCal groups were 73.3% and 66.6%, respectively. These rates did not reveal any significant difference. In both laser groups, success rates were 100%. The Er,Cr:YSGG laser-irradiated TheraCal and Er,Cr:YSGG laser-irradiated CH groups showed statistically higher success rates than the TheraCal and CH groups, respectively.

CONCLUSIONS

Er,Cr:YSGG laser irradiation at 0.5 W without water combined with pulp capping agents can be recommended for direct pulp therapy.

Pulp response to high fluoride releasing glass ionomer, silver diamine fluoride, and calcium hydroxide used for indirect pulp treatment: An in-vivo comparative study

Aims and Objectives:

The study aims at determining pulp response of two high fluoride releasing materials silver diamine fluoride (SDF) and Type VII glass ionomer cement (GIC) when used as indirect pulp treatment (IPT) materials.

Materials and Methods:

Deep Class V cavities were made on four first premolars indicated for extraction for orthodontic reasons. SDF, Type VII GIC, and calcium hydroxide base are given in three premolars, and one is kept control. Premolars were extracted 6 weeks after the procedure and subjected to histopathological examination to determine the pulp response. The results were analyzed using Chi-square test.

Results:

No inflammatory changes were observed in any of the groups. Significantly more number of specimens in SDF and Type VII GIC groups showed tertiary dentin deposition (TDD) when compared to control group. No significant difference was seen in TDD when intergroup comparison was made. Odontoblasts were seen as short cuboidal cells with dense basophilic nucleus in SDF and Type VII GIC group.

Conclusion:

The study demonstrated TDD inducing ability of SDF and Type VII GIC and also established the biocompatibility when used as IPT materials.

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.