Restoration of endodontically treated teeth review and treatment recommendations

Advancing Adhesive Strategies for Endodontically Treated Teeth-Part II: Dentin Sealing Before Irrigation Increases Long-Term Microtensile Bond Strength to Coronal Dentin

OBJECTIVE

To compare the long-term microtensile bond strength (μTBS) to coronal dentin using pre-endodontic dentin sealing (PEDS) and post-endodontic adhesion (PEA) techniques under various endodontic irrigation protocols.

MATERIALS AND METHODS

Ten study groups (n = 10) were established based on the timing of adhesive application (PEDS versus PEA) and irrigation protocol: distilled water (control), 3% sodium hypochlorite (NaOCl), 3% NaOCl followed by 17% ethylenediaminetetraacetic acid (EDTA), 3% NaOCl followed by 17% EDTA and 2% chlorhexidine, and a mixture of 3% NaOCl and 9% etidronic acid (HEDP). Specimens underwent μTBS testing after a six-month microspecimen aging period. Fracture patterns were analyzed, and adhesive interfaces were assessed using scanning electron microscopy (SEM). Statistical analysis employed a mixed linear regression model with a 5% significance level.

RESULTS

PEDS consistently preserved high bond strength across all irrigation protocols (57.4-59.5 MPa), while PEA groups treated with endodontic irrigants resulted in significantly lower values (33.3-40.8 MPa; p < 0.001). No significant differences were observed within the PEDS groups (p > 0.05). SEM analysis revealed consistent hybrid layers in PEDS and PEA/Control groups, while PEA groups treated with endodontic irrigation solutions showed significant resin-dentin interface variations and interfacial gaps.

CONCLUSIONS

The PEDS technique preserved high and consistent μTBS regardless of the irrigation protocol, whereas endodontically irrigated PEA groups exhibited significantly reduced bond strength. PEDS offers a predictable approach to optimizing adhesive performance in endodontic-restorative treatments.

CLINICAL SIGNIFICANCE

Integrating PEDS into routine endodontic-restorative workflow is recommended to enhance long-term bond strength to coronal dentin. The PEDS technique ensures consistent adhesive performance regardless of the endodontic irrigation protocol, enhancing restorative predictability and treatment success while preserving tooth structure.

Influence of cement type on the bond strength of orthodontic bands to zirconia crowns

BACKGROUND

This study evaluated the retentive strength and residual cement of orthodontic bands bonded to zirconia crowns using four cementation protocols: Glass-ionomer cement (GIC), Resin-modified glass ionomer cement (RMGIC), Transbond Plus Light Cure Band Adhesive without silane, and Transbond Plus with silane primer application.

MATERIALS AND METHODS

Sixty zirconia crowns were divided into four groups (15 each) and cemented with the respective cements. Each crown was mounted on a resin-based tooth-like structure and secured to a universal testing machine. Orthodontic bands were adapted to the crowns, and forces were applied to measure retentive strength. After debonding, the remaining cement was assessed using the Adhesive Remnant Index (ARI). Specimens underwent thermocycling (5,000 cycles between 5 °C and 55 °C) to simulate oral conditions.

RESULTS

The mean retentive strength was 1.23 MPa. Group 4 (Transbond Plus with silane) exhibited the highest strength (1.44 MPa), while group 1 (GIC) demonstrated the lowest (0.85 MPa). Cementation protocol significantly influenced retentive strength, with groups 2 (RMGIC) and 4 showing superior results to groups 1 and 3 (Transbond Plus without silane).

CONCLUSION

The cement type and protocol employed significantly affect the shear-peel bond strength of orthodontic bands cemented to zirconia crowns. RMGIC and Transbond Plus, especially with silane, provide superior retention compared to GIC.

Unveiling the mechanical performance of partially replaced coronal restorations in root canal-treated teeth: an in-vitro study

OBJECTIVES

To compare the mechanical performance of partially replaced (repaired) intra-coronal restorations to totally replaced ones in root canal-treated teeth.

METHODS

Thirty maxillary second premolars were selected according to strict criteria, mounted on moulds, and had mesio-occluso-distal (MOD) cavities prepared. Resin composite restorative material was used to perform the initial restoration, followed by aging procedures using thermo-mechanical cycling fatigue to replicate six months of intraoral aging. The specimens were then randomly divided into two groups: a totally replaced restoration (TR) group (n = 15), which involved the preparation of a traditional endodontic access cavity after the complete removal of the pre-existing coronal filling; and a partially replaced restoration (PR) group (n = 15), which involved accessing the tooth through the pre-existing restoration without completely removing it. Root canal preparation and filling procedures were conducted, and the access cavity was sealed with a new resin composite restoration, followed by a new thermo-mechanical cycling aging procedure. Finally, the specimens were submitted to a static fracture test to measure specimen fracture strength and determine the failure mode pattern (repairable fracture or irreparable fracture). Chi-square and t-tests were used for statistical analysis.

RESULTS

Significant differences between the groups regarding their mechanical resistance were found. The average failure load of the TR group was 1115.13 N and 1330.23 N in the PR group (p = 0.002). Regarding the failure modes, the TR group exhibited eight irreparable fractures, while the PR group had four (p = 0.136).

CONCLUSIONS

Partially replaced restorations presented higher fracture strength and led to fewer irreparable fractures when compared to totally replaced restorations in root canal-treated teeth.

A Finite Element Method Study of Stress Distribution in Dental Hard Tissues: Impact of Access Cavity Design and Restoration Material

The design of the access cavity is an important factor in endodontic treatment for the further evolution of the tooth. The objective of this study was to highlight the most favorable access cavity design (TrussAC, UltraAC, TradAC, CariesAC, ConsAC, RestoAC) based on the stress distribution on virtual models of mandibular molars. To achieve the objectives of the study, four series of virtual models of six molars were made. The first two series of external virtual models were obtained based on the three-dimensional scanning of the molars before the access cavity preparation and after their restoration, to obtain the density of the restorative materials. Internal morphology was added to the next two series of virtual models and after that, materials were added, specific for root canal obturation and coronal restoration. The simulations were performed for two coronary restoration materials, bulk fill composite and amalgam. The results showed, based on the stress maps, that the highest values were recorded for CariesAC and the lowest values for UltraAC. Comparing the two restorative materials, the lowest level of stress, strains, and displacements was highlighted in the case of UltraAC, TradAC, and ConsAC cavities for amalgam. The results obtained in this study should guide doctors towards a conservative attitude with the preservation of as much hard tissue as possible and the differentiated use of restorative materials according to the amount of tissue lost when preparing the access cavity.

Adhesion and sealing of different universal adhesive systems associated with bulk-fill resins after using endodontic irrigation solutions: An in vitro study

This study aimed to evaluate the interface of universal adhesive (UA) with bulk-fill resin (BF) and dentin, after endodontic irrigation. The pulp chamber of 96 molars was irrigated with chlorhexidine 2% (CHX) or sodium hypochlorite 5.25% (NaOCl) and restored according to three restorative protocols. Microtensile bond strength (μTBS) and nanoleakage tests were performed after 24 h of thermocycling. Kruskal Wallis, Mann-Whitney and Wilcoxon were performed (p < 0.05). Comparing restorative systems, a difference was found only when irrigated with CHX after 24 h. CHX provided higher μTBS than NaOCl after 24 h for two restorative protocols; after thermocycling, NaOCl provided the greatest μTBS than CHX for one group. Decreased μTBS was observed for all restorative systems when CHX was used after thermocycling. NaOCl demonstrated the highest nanoleakage. The composition of UA influenced the immediate adhesion and sealing to BF when CHX was used; ageing has a deteriorating effect on adhesion and sealing for all restorative systems.

Effect of remaining pericervical dentin on biomechanical behavior of endocrown-restored molars with different materials: Three-dimensional finite element and Weibull analyses

To evaluate the effect of remaining pericervical dentin (PCD) on the biomechanical behavior of endocrown-restored molars with different materials, six three-dimensional finite element (FE) models were reconstructed with different thicknesses and heights of pulp-chamber lateral dentinal wall (PCLDW). IPS Empress 2, In-Ceram Zirconia, and Lava Ultimate were selected as the materials. Compared with the Lava Ultimate FE models, the maximum tensile stress in the FE models using ceramics was higher in the endocrown and lower in the PCD surrounding it, and the overall failure probabilities with different PCLDW thicknesses and heights were similar, ranging from 9.8% to 12.9% under the normal lateral masticatory force, which were lower than the FE models using Lava Ultimate (ranging from 13.4% to 15.1%). Considering the bonding properties of ceramics, endocrown-restored molars using etchable lithium disilicate-reinforced glass ceramic exhibit superior longevity due to the stress shielding effect, regardless of the thickness and height of PCLDW.

A Comparative Study of the Marginal Fit of Endocrowns Fabricated From Three Different Computer-Aided Design/Computer-Aided Manufacturing (CAD/CAM) Ceramic Materials: An In Vitro Study

INTRODUCTION

The marginal seal and adaptation are important factors for successful restoration. An inadequate marginal seal can lead to bacterial microleakage, plaque accumulation, and eventually treatment failure This in vitro study aimed to compare the marginal gap of endocrowns fabricated from three different computer-aided design/computer-aided manufacturing (CAD/CAM) ceramic materials.

METHODS

Thirty extracted mandibular molars were selected for the study. Endocrown preparations were completed after root canal treatment. Teeth were divided into three groups to receive endocrowns fabricated of lithium disilicate ceramic (IPS-e.max CAD, Ivoclar Vivadent AG, Schaan, Liechtenstein), zirconia-reinforced lithium silicate ceramic (VITA Suprinity®, VITA Zahnfabrik, Bad Säckingen, Germany), and polymer-infiltrated ceramic (VITA Enamic®, VITA Zahnfabrik). The digital impressions were transferred to the design software to construct the endocrowns. The endocrowns were milled and cemented. The marginal fit was examined using a digital camera stereomicroscope at a magnification of 80X. Images were transferred to Image-J software (National Institutes of Health, Bethesda, Maryland, United States) to measure the marginal gap.

RESULTS

One-way ANOVA showed a significant difference in the marginal gap between the different ceramic groups (P=0.006). Tukey's Honest Significant Difference (HSD) post-hoc test showed that VITA Suprinity had significantly higher gap width values than VITA Enamic (P=0.005). No significant differences in gap width values were found between VITA Enamic and IPS e.max CAD or between VITA Suprinity and IPS e.max CAD (P>0.05).

CONCLUSION

The marginal gap of endocrown restorations varies with different CAD/CAM materials (zirconia-reinforced lithium silicate glass-ceramic, polymer-infiltrated hybrid ceramic, and lithium disilicate glass-ceramic), but are all within clinically acceptable marginal gap width.

A Retrospective Study on Endodontic Treatment Outcomes in Patients with Special Needs

INTRODUCTION

Outcomes of endodontic treatment in patients with special needs are not fully understood, leading to reluctance in performing endodontic treatment.

METHODS

This retrospective cohort study evaluated the periapical healing and tooth survival in patients with special needs who had permanent teeth endodontically treated in a hospital setting between 1998 to 2019. Data characterization was performed using univariate analyses. Logistic and Cox regression analyses (P<0.05) were performed to identify the odds ratio (OR) and hazard ratio (HR) of the potential prognostic factors, respectively. These predictors were chosen from previous outcome studies in the general population and patients with special needs.

RESULTS

61 patients (108 teeth) met the inclusion criteria. Most common treatment modality was initial therapy with 81.5% of cases being managed without a need for general anesthesia. Healing rate for initial endodontic treatment was 89.9% and was affected by no restoration at follow-up (OR=0.15, 95%CI:0.12, 0.71, P=0.02). After a mean follow up of 79.36±59.6 months, the survival rate was 73% and was correlated with gender (HR for males = 0.3; 95% CI, 0.1-0.6; P <0.05) and age (HR for patients >45 years = 3.7; 95% CI, 1.7-8.2; P<0.05). The most common reason for tooth extraction was unrestorable tooth fracture.

CONCLUSIONS

Endodontic therapy without a need for general anesthesia is a viable treatment option for patients with special needs. If the overall patient condition permits, then treatment can be administered by community dentists rather than waiting for a patient to be seen in a hospital setting.

Clinical performance of resin-matrix ceramic partial coverage restorations: a systematic review

OBJECTIVE

To evaluate clinical performance of the new CAD/CAM resin-matrix ceramics and compare it with ceramic partial coverage restorations.

MATERIALS AND METHODS

An electronic search of 3 databases (The National Library of Medicine (MEDLINE/PubMed), Scopus, and the Cochrane Central Register of Controlled Trials) was conducted. English clinical studies published between 2005 and September 2020 that evaluated the clinical performance of CAD/CAM resin-matrix ceramics inlays, onlays, or overlays were selected. The primary clinical question was applied according to PICOS strategy (Population, Intervention, Comparison, Outcome, Study design). The included studies were individually evaluated for risk of bias according to the modified Cochrane Collaboration tool criteria.

RESULTS

A total of 7 studies were included according to the established inclusion and exclusion criteria. From the included studies, 6 were randomized clinical trials while one study was longitudinal observational study without control group. According to the results of the included studies, the success rate of CAD/CAM resin-based composite ranged from 85.7 to 100% whereas the success rate reported for ceramic partial coverage restorations ranged from 93.3 to 100%. Fractures and debondings are found to be the most common cause of restorations failure.

CONCLUSION

CAD/CAM resin-based composite can be considered a reliable material for partial coverage restorations with clinical performance similar to glass ceramic restorations. However, this result needs to be confirmed in long-term evaluations.

CLINICAL RELEVANCE

CAD/CAM resin-based composites provide a potential alternative to ceramic indirect restorations. However, clinicians must be aware of the lake of knowledge regarding long-term outcome.

Interfacial Biomaterial-Dentin Bacterial Biofilm Proliferation and Viability Is Affected by the Material, Aging Media and Period

Biomaterial−dentin interfaces undergo degradation over time, allowing salivary, tissue fluid, and bacterial movement between the root filling or restoration and dentin. This study aims to investigate the effect of aging in simulated human salivary/bacterial/blood esterases (SHSE) on proliferation and viability of Enterococcus faecalis biofilm within the dentin interface with four materials used to fill/restore the endodontic space. Root canals of human anterior teeth were prepared and filled with gutta-percha and one of the following: self-cured resin composite (BisfilTM 2B, Bisco, Schaumburg, IL, USA) with either self-etch (SE) (EasyBond) or total-etch (TE) (ScotchbondTM, 3M, Saint Paul, MN, USA) methacrylate-based adhesives, epoxy-resin sealer (AH Plus®, Dentsply Sirona, York, PA, USA), or bioceramic sealer (EndoSequence® BC Sealer™, Brasseler USA, Savannah, GA, USA). Specimens were aged in SHSE or phosphate-buffered saline (PBS) for up to 360 days, followed by cultivation of steady-state E. faecalis biofilm. Depth and viability of interfacial bacterial biofilm proliferation were assessed by confocal laser scanning microscopy and live/dead staining. Data were analyzed using three-way ANOVA and Scheffe’s post hoc analyses. Initial depths of biofilm proliferation were similar among material groups (p > 0.05). All groups showed significantly deeper biofilm proliferation with increased aging period (p < 0.05). SHSE aging increased interfacial biofilm depth for TE, SE and BC (p < 0.05) but not AH. For unaged interfaces, BC exhibited the lowest ratio of live bacteria, followed by AH, TE, and SE (p < 0.05). Interfacial bacterial biofilm proliferation and viability were dependent on the biomaterial, aging media, and period.

Taurodontism—Prevalence, Extent, and Clinical Challenge in Ashkelon, Israel—A Retrospective Study

Taurodontism, a known morpho-anatomic variation in the shape of teeth, has already attracted substantial attention. The aim of this study is to contribute to this by discussing its direct impact on the dental practitioner via an evaluation of the prevalence of taurodontism in molars in Ashkelon, Israel. This retrospective study analyzed panoramic radiographs of 624 patients (330 males, 294 females), aged of 9–29 years—2849; first and second permanent molars were screened. Objective measurements and variables were used and analyzed using statistical SPSS version 27 (IBM, Chicago, IL, USA). Taurodontism was observed in 33.6% of the patients and was more prevalent among females (53% vs. 47%) and in maxillary molars compared to mandibular molars (57% vs. 43%). The overall prevalence of hypotaurodontism, mesotaurodontism, and hypertaurodontism was 10.8%, 0.5%, and 0.2%, respectively. No statistical difference between right and left sides was discovered, however, taurodont teeth in the upper left side exhibited the highest frequency, while the lower left side had the least. The highest occurrence of hypotaurodontism was on the upper right second molar followed by upper left first and second molars. The clinical challenge posed in endodontic, orthodontic, and restorative dentistry is discussed, and suitable alternative approaches are proposed for dental practitioners.

Sealing Ability of Various Types of Root Canal Sealers at Different Levels of Remaining Gutta Percha After Post Space Preparation at Two Time Intervals

OBJECTIVE

This study evaluated the apical sealing ability of various types of sealers (Sure-Seal Root, AH Plus, and GuttaFlow2) at different levels of remaining gutta percha after post space preparation at two time intervals (1 day and 1 week after obturation).

MATERIALS AND METHODS

One hundred and two single canal mandibular premolars were decoronated at the cement-enamel junction and biomechanically prepared. Twelve samples served as negative and positive controls (n = 6). The remaining 90 samples were distributed into three groups (n = 30 each), based on the used sealer for obturation with gutta percha (Sure-Seal Root, AH Plus, GuttaFlow2). Each experimental group was divided into two subgroups (n = 15 each), subgroup I: post space prepared 1 day after obturation and subgroup II: post space prepared 1 week after obturation. For each subgroup, the post space was prepared to a length that remained 3, 4, or 5 mm of gutta percha apically for each of five samples. Then, the dye penetration technique was used to measure the apical microleakage. Data were analyzed using "ANOVA test" and "post hoc Duncan's test."

RESULTS

Sure-Seal Root sealer demonstrated the best apical seal compared with other tested sealers. Post space preparation 1 day after obturation exhibited less microleakage than the group with 1 week after obturation. Additionally, 5 mm of remaining gutta percha showed superior sealing value than 3 and 4 mm.

CONCLUSION

Bioceramic (Sure-Seal) sealer is the material of choice to be used when post space preparation is required. Post space preparation was preferred to be done 1 day after obturation than 1 week after obturation. Superlative apical seal was obtained with a maximum length of remaining gutta percha.

What Are the Chances of Resilon to Dominate the Market Filling Materials for Endodontics?

This paper is a literature review with additional virtual analyses of the authors’ own experimental research results. Knowledge from various areas was synergistically combined, appropriately for concurrent engineering, presenting several possible methodological approaches used in research, optimizing the selection of engineering materials and the conditions of their application with particular application in endodontics. Particular attention was paid to the theoretical aspects of filling material strengths, weaknesses, opportunities, and threats SWOT analysis. Attention was paid to the original concepts of Sustainable Dentistry Development in conjunction with Dentistry 4.0, which includes endodontics as an important element. The dentists’ actions, among others, in conservative dentistry, along with endodontics, requires close cooperation with engineers and the enginering sciences. Methods of root canal preparation were described, together with selected tools, including those made of nitinol. Principles concerning the process of cleaning and shaping the pulp complex are presented. The importance of obturation methods, including the Thermo-Hydraulic-Condensation THC technique, and the selection of filling materials with the necessary sealants for the success of endodontic treatment are discussed. The experimental studies were carried out in vitro on human teeth removed for medical reasons, except for caries, for which two groups of 16 teeth were separated. After the root canal was prepared, it was filled with studs and pellets of a filling material based on polyester materials, which has gained the common trade name of resilon or, less frequently, RealSeal (SybronEndo) with an epiphany sealant. The teeth for the first group were obturated by cold lateral condensation. In the second case the obturation was performed using the Thermo-Hydraulic-Condensation technique using System B and Obtura III. The experimental leakage testing was done using a scanning electron microscope SEM and a light stereoscopic microscope LSM, as typical research tools used in materialography. The research results, in a confrontation with the data taken from the literature studies, do not indicate the domination of resilon in endodontics.

Pediatric Endodontic Treatment of Adolescent Patients

This article is intended to familiarize clinicians with several pulp therapy modalities and new materials that are currently available for immature young pulp in the adolescent population. Objectives and considerations for immature young permanent teeth as well as the healing potential of the young pulp tissue after treatment of the inflammatory process are discussed. The article emphasizes that the future holds great possibilities for the regeneration of dental pulp in adolescent patients.

Virtual Approach to the Comparative Analysis of Biomaterials Used in Endodontic Treatment

The importance of endodontics is presented within our own concept of Dentistry Sustainable Development (DSD) consisting of three inseparable elements; i.e., Advanced Interventionist Dentistry 4.0 (AID 4.0), Global Dental Prevention (GDP), and the Dentistry Safety System (DSS) as a polemic, with the hypothesis of the need to abandon interventionist dentistry in favour of the domination of dental prevention. In view of the numerous systemic complications of caries that affect 3−5 billion people globally, endodontic treatment effectively counteracts them. Regardless of this, the prevention of oral diseases should be developed very widely, and in many countries dental care should reach the poorest sections of society. The materials and methods of clinical management in endodontic procedures are characterized. The progress in the field of filling materials and techniques for the development and obturation of root canals is presented. The endodontics market is forecast to reach USD 2.1 billion in 2026, with a CAGR of 4.1%. The most widely used and recognized material for filling root canals is gutta-percha, recognized as the “gold standard”. An alternative is a synthetic thermoplastic filler material based on polyester materials, known mainly under the trade name Resilon. There are still sceptical opinions about the need to replace gutta-percha with this synthetic material, and many dentists still believe that this material cannot compete with gutta-percha. The results of studies carried out so far do not allow for the formulation of a substantively and ethically unambiguous view that gutta-percha should be replaced with another material. There is still insufficient clinical evidence to formulate firm opinions in this regard. In essence, materials and technologies used in endodontics do not differ from other groups of materials, which justifies using material engineering methodology for their research. Therefore, a detailed methodological approach is presented to objectify the assessment of endodontic treatment. Theoretical analysis was carried out using the methods of procedural benchmarking and comparative analysis with the use of contextual matrices to virtually optimize the selection of materials, techniques for the development and obturation of root canals, and methods for assessing the effectiveness of filling, which methods are usually used, e.g., in management science, and especially in foresight research as part of knowledge management. The results of these analyses are presented in the form of appropriate context matrices. The full usefulness of the research on the effectiveness and tightness of root canal filling using scanning electron microscopy is indicated. The analysis results are a practical application of the so-called “digital twins” approach concerning the virtual comparative analysis of biomaterials used in endodontic treatment.

Drug-Silica Coassembled Particles Improve Antimicrobial Properties of Endodontic Sealers

INTRODUCTION

The purpose of this study was to assess the antimicrobial activity and flow of root canal sealers after incorporating novel highly loaded antimicrobial drug-silica coassembled particles (DSPs).

METHODS

DSPs were synthesized through coassembly of silica and octenidine dihydrochloride (OCT) antimicrobial surfactant. DSPs were loaded (1% and 2% wt) into epoxy resin sealer (AH Plus [AH]; Dentsply DeTrey GmbH, Konstanz, Germany) or calcium silicate-based sealer (EndoSequence Bioceramic Sealer (BC); Brasseler, Savannah, GA). OCT release from DSP-modified sealers was determined using liquid chromatography. Antimicrobial activity of sealers against planktonic or biofilm form Enterococcus faecalis was assessed using direct contact and membrane restricted tests. Sealer flow was tested according to ISO6876:2012.

RESULTS

OCT release from BC + 1% or 2% DSPs was above the minimum inhibitory concentration following 2 days throughout the 30-day experiment, whereas OCT release from AH + 1% or 2% DSP was significantly below the minimum inhibitory concentration against E. faecalis (4 μg/mL) over the whole 30-day experimental period. All materials (with or without DSPs) killed planktonic bacteria initially. AH ± 1% or 2% DSPs had no antimicrobial activity after 7 days. BC + 1% or 2% DSPs maintained antibacterial activity over the 30-day period. Both modified and unmodified sealers completely inhibited the growth of E. faecalis biofilms after 24 hours of contact. DSPs decreased the flow of AH and BC sealers; for AH, the reduction was proportional to the amount of DSPs added. All modified and unmodified sealers, except for AH + 2% DSPs, were within the acceptable limits of ISO 6876 flow tests.

CONCLUSIONS

DSPs enhanced the antimicrobial performance of BC but not AH, whereas the material's flow remained compliant with ISO 6876 standards. Depending on the sealer, DSPs may enhance antimicrobial efficacy in root canal treatment and potentially improve treatment outcome.

Comparison between immediate and delayed post space preparations: a systematic review and meta-analysis

OBJECTIVES

This systematic review and meta-analysis compared the effects of immediate and delayed post space preparation on apical sealing.

MATERIALS AND METHOD

Two independent authors conducted a systematic search (PubMed/Medline, Cochrane Library, and other databases, until February 2020) and a risk of bias evaluation. Only in vitro studies that compared the effects of immediate and delayed post space preparations on apical filling and adhesion of the post were eligible.

RESULT

Of the 742 articles retrieved, 32 were included. Most of the studies used single-rooted human teeth and rotary files for root canal preparation, a single-cone technique for the filling protocol, and rotary instruments for post space preparation. Various delayed preparation times were evaluated: 8-72 h, 5-30 days (mainly 7 days), and 4 months. In nine studies, the delayed groups showed more apical leakage, while four studies reported more leakage in the immediate groups; ten studies found no significant difference. One study found more bacterial penetration in the delayed group, whereas three studies showed no significant difference. One study reported more voids in the delayed group, while another found no such difference. Three studies showed better post-bond strength in the delayed group, one in the immediate group, whereas three found no significant difference in post-bond strength. Three studies employing varied sealers for root canal fillings were considered for meta-analysis. Two subgroup analyses were also performed (one concerning the use of resin-based sealers (AH Plus), another for zinc oxide-eugenol-based sealers). The results of the meta-analysis showed that a delayed post space preparation led to a significantly higher apical leakage than an immediate preparation (mean difference = 0.41 mm, confidence interval = 0.24-0.59, p < 0.001).

CONCLUSION

Delayed post space preparation seems to negatively influence apical sealing; however, further studies are needed to determine the influence of the timing of post space preparation on the other parameters.

CLINICAL RELEVANCE

Immediate post space preparation may be the safest clinical choice to prevent apical leakage.

The Concept of Sustainable Development of Modern Dentistry

This paper concerns the assessment of the current state of dentistry in the world and the prospects of its sustainable development. A traditional Chinese censer was adopted as the pattern, with a strong and stable support on three legs. The dominant diseases of the oral cavity are caries and periodontal diseases, with the inevitable consequence of toothlessness. From the caries 3.5–5 billion people suffer. Moreover, each of these diseases has a wide influence on the development of systemic complications. The territorial range of these diseases and their significant differentiation in severity in different countries and their impact on disability-adjusted life years index are presented (DALY). Edentulousness has a significant impact on the oral health-related quality of life (OHRQoL). The etiology of these diseases is presented, as well as the preventive and therapeutic strategies undertaken as a result of modifying the Deming circle through the fives’ rules idea. The state of development of Dentistry 4.0 is an element of the current stage of the industrial revolution Industry 4.0 and the great achievements of modern dental engineering. Dental treatment examples from the authors’ own clinical practice are given. The systemic safety of a huge number of dentists in the world is discussed, in place of the passive strategy of using more and more advanced personal protective equipment (PPE), introducing our own strategy for the active prevention of the spread of pathogenic microorganisms, including SARS-CoV-2. The ethical aspects of dentists’ activity towards their own patients and the ethical obligations of the dentist community towards society are discussed in detail. This paper is a polemic arguing against the view presented by a group of eminent specialists in the middle of last year in The Lancet. It is impossible to disagree with these views when it comes to waiting for egalitarianism in dental care, increasing the scope of prevention and eliminating discrimination in this area on the basis of scarcity and poverty. The views on the discrimination of dentistry in relation to other branches of medicine are far more debatable. Therefore, relevant world statistics for other branches of medicine are presented. The authors of this paper do not agree with the thesis that interventional dental treatment can be replaced with properly implemented prophylaxis. The final remarks, therefore, present a discussion of the prospects for the development of dentistry based on three pillars, analogous to the traditional Chinese censer obtaining a stable balance thanks to its three legs. The Dentistry Sustainable Development (DSD) > 2020 model, consisting of Global Dental Prevention (GDP), Advanced Interventionist Dentistry 4.0 (AID 4.0), and Dentistry Safety System (DSS), is presented.

Mechanical and thermal stress evaluation of PEEK prefabricated post with different head design in endodontically treated tooth: 3D-finite element analysis

An endodontic post is required to retain and support the core restoration in case of insufficient remaining coronal dentin after root canal therapy. This study analyzed the biomechanical and thermal behavior of PEEK prefabricated post after choosing the head design that produces the least amount of stress on the core and remaining tooth structure. These results were compared with the most common commercially available prefabricated post, which is titanium and glass fiber post. Thus a CBCT scanning of a maxillary central incisor with its supporting structure was used to construct a 3D solid model of an endodontically treated teeth for finite element analysis (FEA). The restored tooth with the spherical head design of PEEK prefabricated post yielded a more benign stress distribution and repairable failure mode on the crown, luting cement, core, and dentin under both mechanical and thermal loads, followed by glass fiber post and titanium post respectively.

Fracture Resistance of Ceramic Crowns Supported with Indirect Chair-side Composite Cores

Aims and Objectives

To evaluate the influence of indirect chair-side polymerization of resin composite cores on the fracture resistance of overlaying IPS e.max Press crowns.

Materials and Methods

Root canals of 60 extracted premolars were prepared to receive #2 fiber posts after the crowns were sectioned 2 mm above the cervical line. In Groups 1-3 (n = 10 each), posts were luted to the prepared dowel spaces using self-adhesive resin cement. Resin composite cores were then bonded and incrementally built-up using Filtek Z250 XT, Filtek P60, and Filtek P90 resin composites. In Groups 4-6 (n = 10 each), the fabricated post-core systems were subjected to post-curing heat and pressure treatment before cementation to their respective teeth using self-adhesive resin cement. Another 10 sound premolars served as control. All teeth in the test and control groups were then subjected to standardized preparation to receive IPS e.max Press crowns before testing their fracture resistance and the mode of restorations' failure. The collected results were statistically analyzed using ANOVA, Kruskal-Wallis, and Tukey's tests on the past software used at α = 0.05 to stand on the significance of the detected differences.

Results

Significant differences were detected between the fracture resistance of teeth in different groups (ANOVA, P = 2.857E-35). Crowns in Groups 4-6 provided higher fracture resistance than those in Groups 1-3 (Tukey's test, P < 0.05). Crowns in Groups 4 and 6 provided higher fracture resistance than the control, while those in Groups 2 and 3 provided lower fracture resistance than the control (Tukey's test, P < 0.05).

Conclusion

Indirect composite cores improved the fracture resistance of IPS e.max Press crowns when compared to directly fabricated post and cores. The directly and indirectly polymerized nanohybrid, methacrylate-based composite (Filtek Z250 XT) cores yielded the highest fracture resistance for the utilized all-ceramic crowns.

Enterococcus faecalis Hydrolyzes Dental Resin Composites and Adhesives

INTRODUCTION

After root canal treatment, the dentin-sealer interface undergoes degradation, allowing for interfacial microbial biofilm proliferation and treatment failure. Saliva and cariogenic bacteria showed esterase-like activities (ie, cholesterol esterase [CE]-like and/or pseudocholinesterase [PCE]-like) that degrade methacrylate-based resin materials and/or the restoration-tooth interface, increasing microbial interfacial proliferation. Enterococcus faecalis is a gram-positive bacterium that is commonly detected in persistent endodontic infections. The aim of this study was to measure E. faecalis esterase-like, CE-like, and PCE-like activities and to assess the ability of the bacterium to degrade methacrylate-based resin composite (RC) and total-etch (TE) and self-etch (SE) adhesives.

METHODS

CE-like and PCE-like activities from E. faecalis were measured using nitrophenyl and butyrylthiocholine substrates, respectively. The ability of E. faecalis to degrade resin composite, total-etch and self-etch adhesives was examined by quantifying the release of a universal resin degradation by-product (ie, Bis[hydroxypropoxy]-phenyl propane [BisHPPP]) using high-performance liquid chromatography.

RESULTS

E. faecalis showed CE-like (1.23 ± 0.13 U/μg dry bacteria) but no PCE-like activity. After 30 days and/or 14 days of incubation, the amount of BisHPPP released was significantly higher in the presence of bacteria versus media for TE and RC but not SE (P < .05). The amount of BisHPPP released after 30 days of incubation with bacteria was highest for TE (23.69 ± 1.72 μg/cm²) followed by RC (3.43 ± 1.20 μg/cm²) and lowest for SE (0.86 ± 0.44 μg/cm²) (P < .05).

CONCLUSIONS

E. faecalis possesses esterase-like degradative activity toward dental methacrylate resin restoration materials, which could accelerate the degradation of the dentin-methacrylate resin interface, increasing bacterial biofilm proliferation and penetration into the root canal system.

Impact of Root Dentin Thickness on the in vitro Compressive Strength of Teeth treated with Recent Post and Core Systems

INTRODUCTION

Endodontically treated teeth dry with time, and its dentin undergoes changes making the teeth brittle and friable. The main function of a post is to strengthen or reinforce a weakened root. However, doing a post and core frequently requires the removal of sound tooth tissue. Recent materials introduced in the market for post and cores have been promising.

AIM

The aim of this study is to evaluate the fracture resistance of endodontically treated extracted permanent teeth with variable remaining root dentin thickness after post space preparation.

MATERIALS AND METHODS

A total of 270 freshly extracted permanent maxillary central incisors with fully formed apices were selected, decoronated at cementoenamel junction, and divided into three main groups according to remaining root dentin thickness, determined using a Vernier caliper into 0.5, 1, and 1.50 mm after post space preparation. Each group was further divided into three subgroups (subgroup a: Custom-made cobalt-chromium alloy post and core; subgroup b: Prefabricated glass fiber post and composite core; and subgroup c: EverStick fiber post). Each specimen was subjected to compressive load using universal testing machine. The force required to fracture was recorded and data were analyzed using analysis of variance (ANOVA) test.

RESULTS

Analysis of variance revealed that compressive strength of the tooth is significantly affected by the increase in the remaining dentin thickness after post space preparation (p < 0.05). Furthermore, teeth with custom fabricated posts showed a significantly higher compressive strength (p < 0.05) than prefabricated glass fiber post and EverStick fiber post groups except the group with minimum remaining dentin thickness.

CONCLUSION

The present in vitro study revealed that compressive strength of the post and core systems is directly related to the amount of healthy remaining dentin thickness. Hence, efforts to maximize the preservation of natural dentin should be taken during post space preparation.

A Radiographic Study of the Association between Apical Periodontitis and Technical Quality of Intraradicular Posts and Root Canal Fillings: A Cross-sectional Study in Qassim Region, Saudi Arabia

OBJECTIVES

This study evaluates the association between the apical periodontitis (AP) and quality of intraradicular posts and the quality of root fillings assessed radiographically in Qassim region, Saudi Arabia.

MATERIALS AND METHODS

Digital periapical radiographs of 327 teeth with post-retained restoration were retrieved randomly from the Qassim University screening clinic's digital archives and evaluated. The quality of the intraradicular post and root filling was evaluated according to the optimum criteria. The presence of AP was assessed based on the periapical index scoring system. The relation between the post technical quality, the quality of root filling, and AP was determined. The data were analyzed using Chi-square test and logistic regression.

RESULTS

AP was found in 22% of the investigated teeth. Adequate root fillings were found in 69% of roots, and 14% of these cases were associated with AP. In roots with root filling classified as inadequate, 38% had AP with a statistically significant association between the root filling length and the presence of AP (P < 0.001). The most frequently used posts were prefabricated metallic posts (57%). Teeth restored with cast posts and prefabricated metallic posts exhibited AP with a frequency of 42.3% and 25.4%, respectively, and teeth with nonmetallic posts had significantly fewer cases of AP (12.0%) with a statistically significant association between the post type and the presence of AP (P = 0.016).

CONCLUSION

Both the quality of the root filling and the intraradicular post type were correlated significantly with the presence of AP. The technical quality of root fillings and intraradicular posts was adequate. Nevertheless, the use of threaded posts is still a common practice in this study population.

2016 ASE undergraduate essay competition candidate information

The aim of this review is to discuss the role of medicaments and materials used in teeth undergoing root canal treatment and how they affect the overall prognosis of root canal treated teeth. Irrigants, medicaments and materials play a vital role in RCT. They reduce the overall microbial load within the root canal system, help reduce inter-appointment pain, and induce apexification during RCT of permanent teeth with immature apices. In addition, they also help create a hermetic coronal and periradicular seal to entomb any residual microorganisms within the canals and prevent future ingress of contaminants into the root canal system and subsequent reinfection. Whilst the role of various materials in RCT has been thoroughly investigated, the available literature and longitudinal clinical studies evaluating the affect of such materials on the prognosis of RCT is scarce, and requires further investigation.

Scaffolds to control inflammation and facilitate dental pulp regeneration

In dentistry, the maintenance of a vital dental pulp is of paramount importance because teeth devitalized by root canal treatment may become more brittle and prone to structural failure over time. Advanced carious lesions can irreversibly damage the dental pulp by propagating a sustained inflammatory response throughout the tissue. Although the inflammatory response initially drives tissue repair, sustained inflammation has an enormously destructive effect on the vital pulp, eventually leading to total necrosis of the tissue and necessitating its removal. The implications of tooth devitalization have driven significant interest in the development of bioactive materials that facilitate the regeneration of damaged pulp tissues by harnessing the capacity of the dental pulp for self-repair. In considering the process by which pulpitis drives tissue destruction, it is clear that an important step in supporting the regeneration of pulpal tissues is the attenuation of inflammation. Macrophages, key mediators of the immune response, may play a critical role in the resolution of pulpitis because of their ability to switch to a proresolution phenotype. This process can be driven by the resolvins, a family of molecules derived from fatty acids that show great promise as therapeutic agents. In this review, we outline the importance of preserving the capacity of the dental pulp to self-repair through the rapid attenuation of inflammation. Potential treatment modalities, such as shifting macrophages to a proresolving phenotype with resolvins are described, and a range of materials known to support the regeneration of dental pulp are presented.

Stability of endodontically treated teeth with differently invasive restorations: Adhesive vs. non-adhesive cusp stabilization

OBJECTIVES

Aim of the present study was to evaluate fracture strength of endodontically treated molars with different preparations/restorations after thermomechanical loading in vitro.

METHODS

264 extracted human third molars were used. Beside the control group, 256 teeth in 32 test groups (n=8) received root canal treatment (MTwo #40/.6) and root canal obturation with AH Plus and Guttapercha. After postendodontic sealing and build-up (Syntac, SDR), specimens were additionally prepared MO or MOD. Postendodontic restorations were: Direct restorations (Tetric EvoCeram Bulk Fill bonded with Syntac; as filling or direct partial crown (PC) after reducing the cusps 3mm; amalgam as filling or direct pin-retained partial crown (PC)), vs. indirect adhesive restorations (I: Inlay vs. PC; IPS Empress I/PC; Celtra Duo I/PC; e.max CAD I/PC; Lava Ultimate I/PC; Enamic I/PC - all inserted with Syntac/Variolink) vs. cemented cast gold I/PC. After 300,000 thermocycles (5/55°C) and 1.2 Mio. 100N load cycles, specimens were loaded until fracture.

RESULTS

Whereas IPS Empress showed no difference between I and PC (p>0.05), in all other groups PC were significantly more stable than fillings/inlays (p<0.05), this effect was more pronounced after MOD preparations. Cast gold PC exhibited the highest fracture strengths (p<0.05), inlays the lowest (p<0.05). IPS Empress was generally inferior to the other bonded materials under investigation (p<0.05) which as PC almost reached the level of control specimens. Amalgam fillings showed the worst outcome (p<0.05).

SIGNIFICANCES

Less invasive preparation designs were not beneficial for the stability of postendodontic restorations. Except for IPS Empress, PC were generally more successful in restabilization of weakened cusps after endodontic treatment and preparation. Cast gold PC remain the ultimate stabilization tool for ETT in terms of fracture resistance.

Conservative, Surgical, and Prosthetic Treatment of a Patient with a Periapical Lesion Associated with an Atypical Intraoral Sinus Tract

This report describes a clinical case with an atypical intraoral sinus tract formation from diagnosis and treatment to short-term outcome and definitive prosthetic rehabilitation. In detail, the patient underwent conservative nonsurgical root canal treatment followed by guided bone augmentation of the regions involved in periapical inflammation and sinus tract formation. The removal of the inflammatory source of the lesion as well as the affected tissue clearly led to a healing of the surrounding bone tissues. Subsequently, the tooth was reconstructed using a fibreglass post and a metal-ceramic crown; an implant was successfully placed in the previously inflamed bone region.

Fracture resistance and microleakage of endocrowns utilizing three CAD-CAM blocks

This study assessed marginal leakage and fracture resistance of computer-aided design/computer-aided manufacturing (CAD/CAM) fabricated ceramic crowns with intracoronal extensions into the pulp chambers of endodontically treated teeth (endocrowns) using either feldspathic porcelain (CEREC Blocks [CB], Sirona Dental Systems GmbH, Bensheim, Germany), lithium disilicate (e.max [EX], Ivoclar Vivadent, Schaan, Liechtenstein), or resin nanoceramic (Lava Ultimate [LU], 3M ESPE, St Paul, MN, USA).). Thirty extracted human permanent maxillary molars were endodontically treated. Standardized preparations were done with 2-mm intracoronal extensions of the endocrowns into the pulp chamber. Teeth were divided into three groups (n=10); each group was restored with standardized CAD/CAM fabricated endocrowns using one of the three tested materials. After cementation with resin cement, specimens were stored in distilled water at 37°C for one week, subjected to thermocycling, and immersed in a 5% methylene-blue dye solution for 24 hours. A compressive load was applied at 35 degrees to long axis of the teeth using a universal testing machine until failure. Failure load was recorded, and specimens were examined under a stereomicroscope for modes of failure and microleakage. Results were analyzed using one-way analysis of variance and Bonferroni post hoc multiple comparison tests (α=0.05). LU showed significantly (p<0.05) higher fracture resistance and more favorable fracture mode (ie, fracture of the endocrown without fracture of tooth) as well as higher dye penetration than CB and EX. In conclusion, although using resin nanoceramic blocks for fabrication of endocrowns may result in better fracture resistance and a more favorable fracture mode than other investigated ceramic blocks, more microleakage may be expected with this material.

A comparative evaluation of gutta percha removal and extrusion of apical debris by rotary and hand files

AIM

The aim of this study was to evaluate the efficacy of Protaper retreatment files in comparison with RaCe, K3 and H-files for removal of gutta-percha and apically extruded debris using volumetric analysis.

MATERIALS AND METHODS

Forty extracted single rooted maxillary incisor teeth with straight canals and mature apices were selected for the study. After access cavity preparation, apical patency was confirmed with a size 10 K-file extending 1mm beyond the point at which it was first visible at the apical end. Working lengths were determined with the use of size 15 K-file. The canals were prepared in a step-back technique and the master apical file was size 30 for all teeth. 3% sodium hypochlorite was used as an irrigant after each instrumentation. Before final rinse, size 20 K-file was passed 1mm beyond the apex to remove any dentinal shaving plugs and maintain the apical patency. Then the canals were dried with paper points. The root canal was filled using standard gutta-percha points and zinc oxide eugenol sealer under lateral condensation technique. The teeth were then randomly divided into four groups of ten teeth each based on the instrument used for gutta percha removal. All the rotary instruments used in this study were rotated at 300rpm. The instruments used were: Group 1 - RaCe Files, Group 2 - ProTaper retreatment Files, Group 3 - K3 Files and Group 4 - H Files. The volume of the obturating material was calculated before and after removal using volumetric analysis with spiral CT. The removal efficacy with each instrument was calculated and statistically analysed.

RESULTS

The results of the study show that the ProTaper retreatment files (Group 2) (97.4%) showed the highest efficiency in the removal of obturating material, which was followed by RaCe (95.74%), K3 (92.86%) and H files (90.14%) with the efficiency in the decreasing order. Similarly the mean apical extrusion in H files (0.000 ± 0.002) was significantly lower than all the rotary instruments. However, the difference among the rotary files were not statistically significant (p>0.05).

CONCLUSION

ProTaper retreatment files show significant difference over other groups in removal of obturating material and can be the system of choice in endodontic retreatment procedures.

Effects of etching and adhesive applications on the bond strength between composite resin and glass-ionomer cements

Objective

This study determined the effects of various surface treatment modalities on the bond strength of composite resins to glass-ionomer cements.

Material and Methods

Conventional (Ketac^TM Molar Quick Applicap^TM) or resin-modified (Photac^TM Fil Quick Aplicap^TM) glass-ionomer cements were prepared. Two-step etch-rinse & bond adhesive (Adper^TM Single Bond 2) or single-step self-etching adhesive (Adper^TM Prompt^TM L-Pop^TM) was applied to the set cements. In the etch-rinse & bond group, the sample surfaces were pre-treated as follows: (1) no etching, (2) 15 s of etching with 35% phosphoric acid, (3) 30 s of etching, and (4) 60 s of etching. Following the placement of the composite resin (Filtek^TM Z250), the bond strength was measured in a universal testing machine and the data obtained were analyzed with the two-way analysis of variance (ANOVA) followed by the Tukey's HSD post hoc analysis (p=0.05). Then, the fractured surfaces were examined by scanning electron microscopy.

Results

The bond strength of the composite resin to the conventional glass-ionomer cement was significantly lower than that to the resin-modified glass-ionomer cement (p<0.001). No significant differences were determined between the self-etching and etch-rinse & bond adhesives at any etching time (p>0.05). However, a greater bond strength was obtained with 30 s of phosphoric acid application.

Conclusions

The resin-modified glass-ionomer cement improved the bond strength of the composite resin to the glass-ionomer cement. Both etch-rinse & bond and self-etching adhesives may be used effectively in the lamination of glass-ionomer cements. However, an etching time of at least 30 s appears to be optimal.