Unveiling the correlation between in vivo endodontic reciprocate instrumentation and crack formation.

INTRODUCTION: Dentinal microcracks have been supposedly associated with unrestorable vertical root fractures and consequently long-term treatment failure. This study aimed to investigate whether in vivo root canal instrumentation in mandibular incisors with vital pulps causes dentinal microcracks using two different irrigating solutions. METHODS: Five patients with four vital mandibular incisors indicated for extraction were included. In vivo root canal preparation was performed using Reciproc R40 (tip #40 and taper 0.06). From these, two teeth were randomly assigned for root canal instrumentation irrigated with 5.25 % sodium hypochlorite irrigation (n = 10) or 2 % chlorhexidine gel with saline solution irrigation (n = 10). In sequence, all teeth were carefully extracted, stored in saline solution until microtomography (µCT) scan. Images were reconstructed and assessed for the presence or absence of dentinal microcracks where microcracks originating from the root canal lumen would be considered. All reconstructed samples were analysed dynamically and rendered in videos through the entire extension of the teeth, evaluating the axial cuts considering each third separately from the apex to the enamel-dentinal junction. Teeth were analysed using the DataViewer software at 100 % magnification without filters by three examiners blinded to the condition allocation. RESULTS: No complete dentinal microcracks were observed after root canal instrumentation of mandibular incisors with vital pulps using Reciproc R40 regardless the irrigating solutions, 5.25 % sodium hypochlorite or 2 % chlorhexidine gel. CONCLUSIONS: In vivo root canal instrumentation of mandibular incisors with vital pulps and bone/periodontal insertion does not cause dentinal microcracks and the irrigating solutions tested did not influence this occurrence. Microcrack evaluation must be performed in vivo conditions of dental tissue moist and periodontal support to avoid dryness dentinal alterations after extraction provoking false positive results. CLINICAL RELEVANCE: Reciprocating instrumentation performed in vivo is safe and do not induce dentinal microcracks in mandibular incisors.

Apical enlargement favors endodontic irrigation ­ an in vivo study

Aim: This study evaluated the irrigation penetration during root canal instrumentation and the clinical step in which the irrigation solution can be detected in the apical region. Materials and Methods: Twenty necrotic molars were divided according to the irrigation protocol, saline solution with manual active pressure, and 2.5% sodium hypochlorite with dripping delivery. Solution penetration assessment used a radiopaque component added to each irrigant solely before a periapical radiograph. Instrumentation sequence was: #10, and #15 K-files (step 1), cervical flaring using WaveOne Small (step 2), WaveOne Small at working length (step 3), Hero-642 #35/.02 (step 4), and Hero-642 #40/.02 (step 5). The step each contrasted-irrigant reached the 2-mm-apical region was registered. Shapiro-Wilk and Fisher's exact tests were used for comparisons. Results: In step 3, both contrasted-irrigants started to be detected in the apical region, and after step 5, contrasted-irrigants penetrated in 100% of the cases, without significant difference. Conclusion: Considering distal molar roots, the apical enlargement up to an instrument #40.02 favors the irrigation to reach the 2-mm apical region.

Biocompatibility analysis in subcutaneous tissue and physico-chemical analysis of pre-mixed calcium silicate-based sealers.

OBJECTIVES: To evaluate the biocompatibility, physical and chemical properties of three pre-mixed calcium silicate-based sealers and an epoxy resin-based material were assessed. Pre-mixed sealers supposedly obtain water from the root canal moist to hydrate and set. MATERIALS AND METHODS: Polyethylene tubes were filled with the materials Bio-C Sealer Ion+, Bio-C Sealer, EndoSequence BC Sealer and AH Plus Jet, or left empty and surgically implanted in the subcutaneous tissue of Wistar rats. The animals were euthanised and the tubes and tissue were removed for histological analysis and scanning electron microscopy (SEM) coupled with energy-dispersive spectrometry (EDS). Materials' surface chemical characterisation was assessed using Raman spectroscopy and SEM/EDS. Flow, setting time (in two conditions), solubility, radiopacity and pH were also analysed. ANOVA and Bonferroni correction were performed for comparisons (P < 0.05). RESULTS: Inflammatory response observed in the tissues subsided from 7 to 30 days. Tungsten migration could be detected in the surrounding tissue following AH Plus Jet implantation. All calcium silicate-based sealers exhibited zirconium oxide (radiopacifier) and tricalcium silicate peaks before and after implantation. All materials exhibited flow values above 17 mm. An approximately tenfold difference was observed between the plaster- and metal-mould setting times of the calcium silicate cements indicating its sensitivity to moist variations and solubility above 8% was also observed for these materials. CONCLUSIONS: Pre-mixed materials exhibited variable setting time and solubility with a decreasing inflammatory response. CLINICAL RELEVANCE: The variable moist-dependant setting time with high solubility poses a concern for the clinical use of these pre-mixed sealers.

Can strontium replace calcium in bioactive materials for dental applications?

The substitution of calcium with strontium in bioactive materials has been promising but there has been some concern over the material instability and possible toxicity. The aim of this research was the synthesis and characterization of calcium and strontium substituted bioactive materials and assessment of interactions with local tissues and peripheral elemental migration in an animal model. A bioactive glass, hydroxyapatite and hydraulic calcium silicate with 50% or 100% calcium substitution with strontium were developed and the set materials were characterized immediately after setting and after 30 and 180-days in solution. Following subcutaneous implantation, the local (tissue histology, elemental migration) and systemic effects (elemental deposition after organ digestion) were assessed. The strontium-replaced silicate cements resulted in the synthesis of partially substituted phases and strontium leaching at all-time points. The strontium silicate implanted in the animal model could not be retrieved in over half of the specimens showing the high rate of material digestion. Tissue histology showed that all materials caused inflammation after 30 days of implantation however this subsided and angiogenesis occurred after 180 days. Strontium was not detected in the local tissues or the peripheral organs while all calcium containing materials caused calcium deposition in the kidneys. The tricalcium silicate caused elemental migration of calcium and silicon in the local tissues shown by the elemental mapping but no deposition of calcium was identified in the peripheral organs verified by the assessment of the digested tissues. Strontium can substitute calcium in bioactive materials without adverse local or systemic effects.

Antimicrobial Activity of Calcium Silicate-Based Dental Materials: A Literature Review.

Endodontic biomaterials have significantly improved dental treatment techniques in several aspects now that they can be used for vital pulp treatments, as temporary intracanal medication, in definitive fillings, in apical surgeries, and for regenerative procedures. Calcium silicate-based cement is a class of dental material that is used in endodontics in direct contact with the dental structures, connective tissue, and bone. Because the material interacts with biological tissues and stimulates biomineralization processes, its properties are of major importance. The main challenge in endodontic treatments is the elimination of biofilms that are present in the root canal system anatomical complexities, as it remains even after chemical-mechanical preparation and disinfection procedures. Thus, an additional challenge for these biomaterials is to exert antimicrobial activity while maintaining their biological properties in parallel. This article reviews the literature for studies considering the antimicrobial properties of calcium silicate-based dental biomaterials used in endodontic practice. Considering the reviewed studies, it can be affirmed that the reduced antimicrobial effect exhibited by calcium silicate-based endodontic materials clearly emphasizes that all clinical procedures prior to their use must be carefully performed. Future studies for the evaluation of these materials, and especially newly proposed materials, under poly-microbial biofilms associated with endodontic diseases will be necessary.

Investigation of a modified hydraulic calcium silicate-based material - Bio-C Pulpo.

This study evaluated the physicochemical, biological, and antimicrobial properties of a new hydraulic calcium silicate-based modified material, and compared it with MTA Repair HP and MTA Angelus. The materials were assessed regarding color luminosity (L), color change, radiopacity, setting time, and ISO 6876:2012 linear flow. Volumetric filling and volume change were evaluated using microcomputed-tomography (µCT). Chemical characterization after 28 days in Hank's Balanced Salt Solution (HBSS) and pH analysis were also assessed. Biological characterization of cytotoxicity and microbiological assessment were also undertaken. Shapiro-Wilk, ANOVA, Levene and post hoc analyses with Bonferroni correction were performed, adopting a 5% significance level (p <0.05). Bio-C Pulpo exhibited the highest L values after 90 days. All tested materials demonstrated color change during the analyses, and had radiopacity above 5 mm Al. MTA Repair HP set faster than Bio-C Pulpo, whereas the latter had the highest linear flow. MTA Repair HP had the highest volumetric filling in µCT analysis. Bio-C Pulpo showed the highest alkalinity during all tested periods, and the highest volumetric loss (above 9%), in comparison with MTA Repair HP and MTA Angelus. Bio-C Pulpo did not form calcium hydroxide after hydration. MTA Repair HP demonstrated the highest cytocompatibility, and Bio-C Pulpo, the highest cytotoxicity. No inhibition halos were observed for any material, and similar higher turbidity values were seen after direct contact. Composition additives used in Bio-C Pulpo modified its properties, and both the absence of calcium hydroxide deposition after hydration, and the related cytotoxicity of this material are of particular concern.

Investigation of a modified hydraulic calcium silicate-based material - Bio-C Pulpo

Abstract This study evaluated the physicochemical, biological, and antimicrobial properties of a new hydraulic calcium silicate-based modified material, and compared it with MTA Repair HP and MTA Angelus. The materials were assessed regarding color luminosity (L), color change, radiopacity, setting time, and ISO 6876:2012 linear flow. Volumetric filling and volume change were evaluated using microcomputed-tomography (µCT). Chemical characterization after 28 days in Hank's Balanced Salt Solution (HBSS) and pH analysis were also assessed. Biological characterization of cytotoxicity and microbiological assessment were also undertaken. Shapiro-Wilk, ANOVA, Levene and post hoc analyses with Bonferroni correction were performed, adopting a 5% significance level (p <0.05). Bio-C Pulpo exhibited the highest L values after 90 days. All tested materials demonstrated color change during the analyses, and had radiopacity above 5 mm Al. MTA Repair HP set faster than Bio-C Pulpo, whereas the latter had the highest linear flow. MTA Repair HP had the highest volumetric filling in µCT analysis. Bio-C Pulpo showed the highest alkalinity during all tested periods, and the highest volumetric loss (above 9%), in comparison with MTA Repair HP and MTA Angelus. Bio-C Pulpo did not form calcium hydroxide after hydration. MTA Repair HP demonstrated the highest cytocompatibility, and Bio-C Pulpo, the highest cytotoxicity. No inhibition halos were observed for any material, and similar higher turbidity values were seen after direct contact. Composition additives used in Bio-C Pulpo modified its properties, and both the absence of calcium hydroxide deposition after hydration, and the related cytotoxicity of this material are of particular concern.

Dental discoloration caused by Grey-MTAFlow cement: analysis of its physicochemical, biological and antimicrobial properties.

Tricalcium silicate-based cement are materials used in reparative and regenerative procedures in endodontics. A recently proposed formulation aimed to enhance handling during clinical use with a versatile material applicable by syringe. Although, the use of bismuth oxide as radiopacifier and grey raw powder are drawbacks considering aesthetics. Objectives Evaluate physicochemical, biological, and antimicrobial properties of Grey-MTAFlow (Ultradent) and assess whether the addition of zinc oxide (ZnO) prevents dentinal discoloration caused by bismuth oxide. Methodology Grey-MTAFlow was manipulated in 'thin' consistency for all tests. Luminosity, color change, ion migration to dentine, radiopacity, setting time, ISO 6876:2012 linear flow, volumetric lateral flow and central filling of simulated grooves scanned using micro-computed tomography (µCT), pH, calcium release, volumetric change using µCT, chemical characterisation, cytotoxicity, and antimicrobial activity were assessed. Addition of 5% ZnO to Grey-MTAFlow and a bismuth-containing experimental composition were comparatively tested. Statistical analyses used Shapiro-Wilk, T-test, ANOVA, and Kolmogorov-Smirnov (p<0.05). Results The addition of ZnO to Grey-MTAFlow prevented dentine darkening after 90 days due to bismuth migration reduction, although no statistical difference was found (p=0.863). ZnO addition significantly enhanced Grey-MTAFlow radiopacity without differences in initial setting time. Grey-MTAFlow presented an ISO linear flow of 10.9 mm and a balanced volumetric lateral flow with central filling in µCT evaluation. All compositions presented an alkaline pH after immersion. Grey-MTAFlow had a significantly higher calcium ion release after 28 days in comparison to 24 hours (p=0.011) and volumetric expansion of 0.4±1.8% after immersion. ZnO addition altered the hydrated cement matrix once calcium hydroxide (portlandite) could not be detected in characterisation. Neither of the materials produced inhibition halos nor reduced bacterial turbidity, but all presented cytocompatibility above 100%. Conclusion Grey-MTAFlow expanded after immersion and exhibited higher luminosity values after the evaluation period when ZnO was added, but chemical modifications after this addition occurred.

Apical root canal cleaning after preparation with endodontic instruments: a randomized trial in vivo analysis.

OBJECTIVES: This study aimed to evaluate vital pulp tissue removal from different endodontic instrumentation systems from root canal apical third in vivo. MATERIALS AND METHODS: Thirty mandibular molars were selected and randomly divided into 2 test groups and one control group. Inclusion criteria were a positive response to cold sensibility test, curvature angle between 10 and 20 degrees, and curvature radius lower than 10 mm. Root canals prepared with Hero 642 system (size 45/0.02) (n = 10) and Reciproc R40 (size 40/0.06) (n = 10) and control (n = 10) without instrumentation. Canals were irrigated only with saline solution during root canal preparation. The apical third was evaluated considering the touched/untouched perimeter and area to evaluate the efficacy of root canal wall debridement. Statistical analysis used t-test for comparisons. RESULTS: Untouched root canal at cross-section perimeter, the Hero 642 system showed 41.44% ± 5.62% and Reciproc R40 58.67% ± 12.39% without contact with instruments. Regarding the untouched area, Hero 642 system showed 22.78% ± 6.42% and Reciproc R40 34.35% ± 8.52%. Neither instrument achieved complete cross-sectional root canal debridement. Hero 642 system rotary taper 0.02 instruments achieved significant greater wall contact perimeter and area compared to reciprocate the Reciproc R40 taper 0.06 instrument. CONCLUSIONS: Hero 642 achieved higher wall contact perimeter and area but, regardless of instrument size and taper, vital pulp during in vivo instrumentation is not entirely removed.

Dental discoloration caused by Grey-MTAFlow cement: analysis of its physicochemical, biological and antimicrobial properties

Abstract Tricalcium silicate-based cement are materials used in reparative and regenerative procedures in endodontics. A recently proposed formulation aimed to enhance handling during clinical use with a versatile material applicable by syringe. Although, the use of bismuth oxide as radiopacifier and grey raw powder are drawbacks considering aesthetics. Objectives Evaluate physicochemical, biological, and antimicrobial properties of Grey-MTAFlow (Ultradent) and assess whether the addition of zinc oxide (ZnO) prevents dentinal discoloration caused by bismuth oxide. Methodology Grey-MTAFlow was manipulated in 'thin' consistency for all tests. Luminosity, color change, ion migration to dentine, radiopacity, setting time, ISO 6876:2012 linear flow, volumetric lateral flow and central filling of simulated grooves scanned using micro-computed tomography (μCT), pH, calcium release, volumetric change using μCT, chemical characterisation, cytotoxicity, and antimicrobial activity were assessed. Addition of 5% ZnO to Grey-MTAFlow and a bismuth-containing experimental composition were comparatively tested. Statistical analyses used Shapiro-Wilk, T-test, ANOVA, and Kolmogorov-Smirnov (p<0.05). Results The addition of ZnO to Grey-MTAFlow prevented dentine darkening after 90 days due to bismuth migration reduction, although no statistical difference was found (p=0.863). ZnO addition significantly enhanced Grey-MTAFlow radiopacity without differences in initial setting time. Grey-MTAFlow presented an ISO linear flow of 10.9 mm and a balanced volumetric lateral flow with central filling in μCT evaluation. All compositions presented an alkaline pH after immersion. Grey-MTAFlow had a significantly higher calcium ion release after 28 days in comparison to 24 hours (p=0.011) and volumetric expansion of 0.4±1.8% after immersion. ZnO addition altered the hydrated cement matrix once calcium hydroxide (portlandite) could not be detected in characterisation. Neither of the materials produced inhibition halos nor reduced bacterial turbidity, but all presented cytocompatibility above 100%. Conclusion Grey-MTAFlow expanded after immersion and exhibited higher luminosity values after the evaluation period when ZnO was added, but chemical modifications after this addition occurred.

Relación entre el piso del seno maxilar y las raíces de las piezas posteriores superiores, mediante tomografía computada / Relationship between maxillary sinus floor and the posterior upper teeth roots, by means of computed tomography

Objetivo: El objetivo de este estudio fue evaluar la frecuencia con que las raíces de premolares y molares superiores se encuentran dentro del seno maxilar. Conocer la relación entre dichas estructuras es importante para planificar los procedimientos endodónticos y quirúrgicos a ser realizados en esa región. Materiales y métodos: Se realizó el análisis cualitativo dinámico de 82 tomografías computadas de haz cónico (CBCT) unilaterales, analizándose 738 raíces correspondientes a premolares y molares de una sola hemiarcada superior. Se utilizó sala con iluminación controlada y la observación fue realizada por un solo examinador. El criterio de inclusión requería que la cortical inferior del seno maxilar debía ser visible para poder establecer la relación. Se utilizaron los tres planos tomográficos de visualización, permitiendo ajustes de brillo y contraste. La escala de clasificación de cada raíz consideró su relación como: dentro o fuera del seno maxilar. Los datos obtenidos fueron sometidos a las pruebas de Chi-cuadrado y Test Exacto de Fisher. Resultados: el primer premolar superior mostró una proyección hacia el interior del seno maxilar significativamente menor que las otras piezas dentarias posteriores (p>0.05), observándose su raíz vestibular sin proyección. La raíz palatina del primer premolar superior mostró la mayor incidencia dentro del seno maxilar, con un 39,02% del total de las raíces analizadas (p<0,05). El segundo molar superior mostró considerable proximidad con el seno maxilar, pero con menor incidencia con relación a la raíz palatina del primer molar. Conclusión: los procedimientos endodónticos o quirúrgicos a realizarse en cercanía al seno maxilar deben considerar siempre la relación raíz/seno, para evitar maniobras que lo invadan. La raíz palatina del primer molar superior mostró la mayor incidencia dentro del seno maxilar, con un 39,02% (AU)