Release Kinetics of Monomers from Dental Composites Containing Fluoride-Doped Calcium Phosphates.

This study analyse the type of release kinetic of specific monomers from dental resin composites containing various fluoride-doped calcium phosphates. The release behavior of urethane dimethacrylate (UDMA), ethoxylated bisphenol-A dimethacrylate (bis-EMA) and 1.6-hexanediol ethoxylate diacrylate (HEDA) was evaluated over a period of 35 days. Two tailored calcium phosphates doped with different concentrations of fluoride salts (VS10% and VS20%) were prepared and incorporated in the dimethacrylate matrix at various concentrations to generate a range of experimental composites. The release kinetics were characterized using mathematical models such as zero-order, first-order, Peppas and Higuchi models. The results showed that the first-order model best described the release kinetics. UDMA and HEDA exhibited significant differences in release compared to bis-EMA from day 1, while no significant differences were observed between UDMA and HEDA, except on day 35, when UDMA exhibited a higher release rate than HEDA. When comparing the release of each monomer, VS20-R20% had the highest total release percentage, with 3.10 ± 0.25%, whereas the composite VS10-R5% showed the lowest release percentage, with a total of 1.66 ± 0.08%. The release kinetics were influenced by the composition of the resin composites and the presence of calcium fluoride and sodium fluoride in the calcium phosphate played a role in the maximum amounts of monomer released. In conclusion, the release of monomers from the tested resin composites followed a first-order kinetic behaviour, with an initial rapid release that decreased over time. The composition of the resin monomers and the presence of fluoride salts influenced the release kinetics. The VS10-R5% and VS10-R10% resin composites exhibited the lowest total monomer release, suggesting its potential favourable composition with reduced monomer elution. These findings contribute to understanding the release behavior of dental resin composites and provide insights for the development of resin-based bioactive dental materials.

Complicated Crown Fracture of Permanent Incisors: A Conservative Treatment Case Report and a Narrative Review.

Dental trauma may have a severe impact on the social and psychological wellbeing of a patient. Most cases of dental injuries involve anterior teeth, especially the maxillary upper incisors. Crown fractures, with or without pulp exposure, are the most common trauma in permanent dentition. There are many methods of management, in which the initial state of the pulp, the time since the injury, and the presence of an accompanying injury play a key role. This case report aimed at showing a possible conservative treatment after complicated tooth fracture that consisted of partial pulpotomy followed by adhesive reattachment of the tooth fragment using a technique based on heated resin composite. Such a specific procedure represents a conservative approach to traumatic coronal lesions, providing a suitable opportunity to maintain the tooth vitality, aesthetics, and function. Indeed, reattachment of tooth fragment using a composite/adhesive is a simple technique to achieve excellent results in terms of aesthetic and function.

In Vitro Evaluation of Antibacterial Properties and Smear Layer Removal/Sealer Penetration of a Novel Silver-Citrate Root Canal Irrigant.

This study aimed at evaluating the efficacy of a novel silver-citrate root canal irrigation solution (BioAKT) on smear layer removal, sealer penetration after root canal instrumentation and antibacterial activity. Single-root teeth were endodontically treated, sealed with an epoxi-amine resin sealer and irrigated using: Group I: 5.25% sodium hypochlorite (NaOCl); Group II: silver-citrate solution (BioAKT); Group III: phosphate buffer solution (PBS); Group IV: 17% ethylenediaminetetraacetic acid (EDTA). Smear layer removal and silver deposition at the coronal, middle and apical portion of each canal were analyzed using scanning electron microscopy (SEM) and energy-dispersive x-ray spectroscopy (EDS). Sealer penetration into dentinal tubules at coronal, middle and apical portion was assessed through dye-assisted confocal microscopy (CSM). Both SEM and CSM micrographs were evaluated by two examiners (κ = 0.86), who were blind to the irrigation regimens; scores were given according to the degree of penetration of the sealer. Data analysis included Pearson's x2 and Sidak's multiple comparisons. Dentin discs were polished and sterilized. Enterococcus faecalis biofilms were grown using a continuous-flow bioreactor under anaerobic conditions for 72 h. Specimens were irrigated with the tested solutions, and bacterial viability was assessed using a tetrazolium salt assay (MTT). Statistical analysis included one-way ANOVA and Student's post-hoc t-test (p < 0.05). BioAKT and EDTA were the most efficient solutions both in removing the smear layer and allowing sealer penetration. However, at the apical portion BioAKT performed significantly better compared to EDTA both in smear layer removal and sealer penetration (p < 0.05). BioAKT and NaOCl showed comparable antibacterial effect (p = 0.53). In conclusion, BioAKT represents a suitable smear layer removal agent, which allows for reliable sealer penetration at the apical portion of the root canal system and offers significant antibacterial properties.

Efectividad de dos anestésicos tópicos para la colocación de la grapa. Estudio clínico aleatorizado

Objetivos: Valorar la eficacia de la mezcla eutéctica de lidocaína y prilocaína al 4% comparándola con el gel de benzocaína al 20% en el control del dolor generado por la colocación de una grapa para el aislamiento absoluto previo a la realización de un sellante de fisuras y valorar el efecto psicológico placebo del uso del anestésico tópico. Material y métodos: Se llevó a cabo un estudio clínico aleatorizado. La muestra estuvo constituida por 96 primeros molares permanentes con fosas y fisuras profundas y retentivas, pertenecientes a 24 pacientes. Los molares fueron distribuidos aleatoriamente en 3 grupos de estudio, benzocaína 20%, lidocaína y prilocaína al 4%, vaselina y un grupo control. Antes y después de la colocación de la grapa se registró la escala de dolor de caras-revisada y la frecuencia cardíaca. Resultados: La mezcla eutéctica de lidocaína y prilocaína al 4% obtuvo valores significativamente más bajos en la escala de dolor de caras-revisada, seguida de la benzocaína al 20% y la vaselina (p<0,05). La mezcla eutéctica de lidocaína y prilocaína al 4% presentó menor modificación de la frecuencia cardíaca (p<0,05) en relación con los otros grupos, entre los que no se encontró diferencias estadísticamente significativas. Conclusiones: La mezcla eutéctica de lidocaína y prilocaína al 4% demostró mayor efectividad que el gel de benzocaína al 20% en la prevención del dolor generado por la colocación de una grapa. Del mismo modo se confirmó el efecto psicológico placebo de la anestésica tópica.

The effect of dentine pre-treatment using bioglass and/or polyacrylic acid on the interfacial characteristics of resin-modified glass ionomer cements.

OBJECTIVE: To evaluate the effect of load-cycle aging and/or 6 months artificial saliva (AS) storage on bond durability and interfacial ultramorphology of resin-modified glass ionomer cement (RMGIC) applied onto dentine air-abraded using Bioglass 45S5 (BAG) with/without polyacrylic acid (PAA) conditioning. METHODS: RMGIC (Ionolux, VOCO) was applied onto human dentine specimens prepared with silicon-carbide abrasive paper or air-abraded with BAG with or without the use of PAA conditioning. Half of bonded-teeth were submitted to load cycling (150,000 cycles) and half immersed in deionised water for 24 h. They were cut into matchsticks and submitted immediately to microtensile bond strength (µTBS) testing or 6 months in AS immersion and subsequently µTBS tested. Results were analysed statistically by two-way ANOVA and Student-Newman-Keuls test (α = 0.05). Fractographic analysis was performed using FE-SEM, while further RMGIC-bonded specimens were surveyed for interfacial ultramorphology characterisation (dye-assisted nanoleakage) using confocal microscopy. RESULTS: RMGIC applied onto dentine air-abraded with BAG regardless PAA showed no significant µTBS reduction after 6 months of AS storage and/or load cycling (p > 0.05). RMGIC-dentine interface showed no sign of degradation/nanoleakage after both aging regimens. Conversely, interfaces created in PAA-conditioned SiC-abraded specimens showed significant reduction in µTBS (p < 0.05) after 6 months of storage and/or load cycling with evident porosities within bonding interface. CONCLUSIONS: Dentine pre-treatment using BAG air-abrasion might be a suitable strategy to enhance the bonding performance and durability of RMGIC applied to dentine. The use of PAA conditioner in smear layer-covered dentine may increase the risk of degradation at the bonding interface. CLINICAL SIGNIFICANCE: A combined dentine pre-treatment using bioglass followed by PAA may increase the bond strength and maintain it stable over time. Conversely, the use of PAA conditioning alone may offer no significant contribute to the immediate and prolonged bonding performance.

Cemental tear: To know what we have neglected in dental practice.

Cemental tear is a special kind of root surface fracture, contributing to periodontal and periapical breakdown. However, it is a challenge for doctors to diagnose, resulting in delayed or improper treatment. We reviewed the predisposing factors, location, radiographic/clinical characteristics, diagnosis and treatments of cemental tears. From the literature, patients with cemental tear were mainly males, over 60 year-old. Possible predisposing factors include gender, age, tooth type, traumatic occlusal force and vital teeth. Cemental tears were common in upper and lower anterior teeth, single or multiple, and can be present in cervical, middle and apical third of roots. Morphology of cemental tears can be either piece-shaped or U-shaped. Clinically, cemental tear shows a unitary periodontal pocket and signs/symptoms mimicking localized periodontitis, apical periodontitis and vertical root fractures. Treatment of cemental tears include scaling, root planning, root canal treatment, periodontal/periapical surgery, guided tissue regeneration, bone grafting, and intentional replantation. Recurrence of cemental tear is possible especially when the fracture involves root apex. Extraction is recommended for teeth with poor prognosis. In conclusion, cemental tears can involve both periodontal and periapical area. Dentists should understand the predisposing factors and clinical features of cemental tears for early diagnosis/treatment to prevent bone loss/tooth extraction.

Innovative root-end filling materials based on calcium-silicates and calcium-phosphates.

This in vitro study evaluated the apical sealing ability, bioactivity and biocompatibility of an experimental calcium silicate-based and two light-curing calcium silicate/calcium-phosphate cements as potential root end filling materials. A calcium silicate Portland-based (Control PC), an experimental calcium silicate (Exp. PC) and two light-curing cements (LC-CaP; LC-Si/CaP) were assessed for their alkalinising activity (pH) and biocompatibility. Single-rooted human canines were endodontically treated, filled with gutta-percha and finally submitted to apicoectomy. Root end fillings were performed using all tested cements, and their apical sealing ability was evaluated up to 4 weeks of immersion in simulated body fluid (SBF). The mineral precipitation at the apical region and the cement adaptation to root dentine were also evaluated through non-destructive optical microscopy both at 24 h and after prolonged water storage (four week). LC-CaP and LC-Si/CaP had neutral pH, the greatest sealing ability (24 h) and excellent cytocompatibility. The Exp. PC cement presented sealing ability after two and four weeks, as well as biocompatibility after four and seven days, similar to LC-CaP and LC-Si/CaP. The control PC cement showed the lowest sealing ability and the greatest cytotoxicity. Mineral precipitation was observed in all groups, while some differences were seen in terms of cement adaptation along the root canal dentine walls. The experimental light-curable cements as well as the experimental PC might be suitable root end filling materials with appropriate (in vitro) sealing ability, biocompatibility and aptitude to induce mineral precipitation.

Dicalcium phosphate (CaHPO4·2H2O) precipitation through ortho- or meta-phosphoric acid-etching: effects on the durability and nanoleakage/ultra-morphology of resin-dentine interfaces.

OBJECTIVES: To compare the effects of two etching procedures using meta-phosphoric (MPA) or ortho-phosphoric acid (OPA) on dentine demineralisation, resin-dentine bonds durability and interface nanoleakage/ultra-morphology. METHODS: Middle-dentine specimens were etched using 37% OPA (15s) or 40% MPA (60s) and submitted to infrared spectroscopy (FTIR) or ultra-morphology dye-assisted (calcium-staining) confocal microscopy (Ca-CLSM). A three-step etch-and-rinse adhesive was formulated, applied onto dentine and light-cured for 30s before composite build-up. After 24h, the dentine-bonded specimens were cut into 1mm(2) beams; half were immediately submitted to microtensile bond strength (µTBS) and half stored in DW for six months. The µTBS results were analysed with repeated-measures ANOVA and Tukey's test (p<0.05). Further teeth were bonded and prepared for interface nanoleakage/ultra-morphology confocal evaluation. RESULTS: FTIR and Ca-CLSM analyses showed dicalcium phosphate dihydrate (Brushite) precipitation in MPA-etched dentine and on the bottom (front of demineralisation) of the OPA-etched dentine. Statistical analysis showed similar µTBS for both etching procedures after 24h. The µTBS of specimens in OPA-group dropped significantly (p<0.05) after six month; the specimens in the MPA group showed no statistically difference (p>0.05). CLSM depicted no evident sign of nanoleakage within the resin-dentine interface of the MPA-treated specimens, while the specimens in OPA-group presented intense nanoleakage and interface degradation. CONCLUSION: The use of MPA (60s) as an alternative dentine conditioning agent in etch-and-rinse bonding procedures may be a suitable strategy to create more durable resin-dentine bonds.

Microestructure alterations of rotary files aftermultiple simulated operative procedures

Aim: To assess morphological alterations of ProTaper rotary NiTi files before and after continuous use by scanning electron microscopy (SEM). Study Design: 30 root canals were chosen with an angle between 15 and 30º. Before starting to prepare the canals the files were observed microscopically using a scanning electronic microscope. The ProTaper sequence recommended by the manufacturer was used, with NaOCl as irrigant. The instruments were sterilised after every three canals were shaped. The instruments were observed with the same microscope after shaping each canal, until 30 root canals were shaped. The criteria used for checking the instruments were: blunt cutting edges, disruption of cutting edge, microfractures, fatigue cracks, metal flash, dentine remains.Results: Many microscopic defects were found such as: cutting edge breaks (up to 70%); fatigue cracks, between 33 and 100%. No microfractures were found. An S1 and an SX file were fractured. Conclusion: ProTaper instruments are quite reliable if used following usual requirements (AU)

Microstructure alterations of rotary files after multiple simulated operative procedures.

AIM: to assess morphological alterations of ProTaper rotary NiTi files before and after continuous use by scanning electron microscopy (SEM). STUDY DESIGN: 30 root canals were chosen with an angle between 15 and 30 degrees . Before starting to prepare the canals the files were observed microscopically using a scanning electronic microscope. The ProTaper sequence recommended by the manufacturer was used, with NaOCl as irrigant. The instruments were sterilised after every three canals were shaped. The instruments were observed with the same microscope after shaping each canal, until 30 root canals were shaped. The criteria used for checking the instruments were: blunt cutting edges, disruption of cutting edge, microfractures, fatigue cracks, metal flash, dentine remains. RESULTS: Many microscopic defects were found such as: cutting edge breaks (up to 70%); fatigue cracks, between 33 and 100%. No microfractures were found. An S1 and an SX file were fractured. CONCLUSION: ProTaper instruments are quite reliable if used following usual requirements.

Third canal in the mesial root of permanent mandibular first molars: review of the literature and presentation of 3 clinical reports and 2 in vitro studies.

INTRODUCTION: Systematic anatomical studies corroborate the anatomical complexity of the root canal system. Deviations from the norm such as multiple orifices, apical deltas, accessory canals and other variations are frequent. OBJECTIVES: To present clinical reports of mandibular molars with three canals in the mesial root and two in vitro studies of the morphology of these canals, together with a review of the literature. MATERIALS AND METHODS: Three clinical reports are presented of mandibular molars where three canals in the mesial roots were treated endodontically. Two in vitro studies were performed, one using computerized tomography and the other with scanning electron microscopy, to describe the morphology of the mesial root canals of permanent first molars. The scientific literature on this anatomical situation was also reviewed. RESULTS: The tomographic study found that the prevalence of a third mesial canal in the 27 teeth analysed was 14.81%; the microscopic study of 25 teeth found it to be 12%. The review of the literature encountered that the authors who report cases such as these found prevalences ranging from 1% to 15%. CONCLUSIONS: From the teeth analysed in vitro, it is concluded that a third mesial canal may be present in a mandibular first molar in approximately 13% of cases. Clinically, the third canal is difficult to find and exhibits a very variable morphology, which may present anastomosis with the other canals.

Third canal in the mesial root of permanent mandibular first molars: review of the literature and presentation of 3 clinical reports and 2 in vitro studiesp

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Introduction. Systematic anatomical studies corroborate the anatomical complexity of the root canal system. Deviations from the norm such as multiple orifices, apical deltas, accessory canals and other variations are frequent.Objectives. To present clinical reports of mandibular molars with three canals in the mesial root and two in vitro studies of the morphology of these canals, together with a review of the literature.Materials and Methods. Three clinical reports are presented of mandibular molars where three canals in the mesial roots were treated endodontically. Two in vitro studies were performed, one using computerized tomography and the other with scanning electron microscopy, to describe the morphology of the mesial root canals of permanent first molars. Thescientific literature on this anatomical situation was also reviewed.Results. The tomographic study found that the prevalence of a third mesial canal in the 27 teeth analysed was 14.81%; the microscopic study of 25 teeth found it to be 12%. The review of the literature encountered that the authors who report cases such as these found prevalences ranging from 1% to 15%.Conclusions. From the teeth analysed in vitro, it is concluded that a third mesial canal may be present in a mandibular first molar in approximately 13% of cases. Clinically, the third canal is difficult to find and exhibits a very variable morphology, which may present anastomosis with the other canals