Fracture resistance of simulated immature roots using Biodentine and fiber post compared with different canal-filling materials under aging conditions

Objective

The aim of this study was to evaluate the fracture resistance of simulated immature roots using Biodentine (BD) and fiber post (FP) compared with different root canal-filling materials under aging conditions.

Materials and methods

One hundred and forty maxillary central anterior teeth were randomly divided into seven groups (n = 20/group). Negative control received no treatment. In the other groups, the root canals were prepared to simulate immature teeth. The root canals were filled with a 4-mm apical plug of BD and restored intraradicular with BD, BD + FP, composite resin (CR), CR + FP, and gutta-percha (GP). Positive controls were instrumented but without restoration. Teeth were subjected to thermocycling and received cyclic loading before fracture resistance test. Fracture resistance was conducted using a universal testing machine with a crosshead speed of 0.5 mm/min until fracture. Load to fracture was recorded in newtons (N). Data were statistically analyzed using one-way analysis of variance and Tukey’s test at P < 0.05.

Results

Root canals restored intraradicular with BD + FP and CR + FP showed the highest fracture resistance compared with the other experimental groups (P < 0.001). There was no significant difference in the fracture resistance between CR and BD groups (P = 0.998). GP and positive control groups were significantly lower resistance to fracture than the other groups (P < 0.001).

Conclusions

Intraradicular reinforcement with BD + FP and CR + FP enhanced the fracture resistance of simulated immature teeth than the other experimental groups.

Clinical relevance

Biodentine or composite resin combined with fiber post could be used to reinforce immature teeth with an apical Biodentine plug.

     

Coronal discoloration induced by calcium silicate-based cements used in full pulpotomy in mature permanent molars: a randomized clinical trial

Objectives

This study aimed to randomly compare in vivo coronal discoloration at 6 and 12 months after full pulpotomy in mature permanent molars using MTA, Biodentine, and TotalFill and to investigate the effect of variables such as remaining buccal wall thickness and time to achieve hemostasis.

Materials and methods

One hundred eight teeth that met the inclusion criteria received full pulpotomy and were randomly divided into 3 groups via a block randomization technique according to the calcium silicate cement (CSC): ProRoot WMTA, TotalFill, or Biodentine. Assessment of tooth color was carried out using a spectrophotometric device (VITA Easyshade Compact) after composite placement (T0), at 6- and 12-month follow-up. Buccal wall thickness and time to hemostasis were recorded. The primary outcome measure (color change ΔE) was calculated, and the results were analyzed by three-way ANOVA and crosstabulations in relation to material type and effect of variables.

Results

Four cases were excluded after pulpotomy failure; 81 teeth were evaluated at 6 months and 95 teeth at 12 months. All CSCs caused tooth discoloration (defined as ΔE > 3.7); MTA significantly caused the highest color change at 6- and 12-month follow-up (76% (19/25) and 87.5% (28/32), respectively) compared to Biodentine (41% (9/22), 48% (13/27)) and TotalFill (44% (15/34), 53% (19/53)) (p = 0.022, p = 0.002), while no significant difference was found between the Biodentine and TotalFill groups (p = 0.813, p = 0.8). Buccal wall thickness (above or below 2.7 mm) had a significant effect on the degree of discoloration (p = 0.004).

Conclusions

The 3 CSCs caused tooth discoloration based on the threshold of ΔE > 3; the remaining buccal wall thickness was a significant factor. The use of Biodentine and TotalFill instead of MTA is encouraged to minimize discoloration.

Clinical relevance

While experimental studies report coronal discoloration after CSCs use, clinical data is lacking. This study assessed discoloration using a spectrophotometric device. The use of materials with lower discoloration potential in pulpotomy is encouraged.

Trial registration

The study was registered with clinical trial registration number: NCT04346849 on 14.4.2020.

     

Resistance to fracture of simulated external cervical resorption cavities repaired with different materials

The aim of the study was to evaluate the fracture resistance (FR) of teeth with simulated external cervical resorption (ECR) cavities repaired with different materials. Following the shaping of the 80 human permanent maxillary central incisors, standard ECR cavities were prepared and restored with a nanohybrid composite resin; a high viscosity GIC Equia Forte Fill; Biodentine; Biodentine + nanohybrid composite resin; MTA BIOREP; MTA BIOREP + nanohybrid composite resin. Then, the root canals were obturated with AH Plus and gutta-percha. The roots were embedded acrylic resin blocks and fracture strength test was applied. The highest FR was observed in the Biodentine group, while the lowest was in Equia group (p < 0.05). No significant results were observed among composite, Biodentine + composite, MTA BIOREP + composite and MTA BIOREP (p > 0.05). Biodentine may be a preferable material for repairing ECR cavities. Adding a composite layer on MTA BIOREP and Biodentine did not improve the FR of these materials.     

Effectiveness of adjunctive hyaluronic acid application in coronally advanced flap in Miller class I single gingival recession sites: a randomized controlled clinical trial

Objectives

The aim of this randomized controlled clinical trial was to evaluate the possible advantages of adjunctive hyaluronic acid (HA) application in the coronally advanced flap (CAF) procedure in single Miller class I/recession type 1 (RT1) gingival recession treatment.

Material and methods

Thirty patients with one recession were enrolled; 15 were randomly assigned CAF + HA and 15 to CAF alone. The recession reduction (RecRed), clinical attachment level gain (CAL-gain), changes in probing pocket depth (PPD) and in the width of keratinized tissue (KT), complete root coverage (CRC), and mean root coverage (MRC) were calculated after 18 months. Post-operative morbidity (pain intensity, discomfort, and swelling) was recorded 7 days after treatment using visual analogue scale (VAS).

Results

After 18 months, RecRed was statistically significantly higher in the test group (2.7 mm [1.0]) than in the control group (1.9 mm [1.0]; p = 0.007). PPD were found to be slightly but statistically significantly increased in both groups. No statistically significant difference was found for KT gain between treatments. CRC was 80% for test and 33.3% for control sites (p < 0.05). A MRC of 93.8 ± 13.0% for test and 73.1 ± 20.8% for control sites was calculated (p < 0.05). The test group reported lower swelling and discomfort values 7-days post-surgery (p < 0.05). Statistically significant difference was not found for pain intensity.

Conclusions

The adjunctive use of HA was effective in obtaining CRC for single Miller class I/RT1 gingival recession sites.

Clinical relevance

Adjunctive application of HA in the coronally advanced flap procedure may improve the reduction of the recessions and increase the probability of CRC in Miller class I recessions.

     

Clinical performance of a glass ionomer restorative system: a 6-year evaluation

Objectives

The aim of this study is to evaluate the long-term clinical performance of a glass ionomer (GI) restorative system in the restoration of posterior teeth compared with a micro-filled hybrid posterior composite.

Materials and methods

A total of 140 (80 Cl1 and 60 Cl2) lesions in 59 patients were restored with a GI system (Equia) or a micro hybrid composite (Gradia Direct). Restorations were evaluated at baseline and yearly during 6 years according to the modified-USPHS criteria. Negative replicas at each recall were observed under SEM to evaluate surface characteristics. Data were analyzed with Cohcran’s Q and McNemar’s tests (p < 0.05).

Results

One hundred fifteen (70 Cl1 and 45 Cl2) restorations were evaluated in 47 patients with a recall rate of 79.6% at 6 years. Significant differences were found in marginal adaptation and marginal discoloration for both restorative materials for Cl1 and Cl2 restorations (p < 0.05). However, none of the materials were superior to the other (p > 0.05). A significant decrease in color match was observed in Equia restorations (p < 0.05). Only one Cl2 Equia restoration was missing at 3 years and another one at 4 years. No failures were observed at 5 and 6 years. Both materials exhibited clinically successful performance after 6 years. SEM evaluations were in accordance with the clinical findings.

Conclusions

Both materials showed a good clinical performance for the restoration of posterior teeth during the 6-year evaluation.

Clinical relevance

The clinical effectiveness of Equia and Gradia Direct Posterior was acceptable in Cl1 and Cl2 cavities subsequent to 6-year evaluation.

     

Clinical evaluation of direct pulp capping using a calcium silicate cement—treatment outcomes over an average period of 2.3 years

Objectives

This study aims to assess the treatment outcomes of direct pulp capping with a calcium silicate cement (Biodentine) after caries excavation.

Materials and methods

A total of 245 teeth of 226 patients diagnosed to be clinical healthy or showing spontaneous pain were directly capped. The teeth were examined 0.19 to 7.4 (mean 2.3 ± 2.04) years after treatment. The following data were recorded: age and sex of the patient, type of tooth and restoration (glass ionomer cement [GIC], amalgam, composite resin, ceramic, gold) and symptoms before or after treatment. The evaluation of the treatment was carried out by sensibility and percussion testing and by the patient’s questioning. A positive sensibility test, a negative percussion test, the absence of swelling and discomfort were considered as treatment success. Survival analysis was performed using the Kaplan-Meier, log-rank, Chi-square and Fisher’s exact test, respectively.

Results

After an average period of 2.3 years, 86.0% of the teeth remained vital; the survival rate after 7.4 years was 83.4%. The treatment outcome was significantly worse for cavities restored with GIC compared to all other restorative materials (p < 0.05). All other evaluated factors had no significant influence on the success rate (p > 0.05).

Conclusion

Exposed pulps of asymptomatic vital permanent teeth and teeth with spontaneous pain before treatment can be successfully capped directly using Biodentine. A subsequent restoration with GIC does not appear to be suitable as it significantly reduces the success of the treatment.

Clinical relevance

Direct pulp capping can be done successfully with this type of calcium silicate cement.

     

Evaluation of the protective effects of non-thermal atmospheric plasma on alveolar bone loss in experimental periodontitis

Objectives

The inhibition of bone destruction is one of the main goals of periodontitis treatment. The aim of this study was to investigate the protective effects of non-thermal atmospheric plasma (NTAP) on alveolar bone loss radiographically, histomorphometrically, and histologically in experimental periodontitis in rats.

Materials and methods

A total of twenty-eight rats were randomly divided into three groups: control group (CG) (n = 8), periodontitis group (PG) (n = 10), and NTAP group (NTAPG) (n = 10). In PG and NTAPG, experimental periodontitis was created with ligating. The kINPen 11 plasma jet was applied around the ligatured teeth in NTAPG. The samples from each group were radiographically assessed with microcomputed tomography (micro-CT); then, histological (presence of osteoclasts and inflammatory cells) and immunohistochemical (immunoreactive of OCN and ALP) findings were compared.

Results

The results revealed a significant increase in alveolar bone loss in the PG compared with CG and NTAPG (p < 0.05). Inflammation, alveolar resorption, and cement damage were reduced significantly in the group treated with NTAP compared to the PG (p < 0.05). Significantly higher levels of osteoclasts were detected in the PG in comparison with both CG and NTAPG (p < 0.05). The lowest osteocalcin and ALP values were determined in PG, and the differences between PG and both groups were also significant (p < 0.05).

Conclusion

Within the limitations of the present study, we can say that NTAP may enhance the bone remodeling process by inhibiting inflammation and preventing alveolar bone destruction.

Clinical relevance

NTAP has clinical potential for accelerating and treating periodontitis with the inflammatory response modulation, osteoblast differentiation, and alveolar bone loss reduction.

     

Comparison between flapless-guided and conventional surgery for implant placement: a 12-month randomized clinical trial

Objectives

The study was aimed at comparing implants installed with guided and conventional surgery.

Material and methods

Twenty-nine total edentulous patients were selected, and maxillary contralateral quadrants were randomly assigned to static computer-aided implant surgery (S-CAIS): flapless computer-guided surgery, and conventional surgery (CS): flap surgery with conventional planning. Tomography scans were performed at baseline and 10 days after the surgery for deviation measurement, and radiography was done at baseline and after 6 and 12 months, for peri-implant bone level (PIBL) analysis. Peri-implant fluid and subgingival biofilm were collected to evaluate bone markers and periodontal pathogens.

Results

S-CAIS showed less linear deviation at the apical point and the midpoint and less angular deviation (p < 0.05), with greater depth discrepancy in the positioning of the platform (p < 0.05). Higher values of vertical PIBL were observed for the S-CAIS group at baseline (p < 0.05), while lower values of horizontal PIBL were observed for CS (p < 0.05). Bone markers and Tf presented higher levels in CS (p < 0.05). Flapless S-CAIS allowed smaller linear and angular deviations than the conventional technique.

Conclusion

However, PIBL was higher in S-CAIS; the conventional technique led to a greater angiogenic and bone remodeling activity by elevating the angiogenic levels and bone markers.

Clinical relevance

Evaluating the different implant insertion techniques can guide clinical and surgical regarding the accuracy, the release pattern of bone markers, and the peri-implant bone level.

Trial registration

ReBEC-RBR-8556fzp.

     

The effect of an oral care protocol and honey mouthwash on mucositis in acute myeloid leukemia patients undergoing chemotherapy: a single-blind clinical trial

Objectives

The purpose of the study is to evaluate and compare the effectiveness of honey mouthwash and an oral care protocol on mucositis and weight loss in patients with acute myeloid leukemia receiving chemotherapy.

Materials and methods

In this single-blind clinical trial, 53 acute myeloid leukemia (AML) patients receiving chemotherapy were randomly assigned into three groups: honey mouthwash (n = 17), oral care (n = 17), and control (n = 19). The severity of mucositis and weights was examined blindly at the baseline and 4-week follow-up.

Results

The prevalence of grades of mucositis in the study groups was significant at the end of the third (p = 0.002) and fourth (p < 0.001) weeks. The mucositis severity decreased at the end of the third and fourth weeks in the honey mouthwash group (p < 0.05), whereas it increased in the control group (p < 0.001). The difference in the weight was significant between the honey mouthwash and the control groups (p < 0.05, MD = 1.95) at the end of the third week, and between the honey mouthwash group with the control (p < 0.01, MD = 2.92) and oral care groups (p < 0.05, MD = 1.95) at the end of the fourth week.

Conclusions

Honey mouthwash is effective in preventing and reducing the severity of mucositis, and weight loss and can be recommended for patients undergoing chemotherapy.

Clinical relevance

The results of this study suggest that honey mouthwash can reduce the incidence and severity of mucositis in patients, reduce or eliminate the possibility of weight loss in them, as well as encourage some weight gain. Compared to routine oral care, honey mouthwash is also easier to use and handle.

Trial registration

IRCT2015121419919N7

     

Fracture resistance of endodontically treated mandibular first molars with conservative access cavity and different restorative techniques: An in vitro study

The aim was to investigate in vitro the fracture resistance (FR) of endodontically treated teeth (ETT) with conservative access cavity restored using various direct and indirect restorative materials and techniques. Seventy‐two mandibular first molars were equally divided into six groups. Teeth in Group 1 were untreated (controls). In Groups 2, 3, 4, 5 and 6, teeth were restored with amalgam, composite resin, ceramic inlay, ceramic onlay and zirconium crown, respectively. A fracture test was performed on all teeth using a static load. Compared with other groups, teeth in Groups 3 (P < 0.05) and 6 (P < 0.05) had the highest FR values with no significant difference in‐between them. Teeth in Group 4 had the lowest FR than other groups (P < 0.05). All restorative techniques tested led to a significant reduction in FR. It is necessary to consider type of fracture when evaluating fracture resistance of endodontically treated teeth. Crowned molars had the highest favourable fractures among the five treatment groups. Although the results of this in vitro study showed variations between tested techniques in ETT with a conservative access cavity, further long‐term controlled clinical trials are required to confirm these in vitro findings.     

Morphological measurements of two separate mesiobuccal canals in maxillary first molars using micro-computed tomography

Objectives

To obtain radicular measurements of two separate mesiobuccal (MB) root canals in maxillary first molars using micro-computed tomography (μCT) with customized software.

Materials and methods

Human maxillary first molar MB roots (N = 36) with two separate canals (MB1, MB2) and apical foramina were scanned by μCT and analyzed with Kappa2 software to reconstruct three-dimensional (3D) surface models of roots and canals. These models were sectioned at 0.1 mm intervals perpendicular to the central axis of each canal. Canal widths, 3D curvatures, and surrounding dentine thicknesses were measured concurrently on each section. Dentine thicknesses were analyzed statistically for differences between each direction and the different levels of both canals.

Results

Dentine walls around MB1 were thicker than MB2 (p < 0.05). Thinnest dentine was most often located at disto-inside direction in both canals. Canal widths were significantly smaller in MB2 than MB1 (p < 0.01). Apical constrictions were smaller (p < 0.05) and further (p < 0.05) from the apex in MB2 than MB1. Canal curvatures were greatest in the apical third of both canals (p < 0.001), and they were greater in MB2 than MB1 (p < 0.05).

Conclusions

MB2 canals had shorter lengths, smaller widths, and more severe curvatures and were surrounded by thinner dentine walls. In MB2, apical constrictions were between 1 and 2 mm from the apex, compared to about 1 mm for MB1.

Clinical relevance

These detailed measurements and in-depth 3D analyses of maxillary first molar MB roots with two separate canals and apical foramina provide morphologic references for root canal therapy.

     

Quaternary ammonium compound as antimicrobial agent in resin-based sealants

Objectives

The aim of this study was to evaluate the influence of [2-(methacryloyloxy)ethyl] trimethylammonium chloride (METAC) in the physico-chemical properties, antibacterial activity and cytotoxicity of an experimental resin–based sealant.

Materials and methods

An experimental resin-based sealant was formulated with dimethacrylates and a photoinitiator system. METAC was added at 2.5 wt.% (G_2.5%) and 5 wt.% (G_5%) into the experimental resin–based sealant, and one group remained without METAC as control (G_CTRL). The resin-based sealants were analysed for polymerization behaviour and degree of conversion (DC), Knoop hardness (KHN) and softening in solvent (ΔKHN), ultimate tensile strength (UTS), contact angle, surface free energy (SFE), immediate and long-term micro-shear bond strength (μ-SBS) and antibacterial activity and cytotoxicity against human keratinocytes.

Results

The experimental resin–based sealants presented different polymerization behaviours without significant differences in the DC (p > 0.05). There was no significant difference for initial KHN (p > 0.05). The ΔKHN ranged from 51.62 (±3.70)% to 62.40 (±4.14)%, with higher values for G_5% (p < 0.05). G_2.5% and G_5% had decreased μ-SBS between immediate and long-term tests (p < 0.05) without significant differences among groups in the immediate and long-term analyses (p > 0.05). There were no significant differences for UTS, contact angle and SFE among groups (p > 0.05). G_2.5% and G_5% presented immediate and long-term antibacterial activity (p < 0.05) without cytotoxicity compared to G_CTRL (p > 0.05).

Conclusion

The addition of METAC provided antibacterial activity to the experimental resin–based sealant.

Clinical relevance

METAC is an effective quaternary ammonium compound as an antibacterial agent for resin-based sealants without cytotoxic effects against human keratinocytes.

     

Remineralization capacity of carious and non-carious white spot lesions: clinical evaluation using ICDAS and SS-OCT

Objectives

To assess the remineralization capacity of carious, non-carious, and combined white spot lesions (WSLs) using the ICDAS and SS-OCT.

Materials and methods

This clinical trial was based on a quasi-experimental design. Forty-two healthy subjects (median age 26.6 years), who visited university hospital and had at least one WSL with an ICDAS score of 2 or 1, were recruited. The subjects chewed a non-blind sugar-free gum containing bioavailable calcium and fluoride for 3 months. The remineralization capacities of carious and non-carious 121 WSLs were assessed using ICDAS by two calibrated non-blind examiners and optical boundary depth (BD) by SS-OCT at a monthly recall. The outcome variables, transitions of ICDAS score, mean BD, and mean BD recovery rate (RR%), were statistically analyzed using the chi-square test, two way-repeated measures ANOVA, and Wilcoxon rank sum test, respectively (alpha = 0.05).

Results

Based on the visual inspection, OCT images at the baseline, 72 WSLs were purely carious, 20 were non-carious (developmental) lesions, while 29 were combined (carious-developmental). The responses of WSLs over time showed to be highly variable. There was a significant difference in transitions of ICDAS scores after 3 months between carious and non-carious WSLs (p < 0.05) and non-carious and combined WSLs (p < 0.05). Carious and combined WSLs underwent significant changes in the mean BD between baseline (161.8 ± 56.8 μm) and 2 months (130.7 ± 57.4 μm) or 3 months (119.1 ± 57.5 μm) (p < 0.05), while there was no significant difference between baseline (132.2 ± 26.2 μm) and 2 months (122.8 ± 24.1 μm) or 3 months (119.8 ± 22.6 μm) in non-carious WSLs (p > 0.05). There was a significant difference in mean RR% after 2 and 3 months between carious and non-carious WSLs (p < 0.05).

Conclusions

The remineralization capacity of WSL was variable among the cases and subjects, and depended on the WSLs history, etiology (carious, non-carious, or combined lesion) and structure (histological pattern).

Clinical relevance

Carious WSLs showed the highest remineralization potential.

     

Influence of clodronate and compressive force on IL-1ß-stimulated human periodontal ligament fibroblasts

Objectives

The aim of this study was to investigate in vitro the effect of clodronate on interleukin-1ß (IL-1ß)–stimulated human periodontal ligament fibroblasts (HPdLFs) with the focus on inflammatory factors of orthodontic tooth movement with and without compressive force.

Materials and methods

HPdLFs were incubated with 5 μM clodronate and 10 ng/mL IL-1ß. After 48 h, cells were exposed to 3 h of compressive force using a centrifuge. The gene expression of cyclooxygenase-2 (COX-2), interleukin-6 (IL-6), matrix metalloproteinase 8 (MMP-8), and the tissue inhibitor of MMP (TIMP-1) was analyzed using RT-PCR. Prostaglandin E2 (PGE-2), IL-6, and TIMP-1 protein syntheses were quantified via ELISA.

Results

Compressive force and IL-1ß induced an overexpression of COX-2 gene expression (61.8-fold; p < 0.05 compared with control), diminished by clodronate (41.1-fold; p < 0.05 compared with control). Clodronate slowed down the compression and IL-1ß induced IL-6 gene expression (161-fold vs. 85.6-fold; p < 0.05 compared with control). TNF-α was only slightly affected without statistical significance. Clodronate reduced IL-1ß-stimulated MMP-8 expression with and without compressive force. TIMP-1 on gene and protein level was downregulated in all groups. Analyzing the MMP-8/TIMP-1 ratio, the highest ratio was detected in IL-1ß-stimulated HPdLFs with compressive force (21.2-fold; p < 0.05 compared with control). Clodronate diminished IL-1ß-induced upregulation of MMP-8/TIMP-1 ratio with (11.5-fold; p < 0.05 compared with control) and without (12.5-fold; p < 0.05 compared with control) compressive force.

Conclusion

Our study demonstrates a slightly anti-inflammatory effect by clodronate under compressive force in vitro. Additionally, the periodontal remodeling presented by the MMP-8/TIMP-1 ratio seems to be diminished by clodronate.

Clinical relevance

Reduction of pro-inflammatory factors and reduction of periodontal remodeling might explain reduced orthodontic tooth movement under clodronate intake.

     

Biological effects of low-level laser irradiation (LLLI) on stem cells from human exfoliated deciduous teeth (SHED)

Objectives

To investigate the effects of low-level laser irradiation (LLLI) on viability/proliferation, migration, osteo/odontogenic differentiation, and in vitro biomineralization of stem cells from human exfoliated deciduous teeth (SHED).

Materials and methods

SHED cultures were established by enzymatic dissociation from pulps of deciduous teeth. SHED were irradiated with a diode laser (InGaAsP; 940 nm; 0.2 W, continuous mode) at energy fluences 4, 8, and 16 J/cm² in the dark, while non-irradiated SHED served as control. Cell viability/proliferation was evaluated by MTT assay and cell mobilization by Transwell™ migration assay. Expression of osteo/odontogenesis-related genes (ALP, BMP-2, BGLAP, DSPP, MSX2, RUNX2) was assessed by real-time PCR, while in vitro biomineralization by Alizarin Red staining. Statistical analysis was performed by two-way ANOVA and Tukey’s post hoc tests (*p < 0.05, **p < 0.01).

Results

Statistically significant stimulation of cell viability/proliferation was observed at all energy fluences, reaching the highest effect for the 4 and 16 J/cm². Although the 8 J/cm² fluence showed the lowest stimulatory effect on cell viability/proliferation, it was the most effective in inducing SHED migration, upregulation of odontogenesis-related genes (DSPP, ALP, BMP-2) at specific time-points, and the in vitro biomineralization potential of SHED compared to the other two energy fluences.

Conclusions

LLLI proved beneficial in promoting SHED biological processes critical for pulp repair in deciduous teeth. Overall, the 8 J/cm² energy fluence showed the most beneficiary effects.

Clinical relevance

These results provide insights on a narrow “therapeutic window” of LLLI application in vital pulp therapies of deciduous teeth, paving the way for the establishment of effective clinical protocols.

     

Dentinal tubule penetration of AH Plus,BC Sealer and a novel tricalcium silicate sealer: a confocal laser scanning microscopy study

Objectives

The aim of this in vitro study was to assess the dentinal tubule penetration of three different sealers, AH Plus, BC Sealer and a novel tricalcium silicate sealer (NTS).

Materials and methods

Ninety-six human maxillary central incisors were divided into three experimental groups (n = 32) and were filled with gutta-percha using a single-cone technique in conjunction with one of the three sealers: AH Plus, BC Sealer or NTS. The roots in each group were cross-sectioned at 1 and 5 mm from the root apex, and the surfaces were examined under confocal laser scanning microscopy (CLSM). The sealer penetration depths were measured at their maximum depths and at four circumferential depths (12, 3, 6 and 9 o’clock) and were evaluated using ImageJ software (ImageJ, NIH).

Results

The maximum and mean penetration depths were significantly higher at 5 mm compared to 1 mm from the apex in the AH Plus (p < 0.001), BC Sealer (p < 0.001) and NTS groups (p < 0.001). No significant difference was observed between the groups at 1 mm for both parameters. The maximum and mean penetration depths were significantly lower at 5 mm for AH Plus compared with the other two groups (p = 0.012).

Conclusions

Within the study limitations, the BC Sealer and NTS demonstrated better tubule penetration results than the AH Plus sealer.

Clinical relevance

Although no study has confirmed a relationship between the penetration depth of root canal sealers and the prevention of apical periodontitis, dentinal tubule sealer penetration may improve obturation quality.

     

The impact of print orientation on the fracture resistance and failure patterns of additively manufactured cobalt-chromium post and cores

Purpose

The aim of this study was to evaluate the impact of the print orientation of direct metal laser sintering (DMLS) posts and cores on the fracture resistance and failure patterns of endodontically treated mandibular premolar teeth.

Materials and Methods

Sixty intact human mandibular premolars were endodontically treated. The teeth were then randomly divided into four groups (n = 15). Cobalt-chromium (Co-Cr) metal posts were fabricated by traditional casting (Group C), and DMLS method in 0-, 45-, and 90-degree print orientations (Group DMLS 0, Group DMLS 45, and Group DMLS 90). The posts and cores were cemented with composite resin cement and subjected to compression test at a crosshead speed of 1 mm/min. Data was analyzed by using one-way analysis of variance ANOVA and multiple comparison post hoc Tukey tests (α = 0.05). Specimens were viewed under a stereo microscope with x20 magnification to evaluate the fracture types.

Results

No significant differences were found among the groups tested in terms of fracture resistance (p > 0.05). Group C and Group DMLS 0 group exhibited similar fracture patterns.

Conclusions

It is possible to produce post and core restorations with the DMLS technique and use them clinically.  Print orientation did not influence the fracture resistance. However, fracture patterns were different. Group C outperformed all DMLS groups in terms of fracture patterns.     

Effect of intracanal cryotherapy on the fracture resistance of endodontically treated teeth

Objective: The aim of this study is to evaluate the effect of intracanal cryotherapy on the fracture resistance of endodontically treated teeth.

Materials and methods: Sixty single-rooted maxillary lateral incisor teeth with single root canals were selected and randomly divided into two groups (n?=?30). The specimens were immersed in distilled water, which was heated to 37?°C during the procedures. The root canals were chemomechanically prepared up to the apical size of 50 and assigned to either the control group or the cryotherapy group. The specimens in the cryotherapy group were irrigated with 20?mL sterile cold (2.5?°C) saline solution, which was delivered with an EndoVac system for 5?min, whereas the specimens in the control group received a sterile saline solution at room temperature. The fracture resistance of the specimens was then tested with a universal testing machine. The data was analyzed using the independent sample t test with a 5% significance threshold.

Results: The fracture strength of the specimens in the intracanal cryotherapy group was significantly lower than that of the control group (p< .05).

Conclusions: Application of intracanal cryotherapy as a final irrigant reduced the vertical fracture resistance of prepared roots when compared to the control group.     

Effects of non-thermal atmospheric plasma treatment on dentin wetting and surface free energy for application of universal adhesives

Objectives

The study aims to evaluate the effects of non-thermal atmospheric plasma (NTAP) treatments on dentin wetting and surface free energy (SFE) and compare the effects of NTAP treatment, etch-and-rinse, and self-etch protocols for application of universal adhesives.

Materials and methods

Mid-coronal dentin of intact third molars was used to measure contact angles of distilled water, ethylene-glycol, and diiodomethane and calculate SFE following different NTAP preset treatments (feeding gas consisting of pure He, He + 1% O₂, He + 1.5% O₂), power input (1 or 3 W), and tip-to-surface distance (2, 4, or 8 mm). Contact angles of reference liquids and SFE of dentin following He + 1.5% O₂ at 3-W and 4-mm treatment was compared to phosphoric acid etching. Contact angles of Single Bond Universal (SBU; 3M ESPE) and Clearfil Universal Bond (CUB; Kuraray Noritake) were measured following NTAP, etch-and-rinse, and self-etch protocols.

Results

NTAP significantly reduced contact angles of reference liquids and increased dentin SFE compared to untreated dentin (p < 0.05). O₂ intensified the effect of He NTAP (p < 0.05). NTAP and phosphoric acid increased dentin polarity and Lewis base surface characteristics. Phosphoric acid increased contact angles of adhesives compared to the self-etch protocol (p < 0.05). NTAP resulted in lower adhesive contact angles than phosphoric acid, the difference being statistically significant for CUB (p < 0.05). Compared to the self-etch protocol, NTAP slightly reduced CUB contact angle but not that of SBU (p > 0.05).

Conclusions

He NTAP with and without O₂ increased dentin wetting and SFE, surpassing the effect of phosphoric acid and lowering adhesive contact angles. NTAP produced no apparent micro-morphological changes on dentin surface comparable to acid etching.

Clinical significance

NTAP treatment of dentin prior to adhesive application increases dentin wetting and surface free energy facilitating better adhesive distribution on dentin surface compared to phosphoric acid etching and similar to the “self-etch” application protocol.

     

Chemical analysis of in vivo–irradiated dentine of head and neck cancer patients by ATR-FTIR and Raman spectroscopy

Objectives

To evaluate the effect of in vivo radiotherapy on the chemical properties of human dentine by Fourier-transform infrared spectroscopy (FTIR) and Raman analysis.

Materials and methods

Chemical composition was evaluated comparing control and irradiated group (n = 8). Irradiated teeth were obtained from radiotherapy patients subjected to fractionated X-ray radiation of 1.8 Gy daily totaling 72 Gy. The teeth were sectioned according to the type of dentine (crown or root dentine), obtaining 3-mm dentine cervical slices. The analyzed parameters by FTIR and Raman spectroscopies were mineral/matrix ratio (M:M), carbonate/mineral ratio (C:M), amide I/amide III ratio, and amide I/CH₂ ratio. Raman also calculated the phosphate and carbonate crystallinity.

Results

FTIR revealed that M:M had a decrease in both factors (p = 0.008; p = 0.043, respectively) and root dentine showed a lower C:M in the irradiated group (p = 0.003). Raman revealed a higher phosphate crystallinity and a lower carbonate crystallinity in crown dentine of irradiated group (p = 0.021; p = 0.039). For amide I/amide III, the irradiated showed a lower ratio when compared to the control group (FTIR p = 0.002; Raman p = 0.017). For amide I/CH₂, the root dentine showed a higher ratio than the crown dentine in both methods (p < 0.001).

Conclusions

Radiotherapy altered the chemical composition of human dentine. The exchange of phosphate-carbonate ions in the hydroxyapatite and higher concentration of organic components was found after radiotherapy.

Clinical relevance

The increased risk of radiation-related caries in patients undergoing head and neck radiotherapy is due not only to salivary, dietary, and microbiological changes but also to changes in tooth chemical composition.