Biocompatibility Evaluation of Biodentine in Subcutaneous Tissue of Rats

Introduction

Biodentine (Septodont, St-Maur-des-Fossés, France) is a new material suitable for various clinical situations in endodontics, such as perforation repair, retrograde filling, pulp capping, and others. Because it is a new material, its properties should be analyzed before routine clinical use. Thus, this study evaluated the biocompatibility of Biodentine in the subcutaneous tissue of rats.

Methods

This study was conducted on 15 male rats. Two incisions were made on the dorsal region of each animal for the introduction of 4 tubes. One tube was empty, 1 was filled with zinc oxide–eugenol cement, 1 was filled with mineral trioxide aggregate, and the last tube was filled with Biodentine. After 7, 14, and 30 days, the animals were sacrificed, and the specimens were submitted to histotechnical preparation. The histologic sections were stained with hematoxylin-eosin and analyzed using light microscopy. Scores were established according to the inflammatory process and were statistically compared using the Kruskal-Wallis test (P < .05).

Results

The analysis of the histologic sections evidenced a nonsignificant or mild presence of inflammatory reaction in the connective tissue in contact with the empty tube and the tube containing MTA, which was different from the tube containing zinc oxide eugenol. The connective tissue was moderately inflamed at 7 days when in contact with Biodentine; however, at 14 and 30 days, the inflammatory process was mild or nonsignificant.

Conclusions

Biodentine was biocompatible with tissue after the 14th day.     

Biocompatibility of New Calcium Aluminate Cement: Tissue Reaction and Expression of Inflammatory Mediators and Cytokines

Introduction

The aim of this study was to evaluate the biocompatibility of a new calcium aluminate cement (EndoBinder) in subcutaneous tissue of rats in comparison with mineral trioxide aggregate and calcium hydroxide hard-setting cement.

Methods

Polyethylene tubes (1.5 × 10 mm) containing the dental cements were implanted into dorsal subcutaneous tissue of 30 rats. After experimental periods of 7, 30, and 90 days, biopsies were performed for tissue response analysis under optical light microscope. The mRNA extraction was performed for molecular evaluation of the inflammatory process in the peri-implant tissue, which was submitted to quantitative real-time polymerase chain reaction analysis for inflammatory mediators and cytokines TNF-α, Ptges2, Il-1β, Il-4, and Il-10.

Results

On the basis of the score used to grade the tissue reaction (0–3), EndoBinder (0) presented no inflammatory reaction after the 90-day period, a similar result to mineral trioxide aggregate and calcium hydroxide. The thickness of inflammatory capsules (μm) also presented significant decrease during the course of periods (P < .05). As regards expression of inflammatory mediators, Ptges2 and Il-10 were detected only at 7 and 30 days, with no statistically significant difference among the experimental groups (P > .05).

Conclusions

EndoBinder induced limited inflammatory reaction. It was considered biocompatible when tested in subcutaneous tissue of rats.     

The Effect of Medicaments Used in Endodontic Regeneration Technique on the Dislocation Resistance of Mineral Trioxide Aggregate to Root Canal Dentin

Introduction

The aim of this study was to evaluate the effect of calcium hydroxide (CH) and antibiotic pastes, including a mixture of metronidazole and ciprofloxacin, with and without minocycline or cefaclor, on the dislocation resistance of mineral trioxide aggregate (MTA) to root dentin.

Methods

Eighty single-rooted human mandibular premolars were selected. The teeth were prepared by using the ProTaper system. The prepared teeth were then instrumented to a #6 Peeso reamer to obtain a standard internal diameter of 1.5 mm. The reamers were passed 1 mm beyond apex to simulate immature teeth. The specimens were then randomly divided into a control group (no intracanal medicament was used) and 4 experimental groups that were treated with an intracanal medicament: CH, double antibiotic paste (DAP) with metronidazole and ciprofloxacin, triple antibiotic paste (TAP) with minocycline, or TAP with cefaclor (n = 16). After 3 weeks, the medicaments were removed, and approximately 3 mm of MTA was placed in the coronal third of the canals. A push-out test was used to measure the dislocation resistance between the root dentin and MTA. Data were analyzed by using one-way analysis of variance and Tukey post hoc tests.

Results

The dislocation resistance values of the CH, TAP with minocycline, and TAP with cefaclor groups were similar to those of the control group (P > .05), whereas the DAP group had the lowest dislocation resistance when compared with the other groups (P < .05). Overall, there was a predominance of cohesive failures between root dentin and MTA.

Conclusions

The results of this study indicate that the application of DAP as an intracanal medicament reduced the dislocation resistance of MTA to root dentin.     

Subcutaneous tissue reaction to castor oil bean and calcium hydroxide in rats

Castor oil bean cement (COB) is a new material that has been used as an endodontic sealer, and is a candidate material for direct pulp capping.

Objective

The purpose of this study was to evaluate the biocompatibility of a new formulation of COB compared to calcium hydroxide cement (CH) and a control group without any material, in the subcutaneous tissue of rats.

Material and methods

The materials were prepared, packed into polyethylene tubes, and implanted in the rat dorsal subcutaneous tissue. Animals were sacrificed at the 7th and 50th days after implantation. A quantitative analysis of inflammatory cells was performed and data were subjected to ANOVA and Tukey''s tests at 5% significance level.

Results

Comparing the mean number of inflammatory cells between the two experimental groups (COB and CH) and the control group, statistically significant difference (p=0.0001) was observed at 7 and 50 days. There were no significant differences (p=0.111) between tissue reaction to CH (382 inflammatory cells) and COB (330 inflammatory cells) after 7 days. After 50 days, significantly more inflammatory cells (p=0.02) were observed in the CH group (404 inflammatory cells) than in the COB group (177 inflammatory cells).

Conclusions

These results demonstrate that the COB cement induces less inflammatory response within long periods.     

Effect of Calcium Hydroxide and Double and Triple Antibiotic Pastes on the Bond Strength of Epoxy Resin–based Sealer to Root Canal Dentin

Introduction

The aim of this study was to evaluate the effects of calcium hydroxide (CH) and triple (TAP) and double (DAP) antibiotic pastes on the bond strength of an epoxy resin–based sealer (AH Plus Jet; Dentsply DeTrey, Konstanz, Germany) to the root canal dentin.

Methods

Sixty-four single-rooted human mandibular premolars were decoronated and prepared using the rotary system to size 40. The specimens were randomly divided into a control group (without intracanal dressing) and 3 experimental groups that received an intracanal dressing with either CH, DAP, or TAP (n = 16). The intracanal dressing was removed by rinsing with 10 mL 17% EDTA followed by 10 mL 2.5% sodium hypochlorite. The root canals were then obturated with gutta-percha and AH Plus Jet sealer. A push-out test was used to measure the bond strength between the root canal dentin and the sealer. The data were analyzed using 2-way analysis of variance and Tukey post hoc tests to detect the effect of the independent variables (intracanal medicaments and root canal thirds) and their interactions on the push-out bond strength of the root canal filling material to the root dentin (P = .05).

Results

The push-out bond strength values were significantly affected by the intracanal medicaments (P < .001) but not by the root canal thirds (P > .05). In the middle and apical third, the bond strength of the TAP group was higher than those of the CH and DAP groups (P < .05).

Conclusions

The DAP and CH did not affect the bond strength of the epoxy resin–based sealer. Additionally, the TAP improved the bond strength of the epoxy resin–based sealer in the middle and apical thirds.     

Evaluation of subcutaneous and alveolar implantation surgical sites in the study of the biological properties of root-end filling endodontic materials

Objective

The aim of this study was to compare two methodologies used in the evaluation of tissue response to root-end filling materials in rats.

Material and Methods

Forty rats were divided into 4 groups: in Groups I and II (control groups), empty polyethylene tubes were implanted in the extraction site and in the subcutaneous tissue, respectively; in Groups III and IV, polyethylene tubes filled with ProRoot MTA were implanted in the extraction site and in the subcutaneous tissue, respectively. The animals were killed 7 and 30 days after tube implantation, and the hemi-maxillas and the capsular subcutaneous tissue, both with the tubes, were removed. Specimens were processed and evaluated histomorphologicaly under light microscopy. The scores obtained were analyzed statistically by the Kruskal-Wallis test (p<0.05).

Results

There were no statistically significant differences between the implantation methods (p=0.78033, p=0.72039). It was observed that the 30-day groups presented a more mature healing process due to smaller number of inflammatory cells.

Conclusion

The present study showed no differences in tissue responses as far as the implantation site and the studied period were concerned. Alveolar socket implantation methodology represents an interesting method in the study of the biological properties of root-end filling endodontic materials due to the opportunity to evaluate bone tissue response.     

Spectrophotometric Analysis of Crown Discoloration Induced by Various Antibiotic Pastes Used in Revascularization

Introduction

Antibiotic pastes are used for disinfection in regenerative endodontic procedures. This study evaluated the crown discoloration induced by various antibiotic pastes including the mixture of metronidazole and ciprofloxacin with minocycline, doxycycline, amoxicillin, or cefaclor.

Methods

Seventy extracted bovine incisors were sectioned to obtain a standardized root length of 10 mm above the facial cementoenamel junction. After pulp tissue removal, irrigation with sodium hypochlorite and the placement of temporary filling material and cotton pellet were performed from the apical aspect. The specimens were then randomly divided into 7 groups (n = 10 for each group), and each group received the following antibiotic paste fillings: no filling (control group), calcium hydroxide, double antibiotic paste (DAP), triple antibiotic paste (TAP) with minocycline, TAP with doxycycline, TAP with amoxicillin, and TAP with cefaclor. Spectrophotometric readings were obtained on the buccal surfaces of the crown on day 1 to week 3 after filling, and the ΔE value was calculated. Data were analyzed with 2-way analysis of variance and the Tukey post hoc tests (P = .05), and the human perceptibility threshold was set to 3.7.

Results

TAP with minocycline, doxycycline, and cefaclor induced more coronal discoloration compared with the control group (P < .05). The control, calcium hydroxide, and DAP groups showed no color changes exceeding the perceptibility threshold at all time points.

Conclusions

The results indicated that all antibiotic pastes, except DAP, induced crown discoloration.     

In vivo host interactions with mineral trioxide aggregate and calcium hydroxide: inflammatory molecular signaling assessment

Introduction

Mineral trioxide aggregate (MTA) and calcium hydroxide [Ca(OH)₂] are promising biomaterials for stimulating dentinogenesis and cementogenesis. This research was undertaken to understand how MTA and CA(OH)₂ participate in the inflammatory, healing, and biomineralization processes. In this part of the study, we evaluated inflammatory signaling molecules promoted by in vivo host interaction with MTA and Ca(OH)₂.

Methods

Human dentin tubes were filled with ProRoot MTA (Dentsply Tulsa Dental, Tulsa, OK), Ca(OH)₂, or kept empty. After 12 hours and 1, 3, 7, 15, 30, and 60 days of implantation in subcutaneous tissues in the backs of mice, the tubes and surrounding tissues were retrieved for cytokine level quantification and histological and immunohistochemical analysis.

Results

MTA and Ca(OH)₂ induced proinflammatory cytokine up-regulation for up to 3 days. Moreover, interleukin-10 overexpression was noted on the tissue in contact with the biomaterials during the acute phase of the inflammatory reaction. Immunohistochemical analyses showed an increased expression of myeloperoxidase, nuclear factor kappa B (NF-κB), cyclooxygenase-2, inducible nitric oxide synthase enzymes, and vascular endothelial growth factor on day 1 for all groups.

Conclusions

MTA and Ca(OH)₂ increased the activation of the NF-κB signaling system on day 1 for all groups. This finding can be associated with a proinflammatory and pro-wound healing environment, which was promoted earlier by MTA.     

M2 Macrophages Participate in the Biological Tissue Healing Reaction to Mineral Trioxide Aggregate

Introduction

This study examined the protein and messenger RNA (mRNA) expression of molecules associated with M2 (wound healing) macrophages in mineral trioxide aggregate (MTA)-implanted rat subcutaneous tissue to elucidate the involvement of M2 macrophages in the connective tissue response to MTA.

Methods

Silicone tubes containing freshly mixed MTA or a calcium hydroxide cement (Life; Kerr, Romulus, MI) were subcutaneously implanted into the backs of Wistar rats. Solid silicone rods implanted in different animals served as controls. The specimens were then double immunostained for ED1 (CD68, a general macrophage marker) and ED2 (CD163, an M2 macrophage marker). Immunostaining for CD34 (a marker for vascularization and wound healing) was also performed. Expression levels of CD34, CD163, and mannose receptor c type 1 (an M2 macrophage marker) mRNAs were determined with real-time polymerase chain reaction.

Results

MTA-implanted subcutaneous tissues showed significant increases in the density of ED1+ED2+ macrophages beneath the implantation site and expression levels of CD163 and MMR mRNAs compared with Life-implanted and control tissues. MTA-implanted subcutaneous tissues also showed a significant increase of CD34-immunostained areas and up-regulation of CD34 mRNAs compared with Life-implanted and control tissues.

Conclusions

MTA implantation induced the accumulation of M2 macrophage marker (ED2)-expressing macrophages and enhanced the expression of M2 macrophage marker genes. MTA implantation also enhanced the expression of CD34, suggesting acceleration of the healing/tissue repair process. Taken together, biological connective tissue response to MTA may involve wound healing/tissue repair processes involving M2 macrophages.     

Experimental periodontitis promotes transient vascular inflammation and endothelial dysfunction

Objectives

This study aimed to evaluate the systemic inflammatory response and cardiovascular changes induced by experimental periodontitis in rats.

Design

Experimental periodontitis was induced by placing a cotton ligature around the cervix of both sides of mandibular first molars and maxillary second molars in each male rat. Sham-operated rats had the ligature removed immediately after the procedure. Seven, 14 or 28 days after procedure, the effects of acetylcholine, sodium nitroprusside and phenylephrine were evaluated on blood pressure, aortic rings and isolated and perfused mesenteric bed. The blood was obtained for plasma Interleukin-6 (IL-6), C-reactive protein (CRP) and lipid evaluation. The mesenteric vessels were obtained to evaluate superoxide production and nitric oxide synthase 3 (NOS-3) expression.

Results

Ligature induced periodontitis reduced endothelium-dependent vasodilatation, a hallmark of endothelial dysfunction. This effect was associated with an increase in systemic inflammatory markers (IL-6 and CRP), worsens on lipid profile, increased vascular superoxide production and reduced NOS-3 expression. It is interesting to note that many of these effects were transitory.

Conclusion

Periodontitis induced a transient systemic and vascular inflammation which leads to endothelial dysfunction, an initial step for cardiovascular diseases. Moreover, the animal model of periodontitis used here may represent a valuable tool for studying the relationship between periodontitis and endothelial dysfunction.     

Intracanal Delivery of Resolvin E1 Controls Inflammation in Necrotic Immature Rat Teeth

Introduction

Pulp necrosis in immature teeth and the resulting periodontal apical inflammation negatively affect root formation. Resolvin E1 (RvE1) is a lipid-derived endogenous pro-resolution molecule that controls inflammation. The aim of this investigation was to evaluate the impact of RvE1 applied as an intracanal medication on root formation in nonvital immature teeth.

Methods

To arrest root development, pulpectomy was performed in the lower first molars of 4-week-old Wistar rats. After 3 weeks, irrigation with 2.5% sodium hypochlorite and 0.9% sterile saline was performed, and either a triple antibiotic paste (TAP) or RvE1 in saline was applied into the root canals. In the control group, access openings drilled into molars were left exposed to the oral environment. Root development and periapical repair were evaluated radiographically and histologically at 3 and 6 weeks after treatment.

Results

RvE1 reduced periapical lesion size compared with the control at 3 weeks, which was similar to TAP. Inflammatory response in the RvE1-treated group was markedly reduced compared with both TAP and control specimens. At 6 weeks, root development was observed in both groups, but RvE1 treatment produced less cellularity with more regular calcified tissue deposition.

Conclusions

RvE1 and TAP had a positive impact on reducing inflammation and promoting root formation. RvE1 was more effective in reducing inflammation at earlier stages. RvE1 has potential to be used as root canal dressing to control inflammation in endodontically compromised teeth before complete root formation. Stability of RvE1 within the root canal and its delivery are issues to be addressed before its clinical use.     

Effect of Dentin Conditioning with Intracanal Medicaments on Survival of Stem Cells of Apical Papilla

Introduction

Regenerative endodontics is a valuable treatment modality for immature teeth with pulpal necrosis. A common feature in regenerative cases is the use of intracanal medicaments. Although these medicaments are chosen because of their antibacterial properties, their enduring effect on dentin (conditioning) and the subsequent impact on stem cell survival has never been evaluated. In this study, we hypothesized that triple antibiotic paste (TAP), double antibiotic paste (DAP), or Ca(OH)₂ has an indirect adverse effect on the survival of stem cells of apical papilla (SCAP) by dentin conditioning.

Methods

Human dentin disks were created with a standardized root canal diameter of 3.2 mm. The disks were then exposed to either TAP or DAP (at concentrations of 1 mg/mL or 1000 mg/mL), Ca(OH)₂ (Ultracal), or Hank's balanced salt solution for 7 or 28 days. Next, the medicaments were removed with copious irrigation, followed by placement of SCAP in a Matrigel scaffold in the lumen of the disks. The bioengineered constructs were cultured for 7 days, followed by determination of cellular viability by using the CellTiter-Glo luminescence assay. Data were analyzed using 1-way analysis of variance with Bonferroni post hoc test.

Results

Exposure of dentin to TAP or DAP at 1000 mg/mL resulted in no viable SCAP, whereas the use of these medicaments at 1 mg/mL had no adverse effect on cell viability. In contrast, Ca(OH)₂ treatment significantly increased SCAP survival and proliferation when compared with the control group.

Conclusions

Dentin conditioning with TAP and DAP at commonly used clinical concentration (approximately 1000 mg/mL) alters dentin in such a way as to prevent SCAP survival. This lethal indirect effect of both TAP and DAP can be largely avoided if these medicaments are used at the 1 mg/mL concentration. Conversely, dentin conditioning with Ca(OH)₂ promotes SCAP survival and proliferation.     

Apical Extrusion of Debris Using Self-Adjusting File,Reciprocating Single-file,and 2 Rotary Instrumentation Systems

Introduction

The purpose of this study was to evaluate the weight of debris extruded apically from teeth using different in vitro preparation techniques.

Methods

Sixty-eight extracted human mandibular premolars with single canals and similar lengths were instrumented using ProTaper F2 (25, .08; Dentsply Maillefer, Ballaigues, Switzerland), the Self-Adjusting File (1.5-mm diameter; Re-Dent Nova, Ra'anana, Israel), Revo-S SU (25, .06; MicroMega, Besancon, France), or Reciproc (R25; VDW GmbH, Munich Germany). Debris extruded during instrumentation were collected into preweighed Eppendorf tubes. The Eppendorf tubes were then stored in an incubator at 70°C for 5 days. The Eppendorf tubes were weighed to obtain the final weight of the Eppendorf tubes when the extruded debris were included. Three consecutive weights were obtained for each tube.

Results

There were no statistically significant differences among the groups (P = .218). The ProTaper group produced the highest mean extrusion value. The Reciproc produced less debris compared with all the other instruments (P > .05).

Conclusions

All instrumentation techniques were associated with extruded debris.     

Iloprost Induces Tertiary Dentin Formation

Introduction

Prostacyclin (PGI₂), a member of the prostaglandin family, can promote angiogenesis and cell proliferation.

Methods

In this study, the effect of the application of a PGI₂ analog (iloprost) on dentin repair was examined in vitro and in vivo.

Results

Iloprost significantly stimulated the expression of vascular endothelial growth factor and osteo-/odontogenic marker messenger RNA in human dental pulp cells (HDPCs) under osteoinductive conditions in vitro. In addition, iloprost enhanced HDPC alkaline phosphatase enzymatic activity and mineral deposition. An in vivo study was performed using a rat molar mechanical pulp exposure model. After 30 days, histologic analysis revealed that there was a dramatic tertiary dentin formation in the iloprost-treated group compared with the calcium hydroxide and the untreated control groups. Furthermore, vascular endothelial growth factor protein expression in dental pulp tissue was increased in the iloprost-treated group as determined by immunohistochemical staining.

Conclusions

Taken together, the present study, for the first time, shows that iloprost induces the expression of osteo-/odontogenic markers in vitro and promotes angiogenic factor expression and enhances tertiary dentin formation in vivo. This implies the potential clinical usefulness of iloprost in vital pulp therapy.     

Evaluation of Triple Antibiotic Paste Removal by Different Irrigation Procedures

Introduction

Regenerative endodontics aims to re-establish a functional pulp-dentin complex. First, the root canal system is disinfected primarily by irrigants and medicaments. Triple antibiotic paste (TAP), a commonly used intracanal medicament, has been shown to be directly toxic to stem cells at concentrations greater than 0.1 g/mL. Thus, its complete removal is a crucial step in regenerative endodontic procedures. We hypothesized that currently used irrigation techniques do not completely remove TAP from root canal system.

Methods

TAP was radiolabeled by the incorporation of I¹²⁵, and calcium hydroxide (Ultracal; Ultradent, South Jordan, UT) was radiolabeled with Ca⁴⁵. The intracanal medicaments were placed into standardized human root segments and incubated for 28 days at 37°C. Then, canals were irrigated with EndoActivator (Dentsply, Tulsa, OK), passive ultrasonic irrigation, EndoVac (SybronEndo, Coppell, TX), or a syringe/Max-i-Probe needle (Dentsply Rinn, Elgin, IL) using a standardized irrigation protocol in a closed system. Radioactivity levels (counts per minute values) were measured for each tooth before and after the irrigation protocols. Furthermore, the canals were sequentially enlarged and dentin samples collected and evaluated for radioactivity. Data were analyzed with analysis of variance and Bonferroni post hoc testing (P < .05).

Results

Approximately 88% of the TAP was retained in the root canal system regardless of the irrigation technique used (no difference among groups). Furthermore, approximately 50% of the radiolabeled TAP was present circumferentially up to 350 μm within the dentin. Conversely, up to 98% of the radiolabeled intracanal calcium hydroxide was removed, and most residual medicament was found present in the initial 50 μm of dentin.

Conclusions

Current irrigation techniques do not effectively remove TAP from root canal systems, possibly because of its penetration and binding into dentin. However, calcium hydroxide is effectively removed with significant less residual presence.     

L’importanza dei Toll-Like Receptors nei tessuti parodontali. Ruolo delle cellule del parodonto nell’attivazione dell’infiammazione locale in seguito ad aggressione batterica

Objectives

As become clear in recent years, periodontitis is an inflammatory disease initiated by the oral microbial biofilm and mediated by a set of receptors that Pathogenrecognize microbial components: Toll-Like Receptors (TLR).

Materials and methods

This paper reviews recent findings on TLR expression and functions on innate immune cells and periodontium, and direct and indirect effects of invading pathogens on bone remodeling observed in periodontitis.

Results

The binding between molecules coming from periodontopathogenic organisms and sensing pathogen receptors named Toll-Like Receptors (TLR) causes the initial inflammatory reactions and induces osteoclastogenesis.

Conclusions

The crucial role of TLR in the pathogenesis of periodontitis prompts us to speculate on new therapeutic strategies, which involving TLR and TLR agonists, may contain the inflammation and prevent tissue destruction.     

Traumatized Immature Teeth Treated with 2 Protocols of Pulp Revascularization

Introduction

Pulp revascularization may be considered a promising alternative for traumatized necrotic immature teeth. The aim of this study was to evaluate traumatized immature teeth treated with 2 protocols of pulp revascularization.

Methods

Twenty-three teeth of young patients (7–17 years old) with necrotic upper incisors caused by dental trauma were divided into 2 groups; one group was treated with triple antibiotic paste (metronidazole, ciprofloxacin, and minocycline) (TAP) (n = 12), and the other was medicated with combination of calcium hydroxide and 2% chlorhexidine gel (CHP) (n = 11). Patients were treated and followed up for a period from 9–19 months in 2 dental institutions for evaluation of clinical and radiographic data.

Results

Most of the teeth were affected by lateral luxation (47.8%). Clinical evaluation in group TAP showed significant reduction in spontaneous pain (P = .01), pain on horizontal percussion (P = .007), and pain on palpation (P = .03), whereas group CHP showed significant reduction in pain on vertical percussion (P = .03). Crown discoloration was observed significantly more in teeth of group TAP (83.3%) (P < .002). On radiographic exam, periapical repair was found in all TAP-treated teeth (P = .03). Similarly, the same findings were found for all teeth treated with CHP with exception of 1 tooth (P = .21). Apical closure was significantly observed in both groups (P < .05). Increase in root length was demonstrated in 5 teeth (41.7%) and 3 teeth (27.3%) of groups TAP and CHP, respectively. Thickening of lateral dentinal walls was observed in 5 teeth of each group.

Conclusions

Revascularization outcomes for traumatized patients treated with the tested protocols presented similar clinical and radiographic data. However, TAP caused esthetic problem leading to tooth discoloration, which can be considered a disadvantage when compared with CHP.     

Efficacy of Needle Irrigation,EndoActivator, and Photon-initiated Photoacoustic Streaming Technique on Removal of Double and Triple Antibiotic Pastes

Introduction

Photon-induced photoacoustic streaming (PIPS) is a novel technique used for the removal of material on root canal walls, such as bacteria and the smear layer. This study evaluated the efficacy of needle irrigation, the EndoActivator System (Dentsply Tulsa Dental Specialties, Tulsa, OK), and PIPS on the removal of antibiotic pastes from an artificial groove created in a root canal.

Methods

Root canal preparation was performed up to size #40 on 84 extracted single-rooted teeth using ProTaper rotary instruments (Dentsply Maillefer, Ballaigues, Switzerland). The specimens were then split longitudinally, and 2 standardized grooves were prepared in the coronal and apical part of each segment. Double (DAP) and triple antibiotic pastes (TAP) were placed in the grooves for 4 weeks, and the root halves were reassembled. Needle irrigation, the EndoActivator System, and PIPS were used for the removal of DAP and TAP. The root segments were disassembled, and the amount of remaining antibiotic pastes was evaluated under a stereomicroscope at 20× magnification using a 4-grade scoring system. The data were evaluated statistically using Mann-Whitney U tests with a 95% confidence level (P = .05).

Results

PIPS removed significantly more antibiotic pastes than the EndoActivator and needle irrigation (P < .001). The EndoActivator was superior to needle irrigation in removing antibiotic pastes (P < .001). There were no statistically significant differences between DAP and TAP and between coronal and apical thirds in their removing from artificially created grooves (P > .05).

Conclusions

PIPS was more effective in removing both DAP and TAP from artificial grooves in root canals than the EndoActivator System and needle irrigation. The EndoActivator was also more effective than needle irrigation. It is difficult to completely remove antibiotic pastes from root canals.     

Tissue Response and Immunoexpression of Interleukin 6 Promoted by Tricalcium Silicate–based Repair Materials after Subcutaneous Implantation in Rats

Introduction

The aim of the present study was to evaluate the inflammatory response induced by experimental tricalcium silicate cement with 20% zirconium oxide (TSC) and MTA Plus (MTAP; Avalon Biomed Inc, Bradenton, FL) in rat subcutaneous tissues.

Inflammation–regeneration interplay in the dentine–pulp complex

Objectives

Dental tissue disease and trauma provides an excellent model for the interaction between tissue defence and regenerative processes and has application to many of the body's other tissues. Following dental tissue infection, characterised by caries, the molecular and cellular mediators of the immune/inflammatory processes clearly impact on the dental tissues’ natural regenerative responses. This review of the literature was performed to better understand how these two processes interact and identify whether cross-talk may provide novel areas for future research and subsequent translation into clinical application.

Data and sources

A review of the literature was performed using the PubMed database resource and this was followed by extensive hand searching using reference lists from relevant articles.

Conclusions

Frequently, the dental tissue inflammatory and regenerative processes are seen as both distinct and antagonistic and subsequently have often been studied in isolation; however, both direct and indirect data are now emerging which indicate significant inter-relationship. Whilst the ensuing inflammatory process will result in dental tissue breakdown and molecular signalling which may impede regeneration, low grade inflammation, potentially induced by mechanical trauma and tissue necrosis, may promote regenerative mechanisms, including angiogenic and stem cell processes. Notably, the locally derived growth factors, neuropeptides, cytokines and chemokines, released from the host dentine matrix and by resident pulpal cells, immune cells, neurons and/or dying cells, will modulate defence and repair processes within the tissue.