Immunohistological study of the effect of vascular Endothelial Growth Factor on the angiogenesis of mature root canals in rat molars.

Tissue bioengineering has been applied to Endodontics to seek a more biological treatment. The presence of blood vessels is crucial for cell nutrition during tissue formation. Objective This study analysed the application of vascular endothelial growth factor (VEGF) in the angiogenesis of mature root canals. Material and methods Upper first molars of twelve 13-week old Wistar male rats were used. The root pulp of the mesiobuccal canal was removed and the root canal instrumented with K-files up to size #25. Periapical bleeding was induced into the root canal by introducing a #15 K-file beyond the apex. The teeth on the right side of the arch were filled up with blood clot (G1), whereas those on the left side were filled up with blood clot plus 50 ng/ml of VEGF (G2). Teeth were sealed with light-curing glass-ionomer cement and the animals were sacrificed after 60 days. The maxilla was dissected and fixed before obtaining serial sections for histological processing with haematoxylin-eosin (HE) and immunohistochemical factor-VIII. Immunohistochemical labelling was evaluated using scores for statistical analysis. Results Immunohistological analysis demonstrated the presence of angiogenesis in both groups, but with higher angiogenic maturation in G2 during the experimental period (p<0.05). HE staining showed connective tissue with absence of odontoblasts in all specimens. Conclusions It can be concluded that it is possible to obtain angiogenesis in mature root canals with or without the use of VEGF, although the latter tends to accelerate blood vessel formation.

Immunohistological study of the effect of vascular Endothelial Growth Factor on the angiogenesis of mature root canals in rat molars

Abstract Tissue bioengineering has been applied to Endodontics to seek a more biological treatment. The presence of blood vessels is crucial for cell nutrition during tissue formation. Objective This study analysed the application of vascular endothelial growth factor (VEGF) in the angiogenesis of mature root canals. Material and methods Upper first molars of twelve 13-week old Wistar male rats were used. The root pulp of the mesiobuccal canal was removed and the root canal instrumented with K-files up to size #25. Periapical bleeding was induced into the root canal by introducing a #15 K-file beyond the apex. The teeth on the right side of the arch were filled up with blood clot (G1), whereas those on the left side were filled up with blood clot plus 50 ng/ml of VEGF (G2). Teeth were sealed with light-curing glass-ionomer cement and the animals were sacrificed after 60 days. The maxilla was dissected and fixed before obtaining serial sections for histological processing with haematoxylin-eosin (HE) and immunohistochemical factor-VIII. Immunohistochemical labelling was evaluated using scores for statistical analysis. Results Immunohistological analysis demonstrated the presence of angiogenesis in both groups, but with higher angiogenic maturation in G2 during the experimental period (p<0.05). HE staining showed connective tissue with absence of odontoblasts in all specimens. Conclusions It can be concluded that it is possible to obtain angiogenesis in mature root canals with or without the use of VEGF, although the latter tends to accelerate blood vessel formation.

Histologic Findings of a Human Immature Revascularized/Regenerated Tooth with Symptomatic Irreversible Pulpitis.

INTRODUCTION: Pulp revascularization/regeneration in immature permanent teeth with necrotic pulp and/or apical periodontitis is an effective approach for inducing root maturation. Previous histologic studies showed cementoid/osteoid tissue and/or periodontal ligament-like tissue formed within the root canals. This case report describes the histologic findings of a human symptomatic irreversible pulpitis immature permanent tooth with most of the pulp removed after a revascularization/regeneration procedure. METHODS: A human immature permanent mandibular premolar (tooth #29) was diagnosed as symptomatic irreversible pulpitis with symptomatic apical periodontitis at the emergency department. Most of the pulp was removed. The tooth was treated with revascularization/regeneration. RESULTS: At the 12-month recall, the radiographic examination revealed thickening of the root canal wall, narrowing of the root apex, and lengthening of the root. The tooth was extracted at 12 months for orthodontic treatment. The specimens were processed for histologic examination. Histologically, the apical third of the root canal was filled with newly formed dentinlike and pulplike tissue. There was a layer of flattened odontoblastlike cells lining the dentinal wall. In the midportion of the root canal, the newly formed dentinlike tissue gradually changed to cementumlike tissue. In the upper third of the root canal, there was a presence of cementocytelike cells housed in the lacunae of cementumlike tissue around the loose connective tissue. CONCLUSIONS: In the present case, regeneration of the pulplike tissue and the periodontium existed after a revascularization/regeneration procedure in an immature permanent tooth clinically diagnosed as symptomatic irreversible pulpitis.

Second-generation Platelet Concentrate (Platelet-rich Fibrin) as a Scaffold in Regenerative Endodontics: A Case Series.

INTRODUCTION: The purpose of this case series was to report the clinical and radiographic results of a pulp regenerative procedure using platelet-rich fibrin (PRF), a second-generation platelet concentrate, in immature teeth with necrotic pulps. METHODS: Root canal revascularization using PRF was performed on 4 immature teeth with necrotic pulps. After access cavity preparation, the root canals were irrigated with low concentration sodium hypochlorite solution (1.5% sodium hypochlorite [20 mL/canal, 5 minutes]) and then irrigated with saline (20 mL/canal, 5 minutes). Equal proportions (167 mg) of ciprofloxacin, metronidazole, and cefaclor were mixed and diluted to a final concentration of 1 g/mL. Finally, the canal was sealed with 3-4 mm of a temporary restorative material, and patients were dismissed for 2 to 3 weeks. At the second appointment, 9 mL of the patient's whole blood was obtained and centrifuged to prepare a PRF clot. Canals were irrigated with 17% EDTA, and a sharp spreader was inserted beyond the apex. Then, the PRF clot was placed inside the root canals, and Biodentine (Septodont, Saint-Maur, France) was placed directly over the PRF. The teeth were restored permanently with glass ionomer cement and composite resin. RESULTS: Clinical examinations revealed that all cases were asymptomatic at the recall appointments at 1, 3, 6, 12, and 18 months. Radiographs revealed resolution of the periapical lesions, further root development, and apical closure in all cases. CONCLUSIONS: On the basis of the short-term results up to 12 months, PRF clots acted as successful scaffolds for the regeneration of pulpal contents in immature teeth with necrotic pulps.

Effect of simulated pulpal blood flow rate on the rise in pulp chamber temperature during direct fabrication of exothermic provisional restorations.

AIM: To evaluate ex vivo the effect of several simulated pulpal blood flow rates on the change in pulp chamber temperature during direct fabrication of a provisional restoration using a polymethylmethacrylate (PMMA) resin. METHODOLOGY: Fifteen noncarious human premolars were prepared for complete coverage restorations. A curved needle connected to a peristaltic pump simulated the pulp blood flow. Two K-type thermocouples connected to a digital thermometer were placed in the pulp chamber, and the assembly was placed in an incubator at 37 °C. Three provisional crowns were made for each specimen using no water flow (group 1), a 1-mL min-1 flow rate (group 2) and a 0.5-mL/min-1 flow rate (group 3). The pulp chamber temperature was recorded continuously during polymerization until the temperature increase peaked and started to decrease and reached the baseline temperature (37 °C). The temperature increase was measured for the three water flow conditions. Data were analysed statistically using descriptive statistics, repeated measures one-way analysis of variance (anova) with Greenhouse-Geisser correction and Bonferroni tests. The level of significance was set at P < 0.05. RESULTS: All of the groups were associated with an increased pulp chamber temperature. Groups with flow rates at 1 and 0.5 mL min-1 had a significantly lower temperature rise when compared to the group without water flow (P < 0.001). CONCLUSIONS: Direct fabrication of provisional restorations can cause a critical increase in pulp chamber temperature. However, in the presence of simulated pulpal blood flow rates of 1 or 0.5 mL min-1 , the increase in pulp chamber temperature did not exceed the critical threshold (5.6 °C).

A scoping review of root canal revascularization: relevant aspects for clinical success and tissue formation.

The aim of this scoping study was to evaluate the survival rate and nature of tissue formed inside root canals of human immature permanent teeth with necrotic pulps (NIPT) under root canal revascularization (RCR). The search was performed in SciVerse Scopus®, PubMed/MEDLINE, Web of Science®, BIREME and in the grey literature up to November 2015. The keywords were selected using MeSH terms and DECs. Two independent reviewers scrutinized the records obtained considering specific inclusion criteria. The included studies were evaluated in accordance with a modified Arksey and O' Malley's framework. From 375 studies that were evaluated, 75 were included. A total of 367 NIPT were submitted to RCR, from which only 21 needed further endodontic treatment. The weighted mean follow-up time was 17.6 months. The data were derived mainly from case reports (69%) or small case series (15%). NaOCl [0.5-6%] was applied as the disinfecting solution in almost all studies. Triple antibiotic paste was as effective as Ca(OH)2 as on intracanal medicament. De novo tissue was cementum and poorly mineralized bone positive to bone sialoprotein (BSP) but negative to dentine sialoprotein (DSP). Failures were associated mainly with reinfection of the root canal. The majority of included studies reported a significant increase in both root length and width. However, as most of these data came from case reports, they must be interpreted with care, as most were focused on treatment successes (not failures). Therefore, well-designed randomized controlled trials comparing RCR with available apexification treatments are needed to address this gap in the literature.

Time-dependent effectiveness of the intracanal medicaments used for pulp revascularization on the dislocation resistance of MTA.

BACKGROUND: The aim of the present study was to evaluate the time-dependent effectiveness of the intracanal medicaments used in pulp revascularization on the dislocation resistance of mineral trioxide aggregate (MTA). METHODS: One hundred ninety-two extracted human maxillary incisor teeth were sectioned apically 12 mm below and coronally 2 mm above the cemento-enamel junction. Roots were enlarged to size 40 (Protaper F4). Next, Peeso reamers from #1 to #5 were used sequentially. Sodium hypochlorite (2.5 %), EDTA (17 %), and distilled water were used in final irrigation. The specimens were randomly divided into four groups (n = 48): Group 1, in which triple antibiotic paste (TAP) (ciprofloxacin + metronidazole + minocycline) was prepared and delivered into the canals using a lentulo spiral; Group 2, in which double antibiotic paste (DAP) (ciprofloxacin + metronidazole) was placed into the canals; Group 3, in which calcium hydroxide paste (CH) (calcium hydroxide + distilled water) was introduced into the roots; and Group 4 (control), in which no medicament was applied into the root canals. Then, the samples were kept in saline solution for 2, 4, and 12 weeks, after which time 16 roots were selected randomly from each group, representing the samples of each time point. After removal of the medicaments, MTA was placed into the coronal third of the roots, and the samples were incubated for 7 days. A push-out test was used to measure the dislocation resistance (DR) of MTA. The data were analyzed using a two-way ANOVA followed by Tukey's pairwise comparisons (p = 0.05). RESULTS: The time factor displayed a significant effect on the DR of MTA (p < 0.05). All medicaments resulted in significantly smaller DR values after 12 weeks compared to after 1 week (p < 0.05). A significant unfavorable effect of TAP and DAP was observed as early as 2 weeks after the application, while 2 and 4 weeks after the application of CH there was no effect on the DR of MTA. No significant differences were found between the time points in the control group (p > 0.05). CONCLUSION: The type and the intracanal duration of medicaments used for pulp revascularization should be chosen carefully to provide maximum antimicrobial effect while creating a favorable environment both for stem cell attachment and MTA adhesion.

The effect of blood contamination on dislocation resistance of different endodontic reparative materials.

This study evaluated the retention characteristics of ProRoot mineral trioxide aggregate (MTA), RetroMTA, Supra MTA, and Biodentine biomaterials used to repair furcation perforations contaminated with blood. Furcal perforations measuring 1.3 mm in diameter and 2 mm in height were created in 96 mandibular first molar teeth, which were then randomly divided into the following two groups (n = 48): contaminated (+) or non-contaminated (-) with blood. The groups were subdivided into four groups (n = 12) according to the material used (ProRoot MTA, RetroMTA, Supra MTA, and Biodentine) to seal the perforations. The samples were allowed to set for 14 days and were then subjected to push-out testing. The results were analyzed using ANOVA, and the failure modes were examined using a surgical microscope. ProRoot MTA (+/-) and RetroMTA (+/-) exhibited superior bond strength values; in addition, there were no significant differences among these groups (P > 0.05). Biodentine (+) showed intermediate values that were sometimes statistically similar to the ProRoot MTA (+/-) and RetroMTA (+/-) groups (P > 0.05) and, at other times, the Biodentine (-) and Supra MTA (+/-) groups (P > 0.05). The lowest bond strength values were shown by the Biodentine (-) and Supra MTA groups (P > 0.05). "Adhesive failure mode" was the most frequently observed type for all tested materials. Blood contamination did not affect the dislocation resistance of materials.

Effects of bleaching on laser Doppler blood-flow signals recorded from human teeth in vitro.

OBJECTIVE: To determine if bleaching a tooth affects significantly laser Doppler recordings of pulpal blood flow that are made through the treated enamel and dentine. DESIGN: Recordings of blood flow (flux) were made with a laser-Doppler flow meter from the crowns of 14, recently extracted, human premolars while diluted blood was pumped at three different rates through a cannula that was inserted into the pulp cavity with its tip in the coronal pulp chamber. The recordings of flux were made before and after bleaching the crown with 38% hydrogen peroxide for 30min. The colour changes produced by bleaching were also measured with a digital spectrophotometer in 15 teeth. The effects of bleaching on both blood flow recordings and tooth colour were studied in 11 of the teeth. RESULTS: Both before and after bleaching, there was a linear relationship between blood perfusion rate and flux. After bleaching, the flux readings increased by an average of 46%, and were significantly increased in every tooth (P<0.001, Wilcoxon Signed Rank Test). There was no significant correlation between the changes in flux and the changes in tooth colour. CONCLUSION: A laser Doppler flow meter cannot be used to determine the effect of bleaching on pulpal blood flow in intact teeth.

Clinical and histological characterization of an aggressive periodontitis case associated with unusual root canal curvatures.

The article presents the histological and clinical characteristics in a severe generalized aggressive periodontitis case associated with multiple root curvatures and the complex therapeutic approach of the severe periodontal destructions. The patient received a complex therapy, including periodontal non-surgical, regenerative and reconstructive approaches, and also endodontic and prosthetic treatments. Recall appointments were fixed at 3-month intervals. One year after the finalization of the active therapy, a hyperplasic, inflamed interdental papilla associated with a recurrent clinical attachment loss was diagnosed at the mesial aspect of the right maxillary second premolar. A biopsy was harvested for histological examination and the recurrent site was treated. The histological study revealed important modifications of the epithelial layer and of the connective tissue of the gingiva. An extremely accentuated pattern of the gingival rete ridges at the epithelial-connective tissue junction, the presence of inflammatory cells infiltrating the epithelial layer and lamina propria and the disorganization of the fascicules of collagen fibers were observed. The inflammatory infiltrate was dominated by plasma and monocytic-like cells as immunohistochemical analyses highlighted. The complex therapeutic approach led to a satisfactory aesthetic and functional outcome. The severe root curvatures may be an unusual trait in this generalized aggressive periodontitis case substantially increasing the amount and the costs of non-periodontal procedures. In this case, the cell make-up of the inflammatory infiltrate and the paucity of collagen in the infiltrated tissue portions are considered to correspond to a fully developed recurrent lesion.

Histologic examinations of teeth treated with 2 scaffolds: a pilot animal investigation.

INTRODUCTION: A growing body of evidence is building a case for the possibility of tissue regeneration within the root canal of necrotic teeth, allowing for continued root development. However, it remains unknown what type of tissue is produced after regenerative endodontics. The purpose of this study was to use blood clots and platelet-rich plasma (PRP) as scaffolds in regenerative endodontics under ideal conditions in a ferret model to examine the tissues generated within the root canals. METHODS: The pulps of 21 canine teeth from 7 young ferrets were extirpated using broaches without filing the canal walls. Bleeding was stimulated from the periapical tissues, and a blood clot was induced in the canal space to the level of the cementoenamel junction in 12 teeth. PRP was prepared and placed in the canals to the level of the cementoenamel junction in 9 teeth. The coronal access was sealed with mineral trioxide aggregate. Seven canines were not operated on and served as controls. Three months later, block sections including each canine and its surrounding tissues were removed for histologic evaluation. The tissues found in the canals of experimental teeth were compared with those in the control teeth. RESULTS: Almost all of the experimental teeth showed the presence of intracanal bonelike tissue. No evidence of dentinal wall thickening or apical narrowing was noted in the experimental teeth. CONCLUSIONS: In this experimental model, the use of either PRP or blood clots during regenerative endodontics leads to the formation of intracanal bonelike tissue without continual root maturation.

Tissue engineering in endodontics: root canal revascularization.

Root canal revascularization attempts to make necrotic tooth alive by the use of certain simple clinical protocols. Earlier apexification was the treatment of choice for treating and preserving immature permanent teeth that have lost pulp vitality. This procedure promoted the formation of apical barrier to seal the root canal of immature teeth and nonvital filling materials contained within root canal space. However with the success of root canal revascularization to regenerate the pulp dentin complex of necrotic immature tooth has made us to rethink if apexification is at the beginning of its end. The objective of this review is to discuss the new concepts of tissue engineering in endodontics and the clinical steps of root canal revascularization.

Concentrated platelet-rich plasma used in root canal revascularization: 2 case reports.

AIM: To present two case reports describing the treatment of immature teeth with necrotic pulps using concentrated platelet-rich plasma (cPRP) with 12-month clinical and radiographic follow-up. SUMMARY: Root canal revascularization was performed on immature permanent teeth clinically and radiographically diagnosed as requiring root canal treatment. Following disinfection of the canal space with triple antibiotic paste (1 : 1 : 1: ciprofloxacin, metronidazole and cefaclor), a tissue scaffold was created with cPRP prepared using 2-step centrifugation. The final restoration was completed with white mineral trioxide aggregate and composite resin. The patients were recalled for clinical and radiographic evaluations every 3 months. At the 12-month follow-up apical closure by narrowing of the apical foramen and convergence of the apical walls in the treated teeth was observed.

Risk of airway embarrassment during root canal therapy.

BACKGROUND: Root canal therapy (RCT) is a commonly performed dental procedure that has a good success rate. Complications of RCT usually are minor, but severe complications can occur. CASE DESCRIPTION: A 59-year-old Hispanic man with no history of coagulopathy started to hemorrhage profusely from the mesiolingual canal of the right mandibular first molar (tooth no. 30) during RCT. The general dentist practitioner briefly controlled the hemorrhaging by packing a gutta-percha point into the mesiolingual canal. Shortly afterward, the patient developed an expanding hematoma in the submandibular space. The authors extracted tooth no. 30, raised buccal and lingual flaps, and evacuated the hematoma. PRACTICAL IMPLICATIONS: It is possible for clinicians to encounter significant hemorrhaging and airway compromising swelling when performing root canal therapy. Clinicians must recognize and understand how to manage such complications when they occur.

Effects of enamel and dentine thickness on laser Doppler blood-flow signals recorded from the underlying pulp cavity in human teeth in vitro.

OBJECTIVE: To determine the effect of enamel and dentine thickness on laser Doppler blood-flow (LDF) signals recorded from dental pulp. DESIGN: Observations were made on 18 human premolars that had been extracted from young patients during orthodontic treatment. The apical 2/3 of the root was cut off and the remaining pulp removed. Blood flow signals were recorded from the buccal surface of the crown with a laser Doppler flow metre while dilute blood was pumped at 10 ml/min. through a cannula inserted into the pulp cavity. Recordings were made from the enamel surface and at 0.5 mm steps through the enamel and dentine. RESULTS: The blood flow signal increased significantly as the cavity depth increased and at 2.0 mm, the median flux signal was more than ten times greater than that obtained on the enamel surface. The backscattered light intensity did not change with cavity depth. CONCLUSION: When recording pulpal blood flow from a human tooth with a laser Doppler flow metre, a substantially better signal-to-noise ratio should be obtained by placing the probe on dentine in the floor of a cavity than on the enamel surface.

Regenerative endodontic treatment of permanent teeth after completion of root development: a report of 2 cases.

INTRODUCTION: Clinical regenerative endodontic treatment has been focused on immature necrotic teeth, but it should be extended to mature teeth as an alternative to conventional endodontic treatment. There have been no clinical reports to attempt to revascularize pulp in the entire root canals of mature necrotic teeth. The present report describes the treatment of mature, necrotic, permanent incisors with apical periodontitis by using regenerative endodontic therapy. METHODS: In this case report, modified regenerative endodontic procedures were used to enhance the probability of pulp revasuclarization in mature necrotic teeth. At the first appointment, the root canals were mechanically instrumented to the apices with a large apical size by using the step-back technique and irrigated copiously with antimicrobial solution. Intracanal medicaments (calcium hydroxide or ciprofloxacin) were placed in the root canals. At the following appointment, the root canals were irrigated with antimicrobial solution, and bleeding was induced into the root canals by passing hand files beyond apices. Collagen membranes were placed in the canals as a matrix against which mineral trioxide aggregate was placed. Glass ionomer was used to restore the teeth. The resolution of apical radiolucency and regression of clinical signs and symptoms were observed at recall appointments. CONCLUSIONS: The present report presents modified regenerative endodontic procedures for mature necrotic permanent teeth. Further clinical studies with a large number of cases are needed to investigate the outcome of regenerative endodontic therapy for mature necrotic teeth.

Evaluacion de tres técnlcas de irrigación de conducto radicular frente a la actividad del enterococcusfaecalis / Evaluation of three techniques of root canal irrigation activity against enterococcusfaecalis

Objetivo: El objetivo de este estudio in vitro es comparar la eficacia antibacteriana de tres técnicas de irrigacion del conducto radicular: presion positiva, presion negativa y sónica frente a una cepa de enterococcusfaecalisatcc 2012. Materiales y Metodos: Raices de premolares extraidos calibrados a 16mm de longitud apico coronal fueron contaminados con Enterococcusfaecalis ATCC 29212 por 21 días y luego distribuidos aleateoriamente en 3 grupos experimentales con 24 especimenes cada uno: grupo 1, presion positiva con agujas 27G insertadas a 4mm de la longitud de trabajo; grupo 2. Fue irrigado activando las puntas endosónicas a 3mm; grupo3, con el sistema EndoVac. El volumen de irrigantes utilizado para todos los grupos fue de 13 ml. El grupo de control negativo fue irrigado con solución salina (volumen total: 13ml). Se tomaron muestras después de la irrigación para cultivarlas, a las 24 horas se contabilizaron las unidades formadoras de colonias (UFC's). Resultados: Los tres grupos experimentales fueron más efectivos que el grupo de control negativo en la disminución de la cantidad de bacterias. Conclusiones: No se encontró diferencia estadísticamente significativa entre los tres grupos evaluados.

Introduction: The different types of bacteria found in the root canal suggest that is necessary to pursue a correct cleaning of it; thus, by means of the irrigation techniques disinfection will improve. The aim of this in vitro study is to compare the antibacterial efficacy of 3 different irrigation techniques. Methods: Roots of premolars extracted teeth calibrated to 16 mm in apex-coronal direction were contaminated with Enterococcus faecalis ATCC 29212 within 21 days and then randomly divided into 3 experimental groups of 24 specimens: group 1, positive pressure irrigation with 27G needles inserted up to 4 mm short of the working length; group 2, same as group 1, but complemented with final irrigant activation by the EndoSonic tips; and group 3, irrigation with the Endo Vac system. The irrigants used in all experimental groups were NaOCI and ethylenediaminetetraacetic acid (EDTA). The diameter preparation was constant for the groups ISO .40/.04 (RaCe). The irrigants volume was 13mL for all the groups. The control group was irrigated with saline solution (total volume, 13 mL). Samples were taken after irrigation procedures for cultivation and successively colony-forming units (CFUs) were counted after 24 hours. Results: The 3 experimental groups were more effective than the negative control group in reducing bacteria. Conclusions: There was no statistical significant difference between the 3 techniques.

[Experimental study on pulp revitalization of Beagle dog's immature permanent teeth after pulpectomy].

OBJECTIVE: To observe the process of pulp revitalization of immature permanent teeth after pulpectomy. METHODS: Thirty-two single-rooted teeth with open apices from 4 Beagle dogs aged 4 months were included in the study. The pulpal tissues of 8 front teeth with single root of each dog were removed, and a blood clot was produced to the level of the cementoenamel junction followed by a double seal of mineral trioxide aggregate and composite resin. At day 7, 14, 21 and 28, respectively after operation, the dog was sacrificed, and then longitudinal paraffin sections were made for histologic investigation. RESULTS: After 7 days, about one thirth of the pulp chamber had an ingrowth of new tissue. After 14, 21, 28 days, there were more and more new tissue in the chamber. This new tissue consisted of well-organized and well-vascularized connective tissue. Hard tissue was too observed in the root canal. In some cases, the newly generated hard tissue even deposited against the canal dentinal walls. CONCLUSIONS: The pulp of immature permanent teeth can revitalize after removal of the original pulp tissue under suitable conditions.

Pulpal blood flow recorded from human premolar teeth with a laser Doppler flow meter using either red or infrared light.

OBJECTIVE: To compare red (635 nm) and infrared (780 nm) light for recording pulpal blood flow from human premolar teeth. DESIGN: Recordings were made from 11 healthy teeth in 9 subjects (aged 16-30 years) using a laser Doppler flow meter (Periflux 4001) equipped with both red and infrared lasers. Average blood flow signals were obtained with both light sources alternately from each tooth under five conditions: intact tooth without opaque rubber dam, intact tooth with dam, after injecting local anaesthetic (3% Mepivacaine) (LA) over the apex of the tooth and cavity preparation to almost expose the pulp, after removal and replacement of the pulp, and with the root canal empty. RESULTS: With infrared light, the dam significantly decreased the mean blood flow by 80%. Injecting LA and cavity preparation had no significant effect. Removal and replacement of the pulp reduced the mean blood flow by 58%. There was no further change when the pulp was removed. With red light, the dam reduced the signal from intact teeth by 60%. Injecting LA and cavity preparation had no significant effect. The signal fell by 67% after pulp removal and replacement and did not change significantly when the pulp was removed. CONCLUSIONS: Opaque rubber dam minimises the contribution of non-pulpal tissues to the laser Doppler signal recorded from premolars. Using dam, the pulp contributed about 60% to the blood flow signal with both red and infrared light. The difference between them in this respect was not significant.

Parameters influencing increase in pulp chamber temperature with light-curing devices: curing lights and pulpal flow rates.

UNLABELLED: This laboratory study examined the effects of curing lights with different light intensities and changing flow rate on the increase in pulpal temperature during the light curing process and the rate of the subsequent decrease in temperature after the termination of light curing. The tip of a temperature sensor was positioned on the pulpal dentinal wall of the buccal side of the maxillary premolar. Metal tubes were inserted in the palatal and buccal root of the tooth, one for water inflow and the other for water outflow. The tubes were connected to a pump to control the flow rate. The water flow rate was set to 4.2 microl/minute, 28 microl/minute or 70 microl/minute. At each flow rate, the unprepared tooth was light cured from the buccal side 1 mm from the buccalsurface, using four different curing lights. The temperature data were recorded and stored on a computer every second for three minutes. The curing lights that were used were: Astralis 10 (QTH(high), Ivoclar Vivadent), Bluephase 16i (LED(conv), Ivoclar Vivadent) and two experimental LED-curing lights (LED(exp2000), LED(exp3000), Ivoclar Vivadent). The power densities were 1200 mW/cm2, 1600 mW/cm2, 2000 mW/cm2 and 3000 mW/cm2, respectively. The curing lights, LED(conv), LED(exp2000) and LED(exp3000) were activated for 60 seconds, and the QTH(high) was activated for 30 sec- onds. The maximum intrapulpal temperature (TM) and rate of temperature change at 30 seconds after turning off the light (S(30LO)) were analyzed by two-way ANOVA with a post-hoc Tukey test (p < 0.05). The influencing factors were the flow rates and curing lights. RESULTS: The T(MAX) ranged from 41.0 degrees C to 53.5 degrees C. There was a difference between the curing lights (p < 0.05), with LED(exp3000) > LED(exp2000) > LED(conv) > QTH(high). There was no difference in T(MAX) between the different flow rates (p > 0.05). Both the curing lights and flow rates affected the SE(30LO) (p < 0.05). The S(30LO) was LED(exp3000) < LED(exp2000) > LEDon, , QTH(high) (p < 0.05). The S(30LO) at 70 microl/minutes was higher than at 4.2 pd/minutes and 28 microl/minutes (p < 0.05). CLINICAL IMPLICATION: Because the increase in temperature is directly related to the light intensity and exposure time, curing devices with high power density (> 1200 mW/cm2) should only be activated for a short period of time (< 15 seconds) even in teeth without cavity preparation. The flow rate had only a negligible effect on the temperature increase.