Effect of extracorporeal shockwave therapy (ESWT) on pulpal blood flow after orthodontic treatment: a randomized clinical trial.

OBJECTIVES: The effect of non-invasive extracorporeal shockwaves on pulpal blood flow in orthodontic patients who have undergone active treatment was investigated. MATERIALS AND METHODS: Seventy-two adult patients were enrolled in the clinical trial and allocated by block randomization to a treatment or a placebo group at a 1:1 ratio. The patients were required to be otherwise healthy. Blinding was performed for the subjects and the outcome assessor. The region of interest was the mandibular incisors and canines, which were vital, unrestored, and had experienced no trauma. The active treatment group received a single shockwave treatment with 1000 impulses at 0.19-0.23 mJ/mm(2) while the placebo group was treated with a deactivated shockwave applicator but acoustic sham. Pulpal blood flow was evaluated four times over a period of 6 months starting from the day of bracket removal, using a laser Doppler device. RESULTS: Thirty patients were evaluated in each group. Orthodontic patients who have undergone active treatment tend to have high levels of pulpal blood flow which decrease over a period of 6 months. Pulpal blood flow did not differ significantly over 6 months between the placebo and treatment group. Shockwave treatment was associated with no significant effect in respect of tooth type, age, sex, or mean blood pressure, and had no unintended pernicious effects. CONCLUSIONS: Extracorporeal shockwaves had no statistically significant effect on pulpal blood flow. Multiple applications of ESWT in a pathological setup may be needed in future studies to demonstrate significant differences. CLINICAL RELEVANCE: The absence of any adverse effects justifies further principal investigations of the use of shockwave treatment in the oral cavity.

Oxygen saturation and perfusion index from pulse oximetry in adult volunteers with viable incisors.

OBJECTIVE: Evaluation of pulp vitality is an important diagnostic procedure in dentistry. Conventional techniques for measurement of pulp vitality, including thermal stimulation, electrical stimulation, or direct dentin stimulation, are frequently associated with false positive or false negative results. Recently, oxygen saturation from pulse oximetry has been utilized in the evaluation of pulp vitality. Perfusion index (PI) data calculated from photoplethysmography have been widely used to evaluate peripheral perfusion. The combination of oxygen saturation and PI may aid in the accurate measurement of pulp vitality. We aimed to investigate the baseline values of oxygen saturation and PI using pulse oximetry in adult volunteers. MATERIAL AND METHODS: Fifteen adult volunteers with viable incisors were tested. To measure PI, a fabricated oxygen sensor was applied to an incisor without a pulp lesion while oxygen saturation was simultaneously measured in the finger. Oxygen saturation and PI were continuously measured with customized software. The normal reference values of oxygen saturation and PI were obtained by analyzing the recorded data. RESULTS: Pulse oximetry showed relatively stable, objective, and accurate oxygen saturation results. The tooth oxygen saturation ranged from 97% to 100%. The PI ranged from 0.3% to 0.5%, and PI and oxygen saturation showed relatively consistent values across subjects. CONCLUSIONS: Although there are some limitations to our study, these results may prove useful for detecting teeth with impaired vitality and non-invasively differentiating between necrotic and vital pulp.

Long-term follow up of revascularization using platelet-rich fibrin.

INTRODUCTION: Trauma is one of the primary causes of tooth loss and pulpal injury in adolescents and children. Prior to regenerative endodontics, treatment of necrotic, immature teeth with open apices was limited to long-term calcium hydroxide (Ca(OH)2 ) apexification and subsequent root canal therapy or extraction. Through revascularization, retention of these teeth can be achieved and the elimination of patient symptoms and the radiographic appearance of continued root development were obtained. CASE REVIEW: This report illustrates a revascularization protocol through a case where platelet-rich fibrin (PRF) was utilized as an autologous scaffold for traumatized, necrotic, immature teeth with incomplete root development. Through consistent follow-up reports, comprising of both clinical examination and radiographs, marked improvement in the condition of the traumatized tooth was noted. DISCUSSION: This case demonstrates the feasibility of utilizing PRF as an effective treatment protocol for traumatized teeth in lieu of traditional treatment protocols, such as long-term calcium hydroxide (Ca(OH)2 ) apexification or extraction. The choice of utilizing PRF, as opposed to other platelet concentrates, such as platelet-rich plasma (PRP) or a blood clot, lies in PRF's ability to allow for a slow, long-term release of autologous growth factors.

Measurement of pulp blood flow rates in maxillary anterior teeth using ultrasound Doppler flowmetry.

AIM: To measure pulp blood flow rates of clinically normal maxillary anterior teeth of healthy adults using ultrasound Doppler flowmetry (UDF). METHODOLOGY: A total of 359 anterior teeth from 63 patients (mean age, 29.8 years; range, 22-52 years; 26 females and 36 males) were included. The data were collected according to tooth type (three groups: central incisors, lateral incisors and canines). An MM-D-K (Minimax, Moscow, Russia) ultrasound Doppler imaging instrument was used to measure pulp blood flow. Differences between the tooth types were analysed with one-way anova and a Bonferroni correction at the 95% confidence level. RESULTS: The mean average linear velocities during the systolic period (Vams) of the central incisors, lateral incisors and canines were 0.58, 0.58 and 0.52 cm s(-1) , respectively. There were no significant differences in the mean Vams between the tooth types (P > 0.05). CONCLUSIONS: Within the limitations of this study, the pulp blood velocities of clinically normal, maxillary anterior teeth of healthy adults were between 0.5 and 0.6 cm s(-1) . There were no significant differences in mean blood flow rates between maxillary central incisors, lateral incisors and canines.

Comparative evaluation of pulpal blood flow during incisor intrusion.

AIM: The aim of the present study was to evaluate and compare changes in pulpal blood flow (PBF) as a result of maxillary incisor intrusion achieved by one of two methods (utility arches or mini-implants). MATERIALS AND METHODS: Thirty subjects were divided into three groups, the first of which underwent maxillary incisor intrusion using utility arches (UA) and a second group, intrusion via mini-implants (MI). The third group acted as a control. An intrusive force of 100 g was applied to the upper incisors in the treatment groups, whereas no force was applied to the anterior teeth in the control group. A laser Doppler flowmeter (LDF) was used to measure PBF at baseline (T0) and during incisor intrusion at 24 hours (T1), three days (T2), seven days (T3) and three weeks (T4). Statistical changes in PBF were assessed by the Wilcoxon Signed Rank and Mann-Whitney U tests, with significance set at p < 0.05. RESULTS: The mean PBF in the UA and MI groups decreased significantly from T0 to T1 (p < 0.001), slightly increased at T2 and continued to increase gradually at T3. PBF attained levels similar to those measured prior to intrusion at T4. No significant changes in PBF were observed in the control group over the course of the study. The only statistically significant difference between the UA and MI groups were at T1 and T2, at which time the MI group had lower PBF values (p < 0.001). CONCLUSIONS: Despite slight regressive changes in pulpal tissue observed over the short-term, PBF values tended to return to initial levels within three weeks, indicating that changes observed in PBF with the UA and MI intrusion methods are reversible. Although the changes in PBF could not be directly related to the method of intrusion employed, in general, a more severe drop in PBF was observed in the MI group during the first three days of intrusion.

Preliminary study of video imaging of blood vessels in tissues lining the gingival sulcus in periodontally healthy individuals.

BACKGROUND AND OBJECTIVE: The aim of this study was to obtain in vivo images of the microcirculation in tissues lining the gingival crevice in periodontally healthy volunteers and to assess the repeatability of the parameters measured. MATERIAL AND METHODS: Video microscopy images of the microcirculation of tissues lining the gingival crevice were obtained from 20 periodontally healthy volunteers. Images were obtained with a single 1 mm diameter 1 pitch gradient index lens with a high numerical aperture and with a plain glass lens and illumination with a green 525 nm light-emitting diode and recorded using a video microscope. RESULTS: The morphological features of the vessels (including vessel diameter, vessel density, loops, branches, dilated vessels) were similar to those described previously in other mammals. The Kappa values for the assessment of morphology of the vessels using the gradient index lens range from 0.83 for branching to 0.91 for dilated and using the glass lens 0.47 for branching and 0.38 for dilated. CONCLUSIONS: This novel system allowed for a consistent and repeatable assessment of the gingival microvasculature. However, there was some evidence of possible pressure artefacts in those cases where the measurements of separation between vessels exceeded 150 µm.

Changes in maxillary incisor dental pulp blood flow during intrusion by mini-implants.

AIM: The aim of this clinical study was to identify changes in pulpal blood flow (PBF) in human central incisors resulting from short- and long-term intrusive orthodontic forces from mini-implants. MATERIALS AND METHODS: A total of 40 sound upper central and lateral incisors in 20 patients scheduled for intrusion for orthodontic reasons were divided into two groups. From each group, 20 teeth were subjected to intrusive force from mini-implants (Group 1 = Light Force: 40 g; Group 2 = Heavy Force: 120 g), whereas the remaining 20 contralateral teeth were not subjected to forces from mini-implants and served as controls. Laser-Doppler flowmetry (LDF) measurements were recorded at baseline and at 3 days and 3 weeks following intrusion. RESULTS: PBF decreased significantly at 3 days (Light Force Group: 7.72 ± 0.50; Heavy Force Group: 7.72 ± 0.52) and then increased towards baseline at 3 weeks (Light Force Group: 10.37 ± 0.58; Heavy Force Group: 10.31 ± 0.45) following intrusion. CONCLUSIONS: In other words, despite slight regressive changes in pulpal tissue in the short-term, PBF improved after 3 weeks following intrusion by mini-implants, indicating that the changes observed in PBF is reversible, even following radical incisor intrusion.

Nerve damage assessment following implant placement in human cadaver jaws: an ex vivo comparative study.

The present study compared the use of cone beam computerized tomography (CBCT) images and intra-oral radiographs in the placement of final implant drills in terms of nerve damage to cadaver mandibles. Twelve cadaver hemimandibles obtained from 6 cadavers were used. Right hemimandibles were imaged using peri-apical radiography and left hemimandibles using CBCT, and the images obtained were used in treatment planning for the placement of implant drills (22 for each modality, for a total of 44 final drills). Specimens were dissected, and the distances between the apex of the final implant drill and the inferior alveolar neurovascular bundle and incisive nerve were measured using a digital calliper. Nerves were assessed as damaged or not damaged, and the Chi-square test was used to compare nerve damage between modalities (P < 0.05). Nerve damage occurred with 7 final drills placed based on peri-apical radiography (31.8%) and 1 final drill placed using CBCT images (4.5%). The difference in nerve damage between imaging modalities was statistically significant (P = 0.023), with CBCT outperforming intraoral film in the placement of final implant drills ex vivo. In order to prevent nerve damage, CBCT is recommended as the principal imaging modality for pre-implant assessment.

Revascularization in an immature necrotic permanent incisor after severe intrusive luxation injury: a case report.

BACKGROUND: Pulp necrosis as a result of trauma is common in almost all intruded teeth, and the ideal treatment method for intruded immature and necrotic teeth has not yet been determined. Therefore, the aim of this report was to present a case of pulp revascularisation in a severely intruded immature maxillary right incisor. CASE REPORT: After clinical and radiographic examination, the incisor was defined as necrotic. Revascularisation therapy was performed over multiple appointments. After 21 months of recall appointments, healing of the periapical area and apical closure were seen to be complete. However, at the 27-month appointment, the vitality tests were negative and revascularisation of the right incisor, which had intrusion injuries, had not occurred. The tooth underwent root canal treatment. Finally, the tooth spontaneously erupted into the vestibule and was repositioned with orthodontic appliances. CONCLUSION: Although revascularisation can promote continued root development and root dentin apposition, long-term root canal treatment may be required due to treatment results with periapical inflammation in intruded teeth with open apices.

Effect of tooth isolation on laser Doppler readings.

AIM: To measure differences between single (STI) and multiple teeth isolation (MTI), pulpal blood flow (PBF) was assessed using laser Doppler flowmetry (LDF). METHODOLOGY: Pulpal blood flow of twenty maxillary incisors with no restorations or abnormal responses to sensitivity tests in healthy patients between 24 and 42 years of age was measured in perfusion units (PU). STI (isolation of only the tooth undergoing blood flow assessment) and MTI (isolation including the maxillary right to the maxillary left canine) recordings were taken with regular blood flow (RBF) and with local infiltration (LI) with vasoconstrictor. anova and Tukey HSD tests were used for statistical analysis. RESULTS: The mean PBF with regular blood flow conditions was significantly different between single tooth isolation [5.53 PU (SD ± 2.98)] and multiple tooth isolation [2.85 PU (SD ± 2.13)] (P < 0.01). When local anaesthesia was administered (LI), the PBF was significantly different between single tooth isolation [2.95 PU (SD ± 2.48)] and multiple tooth isolation [1.32 PU (SD ± 0.70)] (P < 0.05). Significant differences in PBF also existed between single tooth isolation under regular blood flow conditions and with local anaesthesia (P < 0.01), between single tooth isolation under regular blood flow conditions and multiple tooth isolation with local anaesthesia (P < 0.01), and between multiple tooth isolation under regular blood flow conditions and with local anaesthesia (P < 0.05). CONCLUSIONS: Pulpal blood flow measurements could be obtained with multiple teeth isolation and single tooth isolation. Multiple teeth isolation blocked signal contamination better. Single tooth isolation provided significantly different readings for regular blood flow and LI conditions and may therefore provide an option for pulpal blood flow assessment with LDF.

Doppler ultrasound to detect pulpal blood flow changes during local anaesthesia.

AIM: To examine whether Doppler ultrasound can detect changes in pulpal blood flow after infiltration anaesthesia. METHODOLOGY: Changes in pulpal blood flow in maxillary central incisor teeth of 18 patients (mean age 26.7 years, 13 men, five women) after infiltration anaesthesia were examined. Before infiltration anaesthesia, the pulpal blood flow was measured using Doppler ultrasound. A local anaesthetic solution containing 2% lidocaine with 1:80,000 epinephrine was injected into the submucosa above the experimental tooth. The Doppler ultrasound test was carried out at 5, 10, 20, 30, 45 and 60 min after infiltration. The parameters were Vas (maximum linear velocity, cm s(-1) ), Vam (average linear velocity, cm s(-1) ) and Vakd (minimum linear velocity, cm s(-1) ), which are indicators of the level of blood flow. The mixed procedure at the 95% confidence interval was used to examine the changes in pulpal blood flow after the injection. RESULTS: The linear velocity profiles (Vas, Vam, and Vakd) decreased sharply 5 min after anaesthesia and then reduced continuously for 30 min. The maximum degree of blood flow reduction in Vas, Vam and Vakd was 58%, 83% and 82%, respectively. After 30 min, the linear velocities increased gradually. The Vam returned to the pre-anaesthesia state at 60 minutes but the Vas and Vakd did not recover completely. CONCLUSIONS: Doppler ultrasound can detect changes in pulpal blood flow after infiltration anaesthesia. In the future, Doppler ultrasound can be used as a tool for measuring pulpal blood flow.

Monitoring dental pulp sensibility and blood flow in patients receiving mandibular orthognathic surgery.

AIM: To investigate the effect of orthognathic surgery, in particular genioplasty, on pulp sensibility and pulp blood flow (PBF). METHODOLOGY: Pulp blood flow monitoring and CO(2) pulp sensibility testing were performed on 101 mandibular anterior teeth from 17 subjects who received mandibular bilateral sagittal split osteotomy (BSSO) with or without genioplasty and other maxillary surgical procedures combined with orthodontic treatment. A laser Doppler flowmeter was used to monitor PBF using customized acrylic splints for each subject. Preoperative baseline scores were recorded from up to 1 week preoperatively, and subsequently monitored for up to 18-28 weeks postoperatively. The data were analysed by RMANOVA and pairwise comparisons. Statistical significance was defined as P < 0.05. RESULTS: The average PBF in subjects who received genioplasty was not significantly different to those who received no genioplasty (F = 0.076, P = 0.784). In both groups, PBF decreased significantly postoperatively (F = 23.323, P = 0.000) and remained significantly lower (P = 0.000) than preoperative values at all times. PBF decreased markedly for 1-2 weeks postoperatively in patients who received genioplasty. However, there were no statistical differences between the PBF values at any time postoperatively for either group (P > 0.05). All teeth in both groups responded to CO(2) preoperatively. The average number of teeth that responded to CO(2) postoperatively in the genioplasty group was lower without significant difference when compared to the group without genioplasty (binomial distribution F = 2.63, P = 0.1256, normal distribution F = 2.98, P = 0.1048). At each progressive period after 1-2 weeks following surgery, the number of teeth responding to CO(2) increased significantly (P < 0.001) in both groups. At the end of the study, in the genioplasty group 81.1% of teeth responded to CO(2) compared to all teeth in the group without genioplasty. CONCLUSION: Pulp blood flow decreased and remained significantly lower than preoperative values in mandibular anterior teeth postoperatively with or without genioplasty. At no time was the absence of PBF recorded. The number of teeth that responded to CO(2) decreased markedly postoperatively but recovered significantly over time. All teeth regained sensibility in the group without genioplasty at the end of the study. There were neither common trends nor coincidence in the recovery of PBF and pulp sensibility.

Revascularization of immature permanent incisors after severe extrusive luxation injury.

Pulp necrosis is an uncommon sequel to extrusive luxation in immature teeth with incomplete apical closure. In this report, we describe the management of severely extruded immature maxillary incisors and the outcome of revascularization to treat subsequent pulp necrosis. An 8.5-Year-old boy with severe dentoalveolar trauma to the anterior maxillary region as a result of a fall was provided emergency treatment consisting of reduction of the dislodged labial cortical bone and repositioning of the central incisors, which had suffered extrusive luxation. When he presented with spontaneous pain involving the traumatized incisors a week later, the teeth were treated via a revascularization protocol using sodium hypochlorite irrigation followed by 3 weeks of intracanal calcium hydroxide, then a coronal seal of mineral trioxide aggregate and resin composite. Complete periradicular healing was observed after 3 Months, followed by progressive thickening of the root walls and apical closure. Follow-up observations confirmed the efficacy of the regenerative treatment as a viable alternative to conventional apexification in endodontically involved, traumatized immature teeth.

Variations of vascular distribution in the mandibular anterior lingual region: a high risk of vascular injury during implant surgery.

PURPOSE: To clarify variations of vascular distribution around the mandibular anterior tooth lingual region, an area in which vascular injuries have often been reported during dental implant surgery. The reasons for such injuries in this region are discussed from an anatomical perspective. MATERIALS AND METHODS: Anatomical dissections were performed on 100 sides of 50 cadavers used for anatomy education. Ten sides of 5 cadavers were injected intravascularly with methyl methacrylate, and penetration of the mandible was closely evaluated. RESULTS: In the mandibular anterior tooth lingual region, both the sublingual and submental arteries showed various distribution patterns. Distal branches basically penetrated the bone. CONCLUSIONS: In the mandibular anterior tooth lingual region, the sublingual and submental arteries traveled from the vicinity of the mylohyoid muscle attachment along the bone surface in an anterosuperior direction. Many of these blood vessels penetrated the alveolar mucosa in the anterior tooth region, and many distal branches of the vessels also finally penetrated the bone. This seems to explain why many vascular injuries are encountered around the mandibular anterior tooth lingual region during implant surgery.

Comparison of the reliability of laser Doppler flowmetry, pulse oximetry and electric pulp tester in assessing the pulp vitality of human teeth.

This study was designed to evaluate and compare the reliability of laser Doppler flowmetry (LDF), pulse oximetry (PO) and electric pulp tester (EPT) for assessing the pulpal status as a vitality test method by calculating their sensitivity, specificity and predictive values. Data were collected from 59 pairs of maxillary anterior teeth (38 pairs of central, 21 pairs of lateral incisors) in 51 patients (range 12-18years, mean age 14·6±1·73years, 28 women, 23 men). The teeth with complete endodontic fillings constituted the study group, and the healthy, contralateral teeth of the same patients were constituted the control group. The calculated sensitivity was 0·915 for the EPT and 0·813 for the PO. And the specificity of EPT was 0·881 and PO was 0·949. The difference between the LDF values obtained from the study, and control group was statistically significant (P=0·0001). The findings of this study indicated that LDF can reliably discriminate the vitality of the teeth with a sensitivity and specificity of 1·0 for this sample. Laser Doppler flowmetry was found to be a more reliable and effective method than PO and EPT of assessing the pulpal status of human teeth.

Assessment of pulp blood flow in primary and permanent teeth using pulse oximetry.

Pulse oximetry (PO) is a well-accepted non-invasive method for assessing vascular health, based on oxygen saturation (SaO(2) ) measurements. The objectives of this study were to design and build a custom-made PO dental sensor holder, to evaluate the effectiveness of PO in determining pulp blood flow in primary and permanent teeth, and to compare the SaO(2) levels obtained in teeth and on the little finger of patients. The PO sensor adapted to the custom-made sensor holder is termed as a device to position and hold the PO sensor. This study evaluated SaO(2) readings obtained in the pulp of 123 teeth of 84 children aged 4-13years. The teeth were divided into three groups: group I - primary teeth: 23 central incisors and 28 canines; group II - permanent teeth: 25 central incisors and 28 canines; and group III - endodontically treated teeth (control): 12 permanent central incisors and seven primary central incisors. The pulp blood flow and SaO(2) were measured and were compared with readings of the patient's finger. Data were analyzed by paired t-tests and Pearson's analysis method. The PO was able to identify all the clinically normal pulps contained in the sample, and all the endodontically treated teeth (controls) showed no response. The mean SaO(2) values were 85.27% in the teeth and 92.85% in the fingers. In conclusion, PO readings were effective in determining pulp blood flow in primary and permanent teeth. However, there was no correlation between the SaO(2) values in the fingers and in the teeth of the patients (P<0.05).

Revascularization of an immature permanent tooth with periradicular abscess after luxation.

An immature permanent mandibular central incisor with periapical involvement in a 7-year-old boy was treated to promote revascularization. The tooth suffered from acute apical periodontitis after periodontal treatment by a general practitioner. An access cavity was prepared in the tooth and the cavity was left open until the next visit to achieve drainage through the canal. The root canal was not mechanically cleaned during the treatment period, but was irrigated with hydrogen peroxide and sodium hypochlorite. Calcium hydroxide compound was used for disinfection. At the fifth visit vital tissue appeared in the canal near the apical region, and calcium hydroxide compound was placed in contact with the soft tissue in the root canal. The access cavity was sealed with glass-ionomer cement followed by an adhesive composite resin filling. Radiographic examination 30 months after the initial treatment confirmed closure of the apex and thickening of the root wall. The case was observed for up to 13 years and root development was confirmed.

Effect of simulated pulpal microcirculation on intrapulpal temperature changes following application of heat on tooth surfaces.

AIM: To evaluate ex vivo whether a simulated pulpal microcirculation inside a pulp chamber influenced intrapulpal temperature rise following application of heat on tooth surfaces. METHODOLOGY: An ex vivo model that allowed the circulation of 37 degrees C warm water inside the pulp chamber of an extracted human tooth was designed. The experimental model resembled pulpal microcirculation. After application of specific thermal stimuli for 30 s to the external surface of 15 maxillary central incisors, lateral incisors and canines, temperature changes were measured in the pulp chamber. The Greenhouse-Geisser and Bonferroni tests were used for analysis of the data. The level of significance was set at 0.05. RESULTS: Significant differences were found in all three groups of teeth between temperature measurements with or without intrapulpal water flow. Additionally, temperature changes resulting from the application of different stimuli to the group of lateral incisors were significantly greater compared with the other groups of teeth (P < 0.05). CONCLUSIONS: The importance of the cooling effect of simulated pulp microcirculation in the thermal behaviour of the dentine was established. Thickness of tooth tissue influenced significantly pulp temperature rise ex vivo.

Case report: pulp revascularization of a necrotic, infected, immature, permanent tooth.

The purpose of this report is to present the case of a patient wherein revascularization of the necrotic infected pulp space of an immature permanent maxillary central incisor tooth was induced in vivo by stimulation of a blood clot from the periapical tissues into the canal space. This was achieved after disinfecting the canal space with a topical antibiotic paste followed by inducing a blood clot scaffold from the periapical tissues. This treatment approach offers great potential to avoid the need for traditional apexification with calcium hydroxide or the need to achieve an artificial apical barrier with mineral trioxide aggregate. Furthermore, this treatment approach can help rescue infected immature teeth by physiologically strengthening the root walls.

Regenerative Endodontic Procedures Posttrauma: Immunohistologic Analysis of a Retrospective Series of Failed Cases.

INTRODUCTION: Regenerative endodontic procedures (REP) are a novel treatment modality to restore the function of necrotic pulp tissue via stimulation or transplantation of stem cells into the root canal. This study aimed to investigate the immunohistologic outcome of 3 extracted teeth because of sequelae of trauma and unsatisfactory REP outcomes. METHODS: Three immature permanent maxillary central incisors of 3 female patients (6-9 years) were extracted 5.5-22 months after REP. Additionally, 1 sound permanent immature central maxillary incisor of 1 of the included patients was extracted for orthodontic reasons. The teeth were immunohistologically stained with Masson's trichrome, neurofilament (NF), pan cytokeratin, dentin sialophosphoprotein, and Gram+/-. RESULTS: The REP-teeth presented intracanalar vascularized connective/mineralized reparative tissue (RT), which was less organized than the pulp tissue of the sound tooth. Moderate to considerable calcification was observed below the Portland cement used during REP. In 1 case, the RT was NF+; in the 2 other cases, the periodontal ligament and apical granuloma/papilla were NF+. All teeth were Gram+/- negative; nevertheless, inflammatory cells were present in 2 cases. The pan cytokeratin and dentin sialophosphoprotein stainings were not specific enough for 2 cases. CONCLUSIONS: This immunohistologic study of failed REP cases resulted in bacteria-free intracanalar RT and biomaterial-induced calcification. Nevertheless, the presence of inflammatory cells revealed a persistent inflammation. Hence, the clinical and radiographic signs were decisive for tooth survival and multidisciplinary outcome determination.