Ion Channels Involved in Tooth Pain.

The tooth has an unusual sensory system that converts external stimuli predominantly into pain, yet its sensory afferents in teeth demonstrate cytochemical properties of non-nociceptive neurons. This review summarizes the recent knowledge underlying this paradoxical nociception, with a focus on the ion channels involved in tooth pain. The expression of temperature-sensitive ion channels has been extensively investigated because thermal stimulation often evokes tooth pain. However, temperature-sensitive ion channels cannot explain the sudden intense tooth pain evoked by innocuous temperatures or light air puffs, leading to the hydrodynamic theory emphasizing the microfluidic movement within the dentinal tubules for detection by mechanosensitive ion channels. Several mechanosensitive ion channels expressed in dental sensory systems have been suggested as key players in the hydrodynamic theory, and TRPM7, which is abundant in the odontoblasts, and recently discovered PIEZO receptors are promising candidates. Several ligand-gated ion channels and voltage-gated ion channels expressed in dental primary afferent neurons have been discussed in relation to their potential contribution to tooth pain. In addition, in recent years, there has been growing interest in the potential sensory role of odontoblasts; thus, the expression of ion channels in odontoblasts and their potential relation to tooth pain is also reviewed.

Finite element analysis of the dental pulp under orthodontic forces.

INTRODUCTION: To evaluate the stress at the apical third of the pulp and neurovascular bundle (NVB) during 5 types of orthodontic movement at different levels of bone loss. Furthermore, correlations among bone loss, orthodontic appliances, and stress increase were assessed. METHODS: Based on cone-beam computed tomography datasets, 10 models of the mandibular second premolar were created. Each of these models was subjected to a gradual horizontal bone loss simulation (0-8 mm). Orthodontic forces of 20 g, 60 g, and 120 g were applied during the finite element analysis (FEA). For each bone loss level, stress values were evaluated with the use of Abaqus at the apical third of the pulp and the NVB. RESULTS: The stress manifested at the apical third of the pulp was smaller than that at the NVB. The highest apical NVB stress was found for rotation (0.000546 N/mm2 for 8 mm bone loss) whereas the lowest stress resulted after translational movements (2.35E-04 MPa for 8 mm bone loss). The FEA showed that Proffit's indicated orthodontic forces did not significantly disturb the pulpal blood flow and damage the apical NVB. Up to a doubling of the NVB stress, bone loss correlated with the force reduction to obtain similar stress levels compared with teeth with no bone loss. CONCLUSIONS: The present findings indicate that the stress manifested at the apical third of the pulp is smaller than that at NVB. Rotational movements induce the highest stress and translational forces develop the lowest stress related to the physiologic capillary blood pressure. Furthermore, in situations with reduced periodontium, lower forces are needed to reach the maximum tolerable stress compared with teeth with intact periodontium.

Role of medullary astroglial glutamine synthesis in tooth pulp hypersensitivity associated with frequent masseter muscle contraction.

Background The mechanisms underlying tooth pulp hypersensitivity associated with masseter muscle hyperalgesia remain largely underinvestigated. In the present study, we aimed to determine whether masseter muscle contraction induced by daily electrical stimulation influences the mechanical head-withdrawal threshold and genioglossus electromyography activity caused by the application of capsaicin to the upper first molar tooth pulp. We further investigated whether astroglial glutamine synthesis is involved in first molar tooth pulp hypersensitivity associated with masseter muscle contraction. Methods The first molar tooth pulp was treated with capsaicin or vehicle in masseter muscle contraction or sham rats, following which the astroglial glutamine synthetase inhibitor methionine sulfoximine or Phosphate buffered saline (PBS) was applied. Astroglial activation was assessed via immunohistochemistry. Results The mechanical head-withdrawal threshold of the ipsilateral masseter muscle was significantly decreased in masseter muscle contraction rats than in sham rats. Genioglossus electromyography activity was significantly higher in masseter muscle contraction rats than sham rats. Glial fibrillary acidic protein-immunoreactive cell density was significantly higher in masseter muscle contraction rats than in sham rats. Administration of methionine sulfoximine induced no significant changes in the density of glial fibrillary acidic protein-immunoreactive cells relative to PBS treatment. However, mechanical head-withdrawal threshold was significantly higher in masseter muscle contraction rats than PBS-treated rats after methionine sulfoximine administration. Genioglossus electromyography activity following first molar tooth pulp capsaicin treatment was significantly lower in methionine sulfoximine-treated rats than in PBS-treated rats. In the ipsilateral region, the total number of phosphorylated extracellular signal-regulated protein kinase immunoreactive cells in the medullary dorsal horn was significantly smaller upon first molar tooth pulp capsaicin application in methionine sulfoximine-treated rats than in PBS-treated rats. Conclusions Our results suggest that masseter muscle contraction induces astroglial activation, and that this activation spreads from caudal to the obex in the medullary dorsal horn, resulting in enhanced neuronal excitability associated with astroglial glutamine synthesis in medullary dorsal horn neurons receiving inputs from the tooth pulp. These findings provide significant insight into the mechanisms underlying tooth pulp hypersensitivity associated with masseter muscle contraction.

Dental properties, ultrastructure, and pulp cells associated with a novel DSPP mutation.

OBJECTIVE: To investigate physical characteristics and behaviours of dental pulp cells of teeth isolated from a dentinogenesis imperfecta (DGI) patient with a novel dentin sialophosphoprotein (DSPP) mutation. SUBJECTS AND METHODS: Whole exome and Sanger sequencing were employed to identify mutations. Physical characteristics of the teeth were examined. Pulp cells' behaviours including cell proliferation, colony-forming unit, osteogenic differentiation, pluripotent markers, and mesenchymal stem cell markers were investigated. RESULTS: The proband had opalescent brown primary teeth with extensive loss of enamel. Mutation analysis revealed a novel heterozygous 4-bp deletion, c.1915_1918delAAGT (p.K639QfsX674), in exon 5 of the DSPP associated with DGI. Analysis of the extracted primary incisor demonstrated a decrease in brightness but an increase in yellow and red chroma. The dentin showed reduced mineral density. The dentinal tubules were present in the predentin, but progressively collapsed in the dentin. The pulp cells exhibited markedly reduced CD105 expression, decreased cell proliferation, and smaller colony-forming units. CONCLUSIONS: We identified a novel mutation in the DSPP gene which disturbed dentin characteristics and pulp cells' behaviours. Our study expands the mutation spectrum and understanding of pathologic dentin phenotypes related to the frameshift deletion in the dentin phosphoprotein (DPP) region of the DSPP gene.

Expression of factors involved in dental pulp physiopathological processes by nemotic human pulpal fibroblasts.

AIM: To investigate in human dental pulp fibroblasts (HDPF) the expression of factors involved in dental pulp physiopathological processes and in an experimental model of cell activation called nemosis, and to compare the behaviour of pulp cell activation with sound lung fibroblast MRC5, employed as a reference model for nemosis. METHODOLOGY: Nemotic response was induced in three-dimensional cultures of HDPF and lung fibroblasts. The expressions of molecules involved in physiological (alkaline phosphatase, type I collagen) and in inflammatory processes (IL-6, CXCL8, CCL20, COX-2) were studied using real-time PCR. Concentrations of IL-6 and CXCL8 were analysed during 4 days with ELISA. Nonparametric tests were used to determine statistical differences between groups. RESULTS: A significant decrease (P < 0.001) in type I collagen and alkaline phosphatase was observed in MRC5 and HDPF nemotic responses. Although the amounts of mRNA differed between these cell types, there was an increase in CCL20, CXCL8 and COX-2 expression (P < 0.001). Unlike HDPF, MRC5 spheroids displayed significant amounts of IL-6 concentrations and mRNA expression. Notably, increased concentrations of CXCL8 were recorded in all three-dimensional cultures compared with monolayers as a function of time (P < 0.05). CONCLUSION: Although the nemotic responses observed were not identical in the pulpal and lung fibroblasts, similarities occurred in the expression of chemokines and cyclooxygenase-2. Nemotic reactions and inflammatory processes in pulp diseases share similarities in terms of the expression of factors. Thus, this in vitro model could constitute a powerful tool to study intercellular relations within the dental pulp and to develop new local treatments to counteract the inflammatory reaction that occurs during pulpitis.

[The efficacy of electroodontodiagnosis by means of various types of current]. / Éffektivnost' élektroodontodiagnostiki s pomoshch'iu razlichnykh vidov toka.

THE PURPOSE OF THE STUDY: determination of the optimal parameters of the action of various types of current, which have the most pronounced irritating effect on the receptor apparatus of the tooth pulp. The study involved 102 volunteers aged 19 to 72 years (53 females and 49 males). The study was conducted on 217 teeth: 86 molars, 25 premolars, 19 canines and 98 incisors. 137 (63%) teeth were intact, in 48 (22%) teeth caries were found, in 32 (15%) teeth there was pulpitis or teeth were depulpated. Electroexcitability of the teeth was determined with the help of various types of electric current: an impulse variable, an impulse constant and a sinusoidal variable. The optimal current for carrying out an electroodontodiagnosis proved to be sinusoidal variable current with a frequency of 50 Hz. This current does not cause polarization of tissues, it is easy to dose, it causes a clear, but not painful sensation, gives the smallest spread of the indicators during repeated studies. The obtained results allowed formulating requirements for electroodontodiagnosis devices.

Predicting pre- and postoperative pain of endodontic origin in a southern Brazilian subpopulation: an electronic database study.

AIM: To determine the prevalence of preoperative endodontic pain (PREP) and the incidence of postoperative endodontic pain (POEP), identifying the predictors of PREP and POEP in a southern Brazilian subpopulation, using clinical data from an electronic chart database (ECD). METHODOLOGY: This retrospective observational study included 563 consecutive individuals presenting for root canal treatment (RCT). Patients were treated by undergraduate and graduate students, following standard RCT protocols. Demographic, medical and dental variables were extracted from a pre-structured and standardized ECD. The main outcomes PREP and incident POEP were collected through a 0-10 numeric rating scale, dichotomized as none/mild (<4) or moderate/severe (≥4) pain. Predictive models calculating the prevalence ratios (PR) of PREP and the relative risks (RR) of incident POEP were carried out with Poisson regression analysis, estimating the relationship between clinical factors, PREP and incident POEP. RESULTS: Mean age at baseline was 49.2 ± 17.1 years, with 68.4% women. The prevalence and incidence of moderate/severe PREP and POEP were 44.4% and 3.8%, respectively. RCT intervention significantly reduced PREP (P < 0.001). Multivariate analysis revealed that group of teeth, location (mandibular teeth), pulpitis, necrotic pulp, preoperative swelling and periapical radiolucency were independently associated with moderate/severe PREP, whilst age ≥60 years and root canal retreatments were independent protective factors to PREP (P < 0.05). No demographic, medical or dental variables were associated with POEP, although molar teeth (RR = 4.23, 95%CI = 0.93-19.2, P = 0.056) had a borderline nonsignificant association. CONCLUSIONS: Moderate/severe PREP was independently associated with age, group of teeth, location, preoperative swelling, retreatments and pulp and periapical status. No demographic, medical or dental variable predicted moderate/severe POEP following RCT amongst this subpopulation.

Age-related morphological, histological and functional changes in teeth.

Throughout lifetime, the teeth are continuously exposed to numerous chemical and physical impacts, which cause the wear of the dental hard tissues, gingival recession and other oral changes with sometimes subsequent problems. Age-related wear of tooth surfaces reduces the dental enamel thickness and exposes deeper layers of enamel, which have different physical and chemical properties than the surface enamel. Gingival recession is the main causal factor of root caries and dentine hypersensitivity. Age-related changes in dentine include the formation of secondary dentine and the reduction in tubular lumen diameter (dentine sclerosis), which lead to a reduction in the volume of the pulp chamber. In addition to the reduction in the volume of pulp chamber, changes to the dental pulp also include dental pulp calcifications. The age-related physiological changes to the teeth should be carefully distinguished from pathological changes, especially when they induce pain or a negative impact on the oral health-related quality of life (OHRQoL) of the older individuals. Therefore, regular oral examinations coupled with early preventive measures should aim at maintaining oral health until old age.

Differential inflammatory response of dental pulp explants and fibroblasts to saliva.

AIM: To investigate the inflammatory response of dental pulp fibroblasts and the respective explants to whole saliva. METHODOLOGY: Explants from human and porcine dental pulp tissue and isolated dental pulp fibroblasts were used to investigate the inflammatory response to sterile saliva. Cytokine and chemokine expression was assessed by RT-PCR. Western blot analysis and pharmacologic inhibitors were used to determine the involvement of signalling pathways. RESULTS: Dental pulp explants of human and porcine origin exposed to human saliva exhibited no major changes of IL-6 and IL-8 mRNA expression (P > 0.05). In contrast, isolated porcine and human dental pulp fibroblasts, when stimulated with human saliva, exhibited a vastly increased expression of IL-6 and IL-8 mRNA (P < 0.05). In pulp fibroblasts, saliva also increased the expression of other cytokines and chemokines via activation of NFkappaB, ERK and p38 signalling. Notably, a significantly reduced inflammatory response was elicited when pulp fibroblasts were transiently exposed to saliva. CONCLUSIONS: Saliva has a potential impact on inflammation of dental pulp fibroblasts in vitro but not when cells are embedded in the intrinsic extracellular matrix of the explant tissue.

[Impact of different degree pulpitis on cell proliferation and osteoblastic differentiation of dental pulp stem cell in Beagle immature premolars].

OBJECTIVE: To compare the proliferation and osteoblastic differentiation of dental pulp stem cell (DPSC) isolated from normal and inflamed pulps of different degrees in Beagle immature premolars, and provide evidence for the use of inflammatory DPSC (IDPSC). METHODS: This study evaluated 14 Beagle's young premolars (21 roots). In the experiment group, irreversible pulpitis was induced by pulp exposure and the inflamed pulps were extracted 2 weeks and 6 weeks after the pulp chamber opening.For the control group, normal pulps were extracted immediately after the exposure. HE staining and real-time PCR were performed to confirm the inflammation. The cells were isolated from the inflamed and normal pulps (IDPSC and DPSC). Cell proliferation and osteoblastic differentiation potentials of the two cells were compared. RESULTS: Inflammation cells infiltration was observed in the inflamed pulps by HE staining. The expression of inflammatory factor was much higher in the 6 week inflamed pulp. IDPSC had higher potential of cell proliferation and osteoblastic differentiation potentials. Furthermore, the osteoblastic differentiation potentials of IDPSC from 2 week inflamed pulp were higher than those from 6 week inflamed pulp. CONCLUSION: The potential of cell proliferation and osteoblastic differentiation of DPSC was enhanced at early stage of irreversible pulpitis, and reduced at late stage in Beagle immature premolars.

Temporal dynamics of anxiety phenotypes in a dental pulp injury model.

BACKGROUND: Accumulating clinical and preclinical evidence indicates that chronic pain is often comorbid with persistent low mood and anxiety. However, the mechanisms underlying pain-induced anxiety, such as its causality, temporal progression, and relevant neural networks are poorly understood, impeding the development of efficacious therapeutic approaches. RESULTS: Here, we have identified the sequential emergence of anxiety phenotypes in mice subjected to dental pulp injury (DPI), a prototypical model of orofacial pain that correlates with human toothache. Compared with sham controls, mice subjected to DPI by mechanically exposing the pulp to the oral environment exhibited significant signs of anxiogenic effects, specifically, altered behaviors on the elevated plus maze (EPM), novelty-suppressed feeding (NSF) tests at 1 but not 3 days after the surgery. Notably, at 7 and 14 days, the DPI mice again avoided the open arm, center area, and novelty environment in the EPM, open field, and NSF tests, respectively. In particular, DPI-induced social phobia and increased repetitive grooming did not occur until 14 days after surgery, suggesting that DPI-induced social anxiety requires a long time. Moreover, oral administration of an anti-inflammatory drug, ibuprofen, or an analgesic agent, ProTx-II, which is a selective inhibitor of NaV1.7 sodium channels, both significantly alleviated DPI-induced avoidance in mice. Finally, to investigate the underlying central mechanisms, we pharmacologically blocked a popular form of synaptic plasticity with a GluA2-derived peptide, long-term depression, as that treatment significantly prevented the development of anxiety phenotype upon DPI. CONCLUSIONS: Together, these results suggest a temporally progressive causal relationship between orofacial pain and anxiety, calling for more in-depth mechanistic studies on concomitant pain and anxiety disorders.

Efficacy of different treatments of root canal walls on the pull-out bond strength of the fiber posts.

The aim of this study was to evaluate the efficacy of different irrigation protocols, including laser, on the retention of the fiber-reinforced composite posts to root canal dentinal walls using pull-out tests. Root canals of 60 single-rooted human teeth were filled and post spaces were prepared. Finally, specimens were divided randomly into five groups, each consisting of 12 specimens as follows: 5% NaOCl (control group), 17% EDTA, ultrasonic with 17% EDTA, single 1.5-W Er:YAG laser application, and the combined use of Er:YAG laser and 17% EDTA. After the root canal procedures, fiber posts were cemented to the root canal. Pull-out tests were performed using a universal testing machine at a crosshead speed of 2 mm/min. The data were analyzed using a one-way ANOVA and Bonferroni post hoc test (p = 0.05). Irradiation by the Er:YAG laser with/without EDTA positively affected the pull-out bond strength (p < 0.001). The pull-out strength was significantly higher in the ultrasonic group than that of the single irrigation with NaOCl or EDTA (p < 0.001). Er:YAG laser irradiation with/without EDTA enhanced the bond strength of fiber posts to root canal dentin walls. Additionally, ultrasonic-EDTA combination increased the bond strength.

Efficiency and Reliability of Thermal and Electrical Tests to Evaluate Pulp Status in Primary Teeth with Assessment of Anxiety Levels in Children.

OBJECTIVE: Assessing the pulp status plays a vital role in diagnosis and treatment planning in dentistry especially in children, who may not be able to verbalize their dental symptoms. Pulp sensibility test is used as a valuable investigation to evaluate the state of pulp. The aim of this study is to assess the efficiency and reliability of thermal and electrical pulp tests in primary teeth and to rule out the anxiety level involved in each tests. STUDY DESIGN: 30 children aged between 6 to 8 years with carious primary molar teeth in need of conservative pulp therapy were included in this study. 3 tests at random were employed on each tooth which includes cold, heat, electrical pulp test. The sensitivity, specificity, positive predictive value and negative predictive value were evaluated based on the clinical visual examination on access opening and the accuracy for each test was calculated. The Facial Image Scale (FIS) was used to assess the state of dental anxiety in children due to these pulp sensibility tests. RESULTS: The highest accuracy rate was calculated for EPT (0.814) followed by cold test (0.777) and heat test (0.759). CONCLUSION: No significant association was found between the accuracy of all the three tests. (P value > 0.05). Cold test is the most reliable test due to its simplicity and ease to perform. (FIS -1.53).

Pulpal response to sensibility tests after traumatic dental injuries in permanent teeth.

BACKGROUND/AIM: The assessment of pulp vitality is one of the major challenges in dental traumatology due to the temporary loss of sensibility after trauma and because of the limitations of conventional pulp tests. The aim of this study was to evaluate pulpal response to sensibility tests and to determine their accuracy after crown fractures and luxation injuries. MATERIALS AND METHODS: A total of 121 permanent anterior teeth from 78 patients treated at the Dental Trauma Clinic of the Federal University of Minas Gerais were evaluated. Responses to pulp sensibility tests were monitored for a minimum period of 24 months or until the diagnosis of pulp necrosis. RESULTS: At the first appointment, 68 teeth responded positively to sensibility tests, one tooth was necrotic and 52 teeth did not respond to sensibility tests but showed no other signs of necrosis. The initial lack of response was not associated with age (P = 0.18), but was related to the presence of luxation (P < 0.001). At the final appointment, 87 teeth were classified as vital and 31 were classified as non-vital. While a positive response shortly after trauma was a good predictor of vitality, a lack of response was not associated with subsequent necrosis. The final pulpal condition of the teeth that initially did not respond was associated with the type of injury, as displaced teeth tended to develop necrosis (P = 0.008). The accuracy of each sensibility test at the initial and final appointments was, respectively, 55.1% and 67.8% for the heat test, 55.9% and 77.9% for the cold test, and 57.6% and 89% for the electrical test. CONCLUSIONS: A temporary loss of sensibility was a frequent finding during post-traumatic pulpal healing, especially after luxation injuries. All sensibility tests presented low accuracy shortly after trauma. The electrical test provided the best support for pulpal diagnosis after long-term follow up. The clinician must be aware of additional signs of crown discoloration and radiographic changes before initiating endodontic treatment.

Pulp and periodontal healing after replantation of a maxillary immature incisor: a 13-year follow-up.

BACKGROUND: Traumatic tooth avulsions occur most often in 7 to 9 year-old children. Replantation is considered the treatment of choice and follow-up is required in order to prevent possible complications. CASE REPORT: A case of replantation of a maxillary immature incisor in a 9.2-year-old male is reported. Tooth 21 was stored in saliva, in the child's mouth, and it was replanted within 45 min following a bicycle accident. A flexible splint was applied from tooth 11 to tooth 63, and it was removed after 4 weeks. Pulp canal obliteration was diagnosed at the 6 months check-up visit. Pulp sensibility was positive after 3 months and absent after 5 years. During the follow-up the tooth completed its development and always presented a physiological mobility and a probing depth <3 mm. Only a minimal discoloration of the crown was observed. CONCLUSION: The knowledge of emergency care at the scene of dental trauma is resolutory for treatment outcome.

Descriptors of permanent teeth with cariously exposed pulp in patients presenting at a Nigerian hospital.

AIM: To describe the pattern of presentation of carious permanent teeth with pulp exposure and to determine factors associated with choice of treatment for such teeth. MATERIALS AND METHODS: All patients presenting at the oral diagnosis clinic of Lagos University Teaching Hospital Dental centre between January 2009 and June 2009 were examined and those with carious lesion involving the pulp were included in the study. The history and character of pain from teeth, extent of tooth structure lost, proposed treatment and reason for proposed treatment was recorded. RESULTS: The tooth most affected by pulp exposure due to caries is the lower first molar (17.5%). Extraction was the treatment of choice for many patients due to the following reasons: obliterated root canals (30%), patients' preference (30%) and non-restorable teeth (22%). CONCLUSION: Extraction was the predominant treatment chosen for cariously exposed permanent teeth due to the condition of the tooth.

[Influence of intra-pulpal temperature when using femtosecond laser in specific parameters to prepare cavities in tooth enamel: an in vitro study].

OBJECTIVE: To take the Real-time measurement of the intra-pulpal temperature (IPT) when using femtosecond laser in specific parameters to prepare cavities in tooth enamel in vitro, and to preliminarily evaluate the effect of air cooling. METHODS: All pulp champers of extracted human teeth (premolars and molars) were exposed by roots amputated and pulp scraped out. All chambers were tightly filled with copper powder, and thermocouple was inserted into the center of the powder stack. The bottom of the chamber was sealed with insulating tape. Thermocouple wire was fixed at the same time. The 2.25 mm×2.25 mm square cavities were prepared using femtosecond laser in the enamel with the average scan speed of 0.4 mm/s. The real-time IPT change was measured with thermocouple digital thermometer. Air cooling was added to the procedure once the temperature increased to reach a balance. RESULTS: The IPT rising was defined as ΔT . Before the usage of air cooling, the maximum of the ΔT value of the sample premolar was 12.3 °C. After using air cooling, the IPT decreased and ΔT value became 3.0 °C . The maximum of ΔT of the sample molar before using air cooling was 1.8 °C , and decreased to -0.1 °C after it. CONCLUSION: When preparing a cavity whose average depth is about 250 µm by femtosecond laser system in specific parameters, the IPT rises while the depth increass, but it could be controlled effectively by air cooling.

Root resorption of primary molars without successor teeth. An experimental study in the beagle dog.

Tooth agenesis is a common craniofacial congenital malformation in humans, but little is known about the mechanisms of root resorption in this condition. The purpose of this study was to investigate the mechanisms of root resorption in primary molars without successors. An animal model without permanent tooth germs was established by surgery in beagles. The times of onset of primary molar root resorption, with and without successors, were compared. The distribution of immune cells, odontoclasts, and their activating factors were determined by histochemistry and immunohistochemistry. Root resorption of primary mandibular molars without successors began later than physiological resorption. In primary molars without permanent germs, odontoclasts and immune cells were present mainly in the apical pulp at the start of root resorption, whereas in control teeth receptor activator of nuclear factor-κB ligand (RANKL)-positive cells were found mainly in the region of the periodontal ligament. CD14(+) and CD3(+) cells were found in both the pulp and the periodontal ligament region. These results suggest that the dental pulp of primary molars, as well as immune cells, may play an important role in root resorption in primary molars without permanent tooth germs.

Pulp regeneration after non-infected and infected necrosis, what type of tissue do we want? A review.

Regeneration (revitalization) of infected necrotic pulp tissue has been an important issue in endodontics for more than a decade. Based on a series of case reports, there appears to be evidence that new soft tissue can enter the root canal with a potential for subsequent hard tissue deposition resulting in a narrowing of the root canal. Very little is presently known about the exact nature of this tissue growing into the canal and how it may behave in the long term. In the case of regeneration of necrotic non-infected pulp tissue, a series of clinical and histological studies have shown that such events may take place in four variants: (i) Revascularization of the pulp with accelerated dentin formation leading to pulp canal obliteration. This event has a good long-term prognosis. (ii) Ingrowth of cementum and periodontal ligament (PDL). The long-term prognosis for this event is not known. (iii) Ingrowth of cementum, PDL, and bone. The long-term prognosis is only partly known, but cases developing an internal ankylosis have been described. (iv) Ingrowth of bone and bone marrow is a rare phenomenon and the long-term prognosis does not appear to be good. Based on current knowledge, expectations with respect to pulp regeneration (revitalization) of infected necrotic dental pulps are difficult to predict; more information than now available is needed before procedures for pulpal regeneration can be routinely recommended with a predictable long-term prognosis.

Dental Trauma Guide: a source of evidence-based treatment guidelines for dental trauma.

Diagnosis and treatment for traumatic dental injuries are very complex owing to the multiple trauma entities represented by six luxation types and nine fracture types affecting both the primary and the permanent dentition. When it is further considered that fracture and luxation injuries are often combined, the result is that more than 100 trauma scenarios exist, when the two dentitions are combined. Each of these trauma scenarios has a specific treatment demand and prospect for healing. With such a complexity in diagnosis and treatment, it is obvious that even experienced practitioners may have problems in selecting proper treatment for some of these trauma types. To remedy this situation, an Internet-based knowledge base consisting of 4000 dental trauma cases with long-term follow up is now available to the public and the professions on the Internet using the address http://www.DentalTraumaGuide.org. It is the aspiration that the use of this Guide may lead the practitioner to offer an evidence-based diagnosis and treatment.