Comprehensive Characterization of 2 Immature Teeth Treated with Regenerative Endodontic Procedures.

INTRODUCTION: Regeneration of the pulp-dentin complex is the penultimate goal of regenerative endodontic procedures (REPs). Histological outcomes have demonstrated reparative tissue formation in human teeth extracted post-REPs. However, lack of accurate characterization has precluded identification of the true nature of tissues formed post-REP. METHODS: Here, we present 2 case reports of tooth #29 and #9 treated with REPs and demonstrate their clinical, radiographic, and histological outcomes. RESULTS: Clinical outcomes revealed healing of apical periodontitis in both teeth and re-establishment of vitality responses in tooth #29. Moreover, radiographic assessments using 2D and 3D-volumetric analyses demonstrate considerable increase in root development for both teeth. Further, histological outcomes evaluated using Hematoxylin and Eosin and immunohistochemical staining demonstrates presence of vascular and lymphatic structures as well as immune cell markers indicative of regeneration of an immunocompetent pulp. Lastly, examination of hard tissue deposition shows dentin-like tissue in parts of tooth #29 demonstrating for the first time, regeneration of a pulp-dentin complex post-REP. CONCLUSIONS: Collectively, this is the first study demonstrating recapitulation of several tissues commonly found as part of a pulp-dentin complex in teeth treated with REPs.

Immunoexpression of tumour necrosis factor-α, interleukin-1α and interleukin-10 on odontogenic cysts and tumours.

AIM: To analyse the immunoreactivity of IL-1α, TNF-α and IL-10 in odontogenic cysts and tumours and to investigate possible associations with established biological behaviours of these different lesions. METHODOLOGY: Immunohistochemical expression of anti-IL-1α, anti-TNF-α and anti-IL-10 antibodies was assessed on epithelium and mesenchyme of 20 radicular cysts (RCs), 20 residual cysts (RECs), 20 dentigerous cysts (DCs), 18 solid ameloblastomas (SAs), 20 keratocystic odontogenic tumours (KCOTs) and 15 dental follicles (DFs). Comparative analysis of data was performed using the nonparametric Wilcoxon signed-rank test and Kruskal-Wallis's test. RESULTS: Significantly greater expression of IL-1α in the epithelium was noted in RC, KCOT and SA (P = 0.01), whilst IL-10 and TNF-α was in the epithelium of RC, DC and KCOT (P < 0.01). In the mesenchyme, significantly greater immunopositivity was observed for IL-1α, IL-10 and TNF-α in KCOT, DC and RC (P < 0.01). In epithelial and mesenchymal tissues, there were a significant number of cases of RC and DC with IL-1α < IL-10 ratio (P < 0.01), whilst SA and KCOT showed IL-1α > IL-10 (P < 0.01). There was a significantly greater percentage of DF, DC and KCOT with TNF-α > IL10 ratio (P < 0.01). CONCLUSION: These results suggest involvement of the proteins in the pathogenesis of odontogenic cysts and tumours, with emphasis on the highest immunoreactivity of osteolysis stimulating factors in tumours with aggressive biological behaviour, such as SA and KCOT.

Host-Bacterial Interactions in Post-treatment Apical Periodontitis: A Metaproteome Analysis.

INTRODUCTION: This study evaluated the bacterial and human metaproteome of root apexes and the matched inflammatory lesions from teeth with post-treatment apical periodontitis. METHODS: Root apexes and matched inflammatory lesions from root canal-treated teeth with apical periodontitis were obtained during periradicular surgery. All root canal fillings were rated as adequate on the basis of radiographs and cone-beam computed tomography. The specimens were cryopulverized and subjected to metaproteomic analysis for human and bacterial proteins by using a mass spectrometry platform that is based on nanoflow liquid chromatography coupled with linear ion trap quadrupole Velos Orbitrap. RESULTS: The metaproteome analyses revealed the presence of viable and metabolically active human and bacterial cells in both apexes and lesions. Several bacterial proteins of interest for pathogenicity and therapeutics were identified in both apexes and lesions, including proteins related to antibiotic resistance, proteolytic function, stress response, adhesion, and virulence. Many human proteins related to immune defense mechanisms were also detected in both root apex and lesion specimens, including immunoglobulins, complement system, and proteins linked to T-cell and B-cell activation, neutrophil microbicidal processes, antigen recognition/presentation, bone resorption, and protection against tissue damage. CONCLUSIONS: Occurrence of host defense factors from the innate and adaptive immune responses and bacterial virulence, survival, and resistance proteins in matched root apexes/periradicular inflammatory lesions indicates a complex and dynamic host-pathogen interaction in teeth with post-treatment apical periodontitis.

The expression of macrophage migration inhibitory factor is correlated with receptor activator of nuclear factor kappa B ligand in induced rat periapical lesions.

INTRODUCTION: Macrophage migration inhibitory factor (MIF) has been defined as a key cytokine in regulation of innate and adaptive immunity. The purpose of this study was to investigate the immunohistochemical localization of MIF and its relationship with receptor activator of nuclear factor kappa B ligand (RANKL) protein during the development of periapical lesions in rats. METHODS: Apical periodontitis was induced in Wistar rats by occlusal pulp exposure in mandibular first molar teeth. The animals were randomly killed at 0, 7, 14, 21, 28, and 35 days after pulp exposure. The jaws that contained the first molar were obtained and were prepared for histologic analysis, enzyme histochemistry, immunohistochemistry, and double immunofluorescence staining. RESULTS: From day 0 to day 35, the areas of periapical bone loss increased and seemed to be stabilized on day 35. A few MIF-positive and RANKL-positive cells and osteoclasts could be observed on day 7, and all climaxed on day 14. From day 21 to day 35, the expression of MIF and RANKL protein decreased, and fewer osteoclasts could be observed. CONCLUSIONS: These findings showed that MIF might be associated with the differentiation of osteoclasts in the periapical lesions. MIF contributes to the pathogenesis of the periapical lesions through the induction of RANKL protein.

Root resorption and immune system factors in the Japanese.

The objective of this study was to determine whether there is an association between excessive root resorption and immune system factors in a sample of Japanese orthodontic patients. The records of 60 orthodontic patients (18 males, age 17.7 +/- 5.7 years; 42 females, age 16.4 +/- 6.0 years) and 60 pair-matched controls (18 males, age 15.9 +/- 4.5 years; 42 females, age 18.5 +/- 5.2 years) based on age, sex, treatment duration, and the type of malocclusion were reviewed retrospectively. The validity of our hypothesis was tested using the logistic regression analysis. The pretreatment records revealed that the incidence of allergy and root morphology abnormality was significantly higher in the root resorption group (P = .030 and .001), with a mean odds ratio of 2.794 and 6.317 and 95% confidence interval of 1.107-7.053 and 2.043-19.537, respectively. The incidence of asthma also tended to be higher in the root resorption group. From these results, we concluded that allergy, root morphology abnormality, and asthma may be high-risk factors for the development of excessive root resorption during orthodontic tooth movement in Japanese patients.

Sympathectomy causes increased root resorption after orthodontic tooth movement in rats: immunohistochemical study.

Accumulating evidence suggests that the sympathetic nervous system modulates inflammatory responses and bone remodeling. We have studied the effects of sympathectomy and orthodontic tooth movement (OTM) on root resorption, immunocompetent cell recruitment, neuropeptide, neurokinin-1 receptor (NK1-R), and interleukin 6 (IL-6) expression. Experimental rats (n=8) had the right superior cervical ganglion surgically removed, whereas control rats (n=6) underwent sham surgery. Three days later, all rats had the right maxillary first molar moved mesially by an orthodontic appliance. The rats were perfused 13 days later, and the right maxillae were processed for immunohistochemistry by using primary antibodies directed against ED1 antigen, CD43, substance P (SP), NK1-R, neuropeptide Y (NPY), and IL-6. Following OTM, sympathectomized (SCGx) rats had significantly more root resorption (P<0.01) and SP-immunoreactive (IR) fibers (P=0.01) in the compressed periodontal ligament (PDL) compared with control rats. There was a significant decrease in recruitment of CD43+ cells in the pulp after OTM in SCGx rats compared with control rats (P=0.02). An upregulation of NK1-R immunoreactivity was observed surrounding the hyalinized tissue, and an increase in the number of NK1-R IR cells and density of SP-IR fibers was present in first molar pulp of all rats. NPY-IR fibers were absent in the compressed PDL of SCGx and control rats. Thus, OTM induces remodeling not only around the periodontal tissues, but also in the dental pulp. The sympathetic nerves have an inhibitory effect on hard tissue resorption and a stimulatory effect on CD43+ cell recruitment after OTM.

Differential activation of human neutrophils by Streptococcus mutans isolates from root surface lesions and caries-free and caries-active subjects.

Phagocytosis of bacterial pathogens is an important defense mechanism and may contribute to regulating Streptococcus mutans-induced dental caries, particularly at root surfaces. This study was undertaken to examine and compare differences in polymorphonuclear leukocyte or neutrophil activation by clinical isolates of S. mutans collected from the saliva of caries-free or caries-active individuals with S. mutans isolates from root surface lesions. S. mutans clinical isolates (5 caries-free, 5 caries-active, 5 root caries isolates and a laboratory strain) were incubated with neutrophils in the presence of normal human serum and the luminol dependent chemiluminescence was measured for 1 h at 37 degrees C. Results indicated that the caries active and laboratory strains activated neutrophils equally. The mean integration stimulated by caries-free strains, however, displayed a 25-30% enhanced neutrophil activation over the caries-active and laboratory strains. In contrast, neutrophil activation by root caries strains of S. mutans was 45-50% lower than all other S. mutans strains, possibly suggesting a natural selection for S. mutans strains that can evade neutrophil recognition and subsequent phagocytosis. Stimulation of neutrophils with the cell wall and membrane surface component preparations indicated that extracts from all four groups activated neutrophils significantly. Again, caries-free preparations activated neutrophils significantly more than caries active, laboratory strain and root caries isolates. This selection may become more important on root surfaces due to increased exposure to crevicular fluid and neutrophils. The data provide evidence for the presence or onset of mechanisms or biological alterations in S. mutans developed to circumvent neutrophil recognition and/or phagocytosis, thus increasing S. mutans survival and colonization on tooth surfaces, resulting in an enhanced risk of dental caries, particularly at root surfaces.

[Dysregulation of the immunological mechanisms and phagocytic activity of the leukocytes--the leading cause of acute inflammation]. / Dizreguliatsiia immunologicheskikh mekhanizmov i fagotsitarnoi aktivnosti leikotsitov--vedushchaia prichina ostrogo vospaleniia.

The paper provides evidence for the assumption that the leading cause of acute odontogenic inflammatory processes of the face and neck is immunological deficiency which initiates the spread of infection from the radix dentis into cellular spaces. The type of inflammation (normo-, hyper-, or hypoergic) mainly depends upon the responsiveness of the phagocytic system. This conclusion is supported by the results of nonspecific and immunological correction made in patients.

Humoral immune response to active root resorption with a murine model.

A depression in autoantibody titers to tooth root antigens has been shown to coincide with active root resorption in the dog. Since a murine model would facilitate immunologic studies of root resorption because of the availability of syngeneic and immunodeficient strains, the objectives of this study were to develop a quantitative mouse model for root resorption and to determine if a similar drop in tooth root autoantibodies coincides with active root resorption in this species. Uniform areas of necrosis were created in the periodontal ligaments of lower incisors of 36 male Swiss albino mice by inserting a cryoprobe through a skin incision (-80 degrees C; 5 minutes). Contralateral incisors served as controls. At 0, 3, 5, 7, 10, 14, and 21 days; six mice were killed, and blood and incisors were collected. Relative surface areas of root resorption were quantified with micrographs taken at a standardized position, tilt, and magnification with a scanning electron microscope. Serum autoantibody titers were determined with an enzyme-linked immune sorbent assay with antigen prepared from a 5 mol/L guanidine-HCl-EDTA (pH 5.0) extract of incisor roots that were harvested from syngeneic mice. ANOVA and the paired Student t test were used to compare data at the various time points. No root resorption was evident on control teeth. Localized lesions on treated teeth were found to be of significant size between 7 and 14 days (p less than 0.05), but most of these erupted into the mouth by 21 days.(ABSTRACT TRUNCATED AT 250 WORDS)

Humoral immunity in root caries in an elderly population. 2.

Saliva specimens stored for 18 months at -20 degrees C with or without glycerol and the anti-protease benzamidine-HCl, lost all antibody activity for S. mutans. IgA activity in processed whole saliva decreased significantly after one week when stored either at 4 degrees C or -20 degrees C with or without glycerol, although it was stable in parotid saliva for at least 40 days. Loss of activity prior to processing was significant in the first 24 h, and the addition of 50% glycerol and storage at -70 degrees after processing, prevented loss of antibody activity in both whole and parotid saliva. Diurnal variations in IgA, lactoferrin and the IgA secretion rate were insignificant in parotid saliva but showed some fluctuations in whole saliva. Albumin and lactoferrin levels exhibited the greatest fluctuation in whole saliva specimens although IgA and IgA antibody levels were still more characteristic of the patient than the time of sampling. Monthly variations in IgA, IgA antibody activity and other parameters were least in parotid saliva and e.g., values for parameters that were high in patients samples on the first month, remained high during the 4-month study period. Statistical analyses showed a high correlation between values obtained for most of the 15 parameters that were measured in parotid and whole saliva specimens collected from greater than 20 patients during 2 successive visits. Whole saliva values for albumin, lactoferrin and albumin levels in parotid saliva, were most variable but differences were not significant. Hence, patients with very low or very high values, even in whole saliva, can be identified within the population on the basis of specimens collected at a single time.

Humoral immunity in root caries in an elderly population. 1.

IgA, IgG and IgM antibody activity (ELISA Units/ml) to Streptococcus mutans, Actinomyces viscous and Escherichia coli CF8 in serum, parotid saliva and whole saliva was measured using the amplified ELISA (a-ELISA) while the concentration (microgram/ml) of each isotype of immunoglobulin as well as albumin and lactoferrin, was determined using sandwich ELISAs. Selection of suitable reagents from those commercially available was based on specificity tests using purified human immunoglobulin; most polyclonal reagents required further absorption to attain class specificity. Cross-absorption studies indicated the absence of patient antibodies that were cross-reactive among the bacteria studied, except for IgM in some cases. Expression of response in ELISA Units (E.U.) per microgram of immunoglobulin, i.e. specific activity, revealed that IgG specific activity was significantly higher in parotid saliva than in either whole saliva or serum for all bacteria studied; serum and whole saliva did not differ except for the higher specific activity in whole saliva to E. coli. The value of one E.U. was determined using the Comparative Antibody-immunoglobulin Capture Assay (CACA). Using this novel method, we estimated that about 0.05 percent of serum IgA was specific for Streptococcus mutans, 0.008 for Actinomyces viscosus and 0.004 for Escherichia coli CF8. The percentage of specific IgM antibodies was higher than for IgA and IgG. The concentration of IgA anti-Streptococcus mutans, Actinomyces viscosus and Escherichia coli levels are approximately 92 ng/ml, 25 ng/ml and 16 ng/ml in whole saliva and 46 ng/ml, 9.4 ng/ml and 6.3 ng/ml in parotid saliva.(ABSTRACT TRUNCATED AT 250 WORDS)

Evidence of the alloimmunogenic potential of donor periodontal ligament.

The alloimmunogenic potential of each of the tooth graft components (periodontal ligament, mineralized root surface and passenger leukocytes) was evaluated. The model employed was orthotopic tooth allografts in inbred strains of Syrian hamsters. Isolated allogenic mineralized root surface is not immunogenic, as was demonstrated by the inability of tooth grafts to stimulate accelerated rejection of a subsequent skin graft if the tooth had undergone pretransplant enzymolysis of its periodontal ligament. Similarly, tooth grafts were rendered nonimmunogenic if exposed to repeated freezing and thawing. In contrast, isolated allogenic periodontal ligament on a syngeneic tooth graft was shown to evoke an accelerated rejection of skin grafts. Thus, the normal median survival time of skin (11.3 days) in the strain combination of hamsters employed was reduced to 7.4 days following exposure to an orthotopic tooth graft in which the periodontal ligament was the only obvious source of alloantigen. Prior elimination of a tooth allograft's passenger leukocytes by lethal whole body gamma-irradiation did not affect the graft's ability to sensitize the host.