Effect of Photobiomodulation Therapy on Differentiation of Mesenchymal Stem Cells Derived from Impacted Third Molar Tooth into Neuron-like Cells.

Peripheral nerve damages are among the most important consequences of dental and maxillofacial procedures. Tissue engineering using mesenchymal stem cells (MSCs) is a promising method to manage such injuries. Moreover, photobiomodulation therapy (PBMT) can enhance this treatment. The present study aimed to investigate the effect of PBMT on differentiation of MSCs derived from dental follicle (DF) into neurons. MSCs were isolated from an impacted tooth follicle by digestion method. The stem cells were cultured, and differentiated into neurons. The cells received two sessions of PBMT with 810 or 980 nm diode laser (100 mW, 4 J cm-2 ) in either DMEM or neural inductive medium. Phenotypic characterization of the cells was determined using flow cytometry. In addition, ß-tubulin and MAP2 genes expression level changes were analyzed using RT-PCR and western blot technique. After 14 days, flow cytometry analysis confirmed the mesenchymal nature of cells. RT-PCR and western blot affirmed the expression of ß-tubulin and MAP2 genes and proteins respectively. PBMT with both wavelengths significantly increased ß-tubulin and MAP2 expression in neural inductive medium with highest expression mean in 980 nm group. PBMT with 810 and 980 nm lasers could be a promising adjunctive method in differentiation of DF-originated MSCs into neural cells.

TP53 polymorphisms in smokers' and nonsmokers' pericoronal follicles of asymptomatic impacted third molars.

BACKGROUND AND PURPOSE: The investigators designed and implemented a prospective cohort study composed of smoking and nonsmoking patients with asymptomatic fully impacted mandibular third molars. The objective of the paper was to evaluate 21 single-nucleotide polymorphisms (SNP) on the TP53 gene in smokers' (S) and nonsmokers' (NS) pericoronal follicles of asymptomatic impacted third molars. MATERIALS AND METHODS: Matrix-assisted desorption/ionization time of the flight mass spectrometry was used for SNP analysis of 21 regions in the TP53 gene. Descriptive statistics and Chi-square tests were computed with a P value of 0.05. RESULTS: : Ten of the 21 SNPs related to oral pathologies according to NCBI dbSNP, were detected; in these, the genotypic frequencies showed no differences between the S and NS groups (P > 0.05). The results showed a high ratio of SNPs without correlation between smoking and TP53 gene status. CONCLUSION: Further studies should examine the entire TP53 gene to elucidate how smoking affects it in larger study populations.

Is the Level of Nitric Oxide in the Dental Follicular Tissues of Impacted Third Molars With a History of Recurrent Pericoronitis a True Marker of Oxidative Stress?

PURPOSE: Nitric oxide (NO) is an indicator of oxidative stress in several tissues. Its role in dental follicular (DF) tissues of impacted third molars with a history of recurrent pericoronitis is not well elucidated. The present study compared NO levels between inflamed and noninflamed DF tissues of impacted third molars with a history of recurrent pericoronitis. MATERIALS AND METHODS: A cross-sectional study was designed. The study sample included inflamed DF tissues (test group) with certain local inflammatory symptoms, such as pain, tenderness, swelling, and erythema and noninflamed DF tissues (control group) without local inflammatory symptoms of impacted mandibular third molars. Each patient contributed only 1 specimen to the samples. All tissues samples were biochemically investigated for NO levels as an indicator of oxidative stress. The primary predictor variable was inflammatory status; secondary predictor variables were age and gender. The primary outcome variable was NO level. Descriptive and comparative analyses were conducted. RESULTS: The test group consisted of 57 patients (28 men, 29 women; mean age, 23.28 ± 5.16 yr) and the control group consisted of 57 patients (30 men, 27 women; mean age, 23.02 ± 5.42 yr). No relevant intergroup differences were noted for demographic findings such as age and gender. NO levels were significantly higher in inflamed DF tissues of impacted third molars than in noninflamed DF tissues (P < .05). CONCLUSION: Results of this study showed that NO might be used as an indicator of oxidative stress and the necessity to remove impacted mandibular third molars with a history of recurrent pericoronitis.

The evaluation of Ki67, p53, MCM3 and PCNA immunoexpressions at the level of the dental follicle of impacted teeth, dentigerous cysts and keratocystic odontogenic tumors.

UNLABELLED: The aim of this study is to analyze the immunoexpression of Ki67, p53, MCM3 and PCNA markers in epithelial remnants of dental follicles of impacted teeth and to identify a possible correlation between the immunoexpression of these markers in dentigerous cysts and keratocystic odontogenic tumors in order to evaluate their evolutionary behavior. MATERIALS AND METHODS: A total of 102 cases were included in the study and divided into three subgroups: the first subgroup consisted of 62 cases with dental follicles of impacted teeth, the second included 20 cases of dentigerous cysts and the third subgroup comprised a number of 20 cases with keratocystic odontogenic tumors. Immunomarking with the four antibodies was performed. RESULTS: A positive marking was obtained in over 60% of the dental follicles for all markers. Statistically significant differences were also obtained in dentigerous cysts and keratocystic odontogenic tumors for Ki67, p53 and MCM3. Assessment of the four antibodies in the two layers of keratocystic odontogenic tumors shows a positive correlation between Ki67 and MCM3 both for the basal and parabasal layer, with slightly increased values in the latter. CONCLUSIONS: In order to determine the proliferative capacity of epithelial remnants in the dental follicles, Ki67 and PCNA, Ki67 and MCM3 are the most useful markers in practice; they have similar behavior and are more likely to help in distinguishing between dentigerous cysts and keratocystic odontogenic tumors.

Does smoking affect the Ki67 and p53 expressions in asymptomatic fully impacted lower third molar follicles?

PURPOSE: Ki67 and p53 protein expressions are the most widely used markers to show the pathologic proliferation and early-stage tumoral alterations in vital tissues. The aim of this study was to compare Ki67 and p53 protein expressions in smokers' and nonsmokers' pericoronal follicles of asymptomatic impacted lower third molars (ILTMs). MATERIALS AND METHODS: A cross-sectional study was planned. The study sample was derived from a population of patients who presented for evaluation and operative treatment of asymptomatic ILTMs. The predictor variable was smoking status, defined as smoker or nonsmoker. Outcome variables were Ki67 and p53 protein expressions in ILTM follicles. Other study variables were age, gender, tooth position, cigarette pack-year, epithelial layer staining, and inflammation. Independent-samples t test analyses were conducted with SPSS 10.0 (SPSS, Inc, Chicago, IL), with statistical significance set at a P value equal to .05. RESULTS: The study sample was composed of 70 patients (35 in the smoker group) who contributed 60 follicles. There were statistical differences between the 2 groups for variables Ki67 and p53. Mean expression levels of Ki67 were 3.93 ± 2.17 and 2.48 ± 2.09, respectively, for smokers and nonsmokers (P = .011). Mean expression levels of p53 were 5.32 ± 1.98 and 3.06 ± 2.34, respectively, for smokers and nonsmokers (P = .000). CONCLUSION: The present study showed that dental follicles of smokers have higher Ki67 and p53 protein expressions than nonsmokers' follicles.

The study of barium concentration in deciduous teeth, impacted teeth, and facial bones of Polish residents.

The study determines the concentration of Ba in mineralized tissues of deciduous teeth, permanent impacted teeth, and facial bones. The study covers the population of children and adults (aged 6-78) living in an industrial area of Poland. Teeth were analyzed in whole, with no division into dentine and enamel. Facial bones and teeth were subjected to the following preparation: washing, drying, grinding in a porcelain mortar, sample weighing (about 0.2 g), and microwave mineralization with spectrally pure nitric acid. The aim of the study was to determinate the concentration of Ba in deciduous teeth, impacted permanent teeth, and facial bones. The concentration of barium in samples was determined over the ICP OES method. The Ba concentration in the tested bone tissues amounted to 2.2-15.5 µg/g (6.6 µg/g ± 3.9). The highest concentration of Ba was present in deciduous teeth (10.5 µg/g), followed by facial bones (5.2 µg/g), and impacted teeth (4.3 µg/g) (ANOVA Kruskal-Wallis rank test, p = 0.0002). In bone tissue and impacted teeth, Ba concentration increased with age. In deciduous teeth, the level of Ba decreased with children's age.

Expression of the IGF-1, IGFBP-3 and IGF-1 receptors in dental pulp stem cells and impacted third molars.

IGF-1 regulates the metabolism of hard dental tissue through binding to the IGF-1 receptor on target cells. Furthermore, IGF-binding-protein-3 promotes the accessibility of IGF-1. The aim of this study was to investigate the expression of IGF-1, IGFBP-3 and IGF-1R in STRO-1-positive dental pulp stem cells (DPSCs) and fully impacted wisdom teeth in relation to tooth development. Third molars were surgically removed from 60 patients and classified into two groups: teeth showing ongoing development (group 1) and teeth that had completed root shaping (group 2). The transcript and protein levels of IGF-1, IGFBP-3 and IGF-1R were investigated using RT-PCR and immunohistochemistry. The expression of the same proteins was also analyzed in DPSCs. The teeth from group 1 showed significantly stronger expression of IGF-1 and IGF-1R. The major sources of all of the proteins investigated immunohistochemically in sections of wisdom teeth were odontoblasts, cementoblasts and cell colonies in the pulpal mesenchyme. These colonies were identified as stem cells in view of their positivity for STRO-1, and the cells were subsequently sorted by flow cytometry. These DPSCs demonstrated high levels of pluripotency markers and IGF-1 and IGF-1R. We conclude that members of the IGF-1 family are involved in the late stage of tooth development and the process of pulpal differentiation.

Immunohistochemical analysis of CK 18 in dental follicles of impacted third molars: a pilot study.

OBJECTIVE: Odontogenic tumors are lesions derived from epithelial, ectomesenchymal, and/or mesenchymal elements that still are, or have been, part of the tooth-forming apparatus. Approximately 80% of odontogenic tumors occur in the mandible, with a marked predilection for the posterior region, and are often associated with an unerupted tooth. The aim of this study was to determine whether cytokeratin (CK) 18 immunostaining decorated the follicular tissue removed at the time of prophylactic extraction of impacted mandibular third molars, which might suggest oncofetal transformation. MATERIALS AND METHODS: Fifty-four impactions met the study inclusion criteria, of which 24 cases showed the presence of reduced enamel epithelium and/or connective tissue with odontogenic epithelium, which were subjected to CK 18 immunostaining. RESULTS: All 24 cases with adequate epithelium were CK 18 immunonegative. CONCLUSION: There was no oncofetal transformation in the odontogenic epithelia of the dental follicles studied. Thus, although we reaffirm that evaluation of follicular tissue is imperative since disease conditions may be found in minute follicular spaces, development of odontogenic cysts and tumors is unlikely.

Ki-67 and MCM-2 in dental follicle and odontogenic cysts: the effects of inflammation on proliferative markers.

The aim of this study was to investigate whether there is any association between inflammation and the expression of markers of cell cycle entry (Ki-67 and MCM-2) in dental follicle (DF) of asymptomatic impacted teeth and odontogenic cysts. The study consisted of 70 DFs and 20 odontogenic cysts (radicular cyst (RC), dentigerous cyst (DC) and keratocytic odontogenic tumor (KCOT) located at posterior mandibular region. Histological findings of inflammation for all specimen and mucous cell prosoplasia, squamous metaplasia, glandular epithelium for all DFs were stained with hematoxyline and eosin, periodic acid schiff, alcian blue, and mucin. Epithelial cell proliferation was determined by using immunohistochemical labeling for Ki-67 and MCM-2. The histologic examinations showed 16% mucous cell prosoplasia, 54% squamous metaplasia, 20% glandular epithelium, 37% inflammation. Inflammation was detected in all RCs and %62 in DF, %43 in DC and KCOT. Positive correlation was found between the inflammation of DF and odontogenic cysts (P < 0.01). The mean Ki-67 and MCM-2 expressions were found 9, 64 ± 5, 99 and 6, 34 ± 3, 81 in DF, 11, 85 ± 9, 01 and 13, 6 ± 9, 94 in odontogenic cysts, respectively. While the mean Ki-67 expressions were statistically significant in DF and KCOT (P < 0.01), MCM-2 were significant in RC and KCOT (P < 0.01). MCM-2 expresion in RCs were statistically significant than KCOT (P < 0.01). The results of this study indicated that the higher MCM-2 expressions in RC than the KCOT might be related to the inflammation and this protein might be more sensitive to inflammation.

Interleukin-1 beta, interleukin-6 and TGF-beta in follicular tissue of impacted third molars.

The clinical evaluation and management of impacted third molars remain challenging. The aim of the present study was to investigate possible associations between follicular tissue cytokines and radiographic manifestations of impacted third molar. The population included 72 patients who underwent surgical extraction of impacted third molars. All these patients underwent a preliminary panoramic radiograph. Levels of interleukin-1 beta (IL-1ß), interleukin-6 (IL-6) and transforming growth factor beta (TGF-ß) in tissue extracts were determined using ELISA. There were no significant differences between bony and tissue impaction as regards IL-1ß, IL-6 and TGF-ß levels. Moreover, the same results were obtained as far as the amount of pericoronal space and the presence or absence of a history of pericoronitis are concerned. These results suggest that radiographic findings or a history of pericoronitis are not associated with levels of expression of pro-inflammatory cytokines in patients undergoing surgical removal of impacted third molars. However, further studies are needed to address the possibility of variability during disease progression.

Malondialdehyde levels in dental follicles of asymptomatic impacted third molars.

PURPOSE: Increased levels of reactive oxygen species lead to oxidative stress and tissue damage. Malondialdehyde (MDA) is one of many low-molecular-weight endproducts of lipid peroxidation that increases with oxidative stress. The aim of this study was to determine oxidative stress in dental follicles (DFs) of radiologically asymptomatic impacted third molars (ITMs) using MDA. MATERIALS AND METHODS: This study involved 40 DFs of 40 patients referred for clinically and radiographically asymptomatic ITMs. Forty healthy gingival tissues in the same patients were obtained during surgical removal of teeth as a control group. DF widths on periapical radiographs narrower than 2.5 mm were included in the study. All tissues samples were analyzed for MDA as an indicator of oxidative stress. RESULTS: Levels of MDA were significantly higher in DFs from ITMs than those from healthy gingival tissues of the same patients (P < .01). CONCLUSION: The results suggest that significant oxidative stress may occur in DFs of asymptomatic ITMs. The findings suggest that increased MDA may play an important role in oxidative stress in DFs. In light of these preliminary findings of the present study, further investigations and comprehensive studies are required to determine the role of antioxidants that scavenge free radicals in DFs.

Pathological changes and immunoexpression of p63 gene in dental follicles of asymptomatic impacted lower third molars: an immunohistochemical study.

OBJECTIVE: The aim of this study was to examine the pathologic changes and immunoexpressivity of p63 gene in dental follicles (DFs) of asymptomatic partially and completely impacted lower third molars. STUDY DESIGN: Clinical and radiologic examinations included 50 DFs with no signs of abnormal radiolucency (follicular space <2.5 mm), taken from 50 patients. RESULTS: Histopathologic examinations of the specimens revealed 47 normal dental follicular tissues, 1 ameloblastoma, and 2 dentigerous cysts. p63 Immunoexpressivity was stronger in the DFs of the group with completely impacted teeth (64%),than it was in the case of DFs of the group with partially impacted teeth (40%). CONCLUSIONS: Stronger p63 gene immunoexpression in the group with completely impacted teeth might be a consequence of bigger number of stem cells than it is in the case of the group with partially impacted teeth. This study also supports prophylactic removal of impacted teeth because of the development of pathologies associated with them.

Molecular characterization of human impacted third molars: diversification of compartments.

To gain more insight into the development of human teeth, we characterized different compartments of impacted third molars at two developmental stages by assessing expression levels of a set of genes. We considered genes known to be essential for the development of teeth and ectomesenchyme as well as genes covering characteristic features of stemness. Molars were divided into the operculum, periodontal ligament, developing pulp and, using a new approach, the pad-like tissue beneath the developing pulp. Markers for ectomesenchyme and tooth development known from rodents were assayed by semiquantitative PCR and every compartment was assigned its own signature of gene expression. The expression of markers characteristic of stem cells pointed to multipotent features. The expression patterns found shift in the course of development underscoring the relevance of these genes involved in human tooth development. The results suggest an inherent asymmetry between the developing pulp and pad-like tissue established early in tooth development. A microarray analysis of cells derived from pad-like tissue and pulp proper was performed to obtain cues regarding the consequences of tissue diversification. Both sets of data support the validity of our new approach to the subdivision of the developing tooth, by indicating a compartment-dependent commitment of isolated cells probably due to the postulated asymmetry within the developing tooth germ.

Early soft tissue pathosis associated with impacted third molars without pericoronal radiolucency.

OBJECTIVES: This study was performed to histologically evaluate soft tissue pathosis in pericoronal tissues of impacted third molars that did not exhibit pathologic pericoronal radiolucency. STUDY DESIGN: One hundred impacted third molars without evidence of abnormal pericoronal radiolucency (follicular space <2.0 mm) were removed for reasons other than participation in this study, and the pericoronal tissues were submitted for histopathologic examination. Specimens were fixed and processed routinely and were stained with hematoxylin and eosin before independent evaluation by each of 2 oral pathologists. A subset of both diseased and healthy tissues underwent additional evaluation for the presence of proliferating cell nuclear antigen (PCNA) for assessment of cellular activity. RESULTS: Of the specimens submitted, 34% showed squamous metaplasia suggestive of cystic change equivalent to that found in dentigerous cysts. Soft tissue pathosis was significantly higher in patients over 21 years of age (P =.001). Five of 8 diseased specimens demonstrated PCNA uptake, whereas none of 10 healthy specimens were PCNA positive. CONCLUSIONS: These findings suggest that radiographic appearance may not be a reliable indicator of the absence of disease within a dental follicle. We conclude that the incidence of soft tissue pathologic conditions is higher than generally assumed from radiographic examination alone.

High resolution electron microscopy of the initial mineral deposition on enamel surface.

The human partially impacted third molar was used to investigate the initial stage of dental calculus on enamel surface. The thin layer of mineral deposition consisted of needle-like crystals. High resolution electron microscopy (HREM) revealed that these crystals directly contacted each other. Electron diffraction represented that needle-like crystals of calculus consisted of hydroxyapatite (OH-AP). These findings indicate that the high calcium (Ca) x inorganic phosphate (Pi) ion-product condition in an extremely narrow and closed environment produces the stable OH-AP precipitates and that the growth of calculus crystals is thought to advance through the additional mineralization.

Systemic lead absorption in human tooth roots.

One-hundred and five impacted and erupted sound teeth were analysed for lead content by graphite furnace atomic absorption spectrophotometry. The results showed that lead accumulated before eruption, presumably soon after the onset of dentine formation. The accumulation in dentine was systemic, without any contribution from the oral environment. The amount of lead in dentine may denote the amount of absorption into the body and serve as a precise index to body burden as no absorption from the mouth can take place. In adults, impacted and erupted teeth can be used together in any research and the donor's age can be considered as the period of lead accumulation.

Fluoride concentrations in fissure and cervical enamel of unerupted human teeth.

Fluoride concentration of fissure enamel from unerupted third molars was higher than that of the cervical-lingual but not cervical-buccal surfaces at a similar depth of the removed enamel. The highest fluoride concentration was found in the fissure enamel due probably to its earlier formation, higher permeability and embedding tissue before eruption.