The effects of systemic stress on orthodontic tooth movement

Objectives: To determine if systemic stress affects the biological reactions occurring during orthodontic tooth movement. Methods: Four groups of male 10 week-old Wistar rats were used. Group A animals (N=10) were restrained for one hour per day for 40 days; Group B animals (N=10) were restrained for one hour per day for three days; Group C (N=10) and Group D (N=8) animals were unrestrained. The upper left first molars in the rats in Groups A (long-term stress), B (short-term stress) and C (control) were moved mesially during the last 14 days of the experiment. The animals in Group D (N=8) were used for body weight and hormonal dosage comparisons only. They were not subjected to any stress and did not have appliances fitted. All animals were killed at 18 weeks of age and blood collected for measurement of plasma corticosterone. Tooth movement was measured with an electronic caliper. The right and left hemi-maxillae of five rats from each group were removed and the number of tartrate-resistant acid phosphatase (TRAP) positive cells, defined as osteoclasts, adjacent to the mesial roots of the upper first molars counted. The contralateral side in each animal served as the control (split-mouth design). Results: Corticosterone levels were significantly higher in the stressed groups (Groups A and B) than in the control group (Group C). Tooth movement was significantly greater in Group A (long-term stress) compared with Group B (short-term stress) and Group C (control), which did not differ from each other. There were significantly more osteoclasts in the long-term stress group than in the short-term stress and control groups. Conclusion: Persistent systemic stress increases bone resorption during orthodontic tooth movement. Systemic stress may affect the rate of tooth movement during orthodontic treatment.

Role of cytokines in mediating mechanical hypernociception in a model of delayed-type hypersensitivity in mice

In the present study, we used the electronic version of the von Frey test to investigate the role of cytokines (TNF-alpha and IL-1 beta) and chemokines (KC/CXCL-1) in the genesis of mechanical hypernociception during antigen-induced inflammation in mice. The nociceptive test consisted of evoking a hindpaw flexion reflex with a hand-held force transducer (electronic anesthesiometer) adapted with a 0.5 mm(2) polypropylene tip. The intraplantar administration of methylated bovine serum albumin (mBSA) in previously immunized (IM), but not in sham-immunized (SI) mice, induced mechanical hypernociception in a dose-dependant manner. Hypernociception induced by antigen was reduced in animals pretreated with IL-lra and reparixin (a non-competitive allosteric inhibitor of CXCR2), and in TNF receptor type 1 deficient (TNFR1-/-) mice. Consistently, antigen challenge induced a time-dependent release of TNF-alpha, IL-1 beta and KC/CXCL-1 in IM, but not in SI, mice. Consistently, antigen challenge induced a time-dependent release of TNF-alpha, IL-1 beta and KC/CXCL-1 in IM, but not in SI, mice. The increase in TNF-alpha levels preceded the increase in IL-1 beta and KC/CXCL1. Antigen-induced release of IL-1 beta and KC/CXCL1 was reduced in TNFR1-/- mice, and TNF-alpha induced hypernociception was inhibited by IL-lra and reparixin. Hypernociception induced by IL-1 beta in immunized mice was inhibited by indomethacin, whereas KC/CXCL1-induced hypernociception was inhibited by indomethacin and guanethidine, Antigen-induced hypernociception was reduced by indomethacin and guanethidine and abolished by the two drugs combined. Together, these results suggest that inflammation associated with an adaptive immune response induces hypernociception that is mediated by an initial release of TNF-alpha, which triggers that subsequent release of IL-1 beta and KC/CXCL1. The latter cytokines in turn stimulate the release of the direct-acting final mediator, prostanoids and sympathetic amines. (C) 2008 European Federation of Chapters of the International Association for the Study of Pain. Published by Elsevier Ltd. All rights reserved.

COEXISTENCE OF TWO CHRONIC NEUROPATHIES IN A YOUNG CHILD: CHARCOT-MARIE-TOOTH DISEASE TYPE 1A AND CHRONIC INFLAMMATORY DEMYELINATING POLYNEUROPATHY

We report an 18-month-old Charcot-Marie-Tooth type 1A (CMT1A) patient who developed a rapid-onset neuropathy, with proximal and distal weakness, and non-uniform nerve conduction studies. The neuropathy responded well to immunomodulation, confirming the coexistence of an inherited and an inflammatory neuropathy. Unexpected clinical and/ or electrophysiological manifestations in CMT1A patients should alert clinicians to concomitant inflammatory neuropathy. In addition, this association raises reflections about disease mechanism in CMT1A. Muscle Nerve 42: 598-600, 2010

Compound Charcot-Marie-Tooth disease may determine unusual and milder phenotypes

Compound forms of Charcot-Marie-Tooth (CMT) disease have been recently associated with unusually severe neuropathies, an observation that prompted the proposition that the additive effects of two mutations should be searched in patients whose clinical severity falls outside the common CMT phenotypes. In this report, we present a father and a daughter with a very mild and unusual disease that segregates with two mutations in PMP22 gene, the 17p11.2-p12 duplication and a Ser72Leu point mutation. We propose that the deleterious effects of each mutation are partially compensated by the functional effect of the other.

Characterizing the phenotypic manifestations of MFN2 R104W mutation in Charcot-Marie-Tooth type 2

Mutations of the mitofusin 2 (MFN2) gene have been reported to be the most common cause of the axonal form of Charcot Marie Tooth disease (CMT). The aim of this study was to describe a de novo MFN2 p.R104W mutation and characterize the associated phenotype. We screened the entire coding region of MFN2 gene and characterized its clinical phenotype, nerve conduction studies and sural nerve biopsy. Neuropsychological tests and brain MRI were also performed. A de nova mutation was found in exon 4 (c.310C > T; p.R104W). In addition to a severe and early onset axonal neuropathy, the patient presented learning problems, obesity, glucose intolerance, leukoencephalopathy, brain atrophy and evidence of myelin involvement and mitochondrial structural changes on sural nerve biopsy. These results suggest that MFN2 p.R104W mutation is as a hot-spot for MFN2 gene associated to a large and complex range of phenotypes. (C) 2011 Elsevier B.V. All rights reserved.

Expression of Extracellular Matrix Proteins in Human Dental Pulp Stem Cells Depends on the Donor Tooth Conditions

Introduction: Stem cells are characterized by the ability to renew themselves through mitotic cell division and differentiating into a diverse range of specialized cell types. An important source of adult stem cells is the dental pulp. In dentistry, regenerative strategies are of importance because of hard dental tissue damage especially as result of caries lesions, trauma, or iatrogenic procedures. The regeneration of dental tissues relies on the ability of stem cells to produce extracellular (ECM) proteins encountered in the dental pulp tissue. Thus, the aim of this study was to analyze the expression and distribution of proteins encountered in dental pulp ECM (type I collagen, fibronectin, and tenascin) in stem cells. Methods: Human immature dental pulp stem cells (hIDPSCs) from deciduous (DL-1 and DL-4 cell lines) and permanent (DL-2) teeth were used. The distribution of ECM proteins was observed using the immunofluorescence technique. The gene expression profile was evaluated using reverse transcription polymerase chain reaction (RT-PCR) analysis. Results: Positive reactions for all ECM proteins were observed independently of the hIDPSCs analyzed. Type I collagen appeared less evident in DL-2 than in other hIDPSCs. Fibronectin and tenascin were less clear in DL-4. The RT-PCR reactions showed that type I collagen was lesser expressed in the DL-2 cells, whereas fibronectin and tenascin were similarly expressed in all hIDPSCs. Conclusions: The distribution and expression of ECM proteins differ among the hIDPSCs. These differences seemed to be related to the donor tooth conditions (deciduous or permanent, retained or erupted, and degree of root reabsorption). (J Endod 2010;36:826-831)

Use of laser phototherapy on a delayed wound healing of oral mucosa previously submitted to radiotherapy: case report

Radiotherapy produces both acute and delayed effects on mucosal tissues, disturbing their healing. This report shows a successful treatment with laser phototherapy (LPT) on a delayed wound healing in oral mucosa previously submitted to radiotherapy with a follow up of 3 years. A 47-year-old patient treated 6 months earlier for tongue squamous cell carcinoma by surgery and radiotherapy presented with a mass in the operated area. Biopsy showed chronic inflammatory infiltrate around a residual polyglactin suture. After 2 months there was a painful mucosal dehiscence on the biopsy site. LPT was performed using a semiconductor laser with 660-nm wavelength (InGaAlP) and spot size of 0.04 cm(2). The parameters applied were 40 mW, 4 Jcm(2)/point, 0.16 J/point, 2.4 J/session. The irradiation was performed punctually, through contact mode in 15 points (4 seconds/point), on top of and around the lesion, during ten sessions. The wound healed completely after ten sessions. This treatment proved to be conservative and effective, inducing healing of a chronic wound in a tissue previously submitted to radiotherapy.

Tooth Tissue Engineering: Optimal Dental Stem Cell Harvest Based on Tooth Development

Our long-term objective is to devise reliable methods to generate biological replacement teeth exhibiting the physical properties and functions of naturally formed human teeth. Previously, we demonstrated the successful use of tissue engineering approaches to generate small, bioengineered tooth crowns from harvested pig and rat postnatal dental stem cells (DSCs). To facilitate characterizations of human DSCs, we have developed a novel radiographic staging system to accurately correlate human third molar tooth developmental stage with anticipated harvested DSC yield. Our results demonstrated that DSC yields were higher in less developed teeth (Stages 1 and 2), and lower in more developed teeth (Stages 3, 4, and 5). The greatest cell yields and colony-forming units (CFUs) capability was obtained from Stages 1 and 2 tooth dental pulp. We conclude that radiographic developmental staging can be used to accurately assess the utility of harvested human teeth for future dental tissue engineering applications.

MMP1 and MMP20 contribute to tooth agenesis in humans

Objective: Variations in genes that are critical for tooth formation may contribute to the tooth agenesis. MMPs are potential candidate genes for dental alterations based on the roles they play during embryogenesis. The aim of this study was to investigate the possible association between MMP1, MMP3, and MMP20 and tooth agenesis. Methods: One hundred sixty-seven nuclear families from two different populations were analysed, 116 from Brazil and 51 from Turkey. Probands had at least one congenitally missing tooth. DNA samples were obtained from blood or saliva samples and genotyping was performed using TagMan chemistry. In addition, Mmp20 was selected for quantitative real-time polymerase chain reaction analysis with SYBR Green I Dye in mouse tooth development. Results: Associations between tooth agenesis and MMP1 (p = 0.007), and MMP20 (p = 0.03) were found in Brazilian families. In the total dataset, MMP20 continued to be associated with tooth agenesis (p = 0.01). Mmp20 was not expressed during the initial stages of tooth development. Conclusion: Our findings provide evidence that MMP1 and MMP20 play a role in human tooth agenesis. (C) 2010 Elsevier Ltd. All rights reserved.

Tooth loss prevalence and risk indicators in an isolated population of Brazil

Objective. The aim of this study was to assess the prevalence, extent, and risk indicators of tooth loss in an isolated population of Brazil. Material and methods. Two-hundred-and-forty-two subjects, ranging in age from 14 to 82 years (mean 36.2 years), were identified by census in an isolated population of Brazil. All consenting subjects received a full-mouth clinical (DFT index and information about missing teeth) and periodontal examination of 6 sites per tooth. Furthermore, they were interviewed using a structured written questionnaire in order to gather information about demographic, environmental, and biological variables. Results. Of the 200 subjects (80% response rate), 19 (9.5%) were edentulous, 90% had lost at least one tooth, and 39% had lost more than 8 teeth. The mean number of teeth lost was 9.5 (95% CI = 8.2-10.8). First mandibular molars were the most commonly missing teeth. In a multiple logistic regression analysis based on a theoretical hierarchical model of tooth loss, having more than 8 teeth lost was strongly associated with adult age (OR = 18.3-17.3, 95% CIs = 4.8-69.7 and 4.0-75.1) and female gender (OR = 5.9, 95% CI = 1.9-18.2) in the final model. Conclusions. Tooth loss was highly prevalent and extensive in this isolated population. Demographic and behavioral factors played an important role in tooth loss prevalence in this population.

Effect of diabetes on orthodontic tooth movement in a mouse model

Orthodontic tooth movement is achieved by the remodeling of alveolar bone in response to mechanical loading. Type 1 diabetes results in bone remodeling, suggesting that this disease might affect orthodontic tooth movement. The present study investigated the effects of the diabetic state on orthodontic tooth movement. An orthodontic appliance was placed in normoglycemic (NG), streptozotocin-induced diabetes (DB), and insulin-treated DB (IT) C57BL6/J mice. Histomorphometric analysis and quantitative PCR of periodontium were performed. The DB mice exhibited greater orthodontic tooth movement and had a higher number of tartrate-resistant acid phosphate (TRAP) -positive osteoclasts than NG mice. This was associated with increased expression of factors involved in osteoclast activity and recruitment (Rankl, Csf1, Ccl2, Ccl5, and Tnfa) in DB mice. The expression of osteoblastic markers (Runx2, Ocn, Col1, and Alp) was decreased in DB mice. Reversal of the diabetic state by insulin treatment resulted in morphological findings similar to those of NG mice. These results suggest that the diabetic state up-regulates osteoclast migration and activity and down-regulates osteoblast differentiation, resulting in greater orthodontic tooth movement.

CCR5 Down-regulates Osteoclast Function in Orthodontic Tooth Movement

During orthodontic tooth movement, there is local production of chemokines and an influx of leukocytes into the periodontium. CCL5 plays an important role in osteoclast recruitment and activation. This study aimed to investigate whether the CCR5-receptor influences these events and, consequently, orthodontic tooth movement. An orthodontic appliance was placed in wild-type mice (WT) and CCR5-deficient mice (CCR5(-/-)). The expression of mediators involved in bone remodeling was evaluated in periodontal tissues by Real-time PCR. The number of TRAP-positive osteoclasts and the expression of cathepsin K, RANKL, and MMP13 were significantly higher in CCR5(-/-). Meanwhile, the expression of two osteoblastic differentiation markers, RUNX2 and osteocalcin, and that of bone resorption regulators, IL-10 and OPG, were lower in CCR5(-/-). Analysis of the data also showed that CCR5(-/-) exhibited a greater amount of tooth movement after 7 days of mechanical loading. The results suggested that CCR5 might be a down-regulator of alveolar bone resorption during orthodontic movement.

Effect of ion supplementation of a commercial soft drink on tooth enamel erosion

Acidic soft drinks are potentially erosive for dental hard tissues. This in vitro study evaluated the effect of calcium, fluoride, iron and phosphate, supplemented alone or in combination to a commercial citric acid-based carbonated beverage on dental erosion. Ninety enamel samples (4 x 4 x 3 mm) were randomly allocated to nine groups (n = 10): G1 - pure beverage (control); G2 - with 1 mM Ca; G3 - with 0.047 mM F; G4 - with 1 mM Fe; G5 - with 1 mM P; G6 - with 1 mM Ca and 0.047 mM F; G7 - with 1 mM Ca and 1 mM P; G8 - with 1 mM Fe and 0.047 mM F; and G9 - with 1 mM Ca, 1 mM P, 0.047 mM F and 1.0 mM Fe. The samples were subjected to six pH cycles over a 24-h period. In each cycle, the samples were immersed in pure or modified beverage (1 min) and in artificial saliva (59 min). During the remaining period (18 h), the samples were maintained in artificial saliva. Enamel loss was assessed by profilometry (mm). Data were tested using ANOVA and Tukey`s tests (p < 0.05). Highest enamel losses were observed in the control group (G1) and in the groups containing Fe (G4 and G8). The groups containing Ca (G2 and G6) showed significantly less wear compared to control. In conclusion, the modification of an erosive soft drink with low concentrations of Ca with or without F may reduced its erosive potential.

Prevalence of dental wear among 12-year-old Brazilian adolescents using a modification of the tooth wear index

Objective. This study investigated the prevalence of dental wear in 12-year-old adolescents using a modification of the tooth wear index (TWI). The modifications were proposed in order to fit with the World Health Organization standard, thus allowing application of the index in broad epidemiological surveys. Study design: An epidemiological cross-sectional survey was performed by trained, calibrated examiners, using a modified version of the TWI. Methods: Urban elementary schools were chosen because they provide a fair representation of the city`s population in terms of socio-economic status. The sample included 295 adolescents, selected randomly and systematically. Dental wear was assessed by calibrated examiners (kappa > 0.85), using a modified version of the TWI. This modified version includes a code for teeth restored due to wear, and another code for teeth that cannot be assessed. In addition, it does not differentiate the depth of dentine involvement. Proportions and confidence intervals were used to describe the prevalence of dental wear. Mann-Whitney test was used to detect differences in the degree of dental wear between mates and females. The level of statistical significance was set at 5%. Results: In total, 24,780 dental surfaces were evaluated. Among these surfaces, 73.10% did not present dental wear, 24.10% had incipient lesions, 2.46% had moderate lesions and 0.34% had been restored. No severe lesions were detected. Tooth wear was mainly seen on the occlusal/incisal surfaces (26.55%), involving enamel or enamel-dentine, but not the secondary dentine or pulp. The prevalence of dental wear was 26.90%. Considering the different teeth, wear was present in 53.22% of incisors, 50.51% of canines, 10.17% of premolars and 10.85% of molars. The prevalence of the different degrees of dental wear was similar in mates and females (P > 0.05). Conclusion: The modified TWI seems to bean effective toot for use in broad epidemiological surveys, due to easier calibration and high reproducibility rates. (C) 2008 The Royal Institute of Public Health. Published by Elsevier Ltd. All rights reserved.