A review of laser applications in orthodontics.

Laser technique now is widely applied in orthodontic treatment and proved to have many benefits. Soft tissue lasers can be used to perform gingivectomy, frenectomy and surgical exposure of tooth with less bleeding and swelling, improved precision, reduced pain and less wound contraction. Other laser applications include enamel etching and bonding and bracket debonding. Lower level lasers have the potential effects of pain control and accelerating tooth movement. Clinicians must be aware of the safety issues and risks associated with laser and receive proper training before the laser treatment is started.

Analysis of the association of COL2A1 and IGF-1 with mandibular prognathism in a Chinese population.

OBJECTIVE: In this study, we performed a case-control association analysis to determine whether the candidate genes COL2A1 and IGF-1 are susceptibility genes for mandibular prognathism (MP). METHODS: Eleven and five single-nucleotide polymorphisms (SNPs) located in COL2A1 and IGF-1, respectively, were selected and genotyped in 211 cases and 224 controls. The individual SNPs and the relevant haplotypes were analyzed and tested for an association with MP, to identify genes potentially associated with MP. RESULTS: In the analysis of individual SNPs, the SNP rs1793953 in the COL2A1 gene showed a possible association with MP with regard to allelic frequency and genotypic distribution (p = 0.031; p = 0.025, respectively) in the 211 cases and 224 controls. The A allele of rs1793953 was associated with a significantly decreased risk of MP (OR: 0.74; 95% CI: 0.58-0.97). Linkage disequilibrium and haplotype analysis revealed that MP was not associated with haplotypes that included the rs1793953 alleles. IGF-1 gene did not show the association with MP. CONCLUSION: An association between polymorphism in the COL2A1 gene and MP was observed. The results suggested that the COL2A1 gene could be a new susceptibility gene for use in the study of genetic risk factors for MP.

Aetiology of supernumerary teeth: a literature review.

BACKGROUND: Supernumerary teeth are teeth, or tooth-like structures that have either erupted or remain unerupted in addition to the 20 primary and 32 permanent teeth. AIMS: This paper attempts to (a) provide an overview of the proposed hypotheses and the current understanding of the aetiology of supernumerary teeth, and (b) review the published cases of supernumerary teeth occurring in families. REVIEW: No studies have been able to distinguish between different aetiologies for the different locations of supernumerary teeth, while, from a developmental or molecular perspective, the proposed hypotheses may be plausible and explains the origin of different types of supernumerary teeth. CONCLUSION: The only clearly evident feature, based on the existing published reports, is that it is logical to state that supernumerary teeth have a genetic component in their aetiology.

Effect of different advancement positions on the maximum retrusive force of the mandible.

INTRODUCTION: Functional appliances lead, in different degrees, to loss of anchorage in the lower arch. By anchoring them to the mandibular bone, any dental side effects may be avoided and the skeletal effect enhanced. Stability of bone-borne fixation would be affected by forces created by the pull of the masticatory muscles. We aimed to identify mean maximum forces produced by mandibular retrusive muscles, at different degrees of advancement. SUBJECTS AND METHODS: Eighteen healthy adult volunteers participated in the study. Maximum retrusive force was measured using a splint/load cell system. Readings of the maximum forces of retrusion were taken from five mandibular positions: unstrained retruded position, and 4, 5, 6, and 7 mm anterior to the unstrained position. Data were presented as means ± SD and anova was performed to examine statistical significant differences between means of the maximum retrusion force. RESULTS: Mean maximum retrusion force ranged between 63.3 and 198.2 newtons at the unstrained and 7 mm positions, respectively. It increased as the distance of advancement increased, being statistically significantly (p < 0.05) less at unstrained position compared with all advancement distances, 4 mm of advancement than 6 and 7 mm advancement, 5 mm of advancement than at 7 mm advancement. CONCLUSION: Magnitude of the forces exerted by muscles during voluntary maximum retrusion movement from different advancement positions increased proportionately as the retrusion distance increased up to 7 mm. Such range of high forces might be important to consider when designing a bone-borne functional appliance.

Diagnostic tools used to predict the prevalence of supernumerary teeth: a meta-analysis.

OBJECTIVES: This study sought to (i) determine the variations in prevalence figures based on the diagnostic tools employed, and (ii) provide an insight into the prevalence of supernumerary teeth. METHODS: A comprehensive literature search of the prevalence reports on supernumerary teeth was conducted using two databases. Two independent observers rated these articles according to exclusion and inclusion criteria. 28 papers were included in the analysis to determine the variations in the prevalence figures in relation to the method of diagnosis, and 14 studies were included to estimate the prevalence figures for supernumerary teeth. Statistical analysis was computed using analysis of variance (ANOVA), Student Neumann-Keuls (SNK) test and multiple regression analysis. RESULTS: Statistically significant differences were evident in the prevalence figures based only on a clinical examination compared with groups that also employed radiographs (p < 0.05, ANOVA, SNK). The prevalence figures for supernumerary teeth ranged from 0% to 3%. The mean prevalence value for the European white population [1.6% (±0.6)] was lower than that of the southern Chinese population [2.7% (±0.14)]. The overall prevalence of supernumerary teeth for males was significantly higher than for females [relative risk = 1.37 (1.13-1.50)]. CONCLUSIONS: Clinical examination plus some types of radiograph(s) are essential for determining the prevalence of supernumerary teeth; nevertheless, it is still underestimated. Several disparities in the prevalence reports make the available data on supernumerary teeth questionable.

Resveratrol inhibits periodontal pathogens in vitro.

The gram-negative anaerobic bacteria A. actinomycetemcomitans (Aa) and P. gingivalis (Pg) are key components in the aetiology of periodontal disease, and associated hard-tissue destruction. Resveratrol is a phytoalexin, produced naturally by several plants when under attack by bacterial or fungal pathogens. It is found in many foods including mulberries, peanuts and the skin of labrusca and muscadine grapes. The objective of this study was to evaluate the effect of resveratrol on the in vitro growth of periodontal pathogens Aa and Pg. For comparison, resveratrol's effect on a variety of other oral microorganisms was also evaluated. Resveratrol demonstrates a poor solubility in water, thus different concentrations of resveratrol in the solvent dimethyl sulphoxide (DMSO) were added to calibrated suspensions of Aa and Pg. As a control, a parallel series of dilutions containing the vehicle DMSO alone was made to measure the effect of the solvent. Minimum inhibitory concentrations of the periodontal pathogens were calculated. All suspensions were incubated for 1, 3, 6 and 24 h in an anaerobic chamber at 37 °C. At each time interval, selected dilutions from each culture broth were plated on blood agar plates. Colonies appearing on blood agar plates were visually counted at 3 days for Aa, and at 5 days for Pg. The periodontal bacteria showed a significant decrease (p < 0.05) in viable counts after 1 h, whilst no colony forming units could be observed after 24 h. The results suggest that resveratrol possesses significant antimicrobial properties on periodontal pathogens in vitro.

Effects of vascular endothelial growth factor (VEGF) on MC3T3-E1.

UNLABELLED: Osteogenesis and angiogenesis are closely correlated. Vascular endothelial growth factor (VEGF) is believed to play a critical role in skeletal development. OBJECTIVE: To investigate whether VEGF has direct effects on bone cells activities and to better understand how VEGF promotes bone remodeling. MATERIALS AND METHODS: MC3T3-E1 cell line was cultured with and without VEGF in vitro. The cells in both control and test groups were collected at different culture time points of 24, 48 and 72 h. Real-time polymerase chain reaction (qPCR) was carried out to quantify the mRNA expression of VEGF receptor (VEGFR2), alkaline phosphatase (ALP) and osteocalcin (OCN), osteoprotegerin (OPG) and receptor activator of nuclear factor kappa ß ligand (RANKL). RESULTS: The expression of VEGFR2 significantly increased by 53% at 24 h and remained increased by 8% at 72 h compared to control (p < 0.05). ALP showed an early increase by 73% at 24 h (p < 0.001), but dropped by 14 and 41% at 48 and 72 h, respectively (p < 0.05). OCN was down-regulated by 41% at 24 h but then up-regulated by 149% at 72 h (p < 0.001). The expression of OPG significantly decreased by 7% at 24 h (p < 0.001) while dramatically increased by 133% at 72 h (p < 0.001). RANKL remained unchanged at all three time points (p > 0.05). CONCLUSION: VEGF promotes bone remodeling by direct effects on osteoblastic cells via regulating gene expression of ALP, OCN, and OPG through VEGFR2 signaling pathway.

Genes, genetics, and Class III malocclusion.

To present current views that are pertinent to the investigation of the genetic etiology of Class III malocclusion. Class III malocclusion is thought to be a polygenic disorder that results from an interaction between susceptibility genes and environmental factors. However, research on family pedigrees has indicated that Class III malocclusion might also be a monogenic dominant phenotype. Recent studies have reported that genes that encode specific growth factors or other signaling molecules are involved in condylar growth under mechanical strain. These genes, which include Indian hedgehog homolog (IHH), parathyroid-hormone like hormone (PTHLH), insulin-like growth factor-1 (IGF-1), and vascular endothelial growth factor (VEGF), and variations in their levels of expression play an important role in the etiology of Class III malocclusion. In addition, genome-wide scans have revealed chromosomal loci that are associated with Class III malocclusion. It is likely that chromosomal loci 1p36, 12q23, and 12q13 harbor genes that confer susceptibility to Class III malocclusion. In a case-control association study, we identified erythrocyte membrane protein band 4.1 (EPB41) to be a new positional candidate gene that might be involved in susceptibility to mandibular prognathism. Most of the earlier studies on the genetic etiology of Class III malocclusion have focused on the patterns of inheritance of this phenotype. Recent investigations have focused on understanding the genetic variables that affect Class III malocclusion and might provide new approaches to uncovering the genetic etiology of this phenotype.

Effect of bio-oss collagen and collagen matrix on bone formation.

OBJECTIVE: to compare the amount of new bone produced by Bio-Oss((R)) Collagen to that produced by collagen matrix in vivo. METHOD: eighteen bone defects, 5mm by 10mm were created in the parietal bone of 9 New Zealand White rabbits. 6 defects were grafted with Bio-Oss((R)) Collagen. 6 defects were grafted with collagen matrix alone (positive control) and 6 were left empty (negative control). Animals were killed on day 14 and the defects were dissected and prepared for histological assessment. Quantitative analysis of new bone formation was made on 100 sections (50 sections for each group) using image analysis. RESULTS: A total of 339% more new bone was present in defects grafted with Bio-Oss((R)) Collagen than those grafted with collagen matrix (positive control). No bone was formed in the negative control group. CONCLUSION: Bio-Oss((R)) Collagen has the effect of stimulating new bone formation locally compared with collagen matrix in vivo. Bio-Oss((R) )Collagen may be utilized as a bone graft material.

Effect of Buguzhi (Psoralea corylifolia fruit) extract on bone formation.

The objective of the study is to compare the amount of new bone produced by Buguzhi (Psoralea corylifolia fruit) extract in collagen matrix to that produced and collagen matrix in vivo. Eighteen bone defects, 5 mm by 10 mm, were created in the parietal bone of 9 New Zealand white rabbits. Six defects were grafted with Buguzhi extract mixed with collagen matrix. Six defects were grafted with collagen matrix alone (positive control) and 6 were left empty (negative control). Animals were sacrificed on day 14 and the defects were dissected and prepared for histological assessment. Quantitative analysis of new bone formation and bone cells was made on 100 sections (50 sections for each group) using image analysis. A total of 275% more new bone was present in defects grafted with Buguzhi extract in collagen matrix than those grafted with collagen matrix. No bone was formed in the negative control group. The amount of bone cells was also significantly greater in the Buguzhi group than in the positive control group. To conclude, Buguzhi extract in collagen matrix has the effect of increasing new bone formation locally in vivo. Buguzhi extract in collagen matrix can be used as a bone graft material.

Inhibitory effect of quercetin on periodontal pathogens in vitro.

Actinobacillus actinomycetemcomitans (Aa) and Porphyromonas gingivalis (Pg) are bacteria strongly associated with early onset, progressive and refractory periodontal disease and associated alveolar bone loss. Quercetin is a flavonoid found in many foods including apples, onions and tea. The aim of this study was to evaluate the effect of quercetin on in vitro growth of periodontal pathogens Aa and Pg. For comparison, quercetin's effect on several oral microbes was also evaluated. Different concentrations of quercetin solution were added to calibrated suspensions of Aa and Pg. All suspensions were incubated for 1, 3, 6, and 24 h in an anaerobic chamber at 37 degrees C. At each time point, selected dilutions from each culture broth were plated on blood agar plates. Colonies appearing on blood agar plates were visually counted on 3 days for Aa and 5 days for Pg. Minimum inhibitory concentrations of both periodontal pathogens were also determined. Both periodontal bacteria showed a significant decrease (p < 0.05) in viable counts after 1 h. No colony forming units of Pg could be observed after 24 h. The results suggest that quercetin possesses significant antimicrobial properties on periodontal pathogens in vitro.

Does orthodontic tooth movement cause an elevation in systemic inflammatory markers?

SUMMARY: The aim of this study was to evaluate the effects of orthodontic treatment on systemic levels of the inflammatory markers, C-reactive protein (CRP), tumour necrosis factor-alpha (TNF-alpha), and interleukin-6 (IL-6). The study group comprised 11 girls and 6 boys (mean age 13.1 years) treated with fixed appliances and distalizing headgear. Venous blood samples were taken from the cubital vein of each subject before treatment (T0) and then at three further time points during treatment (T1-T3), 2 months apart. The sera from these blood samples were analysed using enzyme-linked immunosorbent assay (ELISA) assay technology for CRP, TNF-alpha, and IL-6 concentration levels. Data were compared between baseline and subsequent sequential time points using a Mann-Whitney test for non-normally distributed variables. The results showed that there was no significant elevation of any of the three inflammatory markers at any of the time points. This research provides evidence that conventional orthodontic treatment is not associated with a systemic immune response in the factors investigated.

Factors regulating endochondral ossification in the spheno-occipital synchondrosis.

OBJECTIVES: To identify the temporal pattern of core-binding factor alpha1 (Cbfa1) and vascular endothelial growth factor (VEGF) expressions in the spheno-occipital synchondrosis in vitro with and without tensile stress. MATERIALS AND METHODS: Sixty male BALB/c mice were randomly divided into an experimental group (with tensile stress) and a control group (without tensile stress) at each of five time points. Animals were sacrificed and the cranial base synchondroses were aseptically removed. In the experimental groups, mechanical stress was applied on the surgical explants with helical springs and incubated as organ culture for 6, 24, 48, 72, and 168 hours. In the control group, the springs were kept at zero stress. Tissue sections were subjected to immunohistochemical staining for quantitative analysis of Cbfa1 and VEGF expression. RESULTS: Quantitative analysis revealed that Cbfa1 and VEGF expressions reached a peak increase at 24 and 48 hours, respectively. Compared with the control groups, both Cbfa1 and VEGF were expressed consistently higher in the experimental groups at all time points. CONCLUSION: Mechanical stress applied to the spheno-occipital synchondrosis elicits Cbfa1 expression and subsequently up-regulates the expression of VEGF. Increased levels of expression of both factors could play a role in the growth of the spheno-occipital synchondrosis.

Effect of quercetin on preosteoblasts and bone defects.

Quercetin is a flavonol, also a phytoestrogen, available commonly in onion and apple. Our laboratory investigated its effect on MC3T3-E1 cells' alkaline phosphatase activity in vitro and compared the amount of new bone produced by quercetin in collagen matrix to that produced by bone grafts and collagen matrix in vivo. Four bone defects, 5mm by 10mm were created in the parietal bone of 2 New Zealand White rabbits. In the experimental animal, 2 defects were grafted with quercetin solution mixed with collagen matrix. In the control animal, 2 defects were grafted with collagen matrix alone. Animals were killed on day 14 and the defects were dissected and prepared for histological qualitative assessment. Results showed that 10muM of quercetin increased alkaline phosphatase activity of MC3T3-E1 cells at 72 hours in vitro by 32%. In the experimental animal, there was new bone growing inside the bone defects. In conclusion, specific concentration of quercetin increased alkaline phosphatase activity of MC3T3-E1 cells in vitro and quercetin in collagen matrix has the effect of forming new bone across bone defects in vivo.

Local massage with topical analgesic, a novel treatment modality for temporomandibular muscular pain, a case study report of 5 consecutive cases.

INTRODUCTION: Temporomandibular disorders (TMDs) represent a group of painful conditions involving the muscles of mastication and the temporomandibular joint. Ping On Ointment has been used in the Chinese Orthopedics as a soothing massage balm for muscular aches, strain and sprain. If topical application of the ointment can be effective for the treatment of TMD muscular pain, it may be the long-sought-after method for safe, simple, cheap, non-invasive, and effective treatment modality of TMD muscular pain. PURPOSE: This report documented a case study of the first five consecutive cases using this treatment modality. RESULTS: All cases resulted in complete remission of pain within one month of topical massage. CONCLUSION: This treatment method has high potential to benefit a significant number of people and randomized control trials should be performed.

Inhibitory effect of quercetin on periodontal pathogens.

INTRODUCTION: Periodontal disease and associated bone loss can severely hinder orthodontic treatment. Actinobacillus actinomycetemcomitans (Aa) and Porphyromonas gingivalis (Pg) are bacteria which are strongly associated with this type of bone loss. Quercetin, a unique flavonoid, which is found in many common foods including apples, onions and tea may have a effect against these bacteria. AIMS: To study the effect of quercetin on the in vitro growth of periodontal pathogens Aa and Pg. MATERIAL AND METHODS: The antimicrobial effects were determined in vitro using a broth dilution assay. Aa and Pg were grown to a density of 10(7) to 10(8) cfu/mL and subsequently incubated with test solutions of quercetin at different concentrations (0.025 g/mL, 0.05 g/mL, and 0.1 g/ mL). 0.2% chlorhexidine was used as the positive control and 0.9% sodium chloride (NaCl) as the negative control. Aliquots for the growth assay were taken as soon as the solutions were mixed, and after 1, 3, 6, and 24 hours of incubation in an anaerobic chamber for Aa and Pg. Colonies appearing on the blood agar plates were visually counted after three days for Aa and 5 days for Pg. RESULTS: This study demonstrated that quercetin is a potent antimicrobial agent. When Aa and Pg were incubated with quercetin, their growth began to be inhibited at 1 hour. Aa, shows a transient inhibitory effect for 1 to 12 hours after which the antimicrobial effect gradually decreasds. With Pg, the effect increased with time and complete inhibition was achieved with concentrations of 0.1 g/mL, 0.05 g/mL and 0.025 g/mL by 24 hours. No significant difference was found between the chlorhexidine group and the quercetin solution after 24 hours of incubation. CONCLUSION: Quercetin has an inhibitory effect on Aa and Pg.

Effect of Danshen extract on bone formation.

BACKGROUND: Danshen is a traditional Chinese medicine used for treatment of cardiac diseases through improving blood circulation. The authors' laboratory compared the amount of new bone formed in collagen matrix with Danshen extract with that produced by bone graft and collagen matrix alone. METHODS: Eighteen bone defects, 5 mm x 10 mm were created in the parietal bone of nine New Zealand White rabbits. In the experimental group, six defects were grafted with a collagen matrix with Danshen extract. In the control groups, six defects were grafted with collagen matrix alone (active control) and six were left empty (passive control). The animals were killed on day 14 and the defects were dissected and prepared for histological assessment. Serial sections were cut across each defect. Quantitative analysis of new bone formation was made on 100 sections (50 sections for each group) using image analysis. RESULTS: A total of five times more new bone was present in defects grafted with Danshen extract in a collagen matrix than those grafted with collagen matrix alone. Very little new bone was formed in the passive control group. CONCLUSIONS: Danshen extract in collagen matrix has the effect of increasing new bone formation locally and can be used for bone grafting especially in cases with compromised vascular responses.

Effect of Salvia miltiorrhiza extract on bone formation.

Salvia miltiorrhiza (SM) is a Chinese medicine used for treatment of cardiac diseases through improving blood circulation. Our laboratory compared the amount of new bone formed in collagen matrix with SM extract to that formed in the collagen matrix alone. Eighteen bone defects, 5 mm x 10 mm were created in the parietal bone of nine New Zealand White rabbits. In the experimental group, six defects were grafted with collagen matrix with SM extract. In the control groups, six defects were grafted with collagen matrix alone (positive control) and six were left empty (negative control). Animals were killed on day 14 and the defects were dissected and prepared for histological assessment. Serial sections were cut across each defect. Quantitative analysis of new bone formation was made on 100 sections (50 sections for each group of SM and positive control) using image analysis. A total of 478% more new bone was present in defects grafted with SM extract in collagen matrix than those grafted with the collagen matrix alone. Very little new bone was formed in the passive control group. In conclusion, SM extract in collagen matrix has the effect of increasing new bone formation locally and can be used for bone grafting especially in cases with compromised vascular responses.

VEGF: an essential mediator of both angiogenesis and endochondral ossification.

During bone growth, development, and remodeling, angiogenesis as well as osteogenesis are closely associated processes, sharing some essential mediators. Vascular endothelial growth factor (VEGF) was initially recognized as the best-characterized endothelial-specific growth factor, which increased vascular permeability and angiogenesis, and it is now apparent that this cytokine regulates multiple biological functions in the endochondral ossification of mandibular condylar growth, as well as long bone formation. The complexity of VEGF biology is paralleled by the emerging complexity of interactions between VEGF ligands and their receptors. This narrative review summarizes the family of VEGF-related molecules, including 7 mammalian members, namely, VEGF, placenta growth factor (PLGF), and VEGF-B, -C, -D, -E, and -F. The biological functions of VEGF are mediated by at least 3 corresponding receptors: VEGFR-1/Flt-1, VEGFR-2/Flk-1, VEGFR-3/Flt-4 and 2 co-receptors of neuropilin (NRP) and heparan sulfate proteoglycans (HSPGs). Current findings on endochondral ossification are also discussed, with emphasis on VEGF-A action in osteoblasts, chondroblasts, and chondroclasts/osteoclasts and regulatory mechanisms involving oxygen tension, and some growth factors and hormones. Furthermore, the therapeutic implications of recombinant VEGF-A protein therapy and VEGF-A gene therapy are evaluated. Abbreviations used: VEGF, Vascular endothelial growth factor; PLGF, placenta growth factor; NRP, neuropilin; HSPGs, heparan sulfate proteoglycans; FGF, fibroblast growth factor; TGF, transforming growth factor; HGF, hepatocyte growth factor; TNF, tumor necrosis factor; ECM, extracellular matrix; RTKs, receptor tyrosine kinases; ERK, extracellular signal kinases; HIF, hypoxia-inducible factor.

A new approach to control condylar growth by regulating angiogenesis.

OBJECTIVE: To provide a comprehensive review of the mechanisms of growth of mandibular condyle, the roles of angiogenesis enhancers and inhibitors during endochondral ossification in mandibular condyle and newly developed delivery methods for local gene delivery that may represent strategies to regulate condylar growth. DESIGN: Narrative review. RESULTS: Angiogenesis is the crucial step in mandibular condylar growth for it regulates the transformation from cartilage to bone. Angiognesis enhancers, especially VEGF and FGF, play important roles in the process of new blood lumen formation and invasion. On the other hand, angiostatin and endostatin inhibit angiogenesis by targeting endothelial cells and several signal cascades. Delivery methods such as liposomes, stem cells and virus vectors have been studied. Recombinant AAV-mediated gene therapy is considered as one of the most promising strategies of condylar growth management. CONCLUSION: AAV-mediated gene therapy using VEGF or angiogenesis inhibitor will be a promising way to regulate condylar growth at an early stage.