Predictors of favorable soft tissue profile outcomes following Class II Twin-block treatment.

OBJECTIVE: The aim of this study was to determine cephalometric factors that help predict favorable soft-tissue profile outcomes following treatment with the Class II Twin-block appliance. METHODS: Pre- and post-treatment lateral cephalograms of 45 patients treated with the Class II Twin-block appliance were retrospectively analyzed. Profile silhouettes were drawn from the cephalograms and evaluated by three orthodontists in order to determine the extent of improvement. Samples were divided into a favorable group (upper 30% of visual analogue scale [VAS] scores, n = 14) and an unfavorable group (lower 30% of VAS scores, n = 14). Skeletal and soft-tissue measurements were performed on the cephalograms and an intergroup comparison was conducted. RESULTS: An independent t-test revealed that the following pre-treatment values were lower in the favorable group compared to the unfavorable group: lower incisor to mandibular plane angle, lower incisor to pogonion distance, point A-nasion-point B angle, sella-nasion line (SN) to maxillary plane angle, SN to mandibular plane angle, gonial angle, and symphysis inclination. The favorable group had a larger incisor inclination to occlusal plane. Moreover, the favorable group showed larger post-treatment changes in gonial angle, B point projection, and pogonion projection than did the unfavorable group. CONCLUSIONS: Class II malocclusion patients with a low divergent skeletal pattern and reduced lower incisor protrusions are likely to show more improvement in soft-tissue profile outcomes following Class II Twin-block treatment.

Analysis of midpalatal miniscrew-assisted maxillary molar distalization patterns with simultaneous use of fixed appliances: A preliminary study.

Skeletal anchorage-assisted upper molar distalization has become one of the standard treatment modalities for the correction of Class II malocclusion. The purpose of this study was to analyze maxillary molar movement patterns according to appliance design, with the simultaneous use of buccal fixed orthodontic appliances. The authors devised two distinct types of midpalatal miniscrew-assisted maxillary molar distalizers, a lingual arch type and a pendulum type. Fourteen patients treated with one of the two types of distalizers were enrolled in the study, and the patterns of tooth movement associated with each type were compared. Pre- and post-treatment lateral cephalograms were analyzed. The lingual arch type was associated with relatively bodily upper molar distalization, while the pendulum type was associated with distal tipping with intrusion of the upper molar. Clinicians should be aware of the expected tooth movement associated with each appliance design. Further well designed studies with larger sample sizes are required.

Uprighting mesially impacted mandibular molars with 2 miniscrews.

Mesially tilted or impacted mandibular molars cause occlusal disharmony and periodontal problems. For proper restoration of the occlusion and to prevent further periodontal damage, uprighting of tilted molars is the recommended treatment option. Although several orthodontic methods including miniscrews have been proposed, most of them have innate limitations and problems such as the possibility of unwanted tooth movement. In this case series, we introduce a new system that uses 2 miniscrews with slots that can accommodate rectangular orthodontic wires to 3 dimensionally control the tilted molar in 3 patients. We also discuss the advantages and possible disadvantages of this new system.

Induction of S100A4 in periodontal ligament cells enhances osteoclast formation.

BACKGROUND: An increase in the expression of S100A4 has been reported in various inflammatory diseases. However, little is known about the association between periodontal inflammation and S100A4 expression. The aims of this study were to investigate changes in S100A4 expression in human periodontal ligament (hPDL) cells in response to inflammatory stimuli and to describe a possible mechanism underlying the change. METHOD: Human PDL cells were treated with lipopolysaccharide (LPS) and the level of S100A4 was analyzed by real-time RT-PCR and Western blotting. LPS was added to co-cultures of hPDL and osteoclast progenitor cells under osteoclastogenic condition and the formation of osteoclasts was assessed. Alternatively, progenitor cells were directly treated with recombinant S100A4 for evaluation of osteoclastogenesis. The activity of nuclear factor kappaB (NFκB) was examined by Western blotting for phosphorylated forms of inhibitor kappaB (IκB) and p65. An NFκB inhibitor was added to the culture of hPDL cells with LPS and the level of S100A4 was measured by real-time RT-PCR. RESULTS: We found that LPS stimulation resulted in a significant increase of S100A4 expression in hPDL cells. S100A4 protein secretion from hPDL cells was also increased. The enhanced expression of S100A4 in hPDL cells under inflammatory conditions led to stimulation of the generation of osteoclasts. In addition, direct S100A4 treatment stimulated osteoclastogenesis. The underlying mechanism for the increased S100A4 expression in hPDL cells was activation of the NFκB signaling pathway. CONCLUSION: Our results suggest that bone destruction in periodontitis might be associated with increased S100A4 expression in hPDL cells.

Effects of moderate intensity static magnetic fields on human bone marrow-derived mesenchymal stem cells.

This study aimed to explore effects of static magnetic fields (SMFs) of moderate intensity (3-50 mT) as biophysical stimulators of proliferation and osteoblastic differentiation of human bone marrow-derived mesenchymal stem cells (MSCs). MSCs were exposed to SMFs of three intensities: 3, 15, and 50 mT. Proliferation was assessed by cell counting and bromodeoxyuridine incorporation, and differentiation by measuring alkaline phosphatase (ALP) activity, calcium content, mineralized nodule formation, and transcripts of osteogenic markers. Moderate intensity SMFs increased cell proliferation, ALP activity, calcium release, and mineralized nodule formation in a dose- and time-dependent manner, which peaked at 15 mT. In the same manner, they upregulated expression of osteogenic marker genes such as ALP, bone sialoprotein 2 (BSP2), collagen1a1 (COL1a1), osteocalcin (OCN), osteonectin (ON), osteopontin (OPN), osterix (OSX), and runt-related transcription factor 2 (RUNX2) with peak at 15 mT after 14 or 21 days of exposure. Results demonstrate that moderate intensity SMFs promote proliferation and osteoblastic differentiation of MSCs. This effect could help to improve MSC responses during osseointegration between a dental implant and surrounding bone.

Asymmetric transverse control of maxillary dentition with two midpalatal orthodontic miniscrews.

There have been several orthodontic modalities for maxillary transverse control with most addressing symmetric control. The asymmetric transverse control of maxillary dentition is challenging to orthodontists due to the lack of certain modalities and possible dental side effects. Skeletal anchorages provide biomechanics without orthodontic side effects, but reports of their utilization for transverse control of maxillary dentition are scarce. The purpose of this article is to introduce a novel method utilizing two midpalatal orthodontic miniscrews and a connecting wire system for the asymmetric transverse control of maxillary dentition. Records of two patients consecutively treated with this system are reported, and the related biomechanical considerations are presented.

Alveolar bone turnover and periodontal ligament width are controlled by Wnt.

BACKGROUND: The molecular signals responsible for maintaining homeostatic control over the periodontal ligament (PDL) are unknown. The purpose of this study is to investigate the role of Wnt signaling in this process using gain- and loss-of-function approaches. METHODS: The function of endogenous Wnt signal in the PDL was evaluated in Lrp5(ACT) mice in which a mutation in the low-density lipoprotein receptor-related protein 5 Wnt coreceptor causes constitutive activation of Wnt signaling, and in adenovirus Dkk1-treated mice in which overexpression of the Wnt inhibitor Dkk1 causes transient Wnt signal inhibition. PDL in both animal models was examined using histology and immunohistochemical analyses for osteopontin, runt-related transcription factor 2 (Runx2), fibromodulin, osterix, ki67, receptor activator of nuclear factor-κB ligand (RANKL), and alkaline phosphatase activity. RESULTS: Lrp5(ACT) mice exhibited a significant narrowing of the PDL space caused by an increase in osteogenic gene expression, a reduction in RANKL expression and osteoclast activity, and an increase in alveolar bone formation. Conversely, adenovirus Dkk1-treated mice showed decreased expression of osteogenic markers, coupled with an increase in osteoclast activity, which resulted in a slight increase in PDL width. CONCLUSION: The Wnt pathway is involved in the homeostatic control of the PDL, and conditions that elevate or repress Wnt signaling alter the expression of osteogenic genes within the PDL space, which in turn affects its overall width.

Downregulation of Wnt causes root resorption.

INTRODUCTION: There are multiple causes of external root resorption, but absent a disease state, it is most often observed when excessive physical force is used during orthodontic treatment. Even without mechanical stimulation, however, root resorption can still occur. The purpose of this study was to test whether Wnt signaling plays a role in pathologic root resorption, by conditionally deleting Wntless (Wls) from odontoblasts and osteoblasts and then evaluating the phenotypic effects on the maintenance of the root surface. METHODS: Ten (age, 1 month) and 20 (age, 3 months) OCN-Cre;Wls(fl/fl) mice and their wild-type littermates were evaluated using microcomputed tomography, histology, and immunohistochemistry. Phenotypic alterations in the alveolar bone, dentin, and cementum were characterized and quantified. RESULTS: In a genetic model of reduced Wnt signaling, we found that RANKL expression is upregulated, and osteoprotegerin expression is downregulated. This molecular disruption results in an increase in osteoclast activity, a decrease in osteoblast activity, and extensive, spontaneous root resorption. A genetic strain of mice in which Wnt signaling is elevated exhibits thicker cementum, whereas, even in the perinatal period, OCN-Cre;Wls(fl/fl) mice exhibit thinner cementum. CONCLUSIONS: Taken together, these data demonstrate that Wnts regulate cementum homeostasis, and that idiopathic cases of root resorption might have as their etiology a reduction in endogenous Wnt signaling.

The molecular and cellular effects of ageing on the periodontal ligament.

AIM: Many in vitro studies have investigated age-related biological changes in cells comprising the periodontium but the basic question of whether the periodontium can maintain its integrity with age remains unanswered. Thus, the aim of this study was to understand how, in the absence of disease, advancing age impacts the structure of the periodontium. MATERIALS AND METHODS: Of 4, 10, 25, and 50-week-old mice were examined using histology and immunohistochemical analyses for cell proliferation, cell turnover, collagen quantity and quality, osteogenic markers, bone turnover, and cytokine expression. RESULTS: The periodontal ligament (PDL) space shows a gradual decrease in width over the lifespan of the mice. Cell proliferation as well as the quantity and quality of collagen fibres decreased with age although cell density did not appear to be altered. Osteoprogenitor markers in the PDL maintained their expression with increasing age. Alkaline phosphatase (ALP) activity decreased, but osteoclast activity increased with age. CONCLUSIONS: Ageing is associated with a decline in the quality and quantity of collagen and an increase in bone resorption, all of which can diminish the function of the periodontium even in the absence of disease.

The effects of TMJ symptoms on skeletal morphology in orthodontic patients with TMJ disc displacement.

OBJECTIVE: The aim of this study was to investigate the effects of temporomandibular joint (TMJ) symptoms on skeletal morphologies of orthodontic patients with TMJ disc displacement (DD). MATERIALS AND METHODS: The sample consisted of 197 women seeking orthodontic treatment. The subjects were divided into two groups according to the presence of TMJ symptoms: the presence and absence of TMJ symptoms. Each group was sub-divided into three groups based on magnetic resonance images of bilateral TMJs: bilateral normal disc position (BN), bilateral disc displacement with reduction (DDR) and bilateral disc displacement without reduction (DDNR). Seventeen variables from lateral cephalograms were analyzed by two-way analysis of variance to identify differences in skeletal morphologies with respect to TMJ symptoms and TMJ DD status. RESULTS: Patients with TMJ DD were more likely to have short ramus height, short mandibular body length and backward positioning of the ramus and mandible. These skeletal morphologies became more severe as TMJ DD progressed to DDNR. However, the skeletal morphologies associated with TMJ DD were not significantly different between symptomatic and asymptomatic patients. As a result, patients with TMJ DD had backward positioning and clockwise rotation compared to those with bilateral normal TMJs, irrespective of the presence of TMJ symptom. CONCLUSIONS: This study suggests that TMJ DD is associated with altered skeletal morphology, but TMJ symptoms do not significantly influence the relationships between TMJ DD and skeletal morphology.

Wnt signaling regulates pulp volume and dentin thickness.

Odontoblasts, cementoblasts, ameloblasts, and osteoblasts all form mineralized tissues in the craniofacial complex, and all these cell types exhibit active Wnt signaling during postnatal life. We set out to understand the functions of this Wnt signaling, by evaluating the phenotypes of mice in which the essential Wnt chaperone protein, Wntless was eliminated. The deletion of Wls was restricted to cells expressing Osteocalcin (OCN), which in addition to osteoblasts includes odontoblasts, cementoblasts, and ameloblasts. Dentin, cementum, enamel, and bone all formed in OCN-Cre;Wls(fl/fl) mice but their homeostasis was dramatically affected. The most notable feature was a significant increase in dentin volume and density. We attribute this gain in dentin volume to a Wnt-mediated misregulation of Runx2. Normally, Wnt signaling stimulates Runx2, which in turn inhibits dentin sialoprotein (DSP); this inhibition must be relieved for odontoblasts to differentiate. In OCN-Cre;Wls(fl/fl) mice, Wnt pathway activation is reduced and Runx2 levels decline. The Runx2-mediated repression of DSP is relieved and odontoblast differentiation is accordingly enhanced. This study demonstrates the importance of Wnt signaling in the homeostasis of mineralized tissues of the craniofacial complex.