Enamel etching for bonding fixed orthodontic braces.

BACKGROUND: Acid etching of tooth surfaces to promote the bonding of orthodontic attachments to the enamel has been a routine procedure in orthodontic treatment since the 1960s. Various types of orthodontic etchants and etching techniques have been introduced in the past five decades. Although a large amount of information on this topic has been published, there is a significant lack of consensus regarding the clinical effects of different dental etchants and etching techniques. OBJECTIVES: To compare the effects of different dental etchants and different etching techniques for the bonding of fixed orthodontic appliances. SEARCH METHODS: We searched the following electronic databases: the Cochrane Oral Health Group's Trials Register (to 8 March 2013), the Cochrane Central Register of Controlled Trials (CENTRAL) (The Cochrane Library 2013, Issue 2), MEDLINE via OVID (to 8 March 2013), EMBASE via OVID (to 8 March 2013), Chinese Biomedical Literature Database (to 12 March 2011), the WHO International Clinical Trials Registry Platform (to 8 March 2013) and the National Institutes of Health Clinical Trials Registry (to 8 March 2013). A handsearching group updated the handsearching of journals, carried out as part of the Cochrane Worldwide Handsearching Programme, to the most current issue. There were no restrictions regarding language or date of publication. SELECTION CRITERIA: Randomized controlled trials (RCTs) comparing different etching materials, or different etching techniques using the same etchants, for the bonding of fixed orthodontic brackets to incisors, canines and premolars in children and adults. DATA COLLECTION AND ANALYSIS: Two review authors extracted data and assessed the risk of bias of included studies independently and in duplicate. We resolved disagreements by discussion among the review team. We contacted the corresponding authors of the included studies to obtain additional information, if necessary. MAIN RESULTS: We included 13 studies randomizing 417 participants with 7184 teeth/brackets. We assessed two studies (15%) as being at low risk of bias, 10 studies (77%) as being at high risk of bias and one study (8%) as being at unclear risk of bias. Self etching primers (SEPs) versus conventional etchantsEleven studies compared the effects of SEPs with conventional etchants. Only five of these studies (three of split-mouth design and two of parallel design) reported data at the participant level, with the remaining studies reporting at the tooth level, thus ignoring clustering/the paired nature of the data. A meta-analysis of these five studies, with follow-up ranging from 5 to 37 months, provided low-quality evidence that was insufficient to determine whether or not there is a difference in bond failure rate between SEPs and convention etchants (risk ratio 1.14; 95% confidence interval (CI) 0.75 to 1.73; 221 participants). The uncertainty in the CI includes both no effect and appreciable benefit and harm. Subgroup analysis did not show a difference between split-mouth and parallel studies.There were no data available to allow assessment of the outcomes: decalcification, participant satisfaction and cost-effectiveness. One study reported decalcification, but only at the tooth level. SEPs versus SEPsTwo studies compared two different SEPs. Both studies reported bond failure rate, with one of the studies also reporting decalcification. However, as both studies reported outcomes only at the tooth level, there were no data available to evaluate the superiority of any of the SEPs over the others investigated with regards to any of the outcomes of this review.We did not find any eligible studies evaluating different etching materials (e.g. phosphoric acid, polyacrylic acid, maleic acid), concentrations or etching times. AUTHORS' CONCLUSIONS: We found low-quality evidence that was insufficient to conclude whether or not there is a difference in bond failure rate between SEPs and conventional etching systems when bonding fixed orthodontic appliances over a 5- to 37-month follow-up. Insufficient data were also available to allow any conclusions to be formed regarding the superiority of SEPs or conventional etching for the outcomes: decalcification, participant satisfaction and cost-effectiveness, or regarding the superiority of different etching materials, concentrations or etching times, or of any one SEP over another. Further well-designed RCTs on this topic are needed to provide more evidence in order to answer these clinical questions.

Porphyromonas gingivalis lipopolysaccharide inhibits the osteoblastic differentiation of preosteoblasts by activating Notch1 signaling.

Although Porphyromonas gingivalis lipopolysaccharide (P-LPS) is known to inhibit osteoblast differentiation, the exact molecular mechanisms underlying this phenomenon remain unclear. Here, we investigated the role of Notch signaling in the osteoblastic differentiation of both MC3T3E-1 cells and primary mouse bone marrow stromal cells (BMSCs). P-LPS stimulation activated the Notch1 signaling cascade and increased expression of the Notch target genes HES1 and HEY1. P-LPS can also act as an inhibitor because it is capable of suppressing Wnt/beta-catenin signaling in preosteoblasts by decreasing both glycogen synthase kinase-3beta (GSK-3beta) phosphorylation and the expression of nuclear beta-catenin. These effects were rescued, however, by inhibiting Notch1 signaling. Furthermore, P-LPS treatment inhibited osteoblast differentiation in preosteoblasts as demonstrated by reductions in alkaline phosphatase activity, osteoblast gene expression, and mineralization, all of which were rescued by suppression of Notch1 signaling. Moreover, inhibition of GSK-3beta, HES1, or HEY1 partially reversed the P-LPS-induced inhibition of osteoblast differentiation. Together, these findings suggest that P-LPS inhibits osteoblast differentiation by promoting the expression of Notch target genes and suppressing canonical Wnt/beta-catenin signaling.

Orthodontic space closure versus prosthetic replacement of missing upper lateral incisors in patients with bilateral cleft lip and palate.

OBJECTIVE: To compare dental aesthetics and function of orthodontic space closure versus prosthetic replacement of upper lateral incisors in patients with bilateral cleft lip and palate. The predominant mode of prosthetic replacement was resin-bonded bridges. PATIENTS AND METHODS: The retrospective study group consisted of 17 patients treated with orthodontic space closure (13 men, four women; median age, 27.1 years; interquartile range, 20.6 to 33.3 years) and 10 patients treated with prosthetic replacement (five men, five women; median age, 27.7 years; interquartile range, 20.9 to 39.7 years). Dental aesthetics were evaluated by the patients and by a professional panel. Mandibular function was evaluated by means of the mandibular function impairment questionnaire. The level of mandibular impairment was calculated using the Function Impairment Rating Scale. RESULTS: With respect to dental aesthetics, no significant differences between patients treated with orthodontic space closure and prosthetic replacement were found. With respect to function, the level of mandibular impairment was significantly higher in patients treated with prosthetic replacement compared with patients treated with orthodontic space closure, as indicated by high scores on specific masticatory functions. CONCLUSION: Orthodontic space closure and prosthetic replacement in bilateral cleft lip and palate patients produce similar results in terms of aesthetics. In terms of function, prosthetic replacement results in significantly more impairment of specific masticatory functions.

Adhesive properties of bonded orthodontic retainers to enamel: stainless steel wire vs fiber-reinforced composites.

PURPOSE: The objectives of this study were to compare the bond strength of a stainless steel orthodontic wire vs various fiber-reinforced composites (FRC) used as orthodontic retainers on enamel, analyze the failure types after debonding, and investigate the influence of different application procedures of stainless steel wires on bond strength. MATERIALS AND METHODS: Caries-free, intact human mandibular incisors (N = 80, n = 10 per group) were selected and randomly distributed into 8 groups. After etching with 37% H3PO4 for 30 s, rinsing and drying, bonding agent (Stick Resin) was applied and light polymerized. Then one of the following FRC materials was applied on the flowable composite (Stick Flow) using standard molds: group 1: Angelus Fibrex Ribbon; group 2: DentaPreg Splint; group 3: ever-Stick Ortho; group 4: Ribbond. In group 5, Quad Cat Wire was applied in the same manner as in FRC groups. In group 6, after applying bonding agent (Stick Resin), Quad Cat Wire was placed directly on the tooth surface and covered with Stick Flow composite. In group 7, after bonding agent (Heliobond) was applied, Quad Cat Wire was placed directly on the tooth surface and covered with Tetric Flow composite. In group 8, after applying bonding agent (Heliobond) and polymerization, Tetric Flow composite was applied, not polymerized, and Quad Cat Wire was placed and covered with Tetric Flow again. Specimens were thermocycled for 6000 cycles between 5 degrees C and 55 degrees C and loaded in a universal testing machine under shear stress (crosshead speed: 1 mm/min) until debonding occurred. The failure sites were examined under an optical light microscope. Data were analyzed using one-way ANOVA and the Tukey-Kramer adjustment test (alpha = 0.05). RESULTS: Significant differences were found between the groups (p = 0.0011) (ANOVA). Bond strength results did not significantly differ either between the FRC groups (groups 1 to 4) (6.1 +/- 2.5 to 8.4 +/- 3.7 MPa) (p > 0.05) or the wire groups (groups 5 to 8) (10.6 +/- 3.8 to 14 +/- 6.7 MPa) (p > 0.05). Failure types varied within the FRC groups, but mainly composite was found left adhered on the enamel surface at varying degrees. In the stainless steel wire groups, when the retainer was applied onto the bonding agent and then covered with flowable resin, partially attached composite on the enamel was often found after debonding. When the wires were embedded in the flowable composite, the Heliobond group (group 8) showed more adhesive failures between the enamel and the composite compared to group 5, where the bonding agent was Stick Resin. CONCLUSION: Regardless of their application mode, stainless steel orthodontic bonded retainers delivered higher bond strengths than those of fiber retainers. The differences were statistically significant compared to those of Angelus Fibrex Ribbon and DentaPreg Splint.

Effect of dental arch convexity and type of archwire on frictional forces.

INTRODUCTION: Friction measurements in orthodontics are often derived from models by using brackets placed on flat models with various straight wires. Dental arches are convex in some areas. The objectives of this study were to compare the frictional forces generated in conventional flat and convex dental arch setups, and to evaluate the effect of different archwires on friction in both dental arch models. METHODS: Two stainless steel models were designed and manufactured simulating flat and convex maxillary right buccal dental arches. Five stainless steel brackets from the maxillary incisor to the second premolar (slot size, 0.22 in, Victory, 3M Unitek, Monrovia, Calif) and a first molar tube were aligned and clamped on the metal model at equal distances of 6 mm. Four kinds of orthodontic wires were tested: (1) A. J. Wilcock Australian wire (0.016 in, G&H Wire, Hannover, Germany); and (2) 0.016 x 0.022 in, (3) 0.018 x 0.022 in, and (4) 0.019 x 0.025 in (3M Unitek GmbH, Seefeld, Germany). Gray elastomeric modules (Power O 110, Ormco, Glendora, Calif) were used for ligation. Friction tests were performed in the wet state with artificial saliva lubrication and by pulling 5 mm of the whole length of the archwire. Six measurements were made from each bracket-wire combination, and each test was performed with new combinations of materials for both arch setups (n = 48, 6 per group) in a universal testing machine (crosshead speed: 20 mm/min). RESULTS AND CONCLUSIONS: Significant effects of arch model (P = 0.0000) and wire types (P = 0.0000) were found. The interaction term between the tested factors was not significant (P = 0.1581) (2-way ANOVA and Tukey test). Convex models resulted in significantly higher frictional forces (1015-1653 g) than flat models (680-1270 g) (P <0.05). In the flat model, significantly lower frictional forces were obtained with wire types 1 (679 g) and 3 (1010 g) than with types 2 (1146 g) and 4 (1270 g) (P <0.05). In the convex model, the lowest friction was obtained with wire types 1 (1015 g) and 3 (1142 g) (P >0.05). Type 1 wire tended to create the least overall friction in both flat and convex dental arch simulation models.

Fluoride release and cariostatic potential of orthodontic adhesives with and without daily fluoride rinsing.

INTRODUCTION: In this study, we aimed to evaluate the fluoride-release profiles and caries lesion development in an enamel model with brackets cemented with 4 orthodontic adhesives with and without daily fluoride exposure. METHODS: Four orthodontic adhesives (Ketac Cem mu, 3M ESPE, Seefeld, Germany; Fuji Ortho LC, GC Corporation, Tokyo, Japan; Light-Bond, Reliance Orthodontic Products, Itasca, Ill; and Transbond XT, 3M Unitek, Monrovia, Calif) were used. Brackets were bonded on bovine enamel with each adhesive (n = 10) and subjected to alternate cycles of demineralizing (pH 4.55) and remineralizing (pH 6.8) solutions. Unbracketed enamel samples served as a reference. Five samples from each group were immersed in a fluoride mouth rinse (250 ppm fluoride) for 1 minute each day (test groups). Fluoride release was measured at regular intervals over 28 days. The mineral distribution of peribracket enamel after 28 days was quantified by transversal microradiographs. RESULTS: Fluoride-release profiles of Ketac Cem mu, Fuji Ortho LC, and Light-Bond were high for the first 24 hours and reached a constant level after 2 weeks. Fuji Ortho LC released significantly more fluoride than did the other adhesives in both the control and test groups (P <0.01, repeated measures ANOVA and Bonferroni test). Enamel bonded with Fuji Ortho LC had significantly shallower lesions and less mineral loss (P <0.01, 2-way ANOVA, and Tukey HSD). CONCLUSIONS: Bonding of orthodontic brackets with Fuji Ortho LC resulted in less peribracket enamel demineralization with and without daily fluoride rinsing, mainly due to its better fluoride-release profile. In contrast, Transbond XT and Light-Bond offered few cariostatic effects to the enamel.

Mechanical tensile stress effects on the expression of bone sialoprotein in bovine cementoblasts.

OBJECTIVE: To develop a new cementoblast culture method and to detect bone sialoprotein (BSP) expression in response to high and low mechanical tensile stress in cementoblast in vitro. MATERIALS AND METHODS: Cementoblasts were collected from the roots of newborn bovine teeth and were identified with cementum-derived attachment protein (CAP) antibody 3G9. Cell proliferation was evaluated by MTT [3-(4,5-dimethylthazol-2-yl)-2,5-diphenyl tetrazolium bromide] assay, and mineralization was confirmed by von Kossa staining. Mechanical tensile stress was applied in vitro to the cementoblast with the use of a uniaxial four-point bending system with 2000 or 4000 microstrains, at a frequency of 0.5 Hz for 3, 6, 12, 24, or 36 hours. BSP mRNA level was quantified by real-time quantitative reverse transcriptase-polymerase chain reaction (qRT-PCR). RESULTS: A large amount of cementoblast was observed to be expressing CAP. Cementoblasts had a proliferation tendency similar to that of osteoblasts but different from that of periodontal ligament (PDL) cells. Cementoblasts had the ability to become mineralized between osteoblasts and PDL cells. The mechanical tensile stress significantly up-regulated BSP mRNA expression, which reached a peak at 24 hours in both 2000 and 4000 microstrain groups (P < .01) and was tenfold and sixfold higher than that of controls, respectively. BSP expression dropped toward baseline levels at 36 hours in both groups. CONCLUSIONS: Mechanical tensile stress up-regulated the expression of BSP. Low mechanical tensile stress induced earlier and more intensive up-regulation of BSP mRNA; this might represent the optimal stimuli for cementoblast activity.

Osteoprotegerin and ligand of receptor activator of nuclear factor kappaB expression in ovariectomized rats during tooth movement.

OBJECTIVE: To test the null hypothesis that increased tooth displacement in ovariectomized rats is not related to differential expressions of OPG and RANKL in the periodontium. MATERIALS AND METHODS: Eighty-four 12-week female rats were used; half were ovariectomized and half were not. Three months later, the maxillary first molar was moved mesially. Groups of rats were sacrificed at days 0, 1, 3, 5, 7, 10, and 14 after activation. Tooth movement was measured at each time point. OPG and RANKL expressions were examined through immunohistochemistry. RESULTS: Ovariectomized and nonovariectomized rats showed three-phase tooth movement. In both groups, OPG expression increased at the tension area and RANKL increased at the pressure area. The OPG/RANKL ratio coincided with tooth movement, especially in the linear phase from 7 to 14 days. CONCLUSIONS: The null hypothesis is rejected. The increased rate of tooth movement in ovariectomized rats was related to differential expressions of OPG and RANKL.

Patients' perceptions, treatment need, and complexity of orthodontic re-treatment.

The aim of the present study was to investigate the subjective perception and objective treatment need and complexity of patients seeking orthodontic re-treatment. One hundred subjects (66 females, 34 males, age 26.7+/-8.2 years) seeking re-treatment were asked to complete a questionnaire which was constructed based on pilot interviews with 15 patients. The questions focussed on treatment experiences, retention procedures following the first course of treatment, and expectations of and motivations for re-treatment. A visual analogue scale (VAS 0-10) was used. The 're-treatment' group was matched with an untreated control group by age, gender, and the first consultation date. The study models of both groups were scored with the Index of Complexity, Outcome, and Need (ICON). Analysis of variance was used for across-time comparisons of VAS scores of patient's perception of their dental appearance, paired t-test for comparisons of the motivation VAS scores between the first treatment and re-treatment, and Mann-Whitney test for comparisons between the re-treatment and control groups. Eighty-eight patients (26.3+/-8.4 years) completed the questionnaire. After the initial treatment, 36 per cent of the patients did not have any retention measures. The mean VAS scores for dental aesthetics at the start and end of the initial treatment were 2.3+/-2.1 and 6.6+/-2.7, respectively. The scores for the present situation and expected results of re-treatment were 4.1+/-2.7 and 8.8+/-1, respectively. These scores differed significantly from each other. Seventy-nine pairs of models were matched for evaluation of treatment need and complexity. The mean ICON scores of the re-treatment group were significantly lower than the controls (45+/-21 versus 57+/-24), the aesthetic component being the main contributing factor to this difference (25+/-16 versus 36+/-18). Both groups showed a treatment need (ICON>43), with the untreated controls having a relatively higher complexity. These results indicate that patients seeking re-treatment had a good perception of dental aesthetics, strong motivation, and an objective treatment need.

Skeletal anchorage in orthodontics--a review of various systems in animal and human studies.

PURPOSE: The aim of the present investigation was to review and evaluate the current literature on skeletal bone anchorage in orthodontics with regard to success rates of the various systems. MATERIALS AND METHODS: MEDLINE, PubMed, and Cochrane searches (period January 1966 to January 2006, English language) of animal and human studies using skeletal anchorage during orthodontic treatment were scrutinized. A total of 50 relevant articles were identified which investigated various types of implants. RESULTS: Two types of anchorage systems are used in orthodontics: (1) osseointegrated dental implants, including temporary mid-palatal implants. These systems were associated with a wide variety of success rates in animal studies. In human studies, the systems were shown to be reliable, with success rates between 85% and 100% (ie, systems still functioning at the end of the orthodontic treatment). (2) Nonosseointegrated mini-plates and mini-screw anchorage systems. Titanium miniplates were associated with 100% success in animals, and hardly any loss of these mini-plates (bone anchors) were lost due to infection in human studies, with success rates between 91% and 100%. Few long-term studies on nonosseointegrated mini-screws were found, but in animal studies, success rates ranged from 90% to 100%. A success rate of more than 75% in human studies is considered favorable for these orthodontic implants, which confirms the clinical applicability of this type of immediate loading anchor support in orthodontics. CONCLUSIONS: Both animal and human studies revealed that mesiodistal and intrusion movements can be reliably carried out by means of skeletal anchorage devices. A drawback is that animal studies do not reflect the real orthodontic clinical situation; thus, the outcome of these studies should be interpreted with caution. Human studies, however, show that orthodontic forces between 100 and 400 grams can be applied successfully to skeletal anchorage devices. Appropriate treatment strategies need to be confirmed by randomized prospective clinical trials. (More than 50 references).

Subjective evaluation of the accuracy of video imaging prediction following orthognathic surgery in Chinese patients.

PURPOSE: The aims of this retrospective study were to assess the subjective accuracy of predictions generated by a computer imaging software in Chinese patients who had undergone orthognathic surgery and to determine the influence of initial dysgnathia and complexity of the surgical procedure on prediction accuracy. PATIENTS AND METHODS: The sample consisted of 40 Chinese patients who had completed treatment involving orthodontics and orthognathic surgery. All the patients had lateral cephalometric radiographs and profile photographs taken within 3 months before surgery and at least 6 months after surgery. The computer-generated predicted images and the actual post-treatment images were displayed simultaneously to a panel of orthodontists, oral maxillofacial surgeons and laypersons to allow side-by-side comparison. The panel was asked to determine which image was more esthetic and to rate the likeness between the actual and predicted images using a 10 cm visual analog scale. RESULTS: The results showed that the actual image was judged to be more esthetic in 82% of the cases, with the orthodontists more likely to select the actual profile compared to laypersons (P = .005). Orthodontists and surgeons rated the likeness of the images similarly while laypersons rated the likeness significantly lower than the clinicians (P = .012 and P = .015, respectively). Skeletal III cases were judged to be less accurately predicted than skeletal II cases by laypersons (P = .006) and orthodontists (P = .036). Cases treated by single-jaw osteotomy were given better ratings compared to cases with bimaxillary osteotomy by all panel groups but the differences did not reach significant level. CONCLUSIONS: Skeletal III cases managed by bimaxillary osteotomy were least accurately predicted by the computer program. As there exists a possibility that the predicted image may be judged to be more esthetic than the actual image, clinicians must make extra effort to manage patient expectations when using computer simulations for patient education.

Evaluation of the linearity of soft- to hard-tissue movement after orthognathic surgery.

INTRODUCTION: Our aim in this study was to investigate whether a linear relationship exists between soft- to hard-tissue changes for both maxillary and mandibular landmarks over a wide range of skeletal changes. METHODS: The sample consisted of 30 Chinese patients with Class III malocclusion treated with bilateral sagittal split osteotomy and LeFort I advancement. Lateral cephalograms were taken within 2 months before surgery and at least 6 months after surgery. Soft- and hard-tissue changes were recorded by computer-supported measurements of presurgical and postsurgical lateral cephalograms. To evaluate the linear association between soft- and hard-tissue movement, a quadratic function of hard-tissue movement adjusted for sex was initially fitted to the data. The residual plots were used to examine the appropriateness of the fitted quadratic function, and the lack of fit was examined by the F test. A linear function was fitted to the data when the quadratic term was not significant. RESULTS: Visual inspection of the scatter plots of the 5 pairs of corresponding soft- and hard-tissue landmarks showed that relationships between the soft and hard tissues were reasonably linear for both male and female subjects, except for the Sn-ANS pair that showed a curvilinear relationship. Statistical tests confirmed that the association for the Sn-ANS pair was quadratic. CONCLUSIONS: The results of this study provide evidence of a linear relationship between soft- to hard-tissue changes for mandibular landmarks over a wide range of skeletal changes. The nonlinear response of maxillary soft tissues to underlying hard-tissue change in the Sn-ANS pair supports the use of nonlinear ratios for selected maxillary soft- to hard-tissue movements in simulation software.

PRedicting Outcomes For Crohn's dIsease using a moLecular biomarkEr (PROFILE): protocol for a multicentre, randomised, biomarker-stratified trial.

BACKGROUND: The course of Crohn's disease (CD) varies substantially between individuals, but reliable prognostic markers do not exist. This hinders disease management because patients with aggressive disease are undertreated by conventional 'step-up' therapy (in which treatment is gradually escalated in response to refractory or relapsing disease) while those with more indolent disease would be exposed to unnecessary treatment-related toxicity if a more aggressive 'top-down' approach was indiscriminately used. The Predicting outcomes for Crohn's disease using a molecular biomarker trial will assess whether a prognostic transcriptional biomarker, that we have developed and validated, can improve clinical outcomes by facilitating personalised therapy in CD. This represents the first the biomarker-stratified trial in inflammatory bowel disease. METHODS AND ANALYSIS: This biomarker-stratified trial will compare the relative efficacy of 'top-down' and 'accelerated step-up' therapy between biomarker-defined subgroups of patients with newly diagnosed CD. 400 participants from ~50 UK centres will be recruited. Subjects within each biomarker subgroup (IBDhi or IBDlo) will be randomised (1:1) to receive one of the treatment strategies until trial completion (48 weeks). The primary outcome is the incidence of sustained surgery and steroid-free remission from the completion of induction treatment through to week 48. Secondary outcomes include mucosal healing, quality-of-life assessments and surrogate measures of disease burden including number of flares, cumulative steroid exposure, number of hospital admissions and number of Crohn's-related surgeries (assessed hierarchically). Analyses will compare the relative benefit of the treatment strategies in each biomarker-defined subgroup, powered as an interaction analysis, to determine whether the biomarker can accurately match patients to the most appropriate therapy. ETHICS AND DISSEMINATION: Ethical approval has been obtained and recruitment is under way at sites around the UK. Following trial completion and data analysis, the results of the trial will be submitted for publication in peer-reviewed journals and presented at international conferences. TRIAL REGISTRATION NUMBER: ISRCTN11808228; Pre-results.

Biofilm formation on surface characterized micro-implants for skeletal anchorage in orthodontics.

Micro-implants are increasingly popular in clinical orthodontics to effect skeletal anchorage. However, biofilm formation on their surfaces and subsequent infection of peri-implant tissues can result in either exfoliation or surgical removal of these devices. The present study aimed to assess biofilm formation on five commercially available, surface characterized micro-implant systems in vitro. The elemental surface compositions of as-received and autoclave-sterilized micro-implants were characterized by X-ray photoelectron spectroscopy. High carbon contamination was detected on the oxide surfaces, along with traces of inorganic elements (Ca, Cu, Cr, Pb, Zn, and P) which disappeared after Ar(+) ion sputtering. The mean surface roughnesses (R(a)) were around 182nm for titanium micro-implants, and 69nm for stainless steel micro-implants, as measured by atomic force microscopy. Scanning electron microscopy revealed different surface topographies between manufacturers, varying from typical machined grooves to structural defects like pores and pits. Overnight biofilms were grown on micro-implant surfaces by immersion in pooled human whole saliva. Biofilms on micro-implants treated with chlorhexidine and fluoride mouthrinses contained comparable numbers of viable organisms, but significantly less than did untreated micro-implants. Comparison of different implant systems using multiple linear regression analysis indicated that biofilm formation was governed by roughness of the implant surface and the prevalence of carbon- and oxygen-rich components.

Outcome of orthognathic surgery in Chinese patients. A subjective and objective evaluation.

OBJECTIVE: To evaluate the outcome of orthognathic surgery by objective cephalometric measurement of posttreatment soft-tissue profile and by subjective evaluation of profile esthetics by laypersons and clinicians. MATERIALS AND METHODS: The sample consisted of 30 Chinese patients who had completed combined orthodontic and orthognathic surgical treatment. The posttreatment cephalograms of these patients were analyzed with respect to profile convexity, facial height, and lip contours and these were compared to the previously established esthetic norms. Line drawings of the soft-tissue profile were displayed to a panel comprising six laypersons and six clinicians who scored the esthetics of each profile using a 7-point scale. RESULTS: Complete normalization of cephalometric soft-tissue variables was not achieved with orthognathic surgery in most patients, with four of the six soft-tissue cephalometric measurements showing significant differences compared to the esthetic norms. There were good correlations in the esthetic scores between laypersons and clinicians, even though clinicians tend to rate the profiles more favorably. Facial convexity and facial height did not significantly influence the subjective scores of both the laypersons and clinicians. Lower lip protrusion was the only cephalometric variable that significantly influenced clinicians' assessment of profile esthetics (P<.01). CONCLUSIONS: Profile convexity and lower facial height proportion had little influence on both lay and professional perception of profile esthetics. Lower lip position is the only cephalometric variable that significantly influenced clinicians' assessment of profile esthetics.

Risk factors for small pharyngeal airway dimensions in preorthodontic children: A three-dimensional study.

OBJECTIVE: To analyze which parameters, gathered from standard orthodontic diagnostic material, were most relevant for identifying small pharyngeal airway dimensions in preorthodontic children. MATERIALS AND METHODS: The sample was composed of 105 cone beam computed tomography scans of healthy preorthodontic children (44 boys, 61 girls; mean age, 10.7 ± 2.4 years). Airway volume and minimal cross-sectional area were three-dimensionally assessed. Cephalometric features and skeletal maturity were assessed on generated two-dimensional cephalograms. Associations were analyzed and adjusted for age, gender, and skeletal maturity by multiple regression analyses. RESULTS: Airway volume and minimal cross-sectional area were significantly smaller in prepubertal children (P < .001, P < .05, respectively) and positively associated with age (P < .001, P < .01, respectively). After adjustment of age, skeletal maturity and gender significant associations were found between pharyngeal airway dimensions and craniofacial morphology. Airway volume was positively associated with maxillary and mandibular width (P < .01; P < .001, respectively) and anterior face height (P < .05; P < .05, respectively). Minimal cross-sectional area was positively associated with maxillary and mandibular width (P < .01; P < .001, respectively) and negatively associated with sagittal jaw relationship (AnPg, P < .05). Mandibular width and age were the most relevant factors for airway volume (r2 = 0.36). Mandibular width and sagittal jaw relationship were the most relevant factors for minimal cross-sectional area (r2 = 0.16). CONCLUSION: Pharyngeal airway dimensions were significantly associated with age, skeletal maturity, and craniofacial morphology in all three planes. Children with a reduced mandibular width and increased sagittal jaw relationship are particularly at risk of having small pharyngeal airway dimensions.

Multivariate analysis of surface physico-chemical properties controlling biofilm formation on orthodontic adhesives prior to and after fluoride and chlorhexidine treatment.

Biofilm formation on orthodontic adhesives is a serious clinical problem, as it leads to enamel demineralization around fixed orthodontic appliances, often leaving white spot lesions after their removal. The aim of this work was to determine the influence of surface physico-chemical properties of four commonly used orthodontic adhesives (Concise, Fuji ORTHO LC, Ketac Cem mu, and Transbond XT) on early bacterial biofilm formation. In addition, effects of two commercially available mouthrinses (0.05% sodium fluoride and 0.2% chlorhexidine gluconate) on these properties and biofilm formation were determined. Water contact angles on the adhesives decreased after fluoride and chlorhexidine treatment, concurrent with an increase in carbon and a decrease in oxygen surface concentrations, except for Transbond, as determined by X-ray photoelectron spectroscopy. No fluorine was detected on any of the adhesive surfaces after fluoride treatment, while all surfaces showed chlorine after chlorhexidine treatment. Surface roughness of the adhesives measured using three-dimensional optical profilometry was around 4 microm and found not to be a factor governing early biofilm formation. Multiple linear regression analysis indicated that early biofilm formation by Streptococcus sanguis could be explained in a model comprising hydrophobicity and the prevalence of oxygen- and nitrogen-rich components on the adhesive surfaces.

Occlusal status in Asian male adults: prevalence and ethnic variation.

The purpose of this study was to determine the occlusal status in young Asian male adults of three ethnic groups. Study models of a sample of male army recruits (N = 339, age 17-22 years) with no history of orthodontic treatment were assessed. The ethnic proportions of the sample were Chinese 76.1% (n = 258), Malay 17.7% (n = 60), and Indian 6.2% (n = 21). British Standard Institute (BSI) and Angle's classification were used to determine incisor and molar relationships, respectively. Chi-square test or Fisher's Exact test was performed to compare the occlusal traits between ethnic groups. The distribution of incisor relationships of the total sample consisted of Class I = 48.1%, Class II/1 = 26.3%, Class II/2 = 3.2%, and Class III = 22.4%. Right Angle's molar relationships were 49.9%, 24.5%, and 24.2% whereas left Angle's molar relationships were 53.1%, 25.1%, and 21.2% for Class I, II, and III, respectively. Comparison between ethnic groups found that Indian subjects were more likely to have Class II/1 malocclusions and clinically missing permanent teeth (P < .05). The study found that the overall prevalence of malocclusion (BSI) was Class I, Class II/1, Class III, and Class II/2 in descending order of proportions. Angle's Class I molar was most prevalent followed by Class II and Class III relations. A significant difference in occlusal status between the ethnic groups was found regarding incisor relationship and missing permanent teeth (P < .05).

Orthodontic treatment need in Asian adult males.

Orthodontic treatment in adults has gained social and professional acceptance in recent years. An assessment of orthodontic treatment need helps to identify individuals who will benefit from treatment and safeguard their interest. The purpose of this study was to assess the objective and subjective levels of orthodontic treatment need in a sample of orthodontically untreated adult Asian males. A sample of male army recruits (n = 339, age 17-22 years, Chinese = 258, Malay = 60, Indian = 21) with no history of orthodontic treatment or craniofacial anomalies participated in the study on a voluntary basis with informed consent. Impressions for study models were taken. Objective treatment need was assessed based on study model analysis using the Index of Orthodontic Treatment Need (IOTN). Questionnaires were used to assess subjective treatment need based on subjective esthetic component (EC) ratings. Fifty percentage of the sample had a definite need for orthodontic treatment (dental health component [DHC] grades 4 and 5), whereas 29.2% had a moderate need for treatment (DHC grades 3). The occlusal trait most commonly identified was dental crossbite. Malay males had the highest percentage with a definite need for treatment for both dental health and esthetic reasons in comparison with Chinese and Indian males. However, there was no difference in the level of treatment need among the ethnic groups (P > .05). No correlation between objective and subjective EC scores was found (P > .05). A high level of investigator-identified treatment need was not supported by a similar level of subject awareness among the adult sample.

Notch1 signaling regulates the proliferation and self-renewal of human dental follicle cells by modulating the G1/S phase transition and telomerase activity.

Multipotent human dental follicle cells (HDFCs) have been intensively studied in periodontal regeneration research, yet the role of Notch1 in HDFCs has not been fully understood. The aim of the current study is to explore the role of Notch1 signaling in HDFCs self-renewal and proliferation. HDFCs were obtained from the extracted wisdom teeth from adolescent patients. Regulation of Notch1 signaling in the HDFCs was achieved by overexpressing the exogenous intracellular domain of Notch1 (ICN1) or silencing Notch1 by shRNA. The regulatory effects of Notch1 on HDFC proliferation, cell cycle distribution and the expression of cell cycle regulators were investigated through various molecular technologies, including plasmid construction, retrovirus preparation and infection, qRT-PCR, western blot, RBP-Jk luciferase reporter and cell proliferation assay. Our data clearly show that constitutively activation of Notch1 stimulates the HDFCs proliferation while inhibition of the Notch1 suppresses their proliferation in vitro. In addition, the HDFCs proliferation is associated with the increased expression of cell cycle regulators, e.g. cyclin D1, cyclin D2, cyclin D3, cyclin E1, CDK2, CDK4, CDK6, and SKP2 and the decreased expression of p27 (kip1). Moreover, our data show that the G1/S phase transition (indicating proliferation) and telomerase activity (indicating self-renewal) can be enhanced by overexpression of ICN1 but halted by inhibition of Notch1. Together, the current study provides evidence for the first time that Notch1 signaling regulates the proliferation and self-renewal capacity of HDFCs through modulation of the G1/S phase transition and the telomerase activity.