Oxygen reduction mechanism on corroded zinc

The mechanism of oxygen reduction on the as-polished and corroded zinc specimens has been studied using a rotating ring disc electrode (RRDE) system. On the as-polished surface, oxygen was reduced into two distinct steps. In the first step, about 44% of O₂ was reduced to H₂O₂ in a 2-electron reaction with the rest being reduced to OH^? in a 4-electron reaction. On the other hand, in the second step, with the increase of overpotential O₂ was almost exclusively reduced to OH^? in a 4-electron reaction. The first step reduction occurred on an air-formed oxide-covered surface at more positive potential than ?1.2 V vs. Ag/AgCl and the second step reduction (E < ?1.2 V) took place on a semi-uniformly active surface. On the corroded surface, the second step was not distinctly observed on the polarization curve, because reduction of the zinc corrosion products simultaneously took place around ?1.2 V. The O₂ reduction in the first step was inhibited by deposition of the corrosion products, though the ratio of amount of O₂ reduced to OH^? in a 4-electron reaction was larger than that on the as-polished surface. The mechanism of oxygen reduction is discussed on the basis of results obtained from the RRDE experiment.     

Patterns of missing occlusal units and oral health-related quality of life in SDA patients

Summary  The aim of this study was to explore the relationship between patterns of missing occlusal units (OUs) and oral health-related quality of life (OHRQoL) in subjects with the shortened dental arches (SDAs). Subjects with SDAs were recruited consecutively for 1 month from six university-based prosthodontic clinics. In total, 115 SDA subjects participated (mean age, 58·5 ± 10·0 years; 71% female). The location and number of missing teeth were examined and the number of missing OUs was calculated. To evaluate OHRQoL, the Japanese version of the Oral Health Impact Profile (OHIP-J) was administered and the summary score of OHIP-J was calculated. The SDA subjects were categorized depending upon the anterior-posterior lengths of the missing or remaining OUs. Regression analyses were performed to investigate the OHIP-J differences between groups of subjects with various anterior–posterior SDA lengths. The analyses revealed that subjects who only lost the second molar contact exhibited significantly better OHRQoL than those who lost more teeth [coefficient: 11·1, 95% confidence interval (CI): 2·8–19·2, P  = 0·02]. Furthermore a statistically significant group difference was observed between the groups with and without the first molar occlusal contact (coefficient: 12·8, 95% CI: 1·4 to 24·1, P  = 0·03). In conclusion, although our results are of exploratory nature and need validation, patterns of missing OUs are likely to be related to the OHRQoL impairment in SDA subjects with the presence of first molar contact having a particularly important role.     

青少年产生正畸治疗需求动机的影响因素

目的：研究各种主、客观因素对青少年产生正畸治疗需求动机的影响。方法：随机抽取１１岁～１３岁青少年３００名（男女各半），做问卷调查，测量研究模型，获得被测试的治疗优先指数（ｔｒｅａｔｍｅｎｔｐｒｉｏｒｉｔｙｉｎｄｅｘ，ＴＰＩ）等级。结果：１．青少年的认知水平和对外界反馈的认知均与治疗需求显著相关；２．性别因素、家长因素及客观畸形程度都对治疗需求产生影响。结论：青少年正畸治疗需求动机的产生受社会心理因素及客观畸形程度的影响     

The clinical relevance of orthognathic surgery on quality of life

The aim of orthognathic surgery is to produce a more aesthetic facial skeletal appearance, and improve jaw function. This prospective study, aimed to evaluate the impact of orthognathic surgery on quality of life for patients with dentofacial deformity, and whether it was clinically meaningful. 62 consecutive patients were recruited (27 male, 35 female) aged 18–38 years. Baseline data were collected using a validated health status measure (Orthognathic Quality of Life Questionnaire (OQLQ)) and a visual analogue scale (VAS). Postoperative questionnaires (OQLQ, VAS) and a Global Transition Scale (GTS) were completed at 6 months after completion of treatment and compared with pre-treatment scores. Following surgery, there was a significant (p < 0.05, paired t test) improvement in OQLQ scores for each domain. The proportion of patients reporting a moderate or large improvement was: facial appearance (93%), chewing function (64%), comfort (60%) and speech (32%). Clinical relevance of change scores was reported in terms of effect sizes, and the largest effect was on facial aesthetics. The clinical impact was moderate on social aspects of deformity and oral function and a small effect on awareness of facial deformity. This research reaffirms that orthognathic surgery has positive effects on quality of life.     

Comparing the Impact of Oral Disease in Two Populations of Older Adults: Application of the Geriatric Oral Health Assessment Index

Objectives : This study compares the distributional and psychometric properties of the Geriatric Oral Health Assessment Index (GOHAI) in two samples of older adults, and examines how the self-perceived impact of oral disease, as measured by the GOHAI, varies in accordance with sample sociodemographic and health characteristics. Methods : Results are based on survey data from two samples of older men: a Medicare sample of patients using community physicians (n=799; mean age=74) and users of VA ambulatory health care (n=542; mean age=72). Results : The findings indicated significant differences between samples in mean GOHAI scores, with the VA sample exhibiting worse scores. A number of similarities in psychometric properties of the instrument across the two samples were found: high internal consistency reliability and similar inter-item and item-scale correlations. Factor analyses revealed somewhat different structures between the two samples, but explained similar amounts of variance; regression analyses indicated that income and self-rated oral health were significant predictors of GOHAI scores in both samples. Conclusions : The GOHAI exhibits satisfactory psychometric properties in both samples and is sensitive to sociodemographic differences among and between two samples of older men. Results suggest continued use of the GOHAI as an indicator of the impact of oral conditions on functioning and well-being in a variety of samples.     

Histomorphometric and removal torque analysis for TiO2-blasted titanium implants. An experimental study on dogs

The aim of the present study was to compare the anchorage of TiO2-blasted screw and cylindrical implants with conventionally used machine-produced screw and cylindrical implants inserted immediately in extraction sockets on dogs. 6 adult mongrel dogs had 3rd and 4th mandibular premolars extracted bilaterally and 24 commercial pure titanium implants were placed immediately in extraction sockets and covered with mucoperiosteum. Each dog had inserted 4 implants: 1 screw implant and 1 cylindrical implant blasted with titanium-dioxide-particles; 1 screw implant and 1 cylindrical implant with machine-produced (m.p.) surface (controls). After a healing period of 12 weeks, 16 implants from 4 animals were used for removal torque test, which demonstrated that significantly higher removal torque force was needed to unscrew the implants blasted with titanium-dioxide-particles, than the normal m.p. implants. The medians for the TiO2-blasted screw and cylindrical implants were > 150 Ncm and 105 Ncm, respectively, while the values for the m.p. implants were 60 Ncm and 35 Ncm, respectively. The SEM investigation demonstrated a high irregularity of the TiO2-blasted surface compared to the machined surface. The Ra and Rz values for surface roughness were higher for the TiO2-blasted implants than for the normal m.p. implants. Histomorphometrically, the arithmetic mean of the direct bone-implant contact fraction was 69%. There was no significant difference in direct bone-implant contact length fraction between TiO2-blasted implants and the control implants. The implants blasted with titanium-dioxide-particles in this study showed a better anchorage than implants with a machine-produced surface. The screw implants showed a better anchorage than the cylindrical implants.     

Newly designed phantom for visual detection tests of intra-oral x-ray imaging systems

A new phantom set, which consists of ten acrylic plate phantoms with several kinds of holes, was designed for visual detection tests of intra-oral x-ray imagin systems. Detection tests of two kinds of dental x-ray films were performed using three kinds of phantoms, an aluminum test object, Burger's phantom and the new phantom set. Detection-ability curves generated against optical density were compared. Moreover, correlation between the SNR (signal-to-noise ratio) factor and detection ability was analyzed. False positive rates were also compared. To reduce the number of phantom plate that had to be tested in the new phantom set, the number of detected signals for each phantom plate was cumulatively added and statistically compared to the total number of detected signals. The signals produced with the aluminum test object were too large. The detection ability with Burger's phantom was affected by psychological effect. The detection ability with the new phantom set was most closely correlated to the SNR. False positive rates could be compared with the new phantom set but not with the aluminum test object. The new phantom with holoes smaller than 0.6mm in diameter did not figure into the results. In conclusion, the newly designed phantom set is useful for visual detection tests of intra-oral x-ray imaging systems.     

Quality of life and psychosocial outcomes after fixed orthodontic treatment: a 17-year observational cohort study

Arrow P, Brennan D, Spencer AJ. Quality of life and psychosocial outcomes after fixed orthodontic treatment: a 17‐year observational cohort study. Community Dent Oral Epidemiol 2011; 39: 505–514. © 2011 John Wiley & Sons A/S Abstract – Background: There is little evidence to suggest that orthodontic treatment can prevent or reduce the likelihood of dental caries or of periodontal disease or dental trauma and temporomandibular disorders, but there is a modest association between the presence of malocclusion/orthodontic treatment need and quality of life. However, little is known of the long‐term outcomes of orthodontic treatment. This study reports on the longitudinal follow‐up of quality of life and psychosocial outcomes of orthodontic treatment among a cohort of adults who were examined as adolescents in 1988/1989. Materials and Methods: Children who were examined in 1988/1989 were invited to a follow‐up in 2005/2006. Respondents completed a questionnaire, which collected information on quality of life, receipt of orthodontic treatment and psychosocial factors, and were invited for a clinical examination. Oral health conditions including occlusal status using the Dental Aesthetic Index were recorded. Analysis of variance and multiple linear regression were used to examine the relationship between the measured factors. Results: There was no statistically significant association between occlusal status at adolescence and quality of life at adulthood. Those individuals who had orthodontic treatment but did not need orthodontic treatment had higher self‐esteem (23.1, SD 5.2) and were more satisfied with life (18.5, SD 3.7) than other treatment groups (self‐esteem range, 20.0–22.7; life satisfaction range, 16.4–18.1), anova P < 0.01 and P < 0.05, respectively. Occlusal status at adulthood was significantly associated with quality of life, P < 0.01. Multivariate analyses showed a statistically significant association between occlusal status at adolescence (‘Desirable treatment’β = 0.70, P = 0.04) and adulthood (‘Desirable treatment’β = 1.66, P < 0.01) with quality of life. Orthodontic treatment was negatively associated with psychosocial factors (life satisfaction; fixed orthodontic treatment (FOT) β = ?0.91, P = 0.02 and self‐esteem; FOT β = ?1.39, P < 0.01). Conclusions: Occlusal status appears to have limited association with quality of life and psychosocial factors. Receipt of fixed orthodontic treatment does not appear to be associated with oral health‐related quality of life but appears to be negatively associated with self‐esteem and satisfaction with life.     

Factors Influencing the Appropriateness of Restorative Dental Treatment: an Epidemiologic Perspective

Objectives : An epidemiologic analysis was performed to identify patient and dentist factors influencing over- and undertreatment of restorative services in a sample of insured adults. Methods : At baseline, 681 Washington State employees and their spouses, aged 20 to 34 years and residing in the Olympia or Pullman areas, were interviewed by telephone. Oral assessments were conducted to measure personal characteristics, oral disease, and restoration quality. Adults were followed for two years to measure use of restorative services from dental insurance claims. Each adult's baseline and claims data were linked with provider and practice variables collected from the dentist who provided treatment. Results : For overtreatment, 39 percent of adults received one or more replacement restorations in nondecayed teeth with satisfactory fillings at baseline, while 18 percent of adults had one or more restorations placed in teeth with no decay and fillings. An adult's probability of overtreatment was higher if the adult had more fillings at baseline, or if an adult's dentist was younger, had a busy practice, advertised, charged higher fees, had less continuing education, or had a solo practice. For undertreatment, about 16 percent of adults either received no replacement restorations in teeth with unsatisfactory fillings at baseline, or had decayed teeth at baseline that were not filled or crowned. An adult's probability of undertreatment was higher if an adult had less decayed or more missing surfaces at baseline, or if an adult's dentist believed in sharing information with patients, had a busy practice, or reported not placing fillings when radiographic evidence of new caries was present. Conclusion : A minority of adults aged 20 to 34 experienced potential over- or undertreatment of restorative services, which are influenced by both patient and dentist factors.     

Pediatric patients' orthodontic treatment need, quality of life, and smiling patterns -- an analysis of patient, parent, and provider responses

Objectives: The objectives of this study is to explore the relationship between pediatric patients' orthodontic treatment need, the patients' assessments of their smile‐related quality of life (QoL), their parents' proxy assessment of their child's QoL and own assessments of their child's smile, and the patients' objectively assessed smiling patterns. Methods: Survey data were collected from 102 patients (53 boys/49 girls; age range: 9–13 years) and their parents. Orthodontic treatment need was assessed with the Index of Complexity, Outcome, and Need (ICON). Smiling patterns were determined by videotaping patients' smiles while they watched a cartoon. Thirty predetermined sections of these tapes were then assessed by two independent raters to measure the patients' smiling patterns. Results: The aesthetic component and total ICON scores correlated with the patients' smile‐related QoL (r = 0.25; P = 0.014/r = 0.23; P = 0.024), parental proxy assessments of the child's smile‐related QoL (r = 0.29; P = 0.004/r = 0.26; P = 0.009), the parents' own assessments of their child's smile (r = 0.32; P = 0.002/r = 0.29; P = 0.005), and the number of negative adjectives chosen by the parents to describe their child's smile (r = 0.32; P = 0.002/r = 0.30; P = 0.004). Although the smiling patterns were correlated with the patients' smile‐related QoL responses (height of smile: r = 0.29; P = 0.005/number of teeth shown: r = 0.30; P = 0.004), the ICON scores were not correlated with the patients' smiling patterns. Conclusions: Objectively assessed orthodontic treatment need correlates with the patients' and parents' assessments of the child's smile‐related QoL scores. However, while objective smiling patterns are related with the patients' smile‐related QoL, they are not correlated with the patients' orthodontic treatment need.