National prevalence of oral HPV infection and related risk factors in the U.S. adult population.

This article reviews the rapidly growing evidence that oral human papilloma viruses (HPV) infection contributes to the risk of oral squamous cell carcinoma. It also reports the first nationally representative estimates of oral HPV prevalence in the United States adult population. An estimated 7.3% (95% CI: 6.0, 8.9) of the U.S. population had one or more oral HPV types detected in oral rinse; 3.1% (95%CI: 2.4, 3.9) of the U.S. population had one or more oncogenic HPV types. A substantial excess risk of HPV infection in men is not explained by education, smoking, age of sexual debut, or number of lifetime sex partners. Based on the published finding from a case-control study, where there was an odds ratio of 2.6 (95% CI: 1.5, 4.2) for the association of head and neck cancer oncogenic oral HPV infection, the estimated population attributable risk for head and neck cancer in the U.S. population was 4.7%. In other words, there would be a 4.7% reduction in incidence rate of head and neck cancer in the United States if oncogenic HPV infection could be prevented. The results also provide population data that help evaluate the likely public health benefits of prophylactic vaccination against oral HPV acquisition.

Emulation of Community Water Fluoridation Coverage Across US Counties.

INTRODUCTION: Expansion of community water fluoridation has stalled in the United States, leaving 115 million Americans without fluoridated drinking water. OBJECTIVE: This study used spatial regression methods to assess contributions of supply-side factors (neighboring counties' fluoridation coverage) and demand-side factors (health literacy, education, and population density of the local county) in predicting the extent of fluoridation in US counties. METHODS: For this cross-sectional ecological analysis, data from the 2014 Water Fluoridation Reporting System for all 3,135 US counties were merged with sociodemographic data from the 2014 American Community Survey and county-level estimates of health literacy based on the National Association of Adult Literacy Survey. We employed multilevel geographically weighted autoregressive models to predict fluoridation coverage of each county as a function of fluoridation coverage of neighboring counties and local-county covariates: either health literacy or sociodemographic characteristics. Akaike's Information Criterion was used to distinguish the better model in terms of explanatory power and parsimony. RESULTS: In the best-fit model, an increase from the first to third quartile of neighboring counties' fluoridation coverage was associated with an increase of 27.76 percentage points (95% confidence limits [CI] = 27.71, 27.81) in a local county's fluoridation coverage, while an increase from the first to third quartile of local county's health literacy was associated with an increase of 2.8 percentage points (95% CL = 2.68, 2.89). The results are consistent with a process of emulation, in which counties implement fluoridation based upon their population's health literacy and the extent of fluoridation practiced in neighboring counties. CONCLUSION: These results suggest that demand for community water fluoridation will increase as health literacy increases within a county. Furthermore, when considering expansion of fluoridation, non-fluoridated communities can benefit from precedents from nearby communities that are fluoridated. KNOWLEDGE TRANSFER STATEMENT: Expanded coverage of community water fluoridation has stalled in the United States. The economic theory of diffusion describes how, over time and space, policy enacted in one community can influence public opinion in a neighboring community. This study applies geospatial analysis of county-level data and the theory of policy diffusion to demonstrate that fluoridated counties can promote the implementation of community water fluoridation in their neighboring, non-fluoridated communities.

Biomarkers of periodontal inflammation in the Australian adult population.

BACKGROUND: Several inflammatory biomarkers are implicated in the pathogenesis of periodontitis including interleukin-1beta (IL-1beta) and C-reactive protein (CRP). This study investigated the presence of these factors in gingival crevicular fluid (GCF) and their relationship to clinical and social determinants of periodontitis in the Australian population. METHODS: Equal numbers of periodontitis cases and non-cases were sampled during oral epidemiologic examination in the National Survey of Adult Oral Health. GCF was sampled from four sites where probing pocket depth (PPD) and recession were recorded. From these, IL-1beta and CRP were quantified by ELISA and the log amount of GCF IL-1beta (pg) per person and the proportion of adults with detectable CRP was computed. RESULTS: Periodontitis cases (n = 511) had significantly higher levels of IL-1beta and CRP than non-cases (n = 562). PPD, clinical attachment loss, plaque and gingivitis indices were positively associated with elevated levels of both biomarkers. Levels of both were positively associated with age, low socio-economic position and non-Australian birth. CONCLUSIONS: The presence of IL-1beta and CRP in GCF are associated with periodontal disease parameters within the Australian population. The levels of both biomarkers are influenced by age, education and eligibility for public dental care.

Impact of dental care on oral health-related quality of life and treatment goals among elderly adults.

BACKGROUND: General dental care can effectively control disease and restore damaged tissue, yet little is known about its impact on patients' subjective oral health, namely treatment goals and oral health-related quality of life (OHRQoL). This study aimed to evaluate change in both aspects of subjective oral health among elderly adults receiving publicly-funded, general dental care. METHODS: We conducted a prospective, single-group intervention study of adults aged 75+ years receiving care through the South Australian Dental Service (SADS). Before receiving dental care, subjects completed the Oral Health Impact Profile (OHIP-14) questionnaire which evaluates OHRQoL. In this questionnaire, subjects rated the extent to which they had attained a self-nominated oral health goal. Dentists provided standard-of-care treatment and six months later the OHIP-14 and goal attainment questions were re-administered. RESULTS: Among the 253 adults studied, overall improvements in OHRQoL were observed (p < 0.05), although the effect was dependent on pre-treatment goal: mean OHIP-14 scores did not change significantly for subjects whose goal was less pain/discomfort while significant improvements were observed for subjects with other treatment goals. In contrast, mean goal attainment ratings improved significantly (P < 0.05), regardless of treatment goal categories. CONCLUSIONS: Dental care was associated with improvements in subjective oral health, although different patterns of improvement were observed for OHRQoL compared with goal attainment ratings.

Differential Misclassification of Disease under Partial-Mouth Sampling.

AIM:: The effect of misclassification of a cluster-level dichotomous outcome (disease) due to partial-cluster sampling on its association with a dichotomous exposure is investigated. METHODS:: Disease (e.g., chronic periodontitis) is deemed to exist in a cluster (e.g., full mouth) when a condition of interest (e.g., pocket depth or clinical attachment loss exceeding an established threshold) is present in number and pattern across observations (e.g., tooth sites) in the cluster according to a specific criterion. When a subset of observations within each cluster is selected (i.e., partial-mouth sampling), specificity of disease is 100% (in the absence of site-level measurement error), whereas sensitivity is imperfect and generally unknown. Using conditional probability arguments, we investigate disease misclassification under partial-cluster sampling and its impact on the estimated disease-exposure association when the exposure is cluster level and measured without error. RESULTS:: When the probability of disease varies by exposure status, outcome misclassification at the cluster level is differential under partial-cluster sampling and depends on 1) the partial recording protocol, including the number of observations sampled and the particular sites selected in a cluster; 2) the joint probability structure of the condition within clusters; and 3) the criterion for disease. A numeric example demonstrates that disease-exposure odds ratios under partial-cluster random sampling can be biased in either direction (toward or away from the null) relative to gold-standard odds ratios under full-cluster sampling. CONCLUSIONS:: In general, misclassification of disease is differential under partial-cluster sampling. In particular, sensitivity and negative predictive values depend on exposure status, which leads to biased inference. KNOWLEDGE TRANSFER STATEMENT:: Partial-mouth sampling causes disease misclassification probabilities, including sensitivity, to vary by exposure groups when disease prevalence differs between groups. As a result, disease-exposure associations may be under- or overestimated by standard analysis procedures for periodontal data relative to full-mouth estimates. Procedures that address bias are needed for partial-recording protocols.

Long-chain omega-3 fatty acids and headache in the U.S. population.

The objective of this study was to assess whether dietary intake of long-chain omega-3 polyunsaturated fatty acids (PUFAs) is associated with lower prevalence of headache in the U.S. POPULATION: This cross-sectional study used data for a nationally representative sample of 12,317 men and women aged ≥ 20 years participating in the National Health and Nutrition Examination Surveys of 1999-2004. Interviewers recorded self-report of severe headache or migraine in the past three months. Eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) were quantified from 24-hour dietary recall using the U.S. Department of Agriculture National Nutrient Database. Serum concentration of C-reactive protein, a marker of inflammation and potential mediator of PUFA's analgesic properties, was quantified by latex-enhanced nephelometry. Multivariable generalized linear models estimated prevalence ratios (PR) with 95% confidence limits (CL) for severe headache or migraine adjusting for NHANES cycle, sociodemographic characteristics, body mass index and total energy intake. The unadjusted prevalence of severe headache or migraine was 22.0% (females 28.2%, males 15.5%). In multivariable analysis, greater intake of omega-3 PUFAs was associated with lower prevalence of severe headache or migraine: PR 0.94 (95% CL: 0.88, 0.99, p = 0.035) per log unit increase in EPA, and PR 0.94 (95% CL: 0.90, 0.99, p = 0.023) per log unit increase in DHA. The strength of association was greater for non-Mexican Hispanics than for other racial/ethnic groups but was not attenuated after adjustment for C-reactive protein. In conclusion, higher dietary intakes of EPA and DHA were associated with lower prevalence of headache supporting the hypothesis that omega-3 PUFAs may prevent or reduce headache.

Water Fluoridation and Dental Caries in U.S. Children and Adolescents.

Fluoridation of America's drinking water was among the great public health achievements of the 20th century. Yet there is a paucity of studies from the past 3 decades investigating its dental health benefits in the U.S. POPULATION: This cross-sectional study sought to evaluate associations between availability of community water fluoridation (CWF) and dental caries experience in the U.S. child and adolescent population. County-level estimates of the percentage of population served by CWF (% CWF) from the Centers for Disease Control and Prevention's Water Fluoridation Reporting System were merged with dental examination data from 10 y of National Health and Nutrition Examination Surveys (1999 to 2004 and 2011 to 2014). Dental caries experience in the primary dentition (decayed and filled tooth surfaces [dfs]) was calculated for 7,000 children aged 2 to 8 y and in the permanent dentition (decayed, missing, and filled tooth surfaces [DMFS]) for 12,604 children and adolescents aged 6 to 17 y. Linear regression models estimated associations between % CWF and dental caries experience with adjustment for sociodemographic characteristics: age, sex, race/ethnicity, rural-urban location, head-of-household education, and period since last dental visit. Sensitivity analysis excluded counties fluoridated after 1998. In unadjusted analysis, caries experience in the primary dentition was lower in counties with ≥75% CWF (mean dfs = 3.3; 95% confidence limit [CL] = 2.8, 3.7) than in counties with <75% CWF (mean dfs = 4.6; 95% CL = 3.9, 5.4), a prevented fraction of 30% (95% CL = 11, 48). The difference was also statistically significant, although less pronounced, in the permanent dentition: mean DMFS (95% CL) was 2.2 (2.0, 2.4) and 1.9 (1.8, 2.1), respectively, representing a prevented fraction of 12% (95% CL = 1, 23). Statistically significant associations likewise were seen when % CWF was modeled as a continuum, and differences tended to increase in covariate-adjusted analysis and in sensitivity analysis. These findings confirm a substantial caries-preventive benefit of CWF for U.S. children and that the benefit is most pronounced in primary teeth.

Stomaching the pain of spinal fusion: gastrointestinal discomfort is as severe as back pain in 50% of adolescent idiopathic scoliosis patients following posterior spinal fusion.

PURPOSE: There have been no prospective studies investigating gastrointestinal (GI) symptoms of patients with adolescent idiopathic scoliosis (AIS) following posterior spinal fusion (PSF). The purpose of this study was to evaluate the incidence and severity of self-reported GI symptoms following PSF. METHODS: In all, 40 AIS patients undergoing PSF were prospectively enrolled between March 2015 and October 2016. Patients completed a survey on each postoperative, inpatient day regarding nausea, emesis, constipation, abdominal pain and back pain, rating their pain on a scale of 1 to 10. RESULTS: Abdominal pain (50%), emesis (63%), nausea (65%) and constipation (68%) were experienced by the majority of patients. Of those reporting back pain, the mean pain level during the postoperative period was 5.1 (0.2 to 9.6). Of those reporting abdominal pain, the mean pain level during the postoperative period was 5.5 (1.4 to 8.6), which was not different than the severity of their back-pain levels (mean = 6.0, p = 0.31). CONCLUSIONS: Gastrointestinal issues in AIS patients following PSF are common. Abdominal pain was as severe as the back pain for half of the patients. LEVEL OF EVIDENCE: II.

Does psychological stress mediate social deprivation in tooth loss?

It is unclear which theoretical dimension of psychological stress affects health status. We hypothesized that both distress and coping mediate the relationship between socio-economic position and tooth loss. Cross-sectional data from 2915 middle-aged adults evaluated retention of < 20 teeth, behaviors, psychological stress, and sociodemographic characteristics. Principal components analysis of the Perceived Stress Scale (PSS) extracted 'distress' (a = 0.85) and 'coping' (a =0.83) factors, consistent with theory. Hierarchical entry of explanatory variables into age- and sex-adjusted logistic regression models estimated odds ratios (OR) and 95% confidence intervals [95% CI] for retention of < 20 teeth. Analysis of the separate contributions of distress and coping revealed a significant main effect of coping (OR = 0.7 [95% CI = 0.7-0.8]), but no effect for distress (OR = 1.0 [95% CI = 0.9-1.1]) or for the interaction of coping and distress. Behavior and psychological stress only modestly attenuated socio-economic inequality in retention of < 20 teeth, providing evidence to support a mediating role of coping.

Chronic Periodontitis Genome-wide Association Study in the Hispanic Community Health Study / Study of Latinos.

Chronic periodontitis (CP) has a genetic component, particularly its severe forms. Evidence from genome-wide association studies (GWASs) has highlighted several potential novel loci. Here, the authors report the first GWAS of CP among a large community-based sample of Hispanics/Latinos. The authors interrogated a quantitative trait of CP (mean interproximal clinical attachment level determined by full-mouth periodontal examinations) among 10,935 adult participants (mean age: 45 y, range: 18 to 76 y) from the Hispanic Community Health Study / Study of Latinos. Genotyping was done with a custom Illumina Omni2.5M array, and imputation to approximately 20 million single-nucleotide polymorphisms was based on the 1000 Genomes Project phase 1 reference panel. Analyses were based on linear mixed models adjusting for sex, age, study design features, ancestry, and kinship and employed a conventional P < 5 × 10-8 statistical significance threshold. The authors identified a genome-wide significant association signal in the 1q42.2 locus ( TSNAX-DISC1 noncoding RNA, lead single-nucleotide polymorphism: rs149133391, minor allele [C] frequency = 0.01, P = 7.9 × 10-9) and 4 more loci with suggestive evidence of association ( P < 5 × 10-6): 1q22 (rs13373934), 5p15.33 (rs186066047), 6p22.3 (rs10456847), and 11p15.1 (rs75715012). We tested these loci for replication in independent samples of European-American ( n = 4,402) and African-American ( n = 908) participants of the Atherosclerosis Risk in Communities study. There was no replication among the European Americans; however, the TSNAX-DISC1 locus replicated in the African-American sample (rs149133391, minor allele frequency = 0.02, P = 9.1 × 10-3), while the 1q22 locus was directionally concordant and nominally significant (rs13373934, P = 4.0 × 10-2). This discovery GWAS of interproximal clinical attachment level-a measure of lifetime periodontal tissue destruction-was conducted in a large, community-based sample of Hispanic/Latinos. It identified a genome-wide significant locus that was independently replicated in an African-American population. Identifying this genetic marker offers direction for interrogation in subsequent genomic and experimental studies of CP.

GWAS Identifies New Loci for Painful Temporomandibular Disorder: Hispanic Community Health Study/Study of Latinos.

Temporomandibular disorder (TMD) is a musculoskeletal condition characterized by pain and reduced function in the temporomandibular joint and/or associated masticatory musculature. Prevalence in the United States is 5% and twice as high among women as men. We conducted a discovery genome-wide association study (GWAS) of TMD in 10,153 participants (769 cases, 9,384 controls) of the US Hispanic Community Health Study/Study of Latinos (HCHS/SOL). The most promising single-nucleotide polymorphisms (SNPs) were tested in meta-analysis of 4 independent cohorts. One replication cohort was from the United States, and the others were from Germany, Finland, and Brazil, totaling 1,911 TMD cases and 6,903 controls. A locus near the sarcoglycan alpha ( SGCA), rs4794106, was suggestive in the discovery analysis ( P = 2.6 × 106) and replicated (i.e., 1-tailed P = 0.016) in the Brazilian cohort. In the discovery cohort, sex-stratified analysis identified 2 additional genome-wide significant loci in females. One lying upstream of the relaxin/insulin-like family peptide receptor 2 ( RXP2) (chromosome 13, rs60249166, odds ratio [OR] = 0.65, P = 3.6 × 10-8) was replicated among females in the meta-analysis (1-tailed P = 0.052). The other (chromosome 17, rs1531554, OR = 0.68, P = 2.9 × 10-8) was replicated among females (1-tailed P = 0.002), as well as replicated in meta-analysis of both sexes (1-tailed P = 0.021). A novel locus at genome-wide level of significance (rs73460075, OR = 0.56, P = 3.8 × 10-8) in the intron of the dystrophin gene DMD (X chromosome), and a suggestive locus on chromosome 7 (rs73271865, P = 2.9 × 10-7) upstream of the Sp4 Transcription Factor ( SP4) gene were identified in the discovery cohort, but neither of these was replicated. The SGCA gene encodes SGCA, which is involved in the cellular structure of muscle fibers and, along with DMD, forms part of the dystrophin-glycoprotein complex. Functional annotation suggested that several of these variants reside in loci that regulate processes relevant to TMD pathobiologic processes.

An empirically derived population-response model of the short form of the Oral Health Impact Profile.

OBJECTIVE: The aim of this paper was to model the consequences of dental conditions from an empirical basis and to test the model's ability to predict response combinations. METHODS: The model was derived from responses to the short-form Oral Health Impact Profile (OHIP14) obtained from a UK population sample of 5281 dentate adults. This model was then used to predict OHIP14 response combinations obtained from a sample of 3973 dentate and edentulous adults in Australia. FINDINGS: The empirically derived population-response model accounted for over 98% of response combinations of Australian dentate adults. CONCLUSIONS: The empirically derived model followed a similar hierarchical pattern to the base model underlying the long-form version of the measure (thereby supporting the validity of the OHIP14 measure) and was strongly predictive of the pattern of responses obtained from Australian adults.

Risk factors for dental caries in the five-year-old South Australian population.

BACKGROUND: This study tested the hypothesis that risk behaviours in disadvantaged groups would explain socio-economic inequality in dental caries prevalence among preschool children. METHODS: Using a case-control study, children with caries experience (one or more decayed, missing or filled primary tooth surfaces) and with no caries experience were sampled with known probabilities from among five year olds attending the South Australian Dental Service (SADS). Dental caries experience of primary teeth was recorded by SADS clinicians. Social and behavioural information was collected using a questionnaire mailed to parents. Prevalence rates, prevalence ratios (PR) and 95 per cent confidence intervals (95% CI) were computed, taking into account sampling probabilities. RESULTS: Questionnaires were obtained for 64.6 per cent of sampled children (n = 1398) and 40.2 per cent (95% CI = 37.8-42.6) of them had caries experience. Five statistically significant risk factors were identified relating to previous feeding, current oral hygiene and parent's own oral health perceptions. The prevalence of four risk factors was greater in low-income households compared with high-income households (P < or = 0.01). In multivariate analysis, after adjusting for age of tooth cleaning onset, age at which toothpaste was introduced was not significantly associated with caries prevalence. Behavioural risk factors did not explain income-related gradients in caries prevalence but modified the level of risk associated with delayed onset of tooth cleaning. Children who delayed tooth cleaning until the age of 24 months or more and who were from low-income households had a 2.7-fold increase in caries prevalence (95% CI = 2.1-3.4). CONCLUSIONS: Caries prevention efforts need to target behaviours in infancy and non-behavioural risk factors among preschoolers in low-income households.

Painful Temporomandibular Disorder: Decade of Discovery from OPPERA Studies.

In 2006, the OPPERA project (Orofacial Pain: Prospective Evaluation and Risk Assessment) set out to identify risk factors for development of painful temporomandibular disorder (TMD). A decade later, this review summarizes its key findings. At 4 US study sites, OPPERA recruited and examined 3,258 community-based TMD-free adults assessing genetic and phenotypic measures of biological, psychosocial, clinical, and health status characteristics. During follow-up, 4% of participants per annum developed clinically verified TMD, although that was a "symptom iceberg" when compared with the 19% annual rate of facial pain symptoms. The most influential predictors of clinical TMD were simple checklists of comorbid health conditions and nonpainful orofacial symptoms. Self-reports of jaw parafunction were markedly stronger predictors than corresponding examiner assessments. The strongest psychosocial predictor was frequency of somatic symptoms, although not somatic reactivity. Pressure pain thresholds measured at cranial sites only weakly predicted incident TMD yet were strongly associated with chronic TMD, cross-sectionally, in OPPERA's separate case-control study. The puzzle was resolved in OPPERA's nested case-control study where repeated measures of pressure pain thresholds revealed fluctuation that coincided with TMD's onset, persistence, and recovery but did not predict its incidence. The nested case-control study likewise furnished novel evidence that deteriorating sleep quality predicted TMD incidence. Three hundred genes were investigated, implicating 6 single-nucleotide polymorphisms (SNPs) as risk factors for chronic TMD, while another 6 SNPs were associated with intermediate phenotypes for TMD. One study identified a serotonergic pathway in which multiple SNPs influenced risk of chronic TMD. Two other studies investigating gene-environment interactions found that effects of stress on pain were modified by variation in the gene encoding catechol O-methyltransferase. Lessons learned from OPPERA have verified some implicated risk factors for TMD and refuted others, redirecting our thinking. Now it is time to apply those lessons to studies investigating treatment and prevention of TMD.

Impacts of oral disorders in the United Kingdom and Australia.

BACKGROUND: Surveys of oral health have not previously compared national adult populations using measures of subjective oral health. AIMS: To compare subjective oral health of adults in the UK and Australian populations. METHODS: Cross sectional studies were conducted of people aged 18+ years in the 1998 UK Adult Dental Health Survey and the 1999 Australian National Dental Telephone Interview Survey. Subjective oral health was measured using the 14-item Oral Health Impact Profile questionnaire (OHIP-14). RESULTS: Among dentate people, the percentage reporting impacts 'fairly often' or 'very often' was marginally greater in Australia (18.2%, 95% confidence interval (CI) = 16.2-20.2) than the UK (15.9%, 95%CI = 14.4-17.4). There were larger regional variations in prevalence within populations, ranging from 14.8% to 22.3% among Australian states/ territories, and from 13.6% to 19.8% among countries within the UK. However, the mean number of impacts and rated severity of impacts was significantly greater in Australia than the UK. CONCLUSIONS: While the percentage of adults reporting adverse impacts of oral health was similar, Australians reported a larger number of impacts and more severe impacts than dentate people in the UK. Differences in the number and severity of impacts between the two populations may be an artifact of different data collection methods or may reflect relatively subtle socio-cultural differences in subjective oral health between these populations.

Why do poor adults rate their oral health poorly?

BACKGROUND: The reasons why socioeconomic circumstances are associated with oral health are not well understood. This study investigated whether psychosocial factors might play an explanatory role. METHODS: Cross-sectional survey data were used from the 1999 National Dental Telephone Interview Survey together with information from an accompanying questionnaire sent to adult interviewees. Household income and self-rated oral health were assessed with single items and life dissatisfaction, personal constraint and perceived stress were evaluated with standard psychometric scales. Bivariate associations were tested using chi-square and ANOVA and odds ratios estimated for low self-rated oral health using logistic regression. RESULTS: Response to the questionnaire was 64.6 per cent and analysis was limited to dentate adults (n = 3678). Low household income was positively associated with low self-rated oral health. Higher dissatisfaction with life, personal constraint and perceived stress scores were associated with low income and with low self-rated oral health. After adjusting for gender, age, income and missing teeth, adults with high personal constraint scores had greater odds of low self-rated oral health (OR 1.26; 1.10-1.43) as had adults with higher perceived stress scores (OR 1.69; 1.34-2.13). CONCLUSION: Psychosocial factors are important in understanding pathways between socioeconomic position and oral health status.

COMT Diplotype Amplifies Effect of Stress on Risk of Temporomandibular Pain.

When measured once, psychological stress predicts development of painful temporomandibular disorder (TMD). However, a single measurement fails to characterize the dynamic nature of stress over time. Moreover, effects of stress on pain likely vary according to biological susceptibility. We hypothesized that temporal escalation in stress exacerbates risk for TMD, and the effect is amplified by allelic variants in a gene, catechol-O-methyltransferase (COMT), regulating catechol neurotransmitter catabolism. We used data from the Orofacial Pain: Prospective Evaluation and Risk Assessment prospective cohort study of 2,707 community-dwelling adults with no lifetime history of TMD on enrollment. At baseline and quarterly periods thereafter, the Perceived Stress Scale (PSS) measured psychological stress. Genotyped DNA from blood samples determined COMT diplotypes. During follow-up of 0.25 to 5.2 y, 248 adults developed examiner-verified incident TMD. PSS scores at baseline were 20% greater (P < 0.001) in adults who developed incident TMD compared with TMD-free controls. Baseline PSS scores increased by 9% (P = 0.003) during follow-up in cases but remained stable in controls. This stress escalation was limited to incident cases with COMT diplotypes coding for low-activity COMT, signifying impaired catabolism of catecholamines. Cox regression models confirmed significant effects on TMD hazard of both baseline PSS (P < 0.001), modeled as a time-constant covariate, and change in PSS (P < 0.001), modeled as a time-varying covariate. Furthermore, a significant (P = 0.04) interaction of COMT diplotype and time-varying stress showed that a postbaseline increase of 1.0 standard deviation in PSS more than doubled risk of TMD incidence in subjects with low-activity COMT diplotypes (hazard ratio = 2.35; 95% confidence limits: 1.66, 3.32), an effect not found in subjects with high-activity COMT diplotypes (hazard ratio = 1.42; 95% confidence limits: 0.96, 2.09). Findings provide novel insights into dynamic effects of psychological stress on TMD pain, highlighting that effects are most pronounced in individuals whose genetic susceptibility increases responsiveness to catecholamine neurotransmitters.

A preliminary investigation of shape memory alloys in the surgical correction of scoliosis.

Nitinol, a shape memory alloy, is flexible at low temperatures but retains its original shape when heated. This offers interesting possibilities for scoliosis correction. Of the shape memory alloys, nitinol is the most promising medically because of biocompatibility and the ability to control transition temperature. In vivo: Six goats with experimental scoliosis were instrumented with 6-mm nitinol rods. The rods were transformed, and the scoliosis corrected, in the awakened goats by 450-kHz radio frequency induction heating. The curves averaged 41 degrees before instrumentation, 33 degrees after instrumentation, and 11 degrees after rod transformation. The animals tolerated the heating without discomfort, neurologic injury, or evidence of thermal injury to the tissues or the spinal cord. In vitro: Nitinol rods were tested under both constant deflection and constant loading conditions and plotted temperature versus either force or displacement. The 6-mm rod generated forces of 200 N. The 9-mm rod generated up to 500 N. We safely coupled shape memory alloy transformation to the spine and corrected an experimental spinal deformity in awake animals. The forces generated can be estimated by the rod's curvature and temperature. The use of shape memory alloys allows continuous neurologic monitoring during awake correction, true rotational correction by rod torsion, and the potential option of periodic correction to take advantage of spinal viscoelasticity and the potential of true rotational correction by rod torsion.

Mechanisms of curve progression following sublaminar (Luque) spinal instrumentation.

Fifty-two patients with Luque instrumentation were reviewed for spinal deformities. Forty-two patients were reviewed during 1 year (longest 7.2 years) at follow-up. Two patients were included who lost correction within 1 year (both 8 months). Follow up averaged 2.9 years. Curve causes primarily were neuromuscular but included one was caused by idiopathic scoliosis, four by Scheuermann's disease, and 1 by post-laminectomy kyphosis. The Cobb angle progressed in 45% of patients postoperatively. Factors contributing to progression included progressive vertebral rotation or the crankshaft phenomenon (11), wire pull out (7), progressive pelvic obliquity (4), rod bending (3), pseudarthrosis (2), and rod migration (2). Factors correlating with progression were kyphosis, postoperative curve greater than 35 degrees, preoperative curve greater than 60 degrees, and not fusing to the pelvis in nonambulators. Crankshaft was common in patients Risser II or less but did not occur in more mature patients.