X-ray induced electron and ion fragmentation dynamics in IBr.

Characterization of the inner-shell decay processes in molecules containing heavy elements is key to understanding x-ray damage of molecules and materials and for medical applications with Auger-electron-emitting radionuclides. The 1s hole states of heavy atoms can be produced by absorption of tunable x rays and the resulting vacancy decays characterized by recording emitted photons, electrons, and ions. The 1s hole states in heavy elements have large x-ray fluorescence yields that transfer the hole to intermediate electron shells that then decay by sequential Auger-electron transitions that increase the ion's charge state until the final state is reached. In molecules, the charge is spread across the atomic sites, resulting in dissociation to energetic atomic ions. We have used x-ray/ion coincidence spectroscopy to measure charge states and energies of Iq+ and Brq'+ atomic ions following 1s ionization at the I and Br K-edges of IBr. We present the charge states and kinetic energies of the two correlated fragment ions associated with core-excited states produced during the various steps of the cascades. To understand the dynamics leading to the ion data, we develop a computational model that combines Monte-Carlo/Molecular-Dynamics (MC/MD) simulations with a classical over-the-barrier model to track inner-shell cascades and redistribution of electrons in valence orbitals and nuclear motion of fragments.

Assessing uncertainties in land cover projections.

Understanding uncertainties in land cover projections is critical to investigating land-based climate mitigation policies, assessing the potential of climate adaptation strategies and quantifying the impacts of land cover change on the climate system. Here, we identify and quantify uncertainties in global and European land cover projections over a diverse range of model types and scenarios, extending the analysis beyond the agro-economic models included in previous comparisons. The results from 75 simulations over 18 models are analysed and show a large range in land cover area projections, with the highest variability occurring in future cropland areas. We demonstrate systematic differences in land cover areas associated with the characteristics of the modelling approach, which is at least as great as the differences attributed to the scenario variations. The results lead us to conclude that a higher degree of uncertainty exists in land use projections than currently included in climate or earth system projections. To account for land use uncertainty, it is recommended to use a diverse set of models and approaches when assessing the potential impacts of land cover change on future climate. Additionally, further work is needed to better understand the assumptions driving land use model results and reveal the causes of uncertainty in more depth, to help reduce model uncertainty and improve the projections of land cover.

Pink-beam focusing with a one-dimensional compound refractive lens.

The performance of a cooled Be compound refractive lens (CRL) has been tested at the Advanced Photon Source (APS) to enable vertical focusing of the pink beam and permit the X-ray beam to spatially overlap with an 80 µm-high low-density plasma that simulates astrophysical environments. Focusing the fundamental harmonics of an insertion device white beam increases the APS power density; here, a power density as high as 500 W mm(-2) was calculated. A CRL is chromatic so it does not efficiently focus X-rays whose energies are above the fundamental. Only the fundamental of the undulator focuses at the experiment. A two-chopper system reduces the power density on the imaging system and lens by four orders of magnitude, enabling imaging of the focal plane without any X-ray filter. A method to measure such high power density as well as the performance of the lens in focusing the pink beam is reported.

Strength properties of preceramic brazed joints of a gold-palladium alloy with a microwave-assisted oven and gas/oxygen torch technique.

STATEMENT OF PROBLEM: The effect of microwave brazing on the strength properties of dental casting alloys is not yet known. PURPOSE: The purpose of this study was to compare the strength properties of preceramic brazed joints obtained by using a microwave oven and a conventional torch flame for a high noble alloy (Au-Pd). MATERIAL AND METHODS: A total of 18 tensile bars made of an Au-Pd ceramic alloy were fabricated. Six specimens were cut and joined with a high-fusing preceramic solder in a specially designed microwave oven, and 6 specimens were joined with a conventional natural gas/oxygen torch. The remaining 6 uncut specimens were tested as a control. All the specimens were subjected to testing with a universal testing machine. A 1-way ANOVA was performed for each strength property tested. RESULTS: The tensile strength of the uncut group was the highest (745 ±19 MPa), followed by the microwave group (420 ±68 MPa) and the conventional torch group (348 ±103 MPa) (P<.001); however, no significant difference in tensile strength was found between the microwave group and gas torch group. The tensile strength of the microwave group exceeded ANSI/ADA Standard No. 88, Dental Brazing Alloys (a joint standard of the American National Standards Institute and the American Dental Association). CONCLUSIONS: The microwave heating preceramic solder method demonstrated the excellent tensile strength of an Au-Pd alloy and may be an alternative way of joining alloys when a torch flame is contraindicated.

Attitudes toward monitoring blood pressure and blood sugar at a New York State dental school.

The aim of this retrospective study was to assess dental patient, physician and dental student attitudes toward blood pressure and glycemic monitoring within a dental school environment. The responses of these cohort groups were analyzed by using an Institutional Review Board-approved survey. Physicians and dental students viewed blood pressure monitoring positively, while patients were less enthusiastic. All three groups viewed measuring blood sugar on diabetic patients prior to dental surgery as important, but not on a routine basis.

Comparison of bleaching effects when applied to white-spot lesions before or after resin infiltration: An in vitro study.

BACKGROUND: The purpose of this study was to compare color alterations (ΔE) of white-spot lesions (WSLs) bleached before versus after resin infiltration (RI). METHODS: Using the facial surfaces of bovine maxillary incisors, WSLs were created and the teeth were allocated into 2 groups (n = 45/group): bleach then RI (B-RI group) and RI then bleach (RI-B group). To determine ΔE, Commission Internationale de l'Eclairage L∗ a∗ b∗ (L∗ represents lightness, ranging from black to white [0-100]; a∗ represents green to red chromaticity [-150-+100]; and b∗ represents blue to yellow chromaticity [-100-+150]) measurements were obtained at baseline, after WSL formation, and after RI and bleaching. Representative specimens were evaluated by means of scanning electron microscopy. Statistical analyses included the Mann-Whitney U and Wilcoxon signed rank tests (P ≤ .0016) and repeated measures analysis of variance (P ≤ .05). RESULTS: No differences in ΔE were found comparing B-RI with RI-B groups or when the B-RI group was compared with bleached enamel. A statistically significant difference was found when the RI-B group was compared with bleached enamel (ΔE, 0.81; P < .001), but the difference was deemed not clinically significant. Scanning electron microscopy revealed that bleaching after RI increased surface roughness of the resin. CONCLUSIONS: There were no clinically significant differences in ΔE of WSLs when bleach was applied before or after RI; however, applying bleaching agent after RI roughened the surface of the resin material. PRACTICAL IMPLICATIONS: Results indicate that ΔE were not clinically significantly different between WSLs bleached before versus after RI, although it is best to sequence bleaching before RI therapy, as bleaching after RI roughened the restoration's surface.

Effects of Invisalign (G5) with virtual bite ramps for skeletal deep overbite malocclusion correction in adults.

OBJECTIVES: To investigate the skeletal and dentoalveolar effects of Invisalign's G5 protocol with virtual bite ramps in the treatment of adults with skeletal deep bites. MATERIALS AND METHODS: This retrospective study was conducted on consecutively treated adults presenting with skeletal deep bites as defined by the Overbite Depth Indicator (ODI). Subjects were divided into 2 groups: Invisalign group (n = 24) treated with the Invisalign G5 protocol and a full fixed appliance (FFA) group (n = 24) treated with edgewise FFAs and matched to the Invisalign group by ODI, sex, type of malocclusion, and non-extraction treatment. Pretreatment (T1) and post-comprehensive treatment (T2) lateral cephalograms were obtained and analyzed. RESULTS: Both the Invisalign and FFA groups showed significant changes from T1 to T2 in ODI and other skeletal and dentoalveolar measurements. The mean change in ODI was -1.5° (P < .001) for the Invisalign group and -2.0° (P < .001) for the FFA group. The mean decrease in overbite was 1.3 mm (P < .001) and 2.0 mm (P < .001) for the Invisalign and FFA groups, respectively. The mean increase in mandibular plane angle (Sn-GoGn) was 0.65° (P = .003) for the Invisalign group and 1.15° (P < .001) for the FFA group. When the groups were compared with each other, both ODI (P = .03) and overbite (P = .003) were significantly different in addition to other measurements. CONCLUSIONS: Although FFA treatment had more apparent skeletal changes for deep bite adult patients when compared with Invisalign, both systems were effective in opening deep bites at dentoalveolar and skeletal levels.

Mechanobehavior and mandibular ramus length in different facial phenotypes.

OBJECTIVES: To test the hypotheses that mechanobehavior scores (MBS) were correlated with mandibular ramus lengths (Co-Go) and differed between facial phenotypes. MATERIALS AND METHODS: Subjects gave informed consent to participate. Co-Go (mm), mandibular plane angles (SN-GoGn, °), and three-dimensional anatomy were derived from cephalometric radiography or cone beam computed tomography. Temporomandibular joint (TMJ) energy densities (ED) (mJ/mm3) were measured using dynamic stereometry and duty factors (DF) (%) were measured from electromyography, to calculate MBS (= ED2 × DF,) for each TMJ. Polynomial regressions, K-means cluster analysis, and analysis of variance (ANOVA) with Tukey post-hoc tests were employed. RESULTS: Fifty females and 23 males produced replete data. Polynomial regressions showed MBS were correlated with Co-Go (females, R2 = 0.57; males, R2 = 0.81). Cluster analysis identified three groups (P < .001). Dolichofacial subjects, with shorter normalized Co-Go, clustered into two subgroups with low and high MBS compared to brachyfacial subjects with longer Co-Go. SN-GoGn was significantly larger (P < .03) in the dolichofacial subgroups combined (33.0 ± 5.9°) compared to the brachyfacial group (29.8 ± 5.5°). CONCLUSIONS: MBS correlated with Co-Go within sexes and differed significantly between brachyfacial and dolichofacial subjects.

Validity of self-reported measures for surveillance of periodontal disease in two western New York population-based studies.

BACKGROUND: Public health and other population-based studies often depend on participants' self-reported disease status to assess prevalence, incidence, and disease trends. We sought to assess the feasibility of self-reported periodontal disease measures using dental history questions combined with demographic and medical history to predict periodontal disease. METHODS: We evaluated results from two separate population-based studies carried out at the University at Buffalo, Buffalo, New York, i.e., the "Periodontal Infection and Risk for Myocardial Infarction Study," a study of 1,578 adults assessing the association between periodontal disease and myocardial infarction and the "Periodontal Disease Research Center" (the Erie County Study), an epidemiologic risk assessment study of 1,438 adults. In each study, an extensive list of oral health questions was asked, and a comprehensive medical history, blood analysis using chemistry and hematology tests, and demographic data were collected. RESULTS: Using a predefined measure of severity of periodontal disease, we compared patients with severe disease to all others (i.e., those with moderate and no or mild disease). We examined areas under the curve (AUC) of the receiver operating curve to determine the best models, adding one, two, or three dental variables in all possible combinations. The AUC maximized at 0.76, and the combined sensitivity and specificity maximized at 142 and were comparable in both studies. CONCLUSIONS: Self-reported measures of periodontal disease are moderately predictive of clinical attachment loss. The demographic variables of age, race, smoking, gender, and diabetes mellitus accounted for much of the predictive power for self-reported periodontal disease; however, increases in sensitivity and specificity in the C statistics occurred when questions, including "Gum surgery in the past?," "Sore gums in the past?," "Scaling in the past?," "Bleeding gums now?," "Periodontal surgery in the past 2 years?," and "Chewing satisfaction?," were added to the model.

Malocclusion as a risk factor in the etiology of headaches in children and adolescents.

INTRODUCTION: The purpose of this study was to determine the importance of occlusal factors in recurrent headaches in children and adolescents without other signs or symptoms of temporomandibular disorders or related craniomandibular disorders. METHODS: A sample of 50 children and adolescents, ages 8 to 16, who reported headaches was obtained from the University at Buffalo Orthodontic Clinic records; a control group of 50 children and adolescents, matched for age and sex, was also obtained. Plaster models, made during the routine collection of orthodontic records, were used to obtain the following occlusal trait measurements: Angle classification, overjet, anterior and posterior crossbite, scissors-bite, overbite, open bite, dental midline discrepancy, crowding, spacing, and dental development stage. RESULTS: Overbite, overjet, and posterior crossbite showed statistically significant associations (chi-square) with increased risk for headaches. Logistic regression analysis demonstrated that overjet was a significant factor only because of its correlation with overbite and posterior crossbite. Overjet was not significant after adjusting for the other 2 variables, whereas overbite and posterior crossbite were associated with significantly increased risk (>3:1) of headache. The combination of 2 or more of these 3 occlusal factors increased the risk of headache even more (8.5:1). CONCLUSIONS: Posterior crossbite and overbite > or =5 mm were associated with significantly increased risk of headache in children and adolescents.

Ecosystem service provision in a changing Europe: adapting to the impacts of combined climate and socio-economic change.

CONTEXT: Future patterns of European ecosystem services provision are likely to vary significantly as a result of climatic and socio-economic change and the implementation of adaptation strategies. However, there is little research in mapping future ecosystem services and no integrated assessment approach to map the combined impacts of these drivers. OBJECTIVE: Map changing patterns in ecosystem services for different European futures and (a) identify the role of driving forces; (b) explore the potential influence of different adaptation options. METHODS: The CLIMSAVE integrated assessment platform is used to map spatial patterns in services (food, water and timber provision, atmospheric regulation, biodiversity existence/bequest, landscape experience and land use diversity) for a number of combined climatic and socio-economic scenarios. Eight adaptation strategies are explored within each scenario. RESULTS: Future service provision (particularly water provision) will be significantly impacted by climate change. Socio-economic changes shift patterns of service provision: more dystopian societies focus on food provision at the expense of other services. Adaptation options offer significant opportunities, but may necessitate trade-offs between services, particularly between agriculture- and forestry-related services. Unavoidable trade-offs between regions (particularly South-North) are also identified in some scenarios. CONCLUSIONS: Coordinating adaptation across regions and sectors will be essential to ensure that all needs are met: a factor that will become increasingly pressing under dystopian futures where inter-regional cooperation breaks down. Integrated assessment enables exploration of interactions and trade-offs between ecosystem services, highlighting the importance of taking account of complex cross-sectoral interactions under different future scenarios of planning adaptation responses.

Association of Masseter Muscle Activities during Awake and Sleep Periods with Self-Reported Anxiety, Depression, and Somatic Symptoms.

AIM AND BACKGROUND: The objective of this study was to determine if duty factors (DF) of low-magnitude MMA during awake and sleep periods were associated with self-reports of anxiety, depression, and somatic symptoms, and if so, whether or not any associations were modified by gender or the presence of pain. Limited information is currently available in the literature regarding the association of low-magnitude masseter muscle activities (MMA) in habitual environmental settings and the presence of psychological symptoms. MATERIALS AND METHODS: Sixty-eight consenting participants were classified using the Diagnostic Criteria for Temporomandibular Disorders examination and validated self-reporting psychological symptom evaluation questionnaires. Each subject also had masseter electromyography recordings during standardized biting tasks in 2 laboratory sessions to calibrate the in-field MMA collected during 3 awake and 3 sleep periods. RESULTS: During awake periods, subjects with self-reported depression and somatic symptoms had statistically high odds of having higher DF of low-magnitude MMA (defined by ≥ 75th percentile of sample). The association between high DF of low-magnitude MMA and self-reported depression symptoms was significantly augmented among male participants, whereas, the association between high DF of low-magnitude MMA and self-reported somatic symptoms was significantly increased among female participants without pain. CONCLUSION: These pilot data support associations of low-magnitude masseter muscle activities with self-reported depression and somatic symptoms during awake periods.

Screening for diabetes mellitus in dental practices: a field trial.

BACKGROUND: In this field trial, the authors assess the feasibility of screening for diabetes and prediabetes in dental practices and in a community health center. METHODS: Dental patients 45 years and older who were not aware of their diabetic status underwent evaluation for diabetes risk with an American Diabetes Association Diabetes Risk Test and with hemoglobin (Hb) A1c measurement. Participants with an HbA1c level of 5.7 percent or greater were referred to their physicians for diagnosis. RESULTS: Of the 1,022 patients screened, 416 (40.7 percent) had an HbA1c blood level of 5.7 percent or greater and were referred for diagnosis. The HbA1c and the American Diabetes Association Diabetes Risk Test were correlated (P < .001). Of the 416 participants who were referred, 35.1 percent received a diagnosis from their physicians within one year; 78.8 percent of these patients were seen in the community health center and 21.4 percent were seen in private dental offices. The diagnoses were diabetes (12.3 percent of patients), high risk of developing diabetes (that is, prediabetes) (23.3 percent) and no diabetes (64.4 percent). CONCLUSIONS: The study results show that screening for prediabetes and diabetes is feasible in a dental office, with acceptance by the dentist and dental office staff members, patients' physicians and patients. Patients from the community health center demonstrated good compliance with referrals to physicians; however, compliance was poor among those in the private dental offices. PRACTICAL IMPLICATIONS: Screening for diabetes and prediabetes in the dental office may provide an important benefit to patients and encourage interprofessional collaboration to achieve a chronic care model in which health care professionals work together to care for a panel of patients.

Forest land cover continues to exacerbate freshwater acidification despite decline in sulphate emissions.

Evidence from a multi-date regional-scale analysis of both high-flow and annual-average water quality data from Galloway, south-west Scotland, demonstrates that forest land cover continues to exacerbate freshwater acidification. This is in spite of significant reductions in airborne pollutants. The relationship between freshwater sulphate and forest cover has decreased from 1996 to 2006 indicating a decrease in pollutant scavenging. The relationship between forest cover and freshwater acidity (pH) is, however, still present over the same period, and does not show conclusive signs of having declined. Furthermore, evidence for forest cover contributing to a chlorine bias in marine ion capture suggests that forest scavenging of sea-salts may mean that the forest acidification effect may continue in the absence of anthropogenic pollutant inputs, particularly in coastal areas.

Levels of serum immunoglobulin G specific to bacterial surface protein A of Tannerella forsythia are related to periodontal status.

BACKGROUND: Tannerella forsythia (Tf) is a Gram-negative anaerobe implicated in the development of periodontal disease. Bacterial surface protein A (BspA) is a surface-expressed and -secreted protein that is recognized as an important virulence factor of Tf. This study was undertaken to determine whether Tf BspA induces an antibody response in periodontal disease. We hypothesized that serum immunoglobulin (Ig)G antibody levels against BspA correlate with the disease of patients. METHODS: Sera were obtained from 100 patients with cardiac disorders and periodontal disease and 73 patients who experienced myocardial infarction but were periodontally healthy. Sera samples were assayed for anti-BspA antibody (total IgG and IgG subtypes) by enzyme-linked immunosorbent assay (ELISA). Antibody levels were measured in ELISA units by using an arbitrary patient as a standard. RESULTS: A negative correlation was found with BspA-specific total IgG antibody titers and the severity of disease measured as the clinical attachment level (CAL) when healthy and diseased groups were analyzed separately (healthy group: [-0.23, correlation value] Student's t value [73 degrees of freedom] = 1.99; P = 0.05; diseased group: [-0.21] t [100 degrees of freedom] = 2.12; P = 0.03]). However, there was a positive correlation ([0.18 correlation value] Student's t value [173 degrees of freedom] = 2.39; P = 0.017) when healthy and diseased groups were combined. A strong positive correlation ([0.338 correlation value] Student's t value [173 degrees of freedom] = 4.69; P <0.0001) between the BspA-specific IgG titers and periodontal probing depth was observed when healthy and disease groups were combined. CONCLUSIONS: Data demonstrated that antibodies to Tf BspA were elicited in patients with periodontal disease, and antibody levels were associated with the disease severity. Furthermore, data suggested that anti-BspA IgG might have a protective function in periodontal disease by minimizing the loss of tooth attachment tissue.

In vitro model to evaluate reliability and accuracy of a dental shade-matching instrument.

STATEMENT OF PROBLEM: There are several electronic shade-matching instruments available for clinical use; unfortunately, there are limited acceptable in vitro models to evaluate their reliability and accuracy. PURPOSE: The purpose of this in vitro study was to evaluate the reliability and accuracy of a dental clinical shade-matching instrument. MATERIAL AND METHODS: Using the shade-matching instrument (ShadeScan), color measurements were made of 3 commercial shade guides (VITA Classical, VITA 3D-Master, and Chromascop). Shade tabs were selected and placed in the middle of a gingival matrix (Shofu Gummy), with tabs of the same nominal shade from additional shade guides placed on both sides. Measurements were made of the central region of the shade tab inside a black box. For the reliability assessment, each shade tab from each of the 3 shade guide types was measured 10 times. For the accuracy assessment, each shade tab from 10 guides of each of the 3 types evaluated was measured once. Reliability, accuracy, and 95% confidence intervals were calculated for each shade tab. Differences were determined by 1-way ANOVA followed by the Bonferroni multiple comparison procedure. RESULTS: Reliability of ShadeScan was as follows: VITA Classical = 95.0%, VITA 3D-Master = 91.2%, and Chromascop = 76.5%. Accuracy of ShadeScan was as follows: VITA Classical = 65.0%, VITA 3D-Master = 54.2%, Chromascop = 84.5%. CONCLUSIONS: This in vitro study showed a varying degree of reliability and accuracy for ShadeScan, depending on the type of shade guide system used.

Validity of Self-Reported Measures for Surveillance of Periodontal Disease in Two Western New York Population-Based Studies.

BACKGROUND: Public health and other population-based studies often depend on participants' self-reported disease status to assess prevalence, incidence, and disease trends. We sought to assess the feasibility of self-reported periodontal disease measures using dental history questions combined with demographic and medical history to predict periodontal disease. METHODS: We evaluated results from two separate population-based studies carried out at the University at Buffalo, Buffalo, New York, i.e., the "Periodontal Infection and Risk for Myocardial Infarction Study," a study of 1,578 adults assessing the association between periodontal disease and myocardial infarction and the "Periodontal Disease Research Center" (the Erie County Study), an epidemiologic risk assessment study of 1,438 adults. In each study, an extensive list of oral health questions was asked, and a comprehensive medical history, blood analysis using chemistry and hematology tests, and demographic data were collected. RESULTS: Using a predefined measure of severity of periodontal disease, we compared patients with severe disease to all others (i.e., those with moderate and no or mild disease). We examined areas under the curve (AUC) of the receiver operating curve to determine the best models, adding one, two, or three dental variables in all possible combinations. The AUC maximized at 0.76, and the combined sensitivity and specificity maximized at 142 and were comparable in both studies. CONCLUSIONS: Self-reported measures of periodontal disease are moderately predictive of clinical attachment loss. The demographic variables of age, race, smoking, gender, and diabetes mellitus accounted for much of the predictive power for self-reported periodontal disease; however, increases in sensitivity and specificity in the C statistics occurred when questions, including "Gum surgery in the past?," "Sore gums in the past?," "Scaling in the past?," "Bleeding gums now?," "Periodontal surgery in the past 2 years?," and "Chewing satisfaction?," were added to the model.

Prediction accuracy of computer-assisted surgical visual treatment objectives as compared with conventional visual treatment objectives.

PURPOSE: This present study used the conventional visualized treatment objectives (VTOs) as a tool to evaluate the predictive value of the Dolphin computer-assisted VTOs. MATERIALS AND METHODS: Presurgical cephalometric tracing predictions generated by oral and maxillofacial surgeons and the Dolphin Imaging software were compared with the postsurgical outcome as seen on lateral cephalometric tracings. Sixteen measurements of the predicted and actual postsurgical hard tissue landmarks were compared statistically. RESULTS: A paired Student's t test showed that 7 measurements had statistically significant differences for the conventional VTOs (facial angle, P < .0001; AOC, P < .0001; SNB, P = .003; ANB, P = .004; U1-NA-degrees, P = .01; U1-NA-mm, P = .02; and N perp Pog, P < .0001), while 9 measurements were statistically significant ( P = <.0001) for Dolphin (facial angle, P = .0001; AOC, P = .005; SNB, P = .001; ANB, I = .04; U1-NA-degrees, P = .003; PogNB, P = .04; U1-NA-mm, P = .002; N perp Pog, P = .0001; UFH, P = .03; and LFH, P = .03). CONCLUSION: From these data, it appears that both VTOs demonstrated good predictive comparative outcome and are equally precise.

The Role of Osteopenia in Oral Bone Loss and Periodontal Disease.

Osteoporosis and periodontitis are diseases which affect a large number of women and men, with incidence increasing with advancing age. Osteopenia is a reduction in bone mass due to an imbalance between bone resorption and formation, favoring resorption, resulting in demineralization and leading to osteoporosis. Osteoporosis is a disease characterized by low bone mass and fragility and a consequent increase in fracture risk. Periodontitis is characterized by inflammation of the supporting tissues of the teeth, resulting in resorption of the alveolar bone as well as loss of the soft tissue attachment to the tooth and is a major cause of tooth loss and edentulousness in adults. The relationship of osteopenia to oral bone loss and periodontal disease has been addressed in a limited number of studies. A review of current knowledge regarding this relationship is presented. Interpretation of the literature is complicated by the variety of methods used to assess osteopenia, oral bone mass, and periodontitis, as well as varying definitions of outcomes of interest. Results of a previously unpublished study are presented which suggest that severity of osteopenia is related to loss of alveolar crestal height and tooth loss in post-menopausal women. The literature on the relationship among these disorders is limited and points to the need for additional studies which thoroughly evaluate the influence of potential confounding factors to further define the relationship between low bone mineral density and periodontal disease in larger populations. Clearer understanding of this relationship may aid health care providers in their efforts to detect and prevent osteoporosis and periodontal disease. Increased dialogue among medical and dental professionals will be increasingly important in achieving and maintaining patients' optimal health. J Periodontol 1996;67:1076-1084.