3D Printing Phosphonium Ionic Liquid Networks with Mask Projection Microstereolithography

Photopolymerization coupled with mask projection microstereolithography successfully generated various 3D printed phosphonium polymerized ionic liquids (PILs) with low UV light intensity requirements and high digital resolution. Varying phosphonium monomer concentration, diacrylate cross-linking comonomer, and display images enabled precise 3D design and polymeric properties. The resulting cross-linked phosphonium PIL objects exhibited a synergy of high thermal stability, tunable glass transition temperature, optical clarity, and ion conductivity, which are collectively well-suited for emerging electro-active membrane technologies. Ion conductivity measurements on printed objects revealed a systematic progression in conductivity with ionic liquid monomer content, and thermal properties and solvent extraction demonstrated the formation of a polymerized ionic liquid network, with gel fractions exceeding 95%.

The influence of smoking on 3-year clinical success of osseointegrated dental implants

BACKGROUND

Health risks associated with smoking have been exhaustively documented and include increased incidence of periodontal disease, greater risk of osteitis following oral surgery, and compromised wound healing due to hypoxia. Information related directly to dental implants, although limited, points to higher rates of implant failures among smokers than non-smokers. This paper reports on long-term clinical outcomes of osseointegrated dental implants placed in smokers and non-smokers in a longitudinal clinical study of endosseous dental implants.

METHODS

In 1990, the Dental Implant Clinical Research Group (DICRG) of the Department of Veterans Affairs (DVA) launched an 8-year, randomized, prospective clinical study of more than 2,900 endosseous dental implants in more than 800 patients at 32 study centers. Confounding variables, including smoking patterns, were recorded. For this report, new follow-up data were analyzed for two groups: 1) current smokers and 2) those who never smoked combined with those who quit. Most of the variables recorded for each implant were screened on a univariate basis as possible predictors associated with implant survival/failure. Those with P values less than 0.15 and those likely to be a factor of clinical importance were placed in a logistic regression equation and analyzed for a simultaneous effect on survival. A step-wise procedure was used to eliminate those variables that showed the least significance, until only those variables with a Wald chi-square of significance in the presence of others remained. The effects of clustering within patients and of unbalanced distribution within hospitals were standardized to facilitate analysis of influence of demographic variables. The GEE analysis was performed with the patient as the primary cluster.

RESULTS

Current data do not support earlier findings that smoking contributes to early implant failure (placement to uncovering). A trend of greater failures in smokers appeared between the time after uncovering and before insertion of the prosthesis. Hydroxyapatite (HA)-coated implants had significantly lower failure rates. For the entire 3-year period, overall failures were significantly higher for smokers than non-smokers.

CONCLUSIONS

Results suggest that increased implant failures in smokers are not the result of poor healing or osseointegration, but of exposure of peri-implant tissues to tobacco smoke. Data also suggest that detrimental effects may be reduced by: 1) cessation of smoking; 2) the use of preoperative antibiotics; and 3) the use of HA-coated implants.

Biochemical evidence of cannibalism at a prehistoric Puebloan site in southwestern Colorado

The existence of cannibalism is one of the most controversial issues in the archaeology of the American Southwest. Disarticulated, cut-marked and heat-altered human remains from non-burial contexts at prehistoric Puebloan (Anasazi) archaeological sites in the Four Corners region of the American Southwest have been interpreted by some scholars as evidence of cannibalism. Osteological studies indicate that many of the disarticulated bodies found at these sites were processed in a manner consistent with food preparation. Opponents of this interpretation point out that non-cannibalistic practices such as secondary interment, corpse mutilation and ritualized witch executions might account for the assemblages. Osteological evidence alone does not document the actual ingestion of human flesh. Here we show consumption of human flesh did occur as demonstrated in preserved human waste containing identifiable human tissue remains from a site with osteological evidence of cannibalism.

Detection of radiation-induced, accelerated atherosclerosis in patients with osteoradionecrosis by panoramic radiography

PURPOSE

Osteoradionecrosis (ORN) of the mandible has long been considered the most destructive complication of head and neck irradiation. Recently, therapeutic irradiation has been implicated as the cause of induced/accelerated atherosclerosis of the cervical carotid artery and subsequent stroke. Panoramic radiography, previously shown to be capable of identifying carotid artery atherosclerosis in nonirradiated individuals, was used to assess the carotid vasculature of patients being treated for ORN.

PATIENTS AND METHODS

The panoramic radiographs of 61 men (mean age, 60.5 years; range, 41 to 77 years) who received therapeutic irradiation to the neck 36 months or more previously were assessed for the presence of carotid artery atherosclerotic lesions. Sixty-one control subjects who never received therapeutic irradiation, but who were similarly susceptible to atherosclerosis by virtue of age, were assessed in a like manner.

RESULTS

The irradiated individuals sustained a dose of 40 to 72 Gy to the area of the carotid bifurcation. Seventeen individuals (27.9%) with an irradiation dosage to the carotid bifurcation that averaged 59.2 Gy had a panoramic radiograph with a carotid atheroma (11 with unilateral lesions and six with bilateral lesions). The radiographs of the control subjects showed that three individuals (4.9%) had calcified carotid lesions. The mean age of these subjects was 66.1 years; two had unilateral lesions, and one had bilateral lesions. The difference in the proportion of individuals with ORN who manifested carotid artery atherosclerosis on their panoramic radiographs was statistically significant (P = .001) when compared with the nonirradiated control subjects. The lesions seen in both populations had a similar morphologic appearance and were radiographically located within the soft tissues of the neck 1.5 to 4.0 cm inferior-posterior to the angle of the mandible.

CONCLUSIONS

Individuals with radiation doses sufficient to cause osteoradionecrosis of the mandible are at significantly higher risk of developing carotid artery atherosclerotic lesions than age-matched, nonirradiated controls.

The influence of maxillary sinus augmentation on the success of dental implants through second-stage surgery

An interim evaluation of the status of 102 implants placed in 42 augmented sinuses in 27 patients involved in an alternate category of the Dental Implant Clinical Research Group's long-term, randomized, prospective clinical investigation is presented. Autogeneic, allogeneic, and alloplastic sinus grafts were used, individually or mixed. Through second-stage surgery, 101 implants were found to be integrated. The mean Periotest value at uncovering was -3.36, with a standard deviation of 4.19. The results suggest that root form implants placed in augmented sinuses are successful through second-stage surgery, regardless of the augmentation material or implant design used.

Positive effect of surgical experience with implants on second-stage implant survival

This Dental Implant Clinical Research Group study defined a learning curve for dental implant placement. Implants placed by inexperienced surgeons (< 50 implants) failed twice as often as those placed by experienced surgeons (> or = 50 implants). Implants placed during the first 6, 8, 10, 12, and 16 cases were compared with all others. The greatest difference was seen between the first nine cases and all others (P = .001), with later cases failing significantly less often. Inexperienced surgeons had more failures in the first nine cases (5.9%) than more experienced surgeons (2.4%). Surgeons with little or no previous experience must expect a definite learning curve. Previous experience may transfer and result in a shallower learning curve for subsequent systems.

The influence of 0.12% chlorhexidine digluconate rinses on the incidence of infectious complications and implant success

The effect of perioperative chlorhexidine on the frequency of infectious complications through stage II was examined. Chlorhexidine was used perioperatively in 54.6% of patients (52.5% of implants) in a Dental Implant Clinical Research Group study with a database of 2,641 implants (595 patients). With chlorhexidine, there was a significant reduction in the number of infectious complications (4.1% vs 8.7%). Two percent of implants failed in the absence of an infectious complication, whereas 12% with infectious complications failed. This sixfold difference is highly significant. Chlorhexidine may reduce microbial complications when used in the immediate perioperative period.

Skeletal evidence for child abuse: a physical anthropological perspective

Analysis of the skeletal remains of abused children can prove challenging for forensic pathologists and radiographers who are inexperienced in the direct examination of bones. In such cases, radiographically invisible skeletal lesions that document a history of trauma can often be identified by a physical anthropologist with appropriate osteological experience. This is illustrated by cases in which skeletal remains of four murdered children and a mentally handicapped adult produced evidence of antemortem trauma and perimortem injuries that was critical in developing murder cases against the assailants. In these cases, well-healed areas of subperiosteal new bone formation were identified that were below the threshold of radiographic detection. Such injuries provide strong evidence for a history of physical abuse.

The effect of smoking on implant survival at second-stage surgery: DICRG Interim Report No. 5. Dental Implant CLinical Research Group

Smoking has been reported to have a deleterious effect on the oral cavity. Research has associated smoking with oral cancer, periodontal disease, leukoplakia, stomatitis nicotina, and impaired gingival bleeding. In 1991 the Dental Implant Clinical Research Group initiated a prospective, randomized clinical study in cooperation with the Department of Veterans Affairs to investigate the influence of implant design, application, and site of placement on long-term clinical performance and crestal bone height. Over 70 dental and medical history variables and exclusion factors were analyzed to determine relationships, if any, with implant failure at the time of second-stage surgery. The variables were analyzed separately for individual implants, cases (prostheses), and patients. The cases ranged from one to five implants each, and more than one case from a single patient could be included in the investigation. At this interim analysis, 2,066 implants have been placed representing 433 cases in 310 patients. With regard to implant failure rates, possible exclusion variable (9) and medical history variables (39) were not found to be statistically significant. For the dental history variables (23), only the question related to smoking was statistically significant on an implant, case, and patient basis (P < 0.007). Results of this interim analysis suggest that smoking is detrimental to implant success.

Technique for standardization of panoramic radiographs using helium-neon laser guided positioning

A limitation of the use of panoramic radiography in implant dentistry has been variations in patient positioning, which can produce dissimilar radiographs and is a serious problem in longitudinal investigations. Previous techniques to standardize panoramic radiographs have been cumbersome and technique sensitive. Bilateral helium-neon lasers were mounted on two-axis micrometer translation stages and projected as cross-hairs on a phantom skull. The cross-point of each pattern was superimposed on a facial soft tissue landmark on either side of the skull. Laser coordinates were recorded and an initial radiograph was produced for each of three experimental groups. Two investigators repeated radiographs for each group six times using the original settings. The radiographs were digitized and the variance calculated and compared using a video digital analysis program. Repeat radiographs were compared to the originals by superimposing each pair and measuring the variance in radiographic markers. The variance ranged from 0.1 to 2.2 mm with the experimental groups and from 2.5 to 38.7 mm with the control group. Repeated measures analysis of variance showed no statistical significance (P > 0.125) among each of the experimental groups using the laser system and a significant difference (P < 0.001) when the control group is included in the analysis. Variance for experimental groups was not significant between the examiners (P > 0.45). A laser repositioning system may have application in implant dentistry by standardizing panoramic radiographs for comparisons in long-term investigations.

Three-dimensional computed tomography and anatomic replicas in surgical treatment planning. Report of a case

A case that demonstrates the use of three-dimensional computed tomography and anatomic replication in the management of a severe anterolateral open bite deformity is presented. Preoperative surgical treatment planning was facilitated by rehearsal model surgery. Construction of an accurate surgical splint enabled precise positioning of osteotomized segments at surgery.

Age and sex biases in the preservation of human skeletal remains

Inaccuracies introduced through biases in preservation are a major source of error in paleodemographic reconstructions. Although it is generally assumed that such biases exist, little is known about their magnitude. To investigate this problem, we studied age and sex differences in the preservation of skeletal remains from Mission La Purisima and a prehistoric cemetery (Ca-Ven-110). Comparison of mortality profiles obtained through analysis of skeletal remains and burial records from the mission indicates that biases in preservation can be very significant in poorly preserved skeletal collections. The Purisima burial records show that most of the people interred in the cemetery were either infants or elderly adults. The skeletal remains, in contrast, are predominantly those of young adults. The burial records and skeletal collection produced comparable sex ratios. These results show that age biases in preservation are much more important than sex biases. This conclusion is supported by data on the completeness of the skeletons from La Purisima and Ca-Ven-110. At both sites, the remains of young adults were better preserved than those of children or elderly adults, and the completeness of male and female skeletons was comparable.

Hemimandibulectomy without bone grafting: report of a case

Some patients require hemimandibulectomy who are poor candidates for reconstructive surgery or who do not want to subject themselves to multiple surgical episodes. With the use of an articulated external skeletal fixation appliance, near-normal esthetics and function can be achieved in these patients without bone grafting. A report of one such case is presented.

A two-piece surgical splint to facilitate hydroxylapatite augmentation of the mandibular alveolar ridge

Details of the design and fabrication of a two-piece splint that facilitates the HA augmentation of the mandibular alveolar ridge are presented. The use of the splint has eliminated migration of HA particles, reduced elevation of the vestibule, and increased the predictability of the outcome of the procedure.

The British-Norwegian migrant study: 5-year mortality differentials due to cigarette smoking

Cigarette smoking and 5-year survivorship of 20,017 British and 10,016 Norwegian migrants to the United States were compared with 17,696 British and 26,155 Norwegian nonmigrants. The highest mortality ratios for 5-year age-adjusted death rates observed were of cigarette smokers to nonsmokers, ranging from 1.40 to 1.60 for men and from 1.18 to 1.36 for women. Mortality ratios of nonmigrants to migrants ranged from 1.07 to 1.19 for men and from 1.22 to 1.36 for women. Mortality ratios for British to Norwegian groups ranged from 1.13 to 1.27. Some differences in mortality ratios for cardiovascular diseases contrasted with mortality ratios for noncardiovascular diseases were noted. The most important of these differences was the apparent lack of any consistent difference between nonmigrants and migrants in their 5-year cardiovascular mortality rates, although there were consistent differences for noncardiovascular diseases.

Dermal grafts to bony defects in irradiated and nonirradiated tissues

Coverage of intraoral ablative defects presents many different problems. Free dermal grafts have been used to cover exposed mandibular bone in dogs. Grafts were placed in animals both before and after irradiation. Grafts were uniformly successful in animals not previously irradiated but failed when placed after irradiation.

Autogenous dermal graft coverage of submerged roots in the dog

Dermal grafts were compared with conventional supraperiosteal recipient beds grafted with split-thickness skin for covering submerged vital roots in six dogs. Several potential advantages of this new technique are suggested.

Free autogenous graft coverage of vital retained roots

The use of free autogenous grafts to the alveolus during root submergence was shown to be a method that might be used to prevent the loss of masticatory mucosa and vestibular depth, which have been regarded as problems associated with the procedure.

The British-Norwegian migrant study--analysis of parameters of mortality differentials associated with angina

The prevalence of selected cardiorespiratory symptoms was ascertained by a common mail questionnaire for 73,884 men and women in the United States, Great Britain and Norway. The study groups were identified in the early 1960's and included 30,033 British and Norwegian migrants to the United States and 43,851 non-migrants who resided in Great Britain and Norway. The main study objectives were to contrast the morbidity and mortality experience of the migrant and non-migrant groups in the light of known national differences in mortality from cardiorespiratory diseases in the early 1960's. At that time, the U.S. had the highest death rates from coronary heart disease while Great Britain had the highest rates for lung cancer and for chronic non-specific lung disease. Norway had the lowest rates for all three rubrics. The prevalence of "angina" and other symptoms was ascertained for each of the study groups. Contrary to expectation, angina was reported much more frequently by persons remaining in Britain and Norway than by migrants to the United States. Mortality rates during the five years and responding to the symptoms questionnaire were determined and mortality patterns were evaluated according to the presence or absence of angina. Angina was found to be a strong predictor of cardiovascular mortality. In the absence of angina, it was observed that migrants had similar mortality rates to non-migrants regardless of country of origin. However, the British had higher mortality rates from cardiovascular and from non-cardiovascular causes than the Norwegians. The primary determinant of angina prevalence was found to be migration status. It is believed that this differential was determined primarily by selection of those who migrate, with the migrants to the U.S. being a healthier group than their counterparts remaining in the native country.

Four cardiorespiratory symptoms as predictors of mortality

The power of four cardiorespiratory symptoms to predict subsequent mortality has been analysed in data derived from a random sample of the population of Great Britain recruited in 1965 and followed for 12.4 years. The associations of respiratory symptoms with all causes of death (except stroke) and of cardiovascular symptoms with death from coronary heart disease were strong. The trends of these two associations over the 12.4 years of the follow-up differed substantially: the relative death rates associated with respiratory symptoms remained throughout at about the same level, while those associated with cardiovascular symptoms declined after four years. The excess premature deaths associated with presence of one or more symptoms at entry represented about a quarter of the observed deaths of men and one tenth of those of women.

Radiotherapy of carcinomas of the extrahepatic biliary system

Carcinomas of the gallbladder and extrahepatic bile ducts carry a dismal prognosis. Due to the proximity of a number of vital structures and their early invasion, these tumors are rarely resectable. Long-term survival or cure is an exception. Results of treatment in 11 patients are reported. In 4 patients, radiotherapy was given as an adjuvant to surgery; in 5 patients the aim was palliation, while 2 patients received potentially curative doses of radiation. Good palliation has been achieved. Long-term, disease-free survival has been observed in some radically treated patients. The results suggest that radiotherapy may contribute to cure not only when used as a surgical adjuvant but also as the sole treatment modality in unresectable but still localized carcinomas of the bile ducts.

Radiation myelopathy of the thoracic spinal cord in long term survivors treated with radical radiotherapy using conventional fractionation

Previous reports on radiation myelopathy of the thoracic spinal cord have attempted to predict tolerance doses as a function of overall treatment time and number of fractions by extrapolation of data from collected myelopathy cases having markedly heterogeneous treatment parameters. A review of long term survivors receiving radical radiotherapy with conventional fractionation for lung and esophageal cancer was undertaken to determine if the proposed tolerance levels were consistent with clinical results in a series of patients constituting the group at risk for developing myelopathy. Spinal cord doses were determined in 58 patients who survived greater than or equal to 18 months following radiotherapy. All patients were treated with megavoltage equipment at dose rates of 200 rads/day continuously (53 patients) or 250 rads/day using split course (5 patients). Tumor doses ranged from 4500 rads to 7000 rads. Seventeen patients (29%) received less than 5000 rads to the thoracic cord, 6 patients (10%) received 5000 rads, and 35 patients (61%) received greater than 5000 rads. There were two patients who developed myelopathy. Review of our data, the clinical data of others and recent experimental results suggest that the slope of tolerance curves for thoracic spinal cord commonly utilized to express time-dose-fractionation relationships may be inappropriate. It is suggested that cord tolerance to well fractionated radiation has been previously underestimated.

In vitro retentive strength of fixed bridges constructed with acrylic pontics and an ultraviolet-light-polymerized resin

The in vitro retentive strength of 24 test bridges was studied. The bridges were maxillary canine to central incisor spans, and an acrylic pontic replaced the lateral incisors. The pontic was retained by a resin polymerized with ultraviolet light. The mean forces necessary to dislodge the pontic bonded to natural teeth in the three-unit bridges were determined to be 41.5 lb for a force applied toward the incisal edge and 55.8 lb for a force applied toward the gingival ridge. A promising clinical application of this technique is suggested.

Hospital admissions for peptic ulcer during 1958-72

Unpublished data from the Hospital In-patient Enquiry in England, Wales, and Scotland between 1958 and 1972 show that the frequency of admissions to hospital for peptic ulcer, particularly gastric ulcer, has fallen. This seems more likely to have been due to a true fall in the incidence of ulcer than to changes in treatment. Some three times as many people are admitted to hospital with duodenal ulcer in the north as in the south, but the frequency of admissions for gastric ulcer seems to vary little. The reasons for these differences are not understood.

Influenza and infant mortality

Early neonatal mortality in England and Wales in the second quarter of 1970 after a major influenza epidemic was slightly but significantly higher than in the corresponding quarter of the previous year. An increase was also noted in the first quarter of 1970. Analysis of infant mortality and an index of influenza prevalence over the past quarter-century indicates that similar increases occurred in relation to four of the other five major influenza epidemics during the period, the exception being the "Asian 'flu" epidemic of the autumn of 1957. It is suggested that the increased mortality in 1970 was the consequence of an increase in the prematurity rate, but we have no evidence to indicate whether the effect is specifically due to the virus or is nonspecific in nature.

Liaison of a county health department medical officer with a group of general practitioners in Hampshire

A pilot scheme was set up in Hampshire in January 1970, in which a local health authority doctor was "attached" to a group of general practitioners to carry out developmental assessment on infants and young children. Older pre-school children are also seen when necessary, and in all cases possible future educational requirements are considered. Such a scheme reduces duplication of work, increases mutual understanding between general practitioners and local health authority doctors, and helps to make full use of the limited resources of medical manpower.