Group 2 ITI Consensus Report: Technological developments in implant prosthetics.

OBJECTIVES: Group-2 reviewed the scientific evidence in the field of «Technology¼. Focused research questions were: (1) additive versus subtractive manufacturing of implant restorations; (2) survival, complications, and esthetics comparing prefabricated versus customized abutments; and (3) survival of posterior implant-supported multi-unit fixed dental prostheses. MATERIALS AND METHODS: Literature was systematically screened, and 67 publications could be critically reviewed following PRISMA guidelines, resulting in three systematic reviews. Consensus statements were presented to the plenary where after modification, those were accepted. RESULTS: Additively fabricated implant restorations of zirconia and polymers were investigated for marginal/internal adaptation and mechanical properties without clear results in favor of one technology or material. Titanium base abutments for screw-retained implant single crowns compared to customized abutments did not show significant differences concerning 1-year survival. PFM, veneered and monolithic zirconia implant-supported multi-unit posterior fixed dental prostheses demonstrated similar high 3-year survival rates, whereas veneered restorations exhibited the highest annual ceramic fracture and chipping rates. CONCLUSIONS: For interim tooth-colored implant single crowns both additive and subtractive manufacturing are viable techniques. The clinical performance of additively produced restorations remains to be investigated. Implant single crowns on titanium base abutments show similar clinical performance compared to other type of abutments; however, long-term clinical data from RCTs are needed. The abutment selection should be considered already during the planning phase. Digital planning facilitates 3D visualization of the prosthetic design including abutment selection. In the posterior area, monolithic zirconia is recommended as the material of choice for multi-unit implant restorations to reduce technical complications.

Noncatastrophic and catastrophic fractures in racing Thoroughbreds at the Hong Kong Jockey Club.

BACKGROUND: Reports of fractures in racehorses have predominantly focused on catastrophic injuries, and there are limited data identifying the location and incidence of fractures that did not result in a fatal outcome. OBJECTIVE: To describe the nature and the incidence of noncatastrophic and catastrophic fractures in Thoroughbreds racing at the Hong Kong Jockey Club (HKJC) over seven racing seasons. STUDY DESIGN: Retrospective cohort study. METHODS: Data of fractures sustained in horses while racing and of race characteristics were extracted from the HKJC Veterinary Management Information System (VMIS) and Racing Information System (RIS), respectively. The fracture event was determined from the first clinical entry for each specific injury. The incidence rates of noncatastrophic and catastrophic fractures were calculated per 1000 racing starts for racetrack, age, racing season, sex and trainer. RESULTS: One hundred and seventy-nine first fracture events occurred in 64,807 racing starts. The incidence rate of noncatastrophic fractures was 2.2 per 1000 racing starts and of catastrophic fractures was 0.6 per 1000 racing starts. Fractures of the proximal sesamoid bones represented 55% of all catastrophic fractures, while the most common noncatastrophic fractures involved the carpus and the first phalanx. Significant associations were detected between the incidence of noncatastrophic fractures and sex, trainer and racing season. MAIN LIMITATIONS: The first fracture event was used to calculate the incidence rate in this study and may have resulted in underestimation of the true incidence rate of fractures in this population. However, given the low number of recorded fracture events compared with the size of the study population, this underestimation is likely to be small. CONCLUSIONS: There were 3.6 times as many noncatastrophic fractures as catastrophic fractures in Thoroughbreds racing in Hong Kong between 2004 and 2011. Noncatastrophic fractures interfere with race training schedules and may predispose to catastrophic fracture. Future analytical studies on noncatastrophic racing fractures should be a priority for the racing industry.

Temperature-Dependent Kinetic Prediction for Reactions Described by Isothermal Mathematics.

Most kinetic models are expressed in isothermal mathematics. This may lead unaware scientists either to the misconception that classical isothermal kinetic models cannot be used for any chemical process in an environment with a time-dependent temperature profile or, even worse, to a misuse of them. In reality, classical isothermal models can be employed to make kinetic predictions for reactions in environments with time-dependent temperature profiles, provided that there is a continuity/conservation in the reaction extent at every temperature-time step. In this article, fundamental analyses, illustrations, guiding tables, and examples are given to help the interested readers using either conventional isothermal reacted fraction curves or rate equations to make proper kinetic predictions for chemical reactions in environments with temperature profiles that vary, even arbitrarily, with time simply by the requirement of continuity/conservation of reaction extent whenever there is an external temperature change.

Impact of Patient Compliance on Tooth Loss during Supportive Periodontal Therapy: A Systematic Review and Meta-analysis.

Periodontal treatment consists of active periodontal therapy (APT) and supportive periodontal therapy (SPT). Regular SPT is recommended to prevent and control the occurrence of periodontal disease following APT. A patient's compliance with SPT is considered one of the most important factors affecting long-term periodontal status. Tooth loss is generally considered the final outcome of periodontitis. This review aimed to analyze the relationship between patient compliance with regular SPT and tooth loss. The PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analyses) guideline for systematic reviews was used. A search of articles was conducted using MEDLINE (PubMed) and other databases. Quality assessments of selected studies were performed. To assess the effect of compliance on tooth loss during SPT, pooled risk ratio of tooth loss (RRTL) was used as the primary outcome. Pooled risk difference of tooth loss (RDTL) and weighted mean difference of tooth loss rate (WDTLR) were used as secondary outcomes. Subgroup analysis and meta-regression were conducted to evaluate the effects of different variables. In total, 710 articles were screened. Eight studies, which had a regular-compliance (RC) group and an erratic-compliance (EC) group with at least a 5-y follow-up period, qualified for the meta-analysis. The risk of tooth loss in the RC group was significantly lower than that in the EC group (pooled RRTL: 0.56 [confidence interval (CI): 0.38, 0.82]; pooled RDTL: -0.05 [CI: -0.08, -0.01]). The definition of compliance was a variable significantly related to risk ratio of tooth loss. Patients in the RC group had significantly lower tooth loss rate during SPT than did patients in the EC group (WDTLR: -0.12 [CI: -0.19, -0.05]). Teeth have less risk of being lost if patients are more compliant with supportive periodontal therapy. However, unidentified variables causing data heterogeneity and affecting the risk of tooth loss may have been present. More well-controlled prospective studies are needed in the future.

Color and organic compounds removal from secondary effluent of landfill leachate with a novel inorganic polymer coagulant.

Emerging contaminants in landfill leachate are causing environmental concerns due to their adverse impacts on the aquatic environment. The most popular biological process is mostly the first stage in combination with additional physical-chemical process. Current post-treatments are limited by high operating costs, low treatment efficiencies, or sensitive operating conditions. Poly-aluminium(III)-magnesium(II)-sulfate (PMAS in brief) is used to remove color and organic compounds in secondary effluent of landfill leachate. More than 40 kinds of organic matters in the secondary effluent are identified and 10 of them belong to the Black List of environmental preferred controlled pollutants considered by EPA of USA or China. Removals of COD, BOD(5), UV(254) and color by coagulation with PAMS can reach above 60%, 55%, 85% and 85% respectively under the optimum conditions. The species of alkyl, alkene, acyclic alcohol and acyclic acyl amine are efficiently removed (about 85%), with some of them removed completely, while the species of acid, ester and ketone are mostly removed (about 65%) and such matters with benzene ring as aromatic hydrocarbon, hydroxybenzene, aromatic alcohol, aromatic acyl amine are partially removed (about 50%). Organic pollutants in the secondary effluent are greatly removed with high efficiency here, which greatly weakens its pollution extent.

High frequency components of bone strain in dogs measured during various activities.

Rubin et al. [J. Biomechanics 23, 43-54 (1990)] proposed that high frequency bone strains in the 15-30 Hz range might have significant influence on the morphological adaptation of bone tissue. We sought to further their findings by determining the magnitude of high frequency strains during various activities. We measured strains in the forelimbs of dogs during walking, standing and with their limbs unweighted. As negative controls, we measured strains while the dogs were tranquilized and after sacrifice. Strains in the 15-30 Hz range were not significantly greater than controls for any activity except walking, in which they were less than 4% as large as in the 0-15 Hz range. The high frequency strains observed during walking seemed to occur prior to footfall, suggesting that they were not the result of foot strike. The biological significance of high frequency bone strains has yet to be determined, but may be less than originally proposed because of the relatively small magnitude of these strains.

The effects of muscle fatigue on bone strain.

There is anecdotal evidence that bone strains may increase to the point that bone becomes susceptible to rapid failure when muscles become fatigued. To determine whether neuromuscular response could be a factor in accelerating bone failure, we tested the hypothesis that muscle fatigue causes a significant increase in peak principal and shear strains in bone. Ten adult foxhounds were subjected to rigorous exercise that caused muscular fatigue while myoelectrical activity of the quadriceps and hamstrings and strain on the distal tibia were monitored simultaneously. Ground reaction forces on the dog hindlimbs were measured before and after strain gauges had been applied to the tibia. The data show a significant shift to lower median myoelectrical frequencies in the quadriceps, indicating muscular fatigue, following the 20 min exercise period. In conjunction with this shift, peak principal and shear strains increased on both compressive and tensile cortices of the tibia and shear strain on the tensile cortex increased significantly (P = 0.02). The largest changes were along the anterior and anterolateral surfaces of the tibia, where peak principal strain increased by an average of 26-35% following muscular fatigue. The cross-sectional strain distribution was calculated at the gauge site at peak strain at the beginning of the exercise period and at peak strain after 20 min of exercise. These data show a change in strain distribution when muscle becomes fatigued. Strains on the posterior cortex of the bone showed the greatest change. Correlation analysis demonstrated a significant inverse association between median myoelectrical frequency and bone strain after 20 min of exercise (Spearman r2 = 1.00; P = 0.05). These data show that muscle fatigue may be associated with increased bone strain.

Histomorphometric assessment of the mechanisms for rapid ingrowth of bone to HA/TCP coated implants.

The purpose of this work is to use dynamic histomorphometry to evaluate the basic biological mechanisms by which hydroxyapatite/tricalcium phosphate (HA/TCP) implant coatings accelerate bone formation rates. Twenty-five rabbits had an HA/TCP coated cylindrical titanium fiber metal mesh implant surgically placed in the subchondral bone of the proximal tibia and a noncoated implant placed in the contralateral tibia. Twenty-two of these animals had HA/TCP coated cylindrical solid titanium implants placed in the distal femur and an uncoated implant placed in the contralateral femur. The animals were double labeled with vital stains, and sacrificed at 3, 6, 16, or 26 weeks after surgery. Histomorphometric analyses were done of the bone implant interfaces. Both static and dynamic histomorphometric parameters indicate that HA/TCP coatings stimulate faster bone ingrowth to coated fiber metal implants through the early production of woven bone and by subsequent rapid lamellar bone formation rates. Coated fiber metal implants demonstrated significantly more bone ingrowth than noncoated implants through 16 weeks postimplantation, but not by 26 weeks. In solid implants, the differences between coated and noncoated implants are less pronounced and not statistically significant, although there is a trend toward increased bone apposition to the surface of the implants over the first 16 weeks following implantation. The clinical significance of these results is that coated implants may allow earlier return to normal weightbearing.

Do different fluorochrome labels give equivalent histomorphometric information?

Substances that bind calcium are given to determine where and how fast bone is forming. Several vital dyes are used (tetracycline, calcein, alizarin, xylenol), but it is not known whether the histomorphometric results they provide are equivalent. This work tests whether different fluorochrome labels give the same results when they are quantitatively measured. Twelve-week-old rats (n = 58) were divided into six groups and given double labels IP of calcein, tetracycline HCl, alizarin complexone, or xylenol using a 1-7-1 scheme. Two other groups received either calcein followed by tetracycline, or tetracycline followed by calcein. Our results show that (a) tetracycline hydrochloride leads to a significant underestimation of mineralizing surface when given as the second label, probably because of its weak fluorescence; (b) there were no differences among any of the non-tetracycline labels for any of the histomorphometric measurements; (c) there was no evidence of osteoblast suppression with any label; and (d) there was no evidence that tetracycline caused increased osteoblast resting periods.

Chondrosarcoma in Maffucci's syndrome.

Nine patients with Maffucci's syndrome were seen at our institution; chondrosarcoma developed in five. On the basis of the cases of these patients and those reported in the English literature since 1973, we determined that the incidence of chondrosarcoma in patients with Maffucci's syndrome is 17.8 per cent.