bluuebunny/crossref_metadata_2025 huggingface dataset:
Learning when school is not in session: a reading summer day‐camp intervention to improve the achievement of exiting First‐Grade students who are economically disadvantaged
Authors: Schacter John , Jo Booil
Published: May 2005

During the summer vacation children who are economically disadvantaged experience declines in reading achievement, while middle‐ and high‐income children improve. Previous research has demonstrated that the most widely implemented intervention – sending economically disadvantaged students to summer school – has not led to increases in reading achievement. In this longitudinal randomised trial, a randomly assigned group of exiting First‐Grade children who were economically disadvantaged was enrolled in a seven‐week summer reading day camp. The intervention students' reading achievement was then compared to control group participants at four time points. Results showed noteworthy differences for intervention students in reading comprehension.
Solving the Problems of Economic Development Incentives
Authors: BARTIK TIMOTHY J.
Published: May 2005

ABSTRACT  This paper reviews the research literature relevant to economic development incentives provided by state and local governments, and recommends reforms in these incentives. I argue that the main problem with current incentive policies is that state and local governments often provide incentives that are not in the best interest of that state or local area, for example that are excessively costly per job created, or that provide jobs that do not improve the job opportunities of local residents. I suggest that reforms should be “bottom‐up” rather than “top‐down.” Regulation of incentives by the federal government may prevent both desirable and undesirable incentives. “Bottom‐up” reforms would include more information on incentive offers, a budget constraint on the volume of incentives, stronger standards for job quality and job accessibility for the local unemployed, and better benefit‐cost analyses of incentives.
Renewing Canada's Manufacturing Economy: A Regional Comparison, 1973‐1996
Authors: BROWN MARK
Published: May 2005

ABSTRACT  Regional economies are continually undergoing adjustment as their firm populations react to changing tastes, technologies, and the challenges of outside competition. Adjustment typically takes place as the stock of jobs is renewed in each industry. This micro‐dynamic process of renewal has a substantial impact on the structure of national and regional economies. The primary objective of this paper is to measure the degree of renewal within the Canadian manufacturing economy as whole and within individual provinces. Using a longitudinal micro‐data set—which covers the population of manufacturing plants in Canada from 1973 to 1996—the study shows that the manufacturing sector experienced considerable job renewal. Two‐thirds of jobs in 1996 were newly created since 1973. There was considerable variation in provincial renewal rates. A decomposition analysis suggests this variation is not purely an artifact of the types of industries found in provinces, but reflects other characteristics of provincial economies.
Regional Development and Land Use Change in the Rocky Mountain West, 1982‐1997
Authors: VIAS ALEXANDER C. , CARRUTHERS JOHN I.
Published: May 2005

ABSTRACT  Economic and demographic restructuring, along with the increasing desirability of environmental amenities, have driven growth in the eight‐state region of the Rocky Mountain West to extraordinary levels in recent decades. While social scientists have developed a solid conceptual understanding of the processes driving growth and change in the region, the broad nature of the land use outcomes associated with in‐migration has not received nearly as much scholarly attention. This article initiates an in‐depth empirical investigation on the magnitude, nature, and spatial variation of land use change in the Rocky Mountain West over the 1982‐1997 time period. Data from the USDA's National Resources Inventory reveals that the conversion of landscapes from rural to urban types of land uses varies significantly from place to place, not only in terms of total land developed, but also with respect to how population pressures and a number of other local characteristics of counties manifest themselves in the spatial pattern of growth.
Genetic and environmental influences on conduct disorder: symptom, domain and full‐scale analyses
Authors: Gelhorn Heather L. , Stallings Michael C. , Young Susan E. , Corley Robin P. , Rhee Soo Hyun , Hewitt John K.
Published: May 2005

Background: We used variable threshold models which accounted for age and gender differences to investigate the genetic and environmental influences on DSM‐IV conduct disorder (CD) at the level of symptoms, aggressive versus non‐aggressive domains, and full‐scale.

Method: A community sample of 1100 twin pairs (age 11–18) was interviewed using the Diagnostic Interview Schedule for Children.

Results: Behavior genetic model fitting suggested that genetic and environmental influences on individual symptoms varied by symptom. The best‐fitting models for aggressive and non‐aggressive domains, and full‐scale CD included additive genetic effects and unique environmental effects only (AE models). These effects could be constrained across age cohorts and sex. The results suggest that using models that incorporate age‐ and gender‐appropriate thresholds specific to each subject we can account for prevalence differences between cohorts. Heritability estimates were .49, .55 and .53 for the aggressive domain, non‐aggressive domain, and full‐scales, respectively. These results are in contrast to previous research on antisocial behavior measured with the CBCL reporting higher heritability for aggressive versus non‐aggressive domains.

Conclusions: Results suggest that individual symptoms of CD may be differentially heritable. Additionally, CD assessed using DSM‐IV criteria may show differing patterns of heritability compared with estimates obtained for other measures of antisocial behavior such as the CBCL.
The genetic‐environmental etiology of parents' perceptions and self‐assessed behaviours toward their 5‐month‐old infants in a large twin and singleton sample
Authors: Boivin Michel , Pérusse Daniel , Dionne Ginette , Saysset Valérie , Zoccolillo Mark , Tarabulsy George M. , Tremblay Nathalie , Tremblay Richard E.
Published: May 2005

Background: Given the importance of parenting for the child's early socio‐emotional development, parenting perceptions and behaviours, and their correlates, should be assessed as early as possible in the child's life. The goals of the present study were 1) to confirm, in two parallel population‐based samples, including a large sample of twins, the factor structure of a new self‐administered questionnaire assessing both parents’ specific parenting perceptions and behaviours toward their 5‐month‐old infants (i.e., parental self‐efficacy, perceived parental impact, parental hostile‐reactive behaviours and parental overprotection), 2) to identify the specific risk factors associated with the negative side of these parenting dimensions, 3) to document the genetic‐environmental etiology of these parenting dimensions through the twin method.

Methods: Parents (2,122 mothers and 1,829 fathers) of 5‐month‐old infants, and parents of 5‐month‐old infant twins (510 families) completed the questionnaire (28 items). The data were submitted to a series of confirmatory factor analyses. The contribution to parenting of a variety of risk factors was examined in the two samples using regression analyses. A series of quantitative genetic analyses were performed to quantify the different sources of variation in parenting.

Results: A consistent factor structure was found across informants and across samples. There were significant mean differences in parenting between mothers and fathers, as well as between parents of twins and parents of singletons. A differentiated pattern of association with risk factors was found for each dimension of parenting. The twin analyses revealed that shared environment accounted for each parenting dimension. Maternal hostile‐reactive behaviours were also moderately related to genetic factors in the child and this association was mainly mediated by the infant difficultness.

Conclusions: The overall pattern of results was consistent withBelsky's (1984)view of parenting as multiply determined. The longitudinal follow‐up of these families should provide the means for testing developmental models about the determinants and outcomes of these parenting dimensions.
Developmental consequences of poor phonological short‐term memory function in childhood: a longitudinal study
Authors: Gathercole Susan E. , Tiffany Claire , Briscoe Josie , Thorn Annabel ,   The ALSPAC team
Published: May 2005

Background:  A longitudinal study investigated the cognitive skills and scholastic attainments at 8 years of age of children selected on the basis of poor phonological loop skills at 5 years.

Methods:  Children with low and average performance at 5 years were tested three years later on measures of working memory, phonological awareness, vocabulary, language, reading, and number skill.

Results:  Two subgroups of children with poor early performance on phonological memory tests were identified. In one subgroup, the poor phonological memory skills persisted at 8 years. These children performed at comparable levels to the control group on measures of vocabulary, language and mathematics. They scored more poorly on literacy assessments, but this deficit was associated with group differences in complex memory span and phonological awareness performance. The second subgroup of children performed more highly on phonological memory tests at 8 years, but had enduring deficits in language assessments from 4 to 8 years.

Conclusions:  Persistently poor phonological memory skills do not appear to significantly constrain the acquisition of language, mathematics or number skills over the early school years. More general working memory skills do, however, appear to be crucial.
The sinus lift with phycogenic bone substitute
Authors: Simunek Antonin , Cierny Michal , Kopecka Dana , Kohout Ales , Bukac Josef , Vahalova Dagmar
Published: May 2005

Objectives: The aim of this histomorphometric prospective study was to ascertain the efficacy of phycogenic bone substitute in an augmented sinus. The process of graft healing, bone remodeling, and biomaterial replacement was examined.

Material and methods: The phycogenic material (fluorohydroxyapatite) made from calcium‐encrusted sea algae was used for the sinus lifts. Twenty‐four procedures were carried out (one‐stage and two‐stage equally) and 45 titanium stepped‐screw implants were placed. The patients were followed for 12–23 months. In intervals of 6, 9, 12, or 15 months after the sinus lift, 24 graft specimens were taken with a trephine bur. These specimens were examined histomorphometrically.

Results: The grafting material was gradually resorbed and replaced by newly formed bone. Between the sixth and 15th month after the sinus lift, the percentage of newly formed bone grew linearly (from 15.5±9.6% to 40.8±15.3%) and the percentage of bone substitute decreased linearly (from 34.5±8.6% to 13±9.6%). After 15 months, the density of trabeculae in grafted bone corresponded to cancellous bone of good quality; however, the bone substitute was not completely resorbed during this period. No significant difference between the quality of the newly formed bone in the cases of the one‐ and two‐stage sinus lifts was found.

Conclusion: Sinus lift carried out with phycogenic bone substitute was shown to be an effective method with limited invasiveness and a high survival rate of implants (97.8%).
Oxidized titanium implants (Nobel Biocare® TiUnite™) compared with turned titanium implants (Nobel Biocare® mark III™) with respect to implant failure in a group of consecutive patients treated with early functional loading and two‐stage protocol
Authors: Jungner Måns , Lundqvist Peter , Lundgren Stefan
Published: May 2005

Objectives: The purpose of this study was to compare two implant types of similar shape but with different surfaces with respect to implant failure.

Material and methods: A total of 136 patients were treated with Nobel Biocare® Implants between January 2001 and December 2002. Totally 394 implants were placed, of which 199 were oxidized titanium implants (Nobel Biocare® TiUnite™) and 195 with turned titanium surface (Nobel Biocare® Mark III™). Sixty‐three patients underwent a one‐stage surgical protocol, of which 24 were objected to early functional loading. The remaining 73 patients were treated with a traditional two‐stage surgical protocol. All patients were followed for a minimum of 5 months after loading of the implants. Implants were classified as survivals when clinically stable and fulfilling purported function without any discomfort to the patient, with no signs of infection or ongoing pathologic process.

Results: Seven implants were lost in five patients (two males and three females), six in the maxilla and one in the mandible. All failed implants were Mark III implants, inserted following the traditional two‐stage protocol. The implant success rate was 98.2% for the whole‐patient group, divided as a 100% success rate following the implants with oxidized surface (Nobel Biocare® TiUnite™) compared with a success rate of 96.4% with implants with turned surface (Nobel Biocare® Mark III™).
Technical and biological complications/failures with single crowns and fixed partial dentures on implants: a 10‐year prospective cohort study
Authors: Brägger Urs , Karoussis Ioannis , Persson Rutger , Pjetursson Bjarni , Salvi Giovanni , Lang Niklaus P.
Published: May 2005

Objectives: To assess prospectively over 10 years the incidences of technical and/or biological complications and failures occurring in a cohort of consecutive partially edentulous patients with fixed reconstructions on implants of the ITI® Dental Implant System.

Methods: Eighty‐nine patients were available, 34 (38.2%) were male, 55 (61.8%) were female. At the 10‐year examination (range 8–12 years), they were 58.9 years old (range 28–88 years).

Results: Single crowns (SC): 48 patients had been restored with 69 SC on 69 implants. Five of the implants with the crowns were lost because of biological failures. Two crowns (2.9%) were remade because of technical failures. Total failure amounted to seven (10%). Implant borne fixed partial dentures (I‐I FPD): In 29 patients who had been restored with 33 implant borne suprastructures, the total number of failed I‐I FPD was 2 (6.1%). Tooth–implant borne fixed partial dentures (I‐T FPD): In 21 patients, 22 mixed tooth–implant borne reconstructions were constructed. The number of failed FPD reached 7 (31.8%). Statistically significantly fewer biological failures occurred with I‐I FPD compared with the I‐T FPDs (ANOVA, Bonferroni, P=0.022). The I‐T FPDs experienced statistically significantly more frequent technical failures compared with the other two groups of suprastructures (P=0.003, 0.031). Consequences of complications: The occurrence of loss of retention as a complication increased the odds ratio (OR) to 17.6 (P<0.001) to end up in a technical failure. Similarly, the event of a porcelain fracture increased the OR for the suprastructure to be a failure at 10 years to 11.0 (P≤0.004). Treatment of periimplantitis increased the OR to 5.44 (P≤0.011) to result in a biological failure compared with implants in which this type of treatment was not applied.

Conclusion: The three groups of suprastructures demonstrated marked differences in their patterns of failures and complications. Complications increased the risk for failure. Support by CRF, University of Berne, Switzerland.
Biodegradation of differently cross‐linked collagen membranes: an experimental study in the rat
Authors: Rothamel Daniel , Schwarz Frank , Sager Martin , Herten Monika , Sculean Anton , Becker Jürgen
Published: May 2005

Abstract: The aim of the present study was to compare the biodegradation of differently cross‐linked collagen membranes in rats. Five commercially available and three experimental membranes (VN) were included: (1) BioGide® (BG) (non‐cross‐linked porcine type I and III collagens), (2) BioMend® (BM), (3) BioMendExtend® (BME) (glutaraldehyde cross‐linked bovine type I collagen), (4) Ossix® (OS) (enzymatic‐cross‐linked bovine type I collagen), (5) TutoDent® (TD) (non‐cross‐linked bovine type I collagen, and (6–8) VN(1–3) (chemical cross‐linked porcine type I and III collagens). Specimens were randomly allocated in unconnected subcutaneous pouches separated surgically on the back of 40 wistar rats, which were divided into five groups (2, 4, 8, 16, and 24 weeks), including eight animals each. After 2, 4, 8, 16, and 24 weeks of healing, the rats were sacrificed and explanted specimens were prepared for histologic and histometric analysis. The following parameters were evaluated: biodegradation over time, vascularization, tissue integration, and foreign body reaction. Highest vascularization and tissue integration was noted for BG followed by BM, BME, and VN(1); TD, VN(2), and VN(3) showed prolongated, while OS exhibited no vascularization. Subsequently, biodegradation of BG, BM, BME and VN(1) was faster than TD, VN(2), and VN(3). OS showed only a minute amount of superficial biodegradation 24 weeks following implantation. Biodegradation of TD, BM, BME, VN(2), and VN(3) was associated with the presence of inflammatory cells. Within the limits of the present study, it was concluded that cross‐linking of bovine and porcine‐derived collagen types I and III was associated with (i) prolonged biodegradation, (ii) decreased tissue integration and vascularization, and (iii) in case of TD, BM, BME, VN(2), and VN(3) foreign body reactions.
A prospective 3‐year study of fixed bridges linking Astra Tech ST implants to natural teeth
Authors: Palmer R. M. , Howe L. C. , Palmer P. J.
Published: May 2005

Background: Connecting teeth and osseointegrated implants in fixed reconstructions is not generally recommended because of differences in their response to loading.

Aim: The aim of the present study was to assess the clinical and radiographic performance of the teeth and implants used to support three unit fixed bridges subjected to normal functional loads.

Subjects and methods: Nineteen subjects (10 males, nine females, age range 27–65 years) with an edentulous posterior free end saddle in either maxilla or mandible (Kennedy Class 2), and opposing natural teeth or a tooth‐supported fixed bridge were treated and completed the 3‐year trial. An Astra Tech ST implant (length: 9 mm (n=2), 11 mm (n=9) or 13 mm (n=8); diameter: 4.5 mm) was placed immediately distal to the last tooth or leaving a single premolar sized space. The distal tooth received a gold coping and the implant was restored with a customised Prepable abutment (Astra Tech Profile BiAbutment: diameter 5.5 or 7 mm). A fixed bridge was placed linking the gold coping and implant abutment either with the pontic as a distal cantilever (n=6, length 7–8 mm) or as a fixed–fixed design (n=13, length 6–12 mm). Standardised radiographs and clinical records were taken at delivery of the prosthesis (baseline BL) and annually.

Results: Plaque scores at implant sites increased between BL and subsequent years (P<0.02). Statistically significant increases in probing depth were observed at both abutment teeth and implants between baseline and subsequent years (P<0.001). Marginal bone levels (mm) at the implant and tooth were stable between BL, 1‐, 2‐ and 3‐year examinations (implant: BL 0.65±0.42, 1 year 0.63±0.47, 2 years 0.88±0.55, 3 years 0.78±0.64; tooth: BL 2.29±0.82, 1 year 2.41±0.8, 2 years 2.38±1.02, 3 years 2.68±0.86). No signs of the intrusion of the abutment teeth were detected. One case of abutment screw loosening occurred. Eight bridges required re‐cementation with a permanent cement in place of the temporary cement. There were eight subjects presenting with fractures/chips to the composite component of the bridges.

Conclusion: The 3‐year results demonstrate fully functional successful restorations with no evidence of tooth intrusion and with stable bone levels at both teeth and implants.
Economic aspects of single‐tooth replacement
Authors: Brägger Urs , Krenander Paul , Lang Niklaus P.
Published: May 2005

Abstract: The aim of this study was to assess and compare economic parameters of two treatment options in patients requiring single‐tooth replacements in private practice. Thirty‐seven patients received 41 conventional three‐unit fixed partial dentures (FPDs). Fifty‐two patients received 59 single crowns on implants (I). Treatment assignment was not random. All except one were metal ceramic reconstructions. All except one were crowns cemented on solid abutments of the ITI® Dental Implant System. Economic parameters were noted for the preparatory phase, the actual reconstruction and for treatment of biological and/or technical complication thereafter (range 1–4 years): number of visits, chair‐side time, treatment costs, costs for implant components and laboratory work. Costs were based on the tariffs between the Swiss dentists association and the insurers (Sfr 3.1 per tariff point). Implant treatment required more visits than FPD (8.1±2/4.8±2.3, χ2: P=0.02). However, the total treatment time was similar (I: 4.8 h±0.9 h/FGM: 5.1 h±1.3 h, NS). Laboratory costs were higher for FPD (1527.8±209 SFr) vs. 579.6±106.9 CHF for I. Costs for treatment of technical and biological complications were similar. Total costs amounted to 3939.4±766.4 SFr for FGM vs. 3218±512.2 SFr for I (P<0.003, Kolmogorov–Smirnov). Even when considering opportunity costs (50 SFr) for each visit the implant solution was less expensive: 3623.2±656.1 SFr vs. 4178.7±822.1 SFr (P<0.04, Kolmogorov–Smirnov). Costs for treatment of complications were similar. In conclusion, over a short observation period, the implant reconstruction demonstrated a more favorable cost/effectiveness ratio. Especially in clinical situations with either non‐ or minimally restored teeth and sufficient bone, the implant reconstruction is to be recommended from an economical point of view.
Does platelet‐rich plasma promote remodeling of autologous bone grafts used for augmentation of the maxillary sinus floor?
Authors: Raghoebar Gerry M. , Schortinghuis Jurjen , Liem Robert S. B. , Ruben Jan L. , Van Der Wal Jacqueline E. , Vissink Arjan
Published: May 2005

Abstract: The aim of this study was to evaluate the effect of platelet‐rich plasma (PRP) on remodeling of autologous bone grafts used for augmentation of the floor of the maxillary sinus. In five edentulous patients suffering from insufficient retention of their upper denture related to a severely resorbed maxilla, the floor of both maxillary sinus was augmented with an autologous bone graft from the iliac crest. Randomly, PRP was added to the bone graft used to augment the floor of the left or right sinus (split‐mouth design). Three months after the reconstruction, bone biopsies were taken with a trephine from the planned implant sites (N=30). Subsequently, three implants were placed in the left and right posterior maxilla. Microradiograms were made of all biopsies (N=30), whereafter the biopsies were processed for light microscopic examination. In addition, clinical parameters were scored. Wound healing was uneventful, clinically no difference was observed between the side treated with PRP or not. Also microradiographical and histomorphological examination of the biopsies revealed no statistical difference between the PRP‐ and non‐PRP side. One implant placed in the PRP side of the graft was lost during the healing phase. Implant‐retained overdentures were fabricated 6 months after implantation. All patients functioned well (follow‐up 20.2±4.3 months). In this study, no beneficial effect of PRP on wound healing and bone remodeling was observed. It is posed that PRP has no additional value in promoting healing of grafted non‐critical size defects.
The impact of nicotine on bone healing and osseointegration
Authors: Balatsouka Dimitra , Gotfredsen Klaus , Lindh Christian H. , Berglundh Tord
Published: May 2005

Abstract
Objectives: To examine the short‐term effect of nicotine on bone healing and osseointegration.

Material and methods: Sixteen female rabbits were divided into two groups. The test group was exposed to nicotine tartrate for 8 weeks and the control group was exposed to placebo. Nicotine or placebo was administered via a miniosmotic pump and plasma cotinine levels were measured weekly. The pump delivered 15 mg of nicotine/day for the animals in the test group. All rabbits had three tibial bone preparations. In the proximal and distal bone bed, implants were placed after 4 weeks (right tibia) and after 6 weeks (left tibia). Thus, 2‐ and 4‐week healing groups were created. Removal torque test (RMT) was performed at the distal implants. Ground sections were made from the proximal and the central bone beds. The fraction of mineralized bone in contact to the implant (BIC) and the bone density within the implant threads (BD‐i) were determined for the bone–implant specimens. For the central bone beds without implants the bone density (BD‐c) in the bone defects was determined.

Results: No significant difference in RMT values was found between the test and the control group. Histomorphometric measurements of the BIC and the peri‐implant BD‐i showed no significant differences between the test and the control group after 2 or 4 weeks. Significant differences were, however, found between the 2‐ and 4‐week samples. In the central bone beds, there was no significant difference in BD‐c between the test and the control group.

Conclusion: Nicotine exposure in a short period of time did not have a significant impact on bone healing or implant osseointegration in rabbits.
New formation of periodontal tissues around titanium implants in a novel dentin chamber model
Authors: Parlar Ates , Bosshardt Dieter D. , Ünsal Berrin , Çetiner Deniz , Haytaç Cenk , Lang Niklaus P.
Published: May 2005

Abstract: Direct bone‐to‐implant contact, defined as ‘osseointegration’, is considered most optimal for long‐term stability and survival of dental implants. However, the possibility of the formation of a tooth‐like attachment apparatus around implants has also been demonstrated. The purpose of this study was to explore the formation of periodontal tissues around titanium implants using a novel and unique experimental model. After resection of the crowns of the maxillary canine teeth in nine mongrel dogs, the roots were hollowed to a depth of 5 mm leaving a thin dentinal wall. Slits were prepared in the cavity wall to create passages from the chamber to the periodontal ligament area. A custom‐made, titanium implant was placed into the center of each chamber. Machined, titanium plasma sprayed (TPS) and sand blasted with large grit and acid attacked (SLA) surfaces were used. A collagen barrier was placed over the submerged chamber. Following 4 months of healing, jaw sections were processed for histology. Newly formed periodontal ligament, alveolar bone, and root cementum filled the space between the implant and the wall of the chamber. Ingrown bone was neither in contact with dentin nor with the implant. Thus, an interposed soft connective tissue layer was present. Healing by fibrous encapsulation was observed around most implants. However, cellular cementum was deposited on one TPS and one SLA implant and on the dentinal walls of the chamber. This study shows a remarkable capacity for new periodontal tissue formation at a site where no such tissues ever existed. Maintenance of original periodontal tissue domains most likely prevented osseointegration of the implants. The cementum layer deposited on two implants was likely formed through cementoconductivity rather than by differentiation of periodontal ligament cells upon contact with the implant surface.
Oro‐facial injuries in Central American and Caribbean sports games: a 20‐year experience
Authors: Amy Enrique
Published: May 2005

Abstract –  Dental services in sports competitions in the Games sponsored by the International Olympic Committee are mandatory. In every Central American, Pan American and Olympic Summer Games, as well as Winter Games, the Organizing Committee has to take all the necessary measures to assure dental services to all competitors. In all Olympic villages, as part of the medical services, a dental clinic is set up to treat any dental emergency that may arise during the Games. Almost every participating country in the Games has its own medical team and some may include a dentist. The major responsibilities of the team dentist as a member of the national sports delegation include: (i) education of the sports delegation about different oral and dental diseases and the illustration of possible problems that athletes or other personnel may encounter during the Games, (ii) adequate training and management of orofacial trauma during the competition, (iii) knowledge about the rules and regulations of the specific sport that the dentist is working, (iv) understanding of the anti‐doping control regulations and procedures, (v) necessary skills to fabricate a custom‐made and properly fitted mouthguard to all participants in contact or collision sports of the delegation. This study illustrates the dental services and occurrence of orofacial injury at the Central American and Caribbean Sports Games of the Puerto Rican Delegation for the past 20 years. A total of 2107 participants made up the six different delegations at these Games. Of these 279 or 13.2% were seen for different dental conditions. The incidence of acute or emergency orofacial conditions was 18 cases or 6% of the total participants. The most frequent injury was lip contusion with four cases and the sport that experienced more injuries was basketball with three cases.
Evaluation of intruded primary incisors
Authors: Gondim Juliana Oliveira , Moreira Neto José Jeová Siebra
Published: May 2005

Abstract –  Tooth intrusion consists of the displacement of the tooth into its alveolus and is the most common trauma during early infancy. This work aims to evaluate the aspects related to tooth intrusion in primary teeth by monitoring 16 patients (22 teeth) for a period between 3 and 36 months. Of the patients who suffered from tooth intrusion, 56.25% were male and 91% of the intruding teeth were upper central incisors. In all cases the treatment indicated was to await spontaneous re‐eruption: total re‐eruption occurred in 42.5% of cases, partial re‐eruption in 47% of cases and in 10.5% there was no re‐eruption. Twenty‐three percentage of the teeth suffered necrosis, 33% suffered internal or external root resorption and none suffered root canal obliteration. Fifty‐seven percentage indicated healthy pulps independent of degree of re‐eruption.
Orthodontic extrusion of subgingivally fractured incisor before restoration. A case report: 3‐years follow‐up
Authors: Koyuturk Alp Erdin , Malkoc Sıddık
Published: May 2005

Abstract –  Orthodontic forced eruption may be a suitable approach without risking the esthetic appearance in tooth fracture below the gingival attachment or alveolar bone crest. Extrusion of such teeth allows elevating the fracture line above the epithelial attachment and so the proper finishing margins can be prepared. Restoration after orthodontic eruption may present a more conservative treatment choice in young patients compared with the prosthetic restoration after extraction. This case describes a multidisciplinary approach using the orthodontic forced eruption facilitating the composite restoration of a fractured upper permanent central incisor.
An alternative method for fabricating a custom‐made metal post with a ceramic core
Authors: Deger Sabire , Akgüngör Gökhan , Caniklioglu Babür
Published: May 2005

Abstract –  The restoration of anterior non‐vital teeth with metal posts and cores and all‐ceramic restorations may lead to compromised esthetics because of the semitranslucence of ceramics and the metallic color of the underlying post and cores. This article presents a technique that combines the optical properties of ceramic cores with the mechanical properties of custom‐made cast metal posts. The technique involves heat pressing of the core from leucite‐enriched glass‐ceramic to the underlying custom‐made metal post and may provide additional esthetic benefit for anterior teeth especially with little remaining coronal dentin and with small root volume.
Dentinal pH changes following electrophoretically activated calcium hydroxide ions in the root canal space of bovine teeth
Authors: Tsesis Igor , Lin Shaul , Weiss Ervin I. , Fuss Zvi
Published: May 2005

Abstract –  The aim of the study was to evaluate pH changes of external root dentin surface at different depths following electrophoretic activation of calcium hydroxide (CH) in the root canals. For the study, 60 cavities were drilled on three external root surfaces of 20 bovine teeth specimens to obtain remaining dentin thickness (RDT) of 0.3, 0.7 and 1.0 mm. CH paste was inserted in the lumens. In the experimental group (10 specimens) CH paste was electrophoretically activated. Microelectrode was used to measure pH changes in the cavities immediately after placement of CH, following electrophoretical activation, and after 30 days storage. A significant (P < 0.05) increase in pH following electrophoresis was found in all specimens in the experimental group. Cavities with 0.4 mm RDT showed a maximal pH increase to the value of 11.3 ± 0.4. In the control group no change in pH was observed after 3 min. A similar increase in pH was observed in both groups after 30 days. The pH changes were significantly depended on the RDT (P < 0.05) in all groups. Electrophoretically activated CH could significantly increase dentinal pH of external root surface within minutes up to 30 days.
A comparative study of white and grey mineral trioxide aggregate as pulp capping agents in dog's teeth
Authors: Parirokh Masoud , Asgary Saeed , Eghbal Mohammad Jafar , Stowe Sally , Eslami Behnam , Eskandarizade Ali , Shabahang Shahrokh
Published: May 2005

Abstract –  Mineral trioxide aggregate (MTA) is widely used for different perforation repairs, root‐end filling, pulp capping and many other endodontic procedures. Because of potential discoloration effect of gray MTA, white MTA has been introduced into endodontic treatment for the same purposes. This study examined the dental pulp responses in dogs to both types of MTA used as a pulp‐capping agent. The pulps of 24 teeth of four male dogs were exposed with a No.1 round bur and capped with either gray or white MTA. Histologic analysis was performed one and 2 weeks after treatment. Calcified bridge could be seen 1 week after treatment with both types of MTA, with no significant differences between the two treatments.
Can mouthguards prevent mandibular bone fractures and concussions? A laboratory study with an artificial skull model
Authors: Takeda Tomotaka , Ishigami Keiichi , Hoshina Sanae , Ogawa Toru , Handa Jun , Nakajima Kazunori , Shimada Atsushi , Nakajima Tsuneya , Regner Connell Wayne
Published: May 2005

Abstract –  Some sports’ accidents are responsible for inflicting traumatic brain injuries and mandibular bone fractures when impacts occur to the chin. It is often thought that mouthguards can prevent many of these injuries. However, such assertions may be insufficient without adequate research. It is therefore necessary to establish a systematic method of investigation to solve this problem. In the present laboratory study, tests were performed using pendulum impact equipment and an artificial skull model connected to strain gages and accelerometers to simulate and measure the surface distortions related to bone deformation or fractures and the acceleration of the head related to concussions. As impacts, direct blows to the mandibular undersurface were applied. As a result, wearing a mouthguard decreased (P  < 0.01) the distortion to the mandibular bone and the acceleration of the head significantly compared with not wearing a mouthguard (54.7%: to the mandible – measured at a total of three different points, 18.5%: to the head measured at a total of three different points). Within the limits of this study, the following conclusions were drawn: The present measuring system in this study was able to evaluate the distortion to the mandibular and the acceleration of the head from the direct blow to the mandibular undersurface. Mouthguards can reduce distortion to the mandibular and the acceleration of the head from the same blow. So mouthguards might have the possibility to prevent mandibular bone fractures and concussions. However, further well‐designed and exhaustive studies are vital to show that mouthguards reduce the incidence of concussions and mandibular bone fractures.
An Efficient and Accurate Numerical Method of Stress Intensity Factors Calculation of a Branched Crack
Authors: Yan Xiangqiao
Published: May 2005

Based on the analytical solution of Crouch to the problem of a constant discontinuity in displacement over a finite line segment in an infinite elastic solid, in the present paper, the crack-tip displacement discontinuity elements, which can be classified as the left and the right crack-tip elements, are presented to model the singularity of stress near a crack tip. Furthermore, the crack-tip elements together with the constant displacement discontinuity elements presented by Crouch and Starfied are used to develop a numerical approach for calculating the stress intensity factors (SIFs) of general plane cracks. In the boundary element implementation, the left or the right crack-tip element is placed locally at the corresponding left or right crack tip on top of the constant displacement discontinuity elements that cover the entire crack surface and the other boundaries. The method is called the hybrid displacement discontinuity method (HDDM). Numerical examples are given and compared with the available solutions. It can be found that the numerical approach is simple, yet very accurate for calculating the SIFs of branched cracks. As a new example, cracks emanating from a rhombus hole in an infinite plate under biaxial loads are taken into consideration. The numerical results indicate the efficiency of the present numerical approach and can reveal the effect of the biaxial load on the SIFs. In addition, the hybrid displacement discontinuity method together with the maximum circumferential stress criterion (Erdogan and Sih) becomes a very effective numerical approach for simulating the fatigue crack propagation process in plane elastic bodies under mixed-mode conditions. In the numerical simulation, for each increment of crack extension, remeshing of existing boundaries is not required because of an intrinsic feature of the HDDM. Crack propagation is simulated by adding new boundary elements on the incremental crack extension to the previous crack boundaries. At the same time, the element characters of some related elements are adjusted according to the manner in which the boundary element method is implemented.
Nonsynchronous Vibration (NSV) due to a Flow-Induced Aerodynamic
Instability in a Composite Fan Stator
Authors: Sanders A. J.
Published: May 2005

This paper describes the identification and prediction of a new class of nonsynchronous vibration (NSV) problem encountered during the development of an advanced design composite fan stator for an aircraft engine application. Variable exhaust nozzle testing on an instrumented engine is used to map out the NSV boundary, with both choke- and stall-side instability zones present that converge toward the nominal fan operating line and place a limit on the high-speed operating range. Time-accurate three-dimensional viscous CFD analyses are used to demonstrate that the NSV instability is being driven by dynamic stalling of the fan stator due to unsteady shock-boundary layer interaction. The effects of downstream struts in the front frame of the engine are found to exasperate the problem, with the two fat service struts in the bypass duct generating significant spatial variations in the stator flow field. Strain gage measurements indicate that the stator vanes experiencing the highest vibratory strains correspond to the low static pressure regions of the fan stator assembly located approximately 90 degrees away from the two fat struts. The CFD analyses confirm the low static pressure sectors of the stator assembly are the passages in which the flow-induced NSV instability is initiated due to localized choking phenomena. The CFD predictions of the instability frequency are in reasonable agreement with the strain gage data, with the strain gage data indicating that the NSV response occurs at a frequency approximately 25% below the frequency of the fundamental bending mode. The flow patterns predicted by the CFD analyses are also correlated with the results of an engine flow visualization test to demonstrate the complex nature of the flow field.
Adiabatic Effectiveness Measurements of Endwall Film-Cooling for a
First-Stage Vane
Authors: Knost D. G. , Thole K. A.
Published: May 2005

In gas turbine development, the direction has been toward higher turbine inlet temperatures to increase the work output and thermal efficiency. This extreme environment can significantly impact component life. One means of preventing component burnout in the turbine is to effectively use film-cooling whereby coolant is extracted from the compressor and injected through component surfaces. One such surface is the endwall of the first-stage nozzle guide vane. This paper presents measurements of two endwall film-cooling hole patterns combined with cooling from a flush slot that simulates leakage flow between the combustor and turbine sections. Adiabatic effectiveness measurements showed the slot flow adequately cooled portions of the endwall. Measurements also showed two very difficult regions to cool, including the leading edge and pressure side-endwall junction. As the momentum flux ratios were increased for the film-cooling jets in the stagnation region, the coolant was shown to impact the vane and wash down onto the endwall surface. Along the pressure side of the vane in the upstream portion of the passage, the jets were shown to separate from the surface rather than penetrate to the pressure surface. In the downstream portion of the passage, the jets along the pressure side of the vane were shown to impact the vane thereby eliminating any uncooled regions at the junction. The measurements were also combined with computations to show the importance of considering the trajectory of the flow in the near-wall region, which can be highly influenced by slot leakage flows.
Experimental Investigation of a Transonic Aspirated
Compressor
Authors: Schuler Brian J. , Kerrebrock Jack L. , Merchant Ali
Published: May 2005

The experimental investigation of a transonic aspirated stage demonstrating the application of boundary layer aspiration to increase stage work is presented. The stage was designed to produce a pressure ratio of 1.6 at a tip speed of 750ft∕s resulting in a stage work coefficient of 0.88. The primary aspiration requirement for the stage is a bleed fraction 0.5% of the inlet mass flow on the rotor and stator suction surfaces. Additional aspiration totaling 2.8% was also used at shock impingement locations and other locations on the hub and casing walls. Detailed rotor and stator flow field measurements, which include time-accurate and ensemble-averaged data, are presented and compared to three-dimensional viscous computational analyses of the stage. The stage achieved a peak pressure ratio of 1.58 and through-flow efficiency of 90% at the design point. In addition, the stage demonstrated good performance with an aspiration lower than the design requirement, and a significant off-design flow range below that predicted by the computational analysis.
Nusselt Numbers and Flow Structure on and Above a Shallow Dimpled
Surface Within a Channel Including Effects of Inlet Turbulence Intensity
Level
Authors: Ligrani P. M. , Burgess N. K. , Won S. Y.
Published: May 2005

Experimental results from a channel with shallow dimples placed on one wall are given for Reynolds numbers based on channel height from 3,700 to 20,000, levels of longitudinal turbulence intensity from 3% to 11% (at the entrance of the channel test section), and a ratio of air inlet stagnation temperature to surface temperature of approximately 0.94. The ratio of dimple depth to dimple print diameter δ∕D is 0.1, and the ratio of channel height to dimple print diameter H∕D is 1.00. The data presented include friction factors, local Nusselt numbers, spatially averaged Nusselt numbers, a number of time-averaged flow structural characteristics, flow visualization results, and spectra of longitudinal velocity fluctuations which, at a Reynolds number of 20,000, show a primary vortex shedding frequency of 8.0Hz and a dimple edge vortex pair oscillation frequency of approximately 6.5Hz. The local flow structure shows some qualitative similarity to characteristics measured with deeper dimples (δ∕D of 0.2 and 0.3), with smaller quantitative changes from the dimples as δ∕D decreases. A similar conclusion is reached regarding qualitative and quantitative variations of local Nusselt number ratio data, which show that the highest local values are present within the downstream portions of dimples, as well as near dimple spanwise and downstream edges. Local and spatially averaged Nusselt number ratios sometimes change by small amounts as the channel inlet turbulence intensity level is altered, whereas friction factor ratios increase somewhat at the channel inlet turbulence intensity level increases. These changes to local Nusselt number data (with changing turbulence intensity level) are present at the same locations where the vortex pairs appear to originate, where they have the greatest influences on local flow and heat transfer behavior.
Ultimate Response of Composite Cylinders Under Flexural Load
Authors: Huang Zheng-Ming
Published: May 2005

Composite cylinders are generally used as primary load carrying structures. Their constitutive behavior up to failure is crucial for a critical design. This paper focuses on the ultimate flexural strength of a polymer based composite cylinder subjected to bending. In such a case, the outmost filament of the cylinder subjected to the maximum bending stress fails the first. The complexity, however, lies in the fact that the failure of this outmost filament generally does not correspond to the ultimate failure. Additional loads can still be applied to the cylinder and a progressive failure process will result. To deal with such a problem in this paper, the cylinder is discretized into a number of lamina layers with different widths. The bridging micromechanics model [Huang, Z. M., Composites Part A, 2001] combined with the classical lamination theory has been applied to understand the progressive failure process generated in the cylinder. Only its constituent fiber and matrix properties under bending are necessary for this understanding and reasonably good accuracy has been achieved. However, the ultimate failure of the cylinder cannot be figured out only based on a stress failure criterion, as one cannot know a priori which ply failure corresponds to the ultimate failure. An additional critical deflection (curvature) condition must be employed also. By using both the stress and the deflection conditions, the estimated ultimate strength of the cylinder agreed well with an experimental measurement.