Annals of periodontology最新文献

{"title":"Implant Survival to 36 Months as Related to Length and Diameter","authors":"Sheldon Winkler,&nbsp;Harold F. Morris,&nbsp;Shigeru Ochi","doi":"10.1902/annals.2000.5.1.22","DOIUrl":"10.1902/annals.2000.5.1.22","url":null,"abstract":"<p><b>Background:</b> It is generally accepted that diameter and length of an endosseous dental implant and its stability at placement are critical factors in achieving and maintaining osseointegration. In the event of slight implant mobility at placement, the conventional or accepted treatment is to place a longer implant and/or one of wider diameter. This manuscript presents stability and survival/failure data for implants of different diameters and lengths following 36 months post-placement, as well as crestal bone loss data between placement and uncovering.</p><p><b>Methods:</b> A subset of the Dental Implant Clinical Research Group's database was used to study the 3- year survival and stability of various implant lengths (7 mm, 8 mm, 10 mm, 13 mm, and 16 mm) and diameters (3 mm+ and 4 mm+). Placement to uncovering crestal bone loss was also determined. The implants were generally representative of those available for clinical use (screws, basket, grooved, hydroxy-apatitecoated, CP-Ti, Ti-alloy). The study protocol specified that the implants be randomized to various jaw regions to accomplish the primary goals of the study—the comparison of each implant design's overall survival. A total of 2,917 implants were placed, restored, and followed. Data for all 3 mm to 3.9 mm diameter implants were pooled into a “3+” group, and the 4 mm to 4.9 mm diameter implants into a “4+” mm group. No attempt was made to look at the influence of any other variables on survival outcomes. The possible influence of clustering on survival was taken into consideration.</p><p><b>Results:</b> The 3+ mm group had a mean stability (PTV) of −3.8 (SD = 2.9), and the 4+ group had a mean PTV of −4.4 (SD = 2.7) (<i>P</i> &lt;0.05). The PTVs for implant lengths ranged from −2.9 (SD = 2.8) for 7 mm lengths to −3.9 (SD = 2.9) for 16 mm lengths (<i>P</i> &lt;0.05). Survival to 36 months was 90.7% for the 3+ diameter and 94.6% for the 4+ group (<i>P</i> = 0.01). Survival ranged from 66.7% for the 7 mm implants to 96.4% for 16 mm implants (<i>P</i> = 0.001). Outcomes did not change when clustering was considered, although the P value decreased slightly.</p><p><b>Conclusions:</b> The results indicate that: 1) shorter implants had statistically lower survival rates as compared with longer implants; 2) 3+ mm diameter implants had a lower survival rate as compared with 4+ mm implants; 3) 3+ mm diameter implants are less stable (more positive PTVs) than 4+ mm implants; and 4) there was no significant difference in crestal bone loss for the two different implant diameters between placement and uncovering.<i>Ann Periodontol 2000;5:22-31.</i></p>","PeriodicalId":79473,"journal":{"name":"Annals of periodontology","volume":"5 1","pages":"22-31"},"PeriodicalIF":0.0,"publicationDate":"2000-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1902/annals.2000.5.1.22","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"68173725","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Survival of Various Implant-Supported Prosthesis Designs Following 36 Months of Clinical Function","authors":"Arthur M. Rodriguez,&nbsp;Ira H. Orenstein,&nbsp;Harold F. Morris,&nbsp;Shigeru Ochi","doi":"10.1902/annals.2000.5.1.101","DOIUrl":"10.1902/annals.2000.5.1.101","url":null,"abstract":"<p><b>Background:</b> The use of endosseous dental implants to replace natural teeth lost to trauma, dental caries, or periodontal disease has become a predictable form of prosthetic treatment since gaining popularity in the early 1980s. While numerous clinical studies have focused on the survival of implants, few address the survival of different prosthesis designs.</p><p><b>Methods:</b> Beginning in 1991, 882 prostheses supported by more than 2,900 implants (687 patients) were placed by the Department of Veterans Affairs Dental Implant Clinical Research Group (DICRG). These prostheses were divided into five research strata based on arch location. The recommended design for each stratum was: bar-supported overdenture (maxillary completely edentulous); screw-retained hybrid denture (mandibular completely edentulous); screw-retained fixed partial denture (mandibular and maxillary posterior partially edentulous); and cemented single crown (maxillary anterior single tooth). Alternative overdenture designs were utilized in the edentulous arches when the recommended prosthesis could not be fabricated. Prosthesis success rates for the research strata were calculated for an observation time of up to 36 months following prosthesis placement.</p><p><b>Results:</b> Success rates for the maxillary edentulous stratum ranged from 94.6% for the bar-retained overdenture supported by five to six fixtures to 81.8% for the cap-retained overdenture. The mandibular edentulous strata produced success rates of 98.1% for the fixed hybrid prosthesis to 91.7% for the cap-retained prosthesis. Success rates for maxillary and mandibular posterior fixed partial dentures were 94.3% and 92.6%, respectively, while the maxillary anterior single-tooth prosthesis yielded a success rate of 98.1% for the 36-month observation period.</p><p><b>Conclusions:</b> The recommended prosthesis designs investigated in this study proved to be reliable, with encouraging success rates for an observation period of 36 months following placement. <i>Ann Periodontol 2000;5:101-108.</i></p>","PeriodicalId":79473,"journal":{"name":"Annals of periodontology","volume":"5 1","pages":"101-108"},"PeriodicalIF":0.0,"publicationDate":"2000-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1902/annals.2000.5.1.101","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"68172844","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Stability of the Bone-Implant Complex. Results of Longitudinal Testing to 60 Months With the Periotest Device on Endosseous Dental Implants","authors":"Richard S. Truhlar,&nbsp;Harold F. Morris,&nbsp;Shigeru Ochi","doi":"10.1902/annals.2000.5.1.42","DOIUrl":"10.1902/annals.2000.5.1.42","url":null,"abstract":"<p><b>Background:</b> Maintenance of the health and integrity of the bone-implant complex (osseointegration) has been shown to be essential for long-term success of root-form, endosseous dental implants. If reliable clinical indicators of adequacy of the bone-implant complex existed, they could stimulate new and innovative early intervention research to arrest or reverse early deterioration of the bone-implant complex. In the absence of such indicators, this has been problematic. The Periotest may have the potential to provide this information by indirectly assessing the status of the bone-implant complex. However, little information is available that documents either the capability of the Periotest to reliably assess changes of the bone-implant complex or the “normal variations” in Periotest values (PTVs) for both HA-coated and non-coated implants.</p><p><b>Methods:</b> The purpose of this paper was to document changes in PTVs as influenced by various implant surfaces, implant designs, and bone densities. The mean PTVs recorded for each visit, for all implant types and bone densities, were combined to provide an overall average PTV (A-PTV). The changes in stability (PTVs) were analyzed using a generalized linear model (GLM) with repeated measures (Hotelling's Trace).</p><p><b>Results:</b> The A-PTV for all implants over all visits was −3.5. The mean PTVs ranged from −4.2 (SD = 2.4) at uncovering to −3.9 (SD = 2.9) at 60 months. All implants in bone qualities 1 and 2 (BQ-1 and BQ-2) became more stable over time, while those in bone quality 3 or 4 (BQ-3 and BQ-4) showed a slight decrease in stability. In BQ-1, the mean PTVs increased from −4.7 at uncovering to −4.9 at 60 months. A similar increase in stability occurred in BQ-2 (−4.1 at uncovering to −4.4 at 60 months). In BQ-3, the stability of the implants decreased over time (−3.6 at uncovering to −2.9 at 60 months), with similar changes recorded for BQ-4 (−2.5 at uncovering to −1.0 at 60 months). When comparing the stability of all HA-coated with all non-coated implants, the HA implants became less stable (−4.4 to −3.4) over time, while non-coated implants showed an improvement in stability (−3.5 to −4.5). The changes in stability found in BQ-1, BQ-2, and BQ-3 were similar, with HA implants becoming less stable and non-coated more stable. HA- and non-coated comparisons were not possible in BQ-4 since there were too few non-coated implants placed in this type of bone. The HAcoated screw showed a decrease in stability when compared to the non-coated screw.</p><p><b>Conclusions:</b> Conclusions of the study are as follows: 1) PTVs are influenced by bone quality and surface coating of the implant; 2) the PTVs at the time of uncovering provide the best estimate of a clinically acceptable PTV for that bone-implant complex; 3) while the PTVs for any bone-implant complex may fluctuate +/− 1.0 around the uncovering PTV during routine healing and loading of the implant, a consistent shift toward a positi","PeriodicalId":79473,"journal":{"name":"Annals of periodontology","volume":"5 1","pages":"42-55"},"PeriodicalIF":0.0,"publicationDate":"2000-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1902/annals.2000.5.1.42","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"68174096","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Clinical Studies of Endosseous Dental Implants: The Good, the Bad and the Ugly","authors":"Harold F. Morris,&nbsp;Shigeru Ochi","doi":"10.1902/annals.2000.5.1.6","DOIUrl":"10.1902/annals.2000.5.1.6","url":null,"abstract":"","PeriodicalId":79473,"journal":{"name":"Annals of periodontology","volume":"5 1","pages":"6-11"},"PeriodicalIF":0.0,"publicationDate":"2000-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1902/annals.2000.5.1.6","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"68174244","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Index","authors":"","doi":"10.1902/annals.2000.5.1.188","DOIUrl":"https://doi.org/10.1902/annals.2000.5.1.188","url":null,"abstract":"","PeriodicalId":79473,"journal":{"name":"Annals of periodontology","volume":"5 1","pages":"188-192"},"PeriodicalIF":0.0,"publicationDate":"2000-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1902/annals.2000.5.1.188","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"138020897","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Variables Affecting Survival of Single-Tooth Hydroxyapatite-Coated Implants in Anterior Maxillae at 3 Years","authors":"Ira H. Orenstein,&nbsp;Vincent Petrazzuolo,&nbsp;Harold F. Morris,&nbsp;Shigeru Ochi","doi":"10.1902/annals.2000.5.1.68","DOIUrl":"10.1902/annals.2000.5.1.68","url":null,"abstract":"<p><b>Background:</b> The development and expanded use of endosseous dental implants over the last two decades have been remarkably rapid. It is, therefore, imperative that the dental profession closely monitor the performance of root-form implants used in a variety of applications. The Dental Implant Clinical Research Group (DICRG) was established in 1990 by the Department of Veterans Affairs as a forum for conducting prospective, multidisciplinary, multicentered studies in the field of implant dentistry. The DICRG comprised 30 VA medical centers and 2 dental schools at the time of this study. This paper reports on the survival of hydroxyapatite (HA)-coated grooved implants used to replace single missing teeth in anterior maxillae at 3 years post-implant placement.</p><p><b>Methods:</b> During a 4-year accrual period, a total of 247 single-tooth implant restorations were placed in anterior maxillae. This paper focuses on the survival of 222 implants (149 patients) for which 3-year data were recorded for the period from placement. Survival was examined with respect to patient demographics and health status, implant location, surgical variables, and 2-week post-placement use of chlorhexidine digluconate (0.12%) rinses. Implant stability was recorded using a hand-held probe. Periodontal-type measures were recorded and evaluated, and all complications related to osseointegration were noted. Failure was defined as removal of the implant for any reason.</p><p><b>Results:</b> Establishment and maintenance of osseointegration at 3 years post-placement was 97.3%. During this 3-year period, 6 implants were removed due to either failure to osseointegrate or loss of osseointegration. Implant length correlated positively with 3-year survival (<i>P</i> = 0.003, exact test). The use of preoperative antibiotics was nearly significant to implant survival (<i>P</i> = 0.051, Pearson chi-square). Mean stability values (PTVs) increased incrementally from −4.5 at uncovering to +1.1 at 36 months, indicating a decrease in stability of the bone-implant-prosthesis complex. The most common complication was related to inadequate available bone to fully house implants.</p><p><b>Conclusions:</b> Three-year post-placement survival data suggest that the use of HA-coated, grooved, endosseous implants to support maxillary anterior single-tooth replacements is a predictable and reliable procedure that can offer significant benefits. Longer implants demonstrated higher survival than shorter implants. The use of preoperative antibiotics was nearly significant to implant survival, and there was an increase in mean PTVs observed over the duration of the study. Further research is needed to assess stability of the hydroxyapatite-bone interface over time.<i>Ann Periodontol 2000;5:68-78.</i></p>","PeriodicalId":79473,"journal":{"name":"Annals of periodontology","volume":"5 1","pages":"68-78"},"PeriodicalIF":0.0,"publicationDate":"2000-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1902/annals.2000.5.1.68","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"68173746","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Three-Year Post-Placement Survival of Implants Mobile at Placement","authors":"Ira H. Orenstein,&nbsp;Dennis P. Tarnow,&nbsp;Harold F. Morris,&nbsp;Shigeru Ochi","doi":"10.1902/annals.2000.5.1.32","DOIUrl":"10.1902/annals.2000.5.1.32","url":null,"abstract":"<p><b>Background:</b> Although rigid fixation of endosseous implants at the time of placement is generally thought to be a prerequisite for successful osseointegration, the Dental Implant Clinical Research Group (DICRG) of the Department of Veterans Affairs has reported on implants that integrated despite being mobile at placement. The present study examines the frequency of osseointegration and the 36-month post-placement survival of implants mobile at placement in a prospective, multicenter, longitudinal clinical study of more than 3,000 implants conducted by the DICRG.</p><p><b>Methods:</b> A total of 3,111 implants of 6 different designs were placed in all jaw regions in more than 800 patients at 32 study centers. At the time of this report, 2,770 of these implants had been followed for 36 months post-placement. They included 89 implants that were mobile at placement. Data for demographic variables, implant coating, bone quality, incision type, bone augmentation, and antibiotic usage were recorded. An electronic hand-held probe was used to measure mobility at uncovering and at regular follow-up intervals.</p><p><b>Results:</b> Eighty-nine of 2,770 inserted implants were mobile at placement. Results are reported for two periods: from placement to 36 months and from prosthetic loading to 36 months. The latter method eliminated early failures and resulted in substantially higher scores for both mobile implants at placement (95.9% survival from prosthetic loading to 36 months post-placement versus 79.8% from placement to 36 months) and implants not mobile at placement (98.4% versus 93.4%). Mobility at placement was significant to 3-year survival (<i>P</i> &lt;0.001). Hydroxyapatite (HA) coating improved the performance of implants mobile at placement (91.8% for HA-coated versus 53.6% for non-HA) and those not mobile at placement (97.2% for HAcoated versus 87.4% for non-HA). Radiographic findings suggested that crestal bone response around implants which were mobile versus immobile at placement was similar.</p><p><b>Conclusions:</b> Although implant stability at the time of placement is clearly desirable as seen in the superior 3-year survival of stable implants, it may not be an absolute prerequisite to osseointegration or to longterm survival. Several factors may influence the decision to remove or replace a mobile implant. HA-coating significantly improved the performance of both mobile and immobile implants at placement to 3 years post-placement (<i>P</i> &lt;0.001). <i>Ann Periodontol 2000;5:32-41.</i></p>","PeriodicalId":79473,"journal":{"name":"Annals of periodontology","volume":"5 1","pages":"32-41"},"PeriodicalIF":0.0,"publicationDate":"2000-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1902/annals.2000.5.1.32","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"68173921","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Periodontal-Type Measurements Associated With Hydroxyapatite-Coated and Non—HA-Coated Implants: Uncovering to 36 Months","authors":"Harold F. Morris,&nbsp;Shigeru Ochi,&nbsp;J. Robert Spray,&nbsp;John W. Olson","doi":"10.1902/annals.2000.5.1.56","DOIUrl":"10.1902/annals.2000.5.1.56","url":null,"abstract":"<p><b>Background:</b> While the use of hydroxyapatite (HA)-coated endosseous dental implants has gained in popularity over the past 10 years, the short-term and long-term predictability and indications for their use remain highly controversial. Some reports suggest that the HA coating may separate from the substructure, undergo dissolution in tissue fluids, and/or contribute to rapid osseous breakdown around the implant. Other reports, however, relate favorable responses to HA-coated implants, which include rapid bone adaptation to the HA, greater stability at uncovering, and increased coronal bone growth. These contradictions may be related to differences in chemical composition of the HA on the implant surface. Most clinicians and researchers may agree that long-term, independent, scientific clinical studies are needed to compare HA-coated and non—HA-coated (titanium-alloy and CP-titanium) implants under the same conditions. Concerns appear in the literature that HA-coated implants experience greater breakdown because they are more susceptible to bacterial colonization due to their roughness and hydrophilicity. Some studies suggest that specific putative periodontal pathogens may adhere to the HA, thereby predisposing the implant to greater peri-implantitis than that experienced by non-HA implants.</p><p><b>Methods:</b> A total of 32 clinical research centers, located in various geographic regions of the United States, were selected to participate in a comprehensive clinical study. More than 2,900 HA-coated and non- HA implants were randomized as to location within one of three jaw regions—maxillary anterior, mandibular anterior, and mandibular posterior—and followed for 36 months. It can be assumed that in each of these jaw regions, the conditions associated with both implant surface types would be similar enough to permit meaningful comparisons of periodontal-type measurements that have not previously been reported. Periodontal- type measurements (gingiva, plaque, suppuration, and calculus indices; probing depth; attachment levels; recession; and keratinized tissue width) for each aspect of each implant (mesial, facial, distal, and lingual) were recorded at 3, 6, 9, 12, 18, 24, and 36 months following implant uncovering. The implant was considered the experimental unit for analysis using generalized estimating equation and repeated measure methods. Data for the four aspects of each implant, as well as measurements over time, were all clustered in the unit of analysis.</p><p><b>Results:</b> The percentages of implants with zeros recorded for the indices was remarkably similar for both HA-coated and non-HA implants. While statistically significant differences were found for some of the measurements associated with HA-coated and non-HA implants under certain conditions, these differences were too small to be considered clinically significant.</p><p><b>Conclusions:</b> Overall, there was no clinically significant difference between the periodonta","PeriodicalId":79473,"journal":{"name":"Annals of periodontology","volume":"5 1","pages":"56-67"},"PeriodicalIF":0.0,"publicationDate":"2000-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1902/annals.2000.5.1.56","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"68174191","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Periodontic-Endodontic Lesions","authors":"Huan Xin Meng Dr.","doi":"10.1902/annals.1999.4.1.84","DOIUrl":"10.1902/annals.1999.4.1.84","url":null,"abstract":"<p>Lesions of the periodontal ligament and adjacent alveolar bone may originate from infections of the periodontium or tissues of the dental pulp. This review focuses on the relationship of lesions of endodontic origin with lesions of periodontal origin and their classification. <i>Ann Periodontol 1999;4:84-89.</i></p>","PeriodicalId":79473,"journal":{"name":"Annals of periodontology","volume":"4 1","pages":"84-89"},"PeriodicalIF":0.0,"publicationDate":"1999-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1902/annals.1999.4.1.84","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"21707034","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Consensus Report: Periodontitis as a Manifestation of Systemic Diseases","authors":"Jan Lindhe,&nbsp;Richard Ranney,&nbsp;Ira Lamster,&nbsp;Allan Charles,&nbsp;Chong-Pyoung Chung,&nbsp;Thomas Flemmig,&nbsp;Denis Kinane,&nbsp;Max Listgarten,&nbsp;Harald Löe,&nbsp;Robert Schoor,&nbsp;Gregory Seymour,&nbsp;Martha Somerman","doi":"10.1902/annals.1999.4.1.64","DOIUrl":"10.1902/annals.1999.4.1.64","url":null,"abstract":"","PeriodicalId":79473,"journal":{"name":"Annals of periodontology","volume":"4 1","pages":"64"},"PeriodicalIF":0.0,"publicationDate":"1999-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1902/annals.1999.4.1.64","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"68171293","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}