bluuebunny/crossref_metadata_2025 huggingface dataset:
Histopathological Investigation of Gingival Tissue From Patients With Rapidly Progressive Periodontitis
Authors: Hillmann Georg , Dogan Sami , Geurtsen Werner
Published: March 2012

In this study, fine structural features of the pocket walls in rapidly progressive periodontitis (RPP) and adult periodontitis (AP) in 20 cases were compared using light and transmission electron microscopy. Gingiva was also obtained from a control group of periodontally healthy teeth. Clinical parameters were assessed in both RPP and AP patients and in controls. Bone destruction and attachment loss were more marked in RPP than in AP. Light microscopical observations of inflamed RPP tissue as compared to AP showed gross histological distortions in the pocket walls. Micro‐ridges within the epithelium and large intercellular spaces between the epithelial cells were observed in most RPP biopsies. Epithelial cells surrounding the microclefts and adjacent keratinocytes were found to produce interleukin‐1β (IL‐1β). Prevotella intermedia and Porphyromonas gingivalis were identified in the RPP biopsies using immunohistological methods. These microorganisms were localized outside the epithelium and inside intercellular spaces. Furthermore, the effect of inflammation on the distribution of collagen types I, III, IV, V, and VI in the human gingiva was studied after staining them with antibodies to these proteins. In RPP and AP tissues, the staining was sparse in areas of inflammation and leukocytic infiltration. Collagen type I and III were almost entirely lost at sites of inflammation. Type V and VI collagen antibodies were retained in inflamed areas. Type IV collagen was restricted to basement membrane structures. These observations demonstrated numerous structural features indicative of more pronounced degenerative changes in RPP than in AP. J Periodontol 1998;69:195–208.
Immediate Loading of Titanium Plasma‐Sprayed Implants: An Histologic Analysis in Monkeys
Authors: Piattelli A. , Corigliano M. , Scarano A. , Costigliola G. , Paolantonio M.
Published: March 2012

Aim of this study was to evaluate peri‐implant tissue reactions to immediately loaded titanium plasma‐sprayed implants in Macaca fascicularis monkeys. A total of 48 titanium plasma‐sprayed implants were inserted (24 in the posterior maxilla and 24 in the posterior mandible). A metal superstructure was cemented 3 days after implant insertion on 24 implants (12 in the maxilla and 12 in the mandible) (test implants). The remaining 24 implants (12 in the maxilla and 12 in the mandible) were left unloaded (control implants). Nine months after implant placement a block section was carried out, the defect filled with non‐resorbable hydroxyapatite, and all 48 implants retrieved. The implants were treated to obtain thin ground sections. Three slides were cut for each implant and examined under normal and polarized light and a morphometrical analysis done. All implants were covered by bone under light microscopy. The histomorphometrical analysis demonstrated that in test implants, the bone‐implant contact percentage was 67.3% (± 7.6%) in the maxilla, and 73.2% (± 5.9%) in the mandible; in control implants the percentages were, respectively, 54.5% (± 3.3%) and 55.8% (± 6.5%). In the test implants the bone around the implants tended to have a more compact appearance. In conclusion, our study demonstrated that in test implants the bone‐implant contact percentage was significantly greater than in the controls (P < 0.01) and no fibrous connective tissue was present at the interface. J Periodontol 1998;69:321–327.
Horizontal Alveolar Bone Loss and Vertical Bone Defects in an Adult Patient Population
Authors: Persson Rigmor E. , Rollender Lars G. , Laurell Lars , Persson G. Rutger
Published: March 2012

The objectives of the present investigation were to analyze intraoral radiographs and to study 1) the distribution of the distance between the cemento‐enamel junction (CEJ) and the alveolar bone level (BL) and 2) the prevalence and severity of vertical defects, and furcation lesions in 416 individuals seeking dental care. Full mouth radiographs were enlarged 7.5 times and the mesial and distal distances between CEJ and bone level were measured. The extent of interradicular molar radiolucencies was also measured. Images of 10,282 teeth were studied. Subjects were between 15 to 94 years (mean age: 47.2,. S.D. ± 15.2). On average they had 24.8 teeth (S.D.±5.5). The mean distance CEJ‐BL increased significantly up to age 45 (r2 = 0.07; β = 0.29; P < 0.0001) and remained stable thereafter r2 = 0.09, β = −0.02, N.S.). The mean distance CEJ‐bone level was 1.4 mm (S.D.±0.7) in the 15 to 24 age group; 3.0 (S.D.±1.5) in the 45 to 54 age group; and 3.02 (S.D.±1.4) in the 75 to 94 age group. No vertical defects were found in 163 participants (39.3%); vertical defects s: 3.0 mm were found in 30.2% (126). Mesial defects were significantly more common that distal defects (P < 0.001). The extent of horizontal bone loss was correlated to extent of vertical defects (r2 = 0.88; P < 0.0001). The number of remaining teeth was not associated with horizontal or vertical bone loss. In conclusion, the study indicated that few of the individuals had extensive horizontal bone loss. Vertical defects suitable for guided tissue regeneration procedures however, were found in many patients. J Periodontol 1998;69:348–356.
Histology Near Periodontitis Osteoclasts
Authors: Udert Chad E. , Ganatra Seema , Reinhardt Richard A. , Patil Kashinath D.
Published: March 2012

Histologic evaluation of periodontal tissues generally has included only areas adjacent to the gingival crevice, without knowledge or quantitation of alveolar crest osteoclastic (periodontitis) activity and infiltrate. The purpose of this study was to use human autopsy material to quantitate collagen and cell types adjacent to presumed periodontitis activity and quiescence, each in the same individual. Thirteen subjects contributed 4 sites each, 2 exhibiting alveolar crest periosteal osteoclasts in resorption lacunae/periodontitis activity (OC/PA) and 2 with no osteoclasts or resorption lacunae/periodontal quiescence (NOC/PQ). Tissue and cell morphotypes were quantitated by 2 evaluators at 100 intersects in 0.06 mm2 fields progressing from the alveolar crest toward the gingival crevice. Cell morphotypes/tissue components were compared between groups and fields using a general linear model with repeated measures. OC/PA fields adjacent to the alveolar crest contained significantly more intersects with macrophage‐like cells (10.7 ± 1.1 versus 5.3 ± 0.6%, P = 0.0003), lymphocytes (4.6 ± 1.1 versus 0.7 ± 0.2%, P = 0.0013), plasma cells (13.3 ± 2.7 versus 2.1 ± 0.6%, P = 0.0004), and less with collagen (48.9 ± 3.5 versus 75.0 ± 2.0%, P = 0.0001) than NOC/PQ fields. Numbers of lymphocytes and plasma cells increased (P = 0.0006 and P = 0.0002, respectively), and fibroblasts and collagen decreased (P = 0.0024 and P = 0.0001, respectively) in fields up to 1 mm closer to the gingival crevice. However, apparent osteoclastic activity in periodontitis subjects is associated with a significant inflammatory cell infiltrate, especially macrophages and plasma cells. J Periodontol 1998;69:363–366.
Elevated Salivary EGF Levels Stimulated by Periodontal Surgery
Authors: Oxford Gregory E. , Nguyen Kim H. T. , Alford Connie E. , Tanaka Yoko , Humphreys‐Beher Michael G.
Published: March 2012

Previous studies have shown epidermal growth factor (EGF) to be involved in oral wound healing as well as gastric cytoprotection. EGF functions with hormone‐like properties to stimulate epithelial cells by binding to the EGF receptor which ultimately leads to proliferation via signal transduction mechanisms. Salivary glands are a major source of EGF. The purpose of this study was to determine if intra‐oral wounding by periodontal surgery stimulated increased salivary EGF levels. Salivary EGF levels were determined for 12 systemically healthy individuals (ages 27 to 70 years old) presurgically and postsurgically at 6, 12, 18, 24, 30, 36, and 42 hours and 2 and 6 weeks. Three ml of unstimulated whole saliva was obtained at each time point to allow immunoassay quantitation. Age and gender matched unoperated patients served as controls. Salivary samples were incubated with monoclonal and polyclonal EGF antibodies in these “sandwich” enzyme immunoassays. Quantitation was obtained by spectrometric analysis at OD 450 nm after addition of 200 μl of colorimetrie substrate. Mean EGF levels ranged from 2441 pg/ml presurgically to 3349 pg/ml at 18 hours postsurgically and 1207 pg/ml at 6 weeks postsurgically. Repeated measures analysis of variance indicated statistically significant differences in 18 hours postsurgical salivary EGF levels when compared to controls and to postsurgical levels from 36 hours forward (P < 0.01). A second smaller rise in EGF was detected at 30 hours. These results suggest a transient increase in salivary EGF levels in response to intra‐oral wounding. J Periodontol 1998;69:479–484.
The Role of Local Drug Delivery in the Management of Periodontal Diseases: A Comprehensive Review
Authors: Greenstein Gary , Polson Alan
Published: March 2012

This review article evaluates the role of local drug delivery systems in the management of periodontal diseases. The efficacy of several local delivery devices (i.e., tetracycline fibers, metronidazole and minocycline gels, chlorhexidine chips, and doxycycline polymer) which are either commercially available in the United States or abroad, or are currently under consideration for Food and Drug Administration (FDA) approval are discussed. The drug delivery systems are assessed with regard to their functional characteristics, effectiveness as a monotherapy, as compared to scaling and root planing, and ability to enhance conventional therapy. Furthermore, controversies associated with local delivery are addressed (e.g., induction of bacterial resistant strains, the efficacy of systemic versus local drug delivery, and whether local drug delivery should function as an alternative or as an adjunct to conventional treatment). J Periodontol 1998;69:507–520.
Guided Bone Regeneration Utilizing Expanded Polytetrafluoroethylene Membranes in Combination With Submerged and Nonsubmerged Dental Implants in Beagle Dogs
Authors: Fiorellini Joseph P. , Engebretson Steven P. , Donath Karl , Weber Hans Peter
Published: March 2012

Treatment of partial and total edentulism with submerged and nonsubmerged dental implants which follows the concept of osseointegration has become an accepted treatment modality. With compromised implant sites, practitioners have begun to combine one‐stage implants with established techniques including guided bone regeneration. However, the clinical evaluation of this technique is limited. Therefore, the purpose of this study was to evaluate osseointegration and bone regeneration around nonsubmerged or submerged implants placed directly into surgically created osseous defects with or without expanded polytetrafluoroethylene (ePTFE) membranes. A total of 24 implants were placed in the mandibles of 4 beagle dogs and randomly assigned to 1 of 3 treatment groups. In group A, nonsubmerged implants were placed into osseous defects and treated with a poncho style ePTFE membrane. These membranes had a hole punched into the center and were slipped over the nonsubmerged implants. In group B, nonsubmerged implants were placed into osseous defects without an ePTFE membrane. In group C, submerged implants were placed into osseous defects and covered with an ePTFE membrane. Histometric measurements of each treatment group were made to determine percent bone gain or loss along the implant surface. Although a number of membrane removals occurred during the healing period, histological analysis indicated osseous ingrowth and osseointegration around nonsubmerged and submerged implants. An overall comparison of the treatment groups with ANOVA revealed that there were no significant differences between treatment groups, P >0.05. However, when the data were stratified into sites which retained or lost the ePTFE membrane, the percent of bone regeneration was reduced in group A. Therefore, it may be recommended that nonsubmerged implants be placed with a submerged or “semi‐submerged” protocol when utilized in conjunction with ePTFE membranes. J Periodontol 1998;69:528–535.
A Clinical Evaluation of an Allograft Combined with a Bioabsorbable Membrane Versus an Alloplast/Allograft Composite Graft Combined With a Bioabsorbable Membrane. 100 Consecutively Treated Cases
Authors: Harris Randall J.
Published: March 2012

The purpose of this study was to evaluate and compare the clinical effectiveness of 2 surgical techniques in treating periodontal defects. Both techniques involved tetracycline treatment of a root planed root, grafting the osseous defect with a bone graft, and placement of a bioabsorbable membrane. In group A, the bone graft was a mix of demineralized freeze‐dried allograft, tetracycline, and porous hydroxyapatite and in group B, the bone graft was a mix of demineralized freeze‐dried allograft and tetra cycline. There was a statistically significant increase in recession (group A, 0.7 mm; group B, 0.6 mm), decreases in probing depth (group A, 6.1 mm; group B, 5.6 mm), and gains in attachment levels (group A, 5.4 mm; group B, 5.0 mm). There were no statistically significant differences between the results for either group. The defects associated with furcations and those that were not associated with furcations had similar results, except for the percent attachment gain. Smoking and age (≥60 years old) could not be associated with results. Defects with ≥10 mm probing depths (PD) had greater PD reductions (group A, 7.7 mm; group B, 7.1) and attachment gains (group A, 6.6 mm; group B, 6.4 mm) than the defects with probing depths less than 10 mm (probing reduction group A, 4.8 mm; group B, 4.5 mm; attachment gain group A, 4.4 mm; group B, 4.0 mm). Both surgical procedures improved the clinical situation. However, neither technique seemed to offer a statistical advantage over the other. The inclusion of porous hydroxyapatite did not improve or diminish the results. J Periodontol 1998;69:536–546.
Urinary Catecholamine Levels and Gingivitis in Children
Authors: Vanderas Apostole P. , Kavvadia Katerina , Papagiannoulis Liza
Published: March 2012

This study investigated the relationship between gingivitis and emotionally stressful states measured by the urinary catecholamines in children. Three‐hundred and fourteen (314) children, boys and girls, aged 6 to 8 years were included in the study. Gingivitis was recorded by the gingival bleeding index and dental plaque by the plaque control record index. Proximal decayed surfaces, faulty restorations, and stainless steel crowns were diagnosed clinically and radiographically. Information concerning systemic and socioeconomic factors was collected by a questionnaire. A 24‐hour urine sample was collected for each subject and analyzed by the HPLC technique to assay the catecholamine content. The multiple‐regression analysis was carried out to test whether gingivitis was affected by the studied variables. The 95% probability was used. The results showed that epinephrine, norepinephrine, and dopamine did not have a significant association with gingival index. Dental plaque and proximal decayed surfaces significantly affected gingivitis. Of the socioeconomic factors, mother's education had a significant association with gingivitis when all factors were included in the analysis. The data suggest that emotionally stressful states may not increase the probability of developing gingivitis in children of this age. J Periodontol 1998;69:554–560.
The Effect of Root Surface Demineralization on Bone Morphogenetic Protein‐2‐Induced Healing of Rat Periodontal Fenestration Defects
Authors: King Gaston N. , King Nicola , Hughes Francis J.
Published: March 2012

The purpose of this study was to investigate the effect of acid conditioning of root surfaces during recombinant human bone morphogenetic protein‐2 (rhBMP‐2) induced periodontal regeneration in vivo. The buccal aspect of molar roots were denuded of their periodontal ligament through a bony window created in the mandible of 34 Wistar rats under general anesthesia. Three groups of 11 or 12 animals received either 10 μL of 50 g/mL rhBMP‐2 in a collagen gel over the surgical defect (BMP) or 10 μL of collagen gel only (COL) or were left untreated (UN). Each of the 3 groups were further subdivided into those that received prior root acid conditioning with 35% phosphoric acid gel and those without acid conditioning. Animals were sacrificed 10 days after surgery and the tissues processed for histological examination. The BMP groups with and without acid conditioning developed significantly more bone over the second molar (3.89±0.86% and 7.62±0.93%, respectively; mean±SE), compared with the respective COL (1.24±0.26% and 2.77±0.52%) and UN groups (1.34±0.35% and 3.69±0.37%) (P <0.05). Furthermore, significantly more bone was found in the BMP non‐acid conditioned group compared with all other groups (P <0.05). Acid conditioning promoted significantly more ankylosis (50%) compared with non‐acid conditioning (6.3%) (P = 0.007). New cementum formation was greatest in the BMP acid conditioned group (628.4±253.8 ±m2) and lowest in the non‐acid conditioned UN group (207.6±36.4 μm2) (P <0.05). This is the first known report evaluating the effects of root acid conditioning after a single application of rhBMP‐2 in vivo. Results suggest that root conditioning agents operating at low pH administered into the periodontal wound impairs early BMP‐induced Osteogenesis while simultaneously promoting BMP‐induced cementogenesis. J Periodontol 1998;69:561–570.
Retention, Antimicrobial Activity, and Clinical Outcomes Following Use of a Bioerodible Tetracycline Gel in Moderate‐to‐Deep Periodontal Pockets
Authors: Needleman Ian G. , Gerlach Robert W. , Baker Robert A. , Damani Nalin C. , Smith Stuart R. , Smales Frederick C.
Published: March 2012

This randomized, examiner masked, split mouth study evaluated a new model to test periodontal therapy involving a novel bioerodible copolymer gel containing tetracycline hydrochloride. Responses to the tetracycline gel and untreated control were compared for product tolerance and 3 different measures of effectiveness (drug retention, changes in microbial levels, and clinical status). The test gel was administered by syringe into the periodontal pockets of 18 systemically healthy adult volunteers, each of whom presented with 3 or more sites with 6 mm probing depths. Gingival crevicular fluid samples were used to monitor daily drug levels over 7 days, while clinical responses were assessed at day 30. Overall, the test gel was well‐tolerated by all patients. For the 3 effectiveness measures, tetracycline was released throughout the observation period and mean levels exceeded 100 μg/mL over 6 days, statistically significant reductions in selected periodontal pathogens were evident at day 7 but not at day 30, and mean probing depth reductions at test sites were 1.12 mm at 30 days versus 0.36 mm at untreated control sites (P = 0.012). The safety profile, longer‐term drug retention, antimicrobial activity, and clinical response in this Phase I study suggest that this tetracycline‐containing copolymer gel platform may represent a safe and effective bioerodible therapy for periodontitis. The experimental model also shows merit for early phase clinical testing of novel therapeutic agents. J Periodontol 1998;69:578–583.
Reduction of Cyclosporine‐Induced Gingival Overgrowth Following a Change to Tacrolimus. A Case History Involving a Liver Transplant Patient
Authors: Bader G. , Lejeune S. , Messner M.
Published: March 2012

During immunosuppression with cyclosporine, gingival overgrowth, a minor secondary effect, may appear in the first weeks of treatment. In certain cases it may affect the function and/or esthetic appearance in a manner intolerable to the patient. A new immunnosuppressive molecule, tacrolimus, presently used as a treatment of second choice to control acute corticoresistant rejection, may bring oral comfort to these patients, since it reduces gingival overgrowth to negligible levels. J Periodontol 1998;69:729–732.
Pain Threshold Values During Periodontal Probing: Assessment of Maxillary Incisor and Molar Sites
Authors: Heins Paul J. , Karpinia Katherine A. , Maruniak Joyce W. , Moorhead Jaquelyn E. , Gibbs Charles H.
Published: March 2012

Probing pain threshold (PPT) assessments were conducted in the facial and oral sulci of maxillary central incisors and first molars of 10 periodontally healthy adults. All subjects were systemically healthy, free of pain, and reported no current medication usage. A computer‐linked electronic probe, modified to deliver steadily increasing forces up to 200 grams, was used to collect the data. The system contained a subject operated “off‐switch” which, upon activation, signaled the computer to record the subject's PPT Assessments of each subject's PPTs were conducted on 3 separate occasions at 7‐day intervals. Results indicated that the facial sulci of the incisors were the most pain sensitive. They displayed a mean PPT of 50.9 ± 26.6 grams. The oral sulci of the incisors exhibited a mean PPT of 76.5 ± 45.2 grams. Facial and oral sulci of the molars evidenced mean PPT values of 102.6 ± 52.1 grams and 113.5 ± 51.3 grams, respectively. These data suggest that sulci associated with incisor teeth are nearly twice as pain sensitive as sulci associated with molar teeth. In addition, facial sulci are significantly more pain sensitive than oral sulci. Data did not indicate a visit effect nor a side‐of‐mouth effect on PPT values. J Periodontol 1998;69:812–818.
Effect of Allogenic Freeze‐Dried Demineralized Bone Matrix on Guided Tissue Regeneration in Dogs
Authors: Caplanis Nicholas , Lee Michael B. , Zimmerman Grenith J. , Selvig Knut A. , Wikesjö Ulf M.E.
Published: March 2012

This randomized, split‐mouth study was designed to evaluate the adjunctive effect of allogenic, freeze‐dried, demineralized bone matrix (DBM) to guided tissue regeneration (GTR). Contralateral fenestration defects (6 × 4 mm) were created 6 mm apical to the buccal alveolar crest on maxillary canine teeth in 6 beagle dogs. DBM was implanted into one randomly selected fenestration defect. Expanded polytetrafluoroethylene (ePTFE) membranes were used to provide bilateral GTR. Tissue blocks including defects with overlying membranes and soft tissues were harvested following a four‐week healing interval and prepared for histometric analysis. Differences between GTR+DBM and GTR defects were evaluated using a paired t‐test (N = 6). DBM was discernible in all GTR+DBM defects with limited, if any, evidence of bone metabolic activity. Rather, the DBM particles appeared solidified within a dense connective tissue matrix, often in close contact to the instrumented root. There were no statistically significant differences between the GTR+DBM versus the GTR condition for any histometric parameter examined. Fenestration defect height averaged 3.7 ± 0.3 and 3.9 ± 0.3 mm, total bone regeneration 0.8 ± 0.6 and 1.5 ± 0.8 mm, and total cementum regeneration 2.0 ± 1.3 and 1.6 ± 1.7 mm for GTR+DBM and GTR defects, respectively. The histologic and histometric observations, in concert, suggest that allogenic freeze‐dried DBM has no adjunctive effect to GTR in periodontal fenestration defects over a four‐week healing interval. The critical findings were 1) the DBM particles remained, embedded in dense connective tissue without evidence of bone metabolic activity; and 2) limited and similar amounts of bone and cementum regeneration were observed for both the GTR+DBM and GTR defects. J Periodontol 1998;69:851–856.
Increased Presence of Interleukin‐6 (IL‐6) and IL‐8 Secreting Fibroblast Subpopulations in Adult Periodontitis
Authors: Dongari‐Bagtzoglou Anna I. , Ebersole Jeffrey L.
Published: March 2012

Periodontitis is a chronic inflammation of the supporting structures of the dentition which constitutes one of the most common causes of adult tooth loss. While certain microorganisms have been associated with the onset of the disease process, the exact pathogenetic mechanisms underlying periodontal destruction are still poorly understood. We have tested the hypothesis that gingival fibroblasts from diseased sites contribute to pathogenesis by possessing a secretory phenotype characterized by an exuberant secretion of inflammatory mediators and cytokines. Of the cytokines and mediators tested, fibroblast IL‐1β and prostaglandin E2 (PGE2) secretion was not different between health and disease. However, we have shown that fibroblasts from periodontal lesions produce in vitro greater amounts of IL‐6 and IL‐8 constitutively than healthy controls. When fibroblasts were stimulated with a panel of endogenous or exogenous response modifiers, the magnitude of cytokine and mediator stimulation above constitutive levels did not differ between health and disease. A strong positive correlation was identified between IL‐6 or IL‐8 constitutive secretion levels in vitro and the in situ expression of these cytokines within the connective tissues from where these cells originated, indicating that the in vitro phenotype mirrors their in vivo function. Furthermore, we present evidence which indicates that increased cytokine secretion by fibroblasts in disease is due to an elevated proportion of subpopulations with higher cytokine secretory capacity. Finally, we demonstrated that cultures from diseased sites are composed of cells with higher levels of constitutive CD40 expression, which may contribute to the increased IL‐6 and IL‐8 secretory phenotype. J Periodontol 1998;69:899–910.
A New Approach in Restorative Treatment of External Root Resorption. A Case Report
Authors: Dumfahrt Herbert , Moschén Ivano
Published: March 2012

This case report describes the treatment of an external root resorption with extensive loss of tooth structure and bone at the labial surface of an upper left central incisor. The area of bone loss and root resorption was surgically exposed and an impression was taken using curing silicone. An individual ceramic insert was fabricated, allowing endodontic retreatment through an artificial root canal. The insert was incorporated using a dentin bonding system and a dual curing luting composite. Following endodontic retreatment and internal bleaching, a ceramic veneer was bonded to the tooth to obtain good esthetics and to improve stability. Twenty months after surgical treatment no further root resorption could be detected radiographically. A shallow residual pocket but no bleeding on probing was found. J Periodontol 1998;69:941–947.
Preservation of Alveolar Bone in Extraction Sockets Using Bioabsorbable Membranes
Authors: Lekovic Vojislav , Camargo Paulo M. , Klokkevold Perry R. , Weinlaender Michael , Kenney E. Barrie , Dimitrijevic Bozidar , Nedic Melica
Published: March 2012

The purpose of this study was to evaluate the clinical effectiveness of a bioabsorbable membrane made of glycolide and lactide polymers in preserving alveolar ridges following tooth extraction using a surgical technique based on the principles of guided bone regeneration. Sixteen patients requiring extractions of 2 anterior teeth or bicuspids participated in the study (split‐mouth design). Following elevation of buccal and lingual full‐thickness flaps and extraction of teeth, experimental sites were covered with bioabsorbable membranes; control sites did not receive any membrane. Titanium pins served as fixed reference points for measurements. Flaps were advanced in order to achieve primary closure of the surgical wound. No membrane became exposed in the course of healing. Reentry surgeries were performed at 6 months. Results showed that experimental sites presented with significantly less loss of alveolar bone height, more internal socket bone fill, and less horizontal resorption of the alveolar bone ridge. This study suggests that treatment of extraction sockets with membranes made of glycolide and lactide polymers is valuable in preserving alveolar bone in extraction sockets and preventing alveolar ridge defects. J Periodontol 1998;69:1044–1049.
Acceptance Program Guidelines: Products and Methods for the Diagnosis and/or Management of Periodontitis
Authors:   Council on Scientific Affairs
Published: March 2012

Scope: These Guidelines apply to the design of clinical trials to evaluate products and methods which are intended to be used for the detection and diagnosis of periodontitis. The general purpose for such products and methods would be to assist in the identification of sites or subjects with existing periodontitis or, at increased risk of periodontitis, or for the development or progression of periodontitis. Clinical use of such diagnostics might occur: 1) during initial evaluation (screening, pre‐treatment risk assessment, diagnosis, treatment‐planning); 2) during treatment or management (monitoring therapeutic endpoints, identifying therapeutic targets); and 3) post‐treatment (establishment of recall intervals, early detection of recurrent disease). The specifics of clinical trial design for each of these related, but separate, clinical functions may differ depending on a variety of circumstances.
Periodontal Findings in Elderly Patients With Non‐Insulin Dependent Diabetes Mellitus
Authors: Collin Hanna‐Leena , Uusitupa Matti , Niskanen Leo , Kontturi‐Närhi Vuokko , Markkanen Heleena , Koivisto Anna‐Maija , Meurman Jukka H.
Published: March 2012

The periodontal status of 25 patients with non‐insulin dependent diabetes mellitus (NIDDM) (age range 58 to 76) was investigated and compared with 40 nondiabetic control subjects (age range 59 to 77). Surfaces with visible plaque and bleeding after probing, calculus, recessions, and pathological pockets were examined. The total attachment loss was calculated as a sum of recessions and pockets in millimeters. Mesial and distal bone loss was measured from panoramic radiographs and mean alveolar bone loss was calculated. Periodontal disease was considered advanced when mean alveolar bone loss was over 50%, or 2 or more teeth had pockets ≥6 mm. Microbiological analysis comprised the detection of Actinobacillus actinomycetemcomitans, Porphyromonas gingivalis, and Bacteroides forsythus by a Polymerase chain reaction (PCR) method. Patients with NIDDM had significantly more often advanced periodontitis than control subjects, 40.0% and 12.5%, respectively. Diabetic patients did not harbor more pathogens than the control subjects. The HbAIC level deteriorated in patients with advanced periodontitis, but not in other patients with NIDDM, when compared to the situation 2 to 3 years earlier. Advanced periodontitis seems to be associated with the impairment of the metabolic control in patients with NIDDM, and a regular periodontal surveillance is therefore necessary. J Periodontol 1998;69:962–966.
Relationship Between Conversion of Localized Juvenile Periodontitis‐Susceptible Children From Health to Disease and Actinobacillus actinomycetemcomitans Leukotoxin Promoter Structure
Authors: Bueno Lina C. , Mayer Marcia P.A. , DiRienzo Joseph M.
Published: March 2012

The periodontal pathogen Actinobacillus actinomycetemcomitans produces a leukotoxin that is considered a primary virulence factor in localized juvenile periodontitis (LJP). Select strains of the bacterium contain a 530‐bp deletion in the promoter region of the leukotoxin gene operon which results in enhanced transcription of the leukotoxin. DNA hybridization and polymerase chain reaction (PCR) were used to examine genetic variants of A. actinomycetemcomitans in 24 LJP‐susceptible children from 21 families having a history of the disease and 34 control children from non‐LJP families. A significant association was found between the detection of variants that had a deletion in the leukotoxin promoter region, indicative of a high level expression leukotoxin genotype, and conversion from a healthy periodontal status to disease. Subjects harboring A. actinomycetemcomitans of this genotype were more likely to convert to LJP than those subjects who had variants containing the full length leukotoxin promoter region (odds ratio = 22.50, 95% C.I.). These findings support the concept that highly virulent strains or clonai types of periodontal pathogens play a major role in the initiation of periodontal disease in susceptible hosts. J Periodontol 1998;69:998–1007.
Effects of Pore Structure to Electrical Properties in Tight Gas Reservoirs: An Experimental Study
Authors: Liu Xiao-Peng , Hu Xiao-Xin , Xiao Liang
Published: March 2012

The Archie’s equation lost its role in tight gas sands due to the complicated pore structure and strong heterogeneity. It’s a challenge to determine the input parameters in the Archie’s equation. In this paper, 36 core samples, which were drilled from tight gas sands in China, are chosen for resistivity and NMR laboratory measurements. Based on the experimental study of these core samples, the influence factors to electrical properties are concluded to reservoir porosity and the proportion of small pore components. When the porosity is higher than 25%, the relationship between the porosity and the formation factor illustrares a power function, this is coherent with the classical Archie’s equation. When the porosity is low, the statistic line of the porosity and the formation factor bend to the left. The relationship between the porosity and the formation factor is not a simple power function, the parameter of m is various and relevant to porosity. The relationship between the water saturation and the resistivity index is divergent, the saturation exponent n varies from 1.63 to 3.48. After analyzing the corresponding NMR laboratory measurement for the same core samples, an observation can be found that the saturation exponent is relevant to the proportion of small pore components. When core samples are dominant by the small core components, the corresponding saturation exponent is high, vice versa. To estimate reservoir initial water saturation accurately, the pore structure information must be considered.
Lessons from History - Unlocking a New UK Shale Oil Play
Authors: Roche Ian
Published: March 2012

The paper highlights how key results from historical exploration for conventional hydrocarbons, dating back over 70 years, led to the discovery of a new shale oil resource play in the UK.

Early conventional exploration in the West Lancashire sub-basin, conducted by D’Arcy Exploration, a forerunner of BP, was focussed on areas of surface seepage, and resulted in the discovery of the shallow Formby oilfield in 1939. In the late 1940s and early 1950s, a number of deeper wells were drilled, without success, targeting a proposed large Carboniferous conventional trap, leakage from which was thought to be source of the shallow accumulation.

Exploration of the offshore East Irish Sea Basin, in the 1970s to 1990s, resulted in numerous oil & gas discoveries in Triassic reservoirs, sourced directly from Visean-to Namurian-age pro-delta shale source rocks (including the Brigantian-to Pendleian-age Bowland Shale Formation) precluding the requirement for secondary migration from Carboniferous traps. Regional studies highlighting poor poroperm preservation in Carboniferous clastic reservoirs led to the further downgrading of Carboniferous prospectivity.

The recent identification of an unconventional shale gas play in the West Lancashire sub-basin by Cuadrilla Resources, within the Bowland Shale Formation, has led to a re-evaluation of the Formby area.

New palynological and geochemical analyses of the early wells, presented in this paper, confirm the presence of a thick, prospective, Bowland Shale in the south of the West Lancashire sub-basin. Evidence that, locally, the Bowland Shale has generated liquid hydrocarbons is proven by the presence of the Formby shallow oilfield and the numerous oil seeps and relict hydrocarbon columns in the area; opening up a new shale oil resource play.

The cumulative results from decades of exploration has revealed the true, unconventional, nature of the Carboniferous "mother lode" sought initially by D’Arcy, thereby heralding a new chapter in the hydrocarbon exploration of the basin.
Evaluation of Recovery Performance of Miscible Displacement and WAG Process in Tight Oil Formations
Authors: Ghaderi S. M. , Clarkson C. R. , Chen S.. , Kaviani D..
Published: March 2012

Recent advances in well design and production techniques have brought considerable attention to exploitation of tight (low permeability, absolute permeability <1 mD) oil resources. Drilling of long horizontal wells and deployment of hydraulic fractures along these wells (multi-fractured horizontal wells) can substantially improve the primary production rates from such reservoirs. Nevertheless, the low effective permeability of these reservoirs to oil hinders the sustainability of favorable oil rates and at some point applying some EOR technique becomes inevitable.

In the current study, CO2 miscible flooding and WAG process in a tight oil reservoir are investigated. Although several studies have investigated different aspects of the process in conventional oil plays, the design of an effective scheme in tight oil formations is more complex. These complexities are related to the proper design of the fractures (half-length, conductivity, orientation (transverse vs. longitudinal), etc.) and their relative placement along producers and injectors and the operational constraints on each well or segment of the well.

In this work, we utilize an EOR scheme design where multi-fractured horizontal wells are used for both injection and production, and the hydraulic fracturing stages are staggered to delay breakthrough and improve sweep efficiency. For a set of defined parameters, compositional simulations are conducted to investigate the effect of the CO2 slug size, WAG ratio and cycle length on the recovery efficiency of the model. The recovery from the aforementioned EOR process is then compared with its corresponding base case in which the reservoir has gone through periods of primary and water-flooding stages. The results of this study show that the incremental oil recovery from WAG process in tight formation can reach as high as 20%.
Water Management and Microbial Control Programs in the Exploitation of Unconventional Hydrocarbons
Authors: Van Der Kraan Geert M. , Keene Philip A. , James Malcolm , Yin Bei , Williams Terry M. , van Ruiten Otto P. , Love Donald J.
Published: March 2012

Worldwide, the production of natural gas and now oil from shale basins (source rock) has been embraced as a commercially viable way of producing unconventional energy resources leading to a revolution in gas production in the US. Developments to invest in and tap into this alternative way of gas production are taking off in Europe and Asia. Hydraulic fracturing is a proven technology, used for many years to develop hydrocarbon resources. Successful strategies with hydraulic fracturing include the safe and effective use of chemical additives, proper well casing and robust water management programs.

During the exploitation of hydrocarbons from shales, chemical additives such as corrosion inhibitors, gelling agents, biocides etc, have to be used in the fracturing of wells. Sustainable chemistries and effective product stewardship programs are required to minimize environmental and human exposure hazards. The addition of water with organic molecules to the actual fractured wells makes these environments subject to unwanted growth of microorganisms and biofilm development, which has detrimental effects on hydrocarbon flow and leads to pipeline/equipment corrosion. Often the presence of sulfate reducing microorganisms leads to unwanted H2S production and subsequently souring. Due to this, water cycle management and properly designed microbial control programs for all water sources including injected water or produced water, are required. Because the microbial challenges and environmental parameters of these water sources vary, different microbial control strategies and treatments are required for each source.

New formulations of biocides and control programs aimed at the needs of the gas and oil industry have been developed, e.g. improved heat stability and the reduction in biocide levels to achieve the same level of microbial control. These newly developed microbial control technologies will be presented in this paper, and the related regulatory and product stewardship support will be shortly addressed.
After a Decade of Microseismic Monitoring: Can We Evaluate Stimulation Effectiveness and Design Better Stimulations
Authors: Wuestefeld Andreas , Urbancic Ted , Baig Adam , Prince Marc
Published: March 2012

Over the past decade, microsesimic monitoring has become the approach most oftenused to gain an in-situ understanding of the rock’s response during hydraulic fracture stimulations. From initial monitoring performed in the Barnett Shale to monitoring currently being carried out for example in the Horn River and Marcellus formations, we review the evolution of microseismic monitoring from the viewpoint of data collection (single versus multi-well array configurations, utilization of long lateral stimulation wells), to data analysis, to the incorporation of microseismic parameters to constrain and validate reservoir models.

Generally, we have observed that overall fracture height, width and length, orientation, and growth vary from formation to formation and within each formation, thereby highlighting the ongoing necessity for microseismic monitoring. Additionally, through the use of advanced microseismic analysis techniques, such as Seismic Moment Tensor Inversion (SMTI), details on rupture mechanisms have been used to assess stimulation effectiveness, define complex Discrete Fracture Networks (DFN) and provide estimates of Enhanced Fluid Flow (EFF), which assist in calibrating and validating reservoir models. Utilizing spatial and temporal distributions in DFN and EFF, along with estimates of fracture interconnectivity and complexity, the role of pre-existing fractures and fault structures in the rock matrix can be established and used to provide more realistic estimates of stimulation parameters such as Stimulated Reservoir Volume (SRV).
New Hydraulic Fracturing Process Enables Far-Field Diversion in Unconventional Reservoirs
Authors: Mcneil Fraser , van Gijtenbeek Klaas , Van Domelen Mark
Published: March 2012

The challenge in recovering hydrocarbons from shale rock is its very low permeability, which requires cost-effective fracturestimulation treatments to make production economic. Technological advances and improved operational efficiency have made production from shale resources around the globe far more viable; however, while the wells being completed today are proving to be reasonably economical, the question that remains is if the operators are truly capitalizing on their full potential.

In recent years, the industry has been in search of a better method to enable well operators to capitalize on the natural fractures commonly found in shale reservoirs. If properly developed, these natural fractures will create a network of connectivity within the reservoir, potentially improving long-term production when they have been propagated. In most shales, however, the stress anisotropy present can prevent sufficient dilation of the natural fractures during stimulation treatments. To induce branch fracturing, far-field diversion must be achieved inside the fracture to overcome the stresses in the rock holding the natural fractures closed. Increasing net pressure during the treatment will enhance dilation of these natural fractures, creating a complex network of connectivity, and the greater the net pressure within the hydraulic fracture, the more fracture complexity created.

Most of the various processes introduced previously are limited because multiple perforated intervals or large open annular sections are treated at one time. Also, to achieve the high injection rates required, they are treated down the casing, so that any changes made to the treatment require an entire casing volume to be pumped before these changes reach the perforations. This paper presents a case history of a multistage-fracturing process that allows real-time changes to be made downhole in response to observed treating pressure. This functionality enables far-field reservoir diversion to be achieved, ultimately increasing stimulated reservoir contact (SRC).
Probabilistic Reserves and Resources Estimation: A Methodology for Aggregating Probabilistic Petroleum Reserves and Resources
Authors: Galvao M.. , Hastenreiter L.. , Molina J.. , Quadros A.. , Montechiari J.. , Hamacher S..
Published: March 2012

The oil industry strives to create an international standard for classification and estimation of resources since the 1930s. The goal is to provide investors with information obtained under the same assumptions, as to facilitate the comparison between petroleum companies. In 2007 the four major international organizations, Society of Petroleum Engineers (SPE), American Association of Petroleum Geologists (AAPG), World Petroleum Council (WPC) and Society of Petroleum Evaluation Engineers (SPEE), jointly released a single set of guidelines for classification and evaluation of oil and gas resources, the Petroleum Resources Management System (PRMS, 2007).

Several methodologies for estimating reserves can be employed within the PRMS’s (2007) premises, which can be classified as deterministic or probabilistic. Unconventional resources emerge as a new frontier for the oil industry, thus implying high uncertainty levels in both technical and economic assessments. The main purpose of this paper is to explore this issue and to propose a correlation-based probabilistic methodology for aggregating oil and gas reserves of conventional and unconventional resources. The methodology is in accordance with the guidelines of the PRMS (2007) and with the new rules of the Securities Exchange Commission 2009 (SEC). The correlation assessment evaluates technical and operational features, and the probabilistic aggregation is performed by Monte Carlo Simulation (MCS).

Besides the introductory section, this paper comprises four other sections. A literature review presents definitions of conventional and unconventional resources, and an examination of classification, estimation and aggregation of reserves, important for better understanding the following sections. The third section describes the proposed correlation-based probabilistic methodology. Afterward, a case study presents an application of the methodology. Finally, the last section synthesizes the main conclusions.