bluuebunny/crossref_metadata_2025 huggingface dataset:
Focal Epithelial Hyperplasia (Heck's Disease) With Generalized Lesions of the Gingiva. A Case Report
Authors: Morrow Dan J. , Sandhu Harinder S. , Daley Tom D.
Published: March 2012

Focal epithelial hyperplasia is an uncommon benign oral condition that occurs mainly in young individuals of certain racial groups. The lesions most commonly affect the mucosal surfaces of the lips and they have been observed frequently to regress within a few months. This is a report of an unusual case of focal epithelial hyperplasia in a young black adult presenting with generalized involvement of the gingiva. There is no clinical evidence of regression of the lesions and the case remains similar to the original appearance 2 years after diagnosis. The diagnosis and management of focal epithelial hyperplasia are discussed. J Periodontol 1993; 64:63–65.
Histologic Assessment of a Contiguous Autogenous Transplant in a Human Intrabony Defect. A Case Report
Authors: Zubery Yuval , Kozlovsky Avital , Tal Haim
Published: March 2012

Increased blood supply, vital bone marrow cells, and minimal mobility may play a significant role in the success of osseous grafts, and are characteristics of the bone swaging grafting technique. As in all autogenous grafts, the risk of disease transmission is minimal. Previous reports of clinical success raise questions as to the type of tissue response to this procedure. This case report examines 8 months radiographic and histologic results of a clinically successful bone swaging graft. J Periodontol 1993; 64:66– 71.
Guided Tissue Regeneration and Anti‐Infective Therapy in the Treatment of Class II Furcation Defects
Authors: Machtei Eli E. , Dunford Robert G. , Norderyd Ola M. , Zambon Joseph J. , Genco Robert J.
Published: March 2012

The purpose of the present study was to evaluate the effect of anti‐infective therapy on the success of periodontal regeneration in mandibular Class II furcation defects. Eighteen patients with mandibular bilateral Class II furcation defects were enrolled. Following an initial hygienic phase, guided tissue regeneration (GTR) was performed using an expanded polytetrafluoroethylene (e‐PTFE) membrane barrier. The area was surgically exposed, thoroughly root planed, and irrigated with either tetracycline (100 mg/ml) or 0.9% saline. Post‐operative care included systemic tetracycline (250 mg q.i.d.) and Chlorhexidine 0.12% mouthwash twice daily. Patients were maintained on a prophylaxis schedule of every 2 weeks for the first 3 months, and monthly thereafter. Clinical parameters of probing depth (PD), probing attachment level ‐ vertical (PAL‐v), probing attachment level ‐ horizontal (PAL‐h), and target periodontal pathogens were monitored at baseline and quarterly for one year. An overall improvement in all clinical parameters was observed in both groups: probing reduction (3.1 mm), PAL‐h gain (2.3 mm), and PAL‐v gain (1.2 mm) were all statistically significant compared to baseline measurements. Vertical measurements were performed parallel to the long axis of the tooth with no attempt to angulate the probe into the furcation. There was no significant difference in sites receiving tetracycline. A strong positive correlation was noted between initial PD and pocket reduction (r = 0.77, P < 0.0001) and between initial PD and PAL‐h gain (r = 0.54) and PAL‐v gain (r = 0.45) suggesting that initial probing depth might be used to assess the regenerative potential of a given site. PD and PAL have shown marked improvement as early as 6 months post‐operatively, but further improvement occurred over the 12 months of the study. Mean plaque indices were reduced to 0.5 with slight increases at 9 months, while gingival indices were steady at 0.5 through the year. Immunofluorescence demonstrated minimal infection with the target periodontal pathogens following surgery. Actinobacillus actinomycetemcomitans was detected in 5 sites during the monitoring phase and was associated with less favorable clinical results. This finding suggests that anti‐infective therapy and monitoring for A. actinomycetemcomitans and/or other periodontal pathogens might be useful in GTR therapy. J Periodontol 1993; 64: 968–973.
Measurements of Interleukin‐6 in Gingival Crevicular Fluid From Adults With Destructive Periodontal Disease
Authors: Geivelis M. , Turner D.W. , Pederson E. D. , Lamberts B.L.
Published: March 2012

This paper describes a study of whether or not the amounts of interleukin‐6 (IL‐6) in gingival crevicular fluid (GCF) are correlated with periodontal clinical measures. A sensitive ELISA was developed to measure IL‐6 in GCF. Two male and 3 female adult subjects with periodontal disease were examined at their first appointments, after 3 months, and after 6 months. Data were obtained on plaque index (PI), bleeding index (BI), probing depth (PD), and on the IL‐6 content of GCF samples from 16 sites per subject for a total of 240 measurements. Significant correlations were found between BI and IL‐6 (P < 0.005) and between PD and IL‐6 (P <0.05), but not between PI and IL6. Only 6 out of the 80 sites (in 3 of the 5 subjects) showed PD increases of at least 2 mm. However, for each of these 3 subjects, the amounts of IL‐6 in the GCF samples from these sites were markedly higher than the mean amounts of IL‐6 in the GCF samples from the remaining sites. These findings suggest that IL‐6 may be a useful indicator of periodontal disease, although more extensive longitudinal studies are needed to determine the real clinical value of this GCF component. J Periodontol 1993; 64:980–983.
The Clinical Effectiveness of Open Versus Closed Scaling and Root Planing on Multi‐Rooted Teeth
Authors: Wylam Jay M. , Mealey Brian L. , Mills Michael P. , Waldrop Thomas C. , Moskowicz Donald C.
Published: March 2012

Scaling and root planing are the most common techniques utilized to achieve a biologically‐acceptable root surface. Thorough root debridement is a demanding task, with residual deposits of plaque and calculus a not uncommon finding after instrumentation. This study evaluated the effectiveness of scaling and root planing via a closed versus an open flap approach. Sixty multi‐rooted teeth were assigned to one of three groups: untreated controls, closed scaling/root planing, and open flap scaling/root planing. Following debridement, teeth were extracted, immersed in methylene blue, and examined for the percent surface area having stainable residual deposits. The mean percent stained surface area covered by residual plaque and calculus was 54.3% in the closed root planing group compared to 33.0% in the open flap root planing group. The untreated control teeth had 91.0% of the root surface covered with stainable deposits. Within‐group comparisons showed no significant difference in the percent stained residual plaque and calculus in shallow areas of the pocket (≤3 mm apical to the gingival margin) compared to deeper areas (>3 mm subgingival). Examination of furcation regions demonstrated heavy residual stainable deposits for both treatment methods, with no significant differences between techniques. There was no correlation between the time spent in root debridement and the percent residual deposit area. The results demonstrate that hand instrumentation alone is inadequate for thorough debridement of furcations and suggest that new approaches are needed to provide a root surface which is compatible with formation of new periodontal attachment. High frequency ultrasonic instruments, rotary burs, and chemical agents may assist in debridement of such surfaces. Further evaluation of these and other novel approaches to root debridement are needed. J Periodontal 1993; 64:1023–1028.
Closure of Oroantral Communication Using Guided Tissue Regeneration and an Absorbable Gelatin Membrane
Authors: Waldrop Thomas C. , Semba Scott E.
Published: March 2012

Surgical intervention into the maxillary posterior area can lead to inadvertent communication with the maxillary sinus. Spontaneous healing of 1 to 2 mm openings can occur. However, in patients with larger oroantral communications and those with a history of sinus disease, surgical closure is often indicated. Acute and chronic oroantral fistula and sinusitis can occur as a result of inadequate treatment. The most common causes of complications include inadequate site preparation, flap closure, flap necrosis, infection, and patient non‐compliance. A technique for the closure of oroantral communications using guided tissue regeneration is described. This technique utilizes an absorbable gelatin film (membrane), allogenic bone graft material (DFDBA), and nonresorbable expanded polytetrafluoroethylene (ePTFE) membrane. The gelatin membrane prevents displacement of graft material into the antrum and sinus epithelial cell migration, while the ePTFE membrane promotes selective cell population with subsequent regeneration of the osseous wall of the oroantral defect. J Periodontol 1993; 64:1061–1066.
Self‐Reported Periodontal Disease in a Virginia Twin Population
Authors: Corey Linda A. , Nance Walter E. , Hofstede Patricia , Schenkein Harvey A.
Published: March 2012

To investigate the contribution of genetic factors in the etiology of periodontal disease, questionnaire data were collected on 4,908 twin pairs included in the populationbased Virginia Twin Registry. A history of periodontal disease was reported in 420 individuals who were members of 116 monozygotic (MZ) and 233 dizygotic (DZ) twin pairs. The mean age at diagnosis in this sample was 31.4±0.7 years and was significantly earlier in females than males (30.1 vs. 33.0 years, P <0.025). Proband‐wise concordance rates were 0.38 for MZ and 0.16 for DZ twins. There were no differences in concordance rate between same and opposite‐sexed dizygotic twins. These findings provide evidence that genetic factors make an important contribution to risk for adult‐onset periodontal disease. J Periodontol 1993;64:1205–1208.
Cloning and Characterization of Human Gingival and Periodontal Ligament Fibroblasts
Authors: Hou Lein‐Tuan , Yaeger James A.
Published: March 2012

Fibroblast heterogeneity in human periodontal tissues was characterized by cloning and immuno‐histochemical techniques. Cell suspensions from primary cultures gingival (GF) and PDL fibroblasts (PF) were cloned. The relative intensity of double‐labeled immunofluorescence, using specific antibodies to the extracellular matrix (ECM) molecules collagen type I (CI), type III (CIII), and fibronectin (Fn), was measured by photometry. Most clones derived from either GF or PF showed positive intracellular staining for both CI and Fn, and CIII and Fn. However, there were variations in fluorescence intensity for CI and Fn, ranging from relatively weak to strongly positive. The fluorescence for CI and CIII was relatively weak in most isolated GF clones in contrast to their PF clones. These observations coupled with studies of growth and cellular morphology in individual clones suggest that: 1) GF and PF contain functionally heterogeneous subpopulations; and 2) the synthesis and expression of extracellular matrix molecules of GF may be essentially different from that of PF. J Periodontol 1993;64:1209–1218.
Retention of Antimicrobial Activity by Human Root Surfaces after in Situ Subgingival Irrigation with Tetracycline HCl or Chlorhexidine
Authors: Stabholz Ayala , Kettering James , Aprecio Raydolfo , Zimmerman Grenith , Baker Pamela J. , Wikesjö Ulf M. E.
Published: March 2012

Substantivity of tetracycline HCl and Chlorhexidine digluconate was assessed in extracted teeth. Fifty periodontally compromised teeth scheduled for extraction with probing depths ranging between 6 and 12 mm were root planed and then irrigated in situ with 1 of 4 solutions: tetracycline HCl at concentrations of 10 or 50 mg/ml, 0.12% Chlorhexidine digluconate, or 0.9% sterile saline. Each tooth was exposed to 150 ml of the respective irrigation solution. Following extractions, the teeth were transferred to tris buffered saline and incubated at room temperature for 22 days. Incubation solutions were replaced at 24‐hour intervals. Removed solutions were examined for desorbed antimicrobial activity using a microtiter assay in which bacterial growth was evaluated by optical density readings. Tetracycline HCl 50 mg/ml exhibited significantly greater antimicrobial activity than Chlorhexidine digluconate for 12 days and greater than saline for 16 days. Tetracycline HCl 10 mg/ml exhibited significantly greater antimicrobial activity than Chlorhexidine digluconate and saline for 4 days. Chlorhexidine digluconate did not exhibit any significant antimicrobial activity at any time point. Our findings demonstrate longlasting substantivity of tetracycline HCl, but not Chlorhexidine digluconate, by teeth exposed to a single episode of pocket irrigation of their periodontally‐exposed roots. The amount of antimicrobial activity retained is proportional to the concentration of tetracycline HCl used for irrigation. J Periodontol 1993; 64:137–141.
Occurrence and Resolution of Focal Epithelial Hyperplasia in Two Siblings With Leukocyte Adhesion Deficiency
Authors: Mealey Brian L. , Hallmon William W. , Waldrop Thomas C.
Published: March 2012

Focal epithelial hyperplasia is an uncommon disorder characterized by formation of multiple asymptomatic oral mucosal papular and/or nodular lesions. This article relates the occurrence and clinical course of FEH in 2 adolescent siblings with leukocyte adhesion deficiency. Histological findings are described and insights into potential causes are discussed. J Periodontol 1993; 64:149–152.
Glycosaminoglycans and Periodontal Disease: Analysis of GCF by Safranin O
Authors: Giannobile William V. , Riviere George R. , Gorski Jeffrey P. , Tira Daniel E. , Cobb Charles M.
Published: March 2012

The purpose of this study was to quantify glycosaminoglycans (GAG) released into the gingival crevicular fluid (GCF) during health, gingivitis, and adult periodontitis. The investigation tested the hypothesis that increased amounts of GAG can be measured in GCF associated with gingivitis and adult periodontitis as compared to health. An individual patient's sampling sites were assigned to either a health (control) group or 1 of 3 experimental groups, gingivitis, periodontal “maintenance” (perio‐M), or periodontal “non‐maintenance” (perio‐NM) according to standard clinical criteria of pocket probing depth, bleeding on probing, and radiographic evidence of bone loss. The perio‐M group was defined as a periodontal patient who had received a dental prophylaxis and/or root planing within 6 months prior to GCF collection. The perio‐NM group had received no periodontal therapy during the previous 6 months. Subsequent to air‐drying and isolation, GCF was collected by a microcapillary pipette held at the gingival margin. All fluid samples were digested overnight at 37°C with 25 μg of papain and analyzed for GAG content using a chondroitin‐4‐sulfate standard. Data generated from safranin “O” dye binding assays of GAG revealed 4.41 ± 9.82 ng GAG from the health (control) group (n = 23); the gingivitis group (n = 13) showed 15.23 ± 11.85 ng GAG/sample; perio‐M group (n = 11) showed 23.64 ± 12.98 ng GAG/sample and the perio‐NM group (n = 12) exhibited 119.08 ± 33.14 ng GAG/sample. Using Dunn's multiple comparison procedure, statistically significant differences were found between the perio‐NM and health groups; perio‐M and perio‐NM; and perio‐NM and gingivitis groups at P <0.01 while significance at P<0.05 was found between health and perio‐M groups. However, no significant differences were observed between gingivitis and health groups or gingivitis and perio‐M groups. The safranin “O” assay method may be a useful indicator of osseous and connective tissue changes within the periodontium. J Periodontol 1993;64:186–190.
Fructosamine as a Possible Monitoring Parameter in Non‐Insulin Dependent Diabetes Mellitus Patients With Periodontal Disease
Authors: Unal Tahsin , Firatli Erhan , Sivas Ahmet , Meric Hasan , Oz Hikmet
Published: March 2012

Fructosamine assay is a new test used in the diagnosis and monitoring of diabetic patients. This assay may be of interest to the periodontist for, while the traditional plasma glucose value would give a general view and information about diabetic control at a certain point, the fructosamine concentration gives an indication of the plasma glucose level over a considerable period of time, such as 1 to 3 weeks. We investigated whether there was any relation between the diseased state of the periodontal tissues and plasma fructosamine and the plasma glucose values in non‐insulin dependent diabetes mellitus (NIDDM) patients. We found that fructosamine correlated with the degree of gingival bleeding, however serum glucose levels had little or no correlation. J Periodontol 1993;64:191–194.
Periodontal Regeneration of Human Infrabony Defects. III. Diagnostic Strategies to Detect Bone Gain
Authors: Tonetti Maurizio S. , Prato Giovanpaolo Pini , Williams Ray C. , Cortellini Pierpaolo
Published: March 2012

Assessment of actual treatment outcome by simple and available diagnostic tests represents an important aspect in the evaluation of periodontal regenerative procedures. This report focuses on the diagnostic accuracy of different strategies to detect the original extent of bone loss and bone gain in deep vertical defects following guided tissue regeneration. Characteristics of probing attachment level and radiographic bone linear measurements were compared to a gold standard obtained as intrasurgical clinical measurements at baseline and at the 1 year re‐entry operation. Radiographic linear measurements underestimated bone loss (CEJ‐BD) in 55% of cases while the estimate was within 1 mm in 25% of cases. The goodness of agreement could be significantly described by a general linear model incorporating measures of defect morphology. The original level of bone loss could be best detected by an approach which consisted of adding 1.5 mm to the measured attachment level loss. Such an approach correctly estimated bone loss within 1 mm in 85% of sites. In terms of ability to detect bone gain, radiographic measurements underestimated bone gain in 55% and overestimated it in 15% of sites. Diagnostic accuracy was assessed at different threshold values of true gain. The sensitivity and specificity plots intersected at a threshold value of 2.7 mm bone gain. Conversely, measures of probing attachment level gain agreed with the gold standard within 1 mm 45% of times. Intersection of the specificity and sensitivity plots occurred at 3 mm. Classification tables are presented for both diagnostic tests at different threshold values. The best results to detect true bone gain were obtained employing a strategy consisting of the agreement of the radiographic and attachment level measurements. When such agreement was observed (70 to 85% of the observations) the overall diagnostic accuracy approached 100%. The significance of the findings and their clinical applicability in the assessment of actual treatment outcome following GTR procedures in deep vertical defects are discussed. J Periodontol 1993; 64:269–277.
In Vitro Attachment of Human Gingival Fibroblasts to Endosseous Implant Materials
Authors: Guy S.C. , McQuade M.J. , Scheidt M.J. , McPherson J.C. , Rossmann J.A. , Van Dyke T.E.
Published: March 2012

In recent years, the focus of dental implant research has been the nature of the boneimplant interface associated with osseointegration, yet the transgingival portion of endosseous dental implants has received little attention. The purpose of this study was to determine the attachment of human gingival fibroblasts to three different implant materials: commercially pure titanium, non‐porous hydroxyapatite, and porous hydroxyapatite. Cell attachment was quantified by radiolabeling gingival fibroblasts with tritiated thymidine and counting attached cells by liquid scintillation following incubation for periods of 20, 40, and 60 minutes. Additional studies coating implant surfaces with fibronectin were also performed. The nature of the implant material itself appeared to affect the number of attached cells. Determined on a surface area basis, fibroblast attachment was greatest to titanium followed by non‐porous hydroxyapatite. Porous hydroxyapatite demonstrated the least amount of fibroblast attachment. When incubated with fibronectin at a concentration of 50 μg/ml, no increase in the number of cells attached to the various implant materials was observed. A small but statistically significant increase in the number of fibroblasts attached to porous hydroxyapatite at 40 minutes was observed when implant materials were pre‐treated with fibronectin. J Periodontol 1993;64:542–546.
Periodontal Disease in Three Siblings With Familial Neutropenia
Authors: Kirstilä Varpuleena , Sewón Lüsi , Laine Juhani
Published: March 2012

The periodontal status and treatment of three teenagers in a Finnish family with familial neutropenia is described. The mother was also diagnosed with neutropenia. At initial examination, the 15‐year‐old male and the 10‐year‐old female had severe periodontitis, whereas the 13‐year‐old male had oral ulcerations but no significant periodontal disease. The two siblings with periodontitis were treated and followed approximately 5 years. It was concluded that periodontal therapy including scaling, surgery, and use of antimicrobial agents can be successful in patients with familial neutropenia, and that such patients are not necessarily candidates for full mouth extraction. The role of granulocyte colony‐stimulating factor in which was used in the treatment of these patients remains to be established. J Periodontol 1993;64:566–570.
Pain and Discomfort Levels in Patients During Root Surface Debridement With Sonic Metal or Plastic Inserts
Authors: Grant Danielle A. , Lie Tryggve , Clark Stephen M. , Adams Donald F.
Published: March 2012

The study was designed to evaluate whether root surface debridement with a sonic sealer plastic insert would cause less pain and discomfort to patients than an ordinary, probe‐shaped metal sonic insert. One quadrant in each of 23 patients was debrided with each insert. Blood pressure, mean arterial pressure, and heart rate were monitored before, during, and immediately after each treatment. Pain was also evaluated on a visual analogue scale (VAS) after each treatment, as well as 2 weeks later following pain‐provoking stimuli. Blood pressure, mean arterial pressure, and heart rate did not reveal any differences between quadrants treated with plastic or metal inserts. Heart rate had a weak, positive association with treatment time. The VAS gave a higher pain score for the plastic (30.8) than for the metal insert (24.4), but this difference was not statistically significant (P = 0.055). Following pain‐provoking stimuli at the 2‐week follow‐up visit, quadrants debrided with the metal insert (31.3) scored significantly lower (less pain) (P <0.01) on the VAS than quadrants treated with the plastic insert (30.7). It is concluded that the sonic metal insert caused less pain and discomfort to the patients due to its superior accessibility and water spray cooling. The significant difference between metal and plastic tip debrided quadrants at the follow‐up visit was probably caused by the smearing effect of the metal insert with partial closure of the dentin tubule orifices. J Periodontol 1993; 64:645–650.
The Effect of Nicotine on Reproduction and Attachment of Human Gingival Fibroblasts In Vitro
Authors: Peacock Mark E. , Sutherland Donald E. , Schuster George S. , Brennan William A. , O'Neal Robert B. , Strong Scott L. , Van Dyke Thomas E.
Published: March 2012

The ability of fibroblasts to reproduce and attach to teeth is of paramount importance in re‐establishing the lost connective tissue attachment after periodontal therapy. This study examined the effect of nicotine, a major component of the particulate phase of tobacco smoke, on human gingival fibroblast (HGF) reproduction and attachment to tissue culture surfaces. Pooled HGF cultures made from expiants of gingival biopsies were utilized between passages 5 and 10 and plated in 96‐well plates at 1.0 × 104 cells per well. Cell numbers were determined using 3‐(4,5‐dimethylthiazol‐2‐y)‐2,5‐diphenyl tetrazolium bromide (MTT), which is a reflection of mitochondrial dehydrogenase activity. The concentrations of nicotine used were 0.025, 0.05, 0.1, 0.2, and 0.4 μM, the average serum concentration for a smoker being approximately 0.1 μM. The effect of continuous nicotine exposure on HGF reproduction was determined by incubating cell cultures and media containing nicotine for up to 48 hours. Residual toxicity was determined by preincubating cells with nicotine for 1 or 6 hours. HGF suspensions and increasing concentrations of nicotine were added together to determine the effect on attachment. Results showed an enhanced effect of nicotine on HGF attachment, with increasing numbers of cells attaching with increasing nicotine concentrations, compared to the control. Low concentrations of nicotine had a stimulatory effect on cell replication, while higher concentrations of nicotine appear to have no significant effect on HGF reproduction. The responses of cells to some concentrations of nicotine may persist after its removal. J Periodontol 1993;64:658–665.
Surgical Treatment of Intrabony Periodontal Defects Using Expanded Polytetrafluoroethylene Barrier Membranes: Influence of Defect Configuration on Healing Response
Authors: Selvig Knut A. , Kersten Betty G. , Wikesjö Ulf M.E.
Published: March 2012

Twenty‐six proximal, intrabony periodontal defects with probing depths equal to or exceeding 6 mm in 23 patients were treated with gingival flap surgery supported by an expanded polytetrafluoroethylene barrier membrane. The material included 1, 2, and 3‐wall defects with crestal involvement relative to the root circumference ranging between 90° and 270°. Healing was evaluated clinically 12 months after surgery. Deep defects exhibited greater probing depth reduction and attachment gain than shallower defects. Probing depth reduction, attachment gain, and bone fill were positively correlated to the depth of the 3‐wall intrabony component of the defect. The extent of crestal involvement, and wall form in the fundus of the defect did not appear to influence the healing response. The treatment also affected the proximal surface of the defect‐adjacent tooth, which showed some reduction in bone level as well as gingival recession. Thus, the overall healing pattern following barrier membrane‐supported flap surgery appears similar to that generally observed for conventional reconstructive flap surgery in intrabony periodontal defects. J Periodontol 1993; 64:730–733.
Prevalence of Periodontal Disease in a Health Maintenance Organization and Comparisons to the National Survey of Oral Health
Authors: Stoltenberg Jill L. , Osborn Joy B. , Pihlstrom Bruce L. , Hardie Nancy A. , Aeppli Dorothee M. , Huso Beverly A. , Bakdash M. Bashar , Fischer George E.
Published: March 2012

The purposes of this study were to 1) characterize the demographics, oral health behavior, and periodontal status of a health maintenance organization sample; 2) investigate the relationship between the location of posterior proximal measurement sites and prevalence estimates for periodontal disease; and 3) compare the prevalence of persons with pockets ≥ 4 mm in the present sample to the 1985 NIDR Survey of Oral Health. The sample consisted of 1,090 adults attending a large health maintenance organization. All proximal sites in one randomly selected posterior dental sextant were examined for probing depth using a constant force probe. Demographic, medical, and behavioral factors were determined by questionnaire. Results indicated that the sample consisted primarily of medically and periodontally‐healthy middle‐aged adults with good oral hygiene habits. Overall, the mean probing depth was 2.95 mm with 10.1% of sites/subject ≥ 4 mm. A larger percent of subjects had probing depths with pockets ≥ 4 mm at lingual proximal sites than buccal proximal sites. Prevalence of subjects with pockets ≥ 4 mm at mesio‐buccal sites in the present study was similar to NIDR Region III data (15.3% vs. 17.4% respectively). However, when data from all posterior sites were included, the overall prevalence rate in the present sample increased to 36.8%. These findings indicate that disease prevalence is dependent on the location of surfaces measured and conservatively indicate that NIDR survey data may have underestimated the prevalence of persons with periodontal pockets ≥ 4 mm by at least 20%. J Periodontol 1993; 64:853–858.
Phase Behavior and Viscosity Measurements of Heavy Crude Oil With Methane and Ethane at High-Temperature Conditions
Authors: Kariznovi Mohammad , Nourozieh Hossein , Abedi Jalal
Published: March 2012

Heavy oil and extra heavy oil reserves have attracted increasing attention in recent years as alternatives to conventional oil reservoirs. Over the last two decades, new techniques have been developed to take advantage of solvent and heat in heavy oil recovery. In these methods, referred to as solvent/heat-assisted recovery processes, the compound effects of solvent and heat on the bitumen viscosity may provide bitumen production rates that may be equivalent or even higher than those from the injection of steam or solvent alone.

Experimental data on the phase behavior of heavy oil / solvent systems and their physical properties are essential for the design and optimization of such processes. The plain fact is the lack of data at the high-temperature conditions approaching those of in situ steam injection.

In the present study, the solubilities, saturated phase densities and viscosities for methane and ethane in extra heavy oil were measured for a temperature range of 50 to 190°C and pressures up to 8 MPa. These temperatures and pressures cover the conditions of the in situ steam processes.

The experimental results indicate that the reductions of the saturated viscosity and density with pressure at high-temperature conditions were not as significant as those at low temperatures for both solvents. However, equilibration time was reduced significantly, and the application of these processes in the field has become practical. The saturated viscosity data versus pressure showed a linear trend at high temperatures and a nonlinear reduction at low temperatures. Furthermore, ethane had a higher viscosity reduction than methane at all conditions. This difference was more significant at lower temperatures. The gas solubility data for all cases demonstrated a linear increase with pressure at different temperatures.
Production Performance Diagnostics Using Field Production Data and Analytical Models: Method and Case Study for the Hydraulically Fractured South Belridge Diatomite
Authors: Yang Zhengming
Published: March 2012

Oil and water production data are regularly measured in oil field operations and vary from well to well and change with time. Theoretical models are often used to establish the production expectation for different recovery processes. A performance surveillance understanding can be developed by comparing the field production data with the production expectation. This comparison generates quantitative or qualitative signals to determine if the producer meets production expectation or if the producer is underperforming and appropriate operational action is required to address the underperformance.

The case study is for the South Belridge diatomite in California. This hydraulically fractured diatomite reservoir is currently under waterflood and steamflood. A methodology is proposed to establish the production expectation from historical production data. For primary depletion, the formation linear and bilinear flow models are applied to producers with vertical hydraulic fractures. For waterflood, an analytical method based on Buckley-Leveret displacement theory is used. Those analytical methods can predict production and provide surveillance signals for producers in the primary and waterflood recovery stages. For steamflood, a semi-quantitative performance surveillance criterion is proposed based on understanding the mechanistic oil banking concept and reservoir simulation results for steamflood and waterflood. With those models representing expected production performance, an integrated flow regime diagram is proposed for the purpose of production surveillance. A performance expectation can be developed for an individual producer. A significant over-performance relative to the expectation normally indicates changes in the recovery mechanism or improvement in sweep efficiency. A significant under-performance usually signifies an operational issue that requires correction in order to optimize the production performance.

In the case study, the surveillance methodology for producers under primary depletion, waterflood, steamflood are demonstrated using historical production data. In addition, water channeling between injectors and producers and its impact on production performance is discussed. Based on this surveillance methodology, some operational actions were proposed and successful results are demonstrated. Examples of forecast for individual producer in primary depletion stage and field scale prediction in waterflood stage are provided. Application indicates that the proposed methodology can serve as a convenient and practical tool for reservoir surveillance and operational optimization.
A New Screening Tool for Improved Oil Recovery Methods Using Artificial Neural Networks
Authors: Parada C. H. , Ertekin T.
Published: March 2012

In more recent years, improved oil recovery (IOR) techniques are applied to reservoirs even before their natural energy drive is exhausted by primary depletion. Screening criteria for IOR methods are used to select the appropriate recovery technique in view of the reservoir characteristics. However, further reservoir appraisal is necessary after the applicable recovery technique is identified. The methodology proposed in this paper allows the preliminary evaluation of reservoir performance in parallel with the IOR screening process.

In this study, artificial neural network (ANN) methodology is used to build a high-performance neuro-simulation tool for screening IOR methods such as waterflooding, steam injection and miscible injection of CO2 and N2. This innovative tool integrates the field development plan into the screening method. The reservoir characteristics are evaluated together with a proposed production scenario to assess the most suitable recovery process and, at the same time, the reservoir performance is forecasted by providing the estimated oil production curve.

The screening toolbox consists of proxy models that implement a multilayer cascade feedforward back propagation artificial network algorithm. The proxy models work for a diverse range of reservoir fluids and rock properties. The field development plan is featured in the tool by different well patterns, well spacing and well operating conditions. The ANN screening tool predicts oil production rate, cumulative oil production and estimated production time. The tool also provides the flexibility to compare the hydrocarbon production for different sets of inputs, which facilitates comparison of various depletion strategies in the screening process as well.

The results of this study show that the networks are able to recognize the strong correlation between the displacement mechanism and the reservoir characteristics as they effectively forecast hydrocarbon production for different reservoirs. The tool presents a new means to design an efficient and feasible IOR project by using artificial intelligence. The proposed tool facilitates the appraisal of diverse field development strategies for oil reservoirs and allows comparison of reservoir performance under diverse production schemes.
Visualization Grammar: A Phrase-Based Reservoir Information Visualization System
Authors: Gao Zhenzhen , Nocera Luciano , Neumann Ulrich
Published: March 2012

Existing data query and visualization software capable of creating reservoir data visualizations are targeted at expert users and have a high learning curve. Also reservoir data are not usually universally accessible through a unified interface. In this paper we introduce a system called Visualization Grammar (VG) that allows users to generate compelling visualizations from large volumes of structured multi-dimensional reservoir data. VG can be easily deployed and requires virtually no train-ing from end-users.

VG's goal is to create an intuitive and interactive visualization tool aimed at users of the petroleum industry with little or no expertise in data query and graphic design. These visualizations can in turn be used to analyze the ever growing volume of reservoir data.

We describe VG's portable and intuitive user interface and its architecture and provide implementation details. Our results show how VG supports data access and abstraction, visualization query formulation and editing and automatic visua-lization generation. Phrases built by VG provide with a unified and universally intelligible representation that can support collaboration and help managing complex visualization requirements across domains of expertise. We show text, 2D and 3D visualization examples including volume renderings of reservoir data. Collaborative features further improve its usefulness for interdisciplinary data analysis. Consequently VG represents a unified data visualization interface that can be greatly bene-ficial to the petroleum industry.

The VG system provides the following benefits. (1) The user interface is simple and intuitive requires virtually no training. It relies on a natural language formulation supported by a step-by-step visual guidance where the user is presented with valid data and visualization alternatives that are dynamically changing within the context. (2) A volume rendering ex-tension module with a GPU implementation provides interactive performance and improved perception. (3) VG's architecture is scalable and extensible providing access to a heterogeneous set of data sources. VG's visualizations therefore have the po-tential to greatly improve inter-domain collaboration and data analysis in the enterprise.
A Saturation Height Function Model Derived From Capillary Pressure, Lower Etchegoin/Williamson Reservoir, Lost Hills Field
Authors: Lalicata Joseph J. , Tanis Elizabeth A. , Reed Daniel A. , Zannitto Peter J.
Published: March 2012

Fluid flow in light, tight oil (LTO) reservoirs is by nature capillary-force dominated, as opposed to viscous-force dominated. However, most LTO reservoir models rely solely on well-log data to initialize volumes of original hydrocarbons in place, ignoring the physics of capillarity. This reliance on well logs owes to the difficulty of generating accurate, core-derived saturation height function models (SHFM). Moreover, when initializing reservoir saturation distributions to drainage capillary pressure curves, the resulting dynamic model must then obey matrix fluid transport, which is governed by oil-water capillary pressure relationships. This often creates difficulty in the history matching process for numerical simulation models that must honor production data. A contradictory approximation of "zero capillary pressure" is often made for simplification.

We successfully constructed a core-derived SHFM and matrix permeability model for the Lower Etchegoin/Williamson reservoir at the Lost Hills field, California. This unconventional reservoir contains light oil (20 to 25° API) with low matrix permeability (0.05 to 10 md). The SHFM and matrix permeability models were constructed using routine and special core analyses from three wells that were cored and logged. High pressure mercury injection (HPMI) capillary pressure measurements were acquired on 16 core-plugs taken across the three main reservoir zones. From capillary pressure analyses, a Williamson SHFM was generated based on best-fits of irreducible water saturation, capillary entry-pressure, Brooks-Corey exponent, and permeability/porosity combinations. A single free water level (FWL) parameter was tuned in the SHFM at each of the well locations to force a match with the resistivity-derived saturation profiles. An excellent match of the saturation profile for the three wells was achieved.

Unexpectedly, the Williamson SHFM has also proven useful in identifying the presence of geologic faults, independent of logs and seismic. When the capillary pressure model was applied to step-out areas, requiring a ‘depth offset’ correction to maintain a constant FWL across fault blocks (relative to the main reservoir block FWL), it was successfully hypothesized that faulting was present. The ‘depth offset’ correction represents the overall vertical fault displacement between reservoir blocks.
What Every Engineer Should Know About Vacuum Insulated Tubing
Authors: Lombard Michael S.
Published: March 2012

The Petroleum Engineer assigned to the task of designing a thermal well completion using insulated tubing will have a number of questions such as: What is the thermal conductivity value?What is the thermal performance, heat loss per foot or meter of length?What are the mechanical properties and limitations of the insulated string?What are my connection options?What is the price?

While these are very specific requests the answers may not be the answers that lead the engineer to the best purchase decision. A certain level of knowledge about high vacuum multilayer insulation systems should be known before the Petroleum Engineer specifies and purchases an insulated tubing string.

Once it’s decided a steam injection program will benefit from the use of insulated tubing and before the purchase decision is made, it’s important that the buyer understand technical matters concerning the type insulating systems that will be installed. This paper attempts to create a level of technical transparency and provide the engineer with a few tools that can be used to evaluate the various manufacturers and technologies.

Multilayered insulated steam injection tubing was introduced in the late 1970’s by General Electric Company finding immediate acceptance as a means to lower steam costs, solve wellbore issues, and improve steam oil ratios. The first insulated tubing consisted of an Argon gas backfilled insulating system having thermal conductivity values in the range of 0.015 Btu/Hr-Ft-°F (0.026 w/mK). A flurry of activities on the part of oil producers and manufacturers lead to the introduction of Vacuum Insulated Tubing (VIT) in 1983, by Babcock & Wilcox Company (Ayres, 1982). This multilayer and gettered high vacuum insulated tubing systems (VIT) offered substantially improved thermal performance having conductivity values in the range of 0.0018-0.0023 Btu/Hr-Ft-°F (0.003-0.004 w/mK).

Ayres, (1982). Patent No. 4,512,721. USA, Ohio.
Field Trials Using an All Metal Ring Seal Floating Packer
Authors: Lombard Michael S. , Townsend Thomas , Ramirez Enrique , Zambrano Mauricio , Ricardo Jesus , Vargas Leonel , Albornoz Jose Francisco , Cardona Marcela Arteage
Published: March 2012

The Ring Seal Floating Packer is a simple and low cost sealing device for use in steam injection wells and is proven to be an effective mechanical device for controlling and blocking the passage of fluids in an annular space between the tubing and casing. The Ring Seal Packer can be compared to a piston in a cylinder: Pressure forces acting upon a piston result in up and down motion while the piston maintains a seal against the cylinder (casing) wall. Compared to a conventional thermal packer, the Ring Seal Packer does not require an expansion joint allowing the injection tubing to thermally expand and contract while the Ring Seal Packer moves up and down the casing maintaining its sealing ability.

This paper covers the following areas: Mechanical DesignLaboratory testing providing loading confirmation for deployment.Field results at PEMEX Samaria oil field, Mexico, Cyclic Steam Stimulation (CSS)California field results of CSS into vertical wells with multiple zones above and below the RSP.Field results at Mansarovar, Colombia.ConclusionReferences
Measuring the performance of water service providers in urban India: implications for managing water utilities
Authors: Gupta Shreekant , Kumar Surender , Sarangi Gopal K.
Published: March 2012

This study assesses the efficiency of the urban water supply system in 27 selected Indian cities. It applies data envelopment analysis (DEA) as an analytical tool to measure technical efficiency. Cities are categorized into different groups according to the management structure of their water utilities. The results show that within groups, the utilities that are managed by ‘municipal corporations (MCs) and parastatals', with a certain amount of functional autonomy, perform better in comparison to the group ‘MCs and government’ and thus, strengthen the hypothesis that functional autonomy in management leads to better performance of the water utilities. Moreover, the results also have implications for urban domestic water pricing. We find that most water utilities are operating under decreasing returns to scale (DRS), implying that water should be priced at a marginal cost of supply.
Cost of providing sustainable water, sanitation and hygiene (WASH) services: an initial assessment of a life-cycle cost approach (LCCA) in rural Andhra Pradesh, India
Authors: Reddy V. Ratna , Batchelor Charles
Published: March 2012

Water, sanitation and hygiene (WASH) service levels remain stubbornly low in rural India despite high levels of public expenditure recently. In many areas, this is because service levels have slipped back for reasons including inadequate protection of water sources (quantity and quality) and more attention given to capital expenditure than expenditure on operational and capital maintenance. This paper argues that adoption of a life-cycle cost approach (LCCA) could play a significant role in rectifying this by providing a framework for identifying and plugging gaps in the present pattern of expenditure. It is argued that LCCA will provide a sound basis for implementing the WASH Guidelines released by the Rajiv Gandhi National Drinking Water Mission in 2010. These guidelines signal a shift away from viewing the provision of WASH services as primarily an engineering challenge to one that requires activities that include source protection, institution building and long-term support and pro-poor planning, all of which need to be budgeted for by WASH service providers and/or users. Preliminary findings indicate that LCCA can be used to assess actual life-cycle costs of sustainable, equitable and efficient WASH service delivery. The challenge now is to investigate how best LCCA can be mainstreamed into WASH planning and other governance processes.
Growing more food with less water: how can revitalizing Asia's irrigation help?
Authors: Mukherji Aditi , Facon Thierry , de Fraiture Charlotte , Molden David , Chartres Colin
Published: March 2012

Asia accounts for 70% of the world's irrigated area and is home to some of the oldest and largest irrigation schemes. While these irrigation schemes played an important role in ensuring food security for billions of people in the past, their current state of affairs leaves much to be desired. This paper takes forward the IWMI–FAO–ADB (Asian Development Bank) recommendation of a five-pronged approach for revitalizing Asia's irrigation and provides a region-specific road map for doing this. The underlying principle of these multiple strategies is the belief that the public institutions at the heart of irrigation management in Asia need to give up comfortable rigidity and engage with individual users' needs and the demands placed by larger societal changes.