bluuebunny/crossref_metadata_2025 huggingface dataset:
Multi‐Center Clinical Evaluation of Combination Anorganic Bovine‐Derived Hydroxyapatite Matrix (ABM)/Cell Binding Peptide (P‐15) as a Bone Replacement Graft Material in Human Periodontal Osseous Defects. 6‐Month Results
Authors: Yukna Raymond A. , Callan Donald P. , Krauser Jack T. , Evans Gerald H. , Aichelmann‐Reidy Mary Elizabeth , Moore Kent , Cruz Renee , Scott J. Brent
Published: March 2012

A synthetic cell‐binding peptide (P‐15) combined with anorganic bovine‐derived hydroxyapatite bone matrix (ABM) was compared to deminerahzed freeze‐dried bone allograft (DFDBA) and open flap debridement (DEBR) in human periodontal osseous defects in a controlled, monitored, multi‐center trial. Following appropriate initial preparation procedures, flap surgery with defect and root debridement was performed. Three osseous defects per patient were treated randomly with one of three procedures after surgical preparation. Appropriate periodontal maintenance schedules were followed, and at 6 to 7 months re‐entry flap surgery was performed for documentation and finahzation of treatment. Analysis of variation (ANOVA) and t test analyses of patient mean values from 31 patients revealed that the combination ABM/P‐15 grafts demonstrated significantly better mean defect fill of 2.8 ± 1.2 mm (72.3%) versus a mean defect fill of 2.0 ± 1.4 mm (51.4%) for defects treated with DFDBA (P <0.05) and a mean defect fill of 1.5 ± 1.3 mm (40.3%) (P <0.05) for defects treated with DEBR. Other hard tissue findings showed similar chnically superior results with the use of ABM/P‐15. Relative defect fill results showed 87% positive (50% to 100% defect fill) responses with ABM/P‐15, 58% positive responses with DFDBA, and 41% positive responses with DEBR. There were 8 to 9 times more failures (minimal response) with DFDBA and DEBR (26% to 29% frequency) than with ABM/P‐15. Soft tissue findings showed no significant differences among treatments except for greater chnical attachment level gain with ABM/P‐15 compared to DEBR. These results suggest that the use of the P‐15 synthetic cell‐binding peptide combined with ABM yields better chnical results than either DFDBA or DEBR. Further studies are needed to determine the relative roles of the ABM and/or the P‐15 in these improved results. J Periodontol 1998;69:655–663.
Subgingival Microflora Associated With Nifedipine‐Induced Gingival Overgrowth
Authors: Nakou Mela , Kamma Joanna J. , Andronikaki Alkyoni , Mitsis Fotis
Published: March 2012

The purpose of this study was to examine the composition of subgingival plaque of 140 periodontal lesions in 35 patients with cardiovascular disorders who were administered nifedipine and manifested nifedipine‐induced gingival overgrowth (GO). Age was inversely associated with the GO. Plaque index and bleeding index showed a significant association with GO, while nifedipine dosage and duration of nifedipine therapy were not found to be significant predictors of GO. The gingival inflammation as expressed in the logistic regression model by the interaction term color × tone was found to be significantly associated with the GO. Statistically significant differences between the groups of comparable probing depth and different degrees of GO were detected for Propionibacterium acnes, Capnocytophaga gingivalis, Capnocytophaga ochracea, Capnocytophaga sputigena, Bacteroides gracilis, Fusobacterium mortiferum, Fusobacterium nucleatum, Fusobacterium varium and Selenomonas sputigena in deep and enlarged lesions. Significantly more frequently isolated were the bacterial species Eubacterium alactolyticum, Campylobacter concisus, C. gingivalis, C. ochracea, C. sputigena, F. mortiferum, F. nucleatum, and F. varium from the more enlarged lesions (GO >3). J Periodontol 1998;69:664–669.
Induction of COX‐2 Expression by Mechanical Tension Force in Human Periodontal Ligament Cells
Authors: Shimizu Noriyoshi , Ozawa Yasuhito , Yamaguchi Masara , Goseki Takemi , Ohzeki Kimimaro , Abiko Yoshimitsu
Published: March 2012

Occlusal trauma is caused by excessive occlusal forces and is associated with alveolar bone loss. In the periodontal ligament (PDL), which primarily receives the occlusal force, there is increased Prostaglandin E (PGE2) synthesis in response to mechanical stress, and many studies have shown that PGE2 is involved in the pathogenesis of periodontal diseases. Recently, two isozymes of cyclooxygenase, COX‐1 and COX‐2, which are key enzymes in Prostaglandin (PG) biosynthesis, were identified and COX‐2 was induced following the activation of cells by a variety of proinflammatory agents. However, the biosynthetic pathway of mechanical stress‐dependent PGE2 from PDL cells has not been well understood. When cyclic tension force was applied to human PDL cells (18% increase in surface area), PGE2 release to the culture medium increased in a time‐dependent manner. As analyzed by semi‐quantitative PCR, COX‐2 mRNAs, while hardly detectable in controls, increased dramatically on day 3 and 5 in response to tension force. In contrast, COX‐1 mRNAs detected in controls were not affected by tension force. By immunocytochemical staining, COX‐2 protein was significantly increased by tension force around the unstained cell nucleus in a time‐dependent manner. When NS‐398, a selective COX‐2 inhibitor, was added to the medium, PGE2 synthesis increased by tension force was completely inhibited. These results indicate that tension force induces COX‐2 in human PDL cells and that this induction is responsible for the augmentation of PGE2 production stimulated by tension force. Since selective COX‐2 inhibitors have less adverse effects compared with those of non‐steroidal anti‐inflammatory drugs, they may be of therapeutic benefit for treatment of periodontal disease accompanying traumatic occlusion. J Periodontol 1998;69:670–677.
Immunization With Porphyromonas gingivalis Cysteine Protease: Effects on Experimental Gingivitis and Ligature‐Induced Periodontitis in Macaca fascicularis
Authors: Moritz Alan J. , Cappelli David , Lantz Marilyn S. , Holt Stanley C. , Ebersole Jeffrey L.
Published: March 2012

Targeting bacterial virulence factors such as proteases for immunization may hold the key to hmiting or preventing loss of attachment and alveolar bone in periodontal disease. This study examined the chnical, microbiological, and immunological responses following active immunization with a purified Porphyromonas gingivalis cysteine protease (porphypain‐2) in the nonhuman primate (Nhp) Macaca fascicularis. One group of Nhp was immunized with porphypain‐2 antigen while control Nhp received placebo injections. AU Nhp were subjected to experimental gingivitis followed by hgature‐induced periodontitis in a split‐mouth design. An enzyme‐hnked immunosorbent assay demonstrated that immunization elicited a significantly elevated and specific IgG antibody response to both whole cell P. gingivalis (36‐fold) and to porphypain‐2 (194‐fold). Checkerboard hybridization DNA analysis of subgingival plaque from ligated sextants demonstrated that 25% more Gram‐negative anaerobic species became significantly elevated from basehne and at earlier timepoints in the control group than in the immunized group. Immunization with this protease did not suppress the emergence of P. gingivalis. Chnical indices showed few changes related to immunization. Alveolar bone density changes demonstrated a highly significant loss in ligated sextants compared to non‐ligated sextants within the control group (P < 0.001), and a smaller but significant difference within the immunized group (P = 0.043). Comparison of ligated sextants only demonstrated more bone loss in the control group versus the immunized group (−13.07±9.51 versus −9.41±6.18; computerassisted densitometric image analysis units ± SD); the difference approached, but did not reach, significance. The results suggest that porphypain‐2 may contribute to the pathogenic potential of the subgingival plaque microbiota in the Nhp model of hgature‐induced periodontitis, and that active immunization with porphypain‐2 appeared capable of altering this pathogenic response. J Periodontol 1998;69:686–697.
Comparison of Bioactive Glass Synthetic Bone Graft Particles and Open Debridement in the Treatment of Human Periodontal Defects. A Clinical Study
Authors: Froum Stuart J. , Weinberg Mea A. , Tarnow Dennis
Published: March 2012

The purpose of this study was to compare the repair response of bioactive glass synthetic bone graft particles and open debridement in the treatment of human periodontal osseous defects. Fifty‐nine defects in 16 healthy adults were selected. Each patient had at least 2 sites with attachment loss of at least 6 mm with clinical and radiographie evidence of intrabony or furcation defects. One to 3 months after causerelated therapy (oral hygiene instructions, scaling and root planing), the following measurements were recorded prior to surgery: probing depths, clinical attachment level, and gingival recession. Each defect was surgically exposed and measurements made of the alveolar crest height and base of osseous defect. The test defects were implanted with bioactive glass. The other sites served as unimplanted controls. Flaps were sutured at or close to the presurgical level. Radiographs and soft tissue presurgical measurements were repeated at 6, 9, and 12 months. At 12 months all sites were surgically re‐entered to record osseous measurements. At the 12‐month evaluation, significantly greater mean probing depth reduction was noted in the bioactive glass group compared to the controls (4.26 mm versus 3.44 mm; P = 0.028). Clinical attachment level gain was significantly improved (P = 0.0004) in the bioactive glass sites (2.96 mm) compared to the control sites (1.54 mm). There was significantly less gingival recession in the bioactive glass sites (1.29 mm) compared to the control sites (1.87 mm). Defect fill was significantly greater in the bioactive glass sites (3.28 mm) compared to the control sites (1.45 mm). Defect depth reduction was significantly greater in the bioactive glass sites (4.36 mm) compared to the control sites (3.15 mm). In conclusion, bioactive glass showed significant improvement in clinical parameters compared to open flap debridement. J Periodontol 1998;69:698–709.
Rapid Progression of Bone Loss in HIV‐Associated Necrotizing Ulcerative Stomatitis
Authors: Patton Lauren L. , McKaig Rosemary
Published: March 2012

This report describes a case of rapidly progressive periodontal tissue breakdown and bone loss in an HIV‐infected markedly immunosuppressed homosexual male. Within 6 months of initial presentation with a necrotizing ulcerative gingivitis, the lesion extended to a necrotizing ulcerative stomatitis involving the surrounding periodontium and palatal mucosa. With only partial compliance to local debridement, Chlorhexidine oral rinses, and systemic metronidazole therapy, alveolar bone loss resulted in tooth mobility necessitating extraction of 2 involved teeth. This case illustrates the continuum of necrotizing ulcerative infections of the periodontium in the severely immunosuppressed patient. The implications of these oral manifestations of HIV infection are discussed. J Periodontol 1998;69:710–716.
Management of Gingival Vitiligo With the Use of a Tattoo Technique
Authors: Center Jonathan M. , Mancini Sabrina , Baker Gerald I. , Mock David , Tenenbaum Howard C.
Published: March 2012

The purpose of this report is to describe the management of gingival vitiligo in a black female. This patient was referred by her psychiatrist to the Mount Sinai Hospital Dental Department (Toronto) for assessment of progressive loss in gingival pigmentation. According to her psychiatrist this loss of pigmentation, which the patient indicated may be considered in Africa as a hallmark of HIV infection, was a significant exogenous factor in relation to the patient's ongoing clinical depression. After obtaining informed consent, a modification of a tattooing method used for skin was applied to the patient's attached gingival tissues. Test sites were tattooed prior to performing full gingival tattooing under local anaesthesia. The results demonstrate that it was possible to restore this patient's gingival pigmentation in a highly esthetically acceptable manner. The resulting coloration was reminiscent of the patient's natural pigmentation that had been lost ostensibly because of her systemic disorder. Our findings also showed that the artificial pigmentation established via the tattoo method was stable 4 months postoperatively and continues to be stable, as expected. A profound improvement in the patient's mood was noted. J Periodontol 1998;69:724–728.
Nifedipine‐Induced Gingival Overgrowth in Rats: Brief Review and Experimental Study
Authors: Fu Earl , Nieh Shin , Hsiao Chiang Tung , Hsieh Yao‐Dung , Wikesjö Ulf M.E. , Shen E‐Chin
Published: March 2012

The first case report of gingival overgrowth induced by nifedipine (NIF), a calcium‐beta blocker, was in 1984. However, the association between gingival alterations and the drug therapy of sodium diphenyl hydantoinate was initially described in 1939. The purpose of the experimental study was to examine the effect of NIF on gingival morphology in an animal model. Forty‐five male Sprague‐Dawley rats were randomly divided into 3 groups. Animals in each group daily received NIF in dimethyl sulfoxide by gastric feeding at a dosage of 0 (control), 30, or 50 mg/kg body weight for 9 weeks. Gingival gross morphology was assessed tri‐weekly from stone models obtained from the mandibular incisai region. Animals were sacrificed at the end of study and tissue blocks were processed for histopathologic and histometric evaluation. Histometric analysis was performed at 5 selected tissue levels. Macro‐ and microscopic significantly increased gingival dimensions were demonstrated in NIF‐treated animals compared to control. Although a fibrovascular tissue was observed in the tooth‐gingiva interface for both NIF‐treated and control animals, it was thicker and appeared earlier in NIF‐treated animals. The results of the present study suggest that gingival overgrowth can be induced by NIF in rats and that the gingival overgrowth appears dose dependent. J Periodontol 1998;69:765–771.
Pulp Remains Viable Following Vital Amputation of the Mesio‐Buccal Root of the Maxillary Fourth Premolar in Dogs
Authors: Smith Mark M. , Saunders Geoffrey K. , Payne John T. , Cox Charles F.
Published: March 2012

Vital amputation of the mesio‐buccal root of the maxillary fourth premolar (P4) was performed bilaterally in 8 dogs. Histopathologic evaluation of the tooth structure revealed normal pulp in the remaining mesio‐buccal, mesio‐palatal, and distal roots and crown during a mean follow‐up period of 3.5 ± 1.9 months. Amputation site healing was characterized by a reparative dentin bridge produced by odontoid cells. Tunnel defects were observed in 13 of 16 (81%) dentin bridges. It is concluded that the pulp of a tri‐rooted, periodontal disease‐free tooth remains viable during a 6‐month period following vital root amputation. These results point to the intriguing possibility that this may also occur in humans, however, this needs to be directly tested in man. J Periodontol 1998;69:798–805.
The Effects of a Single Course of a Calculus‐Softening Scaling and Root Planing Gel. A Scanning Electron Microscopic Study
Authors: Nagy Richard J. , Endow John P. , Inouye Allen E. , Otomo‐Corgel Joan
Published: March 2012

The effect of a calculus scaling gel was evaluated as an adjunct to instrumentation in a double blind, split‐mouth, clinical study. Fifteen comparable periodontally involved teeth from 5 patients were instrumented on the mesio‐buccal root surface with the aid of either the test gel, placebo gel, or no gel until smoothness was achieved. Test or placebo gel was applied subgingivally for 10 minutes. Instrumentation time, ease, number of strokes, and gingival/tooth surfaces changes were recorded. Scanning electronic microscopic (SEM) evaluation of root surface topography was evaluated. The results demonstrated effective calculus removal in all treatment groups with no differences found between them. Instrumentation time, ease, and number of strokes were similar for all treatment groups. There were no harmful effects to soft or hard tissues. The results of this study do not support the use of calculus scaling gel as an adjunct to root instrumentation. J Periodontol 1998;69:806–811.
Effects of Topical Metronidazole and Tetracycline in Treatment of Adult Periodontitis
Authors: Lie Tryggve , Bruun Georg , Böe Olav E.
Published: March 2012

The present study was performed to assess and compare the clinical healing and the microbiological findings following local application of metronidazole or tetracycline to augment subgingival scaling in previously untreated adult periodontitis sites. Eighteen patients with moderate to severe adult periodontitis at single‐rooted teeth were selected. In each patient, 3 interproximal sites having comparable root anatomy, probing depth ≥5 mm and bleeding on probing were randomly assigned to 1 of 3 treatment groups: 1) two sessions of subgingival scaling and root planing; 2) similar to 1, with each treatment supplemented with a 25% metronidazole sustained release gel; 3) similar to 1 with each treatment supplemented with a 3% tetracycline ointment. The treatments were performed by 1 operator and the clinical variables probing depth, attachment level, and bleeding on probing were evaluated at baseline, 3 months and 6 months by a second blinded examiner. The microbiological findings were evaluated using a commercial test kit. The average probing depth reduction for the 3 groups at 6 months was 1.5 mm and the average gain of clinical attachment was 0.8 mm. There were no significant differences between the effects following topical application of the metronidazole gel or the tetracycline ointment. Scaling and root planing alone appeared as effective as the drug augmented regimens, although there was a weak but non‐significant tendency for better results in sites treated with the antibiotic drugs. Actinobacillus actinomycetemcomitans was generally not detected; Prevotella intermedia was not significantly reduced, while Porphyromonas gingivalis was significantly reduced in all treatment groups. It was concluded that the augmentative effect of the metronidazole gel and the tetracycline ointment was comparable but small compared to scaling and root planing alone. The clinical importance of such small augmentation effects should be further evaluated. J Periodontol 1998;69:819–827.
Histologic Evaluation of New Attachment Utilizing a Titanium‐Reinforced Barrier Membrane in a Mucogingival Recession Defect. A Case Report
Authors: Parma‐Benfenati S. , Tinti C.
Published: March 2012

Guided tissue regeneration was used to treat a localized, deep, buccal recession on a mandibular left central incisor. This tooth was labially displaced and scheduled for extraction for orthodontic reasons. The mucogingival defect had 7 mm of facial gingival recession, and 4 mm mid‐buccal probing depths. The attachment loss was 11 mm. There was no attached gingiva. At surgery the root was notched as landmarks for assessing the histological examination. A titanium reinforced barrier membrane was left in place for 4 weeks. At the time of extraction, 9 months post‐initial treatment, there was a gain of 3 mm of root coverage and 1 mm of gingiva. The tooth and facial tissues were removed by block section for histologie evaluation. The root surface exhibited a total amount of a histologic new connective tissue attachment of 5.6 mm and regeneration of a new bone growth of 6.7 mm of bone. The histologic findings demonstrated that the coronal extent of the new attachment and new facial bone, 9 months after guided tissue regeneration treatment, were located coronal to the preoperative location, in a root surface previously exposed by a deep, long‐standing recession. J Periodontol 1998;69:834–839.
In Vitro Studies on the Effect of Cleaning Methods on Different Implant Surfaces
Authors: Augthun Michael , Tinschert Joachim , Huber Anja
Published: March 2012

The effect of specific cleaning procedures was examined on the surfaces of 3 implant types with different coatings and shapes (plasma sprayed [PS]; hydroxyapatite coated [HA] implants; and smooth titanium surface screws) using a scanning electron microscope. Each implant was treated for 60 seconds per instrument with one of 6 different hygiene measures: plastic curet, metal curet, diamond polishing device, ultrasonic sealer, air‐powder‐water spray with sodium hydrocarbonate solution, and chlorhexidine 0.1% solution rinse. The air‐powder‐abrasive system, chlorhexidine rinse, and curettage with a plastic instrument caused little or no surface damage in all but the hydroxyapatite‐coated fixtures. Therefore, these 3 methods were tested to determine their cleaning efficacy in a second clinical study, which did not include the HA‐coated fixture. Two implants were placed on the facial aspects of both upper molar regions using individual acrylic plates. Thus, 2 fixtures on each side were examined in each patient. The examination revealed that only the sodium hydrocarbonate spray yielded a clean fixture without damage to the implant surface. In a third stage, which imitated the clinical procedure of the second approach, the cell growth of mousefibroblasts on implant surfaces was examined after cleaning the surface with plastic sealer and the air‐abrasive system, which represents the least damaging and most effective methods. In contrast to the implant surfaces treated with plastic scalers, mostly vital cells were found on implants sprayed with the air‐abrasive system. J Periodontol 1998;69:857–864.
The Relationship Between Concentrations of Proinflammatory Cytokines Within Gingiva and the Adjacent Sulcular Depth
Authors: McGee J.M. , Tucci M.A. , Edmundson T.P. , Serio C.L. , Johnson R.B.
Published: March 2012

The objective of this study was to determine and compare concentrations and ratios of 3 proinflammatory cytokines, interleukin (IL) IL‐1β, IL‐6, and IL‐8 within gingival tissue biopsies adjacent to ≤3, 4 to 6, or >6 mm sulci. All gingiva adjacent to ≥4 mm sulci had clinical evidence of active inflammation. Factorial analysis of variance suggested significant effects of sulcus depth on the type and concentration of the three cytokines in the adjacent gingiva (P < 0.001). IL‐8 concentrations were highest in gingiva adjacent to ≤3 and lowest adjacent to >6 mm sulci (P < 0.001). In contrast, IL‐6 concentrations were lowest in gingiva adjacent to ≤6 mm and highest adjacent to >6 mm sites. IL‐1β concentrations were highest in gingiva adjacent to >6 mm and lowest adjacent to 4 to 6 mm sites; they were also higher adjacent to ≤3 mm than adjacent to 4 to 6 mm sites (P < 0.01). Multiple regression analysis suggested that sulcular depth, type of cytokine, and cytokine concentration were significantly correlated (P < 0.001). Ratios of gingival cytokines changed with increased sulcular depth. In gingiva adjacent to ≤6 mm sites, IL‐8 was the most and IL‐6 the least prevalent. In gingiva adjacent to ≥6 mm sites, IL‐8 was the least and IL‐1‐β the most prevalent. The data suggest that the characteristics of the gingival cytokine network are affected by adjacent sulcular depth. These data could be used to design adjunct diagnostic tests for progression of periodontal diseases. J Periodontol 1998;69:865–871.
Calprotectin and Lactoferrin Levels in the Gingival Crevicular Fluid of Children
Authors: Miyasaki Kenneth T. , Voganatsi Alexandra , Huynh Thuc , Marcus Marvin , Underwood Steven
Published: March 2012

The purpose of this study was to determine the levels of calprotectin and lactoferrin, 2 microbiostatic proteins, in the gingival crevicular fluid (GCF) of normal children. The children represented a population, primarily underprivileged, seeking care at a regional dental health care center. GCF was collected from Ramfjord teeth (or their deciduous equivalent). GCF volume was quantified by conductance. Calprotectin and lactoferrin levels were quantified by sandwich ELISA, and found to have a mean value of 70.8 ± 94.2 μg/mL and 68.2 ± 108.7 μg/mL, respectively. The levels of calprotectin and lactoferrin varied directly with one another and inversely with the amount of fluid obtained in a 20‐second sampling period. The mean levels were at or above the minimum inhibitory concentration determined in vitro. J Periodontol 1998;69:879–883.
The Treatment of Class III Maxillary Furcations Using a Resin‐Ionomer. A Case Report
Authors: Anderegg C.R.
Published: March 2012

This case report uses a resin‐ionomer restoration as a barrier in the treatment of a Class III furcation defect. There was a reduction in tooth mobility and plaque count, no bleeding on probing, and a decrease in probing depth with the use of the resin ionomer. The study offers another treatment option in the treatment of a seemingly hopeless maxillary molar. J Periodontol 1998;69:948–950.
Guided Tissue Regeneration in Class II Furcation Involved Maxillary Molars: A Controlled Study of 8 Split‐Mouth Cases
Authors: Avera John B. , Camargo Paulo M. , Klokkevold Perry R. , Kenney E. Barrie , Lekovic Vojislav
Published: March 2012

The purpose of this study was to clinically evaluate the effectiveness of polytetrafluoroethylene membranes in the healing of interproximal Class II furcation defects in maxillary molars using a surgical treatment technique based on the principles of guided tissue regeneration. Eight subjects with similar bilateral Class II furcation lesions on the mesial aspect of maxillary first molars participated in this study. Patients received initial therapy consisting of oral hygiene instructions, scaling and root planing, and occlusal adjustment if necessary. Clinical parameters evaluated included plaque index, sulcular bleeding index, probing depth, attachment level, gingival recession, and open horizontal and vertical furcation fill. An acrylic occlusal stent was used to assure reproducibility of measurements. Experimental sites received a polytetrafluoroethylene membrane following surgical exposure of the furcation. Control sites were treated in the exact same manner but without a membrane. Membranes were removed at 6 weeks after the first surgery. Reentry surgeries were performed at 9 months. Postsurgical results showed a significant improvement in probing depth, attachment level, and open horizontal furcation fill for both groups when compared to baseline values, with experimental sites performing significantly better than controls. Control sites showed a slight loss in open vertical furcation fill while experimental sites remained unchanged. This study suggests that guided tissue regeneration using polytetrafluoroethylene membranes is of some but limited value in the treatment of maxillary molar interpoximal Class II furcation lesions. J Periodontol 1998;69:1020–1026.
Evaluation of Periosteal Membranes and Coronally Positioned Flaps in the Treatment of Class II Furcation Defects: A Comparative Clinical Study in Humans
Authors: Lekovic Vojislav , Klokkevold Perry R. , Camargo Paulo M. , Kenney E. Barrie , Nedic Melica , Weinlaender Michael
Published: March 2012

The purpose of this study was to compare the clinical effectiveness of connective tissue grafts including periosteum used as a mechanical barrier for guided periodontal tissue regeneration and coronally positioned flaps in the treatment of Class II furcation defects. A total of 28 furcation defects were treated; 14 received a periosteal barrier and 14 received a coronally positioned flap. Reentry surgeries were performed at 6 months. No statistically significant differences were found preoperatively between the two treatment groups with respect to clinical parameters and osseous measurements. Postsurgically, both treatment modalities resulted in a significant decrease in probing depth and a significant gain in clinical attachment, but the differences observed were not statistically significant. The periosteal barrier group presented with a significantly better gain in vertical components of the alveolar bone (1.93 ± 0.15 mm and 0.20 ± 0.26 mm for periosteal barrier and coronally positioned flap groups, respectively; P ≥ 0.001) and horizontal components of the alveolar bone (1.60 ± 0.21 mm and 0.13 ± 0.90 mm for periosteal barrier and coronally positioned flap groups, respectively; P ≤ 0.001). The results of this trial indicate that similar clinical resolution of Class II furcation defects can be obtained with periosteal barriers and coronally positioned flaps. Periosteal barriers, however, are a better treatment alternative in achieving bone fill of the furcation area. J Periodontol 1998;69:1050–1055.
Alveolar Bone Levels in AIDS and HIV Seropositive Patients and in Control Subjects
Authors: Persson Rigmor E. , Hollender Lars G. , Persson G. Rutger
Published: March 2012

Alveolar bone levels were studied from intraoral radiographs of 24 non‐hospitalized patients with AIDS, 17 HIV seropositive subjects, and 39 matched control subjects. The AIDS/HIV subjects were seeking dental care in a faculty practice. The matched control subjects came from those non‐HIV‐infected patients seeking dental care at the University of Washington. Magnified intraoral radiographs were used to assess the distance between the cemento‐enamel junction (CEJ) and the alveolar bone level (BL). The extent of vertical defects and furcation invasions was also assessed. The mean age of the AIDS, HIV, and control subjects was 38.9 ± 6.6 years, 37.1 ± 7.6, and 39.9 ± 5.6, respectively, and was not statistically different. Among the AIDS patients, 75% were smokers, while 88.2% of the HIV subjects were cigarette smokers. Therefore, the matched control subjects were also smokers to the same extent. The mean difference in distance CEJ‐BL was 0.1 mm (mesial) and 0.3 mm (distal) and greater in the HIV/AIDS group than in the control group, but not statistically different. No vertical defects ≥ 3.0 mm were found in 69.2% of the control subjects and in 58.5% of the combined HIV/AIDS group. None of the HIV/AIDS subjects had more than 5 defects > 3.0 mm, while 7.6% of the control subjects had such defects. Significant associations were found between smoking and extent of alveolar bone loss (distance) (P < 0.001) as well as the number and extent of vertical defects (P < 0.01), but were not associated with HIV status. The extent of furcation invasions, as read radiographically, did not differ between groups. In conclusion, smoking but not HIV status was the primary factor for alveolar bone loss. J Periodontol 1998,69:1056–1061.
A 2‐Year Clinical Evaluation of a Diphenylphosphorylazide‐Cross‐Linked Collagen Membrane for the Treatment of Buccal Gingival Recession
Authors: Zahedi Shahram , Bozon Caroline , Brunel Gérard
Published: March 2012

To retard collagen membrane enzymatic degradation and to increase its mechanical strength, the diphenylphosphorylazide (DPPA) technique has been demonstrated to achieve natural cross‐links between peptide chains of collagen without leaving any foreign product in the cross‐linked molecule. In the present prospective clinical trial, the potential of a DPPA‐cross‐linked type I bovine collagen membrane was evaluated in the healing of 15 buccal soft tissue recessions in 15 patients according to the biological concept of guided tissue regeneration. The recession decreased from 3.7 mm (SD 1.4) at baseline to 0.8 mm (SD 1.2) at 2 years postsurgery, corresponding to a mean root coverage of 82.2% (P <0.0001). Concurrently, the clinical attachment level decreased from 5.4 mm (SD 1.6) at baseline to 1.9 mm (SD 1.2) 2 years postsurgery, corresponding to an average clinical attachment gain of 3.5 mm (SD 1.3) (P <0.0001). The 2‐year postsurgical width of the keratinized tissue was not significantly different from baseline values. More than half (53%) of the treated sites showed complete root coverage and about two‐thirds (73%) of the total cases showed a 75% to 100% disappearance of the mucogingival defect. The present investigation demonstrated that the use of DPPA‐cross‐linked collagen membranes in the treatment of human buccal soft tissue recessions results in predictable amounts of root coverage and clinical attachment gain. Long‐term randomization controlled clinical trials of this material are needed to fully evaluate its potential for treating periodontal recession. J Periodontol 1998;69:975–981.
Effect of a Calcium Sulfate Implant With Calcium Sulfate Barrier on Periodontal Healing in 3‐Wall Intrabony Defects in Dogs
Authors: Kim Chong‐Kwan , Kim Hyun‐Young , Chai Jung‐Kiu , Cho Kyoo‐Sung , Moon Ik‐Sang , Choi Seong‐Ho , Sottosanti John S. , Wikesjö Ulf M.E.
Published: March 2012

This controlled, split‐mouth, preclinical study was designed to evaluate outcome following surgical implantation of an allogeneic, freeze‐dried demineralized bone matrix‐calcium sulfate (DBM+CS) composite with a CS barrier in 3‐wall intrabony periodontal defects in 4 dogs. Control conditions included surgical implantation of DBM or CS and gingival flap surgery (GFS) alone. Three‐wall intrabony defects (4×××4 mm) were surgically created at the mesial and distal aspect of the maxillary and mandibular first and third premolare, respectively. Maxillary and mandibular defects each received 1 of the 4 experimental conditions. Experimental conditions were rotated between defect sites in subsequent animals. Block sections of the defects were collected at sacrifice 8 weeks postsurgery and processed for histometric analysis. Histometric defect height (means ± SD) for the DBM+CS, DBM, CS, and GFS groups amounted to 4.2 ± 0.5, 4.3 ± 0.7, 4.0 ± 0.2, and 4.1 ± 0.2 mm, respectively. Connective tissue adhesion (connective tissue contact to the root without apparent cementum formation) amounted to 0.4 ± 0.3, 0.4 ± 0.3, 0.5 ± 0.2, and 1.6 ± 0.5 mm for the DBM+CS, DBM, CS, and GFS groups, respectively; the DBM+CS, DBM, and CS groups being significantly different from the GFS group (P < 0.05). Cementum regeneration amounted to 3.0 ± 0.3, 3.1 ± 0.4, 2.5 ± 0.4, and 1.6 ± 0.3 mm for the DBM+CS, DBM, CS, and GFS groups, respectively; the DBM+CS, DBM, and CS groups being significantly different from the GFS group (P < 0.05). Alveolar bone regeneration amounted to 2.7 ± 0.4, 2.7 ± 0.3, 1.8 ± 0.5, and 0.7 ± 0.1 mm for the DBM+CS, DBM, CS, and GFS groups, respectively; the DBM+CS, DBM, and CS groups being different from the GFS group (P < 0.05), and the DBM+CS and DBM groups being different from the CS group (P < 0.05). None of the DBM‐containing implants provided evidence of bone metabolic activity. In summary, surgical implantation of DBM and CS, alone or in combination, may result in significantly improved regeneration of alveolar bone and cementum in this preclinical model. Observed regeneration is likely unrelated to a biologic activity inherent in DBM. Rather it appears that space‐providing properties of the implants supported observed regeneration. J Periodontol 1998;69:982–988.
An Advanced Multi-Lateral Horizontal Well Coupled Coalbed Methane (CBM) Simulation Model and its Application in Qinshui Basin of China
Authors: Zheng Shiyi , Xue Lili
Published: March 2012

Production enhancement and ultimate recovery improvement have given multi-branch horizontal wells the advantage over the vertical wells in many CBM marginal reservoirs. However, it is relatively very expensive to drill a muti-branch horizontal well than the vertical one, which makes difficulties for the engineers to determine an economical feasibility of drilling the multi-branch horizontal well as well as to estimate the productivity.

Through a widely literature review, an advanced non-analytical coupled CBM model has been developed in this study for predicting the flux and pressure in the CBM reservoir and multi-branch wellbore simultaneously. The gridding partition is achieved through adjusting the length of the grid to make the branch with an angle of horizontal direction just across the grid intersect point.

The coupled multi-branch CBM model is differeciated using modified IMPES method, LDU decomposition method is used for solving the formed seven point diagonal sparse matrix. Thereafter, the sensitivity analyses were performed to identify the dominant governing parameters such as gas slippage factor, threshold pressure gradient of formation model, branch angle, and branch number of muti-branch horizontal wellbore on the measurements of well deliverability.

The observation shows that gas slippage effect can enlarge gas production rate, while the threshold pressure gradient has the opposite effect. The gas production rate increases with the branch number ranging from 2-6, while decreases when the branch number reached to 8, so it is obviously not the case that the more the branch the better the flux enhancement. The gas flux reached to maximum when the branch angle is 45 degree, while minimum with 30 degree angle. Comparison of the fluid flux between vertical well, horizontal well and multibranch horizontal well was also made. Subsequently the proposed coupled model and developed program is validated by its application to Qinshui basin in Shanxi of China.
Hydraulic Fracture Production Optimization with a Pseudo-3D Model in Low-Permeability, Multi-Layered Lithology
Authors: Yang Mei , Valkó Peter P. , Economides Michael J.
Published: March 2012

Systematic design and optimization procedures for hydraulic fracturing are available using two-dimensional (2D) (with constant fracture height) and pseudo-three-dimensional (p-3D) models to maximize well production by optimizing fracture geometry, including fracture height, half-length and width.

A multi-layered p-3D approach to design is proposed integrating Unified Fracture Design (UFD), fracture propagation models and Linear Elastic Fracture Mechanics (LEFM) relationship to generate optimized fracture geometry, including fracture height, width and half-length to achieve the maximized production. Containment layers are discretized to allow for plausible fracture heights when seeking convergence of fracture height and net pressure.

UFD sizes the fracture geometry to physically optimize the hydraulically fractured well performance. The Proppant Number is a correlating parameter, which in turn provides the maximum dimensionless productivity index (JD) corresponding to the optimum dimensionless fracture conductivity, CfD. Once the latter is determined, the optimum fracture dimensions, i.e., fracture length and width, are set. However, UFD in its original form needs the ability to calculate the Proppant Number and that is possible only if fracture height is an input parameter and hence fraction of proppant ending up in the pay can be determined before the optimization.

PKN or KGD fracture propagation models in design mode provide basic treatment parameters to achieve a known target length and also associated net pressure. Linear Elastic Fracture Mechanics (LEFM) relationship can be used to obtain fracture height associated to a given vertical pressure distribution via vertical stress profile and fracture toughness profile. This study considers the contributions of all layers to the stress intensity factor at the fracture tips to find the potential equilibrium height defined by the condition where the stress intensity factor minus fracture toughness difference changes sign (but not necessary becomes zero.) After an equilibrium height and the corresponding net pressure are found, an optimization is carried out to find target length and a 2D design model is used to calculate treatment parameters, first of all net pressure. The ultimate goal is to find a consistent pair of these two different sub-models; when the assumed pressure condition in the LEFM part coincides with the resulting pressure condition from the UFD/2D part. Parts of this work also allows for determining conditions to avoid propagating into unintended layers (i.e. gas cap and/or aquifer) or to assure coverage of intended layers (such as a non-perforated layer with recoverable hydrocarbon.)
Impact of Fracturing and Fracturing Techniques on Productivity of Unconventional Formations
Authors: Soliman M. Y. , Daal Johan , East Loyd
Published: March 2012

Unlocking the potential of unconventional gas reservoirs can change the balance and future of the oil industry. Unconventional gas reservoirs can be tight-gas, coalbed methane (CBM), or shale reservoirs. Economic production of any of these three types requires the creation of multiple fractures from a long horizontal well. Fracturing horizontal wells presents several challenges regarding the rock mechanics, change of stresses around the created fractures, and fluid flow.

New and reinterpreted laboratory experiments have shed new light on fracturing a horizontal well and the effect of how the well is completed on the fracturing process. The results could explain the presence of multiple fractures at the wellbore. These geomechanical issues could influence the fracturing process, especially in naturally fractured formations. This paper investigates the effect of various fracturing scenarios on the stress distribution around the fractures. Optimization of the number of fractures is also investigated from both fluid-flow and geomechanical points of view.

Special attention is given to shale formations for two reasons—because of the great potential of shale formations, and because of the special characteristics that makes shale unique and challenging. Shale formations have ultra-low permeability that can be in the nanodarcy range. Shale formations are naturally fractured, and, depending on the carbon content, can have a significant amount of adsorbed gas.

This paper also investigates the effect of gas adsorption on productivity. Field examples are presented.
Petrophysical Parameters Evaluation in Unconventional Reservoirs by Well Logging and Mud Logging Data Interactive Correlation Method
Authors: Jurcic Hrvoje , Cogelja Zoran , Maretic Srecko
Published: March 2012

The idea and interest of studying the unconventional hydrocarbon reservoirs in the Panonian Basin System, abbr. PBS, (the Drava, Mura and Zala Depressions) are achieved by defining the joint research project carried out by the multidisciplinary team of MOL and INA petroleum companies. This analysis is performed in the Croatian part of the Panonian Basin System (CPBS). Eight areas with potential existence of unconventional reservoirs were examined with focus on Tight Gas Sands and Gas Shales.

The primary object in this project stage is the estimation of possible unconventional reserves of gas (or Original Gas in Place, abbr. OGIP). Reserves are defined by area and reservoir porosity, saturation and net pay. They are usually estimated from well logging data and core laboratory and hydrodynamic data. Some difficulties and inabilities of accurate, i.e. professionally acceptable reservoir evaluation, were noticed. The reason is inadequate or incomplete well logging suite and inadequate formation evaluation work flow. Therefore, evaluation concepts from unconventional reservoirs presented in North American petroleum provinces could not be directly applied in our case. It was inevitable to use other data source, especially the Mud Logging Data to quantify net pay and qualify saturation. The rate of penetration, abbr. ROP, gas indications while drilling, the presence of hydrocarbon in rock samples, fracture systems on cores, inflows, eruptions and mud losses as well as the interpretation of overpressure using D exponent, abbr. Dcs method, significantly facilitated the evaluation of necessary parameters.

It is crucial to improve economics of hydrocarbon production from any basin through operational efficiency, well productivity as well as new analytical models. Here presented evaluation method of potential hydrocarbon reserves is applicable in any similar case. It provides a highly acceptable professional credibility and can be very useful in situations with incomplete and inadequate Well Logging Suite facilitating identification and categorization of unconventional reservoirs.
Using Deep Azimuthal Resistivity and 3D Seismic for Optimal Horizontal Well Placement: An Integrated Approach, Nipisi Field, Western Canada
Authors: Omovie Sheyore John , Pearson Warren , Homburg Heiko , Manuel Ela , Luxey Pascal , Wright Talmadge
Published: March 2012

A major challenge facing the oil industry is optimizing horizontal wellbore placement in a reservoir. Uncertainty in the predrill geological model and seismic interpretation may lead to the well being placed in non-reservoir, or steering the well out of the prospective formation. This can lead to lower well performance or the requirement to sidetrack the wellbore, both of which directly impact the profitability of the operation.

The Nipisi D Pool produces oil from the Middle Devonian Slave Point Formation, a regionally extensive carbonate bank characterized by low permeability limestone reservoir. The advent of horizontal drilling (HZ) and completion technologies has elevated this reservoir to a top tier tight oil resource play. Although HZ drilling provides a cost effective means to reservoir development, maximizing reservoir penetration while avoiding the unstable shale above the Slave Point are imperative.

Structural definition of the reservoir is provided by 3D seismic coverage. This provides a good predrill estimate of wellbore trajectory, however is limited in its vertical accuracy, as well as definition of small-throw faults that do not appear to be imaged on the seismic data. These two limitations introduce a real risk of drilling out of the productive zone.

Using the contrast in resistivity between the productive carbonate reservoir and the low resistivity Waterways shale which overlies it, deploying Measurement-While Drilling (MWD) deep azimuthal resistivity tools provided the operator with higher resolution measurements to detect the top of reservoir and keeping the wellbore within the desired reservoir. This paper focuses on the integration of geological/3D seismic mapping and MWD azimuthal resistivity for optimal HZ well placement in a tight limestone reservoir, as well as the limitations of each technology when used in isolation. It illustrates how utilizing this approach the operator was able to achieve 100% reservoir exposure.
Numerical Investigation of Hydraulic Fracturing Process and Sensitivity to Reservoir Properties and Operation Variables
Authors: Putthaworapoom Natthapon , Miskimins Jennifer L. , Kazemi Hossein
Published: March 2012

Although a stimulation technique, the hydraulic fracturing process can also cause damage to the reservoir in a variety of ways. These damage mechanisms cannot be completely eliminated, but by careful examination of their individual characteristics and effects on production, focus can be placed on minimizing the most critical factors. This paper presents the results of a sensitivity study of numerous reservoir properties and operational control variables on fracture effectiveness and production from a fractured gas well. Simulations are based on a newly developed mathematical model for hydraulic fracture propagation and cleanup processes, combined with reservoir simulation.

The numerical simulation model considers a three-dimensional reservoir which can either be homogenous or heterogeneous. The created fracture is extended with time and the corresponding leak-off effects on the near wellbore and far-field area are assessed. Two-phase flow equations, both in the fracture and in the surrounding matrix, are used to evaluate behavior during the fracture propagation and production/clean-up periods.

The developed simulation model is validated by history matching with actual field performance from a fractured gas well. The history matched results are used as a base case for the study. The sensitivity results show the creation of different leak-off profiles and the effectiveness of corresponding cleanup processes. Results indicate that shut-in time between end of fracture propagation and beginning of flowback is critical due to imbibition of fracturing fluids. Additionally, heterogeneity of the reservoir has a significant effect on cleanup profiles.

Not only does that this study provide significant insight into phenomena happening on the fracture face and inside the reservoir, it and the developed simulator can also be used as a tool for hydraulic fracturing design or post-stimulation evaluation.