Biomedical subjects

C E Nemcovsky

Publications and source records attributed to C E Nemcovsky.

At least 19 recordsLinked to original sources

PubMed2004

In vitro effects of enamel matrix proteins on rat bone marrow cells and gingival fibroblasts.

Emdogain (EMD), a formulation of Enamel Matrix Proteins (EMP), is used clinically for periodontal regeneration, where it stimulates cementum formation and promotes gingival healing. In this study, we investigated the in vitro effects of EMD on rat bone marrow stromal cells (BMSC) and gingival fibroblasts (GF). EMD (at 25 micro g/mL) increased the osteogenic capacity of bone marrow, as evidenced by approximately three-fold increase in BMSC cell number and approximately two-fold increase in alkaline phosphatase (ALP) activity and mineralized nodule formation. The presence of EMD in the initial stages (first 48 hrs) of the culture was crucial for this effect. In contrast, EMD did not induce osteoblastic differentiation of GF (evidenced by lack of mineralization or ALP activity) but increased up to two-fold both their number and the amount of matrix produced. These in vitro data on BMSC and GF could explain the promotive effect of EMD on bone formation and connective tissue regeneration, respectively.

Alkaline Phosphatase↗

PubMed2003

[Differential diagnosis and treatment strategies for peri-implant diseases].

UNLABELLED: The aim of this article is to discuss the requirements to prevent, intercept and treat the peri-implant diseases at different stages. The ethiology and pathogenesis of peri-implant disease is presented, followed by definition and characteristics of the two main entites: peri-implant mucositis and peri-implantitis. Data and concepts regarding various evaluation parameters, such as pocket probing depth, bleeding on probing, gingival and plaque scores, radiographic and mobility which should be used to assess the clinical status of the peri-implant environment are discussed. The detection and treatment of early pathogenic changes during regular recall maintenance visits can prevent peri-implant soft tissue inflammation and progressive bone loss. The biologic rationale and guidelines for therapeutic procedures aimed to prevent and arrest the Peri-implant Disease according to a maintenance system termed Comulative Interceptive Supportive Therapy (CIST) is presented. The CIST protocol includes as a first sequence mechanical antiseptic and antibiotic treatment to control ongoing infection. Following this, peri-implant bony lesion may be corrected by regenerative or resective surgical techniques. IN CONCLUSION: By continuing diagnosis during maintenance, developing peri-implant infections can be controlled successfully by providing mechanical, antiseptic, antibiotic and surgical supportive therapy, individually or combined.

Alveolar Bone Loss↗

PubMed2001

Tetracycline modulates collagen membrane degradation in vitro.

BACKGROUND: Structural integrity of implanted bioabsorbable barrier membranes should be preserved for a sufficient time to ensure expected results. Collagen membranes are degraded by metalloproteinases (MMP). Their degradation rate can be altered either by enhancing structural integrity or by delaying the degradation process using MMP inhibitors. Tetracyclines (TTC) present inhibitory effects on matrix MMP. Immersing membranes in TTC solution before implantation can delay their degradation. The purpose of the present study was to evaluate the effect of collagen membranes immersed in varying TTC concentration solutions on the rate of their degradation in vitro. METHODS: Collagen bioabsorbable membranes were prepared as 5 mm diameter membrane discs. Membranes were then incubated at 4 degrees C for 24 hours, in either phosphate buffered saline (PBS, Ca2+ and Mg2+ free) or with TTC-HCl dissolved in PBS concentrations of 5 mg/ml, 50 mg/ml or 100 mg/ml. After rinsing, membranes were incubated with either bacterial collagenase or cultures of human bone lineage cells. Membrane degradation was studied on days 2, 4, 7, and 14. Two- and 3-way analysis of variance was used to analyze results. RESULTS: Samples supplemented with bacterial collagenase exhibited a statistically significant interaction between changes of free protein in the medium, antibiotic concentration used for the immersion, presence of collagenase in the medium, and incubation time (P<0.0001). Membranes incubated with bone cells exhibited similar degradation trends. CONCLUSIONS: Collagen membranes immersed in 50 mg/ml TTC solution exhibited the longest degradation time, both in the clostridial collagenase and the human bone cell lineage assays. Immersion in a 50 mg/ml TTC solution before implantation will delay their degradation.

Absorbable Implants↗

PubMed2001

Orthodontic tooth movement enhances bone healing of surgical bony defects in rats.

BACKGROUND: The question of whether the repair of an alveolar bony defect can be enhanced by orthodontic tooth movement was addressed. METHODS: Alveolar bone defects were created in 52 Wistar male rats anterior to both maxillary first molars. After 1 week of healing, orthodontic protraction was applied for 2 weeks on the right side, resulting in mesial tipping and displacement movement. Subsequently, a retention appliance was inserted for 1 week. The left side served as the untreated (control) group. Vital bone staining (procion brilliant red H-8) was administered before and after orthodontic traction. Histomorphometric analysis was performed on 62 hemimaxillae using UV confocal microscopy and an imaging program. The total area of the bony defect was divided into 4 equal quadrants, and the area of bony apposition in each quadrant was measured. RESULTS: The total area of bony apposition was 6.5-fold larger in the treated (26.41 x 10(4) +/- 28.92 x 10(4) microm2) than in the control group (4.07 x 10(4) +/- 2.82 x 10(4) microm2), approaching statistical significance (P = 0.065). The treated occlusal quadrants demonstrated highly significant (P= 0.010), greater bone apposition compared to the control group (13.8-fold) and to the treated apical quadrants (P= 0.04, 5-fold). CONCLUSIONS: This study confirms that orthodontic tooth movement is a stimulating factor of bone apposition. A conversion in the repair pattern of the bony defect from apicoocclusal in the control group (no tooth movement) to occlusoapical in the treated group (with tooth movement) further supports the linkage between tooth movement and enhanced bone deposition. Clinical implication suggests incorporation of orthodontic tooth movement in regenerative therapy.

Alveolar Process↗

PubMed2001

Histopathological morphometric evaluation of 2 different hydroxyapatite-bone derivatives in sinus augmentation procedures: a comparative study in humans.

BACKGROUND: Xenografts to augment the maxillary sinus have been used extensively. The aim of the present study was to evaluate, qualitatively and quantitatively, two different HA derivatives of natural and synthetic sources on newly formed bone in the augmented sinus. METHODS: A bilateral sinus augmentation procedure with simultaneous (16 out of 20 sites) or subsequent implant placement was performed in 10 patients. The antrum was randomly filled with a deproteinized, bovine hydroxyapatite mineral (B-HA) on one side and a non-ceramic resorbable hydroxyapatite (NC-HA) on the other. Cylindrical specimens were harvested from the augmented core at 12 months. Decalcified specimens were sectioned at a cross-horizontal plane and stained with hematoxylin and eosin for histopathologic and histomorphometric examinations. Tissue area fractions of bone, marrow, and the grafted particles were calculated for each specimen from the lateral to the deep region, and changes in values were compared within each material and between them. RESULTS: New bone formation was evident. B-HA and NC-HA particles were observed in all specimens surrounded by newly formed bone in direct connection or by soft tissue marrow. Morphometrically in the B-HA sites, from the lateral to deeper area, bone area fraction increased from 29.8% to 54.2% (average 42.1%) and marrow area fraction decreased from 37.9% to 26.7% (average 33.3%). The mineral area fraction decreased from 32.3% to 19.1% (average 24.7%). All increasing/decreasing patterns were statistically significant (P < 0.001). In the NC-HA sites, from the lateral to deeper area, bone area fraction increased from 25% to 36.5% (average 32.3%) and marrow area fraction decreased from 51.6% to 41.9% (average 43.2%) (P <0.001). The mineral area fraction decreased from 29% to 21.7% (average 24.6%) (P = 0.038). Comparison between the two HA derivative groups showed a significant difference between the bone area fraction averages (P = 0.0053) and between the increasing patterns along the core depth (P = 0.0006). There was also a significant difference between the decreasing marrow patterns (P = 0.003), but not between their averages. Comparison between the mineral area fractions showed no differences. CONCLUSIONS: B-HA and NC-HA were proven to be biocompatible materials. Although the B-HA-augmented sites showed a higher percentage of bone formation at 12 months, both are suitable bone derivatives in sinus augmentation procedures and can accommodate osseointegrated implants.

Absorbable Implants↗

PubMed2001

Efficacy of porous bovine bone mineral in various types of osseous deficiencies: clinical observations and literature review.

Recent developments in osseous regenerative techniques have increased the demand for bone-substitute grafting materials. Porous deproteinized bovine bone mineral (PBBM), a biocompatible xenograft, has been used in different osseous deficiencies prior to or in conjunction with the placement of titanium implants. The different PBBM applications in fresh extraction sites, anatomic defects, and subantral floor elevation techniques are described. The use of an occlusive barrier membrane to regenerate bone via guided tissue regeneration principles was determined for each patient by clinical parameters. PBBM was well amalgamated and incorporated with the augmented hard tissue, but the transition between preexisting bone and the newly regenerated bone-like tissue was distinguishable by clinical examination even after 12 months. Grafted material was also identified using follow-up radiographs. In the presented cases, PBBM showed clinically satisfactory results as a biocompatible filler in bone augmentation procedures.

Adult↗

PubMed2001

Preprosthetic clinical crown lengthening procedures in the anterior maxilla.

Clinical crown lengthening procedures (CCLP) are used to enhance aesthetics and/or provide adequate tooth structure for placement and retention of a restoration while respecting the attachment apparatus. When restoration margins extend beyond the biologic width, inflammation and anatomic changes can develop. Anterior CCLP are indicated to increase the labial exposure of the clinical crown and/or the sound tooth structure coronal to the bone crest. Preservation of the interproximal papillae is mandatory to obtain desirable final results in the aesthetic region. This article illustrates various methods of CCLP used to achieve successful oral rehabilitation in the anterior maxilla.

Crown Lengthening↗

PubMed2001

Interproximal papilla augmentation procedure: a novel surgical approach and clinical evaluation of 10 consecutive procedures.

Periodontal plastic surgery enables enhanced esthetics in the anterior maxillary region. Reconstruction of the interdental papilla is one of the most challenging and least predictable of treatments. Several surgical and nonsurgical procedures to rebuild lost papillae have been presented; however, good results have been elusive. The purpose of the present study was to evaluate a novel surgical procedure based on an advanced papillary flap combined with a gingival graft intended to augment the soft tissue in the interdental area. The study comprised 10 consecutive papilla augmentation procedures performed in nine patients. Previous to the surgical procedure and at least 3 months postoperative, papilla contour measurements were carried out based on a papilla index score (PIS). PIS ranged from 0 to 2 preoperative (mean 1.0) and between 1 and 3 postoperative (mean 2.2). In eight procedures, PIS increased. Differences between pre- and postoperative PIS ranged from 0 to 3 PIS units (mean 1.2). Among the 10 procedures, there was an increase of 1 PIS unit in five, an increase of 2 PIS units in two, 3 PIS units in one, and no increase in the remaining two. This procedure is relatively easy to perform and offers a reliable solution to an esthetic problem. However, larger clinical and histologic follow-up studies are necessary before its long-term predictability can be established.

Adult↗

PubMed2000

Rotated palatal flap in immediate implant procedures. Clinical evaluation of 26 consecutive cases.

Immediate implant placement after tooth extraction is a successful treatment modality. Primary flap closure is important for satisfactory final results in these procedures. The purpose of this article was to evaluate a surgical approach that would enable predictable primary soft tissue closure over implants placed into fresh extraction sockets. In 24 patients, 26 consecutive implants were placed immediately following extraction of one anterior or premolar maxillary tooth. Primary closure was achieved by a surgical technique based on a rotated palatal flap (RPF), covering the implant. Deproteinized bovine bone was used as grafting material. The apicocoronal distance between the buccal alveolar crestal bone and the coronal aspect of the implant body was measured at time of implant placement (mean 2.6 mm, SD 1.72) and at second stage surgery (mean 0.6 mm, SD 0.70). The difference between both records was calculated. The mean gain in crestal bone was 2.0 mm (SD 1.69, P < 0.001). In 1 patient, where the implant cover screw became exposed early, crestal bone loss was noted. This technique offers a predictable valuable treatment approach to achieve and maintain primary soft tissue coverage and crestal bone regeneration over implants immediately placed within a bony envelope, after extracting maxillary teeth, without the use of barrier membranes.

Adult↗

PubMed2000

Displacement of the incisive foramen in conjunction with implant placement in the anterior maxilla without jeopardizing vitality of nasopalatine nerve and vessels: a novel surgical approach.

Accurate implant placement in the anterior maxilla is essential in achieving optimal prosthetic rehabilitation with proper function and acceptable esthetic and phonetic demands. One of the preferable prosthetic solutions to restore a missing maxillary incisor in young adults is by an implant-supported crown. Bone resorption together with an enlarged incisive foramen, challenge proper implant placement. A simultaneous procedure where the implant osteotomy site penetrated the incisive canal is presented. A configurated cortico-cancellous block graft core was adjusted to fit the foramen while its soft tissue content was pushed back posteriorly but not removed. This procedure was followed by an immediate implant placement. Re-entry at 9 months revealed solid bone support embracing the implant body. Although the size of the incisive foramen diminished significantly, the nasopalatine branches were still evident. No complications and/or loss of sensation were observed.

Adult↗

PubMed2000

Interproximal papillae reconstruction in maxillary implants.

BACKGROUND: Gingival esthetics has become an important factor in the overall success of most maxillary implant-supported restorations. Periodontal plastic surgery procedures may be used to enhance esthetics in the maxillary anterior region. The purpose of the present study was to evaluate a new surgical approach, performed at implant exposure, to reconstruct interdental papillae around maxillary implant-supported restorations. METHODS: The surgical procedure was performed on 32 patients, in which 36 consecutive single tooth osseointegrated implants were exposed in the anterior and premolar maxillary region. Previous to implant exposure and 6 months postoperatively, once the implant-supported restoration was in place, mesial and distal papilla contour measurements were calculated, based on a modification of the papillary index score (PIS). Statistical analysis consisted of paired t test, Pearson's correlation, and ANOVA with repeated measures. RESULTS: Preoperative PIS ranged from 0 to 3 and from 1 to 3 at the 6 months follow-up control. A mean of mesial and distal papilla, within the same tooth, was used for paired t test statistical analysis. A mean increase of 1.07 (SD 0.43) in PIS was statistically significant (P<0.001). At the second measurement, in no site was PIS smaller (0%) while in 64 sites PIS was higher (89%). In 51 papilla (71%) there was an increase of 1 PIS unit and 13 (18%) of 2 PIS units between both measurements. CONCLUSIONS: The presented surgical technique performed at second stage implant surgery was useful for partial or total interproximal papilla reconstruction adjacent to maxillary single-implant restorations.

Analysis of Variance↗

PubMed1999

Rotated split palatal flap for soft tissue primary coverage over extraction sites with immediate implant placement. Description of the surgical procedure and clinical results.

Immediate implant placement after tooth extraction is becoming a common procedure in implant-supported oral rehabilitation. However, lack of primary full flap closure can jeopardize final results. A surgical approach that would enable predictable primary soft tissue closure over implants placed into fresh extraction sockets is described and evaluated. This technique is based on a rotated deep split thickness palatal flap (RSPF) containing periosteum and connective tissue, covering the implant and/or a barrier membrane. In 29 patients, 33 consecutive implants were placed immediately post extraction of 1 or 2 anterior or premolar maxillary teeth. Patients were divided in 2 groups: Group A (15 patients; n = 18 sites) where no barrier membrane was used and Group B (14 patients, n = 15 sites) where an occlusive resorbable collagen membrane was used. Distance between the alveolar crestal bone and the coronal aspect of the implant was measured at time of implant placement (Group A: mean 1.9 mm, SD 1.16; Group B: mean 4.6 mm, SD 1.18) and at second stage surgery (Group A: mean 0.3 mm, SD 0.46; Group B: mean 0. 7 mm, SD 0. 7). The difference between both records (crestal bone formation) was calculated (Group A: 1.7 mm, SD 1.03; Group B: 3.9 mm, SD 1.12) and found to be statistically significant (P <0.0001). Crestal bone formation, relative to the initial bone crest-implant distance at time of implant placement was approximately 85% in both groups. In 4 sites (2 in each group), where the cover screws were exposed before second stage surgery, complete crestal bone regeneration did not occur. Use of a barrier membrane may be obviated in appropriate cases while placing implants into fresh extraction sites. This procedure offers a predictable treatment approach in achieving complete soft tissue coverage, while allowing for healing of bony defects in immediate implantation procedures.

Adult↗

PubMed1999

Split palatal flap. I. A surgical approach for primary soft tissue healing in ridge augmentation procedures: technique and clinical results.

This article describes a surgical procedure to predictably obtain primary closure over extraction sockets in the maxilla. The technique offers a valuable treatment approach for the achievement of primary soft tissue closure over bone grafts and/or occlusive osteopromotive membranes, although the use of an osteopromotive membrane may not always be necessary in cases of single-tooth extraction. The surgical technique is based on a split-thickness palatal flap in which the pediculated deep portion is rotated to cover the grafted alveolus or membrane. This procedure was used in a total of 40 sites in 32 consecutive patients; a barrier membrane was used in 20 sites. All treated sites allowed proper implant placement after healing. Two membranes became prematurely exposed and one was removed before implant surgery. Proper soft and hard tissue anatomy was predictably obtained prior to implant placement. This surgical procedure is useful in preserving and/or augmenting the alveolar ridge prior to or during implant placement in cases of advanced alveolar bone loss.

Adult↗

PubMed1999

Split palatal flap. II. A surgical approach for maxillary implant uncovering in cases with reduced keratinized tissue: technique and clinical results.

It is generally accepted that a more ideal and functional soft tissue-implant interface can be established if there is an adequate zone of keratinized mucosa around endosseous dental implants. The purpose of this article was to describe a surgical procedure, based on the use of a split palatal flap, which predictably creates or increases the zone of keratinized tissue around implants at the time of implant uncovering. It is especially useful for maxillary implants with a nonexistent or minimal width of keratinized buccal tissue. The study comprised 34 implants in the maxillae of 8 patients, who were chosen because they had minimal or nonexistent buccal keratinized gingiva prior to implant uncovering. Following healing, between 2 and 5 mm of keratinized gingiva (mean 3.7 mm) could be measured buccally at all abutments. Postsurgical inconveniences were minimal. The use of a split palatal flap at implant uncovering minimizes the number of surgical stages and sites necessary, while predictably providing an adequate zone of buccal keratinized gingiva.

Connective Tissue↗

PubMed1998

The application of deproteinized bovine bone mineral for ridge preservation prior to implantation. Clinical and histological observations in a case report.

Alveolar ridge preservation following tooth extraction is important when implant-supported oral rehabilitation is considered. The ability to maintain the ridge allows implant placement in an ideal position, fulfilling both functional and esthetic demands. A deproteinized bovine bone mineral (DBBM) was used as a socket site filler material to maintain ridge configuration, without applying an occlusive membrane. The material was grafted and packed onto the socket sites immediately after extractions, and subsequently primary soft tissue closure was attempted. The ridge healed for 9 months before the second surgical procedure, in which the implant was placed. New bone formation was observed in all histological specimens. DBBM particles adhered to a highly osteocyte-rich woven and lamellar-type bone. Clinically and histologically, this report demonstrated DBBM particles to be an effective biocompatible filler agent in extraction sockets for ridge preservation prior to titanium fixture implantation. Randomized controlled clinical trials are needed to fully evaluate the usefulness of this material in ridge preservation after tooth extraction.

Adult↗

PubMed1997

Effect of non-erupted third molars on roots of approximal teeth. A radiographic, clinical and histologic study.

This study was undertaken to evaluate clinically and histologically root resorption in extracted human second molars in close proximity to non-erupted third molars. The control group consisted of extracted second molars that were proximal to fully erupted third molars. Eight out of the 11 teeth in the study group presented different degrees of radiographic root resorption, nine presented clinical resorption, and all 11 had histologic evidence of root resorption. In the control group, no signs of root resorption were seen radiographically or clinically. Histologically, limited sites of resorption were identified in all teeth, which were partially repaired by cellular cementum. Histologic observation of study specimens revealed root surface resorption in 10 out of the 11 teeth, one showing replacement resorption as well. Inflammatory resorption was observed in the three most advanced cases in the study group. Reparative cementum partially lining resorbed areas was evident in all teeth with surface resorption. Within the limits of this study, radiographic identification of distal root resorption of second molars in close proximity to non-erupted third molars appears reliable. The findings may support the hypothesis that the presence of a non-erupted third molar in close proximity to the distal root of the second results in root resorption.

Adult↗

PubMed1996

Effect of non-erupted 3rd molars on distal roots and supporting structures of approximal teeth. A radiographic survey of 202 cases.

Root resorption of 2nd molars in proximity to non-erupted 3rd molars has been widely reported. The purpose of this study was to determine the prevalence of root resorption in second molars adjacent to non-erupted third molars. Its association to age and gender of the patient, location and inclination of the non-erupted third molar and to distal bone support of the 2nd molars was analyzed. A radiographic survey of 202 periapical radiographs taken in patients with clinically missing third molars was conducted. 3 examiners independently evaluated the radiographs and only those cases where at least 2 observers agreed were included in this report. Statistical analysis was performed on 186 radiographs. Associations were analyzed with the Pearson chi 2 test. Radiographic evidence of root resorption was found in 45 2nd molars (24.2%) of which 12 (6.5%) showed moderate to complete root resorption. Non-erupted tooth apical position and mesio-inclination of 60 degrees or more relative to the distal root of the second molar were significantly associated with root resorption (p = 0.01368 and p = 0.0194, respectively). Resorption was positively associated with age of patient (p = 0.00606). These results may support early extraction of impacted 3rd molars especially in cases with a mesio-angulation of 60 degrees or more and an apical location in proximity to the distal root of the 2nd molar.

Adolescent↗

PubMed1996

Alveolar ridge preservation following extraction of maxillary anterior teeth. Report on 23 consecutive cases.

The purpose of this article was to clinically evaluate the predictability of a surgical procedure to preserve the alveolar ridge after extracting maxillary anterior teeth with advanced bone loss. This procedure is indicated when a tooth-supported fixed partial denture will rehabilitate the area. Non-resorbable hydroxyapatite crystals are used as graft material and a rotated pediculated split thickness palatal flap covers them. Twenty-three patients who were treated with this procedure were followed for 12 to 24 months. Results were predictable with minimal postoperative ridge deformation. Indications for this procedure are discussed.

Adult↗