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Biomedical subjects

Carlos E Nemcovsky

Publications and source records attributed to Carlos E Nemcovsky.

At least 19 recordsLinked to original sources
PubMed2026

Decoding regional keratinization in human oral mucosa through high-resolution spatial transcriptomics.

Oral mucosa exhibits region-specific keratinization, essential for periodontal health, yet the spatial and molecular mechanisms driving these differences remain poorly understood. This study aimed to generate a high-resolution spatial transcriptomic atlas of the human oral mucosa around the mucogingival junction, to reveal stromal-epithelial interactions, that distinguish keratinized from non-keratinized programs. Formalin-fixed paraffin-embedded specimens from the mucogingival junction area of two healthy donors were analyzed with the 10 × Genomics Visium HD platform, yielding two keratinized and two non-keratinized regions. Spatial clustering, pseudotime trajectory inference, cell-type integration with a single-cell reference, and ligand-receptor network analysis were applied to delineate epithelial and stromal compartments. Sixteen reproducible clusters, recapitulating tissue architecture, were identified and revealed distinct transcriptional signatures, distinguishing gingiva from lining mucosa. Pseudotime analysis revealed bifurcating epithelial lineages, originating from a shared basal progenitor layer into keratinized and non-keratinized programs. Gingival keratinization was driven by stromal collagen ligands (COL1A1, COL1A2, COL6A1, COL6A2) engaging epithelial receptors (CD44, SDC1), further reinforced within the epithelium by desmosomal adhesion via DSG1-DSC2/3. Gingival keratinization emerges from integrated stromal collagen signaling and epithelial adhesion. This spatially resolved framework advances understanding of oral mucosal specialization and provides a foundation for biologically guided regenerative therapies.

Humans↗
PubMed2006

Comparative study of two root coverage procedures: a 24-month follow-up multicenter study.

BACKGROUND: Treatment alternatives to cover exposed root surfaces include free grafts, pedicle flaps, and barrier membranes. This 24-month follow-up study clinically evaluated the long-term effect of a coronally advanced flap procedure with the additional use of enamel matrix derivative (EMD) to treat gingival recession versus the subpedicle connective tissue graft (CTG) procedure. METHODS: Miller Class I or II buccal recession-type defects in the anterior teeth or premolars in 65 patients (28 in EMD and 37 in CTG groups) were treated in several centers. At baseline and 12 and 24 months post-treatment, vertical recession defect (VRD), height of keratinized tissue (HKT), and probing depth (PD) were recorded, and the percentage of root coverage (PRC) of the original defect was calculated. Student t test, analysis of variance, and analysis of covariance were used for statistical analyses. RESULTS: At 12- and 24-month evaluations, PRC was 73.2% (SD=15.58%) and 76.9% (SD=16.77%) in the EMD group and 86.8% (SD=12.48%) and 84.3% (SD=13.32%) in the CTG group, respectively (P<0.001). Differences between groups were statistically significant (P=0.002). Baseline HKT was 1.07 mm (SD=0.66 mm) in the EMD group and 1.65 mm (SD=0.92 mm) in the CTG group. At 12 and 24 months, values were 1.75 mm (SD=0.59 mm) and 2.25 mm (SD=0.52 mm) in the EMD group and 4.24 mm (SD=0.89 mm) and 4.05 mm (SD=0.94 mm) in the CTG group, respectively. Differences in HKT were statistically significant within (EMD: P<0.001; CTG: P=0.017) and between (P<0.001) groups. CONCLUSIONS: Both treatments proved clinically successful. CTG treatment showed a higher percentage of root coverage and HKT increase. EMD is a valuable, long-term effective treatment alternative to achieve root coverage together with an increase in HKT.

Adolescent↗
PubMed2006

Effect of enamel matrix protein derivative on healing of surgical supra-infrabony periodontal defects in the rat molar: a histomorphometric study.

BACKGROUND: Enamel matrix protein derivative (EMD) has proven to enhance periodontal regeneration in human and animal studies. The present histomorphometric study evaluated healing of combined supra-infrabony periodontal defects with EMD. METHODS: The study comprised two groups of 10 Wistar rats each, 7 to 8 months old. Bony defects were created on the mesial aspect of the mesial root of the first maxillary molar. The root surface was planed and 24% EDTA gel applied for 2 minutes and then rinsed with water. In the study group, EMD was applied, and in the control group, only propylene glycol alginate was applied. Animals were sacrificed 12 weeks after surgery, and block sections were removed, demineralized, and embedded in paraffin. For histomorphometric analysis, three sections from the central area of the defect were selected. Root, surgical defect, epithelial attachment, sulcus, supracrestal connective tissue, ankylosis, and the length and area of new cementum and new bone were measured. RESULTS: No statistically significant differences between the two groups were found for root and defect measures. The remaining parameters were calculated as a percentage of the defect. In the study group, smaller gingival recession (P = 0.05), deeper gingival sulcus (P = 0.05), and shorter junctional epithelium (P = 0.01) were found. New cementum was observed in the study group only (P = 0.02). Ankylosis was six times larger in the control group but not statistically significant. New bone formation was similar in both groups. CONCLUSION: Enamel matrix protein derivative enhanced periodontal healing in this model by reducing gingival recession and junctional epithelium along the root surface and enhancing the formation of new cementum.

Alveolar Process↗
PubMed2006

Experimental intrabony and periodontal defects treated with natural mineral combined with a synthetic cell-binding Peptide in the canine: morphometric evaluations.

BACKGROUND: A synthetic peptide (P-15) analog of collagen added to anorganic bovine bone mineral (ABM) has recently been used as an enhanced bone graft material (ABM/P-15). The objective of this study was to test the contribution of ABM/P-15 in a new putty form (PEP) in two experimental membrane-protected defects: periodontal and intrabony. Its efficacy as filler biomaterial in guided tissue regeneration (GTR) and guided bone regeneration (GBR) procedures was evaluated histologically and morphometrically. METHODS: In the maxillary canines, a facial mucoperiosteal flap was raised bilaterally in nine dogs. Two circular defects, 5 mm in diameter and 2 mm in depth, were made on each side: a fenestrated periodontal on the canine root and an intrabony in the alveolar diastema, anteriorly. PEP particles filled both defects on one side; the contralateral side was blood filled (control). All surgical sites were covered with a bioabsorbable membrane. Histologically, at 4 months, tissue blocks were made using the cutting/grinding non-decalcification method followed by morphometric analysis. In the periodontal fenestration root surface, the linear percentage of new cementum (%CEM), area percentage of new bone (%NB), and residual biomaterial particles (%PEP) were calculated. These same measurements were calculated at the intrabony sites, except cementum. The amount of direct NB to PEP contact was measured to assess the osteoconductivity level (OSC). The Pearson correlation test was used to evaluate any significant relationship between the different measured parameters. RESULTS: In the grafted and non-grafted fenestration root surface defects, %CEM averaged 59.5% and 73.9% (P <0.02), respectively; %NB averaged 36.1% and 31.4%, respectively; and %PEP averaged 20.6%. The mean percentage of OSC was 52.4%. In the intrabony grafted and non-grafted sites, %NB averaged 50.7% and 60.1%, respectively (P <0.02). Residual %PEP averaged 26.1%, and OSC averaged 35.6%. At the intrabony sites, higher %NB and lower %OSC were found compared to the fenestration sites (P <0.001 and P <0.03, respectively). Correlation analysis showed a negative correlation between %NB and %PEP at the fenestration defects. In between the two defect types, %OSC was significantly correlated (P <0.05). CONCLUSIONS: ABM/P-15 putty showed osteoconductive and biocompatible qualities. However, at 4 months in this model, no enhanced regeneration was present compared to a higher CEM and NB growth detected at non-grafted membrane-protected sites.

Absorbable Implants↗
PubMed2005

Healing of dehiscence-type defects in implants placed together with different barrier membranes: a comparative clinical study.

OBJECTIVE: Premature exposure of membranes used in guided bone regeneration (GBR) results in decreased bone formation. The effect of an expanded polytetrafluoroethylene (e-PTFE) and two collagen membrane on bone healing of buccal dehiscence defects around implants in cases with and without premature membrane exposure was clinically evaluated. METHODS: Three groups were established: Group OS (Ossix, n=73 implants, 41 patients), Group BG (Bio-Gide, n=53 implants, 28 patients) and Group GT (e-PTFE, Gore-Tex, n=34 implants, 17 patients). Defect height and width were measured at the time of implant placement and at second stage surgery. Surface area was calculated as half ellipses. When several implants were placed simultaneously, a mean of their defect width and height was calculated. RESULTS: Mean percentage reduction of defect area (92.2+/-13.78% Group OS, 94.6+/-6.69% Group BG, and 97.3+/-4.91% Group GT) and height (81.6+/-23.19%, 85.4+/-12.26%, and 93.4+/-9.39% respectively) did not show statistically significant differences between groups. Differences between groups were not statistically significant for all parameters when cases without spontaneous membrane exposure were compared. However, differences were significant when spontaneous membrane exposure occurred. Mean percentage reduction of defect area among cases where membrane exposure occurred was 91.5+/-10.86% Group OS, 71.5+/-8.61% Group BG, and 73.7+/-13.97% Group GT. Mean percentage reduction of defect height among cases with membrane exposure was 76.4+/-18.28%, 53.4+/-9.86%, and 49.4+/-11.05%, respectively. CONCLUSIONS: Premature exposure of membranes and subsequent and consequent exposure of implants results in impaired bone healing. Certain barrier membranes, as used in group OS, are apparently capable of supporting gingival healing even when prematurely exposed that could be advantageous in GBR procedures.

Analysis of Variance↗
PubMed2005

The amount of newly formed bone in sinus grafting procedures depends on tissue depth as well as the type and residual amount of the grafted material.

OBJECTIVES: Bone replacement substitutes are almost unavoidable in augmentation procedures such as sinus grafting. The objective of the present study was to evaluate the osteoconductive capability of two different scaffold fillers in inducing newly formed bone in this procedure. MATERIAL AND METHODS: Sinus floor augmentation and implant placement were carried out bilaterally in 12 patients. Bovine bone mineral (BBM) was grafted on one side and beta-tricalcium phosphate (beta-TCP) on the contralateral side. Both were mixed (1:1 ratio) with autogenous cortical bone chips harvested from the mandible by a scraper. Hard tissue specimen cores were retrieved from the augmented sites (at the previous window area) at 12 months. Decalcified sections were stained with haematoxylin-eosin and the fraction area of new bone and filler particles was measured. In addition to the effect of the filler on new bone formation, the latter was tested to determine whether it correlated with the tissue depth and residual amount of the grafted material. RESULTS: Bone area fraction increased significantly from peripheral to deeper areas at both grafted sites in all cores: from 26.0% to 37.7% at the beta-TCP sites and from 33.5% to 53.7% at the BBM-grafted sites. At each depth the amount of new bone in BBM sites was significantly greater than that in TCP sites. However, the average area fraction of grafted material particles was similar in both fillers and all depth levels (beta-TCP=27.9-23.2% and BBM=29.2-22.6%, NS). A significant negative correlation was found between bone area fraction and particle area fraction at the middle (p=0.009) and deep (p=0.014) depths in the beta-TCP sites, but not at the BBM sites. CONCLUSION: At 12 months post-augmentation, the two examined bone fillers, beta-TCP and BBM, promoted new bone formation in sinus grafting but the amount of newly formed bone was significantly greater in BBM-grafted sites. However, both exhibited similar residual grafted material area fraction at this healing period. This could imply that BBM possesses better osteoconductive properties.

Adult↗
PubMed2005

Effect of air-polishing devices on the gingiva: histologic study in the canine.

OBJECTIVES: The aim of this study was to evaluate histologically the immediate effect of two types of air-polishing devices (APDs) on the gingiva. MATERIAL AND METHODS: The buccal gingiva in four mongrel dogs was exposed to 5, 10 and 20 s of instrumentation, applying a hand-piece type of APD (HP-APD) PROPHYflex and a stand-alone type of APD (SA-APD) Jetpolisher in a split-mouth design. Immediately after treatment, the exposed gingiva was excised by sharp dissection and fixed in 10% buffered formalin. For each specimen, 15 sections, 20 microm apart, corresponding to the central part of the treated and control untreated gingiva were cut and stained with haematoxylin and eosin. Stained sections were examined histomorphometrically for keratin width and epithelial cell layer (ECL) (prickle and basal cell layers) width. Extent of erosion was expressed as loss of keratin and ECL compared with control. RESULTS: Microscopic examination presented changes in keratin and ECL, including keratin detachment and disruption of the normal ECL architecture. The erosive changes in the gingiva caused by both APD, positively correlated with instrumentation time (p<0.001) and type of instrument (p=0.008). Keratin loss was significantly higher for SA APD than for the HP APD in each time interval (p=0.019). Following exposure for 5 s, both APD caused a 25% loss of the ECL. Exposure for 10 and 20 s revealed a significantly greater ECL loss caused by the SA-APD than the HP-APD (p=0.018). Exposure for 20 s was the only time interval that presented the area of total epithelium erosion with SA-APD causing significantly more (p=0.002) areas of total epithelial erosion than the HP-APD. CONCLUSION: Gingiva exposure to air-polishing slurry delivered by APD caused localized trauma because of epithelial erosive changes with severity, positively correlated with instrumentation time and design principles of the applied APD. The clinician should be aware of the potential insult of the gingiva when applying the APD and careful precautions should be taken.

Animals↗
PubMed2004

A multicenter comparative study of two root coverage procedures: coronally advanced flap with addition of enamel matrix proteins and subpedicle connective tissue graft.

BACKGROUND: Free grafts, pedicle flaps, and barrier membranes have been used to cover exposed root surfaces. The aim of the present study was to evaluate the clinical efficacy of a coronally advanced flap procedure with the additional use of enamel matrix protein derivative (EMD) to treat gingival recession and to compare it to the subpedicle connective tissue graft procedure (CTG). METHODS: The study was conducted in six different periodontal clinics. Miller Class I or II buccal recession type defects in the anterior or premolar teeth were treated in 70 consecutive patients, 30 with EMD and 40 with CTG. At baseline and 6 and 12 months post-surgical treatment, vertical recession defect, defined as the distance from cemento-enamel junction to gingival margin; width of keratinized tissue; and probing depth were recorded and the percentage of coverage of the original defect was calculated. Statistical analyses consisted of t-test, analysis of variance, and analysis of covariance. RESULTS: At 6 months, percent of root coverage was 77.4% +/- 11.92% in EMD and 84.1% +/- 11.97% in CTG (statistically significant at P = 0.024). At 12 months, percent of root coverage in EMD was 71.7% +/- 16.14% and 87.0% +/- 12.22% in CTG; again, differences between groups were statistically significant (P < 0.001). Differences between the 6- and 12-month vertical recession defect and percent of root coverage recordings within each group were also statistically significant. CONCLUSIONS: The connective tissue graft procedure was superior to the coronally positioned flap with the addition of enamel matrix proteins derivative in percentage of coverage and increase in width of keratinized tissue. The EMD procedure is a predictable treatment for root coverage that is relatively easy to perform and presents low patient morbidity, and is appropriate especially where a substantial increase in the width of keratinized tissue is not of prime importance.

Adolescent↗
PubMed2004

Bone apposition in surgical bony defects following orthodontic movement: a comparative histomorphometric study between root- and periodontal ligament-damaged and periodontally intact rat molars.

BACKGROUND: The influence of orthodontic tooth movement with diminished periodontal support is unclear. The aim of the present study was to evaluate bone healing in surgical defects following orthodontic tooth movement with and without periodontal ligament (PDL) and root surface damage. METHODS: The study comprised 33 adult male Wistar rats, divided into two groups: group 1 (n = 14) with bony defect and no root damage and group 2 (n = 19) with periodontal bony defect including root/PDL damage on the mesial root of the maxillary first molar. One week after a surgical defect was created, orthodontic protraction of the right maxillary first molar was initiated in both groups. After 2 weeks of protraction, retention of 1 week was established; at the end of this period block sections were made. Histomorphometric analysis through light microscopy of decalcified tissue was performed. Results were statistically analyzed using independent samples t test and analysis of variance (ANOVA) with repeated measures. RESULTS: Differences between groups in total area of bone defect and bone apposition were not statistically significant. Bone apposition calculated as percentage of the bone defect was significantly (t-test) greater (P = 0.002) in group 2 (46.21%) than in group 1 (24.95%). Within each group, area of bone apposition was significantly (ANOVA) greater in the distal than in the mesial quadrants of the bony defect (P = 0.006) and in the apical than the occlusal ones (P = 0.021). CONCLUSION: Following orthodontic tooth movement, periodontal bony defects showed enhanced bony healing compared with alveolar bone defects with no direct association with the periodontal attachment apparatus.

Alveolar Bone Loss↗
PubMed2004

Tetracycline impregnation delays collagen membrane degradation in vivo.

BACKGROUND: Guided tissue and bone regeneration using bioabsorbable collagen membranes is a common practice. Collagen promotes progenitor cell adhesion, chemotaxis, homeostasis, and physiologic degradation with low immunogenicity, which makes it an ideal material for barrier preparation. Collagen membranes have to maintain integrity for a proper time, thus ensuring successful cell exclusion. Early collagen membrane degradation is detrimental for the success of regenerative procedures. This in vivo study was conducted to evaluate the effect of soaking collagen membranes in different tetracycline hydrochloride (TCN) concentration solutions on its degradation. METHODS: Five mm disks of collagen membrane were soaked in either 100 mg/ml TCN (group 100) or 50 mg/ml TCN (group 50); a group of non-treated disks served as controls. All disks were labeled with aminohexanoyl-biotin-N-hydroxy-succinimide ester (biotin) and implanted in rat calvaria bone. Block sections were taken after 3 weeks and histological slides stained with horseradish peroxidase (HRP) to detect remnants of biotinylated collagen. Staining intensity was analyzed by image-analysis software taking quadruplicate measurements of a 500 microm2 area each. Data were analyzed using analysis of variance (ANOVA) with repeated measures and paired t test with Bonferroni correction. RESULTS: Staining intensity of membranes in group 100 was > 5-fold higher than the control while group 50 exhibited > 11-fold higher intensity than the control and > 2.5-fold higher than the 100. All of these differences were statistically significant (P < 0.001). CONCLUSION: Soaking collagen membranes in 50 mg/ml TCN solution is a useful, practical, and simple tool to slow membrane degradation.

Absorbable Implants↗
PubMed2004

Sinus floor augmentation through a rotated palatal flap at the time of tooth extraction.

Rapid crestal bone resorption following maxillary tooth loss is further accentuated in the posterior regions because of pneumatization and enlargement of the maxillary sinuses. A treatment rationale that allows preservation and/or augmentation of vertical available bone at the time of posterior maxillary tooth extraction may offer numerous therapeutic benefits. The present study comprised 14 patients in whom 18 posterior maxillary teeth with no evident bone between the tooth apex and sinus floor, as estimated through preoperative radiographic analysis, were carefully extracted using a palatal approach. The empty alveolus was thoroughly debrided and incrementally filled with tricalcium phosphate. The graft material was gently pushed beyond the empty alveolus to elevate the sinus membrane using an osteotome. Primary soft tissue closure over the grafted sites was achieved by a rotated palatal flap. The distance between bone crest and sinus floor was radiographically estimated 6 to 7 months after the first procedure. Another procedure was then carried out to place the 10- to 14-mm implants, together with a bone-added osteotome sinus floor elevation. At uncovering, all implants were clinically stable, with no signs of infection. The presented surgical procedure performed at the time of extraction of posterior maxillary teeth in close proximity to the sinus floor allowed placement of implants of proper length and width, together with a bone-added osteotome sinus floor elevation during a second procedure.

Adult↗
PubMed2004

Rotated palatal flaps: A functional and aesthetic solution in endentulous sites.

Resorption of alveolar process generally occurs following tooth extraction, and this process may cause a variety of jaw deformities. Bone deformities in the aesthetic zone impair the appearance, quality, and prognosis of the definitive restoration. The rotated palatal flap is a surgical modality that can be used to reduce or prevent alveolar resorption and assist in the repairing of exisiting defects. This presentation demonstrates the application of the rotated palatal flap in a variety of clinical cases as a means of addressing such resorption.

Adult↗
PubMed2003

Scanning electron microscope evaluation of two methods of resharpening periodontal curets: a comparative study.

BACKGROUND: Effective root planing demands sharp cutting edges on dental curets. However, after several strokes, they become dull and must be resharpened frequently. The purpose of this study was to evaluate by scanning electron microscopy (SEM) the quality of the cutting edge of periodontal curets resharpened by 2 different methods. METHODS: Forty new detachable Gracey curets were used in this study. After similar blunting, all instruments were resharpened either with 10 strokes using an Arkansas fine-grit sharpening stone (AR), or with 7 strokes using a high-grit and -density aluminum oxide stone (CH). The cutting edges of each instrument were examined using SEM at 1 mm and 2 mm from the tip before and after the resharpening procedure. Bevel measurement and the amount of functional and non-functional wire edges (WE) on the cutting edge were evaluated. Data were statistically analyzed using analysis of variance (ANOVA) with repeated measures, 2-way ANOVA, and Fisher's exact test. RESULTS: After blunting and resharpening, differences in bevel between groups were statistically non-significant. Generally, after resharpening, there were significantly more functional and non-functional WE in the AR group than in the CH group. There were significantly more instruments with a complete absence of WE in the CH group. CONCLUSIONS: The CH stone resulted in a smoother and better cutting edge than the AR stone. The procedure was easy to perform and required fewer strokes of the curet on the stone.

Aluminum Oxide↗
PubMed2003

Qualitative and quantitative expression of bovine bone mineral in experimental bone defects. Part 1: Description of a dog model and histological observations.

BACKGROUND: The purpose of this study was to evaluate histologically the contribution of inorganic bovine bone biomaterial in a new experimental bone defect in dogs at different healing periods and to examine newly formed bone around the grafted mineral particles and their relationship in membrane-protected (test) and non-protected intrabony (control) defects. METHODS: Four round intrabony defects, 5 x 4 mm were made bilaterally (at different times) on the lateral bony mandibular angle in eight dogs. Two defects were filled with bovine bone mineral (BBM) particles and two remained non-grafted but were blood clotted. A collagen membrane covered each defect type (n = 4). This procedure was repeated on the contralateral side at a different given time to obtain two different healing periods in each dog. Thus, four specimens were obtained at 3, 6, 12, and 24 months postoperatively for each healing period. The non-decalcification method (Donath technique) with Stevenel's blue and van Gieson's picro fuchsin staining was used for histological examination. RESULTS: Newly formed bone was observed at all examined defect types. The BBM particles were clearly evident regardless of the healing period. At 3 and 6 months, newly formed bone, woven in nature, was incorporated with the grafted particles. High cellular bone with occasional osteoclasts was noted towards the surface of the mineral particles. No substantial difference was observed between the protected and the non-protected defects except for higher ossified centers around the membrane-protected defects. At the non-grafted sites, the membrane-protected defect showed newly formed bone near the bony walls, and particularly under the membrane, establishing a bony bridge over the defect at the healing periods. The non-grafted unprotected defect (control) showed bone formation only at the base and close to the bony walls leaving a healed concave configuration. At 1 and 2 years, the grafted sites showed full bone healing configuration. However, the grafted particles still dominated the previous defect area and were completely surrounded by the newly formed bone. Osteons and lamellar bone arrangement were established but the bone was still highly cellular and osteoclasts could still be identified. The non-grafted membrane-protected sites showed excellent bone healing although areas of non-mineralized soft tissue were often seen. The control sites healed but still presented with a concave surface configuration. CONCLUSIONS: BBM biomaterial is a highly osteoconductive material. In a 4-wall bony defect, newly formed bone was well evident in establishing excellent bone healing configuration with or without a regenerative biological barrier. The grafted material dominated the experimental sites with no substantial resorption at any healing period up to 2 years observation.

Alveolar Bone Loss↗
PubMed2003

Qualitative and quantitative expression of bovine bone mineral in experimental bone defects. Part 2: Morphometric analysis.

BACKGROUND: The purpose of this study was to evaluate morphometrically the rate of resorbability of an inorganic bovine bone material in a standardized intrabony defect in dogs whether protected or unprotected by a bioabsorbable membrane at different healing periods, and to assess histomorphometrically the amount of osteoconductivity of this material and final healing site configuration. METHODS: In eight mongrel dogs, four round intrabony defects (5 x 4 mm) were made on the lateral mandibular angle, bilaterally at a different given time. Bovine bone mineral randomly filled two sites, while the other two were left with blood clot. A bioabsorbable collagen membrane covered each type of defect. The blood clotted uncovered sites served as controls. Section blocks for histology were made at 3, 6, 12, and 24 months. Following the non-decalcification method and staining with Stevenel's blue and van Gieson's picro fuchsin, morphometric analysis was performed on each specimen lesion type. RESULTS: Average bone area fraction at the bovine bone mineral uncovered sites (BBM) was 23.1%, 44%, 63.4%, and 58.8% at 3, 6, 12, and 24 months, respectively. Differences were statistically significant between 3 to 6 and 6 to 12 months (P<0.001). Average particle area fraction was 35.6%, 29%, 27.6%, and 26.8% at the respective periods. Differences were statistically significant between 3 to 6 months (P<0.05). In the bovine bone mineral membrane-protected (BBMM) sites, average bone area fraction was 26.4%, 51.7%, 61.2%, and 52.4% at 3, 6, 12, and 24 months, respectively. Differences were statistically significant between 3 to 6 months (P<0.05). Average particle area fraction was 37.9%, 29.8%, 26.8%, and 33.7%, respectively. Differences between the two sites with regard to the newly formed bone and particle presence were insignificant. In both, the increasing pattern of osteoconduction as expressed by the osteoconductivity test along the different healing periods was similar, as well as the decreasing pattern of the remaining concavity of the healing site configuration. Multiple comparison analysis of bone area fraction disclosed statistically significant superiority (P<0.05) of the membrane-ungrafted sites over BBM sites at 3 and 6 months and over BBMM sites at 6 months. Bone area fraction of the BBMM sites (51.7%) was statistically higher than the control sites (37.5%) (P<0.05). At 12 months, all test sites were statistically superior over the controls with regard to the regenerated bone and its healing configuration; i.e., remaining concavity of the defect. The healing site configuration of the test sites was persistently different from the control sites at 24 months. CONCLUSIONS: Newly formed bone and complete healing were evident in the BBM and BBMM sites. The membrane contributed no substantial benefits. Bovine bone particle resorptive phase was observed up to 6 months. Thereafter, there was no continued resorption up to 24 months observation.

Alveolar Bone Loss↗
PubMed2003

Nonceramic hydroxyapatite bone derivative in sinus augmentation procedures: clinical and histomorphometric observations in 10 consecutive cases.

A synthetic, nonceramic resorbable hydroxyapatite (R-HA) was applied to augment the subantral area in 10 consecutive sinus lift procedures in humans. Implants were simultaneously placed in eight patients; in the remaining two, where residual bone height was less than 3 mm, a two-stage surgical approach was carried out. The aim of the study was to examine, clinically and histopathologically at 12 months, the healing pattern of these augmented sinuses around the implants. In the simultaneous technique, radiopaque grafted mineral surrounded the implants. In the two-stage technique, R-HA particles filled the augmented site and were confined to the subantral area. At the uncovering phase, all implants (n = 36) were stable, with no clinical bone resorption around the cervix. A 2.5-mm trephine bur was used to collect specimens from the 10 augmented sites at the lateral-deep area. Histologically, new bone formation was evident in all examined cores. R-HA particles were primarily surrounded by newly formed bone, mostly woven bone, in different stages of remodeling. However, in the deep areas of the specimen cores, lamellar bone fragments were also seen. Morphometric measurements showed that the mean bone area of the 10 sites was 28.1% at the lateral/external side and 37.8% at the deep/inward side. Under polarizing microscopy, the mean lamellar:woven bone ratio was 1:7.2 at the lateral side and 1:4.2 at the deep end. Differences were statistically significant. R-HA proved to be a suitable filler material for osseointegrated implants in sinus augmentation procedures, since it showed both biocompatible and osteoconductive properties.

Adult↗
PubMed2002

Healing of marginal defects at implants placed in fresh extraction sockets or after 4-6 weeks of healing. A comparative study.

The purpose of this study was to evaluate the clinical healing of buccal marginal defects around implants placed in fresh extraction sockets or after several weeks together with barrier membranes and bone graft. Two implant placement protocols were compared: delayed-immediate sites primarily closed by a rotated (full thickness) palatal flap (RPF) at the time of tooth extraction and implantation after 4-6 weeks (Group 1, 24 patients, n = 31 implants) and immediate procedures (into fresh extraction sockets) primarily closed by a rotated split palatal flap (RSPF) (Group 2, 19 patients, n = 23 implants). One or two proximal maxillary implants were simultaneously placed. Height and width of the marginal defect were measured at the time of implant placement and after 6-8 months, at second stage surgery. For Groups 1 and 2, the mean percentage of the reduced defect height was 91.2% (+/- 9.12) and 77.4% (+/- 16.92), respectively, and the mean percentage area of the reduced defect was 97.2% (+/- 3.85) and 90.2% (+/- 9.15), respectively. Differences between groups were statistically significant. Groups were subdivided according to number of implants placed (one or two). Spontaneous implant cover screw exposure was seen only in Group 2. There was an association between the number of implants simultaneously placed and the occurrence of spontaneous exposure. The mean percentage reduction of the defect height and area was significantly smaller where there was spontaneous exposure. Significant differences were found for mean percentage reduction of the defect height and area only between the two implant subgroups within each group.

Alveolar Ridge Augmentation↗