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Biomedical subjects

Marco Degidi

Publications and source records attributed to Marco Degidi.

At least 19 recordsLinked to original sources
PubMed2007

Wide-diameter implants: analysis of clinical outcome of 304 fixtures.

BACKGROUND: In the last decade, the use of wide-diameter implants (WDIs; diameter >3.75 mm) has increased. Although good clinical outcomes have been reported in recent literature, there are few reports on this topic. Thus, we planned a retrospective study on a large series of WDIs to evaluate the clinical outcome. METHODS: From October of 1996 to December of 2004, 205 patients were operated on, and 304 WDIs were inserted. The mean postloading follow-up was 30 months. Implant diameter and length ranged from 5.0 to 6.5 mm and from 8.0 to 15 mm, respectively. Because only five of 304 implants were lost (i.e., a survival rate of 98.4%) and no statistical differences were detected among the studied variables, no or reduced crestal bone resorption (CBR) was considered an indicator of success to evaluate the effect of several host-, surgery-, and implant-related factors. A general linear model (GLM) was performed to detect variables that were associated statistically with CBR. RESULTS: Only five of 304 WDIs were lost, and no differences were detected among the studied variables. On the contrary, the GLM showed that distal teeth (i.e., premolars and molars), small implant diameter (i.e., 5.0 and 5.5 mm), and short implant length (i.e., <13 mm) correlated with a statistically significant lower CBR. CONCLUSION: The use of WDIs is a viable treatment option, and it may provide benefits in posterior regions for long-term maintenance of various implant-supported prosthetic rehabilitations.

Adolescent↗
PubMed2006

Comparative evaluation of the peri-implant bone tissue mineral density around unloaded titanium dental implants.

OBJECTIVE: The mechanical properties of bone are greatly influenced by the percentages of organic and mineral constituents. Nevertheless, the information about the mineral content on a microscopic scale in peri-implant bone is scarce. The aim of this work was to analyze the bone mineral density of peri-implant bone under different techniques. DESIGN: Five unloaded titanium dental implants with a micro-structured surface (three XiVE plus and two Frialit 2, DENTSPLY-Friadent, Mannheim, Germany) were retrieved from the mandible of five patients after a 6-month period. scanning electron microscopy with backscattered electron signal (BSE), light microscopy (LM) with a double staining technique, fluorescence microscopy and confocal laser microscopy were used for measuring microscopic mineral content variations in peri-implant bone. Histomorphometry and image intensity (grey level) were evaluated using a software package for image analysis. RESULTS: The low mineral density index (LMDI) for LM was of 29.2+/-3.1 (mean+/-S.D.), while the high mineral density index (HMDI) was of 88.2+/-3.6 (mean+/-S.D.). The one-way ANOVA analysis showed a significant difference (P<0.001) among the groups. The pairwise Holm-Sidak test identified the differences among HMDI indexes for both LM and SEM values and also for cross-evaluation of the LMDI and HMDI values. The comparison between LMDI indexes for both SEM and LM did not show any significance. The fluorescence microscopy analysis showed clearly the difference between old (high mineralized) and new (low mineralized) bone tissue near the implant surface. Under confocal laser microscopy the same sections showed the area of bone modelling closest to implant surface. CONCLUSION: In this study it was found that bone around unloaded implants showed a low mineral density index under all the investigation methods used. It was also found that the conventional LM technique with the double staining method was able to intensely stain the bone area with a low mineral content.

Analysis of Variance↗
PubMed2006

Maxillary sinus augmentation with different biomaterials: a comparative histologic and histomorphometric study in man.

OBJECTIVE: Rehabilitation of the edentulous posterior maxilla with dental implants can be difficult because of insufficient bone volume caused by pneumatization of the maxillary sinus and crestal bone resorption. Different biomaterials have been used for sinus augmentation. The aim of the study was to compare different materials in maxillary sinus augmentation in man. METHODS: A total of 94 patients participated in this study. Inclusion criteria were maxillary partial (unilateral or bilateral) edentulism involving the premolar/molar areas, and the presence of 3-5-mm crestal bone between the sinus floor and alveolar ridge. A total of 362 implants were inserted. There were 9 biomaterials used in the sinus augmentation procedures. Each patient underwent 1 biopsy after 6 months. A total of 144 specimens were retrieved. RESULTS: None of the 94 patients had complications. All implants were stable, and x-ray examination showed dense bone around the implants. Mean follow-up was 4 years. There were 7 implants that failed. Histologic resultsshowed that almost all the particles of the different biomaterials (i.e., autologous bone, demineralized freeze-dried bone allograft Biocoral [Inoteb, St. Gonnery, France], Bioglass [US Biomaterials, Alachua, FL], Fisiograft [Ghimas, Bologna, Italy], PepGen P-15 [Dentsply Friadent CeraMed, Lakewood, CO], calcium sulfate, Bio-Oss [Geistlich Pharma AG, Wohlhusen, Switzerland], and hydroxyapatite) were surrounded by bone. Some biomaterials were more resorbable than others. Included are the histomorphometry clarified features of the newly formed bone around the different grafted particles. CONCLUSION: All biomaterials examined resulted in being biocompatible and seemed to improve new bone formation in maxillary sinus lift. No signs of inflammation were present. The data are very encouraging because of the high number of successfully treated patients and the good quality of bone found in the retrieved specimens.

Aged↗
PubMed2006

Parallel screw cylinder implants: comparative analysis between immediate loading and two-stage healing of 1,005 dental implants with a 2-year follow up.

BACKGROUND: Recently, several authors have focused on the possibility of an immediate functional loading of dental implants to minimize the delay between surgical and prosthetic phases. PURPOSE: The aim of this study was a reevaluation of the XiVE dental implant (Dentsply-Friadent, Mannheim, Germany) with: (1) a longer follow-up period; (2) a higher number of fixture; and (3) a proper statistical method. MATERIALS AND METHODS: In July 2001 and December 2002, 371 patients (180 males and 191 females; ages ranging from 17 to 83; mean age, 53 years) were consecutively enrolled in this study. In 371 patients, a total of 1,005 XiVE dental implants were distributed as follows: 484 immediately loaded implants (test group) were inserted in 130 patients, whereas 521 unloaded implants were inserted in 241 patients (control group). RESULTS: The implant survival was 98.7 and 99.4% in immediate loading and control group, respectively. Univariate analysis showed no statistically significant difference between the two groups. CONCLUSION: In a previous report, we showed that immediate loading offered a predictable and reliable procedure also for XiVE implants, at least in the short period. In this study, we confirmed the results of the previous study and added information regarding the survival rate and marginal bone level stability with a 2-year follow up.

Adolescent↗
PubMed2006

Immediately loaded titanium implants with a porous anodized surface with at least 36 months of follow-up.

BACKGROUND: Results from some studies clearly suggest that immediate loading can achieve equal success rates as those found in delayed or unloaded implants. There is still a lack of knowledge about the role of surface oxide properties during the peri-implant bone healing processes. PURPOSE: The aim of this study was a clinical follow-up study of immediately loaded implants with a porous anodized surface. MATERIALS AND METHODS: A total of 142 TiUnite (Nobel Biocare, Göteborg, Sweden) implants were inserted from January to September 2001. All implants have been used in fixed restorations. Fifty implants were inserted in completely edentulous mandibles, and 69 implants were inserted in completely edentulous maxillae. All 119 implants were subjected to immediate functional loading (IFL) (immediate restoration with full occlusal contact). The other 23 implants, inserted in 12 patients, underwent immediate nonfunctional loading (INFL) (immediate restoration without occlusal contact) in different anatomical configurations (single tooth, small bridges in the anterior mandible, anterior maxilla, and posterior maxilla). All 142 implants have been followed for at least 3 years. RESULTS: All implants appeared to be osseointegrated from a clinical and radiographic point of view. No failures were observed in the IFL and INFL groups. The implant success was 100%. The mean marginal bone loss was 0.8 and 1.0 mm at 12 and 36 months, respectively. CONCLUSION: Implants with a porous anodized surface appear to work well under an immediate loading state in the long term.

Adult↗
PubMed2006

Syncrystallization: a technique for temporization of immediately loaded implants with metal-reinforced acrylic resin restorations.

BACKGROUND: Rigid temporization has been recognized to have a significant impact on the peri-implant tissue response in immediate implant loading since it reduces the mechanical stress exerted on each implant. PURPOSE: A successful protocol for immediate loading of multiple implants depends on an adequate fixation and immobility of the implants to prevent the risk of micromovements in relation to the surrounding bone. The objective of this article was to evaluate a prosthetic concept for an accelerated rigid splinting of multiple implants for same-day immediate loading with metal-reinforced provisional restorations using a technique of welding temporary implant abutments with a prefabricated titanium bar directly in the oral cavity (syncrystallization). MATERIALS AND METHODS: Between June 2004 and January 2005, immediate loading of threaded implants with a metal- reinforced acrylic resin provisional restoration at stage 1 surgery was evaluated in 40 consecutive patients. A total of 192 implants were placed in selected edentulous or partially edentulous patients using the syncrystallization technique. Once the titanium bar was welded intraorally to the abutments, opaque was applied and the provisional restoration was relined and screw-retained the same day. In addition, a comparison of deformations and stress distributions in implant-supported, metal-reinforced and nonmetal-reinforced resin provisional restorations was analyzed in the edentulous mandible by a three-dimensional finite element model (FEM). RESULTS: All of the 192 rigidly temporized immediately loaded implants osseointegrated. An implant success rate of 100% was achieved over a period of 6 months postplacement. No fracture or luting cement failure of the provisional restoration occurred during the observation time. Compared to mere acrylic superstructures, a significant reduction of deformation and strain within metal-reinforced provisional restorations was detected by FEM analysis. CONCLUSION: The results of this study indicate that the syncrystallization technique allows an expedite and adequate rigid splinting of multiple immediately loaded implants. The advantages of the technique are: (1) reduction of treatment time for immediate temporization at stage 1 surgery; (2) predictable fixation and immobility of implants in the early stages of bone healing; and (3) less time for repairing provisional restorations as a result of no or rare fracture.

Acrylic Resins↗
PubMed2006

Correlation between implant stability quotient and bone-implant contact: a retrospective histological and histomorphometrical study of seven titanium implants retrieved from humans.

BACKGROUND: Primary stability has a relevant role in the long-term success of dental implants. A quantitative method for the measurement of implant stability has been introduced (resonance frequency analysis [RFA]). Information about the significance of RFA measurements and about the relationship between RFA values and their association with implant osseointegration, success, or failure is important from a clinical point of view. PURPOSE: The aim of the present histological and histomorphometric study was to see if a correlation existed between the bone-implant contact (BIC) percentage of retrieved human implants and RFA values. MATERIALS AND METHODS: Seven implants inserted in the posterior mandible, with a sandblasted and acid-etched surface and retrieved after a 6-month period, were evaluated in the present study. These seven implants had been retrieved for different causes. All these implants were submerged and were retrieved with a 5-mm trephine bur and immersed in 10% buffered formalin to be processed for histology. RESULTS: A statistically significant correlation could be detected between implant stability quotient and BIC (p=.016). CONCLUSIONS: Even if the relationship between bone structure and RFA is still not fully understood, in our study, a statistically significant correlation was found between RFA and BIC values. Further studies are needed to evaluate a correlation of RFA and BIC in human implants retrieved after a range of healing periods.

Dental Implantation, Endosseous↗
PubMed2006

Five-year outcome of 111 immediate nonfunctional single restorations.

Immediate loading is a surgical-prosthetic procedure extensively used in implant dentistry. Despite its frequent use, minimal data are available on the long-term clinical success rate of immediate functional loading (IFL) and immediate nonfunctional loading (INFL) of implants. The aim of this study was to evaluate the long-term survival and bone loss of immediate nonfunctional single implant restorations in a group of patients that were monitored for 5 years. One hundred and eleven patients (41.4% men) with a median age of 40 years were included in this study. A total of 111 implants were placed. All implants were placed with a minimum insertion torque of 25 Ncm. A temporary restoration was relined with acrylic resin, trimmed, polished, and cemented or screw-retained 1 to 2 hours later. Occlusal contact was avoided in centric and lateral excursions. After provisional crown delivery, a periapical radiograph was performed by means of a customized Rinn holder device. Data were analyzed by means of Kaplan-Meier and life-table algorithms. Stratification of implant survival was performed for the available variables of interest, and comparisons were analyzed using a log-rank test. Investigated parameters were time of implant placement, bone quality, implant site, implant diameter and length, and type of implant surface enhancement. The parameters for overall success rate were defined by bone resorption <1.5 mm after the first year of loading and <0.2 mm thereafter. During the 5-year follow-up period, a survival rate of 95.5% was observed. All failures occurred within 4 months of implant loading. There were statistically significant differences regarding healed vs post-extraction implant sites (100% and 92.5%, respectively, P = .05) and type of bone (D1 vs D4 yielded 100% and 95.5%, respectively, P <.05). No differences were detected for: (1) site (100% for mandible and 94.63% for maxilla, P =-.319); (2) implant diameter (survival rates of 97.26% for <4.5-mm diameter and 92.11% for >4.5mm diameter, P = .206); (3) implant lengths (survival rates of 96.97% for implants >13 mm and 94.87% for implants <13 mm, P =.624); and (4) type of implant surface enhancement (survival rates of 94.03% for 67 cases of grit-blasted and acid-etched surfaces and a failure rate of 4 out of 5, and 94.12% for 17 cases of hydroxyapatite (HA)-coated surfaces with only 1 failure). The success rate (defined as bone resorption >1.5 mm after the first year of loading and >0.2 mm thereafter) was 97.2%. Immediate nonocclusal loading of single implants is a reliable surgical-prosthetic procedure with a low rate of implant loss and a low quantity of peri-implant bone loss over time.

Adolescent↗
PubMed2006

Inflammatory infiltrate, microvessel density, nitric oxide synthase expression, vascular endothelial growth factor expression, and proliferative activity in peri-implant soft tissues around titanium and zirconium oxide healing caps.

BACKGROUND: The aim of the present study in humans was to conduct a comparative immunohistochemical evaluation of vascular endothelial growth factor (VEGF) and nitric oxide synthase (NOS) expression, inflammatory infiltrate, proliferative activity expression, and microvessel density (MVD) in peri-implant soft tissues of titanium and zirconium oxide healing caps. METHODS: Five patients, three men and two women (aged 30 to 66 years; mean: 49 years), participated in this study. All patients received dental implants that were 3.8 mm in diameter and 11 mm in length. All implants were left to heal in a non-submerged (single-stage) mode. Healing caps (3.8 mm in diameter and 3.0 mm in height) were inserted in all implants. Half of the implants were supplied with standard, prefabricated caps of commercially pure titanium, whereas the other half were provided with test zirconium oxide caps. After a 6-month healing period, a gingival biopsy was performed with a circular scalpel (5.5 mm in diameter) around the healing caps of both groups, without unscrewing or removing the healing caps. The dimensions of the gingival biopsies were 1.7 mm (5.5-3.8 mm) in thickness and 3 mm in height. RESULTS: Statistically significant differences were found in the microvessel density between titanium and zirconium oxide healing caps and group II (P < or = 0.0001). Statistically significant differences were likewise found in the low and high intensities of NOS1, NOS3, and VEGF (P < or = 0.0001). In conclusion, the high intensity of NOS1, NOS3, and VEGF were mostly expressed in the titanium group, whereas the low intensity of NOS1, NOS3, and VEGF were mostly expressed in the zirconium oxide group. CONCLUSIONS: In our specimens, the inflammatory infiltrate was mostly present in the titanium specimens. Their extension was much larger than that of the zirconium oxide specimens. Higher values of MVD were observed in the titanium specimens (29.1 versus 15.8). In addition, a higher expression of VEGF intensity was observed in the peri-implant tissues of titanium healing caps, whereas predominantly lower expressions of VEGF intensity were noted around the zirconium oxide healing caps. The Ki-67 expression was higher in the titanium specimens. All these data revealed that the tissues around titanium healing caps underwent a higher rate of inflammation-associated processes, most probably correlated to the higher inflammation processes observed in these tissues. A higher intensity expression of NOS1 and NOS3 was recorded in the tissues around titanium, whereas, on the contrary, a lower intensity of expression was found in the tissues around zirconium oxide specimens. These latter data indicate that the higher expression of these two mediators could be correlated to the higher amount of bacteria present around the titanium samples.

Adult↗
PubMed2006

Zirconium implant abutments: fracture strength and influence of cyclic loading on retaining-screw loosening.

OBJECTIVE: The purpose of this study was to determine the fracture strength of zirconium implant abutments and the torque required to unfasten the retaining screw before and after applying cyclic loading to the implant-abutment assembly. The dynamic behavior and stress distribution pattern of zirconium abutments were also evaluated. METHODS AND MATERIALS: Static and cyclic loading of 7 XiVE implants with straight Cercon zirconium abutments were simulated under worst-case conditions. Cyclic loading tests were performed via a servohydraulic dynamic testing machine at loads between 100 and 450 N, for up to 5 million loading cycles, at 15 Hz. The dynamic behavior of the zirconium abutments was analyzed by finite element modeling and Pro/Mechanica software, comparing van-der-Mises and maximum stress levels. RESULTS: Cercon zirconium-ceramic abutments exhibited a maximum fracture strength of 672 N during static loading and 269 N at 800,000 to 5 million cycles runout point, and 403 N at 10,000 cycles runout point during cyclic loading. The mean torque value required to unfasten the abutment retaining screws after (initial) tightening was 21 Ncm +/- 1 and 20 Ncm +/- 1 (measurement accuracy +/- 2 Ncm) after loading with up to 5 million cycles respectively. Torque values decreased minimally and screw loosening did not occur. Within the limited number of test specimens (7), the difference was statistically significant (P = .015). FEM analysis displayed higher stress peaks up to 800 MPa at the cervical aspect of the zirconium abutment and at the apical third of its retaining screw at an external load of 250 N. CONCLUSION: Within the limitations of this study, zirconium implant abutments exceeded the established values for maximum incisal bite forces reported in the literature and tightly fit into the titanium implant after several millions of loading cycles.

Bite Force↗
PubMed2005

Genetic effects of anorganic bovine bone (Bio-Oss) on osteoblast-like MG63 cells.

Bio-Oss (Geistlich, Wolhusen, Switzerland) is composed by anorganic bovine bone and is widely used in several bone regeneration procedures in oral surgery. How this biomaterial alters osteoblast gene expression to promote bone formation is poorly understood. We therefore attempted to address this question by using microarray techniques to identify genes that are differentially regulated in osteoblasts exposed to Bio-Oss. By using DNA microarrays containing 20,000 genes, we identified in osteoblast-like cells line (MG-63) cultured with Bio-Oss several genes which expression was significantly up- and down-regulated. The differentially expressed genes cover a broad range of functional activities: (a) signaling transduction, (b) transcription, (c) cell cycle regulation, (d) vesicular transport, (e) apoptosis, and (f) immunity. These results could explain the reported bioaffinity of Bio-Oss to host animals, its biological affinity to osteogenic cells and its capability to stimulate osteoblastic differentiation. The data reported are, to our knowledge, the first genetic portrait of Bio-Oss effects. They can be relevant to our improved understanding of the molecular mechanism underlying bone regenerative procedures and as a model for comparing other materials with similar clinical effects.

Animals↗
PubMed2005

Maxillary sinus augmentation with Bio-Oss particles: a light, scanning, and transmission electron microscopy study in man.

Biological interactions occurring at the bone-biomaterial interface are critical for long-term clinical success. Bio-Oss is a deproteinized, sterilized bovine bone that has been extensively used in bone regeneration procedures. The aim of the present study was a comparative light, scanning, and electron microscopy evaluation of the interface between Bio-Oss and bone in specimens retrieved after sinus augmentation procedures. Under light microscopy, most of the particles were surrounded by newly formed bone, while in a few cases, at the interface of some particles it was possible to observe marrow spaces and biological fluids. Under scanning electron microscopy, in most cases, the particle perimeter appeared lined by bone that was tightly adherent to the biomaterial surface. Transmission electron microscopy showed that the bone tissue around the biomaterial showed all the phases of the bone healing process. In some areas, randomly organized collagen fibers were present, while in other areas, newly formed compact bone was present. In the first bone lamella collagen fibers contacting the Bio-Oss surface were oriented at 243.73 +/- 7.12 degrees (mean +/- SD), while in the rest of the lamella they were oriented at 288.05 +/- 4.86 degrees (mean +/- SD) with a statistically significant difference of 44.32 degrees (p < 0.001). In the same areas the intensity of gray value was 172.56 +/- 18.15 (mean +/- SD) near the biomaterial surface and 158.71 +/- 21.95 (mean +/- SD) in the other part of the lamella with an unstatistically significant difference of 13.79 (p = 0.071). At the bone-biomaterial interface there was also an electron-dense layer similar to cement lines. This layer had a variable morphology being, in some areas, a thin line, and in other areas, a thick irregular band. The analyses showed that Bio-Oss particles do not interfere with the normal osseous healing process after sinus lift procedures and promote new bone formation. In conclusion, this study serves as a better understanding of the morphologic characteristics of Bio-Oss and its interaction with the surrounding tissues.

Absorbable Implants↗
PubMed2005

Collagen fiber orientation near dental implants in human bone: do their organization reflect differences in loading?

This study is the first to investigate the collagen fiber orientation in human bone around titanium dental implants after loading. Birefringence under circularly polarized light (CPL) and scanning electron microscopy (SEM) investigation were used to assess both collagen orientation and density. Twenty osseointegrated dental implants were retrieved from the mandible bone of 10 patients and were used in the present study. The implants were retrieved after 6 months of function. The birefringence measurements were performed on digitized images using both the peri-implant bone (PB) and the alveolar bone (AB) retrieved at the moment of implant placing. All images detected at 100x were measured using a software image analysis. The results showed that 32.96% (3.208 +/- 0.435 mm(2)) of the PB area was composed of transverse collagen fibers while only 19.70% (1.957 +/- 0.253 mm(2)) was composed of longitudinally collagen fibers. In the AB 26.99% (2.620 +/- 0.520 mm(2)) of the examined area was composed of transverse collagen fibers while 22.25% (2.160 +/- 0.320 mm(2)) was composed of longitudinally collagen fibers. The CPL measurements of the birefringence indicated that the difference in area between the two collagen fibers orientations was statistically significant (p = 0.03) for both AB and PB. In PB the transverse collagen fibers were significantly increased (p < 0.01) than in AB; also the longitudinal collagen fibers differ significantly in the two groups (p = 0.02). The transverse collagen fibers in PB are more present under the lower flank of the threads where the load acts with a compression vectors, while outside the tip of the implant threads the collagen fibers run more longitudinally due to the loads that act with a tensile vectors. SEM observations showed, in the first collagen layers facing the implant surface, a random direction of the collagen fibers, while in the areas away from the implant surface the collagen fibers were well oriented and run parallel. In conclusion, in these loaded dental implants, the bone adjacent to the first two implant threads shows a significant increase of the amount of transverse collagen fibers that were mainly associated with the lower flank of the threads where compressive load acts. The longitudinal collagen fibers also differs significantly from those found in the AB.

Adult↗
PubMed2005

Quantitative evaluation of the fibrin clot extension on different implant surfaces: an in vitro study.

The aim of the present study was a quantitative evaluation of the in vitro fibrin clot extension on different implant surfaces. Forty-five disk-shaped commercially pure Grade 2 titanium samples with three different surface topographies (machined, DPS, and Plus) were used in the present study. For the quantitative evaluation of the fibrin clot, 30 specimens were used (10 per group); human whole blood was employed. Venous blood was drawn from three healthy adult volunteers, and 0.2 mL were immediately dropped onto the surface of each specimen. Contact time was 5 min at room temperature; then the samples were rinsed with saline solution and fixed in a buffered solution of glutaraldehyde and paraformaldehyde. Samples were washed again with buffer and dehydrated in an ascending alcohol series. Specimens belonging to all groups were observed under SEM at a magnification of 1000x. From each sample, 50 random micrographs were collected in .tif format with an N x M 1024 x 768 grid of pixels. Quantitative analysis of fibrin clot extension showed the following results: in machined samples fibrin clot extension was 345987.2 +/- 63747.7 pixels(2) (mean +/- SD), in DPS samples fibrin clot extension was 375930.9 +/- 54726.86 pixels(2) (mean +/- SD), and in Plus samples, fibrin clot extension was 612333.6 +/- 46268.42 pixels(2) (mean +/- SD). With ANOVA it was possible to find that there were significant differences among the groups. The Tukey test revealed that the extension of the fibrin clot of Plus samples was statistically higher compared to both machined and DPS samples. The results of this in vitro study indicate that there is a correlation between implant surface morphology and fibrin clot extension. Improvement in surface microtexture complexity seems to determine the formation of a more extensive and three dimensionally complex fibrin scaffold. Further investigations are necessary to explain in more detail the mechanisms that regulate the fibrin clot formation on different implant surfaces.

Adsorption↗
PubMed2005

Maxillary sinus augmentation using a synthetic cell-binding peptide: a histologic and transmission electron microscopy case study in man.

PepGen P-15 is a combination natural anorganic bovine-derived hydroxyapatite matrix coupled with a synthetic cell-binding peptide (P-15). This material has improved bone formation in periodontal osseous defects and bone regenerative procedures. There were 3 specimens retrieved 18 months after a sinus lifting procedure using PepGen P-15. These specimens were treated to be observed under light microscopy and transmission electron microscopy. Light microscopy showed that most of the particles were surrounded by newly formed bone. In some areas, osteoid matrix was present. No acute inflammatory infiltrate was present. In transmission electron microscopy, all phases of bone formation (i.e., osteoid matrix, woven bone, and lamellar bone) were observed in the newly formed bone around the biomaterial particles. In some regions, this newly formed bone seemed to present interdigitations connecting to or entering into the particle surface. To our knowledge, this is the first report presenting data on transmission electron microscopy of PepGen P-15 used in a sinus augmentation procedure in man. Our results confirm previous reports on the clinical effectiveness of this material.

Alveolar Ridge Augmentation↗
PubMed2005

Bone remodeling in immediately loaded and unloaded titanium dental implants: a histologic and histomorphometric study in humans.

Remodeling is thought to prevent microdamage accumulation caused by repetitive loading and to increase the fatigue life of bone. The bone remodeling rate (BRR) is the period of time needed for new bone to replace the existing bone and to allow for the adaptation of bone to its environment. BRR is expressed as a percentage or volume of new bone within a specific time period. The aim of the present study was to evaluate bone remodeling events on submerged and immediately loaded dental implants. Twelve patients with edentulous mandibles participated in this study. All patients were rehabilitated with fixed mandibular prostheses, with 10 dental implants per patient. An additional implant was inserted in the most distal posterior mandibular jaw region. In 6 patients, these additional implants were loaded with a fixed provisional prosthesis the same day of the implant surgery and loaded. In the other 6 patients, the additional implants were left submerged and not loaded. After 6 months, all the additional implants were retrieved with a trephine. The percentage of woven and lamellar bone, number of osteoclasts and osteoblasts, and percentage of bone labeled by tetracycline at 0.5 mm and 2 mm from the implant surface were evaluated. The percentage of lamellar bone, number of osteoblasts, and percentage of bone tetracycline labeling was significantly higher in the loaded implants than in the unloaded implants (P =.0001). Also in the loaded implants, the percentage of woven and lamellar bone, number of osteoclasts and osteoblasts, and percentage of bone tetracycline labeling was significantly higher at 0.5 mm than at 2 mm from the implant surface (P =.0001). No such differences were found in unloaded implants (P =.377). In conclusion, we found that (1) loading appeared to stimulate bone remodeling at the interface, (2) a higher percentage of lamellar bone was found in loaded implants, (3) the percentage of bone labeling was higher at the interface of loaded implants, (4) no differences were found in the BRRs between immediately loaded and unloaded implants, and (5) immediate loading had not interfered on the lamellar bone formation at the interface and had not produced formation of woven bone at the interface.

Adult↗
PubMed2005

7-year follow-up of 93 immediately loaded titanium dental implants.

Recently, several experimental and clinical investigations found that immediately loaded implants obtained satisfactory levels of osseointegration with high success percentages. Only a few long-term studies of immediately loaded implants have been reported in the literature. The aim of this study was a 7-year clinical and radiographic follow-up of 93 immediately loaded dental implants in human patients. Eleven patients were consecutively enrolled in this study. A total of 7 full and 9 partial edentulous arches were rehabilitated. Patients presented a completely edentulous mandible (n=6), a completely edentulous maxilla (n=1), mandibular posterior edentulous areas (n=5), or a posterior maxillary edentulous area (n=1). Patients were rehabilitated with a bar and an overdenture (n=4), a provisional prosthesis of 3 to 12 elements (n=11), or a metal-ceramic bridge of 10 elements (n=1). A total of 93 implants were inserted and loaded within a 24-hour time frame. Six implants failed in the first year after loading. No more failures were observed in the following 6 years, and all the other implants were well integrated from a clinical and radiographic point of view. The cumulative success rate at 7 years was 93.5%, and the prostheses survival rate was 98.5%. The mean marginal bone loss was 0.6 mm after the first year and 1.1 mm at the 7-year evaluation. Primary stability is one of the most important parameters in immediately loaded implants because it avoids micromotion at the bone-implant interface. Four of the 6 failures in our patients occurred in partially edentulous patients; an excessive load applied to these small bridges could be the reason for the failure. Also, the bone quality is important, for 3 of our failed implants had been inserted in D3 bone. Our clinical and radiographic results have shown that these immediately loaded implants have remained osseointegrated for a long period. Our results point to the possibility of using the immediate loading technique in selected and well-informed cases.

Adult↗