Biomedical subjects

Paolo Trisi

Publications and source records attributed to Paolo Trisi.

18 recordsLinked to original sources

PubMed2006

Reintegration success of osseotite implants after intentional countertorque liberation in the endentulous human mandible.

PURPOSE: Implants that rotate during abutment screw tightening may not necessarily constitute implant failure. This prospective study was designed to determine to what degree integrated implants could gain a state of reintegration after intentional countertorque to liberation from the bone. MATERIALS AND METHODS: There were 11 patients with fully edentulous mandibles restored with 2 "clinical" implants (3.75 x 10 mm) placed in the canine sites and an additional nonused "test" implant (3.75 x 10 mm) placed at the symphysis of the anterior mandible. At second-stage surgery, the test implant was countertorqued (T1) using a torque-metering wrench until it detached from the bone. The implant was returned to its original position and allowed to heal for a period until a second countertorque test (T2) was performed. In group A, patients (n = 5) received the countertorque T1 at 3 months and T2 at 5 months. In group B (n = 6) T1 was at 1.5 months, and T2 was at 3.5 months. After completion of T2, the group A test implants were removed with a 5-mm trephine for histologic examination. RESULTS: For both groups, peak forces, all higher than 37.4 Ncm at T1, indicate that all implants were integrated. At T2, torque values were higher than T1 values for most of the test implants. The clinical implants were restored with "patrix" abutments and an overdenture. Histology staining showed distinction between old and new bone, which formed during the remodeling process. DISCUSSION: The increase in peak forces needed to detach implants at T2 may be explained by bone-to-bone healing or the additional bone contact promoted by bleeding that occurred during the T1 procedure. CONCLUSION: The results suggest that all implants were reintegrated after being intentionally countertorqued to liberation and resumed healing in the original osteotomy position.

Aged↗

PubMed2006

Consensus conference on immediate loading: the single tooth and partial edentulous areas.

PURPOSE: A consensus conference was held to determine what the parameters should be for the immediate functional loading of the single-tooth implant restoration and short-span fixed implant-supported bridgework. MATERIALS: Forty-one clinicians and researchers presented cases and situations relating to the topic. A panel then distilled questions that were presented to the audience (430) at large. Answers were gleaned to formulate a consensus. RESULTS: Ten distinct answers evolved that constituted the essence of guidelines for clinicians to be aware of when undertaking immediate loading. These guidelines are contained within the body of the text. CONCLUSIONS: Extreme caution and adherence to a universal generic protocol are suggested for clinicians who are involved with single-tooth and short-span multiple-teeth implant replacements as related to immediate loading as defined within this text.

Dental Abutments↗

PubMed2006

Histomorphometric evaluation of six dental implant surfaces after early loading in augmented human sinuses.

This study investigated the bone-to-implant contact (BIC) and osteoconductive capacity (OC) of 6 different implant surfaces after early loading in humans. Two implants with different surfaces were placed side-by-side in the grafted (n= 5) and nongrafted (n = 1) sinuses of 3 volunteers. Single-tooth restorations were delivered 60 days later. After 6 months of full occlusal loading, implants were retrieved in block sections for histomorphometric analysis. One implant (acid etched) placed in grafted bone failed when loaded. There were no other complications. In grafted bone, the microtextured surface achieved the highest BIC value (94.08%), followed by the oxidized (77.32%), hydroxyapatite (HA) (74.51%), sandblasted and acid-etched (51.85%), and titanium plasma-sprayed (TPS) (41.48%) surfaces. In native bone, the acid-etched surface achieved a higher BIC value (69.03%) than the HA surface (59.03%). The highest OC value in grafted bone was exhibited by the microtextured surface (34.31%), followed by the HA (28.62%), sandblasted and acid-etched (25.08%), oxidized (17.55%), and TPS (-20.47%) surfaces. The HA surface exhibited a higher OC value (30.39%) in native bone compared with the acid-etched surface (24.0%). As a whole, highest BIC and OC values were exhibited by the microtextured surface, and lowest values were exhibited by the TPS surface. All other surfaces demonstrated excellent BIC (>50%) but varied in OC (range = 17.55%-28.62%). These findings are tempered by the limited scope and sample size of the study and should be considered preliminary. More research is needed to determine the impact of implant surface texture on BIC and OC.

Acid Etching, Dental↗

PubMed2006

Sinus graft with biogran, autogenous bone, and PRP: a report of three cases with histology and micro-CT.

Three sinuses were grafted with a bioactive glass bone substitute (Biogran) mixed with autogenous bone retrieved from intraoral donor sites. In two of the three sinuses a platelet-rich plasma (PRP) gel was added to the graft. Bone biopsies retrieved after 5, 6, and 15 months were analyzed. Micro-computerized tomography (micro-CT) values of total bone volume/total volume (TBV/TV) were very reliable compared to histomorphometry. Biogran mixed with autogenous bone and PRP seems to have a positive effect in sinus grafting, with TBV/TV values ranging between 40% and 68%. Micro-CT results have never been compared with histomorphometry for the evaluation of grafted biomaterials. Micro-CT evaluation of some morphometric parameters was difficult, because the radiodensities of Biogran and a certain grade of bone mineralization were similar.

Biocompatible Materials↗

PubMed2006

Vertical ridge augmentation around implants using e-PTFE titanium-reinforced membrane and deproteinized bovine bone mineral (bio-oss): A case report.

The aim of this case report was to evaluate the ability of Bio-Oss used together with an expanded polytetrafluoroethylene, titanium-reinforced membrane to restore a vertical bone defect. Bio-Oss served as a filler material. After the membrane was removed, screw-type implants were placed. During this phase, cylindric bone samples were retrieved from the augmented area for histologic examination. The biopsy samples were composed of low-density trabecular bone with numerous interspersed graft particles. Clinical and histologic results demonstrated that this surgical technique could be a successful and predictable procedure for rebuilding a resorbed ridge to place implants.

Aged↗

PubMed2005

Peri-implant bone reaction to immediate, early, and delayed orthodontic loading in humans.

Seventeen endosseous titanium implants were placed in completely edentulous jaws of 15 patients. The implants were loaded immediately or after 2 or 6 months, with 100 g orthodontic force. Three weeks later, the implants were removed and histologically analyzed. All of the immediately loaded implants, along with three of the eight that were loaded after 2 months, were lost. The remaining implants were stable until the end of the study. Histologic analysis of the retrieved implants showed bone remodeling in the cortical bone, thickening of the bony trabeculae by new lamellar bone deposition, and microcalli of woven bone or a lattice of woven bone formation around some implants that had been placed in soft bone. Tetracycline labeling revealed an elevated amount of newly formed bone. If further studies prove that a controlled application of orthodontic force, before application of occlusal loading, is able to rapidly enhance the density of soft peri-implant bone, we will have a powerful and precise tool to improve the rate of implant success.

Bone Density↗

PubMed2004

Long-term evaluation of sandblasted and acid-etched implants used as orthodontic anchors in dogs.

The aim of this study was the clinical, radiographic, and histologic evaluation of the tissue surrounding SLA (sandblasted and acid-etched) implants loaded with a continuous and constant force for 52 weeks, after a healing period of 6 weeks, after implant insertion. SLA implants were placed in the maxilla of 3 dogs and the mandible of 5 dogs after a 12-week healing period after extraction. Abutments were attached to the 6 test implants (2 in the maxilla, 4 in the mandible). Superelastic nickel-titanium coil springs were activated between the SLA implants and the canines, producing a force of 200 g (2 N). Two unloaded implants (1 in the maxilla, 1 in the mandible) served as controls. Histologic analysis showed a corticalization of bone trabeculae, thicker at the loaded than at the unloaded implants. New bone formation at the level of the crest was slightly superior in the test implants. A difference between the tension and compression areas could not be observed in the test implants. The mean bone-implant contact values of the test implants for the maxilla and mandible were 40.23% and 49.33%, respectively. In the control implants, the bone-implant contact value was 67.91% for the maxilla and 49.23% for the mandible. SLA implants can be used as an anchorage unit with confidence, in spite of a short healing period and a prolonged force application. Further studies with different force magnitudes and healing periods are required to clarify the effects of healing period and force magnitude on bone quality and quantity.

Acid Etching, Dental↗

PubMed2004

Osseointegration of Osseotite and machined titanium implants in autogenous bone graft. A histologic and histomorphometric study in dogs.

It has been shown that a roughened implant surface results in a higher percentage of bone to implant contact (%BIC) than a machined one. A modified implant surface using a dual thermo-acid etching process (Osseotite) has been introduced and evaluated clinically, mechanically and histologically. The aim of the present study was the histological evaluation of the %BIC between the Osseotite or machined surfaces and the autogenous bone graft. Twenty-two custom-made split-type 10-mm-long implants having two opposing surfaces (Osseotite and machined) were placed between the cranial and caudal dorsal iliac spine at the iliac wing of two adult mongrel dogs. An artificial bone defect was created leaving a 2 mm empty space around the coronal 5 mm of the implants, while the apical 5 mm was stabilized in the existing basal bone. The defects around the implants were filled with particulate autogenous bone graft, covered by an Osseoquest membrane, and left to heal for 5 months. All inserted implants showed a complete integration in the bone tissue. It was found that the resulting %BIC at the Osseotite surface was significantly higher than at the machined one in both regenerated (46.44+/-15.81% vs. 28.59+/-12.04%) and basal bone areas (32.32+/-15.09% vs. 17.25+/-7.40%). The findings of this study imply that the use of autogenous bone graft resulted in significantly higher %BIC values in the regenerated area than in the basal bone area itself, for both implant surfaces.

Acid Etching, Dental↗

PubMed2004

Microcomputed tomographic analysis of the peri-implant bone.

A recently developed technology allows evaluation of bone biopsies with 3-D microcomputed tomography (microCT). The present study evaluated the feasibility of application of microCT to the analysis of peri-implant bone tissues. A human bone biopsy containing a titanium screw was analyzed using a microCT scan. The parameters computed by the microCT were bone volume, bone surface, trabecular thickness, trabecular separation, and bone connectivity. Also, the bone-to-implant apposition was measured, and all results were compared with those obtained with standard histomorphometry of the same biopsy. The results of the present study suggest that microCT enables 3-D nondestructive evaluation of bone biopsies containing endosseous titanium implants, also allowing analysis of the bone-implant interface. Measurements of bone-to-implant apposition obtained by microCT were similar to those obtained with standard undecalcified histology.

Biopsy↗

PubMed2003

Bone-implant contact on machined and dual acid-etched surfaces after 2 months of healing in the human maxilla.

BACKGROUND: Recent clinical studies indicate that an implant with a textured surface may be loaded sooner than traditional healing protocols have recommended. In a previous study, the 6-month bone-implant contact for dual acid-etched and machined implant surfaces was reported to be 72.96% and 33.98%, respectively. In 1991, a minimum of 50% bone-implant contact was considered necessary for loading to ensure long-term survival of the implant. This study evaluated the 2-month bone-implant contact for dual acid-etched and machined implant surfaces to determine if this criterion had been met. METHODS: Custom manufactured implants (2 mm diameter and 5 mm length), having on one side a machined surface and on the other side a dual acid-etched surface, were placed in the posterior maxilla of 11 patients, allowed to integrate for 2 months, then removed using a 4 mm internal diameter trephine with irrigation. Sections were processed and stained for histologic and histomorphometric analysis. The parameters calculated for each section were: bone volume (BV%), actual percent bone-implant contact (BIC%), and expected bone contact (EBC%) as determined from 3 implant images superimposed onto the adjacent bone 150, 500, and 1,000 microm lateral to the actual implant surface and representing the bone-implant contact expected on the day the implant was placed, based on the peri-implant bone volume. RESULTS: Histomorphometric analysis indicated that the mean BV% of 36.77% from all sections was closely matched to the mean EBC% of 34.36% (P<0.001). The analysis showed that after 2 months of healing, the 47.81% BIC% on the dual acid-etched side was statistically higher (analysis of variance, P<0.001) than the 19.00% BIC% on the machined side. In areas of low-density bone (<40% BV%), the difference between the BIC% for the machined and dual acid-etched sides was even greater. Nine of the 11 dual acid-etched sides had a higher BIC% than the EBC% value. In the machined group, 1 of the 11 sides had a higher BIC% value than the EBC% value. The bone surrounding the dual acid-etched surface was a woven bone with thin, connecting peri-implant bony trabeculae projecting into and between the threads. Bone on the machined side was observed mostly contacting the tips of the screw threads. CONCLUSIONS: At 2 months, the mean BIC% for the dual acid-etched group increased 39.14% compared to the EBC% value, while the mean BIC% for the machined group decreased 44.70%. Based on the histomorphometric results of this study, sufficient bone for functional loading of the implant exists on a dual acid-etched surface after 2 months of healing in the posterior maxillary arch.

Acid Etching, Dental↗

PubMed2003

Histologic effect of pure-phase beta-tricalcium phosphate on bone regeneration in human artificial jawbone defects.

The effect of the pure-phase beta-tricalcium phosphate (beta-TCP) Cerasorb on bone regeneration was evaluated in hollow titanium cylinders implanted in the posterior jaws of five volunteers. Beta-TCP particles were inserted inside the cylinders and harvested 6 months after placement. The density of the newly formed bone inside the bone-growing chambers measured 27.84% +/- 24.67% in test and 17.90% +/- 4.28% in control subjects, without a statistically significant difference. Analysis of the histologic specimens revealed that the density of the regenerated bone was related to the density of the surrounding bone. The present study demonstrates the spontaneous healing of infrabony artificial defects, 2.5 mm diameter, in the jaw. The pure beta-TCP was resorbed simultaneously with new bone formation, without interference with the bone matrix formation.

Absorbable Implants↗

PubMed2003

Use of a resorbable hydroxyapatite-collagen chondroitin sulfate material on immediate postextraction sites: a clinical and histologic study.

This study looked at a bone-substitute biomaterial (Biostite) used to fill bone defects around immediate implants in humans. Ninety-six peri-implant bone defects were treated without the use of membranes, comparing two groups: group A = filling the defect with Biostite, and group B = no defect fill. After 4 to 6 months of healing, group A revealed higher percentages of implants covered by new, bone-like tissue (67% in group A, 34% in group B). Endochondral osteogenesis was demonstrated histologically in the regenerated tissues in alveolar sites treated, allowing the hypothesis of bone induction from the filling material used.

Absorbable Implants↗

PubMed2003

Bone-to-implant apposition with machined and MTX microtextured implant surfaces in human sinus grafts.

The goal of this study was to histologically document the effect of two different implant surfaces on the percentage of bone-to-implant apposition achieved with implants placed in human sinus grafts. The influences of implant site and post-grafting delay time were also examined. Nine healthy volunteers were scheduled to undergo posterior maxillary sinus floor augmentation in preparation for delayed implant placement. In addition to the conventional dental implants selected for each case, titanium alloy experimental implants, 2.5 mm in diameter and 8 mm in length, were custom manufactured. Each microimplant was prepared longitudinally with two different surface topographies: machined on one side and MTX microtextured on the other side. A notch prepared across the superior aspect of the implants facilitated placement and provided a reference line between the two surfaces. Patients were divided into two groups that received the experimental microimplants at the time of conventional implant placement: Group A (six patients) received the experimental microimplants in the regenerated lateral wall of the sinus graft 11 months after graft placement, and group B (three patients) received them in the alveolar crest 6 months after graft placement. After 6 months of submerged healing, all experimental and conventional implants appeared to be clinically osseointegrated. Histologic analysis revealed that the mean bone-to-implant apposition was significantly greater with MTX (72.31% +/- 17.76%) compared to machined surfaces (38.01% +/- 19.32%), regardless of bone quality. The healing time between graft and implant placement and implant location did not statistically impact the percentage of bone-to-implant apposition.

Alloys↗

PubMed2002

Progressive bone adaptation of titanium implants during and after orthodontic load in humans.

The aim of the present work was the evaluation of implant stability and periimplant bone reaction by histologic and clinical evaluation after therapeutic orthodontic loads. Forty-one adult patients received titanium implants as an orthodontic anchorage device; 12 patients received a retromolar or palatal implant to obtain tooth movement. Seven implants were removed at the end of the orthodontic therapy, after 2, 4, 6, and 12 months of orthodontic load, and processed for histologic examination. It was possible to distalize maxillary and mandibular molars and a group of teeth (molars and premolars), and to obtain tipping, uprighting, intrusion, extrusion, and transfer of anchorage in other parts of the mouth. The results showed that orthodontic therapy is facilitated and quickened by the use of implants. All implants remained stable in the bone up to 12 months of loading, and all were osseointegrated. Microfractures, microcracks, and microcalli were observed around implants that had been placed in both low- and high-density bone. The remodeling rate was still elevated after 18 months.

Adaptation, Physiological↗

PubMed2002

Healing of Osseotite implants under submerged and immediate loading conditions in a single patient: a case report and interface analysis after 2 months.

A growing number of clinical studies show that early (2 months) and immediate loading protocols may be predictable. However, they are based on clinical stability only The aim of this case report was to document the osseointegration status of two Osseotite implants after 2 months of healing in soft bone corresponding to type IV and subjected to two distinct mechanical environments. A completely edentulous patient received a total of 11 Osseotite implants in the mandible. Six were immediately loaded to support a provisional fixed partial denture, and five were left submerged. After 2 months, two submerged and one immediately loaded implants were retrieved and processed for histologic analysis. All immediately loaded implants were clinically stable. One histologic section per implant was obtained. All implants achieved osseointegration. The bone-implant contact was 38.9% for the submerged implant and 64.2% for the immediately loaded one. In the marrow space, both implants were covered by thin, neoformed bone trabeculae. Osseointegration can be achieved after 2 months by Osseotite implants placed in soft bone in the mandible either when immediately loaded and splinted into a provisional denture retained on six implants, or when submerged and unloaded.

Bite Force↗

PubMed2002

Bone-implant contact and bone quality: evaluation of expected and actual bone contact on machined and osseotite implant surfaces.

This article introduces a new technique using histomorphometrics to estimate the extent of bone-to-implant contact that might be expected on an implant surface in relation to the quality of the surrounding bone. Two implant surfaces, one machined and one Osseotite, were compared on the same implant in the same patient Eleven of these custom-made 2-mm-diameter implants were placed in the posterior maxilla and allowed to integrate. After 6 months of nonloaded healing, implants were trephined with surrounding bone tissue and prepared into histologic sections. Digitized images were analyzed at 50x magnification with image-analysis software. Bone surface area was calculated over the entire microscopic field, and the actual bone-to-implant contact for each implant surface was measured. The expected bone-to-implant contact was calculated by superimposing the profile of the implant threads on the bone image a small increment (0.15, 0.5, or 1.0 mm) from the actual implant site and counting the linear amount of bone that would be in contact with the implant surface. The actual bone-to-implant contact for Osseotite was greater than its expected bone-to-implant contact, whereas the actual bone-to-implant contact for the machined surface was mostly lower than the expected values. Thus, the Osseotite surface appears to exert a positive effect on the amount of bone approaching the implant surface and can be described as conductive, while the machined surface is nonconductive. This technique may serve to predict the clinical success that the Osseotite surface will demonstrate in poor-quality bone.

Bone Density↗

PubMedDate not supplied

Human histologic and histomorphometric analyses of hydroxyapatite-coated implants after 10 years of function: a case report.

PURPOSE: No consensus exists on the long-term performance of hydroxyapatite (HA) coatings on dental implants. The aim of this study was to evaluate the long-term stability of the HA coating in a human autopsy specimen. MATERIALS AND METHODS: Two mandibular HA-coated implants were retrieved postmortem from a woman after 10 years of functional loading with an implant/tooth-supported fixed partial denture. After ground sectioning, the specimens were histomorphometrically analyzed. RESULTS: Direct bone-implant contact was found at 78.48% of the implant surface. HA coating disappearance had occurred in a few areas (22.75%), but bone was in direct apposition to the titanium surface. Bone volume measured 27.66%, and expected bone-implant contact was 37.55%. No inflammatory reaction was seen in the supracrestal soft tissues or the bone compartment. DISCUSSION: Most of the HA coating was maintained on the implants, and areas lacking HA were directly apposed by bone. This observation suggests that the underlying titanium surface should have a macro-texture to promote the adaptation of bone to the titanium surface in case of HA disappearance, as well as to decrease failure at the HA-titanium interface. CONCLUSIONS: In a patient in whom prosthetic treatment was appropriately performed and proper plaque control was maintained, the HA coating was not damaged and contributed to the success of the implant over 10 years of clinical functioning.

Bone Density↗

PubMedDate not supplied

Bone mineral density and bone histomorphometry are statistically related.

PURPOSE: The aim of this study was to evaluate how closely analysis of bone quality performed using the bone mineral density (BMD) values obtained by quantitative computerized tomography (QCT) reflected the histologic bone density. MATERIALS AND METHODS: Eighteen patients requiring implant therapy underwent CT scanning. Their data were processed using Image Master software, and the BMD was calculated by measuring the Hounsfield units and relating those values to a phantom (Calibration Phantom, Quantitative Technologies). Each patient wore a radiographic-surgical template in which titanium cylinders were placed as a drilling guide for preparation of the implant site. The mouth regions where the titanium guides were placed (on the CT images and in the patient's mouth) corresponded to the implant sites where the BMD was measured and where tissue specimens for histomorphometric analysis retrieved. Forty specimens measuring 6 mm in length and 2 mm in diameter were obtained. Histomorphometric analysis was performed by digitizing the images, which were subsequently analyzed using the image analysis software IAS 2000. The bone volume (BV) was calculated as a percentage by dividing the area occupied by the mineralized bone over the entire microscopic field. RESULTS: The results of the statistical analysis showed a Pearson correlation coefficient of 0.691 between the BV and BMD values, with a P value < 0.01, which was considered significant. DISCUSSION AND CONCLUSION: The results of this study support the use of QCT to assess the bone quality before implant placement to improve the planning of implant treatment.

Alveolar Process↗