Biomedical subjects

Lambros Kostopoulos

Publications and source records attributed to Lambros Kostopoulos.

At least 19 recordsLinked to original sources

PubMed2007

Fully vs. partially rough implants in maxillary sinus floor augmentation: a randomized-controlled clinical trial.

OBJECTIVES: To compare implants with a rough surface in their whole length (FR) with implants having a 2 mm coronal machined portion (PR) when used in association with a sinus-lift procedure. MATERIAL AND METHODS: Twenty-six patients with 2 mm< or =x< or =9 mm residual alveolar crest were prosthetically restored with implants after a staged sinus-lift procedure using osteotomes. In 13 randomly chosen patients, no more than one FR implant was placed (test group), while the rest were PR implants. The other 13 patients received only PR implants (control group). For comparisons, only one implant from each patient was used, i.e., from the test group only the 13 FR implants were used, while from the control group, one PR implant was randomly chosen. The presence/absence of plaque, BOP, PPD and REC were registered at the day of delivery of the restorations and after 1 year. Residual alveolar crest height and marginal bone levels around the implants were evaluated on standardized periapical radiographs taken at various stages. RESULTS: Four FR and two PR implants were lost, and the cumulative survival rate was 82.9% (six lost out of 35). There were no significant differences between the two groups. Implant type, residual alveolar crest height, time of osseointegration, time of implant loading and smoking did not seem to influence implant survival. CONCLUSIONS: FR and PR implants placed in augmented sinuses did not differ in their clinical performance.

Alveolar Process↗

PubMed2006

The effect of enamel matrix proteins and deproteinized bovine bone mineral on heterotopic bone formation.

To evaluate the osteoinductive potential of deproteinized bovine bone mineral (DBBM) and an enamel matrix derivative (EMD) in the muscle of rats. Sixteen rats were used in this study. The animals were divided in three groups. Group A: a pouch was created in one of the pectoralis profundis muscles of the thorax of the rats and DBBM particles (Bio-Oss) were placed into the pouch. Healing: 60 days. Group B: a small pouch was created on both pectoralis profundis muscles at each side of the thorax midline. In one side, a mixture of EMD (Emdogain) mixed with DBBM was placed into one of the pouches, whereas in the contralateral side of the thorax the pouch was implanted with DBBM mixed with the propylene glycol alginate (PGA--carrier for enamel matrix proteins of EMD). Healing: 60 days. Group C: the same procedure as group B, but with a healing period of 120 days. Qualitative histological analysis of the results was performed. At 60 days, the histological appearance of the DBBM particles implanted alone was similar to that of the particles implanted together with EMD or PGA at both 60 and 120 days. The DBBM particles were encapsulated into a connective tissue stroma and an inflammatory infiltrate. At 120 days, the DBBM particles implanted together with EMD or PGA exhibited the presence of resorption lacunae in some cases. Intramuscular bone formation was not encountered in any group. The implantation of DBBM particles alone, combined with EMD or its carrier (PGA) failed to exhibit extraskeletal, bone-inductive properties.

Animals↗

PubMed2005

Bone formation by enamel matrix proteins and xenografts: an experimental study in the rat ramus.

The aim of this study was to evaluate whether the use of enamel matrix proteins with or without the use of deproteinized bovine bone influences bone formation when used as an adjunct to guided bone regeneration (GBR). Twenty rats, divided into four groups of five animals each, were used in this study. Group A1: A hemispherical PTFE capsule was placed empty on the lateral aspect of the mandibular ramus (GBR). At the contralateral side of the jaw, the capsule was filled with an enamel matrix derivative (EMD) before its placement. The healing period was 60 days. Group A2: The animals were treated in the same manner as in Group A1 but with a healing period of 120 days. Group B1: The animals were treated in the same manner as in Group A1 with the difference that deproteinized bovine bone mineral (DBBM) particles were packed in the capsule. At the contralateral side of the jaw, the capsule was filled with a mixture of EMD and DBBM. The healing period was 60 days. Group B2: The same treatment as in B1 but with a healing period of 120 days. The histological analysis revealed that in Groups A1 and A2 newly formed bone was covering a significant part of the empty capsules (GBR). The use of EMD in the capsule did not offer any added benefit to the use of the capsule alone in terms of new bone formation. At Groups B1 and B2, the presence of DBBM and/or EMD did not positively affect the amount of new bone formation. It can be suggested that neither the application of EMD nor the use of DBBM or the combination of EMD and DBBM results in enhanced amounts of bone formation in comparison with the GBR procedure alone.

Animals↗

PubMed2005

Long-term stability of autogenous bone grafts following combined application with guided bone regeneration.

The aim of the study was to compare the long-term stability of membranous and endochondral autogenous bone grafts with or without combined application of guided bone regeneration (GBR). Twenty-five, male, 6-month old, albino rats were used in the study. The animals were divided into four groups (A5, A11, B5 and B11). Group A5 (control): The inferior border of the mandible was exposed in both sides. At one side of the jaw, a calvarial bone graft (baseline -3 x 4 x 0.64 mm) was placed at the inferior border of the mandible and was fixed with a standardized screw-type titanium microimplant. At the contralateral side, an ischiac bone graft (baseline -3 x 4 x 0.87) was transplanted. The healing period was 5 months. Group A11 (control): The animals were treated in the same manner as in Group A5 with the difference that the healing period was 11 months. Group B5 (test): The animals were treated in the same manner as in Group A5 with the difference that an e-PTFE membrane was adapted over the bone graft on each side of the jaw. Group B11 (test): The animals were treated in the same manner as in Group B5 with the difference that 5 months following transplantation the animals were subjected to a second operation and the membranes were removed. The healing period was 11 months. The animals were killed at 5 (Groups A5 and B5) or at 11 months (Groups A11 and B11) following mandibular augmentation and the jaws were defleshed. The width, the length and the thickness/height of the bone graft were evaluated by means of a stereomicroscope. At 5 months, both types of the membrane-treated bone grafts presented increase in all dimensions compared with baseline. However at 11 months, both types of the membrane-treated bone grafts exhibited a decrease in their dimensions which were similar to the baseline measurements. In the control groups, both types of bone graft presented significant resorption both at 5 and at 11 months with the ischiac bone grafts presenting more resorption in width and length than the calvarial bone grafts. It can be concluded that the long-term volume stability of autogenous endochondral and membranous onlay bone grafts combined with GBR is superior to that of autogenous endochondral and membranous onlay bone grafts alone.

Animals↗

PubMed2005

Clinical and radiographic performance of delayed-immediate single-tooth implant placement associated with peri-implant bone defects. A 2-year prospective, controlled, randomized follow-up report.

OBJECTIVES: The aim of the present study was to compare the delayed-immediate (Im) and the delayed (De) protocols for placement of single-tooth implants. MATERIAL AND METHODS: After allocation to the Im and De groups by random, 46 patients were treated with a single-tooth implant with acid etched surfaces (Osseotite) in the anterior or pre-molar region of the maxilla or the mandible on average 10 days (Im) or 3 months (De) following tooth extraction, respectively. Forty-one patients attended a follow-up visit 2 years after implant placement corresponding to 1(1/2) years of loading of the implant restorations. Peri-implant and prosthetic parameters were evaluated clinically and marginal bone levels measured on radiographs. RESULTS: Three implants were lost, all before mounting of the crown. None of the implant restorations had failed after 1(1/2) years of function. Probing pocket depths were reduced by up to 1.4 mm on average from the time of loading to the 2-year follow-up and at that time, no significant difference between the Im and De groups was found (4.2 versus 4.1 mm). A statistically significant radiographic marginal bone loss had occurred in the Im group (mean=0.8 mm) as well as in the De group (mean=0.7 mm) in the follow-up period. However, a mean marginal bone level of approx. 1.5 mm in both groups measured from the implant-abutment junction was found to be acceptable. It was demonstrated that probing pocket depths and marginal bone levels after 1(1/2) years of loading of the implant-retained crowns were not influenced by the presence of peri-implant bone defects immediately after implant placement. Furthermore, no severe prosthodontic complications, such as screw loosening or porcelain fractures, arose in this study material. CONCLUSION: High success rates of single-tooth implants after 1(1/2) years of function were achieved using the delayed-immediate and delayed implant placement techniques.

Alveolar Bone Loss↗

PubMed2005

Implant placement in bone formed beyond the skeletal envelope by means of guided tissue regeneration: an experimental study in the rat.

OBJECTIVES: The aim of the present study was to evaluate whether the placement of implants in bone formed by means of guided tissue regeneration (GTR) beyond the skeletal envelope may influence bone volume and/or structure. MATERIAL AND METHODS: Rigid, hemispherical, Teflon capsules were placed with their open part facing the lateral surface of the ramus in both sides of the mandible in 18 rats. After 1 year, the capsules were removed by a re-entry operation, and a custom-made titanium implant was placed in the augmented ramus in only one side of the jaw. Six animals were sacrificed shortly after implant surgery, another six after 3 months, and the last six after 6 months. Histological specimens of the augmented sites including the implants were prepared, and the volumes of (1) the newly formed bone (mineralized bone and marrow) (2) the soft connective tissue, and (3) the implant, in the space originally created by the capsule were estimated by a point-counting technique. Additionally the height of the augmented bone was measured. RESULTS: One year after capsule placement, the major portion of the space originally created by the capsules was filled with newly formed bone. In the test specimens, implant placement seemed to result in a denser arrangement of the augmented bone, but this event did not influence its long-term stability. Although some resorption occurred after 3 and 6 months, the vast portion of the generated bone remained stable over time in both tests and controls, and there were no differences between tests and controls at any observation periods. CONCLUSION: It is concluded that large amounts of bone can be formed beyond the skeletal envelope by means of GTR, and that this bone remains stable on a long-term basis both with and without the placement of titanium implants.

Animals↗

PubMed2004

Fate of bone formed by guided tissue regeneration with or without grafting of Bio-Oss or Biogran. An experimental study in the rat.

OBJECTIVES: The aim of the study was to examine whether bone produced by guided tissue regeneration (GTR) in combination with Bio-Oss or Biogran is stable on a long-term basis. MATERIAL AND METHODS: Fifty-four, 3-month-old Wistar rats were divided into three groups and rigid, hemispherical, teflon capsules were placed with their open part facing the lateral surface of the exposed mandibular ramus (one capsule per animal). In the first group, the capsules were loosely packed with a standardized quantity of Bio-Oss, in the second group with Biogran, and in the last group were left empty. After 1 year of healing, the capsules were removed. Six animals from each of the 3 experimental groups were killed immediately after capsule removal (baseline), or 3 or 6 months after re-entry. The volume of (1) newly formed bone, (2) remaining biomaterial particles, and (3) soft connective tissue in the space originally created by the capsule was estimated by a point-counting technique in three to four histological sections, taken by uniformly random sampling. RESULTS: While considerable bone formation had occurred in the empty control capsules, only limited bone formation was observed in the two test groups. The major portion of the space originally created by the capsules in the test groups was occupied by biomaterial particles embedded in connective tissue. At baseline, the mean volume of newly formed bone occupied 23% of the original capsule space in the animals grafted with Bio-Oss, 12.6% in those implanted with Biogran, and 94.1% in those that received empty control capsules. Six months after capsule removal, the corresponding values were 21.5%, 13.2%, and 91.7%, respectively. No statistically significant differences were observed between baseline, and the 3-, and 6-month observation times in terms of bone volume for any of the three treatment groups (p>0.05). CONCLUSION: Bone produced by GTR with and without implantation of Bio-Oss, or Biogran, is stable on a long-term basis, but bone formation is obstructed by implantation of these biomaterials.

Animals↗

PubMed2004

Effect of GBR in combination with deproteinized bovine bone mineral and/or enamel matrix proteins on the healing of critical-size defects.

OBJECTIVES: To evaluate the effect of guided bone regeneration (GBR) in combination with or without deproteinized bovine bone mineral (DBBM) and/or an enamel matrix derivative (EMD) on the healing of critical-size calvarial defects. MATERIAL AND METHODS: Forty rats were used. In all animals, a standardized critical-size calvarial defect was created surgically. The animals were randomly allocated into 4 groups of 10 animals each. Group A: One calvarial defect was left untreated, while the galeal and the cerebral aspect of the contralateral defect were covered with a bioresorbable membrane (GBR). Group B: One calvarial defect was filled with EMD, while the contralateral defect was treated with GBR and EMD. Group C: One defect was filled with DBBM, while the contralateral defect was treated with combination of GBR and DBBM. Group D: One defect was filled with DBBM combined with EMD, while the contralateral defect was treated with combination of GBR, DBBM and EMD. The healing period was 4 months. Five specimens from each group were macerated and the length, the width and the vertical dimension (thickness) of the remaining defect were evaluated by a stereomicroscope. The remaining specimens in each group were analyzed histologically. RESULTS: The defects of the macerated specimens that were left untreated or were treated only by EMD, DBBM and combination of EMD and DBBM did not present predictably complete healing of the defects. All the defects where GBR was applied alone or combined with DBBM and/or EMD presented always complete healing (P<0.05). The combined use of GBR with EMD and/or DBBM did not offer any significant advantage above GBR alone in terms of healing of the length and the width of the defect. However, the vertical dimension of the defect was significantly higher (P<0.05) in the GBR-treated specimens of Groups C and D. The histological analysis supported these findings. CONCLUSION: The predictability of bone formation in critical-size defects depends mainly on the presence or absence of barrier membranes (GBR). The combined use with deproteinized bovine bone mineral and/or enamel matrix proteins did not significantly enhance the potential for complete healing provided by the GBR procedure.

Animals↗

PubMed2004

Patient experience of, and satisfaction with, delayed-immediate vs. delayed single-tooth implant placement.

OBJECTIVES: Recent investigations have focused on patients' subjective assessment of implant treatment. The aim of this study was to compare the patients' experience of surgical and prosthetic procedures, as well as satisfaction with function and aesthetics following single-tooth replacements mounted to early vs. delayed placed dental implants. MATERIAL AND METHODS: Forty-six patients were treated with a single-tooth implant in the anterior or premolar region. Twenty-three implants were placed on average 10 days after tooth extraction (Im), while 23 implants were placed approximately 3 months after tooth extraction (De). Forty-one patients completed a questionnaire regarding the treatment using visual analog scales (VAS) and check boxes 16-18 months after delivery of the restoration. RESULTS: In all, 90% of the respondents rated 88 or higher on the VAS regarding satisfaction with the crown. Satisfaction with the restoration in general and the appearance was significantly greater in the Im group than in the De group (96 vs. 93; P<0.02). Assessment of the implant surgery was not significantly different between the delayed-immediate and the delayed group. Approximately 25% of the patients experienced unpleasantness in relation to the prosthetic procedures, and in 8 of 11 cases, impression taking was the cause. When evaluating satisfaction with the overall implant treatment, the VAS scores for the delayed-immediate group were significantly higher than for the delayed group (96 vs. 90; P<0.02). CONCLUSION: The patients in the present study were highly satisfied with the outcome of the treatment and experienced it to be without significant unpleasantness irrespective of the treatment concept.

Adult↗

PubMed2004

Susceptibility of GTR-regenerated periodontal attachment to ligature-induced periodontitis.

AIM: This study aimed to compare the susceptibility of guided tissue regeneration (GTR)-regenerated periodontal attachment to ligature-induced periodontitis with that of the pristine periodontium. METHODS: Periodontal breakdown was produced in four monkeys by the placement of orthodontic elastics around experimental teeth (test teeth). During a flap operation, the root surfaces were scaled and planed, and a notch indicating the apical termination of scaling and root planing was made in the root surface. Following resection of the crowns and endodontic treatment, an e-PTFE membrane was adapted over the roots. Subsequently, the flaps were sutured to complete closure of the wound (submerged). At membrane removal after 5 weeks, the crowns of the contralateral teeth serving as controls were resected, and the roots treated endodontically during a flap operation. Artificial composite crowns were then placed on both test and control roots. After 3 months of tooth cleaning, cotton floss ligatures were placed passively around both test and control teeth for a period of 6 months. Two weeks later the animals were sacrificed. RESULTS: Histological analysis demonstrated that the instrumented root surfaces of the test teeth were covered by newly formed cementum of the reparative, cellular, extrinsic and intrinsic fiber type, while the cementum on the controls was mainly acellular extrinsic fiber cementum. Histometric assessments demonstrated that similar attachment loss had occurred on test (1.0+/-0.5 mm) and control roots (1.0+/-0.4 mm) during the 6 months of ligature-induced plaque accumulation. CONCLUSION: The results indicate that teeth with a periodontal attachment apparatus formed by GTR is not more susceptible to periodontitis than those with a pristine periodontium.

Animals↗

PubMed2003

Deproteinized bovine bone (Bio-Oss) and bioactive glass (Biogran) arrest bone formation when used as an adjunct to guided tissue regeneration (GTR): an experimental study in the rat.

OBJECTIVES: Grafting of deproteinized bovine bone or bioactive glass has been suggested as an adjunct to guided tissue regeneration (GTR) for the treatment of periodontal and peri-implant bone defects but the influence of these materials on bone formation is not clarified. The aim of the study was to examine the long-term influence of deproteinized bovine bone (Bio-Oss) or bioactive glass (Biogran) on bone formation produced by GTR. MATERIAL AND METHODS: Eighteen rats were used. Following incisions along the inferior border of the mandible, muscle-periosteal flaps were raised to expose the mandibular ramus. Rigid, hemispherical, Teflon capsules (6 mm internal diameter and 1 mm peripheral collar) loosely packed with a standardized quantity of either deproteinized bovine bone (test group 1) or bioactive glass (test group 2), or empty capsules (control group) were then placed with their open part facing the lateral surface of the ramus (one capsule per animal). After 1 year, the capsules were removed by a reentry operation, and the animals were sacrificed. Histological specimens of the augmented sites were prepared, and the volumes of (1). newly formed bone, (2). graft particles, and (3). soft connective tissue in the space originally created by the capsule were estimated by a point-counting technique in three to four histological sections, taken by uniformly random sampling. RESULTS: Limited bone formation was observed in the two test groups. The major part of the space originally created by the capsules was occupied by graft particles embedded in connective tissue. The mean volume of newly formed bone occupied only 23% of the total space in the animals grafted with Bio-Oss and 12.6% in those grafted with Biogran. In the control animals, however, 88.2% (p<0.01) of the space was filled with newly formed bone. There were no signs of ongoing bone formation in any of the three experimental groups. CONCLUSION: It is concluded that grafting of Bio-Oss or Biogran as an adjunct to GTR arrests bone formation.

Animals↗

PubMed2003

Influence of demineralized bone matrix's embryonic origin on bone formation: an experimental study in rats.

BACKGROUND: There are results suggesting that differences regarding bone-inducing potential, in terms of amount and/or rate of bone formation, exist between demineralized bone matrices (DBMs) of different embryonic origins. PURPOSE: The aim of the present study was to examine whether the embryonic origin of DBM affects bone formation when used as an adjunct to guided tissue regeneration (GTR). MATERIALS AND METHODS: Endomembranous (EM) and endochondral (ECH) DBMs were produced from calvarial and long bones of rats, respectively. Prior to the study the osteoinductive properties of the DBMs were confirmed in six rats following intramuscular implantation. Following surgical exposure of the mandibular ramus, a rigid hemispheric Teflon capsule loosely packed with a standardized quantity of DBM was placed with its open part facing the lateral surface of the ramus in both sides of the jaw in 30 rats. In one side of the jaw, chosen at random, the capsule was filled with EM-DBM, whereas in the other side ECH-DBM was used. Groups of 10 animals were sacrificed after healing periods of 1, 2, and 4 months, and undecalcified sections of the capsules were produced and subjected to histologic analysis and computer-assisted planimetric measurements. RESULTS: During the experiment increasing amounts of newly formed bone were observed inside the capsules in both sides of the animals' jaws. Limited bone formation was observed in the 1- and 2-month specimens, but after 4 months of healing, the newly formed bone in the ECH-DBM grafted sides occupied 59.1% (range 45.6-74.7%) of the area created by the capsule versus 46.9% (range 23.0-64.0%) in the EM-DBM grafted sides (p =.01). CONCLUSION: It is concluded that the embryonic origin of DBM influences bone formation by GTR and that ECH-DBM is superior to EM-DBM.

Animals↗

PubMed2003

Bone healing and soft tissue contour changes following single-tooth extraction: a clinical and radiographic 12-month prospective study.

Preservation of alveolar bone volume following tooth extraction facilitates subsequent placement of dental implants and leads to an improved esthetic and functional prosthodontic result. The aim of the present study was to assess bone formation in the alveolus and the contour changes of the alveolar process following tooth extraction. The tissue changes after removal of a premolar or molar in 46 patients were evaluated in a 12-month period by means of measurements on study casts, linear radiographic analyses, and subtraction radiography. The results demonstrated that major changes of an extraction site occurred during 1 year after tooth extraction.

Adult↗

PubMed2002

Augmentation of the mandible with GTR and onlay cortical bone grafting. An experimental study in the rat.

The aim of the present study was to evaluate the effect of augmenting the mandible with onlay mandibular bone grafts that were covered with e-PTFE membranes according to the principle of guided tissue regeneration (GTR). The experiment was carried out in 30 rats. The inferior border of the mandible and parts of the mandibular body were exposed on both sides. On one side, an autogenous bone graft that was harvested from the angle of the mandible was placed on the inferior border of the mandible and was fixed with a titanium microimplant. Subsequently, the graft was covered with an e-PTFE membrane. The contralateral side, serving as control, was treated the same way except for the placement of the membrane. Groups of six animals were sacrificed 15, 30, 60, 120 and 180 days following surgery, and specimens that were prepared from the experimental and control sites were analyzed histologically. The bone graft underneath the membrane initially presented superficial resorption but, subsequently, the space that was created by the membrane gradually became filled with bone. After 180 days, the area underneath the membrane was completely filled with bone and it was impossible to distinguish between the bone graft and the newly formed bone. Generally, the bone grafts at the control sides were characterized by a gradual resorption during the entire experimental period. At 180 days after transplantation, only a few grafts at the control sites had retained their height, and there was frequently a lack of continuity between the bone graft and the underlying mandibular bone. It can be concluded that onlay mandibular bone grafts combined with GTR may improve the predictability of mandibular augmentation, in comparison to bone grafting alone.

Alveolar Ridge Augmentation↗

PubMed2002

Alveolar ridge augmentation by combining autogenous mandibular bone grafts and non-resorbable membranes.

The aim of the present study was to evaluate the effect of using mandibular cortical bone grafts covered with e-PTFE membranes for maxillary alveolar ridge augmentation, in comparison with the use of mandibular cortical grafts alone. The experiment was carried out in 20 rats. At one side of the maxillary jaw, the edentulous alveolar ridge between the incisor and the first molar was augmented by means of an autogenous mandibular bone graft, which was fixed with a titanium microimplant and covered with a Teflon membrane. The contralateral side, serving as control, was treated the same way, except for the placement of a membrane. Histological analysis at 15, 30, 60 and 90 days after surgery demonstrated that, in situations where the membrane was not exposed to the oral cavity during healing, the mandibular bone grafts presented no resorption and were in continuity with the maxillary bone at the recipient site. In situations where the membrane had become exposed, however, the bone grafts presented extensive resorption and lack of continuity with the bone at the recipient site. These latter findings were similar to those made at the non-membrane-treated side. The results indicate that the volume of autogenous bone graft used for alveolar ridge augmentation can be retained by covering the graft with a membrane, provided that the membrane is properly adapted and is kept covered with mucosa during healing.

Alveolar Ridge Augmentation↗

PubMed2002

Augmentation of the rat jaw with autogeneic cortico-cancellous bone grafts and guided tissue regeneration.

The aim of the present study was to evaluate the effect of augmenting the maxillary alveolar ridge and the lateral aspect of the mandible with onlay autogeneic cortico-cancellous bone grafts that were covered with e-PTFE membranes. The experiment was carried out in 51 rats. In 15 rats, the edentulous maxillary jaw between the incisor and the first molar was augmented by means of an autogeneic ischiac bone graft that was fixed with a gold-coated microimplant. In one side, the graft was covered with an e-PTFE membrane, while the other side, which served as control, was treated without a membrane. In the other 36 rats, the lateral aspect of the mandible was augmented in both sides by means of an autogeneic ischiac bone graft that was fixed with a gold-coated or a titanium microimplant. In one side, the augmented area was covered with an e-PTFE membrane, while the contralateral side was treated without a membrane. Histological analysis at 60, 120 and 180 days after augmentation of the maxilla showed that, in the case of the test sites (where most of the membranes were either exposed or lost), the bone grafts presented extensive resorption and there was a lack of bone continuity between the graft and the recipient site. Similar findings were made at the non-membrane-treated control sides. In the case of augmentation of the mandible with membranes, the bone grafts were not resorbed, but were integrated into newly formed bone at the recipient site. In the control sides, the grafts presented varying degrees of resorption and integration into the recipient bone. It is concluded that, in comparison to bone grafting alone, onlay ischiac bone grafting combined with guided tissue regeneration eliminates the risk of bone graft resorption and ensures integration of the graft into newly formed bone at the recipient site, provided that closure of the operated area can be maintained during healing.

Alveolar Ridge Augmentation↗

PubMed2002

Alveolar ridge augmentation using a resorbable copolymer membrane and autogenous bone grafts. An experimental study in the rat.

The aim of the present study was to compare the result of maxillary alveolar ridge augmentation by the combined use of mandibular bone grafts and resorbable membranes (Resolut), with that achieved by the use of the same type of bone graft combined with the placement of e-PTFE membranes (Gore-Tex). The experiment was carried out in 30 rats. In one side of the maxillary jaw, the edentulous alveolar ridge between the incisor and the first molar was augmented by means of an autogenous mandibular bone graft that was fixed with a titanium microimplant and covered with a resorbable membrane. The contralateral side, serving as control, was treated in the same way, with the difference that an e-PTFE membrane was placed over the bone graft. Histological analysis at 15, 30, 60, 120 and 180 days after surgery demonstrated that, in both test and control sites where the membrane was properly adapted and not exposed, the bone grafts presented no resorption and were integrated into the maxillary bone at the recipient site. In cases where the membrane was exposed, however, the bone grafts presented extensive resorption and lack of continuity between the graft and the recipient bed. At 60-180 days after surgery, the exposure of both types of membrane had frequently led to complete resorption of the grafts, encapsulation of the titanium microimplant by fibrous connective tissue, or exfoliation of the microimplant. It is concluded that alveolar ridge augmentation can be predictably accomplished by combining mandibular bone grafting with the placement of resorbable or non-resorbable membranes according to the GTR principle, provided that the membrane is properly adapted over the graft and complete closure of the treated area is maintained during healing.

Absorbable Implants↗

PubMed2002

Bone and suture regeneration in calvarial defects by e-PTFE-membranes and demineralized bone matrix and the impact on calvarial growth: an experimental study in the rat.

The aim of this study was to evaluate the effect of: guided tissue regeneration (GTR) alone, implantation of demineralized bone matrix (DBM) alone, and of the combined treatment on the healing of craniectomy defects involving the sagittal cranial suture, and to examine subsequent calvarial growth. Sixty four-week-old rats were used in the study. These animals were randomly assigned to five groups (A-E) of 12 animals. In four groups (A-D), a calvarial defect (5.0 mm) involving the sagittal suture was produced in each animal. Group A: The defect was left untreated. Group B: DBM was implanted into the defect. Group C: The cerebral and the galeal aspect of the defect was covered with an e-PTFE membrane. Group D: The defect was treated with the double membrane technique combined with implantation of DBM. Group E: The animals were sham-operated, no defect was created. In all groups, two gutta-percha points were placed to indicate the lateral borders of the parietal bones. Histological analysis 4 months following surgery showed that the untreated cranial defects (A) had healed with fibrous connective tissue in the midportion of the defect. The DBM grafted defects (B) healed either completely with bone containing DBM particles or partially with bone and connective tissue. The defects (D) treated with DBM combined with GTR healed completely with bone, while the defects (C) treated with membranes alone healed with bone but a suture-like tissue similar to the normal sagittal suture of the sham-operated controls (E) was always present in the midportion of the defect. Cephalometric radiography demonstrated that the membrane-treated (C) and the sham-operated animals (E) exhibited similar coronal growth of the cranial vault following treatment. Craniometric measurements on chemically defleshed specimens showed that sham-operated and membrane-treated animals presented significantly more biparietal width than the animals treated with DBM alone or DBM combined with GTR (P < 0.05). The results demonstrated that predictable osseous healing including the formation of a sagittal suture can be accomplished in craniectomy defects by GTR, and undisturbed cranial growth reestablished. The treatment of the defects with DBM alone or DBM combined with GTR resulted in craniosynostosis and reduced cranial growth.

Analysis of Variance↗