Contribution of the periosteum to bone formation in guided bone regeneration. A study in monkeys.

The periosteum has been referred to as a protective barrier in the regeneration of bone defects. The objective of this study was to determine the contribution of periosteum as a natural barrier to bone formation in guided bone regeneration. Mucoperiosteal flaps were elevated bilaterally on the buccal aspect of the mandibular angle in 5 cynomolgus monkeys. Bleeding was induced by perforating the cortical bone. A hemispherical titanium mesh was fixed over the areas thus creating a void 5 mm in height between the mesh and the bone surface. One one side the mesh was covered with an ePTFE membrane (test side). The contralateral side did not receive further treatment (control side). After 4 month healing, histomorphometric analyses were used to determine the percentage of new bone in the void underneath the mesh, and the ratio between mineralized tissue and marrow spaces in new and old bone. The mean percentage of new bone tissue was 77.2 +/- 7.5% for the test sides and 68.6 +/- 8.4% for the control sides (P = 0.018, t-test). This new bone contained 80.0 +/- 3.6% mineralized tissue in the test group and 82.5 +/- 5.0% in the control group (P > 0.05, t-test). In both groups the newly formed bone exhibited significantly less mineralized tissue than the old bone (P < 0.05, t-test). It is concluded from this study that new bone formation was enhanced by the additional use of an ePTFE membrane under a periosteum-lined mucoperiosteal flap when space maintenance was excluded as a critical factor.

Changes in peri-implant tissues subjected to orthodontic forces and ligature breakdown in monkeys.

The aims of this investigation were to histologically evaluate in monkeys the effect of a repetitive mechanical trauma alone on the peri-implant tissues, and the effect of a repetitive mechanical trauma in combination with ligature-induced peri-implantitis on the peri-implant tissues. The study used 5 male cynomolgus monkeys. Prior to the start of the study, all premolars and the first and second molars in the mandible were extracted. After a healing period of 12 weeks, following tooth extraction, split/full thickness flaps were elevated on both sides of the mandible in order to expose the bony ridge. Four implants, of 3.75 mm in diameter and 7 mm in length, were then inserted on each side and the flaps were readapted and sutured in place. Following a healing period of 16 weeks, the second stage procedure was performed, impressions were taken, and custom-made crowns using a non-precious metal alloy were fabricated and inserted on all implants 4 weeks after abutment connection. At the same time peri-implantitis was induced on one side of the mandible by placing plaque-retentive ligatures around the implants. On the other side, an oral hygiene program consisting of thrice weekly brushing with a toothbrush and flour of pumice mixed with 2% chlorhexidine was initiated. Four months later, a repetitive mechanical trauma was initiated on implants 1 and 2 on both sides in the mandible. Consequently, a split mouth design was obtained: 1) test 1=ligature-induced peri-implantitis alone (LPNO); 2) test 2=ligature-induced peri-implantitits with a repetitive mechanical trauma (LPMT); 3) test 3=healthy peri-implant tissues with a repetitive mechanical trauma (MT); and 4) control (NO)=healthy peri-implant tissues with no repetitive mechanical trauma. Following 16 weeks of repetitive mechanical trauma the animals were sacrificed. Histologic observations and computed-assisted histometric and histomorphometric analyses were performed to determine the amount of peri-implant bone loss and the percentage of direct mineralized bone-to-implant contact around each endosseous oral implant. Histologically, all implants yielded osseointegration at the light microscopic level. There was a significant difference regarding the mean direct mineralized bone-to-implant contact length as a fraction of the total implant length between the healthy (i.e., MT and NO) and diseased sites (i.e., LPNO and LPMT) (P < 0.05). When comparing the percent of direct mineralized bone-to-implant contact for the 2 best threads of each implant and group, no significant difference (P=0.675) could be detected. Under the conditions of this study, the repetitive mechanical trauma showed no histologic effect on the peri-implant bone loss neither in healthy nor in diseased implant sites. The effects of excessive loading on osseointegration are presently not clearly understood. The key problem seems to be the determination when loading on implants exceeds the physiological range of bone adaptation which may then cause implant failure. Further research to elucidate this problem is essential.

Healing patterns in recession defects treated with ePTFE membranes and with free connective tissue grafts. A histologic and histometric study in the beagle dog.

This study focussed on the biologic success of 2 different procedures for root coverage. In the maxillary canines of 7 beagle dogs, buccal recessions were created and treated on one side with an ePTFE membrane (GTR-group) and on the contralateral side with a free connective tissue graft from the palate (CT-group). 2 areas served as negative controls. After 4 months of healing, histologic sections were processed and histologically analyzed. The evaluated parameters were coverage height, bone, cementum and connective tissue attachment regeneration, length of the epithelium, resorption, and ankylosis. Histologically, both GTR-group and CT-group produced more new bone, new cementum and new connective tissue attachment than the two control teeth. When histologically evaluated, the amount of new bone was more pronounced in the GTR-group than in the CT-group, however, no statistical differences in any of the evaluated parameters could be detected between the 2 procedures tested. Frequency and distribution of resorption and ankylosis were similar in the GTR-group and in the CT-group. Within the limits of this study, no differences in terms of the biologic rehabilitation between those recessions treated with ePTFE membranes and those treated with a free connective tissue graft could be found.

Clinical comparison of resorbable and non-resorbable barriers for guided periodontal tissue regeneration.

The purpose of this study was to compare the clinical results of guided periodontal tissue regeneration (GPTR) using a resorbable barrier manufactured from a copolymer of polylactic and polyglycolic acids (Resolut Regenerative Material) with those of non-resorbable e-PTFE barrier (Gore-Tex Periodontal Material). 12 subjects participated, 6 with similarly paired class II furcations and 6 with 2 similar 2, 3-wall periodontal lesions. The resorbable and non-resorbable barriers were randomly assigned to 1 defect in each subject. Non-resorbable barriers were removed in six weeks. Plaque index (PlI), gingival index (GI), probing depth (PD), clinical attachment level (CAL) and gingival recession (R) were recorded at baseline, (i.e., immediately prior to surgery) and at 12 months postsurgically. The clinical healing was similar and uneventful in both groups. Intrabony pockets depicted significant changes from baseline (p < 0.05) for probing depth reduction and gain in clinical attachment levels. No differences were found between treatments. Class II furcations showed significant improvements from baseline (p < or = 0.05) for probing depth reduction and clinical attachment gain. No differences were detected between treatments. It is concluded that the resorbable barrier tested is as effective as the nonresorbable e-PTFE barrier for the treatment of class II furcations and intrabony defects.

Guided bone regeneration around dental implants in the atrophic alveolar ridge using a bioresorbable barrier. An experimental study in the monkey.

The aim of this study was to evaluate guided bone regeneration (GBR) around dental implants placed in atrophic alveolar ridges using an experimental, nonporous bioresorbable barrier. In 8 Rhesus monkeys, the maxillary canines and lateral incisors were extracted bilaterally and the remaining alveoli were reduced to create atrophic ridges. After a healing period of 3 months, soft tissue expansion was performed using a subperiosteal tissue expander. After 1 month of tissue expansion, and IMZ implant was placed in the atrophic ridge on each side in such a way that its coronal 4 mm to 5 mm remained circumferentially exposed above the bone level. The test implants were covered with a bioresorbable barrier made of poly (D,L-lactid-co-trimethylencarbonate) in a 70/30 ratio, whereas the control implants were covered with a nonresorbable expanded polytetrafluoroethylene (e-PTFE) barrier. The e-PTFE barriers were stabilized with titanium minipins while the bioresorbable barriers were analogously fixed using bioresorbable minipins made of poly (L-lactid-co-D,L-lactid) 70/30. Clinical healing progressed uneventfully in both groups and no soft tissue dehiscences occurred. Histometric and histomorphometric analyses were performed 5 months post surgery. Both test and control implants exhibited direct bone-to-implant contact to variable extents. The mean direct mineralized bone-to-implant contact length fraction was 32% of the total implant length in the test sites and 58% in the control sites. Control sites exhibited significantly greater bone fill compared to the experimental sites (P < 0.001). Histologic observations of test specimens demonstrated a moderate inflammatory reaction related to the degradation and resorption products of the barrier. In conclusion, the nonresorbable e-PTFE GBR barrier was found to be superior to the bioresorbable barriers tested in the present investigation.

Guided periodontal tissue regeneration in interproximal intrabony defects following treatment with a synthetic bioabsorbable barrier.

This study evaluated guided periodontal tissue regeneration (GPTR) wound healing in interproximal intrabony periodontal defects following surgical treatment with a synthetic bioabsorbable barrier made from a copolymer of glycolide and lactide. Periodontal lesions were induced around the mandibular central incisor teeth of 10 adult male rhesus monkeys using orthodontic elastics. Once similar contralateral interproximal defects had been created, the elastics were removed and an oral hygiene program was initiated and maintained until completion of the study. Three weeks after commencing oral hygiene, flap surgery was performed in the mandibular incisor region and the root surfaces were thoroughly scaled and root planed to the apical portion of the defects. On the test sites, a bioabsorbable barrier was placed over the entire interproximal periodontal defect. Control sites did not receive a barrier. Five months after surgery, the animals were sacrificed and the teeth with their supporting periodontium were processed for light microscopic evaluation. Postoperative clinical healing progressed uneventfully and was similar in both control and test sites. Histologic observations from control specimens indicated reparative healing characterized by a long junctional epithelium with limited cementum and bone formation. Test specimens exhibited significantly more new connective tissue attachment, cementum deposition, and bone formation than the control sites (P < 0.001). The barriers had been completely resorbed with no apparent adverse effect on periodontal wound healing. It was concluded that this bioabsorbable barrier facilitated GPTR wound healing in interproximal intrabony periodontal defects.

Guided periodontal tissue regeneration in Class II furcation defects following treatment with a synthetic bioabsorbable barrier.

The purpose of this study was to evaluate guided periodontal tissue regeneration (GPTR) wound healing in Class II furcation defects following surgical treatment with a synthetic bioabsorbable barrier manufactured from a copolymer of glycolide and lactide. Periodonal lesions were induced in four adult male rhesus monkeys around the mandibular first, second, and third molar teeth using orthodontic elastics. After obtaining approximately 30% bone loss, the elastics were replaced by a stainless steel wire which had a projection extending into the furcation. Once similar contralateral Class II furcation defects had been created, the wires were removed, and an oral hygiene program was initiated and maintained until completion of the study. Three weeks after commencing oral hygiene, flap surgery was performed in the mandibular molar region and the root surfaces were thoroughly scaled and root planed to the apical portion of the defects. A bioabsorbable barrier was then placed to cover the furcation defects on one side of the jaw (i.e., test sites). No barriers were placed on the contralateral molars (i.e., control sites). Five months after surgery, the animals were sacrificed and the teeth with their supporting periodontium were processed for light microscopic evaluation. Clinical healing progressed normally and was similar in both groups. Histologic observations from control specimens indicated repair with epithelium and connective tissue occupying the majority of the furcation defects. Test specimens exhibited definitive evidence of regeneration with significantly greater new connective tissue attachment, cementum deposition, and bone formation than the control sites (P < 0.001). It was concluded that this bioabsorbable barrier facilitated GPTR wound healing in Class II furcation defects.

Treatment of peri-implantitis using guided bone regeneration and bone grafts, alone or in combination, in beagle dogs. Part 2: Histologic findings.

The aim of this study was to histologically evaluate and compare the treatment of ligature-induced peri-implantitis using guided bone regeneration, two bone grafts alone, or guided bone regeneration combined with one of the two bone graft materials. Mandibular premolars and first molars in seven beagle dogs were extracted. After placement of Brånemark implants and connection of abutments, experimental peri-implantitis was induced. Flap surgery was performed, abutments were removed, and implant surfaces were treated with an air-powder abrasive unit. Bony defects were randomly treated with either (1) debridement only; (2) debridement plus resorbable hydroxyapatite; (3) debridement plus canine demineralized freeze-dried bone; (4) debridement plus guided bone regeneration; (5) debridement plus resorbable hydroxyapatite and guided bone regeneration; or (6) debridement plus canine demineralized freeze-dried bone and guided bone regeneration. Four months after surgery, a flap was elevated and the barriers were removed. One month later, the animals were sacrificed, and the implants with their supporting peri-implant tissues were processed for histologic evaluation. Guided bone regeneration procedures resulted in the greatest amount of new bone formation, followed by bone grafts alone, and flap debridement. There was no significant difference between guided bone regeneration and both guided bone regeneration/graft combinations in terms of bone regeneration; however, the guided bone regeneration/graft combinations resulted in a greater amount of "reosseointegration" than all of the other treatments. Therefore, the combination of guided bone regeneration with either demineralized freeze-dried bone or resorbable hydroxyapatite appears to be the treatment of choice for plaque-induced peri-implant defects.

Vascular response to guided tissue regeneration procedures using nonresorbable and bioabsorbable membranes in dogs.

Revascularization of the periodontal tissues was studied following guided tissue regeneration (GTR) procedures using both nonresorbable and bioabsorbable membranes. The procedures were performed in 8 female beagle dogs, 4 to 6 years old. Second, third, and fourth mandibular premolars were involved; experimental periods covered from 3 days to 49 days. After elevation of soft tissue flaps, Class II furcation defects were prepared by removing buccal alveolar bone from the teeth and exposed root surfaces were planed in order to remove root cementum. The quadrant was then flushed with sterile saline. Randomly selected, in one quadrant, the second and fourth premolars received nonresorbable expanded polytetrafluoroethylene (ePTFE) membranes. The other quadrant, second and fourth premolars, received the bioabsorbable membranes, made of glycolide and lactide polymers. After the membranes were in place, they were sutured. The third premolars of both quadrants served as negative controls. The animals were sacrificed by exsanguination under general anesthesia and then perfused through the carotid arteries with a combined solution of equal parts of India ink and 10% buffered formalin. Following fixation and demineralization, part of the blocks were processed to obtain cleared specimens following the method of Spalteholtz. The remaining blocks were processed for routine histologic examination. The findings, mainly from the cleared specimens, showed that at the early phase of healing, ePTFE membranes interfered with the revascularization while they were in place. Contrary to this, bioabsorbable membranes allowed earlier anastomosis of the vasculature of the flap and regenerated tissues. However, the long-term vascular response was similar for both membranes.

Treatment of gingival recession using guided periodontal tissue regeneration.

Gingival recession is an apical displacement of the gingival margin and involves loss of connective tissue attachment and the supporting alveolar bone. Various treatment modalities have been utilized in the treatment of gingival recession in order to eliminate etiologic factors, achieve root coverage, regenerate the lost periodontal attachment, and prevent perpetuation of the disease. During the past two decades, the broad concept of guided tissue regeneration has become specific, identifying the specific treatment involved as guided bone regeneration and guided periodontal tissue regeneration. The learning objective of this article is to review the literature and principles of guided periodontal tissue regeneration in the treatment of gingival recession and to describe the surgical technique for clinical application of these principles. Several cases are utilized to illustrate the detailed clinical presentation of selective cell repopulation of gingival tissue defects.

Augmentation of the maxillary sinus: a surgical technique.

Specific anatomic and physiologic differences between the maxillary and mandibular arches have presented challenges in restoring the fully or partially edentulous maxilla. These differences include the quality and quantity of available bone at the potential implant site. To address the limitations of the maxillary arch, attempts have been made during the last two decades to improve implant anchorage in this area. Bone grafting techniques and guided bone regeneration have been utilized to augment and improve the maxillary arch. The learning objective of this article is to review the important aspects related to the anatomy and physiology of the maxillary sinus, to discuss the use of various grafting materials, and to describe the technique and current status of the maxillary sinus augmentation procedures. Emphasis is placed upon presentation of the presurgical, surgical, and postsurgical protocol of maxillary sinus augmentation, as performed by the authors.

Maxillary sinus augmentation using different grafting materials and dental implants in monkeys. Part III. Evaluation of autogenous bone combined with porous hydroxyapatite.

The aim of this study was to evaluate clinically, histologically, and histometrically the use of autogenous bone combined with porous hydroxyapatite (Interpore 200) as a grafting material for maxillary sinus augmentation procedures. In 4 adult male rhesus monkeys (Macaca mulatta) the 1st, 2nd and 3rd maxillary molars on one side of the jaws were extracted. After a healing period of 3 months, maxillary sinus augmentation procedures were performed in each monkey, and the sinuses were grafted with autogenous bone from the monkeys' tibia mixed in a 3:1 ratio with porous hydroxyapatite. At the same time, 2 pure titanium plasma-sprayed IMZ cylinder implants were immediately placed into the augmented sinuses (i.e. simultaneous implants-loaded group). After 4 months, 2 additional similar implants were placed into the previously augmented sinuses (i.e. delayed implants-loaded group). Four months later, the abutment connection was performed and all 4 implants were loaded with a gold-alloy bridge for 6 months (i.e. until sacrifice of the animals). The contralateral side of each monkey received similar treatment with the exception that the extractions were performed 7 months after those in the opposite side and that the implants were not loaded. Thus, 2 additional study groups (i.e. simultaneous implants unloaded group and delayed implants unloaded group) were obtained. Clinically, all loaded implants were stable at the day of sacrifice. Histologically, the grafted sinuses exhibited a significant amount of new bone formation. The porous hydroxyapatite granules appeared integrated with the newly formed bone. Histometric analyses revealed that delayed implant placement resulted in a greater amount of direct mineralized bone-to-implant contact in the augmented area than the simultaneous implant placement. Furthermore, the percentage of direct mineralized bone-to-implant contact was far more significant in the residual bone than in the augmented area. It was concluded that the autogenous bone/porous hydroxyapatite graft combination enhanced bone formation and mineralized bone-to-implant contact in the augmented sinuses and that the delayed implant placement may be favorable for sinus augmentation procedures.

Maxillary sinus augmentation using different grafting materials and dental implants in monkeys. Part I. Evaluation of anorganic bovine-derived bone matrix.

The aim of this study was to evaluate clinically, histologically and histometrically the use of anorganic bovine bone matrix (i.e. Bio-oss) as a grafting material for maxillary sinus augmentation procedures. In 4 adult male rhesus monkeys (i.e. Macaca mulatta) the 1st, 2nd and 3rd maxillary molars on one side of the jaws were extracted. The remaining bone between the alveolar crest and the bottom of the sinus was then reduced to 3-4 mm. After 3 months, maxillary sinus augmentation procedures were performed on one side of the jaws in each monkey and the sinuses were grafted with the bovine bone matrix. At that time, 2 IMZ pure titanium plasma coated implants were immediately placed into the augmented sinuses (i.e. simultaneous implants-loaded group). After 4 months, 2 additional similar implants were placed into these previously augmented sinuses (i.e. delayed implants-loaded group). Four months later, the abutment connection was performed and all 4 implants were loaded with a gold-alloy bridge for 6 months (i.e. until sacrifice of the animals). The contralateral side of each monkey received the same treatment with the exception that the extractions were performed 7 months after those in the opposite side and that the implants in this side were not loaded. Thus, 2 additional study groups (i.e. simultaneous implants-unloaded group and delayed implants-unloaded group) were obtained. Clinically, all loaded implants were stable at the day of sacrifice. Histologically, the grafted sinuses exhibited significant bone formation with integration of the bovine bone matrix particles to the new bone. Direct mineralized bone-to-implant contact was greater for the delayed implant placement groups than for the implants installed simultaneously with the sinus augmentation. Furthermore, the percentage of direct mineralized bone-to-implant contact was greater in the residual bone than in the augmented area. It was concluded that the anorganic bovine bone matrix facilitated bone formation and implant osseointegration in the augmented sinuses and that the delayed implant placement in combination with the sinus augmentation procedure seemed to be preferable.

Maxillary sinus augmentation using different grafting materials and osseointegrated dental implants in monkeys. Part II. Evaluation of porous hydroxyapatite as a grafting material.

The aim of this study was to evaluate clinically, histologically and histometrically the use of porous hydroxyapatite (i.e. Interpore-200) as a bone grafting material for maxillary sinus augmentation procedures. In 4 adult male rhesus monkeys (i.e. Macaca mulatta) the 1st, 2nd and 3rd maxillary molars on one side of the jaws were extracted and the remaining bone between the alveolar crest and the bottom of the sinus was reduced to 3-4 mm. After 3 months, maxillary sinus augmentation procedures were performed on one side of the jaws in each monkey, and the sinuses grafted with the porous hydroxyapatite. Two IMZ titanium plasma-sprayed cylinder implants were then immediately placed into the augmented sinus (i.e. simultaneous implants-loaded group). After 4 months, 2 additional similar implants were placed into the previously augmented sinuses (i.e. delayed implants-loaded group). Four months later, the abutment connection was performed and all 4 implants were loaded with a gold-alloy bridge for 6 months (i.e. until sacrifice). The contralateral side of each monkey received the same treatment with the exception that the extractions were performed 7 months after those in the opposite side and that the implants in this side were not loaded. Thus, 2 additional study groups (i.e. simultaneous implants-unloaded group and delayed implants-unloaded group) were obtained. Clinically, all loaded implants were stable at the day of sacrifice. Histologic analysis demonstrated a significant amount of new bone formation in the augmented sinuses. Porous hydroxyapatite graft particles appeared to be integrated to the new bone. The percentage of direct mineralized bone-to-implant contact in the augmented area was greater on the delayed-placed implants than on the simultaneously-placed implants. Also, the percentage of direct mineralized bone-to-implant contact was greater in the residual bone than in the augmented area. It was concluded that this porous hydroxyapatite bone graft enhanced bone formation and bone-to-implant contact in the augmented sinuses and that the delayed implant placement in combination with the sinus augmentation procedure appears to result in a higher percentage of direct mineralized bone-to-implant contact.

Maxillary sinus augmentation using different grafting materials and dental implants in monkeys. Part IV. Evaluation of hydroxyapatite-coated implants.

The aim of this study was to evaluate clinically, histologically and histometrically the use of hydroxyapatite-coated dental implants in conjunction with maxillary sinus augmentation procedures. In 4 adult male Rhesus monkeys (Macaca mulatta) the 3 maxillary molars on 1 side of the jaws were extracted and the remaining bone between the alveolar crest and the floor of the sinus was reduced to 3-4 mm. After 3 months, maxillary sinus augmentation procedures were performed in each monkey and the sinuses were grafted with a porous hydroxyapatite bone graft (Interpore-200). At the same time, 2 hydroxyapatite-coated cylinder implants (IMZ) were immediately placed into the augmented sinuses (i.e. simultaneous-implants-loaded group). Four months later, 2 additional similar implants were placed into the previously augmented sinuses (i.e. delayed-implants-loaded group). After 4 months, the abutment connection was performed and all 4 implants were loaded with a gold-alloy bridge for 6 months (i.e. until sacrifice of the animals). The contralateral side of each monkey received the same treatment with the exception that removal of the maxillary molars was performed 7 months after those in the opposite side, and that the implants in this side were not loaded. Thus, 2 additional study groups (i.e. simultaneous-implants-unloaded group and delayed-implants-unloaded group) were obtained. Clinically, all loaded and unloaded implants were stable the day of sacrifice. Histologically, the grafted sinuses exhibited a significant amount of new bone formation with integration of the porous hydroxyapatite graft particles and hydroxyapatite-coat of the dental implants to the new bone. Histometric analysis indicated that on the loaded side the implants placed simultaneously with the sinus lift procedure exhibited greater direct mineralized bone-to-implant contact than the delayed placed implants. In addition, the percentage of direct mineralized bone-to-implant contact was significantly greater in the residual bone in comparison to the augmented area in all groups. Loading of the implants exhibited a positive effect on the percentage of direct mineralized bone-to-implant contact in the augmented area. It could be concluded that hydroxyapatite-coated implants may be of benefit when used in conjunction with sinus augmentation procedures.

Reconstruction of the severely resorbed maxilla with dental implants in the augmented maxillary sinus: a 5-year clinical investigation.

The aim of this investigation was to determine the long-term clinical outcome and predictability of the maxillary sinus augmentation procedure utilizing a variety of bone augmentation materials. The augmentation materials evaluated were a xenograft alone (Bio-Oss), an alloplast alone (Interpore), a xenograft-alloplast combination (Bio-Oss mixed with Interpore in a 1:1 ratio), an alloplast (Interpore) mixed with autogenous bone from the iliac crest (in a 1:3 ratio), and an alloplast (Interpore) mixed with autogenous bone from the chin (in a 1:1 ratio). A total of 340 plasma-sprayed cylinder implants (IMZ) were placed, either simultaneously with the sinus augmentation procedure (235 implants), or 6 months after the procedure (105 implants) in 133 patients with insufficient bone volume in the posterior maxilla. The implants were restored with a total of 151 fixed detachable ceramometal prostheses and evaluated up to a 5-year period. Clinical evaluations included yearly assessments of peri-implant inflammation, implant mobility, and clinical attachment levels. Radiographs were also taken prior to sinus augmentation surgery, at abutment connection, at completion of the restoration, and thereafter at yearly intervals. All of the implants placed into the augmented sinuses achieved osseointegration. Only four implants (1.2%) failed to maintain osseointegration after prosthesis placement, yielding an implant survival rate of 98.8% during the entire course of the study. Of the 340 implants, 307 (90.3%) were considered successful according to the success criteria used. Gender, implant length and location, remaining bone height, and type of bone augmentation material had no effect on implant success. None of the 151 prostheses was lost during the observation period. The results of this study support the long-term clinical predictability of maxillary sinus augmentation procedures for the rehabilitation of the edentulous posterior maxilla with implant-supported prostheses.

Guided periodontal tissue regeneration (GPTR): an update.

Periodontal therapy has three primary objectives--elimination of etiologic factors, repair or regeneration of the lost attachment apparatus, and prevention of further periodontal breakdown. Significant progress has occurred in the area of surgical periodontal therapy during the last two decades. Periodontal regeneration has become a viable treatment option utilizing the principles of guided tissue regeneration. The learning objective of this article is to review the biologic rationale, the various barrier materials currently available, and the surgical techniques for guided periodontal tissue regeneration procedures using nonresorbable and resorbable barriers, with and without bone grafting materials.

Influence of the suprastructure on the peri-implant tissues in beagle dogs.

The purpose of this study was to compare clinical, radiographic and histological differences around titanium oral implants loaded with either acrylic-veneered metal or ceramo-metal fixed prostheses. Five beagle dogs were used in this investigation. At the beginning of the study, all mandibular premolars and first molars were extracted. After 3 months of healing, 2 Brånemark implants were installed on each side of the mandibles. Three months later, abutments were inserted on each implant and a daily oral hygiene regime was initiated. One month after abutment connection, the implants on one side of the mandible were restored with an acrylic-veneered metal fixed prosthesis, whereas, on the other side a ceramo-metal fixed prosthesis was inserted. The prostheses were constructed in occlusion with the maxillary first molars. The following clinical parameters were measured around each implant at this time (i.e., baseline), and thereafter, at monthly intervals up to 5 months: Plaque Index; Gingival Index; implant mobility (using the Periotest); probing depth and clinical attachment level (using the Florida Probe). In addition, standardized radiographs were taken at baseline and 5 months after insertion of the prostheses and evaluated by subtraction radiography. Another Brånemark fixture was installed on each side of the mandibles 3 months before the end of the study. These implants remained unloaded and submerged for the entire study period. Five months after prosthesis insertion, the animals were killed, and implants with their supporting peri-implant tissues were processed for histological evaluation. Analyses of the clinical, radiographic and histometric parameters revealed no significant differences between the acrylic-veneered and ceramometal loaded implants.(ABSTRACT TRUNCATED AT 250 WORDS)