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The present study evaluated the effect of combining an enamel matrix derivative (EMD) and a bioresorbable membrane (GTR) in the surgical treatment of degree III mandibular furcation involvements. Nine patients with chronic periodontitis, presenting a total of 14 degree III mandibular furcation involvements, were included in the study. Surgical treatment of the defects was randomly assigned: (1) EMD (four defects); (2) GTR (three defects); and (3) EMD and GTR (seven defects). The degree of involvement was assessed prior to surgery and after 6 and 12 months by measuring the probing attachment level in the horizontal and vertical directions at the furcation site. At 6 and 12 months, partial closure of the involvements had occurred in approximately half of the treated furcations, and the vertical probing level consistently improved following all three treatment modalities. The results suggest that all three treatment modalities may improve healing following surgical treatment of degree III mandibular furcation involvements. However, further studies are needed to examine the clinical significance of these results and the histologic characteristics of the healing following application of EMD.

The purpose of the present study was to histologically evaluate the healing of human intrabony defects following treatment with either a bovine-derived xenograft (BDX) and guided tissue regeneration (GTR) [BDX + GTR] or a bovine-derived xenograft mixed with collagen (BDX Coll) and GTR [BDX Coll + GTR]. Eight patients with chronic periodontitis and each with one very deep intrabony defect around a tooth scheduled for extraction were treated with either a combination of BDX + GTR (five patients) or with BDX Coll + GTR (three patients). The postoperative healing was uneventful in all eight cases. After a healing period of 6 months, the teeth or roots were extracted together with some of their surrounding soft and hard tissues and subsequently fixed in 10% buffered formalin. Following decalcification in EDTA, the specimens were embedded in paraffin and 8-microm histological sections were cut in the mesio-distal direction, parallel to the long axes of the teeth. The sections were alternatively stained with hematoxylin and eosin, van Giesson's connective tissue stain or with the Ladevig's connective tissue staining method and examined under the light microscope. Generally, formation of new cementum with inserting collagen fibers was found in seven out of the eight treated cases, whereas in the remaining case (treated with BDX + GTR) the healing was characterized by formation of a long junctional epithelium along the debrided root surface and no formation of cementum or bone. In the specimens demonstrating periodontal regeneration the new cementum was always of a cellular type. In most cases, the graft particles were surrounded by bone. In some areas, the bone tissue around the graft particles was connected by perpendicularly inserting collagen fibers to the newly formed cementum on the root surface. The epithelium downgrowth stopped always at the most coronal part of the newly formed cementum. No remnants of the membrane material were observed in any of the biopsies. Connective tissue encapsulation of the graft particles was rarely observed and was limited to the most coronal part of the defects. The findings of the present study provide evidence that treatment of intrabony defects with both BDX + GTR and BDX Coll + GTR may enhance periodontal regeneration in humans.

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.

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.

Background: The use of enamel matrix proteins (EMD) has been recently introduced as a new treatment alternative for periodontal regeneration. However, no histological studies are available investigating the effect of EMD in the treatment of degree III furcation involvements., Objectives: The aim of this study was to evaluate the healing of mandibular degree III furcation involvements histologically following treatment with guided tissue regeneration (GTR), EMD and a combination of EMD and GTR., Material and Methods: Degree III furcation involvements were surgically created at the teeth 36, 37, 46, 47 in three monkeys (Macaca fascicularis). Spontaneous healing of the defects was prevented by placing impression material into the defects. After 6 weeks, full-thickness flaps were elevated at the buccal and lingual aspect of the experimental teeth. Following removal of all granulation tissue from the furcation defects, scaling/root planing and conditioning of the root surfaces with 24% EDTA gel, the defects were treated with one of the following treatment modalities: (i) EMD, (ii) GTR or (iii) a combination of EMD and GTR. The defects serving as control did not receive any treatment, except from complete coverage with coronally displaced flaps. After 5 months of healing, the animals were killed and perfused with 10% buffered formalin for fixation. The experimental teeth with surrounding tissues were dissected free, decalcified in EDTA, dehydrated and embedded in paraffin. 8 microm thick histological sections were cut and stained and subsequently examined under the light microscope., Results: The histological analysis revealed that with GTR or combined EMD and GTR treatment, new attachment formation (new cementum with inserting collagen fibers) had occurred on almost the entire circumference of the furcation and new bone was almost filling the defect in the situations where the membrane was not exposed. The sites treated only with EMD exhibited new attachment and new bone formation to a varying extent, while the control sites presented only limited new attachment and bone formation., Conclusion: The results provided histological evidence suggesting that both GTR and EMD may result in true periodontal regeneration, and suggest that this type of healing might be favored by such treatments in comparison with flap surgery.

Aim: To examine in a discriminating capsule model whether denaturation of demineralized bone matrix (DBM) by heating may influence bone formation., Materials and Methods: DBM was produced from the long bones of rats. Half the portion of DBM was denatured by heating in distilled water for 20 min at temperatures between 70 degrees C and 90 degrees C. Prior to the study, the destruction of the osteoinductive properties of the DBM was confirmed in three rats following intramuscular implantation. Thirty, 4-month-old, male albino rats of the Wistar strain were used in the study. Following surgical exposure of the mandibular ramus, a hemispherical Teflon capsule (internal diameter = 5.0 mm) was placed, with its open part facing the lateral aspect of the ramus. On one side (test side), the capsule was loosely packed with denatured DBM, while on the contralateral side, serving as control, the capsule was loosely packed with the same amount of non-denatured DBM. After healing periods of 30, 60, and 120 days, groups of 10 animals were killed and 40-70 microm thick undecalcified sections of the capsules were produced. Three sections from each specimen, representing the mid-portion of the capsule, were subjected to histological analysis and computer-assisted planimetric measurements., Results: Increasing amounts of newly formed bone were observed in both test and control capsules during the experimental period. At 4 months, the new bone formed in the control capsules occupied 46.7% of the cross-sectional area of the capsules, while it was only 19.1% in the test capsules (P<0.05)., Conclusion: Denaturation of DBM by heating significantly reduces bone formation by guided tissue regeneration.

Aim: To evaluate whether bone formation by guided tissue regeneration (GTR) and demineralized bone matrix (DBM) can be enhanced by the use of a cell-permeable Teflon barrier allowing the penetration of undifferentiated mesenchymal cells from the surrounding soft tissues., Material and Methods: DBM was produced from the long bones of rats, and its bone-inductive properties were tested in three rats prior to the study by intramuscular implantation. Thirty, 4-month-old, male albino rats of the Wistar strain were used. Following surgical exposure of the mandibular ramus, a cell-permeable Teflon capsule, loosely packed with DBM, was placed with its opening facing the lateral surface of the ramus (test side). At the contralateral side, serving as control, a non-perforated (cell-occlusive) Teflon capsule, loosely packed with the same amount of DBM, was placed. After healing periods of 30, 60, and 120 days, groups of 10 animals were killed, and 40-70 microm thick undecalcified sections of the capsules were produced., Results: Computer-assisted planimetric measurements on the histological sections disclosed similar amounts of newly formed bone in both test and control capsules. After 4 months, the new bone in the control capsules occupied 45.0% of the cross-sectional area of the capsule, while it was 50.5% in the test capsules. This difference was not statistically significant (P<0.05)., Conclusion: Similar amounts of bone formed in cell-permeable and cell-occlusive capsules grafted with DBM, suggesting that invasion of undifferentiated mesenchymal cells from the surrounding soft tissues into the barrier-protected area is unnecessary for bone formation with GTR.

The aim of the present study was to evaluate the clinical outcome following application of an enamel matrix derivative in degree II mandibular furcation involvements. Ten patients with chronic periodontitis, presenting a total of eight buccal and eight lingual degree II furcation involvements, were included in the study. The following clinical parameters were evaluated prior to treatment and after 6, 12, and 36 months: probing attachment level in horizontal direction in the buccal and/or lingual furcation area (PAL-H) and probing attachment level in vertical direction (PAL-V) at the center of the buccal/lingual furcation area. The postoperative healing phase was uneventful in all cases, and no complications were observed throughout the entire study period. At 6 months, the mean PAL-H of the buccal defects was reduced from 4.0 +/- 1.3 mm to 2.6 +/- 1.4 mm, and the mean PAL-V was reduced from 5.2 +/- 2.0 mm to 4.0 +/- 1.6 mm. At the lingual defects, the mean PAL-H was reduced from 3.6 +/- 1.3 mm to 3.1 +/- 1.1 mm, and the mean PAL-V was reduced from 5.6 +/- 2.0 mm to 4.3 +/- 1.8 mm. At 12 and 36 months, clinical parameters remained similar, without any further clinical improvement. These results suggest that the treatment of degree II mandibular furcation involvements with enamel matrix derivative might lead to clinical improvement. However, controlled clinical trials and histologic studies are needed to examine the clinical significance of these results and the characteristics of healing following application of enamel matrix derivative.

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.

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.

Objectives: To evaluate whether Bio-Oss used as an adjunct to guided tissue regeneration (GTR) improves the healing of 1- or 2-wall intrabony defects as compared with GTR alone, and to examine whether impregnation of Bio-Oss with gentamicin may have an added effect., Material and Methods: Sixty patients, with at least one interproximal intrabony defect with probing pocket depth (PPD) > or =7 mm and radiographic evidence of an intrabony component (IC) > or =4 mm, were treated at random with either a resorbable membrane (GTR), a resorbable membrane in combination with Bio-Oss impregnated with saline (DBB-), a resorbable membrane in combination with Bio-Oss impregnated with gentamicin (DBB+), or with flap surgery (RBF)., Results: All treatment modalities resulted in statistically significant clinical improvements after 1 year. Defects treated with GTR alone presented a probing attachment level (PAL) gain of 2.9 mm, a residual PPD (PPD12) of 4.9 mm, a radiographic bone level (RBL) gain of 3.1 mm, and a residual IC (IC12) of 2.7 mm. GTR combined with Bio-Oss did not improve the healing outcome (PAL gain: 2.5 mm; PPD12: 4.9 mm; RBL gain: 2.8 mm; IC12: 3.3 mm). Impregnation of the Bio-Oss with gentamicin 2% mg/ml resulted in clinical improvements (PAL gain: 3.8 mm; PPD12: 4.2 mm; RBL gain: 4.7 mm; IC12: 2.1 mm), superior to those of the other treatment modalities, but the difference was not statistically significant. Defects treated with only flap surgery showed the most inferior clinical response (PAL gain: 1.5 mm; PPD12: 5.1 mm; RBL gain: 1.2 mm; IC12: 4.2 mm) of all groups., Conclusion: The results failed to demonstrate an added effect of Bio-Oss implantation in combination with GTR on the healing of deep interproximal 1- or 2-wall, or combined 1- and 2-wall intrabony defects compared with GTR alone. Local application of gentamicin, on the other hand, improved the treatment outcome but not to an extent that it was statistically significant.

Objectives: To evaluate in a discriminating "capsule" model whether local application of gentamicin may have an added effect on bone formation produced by Bio-Oss and guide tissue regeneration (GTR)., Material and Methods: Thirty male 3-month-old Wistar rats were used. After elevation of muscle-periosteal flaps, a rigid hemispherical Teflon capsule, loosely packed with 0.025 g of Bio-Oss impregnated with 2 mg/ml gentamicin sulfate (Garamycin), was placed with its open part facing the lateral bone surface of the mandibular ramus (test) in one side of the jaw. A capsule filled only with Bio-Oss (control) was placed on the contralateral side of the jaw. After healing periods of 1, 2 and 4 months, groups of 10 animals were sacrificed and the specimens were processed for histological examination. The volumes of (1) the space created by the capsule, (2) newly formed bone, (3) Bio-Oss particles, (4) loose connective tissue, and (5) acellular space in the capsule were estimated by a point-counting technique in three to four histological sections of each specimen, taken by uniformly random sampling., Results: The histological evaluation showed limited but increasing bone fill in the capsules from 1 to 4 months in both the test and control sides. After 4 months, the newly formed bone occupied 11.9% (CV: 0.39) of the space created by the capsules at the test sides versus 13.2% (CV: 0.41) at the control sides. There was no statistical significant difference between test and control specimens at any observation time (p>0.05)., Conclusion: It is concluded that local application of gentamicin has no added effect on bone formation when combined with Bio-Oss and GTR.

Aim: To evaluate in a discriminating capsule model whether bone formation by guided tissue regeneration (GTR) may be influenced by concomitant implantation of demineralized bone matrix (DBM)., Materials and Methods: Thirty 4-month-old male albino rats of the Wistar strain were used in the study. Following surgical exposure of the mandibular ramus, a hemispherical, Teflon capsule (5.0 mm in diameter), loosely packed with a standardized amount of DBM, was placed with its open part facing the lateral bone surface of the ramus. At the contralateral side, an empty capsule was placed, serving as control. After healing periods of 15, 30, and 120 days, groups of 10 animals were sacrificed and 40-70 microm thick undecalcified sections of the capsules were produced. In the sections, the cross-sectional areas of (1) the space created by the capsule, (2) newly formed bone, (3) DBM particles, (4) loose connective tissue as well as the (5) height of the capsules, and (6) that of the newly formed bone were measured., Results: Increasing bone fill was observed in both test and control sites from 30 to 120 days. After 30 days of healing, the mean amount of bone was approx. 3% of the cross-sectional area of the capsules at the test sites while it was 8% in the control sites (p<0.05). However, no statistically significant differences were observed between the test (46%) and control (64%) sites after 120 days regarding any of the measured parameters (p>0.05). The newly formed bone in the DBM group at 120 days, on the other hand, appeared more dense than that in the control capsules., Conclusion: DBM used as an adjunct to GTR did not provide any added effect on bone formation but increased the density of the newly formed bone.

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.

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.

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.

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.

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.

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.

It has been reported that local application of bone grafts or synthetic bone substitutes (filler materials) may favour bone formation when used in combination with guided tissue regeneration (GTR). Therefore, the aim of the present investigation was to evaluate the effect of application of chitin beads (a bioabsorbable natural polymer) as a bone substitute in bone formation by GTR. The experiment was carried out in 25 rats. The mandibular ramus was exposed on one side after elevation of a muscle-periosteal flap, and a teflon capsule filled with chitin beads (2.0 mm in diameter) was placed with its opening facing the lateral aspect of the ramus. On the contralateral side of the jaw, serving as control, an empty teflon capsule was placed in the same manner. Groups of 5 animals were sacrificed at 7, 15, 30, 60 and 120 days following capsule placement. Histological analysis demonstrated that the amount of newly formed bone was similar in both experimental and control specimens, amounting to approximately 3% of the central/largest, cross-sectional area created by the capsule at 15 days, and to approximately 9% of this area at 30 days following capsule placement. At 60 and 120 days, however, the amount of newly formed bone observed in the control specimens was twice as large as that observed in the test specimens, amounting to approximately 31% of the cross-sectional area created by the capsule at 60 days, and to approximately 45% at 120 days. It is concluded that, although chitin beads (2.0 mm in diameter) are biocompatible, their presence retards bone formation in the model system used.

Background: Promising results have been reported following treatment of periodontal and peri-implant bone defects with deproteinized bovine bone grafts, but their influence on bone formation has not been clarified., Purpose: The goal of this study was to examine whether implantation of deproteinized bovine bone (Bio-Oss, Geistlich AG, Wolhusen, Switzerland) influences bone formation when used as an adjunct to guided bone augmentation (GBA)., Materials and Methods: A rigid, hemispherical, Teflon capsule was loosely packed with a standardized quantity of Bio-Oss and placed with its open part facing the lateral surface of the mandibular ramus (test) in 30 rats. At the contralateral side of the jaw, an empty capsule was placed (control). Groups of 10 animals were sacrificed after 1, 2, and 4 months. The volumes of the space created by the capsule and of the (1) newly formed bone, (2) remaining Bio-Oss particles, (3) soft connective tissue, and (4) acellular space in the capsule were estimated by a point-counting technique in three or four histologic sections, taken by uniformly random sampling., Results: Bone formation at 1 month was limited in both tests and controls. After 2 months, the mean volume of the newly formed bone occupied 9.0% of the space created by the capsule in the test specimens compared with 23.8% in the control specimens (p < .01). After 4 months, the respective figures were 11.6% (tests) versus 38.7% (controls) (p < .01)., Conclusion: It can be concluded that Bio-Oss, used as an adjunct to GBA, interferes with bone formation.

Regenerative periodontal therapy comprises procedures which are specially designed to restore parts of the tooth supporting apparatus which have been lost due to periodontitis. A procedure must fulfill certain criteria to be considered a therapy which encourages regeneration. This paper discusses a variety of surgical approaches including root surface conditioning, the placement of bone garfts or bone substitute implants and the use of organic or synthetic barrier membranes (GTR). Evidence is presented that regenerative surgery utilising the GTR principle fulfills all the criteria required of a surgical procedure to be considered a procedure leading to periodontal regeneration.

Background: Enamel matrix proteins (EMD) have recently been introduced in regenerative periodontal treatment. However, no histological data are yet available concerning the effect of treating intrabony periodontal defects with EMD, and no histological comparisons have been made comparing the result of treatment of intrabony defects with EMD with that of the treatment with guided tissue regeneration (GTR)., Aim: Therefore, the aim of the present study was to evaluate histologically in monkeys the effect of treating intrabony defects with EMD, GTR or combined EMD and GTR., Method: Intrabony periodontal defects were produced surgically at the distal aspect of teeth 14, 11, 21, 24, 34, 31, 41 and 44 in 3 monkeys (Macaca fascicularis). In order to prevent spontaneous healing and to enhance plaque accumulation metal strips were placed into the defects. After 6 weeks the defects were exposed using a full-thickness flap procedure. The granulation tissue was removed and the root surfaces were debrided by means of hand instruments. Subsequently, the defects were treated using one of the following therapies: (i) GTR, (ii) EMD, or (iii) combination of EMD and GTR. The control defects were treated with coronally repositioned flaps. After 5 months, the animals were sacrificed and perfused with 10% buffered formalin for fixation. Specimens containing the defects and surrounding tissues were dissected free, decalcified in EDTA and embedded in paraffin. 8 microm thick histological sections were cut and stained and subsequently examined under the light microscope., Results: In the control specimens, the healing was characterized by a long junctional epithelium and limited periodontal regeneration (i.e., new periodontal ligament, new cementum with inserting connective tissue fibers and new bone) in the bottom of the defect. The GTR-treated defects consistently presented periodontal regeneration when the membranes were not exposed whereas the sites treated only with EMD presented regeneration to a varying extent. The combined therapy did not seem to improve the results., Conclusion: It can be concluded that all 3 treatment modalities favor periodontal regeneration.

The effect of topical application of a metronidazole gel (ELYZOL DENTAL GEL), and adjunctive therapy in the treatment of adult periodontitis was assessed clinically. A single, masked examiner performed clinical assessments. Fourteen patients were involved, each one received four different treatments including control, and the four treatments were randomly applied to at least one tooth in each quadrant for each patient in a comparative split-mouth design. Clinical examinations were carried out before treatment and 90 days after treatment. All patients had at least one tooth in each quadrant with probing pocket depth of > or = 5mm. The four treatment groups were: (I) One session of one hour of scaling and root planning, (II) metronidazole 25% dental gel (ELYZOL DENTAL GEL) applied on day 0 and day 7, (III) scaling adjunctive to metronidazole 25%, and (IV) No treatment. Instruction in oral hygiene was given to all subjects at base line examination. At the end of the study (day 90), all groups had statistically significant improvement in probing pocket depth (P < 0.02), and in plaque and bleeding indices (P < 0.05) when compared to day 0. However, group III had statistically significantly greater improvement (P < 0.03) in probing pocket depth than groups I, II and IV. Both groups I and II had statistically significantly greater improvement (P < 0.05) in probing pocket depth than control group. On the other hand, both groups were not statistically significantly different from each other in probing pocket depth improvement. It is suggested that topical Elyzol treatment may improve periodontal health as well as subgingival scaling and root planning therapy, and adjunctive treatment could obtain an additional therapeutic effect.

The aim of the present study was to evaluate histologically in monkeys the healing in acute fenestration-type defects following treatment with guided tissue regeneration (GTR) or enamel matrix proteins (EMD). Standardized "critical size" fenestration-type defects were produced surgically at the vestibular aspect of teeth 13, 23, 33, 43 in three monkeys (Macaca fascicularis). The vestibular bone plates were removed and the root surfaces were debrided by means of hand instruments in order to completely remove the root cementum. Following root conditioning with ethylenediaminetetraacetate (EDTA), the defects were treated using one of the following therapies: (1) GTR, (2) EMD, or (3) control (coronally repositioned flaps). After 5 months the animals were killed and perfused with 10% buffered formalin for fixation. Specimens containing the defects and surrounding tissues were dissected free, decalcified in EDTA, and embedded in paraffin. Eight-micrometer-thick step serial histological sections were cut in a vestibulo-oral direction, stained with hematoxylin and eosin or oxone-aldehyde-fuchsin-Halmi, and subsequently examined under the light microscope. The results showed that, in the defects treated with GTR, a new connective tissue attachment (i.e., new cementum with inserting collagen fibers) and new bone formation had consistently occurred, whereas, in the defects treated with EMD or with coronally repositioned flaps, new attachment and new bone reformed to a varying extent. The quality of the cementum did not differ after EMD, GTR, or flap surgery. It was concluded that GTR treatment with bioresorbable membranes seems to predictably promote new attachment and new bone formation, whereas the application of EDTA or EMD may also enhance periodontal healing to a certain extent. Further studies with higher numbers of animals and defects are needed in order to definitely clarify the effect of root surface conditioning with EDTA and EMD on periodontal healing.

The aim of the present study was to evaluate whether bone tuberosities produced by GTR on the lateral surface of the mandibular ramus in rats are stable on a long-term basis. Thirty male 6-month-old albino rats of the Wistar strain were used in the study. Tissue flaps were elevated on the lateral aspect of the mandibular ramus. The periosteum was preserved (P+) on one side of the jaw while the bone was denuded (P-) on the other. A rigid, non-porous oval-shaped teflon capsule was placed on both sides with its opening facing the ramus. Six months following surgery, 10 rats were sacrificed and prepared for histology while the remaining 20 rats were subjected to a second operation during which the capsules were removed. Standardized radiographs, taken immediately before and after removal of the capsule and after 3, 6, 9 and 12 months, were subjected to planimetric measurements and subtraction radiography. Ten animals were sacrificed and prepared for histological analysis after 6 months following removal of the capsules and the remaining 10 animals after 12 months. Histology revealed that at 6 months after the placement of the capsules, 17 were completely filled with new bone. The remaining 3 capsules which were displaced exhibited only partial bone fill. The radiographic analysis revealed that after 6 months 98.6 +/- 7.6% (mean +/- SD) in average of the cross-sectional area created by the capsules was filled with new bone. Within 3 months after removal of the capsules a slight resorption of the new bone had occurred, thereby reducing the area of the bone tuberosities by 4 to 8%. No further resorption of the bone tuberosities took place from 3 to 12 months. These observations indicating that new bone produced by GTR is stable on a long-term basis, may question the general belief that non-functional bone will resorb over time.

The aim of the present study was to evaluate histologically in humans the healing of advanced intrabony defects following treatment with enamel matrix proteins (EMD) or guided tissue regeneration (GTR). Fourteen patients, each of them displaying 1 advanced intrabony defect around teeth scheduled for extraction were included in the study. The defects were treated randomly either with an enamel matrix protein derivative (Emdogain, BIORA AB, Malmö, Sweden) or with a bioabsorbable membrane (Resolut, Regenerative Material, W.L. Gore & Assoc., Flagstaff, Arizona, USA). At baseline the mean probing pocket depth (PPD) in the EMD group was 11.3 +/- 1.8 mm and the mean clinical attachment level (CAL) 12.1 +/- 2.0 mm, whereas in the GTR group the mean PPD was 11.4 +/- 2.2 mm and the mean CAL 13.3 +/- 2.3 mm. Healing was uneventful in all cases. Neither allergic reactions against EMD or the bioabsorbable membrane, nor suppuration or abscesses were observed. The clinical results revealed at 6 months in the EMD group a mean PPD of 5.6 +/- 1.3 mm and a mean CAL of 9.1 +/- 1.5 mm. In the GTR group the mean PPD was 5.6 +/- 1.3 mm and the mean CAL 10.1 +/- 1.5 mm. The histological analysis showed in the EMD group a mean 2.6 +/- 1.0 mm of new attachment (i.e. new cementum with inserting collagen fibers) and a mean 0.9 +/- 1.0 mm of new bone. In this group, the formation of new attachment was not always followed by bone regeneration. In the GTR group, the mean new attachment was 2.4 +/- 1.0 mm and the mean new bone 2.1 +/- 1.0 mm. In every case treated with GTR, the formation of new attachment was followed by a varying amount of new bone. After both types of regenerative treatment the newly formed cementum displayed a predominantly cellular character. The findings of the present study indicate that the treatment of intrabony defects with enamel matrix proteins or with bioabsorbable membranes enhances the formation of a new connective tissue attachment in humans.

The aim of the present study was to investigate whether oxytalan fibers are formed in the regenerated human periodontal ligament. 6 patients, each of them exhibiting an advanced intrabony defect, were treated with a bioresorbable membrane according to the GTR-principle. Following a healing period of 6 months, the teeth were extracted together with their surrounding soft and hard tissues and subsequently fixed in 10% buffered formalin. Following decalcification in EDTA, the specimens were embedded in paraffin and 8-microm histological sections were cut in the mesio-distal direction, parallel to the long axes of the teeth. The sections were stained with hematoxylin and eosin, or with the oxone-aldehyde-fuchsin-Halmi staining method and examined in the light microscope. A regenerated periodontal ligament containing newly-formed oxytalan fibers was observed in all specimens. Many of them inserted into the newly formed cementum on the root surface. It is concluded that oxytalan fibers are formed de novo in human regenerated periodontal ligament tissue.

The aim of the present study was to investigate in monkeys the regrowth of oxytalan fibres in different types of acute and chronic periodontal defects following regenerative periodontal treatment. One-wall intrabony and mandibular furcation III-defects were produced surgically in 3 monkeys (Macaca fascicularis). After a 6-wk dental plaque accumulation period the defects were exposed using a full thickness flap procedure. The granulation tissue was removed and the root surfaces were scaled and planed. Additionally, fenestration-type defects were produced at the vestibular surfaces of the maxillary and mandibular canines by surgically removing the vestibular bone plates and the root cementum. Subsequently, the defects were treated with guided tissue regeneration (GTR), enamel matrix proteins (EMP), combination of EMP and GTR or with coronally repositioned flaps. The postoperative care included tooth cleaning once a week during the experiment. After 5 months the animals were sacrificed and and the block sections were embedded in paraffin. Eight microns histological sections were cut and stained with the oxone-aldehyde-fuchsin-Halmi method. The results revealed that in all specimens where a regenerated periodontal ligament could be observed newly formed oxytalan fibers were present. They had a mainly apico-occlusal orientation and were localized closer to the cementum than to the alveolar bone. The regenerated oxytalan fibers had a similar morphological appearance than those observed in the original periodontal ligament regardless of the treatment modality by which regeneration was accomplished. Their presence was related to that of newly formed cementum suggesting a strong relationship between these 2 tissues. The neoformation of oxytalan fibres can thus be observed in some types of periodontal defects where the cementum and the periodontal ligament have been regenerated.

The aim of the present experiment was to test the effect of a deproteinized bovine bone mineral (Bio-Oss) on guided bone regeneration (GBR) in dehiscence defects around implants. The first 2 molars and all premolars were extracted on both sides of the mandibles of 3 monkeys (Macaca fascicularis). Three months later, 2 titanium plasma-coated cylindrical implants were placed in all quadrants of each monkey. During the surgical procedure, standardized dehiscence defects were produced buccally and lingually, measuring 2.5 mm in width and 3 mm in height. Four different experimental situations were created: 2 sites in each monkey were covered with an ePTFE membrane (M), 2 were filled with the graft material (DBBM), 2 were filled with the graft material and also covered with a membrane (M + DBBM), and 2 control sites were neither grafted nor covered (C). The flaps were sutured to allow for primary healing. Linear measurements of bone height and width were calculated on histological specimens obtained 6 months following surgery. In addition, values for bone density and for surface fraction of graft to new bone contact were measured. Vertical bone growth along the implant surface of 100% (SD 0%) for M + DBBM, 91% (SD 9%) for M, 52% (SD 24%) for DBBM, and 42% (SD 35%) for C was measured. The width of the regenerated bone 1.5 mm above the bottom of the original defect, i.e. at the 50% mark of the vertical extension of the defect, in relation to the width at the bottom of the defect amounted to 97% (SD 2%) for M + DBBM, 85% (SD 9%) for M, 42% (SD 41%) for DBBM, and 23% (SD 31%) for C. Assessment of bone density within the confinement of the regenerated bone resulted in an increase of 30% (SD 11%) for M + DBBM, 45% (SD 20%) for M, 33% (SD 20%) for DBBM, and 22% (SD 23%) for C. The values for graft to new bone contact within this compartment amounted to 80% (SD 15%) for M + DBBM and 89% (SD 14%) for DBBM. In conclusion, Bio-Oss exhibited osteoconductive properties and hence can be recommended for GBR procedures in dehiscence defects with respect to vertical and horizontal growth of bone.

Although a number of studies have described the oxytalan fibers as being a natural component of the periodontal ligament, little information exists about the regenerative potential of these connective tissue fibers. The aim of the present study was to examine whether oxytalan fibers have the capacity to reform after regenerative periodontal therapy. Intrabony defects were produced surgically at the mesial aspects of teeth 37, 35, 45, 47 and at the distal aspects of teeth 11, 21, 31, 41 in one monkey (Macaca fascicularis). After 3 months, the defects were exposed using a full-thickness flap procedure. The root surfaces were debrided and subsequently PDGF-growth factors were placed in the defects. 4 of the 8 sites were covered with a bioresorbable membrane before closure of the wound. Post-surgically, antibiotics were given systemically for 1 week, and tooth cleaning was carried out 1x a week during the entire experimental period. After 5 months, the animal was sacrificed and the oral tissues were fixed by perfusion with 10% buffered formalin. Specimens containing the defects and surrounding tissues were dissected free and histological sections were cut in the mesio-distal direction, parallel to the long axes of the teeth. The sections were stained with hematoxylin and eosin or with the oxone-aldehyde-fuchsin-Halmi staining method and subsequently examined in the light and in the electron microscope. The results revealed that new oxytalan fibers oriented mainly in an apico-occlusal direction had developed in the regenerated periodontal ligament. Many of the newly-formed fibers were inserted into the new cementum, thus suggesting a strong relationship between this tissue and the oxytalan fibers. It is concluded that the regenerated periodontal ligament connective tissue formed after surgery contains oxytalan fibers similar to those present in the original tissue. These results demonstrate that oxytalan fibers develop de novo in the newly-formed periodontal ligament.

The present study evaluate the outcome of implant therapy in periodontally compromised patients in need of additional functional tooth support. A total of 31 Astra implants and 93 ITI Dental Implant System implants were inserted in 19 and 56 patients, respectively. The length of the implants varied between 8 and 14 mm, with 45% being 8 mm and 21% being 11 mm or more. Most implants were placed in the maxilla, predominantly in the premolar region, while less than 25% were placed in the mandible. The observation period ranged between 12 and 40 months for Astra implants and between 3 and 84 months for ITI implants. At annual recall visits, 4 sites on all implants were assessed for presence of plaque, bleeding on probing, probing depth, and radiographic assessment of bone loss was performed. A total of 3 implants, all ITI implants, failed, yielding a 3-year survival rate of 95-100%, depending on type of implant. After 3 years, 76-86% of all implants remained free from radiographic bone loss > or = 1.5 mm. After 5 years, 55% of the ITI implants remained free from such bone loss. These results indicate that periodontally compromised patients, who have experienced a considerable loss of alveolar bony support, can be successfully treated with implants.

The present study compared recording reproducibility and image homogeneity after applying two techniques for recording of serial intra-oral radiographs: 1) a technique previously described in 1990 based on mechanical fixation between the patient, the film holder, and the x-ray tube; and 2) a newly developed technique which operates with an optical alignment provided by a light beam. Twenty adults participated in the study. Two intra-oral radiographs were taken with a 30-minute time interval of the mandibular premolar/molar and the incisor region in each individual with either of the methods. All radiographs were scanned and digitized. Subtractions were performed between the two radiographs taken of the same individual and region with the same method. The standard deviation (SD) of the histogram defining the distribution of the grey shades in the subtraction image was used as the statistical test parameter. Subtractions were performed with an automated method and using a reference point-based program in order to test recording reproducibility and image homogeneity, respectively. Paired t-tests revealed that the average SDs obtained by the mechanical fixation method and the optical method were not statistically significantly different neither when applying the automated nor the reference point-based subtraction method (P > 0.05). The SDs increased significantly when the automated method was used compared to the reference point-based method (P = 0.001). In conclusion, the optical method and the mechanical method provided images of similar recording reproducibility and homogeneity.

The aim of this study was to develop an experimental model in rats of an osseous submucous cleft palate and to examine if bone regeneration can be achieved in such defects by the placement of membranes according to the principle of guided tissue regeneration (GTR). An osseous submucous cleft palate defect (5 mm x 2 mm) was created surgically in Wistar rats. Membranes of expanded polytetrafluoroethylene were placed so that they covered both the nasal and the palatal aspect of the defect before the palatal mucoperiosteal flap was repositioned and sutured. Histological analysis after seven weeks of healing showed that significantly more test animals (5/9) healed with newly formed bone and a suture-like tissue in the middle of the defects than controls treated without membranes (0/17). In specimens evaluated macroscopically after 12 weeks, the corresponding rates for the test group were 12/12 compared with 0/13. These observations indicate that an experimental model of an osseous submucous cleft palate can be established in rats, and that complete osseous healing and creation of a midpalatal suture-like tissue in the bony defect is favoured by the placement of membranes according to the principle of GTR.

The effect of periodontal healing after guided tissue regeneration (GTR) in association with local application of metronidazole gel was evaluated in this study. Twelve patients with one pair of vertical periodontal bone defects of comparable size and configuration participated in the study. In a matched paired design, the test defects were treated by GTR using expanded polytetrafluoroethylene (ePTFE) membranes in combination with local application of metronidazole gel. The controls were treated in the same way except for application of metronidazole. During the first month of membrane implantation, no statistically significant differences between test and control surfaces were noted with respect to inflammation of the marginal gingiva. Six weeks following insertion, the membranes were removed. Six months after removal of the membrane, the median gain in probing attachment level as a percentage of the initial defect depth was 92% for test defects and 50% for control defects (P = .001). No statistically significant differences were found between test and control sites regarding plaque, bleeding on probing, reduction in pocket depth, gain in bone height, or recession of the gingival margin. In conclusion, the results of the present study indicate that local application of metronidazole gel has a beneficial effect on healing of periodontal vertical defects treated by guided tissue regeneration.

The aim of this study was to determine if a periodontal ligament can form around self-tapping, screw type titanium dental implants. Implants were inserted in contact with the periodontal ligament of root tips retained in the mandibular jaws of 7 monkeys. In each side of the mandible, 1 premolar and 2 molars were removed in such a manner that in approximately half the cases, the root tips were retained. Following healing, the experimental areas were examined on radiographs, and sites were selected for the insertion of the implants, so that every second implant would have a close contact to the retained root tips. Three months after placement of the implants, the animals were sacrificed, and ground sections were produced for histological analysis. The results demonstrated that newly-formed cementum had become deposited on the implant surface in the contact area between the implant and the retained roots, whereas osseointegration was consistently found on the remaining part of the implant surface as well as on the entire surface of the implants placed without contact to the retained root tips. The study has shown that, when placed in contact with periodontal ligament tissue of retained roots, a periodontal ligament can form on self-tapping, screw type titanium dental implants in areas where a void is present between the surrounding bone and the implant at the time of insertion.

This report presents the findings from an open randomized multicentre clinical trial designed to compare the clinical efficacy of scaling with application of 3 different preparations/dose frequencies of topical metronidazole in the treatment of adult periodontitis. The 4 treatments were: (A) metronidazole 25% dental gel administered 1 x a week for 2 weeks; (B) metronidazole 15% dental gel applied 1 x a week for 2 weeks; (C) metronidazole 15% dental gel applied 2 x a week for 2 weeks; (D) subgingival scaling, performed 1 x only. A split mouth design was used. Patients were included in the study if they had at least 1 tooth in each quadrant with a pocket depth > or = 5 mm in at least 1 of 4 sites. A total of 61 patients from 4 centres were entered into the study. The efficacy parameters were probing pocket depth and bleeding on probing. Follow-up visits for recording of clinical efficacy were made at 2, 4, 6 and 12 weeks after the end of metronidazole treatment. All 3 antibiotic treatments (A, B, C) reduced the symptoms of periodontal pathology and yielded results comparable to those seen after subgingival scaling (D). When using a topical drug therapy, it seems important to use a preparation that requires as few applications as possible. The best candidate for drug therapy would therefore be treatment (A) metronidazole 25% applied 1 x a week for 2 weeks.

The purpose of the present investigation was to evaluate the use of biodegradable membranes of polylactic acid or polyurethane for obtaining regeneration following treatment of circumferential periodontal defects in monkeys with the "guided tissue regeneration" procedure. Orthodontic elastic bands were placed around selected test and control teeth in 4 monkeys in order to induce breakdown of the periodontal tissues. When the destruction of the supporting tissues had progressed to a level corresponding to approximately half the length of the roots, the elastic bands were removed. After 1 to 8 months, full thickness flaps were raised on the buccal and lingual aspects of both test and control teeth. The exposed root surfaces were scaled and a notch was prepared in the root surface at the level of the reduced bone crest. Membranes of polylactic acid or polyurethane were placed circumferentially around the test teeth, while no membranes were placed around the control teeth. The tissue flaps were then sutured in a coronally displaced position. The surgical procedures and sacrifice of the animals were scheduled to provide observation times of 1, 4 and 8 months. During the healing period, various complications such as recession of the flap margins and exposure or exfoliation of the membranes were noticed. The histological analysis showed that the amount of new connective tissue attachment on test and control teeth did not differ and was restricted to the most apical part of the lesions. The bio-degradable membranes could be identified in a few specimens, and they were always surrounded by an epithelial layer.(ABSTRACT TRUNCATED AT 250 WORDS)

The purpose of the present investigation was to evaluate the use of bone grafts in combination with the GTR-procedure in reinstituting periodontal support around teeth with horizontal bone loss. Orthodontic elastic bands were placed around mandibular and maxillary premolars in 3 dogs in order to induce breakdown of the periodontal tissues. When the destruction had reached a level corresponding to approximately half the root length, the elastic bands were removed and the teeth were scaled. After a period with plaque control, mucoperiosteal flaps were elevated on the buccal and lingual aspects of the experimental teeth. The exposed root surfaces were curetted, and a notch was made at the level of the reduced bone crest. In randomly selected test quadrants, Kielbone mixed with fibrin sealant (Tisseel) was placed in the interproximal space and in the bifurcations. Both the buccal and lingual aspect of the test teeth were then covered by a teflon membrane (Zitex) and the raised tissue flaps sutured in a coronally displaced position. The contralateral teeth (controls) were treated the same way, except that fibrin sealant without Kielbone was applied in the bifurcations and the interproximal space prior to the placement of the membranes. The membranes were removed by a 2nd operation after 35 days. Clinically, various complications were observed during healing. The buccal and lingual flap margins consistently failed to join in the interproximal area, and increasing recession of the flap margins and exposure of the membranes, resulting in accumulation of bacterial deposits and food debris, occurred during the period the membranes were maintained.(ABSTRACT TRUNCATED AT 250 WORDS)

The aim of the present study was to evaluate whether new attachment, gained following guided tissue regeneration (GTR) therapy, can be maintained over longer periods of maintenance therapy. 88 sites at 52 teeth with various types of periodontal defects in 39 patients were treated with the GTR procedure during the period 1984-1989. The effect of treatment was evaluated by assessing probing attachment level (PAL) prior to surgery and 6 months post-surgery. Only sites which at the 6-month examination (baseline) had gained 2 mm or more of PAL were regarded as successfully treated and scheduled for further monitoring. At baseline, 80 sites could be identified which fulfilled this criterium. Of the 80 new attachment sites, all have been monitored for 1 year, 65 for 2 years, 40 for 3 years, 17 for 4 years and 9 sites for 5 years. The results demonstrated that the attachment gain, obtained as the result of the GTR treatment, could be maintained over periods up to 5 years.

19 patients with a total of 23 periodontal lesions were selected for the study. Following flap-elevation, an occlusive membrane (Gore Tex) adjusted to the size and shape of the lesion was applied. The membrane was removed 4-6 weeks later by a 2nd operation. Clinical attachment levels were measured and intraoral radiographs taken prior to surgery, and 6 and 12 months postoperatively. The root length and marginal bone level were measured on paper drawings of the teeth magnified (15x) from the conventional radiographs. The radiographs were digitized for analysis of the subtraction images between the preoperative and the 6- and 12-month postoperative images. Clinical attachment gain was seen in 78% of the teeth after 6 months and 70% after 12 months. Bone gain was recorded in 56% and 22% after 6 months and in 44% and 66% after 12 months by conventional and digital subtraction radiography, respectively. The bone level measurements on conventional radiographs differed significantly (p = 0.001) between the preoperative and 6-month postoperative, but not between the 6- and 12-month, (p = 0.29) conventional radiographs. There was no significant relationship between the clinical measurements and the assessments of bone changes on conventional radiographs (r = 0.28, p = 0.25), while a stronger relationship was observed between assessment of clinical attachment gain and assessment of bone changes on the subtraction images (r = 0.58, p = 0.01).

Segmental, 1-cm osteoperiosteal defects were produced in both radii of 10 rabbits. One defect was covered with a biodegradable polyurethane membrane formed as a tube. The contralateral defect served as an untreated control. Healing was analyzed by radiographic and histologic studies after 5 weeks. Nine out of 10 control defects displayed nonunion, whereas membrane-treated defects consistently healed by forming callus external to the membrane fusing the bone fragments. Loose connective tissue was predominant in the bone gap underneath the membrane. Presumably, the membrane has served as a scaffold for regenerating periosteum.

Guided tissue regeneration (GTR) is a new treatment principle in surgical therapy, developed from the result of studies in experimental animals. It implies that only those types of cells with the capacity of producing regeneration are allowed to invade the surgically treated lesion during healing. This is accomplished by the placement of a physical barrier with excludes undesirable types of tissue. Healing of periodontal bony lesions can be obtained predictably by treatment according to the principle of guided tissue regeneration but several studies have suggested that the same principle can also be applied successfully in other fields of dentistry. In implantology, the method has been used for immediate placement of implants into extraction sockets, for healing of peri-implant bony defects and for augmentation of atrophic alveolar ridges.

Recent studies have demonstrated extensive amounts of new attachment formation following reconstructive surgery based on the biological principle of guided tissue regeneration (GTR). The aim of the present investigation was to evaluate the effect of using a polytetrafluorethylene (PTFE) membrane in GTR-treatment of recession-type defects and to examine the interrelationship between the PTFE membrane and surrounding periodontal tissues. Full-thickness flaps were raised around 24 maxillary premolar and molar teeth in 6 monkeys. The buccal alveolar bone was surgically removed to a level corresponding to the apical third of the roots. The exposed root surfaces were scaled and planed. In 12 teeth, PTFE membranes were adjusted to cover the exposed root surfaces from a level 1 to 2 mm apical to the CEJ, to a level 3 to 4 mm apical to the alveolar crest. The coronal border of the membranes was tightly adapted to the root surfaces by sling sutures. Twelve teeth served as control teeth without placement of membranes. The flaps were placed with the margin coronal to the CEJ and sutured. The animals were sacrificed after 3 months of healing and all experimental teeth were subjected to histological analysis. The membranes were found to be incorporated with the surrounding connective tissue, and the apical extension of the junctional epithelium terminated at the coronal border of the membranes. The amount of new attachment formation was on the average 74.3% of the defect height in the test teeth, which corresponded to 100% of the membrane covered root portion. Newly formed connective tissue attachment in the controls amounted to an average of 36.9% of the defect height.(ABSTRACT TRUNCATED AT 250 WORDS)