Histologic evaluation of new attachment apparatus formation in humans. Part II

Healing of intrabony defects following treatment with a bovine-derived xenograft and collagen membrane. A controlled clinical study

AIM

: The purpose of the present study was to compare clinically the treatment of deep intrabony defects with a combination of a bovine-derived xenograft (BDX) and a bioresorbable collagen membrane to access flap surgery.

METHODS

: Twenty-eight patients suffering from chronic periodontitis, and each of whom displayed one intrabony defect, were randomly treated with BDX + collagen membrane (test) or with access flap surgery (control). Soft tissue measurements were made at baseline and at 1 year following therapy.

RESULTS

: No differences in any of the investigated parameters were observed at baseline between the two groups. Healing was uneventful in all patients. At 1 year after therapy, the test group showed a reduction in mean probing depth (PD) from 9.2+/-1.3 to 3.9+/-0.7 mm (p<0.001) and a change in mean clinical attachment level (CAL) from 10.2+/-1.5 to 6.2+/-0.5 mm (p<0.0001). In the control group, the mean PD was reduced from 9.0+/-1.2 to 5.2+/-1.8 mm (p<0.001) and the mean CAL changed from 10.5+/-1.5 to 8.4+/-2.1 mm (p<0.01). The test treatment resulted in statistically higher PD reductions (p<or=0.05) and CAL gains (p<0.001) than the control one. In the test group all sites (100%) gained at least 3 mm of CAL. In the control group no CAL gain occurred in four sites (29%), whereas at six sites (43%) the CAL gain was 2 mm. A CAL gain of 3 mm or more was measured in four defects (29%).

CONCLUSIONS

: Within the limits of the present study, it can be concluded that: (i) at 1 year after surgery both therapies resulted in significant PD reductions and CAL gains, and (ii) treatment with BDX+collagen membrane resulted in significantly higher CAL gains than treatment with access flap surgery.

Combined therapy of mineral trioxide aggregate and guided tissue regeneration in the treatment of external root resorption and an associated osseous defect

BACKGROUND

The treatment of external root resorption and associated periodontal defects can be challenging to the most astute clinician. In this case report, a multidisciplinary approach was performed to treat a maxillary central incisor that presented with a sinus tract. An amalgam restoration had been placed approximately 10 years earlier to repair an area of external root resorption.

METHODS

A full-thickness mucoperiosteal flap was reflected from teeth #8 to #9. Following degranulation of the area, an amalgam restoration was found on the distal root surface of tooth #8. A 2-wall osseous lesion was also associated with the distal surface of #8. The amalgam was removed and the defect was restored with mineral trioxide aggregate (MTA). The root surface was chemically conditioned with tetracycline, and the osseous defect was grafted with decalcified freeze-dried bone allograft (DFDBA) and a calcium sulfate barrier.

RESULTS

An 8 mm gain in clinical attachment, as well as an increase in radiodensity, was noted on the distal surface of tooth #8 at 15 months postsurgery. The patient was also asymptomatic, with no clinical signs of inflammation present.

CONCLUSIONS

A combined approach utilizing MTA for root surface repair, and DFDBA and calcium sulfate to address an associated osseous lesion, appears to be a viable modality in the treatment of chronic endodontic/periodontal lesions.

Characterization of bone defect repair in young and aged rat femur induced by xenogenic demineralized bone matrix

BACKGROUND

The osteoinductive effect of some biomaterials could be affected by those systemic conditions typical of old age. The aim of the present paper was to assess the effects of age on the healing of bone defects treated with demineralized bone matrix (DBM).

METHODS

The study was conducted in young (3 month old) and aged (18 month old) rats to assess the efficacy of DBM in the treatment of osseous defects in bone with limited repair capacities. A standard bone defect was created in the distal femoral condyles of male Wistar rats: the left condyle was filled with rabbit DBM granules, while the right condyle was left empty (control). Histological and microhardness analyses were performed at 30 and 45 days after implant surgery.

RESULTS

After implantation of xenogenic DBM, bone healing areas of the aged and young groups showed a significant increase in the formation of newly mineralized bone relative to controls. Measurements of trabecular thickness on day 45 revealed no differences between newly formed and preexisting bone in the young group, while control values were lower. Microhardness measurements demonstrated that newly mineralized bone, either induced by DBM or not, and preexisting bone were comparable in terms of trabecular hardness after 45 days.

CONCLUSIONS

In conclusion, xenogenic DBM seems to be effective in bone defect healing, since it increases mineralized tissue volume. In both DBM-filled and empty sites, age seems to have a detrimental effect on the volume of new bone formation but no influence on bone maturation.

A retrospective case series comparing the use of demineralized freeze-dried bone allograft and freeze-dried bone allograft combined with enamel matrix derivative for the treatment of advanced osseous lesions

BACKGROUND

Combined regenerative approaches have been used for treating advanced osseous lesions around teeth. The aim of combining treatments is to enhance both clinical predictability and regenerative outcome compared to a monotherapeutic approach. This case series from a private practice reports on the clinical efficacy of an enamel matrix derivative (EMD) combined with either demineralized freeze-dried bone allograft (DFDBA) or freeze-dried bone allograft (FDBA) in the treatment of advanced infrabony lesions. The advanced lesions were veneered by a rapidly formed absorbable polymer barrier of poly(DL-lactide) to enhance graft containment.

METHODS

A total of 22 consecutive patients, each contributing one infrabony lesion, are reported. After patients completed presurgical preparation, the infrabony lesions were surgically treated with a combined approach that included root surface treatment with citric acid. The two groups differed in their composite graft; one received DFDBA-EMD (n = 10) and the other received FDBA-EMD (n = 12). Patients followed a stringent postoperative protocol and were evaluated 6 months postsurgery. Clinical outcomes were assessed by changes in clinical attachment level (CAL) and probing depth (PD) from pretreatment. Surgical re-entry of several sites was possible in each group.

RESULTS

CAL at pretreatment measured 9.2 +/- 1.3 mm and 9.1 +/- 1.9 mm for DFDBA-EMD and FDBA-EMD groups, respectively, with corresponding PD of 8.4 +/- 1.6 mm and 8.9 +/- 2.0 mm for each group. At 6 months post-treatment, CALs were reduced to 4.7 +/- 1.3 mm and 3.8 +/- 1.0 mm for DFDBA-EMD and FDBA-EMD groups, respectively; with corresponding PD decreased to 3.0 +/- 0.8 mm and 3.2 +/- 1.0 mm. Relative improvements in CAL for the DFDBA-EMD and DFDBA-EMD groups were 49.1% +/- 11.0% and 57.3% +/- 9.4%, respectively (P <0.07).

CONCLUSIONS

This case series demonstrates the clinical benefits of using a combined therapeutic approach in which a biologic mediator (EMD) was combined with either DFDBA or FDBA. In this limited case series, a trend was observed towards greater improvement in clinical attachment level gain in advanced infrabony defects when EMD was combined with FDBA as compared to DFDBA. Larger prospective controlled clinical trials are needed to determine if differences exist in the relative efficacy of DFDBA versus FDBA in combination with EMD.

Enhanced guided bone regeneration with a resorbable chamber containing demineralized bone matrix

BACKGROUND

The effectiveness of a nonporous poly-DL-lactide tubular chamber in guiding bone regeneration through a long bone defect had already been assessed in an experimental model using the rabbit radius. The injection of bone marrow stem cells into the chamber had proven to enhance bone regeneration.

METHODS

The present study reports on the development of the above research project in a subsequent stage. Demineralized bone matrix (DBM) obtained by milling New Zealand rabbit femoral and tibial diaphyses was placed into a tubular chamber. A 10-mm defect was bilaterally created in the radii of 10 rabbits. On the left side (chamber side) the defect was treated by means of a poly-DL-lactide chamber filled with DBM, whereas DBM alone was used on the right side (control).

RESULTS

Controls were performed at 3 and 6 months by radiographs and histomorphometry and demonstrated better bone growth on the chamber side versus the control side. A comparison with the results previously obtained by stem cell injection into the chamber revealed significant acceleration of bone regrowth in the first 3 months because of the addition of DBM to the chamber. However, no significant difference was found between the two sides after 6 months.

CONCLUSION

These results have confirmed the effectiveness of the chamber as a container for the factors promoting bone regeneration, probably because the osteogenetic activity is maintained in situ.

A clinical comparison of a bovine-derived xenograft used alone and in combination with enamel matrix derivative for the treatment of periodontal osseous defects in humans

BACKGROUND

Enamel matrix protein derivative (EMD) and particulate anorganic cancellous bovine-derived bone xenograft (BDX) have both shown favorable clinical results in reducing intrabony periodontal defects as compared to open flap debridement alone. These materials have shown results comparable to those obtained with guided tissue regeneration. The primary aim of the present study was to evaluate the effectiveness of EMD combined with BDX as compared to BDX alone, with a secondary aim to compare the treatment outcomes of the 2 modalities.

METHODS

Seventeen patients with paired intrabony defects and probing depths measuring > or = 5 mm who were being treated for chronic periodontitis were selected for this controlled, blinded, split-mouth study. Following non-surgical periodontal therapy, sites were randomly selected to receive either a combination of EMD and BDX (test group) or BDX alone (positive control group). Baseline and 6-month surgical reentry measurements were taken by a calibrated examiner blinded to the treatment. A paired Student t test was utilized to evaluate differences between baseline and post-treatment and between the treatment groups.

RESULTS

Favorable clinical outcomes for both hard and soft tissue measurements were achieved for both treatment groups when compared to baseline (P < 0.001). There was no statistically significant difference for any of the measured clinical parameters. Probing depth reduction for the test group and control group was 4.2 +/- 1.1 mm and 3.9 +/- 1.3 mm, respectively (P > 0.8). Mean gain in clinical attachment levels for the test and control groups was 3.8 +/- 0.9 mm and 3.7 +/- 1.5 mm, respectively (P > 0.6). Hard tissue measurements obtained at surgical reentry were used to calculate the bone fill (BF) and percent bone fill (%BF). The BF was 3.2 +/- 1.4 mm and 3.0 +/- 1.2 mm (P > 0.6), and the %BF was 63.3 +/- 16.3% and 67.0 +/- 19.0% (P > 0.4) for the EMD + BDX and BDX groups, respectively.

CONCLUSIONS

In summary, both the particulate anorganic cancellous bovine-derived bone xenograft used alone and in combination with enamel matrix derivative are effective for the treatment of human intrabony periodontal lesions.

Clinical comparison of an enamel matrix derivative used alone or in combination with a bovine-derived xenograft for the treatment of periodontal osseous defects in humans

BACKGROUND

The combination of bone replacement graft materials has been suggested for the treatment of periodontal osseous defects. The purpose of this study was to evaluate the effectiveness of enamel matrix derivative (EMD) combined with a bovine-derived xenograft (BDX) as compared to EMD alone in the treatment of intraosseous defects in patients with moderate to advanced periodontitis.

METHODS

Sixteen adult patients with at least 2 intrabony defects were entered in this split-mouth design study. Defects were treated with EMD alone or EMD + BDX. Reentries were performed 6 to 8 months after initial surgery. The following soft and hard tissue measurements were recorded prior to initial surgery and at reentry: probing depth (PD), gingival margin location, clinical attachment level (CAL), depth of defect, and crestal bone level. Statistical analyses were performed to determine changes in PD, CAL, fill of osseous defect, and crestal resorption. Percentages of bone fill (%BF) and defect resolution (%DR) were also calculated.

RESULTS

The most significant results were that gingival recession was greater for the group treated with EMD alone (0.8 +/- 0.8 mm) compared to EMD + BDX (0.3 +/- 0.6 mm) (P = 0.04) and bone fill was greater for EMD + BDX (4.0 +/- 0.8 mm) compared to EMD alone (3.1 +/- 1.0 mm) (P = 0.02). The measures for PD reduction, attachment level gain, crestal resorption, %BF, and %DR did not present a statistically significant difference (P > 0.10).

CONCLUSIONS

This study evaluated the performance of EMD + BDX and EMD alone. The results demonstrated that a significant improvement in clinical parameters was observed. When comparing both modalities, a statistically significant difference was only found for gingival recession and bone fill, yielding a more favorable outcome towards the combined approach.

Clinical evaluation of an enamel matrix protein derivative combined with a bioactive glass for the treatment of intrabony periodontal defects in humans

BACKGROUND

The purpose of the present study was to compare the treatment of deep intrabony defects with a combination of an enamel matrix protein derivative (EMD) and a bioactive glass (BG) to BG alone.

METHODS

Twenty-eight patients with chronic periodontitis, each of whom displayed 1 intrabony defect, were randomly treated with a combination of EMD and BG or with BG alone. Soft tissue measurements were made at baseline and at 1 year following therapy.

RESULTS

No differences in any of the investigated parameters were observed at baseline between the 2 groups. Healing was uneventful in all patients. At 1 year after therapy, the sites treated with EMD and BG showed a reduction in mean probing depth (PD) from 8.07 +/- 1.14 mm to 3.92 +/- 0.73 mm and a change in mean clinical attachment level (CAL) from 9.64 +/- 1.59 mm to 6.42 +/- 1.08 mm (P < 0.0001). In the group treated with BG, the mean PD was reduced from 8.07 +/- 1.32 mm to 3.85 +/- 0.66 mm and the mean CAL changed from 9.78 +/- 1.71 mm to 6.71 +/- 1.89 mm (P < 0.0001). No statistically significant differences in any of the investigated parameters were observed between the test and control group.

CONCLUSIONS

Within the limits of the present study, it can be concluded that both therapies led to significant improvements of the investigated clinical parameters, and the combination of enamel matrix derivative and bioactive glass does not seem to additionally improve the clinical outcome of the therapy.

Combined periodontal regenerative technique in human intrabony defects by collagen membranes and anorganic bovine bone. A controlled clinical study

BACKGROUND

Combined periodontal regenerative technique (CPRT) is a surgical procedure that combines the use of barrier membranes with a filling material in the treatment of periodontal defects. The effectiveness of CPRT has been evaluated in many studies in comparison to GTR with membranes alone, but conflicting results have been obtained by different clinicians, particularly in the treatment of intrabony defects. The aim of the present study was to compare CPRT to GTR with collagen membranes in the treatment of human intrabony defects characterized by a relevant 1-wall component.

METHODS

Thirty-four (34) healthy, non-smoking patients affected by moderate to severe chronic periodontitis participated in this study. Each patient had good oral hygiene and at least 1 radiographically detectable intrabony defect > or = 4 mm, with a 1-wall component of at least 50% of the defect, involving 2 tooth surfaces or more with a probing depth (PD) > or = 6 mm. Seventeen (17) subjects were randomly assigned to the test group and underwent CPRT by anorganic bovine bone and a collagen membrane, and 17 randomly assigned to the control group who received GTR with a collagen membrane alone. Pre- and post-therapy clinical parameters (probing depth [PD]; clinical attachment level [CAL]; gingival recession [GR]) and intrasurgical parameters (depth of intraosseous component [IOC]; level of the alveolar crest [ACL]) were compared between test and control groups 1 year after treatment. Vertical bone gain (VBG) from the base of the defect to the cemento-enamel junction was also evaluated in both groups.

RESULTS

At the 1-year examination, clinical and intrasurgical parameters showed statistically significant changes within each experimental group from baseline. A statistically greater CAL gain was reported in the test group (P<0.05), whereas the control group exhibited more GR and alveolar crest resorption at a statistically significant level (P<0.01). VBG was significantly greater (P<0.01) at test sites (5.23 +/- 1.30 mm) compared to controls (3.82 +/- 1.28 mm).

CONCLUSIONS

The results suggest that the use of CPRT may be preferred when bioabsorbable membranes are used to treat intrabony defects characterized by unfavorable architecture.

The effects of varying degrees of allograft decalcification on cultured porcine osteoclast cells

BACKGROUND

Demineralized freeze-dried bone allograft (DFDBA) is widely used in periodontal therapy as a scaffold for new bone formation in periodontal defects. It is demineralized, theoretically, to expose osteoinductive or osteoconductive bone matrix proteins that should facilitate osteogenesis. The degree of DFDBA demineralization varies between tissue banks and may affect clinical regeneration. A 2% residual calcium level in DFDBA has been shown to result in the highest alkaline phosphatase activity levels in cultured human periosteal cells and is optimally osteoinductive or osteoconductive for new bone formation. The purpose of this study was to evaluate the effect of 4 different residual calcium levels in commercially available DFDBA samples on porcine osteoclast activity as measured by resorption on calcium phosphate-coated disks.

METHODS

Bone marrow was harvested from the femurs of 3-week-old farm pigs and cultured for 3 weeks. Hematopoietic stem cells were allowed to differentiate into mature active polykaryons displaying genuine osteoclast characteristics. The osteoclast cells displayed a dense actin band inside the margins of the cytoplasm under light microscopy. Culture media was decanted and collagenase added to free the attached cells. Equal cell samples were pipetted onto calcium phosphate-coated disks in 24-well plates. DFDBA samples with 1.44%, 2.41%, and 5.29% residual calcium; FDBA (30% residual calcium); and control cultures without allograft samples were prepared and all samples incubated for 1 week. Cells were fixed and stained for tartrate-resistant acid phosphatase (TRAP), Oregon Green 488-phalloidin, a stain for cytoskeletal proteins, and counterstained with propidium iodide. Specimens were examined by light and fluorescence microscopy using epi-illumination. Calcium phosphate disks were then rinsed in 5% sodium hypochlorite to remove adherent osteoclasts, and substrate surface changes were measured by white light interferometry and image analysis.

RESULTS

A higher yield of TRAP-positive cells was produced without DFDBA; however, resorptive activity appears to be significantly increased in the presence of 2.41% residual calcium as compared to all other experimental groups (P<0.0065).

CONCLUSION

In this in vitro model, porcine osteoclasts show significantly more resorptive activity as measured on calcium phosphate-coated disks in the presence of 2.41% residual calcium in DFDBA than in other DFDBA residual calcium levels.

Treatment of intrabony defects with enamel matrix proteins and guided tissue regeneration

BACKGROUND

Utilisation of enamel matrix proteins (EMD) and application of the guided tissue regeneration principle (GTR) are treatment modalities which both have been shown to result in periodontal regeneration. However, it is yet unknown whether the combination of EMD and GTR may additionally favor the regeneration process.

AIM

The aim of the present controlled study was to evaluate clinically the treatment effect of EMD, GTR, combination of EMD and GTR, and flap surgery (control) on intrabony defects.

MATERIAL AND METHODS

56 patients each of whom displaying one intrabony defect of a depth of at least 6 mm were randomly treated with one of the treatment modalities. Prior to surgery and at one year after, the following parameters were evaluated by a blinded examiner: Plaque index (PlI), gingival index (GI), bleeding on probing (BOP), probing pocket depth (PPD), gingival recession (GR) and clinical attachment level (CAL). No statistical significant differences between the four groups were observed at baseline for any of the investigated parameters.

RESULTS

At 1 year after therapy, the sites treated with EMD demonstrated a mean PPD reduction of 4.1 +/- 1.7 mm and a mean CAL gain of 3.4 +/- 1.5 mm (p<0.001). The sites treated with GTR showed a mean PPD reduction of 4.2 +/- 1.9 mm and a mean CAL gain of 3.1 +/- 1.5 mm (p<0.001). The sites treated with the combined treatment showed a mean PPD reduction of 4.3 +/- 1.4 mm and a mean CAL gain of 3.4 +/- 1.1 mm (p<0.001). In the control group, the mean PPD reduction was 3.7 +/- 1.4 mm (p<0.001) and the mean CAL gain measured 1.7 +/- 1.5 mm (p<0.01). All 4 treatments led to statistically significant PPD reduction and CAL gain. All three regenerative treatments led to higher CAL gain than the control treatment (p<0.05). No statistical significant differences in PPD reduction and CAL gain were observed between the three regenerative treatments.

CONCLUSION

It may be concluded that (a) all 3 regenerative treatment modalities may lead to higher CAL gain than the control one, and (b) the combined treatment does not seem to improve the outcome of the regenerative procedure.

Treatment of plaque-induced gingivitis, chronic periodontitis, and other clinical conditions

The inflammatory components of plaque induced gingivitis and chronic periodontitis can be managed effectively for the majority of patients with a plaque control program and non-surgical and/or surgical root debridement coupled with continued periodontal maintenance procedures. Some patients may need additional therapeutic procedures. All of the therapeutic modalities reviewed in this position paper may be utilized by the clinician at various times over the long-term management of the patient's periodontal condition.

Histology of connective tissue graft. A case report

BACKGROUND

Few investigations can be found in the literature on the histological nature of the attachment of connective tissue grafts to root surfaces previously exposed by recession.

METHODS

In this case report, a 24-year-old patient was treated with a connective tissue graft combined with a partial-thickness coronally positioned flap for root coverage of Class I Miller recessions at the maxillary right and left canines and first premolars. The treated sites exhibited 83% and 100% root coverage on the right and left sides, respectively. Twelve months later, the case required extraction of all 4 first premolars for orthodontic reasons. Two conservative block sections including the maxillary first premolars with the buccal soft tissues were obtained and processed histologically in a bucco-palatal plane.

RESULTS

Histological analysis showed that healing occurred via a long junctional epithelium throughout the major portion of the previous recession site. Only minimal signs of new cementum-like tissue formation could be seen in the apical portion of the recession area coronal to the base of the instrumented root surface. No root resorption or ankylosis could be detected in any of the serial sections.

CONCLUSIONS

The findings of this case report outline the possible variations in the histological outcome of connective tissue grafts. These variations can be attributed to differences in size and shape of the recession defects and flap positioning at the end of surgery.

Combined implantation of particulate dentine, plaster of Paris, and a bone xenograft (Bio-Oss) for bone regeneration in rats

The purpose of this study is to assess the combination of particulate dentine and plaster as bone substitute material in calvarial bone defects in rats, and to compare it with a bone xenograft (Bio-Oss).

MATERIAL AND METHODS

Forty rats were assigned randomly to five groups and each group was further divided into two subgroups, 8 and 16 weeks after implantation. The defect was filled with different graft materials in each group: Group 1, defects were filled with particulate dentine and plaster using a 2:1 ratio; Group 2, defects were filled with particulate dentine; plaster, and Bio-Oss using a 2:1:1 ratio; Group 3, defects were filled with plaster and Bio-Oss using a 1:1 ratio; Group 4, defects were filled with Bio-Oss only; and Group 5, untreated control defects. Histological sections and histomorphometric analysis of defects were obtained at 8 and 16 weeks postoperatively.

RESULTS

New bone formation was highest in Group 4, followed by Group 3, than Group 2, Group 1, and finally the control group.

CONCLUSION

The combination of particulate dentine and plaster is an alternative bone substitute, although it is less effective than Bio-Oss.

The osteoinductive potential of demineralized freeze-dried bone allograft in human non-orthotopic sites: a pilot study

BACKGROUND

The use of demineralized freeze-dried bone allograft (DFDBA) in periodontal therapy is widely accepted. In addition to histologic studies demonstrating its role in regenerating the attachment apparatus, its recognized ability to exhibit osteoinduction in small laboratory mammals has prompted many clinicians to regard it as osteoinductive when utilized in periodontal therapy. Despite such a theoretical deduction, evaluating and establishing the osteoinductive potential of DFDBA in humans has been problematic. The purpose of this study was to investigate, through the use of a novel implantation/recovery model, the potential of DFDBA to induce new bone formation at sites not normally considered capable of de novo osteogenic activity.

METHODS

Seven patients scheduled to undergo periodontal therapy utilizing non-absorbable membranes agreed to have sterile polypropylene mesh capsules placed adjacent to the primary surgical site for the purpose of this investigation. One capsule was left empty while the second capsule contained DFDBA. At the appropriate time interval for removal of the therapeutic membrane, the capsules were removed and submitted for histologic analysis. Five of the subjects had procedures directed at regenerating bone within molar furcations (guided tissue regeneration) and had the membranes and associated capsules removed between 6 and 8 weeks. The 2 remaining patients had procedures directed toward ridge augmentation (guided bone regeneration) and had the membranes removed either at 8 or 9 months, respectively. In addition, one of the 2 long-term membrane patients had liberal cortical penetration performed directly beneath the implanted capsule.

RESULTS

Histologic analysis of all recovered capsules by 2 independent oral and maxillofacial pathologists could not confirm the presence of either osteoblastic or osteoclastic activity associated with the DFDBA particles, although the 2 longer-term specimens clearly exhibited trace amounts of vital bone non-contiguous with the implanted material.

CONCLUSIONS

The results of this pilot study do not support the osteoinductive potential of DFDBA when utilized in quantities normally associated with periodontal bone grafting, although they do support the use of this implantation/recovery model to study other preparations and mechanisms of bone formation.

Orthodontic tooth movement enhances bone healing of surgical bony defects in rats

BACKGROUND

The question of whether the repair of an alveolar bony defect can be enhanced by orthodontic tooth movement was addressed.

METHODS

Alveolar bone defects were created in 52 Wistar male rats anterior to both maxillary first molars. After 1 week of healing, orthodontic protraction was applied for 2 weeks on the right side, resulting in mesial tipping and displacement movement. Subsequently, a retention appliance was inserted for 1 week. The left side served as the untreated (control) group. Vital bone staining (procion brilliant red H-8) was administered before and after orthodontic traction. Histomorphometric analysis was performed on 62 hemimaxillae using UV confocal microscopy and an imaging program. The total area of the bony defect was divided into 4 equal quadrants, and the area of bony apposition in each quadrant was measured.

RESULTS

The total area of bony apposition was 6.5-fold larger in the treated (26.41 x 10(4) +/- 28.92 x 10(4) microm2) than in the control group (4.07 x 10(4) +/- 2.82 x 10(4) microm2), approaching statistical significance (P = 0.065). The treated occlusal quadrants demonstrated highly significant (P= 0.010), greater bone apposition compared to the control group (13.8-fold) and to the treated apical quadrants (P= 0.04, 5-fold).

CONCLUSIONS

This study confirms that orthodontic tooth movement is a stimulating factor of bone apposition. A conversion in the repair pattern of the bony defect from apicoocclusal in the control group (no tooth movement) to occlusoapical in the treated group (with tooth movement) further supports the linkage between tooth movement and enhanced bone deposition. Clinical implication suggests incorporation of orthodontic tooth movement in regenerative therapy.

Evaluation of the regenerative effect of a 25% doxycycline-loaded biodegradable membrane for guided tissue regeneration

BACKGROUND

Biodegradable materials have been successfully utilized for guided tissue regeneration (GTR) and local delivery systems (LDS) because they are biocompatible, less cytotoxic, and do not require removal. Several studies have demonstrated that tetracyclines (TCs), when applied topically, stimulated osteogenesis in experimental bone defects. The purpose of this study was to evaluate the regenerative effect of a 25% doxycycline-loaded biodegradable GTR membrane (Doxy-M) in dogs.

METHODS

Doxy-M was made by coating the inner surface of a biodegradable membrane (BD-M) with 25% doxycycline. Five male mongrel dogs with 20 created osseous defects were enrolled. The plain BD-M was used as the control membrane. Either Doxy-M or BD-M was applied in 20 randomly selected defects (10 Doxy-M, 10 BD-M) for 12 weeks with the GTR technique. The histometric analysis was evaluated with the following parameters: defect height (DH), apical extension of junctional epithelium (AEJP), new cementum height (NCH), new bone height (NBH), and new bone area (NBA).

RESULTS

The Doxy-M-treated defects showed more pronounced new bone formation and less crestal bone resorption than the BD-M-treated defects. There were no statistically significant differences between the two groups in DH, AEJP, and NCH. Statistically significantly larger NBH (P <0.05) and NBA (P<0.005) were seen in the Doxy-M-treated defects.

CONCLUSIONS

The results strongly suggest that Doxy-M may have a beneficial effect on osteogenesis to favor periodontal regeneration.

Histologic evaluation of periodontal healing in humans following regenerative therapy with enamel matrix derivative. A 10-case series

BACKGROUND

Enamel matrix derivative (EMD) has been developed as a stimulus of periodontal regeneration. Human histology following its use has not been evaluated on pathologically altered root surfaces.

METHODS

Ten intrabony defects in 8 patients were evaluated at 2 centers. Teeth with advanced adult periodontitis that were treatment planned for extraction were treated with sulcular incisions; full-thickness flap reflection; debridement of granulomatous tissue from the defect; placement of a notch in the root at the apical extent of calculus; mechanical root planing; conditioning with citric acid; application of EMD; wound closure with sutures; and placement of a periodontal dressing. Biweekly to monthly recalls were made until removal of small block section biopsies at about 6 months. The biopsies were fixed, decalcified, step-serial sectioned at 6 microns to 8 microns, and stained with hematoxylin and eosin or Masson's trichrome.

RESULTS

Histologic evaluation of the region coronal to the base of the calculus notch showed evidence of regeneration (new cementum, new bone, and new periodontal ligament) in 3 specimens, new attachment (connective tissue attachment/adhesion only) in 3 specimens, and a long junctional epithelium in 4 specimens. No evidence of root resorption, ankylosis, or untoward inflammation was seen.

CONCLUSIONS

The results of this study fulfill the proof of principle that use of EMD can result in periodontal regeneration on previously diseased root surfaces in humans, but on an inconsistent basis.

Long-term results of a minimally invasive surgical approach for bone grafting

A retrospective analysis of the results obtained from regenerative surgery performed utilizing a minimally invasive surgical approach was performed. Bone grafting procedures were performed at 194 sites in 87 patients using small incisions and minimal flap reflection. There were 44 females with a mean age of 52.7 years and 43 males with a mean age of 54.9 years. The mean healing time at which data were collected was 21.7 months. Postsurgical data were collected at the time of routinely scheduled supportive periodontal therapy (SPT) appointments by 2 evaluators. Mean changes in probing depth and attachment levels were evaluated utilizing a Wilcoxon sign rank test. Mean improvement in probing depth was 4.58 mm (P <0.0001) and attachment level was 4.87 mm (P <0.0001). These improvements were seen for all levels of initial prognosis (good to poor) and appeared to be stable over time. The postsurgical gingival margin was at or within 1 mm of the cemento-enamel junction (CEJ) for 58% of the sites treated. This was interpreted to indicate good retention of soft tissue height postsurgically. It was concluded that the minimally invasive approach for bone grafting yielded results that were equivalent to more traditional surgical approaches utilizing longer incisions and greater reflection.

Polymer-assisted regenerative therapy: case reports of 22 consecutively treated periodontal defects with a novel combined surgical approach

This report describes the clinical application of an in situ formed barrier of poly(DL-lactide) used in combination with a composite graft of demineralized freeze-dried bone allograft (DFDBA) mixed with calcium sulfate and tetracycline in a ratio of 7:2:1 and citric acid root conditioning for the treatment of intrabony and furcation defects. The clinical outcome was assessed by changes in clinical attachment level (CAL) and probing depth (PD) in 18 consecutively treated patients with 17 intrabony and 5 furcation lesions. After patients demonstrated acceptable oral hygiene, the lesions were surgically treated with combination therapy using an in situ formed barrier over a DFDBA composite graft. Patients followed a stringent postoperative protocol and were evaluated at 6 months postsurgery. CAL improved for all sites from a presurgical average of 8.8+/-2.3 mm to 4.4+/-1.6 mm at 6 months postsurgery (4.4+/-1.5 mm gain), while PD was reduced from an average of 8.3+/-2.1 mm presurgery to 3.3+/-1.1 mm at 6 months postsurgery (5.0+/-1.8 mm reduction). Five furcations were treated, of which 4 were Class II and 1 was Class III. Of these furcation lesions, 3 had complete clinical closure, while 1 improved by 1 grade. The Class III furcation remained the same. Results suggest that DFDBA composite graft covered by an in situ formed barrier on root surfaces treated with citric acid can enhance the prognoses of teeth with periodontal lesions as measured by CAL gains and PD reductions. Further studies are warranted to compare this treatment to other more traditional forms of regenerative therapy to determine its comparative efficacy.

Guided tissue regeneration in Class II furcation involved maxillary molars: a controlled study of 8 split-mouth cases

The purpose of this study was to clinically evaluate the effectiveness of polytetrafluoroethylene membranes in the healing of interproximal Class II furcation defects in maxillary molars using a surgical treatment technique based on the principles of guided tissue regeneration. Eight subjects with similar bilateral Class II furcation lesions on the mesial aspect of maxillary first molars participated in this study. Patients received initial therapy consisting of oral hygiene instructions, scaling and root planing, and occlusal adjustment if necessary. Clinical parameters evaluated included plaque index, sulcular bleeding index, probing depth, attachment level, gingival recession, and open horizontal and vertical furcation fill. An acrylic occlusal stent was used to assure reproducibility of measurements. Experimental sites received a polytetrafluoroethylene membrane following surgical exposure of the furcation. Control sites were treated in the exact same manner but without a membrane. Membranes were removed at 6 weeks after the first surgery. Reentry surgeries were performed at 9 months. Postsurgical results showed a significant improvement in probing depth, attachment level, and open horizontal furcation fill for both groups when compared to baseline values, with experimental sites performing significantly better than controls. Control sites showed a slight loss in open vertical furcation fill while experimental sites remained unchanged. This study suggests that guided tissue regeneration using polytetrafluoroethylene membranes is of some but limited value in the treatment of maxillary molar interpoximal Class II furcation lesions.

Clinical evaluation of bioactive glass in the treatment of periodontal osseous defects in humans

The purpose of this study was to compare the use of bioactive glass to demineralized freeze-dried bone allograft (DFDBA) in the treatment of human periodontal osseous defects. Fifteen systemically healthy patients (6 males and 9 females, aged 30 to 63) with moderate to advanced adult periodontitis were selected for the study. All patients underwent initial therapy, which included scaling and root planing, oral hygiene instruction, and an occlusal adjustment when indicated, followed by re-evaluation 4 to 6 weeks later. Paired osseous defects in each subject were randomly selected to receive grafts of bioactive glass or DFDBA. Both soft and hard tissue measurements were taken the day of surgery (baseline) and at the 6-month re-entry surgery. The clinical examiner was calibrated and blinded to the surgical procedures, while the surgeon was masked to the clinical measurements. Statistical analysis was performed by using the paired Student's t test. The results indicated that probing depths were reduced by 3.07 +/- 0.80 mm with the bioactive glass and 2.60 +/- 1.40 mm with DFDBA. Sites grafted with bioactive glass resulted in 2.27 +/- 0.88 mm attachment level gain, while sites grafted with DFDBA had a 1.93 +/- 1.33 mm gain in attachment. Bioactive glass sites displayed 0.53 +/- 0.64 mm of crestal resorption and 2.73 mm bone fill. DFDBA-grafted sites experienced 0.80 +/- 0.56 mm of crestal resorption and 2.80 mm defect fill. The use of bioactive glass resulted in 61.8% bone fill and 73.33% defect resolution. DFDBA-grafted defects showed similar results, with 62.5% bone fill and 80.87% defect resolution. Both treatments provided soft and hard tissue improvements when compared to baseline (P < or = 0.0001). No statistical difference was found when comparing bioactive glass to DFDBA; however, studies with larger sample sizes may reveal true differences between the materials. This study suggests that bioactive glass is capable of producing results in the short term (6 months) similar to that of DFDBA when used in moderate to deep intrabony periodontal defects.

Ability of commercial demineralized freeze-dried bone allograft to induce new bone formation is dependent on donor age but not gender

Demineralized freeze-dried bone allografts (DFDBA) have been used extensively in periodontal therapy. DFDBA is used because it contains bone morphogenetic protein (BMP), which induces new bone formation during the healing process. Most commercial bone banks do not verify the presence or activity of BMP in DFDBA nor the ability of DFDBA to induce new bone. Recently, we showed that different bone bank preparations of DFDBA, even from the same bank, varied considerably in their ability to induce new bone, suggesting inherent differences in the quality of the material. Therefore, we examined whether donor age or gender contributed to the variability seen with these preparations. Twenty-seven batches of DFDBA from different donors were donated by one bone bank which had been shown previously to supply DFDBA that was consistently able to induce new bone formation. Each batch was implanted bilaterally in the thigh muscle of nude mice. After 56 days, the implants were excised and examined by light microscopy and histomorphometry. Seventy percent of the preparations tested induced new bone formation. Most of these preparations produced ossicles containing cortical bone surrounding bone marrow-like tissue. The ability to induce bone appears to be age-dependent, with DFDBA from older donors being less likely to have strong bone-inducing activity. By contrast, no difference in ability to induce new bone was noticed between male or female donors. The results of this study confirm that commercial preparations of DFDBA differ in their ability to induce new bone formation. In fact, some of the batches had no activity at all. The ability of DFDBA to induce new bone formation is suggested to be age-dependent, but not gender-dependent by our study. These results indicate that commercial bone banks need to verify the ability of DFDBA to induce new bone formation and should reconsider the advisability of using bone from older donors.

Cervical root resorption associated with guided tissue regeneration: a case report

Root surface resorption, ankylosis (replacement resorption) and alveolar bone resorption are not uncommon sequelae to periodontal healing in both animal and human trials whether the treatment objective is regenerative, preventive, or conservative. The present report describes a case with progressive cervical root resorption in a patient who received periodontal regenerative treatment with guided tissue regeneration (GTR). A 46-year-old woman was referred for treatment of severe periodontitis. Remaining radiographic attachment was less than 50%. Following a period of 18 months, during which non-surgical and surgical therapies were performed, angular defects were diagnosed on radiographs and recurrent bleeding periodontal pockets (6 mm) were found in the proximal areas of 24 and 25. Root caries was not present. Periodontal surgery with GTR was performed in this area. No immediate postsurgical complications were noted. Two years later, clinical and radiographic examinations revealed gingival recession with bleeding periodontal pockets (6 mm) which had partly uncovered severe proximal cervical resorptions in 25. Root surface caries was not present. Following surgical inspection, the root of 25 was removed. The root was subsequently prepared for histological analysis. Resorption cavities covered almost the entire cervical proximal surface of the root above intact infracrestal cementum and were covered by numerous CD68+, both mononuclear and multinucleated cells. In a central area as indicated on the radiographs, the cavities penetrated into the root canal. There was no evidence of root caries.

Periodontal repair in dogs: effect of allogenic freeze-dried demineralized bone matrix implants on alveolar bone and cementum regeneration

The objective of this study was to evaluate alveolar bone and cementum regeneration following surgical placement of an allogenic, freeze-dried, demineralized bone matrix (DBM) cortical strip implant. Critical size, supraalveolar periodontal defects were surgically created around the second, third, and fourth mandibular premolar teeth in eight mongrel dogs. Contralateral jaw quadrants in six animals were randomly assigned to receive the DBM implant, or serve as surgical control. Two additional animals received bilateral DBM implants. Flaps were coronally advanced to submerge teeth and implants, and sutured. Three animals were exited from the study due to extensive early wound failure. Remaining animals were sacrificed at 8 weeks postsurgery. Histometric recordings included defect height, bone regeneration/DBM implant height, cementum regeneration height, root resorption, and ankylosis. Large areas of unresorbed DBM exhibiting fragmentation and empty osteocyte lacunae were observed adjacent to new bone formation, or bone formation was observed adjacent to or within the implant, often exhibiting ankylosis. Cementum regeneration appeared enhanced in shelter of the DBM implant. Histometric recordings (mean+/-SD) for DBM and control defects, respectively, were: defect height, 4.8+/-0.2 mm and 4.4+/-0.2 mm; bone regeneration/DBM implant height, 4.0+/-1.3 mm and 1.2+/-0.6 mm; cementum regeneration height, 1.4+/-0.4 mm and 0.7+/-0.2 mm; root resorption, 0.5+/-0.3 mm and 1.2+/-0.3 mm; and ankylosis, 0.5+/-0.2 mm and 0.1+/-0.1 mm without statistically significant differences between experimental conditions (N=3). Within the limitations of this study, the histologic observations suggest that surgical implantation of allogenic, freeze-dried DBM cortical strip implants may have a potential to support cementum regeneration, possibly by providing conditions for guided tissue regeneration, however, alveolar regeneration appears unpredictable.

Enamel matrix derivative (EMDOGAIN) in the treatment of intrabony periodontal defects

The aim of the present clinical trial was to compare the long-term effect of EMDOGAIN treatment as an adjunct to modified widman flap (MWF) surgery with the effect of MWF and placebo treatment. The investigation was a placebo-controlled, randomized multicenter trial involving 33 subjects with 34 paired test and control sites. The protocol required 2 interproximal sites, appropriately separated, in the same jaw with probing pocket depths > or = 6 mm and an associated intrabony defect with a depth of > or = 4 mm and a width of > or = 2 mm as measured on a radiograph. Only predominantly 1- and 2-wall defects were included. Clinical attachment gain and radiographic bone gain were used as primary outcome variables. Assessments were made at baseline, 8, 16 and 36 months. Mean values for clinical attachment level gain in test and control sites at 8 months were 2.1 mm and 1.5 mm, respectively; at 16 months, 2.3 mm and 1.7 mm, respectively; and at 36 months 2.2 mm and 1.7 mm, respectively; and the differences were statistically significantly different at each time point (p < 0.01). The radiographic bone level continued to increase over the 36 months at the EMDOGAIN-treated sites, while it remained close to the baseline level at the control sites. The statistically significant (p < 0.001) radiographic bone gain at 36 months of 2.6 mm at EMDOGAIN-treated sites corresponded to 36% gain of initial bone loss or 66% defect fill. The present trial has demonstrated that topical application of EMDOGAIN onto diseased root surfaces associated with intrabony defects during MWF periodontal surgery will promote an increased gain of radiographic bone and clinical attachment compared to control (placebo application) surgery in the same patient. There was no evidence to indicate any clinical adverse effects from application of EMDOGAIN conjunction with periodontal surgery.

The influence of endodontic treatment upon periodontal wound healing

The interrelationship between periodontal and endodontic disease has aroused much speculation, confusion, and controversy. Pulpal and periodontal problems are responsible for more than 50% of tooth mortality today. Diagnosis is often difficult since these diseases have been studied primarily as separate entities. The toxic substances of the pulp may initiate periodontal defects through canal ramifications and patent dentinal tubules, thus impairing wound healing in regenerative procedures. Although no studies exist addressing the direct effect of pulpal infection on the outcome of guided tissue regeneration (GTR) procedures, several studies do indicate that pulpal status may play a significant role toward the end results of GTR. This review article discusses the potential influence of endodontic treatment on the long-term outcomes of GTR. Potential pathways between the pulp and periodontal ligament, which may be responsible for the failure of the regeneration of new periodontal attachment apparatus, are explored. Examination and review of the clinical and research findings in the literature relating to perio-endo lesions are made to demonstrate that a negative influence may exist between GTR outcomes and the status of the pulp.

A clinical evaluation of guided tissue regeneration with a bioabsorbable matrix membrane combined with an allograft bone graft. A series of case reports

THE PURPOSE OF THIS STUDY was to evaluate the clinical effectiveness of a surgical technique in treating periodontal defects. The technique combined tetracycline treatment of a root planed root, grafting of the osseous defect with a demineralized freeze-dried bone allograft combined with tetracycline and the placement of a bioabsorbable matrix membrane, made of polylactic acid softened with citric acid ester. Thirty defects were treated in 27 patients. Statistically significant changes, as a result of the surgical procedure, were observed in marginal recession (mean: 0.5 mm), probing depth reductions (mean: 5.7 mm), and attachment level gain (mean: 5.2 mm). No statistically significant difference existed between the results in the furcation and non-furcation groups. The defects with probing depths > or = 10 mm had a greater mean probing depth reduction (7.4 mm) and mean attachment level improvement (7.2 mm) than the defects with < 10 mm probing depths (probing depth reduction 4.5 mm and attachment level gain 3.9 mm). The proposed surgical procedure seemed to be an effective method to treat periodontal defects.

Overview of clinical trials on periodontal regeneration

Periodontal regeneration means healing after periodontal surgery that results in the restoration of the tooth-supporting tissues; namely, cementum, alveolar bone, and periodontal ligament. The response of the periodontium to conventional periodontal flap surgery is primarily repair. Regenerative flap procedures involve modifications intended to alter variables in the normal wound healing response to shift the outcome from repair to regeneration. Technical manipulations, devices, pharmacological agents, and biologicals have been used to obtain regeneration. Evaluation of periodontal therapy is done by clinical and histological assessments. Human clinical trials depend on probing, re-entry, and radiographic measurements which cannot distinguish between periodontal repair and regeneration. Histological studies are difficult in humans because they require the retrieval of tissue blocks containing the teeth and their surrounding tissues, and for this reason these studies have largely been done in animal models; however, the use of animal models creates problems of interpretation when applying the information to the human. There are other fundamental problems related to assessment of new methods of periodontal regeneration. Ideally, periodontal regeneration is attempted after resolving the periodontitis that produced the loss of periodontal support. Does the type of periodontal disease affect the outcome? If it does, then separate clinical trials would be indicated to manage defects produced by different diseases. Furthermore, certain types of periodontal defects apparently respond better than others (for example, intrabony defects versus suprabony defects). Does each type of defect require a separate trial? Do subjects respond differently and, if so, how should this be factored into selection of the study population and sample size? There appear to be more questions than answers concerning the design of clinical trials for periodontal regeneration. This is not surprising since regeneration has been possible for only a few years, is apparently unpredictable, and the origin and nature of the new tissue are poorly understood. These factors make it important that the design of clinical trials be openly and thoroughly discussed so that practical solutions are forthcoming.

Outcome variables for the study of periodontal regeneration

The most reliable outcome variable for assessing periodontal regeneration is human histology; however, the morbidity associated with this technique makes it feasible only in isolated case studies designed to prove that a drug, device, or technique is capable of regenerating the lost periodontium including bone, cementum, and functionally oriented periodontal ligament. In the absence of this genuine variable, other "surrogate" variables must be used. Of these, measurement of new bone is the primary alternative. Direct bone measurements, including linear and volumetric assessment, are by far the best tools; however, the need for a second surgical procedure is a definite drawback of this technique. To overcome this problem, other outcomes have been employed: sounding bone measurements is a less invasive method, albeit it is also less accurate. Another tool that has been tested extensively is radiographic analysis. Conventional radiography is not useful in most regenerative trails where minimal or no crestal changes occur. The use of standardized radiographs and image processing techniques to measure alveolar bone changes has not significantly enhanced the applicability of this method. Digital subtraction radiography (DSR) offers some improvement over previous techniques; however, the correlation between the magnitude of clinical bone changes and changes in the digital image is yet to be substantiated. Other variables have been successfully used in regenerative studies. These include clinical attachment level changes, change in probing depth, and gingival recession. The information derived from these variables, especially attachment level changes, supplement and substantiate the direct bone measurements. Other variables that may be monitored are those associated with plaque formation, periodontal pathogens and gingival inflammation; while not direct measures of regeneration, these variables are likely to affect future prognosis and treatment stability. In summary, direct bone measurements are the most ideal surrogate outcome variable, although clinical attachment level measurements are commonly used in large-scale regenerative clinical trials. Clinical response may be assessed at different time intervals; however, the endpoint measurements for regenerative studies should be taken at least 12-months postoperatively.

Periodontal healing following reconstructive surgery: effect of guided tissue regeneration

Clinical healing following guided tissue regeneration (GTR) in deep intrabony pockets was compared to healing following gingival flap surgery alone (GFS). 15 patients received the GTR treatment including an expanded polytetrafluoroethylene membrane. 13 other patients received the control treatment GFS. A postsurgery protocol emphasizing wound stability and infection control was used. Treatment effects were evaluated 6 months postsurgery. Mean pre-surgery probing depth for the GTR and control treatments was 7.5 +/- 1.0 and 7.7 +/- 1.5 mm, respectively. Significant probing depth reduction (3.8 +/- 1.2 and 2.9 +/- 1.1 mm), attachment level improvement (2.4 +/- 2.1 and 2.2 +/- 1.2 mm) and bone fill (2.0 +/- 2.0 and 2.4 +/- 0.9 mm) followed the GTR and control protocols, respectively (p < 0.01). Significant differences between GTR and control treatments were observed in probing depth reduction (p < 0.01) and in gingival recession increase (1.7 +/- 1.5 and 0.7 +/- 0.9 mm, respectively; p < 0.05). The results suggest that GTR procedures compared to GFS have similar clinical potential in intrabony pockets, under the present protocol.

Periodontal regeneration around natural teeth

1. Evidence is conclusive (Table 2) that periodontal regeneration in humans is possible following the use of bone grafts, guided tissue regeneration procedures, both without and in combination with bone grafts, and root demineralization procedures. 2. Clinically guided tissue regeneration procedures have demonstrated significant positive clinical change beyond that achieved with debridement alone in treating mandibular and maxillary (buccal only) Class II furcations. Similar data exist for intraosseous defects. Evidence suggests that the use of bone grafts or GTR procedures produce equal clinical benefit in treating intraosseous defects. Further research is necessary to evaluate GTR procedures compared to, or combined with, bone grafts in treating intraosseous defects. 3. Although there are some data suggesting hopeful results in Class II furcations, the clinical advantage of procedures combining present regenerative techniques remains to be demonstrated. Additional randomized controlled trials with sufficient power are needed to demonstrate the potential usefulness of these techniques. 4. Outcomes following regenerative attempts remain somewhat variable with differences in results between studies and individual subjects. Some of this variability is likely patient related in terms of compliance with plaque control and maintenance procedures, as well as personal habits; e.g., smoking. Variations in the defects selected for study may also affect predictability of outcomes along with other factors. 5. There is evidence to suggest that present regenerative techniques lead to significant amounts of regeneration at localized sites on specific teeth. However, if complete regeneration is to become a reality, additional stimuli to enhance the regenerative process are likely needed. Perhaps this will be accomplished in the future, with combined procedures that include appropriate polypeptide growth factors or tissue factors to provide additional stimulus.

Ability of commercial demineralized freeze-dried bone allograft to induce new bone formation

Demineralized freeze-dried bone allograft (DFDBA) has been used extensively in periodontal therapy. The rationale for use of DFDBA includes the fact that proteins capable of inducing new bone; i.e., bone morphogenetic proteins, can be isolated from bone grafts. Commercial bone banks have provided DFDBA to the dental practitioner for many years; however, these organizations have not verified the osteoinductive capacity of their DFDBA preparations. The aim of this study was to determine the ability of commercial DFDBA preparations to induce new bone formation. DFDBA with particle sizes ranging from 200 to 500 microns was received from six bone banks using various bone production methods. Different lots of DFDBA from the same tissue bank were sometimes available. A total of 14 lots were examined. The surface area of bone particles in each sample was measured morphometrically and the pH of a solution containing the particles after suspension in distilled water determined. Samples from each DFDBA lot were implanted intramuscularly (10 mg) or subcutaneously (20 mg) into three different animals and tissue biopsies harvested after 4 weeks. One sample from each tissue bank was implanted and harvested after 8 weeks. At harvest, each area where DFDBA had been implanted was excised and examined by light microscopy. The ability of DFDBA to produce new bone was evaluated and the amount of residual bone particles measured. The results show that bone particles from all tissue banks had a variety of shapes and sizes, both before implantation and after 1 or 2 months of implantation. The pH of particle suspensions also varied between batches, as well as between tissue banks. None of the DFDBA induced new bone formation when implanted subcutaneously. Intramuscular implants from three banks induced new bone formation after 1 and 2 months. DFDBA from two banks caused new bone formation only after 2 months. However, DFDBA from one bank did not induce new bone at all. Particle size before implantation correlated with particle size after implantation. However, particle size did not correlate with ability to induce bone. The results show that commercial DFDBA differs in both size and ability to induce new bone formation, but that the two are not related. The study also indicates that wide variation in commercial bone bank preparations of DFDBA exist and that ability to induce new bone formation also varies widely. Furthermore, the results suggest that methods or assays for evaluating the ability of DFDBA to induce new bone should be developed and standardized.

Histologic evaluation of human extraction sockets treated with demineralized freeze-dried bone allograft (DFDBA) and cell occlusive membrane

This study evaluated new bone formation in human extraction sockets treated with demineralized freeze-dried bone allografts (DFDBA) and celloc occlusive membranes. Hard tissue biopsies of 7 sites in 6 patients were obtained 14 weeks to 13 months following extraction and grafting. Histologic analysis revealed that individual particles of DFDBA were discernible up to 13 months in situ. In all samples, all particles of DFDBA were well incorporated within new bone, which exhibited osteocyte-containing lacunae. Distinct cement lines clearly demarcated the DFDBA particles from the surrounding, intimately-apposed woven and lamellar bone. The marrow demonstrated a mild degree of fibrosis without signs of inflammatory reaction. There was also a notable lack of fibrous encapsulation of the allograft, and little osteoclasis was observed. Our findings demonstrate that commercially available DFDBA has the potential to function physically as a nidus for appositional new bone growth in alveolar sockets following tooth extraction. Further investigations of the biological activity of DFDBA in situ are warranted.

Human histologic evaluation of HTR polymer and freeze-dried bone allograft. A case report

This case report compares the results of placement of HTR (Hard Tissue Replacement Synthetic Bone) and freeze-dried bone allograft (FDBA) in the same patient. 2 notches were made in each of 6 teeth, 1 at the gingival margin and the other at the most apical level of calculus. Soft tissue responses with both materials included probing depth reduction, gingival shrinkage and gain in clinical attachment. Histological sections of block extraction sites 30 months after placement of either material showed no signs of new attachment. Little or no inflammation was present with both materials. There was also an absence of all FDBA particles which assumes complete resorption of this material prior to 30 months. Gingival shrinkage resulted in the exposure of the gingival and calculus notch in all FDBA treated sites. Gingival epithelium was found adjacent to the gingival notch in all HTR treated sites. The calculus notch in HTR treated sites was lined by junctional epithelium with connective tissue and bone opposing the adhesion. HTR particles were present and surrounded by connective tissue or bone. HTR appears to serve as a scaffold for new bone formation when in close contact with alveolar bone.

Evaluation of guided tissue regeneration in interproximal defects. (II). Membrane and bone versus membrane alone

This study clinically evaluates the use of expanded polytetrafluoroethylene (ePTFE) membranes with or without the addition of decalcified freezedried bone allograft (DFDBA) in the treatment of interproximal intraosseous defects. 25 patients (26 paired defects) diagnosed with advanced periodontitis and having at least 2 bilateral interproximal probing depths of > or = 6 mm participated in the study. After the hygiene phase, measurements were made to determine soft tissue recession, pocket depth, and clinical attachment levels. Defects from each pair were randomly treated with either ePTFE alone (control), or ePTFE+DFDBA (experimental). Measurements were made during the surgery to determine crestal resorption, defect resolution and defect fill. Membranes were removed at 4 to 6 weeks. At 6 months, the soft and hard tissue measurements (surgical reentry) were repeated. Both groups showed statistically significant improvement when compared to baseline (p < 0.001), but no difference was determined between groups. Control sites showed a 50% bone fill and experimental sites had 54% bone fill. The defect resolution changes were also similar between control and experimental groups, respectively (80%, 74%). For this short-term study, it was concluded that either technique was beneficial for the treatment of intraosseous defects. Other studies are needed to assess the long-term stability of the improvements rendered by these treatments.

Bone allografts in periodontal therapy

Bone allografts as used in dentistry have a 20-year history of safety and efficacy. Case reports and controlled clinical trials have shown the potential of both mineralized and decalcified cortical freeze-dried bone allograft to reconstruct the bone defects caused by periodontitis. Histomorphometric analysis of human biopsies following grafts of decalcified freeze-dried bone allograft have shown the ability of decalcified freeze-dried bone allograft to promote regeneration of new bone, cementum, and periodontal ligament on a tooth root surface previously exposed to bacterial plaque. The addition of mineralized freeze-dried bone allograft and decalcified freeze-dried bone allograft to the guided tissue and guided bone regeneration procedures have significantly enhanced results, especially in large osseous lesions.

Periradicular healing in response to Diaket root-end filling material with and without tricalcium phosphate

The healing of the periradicular tissues was evaluated when the polyvinyl resin Diaket with and without tricalcium phosphate was used as surgical root-end filling material. Non-surgical root canal treatment was performed on 56 mandibular premolar roots in mongrel dogs. Following root-end resection, root-end cavity preparations were filled with Diaket, the comparative material, or Diaket in combination with tricalcium phosphate, the experimental material. Postsurgically, healing of the tissues adjacent to the filling materials and in the surrounding surgical site were evaluated at 30 and 60 days. There was virtually no statistically significant difference between the experimental and comparative group at or within the 30- or 60-day period with regard to inflammation, connective tissue formation, root-end encapsulation, cementum formation, or bone apposition. Findings suggest that cementogenesis occurred over both materials. The overall healing of the periradicular tissues was favourable.

The impact of new technologies to diagnose and treat periodontal disease. A look to the future

The last 25 years have brought unprecedented advances to our understanding of periodontal disease. Consider that in 1970 periodontitis was believed to effect most individuals over the age of 35 years, to progress steadily in an individual once initiated until teeth were lost, to be the primary cause of tooth loss in adults, to be caused by the bacterial mass accumulating on the tooth surface and subgingivally, and to involve the host in some fashion or another. In the 25 years since then, impressive research advances in the epidemiology of periodontal disease, the specific bacterial etiology of periodontal disease and the immunoinflammatory mediators of periodontal tissue destruction have greatly altered our view of periodontal disease. Thus, given these research advances in the understanding of periodontitis, what may the future hold for improved diagnosis and treatment of periodontal disease? Impressive research into new ways to diagnose the periodontal diseases is well underway. Investigators are seeking new ways to diagnose an individual's degree of risk for periodontal disease initiation, susceptibility to disease progression, level of disease "activity" and the likely response to treatment and recurrence of active disease. New diagnostic tests should greatly advance our ability to more accurately and specifically diagnose periodontal disease. The future also looks promising for new treatment strategies to slow or arrest periodontal disease progression. The bacterial specificity of periodontal disease etiology revealed since 1970 has logically led to the use of antibiotics in periodontitis treatment. In the late 1980s the concept of locally delivering antibiotics to the periodontal pocket was introduced, and subsequent clinical trials have indicated that it is possible to reduce pocket depth and inflammation with tetracycline locally delivered to the periodontal pocket. Likely, we have barely scratched the surface in studying the efficacy of locally delivery antimicrobial agents to alter the progression of periodontal disease. As new agents are developed and better delivery systems to the periodontal pocket are developed, the future should see a variety of antimicrobial agents available which can slow periodontal disease progression. The future also holds promise for slowing periodontal disease progression by blocking inflammatory pathways important in periodontal tissue destruction. Clinical trials of flubiprofen, naproxen and ketoprofen indicate that it is possible to slow periodontal disease progression with non-steroidal anti-inflammatory drugs which inhibit one destructive pathway. In addition, data from animal models indicate that chemically modified tetracycline as an inhibitor of collagenase can slow disease progression in animals. Again, we have likely only just begun to explore the wide range of molecular mediators of tissue destruction which may be targeted for blocking and thereby slow or arrest periodontal disease progression. Last, research into regenerating periodontal structures lost as a result of disease has had a noteworthy record of progress in the past 25 years. Techniques that utilize bone grafts, root treatments, tissue guiding membranes or polypeptide growth factors have ably indicated that it is possible to regenerate new attachment structures in humans. As investigators continue to unravel the mysteries of the embryonic development of the periodontium, the ability to predictably regenerate lost periodontal attachment structures holds great promise for the future.

Healing response to anorganic bone implantation in periodontal intrabony defects in dogs. Part I. Bone regeneration. A microradiographic study

The purpose of the present study was to explore the regenerative potential of anorganic bone plus collagen (AB-C) in experimental intrabony defects. Eight healthy female beagle dogs, 3 to 4 years old and weighing 15 to 16 kilos, were used. After extraction of the mandibular third premolars (P3), surgical defects were created and inflammation induced by placement of cotton and steel braids. Eight weeks later, the braids were removed. The experimental lesions thus obtained were either treated by plain flap curettage (group 1: control) or were, in addition, implanted with AB-C (group 2: experimental). Blocks of AB-C alone were observed by scanning electron microscopy (SEM). The results show that the surface of the particles have the characteristics of a bone tissue. These particles are gathered together with a fibrillar network. Six, 18, and 36 weeks postoperative (PO), non-decalcified specimens from both groups were examined histologically by contact microradiography. In group 1, no significant bone regeneration was observed at 6, 18, or 36 weeks PO. In group 2, trabeculae undergoing mineralization and circumscribing dense particles above the reference notch were seen at 6 weeks PO; 18 and 36 week specimens showed significant bone regeneration with more or less dense remaining particles. The periodontal ligament space was always clear and the only signs of ankylosis noticed were deep in the notch on one 18 week group 2 specimen and on one 36 week group 1 specimen.

Fate of demineralized freeze-dried bone allografts in human intrabony defects

Demineralized freeze-dried bone (DFDBA) is the most widely used allograft in periodontics. Little information exists, however, on the fate of DFDBA matrix or on the effects of residual particles within grafted defects. The purpose of this study was to histologically examine the fate of DFDBA used for regeneration in intrabony defects. A secondary objective was to compare the amount of new attachment apparatus formation, including component tissues, in relation to the presence or absence of residual graft material. Histologic data were obtained from earlier studies in which intrabony defects grafted with DFDBA were removed at 6 months en bloc and submitted for histologic examination. Histologic sections (1,120) from 12 patients with 32 grafted defects revealed that 72% of the grafted defects exhibited residual DFDBA particles. When present, DFDBA appeared amalgamated within the new viable bone. Data from 5 patients with 14 grafted sites permitted a within-subject comparison of the amount of regeneration in relation to the presence or absence of residual graft material. Defects harboring residual graft particles exhibited significantly greater amounts of new attachment apparatus formation (1.72 mm vs. 0.20 mm), including new bone (2.33 mm vs. 0.23 mm), cementum (1.74 mm vs. 0.23 mm), and associated periodontal ligament than sites without evidence of graft matrix (P < or = 0.05). No apparent differences were seen in the nature of the new attachment apparatus or component tissues, other than in amount of formation. Inflammation and graft containment appear to be important factors influencing the fate of DFDBA and the regenerative response.

Periodontal repair in dogs: evaluation of the natural disease model

Animal models are frequently consulted for histometric analysis of periodontal reconstructive therapy. Such models include surgical, periodontitis-simulating and natural disease defects in canines or non-human primates. Our studies suggest that homogeneity in defect height is critical for sensitivity of surgical and periodontitis-simulating supraalevolar defect models in discriminating treatment effects. We herein evaluate this model aspect for natural disease defects. Buccal-lingual histologic sections from the 2nd, 3rd, and 4th mandibular premolar teeth (P2, P3, P4) from 6 aged beagle dogs with advanced natural periodontal disease were used. Defect heights from the reduced alveolar bone to the cemento-enamel junction were recorded in central step-serial sections at the buccal and lingual surfaces of the mesial and distal roots for the premolar teeth. Mean defect height, standard deviation and coefficient of variation were calculated for tooth types and jaw quadrants, separately, and for all teeth. Confidence intervals were calculated for teeth in left and right jaw quadrants. Mean defect height and standard deviation for left and right jaw quadrants was 3.6 +/- 0.9 and 3.3 +/- 0.6 mm for P2, 3.3 +/- 0.9 and 2.3 +/- 0.9 mm for P3, and 3.3 +/- 1.0 and 4.5 +/- 1.6 mm for P4, respectively. Coefficient of variation for defects for left and right jaw quadrants was 26 and 40%, respectively. Using confidence intervals for mean differences between jaw quadrants, it was determined that a mean treatment effect may be as large as 0.8, 1.1 and 1.9 mm for P2, P3 and P4, respectively, before being detected as statistically significant (p < or = 0.05; N = 6).(ABSTRACT TRUNCATED AT 250 WORDS)

Periodontal regeneration: potential role of bone morphogenetic proteins

Initiation of osteogenesis and cementogenesis is a problem central to periodontal regeneration. A major advance in the understanding of bone formation has been the identification of an entirely new family of protein initiators, the bone morphogenetic proteins, that regulate cartilage and bone differentiation in vivo. The purification, genetic cloning and expression of recombinant human bone morphogenetic proteins (BMPs) have laid the foundation for the cellular and molecular dissection of bone development and regeneration. The striking evolutionary conservation of the BMP genes indicates that they are critical in the normal development and function of animals. In addition to postfetal osteogenesis, the BMPs may play multiple roles in embryonic development and organogenesis, including skeletogenesis and the development of craniofacial and dental tissues. The availability of recombinant human BMPs provides several challenges and opportunities to gain insights into the mechanisms regulating the regeneration of bone and cementum for optimal outcome in the periodontal patient.