Comparison of tricalcium phosphate and frozen allogenic bone implants in man

Effectiveness of beta-tricalcium phosphate in comparison with other materials in treating periodontal infra-bony defects around natural teeth: a systematic review and meta-analysis

BACKGROUND

Beta-tricalcium phosphate in regenerative surgery has shown promising results in terms of bone gain and new vital bone formation; however, several studies have contradicted this finding. The aim of this study was to evaluate the effectiveness of beta-tricalcium phosphate compared to other grafting materials in the regeneration of periodontal infra-bony defects.

METHODS

Electronic database (Cochrane, MEDLINE, PubMed, Embase, Science Citation Index Expanded) and manual searches for related data were performed up until March 2020. The outcomes were pocket depth reduction, clinical attachment level gain, and amount of bone fill.

RESULTS

Five studies were selected based on the inclusion criteria. Bone regeneration with beta-tricalcium phosphate was observed to be superior to that with debridement alone but showed comparable results to other bone graft materials in terms of pocket depth reduction, clinical attachment level gain, and bone fill. Regenerative procedures for periodontal infra-bony defects that used beta-tricalcium phosphate in combination with other growth factors yielded superior outcomes. The meta-analysis revealed that for cases with two-wall defects, the use of beta-tricalcium phosphate yielded statistically significant differences in pocket depth reduction and clinical attachment level gain, but not in bone fill.

CONCLUSIONS

Beta-tricalcium phosphate appears to be a promising material for use in periodontal infra-bony defect regeneration around natural teeth. However, randomized clinical trials with larger sample sizes and more controlled study designs are needed to support these findings.

Evaluation of the relative efficacy of autologous platelet-rich fibrin membrane in combination with β-tricalcium phosphate (Septodont- resorbable tissue replacement)™ alloplast versus β-TCP alloplast alone in the treatment of grade II furcation defects

Introduction:

Platelet-rich fibrin (PRF) is considered as the second-generation platelet concentrate, contains combined properties of fibrin, platelets, leukocytes, growth factors, and cytokines that make it as healing biomaterial with incredible potential for hard tissue and soft tissue regeneration. The present study was aimed to evaluate the effectiveness of PRF with β-tricalcium phosphate (β-TCP) graft (R. T. R) and compare it with β-TCP allograft alone in the treatment of mandibular Grade II furcation defects.

Material and Methods:

A total of 20 mandibular Grade II furcation defects sites were assigned in the study and treated with either β-TCP alone (Group I) or β-TCP with PRF membrane (Group II). The clinical parameters analyzed were probing pocket depth (PPD), clinical attachment level (CAL), gingival recession (GR), horizontal defect depth (HDD), and vertical defect depth (VDD), recorded baseline and at 6 months reentry.

Results:

At 6 months, both groups showed statistically significant results for all parameters from their baseline value, although intergroup changes were statistically insignificant. In Group I, gain in CAL was 2.80 ± 1.40 and in Group II it was 3.00 ± 1.44. Bone fill in Group I was VDD (3.50 ± 2.12) and HDD (3.70 ± 0.67), whereas Group II showed VDD (3.70 ± 1.57) and HDD (4.0 ± 0.88), respectively. PPD reduction was higher in Group I (3.50 ± 2.27) than Group II (2.80 ± 1.93). At reentry GR was established, Group I showed higher GR (0.70 ± 0.67) and Group II (0.40 ± 0.52).

Conclusions:

Significant improvement was found in both groups, but the combination of PRF with β-TCP allograft led to more favorable improvement in the management of Grade II furcation defect except PPD.

Bone Replacement Materials and Techniques Used for Achieving Vertical Alveolar Bone Augmentation

Alveolar bone augmentation in vertical dimension remains the holy grail of periodontal tissue engineering. Successful dental implant placement for restoration of edentulous sites depends on the quality and quantity of alveolar bone available in all spatial dimensions. There are several surgical techniques used alone or in combination with natural or synthetic graft materials to achieve vertical alveolar bone augmentation. While continuously improving surgical techniques combined with the use of auto- or allografts provide the most predictable clinical outcomes, their success often depends on the status of recipient tissues. The morbidity associated with donor sites for auto-grafts makes these techniques less appealing to both patients and clinicians. New developments in material sciences offer a range of synthetic replacements for natural grafts to address the shortcoming of a second surgical site and relatively high resorption rates. This narrative review focuses on existing techniques, natural tissues and synthetic biomaterials commonly used to achieve vertical bone height gain in order to successfully restore edentulous ridges with implant-supported prostheses.

Cranial suture-like gap and bone regeneration after transplantation of cryopreserved MSCs by use of a programmed freezer with magnetic field in rats

Mesenchymal stem cells (MSCs) can be used for regeneration of various organs and tissues. A previous study revealed that cryopreserved MSCs, which were frozen by a programmed freezer with a magnetic field (Cells Alive System: CAS) and cryopreserved for 7 days in a -150°C deep freezer, can maintain high survival and proliferation rates while retaining both adipogenic and osteogenic differentiation abilities. The purpose of this study was to examine MSC viability and tissue regenerative ability after long-term cryopreservation using a CAS freezer. MSCs were isolated from rat femora bone marrow and cryopreserved in a -150°C deep freezer (CAS group) or directly cryopreserved in a deep freezer (Direct group). After 3 years, the cells were thawed and the number of viable cells was counted. Cell proliferation was also examined after 14 days in culture. For histological examination, forty 4-week-old Fischer 344 male rats received bone and sagittal suture defects with a diameter of 6.0mm, and MSCs (CAS or Direct group) cryopreserved for 1 year were grafted with membranes. Non-cryopreserved MSCs (Control group) were transplanted to an additional twenty rats. The rats were sacrificed at 4, 8, 16, and 24 weeks after surgery. The parietal bones, including the sagittal suture, were observed under a light microscope and the extent of bone regeneration was measured. Our results indicate that MSCs survival and proliferation rates were significantly higher in the CAS group than in the Direct group. In the Control and CAS groups, a large amount of new bone formation and a suture-like gap was identified 24 weeks after transplantation, whereas only a small amount of new bone formation was observed in the Direct group. These results suggest that the CAS freezer is amenable to long-term cryopreservation of MSCs, which can be applied to the regeneration of various tissues, including bone tissue with suture-like gap formation.

Evaluation of relative efficacy of β-tricalcium phosphate with and without type I resorbable collagen membrane in periodontal infrabony defects: a clinical and radiographic study

BACKGROUND AND OBJECTIVES

To compare clinically and radiographically, the regenerative potential of a β-tricalcium phosphate bone graft, Cerasorb(®) with and without a bioresorbable type I collagen membrane, BioMend Extend™, in treating periodontal infrabony osseous defects.

MATERIALS AND METHODS

A total of 20 sites from 10 patients showing bilateral infrabony defects were selected and selected sites were randomly divided into experimental site A (Cerasorb(®)) and experimental site B (Cerasorb(®) and BioMend Extend™) by using split mouth design. The clinical parameters like plaque index, gingival index, probing pocket depth, clinical attachment level and gingival recession were recorded at baseline, 6 weeks, 3, 6 and 9 months. Radiographic evaluation (Linear CADIA) at 6 and 9 months; and intrasurgical measurements at baseline and 9 months were carried out to evaluate the defect fill, change in alveolar crest height and defect resolution.

RESULTS

Significant reduction in all clinical parameters was observed in both the groups. On comparison no statistical significance was observed between the two groups. Radiographically, in site A there was significant defect fill of 78.4 and 97.2% at 6 and 9 months respectively. Whereas in site B reduction was 78.4 and 97.2% at 6 and 9 months respectively. After surgical re-entry, there was significant defect fill of 89.2 and 74% in both groups.

INTERPRETATION AND CONCLUSION

Individually both the graft and membrane have shown promising results in the management of periodontal intrabony defects. But the added benefit by combining Cerasorb(®) with BioMend Extend™ was not observed statistically in both clinical radiographic findings.

Effect of platelet-rich plasma on the healing of intrabony defects treated with Beta tricalcium phosphate and expanded polytetrafluoroethylene membranes

BACKGROUND

Regenerative periodontal therapy using platelet-rich plasma (PRP) and different types of bone substitutes with or without guided tissue regeneration (GTR) has been proposed as a modality to enhance the outcome of regenerative surgery. However, there are limited data from controlled clinical studies evaluating the effect of PRP on the healing of deep intrabony defects treated with a combination of bone substitutes and GTR. The aim of this study was to clinically evaluate the effect of PRP on the healing of deep intrabony defects treated with beta tricalcium phosphate (beta-TCP) and GTR by means of a non-bioresorbable expanded polytetrafluoroethylene membrane.

METHODS

Twenty-eight subjects with advanced chronic periodontal disease and displaying one intrabony defect were treated randomly with a combination of PRP + beta-TCP + GTR or beta-TCP + GTR. Plaque index, gingival index, bleeding on probing, probing depth (PD), gingival recession, and clinical attachment level (CAL) were evaluated at baseline and at 1 year after treatment. CAL was the primary outcome variable.

RESULTS

No differences in any of the investigated parameters were observed at baseline between the two groups. Healing was uneventful in all subjects. At 1 year after therapy, the sites treated with PRP + beta-TCP + GTR showed a reduction in mean PD from 9.1 +/- 0.6 mm to 3.3 +/- 0.5 mm (P <0.001) and a change in mean CAL from 10.1 +/- 1.3 mm to 5.7 +/- 1.1 mm (P <0.001). In the group treated with beta-TCP + GTR, mean PD was reduced from 9.0 +/- 0.8 mm to 3.6 +/- 0.9 mm (P <0.001), and the mean CAL changed from 9.9 +/- 1.0 mm to 5.9 +/- 1.2 mm (P <0.001). In both groups, all sites gained > or =3 mm of CAL. CAL gains > or =4 mm were noted in 86% (12 of 14 defects) of the cases treated with PRP + beta-TCP + GTR and in 79% (11 of 14 defects) of those treated with beta-TCP + GTR. No statistically significant differences in any of the investigated parameters were observed between the two groups at the 1-year reevaluation.

CONCLUSION

At 1 year after surgery, both therapies resulted in significant PD reductions and CAL gains.

New composite endpoints to assess efficacy in periodontal therapy clinical trials

BACKGROUND

Clinical attachment level (CAL) and bone height (radiographic or clinical) are two well-accepted endpoint measures for periodontal clinical trials; however, neither one has been shown to be more predictive of long-term success than the other. We propose using a composite endpoint analysis combining clinical and radiological parameters to assess the beneficial effects on both hard and soft tissues following periodontal therapy using a single statistical test. To address this need, two composite endpoint alternatives are offered as a yardstick for clinical success; each includes the improvement in CAL and either improvement in linear bone growth or percent bone fill.

METHODS

The data for composite endpoint analyses were derived from a clinical trial evaluating two concentrations of recombinant human platelet-derived growth factor-BB (rhPDGF-BB) with beta-tricalcium phosphate (beta-TCP) compared to beta-TCP plus buffer as follows: group I, beta-TCP + 0.3 mg/ml rhPDGF-BB; group II, beta-TCP + 1.0 mg/ml rhPDGF-BB; and group III, beta-TCP + buffer. The construction of composite endpoints was based on the greatest values for change, accepted by the U.S. Food and Drug Administration (FDA), for clinical attachment level (DeltaCAL), mean change in radiographic linear bone gain (LBG), and mean radiographic percent bone fill (%BF), with the following dual standards defining a successful clinical result: CAL gain > or =2.67 mm and radiographic LBG > or =1.1 mm at 6 months and CAL gain > or =2.67 mm and radiographic %BF > or =14.1% at 6 months.

RESULTS

Group I (beta-TCP + 0.3 mg/ml rhPDGF-BB) demonstrated statistically significant differences from group III (active control) for both composite endpoints. For the CAL/LBG composite endpoint, 61.7% of sites in group I versus 30.4% of sites in group III met the composite endpoint benchmarks (P <0.001). For the CAL/%BF composite endpoint, 70% of sites in group I versus 44.6% of sites in group III met the composite endpoint benchmarks (P = 0.003). A non-significant trend was observed for group II versus group III with 37.9% (P = 0.20) and 55.2% (P = 0.13) of sites meeting the CAL/LBG and CAL/%BF composite endpoints, respectively. These results are further emphasized by findings demonstrating a low correlation between the individual efficacy endpoints (DeltaCAL and %BF; DeltaCAL and LBG) for each of the three treatment groups.

CONCLUSIONS

Composite endpoints are advantageous in periodontal clinical trials where no single efficacy endpoint has been established as the most important. A composite endpoint, combining outcome measures of both hard and soft tissue components of the periodontium, may be preferable for assessing efficacy of periodontal regenerative therapies. Two composite endpoints are offered to meet this need.

Injectable Calcium Phosphate Bone Cement Provides Favorable Space and a Scaffold for Periodontal Regeneration in Dogs

BACKGROUND

An earlier study showed that an injectable calcium phosphate cement (CPC) served as a stable scaffold for bone formation and promoted histocompatible healing of periodontal tissue in dogs. In this study, we evaluated the influence of CPC on regeneration of periodontal defects with experimental periodontitis in dogs.

METHODS

Experimental periodontitis was induced by placing stainless-steel mesh on the mesial side of maxillary canines in six adult, healthy beagle dogs. Subsequently, intrabony defects were resized so as to be standard, and CPC was injected in the experimental bone defects. Non-grafted defects on the contralateral side served as controls. Twelve weeks after surgery, the animals were sacrificed and histologic specimens were prepared. Periodontal tissue healing was evaluated histologically and histometrically.

RESULTS

Healing of periodontal tissues, in terms of bone and cementum formation, was consistently observed in the CPC-applied sites. CPC was partly replaced by new bone. New cementum and periodontal ligament-like tissue were observed between CPC and the root surface. New bone (P <0.05), new cementum (P <0.01), and new connective tissue attachment and adhesion (P <0.05) were significantly enhanced in the experimental sites.

CONCLUSION

Calcium phosphate cement provides stable wound healing and enhanced periodontal regeneration in periodontal defects in dogs with experimental periodontitis.

Platelet-derived growth factor stimulates bone fill and rate of attachment level gain: results of a large multicenter randomized controlled trial

BACKGROUND

Growth factors are generally accepted to be essential mediators of tissue repair via well-established mechanisms of action that include stimulatory effects on angiogenesis and cellular proliferation, ingrowth, differentiation, and matrix biosynthesis. The aim of this study was to evaluate in a large-scale, prospective, blinded, and randomized controlled clinical trial the safety and effectiveness of purified recombinant human platelet-derived growth factor (rhPDGF-BB) mixed with a synthetic beta-tricalcium phosphate (beta-TCP) matrix for the treatment of advanced periodontal osseous defects at 6 months of healing.

METHODS

Eleven clinical centers enrolled 180 subjects, each requiring surgical treatment of a 4 mm or greater intrabony periodontal defect and meeting all inclusion and exclusion criteria. Subjects were randomized into one of three treatment groups: 1) beta-TCP + 0.3 mg/ml rhPDGF-BB in buffer; 2) beta-TCP + 1.0 mg/ml rhPDGF-BB in buffer; and 3) beta-TCP + buffer (active control). Safety data were assessed by the frequency and severity of adverse events. Effectiveness measurements included clinical attachment levels (CAL) and gingival recession (GR) measured clinically and linear bone growth (LBG) and percent bone fill (% BF) as assessed radiographically by an independent centralized radiology review center. The area under the curve (AUC), an assessment of the rate of healing, was also calculated for CAL measurements. The surgeons, clinical and radiographic evaluators, patients, and study sponsor were all masked with respect to treatment groups.

RESULTS

CAL gain was significantly greater at 3 months for group 1 (rhPDGF 0.3 mg/ml) compared to group 3 (beta-TCP + buffer) (3.8 versus 3.3 mm; P = 0.032), although by 6 months, this finding was not statistically significant (P = 0.11). This early acceleration of CAL gain led to group 1 exhibiting a significantly greater rate of CAL gain between baseline and 6 months than group 3 as assessed by the AUC (68.4- versus 60.1-mm weeks; P = 0.033). rhPDGF (0.3 mg/ml)-treated sites also had significantly greater linear bone gain (2.6 versus 0.9 mm, respectively; P < 0.001) and percent defect fill (57% versus 18%, respectively; P < 0.001) than the sites receiving the bone substitute with buffer at 6 months. There was less GR at 3 months in group 1 compared to group 3 (P = 0.04); at 6 months, GR for group 1 remained unchanged, whereas there was a slight gain in gingival height for group 3 resulting in comparable GR. There were no serious adverse events attributable to any of the treatments.

CONCLUSIONS

To our knowledge, this study is the largest prospective, randomized, triple-blinded, and controlled pivotal clinical trial reported to date assessing a putative periodontal regenerative and wound healing therapy. The study demonstrated that the use of rhPDGF-BB was safe and effective in the treatment of periodontal osseous defects. Treatment with rhPDGF-BB stimulated a significant increase in the rate of CAL gain, reduced gingival recession at 3 months post-surgery, and improved bone fill as compared to a beta-TCP bone substitute at 6 months.

Clinical Evaluation of an Enamel Matrix Protein Derivative Combined With Either a Natural Bone Mineral or β-Tricalcium Phosphate

BACKGROUND

The purpose of the present study was to compare the healing of deep intrabony defects following treatment with an enamel matrix protein derivative (EMD) combined with either a natural bone mineral (NBM) or beta-tricalcium phosphate (beta-TCP).

METHODS

Twenty-four patients with advanced periodontal disease, each of whom displayed one intrabony defect, were randomly treated with a combination of either EMD + NBM or EMD + beta-TCP. Clinical evaluation was performed at baseline and 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 sites treated with EMD + NBM showed a reduction in mean probing depth (PD) from 7.9 +/- 1.0 mm to 3.2 +/- 0.6 mm and a change in mean clinical attachment level (CAL) from 8.8 +/- 1.1 mm to 4.5 +/- 0.6 mm (P < 0.001). In the group treated with EMD + beta-TCP, the mean PD was reduced from 7.8 +/- 1.2 mm to 3.2 +/- 0.9 mm, and the mean CAL changed from 8.8 +/- 1.2 mm to 4.7 +/- 1.2 mm (P < 0.001). In both groups, all sites gained at least 3 mm of CAL. CAL gains of 4 or 5 mm were measured in the majority of the cases (75%), irrespective of treatment modality. No statistically significant differences in terms of PD reductions and CAL gains were observed between the two groups.

CONCLUSION

Within the limits of the present study, both therapies resulted in significant PD reductions and CAL gains 1 year after surgery.

Ultrastructure of bone healing in defects grafted with a copolymer of polylactic/polyglycolic acids

Bone substitutes have been used for the treatment of bone defects. The objective of this study was to ultrastructurally evaluate the healing pattern of bone defects filled with a copolymer of polylactic/polyglycolic acid (FisiograftR) at a time point in which it is expected to be only partially degraded, with the purpose to ultrastructurally analyze how the bone is forming around the grafting material. Three 5-mm-diameter bone defects were created in each tibia from 5 rabbits (average weight 2.5 kg) in which the material was randomly implanted. Animals were sacrificed 30 days after surgery and the 30 bone defects were fixed in 2% glutaraldehyde-2.5% formaldehyde, under microwave irradiation, decalcified in EDTA, embedded in Spurr resin, and examined in a Jeol 1010 TEM. All the bone defects were filled with connective tissue, interspersed with different amounts of the filling material and newly formed bone trabeculae. In areas where the degrading copolymer was present in small amounts, newly formed bone matrix was detected; it was deposited by osteoblast-like cells in close relation to the copolymer. In areas where the degrading copolymer formed accumulates, an amorphous multilayered material was identified between the connective tissue and the copolymer. In summary, the copolymer of PLA/PGA studied appears to be an osteoconductive material when it is used to fill bone defects.

The efficacy of bone replacement grafts in the treatment of periodontal osseous defects. A systematic review

BACKGROUND

Bone replacement grafts (BRG) are widely used in the treatment of periodontal osseous defects; however, the clinical benefits of this therapeutic practice require further clarification through a systematic review of randomized controlled studies.

RATIONALE

The purpose of this systematic review is to access the efficacy of bone replacement grafts in proving demonstrable clinical improvements in periodontal osseous defects compared to surgical debridement alone.

FOCUSED QUESTION

What is the effect of bone replacement grafts compared to other interventions on clinical, radiographic, adverse, and patient-centered outcomes in patients with periodontal osseous defects?

SEARCH PROTOCOL

The computerized bibliographical databases MEDLINE and EMBASE were searched from 1966 and 1974, respectively, to October 2002 for randomized controlled studies in which bone replacement grafts were compared to other surgical interventions in the treatment of periodontal osseous defects. The search strategy included screening of review articles and reference lists of retrieved articles as well as hand searches of selected journals.

INCLUSION CRITERIA

All searches were limited to human studies in English language publications.

EXCLUSION CRITERIA

Non-randomized observational studies (e.g., case reports, case series), publications providing summary statistics without variance estimates or data to permit computation, and studies without BRG intervention alone were excluded.

DATA COLLECTION AND ANALYSIS

The therapeutic endpoints examined included changes in bone level, clinical attachment level, probing depth, gingival recession, and crestal resorption. For purposes of meta-analysis, change in bone level (bone fill) was used as the primary outcome measure, measured upon surgical re-entry or transgingival probing (sounding).

MAIN RESULTS

1. Forty-nine controlled studies met eligibility criteria and provided clinical outcome data on intrabony defects following grafting procedures. 2. Seventeen studies provided clinical outcome data on BRG materials for the treatment of furcation defects.

REVIEWERS' CONCLUSIONS

1. With respect to the treatment of intrabony defects, the results of meta-analysis supported the following conclusions: 1) bone grafts increase bone level, reduce crestal bone loss, increase clinical attachment level, and reduce probing depth compared to open flap debridement (OFD) procedures; 2) No differences in clinical outcome measures emerge between particulate bone allograft and calcium phosphate (hydroxyapatite) ceramic grafts; and 3) bone grafts in combination with barrier membranes increase clinical attachment level and reduce probing depth compared to graft alone. 2. With respect to the treatment of furcation defects, 15 controlled studies provided data on clinical outcomes. Insufficient studies of comparable design were available to submit data to meta-analysis. Nonetheless, outcome data from these studies generally indicated positive clinical benefits with the use of grafts in the treatment of Class II furcations. 3. With respect to histological outcome parameters, 2 randomized controlled studies provide evidence that demineralized freeze-dried bone allograft (DFDBA) supports the formation of a new attachment apparatus in intrabony defects, whereas OFD results in periodontal repair characterized primarily by the formation of a long junctional epithelial attachment. Multiple observational studies provide consistent histological evidence that autogenous and demineralized allogeneic bone grafts support the formation of new attachment. Limited data also suggest that xenogenic bone grafts can support the formation of a new attachment apparatus. In contrast, essentially all available data indicate that alloplastic grafts support periodontal repair rather than regeneration. 4. The results of this systematic review indicate that bone replacement grafts provide demonstrable clinical improvements in periodontal osseous defects compared to surgical debridement alone.

Histocompatible Healing of Periodontal Defects After Application of an Injectable Calcium Phosphate Bone Cement. A Preliminary Study in Dogs

BACKGROUND

A novel injectable, fast setting calcium phosphate cement (CPC) is currently used in orthopedic therapy for bone fractures. This study evaluated the possibility of applying this cement to healing periodontal defects.

METHODS

Fenestrations and 3-walled periodontal defects were surgically created on bilateral first molars and canines in 5 beagle dogs. CPC was applied to the defects on one side of the mandible. Untreated defects on the contralateral side served as controls. CPC was applied to all defects in the maxilla. Twelve weeks after surgery, the animals were sacrificed and decalcified and undecalcified specimens were prepared. Periodontal tissue healing was evaluated histologically and histometrically under a light microscope.

RESULTS

Healing of periodontal tissues in terms of bone and cementum formation was consistently observed in the CPC-applied sites. CPC was partly replaced by new bone. The residual CPC appeared detached from the denuded root surface. New cementum and periodontal ligament-like tissue were observed between the detached CPC and root surface. No unfavorable reaction was noted in the CPC-applied sites. No statistically significant difference was noted in the experimental or control sites under histometric analysis.

CONCLUSIONS

Although there were no statistically significant differences between the 2 treatment groups, histological observation indicated that CPC seemed to act as a scaffold for bone formation and provided histocompatible healing of periodontal tissues in this study. This cement might be applicable to periodontal therapy; however, further investigations are required.

Effects of pretreatment clinical parameters on bioactive glass implantation in intrabony periodontal defects

BACKGROUND

The various methods for regeneration of periodontal tissue that have been developed can be classified into guided tissue regeneration and bone implantation. Since the implantation materials have shown both deficiencies and merits, dentists have begun exploring the bioactive glass first used in plastic surgery. This paper examines the effectiveness of this new material on periodontal intrabony defects.

METHODS

Clinical effects of bioactive glass implantation in intrabony periodontal defects were evaluated 6 months after surgery in 38 intrabony defects from 38 patients with chronic periodontitis. Twenty-one experimental defects received bioactive glass implantation (test group), while 17 control defects were treated with a flap procedure only (control group). The criteria for comparative observation were preoperative and postoperative probing depth (PD), clinical attachment level (CAL), bone probing depth (BPD), and gingival recession.

RESULTS

Reductions in PD were observed in both groups (P<0.01). The reduction in PD was significantly greater in the test group when preoperative PD exceeded 7 mm (P<0.01). Improvements in CAL were also observed in both groups (P<0.01), with the test group showing significantly greater gains (P<0.05). In those cases where preoperative CAL was less than 7 mm, there was no statistically significant difference between the two groups. Reduction in BPD was observed in both groups, with the test group showing significantly greater reduction (P <0.01). There was no significant difference in BPD change, however, when preoperative BPD was < or =7 mm. Significantly greater reduction of BPD in the test group was observed when intrabony defect depth was >4 mm (P <0.05). Significant improvements in PD, CAL, and BPD were noted in the test group when the crestal involvement exceeded 100 degrees. Correlation test between various clinical parameters indicated that greater changes in PD and CAL in the test group were observed when preoperative CAL was large (P<0.001), and greater changes in PD (P<0.05), CAL (P<0.01), and BPD (P<0.05) were noted when preoperative BPD was large. Correlation between crestal involvement and CAL change was noted only in the control group (P<0.01). High correlations were observed between PD changes and CAL changes and between CAL changes and BPD changes in both groups.

CONCLUSIONS

Use of a bone substitute in a flap operation resulted in significantly greater improvements in CAL and BPD over flap operation alone and seemed to have positive effects in postoperative PD, CAL, and BPD in those cases with more severe preoperative CAL and BPD.

Bone and bone substitutes

Bone replacement grafts will play a continuing role in periodontal and other regenerative therapy. Several choices are available to the clinician including autogenous, allogeneic, xenogeneic and a variety of alloplastic materials. Except for fresh autogenous bone, bone replacement graft(s) do not provide the cellular elements necessary for osteogenesis nor can they reliably be considered truly osteoinductive, but instead are mostly osteoconductive, providing a scaffold for bone deposition. Currently, significant decrease in clinical probing depth and gain of clinical attachment have been reported following use of bone replacement grafts when compared to flap debridement surgery alone for periodontal osseous defects. Reported differences among bone replacement grafts (autogenous, allogeneic, xenogeneic, and alloplastic) occur with respect to histological outcomes. Overall, probing depth reduction, attachment level gain and degree of defect fill are similar for all bone replacement grafts.

"In vitro" dissolution of coral in peritoneal or fibroblast cell cultures

Previous studies have shown that in vivo coral resorption involves a biphasic process: First, the edges of the coral block become powdery, then extracellular fluid and phagocytosis contribute to the dissolution of the crystals. The authors examined some types of cells that could be involved in phagocytosis, particularly the ability of both dermal fibroblasts and mouse-resident peritoneal cells to phagocytose and dissolve coral powder "in vitro". Radioactive coral was incubated for 24, 48, or 72 hrs with cells in the presence or absence of cytochalasin B (a phagocytic inhibitor) or chloroquine (a lysosomotropic agent). Furthermore, to specify the role of crystal cell contacts in the solubilization process, they incubated radioactive coral in conditioned media (obtained from two-day human fibroblastic or macrophagic cell culture in the presence or absence of non-radioactive coral) or at a distance from the cells using culture inserts. Measurements of the radioactivity in the different supernatants were performed. Transmission electron microscopy was carried out on the cells cultivated in the presence or absence of radioactive coral. The data suggest that both fibroblasts and macrophages dissolve the coral, and that the intracellular degradation in phagolysosomes is one of the mechanisms explaining coral powder dissolution.

Osteogenic response to hydroxyapatite-fibrin implants in maxillofacial bone defects

Bone formation in hydroxyapatite-fibrin implants has been reported several times. However, available studies refer to experimental animals, or are limited to short periods after implantation. We report the results of histological, histochemical and ultrastructural studies carried out 2.5-8 yr after implantation of non-resorbable, porous hydroxyapatite (HA) and fibrin glue in human maxillofacial bones. Prominent ossification was found in all cases, with the presence of normally structured spongy bone. HA granules were embedded in the calcified bone matrix. They had not elicited inflammatory reactions and did not induce bone resorption. Ossification was preceded by the appearance of alkaline phosphatase activity on fibroblast-like cells, and by the formation of dense collagenous layers, similar to osteoid borders, on the surface of HA granules. The early phases of the calcification process occurred in these borders, with the appearance of calcification nodules adjacent to alkaline phosphatase-positive osteoblast-like cells. A remodeling process similar to that occurring in normal bones was found in the newly formed bone. These results justify the conclusion that HA-fibrin implants lead to the formation of long-lasting bone that does not differ from that of the normal maxillofacial skeleton. Mixing the HA granules with fibrin has the advantage of creating an easily mouldable material which can be adapted to any skeletal surface and stays in place after surgery.

Evaluation of the osteogenic potential of biomaterials implanted in the palatal connective tissue of miniature pigs using undecalcified sections

Calcium phosphate or calcium carbonate biomaterials are widely used as bone substitutes in periodontal surgery. This study evaluates the osteogenic potential of five different alloplastic biomaterials implanted in the connective tissue of the palatal papilla in miniature pigs. A porous hydroxyapatite (PHA), a dense hydroxyapatite (DHA), a semi-porous hydroxyapatite (SPHA), a tricalcium phosphate (TCP) and a calcium carbonate natural coral (NC) were implanted in a tunnel in the palatal papillae of seven miniature pigs. Undecalcified sections were examined histologically at 1, 2, 3, 4, 8, 12 and 24 wk intervals. Resorbable materials (TCP and NC) were totally resorbed by 24 wk. DHA, PHA and HA showed very limited resorption, although there were multinucleated giant cells in contact with PHA and SPHA. There was no histologically detectable bone formation in contact with or near any of the biomaterials tested. However, several particles of NC, and sometimes of PHA, were surrounded by a dense, mineralized matrix. It is concluded that none of these biomaterials, in their presently available forms, has any bone inducing capacity.

Autogenous and allogeneic bone grafts in periodontal therapy

This article is limited to a review of bone autografts and allografts, as used in periodontal therapy. The various graft materials are discussed with respect to case reports, controlled clinical trials, and human histology. Other reviewed areas are wound healing with periodontal bone grafts, tissue banking and freeze-dried bone allografts, and the use of bone grafts in guided tissue regeneration.

HTR polymer grafts in human periodontal osseous defects. I. 6-month clinical results

HTR polymer was evaluated as a grafting material in periodontal osseous defects in 21 adult patients. Following initial preparation and pre-surgical documentation with standardized measurements, radiographs, and photographs, vertical osseous defects were treated with surgical open flap debridement alone (DEBR) or with DEBR plus placement of HTR polymer graft material. Patients were followed with frequent recalls until surgical re-entry at about 6 months for documentation and any needed remedial therapy. Re-entry data show that use of HTR polymer grafts resulted in significantly better mean defect fill of 2.2 mm (60.8%) compared to 1.0 mm (32.2%) with DEBR alone (P less than .001). Other hard tissue findings such as residual defect depth, crestal resorption, and percent defect resolution showed similar clinically superior results with the use of HTR polymer. Soft tissue findings showed significant differences in favor of HTR for decrease in probing depth and gain in clinical attachment. These results are similar to those reported with other graft materials. Over a 6-month period, HTR polymer was found to show promise for the repair of periodontal osseous defects.

Bone formation in tricalcium phosphate-filled periodontal intrabony lesions. Histological observations in humans

The capacity of a tricalcium phosphate (TCP) ceramic to promote bone formation after grafting in intrabony defects was studied in humans. Five biopsies were collected from 4 patients during reentry surgery 16 to 40 months after implantation. They were processed without demineralization for histological examination. In the less mature samples, the grafted material was surrounded by a highly fibrous, highly cellular, and poorly vascularized connective tissue. Howship's lacuna-like cavities were clearly visible at the surface of the material. They contained resorbing mononuclear phagocytes. At a more mature stage, TCP granules were embedded in an acellular fibrous material which underwent mineralization from the medullary spaces towards the granules. The bone formed was subsequently remodeled. The implanted material itself was progressively modified. It first acquired the staining appearance of bone. After its structure became loose and vacuolated, it was invaded by cells and vessels. The present data indicate that TCP has osteogenic potential and is subject to degradation. Unlike in experimental wounds, these processes are of long duration in human defects.

Comparison of decalcified freeze-dried bone allograft and porous particulate hydroxyapatite in human periodontal osseous defects

The purpose of this study was to clinically compare the healing potential of the osteoinductive decalcified freeze-dried bone allograft (DFDBA) with an osteoconductive synthetic graft, particulate porous hydroxyapatite (HA). Six patients ranging in age from 28 to 52 (mean age 42.6) participated in this investigation. They were without significant systemic disorders and had advanced periodontitis with at least two comparable periodontal defects. Each patient received initial therapy consisting of oral hygiene instruction, scaling, root planing, and occlusal adjustment as indicated. Probing pocket depth, gingival recession, attachment levels, and bleeding on probing were recorded in the posthygiene phase of therapy. Alveolar crest height and depth of osseous defect were obtained at the time of surgery. The cemento-enamel junction was used as the fixed reference point. All measurements were repeated at the time of a 6-month reentry. There was no significant difference in any of the soft tissue measurements when DFDBA and HA were compared. However, both treatment modalities reduced pocket depth and demonstrated a gain in clinical attachment levels. There was 2.2 mm of bone repair with DFDBA and 2.1 mm with HA. These values corresponded to a percent defect fill of 61% for DFDBA and 53% for HA. These values were likewise not statistically different.

Effect of various graft materials with tetracycline in localized juvenile periodontitis

Ten patients with bilateral, posterior osseous defects associated with localized juvenile periodontitis (LJP) completed the study. Following the initial therapy, osseous defects were surgically debrided and grafted with a 4:1 volume ratio combination of either Synthograft/tetracycline (b-TCP/TTC), Periograf/tetracycline (HA/TTC) or freeze-dried bone allograft/tetracycline (FDBA/TTC). Graft materials were selected randomly for each half mouth following defect debridement, with a different material used on the opposite side for that patient. Immediately following each surgery, patients were placed on doxycycline 100 mg/day for 10 days. Direct re-entry evaluation of 51 osseous defects demonstrated no significant differences among the graft materials regarding hard tissue or soft tissue changes, except for greater percent defect fill for HA/TTC compared to b-TCP/TTC. Significant decreases in defect depth and pocket depth were achieved with each graft material. No adverse reactions to the use of any of the graft materials in combination with local and systemic tetracycline were found. The results indicate all three graft materials used in conjunction with TTC are acceptable and beneficial for the treatment and repair of osseous defects associated with localized juvenile periodontitis.

Calcium phosphate materials in restorative dentistry: a review

This report deals with some of the calcium phosphate materials which are currently used in preventive and restorative dentistry and other calcium phosphate materials which have potential for dental and medical applications. Such materials include those which form calcium phosphate in situ (e.g., Bioglass ceramics and calcium phosphate cements) and those originating from natural materials (such as corals and bones).

The reports on the development and current status of the calcium phosphate ceramics and glass ceramics presented here were based on recent reviews and recent evaluations of clinical studies for the period 1975 to 1986 (Table 3) with humans and with animals when reports on human studies were not yet available. Methods of preparation and relevant physico-chemical properties of some of the calcium phosphate materials were based on data reported in the literature and on other studies by the author. New calcium phosphate materials, e.g., calcium phosphate cements, calcium phosphate-coated implants, calcium phosphate/polymer composites, have also been briefly covered in this report.

Based on the information summarized in Tables 1 to 6 and on solicited comments from clinicians and researchers involved with calcium phosphate materials, several areas of basic and clinical research are recommended (Table 7).

Bioceramic implants in surgical periodontal defects. A comparison study

The healing response of two commercially available bioceramics, beta tricalcium phosphate (TCP) and hydroxylapatite (HA), was compared after implantation in surgically created defects in dogs. Three 18 to 24 month old female Labrador dogs were used. Under general anesthesia 3-wall defects were created on the canines and premolars. The roots were planed, and reference notches were placed to identify the alveolar crest and the apical extent of the defects. TCP or HA was placed in alternating canine defects. The premolars received no implants and served as controls. Plaque management was accomplished by biweekly brushing with 0.2% chlorhexidine. Following healing periods of 5, 12 and 16 weeks, the dogs were sacrificed and perfused with 10% formalin. Six-mu step serial sections were evaluated by light microscopy. Healing against the root planed surface varied from a long junctional epithelium to a connective tissue reattachment in new cementum. TCP particles were actively resorbed by giant cells and macrophages and were incorporated into new bone matrix. The HA particles were encapsulated by fibrous connective tissue and rarely seen in contact with repairing bone. Bone formation was slower around HA particles at all time periods. Some evidence of HA particle resorption was seen at each time period.

Flap technique for periodontal bone implants. Papilla preservation technique

A new flap design for placement of implants into osseous defects has been described. The flap design can be used in anterior and posterior areas of human subjects. Photographs of representative cases are presented. Wound healing always occurred by primary intention and without evidence of immediate graft exfoliation. Interdental soft tissue craters did not develop, making it easier for patients to maintain optimal oral hygiene. This type of flap design can also be used without grafts in order to improve postoperative soft tissue contour.

The use of a porous hydroxylapatite implant in periodontal defects. I. Clinical results after six months

Twenty-five patients with advanced periodontal destruction were used in the study. Following initial therapy, two angular interproximal defects were selected in each patient. During flap surgery a porous hydroxylapatite implant shaped to fit the periodontal defect was placed in one defect, the other defect was used as nonimplanted control. The material used for implantation was a hydroxylapatite replicate of coral from the genus Porites, with a pore size of 190 to 220 micron. Clinical parameters were measured prior to flap surgery for each of the defects. An occlusal acrylic stent was used to give a stable reference point for pocket depth, attachment level and gingival margin height measurements. Also gingival fluid, gingival inflammation, plaque index and tooth mobility were recorded. Periapical radiographs using a standardized positioning device were also taken. At the time of surgery, the depth of the osseous defect and the height of the alveolar crest were recorded. After 6 months the clinical measurements were repeated and a re-entry surgery was carried out in 15 selected sites. Results showed that the porous implant produced statistically significant reduction in pocket depth, in the depth of osseous lesion, and a statistically significant gain in attachment level, as compared to control areas.

An evaluation of tricalcium phosphate implants in human periodontal osseous defects of two patients

This study evaluated the use of tricalcium phosphate (TCP) ceramic implant material in periodontal osseous defects. Thirteen defects in two patients were treated with mucoperiosteal flaps and placement of TCP. The defects were evaluated clinically and radiographically utilizing standardized probe placement and radiographic technique. Clinically, there was a mean probing pocket reduction of 4.5 mm as a result of a mean gain of clinical probing attachment level of 2.0 mm and a mean gingival recession of 2.5 mm. Radiographically, there was a mean "fill" of 1.8 mm. Six teeth were removed by block biopsy for histologic analysis, three at 3 months, one at 6 months and two a 9 months. The TCP particles were well tolerated and encapsulated by fibrous connective tissue, but the particles did not stimulate new bone growth. The junctional epithelium ended 1.62 mm coronal to the apical extent of a reference notch placed at the base of the defect. Although new cementum was observed, there was limited evidence of new attachment.

Particle size of periodontal bone grafting materials

Samples of autogenous bone obtained by high speed burs, low speed burs, hand chisels and bone blending; freeze-dried bone purchased from a tissue bank and alloplastic materials, such as Calcitite, Durapatite, Periograf and Synthograft used as donor material for periodontal bone grafting procedures, were evaluated histometrically. Particle sizes ranged from a mean of 210 X 105 mu for bone blend to 1559 X 783 mu for hand-chisel samples. Except for those two materials, all of the others were in the 300 to 500 microns (0.3-0.5 mm) range that seems to be preferred for use in periodontal defects.

Evaluation of durapatite ceramic as an alloplastic implant in periodontal osseous defects. I. Initial six-month results

Eight patients received a new polycrystalline ceramic form of pure hydroxylapatite (Durapatite) as a bone implant material in various types of infrabony defects following internally beveled full thickness flaps, root planing, and defect debridement. All osseous margins and defects were measured from the CEJ using a standardized periodontal probe. Similarly debrided defects that were not implanted served as controls. Defect selection as either experimental or control site was based on either split-mouth or alternating defects design. Periodontal dressing and systemic tetracycline were used for 10 days. Results for documentation and plaque control were at 10, 20, and 30 days, and 3 and 6 months. Measurements relating to defect changes were made at the 6-months surgical re-entry. For evaluation purposes original defect depths were divided into three groups. In Group I (less than 3 mm) defect fill was 1.2 mm (60%) for the implanted defects and 0.6 mm (40.5%) for the control sites (significantly different at P less than 0.05). In Group II (3--6 mm) defect fill of 1.7 mm (48.5%) for implanted sites was significantly better than the 0.1 mm (11.1%) for the control sites. In the deepest group (Group III greater than or equal to 6 mm) Durapatite placement yielded 2.6 mm (39.9%) of defect fill while debridement alone resulted in 1.3 mm (14.8%) of fill. Hard tissue changes demonstrated a substantial advantage for use of Durapatite over controls, while soft tissue changes were similar for both. The clinical impression at re-entry and the numerical data indicate that pure hydroxylapatite ceramic has a definite potential as an alloplastic implant in the treatment of periodontal osseous defects.