Use of bovine-derived anorganic bone associated with guided tissue regeneration in intrabony defects. Six-month evaluation at re-entry

Experimental and clinical studies on regenerative periodontal therapy

The recognition of a periodontal therapy as a regenerative procedure requires the demonstration of new cementum, periodontal ligament, and bone coronal to the base of the defect. A diversity of regenerative strategies has been evaluated, including root surface conditioning, bone grafts and bone substitute materials, guided tissue regeneration, enamel matrix proteins, growth/differentiation factors, combined therapies and, more recently, tissue-engineering approaches. The aim of this chapter of Periodontology 2000 is to review the research carried out in Latin America in the field of periodontal regeneration, focusing mainly on studies using preclinical models (animal models) and randomized controlled clinical trials. This review may help clinicians and researchers to evaluate the current status of the therapies available and to discuss the challenges that must be faced in order to achieve predictable periodontal regeneration in clinical practice.

A clinical and radiological evaluation of the relative efficacy of demineralized freeze-dried bone allograft versus anorganic bovine bone xenograft in the treatment of human infrabony periodontal defects: A 6 months follow-up study

Background:

The ultimate goal of periodontal therapy entails regeneration of the periodontal tissues lost as a consequence of periodontitis. Predictable correction of vertical osseous defects has however posed as a constant therapeutic challenge. The aim of our present study is to evaluate the relative efficacy of demineralized freeze-dried bone allograft (DFDBA) vs anorganic bovine bone xenograft (ABBX) in the treatment of human infrabony periodontal defects.

Materials and Methods:

15 patients with 30 bilaterally symmetrical defect sites in either of the arches, in the age group of 25-50 years were selected as part of split-mouth study design. Defect-A (right side) was grafted with DFDBA while Defect-B (left side) was grafted with ABBX. Various clinical and radiographic parameters viz. probing depth(PD), clinical attachment level(CAL) and linear bone fill were recorded preoperatively, 12- & 24-weeks postoperatively.

Results:

Both defect-A & defect-B sites exhibited a highly significant reduction in probing depth, and gain in clinical attachment level and linear bone fill at 12-weeks & at the end of 24-weeks. Comparative evaluation between the study groups revealed a statistically non-significant reduction in probing depth (P<0.1) and mean gain in linear bone fill (P<0.1). However, there was a statistically significant gain in clinical attachment level (P<0.05) in Defect-A (CD=0.356) as compared to Defect-B (CD=0.346).

Conclusions:

Within the limits of this study, both the materials viz. ABBX and DFDBA are beneficial for the treatment of periodontal infrabony defects. Both the materials were found to be equally effective in all respects except the gain in attachment level, which was found to be more with DFDBA. Long-term studies are suggested to evaluate further the relative efficacy of the two grafts.

A comparative evaluation of the effectiveness of guided tissue regeneration by using a collagen membrane with or without decalcified freeze-dried bone allograft in the treatment of infrabony defects: A clinical and radiographic study

BACKGROUND

The present, randomized, controlled clinical and radiographic study was undertaken to compare the effectiveness of guided tissue regeneration (GTR) by using a collagen membrane barrier with or without decalcified freeze-dried bone allograft (DFDBA) in the treatment of periodontal infrabony defects characterized by unfavorable architecture.

MATERIALS AND METHODS

Sixteen systemically healthy patients with 20 periodontal infrabony defects were selected for the study. Each patient had at least ≥ 5 mm clinical probing pocket depth (PPD) at the selected site and depth of intrabony component ≥ 3 mm as assessed by clinical and radiographic measurements. Baseline measurements included plaque index, papillary bleeding index, PPD, gingival recession, clinical attachment level and radiographic defect depth (DD). At the time of surgery, the defects were randomly assigned to either the test group (collagen membrane plus DFDBA) or the control group (collagen membrane only).

RESULTS

At the 6-month examination, PPPD reduction was significantly greater in the GTR + DFDBA group (4.06 ± 0.38 mm) compared with the GTR group (3.2 ± 0.74 mm). The mean gains of clinical attachment were 3.54 ± 0.36 mm in the test group and 2.50 ± 0.74 mm in the control group. Radiographic DD reduction was similarly greater in the GTR + DFDBA group (2.40 ± 0.51 mm) compared with the GTR group (1.60 ± 0.51 mm).

CONCLUSIONS

The results of the present study indicate that the use of a GTR membrane with bone graft has significantly improved all clinical parameters tested as compared with the use of bioresorbable membrane alone in the treatment of infrabony defects characterized by unfavorable architecture.

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.

Clinical evaluation of guided tissue regeneration combined with autogenous bone or autogenous bone mixed with bioactive glass in intrabony defects

Conflicting data exist on the combined use of grafting materials and barrier membranes in comparison to guided tissue regeneration (GTR) with membrane alone. The aim of the present study was to compare the clinical outcomes of GTR with collagen membrane (CM) alone (control group) or CM combined with autogenous bone graft (test group 1) or autogenous bone mixed with bioactive glass (test group 2) in intrabony defects. A total of 32 intraosseous defects in 22 subjects were treated randomly. After 6 months, significant probing depth reduction, clinical attachment level gain (CAL) and defect resolution were observed in all groups with significantly greater improvements in the test groups. There was no significant difference between the two test groups in any parameter. Results of the present study suggest that autogenous bone can be mixed with bioactive glass if the amount of the harvested bone is not sufficient.

Bacterial cellulose-hydroxyapatite nanocomposites for bone regeneration

The aim of this study was to develop and to evaluate the biological properties of bacterial cellulose-hydroxyapatite (BC-HA) nanocomposite membranes for bone regeneration. Nanocomposites were prepared from bacterial cellulose membranes sequentially incubated in solutions of CaCl₂ followed by Na₂HPO₄. BC-HA membranes were evaluated in noncritical bone defects in rat tibiae at 1, 4, and 16 weeks. Thermogravimetric analyses showed that the amount of the mineral phase was 40%–50% of the total weight. Spectroscopy, electronic microscopy/energy dispersive X-ray analyses, and X-ray diffraction showed formation of HA crystals on BC nanofibres. Low crystallinity HA crystals presented Ca/P a molar ratio of 1.5 (calcium-deficient HA), similar to physiological bone. Fourier transformed infrared spectroscopy analysis showed bands assigned to phosphate and carbonate ions. In vivo tests showed no inflammatory reaction after 1 week. After 4 weeks, defects were observed to be completely filled in by new bone tissue. The BC-HA membranes were effective for bone regeneration.

The problem of analysing the relationship between change and initial value in oral health research

The relationship between initial disease status and subsequent change following treatment has attracted great interest in dental research. However, medical statisticians have repeatedly warned against correlating/regressing change with baseline because of two methodological concerns known as mathematical coupling and regression to the mean. In general, mathematical coupling occurs when one variable directly or indirectly contains the whole or part of another, and the two variables are then analyzed by using correlation or regression. Consequently, the statistical procedure of testing the null hypothesis - that the coefficient of correlation or the slope of regression is zero - may become inappropriate. Regression to the mean occurs with any variable that fluctuates within an individual or a population, either owing to measurement error and/or to physiological variation. The aim of this article was to clarify the conceptual confusion around mathematical coupling and regression to the mean within the statistical literature, and to correct a popular misconception about the correct analysis of the relationship between change and initial value. As examples that use inappropriate methods to analyze the relationship between change and baseline are still found in leading dental journals, this article seeks to help oral health researchers understand these problems and explain how to overcome them.

Position Paper: Periodontal Regeneration

Untreated periodontal disease leads to tooth loss through destruction of the attachment apparatus and tooth-supporting structures. The goals of periodontal therapy include not only the arrest of periodontal disease progression,but also the regeneration of structures lost to disease where appropriate. Conventional surgical approaches (e.g., flap debridement) continue to offer time-tested and reliable methods to access root surfaces,reduce periodontal pockets, and attain improved periodontal form/architecture. However, these techniques offer only limited potential towards recovering tissues destroyed during earlier disease phases. Recently, surgical procedures aimed at greater and more predictable regeneration of periodontal tissues and functional attachment close to their original level have been developed, analyzed, and employed in clinical practice. This paper provides a review of the current understanding of the mechanisms, cells, and factors required for regeneration of the periodontium and of procedures used to restore periodontal tissues around natural teeth. Targeted audiences for this paper are periodontists and/or researchers with an interest in improving the predictability of regenerative procedures. This paper replaces the version published in 1993.

The relationship between baseline value and its change: problems in categorization and the proposal of a new method

Oral health researchers have shown great interest in the relationship between the initial status of diseases and subsequent changes following treatment. Two main approaches have been adopted to provide evidence of a positive association between baseline values and their changes following treatment. One approach is to use correlation or regression to test the relationship between baseline measurements and subsequent change (correlation/regression approach). The second approach is to categorize the lesions into subgroups, according to threshold values, and subsequently compare the treatment effects across the two (or more) subgroups (categorization approach). However, the correlation/regression approach suffers a methodological weakness known as mathematical coupling. Consequently, the statistical procedure of testing the null hypothesis becomes inappropriate. Categorization seems to avoid the problem of mathematical coupling, although it still suffers regression to the mean. We show, first, how the appropriate null hypothesis may be established to analyze the relationship between baseline values and change in the correlation approach and, second, we use computer simulations to investigate the impact of regression to the mean on the significance testing of the differences in the average treatment effects (or average baseline values) in the categorization approach. Data available from previous literature are reanalyzed by testing the appropriate null hypotheses and the results are compared to those from testing the usual (incorrect) null hypothesis. The results indicate that both the correlation and categorization approaches can give rise to misleading conclusions and that more appropriate methods, such as Oldham's method and our new approach of deriving the correct null hypothesis, should be adopted.

Effect of 830-nm laser light on the repair of bone defects grafted with inorganic bovine bone and decalcified cortical osseus membrane

OBJECTIVE

The aim of this study was to histologically assess the effect of low-level laser therapy (LLLT) (lambda830 nm) on the repair of standardized bone defects of the femur of Wistar albinus rats grafted with inorganic bovine bone and associated (or not) with decalcified bovine cortical bone membrane.

BACKGROUND DATA

Bone loss may be a result of pathology, trauma, or surgical procedure. Extensive studies on the process of bone repair have been undertaken, and several techniques for the correction of bone defects have been proposed. Amongst them is the use of several types of grafts, the use of membranes, and the combination of both techniques. There is evidence in the literature of the positive effect of LLLT on the healing of soft tissue wounds. However, its effect on bone healing is not completely understood.

MATERIALS AND METHODS

Five randomized groups were studied: group I (control); group IIA (Gen-ox); group IIB (Gen-ox + LLLT); group IIIA (Gen-ox + Gen-derm); and group IIIB (Gen-ox + Gen-derm + LLLT). Bone defects were created at the femur and were treated according to the group. The animals of irradiated groups were irradiated every 48 h for 15 days; the first irradiation was performed immediately after the procedure. The animals were irradiated transcutaneuosly at four points around the defect. At each point, a dose of 4 J/cm2 was given (phi approximately equal to 0.6 mm, 40 mW), and the total dose per session was 16 J/cm2. The animals were humanely killed at 15, 21, and 30 days after surgery. The specimens were routinely processed to wax, serially cut, stained with H&E and Picrosirius stains, and analyzed under light microscopy.

RESULTS

The results showed more advanced repair of the irradiated groups when compared to the non-irradiated ones. The repair of the irradiated group was characterized by both increased bone formation and on the amount of collagen fibers around the graft within the cavity, as early as the 15th day after surgery, considering the osteoconductive capacity of the Gen-ox and the increment of the cortical repair in specimens with Gen-derm membrane.

CONCLUSION

It is concluded that LLLT had a positive effect on the repair of bone defect by graft associated or not with the use of biological membrane.

Comparison of bone graft matrices for human mesenchymal stem cell-directed osteogenesis

Scaffolds to support cell-based tissue engineering are critical determinants of clinical efforts to regenerate and repair the body. Bone tissue engineering requires materials that are biocompatible, well vascularized, mechanically suited for bone function, integrated with the host skeleton, and support osteoinduction of the implanted cells that form new bone. The aim of this study was to compare the osteogenic potential of bone marrow-derived, culture expanded human mesenchymal stem cells (hMSCs) adherent to different scaffolds composed of various calcium phosphates. Cells were loaded onto 2 x 2 mm cubes of coral calcium carbonate-derived apatite, bovine bone-derived apatite, synthetic hydroxyapatite (HA)/tricalcium phosphate (TCP) (60:40%), or synthetic HA/TCP (20:80%) and placed into the dorsum of SCID mice for 5 weeks. Subsequent histomorphometric analysis of bone formation within the cubes revealed the absence of bone formation within the coral-derived apatite and the bovine bone-derived apatite. Bone formation within synthetic HA/TCP scaffolds was measured to be 8.8% (+/-2.7%) and 13.8% (+/-3.6%) of the total tissue present for the 60:40% and 20:80% materials, respectively. Minimal resorption was observed at this early time point. Scanning electron microscopy evaluation of loaded scaffolds indicates that cell loading was not a variable affecting the different bone formation outcomes in these four scaffolds. In this ectopic model, different apatite-containing scaffolds of similar morphology and porosity demonstrated marked differences in their ability to support osteoinduction by implanted hMSCs. The necessary induction of hMSCs along the osteoblastic lineage may be dependent, in part, on the local microenvironment established by the scaffold chemistry and interactions with the host.

Effect of 830-nm Laser Light on the Repair of Bone Defects Grafted with Inorganic Bovine Bone and Decalcified Cortical Osseous Membrane

OBJECTIVE

The aim of this study was to assess histologically the effect of LLLT (lambda830 nm) on the repair of standardized bone defects on the femur of Wistar albinus rats grafted with inorganic bovine bone and associated or not to decalcified bovine cortical bone membrane.

BACKGROUND DATA

Bone loss may be a result of several pathologies, trauma or a consequence of surgical procedures. This led to extensive studies on the process of bone repair and development of techniques for the correction of bone defects, including the use of several types of grafts, membranes and the association of both techniques. There is evidence in the literature of the positive effect of LLLT on the healing of soft tissue wounds. However, its effect on bone is not completely understood.

MATERIALS AND METHODS

Five randomized groups were studied: Group I (Control); Group IIA (Gen-ox); Group IIB (Gen-ox + LLLT); Group IIIA (Gen-ox + Gen-derm) and Group IIIB (Gen-ox + Gen-derm + LLLT). Bone defects were created at the femur of the animals and were treated according to the group. The animals of the irradiated groups were irradiated every 48 h during 15 days; the first irradiation was performed immediately after the surgical procedure. The animals were irradiated transcutaneously in four points around the defect. At each point a dose of 4 J/cm2 was given (phi approximately 0.6 mm, 40 mW) and the total dose per session was 16 J/cm2. The animals were humanely killed 15, 21, and 30 days after surgery. The specimens were routinely processed to wax, serially cut, and stained with H&E and Picrosirius stains and analyzed under light microscopy.

RESULTS

The results showed evidence of a more advanced repair on the irradiated groups when compared to non-irradiated ones. The repair of irradiated groups was characterized by both increased bone formation and amount of collagen fibers around the graft within the cavity since the 15th day after surgery, through analysis of the osteoconductive capacity of the Gen-ox and the increment of the cortical repair in specimens with Gen-derm membrane.

CONCLUSION

It is concluded that LLLT had a positive effect on the repair of bone defect submitted the implantation of graft.

Guided tissue regeneration associated with bovine-derived anorganic bone in mandibular class II furcation defects. 6-month results at re-entry

BACKGROUND

The use of graft materials with guided tissue regeneration (GTR) in Class II furcation defects is aimed at improving the outcome of the regenerative technique. In this regard, however, there are a limited number of studies discussing the results obtained when GTR and graft materials are used in the treatment of Class II furcation defects. Furthermore, most studies employ either allogeneic or autogenous materials. The present trial sought to determine whether the use of a bovine-derived anorganic bone (ABB) in conjunction with GTR influenced the outcome of mandibular Class II furcation treatment.

METHODS

This study included 14 patients who provided 15 pairs of similar periodontal defects. Each defect was randomly assigned to treatment with either a cellulose membrane in combination with bovine-derived anorganic bone (GTR+ABB) or membrane alone (GTR). Following basic therapy, baseline measurements were recorded including probing depth (PD), clinical attachment level (CAL), and gingival margin position (GMP). Hard tissue measurements were performed during surgery to determine alveolar crestal height (CEJ-AC), and vertical (VDD) and horizontal defect depth (HDD). Membranes remained in position for at least 4 weeks. After 6 months, all sites were re-entered and soft and hard tissue measurements were recorded.

RESULTS

Both surgical procedures resulted in statistically significant probing depth reduction and gain in clinical attachment levels, with no significant difference between groups. Gingival recession was more pronounced in the GTR+ABB group (0.87 +/- 0.83 mm), but not statistically different from the GTR group (0.46 +/- 1.19 mm). Vertical defect resolution was significant in both groups (GTR: 1.60 +/- 1.50 mm; GTR+ABB: 1.80 +/- 2.11 mm), without differences between groups. Only horizontal furcation resolution (GTR: 2.47 +/- 0.99 mm; GTR+ABB: 3.27 +/- 1.39 mm) was significantly different between groups (P <0.05).

CONCLUSIONS

The use of ABB with GTR techniques improved horizontal defect resolution in mandibular Class II furcation defects, but did not yield superior results regarding soft tissue changes when compared to sites treated with GTR alone. Evaluation of a larger sample could indicate differences and advantages between the evaluated approaches and confirm the real necessity of associating filling materials with GTR.