Clinical Advances in Periodontics Vol. 7, No. 4, November 2017 : Page-190

CASE SERIES Evaluation of a Poly(Lactic-Co-Glycolic) Acid – Coated b -Tricalcium Phosphate Bone Substitute for Alveolar Ridge Preservation: Case Series Hanae Saito,* Harlan J. Shiau,* Hari Prasad, † and Mark A. Reynolds* Introduction: b -Tricalcium phosphate ( b -TCP) is a synthetic osteoconductive scaffold that is used as an alternative to autogenous bone grafts. The purpose of this case series was to examine the effectiveness of a polymer-coated b -TCP par-ticulate graft in preserving alveolar ridge height after tooth extraction. Effectiveness was evaluated using radiographic mea-surements, together with a histomorphometric evaluation of bone formation. Case Series: Eight patients, treatment planned for extraction and dental implant placement in the posterior region, were consecutively enrolled in the case series. Study teeth were extracted, and an alloplastic bone substitute, consisting of synthetic b -TCP granules coated with a biodegradable polymer (i.e., poly[lactic-co-glycolic] acid [PLGA]), was placed and adapted into the extraction socket. Patients were recalled at 1, 2, and 4 weeks and 3 months postoperatively to evaluate wound healing and at 4 to 5 months for implant placement. Bone specimens were collected at osteotomy preparation. Heal-ing was uneventful at each graft site. Five sites were available for surgical reentry and implant placement; the sites exhibited £ 10% reduction in radiographic bone height. Histologic evidence of vital bone growth was evident at each grafted site. Conclusions: The PLGA-coated b -TCP bone substitute exhibited good stability and retention after socket grafting. Extraction sites healed with clinical and radiographic evidence of ridge preservation. Clin Adv Periodontics 2017;7:190-194. Key Words : Bone regeneration; bone transplantation; tooth socket. Background Dental extraction generally results in a loss of alveolar ridge dimension or volume within the first 3 months of healing. 1-4 Preservation of the alveolar ridge is often necessary to permit dental implant placement and to provide favorable esthetics and successful long-term outcomes for implant restorations. 3,4 Alveolar ridge preservation (ARP) procedures are intended to minimize changes in alveolar ridge dimension after tooth * Department of Advanced Oral Sciences and Therapeutics, Division of Periodontics, School of Dentistry, University of Maryland, Baltimore, MD. † Division of Oral and Maxillofacial Pathology, University of Minnesota, Minneapolis, MN. extraction by use of a bone graft material, barrier membrane, or both. 3,4 Multiple graft materials, including autogenous bone, demineralized bone allograft, deproteinized bovine bone, and alloplasts, have shown effectiveness in ARP proce-dures. 3-6 b -Tricalcium phosphate ( b -TCP) is a synthetic, bioabsorbable, osteoconductive substitute 3,4,7,8 that sup-ports bone formation in experimental 7 and human clinical applications, including alveolar ridge and maxillary sinus augmentation. 9-11 The purpose of this case series is to evaluate the effective-ness of a poly(lactic-co-glycolic) acid (PLGA)–coated b -TCP bone substitute, which hardens after placement in situ, in preserving the alveolar ridge after tooth extraction. Submitted December 28, 2016; accepted for publication May 10, 2017 doi: 10.1902/cap.2017.160092 Clinical Presentation Eight patients (four males and four females, aged 38 to 75 years; mean age: 56.5 years), treatment planned for extraction, 190 Clinical Advances in Periodontics, Vol. 7, No. 4, November 2017

Evaluation Of A Poly(Lactic-Co-Glycolic) Acid–Coated β-Tricalcium Phosphate Bone Substitute For Alveolar Ridge Preservation: Case Series

Hanae Saito, Harlan J. Shiau, Hari Prasad, and Mark A. Reynolds

Introduction: b-Tricalcium phosphate (b-TCP) is a synthetic osteoconductive scaffold that is used as an alternative to autogenous bone grafts. The purpose of this case series was to examine the effectiveness of a polymer-coated b-TCP particulate graft in preserving alveolar ridge height after tooth extraction. Effectiveness was evaluated using radiographic measurements, together with a histomorphometric evaluation of bone formation.

Case Series: Eight patients, treatment planned for extraction and dental implant placement in the posterior region, were consecutively enrolled in the case series. Study teeth were extracted, and an alloplastic bone substitute, consisting of synthetic b-TCP granules coated with a biodegradable polymer (i.e., poly[lactic-co-glycolic] acid [PLGA]), was placed and adapted into the extraction socket. Patients were recalled at 1, 2, and 4 weeks and 3 months postoperatively to evaluate wound healing and at 4 to 5 months for implant placement. Bone specimens were collected at osteotomy preparation. Healing was uneventful at each graft site. Five sites were available for surgical reentry and implant placement; the sites exhibited £10% reduction in radiographic bone height. Histologic evidence of vital bone growth was evident at each grafted site.

Conclusions: The PLGA-coated b-TCP bone substitute exhibited good stability and retention after socket grafting. Extraction sites healed with clinical and radiographic evidence of ridge preservation. Clin Adv Periodontics 2017;7:190-194.

Key Words: Bone regeneration; bone transplantation; tooth socket.

Background

Dental extraction generally results in a loss of alveolar ridge dimension or volume within the first 3 months of healing.1-4 Preservation of the alveolar ridge is often necessary to permit dental implant placement and to provide favorable esthetics and successful long-term outcomes for implant restorations.3,4 Alveolar ridge preservation (ARP) procedures are intended to minimize changes in alveolar ridge dimension after tooth extraction by use of a bone graft material, barrier membrane, or both.3,4

Multiple graft materials, including autogenous bone, demineralized bone allograft, deproteinized bovine bone, and alloplasts, have shown effectiveness in ARP procedures. 3-6 b-Tricalcium phosphate (b-TCP) is a synthetic, bioabsorbable, osteoconductive substitute3,4,7,8 that supports bone formation in experimental7 and human clinical applications, including alveolar ridge and maxillary sinus augmentation.9-11

The purpose of this case series is to evaluate the effectiveness of a poly(lactic-co-glycolic) acid (PLGA)–coated b-TCP bone substitute, which hardens after placement in situ, in preserving the alveolar ridge after tooth extraction.

Clinical Presentation

Eight patients (four males and four females, aged 38 to 75 years; mean age: 56.5 years), treatment planned for extraction, ARP, and dental implant placement in a posterior sextant, were selected according to inclusion and exclusion criteria, and consecutively enrolled from April to July 2015. Inclusion criteria were: 1) provision of written informed consent; 2) 18 to 75 years of age; 3) treatment plan including a single tooth extraction, with adjacent teeth present; and 4) intact alveolar ridge based on cone-beam computed tomography (CT) imaging. Exclusion criteria included: 1) active caries or endodontic lesions in adjacent teeth; 2) health condition with potential to compromise healing (e.g., uncontrolled diabetes mellitus); 3) previous (£3 months) or current medication with potential to induce gingival overgrowth; 4) smoking >10 cigarettes daily; 5) pregnancy or nursing; and 6) any medical contraindications to surgery. Radiographic verification of ridge integrity was completed using available cone-beam CT images. The study was approved by the Institutional Review Board, University of Maryland, Baltimore, Maryland. All patients provided written informed consent.

Study teeth were extracted under local anesthesia as atraumatically as possible, without raising a mucoperiosteal flap. Extraction sockets were thoroughly debrided, and the integrity of the buccal plate was verified with a periodontal probe‡ (Fig. 1). The bone substitute was prepared by mixing b-TCP granules coated with a biodegradable polymer (PLGA) with N-methyl-2-pyrrolidone liquid activator to form a permeable, moldable material.x The moldable bone substitute was placed into the socket to the level of the crestal bone and adapted to the internal socket morphology (Fig. 2). The composite graft hardened within a few minutes. No attempt was made to adapt the wound margins or to achieve primary wound closure. Postoperative medications (antibiotic, analgesic, and oral antiseptic rinse) were prescribed. Patients were recalled at 1, 2, and 4 weeks and 3 months postoperatively to evaluate wound healing.

Case Management

The characteristics of the cases are presented in Table 1.12A standardized periapical radiograph was exposed using a bite registration and positioning device at time of extraction and at implant placement. Linear measurements of crestal bone height were made in triplicate using the cemento-enamel junction/crown margin of adjacent teeth. About 4 to 5 months after extraction and ridge preservation, five patients returned to the clinic for implant placement. Three patients did not undergo implant surgery because of a change in treatment plan, delay in treatment, and loss to follow-up. At time of implant surgery, a 2-mm trephine bur was used to create the initial osteotomy and harvest bone specimen. Specimens were fixed in 10%buffered formaldehyde and submitted for histologic analysis.

Each bone specimen was processed and polished to a thickness of 45 mm according to the Donath protocol,13 followed by staining with Stevenel blue and van Gieson picrofuchsin. Photomicrographs, obtained with a digital microscope camera‖{ under constant magnification, were used for histologic comparisons.

Clinical Outcomes

Healing was uneventful at each extraction site after ARP. Surgical reentry was completed at five healed sites, with each site exhibiting adequate ridge preservation to support implant placement (Fig. 3). Four of the surgical sites exhibited type III bone density, consistent with initial implant stability of 35 Ncm (Fig. 4). Radiographic measurements revealed a reduction in ridge height ranging from 0% to 10% at the time of implant placement (Table 1).

Microscopic examination of the specimens revealed evidence of vital bone formation at each graft site (Figs. 5 and 6). Vital bone was present in intimate contact with the surface of b-TCP graft particles. Residual graft particles, exhibiting various degrees of resorption, were evident in all specimens. Soft tissue matrix exhibited no evidence of inflammation or foreign body reaction adjacent to residual graft particles.

Each implant was successfully restored 3 to 6 months after surgical placement.

Discussion

Various particulate grafts are used for socket grafting and have been shown to be effective in ridge preservation.3,4,7,8 Clinical strategies to improve the retention and stability of particulate grafts have included the use of barrier membranes, soft tissue grafts, and flap advancement and coverage. More recent focus has been on the use of polymers to create flowable or moldable particulate-based bone substitute to facilitate graft placement and retention. Polymer coatings may also allow for modification of the mechanical and biodegradation properties of particulate grafts.

In this case series, a moldable PLGA-coated b-TCP bone substitute was found to improve ease of adaptation and placement in the extraction sockets. The consistency of this composite graft results from wetting the PLGA-coated b-TCP granules with N-methyl-2-pyrrolidone liquid activator that softens the polymer coating, making the surface sticky.14 Clearance of the activator results in solidification, thereby promoting graft stabilization and particle retention. 14 Surgical reentry revealed minimal ridge remodeling. No additional augmentation was necessary to support implant placement with primary stability. Histologic examination revealed vital bone formation as well as residual graft particles, consistent with the results of other studies evaluating b-TCP.14,15 The effect of the PLGA coating on the rate of b-TCP resorption remains unclear.15

This alloplastic material does not function as a barrier membrane, partitioning the soft tissue and grafted socket, because the latter might have contributed to the poorer bone quality. The additional use of barrier membrane or longer healing period prior to implant placement might be considered in certain clinical scenarios, for example, large or poorly contained extraction sockets. The findings of this case series are necessarily limited by methodology and design. Nonetheless, the b-TCP/PLGA polymer composite graft exhibited good stability and retention after socket grafting, and sites healed with clinical and radiographic evidence of ridge preservation. Long-term follow-up is necessary to determine bone stability and implant survival.

Summary

Why are these cases new information?

■ b-TCP/PLGA polymer composite graft exhibits favorable handling characteristic when used alone for ridge preservation after extraction.

What are the keys to successful management of these cases?

■ Well-contained extraction sockets appear most suitable for the application of this composite graft.

■ Quick placement and adaptation of graft material (about 60 seconds after contact with body fluid) are required.

What are the primary limitations to success in these cases?

■ Impact of polymer on the resorption/replacement of b-TCP is unknown.

Acknowledgments

This study was supported by Sunstar Americas, Schaumburg, Illinois. The authors thank Dr. Akane Takemura, Sunstar Americas, and Dr. Gonzalo Blasi, former resident, University of Maryland, Baltimore, Maryland, for their contribution. The authors report no conflicts of interest related to this case series.

CORRESPONDENCE:

Dr. Hanae Saito, Department of Advanced Oral Sciences and Therapeutics, Division of Periodontics, School of Dentistry, University of Maryland, Rm 4201, 650 W. Baltimore St., Baltimore, MD 21201. E-mail: hsaito@umaryland.edu.

References

1.Schropp L, Wenzel A, Kostopoulos L, Karring T. Bone healing and soft tissue contour changes following single-tooth extraction: A clinical and radiographic 12-month prospective study. Int J Periodontics Restorative Dent 2003;23:313-323.

2.Covani U, Cornelini R, Barone A. Vertical crestal bone changes around implants placed into fresh extraction sockets. J Periodontol 2007;78:810- 815.

3.Avila-Ortiz G, Elangovan S, Kramer KW, Blanchette D, Dawson DV. Effect of alveolar ridge preservation after tooth extraction: A systematic review and meta-analysis. J Dent Res 2014;93:950-958.

4.Van der Weijden F, Dell’Acqua F, Slot DE. Alveolar bone dimensional changes of post-extraction sockets in humans: A systematic review. J Clin Periodontol 2009;36:1048-1058.

5.Jambhekar S, Kernen F, Bidra AS. Clinical and histologic outcomes of socket grafting after flapless tooth extraction: A systematic review of randomized controlled clinical trials. J Prosthet Dent 2015;113:371-382.

6.De Risi V, Clementini M, Vittorini G, Mannocci A, De Sanctis M. Alveolar ridge preservation techniques: A systematic review and metaanalysis of histological and histomorphometrical data. Clin Oral Implants Res 2015;26:50-68.

7.Schwarz F, Herten M, Ferrari D, et al. Guided bone regeneration at dehiscence-type defects using biphasic hydroxyapatite þ beta tricalcium phosphate (bone ceramic) or a collagen-coated natural bone mineral (BioOss collagen): An immunohistochemical study in dogs. Int J Oral Maxillofac Surg 2007;36:1198-1206.

8.Artzi Z, WeinrebM,Givol N, et al. Biomaterial resorption rate and healing site morphology of inorganic bovine bone and beta-tricalcium phosphate in the canine: A 24-month longitudinal histologic study and morphometric analysis. Int J Oral Maxillofac Implants 2004;19:357-368.

9.Brkovic BM, Prasad HS, Rohrer MD, et al. Beta-tricalcium phosphate/ type I collagen cones with or without a barrier membrane in human extraction socket healing: Clinical, histologic, histomorphometric, and immunohistochemical evaluation. Clin Oral Investig 2012;16:581-590.

10.Thompson DM, Rohrer MD, Prasad HS. Comparison of bone grafting materials in human extraction sockets: Clinical, histologic, and histomorphometric evaluations. Implant Dent 2006;15:89-96.

11.Zijderveld SA, Zerbo IR, van den Bergh JP, Schulten EA, ten Bruggenkate CM. Maxillary sinus floor augmentation using a betatricalcium phosphate (Cerasorb) alone compared to autogenous bone grafts. Int J Oral Maxillofac Implants 2005;20:432-440.

12.Lekholm UZ. Patient selection and preparation. In: Branemark PI, Zarb GA, Albrektsson T, eds. Tissue Integrated Prostheses: Osseointegration in Clinical Dentistry. Chicago: Quintessence; 1985: 199-209.

13.Donath K, Breuner G. A method for the study of undecalcified bones and teeth with attached soft tissues. The Sage-Schliff (sawing and grinding) technique. J Oral Pathol 1982;11:318-326.

14.Horowitz RA, Leventis MD, Rohrer MD, Prasad HS. Bone grafting: History, rationale, and selection of materials and techniques. Compend Contin Educ Dent 2014;35:1-6, quiz 7.

15.Bizenjima T, Takeuchi T, Seshima F, Saito A. Effect of poly (lactideco- glycolide) (PLGA)-coated beta-tricalcium phosphate on the healing of rat calvarial bone defects: A comparative study with pure-phase beta-tricalcium phosphate. Clin Oral Implants Res 2016;27:1360- 1367.

indicates key references.


Department of Advanced Oral Sciences and Therapeutics, Division of Periodontics, School of Dentistry, University of Maryland, Baltimore, MD.

† Division of Oral and Maxillofacial Pathology, University of Minnesota, Minneapolis, MN.

Submitted December 28, 2016; accepted for publication May 10, 2017

doi: 10.1902/cap.2017.160092

Read the full article at http://onlinedigeditions.com/article/Evaluation+Of+A+Poly%28Lactic-Co-Glycolic%29+Acid%E2%80%93Coated+%CE%B2-Tricalcium+Phosphate+Bone+Substitute+For+Alveolar+Ridge+Preservation%3A+Case+Series/2908871/445120/article.html.

Previous Page  Next Page


Publication List
Using a screen reader? Click Here