J Oral Maxlllofac Surg

43.570-573, 1985

Use of Collagen Tubes for Implantation of Hydroxylapa tite: An Experimental Study

RICHARD K. GONGLOFF, DMD, WILLIAM WHITLOW, DDS, AND CAROLYN K. MONTGOMERY, MD

Collagen tubes were compared with routine injection for placement of hydroxylapatite in mandibular defects. It was found that the collagen film containers were effective in providing easier handling, more effective shaping, and less migration of particles.

Hydroxylapatite is a particulate bone substitute material that has been studied extensively for use in oral and maxillofacial surgery. I-4 This material, however, is limited in its application due to its par- ticulate nature. At the time of placement it lacks form and cohesive strength, and particles may be misplaced or may compress, dislodge, or migrate under externally applied forces.5 In addition to these physical problems, the hydroxylapatite sy- ringe delivery system offers further limitations in particle placement.

This paper presents the results of a pilot project designed to study the efficacy of using a biodegrad- able tubular container of bovine collagen to contain and thereby prevent compression, dislodgement, and migration of particulate hydroxylapatite. Effec- tive use of such a container could expand the cur- rent applications of hydroxylapatite by allowing its use in areas where rigid maintenance of bony and soft tissue contours are prime requisites for a suc- cessful result.

Materials and Methods

Eighteen male outbred albino Sprague-Dawley rats, 4-8 months of age and weighing 500-600 g, were used as the experimental animals. The graft site chosen was a circular-to-ovoid transosseous de- fect in the angle of the mandible that included the lateral and medial periosteum.

The collagen tube (Helitrex Inc., Princeton, N.J.) used was composed of a surgically pure collagen of bovine deep flexor tendon origin. The particulate

Received from the Veterans Administration Medical Center, San Francisco, California.

Address correspondence and reprint requests to Dr. Gongloff: Chief, Oral and Maxillofacial Surgery, Dental Service (160), 4150 Clement St.. San Francisco. CA 94121.

implant materials, which were implanted randomly, were either small (40-60 mesh), irregularly shaped hydroxylapatite crystals (Cook-Waite Laboratories, Sterling Drug Inc., New York, N.Y.) or larger (20- 40 mesh), rounded hydroxylapatite crystals (Cal- citek, Inc., San Diego, Cal.).

The animals were divided into a study group of 15 rats and a control group of three rats. They were anesthetized with ketamine HCl (100 mg/kg) in- jected intraperitoneally and supplemented with in- filtration of 2% lidocaine into the operative area. In the study group, both angles of the mandible were exposed. Round to oval transosseous defects with diameters ranging from 5 to 7 mm were made through the bone. The lateral and medial perios- teum adjacent to the defect was also excised. The wounds were irrigated with saline prior to place- ment of the implants. One the right side approxi- mately 200 mg of hydroxylapatite of selected par- ticle shape and size, contained within a collagen film tube tied at both ends with a polyglycolic acid suture, was placed in the transosseous bony defect (C-HA). On the left side a similar amount of hydroxylapatite (HA) was directly injected or spooned into the osseous defect. In the control group, the transosseous defects were prepared in a similar fashion to those in the study group. On the right side a 0.7-cm segment of collagen tube without hydroxylapatite was tied at both ends, folded, and placed into the transosseous defect. On the left side the bony defect was allowed to heal spontaneously.

Randomly selected experimental and control an- imals were euthanized at 4, 8, and 16 weeks (Table 1). At the time of sacrifice, the mandible was dis- articulated and halved at the symphysis. The recip- ient areas were then examined clinically, radio- graphically, and histologically, and comparison was made between the right and left sides.

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GONGLOFF ET AL. 571

Table 1. Grading of Presence of Hydroxylapatite (HA) Outside the Graft Site, Graft Mobility, and Graft Consolidation

Rat

Presence of HA Outside the Graft Site*

Collagen + HA HA Alone

Graft Mobilityi

Collagen + HA HA Alone

Graft ConsolidationS

Collagen + HA HA Alone

Euthanized at 4 weeks I Anesthetic Death Anesthetic Death Anesthetic Death 2 Infection Infection Infection Infection Infection Infection 3 cl + 1+ 2+ S L 4 0 + 1-t 1+ S I 5 0 + 0 2+ S L

Euthanized at 8 weeks 6 Anesthetic Death Anesthetic Death Anesthetic Death 7 0 + I+ I+ S 1 8 0 + 1+ 2+ S L 9 0 + 0 I+ S S

10 0 + 0 1+ S I Euthanized at 16 weeks 11 Anesthetic Death Anesthetic Death Anesthetic Death 12 0 + 0 2+ S I 13 0 + 0 I+ S S 14 0 + 0 0 S S 1.5 0 + 0 I+ S 1

* 0. No HA present outside the graft site; + , HA particles present. t 0, No perceptible movement; I+ , 2 mm or less lateral-medial movement; 2 + , between 2 and 4 mm lateral-medial movement: 3 + ,

greater than 4 mm lateral-medial movement. $ S, Solid; I, intermediate; L, loose.

FIGURE 1. A (top), Lateral ra- diograph of hydroxylapatite im- plant placed in a collagen tube container (16 weeks). Notice the graft consolidation and the ab- sence of particles outside the im- plant site. B (bottom), Axial view of the same implant site.

572 COLLAGEN -~UHEIMPLANI-S

FIGURE 2. A Crop). Lateral view of hydroxylapatite implant placed conventionally with a sy- ringe (16 weeks). Notice the pres- ence of particles outside the graft side. B (bottom), Axial view of the same implant site.

Clinical assessment included exploration of the graft bed for the existence of HA particle outside the bony cavity. This was graded as either plus for HA particle present or minus for no particles present. The implant was also compressed digitally and an attempt was made to move it lateromedially within the bone cavity. Consolidation of the implant was graded S for solid, I for intermediate consoli- dation, and L for loose. The movement of the im- plant within the bone cavity was graded 0 for no movement, I + for less than 2 mm movement, 2+ for between 2 and 4 mm movement, and 3 + for greater than 4 mm of lateromedial movement. Ra- diographic assessment included views from both lateral and axial directions. Implant consolidation and the presence of HA particles outside the recip- ient site were evaluated. Histologic examination was accomplished with both hematoxylin and eosin and trichrome stains. The presence of inflamma- tion, the persistence of collagen, and differences in the quality of healing were examined in all speci- mens.

Results

Three animals died at the initial surgery of an- esthetic complications. Of the remaining animals, one control animal and one study animal showed gross evidence of infection in the immediate post-

operative period. All grafts were lost in these ani- mals. No other complications were reported.

CONTROLGROUP

Control animals showed no osseous healing in the ungrafted defect on the left side at 8 and 16 weeks. On the right side where the collagen film had been placed, there was no evidence of persistence of the film nor of bone induction or osseous healing at 8 or 16 weeks.

STUDYGROUP

Clinical Findings

The results regarding the presence of HA parti- cles outside the graft site, graft mobility within the recipient bed, and graft consolidation are shown in Table 1. In the HA implants, particles were present outside the graft site in all but one case, whereas in the C-HA implants, no extra-site hydroxylapatite particles were seen. The collagen tube implants were more rapidly attached to the recipient bed than the corresponding plain hydroxylapatite im- plants and generally were less mobile. The majority of the C-HA implants were also more consolidated than were the corresponding HA implants. All of the collagen-contained implants were rated solid

GONGLOFF ET AL. 573

FIGURE 3. A (1eff). Collagen tube contained implant at 16 weeks. Notice the cellular fibrous connective tissue and presence of inflammatory cells (Hematoxylin and eosin, magnification x 00). B (rig/u). Higher power view of the same specimen ( x 00).

after 4 weeks whereas only three of the noncollagen tube implants were graded as solid even after 16 weeks.

Radiographic Findings

Radiographic examination confirmed the clinical findings. All C-HA implants showed a dense con- solidation within the transosseous defect (Fig. I). In the sites where no collagen carrier was used, only two defects showed radiographic evidence of complete fill of the transosseous defect with hydroxylapatite particles. In the remaining nine de- fects there was a loose haphazard distribution of graft particles with a more dense consolidation of particles at the inferior and lateral aspects of the defect. Additionally, in all of these sites there was radiographic evidence of particles in areas outside of the defect (Fig. 2).

Histologic Examination

At 4, 8, and 16 weeks there was some inflam- mation in all sites examined. On the collagen film side there was evidence of slight persistance of the collagen material at 4 weeks; however, there was no evidence of collagen at 8 and 16 weeks. In all specimens examined, little to no osteoblastic re- sponse was noticed throughout the study period. The character of cellular response was primarily fi- broblastic, with macrophages and giant cells also present (Fig. 3).

Discussion

The results of this pilot project seem to support the hypothesis that collagen film can be used as a

biodegradable container to place hydroxylapatite particles without significantly affecting the favor- able properties of the implant material. Operative placement was simplified and there was no spillage of the particles into undesired areas. The collagen film provided support for the HA particles for up to 4 weeks, and because of this, postoperative con- tainment and consolidation of the particles was im- proved. In clinical use this may indicate that C-HA implants would demonstrate less dimensional change following denture loading.

In conclusion, collagen tubes placed around hydroxylapatite particles were studied in a small group of rats to determine if this would improve implant placement and form, prevent particle mi- gration, and improve particle consolidation. The very favorable results obtained in this study warrant further investigation of this implant system in both experimental animals and human subjects.

References

1. Kent JN, et al: Correction of alveolar ridge deficiencies with nonresorbable hydroxylapatite. J Am Dent Assoc 105:993, 1982

2. Cohen DW: Symposium on new bone grafting implant ma- terial for the treatment of periodontal disease, in Com- pendium of Continuing Education in Dentistry, Jan/Feb Suppl. S6, 1982

3. Rabalars ML, et al: Evaluation of Durapatite ceramic as an alloplastic implant in periodontal osseous defects. J Per- iodont 52:680. 1981

4. Boyne PJ, et al: Fluorescence microscopy of durapatite im- plants, in Proceedings from the Meeting of the 39th An- nual American Institute of Oral Biology, 1982, pp 53-57

5. Drobeck HP et al: Histologic observations of soft tissue responses to implanted, multifaceted particles and discs of hydroxylapatite. J Oral Maxillofac Surg 42: 143. 1984

6. Kaban LB, Glowacki J: Induced osteogenesis in the repair of experimental defects in rats. J Dent Res 60:1356, 1981