J. Periodontat Res: 13: 532-537. 1978

The effect of autogenous cancellous bone grafts on healing of experimental furcation defects in dogs ROLF NILVEUS, OWE JOHANSSON AND JAN EGELBERG

Department of Periodontology, School of Dentistry, University of Lund, Malmo. Sweden Chronic, through-and-through, furcation defects were created in mandibular premolars of six beagle dogs. These defects were surgically treated with and without autogenous, caneellous, bone grafts. Healing sockets in the maxilla served as donor sites. Block specimens were removed after eight weeks. All teeth from all dogs showed some reattachment after treatment as evidenced by newly formed eementum. None of the specimens showed complete regeneration, i.e. a periodontal membrane with new cementum all around the fornix of the furcation. Histometric measurements showed that the use of osseous grafts did not improve the results in the present experimental model. (Accepted for publication February 23, 1978)

achieved with autogenous bone marrow grafts. The healing process after this type The management of periodontal lesions of graft was often complicated by root rewhich have progressed into the furcations sorptions and ankylosis. When newly formed presents difficult clinical problems. The autogenous cancellous hone from extraction treatment procedures currently used are sites was used as grafting material, cotnplete based on the concept that postoperative re- closure of the furcations occurred in 34 % generation and fill of the defects with of the treated teeth. A normal periodontal healthy periodontal tissues is unlikely membrane was formed in the regenerated (Hamp, Nyman & Lindhe 1975). However furcation of these teeth. Schallhorn (1967), Schallhorn, Hiatt & In a subsequent study in monkeys by Boyce (1970) and Schallhorn & Hiatt (1972) Ellegaard, Karring and Loe (1975) complete have reported some cases which clinically regeneration of through-and-through furcashowed substantial improvement after the tion defects was similarly obtained using use of bone marrow grafts. cancellous bone grafts from edentulous Ellegaard et al. (1973) have studied the areas. The frequency of success, however, effect of bone grafts in treatment of experi- seems to have been lower in this later mental, through-and-through furcation de- study. The fact that complete regeneration has fects in the monkey. Complete regeneration and closure of the furcations was frequently been achieved after treatment of through

EFFECT OF BONE GRAFTS O N FURCATIONS and-througb defects in monkeys is somewhat at variance with current concept of the efficacy of such techniques in man. The present investigation is part of a series of studies on expeiimental, through-andthrough furcation defects in dogs. In a previous study it has been found that the method of Eliegaard et al (1973) of inducing furcation defects results, in dogs, in the development of chronic interradicular lesions with characteristics similar to those in man {Johansson, Nilveus & Egelberg 1978). The present investigation evaluates the effect of treatment of these defects with and without the use of grafts of autogenous, newly formed cancellous bone from extraction sites.

Material and Methods

A nimals Six female beagle dogs were used. They were three years old and weighed 10-15 kilograms. The mandibular second, third and fourth premolars (PM 2, PM 3 and PM 4) were subjected to experimentation. Chronic gingivitis was present around these teeth in all of the dogs at the start of the study. The operative procedures were carried out under general anesthesia using intravenously injected pentothal sodium. The animals were fed a soft diet (Egelberg 1965) during the entire experimental period. Induction oj furcation defects Chronic, through-and-through furcation defects were created using the method of Ellegaard et al. (1973) as described and evaluated in dogs by Johansson et al. (1978). Buccal and lingual mucoperiosteal flaps Were raised. A sliver of buccal bone in the furcation area was removed with a chisel. A round bur (No. 1) was gently passed through the bone under the fornix of the ft rcation. A steel wire was threaded through the created defect and ligated over

the crown in order to prevent spontaneous healing. The flaps were replaced and sutured by interdental sutures. The steel wires were left in place for six weeks and then removed. Another two weeks later the defects were treated. At that time a straight dental explorer could easily be passed through the furcations of all experimental teeth. Alveolar bone grafts Concomitant to the induction of the furcation defects (eight weeks prior to treatment) the maxillary second and third premolars on both sides were extracted. Cancellous bone from the healing sockets of these teeth were used for grafting. The bone was not taken out until the furcations to be grafted had been surgically debrided and prepared for the grafts. Thus, small pieces of cancellous bone were directly transferred from the donor sites and loosely packed into the recipient beds. Surgical treatment procedures Buccai and lingual incisions were made along the gingival margins. The incisions were started on the distal aspect of the canine and extended to the mesial aspect of the second molar. Buccal and lingual mucoperiosteal flaps were raised. The flaps were dissected from the bone in the apical direction almost to the base of the mandible. The margin of the flaps was trimmed to remove all chronically inflamed tissue. Horizontal incisions were made on the inner aspect of the flaps through the periosteum about 15 mm apical to the flap margins in order to facilitate elongation of the flaps in the coronal direction (Adeii 1974). The furcations were curetted and debrided. All soft connective tissue coronal to the interradicular bone was removed. The root surfaces were treated with a fine, flame-shaped diamond in order to remove the cementum. Small perforations into the

S34

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Fig. 1. Refer (see text).

interradicular bone were made with a sharp explorer. The furcation areas were cleaned and irrigated with saline. The bone grafts were placed into the furcations of the teeth in one side of the jaw. The left side was used for grafts in three of the dogs and the right side in the remaining three dogs. The flaps were replaced and sutured interdentally. Sutures were also tied over the mesial and distal parts of each tooth in preformed grooves. These sutures raised the elongated flaps coronally and allowed coverage of the furcation areas and part of the crowns. The position of the flaps was checked each day for two weeks postoperatively and sutures replaced as necessary. The sutures tied over the crowns were removed after one week and the interdental sutures after two weeks. The animals were given daily intramuscular injections of 600.000 LU, penicillin (Suspenin - Transin®, Kabi, Sweden) for eight weeks postoperatively starting on the day of surgery. Plaque control was instituted during the first two weeks by topical application of 2 % chlorhexidine gluconate (ICI, England) once daily for one minute. For the remaining six postoperative weeks, the teeth were brushed once daily with a multi-tufted, soft toothhrush.

A N D

E G E L B E R G

Histological evaluation Eight weeks after surgical treatment, specimen blocks consisting of tooth, bone and soft periodontal tissues were removed. The blocks were fixed in 10 % formalin, decalcified in formic acid, trimmed and embedded in paraffin. Serial, seven microns thick sections in a mesio-distal plane were cut through tbe central portion of the tooth. The sections were stained with hematoxylin and eosin. From each block three sections were used for measurements. The section which showed the widest root canals and pulp chamber was first identified. This section was considered to be the most centrally located section of the tooth. Then, the section located 10 sections buccal and the section located 10 sections lingual to this midsection were selected. Thus, three sections bridging about 150 microns of the midportion of each tooth were used for analysis (section 1: buccal; section 2: central; section 3: lingual). Each section was projected onto a screen at 140 times magnification and the following measurements made (Fig, 1): 1. The perpendicular distance between the most coronal point of the furcation fornix and a line tangential to the most coronal part of the interradicular hone (a-b). 2. The length of that part of the circumference of the furcation which was covered by epithelium (x-y).

Results Clinically, postoperative healing appeared uneventful. A gradual shrinkage of the flap margins occurred and after two to four weeks they occupied a normal position 'n relation to the tooth crown. Histologically, at eight weeks all tec:h examined showed some reattachment aff-r

E F F E C T

O F B O N E

G R A F T S

O M

F U R C A T I O N S

Table 1

The length in 10"^ mm of the furcation circumference covered by epithelium (x-y) Section

Dog 1 with graft

266

283

Sec-

Dog 5 with graft

without graft

Me•an

oth

without graft

Dog 2 with graft

without graft

Oog 3 with graft

349

267

194

Dog 6 with gratt

without graft

without gratt

IE!1

Oog A with graft

wilhout graft

163

211

Dilfere nee grafts

no graft

Dog 1 Dog 2 DOQ3

Dog 4 Dog 5 Dog 6

•) cantral section lost.

treatment as evidenced by newly formed cementum. However, none of the teeth had new cementum all around the fornix of the furcation. All fureation areas showed chronic inflammatori' cells in the eonnective tissue. Ankylosis was not observed. A majority of the specimens showed epithelium in the fornix of the furcation. Only three teetli in one dog (Dog 6; PM 2. PM 3. PM 4; with grafts) did not show epithelium in the furcation fornix. New cementutti. however, had not been formed in the fornix of these teeth. The length of the furcation circumference covered by epithelium in each tooth (x-y) is

presented in Table ]. Three dogs had, on the average, a shorter epithelial lining on the grafted side, while three dogs showed the opposite result. The distance between the most coronal interradicular bone and the furcation fornix (a-b) is presented in Table 2. Three dogs had on the average, a shorter distance on the grafted side, while three dogs showed the opposite result. Only one of the grafted teeth showed evidence of remaining osseous graft (Dog 5; PM 4). A small piece of bone with empty lacunae devoid of osteoeytes and encircled by epithelium was seen in this specimen.

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A N D

E G E L B E R G

:ance in 10"^ mm between the most coronal interradicular bone and the furcation fornix (a-b) Section

Dog 1 with graft

without graft

Dog 2 with graft

Section

Dog 5 with graft

without graft

Dog 6

Dog 4 with graft

graft

Difference vs

without graft

fio graft

Dog 1 Dog 2 Dog 3

Dog 5 Dog 6 182(98) ••) 196(105)") 2()3(126)")

*) central section lost, " j graft SI rrounded by epitheiii

Discussion

In 33 out of the 36 teeth comprising the experimental material, epithelium was present in the fornix of the furcation eight weeks after surgical treatment of the defect. In the three specimens which did not show epithelium, connective tissue was located in immediate contact with the tooth in the furcation fornix. New cementum, however, could not be observed. Thus, none of the teeth, regardless of treatment, showed complete regeneration fulfilling the criteria of formation of a new periodontal membrane

with new cementum. These results are somewhat in contrast to the results of Eliegaard et al. (1973), who obtained complete regeneration in 15 % of the furcations without grafts and 34 % of the furcations with grafts. The fraction of the furcation circumference covered by epithelium did not show any difference in favor of treatment either with or without osseous grafts. Likewise, the distance between the interradicular bone and the furcation fornix was similar following the two treatment modalities. These results indicate that the use of osseous grafts

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did not improve the results in the present experimental model. In the studies by Ellegaard et al. (1973, 1975), grafted osseous particles were regularly observed and the most deeply located grafted bone became incorporated in new bone developing from the interradicular septum. The more coronally located graft particles were rejected or became surrounded by a cementum-iike substance. In the present study, the osseous grafts could not be identified except in one instance. The grafts had most likely been rejected during the eight weeks postoperative period. This might explain, why no difference in healing results was observed between grafted and non-grafted furcations. From a clinical standpoint, an acceptable treatment procedure of furcation defects should predictably yield complete regeneration of the defects. Partial fill will probahly he of limited value since the plaque control problem remains. In neither the monkey nor the dog model has complete regeneration predictably been obtained. Further modifications aiming at improving the results of treatment should be examined. In such animal studies, however, due consideration has to be given to the possibility that the regeneration capacity in monkeys and dogs may be superior to that of man. Reierences Adell, R. 1974. Regeneration of the periodonti-

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E G E L B E R G

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um. An experimeatal study in dogs. Thesis. Suppl. lL Scand. J. Plast. and Reconstr. Surg. Egetberg, J. 1965. Local effect of diet on plaque formation and development of gingivitis in dogs. I. Effect of hard and soft diets. Odontol. Revy 16: 31-41. Ellegaard, B., Karring, T., Listgarten, M. & Loe, H. 1973. New attachment after treatment of interradicular lesions. J. Periodontol. 44; 209-217. Ellegaard, B., Karring, T. & Loe, H. 1975. The fate of vital and devitalized bone grafts in the healing of interradicular lesions. J. Periodontal Res. 10: 88-97. Hamp, S. E., Nyman, S. & Lindhe, J. 1975. Periodontal treatment of multirooted teeth. Results after 5 years. J. Clin. Periodontol. 1: 126-135. Johansson, O., Nilveus. R. & Egelberg, J. 1978. Experimental bifurcation defects in dogs. /. Periodontal Res. 13: 525-531. Schallhorn, R. G. 1967. Eradication of bifurcation defects utilizing frozen autogenous hip marrow implants. Periodontal Abstr. 15: 101-105. Schallhorn, R.G. & Hiatt, W.H. 1972. Human ailografts of iliac eancellous bone and marrow in periodontal osseous defects. II. Clinical observations. /. Periodontol. 43: 67-91. Schallhorn, R. G., Hiatt, W. H. & Boyce, W. 1970. Iliac transplants in periodontal therapy. J. Periodontol. 41: 566-580.

Address: Department of Periodontology School of Dentistry University of Lund S-214 21 Malmo, Sweden

The effect of autogenous cancellous bone grafts on healing of experimental furcation defects in dogs.

J. Periodontat Res: 13: 532-537. 1978 The effect of autogenous cancellous bone grafts on healing of experimental furcation defects in dogs ROLF NILVE...
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