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Resorption characteristics of bone and bone substitutes
Plaster: A bone substitute Saul L. Bahn, B.B., D.M.B., M.Sc.D., West Ha??en, COU?~. VETERANS
T
ADMINISTRATION
HOSPITAI,
hc extensive literature on the replacement of osseous tissue recommends the US: of bone and bone substitutes for filling defects caused by neoplasms, cysts, trauma, infection, congenital disease, and surgical intervention. The aims of replacing OSS~OLIS structure are preservation of morphologic contour, restoration of mechanical strength and function, elimination of dead space to reduce postoperative infection and thus promote healing, prevention of ingrowth of soft tissue, and enhancement of retention of prosthetic devices. When conditions a.re favorable for regeneration of bone, such goals can often be achieved. However, in many large lesions or defects or in the absence of favorable conditions in smaller defects, the morphologic contour is not completely restored and the bone remains weakened for long periods until complete healing can occur. The breakdown of the center of the clot or granulation t,issue and a predisposition to infection impede the normal processes of healing.] Regeneration of bone requires an adequate supply of many elemenm from blood and tissue fluid, including protein, inorganic ions (mainly calcium and phosphorus), hormones, enzymes, vitamins, and oxygen. Also functioning cellular elements, including macrophages, platelets, differentiating mesenchymal and endothelial cells, as well as the phosphatase complex, are needed. Temperature, pH, osmolality, and other physical conditions must bc carefully controlled. Factors that interfere with healing, such as movement of adjacent segments, chemical or physical irrit,ation, contamination, and infection, must he eliminated if osseous regeneration is to take place.’ Most. of the surgical interventions proposed in the lit,erature are variations of the primary at,trmpts at bone implantation made by Van Walt,her in I820 and of the grafting of osseous tissnc by Macewin in 1878.’ The orga.nic bone used in these early studies was autogenous, homologous or heterogenous.2 Anorganic derivatives of bone have been prepared and used.” Ma.ny investigators have experimented with such alloplasts (bone substitutes) as polyvinyl sponge,” calcium salts4 glass,5 polyurethane derivatives6 absorbable gelatin sponge (Gelfoam) with penicillin added,’ chondroitin sulfate, various plastics, and acrylics,* alcoholic and acidic extracts of bone and pcriosteum,” soft tissues such as urinary mucosa,4 sera,s total embryonic extracts,8 and meta1s.2 NOIK cartilage,2 antireticulotoxic of the materials studied has been universally successful in achieving the physiologic goals mentioned previously. The ideal material would also satisfy the prac-
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Pluster as hove substitute
tical requirements of ease of manipulation, minimal trauma to the patient, economy. The quest for such a material still continues.
673 and
PLASTER OF PARIS
The first report on the use of plaster of Paris to fill defects in bone was published in 1892 by Dreesman (reviewed by Peltierg), who described the results of filling osseous defects with plaster in eight patients. In three of six patients, tubrrculous cavities in bone were complet,ely filled in with new bone. In one patient with two tuberculous cavities, one cavity healed but the other did not. Two patients had tuberculous defects that did not heal. In the last two patientsone with a cavity due to osteomyelitis and the other with a surgical defect caused by removal of an enchondroma of the fifth metacarpal-complete bone regeneration occurred after implantation of plaster into the defects. Two years later Stachow filled operative defects in the long bones of sheep with plaster of Paris and closed the periosteum over the implant.. 9 He observed complete absorption of the plaster and regeneration of normal bone; only a slight reaction to the plaster of Paris was not.ed. In the same year Mart’in’o carried out similar experiments with dogs. Further interest in the material was not evident until 1925, when a report by Kolfmannll told of the successful use of plaster of Paris to fill osseous cavities in many patients, including one with a tibia1 abscess operated upon in 1912. Oehlecker,l” in discussing Kofmann’s paper, urged that this method be used more extensively in treating bone defects associated with resection of benign tumors and pointed out that plaster o’f Paris was well tolerated by the tissues. In 1928 Nystrom13 reported on the results observed in four patients treated with this material. Three patients showed complete uneventful healing; in the fourth cxtjrusion of a. portion of the plaster of Paris from the wound was followed by healing. In the same year, Petrova,l* working at the Institute of Traumatology in Leningrad, added 10 per cent Riranol or 10 per cent Kreolin, both antiseptics, t.o plaster of Paris before inserting it into the surgical defects of twenty-eight dogs and found that the dcfccts in all the dogs healed. In ten dogs with uninfected wounds there was complete restitution of the normal bony architecture, including the marrow cavity, at the end of 6 to 8 months. The average time r+ quired for the same results in eighteen dogs with infected wounds was 10 months. In 1930 Edburg’” reported a study of the use of plaster of Paris in six patients, including two with dentigerous cysts, one with an abscess of the ilium, one with a cavity caused by osteomyelitis, and two with tuberculous cavities in hone. Solid healing occurred in the last three patients, but in the first three the mat,erial was extruded. Nordmann,16 in 1939, reported success in treating one patient with aseptic necrosis of the lunate bone and another with aseptic necrosis of the cuboid bone by curettage and packing of the en\-itics with the hemihydratc of calcium sulfate (plaster). In 1944 an extensive report by Nielson17 described the use of plaster of Paris in fourt,cen patients with uninfected cavities and in sixteen patients with infected osseous defects, two of which were tuberculous. Nine patients had been followed for at least 4 years, and none developed any complications at.tributable to the
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I Wili
implanted material. Good results WCL’(’reported in all (:;ws. I%ern~r,~’ ill tllc, S:IIII(’ JWW, treated a patient with ;a.large mandibular cyst 1,~ curettage ant1 im~)lant;~lion of a 1 to 1 mixture of plastrr ot’ Paris ;lnd OS ~~uRw~. Thti itnplant \\:\A completely absorbed and replaced by- normal hone without, sequestration. In IM:! .I lauptli’” reported his experience with plaster of Paris implants in the trcatmc,llt ot’ right, patients with dei’ects caused by surgical removal of benign t,umors, t,wo patients with fresh frac+urcs and six patients with nonunitcltl fract,urcx HP hclic~\-rd that the implants stimulated regeneration of bone. An interest.ing papc’r by KovaceCc,20 which appea~d in 1953, described the results of diaphysect~omy in three patients suff’ering from hmnatogenons osteornyclitis of 1110 tibia. Koraccvic filled the surgical dcfccts with cylinders of plaster of Paris to whic*h penicillin and sulfonamide powdrr had h~cn add&l. Ilcaling with ~~tconsiitution of the diaphysis occurrc~l in Mach GW. In I!)% J’elticr and Lillo,” the first American investigators t,o use plaster ot Paris, rrported experiments in which plaster cylinders, sterilized 1)~ hcat, for 48 hours at 200’ C., were inserted into surgical subperiosteal defects prepared in t.hc> radii of mongrel dogs. They c~oncludcd that thr diaphyseal resection \VHSlarge c~~ongh to preclude spontaneous regenc>ration. They found no direct. ~lationship hetn-ccn the occurrence of hone rcyair and the length of the plaster-filled dcfccts. There was no apparent dift’ercncc hrtn-cm commercial grade and dental grade plaster of Paris cylinders. In t’ourtccn dogs with snhperiosteal defects, complctc~ disappearance of the material was Sean radiographically in 45 to 72 days, ant1 complctc regeneration of the dcfrcts occurrod in approximately 3 months. 7’1-1~ disappearance of the plaster was accompanied by increased strum calcium in t hc dogs. As radiographic and histologic bone formation progressed, calcium lcvc~ls rc4urncd to normal. This study includctl radiographic and histologic c~idcnrc of complete> resorption of the pl&er. ?Jinc animals showc>d some bone t’orrnation : complete regeneration of the tlefcrt occurred in three of the nine animals, 11~1, in five dogs there was no rcplaccment by hone. The absorption of thcsct large masses of plaster did not appear to be associated with an increase in the nnmbc~l of wound infections or complications of healing. In a second study, the defects XVcreprepared to include remora1 of adjacent pcriostcal t.issuc. There \vas partial rc~generation in two of the nine animals studied. No regeneration could he se(‘n. histologically or radiographicall~-, in the seven remaining animals. Tn al 1 animals, c~ornplcttr resorption of plaster was noted. The plaster alone was not ostcog:cni(d. IVilS ilWPl~'lYlt~d. hut with periostcum bone fornlation In the same pear (1’355), Nikulin and Ljuho-\-ic!’ concluded that plaster ot Paris implanted in an area oi’ subperiosteal boric resection in rabbits produced no more reaction in the tissue than is normally present in an uninfected fracture. They added t)hat regeneration of complctcly normal hone occurs clarlicr with They also not,etl that elevat(~d plaster implant,s than with alltogrnous grilftS. scrurn (x;ll(‘itlm and s(arum alka lint> phos1)hatast: Irvrls ;~~~~~mpanyabsorptio~~ ot t hcl plnstt>r, but no ill cfYects attril)ntal)lr to the nlatcrial c~~~ltl h s(x(LILin ~~d,jawnt tissllcls 01’ Ol’gallS. The 1’157 StLltly 1)4. JI ~lliO~~~ttlll~l~il illltl AlC'lltil," \VtlO illlJ)Iil~lttYl l)lastel~ of Paris cylinders in the diaphysc>s 01’ goats, c&onfirmed thcl rc>snlts ol)tained by Peltier and IAllo.2’
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Peltier, Bickel, Lillo, and Thein”” did some additional animal experimentation 1~7, ~vhcn thc>y packed plaster of Paris into nrctaphyscal dcft~cts in six mongrel dogs. Complete regeneration occurred in five dogs ; the sixth dog showc~tl sonl~l boric gro\vth, but reI~laecmcnt. was incomplrt,ti. I~Iistologica11y, S111i1.11]M rtic*los 01’ plaster \v(:rc seen in the boric matrix but no foreign body reaction could bc demonstrated. The regcncration of bone was normal in every respect, and there was ostcoclastic resorption of bone along the wall of the defects in the early stages of healing. In 1958 Peltier and 0rn2” described experiments in which autogcnous and homologous bone grafts, each combined with small pellets of plaster of Paris? were used to fill defects in dogs similar to those discussed in the I956 paper (that is, the periosteum was removed with the section of diaphysis). They Connd that autogenons bone grafts were more successful than homologous grafts. The addition of plaster of Paris did not seem to aid or inhibit the healing of defects filled with autogenous bone. Homologous grafts with plaster, however. seemed to promote healing more than the control homologous grafts without plaster, but not to the level of statistical significance. They concluded that, in case of infection, the plaster of Paris can drain out in the pus and does not remain as a sequcstrum. In 1959 Kovacevic reaffirmed his irnpressions of the great value of plaster with antibacterial additives, o he reported clinical SLIC~T~H in t,hc treatment of osteomyelitis. In 1959 Peltier x discussed the results of experimental implantation of plaster of Paris in human beings. IIe reported that the rise in serum calcium noted in his previous animal experiments did not OCCLW in the clinical series. Absorption of the plaster took place in weeks, in cont,rast to the months required for resorpt.ion of autogenous bone. Peltier’s clinical impression was that the material contributed significantly to the rapid healing of the lesions. In 1959 the Russian authors, KorendiasevZG and Elizarovskii,25 reported results in both human and animal subjects which corroborated KovacevicV’ findings. The second American study of plaster was conducted by BelIz in 1960. Previous experimental and clinical results, which suggested that the s~wc~ss of bone grafts depended partially on rapid resorption of the graft material by the host, had stimulated him to make a comparative study of the absorption rates of rariOLIS graft materials and bone substitutes. Radiographic examination of implants 7 mm. in diameter and 3 mm. in thickness placed between the heads of the gastrocncmius muscle in adult mongrel dogs showed that plaster of Paris implants were the most quickly absorbed, taking an average of 4.7 weeks. Autogenous bone implants were absorbed in 7 weeks, homologous bone took 10 weeks, and bovine heterogenous bone was not resorbed in less than lll,$ weeks. E’reeze-dried boric, anorganic bone, and polyurethane foam implants were absorbed much more slowly, if at all. Bell noted that the larger the grain size of any of these materials, the slower the resorption. A report of considerable interest to dentists was published in April, 19~1, 1)~ Lobourg and Biou,?* who used plaster of Paris to fill the wounds remaining after odontectomy of impacted third molars as well as other osseous defects in t,hc mandible and maxilla. In 3 or 4 weeks following implantation, radiographic evidencc sho\vcd that the mass of plaster was completely resorbed and healing ivies greatly acccleratcd as compared to controls, They suggested that the material ilr
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constituted a favorable environment for the regeneration ability to supply inorganic ions for the repair process.
0,s.. O.M. ‘k 0.1’. Akty, IMfi of bone b~~c;lu~~~ of its
HISTOLOGIC STUDY IN RABBITS In a histologic study that I made in 3961, 2[1bilateral identical defects were surgically created in ten rabbit mandibles. Defects on t,he right side were filled with liquid plaster, and the left-side control defect,s were allowed to fill with blood. Animals were killed at designated intervals, and the mandibles \v(bre examined histologically and clinically. The defects in the animals killed 4 days after operat’ion revealed bilateral hemorrhage, necrotic bone fragments, moderate inflammation, fibrin, fibroblastic and vascular bud proliferation, osteoclastic activity, and some hyalinization of the granulation tissues. Evidence of greatcl: osseous repair was seen in the control defect. It was concluded that, during the early stages of bone repair healing was inhibited by the pressure of the solidified plaster against the margins of the defccm. After t,his initial period of 4 to 6 days, the tissue fluid in the area began marginal resorption of the plaster mass. Osseous regeneration was accelerated in all of the subsequent experimental defects, as evidenced by the preponderance of osteoid and new bone in the areas of l)last,cr implantation as compared with the controls. In the rabbit killed 22 days aftci operation, the experimental defect had flllcd with bone, while fibroblastic and osteoid activity was still evident on the control side. In the 54day specimens trabeculae were thicker and more extensive in the cxperiment,al defects. Clinical observations consistently reflectSed these histologic findings. It, was concluded that normal bone regenerat,ion and restoration of morphologic contour can be enhanced by implantation of liquid plaster in surgically prepared defcct,s in the mandibles of rabbits, without foreign-body giant-cell reactions. It was suggested that the hemostatic and odontogenic effects of plaster noted in the study warrant, further investigation and that the material might be useful as a vehicle tjo carry medication into areas of infection, where absorption may allow sustairwd I*t~ltvwt~ of the medicament. A radiographic study of plaster implants was reported by Calhoun and Blackledge”” in 1962. Three corresponding surgical dcfecm mere created in the right mandibles of scvcn mongrel dogs. Liquid plaster was placed in the fii?;t defect and Gelfoarn sponge in the sec,ond. The third defect was allowed to fill with blood and was used as a control. The mandibles were radiographed at various intervals. On the sixtiet,h postopcrat,ivc day, the defect tilled with plaster appeared slightly more rndiopaque. Calhoun and Blackledge concluded that plaster of Paris can be implanted in the mandibles of dogs without dctrinirnt and that it may enhance healing of boric. In 1963 Calhoun and associates”’ implanted standardized blocks of plaster in surgical ostectomy defects of twelve dogs. A similar operation without plaster insertion was performed on twelve control animals. In 50 per cent of the experimental animals killed up to 120 days postoperatively, there was clinical union of the surgical fracture ; 25 per cent of the control anirnals demonstrated similar clinical repair. A more comprehensive study of his previous work was reported by Bell”’
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in 1964. Resorption of ninety intramuscular implants of eleven different types of bone and bone substitutes was studied radiographically in t,wenty-two dogs. On the basis of mean resorption time, the implants were resorbed in the following order: (1) plaster of Paris, (a) autogenous canccllous bone, (3) cathode-raysterilized canine cancellous bone, (4) cathode-rap-sterilized human cancellous bone, (5) homologous canccllous bone, (6) fetal bovine bone, (7) bovine cancellous bone, (8) freeze-dried cancellous bone, (9) collapatite, (10) anorganic bone, and (11) polyurethane foam. Bell concluded that autogenous bone is the material of choice for bone regeneration, since it may actircly contribute cellular elemerits-osteoblasts with osteogenic potency and intact organic matrix which may permit new bone growth from the graft itself. He implies that plaster would be a second choice because of its rapid resorption. In a subsequent histologic study of various intramuscular implants, Bell and SiW3 concluded that plaster implants were the first to be resorbed. Anorganic bone and polyurethane foam did not resorb. The histologic response to autogenous, homologous, human and canine cathode-ray-sterilized, and bovine bone was similar. Calhoun and colleagues,3’ in 1965, studied forty dogs with surgical fractures produced by excision of a segment of mandible-twenty with plaster implants and t,wenty control animals. Clinical, roentgenographic, and microscopic union occurred in twelve experimental animals but in only nine control dogs. CLINICAL
ORAL STUDY
A study in which sterile plaster of Paris (Ethicon) pellets were implanted into cyst cavities, impaction wounds, extraction sites, defects remaining after surgical removal of benign tumors, and in alveolar undercut areas of seventy-five patients at the West IIayen Veterans Administration Hospital is being prepared for publication. Large defects healed completely in a relatively short time. Restoration of morphologic contour and small increases in alveolar ridge dimensions hare been observed. Postoperative infection was rare, but when it occurred the plaster was easily removed or drained out with the pus and eventual healing followed resolution of the i&‘ection by routine therapy. Serum calcium levels were not altered by plast,er implantation. Plaster implants compared favorably with autogenous bone and eliminated the discomfort and difficulty of the additional operation necessary to procure ili;tc. crest or rib bone. DISCUSSION Mechanisms
of action
of plaster
of Paris
There appears to be unanimous agrcemcnt among t,hose experimenting with the use of plaster of Paris in bone defects that the material is beneficial t.o osseous regeneration. The mechanism by which t,his benefit is achieved, however, is a point of disagreement. EIauptlilg believed that plaster of Paris ha.d a stimulatory effect on bone regenerat.ion. Nikulin and Ljubovi? maintained that the material does not stimulate osteogenesis in the absence of bone or periosteum but they did not, deny that, in the presence of bone or periosteum, plaster of Paris may pro-
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O.M. hlay.
d 0.1’. I%Xi
mote osteogenesis. Peltier!’ is not. wil I ing to iIttl*iblltc’ 111r propt~l*t,I- (II’ oss(‘oI1s stimulation to the material. 110 states that plaster of I’ai’is acts prirrl;rrily as a ITlOSt importmt is its 01’ bsorption, space filler WllOSe which closely coincides with the r;rtcl \vlticll ttm Iwnc~ em gt’mv into it tlvt’wt. ~i(l~il.?ltil~('
tliti
Ill'itl
t'iItC
ii
ilt
Plaster
as a space
filler
The concept that a space filler facilitates regcnera.tion of bone is acceptable to ISowe and Killey,’ who believe that a healthy clot is necessary for osseous repair. The organization of the clot in large defects or in the presence of infection depends on an adequate blood supply. The risk of granulation tissue breakdown or necrosis and delayed healing rnay be decreased by the use of an innocuous space-occupying material to restrict the primary hematoma to the periphery of the lesion. Ham35 has stated that regeneration of osseous defeects is not dependent, on the organization of the primary hematoma. It is possible that Ham would not agree that a space-occupying material is beneficial to bone healing. Although his view cannot be completely disregarded, his denial of the importance of the clot, represents a minority opinion. Pelt,ier’s proposal that a space filler is beneficial to healing is endorsed by the majority of those st,udying bone regenerat,ion. Absorption
of plaster
of Paris
BelIZ has stated that previous experimental and clinical results suggest that the success of bone grafts depends partially on rapid absorption of the graft by the host. In his study of materials used to fill osseous defects, he reported that plaster of Paris was absorbed twice as fast as autogenous bone and many times faster than homologous and heterogenous bone. Bell has reported complete absorption of plaster in approximately 33 days. In Peltier’s experiments complete absorption took from 45 to more than 72 days. The ma.rked difference in absorption times reported in the two studies may he explained by pointing out that, Bell implanted plaster in t,he well-vascularized gastrocnemius musculature whereas Peltier attempted to use it in J)OOt*J)’ vascularized bone defects. Plaster
as a source
of inorganic
ions
Peltie? has asked whether the absorption of plaster of Paris by the tissue creates a source of calcium and phosphorus ions for bone formation. This brings up the controversy surrounding the role of calcium salt implantation in the healing of bone defects. Peltier and assoriat&” and Lacroix”G have reviewed the literature and have found that, since 1920 when Albee and Morrison reported that triple calcium phosphate had the ability to stimulate osteogenesis when implanted into surgically prepared defects, there have been two groups reporting divergent findings. Albee and Morrison, Murry, Shands, Schram and Fosdick, and Kay and Ward all reported that st,imulatory activity resulting in accelerated healing of bone is associated with local implantation of calcium salts. Key, St.ewart, IIaldeman and Moore, and Huggins did not find accelerated healing after calcium salt implanta,tion. The apparently contradictory results were clarified by I,acroix, who postulated that hyperconcentration of calcium salts in the area of injury is necessary for bone regeneration. However, without an organizing sub-
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stance, correct pH, and temperature, excess salts cannot aid healing. Rowe and Killeyl explained that the concentration of calcium and phosphorus in serum is such that a state of saturation exists. Excess ions are normally taken up by plasma proteins and excreted. If the concentrations of these ions can be increa.sed locally by phosphatase enzymes in the presence of calcium salts, bone formation can be accelerated if enough suitable organic matrix is present. The source of ions is irrelevant, Implanted salts cannot be utilized by the tissues unless there are functioning osteoblasts which are secreting adequate amounts of phosphatase enzyme. Rowe and Killey believe that sufficient inorganic ions necessary for the repair of fractures are supplied by the absorption of adjacent bone subsequent to the osteoclasis of the bone edges. This may not be true if the defects are large and bone loss is extensive. Implantation of calcium salts may accelerate healing if enough organic matrix and functioning osteoblasts are present,. The studies by Ray and Ward36 in 1952 seem to support this hypothesis. Nikulin and Ljubovid and Peltierg found elevated serum calcium levels associated with absorption of plaster of Paris, which indicates that plaster has the potential of elevating local concentrations of inorganic calcium and phosphorus ions. In Peltier’s clinical studies, however, no such elevation of serum calcium was seen. The animals with increased calcium levels had no clinical manifestations of hypercalcemia. There is unanimity of belief that plaster of Paris is a completely safe implant material as demonstrated by the absence of reports of ill effects attributable to the material. It is also agreed that the material does not inhibit bone growth and repair, that it may be implanted in infected areas, and that it can be beneficial to the healing process if periosteum or bone is present as a source of osteoblasts. Peltier has noted the absence of foreign-body giant cells, a finding that supports the unanimous contention that the material is well tolerated by the tissues. The results reported by Dreesman, Kofmann, Nystrom, Petrova, Edburg, Nordmann, Nielson, Kovacevic, Korendiasev, Nikulin and Ljubovic, and Peltier in their studies of the effects of plaster of Paris implanted in infected wounds show that the material does not interfere with healing. Kovacevic used plaster as a vehicle for penicillin and sulfonamide powder and reported healing and reconstitution of bone in every case; he recommends this method for osteomyelitis therapy. Peltier, although he did not use any a,ntibiotic additives in his studies, states in his latest article that plaster of Paris is the material of choice when infection is present or anticipated. SUMMARY A review of the literature on the use of plaster of Paris in osseous yegeneration has revealed that this simple, inexpensive substance offers many advantages as an implant for filling defects in bone. The material is stable, readily available, and can be easily sterilized. It is well tolerated by hard and soft tissues and can be used effectively in both endochondral and intermembranous bone defects. Its rapid rate of absorption, which coincides with the rate of new bone growth, makes it especially useful in repairing large defects. It does not stimulate foreign-body giant-cell activity and is useful in the treatment of infected osseous defects. In dentistry, plaster of Paris may be particularly useful as a vehicle to carry
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medicaments into infected aI’(‘ils IVII(~W absorption m;t~- WIIN: prolong(~l t7~lwsc of the medicament. Plaster (‘ill1 also IJO used rffectivcly jn extraction or cystic wounds and in surgical and ostcwnlyc~litic dofccts to facilitate r(Lst(jI*i1Iion 01’ noTma morphologic contour a11t1 to rcl)lCld wsor’l)ed alveolar ridgw. REFERENCES
Rowe, M. L., and Killey, II. C. : Fractures of: the Facial Skeleton, Baltinww, 1955, \\‘illiams & Wilkins Company, pp. 718-734. Kruger, Gustav (editor) : Tcxthook of Oral Surgery, St. Louis, 1959, The C‘. v. MOSllJ Company, pp. 406-423. Moss, M. L.: Bone Graft Substitutes, New York State D. J. 24: 353-354, 1958. Huggins, C. B., MeCarroll, Ii. R., snd Blocksom, B. H.: Experiments on the Theory of Osteogenesis: The Influence of Local Calcium Deposits on Calcification, The osteogenic stimulis of epithelium, Arch. Surg. 32: 915-931, 1936. 5. Macewin, W.: Cited in Lacroix, P., and Gilder, 8.: The Organization of Bones, Philadelphia, 1951, The Blakiston Company, p. 198. C., and Zingg, W.: Polyurethane 6. Macoomb, R. K., Hollenberg, Foam (Ostamer j : Its l’sc in Experimental Animals and the Iuvrstigation of Its Tissue Reactions, Surg. Forum 11: 454-456, 1960. 1\fter Odontectomy, Am. J. 7. (a) Thoma, K. H.: A Sew hfethod of Space Obliteration Orthodontics and Oral Surg. 32: 273, 1946. of Cavities (b) Thoma, K. II., and Sleeper, B. L. : Gelatin Sponge in the Obliteration Resulting From the Excision of Cysts and Tumors of the Jaq ORAL SURG., ORAL MED.
8. 9. IO. Il. 12. 13. 14. 15. 16. 17. 18. 19. “(1. 21. 22. 23. 24. 25. 26. 27. 28.
& ORAL
PATH.
1: 24, 1948.
(c) Thoma, K. II.: Oral Surgery, cd. 4, St. Louis, 1963, The C. V. Mosby Company, p. 865. Mondolfo as translated in abstract form in: United States Armed Forces Medical Library; The structure, Composition and Growth of Bone 1930.1953, Washington, 1955, Government Printing Office, p. 143. Peltier, L. F.: The USC of Plnstw of Paris to Fill Dofccts in Bone, Clin. Orthoprdirs 21: l-29, 1961. Martin, E.: Zur Ausfiilling van Knochenhiihlcn mit todtcm Material, Zcntrnlljl. Chir. 21: 193-200, 1894. Kofmann, 8.: Gips als Plo~~ll~enmaterial, Zentralbl. Chir. 52: 1817-1818, 1925. Zentralbl. Chir. 52: 993, 1925. Oehlecker, F. : Uber KnBchenplombc, Nystrom, G.: Plugging Bone Cavities With Kivanol-Plaster Porridge, Acts chir. scandinav. 63: 296, 1928. Petrova, A. : Gipsfiilling ran Kniichenh6hlen bci Osteomyelitis, Zentralorgan f. d. ges. C’hir. 43: 485, 1928. Edberg, E.: Some Experiences of Filling Osseous Cavities With Plaster, Acta chir. seal]dinav. 67: 313-319, 1931. der Lunatumnekrose und Bhnlicher Erkrankunaen mit Nordmann. 0. : Die Behandlune‘ der Gipspiombe, Zentralbl. ChirT66: 534839, 1939. Nielson, A. : The Filling of Infected and Sterile Bone Cavities by Means of Plaster of Paris, Acta chir. seandinav. 91: 17-27, .1944. Berner, A.: Un cas de kystb mandibulaire plombC au pl%trc, Schweiz. med. Wchnschr. 25: 183.185, 1944. HBupt,li, 0. : Die Gipsplombe zur Ausfiillung von fehlendcm Knochengewebe, Schweiz. mcXtl. Wchnschr. 82: 161:168, 1952. Kovacevic, B. : Ein Beitrag zum Problem der Jlamartogenen Osteomyeliti?, Auk klin. (Xir. 276: 432-443. 1953. Peltier, L. F., and Lillo, R.: The Substitution of Paster of Paris Rods for Portions of the Diaphysis of the Radius iu Dogs, Surg. Forum 6: 556-558, 1955. Mukopadhaya, B., and Mehta, M. J.: Espcrimental Diaphysectomy; a Preliminary Review. Indian J. Surg. 6: 438-440, 1957. Peltier, L. F., Bickel, E. Y., Lillo, R., and Thcin, 31. S:.: The Use of Plaster of Paris to Fill Defects in Bow, Ann. Surg. 146: 61-69, 1957. Pelticr, L. F., and Orn, D.: The Effect, of the Addition of Plaster of Paris to Butologous a.nd Homologous Bone Grafts in Dogs, Surg. Formn 8: 571-574, 1957. Peltier, L. F.: The Use of Plaster of Paris to Fill Large Defects jn Bone, A1m. J. Surg. 97: 311-315, 1959. Korendiasev, M. A.: The Significance of Plaster of Paris Filling to Obliterate Bone Cavities and Defects, Ortop. Traum. Protez. 20: 38-23, 1959. Bell, W. I-I.: Resorption Characteristics of Bone and Plaster, J. D. Res. 39: 727, 1960. of Plaster of Paris in Surgical Cavities of Lebourg, L., and Biou, C.: The Imbedding the Jaws, Bern. Hop. Paris 37: 1195-1197, 1961.
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Plaster as bone substitute
681
29. Bahn, S. L.: An Investigation Into the Use of Plaster of Paris in Filling Defects in Membranous Bones, Master’s Thesis, Boston University School of Medicine, Boston, Mass. 1962. 30. Calhoun, N. R., and Blackledge, G. T.: Plaster of Paris Implants in the Mandible of Dogs, Quart. Nat. D. A. 21: 13-15, 1962. 31. Calhoun. N. R.. Greene. G. W.. and Blackledne. G. T.: Effects of Plaster of Paris Imnlants L on Osteogenesis in the’ Mandible of Dogs, J”. ‘Res. 42: 1244, 1963. 32. Bell, W. H.: Resorption Characteristics of Bone and Bone Substitutes, ORAL SURG., ORAL MED. 8s ORAL PATH. 17: 650.657. 1964. 33. Bell, W. H., and Sills, A. H.: Histologic Study of Intramuscular Implants of Bone and Bone Substitutes, J. D. Res. 5: 828, Supp., 1964 (Abst.). 34. Calhoun, N. R., Greene, G. W., and Blackledge, G. T.: Plaster: A Bone Substitute in the Mandible of DOES. J. D. Rrs. 44: 940-946. 1965. 35. Ham, A. W.: H%ology, ed. 3, Philadelpliia, 1957, J. B. Lippincott Company, p. 369. of Bones. Philadelphia. 1951. The Blakixton 36. Laeroix. P., and Gilder. S.: The Organization Company, pp. 197-199. ’
T
ADMINISTRATION
HOSPITAI,
hc extensive literature on the replacement of osseous tissue recommends the US: of bone and bone substitutes for filling defects caused by neoplasms, cysts, trauma, infection, congenital disease, and surgical intervention. The aims of replacing OSS~OLIS structure are preservation of morphologic contour, restoration of mechanical strength and function, elimination of dead space to reduce postoperative infection and thus promote healing, prevention of ingrowth of soft tissue, and enhancement of retention of prosthetic devices. When conditions a.re favorable for regeneration of bone, such goals can often be achieved. However, in many large lesions or defects or in the absence of favorable conditions in smaller defects, the morphologic contour is not completely restored and the bone remains weakened for long periods until complete healing can occur. The breakdown of the center of the clot or granulation t,issue and a predisposition to infection impede the normal processes of healing.] Regeneration of bone requires an adequate supply of many elemenm from blood and tissue fluid, including protein, inorganic ions (mainly calcium and phosphorus), hormones, enzymes, vitamins, and oxygen. Also functioning cellular elements, including macrophages, platelets, differentiating mesenchymal and endothelial cells, as well as the phosphatase complex, are needed. Temperature, pH, osmolality, and other physical conditions must bc carefully controlled. Factors that interfere with healing, such as movement of adjacent segments, chemical or physical irrit,ation, contamination, and infection, must he eliminated if osseous regeneration is to take place.’ Most. of the surgical interventions proposed in the lit,erature are variations of the primary at,trmpts at bone implantation made by Van Walt,her in I820 and of the grafting of osseous tissnc by Macewin in 1878.’ The orga.nic bone used in these early studies was autogenous, homologous or heterogenous.2 Anorganic derivatives of bone have been prepared and used.” Ma.ny investigators have experimented with such alloplasts (bone substitutes) as polyvinyl sponge,” calcium salts4 glass,5 polyurethane derivatives6 absorbable gelatin sponge (Gelfoam) with penicillin added,’ chondroitin sulfate, various plastics, and acrylics,* alcoholic and acidic extracts of bone and pcriosteum,” soft tissues such as urinary mucosa,4 sera,s total embryonic extracts,8 and meta1s.2 NOIK cartilage,2 antireticulotoxic of the materials studied has been universally successful in achieving the physiologic goals mentioned previously. The ideal material would also satisfy the prac-
672
Volume 21 Number 5
Pluster as hove substitute
tical requirements of ease of manipulation, minimal trauma to the patient, economy. The quest for such a material still continues.
673 and
PLASTER OF PARIS
The first report on the use of plaster of Paris to fill defects in bone was published in 1892 by Dreesman (reviewed by Peltierg), who described the results of filling osseous defects with plaster in eight patients. In three of six patients, tubrrculous cavities in bone were complet,ely filled in with new bone. In one patient with two tuberculous cavities, one cavity healed but the other did not. Two patients had tuberculous defects that did not heal. In the last two patientsone with a cavity due to osteomyelitis and the other with a surgical defect caused by removal of an enchondroma of the fifth metacarpal-complete bone regeneration occurred after implantation of plaster into the defects. Two years later Stachow filled operative defects in the long bones of sheep with plaster of Paris and closed the periosteum over the implant.. 9 He observed complete absorption of the plaster and regeneration of normal bone; only a slight reaction to the plaster of Paris was not.ed. In the same year Mart’in’o carried out similar experiments with dogs. Further interest in the material was not evident until 1925, when a report by Kolfmannll told of the successful use of plaster of Paris to fill osseous cavities in many patients, including one with a tibia1 abscess operated upon in 1912. Oehlecker,l” in discussing Kofmann’s paper, urged that this method be used more extensively in treating bone defects associated with resection of benign tumors and pointed out that plaster o’f Paris was well tolerated by the tissues. In 1928 Nystrom13 reported on the results observed in four patients treated with this material. Three patients showed complete uneventful healing; in the fourth cxtjrusion of a. portion of the plaster of Paris from the wound was followed by healing. In the same year, Petrova,l* working at the Institute of Traumatology in Leningrad, added 10 per cent Riranol or 10 per cent Kreolin, both antiseptics, t.o plaster of Paris before inserting it into the surgical defects of twenty-eight dogs and found that the dcfccts in all the dogs healed. In ten dogs with uninfected wounds there was complete restitution of the normal bony architecture, including the marrow cavity, at the end of 6 to 8 months. The average time r+ quired for the same results in eighteen dogs with infected wounds was 10 months. In 1930 Edburg’” reported a study of the use of plaster of Paris in six patients, including two with dentigerous cysts, one with an abscess of the ilium, one with a cavity caused by osteomyelitis, and two with tuberculous cavities in hone. Solid healing occurred in the last three patients, but in the first three the mat,erial was extruded. Nordmann,16 in 1939, reported success in treating one patient with aseptic necrosis of the lunate bone and another with aseptic necrosis of the cuboid bone by curettage and packing of the en\-itics with the hemihydratc of calcium sulfate (plaster). In 1944 an extensive report by Nielson17 described the use of plaster of Paris in fourt,cen patients with uninfected cavities and in sixteen patients with infected osseous defects, two of which were tuberculous. Nine patients had been followed for at least 4 years, and none developed any complications at.tributable to the
674
Bahn
O.S.,O.Jl.‘~O.L’. \I:I,v.
I Wili
implanted material. Good results WCL’(’reported in all (:;ws. I%ern~r,~’ ill tllc, S:IIII(’ JWW, treated a patient with ;a.large mandibular cyst 1,~ curettage ant1 im~)lant;~lion of a 1 to 1 mixture of plastrr ot’ Paris ;lnd OS ~~uRw~. Thti itnplant \\:\A completely absorbed and replaced by- normal hone without, sequestration. In IM:! .I lauptli’” reported his experience with plaster of Paris implants in the trcatmc,llt ot’ right, patients with dei’ects caused by surgical removal of benign t,umors, t,wo patients with fresh frac+urcs and six patients with nonunitcltl fract,urcx HP hclic~\-rd that the implants stimulated regeneration of bone. An interest.ing papc’r by KovaceCc,20 which appea~d in 1953, described the results of diaphysect~omy in three patients suff’ering from hmnatogenons osteornyclitis of 1110 tibia. Koraccvic filled the surgical dcfccts with cylinders of plaster of Paris to whic*h penicillin and sulfonamide powdrr had h~cn add&l. Ilcaling with ~~tconsiitution of the diaphysis occurrc~l in Mach GW. In I!)% J’elticr and Lillo,” the first American investigators t,o use plaster ot Paris, rrported experiments in which plaster cylinders, sterilized 1)~ hcat, for 48 hours at 200’ C., were inserted into surgical subperiosteal defects prepared in t.hc> radii of mongrel dogs. They c~oncludcd that thr diaphyseal resection \VHSlarge c~~ongh to preclude spontaneous regenc>ration. They found no direct. ~lationship hetn-ccn the occurrence of hone rcyair and the length of the plaster-filled dcfccts. There was no apparent dift’ercncc hrtn-cm commercial grade and dental grade plaster of Paris cylinders. In t’ourtccn dogs with snhperiosteal defects, complctc~ disappearance of the material was Sean radiographically in 45 to 72 days, ant1 complctc regeneration of the dcfrcts occurrod in approximately 3 months. 7’1-1~ disappearance of the plaster was accompanied by increased strum calcium in t hc dogs. As radiographic and histologic bone formation progressed, calcium lcvc~ls rc4urncd to normal. This study includctl radiographic and histologic c~idcnrc of complete> resorption of the pl&er. ?Jinc animals showc>d some bone t’orrnation : complete regeneration of the tlefcrt occurred in three of the nine animals, 11~1, in five dogs there was no rcplaccment by hone. The absorption of thcsct large masses of plaster did not appear to be associated with an increase in the nnmbc~l of wound infections or complications of healing. In a second study, the defects XVcreprepared to include remora1 of adjacent pcriostcal t.issuc. There \vas partial rc~generation in two of the nine animals studied. No regeneration could he se(‘n. histologically or radiographicall~-, in the seven remaining animals. Tn al 1 animals, c~ornplcttr resorption of plaster was noted. The plaster alone was not ostcog:cni(d. IVilS ilWPl~'lYlt~d. hut with periostcum bone fornlation In the same pear (1’355), Nikulin and Ljuho-\-ic!’ concluded that plaster ot Paris implanted in an area oi’ subperiosteal boric resection in rabbits produced no more reaction in the tissue than is normally present in an uninfected fracture. They added t)hat regeneration of complctcly normal hone occurs clarlicr with They also not,etl that elevat(~d plaster implant,s than with alltogrnous grilftS. scrurn (x;ll(‘itlm and s(arum alka lint> phos1)hatast: Irvrls ;~~~~~mpanyabsorptio~~ ot t hcl plnstt>r, but no ill cfYects attril)ntal)lr to the nlatcrial c~~~ltl h s(x(LILin ~~d,jawnt tissllcls 01’ Ol’gallS. The 1’157 StLltly 1)4. JI ~lliO~~~ttlll~l~il illltl AlC'lltil," \VtlO illlJ)Iil~lttYl l)lastel~ of Paris cylinders in the diaphysc>s 01’ goats, c&onfirmed thcl rc>snlts ol)tained by Peltier and IAllo.2’
Volume
Number
21
Plnstw
as bone substitute
675
5
Peltier, Bickel, Lillo, and Thein”” did some additional animal experimentation 1~7, ~vhcn thc>y packed plaster of Paris into nrctaphyscal dcft~cts in six mongrel dogs. Complete regeneration occurred in five dogs ; the sixth dog showc~tl sonl~l boric gro\vth, but reI~laecmcnt. was incomplrt,ti. I~Iistologica11y, S111i1.11]M rtic*los 01’ plaster \v(:rc seen in the boric matrix but no foreign body reaction could bc demonstrated. The regcncration of bone was normal in every respect, and there was ostcoclastic resorption of bone along the wall of the defects in the early stages of healing. In 1958 Peltier and 0rn2” described experiments in which autogcnous and homologous bone grafts, each combined with small pellets of plaster of Paris? were used to fill defects in dogs similar to those discussed in the I956 paper (that is, the periosteum was removed with the section of diaphysis). They Connd that autogenons bone grafts were more successful than homologous grafts. The addition of plaster of Paris did not seem to aid or inhibit the healing of defects filled with autogenous bone. Homologous grafts with plaster, however. seemed to promote healing more than the control homologous grafts without plaster, but not to the level of statistical significance. They concluded that, in case of infection, the plaster of Paris can drain out in the pus and does not remain as a sequcstrum. In 1959 Kovacevic reaffirmed his irnpressions of the great value of plaster with antibacterial additives, o he reported clinical SLIC~T~H in t,hc treatment of osteomyelitis. In 1959 Peltier x discussed the results of experimental implantation of plaster of Paris in human beings. IIe reported that the rise in serum calcium noted in his previous animal experiments did not OCCLW in the clinical series. Absorption of the plaster took place in weeks, in cont,rast to the months required for resorpt.ion of autogenous bone. Peltier’s clinical impression was that the material contributed significantly to the rapid healing of the lesions. In 1959 the Russian authors, KorendiasevZG and Elizarovskii,25 reported results in both human and animal subjects which corroborated KovacevicV’ findings. The second American study of plaster was conducted by BelIz in 1960. Previous experimental and clinical results, which suggested that the s~wc~ss of bone grafts depended partially on rapid resorption of the graft material by the host, had stimulated him to make a comparative study of the absorption rates of rariOLIS graft materials and bone substitutes. Radiographic examination of implants 7 mm. in diameter and 3 mm. in thickness placed between the heads of the gastrocncmius muscle in adult mongrel dogs showed that plaster of Paris implants were the most quickly absorbed, taking an average of 4.7 weeks. Autogenous bone implants were absorbed in 7 weeks, homologous bone took 10 weeks, and bovine heterogenous bone was not resorbed in less than lll,$ weeks. E’reeze-dried boric, anorganic bone, and polyurethane foam implants were absorbed much more slowly, if at all. Bell noted that the larger the grain size of any of these materials, the slower the resorption. A report of considerable interest to dentists was published in April, 19~1, 1)~ Lobourg and Biou,?* who used plaster of Paris to fill the wounds remaining after odontectomy of impacted third molars as well as other osseous defects in t,hc mandible and maxilla. In 3 or 4 weeks following implantation, radiographic evidencc sho\vcd that the mass of plaster was completely resorbed and healing ivies greatly acccleratcd as compared to controls, They suggested that the material ilr
676
Bahft
constituted a favorable environment for the regeneration ability to supply inorganic ions for the repair process.
0,s.. O.M. ‘k 0.1’. Akty, IMfi of bone b~~c;lu~~~ of its
HISTOLOGIC STUDY IN RABBITS In a histologic study that I made in 3961, 2[1bilateral identical defects were surgically created in ten rabbit mandibles. Defects on t,he right side were filled with liquid plaster, and the left-side control defect,s were allowed to fill with blood. Animals were killed at designated intervals, and the mandibles \v(bre examined histologically and clinically. The defects in the animals killed 4 days after operat’ion revealed bilateral hemorrhage, necrotic bone fragments, moderate inflammation, fibrin, fibroblastic and vascular bud proliferation, osteoclastic activity, and some hyalinization of the granulation tissues. Evidence of greatcl: osseous repair was seen in the control defect. It was concluded that, during the early stages of bone repair healing was inhibited by the pressure of the solidified plaster against the margins of the defccm. After t,his initial period of 4 to 6 days, the tissue fluid in the area began marginal resorption of the plaster mass. Osseous regeneration was accelerated in all of the subsequent experimental defects, as evidenced by the preponderance of osteoid and new bone in the areas of l)last,cr implantation as compared with the controls. In the rabbit killed 22 days aftci operation, the experimental defect had flllcd with bone, while fibroblastic and osteoid activity was still evident on the control side. In the 54day specimens trabeculae were thicker and more extensive in the cxperiment,al defects. Clinical observations consistently reflectSed these histologic findings. It, was concluded that normal bone regenerat,ion and restoration of morphologic contour can be enhanced by implantation of liquid plaster in surgically prepared defcct,s in the mandibles of rabbits, without foreign-body giant-cell reactions. It was suggested that the hemostatic and odontogenic effects of plaster noted in the study warrant, further investigation and that the material might be useful as a vehicle tjo carry medication into areas of infection, where absorption may allow sustairwd I*t~ltvwt~ of the medicament. A radiographic study of plaster implants was reported by Calhoun and Blackledge”” in 1962. Three corresponding surgical dcfecm mere created in the right mandibles of scvcn mongrel dogs. Liquid plaster was placed in the fii?;t defect and Gelfoarn sponge in the sec,ond. The third defect was allowed to fill with blood and was used as a control. The mandibles were radiographed at various intervals. On the sixtiet,h postopcrat,ivc day, the defect tilled with plaster appeared slightly more rndiopaque. Calhoun and Blackledge concluded that plaster of Paris can be implanted in the mandibles of dogs without dctrinirnt and that it may enhance healing of boric. In 1963 Calhoun and associates”’ implanted standardized blocks of plaster in surgical ostectomy defects of twelve dogs. A similar operation without plaster insertion was performed on twelve control animals. In 50 per cent of the experimental animals killed up to 120 days postoperatively, there was clinical union of the surgical fracture ; 25 per cent of the control anirnals demonstrated similar clinical repair. A more comprehensive study of his previous work was reported by Bell”’
Volume 21 Number 5
Plaster us bone substitute
677
in 1964. Resorption of ninety intramuscular implants of eleven different types of bone and bone substitutes was studied radiographically in t,wenty-two dogs. On the basis of mean resorption time, the implants were resorbed in the following order: (1) plaster of Paris, (a) autogenous canccllous bone, (3) cathode-raysterilized canine cancellous bone, (4) cathode-rap-sterilized human cancellous bone, (5) homologous canccllous bone, (6) fetal bovine bone, (7) bovine cancellous bone, (8) freeze-dried cancellous bone, (9) collapatite, (10) anorganic bone, and (11) polyurethane foam. Bell concluded that autogenous bone is the material of choice for bone regeneration, since it may actircly contribute cellular elemerits-osteoblasts with osteogenic potency and intact organic matrix which may permit new bone growth from the graft itself. He implies that plaster would be a second choice because of its rapid resorption. In a subsequent histologic study of various intramuscular implants, Bell and SiW3 concluded that plaster implants were the first to be resorbed. Anorganic bone and polyurethane foam did not resorb. The histologic response to autogenous, homologous, human and canine cathode-ray-sterilized, and bovine bone was similar. Calhoun and colleagues,3’ in 1965, studied forty dogs with surgical fractures produced by excision of a segment of mandible-twenty with plaster implants and t,wenty control animals. Clinical, roentgenographic, and microscopic union occurred in twelve experimental animals but in only nine control dogs. CLINICAL
ORAL STUDY
A study in which sterile plaster of Paris (Ethicon) pellets were implanted into cyst cavities, impaction wounds, extraction sites, defects remaining after surgical removal of benign tumors, and in alveolar undercut areas of seventy-five patients at the West IIayen Veterans Administration Hospital is being prepared for publication. Large defects healed completely in a relatively short time. Restoration of morphologic contour and small increases in alveolar ridge dimensions hare been observed. Postoperative infection was rare, but when it occurred the plaster was easily removed or drained out with the pus and eventual healing followed resolution of the i&‘ection by routine therapy. Serum calcium levels were not altered by plast,er implantation. Plaster implants compared favorably with autogenous bone and eliminated the discomfort and difficulty of the additional operation necessary to procure ili;tc. crest or rib bone. DISCUSSION Mechanisms
of action
of plaster
of Paris
There appears to be unanimous agrcemcnt among t,hose experimenting with the use of plaster of Paris in bone defects that the material is beneficial t.o osseous regeneration. The mechanism by which t,his benefit is achieved, however, is a point of disagreement. EIauptlilg believed that plaster of Paris ha.d a stimulatory effect on bone regenerat.ion. Nikulin and Ljubovi? maintained that the material does not stimulate osteogenesis in the absence of bone or periosteum but they did not, deny that, in the presence of bone or periosteum, plaster of Paris may pro-
678
Bahn
0.9..
O.M. hlay.
d 0.1’. I%Xi
mote osteogenesis. Peltier!’ is not. wil I ing to iIttl*iblltc’ 111r propt~l*t,I- (II’ oss(‘oI1s stimulation to the material. 110 states that plaster of I’ai’is acts prirrl;rrily as a ITlOSt importmt is its 01’ bsorption, space filler WllOSe which closely coincides with the r;rtcl \vlticll ttm Iwnc~ em gt’mv into it tlvt’wt. ~i(l~il.?ltil~('
tliti
Ill'itl
t'iItC
ii
ilt
Plaster
as a space
filler
The concept that a space filler facilitates regcnera.tion of bone is acceptable to ISowe and Killey,’ who believe that a healthy clot is necessary for osseous repair. The organization of the clot in large defects or in the presence of infection depends on an adequate blood supply. The risk of granulation tissue breakdown or necrosis and delayed healing rnay be decreased by the use of an innocuous space-occupying material to restrict the primary hematoma to the periphery of the lesion. Ham35 has stated that regeneration of osseous defeects is not dependent, on the organization of the primary hematoma. It is possible that Ham would not agree that a space-occupying material is beneficial to bone healing. Although his view cannot be completely disregarded, his denial of the importance of the clot, represents a minority opinion. Pelt,ier’s proposal that a space filler is beneficial to healing is endorsed by the majority of those st,udying bone regenerat,ion. Absorption
of plaster
of Paris
BelIZ has stated that previous experimental and clinical results suggest that the success of bone grafts depends partially on rapid absorption of the graft by the host. In his study of materials used to fill osseous defects, he reported that plaster of Paris was absorbed twice as fast as autogenous bone and many times faster than homologous and heterogenous bone. Bell has reported complete absorption of plaster in approximately 33 days. In Peltier’s experiments complete absorption took from 45 to more than 72 days. The ma.rked difference in absorption times reported in the two studies may he explained by pointing out that, Bell implanted plaster in t,he well-vascularized gastrocnemius musculature whereas Peltier attempted to use it in J)OOt*J)’ vascularized bone defects. Plaster
as a source
of inorganic
ions
Peltie? has asked whether the absorption of plaster of Paris by the tissue creates a source of calcium and phosphorus ions for bone formation. This brings up the controversy surrounding the role of calcium salt implantation in the healing of bone defects. Peltier and assoriat&” and Lacroix”G have reviewed the literature and have found that, since 1920 when Albee and Morrison reported that triple calcium phosphate had the ability to stimulate osteogenesis when implanted into surgically prepared defects, there have been two groups reporting divergent findings. Albee and Morrison, Murry, Shands, Schram and Fosdick, and Kay and Ward all reported that st,imulatory activity resulting in accelerated healing of bone is associated with local implantation of calcium salts. Key, St.ewart, IIaldeman and Moore, and Huggins did not find accelerated healing after calcium salt implanta,tion. The apparently contradictory results were clarified by I,acroix, who postulated that hyperconcentration of calcium salts in the area of injury is necessary for bone regeneration. However, without an organizing sub-
Volume 21
Number 5
Plaster as bone substitute
679
stance, correct pH, and temperature, excess salts cannot aid healing. Rowe and Killeyl explained that the concentration of calcium and phosphorus in serum is such that a state of saturation exists. Excess ions are normally taken up by plasma proteins and excreted. If the concentrations of these ions can be increa.sed locally by phosphatase enzymes in the presence of calcium salts, bone formation can be accelerated if enough suitable organic matrix is present. The source of ions is irrelevant, Implanted salts cannot be utilized by the tissues unless there are functioning osteoblasts which are secreting adequate amounts of phosphatase enzyme. Rowe and Killey believe that sufficient inorganic ions necessary for the repair of fractures are supplied by the absorption of adjacent bone subsequent to the osteoclasis of the bone edges. This may not be true if the defects are large and bone loss is extensive. Implantation of calcium salts may accelerate healing if enough organic matrix and functioning osteoblasts are present,. The studies by Ray and Ward36 in 1952 seem to support this hypothesis. Nikulin and Ljubovid and Peltierg found elevated serum calcium levels associated with absorption of plaster of Paris, which indicates that plaster has the potential of elevating local concentrations of inorganic calcium and phosphorus ions. In Peltier’s clinical studies, however, no such elevation of serum calcium was seen. The animals with increased calcium levels had no clinical manifestations of hypercalcemia. There is unanimity of belief that plaster of Paris is a completely safe implant material as demonstrated by the absence of reports of ill effects attributable to the material. It is also agreed that the material does not inhibit bone growth and repair, that it may be implanted in infected areas, and that it can be beneficial to the healing process if periosteum or bone is present as a source of osteoblasts. Peltier has noted the absence of foreign-body giant cells, a finding that supports the unanimous contention that the material is well tolerated by the tissues. The results reported by Dreesman, Kofmann, Nystrom, Petrova, Edburg, Nordmann, Nielson, Kovacevic, Korendiasev, Nikulin and Ljubovic, and Peltier in their studies of the effects of plaster of Paris implanted in infected wounds show that the material does not interfere with healing. Kovacevic used plaster as a vehicle for penicillin and sulfonamide powder and reported healing and reconstitution of bone in every case; he recommends this method for osteomyelitis therapy. Peltier, although he did not use any a,ntibiotic additives in his studies, states in his latest article that plaster of Paris is the material of choice when infection is present or anticipated. SUMMARY A review of the literature on the use of plaster of Paris in osseous yegeneration has revealed that this simple, inexpensive substance offers many advantages as an implant for filling defects in bone. The material is stable, readily available, and can be easily sterilized. It is well tolerated by hard and soft tissues and can be used effectively in both endochondral and intermembranous bone defects. Its rapid rate of absorption, which coincides with the rate of new bone growth, makes it especially useful in repairing large defects. It does not stimulate foreign-body giant-cell activity and is useful in the treatment of infected osseous defects. In dentistry, plaster of Paris may be particularly useful as a vehicle to carry
680
Bath
medicaments into infected aI’(‘ils IVII(~W absorption m;t~- WIIN: prolong(~l t7~lwsc of the medicament. Plaster (‘ill1 also IJO used rffectivcly jn extraction or cystic wounds and in surgical and ostcwnlyc~litic dofccts to facilitate r(Lst(jI*i1Iion 01’ noTma morphologic contour a11t1 to rcl)lCld wsor’l)ed alveolar ridgw. REFERENCES
Rowe, M. L., and Killey, II. C. : Fractures of: the Facial Skeleton, Baltinww, 1955, \\‘illiams & Wilkins Company, pp. 718-734. Kruger, Gustav (editor) : Tcxthook of Oral Surgery, St. Louis, 1959, The C‘. v. MOSllJ Company, pp. 406-423. Moss, M. L.: Bone Graft Substitutes, New York State D. J. 24: 353-354, 1958. Huggins, C. B., MeCarroll, Ii. R., snd Blocksom, B. H.: Experiments on the Theory of Osteogenesis: The Influence of Local Calcium Deposits on Calcification, The osteogenic stimulis of epithelium, Arch. Surg. 32: 915-931, 1936. 5. Macewin, W.: Cited in Lacroix, P., and Gilder, 8.: The Organization of Bones, Philadelphia, 1951, The Blakiston Company, p. 198. C., and Zingg, W.: Polyurethane 6. Macoomb, R. K., Hollenberg, Foam (Ostamer j : Its l’sc in Experimental Animals and the Iuvrstigation of Its Tissue Reactions, Surg. Forum 11: 454-456, 1960. 1\fter Odontectomy, Am. J. 7. (a) Thoma, K. H.: A Sew hfethod of Space Obliteration Orthodontics and Oral Surg. 32: 273, 1946. of Cavities (b) Thoma, K. II., and Sleeper, B. L. : Gelatin Sponge in the Obliteration Resulting From the Excision of Cysts and Tumors of the Jaq ORAL SURG., ORAL MED.
8. 9. IO. Il. 12. 13. 14. 15. 16. 17. 18. 19. “(1. 21. 22. 23. 24. 25. 26. 27. 28.
& ORAL
PATH.
1: 24, 1948.
(c) Thoma, K. II.: Oral Surgery, cd. 4, St. Louis, 1963, The C. V. Mosby Company, p. 865. Mondolfo as translated in abstract form in: United States Armed Forces Medical Library; The structure, Composition and Growth of Bone 1930.1953, Washington, 1955, Government Printing Office, p. 143. Peltier, L. F.: The USC of Plnstw of Paris to Fill Dofccts in Bone, Clin. Orthoprdirs 21: l-29, 1961. Martin, E.: Zur Ausfiilling van Knochenhiihlcn mit todtcm Material, Zcntrnlljl. Chir. 21: 193-200, 1894. Kofmann, 8.: Gips als Plo~~ll~enmaterial, Zentralbl. Chir. 52: 1817-1818, 1925. Zentralbl. Chir. 52: 993, 1925. Oehlecker, F. : Uber KnBchenplombc, Nystrom, G.: Plugging Bone Cavities With Kivanol-Plaster Porridge, Acts chir. scandinav. 63: 296, 1928. Petrova, A. : Gipsfiilling ran Kniichenh6hlen bci Osteomyelitis, Zentralorgan f. d. ges. C’hir. 43: 485, 1928. Edberg, E.: Some Experiences of Filling Osseous Cavities With Plaster, Acta chir. seal]dinav. 67: 313-319, 1931. der Lunatumnekrose und Bhnlicher Erkrankunaen mit Nordmann. 0. : Die Behandlune‘ der Gipspiombe, Zentralbl. ChirT66: 534839, 1939. Nielson, A. : The Filling of Infected and Sterile Bone Cavities by Means of Plaster of Paris, Acta chir. seandinav. 91: 17-27, .1944. Berner, A.: Un cas de kystb mandibulaire plombC au pl%trc, Schweiz. med. Wchnschr. 25: 183.185, 1944. HBupt,li, 0. : Die Gipsplombe zur Ausfiillung von fehlendcm Knochengewebe, Schweiz. mcXtl. Wchnschr. 82: 161:168, 1952. Kovacevic, B. : Ein Beitrag zum Problem der Jlamartogenen Osteomyeliti?, Auk klin. (Xir. 276: 432-443. 1953. Peltier, L. F., and Lillo, R.: The Substitution of Paster of Paris Rods for Portions of the Diaphysis of the Radius iu Dogs, Surg. Forum 6: 556-558, 1955. Mukopadhaya, B., and Mehta, M. J.: Espcrimental Diaphysectomy; a Preliminary Review. Indian J. Surg. 6: 438-440, 1957. Peltier, L. F., Bickel, E. Y., Lillo, R., and Thcin, 31. S:.: The Use of Plaster of Paris to Fill Defects in Bow, Ann. Surg. 146: 61-69, 1957. Pelticr, L. F., and Orn, D.: The Effect, of the Addition of Plaster of Paris to Butologous a.nd Homologous Bone Grafts in Dogs, Surg. Formn 8: 571-574, 1957. Peltier, L. F.: The Use of Plaster of Paris to Fill Large Defects jn Bone, A1m. J. Surg. 97: 311-315, 1959. Korendiasev, M. A.: The Significance of Plaster of Paris Filling to Obliterate Bone Cavities and Defects, Ortop. Traum. Protez. 20: 38-23, 1959. Bell, W. I-I.: Resorption Characteristics of Bone and Plaster, J. D. Res. 39: 727, 1960. of Plaster of Paris in Surgical Cavities of Lebourg, L., and Biou, C.: The Imbedding the Jaws, Bern. Hop. Paris 37: 1195-1197, 1961.
Volume Number
21 5
Plaster as bone substitute
681
29. Bahn, S. L.: An Investigation Into the Use of Plaster of Paris in Filling Defects in Membranous Bones, Master’s Thesis, Boston University School of Medicine, Boston, Mass. 1962. 30. Calhoun, N. R., and Blackledge, G. T.: Plaster of Paris Implants in the Mandible of Dogs, Quart. Nat. D. A. 21: 13-15, 1962. 31. Calhoun. N. R.. Greene. G. W.. and Blackledne. G. T.: Effects of Plaster of Paris Imnlants L on Osteogenesis in the’ Mandible of Dogs, J”. ‘Res. 42: 1244, 1963. 32. Bell, W. H.: Resorption Characteristics of Bone and Bone Substitutes, ORAL SURG., ORAL MED. 8s ORAL PATH. 17: 650.657. 1964. 33. Bell, W. H., and Sills, A. H.: Histologic Study of Intramuscular Implants of Bone and Bone Substitutes, J. D. Res. 5: 828, Supp., 1964 (Abst.). 34. Calhoun, N. R., Greene, G. W., and Blackledge, G. T.: Plaster: A Bone Substitute in the Mandible of DOES. J. D. Rrs. 44: 940-946. 1965. 35. Ham, A. W.: H%ology, ed. 3, Philadelpliia, 1957, J. B. Lippincott Company, p. 369. of Bones. Philadelphia. 1951. The Blakixton 36. Laeroix. P., and Gilder. S.: The Organization Company, pp. 197-199. ’