Healing After Removal of Benign Cysts and Tumors of the Jaws

Healing after removal of benign cysts and tumors of the jaws A radiologic appraisal

Tadahiko Kawai, DDS, PhD, a Shumei Murakami, DDS, PhD? Hiroko Hiranuma, DDS, c and Masayoshi Sakuda, DDS, PhD, d Osaka, Japan OSAKA UNIVERSITY, FACULTY OF DENTISTRY

A retrospective review of the radiographic findings after removal of benign jaw cysts (n = 31) and ameloblastomas (n = 24) was carried out. The radiographic features of the site margins and interior contents were classified into four categories. In most patients radiographic changes were detected between 1 and 4 months after removal of the lesion, and complete bone healing was found 4 months or more after surgery. Radiographic changes included "spiculed" or "trabecular" contents within the interior of the surgical site. The fourth month was found to be the optimum time for follow-up radiographic examination for the early detection of residual lesions. In nine (53%) of the patients who had ameloblastoma, recurrent lesions were noted within or at the periphery of the original surgical sites 6 to 10 years after the initial tumor removal. (ORAL SURG ORAL /IVIED ORAL PATHOL ORAL RADIOL ENDOD 1995;79:517-25)

Whereas the local recurrence rate and time to recur- rence after removal of ameloblastoma have been evaluated and described,Ill the treatment choices for ameloblastoma remain controversial. 14,12q7 The long-term elimination of ameloblastoma has not been completely successful regardless of the treatment. For surgery the recurrence rate is about 10% for the uni- cystic type of this tumor when it is treated by enucle- ation and curettage, and the recurrence rate is 50% to 90% in ameloblastomas in general. 2"7 Nevertheless enucleation with curettage still remains a treatment of choice for patients with unicystic ameloblasto- ma,5, 13, 14, 16, 18 and enucleation with marginal resec- tion of healthy bone is recommended for young patients with ameloblastoma regardless of the histo- logic pattern. 2, 4 The follow-up program for patients who have such tumors should include monitoring for the early detection of recurrence in an effort to reduce morbidity and medical expense.

Although animal experiments and clinical studies have thoroughly elucidated the histologic condition and biochemistry of healing after bone injury, 19-29 relatively few reports have described the radiology of postsurgical bone healing in animals and humans, 28"39 and even fewer have described the radiographic alterations during the healing process after conserva- tive removal of benign jaw lesions. Furthermore the few clinical reports describing bone healing after re-

aDepartment of Oral and Maxillofacial Radiology. bDepartment of Oral and Maxillofacial Radiology. CDepartment of Oral and Maxillofacial Radiology. dprofessor, Department of Oral and Maxillofacial Surgery. Copyright | 1995 by Mosby-Year Book, Inc. 1079-2104/95/$3.00 + 0 7/16/60705

moval of benign jaw cysts or tumors generally de scribe small samples of patients or of even single in- dividuals. Additionally most of these reports have il- lustrated only the final result of bone healing by radiographs obtained years after surgery and have not described the early stages of the healing process in detail), 7, 9, 11, 17, 18, 40-45 To our knowledge no report has described the radiographic alterations observed at various time intervals throughout the entire process until complete healing after removal of such benign lesions. To study the radiographic features of bone healing, we conducted the present retrospective re- view of radiographs made after the removal of benign jaw cysts and ameloblastomas. The purpose was to investigate radiographic alterations at specific time intervals throughout the entire healing process until complete bone healing occurred. This study was also conducted to determine the optimum time of fol- low-up examination after surgery for the early detec- tion of retained, residual, or recurrent lesions.

MATERIAL AND METHODS The 55 patients included in this study had been

treated for dentigerous cyst (13), odontogenic kera- tocyst (18), and ameloblastoma (24) by fenestration, currettage, or enucleation at Osaka University Den- tal Hospital during the past 10 years (Table I). Patients were excluded, if they had secondary infec- tion, if they were lost to follow-up examination, or if the radiographic image quality was poor.

A total of 374 follow-up radiographs including panoramic (n = 178), posteroanterior skull (n = 175), lateral oblique projection of the mandible (n = 13), panagraphs (n = 4), and occlusal radiographs (n = 4) were reviewed from the selected 55 patients. The ra-

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518 Kawai et al. ORAL SURGERY ORAL MEDICINE ORAL PATHOLOGY Apr i l 1995

I. unchanged H. slightly changed

III. partly reduced IV. entirely absent

Fig. 1. Diagramatic representations of radiographic fea- tures of surgical site margin observed during course of bone healing after removal of odontogenic cyst or ameloblas- toma. Original cystic margin is I, completely preserved; II, partly decreased in width and clarity; III, partly absent; and IV, entirely absent.

~ X X X X

H. ground glass appearance

III. spiculed IV. trabecular X

Fig. 2. Schematic drawings of radiographic features of interior of surgical site observed during course of bone healing after removal of odontogenic cyst or ameloblas- toma. I, Unchanged; radiographic features of internal surgical site show no change after operation. II, Ground glass appearance; periphera ! portion of surgical site shows ground glass appearance. III, Spiculed; radial bone spic- ules are found in peripheral portion. IV, Trabecular; surgi- cal site is regenerated with normal cancellous bone archi- tecture.

Table I. The study population

~ ibuao.

patients Male Female (yr) SD

Odontogenic 31 20 11 28.6 18.6 cyst

Ameloblastoma 24 16 8 25.7 12.7

diographic features of the lesion margin and of the internal portion of the postsurgical area were evalu- ated on the basis of the criteria illustrated in Figs. 1 and 2.

The postsurgical radiographic pattern of the surgi- cal margins in patients who had odontogenic cysts and ameloblastomas was classified as unchanged when the original radiopaque margin of the lesion was unal- tered, slightly changed when the clarity and width of the original margin were reduced, partly reduced when the clarity of the original margin was decreased or when the original margin had partially disappeared or was partly displaced inward toward the center of the surgical area, and entirely absent when the entire margin of the lesion was completely absent (Fig. 1).

The postsurgical radiographic appearance of the internal portion of the surgical site was classified as unchanged when no change from the presurgical ap- pearance was observed, "ground glass" when a slight increase in radiopacity was noted, spiculed when bone spicules were visible from the periphery to the center of the site, and trabecular when radiating trabeculae enclosing marrow spaces were observed (Fig. 2). When both ground glass appearance and spicules were observed at the same surgical site, the radio- graphic appearance was categorized as "spiculed" because of the more calcified feature. When both sp- icules and trabeculation were observed at the same surgical site, the appearance was classified as "tra- becular" for the same reason. "Trabecular" as used here does not always indicate "complete bone heal- ing" but rather a stage in the bone healing process. The features of the presurgical and postsurgical ra- diographs in six patients are illustrated in Figs. 3 to 8.

All of the radiographs in this study were evaluated by three of the authors independently. Each was blinded to the time interval the radiograph was taken after surgery. The images at recall and baseline were viewed and compared side by side. When a marked density difference between presurgical and postsurgi- cal radiographs was noted, comparison of the images was performed with a variable intensity light.

For radiologic tracking of the progression of site healing after conservative removal of benign lesions,

ORAL SURGERY ORAL MEDICINE ORAL PATHOLOGY Kawai et al. 519 Volume 79, Number 4

Fig. 3. Panoramic radiographs in patient with dentigerous cyst patient, a, Presurgical panoramic radiograph reveals well-defined radiolucency including left lower second mo- lar. b, Two-month postsurgical panoramic radiograph show- ing ground glass appearance along inferior border of surgi- cal site (white arrows). Ghost image, more radiopaque zone in ascending ramus of mandible, is clearly visible, but does not hinder accurate interpretation of this image.

we analyzed the occurrence of radiographic changes in the margin and interior of the surgical site at spe- cific time intervals after surgery with a matched-pair chi-squared test.

RESULTS The 31 patients with od0ntogenic cyst underwent a

total of 74 follow-up radiographic examinations, and the 24 patients with ameloblastoma underwent 49.

Radiographic changes in the margin of the surgical site (Tables II and III)

Surgical sites categorized as "unchanged" were observed in 21 of the 31 observations within the first month of the postsurgical follow-up period. The "un- changed" category was seen in a high percentage (68%) of the observations during the first month af- ter surgery (Table II). The hypothesis that radio- graphic changes would not occur during the first month after surgery was assessed by a chi-squared

Fig. 4. Panoramic view in patient with dentigerous cyst involving left upper lateral incisor, a, Presurgical radio- graph showing uniform radiolucency with well-defined margin, b, Two-month postsurgical panagraphy showing bony spicules in peripheral portion of surgical site (white arrows).

test analysis of the incidence of "unchanged" cate- gory in this period. The results shown in Table III in- dicate that the high incidence of the "unchanged" category is significantly associated with this period (p = 0.0001). It is suggested that most follow-up ra- diographic features in comparison with those seen immediately after surgery will not show in the first month. Of the sites examined at 1 to 2 months after surgery, those categorized as "slightly changed" or "partly reduced" accounted for 79%, indicating that the incidence of change of radiographic appearance is high during this period (p = 0.011). Of the observa- tions made in the second and third month after sur- gery, 88% revealed alteration of the site margin, indicating that in most patients some kind of ra- diographic alteration will be detectable in this period (/9 = 0.0001). Furthermore 97% of the sites observed more than 3 months after surgery were categorized as "partly reduced" or "entirely absent," indicating that bone changes will almost always be apparent in the site margin after a postsurgical inter- val of more than 3 months has elapsed (p = 0.0001). Of the observations made more than 4 months after

520 Kawai et al. ORAL SURGERY ORAL MEDICINE ORAL PATHOLOGY April 1995

Fig. 5. Follow-up radiographs in patient with odontogenic keratocyst, a, Preoperative radiograph, b, Sec- tion of posteroanterior skull radiograph obtained 6 months after surgery reveals regenerated bone architec- ture excluding central portion of surgical site (trabecular). c, This radiograph obtained 17 months after sur- gery reveals complete bone healing (trabecular).

Table II. Follow-up radiographic features of the surgical site margin in patients with odontogenic cyst and ameloblastoma

Radiographic categorization

Month after surgery

~ 1 ~ 2 ~ 3 ~ 4 ~ 5 ~ 6 ---->6

Unchanged 21 1 3 1 0 0 0 26 Slightly changed 5 5 3 0 0 0 1 14 Partly reduced 5 6 7 4 0 3 1 26 Entirely absent 0 2 5 3 6 4 37 57 Month total (n) 31 14 18 8 6 7 39 123

Category total (n)

surgery, 90% were classified as entirely absent, indi- cating that the site margin in most patients will be completely remodeled during this period (p = 0.0001).

These results indicate that the follow-up radio- graphic appearance of the margin is characterized by significant progression from "unchanged" through "slightly changed" and "partly reduced" to entirely absent.

Radiographic changes in the interior of the surgical site (Tables IV and V)

The "unchanged" category was seen in a high per- centage (74%) of observations made during the first month after surgery (Table IV). The hypothesis that

radiographic changes would not occur during the first month after surgery was assessed by a chi-squared test to analyze the incidence of the "unchanged" cat- egory in this period. The results shown in Table V in- dicate that the high incidence of "unchanged" cate- gory is significantly associated with this period (p = 0.0001). In other words it is suggested that most follow-up radiographic features in comparison with those seen immediately after surgery will not show changes in the first month. Of those cases observed during the second month after surgery, 79% were classified as "ground glass" appearance or spiculed, suggesting that newly formed bone tissues will be vis- ible on radiographs during the second month after the operation (p = 0.0001). Of the site interiors observed

ORAL SURGERY ORAL MEDICINE ORAL PATHOLOGY Kawai et al. 521 Volume 79, Number 4

Fig. 6. Panoramic radiographs in 22-year-old woman with odontogenic keratocyst, a, Presurgical radiograph shows well-defined radiolucency with sharp white lines, b, Radio- graph obtained 3 months and 3 weeks after surgery shows apparent increased radiodensity of surgical site interior and loss of white margin.

in the second and third month after surgery, 75% were classified as one of the three categories of radio- graphic change, suggesting that in most patients some kind of radiographic alteration will be detectable in this period (p = 0.0001).

Of those site interiors observed more than 3 months after surgery, 97% were classified as spiculed or tra- becular, indicating that apparent osteogenic changes will be detectable in this period (p---0.0001). Of those observed 4 or more months after surgery, 85% were classified as showing trabecular features. This finding suggests that bone regeneration and remodel- ing of the site will occur 4 months or more after sur- gery (p = 0.0001). These results indicate that the fol- low-up radiographic appearance of the site interior progressed from unchanged to ground glass appear- ance to spiculed and trabecular. The rate of interob- server discrepancy for the three raters in radiographic categorization was 2.4% (3 of 123) for the site mar- gin and 1.6% (2 of 123) for the site interior. The five observations in which disagreement occurred were

Fig. 7. Panoramic radiographs in patient with ameloblas- toma. a, Presurgical panoramic radiograph reveals well-de- fined, expansive area of radiolucency in left lower molar to ramus region, b, This panoramic radiograph obtained 6 months after surgery reveals complete bone healing of sur- gical site. Note tooth germ of left lower third molar visible at upper area of surgical site (arrows).

made during the first 3 months and were between "unchanged" and "slight change" at the site margin or "unchanged" and "ground glass" appearance at the site interior. Part of the original cystic margin of the lesion was retained in the bony healing area in sev- eral sites. In addition three of the surgical sites studied that remained at the "trabecular" stage after a long fol- low-up period showed an area of incomplete healing in their central portion. They had a well-localized lucent area but did not have a clearly depicted sclerotic mar- gin. These lucent areas were static for a prolonged pe- riod of time, ranging from 1 to several years. Increased calcification of the site interior compared with the sur- rounding normal bone was observed in two cases. One was observed on radiographs obtained 4 months, 17 days after surgery, and the other was observed on radiographs obtained 5 months, 23 days after surgery. However, in both sites these calcified areas had vanished within the following 7 or 8 months.

522 Kawai et al. ORAL SURGERY ORAL MEDICINE ORAL PATHOLOGY April 1995

Fig. 8. Radiographs of recurrent lesion in patient with ameloblastoma, a, Preoperative radiograph showing man- dibular ameloblastoma lesion, b, Radiograph obtained 11 months after surgery showing complete local bone healing of surgical site. Arrowheads indicate original surgical site margin, e, Radiograph obtained 6 years after surgery showing recurrent ameloblastoma lesion (white and black arrow).

DISCUSSION The categorization of radiologic progression used

in this study is compatible with the histologic phasing of extraction wound or fracture healing previously described in animal and clinical studies. 19"22, 24-28, 29 The category of "unchanged" in this study corre- sponds to the early stage of healing in such injuries in

which hematoma, blood clots, coagulation, granula- tion tissue, or immature fibrous connective tissue for- mation generally develops during the first 2 weeks af- ter surgery. 2~ 2t, 25 In this study the unchanged status sometimes persisted for up to 1 month after surgery. This situation was probably due to the failure of ra- diography to depict the slight initial calcification in the wounds, which should have already been formed histologically. The categories of "slightly changed" and "ground glass appearance" in the site margin and interior corresponded to the second stage of wound healing after extraction or fracture. In this stage con- comitant bone apposition in well-organized fibrous connective tissues and necrotic bone resorption are seen.19-22, 28, 29 This process develops 1 to 4 weeks af- ter dental extractions in animals or humans and 3 to 4 weeks after fracture in humans. The features of "slightly changed" and "ground glass" appearance were not observed in this study until 2 months after surgery, which is twice the interval found after dental extraction or jaw fracture. In addition it has been re- ported that in this stage new bone formation does not occur randomly within the site but rather extends from outside the marrow spaces to the socket wall zS' 26 or fracture ends. 28 It is readily apparent that these phenomena are visualized with radiography as pe- ripheral opacification of the site and decrease of the site margin exactly as illustrated in the diagrammatic representations in this article. The categories of "partly reduced" for the site margin and "spiculed" for the site interior correspond to the third stage o f extraction wound or fracture healing. In this stage bone formation develops from the wall and base of the socket to the socket mouth, 19, 21 and a hard internal or external callus develops into' more organized bone tissues during fracture healing. 28,29 These phases continue for 3 to 5 weeks in extraction wound healing 19-22 and for 3 or 4 months in fracture heal- ing. 28'29 Heppenstall es described that the average duration at the hard callus stage for major long bones in an adult was 3 to 4 months, which is consistent with our results. The categories of entirely absent for the site margin and trabecular for the site interior corre- spond to the stage of remodeling in fracture healing in which mature bone tissues still show temporarily increased calcification followed by remodeling of these areas in angular deformities during the frac- ture-heating process. These calcifications and angu- larities are ultimately remodeled into bone with nor- mal density or the original contour that existed before the fractureY It is very interesting that these phe- nomena have not been described in previous studies of extraction wound healing. This lack of information may be due to the difficulties in perceiving these phe-

ORAL SURGERY ORAL MEDICINE ORAL PATHOLOGY Kawai et al. 523 Volume 79, Number 4

Table IlL Radiographic progression in the site margin

Category

Time interval after surgery

(too) Ratio Percent Chi-squared

analysis Degree of freedom p Value

Unchanged < 1 21/31 68 50.723 1 0.0001 Slightly changed

Partly reduced 1 ~ ~ <2 11/14 79 6.471 1 0.011 Slightly changed

Partly reduced 1 < ~ <3 28/32 88 20.076 1 0.0001 Entirely absent =

Partly reduced _->3 58/60 97 94.831 1 0.0001

Entirely absent Entirely absent >4 47/52 90 70.275 1 0.0001

Table IV. Follow-up radiographic appearance of the surgical site interior in patients with odontogenic cyst and ameloblastoma

Radiographic categorization

Unchanged Ground glass appearance Spiculed Trabecular Month total (n)

~ 1 ~ 2

23 3 7 5 1 6 0 0

31 14

Month after surgery

~ 3

5 7 3 3

18

~ 4

0 1 3 4 8

~ 5 ~ 6 ->_6

1 0 0 0 1 5 6 33 8 38

Category total (n)

32 20 20 51

123

Table V. Radiographic progression in the site interior

Category

Time interval after surgery

(mo) Ratio Percent Chi-squared

analysis Degree of freedom p Value

Unchanged <1 23/31 74 49.978 1 0.0001 Ground glass appearance

Spiculed 1 < ~ <2 11/14 79 15.267 1 0.0001 Ground glass appearance

Spiculed 1 < ~ <3 24/32 75 15.246 1 0.0001 Trabecular

Spiculed _-> 3 58/60 97 72.799 1 0.0001 Trabecular

Trabecular _-> 4 44 / 52 85 69.113 1 0.0001

nomena because of the short time span of extraction wound healing. 19-22, 24-26 Difficulties may also exist in distinguishing the density of the healed socket, which is presumably increased, from that of the surrounding bone tissues, which is also overcalcified, because ini- tial bone apposition is laid down in the marrow spaces adjacent to the socket. 25, 26 Furthermore the decrease of the socket volume in both the verticaP 9-22, 24-26 and horizontal dimensions in patients may obscure the overcalcified density of the socket. In this study, 4 months after surgery the overall radiographic appear- ance was almost the same as that of subsequent ob- servations; the radiolucencies of the surgical site inte-

rior converted wholely to normal trabeculae. Two surgical sites in this study, however, showed overcal- cification of the site interior like that in the remodel- ing stage of fracture healing. Both sites showed remodeling of this feature and normal bone density about 1 year after surgery, two traits that are very similar to the phenomena observed in the remodeling stage of fracture healing. 28 Based on these observa- tions we consider that the present radiographic cate- gorization of the site margin and interior after removal of benign jaw cysts and ameloblastomas is in general an appropriate and useful method of fol- low-up examination of patients with these diseases.

524 Kawai et al. ORAL SURGERY ORAL MEDICINE ORAL PATHOLOGY April 1995

Subt le changes including ei ther "s l ight ly changed" or "g round g lass" appea rance m a y not be demon- s t ra ted wi thout adequa te x - ray exposure set t ings and proper viewing condit ions. Accordingly , in the evalu- a t ion of rad iographs ob ta ined within 2 months af ter surgery, which might reveal sl ight changes, a var iable in tens i ty l ight source is recommended . Our da t a sug- gest tha t the op t imal t ime for ear ly detect ion of resid- ual lesions m a y be the four th month af ter surgery, when rad iograph ic changes of both the site marg in and in ter ior a re apparen t .

In the evaluat ion of a r ad iograph obta ined 3 or more months af ter surgery, a sharp ly defined site marg in l ike tha t of the preopera t ive lesion marg in or a c lear lucent site in ter ior like tha t of the or iginal le- sion lumen should suggest a residual lesion. When bone resorpt ion is observed within or outs ide the site marg in within this per iod af ter surgery, a secondary infect ion should be suspected. Again , ma rked de lay of r ad iog raph ic changes m a y indicate unsuccessful sur- gery, secondarY infection, or metabol ic disease. Fol- low-up r ad iog raph ic features tha t deviate f rom the pa t t e rn presented here should be suspected to indicate res idual lesion, secondary infection, or metabo l ic dis- ease. The recur rence ra te in our pat ients with amelo- b l a s tomas 6 to 10 years af ter surgery was 53% (9 of 17), which is within the repor ted range for such pa- t ients. A pers is tent rad io lucency seen in a few pat ients suggests t ha t such lucencies should be di f ferent ia ted f rom tumor recurrence. Radio lucencies tha t precede bony hea l ing are local ized in the centra l a rea of the site but a re ma rg ina t ed and lack c lear ly visual ized white lines in cont ras t to a recur ren t lesion. Because ame lob la s toma has the potent ia l for local recurrence, fol low-up rad iograph ic examina t ion should be per- fo rmed every year for at least ! 0 years a f te r local bone heal ing. 14

CONCLUSION A f t e r benign j a w cysts or amelob las tomas are

removed the t ime course of changes in the surgical marg in para l le ls tha t of the surgical site interior. The four th month af ter surgery was found to be the opti- m u m t ime for fol low-up rad iograph ic examina t ion to evalua te whether heal ing is normal . Rad iog raph ic observat ion 3 or more months af ter surgery of sharp ly defined site marg ins l ike tha t of the preopera t ive le- sion marg in or of a c lear lucent inter ior l ike tha t of the or iginal lesion lumen m a y indicate a res idual lesion. Radio lucenc ies associa ted with bony hea l ing are local ized in the cent ra l a rea of the site but a re mar - g ina ted wi thout c lear ly visual ized white lines in con- t ras t to a recur ren t lesion. Fol low-up rad iograph ic examina t ion of pa t ien ts with amelob las tomas should

be pe r fo rmed every year for a t least 10 years af ter lo- cal bone healing.

REFERENCES

1. Shatkin S, Hoffmeister FS. Ameloblastoma: a rational ap- proach to therapy. ORAL SURG ORAL MED ORAL PATHOL 1965;20:421-35.

2. Sehdev MK, Huvos AG, Strong EW, Gerold FP, Willis GW. Proceedings: ameloblastoma of maxilla and mandible. Cancer 1974;33:324-33.

3. Adekeye EO. Ameloblastoma of the jaws: a survey of 109 Ni- gerian patients. J Oral Surg 1980;38:36-41.

4. Molla MR, Shaheed I, Shrestha P. Ameloblastoma: a clinical study of 13 cases. Bangladesh Med Res Counc Bull 1991; 17:29- 35.

5. Robinson L, Martinez MG. Unicystic ameloblastoma: a prog- nostically distinct entity. Cancer 1977;40:2278-85.

6. Waldron CA. Ameloblastoma in perspective. J Oral Surg 1966;24:331-3.

7. Gardner DG, Corio RL. The relation~-'-ip of plexiform unicys- tic amelohlastoma to conventional ameloblastoma. ORAL SURG ORAL MED ORAL PATHOL 1983;56:54-60.

8. E1-Mofty SK, Gerard NO, Farish SE, Rodu B. Peripheral ameloblastoma: a clinical and histologic study of 11 cases. J Oral Maxillofac Surg 199l;49:970-4.

9. Minami M, Kaneda T, Yamamoto H, et al. Ameloblastoma in the maxillomandibular region: MR imaging. Radiology 1992; 184:389-93.

10. Thompson IOC, Ferreira R, van Wyk CW. Recurrent unicys- tic ameloblastoma of the maxilla. Br J Oral Maxillofac Surg 1993;31:180-2,

l 1. Collings S J, Harrison A. Recurrent ameloblastoma? An his- toric case report and a review of the literature. Br Dent J 1993;174:202-6.

12. Gardner DG, Pecak AMJ. The treatment of ameloblastoma based on pathologic and anatomic principles. Cancer 1980; 46:2514-9.

13. Gardner DG. Plexiform unicystic ameloblastoma: a diagnos- tic problem in dentigerous cysts. Cancer 198l;47:1358-63.

14. Gardner DG, Corio RL. Plexiform unicystic ameloblastoma: a variant of ameloblastoma with a low-recurrence rate after enucleation. Cancer 1984;53:1730-5.

15. Mtiller H, SlootWeg PJ. The growth characteristics of multi- locular ameloblastomas: a histological investigation with some inferences with regard to operative procedures. J Maxillofac Surg 1985;13:224-30.

16. Leider AS, Eversole LR, Barkin ME. Cystic ameloblastoma: a clinicopathologic analysis. ORAL SURG ORAL MED ORAL PATHOL 1985;60:624-30.

17. Pogrel MA. The use of liquid nitrogen cryotherapy in the management of locally aggressive bone lesions. J Oral Maxil- lofac Surg 1993;51:269-73.

18. Shteyer A, Lustmann J, Lewin-Epstein J. The mural amelo- blastoma: a review of the literature. J Oral Surg 1978;36:866- 72.

19. Huebsch RF, Coleman RD, Frandsen AM, Becks H. The healing process following molar extraction: I Normal male rats (Long-Evans strain). ORAL SURG ORAL MED ORAL PATHOL 1952;5:864-76.

20. Huebsch RF, Hansen LS. A histopathologic study of extrac- tion wounds in dogs. ORAL SURG ORAL MED ORAL PATHOL 1969;28:187-96.

21. Simpson HE. The healing of extraction wound. Br Dent J 1969;126:550-7.

22. Johansen JR. Repair of the postextraction alveolus in Wister rat: a histologic and autoradiographic study. Acta Odontol Scand 1970;28:441-6l.

23. Tsuchimoehi M, Hosain F, Engelke W, Zeicher SJ. Studies on focal alveolar bone healing with technetium (Tc)-99m labeled methylene diphosphonate and gold-collimated cadmium tellu-

ORAL SURGERY ORAL MEDICINE ORAL PATHOLOGY Kawai et al. $25 Volume 79, Number 4

ride probe. ORAL SURG ORAL MED ORAL PATHOL 1991; 71:110-5.

24. Bodner L, Kaffe I, Littner MM, Cohen J. Extraction site heal- ing in rats: a radiologic densitometric study. ORAL SURG ORAL MED ORAL PATHOL 1993;75:367-72.

25. Amler MH, Johnson PL, Salman I. Histological and his- tochemical investigation of human alveolar socket healing in undisturbed extraction wounds. J Am Dent Assoc 1960;61:32- 44.

26. Boyne PJ. Osseous repair of the postextraction alveolus in man. ORAL SURG ORAL MEn ORAL PATHOL 1966;21:805-13.

27. Amler MH. The age factor in human extraction wound heal- ing. J Oral Surg 1977;35:193-7.

28. Heppenstall RB. Fracture treatment and healing, 1st ed. Phil- adelphia: WB Saunders, 1980:41-52,80-5,98-100.

29. Wilson JN. Watson-Jones fractures and Joint Injuries, 6th ed. Vol 1. London: Churchill Livingstone, 1982:14-28.

30. Vose GP, Mack PB, Brown SO, Medlen AB. Radiologic determination of the rate of bone healing. Radiology 1961; 76:770-6.

31. Nicholls P J, Berg E, Bliven-JR FE, Kling JM. X-ray diagno- sis of healing fractures in rabbits. Clin Orthop 1979; 142:234-6.

32. K/ilebo P, Strid KG. Radiographic videodensitometry for quantitative monitoring of experimental bone healing. Br J Radiol 1989;62:883-9.

33. Marmary Y, Brayer L, Tzukert A, Feller L. Alveolar bone re- pair following extraction of impacted mandibular third molars. ORAL SURG ORAL MED ORAL PATHOL 1985;60:324-6.

34. Allard RHB, Lekkas C. Unusual healing of a fracture of an atrophic mandible: report of a case. ORAL SURG ORAL MED ORAL PATHOL 1983;55:560-63.

35. Schwimmer AM, Greenberg AM. Management of mandibu- lar trauma with rigid internal fixation. ORAL SURG ORAL MED ORAL PATHOL 1986;62:630-7.

36. Shufford EL, Kraut RA. Passive rigid fixation of sagittal split osteotomy. ORAL SURG ORAL MED ORAL PATHOL 1989; 68:150-3.

37. Lachner J, Clanton JT, Waite PD. Open reduction and inter-

nal rigid fixation of subcondylar fractures via an intraoral ap- proach. ORAL SURG ORAL MED ORAL PATHOL 1991;71:257- 61.

38. Williams MD, Pearson MH, Milner SM. Complications in the use of compression plates in the treatment of mandibular fractures. ORAL SURG ORAL MED ORAL PATHOL 1991;72: 159-61.

39. Iizuka T, Lindqvist C, Hallikainen D, Mikkonen P, Paukku P. Severe bone resorption and osteoarthrosis after rniniplate fix- ation of high condylar fractures. ORAL SURG ORAL MED ORAL PATHOL 1991;72:400-7.

40. Heimdal A, Isacsson G, Nilsson L. Recurrent central odonto- genie fibroma. ORAL SURG ORAL MED ORAL PATHOL 1980;50:140-5.

41. Kerley TR, Sehow CE. Central giant cell granuloma or cherubism: report of a case. ORAL SURG ORAL MED ORAL PATHOL 1981;51:128-30.

42. Eversole LR, Leider AS, Strub D. Radiographic characteris- tics of cystogenic ameloblastoma. ORAL SURG ORAL MED ORAL PATHOL 1984;57:572-7.

43. Freedman GL, Beigleman MB. The traumatic bone cyst: a new dimension. ORAL SURG ORAL MED ORAL PATHOL 1985; 59:616-8.

44. Mills WP, Davila MA, Beuttenmuller EA, Koudelka BM. Squamous odontogenic tumor: report of a case with lesions in three quadrants. ORAL SURG ORAL MED ORAL PATHOL 1986;61:557-63.

45. Horner K, Forman GH, Smith NJ. Atypical simple bone cysts of the jaws. I: Recurrent lesions. Clin Radiol 1988;39:53-7.

Reprint requests: Tadahiko Kawai, DDS, PhD Department of Oral and Maxillofacial Radiology Osaka University Faculty of Dentistry 1-8 Yamadaoka Suita City Osaka 565, Japan

CALL FOR REVIEW ARTICLES

The January 1993 issue of ORAL SURGERY, ORAL MEDICINE, ORAL PATHOLOGY, ORAL RADIOLOGY, AND ENDODONTICS contained an Editorial by the Journal's Editor in Chief, Larry J. Peterson, that called for a Review Article to appear in each issue.

These Review Articles should be designed to review the current status of matters that are important to the practitioner. These articles should contain current developments, changing trends, as well as re- affirmation of current techniques and policies.

Please consider submitting your article to appear as a Review Article. Information for authors appears in each issue of ORAL SURGERy, ORAL MEDICINE, ORAL PATHOLOGY, ORAL RADIOLOGY, AND ENDODONTICS.

We look forward to hearing from you.