j. max.-fac. Surg. 11 (1983) 211

j. max.-fac. Surg. 11 (1983) 211-215 © 1983 Georg Thieme Verlag Stuttgart • New York

Late Results Following the Brosch-Procedure for Treating Large Mandibular Ramus Cysts Mostafa Farmand, Miro Makek

Maxillo-Facial Surgery Clinic (Director: Prof. H. Obwegeser, M.D., D.M.D.), and the Institute of Pathology (Directors: Prof. Ch. Hedinger, M.D. and Prof. J. R. R~ttner, M.D.), University Hospital Zfirich, Switzerland

Introduction

The Brosch-procedure is the one most preferred for the treatment of large cysts of the ascending ramus of the Clinic for Maxillo-Facial Surgery, University Hospital Zurich. The evaluation of the results of this method for the period 1961-1979 are presented. Operation method of the Brosch-procedure (1957): An oral approach is used to expose the entire buccal cortical plate in the region of the ascending and horizontal ramus to the full extent of the cyst. The overlying lateral cortical bone is completely removed by a decortication-like procedure. The cyst lining is enuncleated in toto. The resultant bony cavity is prepared in such a way that the adjacent tissues may be collapsed easily into the defect in order to obliterate the cavity in the ascending ramus. The undermined bony margins of the cavity must therefore be removed (Fig. 1). Extensions of the cyst cavity into the body of the mandible are not as readily amenable to obliteration by adaptation of adjacent tissues and therefore this portion of the cavity, denuded of cyst epithelium, is packed with iodine-vaseline gauze and treated further by marsupialization in this area. Dependent upon the site and size of the cyst removal of the lingual cortical plate may be indicated (Rosenthal, 1958). Wound closure is accomplished by continuous suture. An extraoral compression bandage helps to adapt the soft tissues to the empty bony cavity. Several authors (Wassmund, 1933; Brosch, 1957; Boehmer, 1958; Becker, 1971) have recommended a two- stage procedure for treating large cysts: fenestration of the cyst is done under local anaesthesia. Some months later the Brosch-procedure is undertaken.

Table 1 Causative cysts requiring Brosch-procedure

Odontogenic keratocyst 21 Dentigerous cyst 4 Radicular cyst 3 Other (cyst. adenomatoid odontogenic tumour) 1

Total 29

Summary

The Brosch-procedure and its modification, removal of the lingual cortex, for treatment of large cysts of the mandibular ramus is presented. 29 patients were treated by this method in the period 1961-1979. In a late follow-up it was found that recurrence occurred within 2 years in 8 of the 21 patients with odontogenic keratocysts. No recurrence could be found in patients with other cysts. Seven of the recurrences occurring within the first 2 years were treated under local anaesthesia. One patient with Gor- lin's syndrome refused further treatment and 9 years postoperatively cystic expansion of the whole ascend- ing ramus and ipsilateral mandibular body was present. It was noted that bone regeneration, irrespective of the nature of the causative cyst, is generally complete in two years.

Key-Words

Mandibular cyst - Treatment of large cysts - Kerato- cyst - Recurrence of cysts - Follow-up - Cystectomy - Cystostomy

Material and Results

We have used this procedure for all large cysts which had extended more than half-way up the ascending ramus. 29 patients are included in the study. Expansion into the mandibular body was not a contraindication. Of 29 patients treated by this procedure 21 had odon- togenic keratocysts, 4 dentigerous cysts and 3 radicular or residual cysts. One patient had a cystic adenomatoid odon- togenic tumour (Table 1).

Fig. 1 Coronal section through the ascending ramus, The undercut bony margins of the cavity are removed and the adjacent tissues are adapted into the defect.

212 J. max.-fac. Surg. 11 (1983) M. Farmand, M. Makek

Abb. 2 a

Abb. 2 b

Abb. 2 c

Fig. 2 Dentigerous cyst of the ramus and body of the mandible treated by the Brosch- procedure (1957): The orthopanthomograms show the preoperative condition (a) and the situation 6 months (b), and 17 months (c) after the operation. (case of Prof. Perko)

Re-examination of all 29 previously examined cyst-linings was undertaken once again in order to reconfirm the previ- ous diagnosis. In 27 instances the buccal cortical wall was removed and in 2 cases the lingual cortical wall was removed. In 12 cases a single procedure was performed, whereas in 13 patients the above-mentioned two-stage procedure with an interopera- tive interval of 3 -6 months was undertaken. Cystectomy or marsupialization was performed prior to the Brosch-proce- dure in a further 4 patients.

In 13 patients the cyst expanded to include the whole ascending ramus, in 6 patients to 1 cm. below the semilunar notch and in 10 patients to just over half way up the ramus. Operative complications comprised direct damage to the inferior alveolar nerve in one case, an infracture of the lingual cortex and fracture of the coronoid process in one case respectively. Postoperative follow-up continued until complete bony regeneration of the defect. This is generally complete in two years (Fig. 2), irrespective of the nature of the causative

Late Results Following Brosch-Procedure J. max.-fac. Surg. 11 (1983) 213

Fig. 3 Odontogenic keratocyst of the right ramus treated by the Brosch-procedure (1957): In comparison with the preoperative situation (a) complete bony regeneration is achieved within 8 months (b). (case of PD Dr. Sailer)

cyst, although in some instances this healing phase may last for as little as 8 months (Fig. 3). Recurrences requiring a cystectomy under local anaesthesia occurred in 8 of the 29 patients, all of whom had an odontogenic keratocyst initially (Table 2). The size of the recurrence was 1.5 cm. in diameter or smaller. Recurrences occurred in the horizontal ramus in 4 patients, mostly in the vicinity of teeth. In 3 of these cases the teeth were retained during the subsequent cystectomy. In 3 patients the recur- rence was seen in the middle of the ramus. The coronoid process was involved in one patient who refused further treatment. At further follow-up of 15 patients, 3-20 years postopera- tively no new recurrences were observed. The patient with involvement of the coronoid process who had previously refused further treatment for recurrence, 9 years after the initial operation presented with cystic expansion of the entire ramus and most of the ipsilateral mandibular body. Additional maxillary cysts and a basal cell carcinoma possibly indicated a Gorlin's syndrome. At this late stage resection and immediate reconstruction was undertaken. The Brosch-procedure did not lead to additional facial deformity. Intraorally prosthetic rehabilitation, if required, remained unaffected. Of 19 patients in whom the inferior alveolar nerve was exposed, only one revealed a postopera- tive hypoaesthesia. Anaesthesia remained 10 years post- operatively in one patient, in whom the nerve was iatrogen- ically damaged.

Table 2 Recurrences after the Brosch-procedure

Odontogenic keratocysts (n = 21) Recurrences in retromolar region 4 In ramus 3 In coronoid proc. 1

Dentigerous cysts (n = 4) 0 Radicular cysts (n = 3) 0

Other ( n = 1) 0 (cyst. adenomatoid odontogenic tumour)

Discussion

Excellent results in the treatment of dentigerous and residual or radicular cysts in the ramus of the mandible are obtainable by means of the Brosch-procedure. Recurrences occurred only in odontogenic keratocysts. The primary treatment of the keratocyst remains controver- sial. Bramley (1971, 1974) recommends the achievement of a definitive result in one operation. The keratocyst recur- rence rate is relatively high. It is approximately 44 % (Toller, 1972), with some authors reporting lesser percent- ages (Panders and Hadders, 1969; Browne, 1970; Stoelinga, 1971; Eversole et al., 1975; Brannon, 1976; Voorsmit et al., 1981). The results of these authors included odontogenic keratocysts of various sizes and located in different sites, despite the predominant location being in the region of the third molar.

214 J. max.-fac. Surg. 11 (1983) M. Farmand, Miro Makek

Fig. 4 Lining of an odontogenic keratocyst with daughter cysts. (HE 63 x)

There is a higher recurrence rate following cystostomy (Reuters and Gundlach, 1981). Our results, incorporating 8 recurrences in 21 patients with odontogenic keratocysts should be viewed, in comparison to other published studies on keratocysts, in the light of the distinctly specific operative indication applicable to the utilization of the Brosch-procedure; namely our use of the procedure only in cases of large keratocysts extending at least half way up the ascending ramus, whereas other publications report recurrences relating to large and small keratocysts in various locations. Several causes for the recurrence of odontogenic kerato- cysts exist. Rarely the recurrence may be due to the exist- ence of Gorlin's syndrome (Gorlin and Goltz, 1960; Bunt- ing and Remensnyder, 1977; Dunnick et al., 1978). Usually though, the recurrence is due in part to the histological nature of the cyst and in part to the operation method employed. Histologically, daughter cysts (Fig. 4) are seen to penetrate the adjacent bone (Shear, 1976), and these may remain in situ following a cystectomy. Additionally, the inner layer of an odontogenic keratocyst is thin. Difficulty in removing the cyst lining in its entirety, particularly in larger cysts, is thus encountered, resulting in remnants of cyst epithelium remaining in situ. Good operative exposure is therefore necessary and this is adequately provided for by the Brosch-procedure. An extra-oral incision (Shear, 1976) is unnecessary. To eliminate the daughter cysts, there are, in the literature, suggestions for the use of a cauterizing agent (Stoelinga, 1971; Voorsmit et al., 1981), and cryotherapy (Bradley and Fisher, 1975). These methods were not used because we did not want any cauterizing of the bone or

damage to the inferior alveolar nerve which had to be exposed in 19 of our patients. One should aim to remove the complete cyst lining, even if the roots of teeth are surrounded by cyst tissue. Failure to do this, we believe, resulted in the 4 recurrences reported here as having occurred within the mandibular body. But in 3 patients we were able to retain the teeth following cystec- tomy. Some authors maintain that new cyst formation may arise from oral mucosa basal cells (Stoelinga, 1973; Stoelinga and Peters, 1973; Voorsmit et al., 1981). No indication of this was noted in our patients, because in none of our 21 patients was the cortical bone perforated and recur- rences do not occur after additional cystectomy of the residual cysts without excision of the overlying mucoperiosteum. Therefore we feel that the routine removal of the overlying mucoperiosteum, as advocated by Bramley (1974) and Voorsmit et al. (1981)is not indicated. Microkeratocysts have been demonstrated in the develop- ing human oral mucosa (Moreillon and Schroeder, 1982). Although their number decreases in the gingiva of the newborn, some of these microcysts persist in the adult gingiva, without being manifest clinically (Moskow, 1966; Moskow et al., 1970). Wysocki et al. (1980) mention that the gingival microcysts of adults have a limited growth potential and therefore have to be distinguished from true odontogenic keratocysts with their higher potential for recurrence. Regular and frequent postoperative radiographic control is paramount, at least until complete bony restitution has been accomplished, usually spanning a period of 2 years. Recurrence during this period is not only easily detected, but also expeditiously treated under local anaesthesia. Extensive investigations by Schulte (1965) and Kirsten (1970) indicate that the location and expansion of the cyst as well as the patient's age, play an important role in postoperative bone regeneration following treatment of a cyst, with especially favourable results being achieved in cysts located in the ascending ramus. Kirsten (1970) claims only 35 % of his cases showed bony restitution following cystostomy or cystectomy alone, 2 years postoperatively, Schulte (1965) reports complete healing between 2 and 3.5 years following filling of the cyst with blood. Selle and Kotthaus (1973) noted good bony regeneration in 86.6 % of their cases 3 years after cystectomy. The results of the Brosch-procedure in comparison with those of the above authors who treated their cysts by cystostomy or cystectomy alone, would appear to involve more rapid healing. The wide opening of the bony cavity created by the Brosch-procedure is not a hindrance to rapid bony regeneration, but rather an advantage due to the possibility of adapting the soft tissues intimately to the exposed bone, thereby aiding the healing process by eliminating dead space without causing noticeable facial soft tissue distortion. Attempts to reduce the size of the cyst cavity have been reported as long ago as 1929: Loos recommended the application of a periosteal flap to the cavity. A similar procedure for the mandibular body was reported by Beck- mann (1948). Rosenthal (1958, 1964) advocates the adap- tation of the soft tissues to the bony cyst base using mattress sutures. Heidsieck (1957, 1964) recommends the use of suction drainage within the cyst cavity following closure. The two stage procedure (Wassmund, 1933; Brosch, 1957;

Late Results Following Brosch-Procedure ]. max.-fac. Surg. 11 (1983) 215

Boehmer, 1958; Becker, 1971) also helps to reduce the size of a cyst before the Brosch-procedure. After fenestration, bony apposition reduces the size of the initial defect caused by a cyst.

Conclusion

The Brosch-procedure is a good method for treating all cysts located high up in the ascending ramus of the mand- ible. The excellent view permitted by this procedure enables the removal of the cyst lining in its entirety. Recurrences or daughter-cysts of odontogenic keratocysts could be treated easily under local anaesthesia. In comparison with cyst- ostomy or cystectomy alone this procedure achieves, in our opinion, more rapid healing.

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Mostafa Farmand, M.D., D.M.D. Clinic for Maxillo-Facial Surgery Zurich University Plattenstrafle 11 CH-8028 Zurich/Switzerland

M. Makek, M.D. Institute of Pathology Zurich University Schmelzbergstr. 12 CH-8091 Zurich~Switzerland