This retrospective study aimed to investigate the recurrence rate of keratocystic odontogenic tumours (KCOTs) treated by enucleation and the application of Carnoy’s solution, and to assess the surgical morbidities associated with this treatment. KCOTs treated using a standard protocol of enucleation and the application of Carnoy’s solution between 1990 and 2013 were evaluated. One hundred and five KCOTS in 105 patients (54 male, 51 female) were analysed. The mean follow-up period was 86.6 months (range 24–313 months). The recurrence rate was 11.4%. A postoperative inferior alveolar nerve neurosensory deficit occurred in 30.1% of the mandibular cases, with 16% of these being permanent. The postoperative infection and fracture rates were 1.9% and 0.9%, respectively. Younger age, multilocular KCOTs, larger tumour size, and longer antero-posterior lesion length on the radiograph were found to be risk factors for recurrence. It is concluded that enucleation and the application of Carnoy’s solution to treat KCOTs results in a relatively low recurrence rate and a low rate of surgical morbidities.
The keratocystic odontogenic tumour (KCOT), previously termed an odontogenic keratocyst before being renamed by the World Health Organization in 2005, is a benign intraosseous tumour of odontogenic origin. KCOTs are reported to comprise 11% of all jaw lesions of a similar kind. These tumours may also be related to nevoid basal cell carcinoma syndrome, which may present with multiple KCOTs, basal cell carcinoma, and skeletal anomalies.
KCOTs are notorious for their high recurrence rate following treatment and their locally aggressive behaviour. Resection has been reported to result in a very low recurrence rate; however this benefit may not outweigh the high rate of surgical morbidity. Other treatment modalities, for example marsupialization and enucleation with adjunctive treatment, are more conservative in nature and have been proved to reduce recurrence. Recent systematic reviews on KCOT treatment modalities and their related recurrence rates have yielded contradictory results. This could be due to the short follow-up times used and the lack of a single standardized treatment protocol for KCOT in some studies.
KCOT treated by enucleation and the application of Carnoy’s solution has been reported to have a low recurrence rate. However, few cases treated by this method have been reported, which makes the evaluation of surgical morbidities and the analysis of risk factors for recurrence difficult. The authors’ institution has used this treatment protocol for KCOT for over 20 years. An evaluation of the treatment outcomes of enucleation and the application of Carnoy’s solution to treat KCOT would be valuable.
The aim of this study was to investigate the recurrence rate of KCOT treated by enucleation and the application of Carnoy’s solution and to analyse the surgical morbidities associated with this treatment, including neurosensory deficits, infection, and postoperative fracture.
Materials and methods
This was a retrospective clinical study. Ethical approval was obtained from the institutional review board. Patients who presented with a KCOT (or odontogenic keratocyst, as named previously), who were treated between January 1990 and January 2013 in the oral and maxillofacial surgery unit of the study institution in Hong Kong using a standard treatment protocol of enucleation and the application of Carnoy’s solution (see ‘Surgical procedure’ below), were included in the study. The inclusion criteria were confirmation of the diagnosis of KCOT/odontogenic keratocyst by incisional biopsy and a follow-up period of at least 2 years. Patients with multiple KCOTs who were diagnosed with nevoid basal cell carcinoma syndrome (NBCCS) and cases of recurrence were excluded from the study.
The postoperative follow-up involved clinical and radiographic examinations during the early postoperative period, at 6 months postoperative, and then annually. KCOT recurrence was confirmed by histopathological examination after re-treatment. The following data were collected: age and sex of the patient, the size of the KCOT measured on a panoramic radiograph with consideration of the 1.2-times magnification (length × height/1.2, presented in cm 2 ), the length of the lesion in antero-posterior dimension (length in cm/1.2), the location of the KCOT, whether it was unilocular or multilocular, pathological subtypes, the follow-up period, the presence and time of any recurrence, the mode of re-treatment, and the presence of any neurosensory disturbance, infection, or pathological jaw fracture.
The surgical procedure was performed under general anaesthesia. After standard disinfection and draping, the KCOT was exposed by mucoperiosteal flap elevation and bone removal. The lesion was enucleated and any teeth adhering to the lesion were removed. The overlying mucosa or periosteum in contact with the KCOT that fenestrated through the bone was excised and removed. The adjacent soft tissues were protected with gauze. Carnoy’s solution (containing chloroform, acetic acid, and alcohol) was applied for 3 min using ribbon gauze or cotton applicators in the bony cavity and fenestrated area where excision of the overlying soft tissue was not possible. After thorough irrigation with saline, the wound was packed loosely with an iodoform pack (or an antrostomy for lesions involving the maxillary sinus) and closed with a resorbable suture.
Analgesics and antibiotics were prescribed postoperatively. Patients were reviewed at the outpatient clinic and the iodoform pack was changed every 2 weeks until self-cleansing of the defect was achievable.
The primary outcome of the study was the recurrence rate of KCOT after enucleation and the application of Carnoy’s solution. The secondary outcomes were the incidence of surgical morbidities including neurosensory deficits of the inferior alveolar nerve (IAN), infection, and postoperative fracture, as well as factors that might affect the recurrence rate (sex, age, size of the KCOT, location of the KCOT, whether the KCOT was unilocular or multilocular).
Statistical analyses were performed using IBM SPSS Statistics version 20.0 software (IBM Corp., Armonk, NY, USA). The patient’s sex and the location of the lesion and their relationships with the recurrence rate were analyzed by χ 2 test. The mean age of the patients and mean size of the lesions and their relationships with the recurrence rate were analyzed by independent t -tests. A 5% significance level was applied for all statistical analyses.
A total of 105 patients with 105 KCOTs were included in the study; 54 were male and 51 were female. The patients ranged in age from 10 to 83 years, with a mean age of 37.1 years (standard deviation (SD) 16.9 years). Seventy-nine percent (83/105) of the KCOTs were located in the mandible; 75.2% of the KCOTs originated in the posterior region of the mandible. The sizes as measured on panoramic radiographs ranged from 0.72 cm 2 to 80.1 cm 2 , with a mean size of 17.3 cm 2 (SD 13.1 cm 2 ). With regard to locularity, 41.9% (44/105) were unilocular and 58.1% (61/105) were multilocular, as seen on the radiographs. The patient demographic data and characteristics of the KCOTs are presented in Table 1 .
|Age, years, mean (SD)||37.1 (16.9)|
|Posterior maxilla||19.1% (20/105)|
|Anterior maxilla||1.9% (2/105)|
|Posterior mandible||75.2% (79/105)|
|Anterior mandible||3.8% (4/105)|
|Size on radiograph, cm 2 , mean (SD)||17.3 (13.1)|
|Antero-posterior length on radiograph, mm|
|Follow-up, months, mean (SD)||86.6 (57.3)|
The follow-up period ranged from 24 months to 313 months, with a mean follow-up period of 86.6 months (SD 57.3 months). The recurrence rate was 11.4% (12/105). In the 12 recurrence cases, the time to recurrence ranged from 10 months to 124 months, with a mean time to recurrence of 40.8 months (SD 39.7 months). The characteristics of the cases of recurrence and their treatment are presented in Table 2 .
|Patient||Sex||Age, years||Location||Locularity||Time to recurrence, months||Treatment for recurrence *||Follow-up after recurrence, months|
|1||Female||16||Posterior mandible||Multilocular||24||E + C||192|
|2||Male||16||Posterior maxilla||Multilocular||14||E + C||212|
|3||Female||16||Posterior mandible||Multilocular||41||E + C||82|
|4||Male||17||Posterior mandible||Multilocular||18||E + C||127|
|5||Female||20||Posterior maxilla||Unilocular||36||E + C||10|
|7||Female||22||Posterior mandible||Multilocular||30||E + C||76|
|8||Male||28||Posterior mandible||Multilocular||124||E + C||159|
|9||Male||30||Posterior maxilla||Multilocular||121||E + C||87|
|10 †||Male||36||Posterior mandible||Multilocular||17||E + C||5|
|11||Male||38||Posterior mandible||Multilocular||13||E + C||109|
|12||Female||60||Posterior mandible||Multilocular||10||E + C||163|
The surgical morbidities are presented in Table 3 . A postoperative IAN deficit was reported in 30.1% (25/83) of the patients with a mandibular KCOT. Of those who presented a postoperative IAN deficit, 84% (21/25) recovered and 16% (4/25) were considered to have a permanent deficit (with incomplete recovery or no recovery after 2 years). For those who recovered from the neurosensory deficit, the mean time to recovery was 4.6 months (SD 3.3 months). The postoperative infection rate was 1.9% (2/105); infections were treated with local measures and antibiotics. Mandibular fracture occurred in one case at 4 weeks postoperative. This fracture was treated with intermaxillary fixation for 6 weeks and healed uneventfully.
|Recurrence rate||11.4% (12/105)|
|Neurosensory deficit of IAN|
|Early postoperative deficit||30.1% (25/83)|
|Permanent deficit||16% (4/25)|
|Time to recovery, months, mean (SD)||4.6 (3.3)|
|Postoperative infection rate||1.9% (2/105)|
|Postoperative mandibular fracture||0.9% (1/105)|
With regard to the factors that might contribute to the recurrence of KCOT, it was found that younger age, multilocular KCOTs, larger KCOT size, and greater length in antero-posterior dimension of the KCOT were risk factors for recurrence. The mean age of recurrence cases was 26.8 years, which was significantly younger than the mean age of those who did not have a recurrence (38.4 years; P = 0.024). The recurrence rate of multilocular KCOT was 18.0% (11/61), which was significantly higher than that for unilocular lesions (2.3%, 1/44; P = 0.012). In the recurrence cases, the mean preoperative size of the KCOT was 26.4 cm 2 (SD 15.0 cm 2 ), which was significantly larger than the size of KCOTs that did not recur (16.0 cm 2 , SD 12.5 cm 2 ; P = 0.009). It was also noted that the length in antero-posterior dimension of the lesion also affected the recurrence rate. The recurrence rates of KCOTs with lesion lengths of <4 cm, 4–8 cm, and >8 cm in antero-posterior dimension were 5.8% (3/52), 10.5% (4/38), and 33.3% (5/15), respectively. The differences were found to be statistically significant ( P = 0.012). The sex of the patient and the location of the KCOT were found not to be risk factors for KCOT recurrence ( Table 4 ).