Adjunctive Strategies for Benign Maxillofacial Pathology

Surgical Resection and Reconstruction of Ameloblastoma: A 13-Year Retrospective Review

BACKGROUND

Ameloblastoma is a locally aggressive, benign tumor presenting in the maxilla and mandible prone to recurrence. Resection greatly limits recurrence; however, reconstruction becomes critical to preserve patients' functionality and esthetics.

PURPOSE

The aim of this study was to describe surgical resection and reconstructive approaches in the treatment of ameloblastoma and compare clinical outcomes to conservative methods of treatment.

STUDY DESIGN, SETTING, SAMPLE

A retrospective case series was completed through analysis of patient records. The study population was composed of patients treated for ameloblastoma at the Royal Brisbane Hospital (Queensland, Australia) in the Oral and Maxillofacial Surgery Unit from January 1, 2008, to December 31, 2020. Patients without histological confirmation of intraosseous ameloblastoma were excluded from the study sample.

PREDICTOR VARIABLE

Not applicable.

MAIN OUTCOME VARIABLE(S)

The primary outcome variable was time to recurrence. Secondary outcome variables included any surgical complications incurred.

COVARIATES

The covariate variables collected included age at diagnosis/treatment, gender, ethnicity, location of lesion and site(s) of involvement, tumor extent, alveolar expansion, histopathological growth pattern, and soft tissue involvement.

ANALYSES

Descriptive statistics were computed for each study variable.

RESULTS

A total of 48 cases of histologically confirmed ameloblastoma were identified (41 mandibular, 7 maxillary) involving 50 excisional operations (44 resections, 6 enucleations). Of these cases, 44 were followed up > 12 months, with a mean length of follow-up time of 65.6 months. No recurrence was detected for resected lesions. One enucleated lesion recurred at 25 months. Thirty-seven reconstructive procedures were undertaken, including 32 immediate free flaps. All reconstructive flaps and grafts survived, and no major complications were recorded.

CONCLUSION AND RELEVANCE

Resection of ameloblastoma limits recurrence and should be considered curative. Immediate microvascular free flap reconstruction of maxillary and mandibular defects from resection of ameloblastoma is safe and predictable.

What Is the 5-year Incidence of Recurrent Disease of Odontogenic Keratocysts?

PURPOSE

There is no consensus on the ideal treatment of odontogenic keratocysts (OKCs). Certain risk factors may modify the disease recurrence rate. The purpose of this study was: 1) to estimate the incidence of OKC recurrence in a statistically rigorous manner; and 2) to identify risk factors associated with OKC recurrence.

METHODS

The investigators designed and implemented a retrospective cohort study and enrolled a sample derived from the population of patients presenting to the Department of Oral and Maxillofacial Surgery outpatient clinics at the University of Washington School of Dentistry and Harborview Medical Center for evaluation and management of OKCs between January 1, 2010, and December 31, 2020. Predictor variables included demographics (age, gender), radiographic characteristics (location of lesion, locularity, size, and cortical perforation), and type of operation performed (decompression + cystectomy, enucleation ± adjuvant therapy, or resection). The primary outcome variable was time to recurrent disease, defined as the time from treatment to radiographic or clinical evidence of a new lesion (recorded in months). Kaplan-Meier analysis was used to estimate median time to recurrence, and Cox proportional hazards models were used to identify covariates statistically associated with recurrent disease (P ≤ .05).

RESULTS

The sample was composed of 60 subjects with 63 previously untreated lesions. Eight subjects (13%) developed a recurrent lesion during the study interval with a median time to recurrence of 31 (interquartile range, 24 to 48) months. One of the 8 recurrences occurred within 12 months of treatment and 7 of the 8 recurrences occurred more than 21 months after treatment. Based on using Kaplan-Meier analysis, the 5-year incidence of disease recurrence was estimated to be 34%. Lesions with cortical perforation were 8.3 times more likely to recur (95% confidence interval [1.7, 41.3]; P-value = .01), and multilocular lesions were 10.6 times more likely to recur (95% confidence interval [1.3, 86.9]; P-value = .03). The sample size was the limiting factor to performing regression analyses.

CONCLUSIONS

Virtually every publication on OKCs to date reports frequencies of disease recurrence rather than applying appropriate survival analyses commonly used to estimate outcomes in cancer research. Failure to use the appropriate statistical analyses underestimates the risk of disease recurrence. Our study is no exception. The estimated frequency of disease recurrence during the study interval was 13% (8/60). When survival analyses are applied that account for varying months of follow-up, the incidence of disease recurrence is 34 per 100 per 5 years. We recommend the application of time-to-event analyses in the study of disease entities with the potential for recurrence.

Biomaterial-based strategies for maxillofacial tumour therapy and bone defect regeneration

Issues caused by maxillofacial tumours involve not only dealing with tumours but also repairing jaw bone defects. In traditional tumour therapy, the systemic toxicity of chemotherapeutic drugs, invasive surgical resection, intractable tumour recurrence, and metastasis are major threats to the patients' lives in the clinic. Fortunately, biomaterial-based intervention can improve the efficiency of tumour treatment and decrease the possibility of recurrence and metastasis, suggesting new promising antitumour therapies. In addition, maxillofacial bone tissue defects caused by tumours and their treatment can negatively affect the physiological and psychological health of patients, and investment in treatment can result in a multitude of burdens to society. Biomaterials are promising options because they have good biocompatibility and bioactive properties for stimulation of bone regeneration. More interestingly, an integrated material regimen that combines tumour therapy with bone repair is a promising treatment option. Herein, we summarized traditional and biomaterial-mediated maxillofacial tumour treatments and analysed biomaterials for bone defect repair. Furthermore, we proposed a promising and superior design of dual-functional biomaterials for simultaneous tumour therapy and bone regeneration to provide a new strategy for managing maxillofacial tumours and improve the quality of life of patients in the future.

Maspin, Syndecan-1, and Ki-67 in the Odontogenic Keratocyst: An Immunohistochemical Analysis

The odontogenic keratocyst (OKC) is a controversial lesion that was reclassified as a tumor with the name “keratocystic odontogenic tumor” in 2005. The reclassification was revoked recently in 2017, with a conclusion on the need for further studies on the subject. In this study, the expressions of an important regulatory protein (maspin), an important integral membrane proteoglycan (syndecan-1), and a universal proliferation marker (Ki-67) in the epithelium of the OKC were investigated in comparison with the dentigerous cyst (DC) and ameloblastoma (AB). Twenty-six OKCs, eleven DCs, and ten conventional ABs were immunohistochemically stained for maspin, syndecan-1, and Ki-67. ImageJ was used to analyze the positivity of maspin and syndecan-1. The Ki-67 score was calculated as the percentage of positive nuclei in 5 high power fields. Analysis of variance (ANOVA) test and Student t-test were used as appropriate. Lower expressions of maspin were noted in OKC and DC compared to those in AB, and lower expressions of syndecan-1 were noted in OKC and AB compared to those in DC. The differences, however, did not reach statistical significance (ANOVA and t-test: P > 0.05). The Ki-67 score was significantly higher in OKC than in DC (t-test: P < 0.05), and not significantly different from AB (t-test: P > 0.05). In conclusion, expressions of maspin and syndecan-1 are not strongly representative of differences in behavior between OKC, AB, and DC. However, the expression of Ki-67 indicates comparable proliferative activities of OKC and AB, which are higher than that of DC. Further investigation on the biologic behavior of OKC is still recommended to arrive at more specific conclusions regarding its classification.