The opinions and assertions expressed herein are those of the authors and are not to be construed as official or as reflecting the views of the Department of the Air Force or the Department of Defense. Objective: The ameloblastic fibro-odontoma (AFO) is an uncommon odontogenic tumor occurring in childhood with limited reported data on recurrence. The purpose of this AFO study was to review its clinicopathologic features, investigate treatment modalities and establish a recurrence rate. Study Design: The clinicopathologic features of 12 new cases of AFO were analyzed and compared with those of 208 cases from the literature, with special emphasis on the clinical behavior, treatment, and recurrence rate. Results:The average age was 9.4 (±6.7) years with a male-to-female ratio of 1.6:1. The mandible was the site of occurrence in 59.5%. The tumor most often presented radiographically as a unilocular mixed density lesion associated with the crown of an impacted tooth. Displacement of teeth, delayed eruption and bony expansion were commonplace. There were 5 recurrences among 68 cases with adequate follow-up for a recurrence rate of 7.4%. All recurrences were attributed to incomplete removal at the time of the initial surgery.Conclusions: The AFO is a childhood tumor most often affecting the posterior jaws and frequently causing bony expansion with profound affects on the dentition. Conservative surgical removal with extraction of the associated teeth is recommended. The established recurrence rate is less than 10%.

Fixation with formaldehyde is the first process to which most biopsy and necropsy specimens are exposed prior to dehydration and embedding in paraffin wax. Tissue specimens that have been fixed in formaldehyde have architectural characteristics that are familiar to virtually every pathologist and these facilitate routine diagnosis. Nevertheless, formaldehyde fixation has some deleterious effects including reduction in immunoreactivity and degradation of nucleic acids. Development of methods to counteract these deleterious effects requires an understanding of the chemical events that occur during tissue fixation and subsequent tissue processing. This short review illustrates some of the chemical consequences of formaldehyde fixation and ethanol dehydration. It also provides some insight into the molecular events accompanying heat-induced antigen retrieval.