Ricardo J. Padilla

Incidental findings from cone beam computed tomography of the maxillofacial region: a descriptive retrospective study

OBJECTIVE To evaluate the type and prevalence of incidental findings from cone beam computed tomography (CBCT) of the maxillofacial region. Findings are divided into those that require (i) intervention/referral, (ii) monitoring, and (iii) no further evaluation. METHODS Three hundred consecutive CBCT scans conducted in the University of North Carolina School of Dentistry Oral and Maxillofacial Radiology Clinic from January 1 to August 31, 2008 were retrospectively reviewed. Findings were categorized into airway, soft tissue calcifications, bone, temporomandibular joint (TMJ), endodontic, dental developmental, and pathological findings. RESULTS A total of 272 scans revealed 881 incidental findings (3.2 findings/scan). The most prevalent was airway findings (35%) followed by soft tissue calcifications (20%), bone (17.5%), TMJ (15.4%), endodontic (11.3%), dental developmental (0.7%), and pathological (0.1%). 16.1% required intervention/referral, 15.6% required monitoring, and the remainder (68.3%) required neither. CONCLUSION This study underscores the need to thoroughly examine all CBCT volumes for clinically significant findings within and beyond the region of interest.

Carcinoma cuniculatum of the oral mucosa: a potentially underdiagnosed entity in the absence of clinical correlation.

OBJECTIVE To delineate the features of carcinoma cuniculatum (CC), emphasizing potential management errors. STUDY DESIGN A retrospective study examined archival cases of CC. An analysis of clinical, microscopic, and management parameters was performed. RESULTS Ten cases were identified, and their clinical and microscopic features were summarized. CC exhibits a sessile pink/red mildly papillary surface. Histologically, CC presents a tortuous invasive component with a more subtle papillary appearance than verrucous carcinoma. CONCLUSIONS CC is an uncommon variant of squamous cell carcinoma distinct from verrucous carcinoma. Diagnostic delays result from misinterpretation of superficial samples or lack of awareness of the entity. Bland cytology and unusual architecture result in underdiagnosis of CC without clinicopathologic correlation. Clinicians should submit multiple deep samples of lesions displaying a cobblestone-like surface and provide a clinical photograph to the pathologist. Pathologists can avoid underdiagnosis by thorough sampling of biopsies and requesting additional tissue as needed.

In Vivo Assessment of Bone Healing following Piezotome® Ultrasonic Instrumentation

PURPOSE This pilot study evaluated the molecular, histologic, and radiographic healing of bone to instrumentation with piezoelectric or high speed rotary (R) devices over a 3-week healing period. MATERIAL AND METHODS Fourteen Sprague-Dawley rats (Charles River Laboratories International, Inc., Wilmington, MA, USA) underwent bilateral tibial osteotomies prepared in a randomized split-leg design using Piezotome® (P1) (Satelec Acteon, Merignac, France), Piezotome 2® (P2) (Satelec Acteon), High-speed R instrumentation, or sham surgery (S). At 1 week, an osteogenesis array was used to evaluate differences in gene expression while quantitative analysis assessed percentage bone fill (PBF) and bone mineral density (BMD) in the defect, peripheral, and distant regions at 3 weeks. Qualitative histologic evaluation of healing osteotomies was also performed at 3 weeks. RESULTS At 1 week, expression of 11 and 18 genes involved in bone healing was significantly (p < .05) lower following P1 and P2 instrumentation, respectively, relative to S whereas 16 and 4 genes were lower relative to R. No differences in PBF or BMD were detected between groups within the osteotomy defect. However, significant differences in PBF (p = .020) and BMD (p = .008) were noted along the peripheral region between P2 and R groups, being R the group with the lowest values. Histologically, smooth osteotomy margins were present following instrumentation using P1 or P2 relative to R. CONCLUSIONS Piezoelectric instrumentation favors preservation of bone adjacent to osteotomies while variations in gene expression suggest differences in healing rates due to surgical modality. Bone instrumented by piezoelectric surgery appears less detrimental to bone healing than high-speed R device.

Biological Assessment of a Calcium Silicate Incorporated Hydroxyapatite-Gelatin Nanocomposite: A Comparison to Decellularized Bone Matrix

Our laboratory utilized biomimicry to develop a synthetic bone scaffold based on hydroxyapatite-gelatin-calcium silicate (HGCS). Here, we evaluated the potential of HGCS scaffold in bone formation in vivo using the rat calvarial critical-sized defect (CSD). Twelve Sprague-Dawley rats were randomized to four groups: control (defect only), decellularized bone matrix (DECBM), and HGCS with and without multipotent adult progenitor cells (MAPCs). DECBM was prepared by removing all the cells using SDS and NH4OH. After 12 weeks, the CSD specimens were harvested to evaluate radiographical, histological, and histomorphometrical outcomes. The in vitro osteogenic effects of the materials were studied by focal adhesion, MTS, and alizarin red. Micro-CT analysis indicated that the DECBM and the HGCS scaffold groups developed greater radiopaque areas than the other groups. Bone regeneration, assessed using histological analysis and fluorochrome labeling, was the highest in the HGCS scaffold seeded with MAPCs. The DECBM group showed limited osteoinductivity, causing a gap between the implant and host tissue. The group grafted with HGCS+MAPCs resulting in twice as much new bone formation seems to indicate a role for effective bone regeneration. In conclusion, the novel HGCS scaffold could improve bone regeneration and is a promising carrier for stem cell-mediated bone regeneration.

Use of archived biopsy specimens to study gene expression in oral mucosa from chemotherapy-treated cancer patients

OBJECTIVES Oral mucositis caused by cancer chemotherapy can result in significant clinical complications. There is a strategic need to accelerate the delineation of the pathobiology. This proof-of-principle study was designed to demonstrate the feasibility of studying archived oral mucosal specimens to further delineate oral mucositis pathobiology. MATERIALS AND METHODS Twenty-nine formalin-fixed and paraffin-embedded tissue blocks of 25-year-old oral mucosa autopsy specimens from cancer chemotherapy patients were studied. Standardized technology was utilized, including RNA isolation and amplification, array hybridization, and gene expression analysis. RESULTS A predominance of DNA damage in buccal mucosal basal keratinocytes was observed. Data comparing basal cells from buccal vs. gingival mucosa identified differential gene expression of host responses in relation to pathways relevant to oral mucositis pathogenesis, including responses to cancer-associated inflammation. CONCLUSIONS This proof-of-principle study demonstrated that archived oral mucosal specimens may be a potentially valuable resource for the study of oral mucositis in cancer patients.

In Vivo Assessment of Osseous Wound Healing Using a Novel Bone Putty Containing Lidocaine in the Surgical Management of Tooth Extractions

Objective. This preclinical pilot study evaluated the systemic, radiographic, and histological responses to bone putty containing lidocaine in a canine tooth extraction model. Methods. In five beagle dogs the right mandibular premolars were extracted and sockets grafted with (1) xenograft particulate bone and a collagen sponge plug (control), (2) bone putty alone, (3) bone putty mixed with xenograft (3 : 1), or (4) xenograft sandwiched between bone putty. At 6 weeks post-op, the systemic and local responses were evaluated using a blood chemistry panel, micro-CT, and histological analyses. Results. No significant differences in blood chemistries were noted at 6 weeks postgrafting compared to baseline. Sockets grafted with either bone putty formulation demonstrated comparable radiographic and histologic evidence of bone healing compared to control sockets. Conclusions. Our preclinical results indicate that this bone putty appears to be a safe biocompatible device that may be useful in the postoperative management of tooth extractions.

Evaluation of a collagen scaffold for cell-based bone repair.

PURPOSE To determine whether a collagen scaffold could provide an environment for mesenchymal stem cell (MSC)-related bone repair of critical-size bone defects in rat calvaria. MATERIALS AND METHODS Craniotomy defects were created in 28 adult Sprague-Dawley rats. Two additional rats were used as MSC donors by means of femoral bone marrow lavage and culture. The rats were randomly divided into four groups: (1) empty/no graft; (2) collagen scaffold (matrix)+saline; (3) matrix+MSCs; (4) matrix+bone morphogenetic protein. The animals were euthanized 28 days after surgery. Microcomputed tomographic reconstructions were obtained to measure bone fill. The specimens were processed for histologic examination, and the total defect and bone fill areas were measured. RESULTS Mean bone fill (± standard deviation) of 9.25%±10.82%, 19.07%±17.38%, 44.21%±3.93%, and 66.06%±15.08%, respectively, was observed for the four groups; the differences were statistically significant. Bone repair was statistically significant for groups 3 and 4. No significant difference was seen for bone repair between groups 1 and 2 or between groups 3 and 4. Bone formation differed significantly across the four groups. Statistically significant changes in radiodensity were observed between groups 1 and 3, groups 1 and 4, and groups 2 and 4. Significant differences were not observed between groups 1 and 2, groups 2 and 3, or groups 3 and 4. CONCLUSION After grafting of adult MSCs adherent within a collagen matrix, repair of bone was significant. Expanded three-dimensional collagen represents a radiolucent, resorbable, biocompatible scaffold that is capable of supporting MSC repair of bone.

Transcriptome Variability in Keratocystic Odontogenic Tumor Suggests Distinct Molecular Subtypes.

Keratocystic Odontogenic Tumor (KCOT) is a locally aggressive developmental cystic neoplasm thought to arise from the odontogenic epithelium. A high recurrence rate of up to 30% has been found following conservative treatment. Aggressive tumor resection can lead to the need for extensive reconstructive surgery, resulting in significant morbidity and impacting quality of life. Most research has focused on candidate-genes with a handful of studies employing whole transcriptome approaches. There is also the question of which reference tissue is most biologically-relevant. This study characterizes the transcriptome of KCOT using whole genome microarray and compare it with gene expression of different odontogenic tissues (“dentome”). Laser capture microdissection was used to isolate the neoplastic epithelial tissue in 20 cases. KCOT gene expression was compared with the “dentome” and relevant pathways were examined. Cluster analysis revealed 2 distinct molecular subtypes of KCOT. Several inflammatory pathways were activated in both subtypes. The AKT pathway was activated in one subtype while MAP kinase pathway was activated in the other. Additionally, PTCH1 expression was downregulated in both clusters suggesting involvement in KCOT tumorigenesis. In conclusion, this study provides new insights into the transcriptome of KCOT and highlights pathways that could be of diagnostic and prognostic value.

Considerations in the diagnosis of oral hairy leukoplakia—an institutional experience

OBJECTIVE We report here the 10-year experience with oral hairy leukoplakia (OHL) at the Division of Oral and Maxillofacial Pathology at the University of North Carolina at Chapel Hill, NC, USA. STUDY DESIGN All the associated hematoxylin and eosin and Epstein-Barr virus encoding region in situ hybridization slides of OHL cases between January 1, 2008, and February 1, 2017, were retrieved and reviewed. Collected demographic characteristics, clinical presentation, medical and social histories were reviewed and reported. RESULTS Six OHL cases with confirmed in situ hybridization showed predilection for the lateral tongue. The study included 3 females and 3 males (mean age 50.5 years; age range 29-70 years). One patient had known HIV-positive status before biopsy was performed. Three patients had reported a history of heavy smoking. Other medical conditions reported were history of breast cancer, a long history of corticosteroid inhaler use for asthma treatment, high cholesterol, diabetes, and hypertension. CONCLUSIONS The findings of this study indicate the need to include OHL as a potential entity in the differential diagnosis of leukoplakic tongue lesions, regardless of the patients HIV status. In addition, the presence of OHL in the patient requires investigation of various explanations for EBV infection, including immunosuppression caused by HIV infection or chronic steroid use.

Ameloblastoma Phenotypes Reflected in Distinct Transcriptome Profiles

Ameloblastoma is a locally invasive benign neoplasm derived from odontogenic epithelium and presents with diverse phenotypes yet to be characterized molecularly. High recurrence rates of 50–80% with conservative treatment in some sub-types warrants radical surgical resections resulting in high morbidity. The objective of the study was to characterize the transcriptome of ameloblastoma and identify relevant genes and molecular pathways using normal odontogenic tissue (human “dentome”) for comparison. Laser capture microdissection was used to obtain neoplastic epithelial tissue from 17 tumors which were examined using the Agilent 44 k whole genome microarray. Ameloblastoma separated into 2 distinct molecular clusters that were associated with pre-secretory ameloblast and odontoblast. Within the pre-secretory cluster, 9/10 of samples were of the follicular type while 6/7 of the samples in the odontoblast cluster were of the plexiform type (p < 0.05). Common pathways altered in both clusters included cell-cycle regulation, inflammatory and MAPkinase pathways, specifically known cancer-driving genes such as TP53 and members of the MAPkinase pathways. The pre-secretory ameloblast cluster exhibited higher activation of inflammatory pathways while the odontoblast cluster showed greater disturbances in transcription regulators. Our results are suggestive of underlying inter-tumor molecular heterogeneity of ameloblastoma sub-types and have implications for the use of tailored treatment.