Steven B. Blanchard

Correlation Between Micro-computed Tomography and Histomorphometry for Assessment of New Bone Formation in a Calvarial Experimental Model

Conventional histologic or histomorphometric evaluation provides clear evidence of the bone healing process. However, the sample preparation process is tedious and destructive, and the three-dimensional (3D) anisotropic information of the bone trabeculae is compromised. Micro-computed tomography (&mgr;CT) has been introduced as an alternative to these traditional evaluation methods. &mgr;CT is noninvasive and provides a faster approach to evaluate and quantify cancellous bone. Most previous studies that used &mgr;CT have focused on studying trabecular structures of cancellous bone. In this study, we used &mgr;CT to analyze the micro-architecture of the regenerated membranous bone using a rabbit cranial defect model. Two 1 cm diameter circular bony defects were created in 12 New Zealand white rabbits. Specimens were harvested at 6 weeks and 12 weeks after surgery and were scanned using a MicroCT machine (Skyscan 1072, Aartselaar, Belgium). The specimens were then sectioned and stained with Goldners trichrome. Bone volume density (BV/TV), bone surface density (BS/BV), and trabecular thickness (TbTh) were determined from histomorphometric and two-dimensional (2D) and 3D &mgr;CT analysis. Pearsons correlation coefficient (&ggr;), paired t-tests, and intraclass correlation coefficients from measurements between the 2D and 3D &mgr;CT and histomorphometry were calculated. There were very strong positive correlations of BV/TV between histomorphometric and 2D or 3D &mgr;CT measurements. Correlation between histomorphometric and 2D &mgr;CT measurements for BS/BV was moderate, whereas correlation between histomorphometric and 3D &mgr;CT measurements was weak. Weak correlations in TbTh among the three methods were found. In conclusion, the present study suggests that, in evaluating micro-architectures in regenerated bones, the correlation between measuring methods vary according to the features measured.

Comparative evaluation of mandibular canal visibility on cross-sectional cone-beam CT images: a retrospective study.

OBJECTIVES The purpose of this study was to determine the visibility of the mandibular canal (MC) in CBCT images and if the visibility of the MC is affected by gender, location and/or age. METHODS CBCT images were evaluated for the visibility of the MC by a board-certified oral and maxillofacial radiologist, a board-certified periodontist and a periodontics resident. Representative slices were examined for the first premolar (PM(1)), second premolar (PM(2)), first molar (M(1)) and second molar (M(2)) sites by all examiners. The visibility of the MC was registered as either present or absent. RESULTS 360 total CBCT cross-sectional images were examined, with the MC identified in 204 sites (56%). Age had a significant effect on MC visibility, but it differed by location: for PM(1), age 47-56 had lower visibility than age 65+ (p = 0.0377). Gender also had a significant effect on canal visibility, where females had lower visibility than males overall (p = 0.0178) and had the most pronounced difference for PM(1) (p = 0.0054). Location had a significant effect on visibility, but it differed by age and by gender: for age 65+, M(2) had lower visibility than PM(1) (p = 0.0411) and PM(2) (p = 0.0180), while for females, PM(1) had lower visibility than M(1) (p = 0.0123) and M(2) (p = 0.0419). CONCLUSIONS The MC was visualized only in just over half of the CBCT images. Age, gender and location had significant effects on the visibility.

Cervical Enamel Projections and Associated Pouch-Like Opening in Mandibular Furcations

BACKGROUND Cervical enamel projections (CEPs) have been listed among the tooth-associated risk factors that could lead to isolated furcation defects around molar teeth. This is more likely when Grade III CEPs are present. However, the histologic aspects of the CEP interface with regard to the presence or absence of cementum over the enamel projection within the furcation have not been well described. This study was initially undertaken to evaluate this relationship. METHODS Thirty-five mandibular molars with Grade III CEPs were selected from a collection of extracted teeth and evaluated for the presence of cementum covering these areas by stereomicroscopy, light microscopy, and scanning electron microscopy (SEM). RESULTS Sixteen of the 35 teeth (45.7%) with Grade III CEPs appeared completely covered by cementum. SEM evaluation showed the presence of a narrow pouch-like opening between cementum and enamel in 15 of 16 teeth (93.8%). Light microscopy evaluation confirmed the presence of the pouch along with some indication of residual degenerated mesenchymal tissue within the defects. SEM evaluation showed the presence of globular bodies in this pouch. CONCLUSIONS This study reports on the presence of a pouch-like opening between the enamel and cementum in mandibular molars with Grade III CEPs. The clinical significance of these cementum pouches has yet to be determined but bacterial contamination of these pouch-like structures in areas of furcation periodontal breakdown may serve as a nidus for recolonization and disease recurrence or for the development of furcation caries if exposed to the oral cavity after surgical procedures.

Periodontal-Endodontic Lesion of a Three-Rooted Maxillary Premolar: Report of a Case

BACKGROUND A 43-year-old African American male initially presented for a dental evaluation of a recurrent swelling on the buccal aspect of tooth #12. His medical history was unremarkable except for a 20-pack year history of smoking. He was eventually diagnosed as having a necrotic pulp #12, and received root canal treatment. The patients problem was unresolved, and he was subsequently referred for a periodontal evaluation with a presumptive diagnosis of a periodontal abscess. METHODS A flap was reflected from teeth #11 through #15. A buccal furcation invasion was discovered on #12. Shortly thereafter, three distinct roots with three grade III furcation invasions were located. The tooth was deemed untreatable, and was extracted. The thin buccal plate of the extraction socket was preserved using freeze-dried bone allograft to facilitate future prosthodontic replacement. RESULTS Healing was uneventful. Periodontal open flap debridement surgery was provided for the remainder of the mouth, and the patient was placed on a 3-month recall program. CONCLUSIONS Periodontitis associated with endodontic lesions are among the most daunting diagnostic and therapeutic challenges faced by periodontists. This is particularly true for maxillary premolars with multiple roots. The tooth in this case, once periodontally involved, had a very poor prognosis. The prognosis was further compromised by the pulpal involvement. Therapy consisted of extraction of the tooth to relieve the patients discomfort and treating the adjacent teeth with periodontal open flap debridement surgery. A review of the literature pertinent to the diagnosis and management of periodontal-endodontic lesions is also presented.