The aim of this study was to evaluate whether volumetric changes in persistent periapical lesions can be detected in follow-ups six months to five years after apicoectomy using cone-beam computed tomography. Patients with a previous treatment history of apicoectomy and for whom a pre-surgical CBCT scan was taken between November 2010 and December 2015 were invited to participate in the study. A post-surgical CBCT image of the treated tooth was obtained at the recall visit. Volumetric and linear measurements of periapical lesions on initial and postoperative CBCT images were performed using DiThreshGUI software and two calibrated examiners—a board-certified endodontist and a board-certified oral radiologist. Repeated-measures ANOVA were used to estimate the magnitude of reduction and to test for differences (at alpha=0.05). A total of 20 patients with 27 surgically treated teeth were recalled at an average interval of 37 months. Reduction in the size of lesions was observed in 24 teeth (88%); overall, the volumes significantly decreased as detected by software-assisted measurement of volume (P = .0002) and by calculation from linear measurements (P < .0001). Volumetric analysis detected a reduction of 86% in lesions while the linear-derived volume measurements yielded an average reduction of 96%. These two methods of lesion assessment were strongly correlated with one another in pre-surgical scans (r>0.88) when apical lesions are measurable.

Cracked teeth have long presented a diagnostic challenge. Previous investigators have considered possible predictive factors, many of which revolve around the tooth’s restorative characteristics. Few have investigated the restorative status of teeth with cracks extending into the pulp chamber. The purpose of this investigation was to determine the prevalence of the different types of restorations present in intrapulpally cracked teeth and determine any other restorative factors that may aid in predicting the presence or extent of an intrapulpal crack. Intrapulpally cracked molars requiring endodontic therapy at the VCU Graduate Endodontic Practice were included in this study. For each tooth, the type of restorative material present and surfaces involved were recorded. The Restoration Volume Proportion (RVP) was calculated to accurately quantify the size of the restoration present. Pulpal and periapical diagnoses, and intrapulpal crack classification were also recorded. Chi squared analysis and logistic regression were used to determine any significant associations. This study included 43 teeth. The study population was 65% female and the average age was 56. Of the various restoration types evaluated, 73% of teeth presented with amalgams, 12% with composites. Class I restorations were 61% of the sample. The most frequently occurring restoration size by volume was a “small” restoration. The most commonly involved teeth were the maxillary 1st molar and mandibular 2nd molar. A significant association was found between restoration size and crack classification suggesting that teeth with larger restorations had a higher incidence of coronal cracks while those with smaller restorations had a higher incidence of radicular cracks. Restoration classification and pulpal walls involved were also significantly associated suggesting that Class II restorations were most frequently associated with cracks involving a single pulpal wall while Class I restorations were evenly associated with one and two wall cracks. Other significant associations were found between tooth type and pulpal walls involved and between restoration surfaces and pulpal wall classification. This study found several significant associations between restoration characteristics and intrapulpal cracks. Further research may continue to reveal how a tooth’s restorative status may influence its risk for the presence of an intrapulpal crack.

Introduction: The aim of this in vitro study was two part. The first being to assess and compare the amount of dentin removed by an instrument with a taper of 0.04 versus an instrument with a taper of 0.06 using the Edge Evolve® file system at different increments within the canal system. Secondly, this study evaluated whether instrumentation with either taper resulted in a remaining dentin thickness (RDT) of less than 0.3mm. If this RDT was imposed upon, fracture resistance was compromised. Both pre and post instrumentation measurements were taken of samples instrumented with the 0.04 and 0.06 tapered files. Methods: Ten maxillary premolars exhibiting Weine class III canal systems and minimal to no root canal curvature were mounted in an acrylic resin filled K-cube. Each acrylic resin cube was sectioned horizontally at 3, 6, 9, and 12mm increments from the apex. The K-cube is a device which allows the investigator to disassemble and then reassemble root slices in their original orientation. Dentin thickness was measured at three positions on each canal using the Zeiss Discovery V20 stereomicroscope. The sections were then reassembled into the K-cube. The ten premolar roots were separated into two groups. In half of the teeth the buccal canals were instrumented with 0.04 tapered files and the lingual canals instrumented with 0.06 tapered files. In the other half of the teeth, instrumentation was reversed: the buccal canals were instrumented with 0.06 tapered files and the lingual canals were instrumented with 0.04 tapered files. Root sections were again separated, and the remaining dentin thickness was measured. A repeated-measures mixed-model ANCOVA was performed to analyze the effect of taper on RDT. Results: The amount of dentin removed was statistically different between the two tapers (P=0.02). Across all of the slices and positions, the 0.04 tapered instruments had an average pre-post difference of 0.1313mm. The 0.06 tapered instruments had an average pre-post difference of 0.1672mm. None of the instruments imposed upon the recommended 0.3mm RDT. Conclusion: The 0.04 tapered files instrument with greater conservancy than the 0.06 tapered files. The 0.06 tapered files had their greatest effect on the canal in the 9mm and 12mm sections. However, neither taper imposed upon the recommended RDT for optimal fracture resistance within the apical 12mm root portion observed in this study. Keywords: Instrumentation, Edge Evolve, Root canal preparation, Taper

Thesis (M.S.)--West Virginia University, 2009. / Title from document title page. Document formatted into pages; contains viii, 44 p. : ill. (some col.). Vita. Includes abstract. Includes bibliographical references (p. 40-43).

Thesis (M.S.)--University of Michigan, 1973.

Thesis (M.S.)--West Virginia University, 2009. / Title from document title page. Document formatted into pages; contains ix, 46 p. : ill. (some col.). Vita. Includes abstract. Includes bibliographical references (p. 27-30).

Thesis (M.S.)--University of Michigan, 2005. / Includes bibliographical references.

Thesis (M.S.)--University of Michigan, 1989.

Thesis (M.S.)--University of Michigan, 1973.

Thesis (M.S.)--University of Michigan, 1975.