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J F Corcoran

Publications and source records attributed to J F Corcoran.

10 recordsLinked to original sources
PubMed1992

Radiographic "working length" revisited.

The desired "working length" for the biomechanical preparation and resultant obturation of the root canal system is one of the most important phases of endodontics. Traditionally, radiographs are used to confirm working length of the root length and to evaluate the subsequent obturation of the root canal system. This study attempts to determine if radiographs are an accurate method of root length determination in a period when electronic apex locators are proposed as their replacement. Eight-seven vital and 24 nonvital teeth were accessed and files placed to and the radiographic working length before the file and teeth were extracted for sectioning. Results showed that the radiographic distance of the file from the apical vertex was 0.7 mm shorter than the actual file position. This discrepancy can lead the clinician to try to get closer to the radiographic apex, when in reality the end of the file is closer to the vertex than is suspected. The average distance short of the vertex as established by Kuttler should be increased to lie between 1.5 and 2.0 mm from the apical vertex to prevent overfilling the root canal.

Adult↗
PubMed1991

Nonionizing method of locating the apical constriction (minor foramen) in root canals.

The electronic method was evaluated as to its accuracy when used to determine the position of the apical constriction (minor foramen) in root canals. There were 39 vital and 8 nonvital teeth for a total of 47 specimens from 22 patients. The specimens were prepared with a Buehler Isomet bone saw to a thickness of 500 microns. Distances were measured and recorded with the use of a Bioquant II image analysis system. The electronic method appeared to measure a mean value of 0.2 mm coronal to the cemetodentinal junction in 47 canals where the apex locator was set at a reference setting of 40. When a frequency curve was plotted, it showed that the probability of being within 0.76 mm (1 SD) of the cementodentinal junction was 68%. This appears to correlate to where Kuttler indicated the minor constriction to be located. These devices seem to offer a unique method to locate the apical constriction and thus to ensure proper working length while reducing ionizing radiation.

Aged↗
PubMed1991

A spectrophotometric analysis of dentinal leakage in the resected root.

The purpose of this study was to compare dye leakage in the dentin of resected and nonresected roots. Fifty-four single rooted extracted teeth were used. The two groups were subdivided into young, middle age, and old age samples. Each sample was biomechanically prepared in a standard fashion and obturated using lateral condensation with sealer and gutta-percha. All root surfaces were sealed with nail polish, leaving the apical portion exposed. The apical portion of the roots were placed in 2% methylene blue dye for 72 h, rinsed, and placed in 15 ml of 35% HNO3 for 72 h. The supernatant was analyzed at 640 nm using a visible light spectrophotometer. The amount of leakage was extrapolated from a standard linear regression curve constructed from the stock 2% methylene blue dye solution. The percentage of concentration leakage in all samples ranged from less than 0.0600 to 0.1658. It was concluded that there is a greater amount of leakage in resected versus nonresected extracted teeth. The data also suggest that older teeth exhibit less leakage than younger teeth.

Adult↗
PubMed1990

Anatomy of the root apex and its histologic changes with age.

There were 87 vital and 24 nonvital teeth for a total of 111 specimens from 47 patients. The specimens were prepared to a thickness of 500 microns with a Buehler Isomet Bone Saw. Distances were measured and recorded with a Bioquant II Image Analysis System. The mean age of the patients was 48.9 years. The median age was 52 years. The range was 51 years, with a maximum of 77 years and a minimum of 26 years. There is a positive correlation, which could not have occurred by chance, that as age increases the deviation and the width of the foramen opening both increase. This increase appears to be a result of apical cemental thickening that occurs as the patient ages. The tissue in the apical area seems to be capable of generating additional cementum as the tooth ages. The cementodentinal junction width, or most apical extent of the dentin, remains constant.

Adult↗
PubMed1990

Influence of the major and minor foramen diameters on apical electronic probe measurements.

There have been conflicting reports on the accuracy of electronic devices used for determining working length. The influence of the major and minor diameters on electronic probe measurements were evaluated to ascertain whether anatomical features of the apical portion of the canal might be responsible for these discrepancies. Forty-seven nonrestorable teeth selected from 22 patients were studied. Conventional access was made. A Kerr file was placed to a position 0.5 mm from the major foramen as registered by the Neosono-D apex locator. The electronic probe length was then measured. After the tooth was extracted, the file was fixed with autopolymerizing composite in the canal. A Buehler Isomet lapadary saw was used to prepare specimens to a thickness of 500 microns. A Bioquant II Image Analysis System was used to measure and record distances. It was found that as the width of the major foramen increased, the discrepancy between the electronic probe tip length induction and the actual position of the major foramen increased.

Dental Pulp Cavity↗