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Biomedical subjects

G R Hartwell

Publications and source records attributed to G R Hartwell.

At least 19 recordsLinked to original sources
PubMed2001

Obturation of a retained primary mandibular second molar using mineral trioxide aggregate: a case report.

This case report demonstrates Mineral Trioxide Aggregate obturation of the root canal system of a retained primary mandibular second molar where no succedaneous permanent tooth was present. The technique seemed to provide a biocompatible seal of the root canal system in this case. It is not recommended for obturation of primary teeth that are expected to exfoliate since it is anticipated that Mineral Trioxide Aggregate would be absorbed slowly, if at all.

Adult↗
PubMed2001

Effects of chlorhexidine gluconate as an endodontic irrigant on the apical seal: short-term results.

The aim of this study was to ascertain whether chlorhexidine gluconate (0.12%), used as an endodontic irrigating solution would affect the apical seal obtained when using three different root canal cements. One hundred extracted human single-canal teeth were divided into 9 experimental groups of 10 teeth each and a positive and negative group of 5 teeth each. The teeth were decoronated at the level of the cementoenamel junction, then accessed, instrumented to a Master Apical File #50, irrigated with either sterile saline, 5.25% NaOCl or 0.12% chlorhexidine gluconate, and dried using paper points. Obturation was accomplished using lateral condensation and 1 of 3 endodontic sealers: Roth's 811, AH26, or Sealapex. At 90 and 180 days after obturation apical leakage was measured using the fluid filtration method. Using the ANOVA test the results showed no significant difference in seal related to the irrigant at both the 90- and 180-day observation periods.

Analysis of Variance↗
PubMed2000

Frequency of second mesiobuccal canals in maxillary molars as determined by use of an operating microscope: a clinical study.

Operating microscopes have recently been introduced to facilitate treatment of surgical and nonsurgical endodontic cases. The aim of this study was to determine in an in vivo clinical study if the use of an operating microscope would increase the number of second mesiobuccal canals located and obturated in maxillary first and second molars. Two hundred maxillary first and second molars treated with the aid of a microscope were evaluated. The number of second mesiobuccal canals that could be negotiated and obturated within 4 mm of the apex was recorded. Thirty percent of all maxillary molars had a negotiable second mesiobuccal canal. Evaluated separately, 33.1% of the maxillary first molars and 24.3% of the second molars had a negotiable second mesiobuccal canal. Results indicated that use of a surgical microscope did not increase the number of second mesiobuccal canals located, compared with those reports where access preparations were modified and the microscope was not used.

Dental Pulp Cavity↗
PubMed1998

Microleakage of super-EBA with and without finishing as determined by the fluid filtration method.

Super-EBA (SEBA) has been used as a root-end filling material because of its superior sealing properties and clinical success. The purpose of this study was to evaluate whether finishing SEBA after it had set would affect the apical seal. Sixty-five extracted maxillary anterior teeth were instrumented and obturated with a single gutta-percha master cone. The root end was resected, and a 3 mm deep root-end preparation was made using ultrasonic tips. Teeth were randomly divided into three groups. Group 1 received SEBA and was finished with a 30-flute high-speed finishing bur. Group 2 received SEBA, which was cold-burnished with a ball burnisher. Temporary Endodontic Restorative Material was used as the negative control in group 3. Microleakage (microliter/min) was measured under 10 psi using the fluid filtration method at days 1, 7, 30, 90, and 180. SEBA/finished exhibited significant microleakage at day 1 when compared with the burnished group. The differences in leakage were not significant at any other time period.

Dental Leakage↗
PubMed1998

Evaluation of setting properties and retention characteristics of mineral trioxide aggregate when used as a furcation perforation repair material.

Furcation perforations were created in 32 extracted maxillary and mandibular molars. The perforations were prepared in the center of the pulp chamber floor parallel to the long axis of each tooth and a saline-moistened Gelfoam matrix was placed below the perforation to simulate a clinical condition. The teeth were randomly divided into four groups, and the perforations were all repaired with mineral trioxide aggregate (MTA) and then covered with either a wet or dry cotton pellet for 24 or 72 h. Instron testing was used to measure the force required to displace the material from the perforation. The force measurements showed that MTA resisted displacement at 72 h to a significantly greater level than at 24 h (p < 0.05). When slight displacement occurred at 24 h the material demonstrated the ability to re-establish resistance to dislodgement from the dentin wall. The presence of some moisture in the perforation during placement was advantageous in aiding adaptation of MTA to the walls of the perforation, but there was no significant difference in MTA retention when a wet or dry cotton pellet was placed in the pulp chamber during the setting time (p > 0.05).

Aluminum Compounds↗
PubMed1998

Comparison of debris extruded apically in straight canals: conventional filing versus profile .04 Taper series 29.

The purposes of this study were to determine quantitatively the amount of debris and irrigant forced in an apical direction, the frequency of apical plug development, and the time required to prepare canals when a step-back technique using K-files was compared with the .04 Taper system. Sixty-nine extracted teeth with straight canals were divided into four statistically similar groups. Two groups were instrumented either 1 mm short of the apical foramen or to the apical foramen with K-files. The other two groups were instrumented to the same levels using .04 Taper files. The extruded debris and irrigant were collected in preweighed vials. The weight of the debris and volume of irrigant extruded using both techniques were compared and analyzed using paired t test and one-way ANOVA. Tukey's Multiple Comparisons Procedure showed K-files used to the apical foramen extruded significantly more debris than the other three groups (p < 0.01). The .04 Taper files used 1 mm short extruded less debris than the other groups. Significantly more irrigant was extruded when filing was performed to the apical foramen (p < 0.007), regardless of the technique used. More apical plugs were created in teeth filed short of the apical foramen, but the difference between the two preparation techniques was not statistically significant. It took significantly less time to instrument canals with the .04 Taper system than with K-files (p < 0.002).

Analysis of Variance↗
PubMed1993

Healing of furcation perforations in primate teeth after repair with decalcified freeze-dried bone: a longitudinal study.

Furcation perforations were created in 18 maxillary and mandibular molars in three adult rhesus monkeys. The perforations were located in the center of the pulp chamber floor and were 1 mm in diameter and 3 mm in depth. Teflon was used as a negative control to cover the perforation site in three teeth and the bony defects in the other 15 teeth were filled with decalcified freeze-dried bone. At the end of the 6-month experimental period the gingival tissues were clinically healthy, there was normal sulcular probing depths around all teeth, and only one tooth demonstrated furcal bone loss, radiographically. The histological picture for the Teflon and decalcified freeze-dried bone groups was very similar. There was a layer of epithelium immediately beneath the perforation site and deep to this was fibrous connective tissue and bone. Chronic inflammation was present in the connective tissue of all 3 Teflon samples but in only 2 of the 15 decalcified freeze-dried bone samples. New bone formation was not observed in any of the samples.

Animals↗
PubMed1992

Modified endodontics for lengthy canals.

A review of the dental literature concerning lengths of maxillary cuspids and reports of cuspid gigantism are presented. Endodontic therapy in these cases requires variations and modifications in conventional therapy for successful treatment. A case report is presented which illustrates some of these treatment modifications.

Cuspid↗
PubMed1991

Detection and treatment of multiple canals in mandibular premolars.

The endodontic treatment of mandibular premolars may not be successful because of failure to recognize and/or treat multiple canals when they are present in these teeth. Factors such as an awareness of data pertaining to the number of canals, knowledge of canal morphology, correct radiographic interpretation, and tactile examination of canal walls are important in detecting the presence of multiple canals. These factors, as well as guidelines for subsequent canal preparation and obturation, are provided.

Adult↗
PubMed1991

Evaluation of size variation between endodontic finger spreaders and accessory gutta-percha cones.

The diameter of nine sizes of three brands of endodontic spreaders was measured at D1 and D16 and compared with corresponding sizes of six brands of accessory gutta-percha cones. Two evaluators independently measured 20 randomly selected samples of each size of finger spreader and accessory gutta-percha cone. A standardized method of measurement was used for all samples and the interrater reliability was found to be extremely high using this methodology. Results indicated that very few of the diameters corresponded when like sizes of finger spreaders and accessory gutta-percha cones were compared. We concluded that there is a need for standardization by the manufacturer of finger spreaders so that accessory gutta-percha cones will fit into the space created by corresponding sized finger spreaders.

Dental Instruments↗
PubMed1990

An in vitro evaluation of injectable thermoplasticized gutta-percha, glass ionomer, and amalgam when used as retrofilling materials.

An in vitro dye leakage study was performed to evaluate the sealing ability of the following retrofilling materials: high- and low-temperature injectable thermoplasticized gutta-percha with and without sealer, a glass ionomer cement, and amalgam with and without varnish. The roots of 105 extracted human maxillary anterior teeth were instrumented and obturated with single cones of gutta-percha and sealer. The apical 3 mm of the roots were then resected and 2-mm deep retrograde preparations were prepared. Each root was then randomly placed into one of seven groups and retrofilled with one of the test materials. After 72 h in India ink, the roots were cleared and evaluated for leakage using a stereomicroscope. Statistical analysis of the results indicated that injectable high-temperature gutta-percha without sealer demonstrated significantly more leakage than the other materials. There were no significant differences in leakage among the other evaluated materials.

Dental Amalgam↗
PubMed1990

An esthetic approach to vertical root extrusion in a patient with an anterior open bite: report of case.

A previous attempt to locate the root canal system in the maxillary left central incisor with a bur created a perforating root defect at the level of the alveolar crest. The patient received root canal therapy. Next, vertical root extrusion was chosen to expose sound tooth structure apical to the defect so that a crown could be constructed. With an anterior open bite, the natural crown was left intact and it was possible to position the anchor bar in an incisal and lingual position, maintaining esthetics for the patient during both the extrusive and stabilization phases of treatment.

Adult↗
PubMed1989

Evaluation of the controlled placement of injected thermoplasticized gutta-percha.

Ninety extracted human teeth with a single canal and a large patent foramen were obturated by one of three methods after placement of a master gutta-percha cone and sealer. The apical seals were evaluated by ink penetration. Statistical analysis of the results indicated that the group obturated with the high-temperature injected thermoplasticized technique (Obtura) had an apical seal comparable to the group obturated by lateral condensation. The group obturated with the low-temperature injected thermoplasticized technique (Ultrafil) produced an apical seal significantly better than the other two techniques.

Dental Leakage↗
PubMed1989

Stereomicroscopic evaluation of canal shape following hand, sonic, and ultrasonic instrumentation.

This study evaluated the root canal shape after using sonic, ultrasonic, and hand instrumentation on the mesial canals of extracted human mandibular first and second molars. One-hundred and five mesial roots were randomly divided into six experimental groups and one untreated control group of 15 roots each. The following instrumentation techniques were evaluated in the experimental groups: hand instrumentation with K-Flex files, sonic instrumentation with the Endostar 5, sonic instrumentation with the Sonic Air MM 3000, and ultrasonic instrumentation with the Cavi-Endo unit. Each technique was directly compared with each other. The mesial roots were instrumented alternating the techniques between the buccal and lingual canals in each group so that a direct comparison could be made. All canals were instrumented to a size corresponding to a #30 K-Flex file 1 mm from the anatomical apex. The roots were then sectioned perpendicular to the long axis so the apical and middle thirds could be evaluated with the stereomicroscope for canal shape. The control group was sectioned and examined without instrumentation. A significantly more regular shape was obtained at both levels with hand instrumentation than was obtained with either sonic or ultrasonic techniques. The comparisons between the sonic and ultrasonic techniques showed significantly better shapes were obtained with the Sonic Air MM 3000 instrument.

Dental Pulp Cavity↗
PubMed1989

A comparison of apical seal: chloroform versus eucalyptol-dipped gutta-percha obturation.

Three groups of extracted teeth were obturated using gutta-percha and lateral condensation. In one group the gutta-percha was dipped in chloroform before condensation. In a second a eucalyptol dip was used. No dip was used in the third group. A dye penetration study was done to compare leakage among the three groups. The teeth were cleared for viewing and measurements of dye penetration were made using a stereomicroscope. Statistical analysis using Kruskal-Wallis one-way analysis of variance of the results showed no significant difference among test groups at the 0.05 level.

Chloroform↗
PubMed1989

Does cold burnishing gutta-percha create a better apical seal?

This study investigated the seal created by cold burnishing the gutta-percha exposed after apical root resection of endodontically treated teeth. Sixty single-rooted extracted human teeth with a single straight canal were divided into four experimental groups of 15 teeth each. In two of the experimental groups the canals were instrumented and obturated well with laterally condensed gutta-percha and sealer. The remaining two groups were instrumented and poorly obturated with laterally condensed gutta-percha and sealer. The apical 2 mm of all the teeth were then resected and the effect of cold burnishing the exposed gutta-percha was investigated using a linear dye penetration technique. Under the condition of this study, cold burnishing gutta-percha after apical root resection of a well-obturated root canal resulted in a poorer apical seal than if no burnishing were performed. Cold burnishing the exposed gutta-percha after apical root resection of poorly obturated root canals improved the apical seal as compared with nonburnished poorly obturated canals.

Dental Leakage↗
PubMed1989

Leakage in vitro with high-temperature thermoplasticized gutta-percha, high copper amalgam, and warm gutta-percha when used as retrofilling materials.

An in vitro dye leakage study was performed to compare the sealing ability of high-temperature thermoplasticized gutta-percha, high copper amalgam, and warm gutta-percha when used as retrofilling materials. Forty-five extracted anterior teeth were obturated with gutta-percha, the apical 3 mm of the roots were resected, and 2-mm-deep retrograde preparations were prepared. The roots were then randomly placed into three groups and retrofilled with one of the experimental materials. After 72 h in India ink, the teeth were cleared and evaluated for leakage using a stereomicroscope. No leakage was evident in the three teeth used as negative controls. Complete leakage was noted in the three positive control teeth. Statistical analysis of the results showed that high-temperature thermoplasticized gutta-percha had significantly less leakage than did high copper amalgam.

Copper↗