Biomedical subjects

R N Weller

Publications and source records attributed to R N Weller.

At least 37 records · Page 2Linked to original sources

PubMed1995

In vitro radicular temperatures produced by injectable thermoplasticized gutta-percha.

In vitro temperatures produced in the root canal and on the root surface were measured simultaneously as heated gutta-percha was injected into the prepared canal. The canals were obturated with the Obtura II heated gutta-percha system with temperature settings of 160, 185, and 200 degrees C. The mean intracanal temperatures ranged from 40.21 to 57.24 degrees C, whereas the mean root surface temperatures were recorded from 37.22 to 41.90 degrees C for all three temperatures tested. The rise in temperature on the root surface was below the critical level of 10 degrees C and should not cause damage to the periodontal ligament.

Body Temperature↗

PubMed1994

In vitro temperatures produced by a new heated injectable gutta-percha system.

In vitro intracanal temperatures produced by the injection of high-temperature thermoplasticized gutta-percha were measured. Obturations of a standard root canal were performed using an Obtura II heated gutta-percha system at temperature settings of 160, 185, and 200 degrees C. There was an increase in the recorded temperatures in the root canal for all three temperature settings with the mean temperature range from 38.52 degrees C to 61.58 degrees C. The mean temperature of the empty heating chamber was also measured and was accurately indicated on the control unit. However, the mean temperature of the gutta-percha in the heating chamber was almost 20 degrees C cooler than expected at each of the three settings. Finally, there was more than a 100 degrees C decrease in the mean temperature of the extruded gutta-percha in relation to the temperature of the gutta-percha in the heating chamber. Several clinically relevant observations were noted. Each of these observations was related to the temperature setting of the Obtura II control unit.

Body Temperature↗

PubMed1993

Effect of smear layer removal on the diffusion of calcium hydroxide through radicular dentin.

Forty single-rooted teeth were sectioned transversely through the cementoenamel junction and instrumented to a size #50 K-Flex file at the working length by saline irrigation. Each root was placed in a dilution vial containing 10 ml of normal saline, and the pH and Ca2+ levels were recorded after 24 h. The roots in group 1 then received a final irrigation with 20 ml of normal saline. Group 2 received a final irrigation with 10 ml of 17% ethylenediaminetetraacetic acid followed by 10 ml of 5.25% NaOCl to remove the smear layer. Group 3 was irrigated in the same manner as group 2, but calcium hydroxide (CH) was placed into the root canal. Group 4 was irrigated with 20 ml of NaOCl, and CH was placed into the root canal. The pH and Ca2+ levels were recorded at 1, 3, 5, and 7 days. After 7 days a 3- x 3- x 1-mm external defect was created in the coronal one third of the root surface. The pH and Ca2+ levels were subsequently recorded at 1, 3, and 7 days. Groups 3 and 4 demonstrated significantly higher H+ and Ca2+ levels than did groups 1 and 2 three days after CH placement and at all subsequent intervals. Group 3 demonstrated significantly higher H+ and Ca2+ readings at some but not all intervals. The results demonstrated that CH diffuses from the root canal to the exterior surface of the root and that the removal of the smear layer may facilitate this diffusion.

Analysis of Variance↗

PubMed1992

Effect of mechanical versus thermal removal of gutta-percha on the quality of the apical seal following post space preparation.

The objective of this study was to compare the effects of a flame-heated endodontic plugger, an electrically-heated endodontic spreader, Peeso reamers, and GPX burs on the apical seal when gutta-percha was removed from the root canal for post space preparation. Eighty-nine human canines were instrumented and obturated with gutta-percha and sealer to a standardized working length of 15 mm. An 11-mm segment of gutta-percha was removed from the roots in each of the four experimental groups of 20 teeth to simulate post space preparation. The teeth were immersed in India ink for 7 days and rendered transparent. The extent of linear dye leakage was measured with a stereomicroscope. There was no statistically significant difference in linear dye leakage among any of the experimental groups when 4 mm of gutta-percha remained.

Dental Instruments↗

PubMed1992

The mental foramen: 2. Radiographic position in relation to the mandibular second premolar.

Seventy-five adult human mandibles were radiographed with a paralleling technique to determine the ability to visualize the mental foramen as well as its size and position. The foramen was seen on 75% of the horizontal periapical radiographs examined. When the foramen was not visualized, is was usually below the inferior edge of the film. The radiographic size of the foramen was smaller than the anatomical size previously reported. The position of the mental foramen was usually mesial and below the radiographic apex of the second premolar.

Adult↗

PubMed1992

In vitro intracanal temperatures produced during warm lateral condensation of Gutta-percha.

In vitro intracanal temperatures produced during the war lateral condensation of gutta-percha were measured using a computerized recording system that allowed repeated obturations of a root canal model. The obturations were performed using a Touch 'n Heat unit. Temperatures were recorded to an accuracy of a hundredth degree centigrade by 16 intracanal themocouples connected to the computerized measurement system. The highest intracanal temperature recorded was 114.51 degrees C at a power setting of 6, while the mean intracanal temperature increase above the average room temperature ranged from 8.18 to 65.05 degrees C. In addition, the spreader was not uniformly heated to the same temperature throughout its entire length. The hottest point on the spreader was located 5 mm from the tip.

Body Temperature↗

PubMed1992

The mental foramen: 3. Size and position on panoramic radiographs.

Panoramic radiographs were made of 75 dry, adult human mandibles. The size and position of the mental foramen in relation to the second premolar was determined. The mental foramen on panographic radiographs was slightly larger than reported on periapical radiographs. The average position of the foramen was mesial and below the radiographic apex of the tooth. Panoramic radiography may account for a distal shift of the foramen and a 23% increase in size of the mandibles examined.

Bicuspid↗

PubMed1992

Root canal configuration of the mandibular first premolar.

One hundred six human mandibular left and right first premolars, previously extracted due to nonrestorable caries, periodontal disease, or orthodontic reasons, were sectioned perpendicular to the long axis of the root starting at the cementoenamel junction. Three-millimeter sections were made with an ultrathin separating disc to the level of the anatomical apex. After 1 day in 5.25% NaOCl, each section was rinsed in phosphate-buffered saline, evaluated with a stereomicroscope, and photographed. The slides were projected and the shape of the canal, incidence of multiple canals, level of bifurcation, and any other variant anatomy were recorded. Seventy-six percent of the premolars demonstrated Type I canals and 24% contained Type IV. The shape of the canals was predominantly oval or round. An interesting finding was the number of C-shaped canals which were associated predominantly with Type IV canal systems. This occurred in 14% of the roots.

Bicuspid↗

PubMed1991

A 2-day decompression: a case report of a maxillary first molar.

A case report of a maxillary first molar is presented in which a drainage tube from a decompression procedure was removed 2 days following placement. The oral surgeon who removed the tube scheduled the patient for surgical enucleation of the large periapical lesion. The surgical appointment was subsequently cancelled and routine endodontic follow-up showed continued osseous repair at 3, 6, and 12 months. The decompression of a large periapical lesion is a conservative alternative to surgical enucleation.

Adult↗

PubMed1991

In vitro intracanal temperatures produced by low- and high-temperature thermoplasticized injectable Gutta-percha.

An in vitro computerized temperature measurement system was developed to measure intracanal temperatures produced by different heated gutta-percha obturation techniques. The temperatures produced by low- and high-temperature thermoplasticized injectable gutta-percha systems were recorded and compared in this investigation. The mean intrachamber temperature of the Obtura syringe was 178.68 degrees C. The mean temperature of the Ultrafil heater was 93.06 degrees C. The mean temperature of the extruded gutta-percha was 137.81 degrees C from the Obtura syringe and 62.88 degrees C from the Ultrafil cannule. The intracanal temperature of the gutta-percha recorded for both systems showed that the gutta-percha cools rapidly after injection into the canal.

Gutta-Percha↗

PubMed1991

A new model system for measuring intracanal temperatures.

A new model system was developed which allows intracanal temperature measurements to be recorded during repeated obturations of a human tooth root canal. A human central incisor was embedded in clear orthodontic resin and sectioned longitudinally. Sixteen thermocouples were secured at 2-mm intervals along two surfaces of the root canal. The thermocouples were connected to a computerized temperature recording system to measure intracanal temperatures produced by high-temperature thermoplasticized injectable gutta-percha. The system was capable of recording 16 simultaneous temperatures every second with an accuracy of a hundredth degree centigrade. There was a linear increase in the recorded temperatures in the root canal. However, the actual temperatures were lower than expected.

Body Temperature↗

PubMed1991

A comparison of thermoplasticized injectable gutta-percha obturation techniques.

This study compared the quality of obturation of high- and low-temperature thermoplasticized injectable gutta-percha techniques and standard lateral condensation. A new model system was developed to more closely simulate the clinical environment. All obturations were performed in this same model which allowed direct comparisons between the different techniques. The resultant mass of gutta-percha was visually examined and graded for each obturation. Statistical analysis of the results indicated that both thermoplasticized injectable techniques were significantly better than lateral condensation. There was no significant difference between either of the thermoplastic obturation techniques.

Analysis of Variance↗

PubMed1990

The mental foramen: 1. Size, orientation, and positional relationship to the mandibular second premolar.

Seventy-five adult human mandibles were examined to determine the size, orientation, and position of the mental foramen. The average size of the foramen was found to be larger on the left side of the mandible and its usual direction of exit was in a posterior-superior direction. The most common location of the mental foramen was inferior to the crown of the second premolar and approximately 60% of the distance from the buccal cusp tip of that tooth to the inferior border of the mandible.

Adult↗

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 evaluation of the apical seal produced by lateral and warm lateral condensation techniques.

The apical sealing ability of a standard lateral condensation technique was compared with that of two different warm lateral condensation techniques. Sixty extracted human teeth with single canals were instrumented and randomly placed into three groups. Four additional teeth were used as controls. Each group of 20 teeth was obturated with gutta-percha and sealer using one of the three techniques. After 7 days in India ink, the teeth were cleared and the linear extent of ink penetration was measured with a stereomicroscope. No leakage was evident in the two negative controls whereas complete leakage was present in the two positive control teeth. Statistical analysis of the results showed no significant difference in leakage between the experimental groups.

Dental Leakage↗

PubMed1990

Standardized technique for linear dye leakage studies: immediate versus delayed immersion times.

A dye leakage study was performed in vitro to compare the extent of leakage into root canals obturated with gutta-percha following immediate versus delayed immersion in Indian ink. Sixty extracted human teeth with single canals were instrumented and obturated with gutta-percha and sealer. Each group of 20 teeth was then immersed in the ink either immediately after obturation or after a delay of 1 or 7 days. After 7 days in Indian ink, the teeth were rendered transparent by clearing, and the linear extent of ink penetration was measured with a stereomicroscope. Complete leakage was observed in the two positive control teeth, and no leakage was evident in the two negative controls. Statistical analysis of the results indicated that there was no significant difference in leakage between the three experimental groups.

Analysis of Variance↗

PubMed1990

Update on antibiotics for the endodontic practice.

The increasing reports of antibiotic-resistant bacteria and the introduction of new antibiotics have resulted in a change in prescribing antibiotics in many dental offices. The purpose of this article is to provide a rationale for selecting the appropriate antibiotic for odontogenic infections and to review the basic concepts of antibiotic therapy.

Anti-Bacterial Agents↗

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↗