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PubMed1995

Effect of dentin preparation and acid etching on the sealing ability of glass ionomer and composite resin when used to repair furcation perforations over plaster of Paris barriers.

Access openings and furcation perforations were prepared in 60 human extracted teeth and randomly divided into four equal groups. Plaster of Paris barriers were created in all perforations. The defects were obturated using either glass ionomer or composite resin with or without acid etching of the dentin. The pulp chambers and access openings were filled with composite resin. After immersion in 2% methylene blue solution for 2 weeks, the teeth were sectioned longitudinally and dye penetration was measured under a stereomicroscope using the NIH Image 1.47 Macintosh program. The results indicated that light-cured glass ionomer provided a significantly better seal than did the light-cured composite resin with or without dentin preparation and acid etching. The glass ionomer allowed significantly less dye penetration when used on etched dentin than it did on nonetched dentin.

Acid Etching, Dental↗
PubMed1995

Radiovisiography versus conventional radiography for detection of small instruments in endodontic length determination. II. In vivo evaluation.

Radiovisiography was compared clinically to conventional D-speed and E-speed radiographs viewed with X 2 magnification using the mesiobuccal root of maxillary molars of 22 patients. Clarity of size 8 and 10 endodontic file tips in relation to the radiographic apex was the object of comparison. Five images of radovisiography, (original, enhanced, negative-to-positive mode), were compared to D-speed and E-speed radiographs. D-speed radiographs were also compared to E-speed radiographs. D-speed radiographs were statistically superior to all five radiovisiography images. Four of the radiovisiography images were equivalent to E-speed radiographs. D-speed radiographs provided superior recognition of small file tips when compared to E-speed radiographs 100% of the time. Accurate identification of the small file tips was achieved on 95% of D-speed and 70% of E-speed radiographs. With radiovisiography, identification was achieved on 95% of the zoom images in the negative-to-positive mode, 86% of enhanced, 82% of standard zoom, and 77% of the images in negative-to-positive conversion.

Adult↗
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↗
PubMed1995

Evaluation of root thickness in curved canals after flaring.

Root thickness in the mesial canals of lower first and second molars was compared before and after flaring by using a muffle system. Gates Glidden burs or M-Series Canal Openers were used with either a straight up-and-down motion or with an anticurvature motion. It was found that Gates Glidden burs used straight up and down removed statistically more dentin at the level of the furcation than Canal Openers used straight up and down or in an anticurvature fashion. At a level 2 mm apical to the furcation, Gates Glidden burs used in an anticurvature fashion removed statistically more dentin than any other method tested.

Analysis of Variance↗
PubMed1975

The effect of preparation procedures on original canal shape and on apical foramen shape.

With the use of clear casting resin, simulated curved canals were created so that canal preparation procedures could be directly visualized and compared. Regardless of the type of enlarging instrument or the technique used, undesirable characteristics were produced in all preparations that would make canal filling difficult. To modify the typical preparations, alteration of the enlarging flutes, use of rasping rather than rotation of the instruments, and a flaring technique are recommended.

Dental Pulp Cavity↗
PubMed1996

An in vitro comparison of the Excalibur handpiece and hand instrumentation in curved root canals.

Root canal preparation may be the most technique-sensitive and labor-intensive procedure in endodontic therapy. Many automatic handpieces and machine-driven devices have been marketed to expedite this procedure. Excalibur is one such handpiece. The purpose of this study was to compare the Excalibur hand piece with traditional K-files for their effectiveness in shaping curved root canals. A total of 24 standardized canals in extracted human mandibular molars were randomly divided into two groups. They were instrumented either with Excalibur according to the manufacturer's instructions or manually using the step-down technique. The cross-sectional shapes of the root canal at the apical, midroot, and coronal levels were digitized before and after instrumentation. Image analyzer software was used to compare the images. The results showed that the methods removed similar amount of dentin at all three levels. Although the Excalibur handpiece had a slight tendency to straighten the canal more than hand instrumentation, the difference was not significant. Strip-perforation occurred in three specimens in the Excalibur group, but none in the manual group. There was no separation of instrument throughout the experiment.

Dental High-Speed Equipment↗
PubMed1997

Obturation of root canals in vivo with a new vacuum technique.

It was demonstrated in vitro that it is possible to achieve obturation of the root canal system with a system utilizing a reduced pressure of 15 hPa (15 mbar). The purpose of this study was to develop a procedure to reach a vacuum of at least 15 hPa within root canals in vivo. It was also determined if root canals could be obturated in daily practice with this vacuum technique. After hand instrumentation of the root canals a tooth was prepared for obturation of the canals with the new technique by obtaining a tightly fitting attachment to a vacuum pump. The result showed that it was possible in vivo to reach reduced absolute pressures of 10 hPa in roots and to fill the root canal system with the new system.

Dental Pulp Cavity↗
PubMed1997

Evaluation for cracks associated with ultrasonic root-end preparation of gutta-percha filled canals.

Many clinicians use ultrasonics for root-end preparations. The purpose of this study was to evaluate resected root-end surfaces of bilaterally matched human teeth for cracks before and after ultrasonic root-end preparation. Twenty matched pairs of extracted single rooted teeth were divided into two experimental groups. In group 1, root-end resection was performed on uninstrumented teeth. In group 2, root-end resection was performed after the canals were instrumented and filled with gutta-percha. All teeth in both groups received root-end preparations using ultrasonic instrumentation at low power. Two examiners evaluated the root-ends after root-end resection and again after root-end preparation using zoom magnification of 20x to 63x. The number, types, and location of cracks were mapped. There were no significant differences when gutta-percha filled roots were compared to uninstrumented roots with regard to the number or type of cracks after root-end resection or root-end preparation. In addition, there were no significant differences in the number or type of cracks following root resection and ultrasonic root-end preparation when compared to teeth with root resection alone.

Analysis of Variance↗
PubMed1998

Residual dentin thickness in mandibular premolars prepared with hand and rotatory instruments.

The residual dentin thickness in the coronal part of root canals of mandibular premolars after stepback preparation and flaring with Gates Glidden (GG) drills was assessed sequentially in a newly designed muffle device. Twelve extracted teeth were embedded in clear polyester resin, sectioned horizontally (1, 3, and 5 mm apically to the cementoenamel junction), and reassembled in the muffle device. The sequence of canal preparation was K-files to #40, then GG-2 and GG-4. After each procedure, the slices were separated and residual dentin thickness measured by a toolmaker microscope in four directions (buccal, lingual, distal, and mesial) and reassembled in the muffle device. Statistical analysis by three-way analysis of variance with repeated measures was undertaken. The difference in residual dentin thickness was highly significant with regard to instrument (control, K-40, GG-2, GG-4; p < 0.0001), slice (upper, middle, and lower; p < 0.0003), and direction (B, L, M, and D; p < 0.001). In each slice, the width of the mesial side was similar to the distal side, as was the buccal to the lingual sides. Reduction of residual dentin thickness in the mesiodistal direction, from the unprepared upper slice to the GG-4 prepared lower slice, was appreciably greater (35%) than in the buccolingual direction (5%).

Analysis of Variance↗
PubMed1998

A new muffle model system to study root canal morphology and instrumentation techniques.

A new muffle model system is presented using the principle of internal indexing. The system is composed of a metal stand, four pins, and a single Teflon mold that is used for the investment of all teeth. This system is very precise, reproducible, and versatile. The sectioned specimens can easily be stored assembled, as opposed to previous systems that rely on external indexing.

Dental Pulp Cavity↗
PubMed1998

In vitro study of a Nd:YAP laser in endodontic retreatment.

Nd:YAP laser is a dental laser with a 1340 nm wavelength. The laser beam is carried by a 200 to 300 microns fiberoptic and is suitable for endodontic therapy. We used the Nd:YAP laser in an in vitro experiment to study its effectiveness in endodontic retreatment. Temperature measurements and irradiation parameters were first defined. Then Nd:YAP laser irradiation was used, alone or in combination with hand instruments, to remove various canal sealers and broken instruments. Clinical parameters were monitored and scanning electron microscopic observations were conducted. When used at 200 mJ--with a pulse duration of 150 ms, an exposure time of 1 s and a frequency of 10 Hz--Nd:YAP laser preserved the dentinal walls of the root canal and enabled root canal retreatment without thermic elevation harming periodontal tissue. It is concluded that, in combination with hand instruments, the Nd:YAP laser is an effective device for root canal preparation in endodontic retreatment.

Dental Pulp Cavity↗
PubMed1998

A comparison of curved canal transportation with balanced force versus lightspeed.

The Flex-R file was compared with the Lightspeed nickel-titanium file in respect to canal center movement and final canal area after instrumentation. Thirty-eight root canals in extracted human molars were divided into two equal groups of 19, in all of which the angle of curvature ranged from 20 to 35 degrees. After mounting in a mold, each root was sectioned at two locations, providing an apical and coronal section. Pre- and postinstrumentation 35 mm photographic slides of each section were projected, traced, and then scanned into a computer. From these computerized pre- and postinstrumentation images, the movement of the canal center and the area of each canal were computed at both the apical and coronal sections. Results showed significant difference in the apical canal center movement and postinstrumentation area with the Lightspeed yielding smaller values in both cases. Coronally, the Flex-R Lightspeed instruments demonstrated no significant difference in canal movement or postinstrumentation area. No significant correlation was found between the angle of root curvature and canal movement or the angle of root curvature and postinstrumentation canal area.

Dental Instruments↗
PubMed1999

An in vitro comparison of two modern apex locators.

Two apex locators were compared regarding their ability to accurately locate the apical constriction in the presence of various canal fluids at different meter readings. Forty-one root canals were filled with 1% NaOCl, 3% H2O2, and 0.9% NaCl, respectively. Electronic working length (EWL) measurements were recorded with the apex locators Root ZX (meter readings: "Apex", "0.5", and "1") and Apit (meter readings: "Apex" and "3"). The deviation of the EWL from the apical constriction was determined. The proportion of measurements within +/- 0.5 mm of the apical constriction ranged between 0.76 and 0.85 for Root ZX at the meter readings "Apex" and "0.5," regardless of the canal contents. Apit consistently displayed shorter measurement values than Root ZX and reached the highest proportions at the meter reading "Apex": 0.59 (1% NaOCl), 0.61 (3% H2O2), and 0.68 (0.9% NaCl). In the presence of NaOCl, Root ZX provides the more accurate EWL measurements at the meter reading "0.5" and "Apex."

Dental Instruments↗
PubMed1999

Effect of preflaring on Root ZX apex locators.

The Root ZX apex locator is an example of a generation of apex locators that identify the terminus of the canal by measuring a ratio between two electrical impedances. Studies have shown this device to have a high degree of accuracy. However, the manufacturer warns that the performance of these devices is limited by the presence of calcifications and dentinal shaving obstructions. An in vitro study was designed to determine if preflaring of canals would facilitate the passage of files to the apical foramen by eliminating cervical interferences and to see what effect this would have on the performance of the Root ZX apex locator. Thirty-two canals were divided into two groups. Group 1 was not manipulated before use of the Root ZX apex locator and served as control. In group 2, the canals were preflared before the use of the Root Zx apex locator. The working length files were secured in place and measured with the linear measurement tool used by the Visilog 5 imaging program. Results of this study suggest that preflaring of canals will allow working length files to more consistently reach the apical foramen (p = 0.015), which in turn increases the efficacy of the Root ZX apex locator.

Dental Instruments↗
PubMed1999

Root deformation during root-end preparation.

Ultrasonic root-end preparation techniques have recently been introduced and revolutionized the field of endodontic surgery. However, several reports claimed that there was an increasing incidence of crack formation after ultrasonic root-end preparation. As yet, little work has focused on the root deformation during root-end preparation. Thus, the purpose of this investigation was to measure the amount of root deformation during root-end preparation with the use of microhandpiece and ultrasonic systems by using strain gauge methods, and simultaneously to detect any cracks with the aid of the stereomicroscope, stain, and an image processing system. The results demonstrated the ultrasonic instrumentation produced significantly greater strain on average than that generated with the microhandpiece system. From the viewpoint of fracture, any technique that could diminish the strain on the root would decrease the likelihood of fracture; however, no crack was observed on any resected surface of roots in this study.

Dental Instruments↗
PubMed1999

Apical canal diameter in the first upper molar at various ages.

The shape of root canals cross-sectioned through their roots at 2 mm from their apices and its correlation with the D0 diameter of endodontic instruments was evaluated in 40 first upper molars. The molars were grouped according to age: under 13 yr (children), 18 to 20 yr (adolescents), 30 to 40 yr (adults), and over 50 yr. Evaluation of the root canal diameters revealed that the shapes were predominantly circular in the palatal canal, mostly flat in the mesiobuccal canal, and circular or flat in equal proportions in the distobuccal root. Age does not seem to affect the shape of the canals. Narrowing with age was statistically significant (p < 0.05) for palatal and mesiobuccal canals only. Correlation between the maximum diameter of the canals and the instruments was varied. Even in old age, diameters were observed that would require instruments of a size that would be impossible to use, because one internal diameter would exceed the root's external diameter in a different direction (i.e. intimal buccolingual diameter of #80 and external mesiodistal diameter of #70).

Adolescent↗
PubMed1996

Thermographic assessment of dentine pin placement.

OBJECTIVE: This in-vitro study aimed to examine the change in surface temperature induced by the actions of drills for the placement of dentine pins. METHODS: Ten decoronated extracted premolar teeth were embedded by the apical tip of their roots in orthoresin. They were held in a bench vice and allowed to reach the ambient temperature of 24 degrees C. A thermal imaging camera, Agema Thermovision 900 series, was positioned 0.05 m perpendicular to the decoronated surface. Sequential recording of a series of images was stored at a rate of three per second during each stage of the pin placement procedure. This included a pilot drill, a channel cutting drill and the pin placement. All pins were 0.675 mm diameter x 2 mm in length and were placed 1 mm from the amelo-dentinal junction using a Kavo handpiece rotating at 4000 rpm. RESULTS: The mean baseline temperature for the thermally stabilized teeth was 23.9 degrees C. The action of the round pilot drill changed the temperature from baseline by 25 degrees C. The action of the channel drill generated the greatest heat, with a mean maximum temperature recorded during these procedures of 94 degrees C +/- 9 degrees C. The pilot drill produced a mean change from baseline of 31.3 degrees C +/- 17.7 degrees C during pin placement. CONCLUSIONS: The placement of dentine pins produced a high temperature increase on the surface of the dentine. All stages of pin placement gave rise to an increased temperature, but this was maximal with the channel drill. Further studies are required to determine whether these surfaces temperatures are transferred to the pulpal chamber.

Body Temperature↗
PubMed1998

Psychological effects of aesthetic dental treatment.

OBJECTIVE: To demonstrate that aesthetic restorative dental treatment, using the porcelain laminate veneer, has a positive effect on the self-esteem of a patient. METHODS: A study group of 17 patients, unhappy with their dental appearance, were assessed psychologically at the pre-operative, immediate post operative and 6 month review stages. Porcelain laminate veneer restorations were used to improve the dental aesthetics for the patients in the study group. A comparison group of 27 subjects, without a dental appearance problem, were also psychologically assessed at comparable intervals. The assessments included Cattell's 16PF Personality Inventory, a Body-Esteem index, a computer administered version of the Repertory Grid technique and semi-structured interviews. RESULTS: The results showed that there were no significant differences between the study and comparison groups on any first or second-order factor of the 16PF. However, highly significant changes in a positive direction (p < 0.005) were observed in the study group in responses to a Body-Esteem questionnaire at each stage in the procedure. Comparison group changes were not significant. Repertory Grid analyses showed a significant overall convergence in the study group compared with the comparison group. There were also significant positive shifts amongst the study group in the normalised ratings of "self' on several of the constructs. Interviews confirmed the Repertory Grid findings. CONCLUSIONS: The study shows that aesthetic restorative treatment has a positive effect on patients' self-esteem.

Adult↗